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Most of the newer forms of carbon materials being demonstrated as potential anodes for lithium-ion batteries suffer a serious drawback in terms of their commercial perspectives due to their failure in the retention of a flat plateau in the charging/discharging profile. Here we present a facile and low-cost approach for the fabrication of solvent-free, binder-free anode material for the practical usage. A filter paper was coated with graphite using a pencil lead followed by pyrolysis (PyPF) and tested for its electrochemical performance. Galvanostatic charge/discharge experiments as carried out in half-cell configuration exhibited a specific capacity of 342 mAhg−1 with a constant plateau at 156 mAg−1 with 98% coulombic efficiency. This clearly shows the potential and competency of the material to be an inexpensive commercial anode. The role of graphite coating on filter paper was clearly manifested in the comparative studies with only pyrolyzed filter paper. Furthermore, full cell studies were performed using PyPF as anode and carbon coated LiFePO 4 as a cathode. A specific capacity of 120 mAhg−1 at C/5 rate with 141 WhKg−1 energy density with the retention of constant plateau and minimal polarization further emphasize the proficiency of PyPF as an anode for a commercial lithium-ion battery. Image 1 • An eco-friendly, binder-free and freestanding anode is developed for practical lithium ion battery. • Favorable plateau in the charge/discharge profile with minimal polarization is obtained. • A small quantity of graphitic carbon derived from pencil lead remarkably engender excellent charge/discharge profile. • Full cell study puts that this anode in scope of commercial lithium ion batteries. [ABSTRACT FROM AUTHOR]

Porous 3-D current collectors have been shown to be the primary choice in replacing classical 2D aluminum foil in applicable developments, especially those using carbon-based current collectors. In this study, we investigated the impact of using a non-woven carbon (NWC) based current collector for sulfur electrodes, in terms of performance and practical use in a commercial battery, keeping in mind the simplicity of electrode preparation method. The benefits of using NWC as a 3D current collector include high sulfur utilization for even highly loaded electrodes, lower polarization, and the provision of an efficient electrolyte reservoir. High discharge capacities up to ∼1200 mAh g −1 can be obtained at moderate C-rates, with relatively good capacity retention (<1% loss per cycle) and practical loadings as high as 8 mAh cm −2 . [ABSTRACT FROM AUTHOR]

Abstract In this article, a flexible free-standing MoS 2 based paper-electrode for lithium-ion batteries (LIBs) was assembled according to a solution-based papermaking process and subsequent in situ carbonization. The ultrathin MoS 2 nanosheets as active materials were efficiently exfoliated from bulk counterparts using TEMPO-oxidized cellulose nanofibrils (CNF) as assistant agents. Meanwhile, the oxidized CNF was utilized both as biobased binder and fibrous skeletons for the fabrication of hierarchical MoS 2 hybrid films. The MoS 2 based nanoarchitectures were finally achieved with carbon nanotubes (CNTs) as conductive fillers and further in situ carbonized under argon atmospheres. The in situ carbonization improved the electrical conductivity and specific surface area dramatically. The flexible paper-electrode assembled with ultrathin MoS 2 nanosheets, carbonized CNF (C-CNF) and CNTs exhibited enhanced performance with a high specific capacity, nice rate capability, and long time cycling stability. The carbonized MoS 2 /CNF/CNTs hybrid film can directly act as an ideal paper-electrode for LIBs without using traditional metallic current collector makes it appropriate for the next-generation flexible/wearable electronics in future. Graphical abstract Carbonized MoS 2 nanosheets/cellulose nanofibrils hybrid films with enhanced conductivity can be directly used as ideal paper-electrode for LIBs without metallic current collectors. Image 1 [ABSTRACT FROM AUTHOR]

Cellulose paper-based energy storage devices have spurred significantly intrinsic advantages compared with the traditional batteries due to environmental benignity, recyclability and easy processing. In this work, the binary functional materials, which contains linear N-doped carbon nanotube (N-CNT, one-dimensional) and spherical C-coated MoS 2 (MoS 2 @C, zero-dimensional), are embedded into the porous recycled paper (RP, two-dimensional) derived from wastepaper via a facile and low-cost vacuum filtration method, and then the N-CNT/MoS 2 @C/RP film (N-M-RP film) featuring a unique compacted “point-line-plane” structure is obtained. In favor of the synergistic effect of high-conductive N-CNT, high-capacity MoS 2 @C and porous RP network, the prepared freestanding N-M-RP film presents a high strength of 35.2 MPa and a comparably low sheet resistance of 127.39 Ω sq −1 , and as an anode material for LIBs, the N-M-R film delivers a high reversible capacity, good cycling performance, superior rate capability and excellent electrochemical kinetics. Besides, the synergistic effect of “point-line-plane” structure on the improved electrochemical performances is also investigated. All the results indicate that the N-M-RP film comprised of 0D-1D-2D materials could be a potential candidate as a freestanding anode for LIBs. [ABSTRACT FROM AUTHOR]

• Variation of Young's modulus of Ga in the process of discharge (lithiation) was measured. • Self-healing ability of EGaIn to automatic repair the cracks resulted from charge/discharge. • The CNF/CNT@EGaIn NPs anode is free-standing, flexible and binder-free. Gallium-based liquid metals are considered as potential anode materials for lithium-ion batteries owing to their self-healing, non-poisonous advantages, as well as high theoretical capacity. However, due to the alloying/dealloying reaction mechanism to store lithium, Gallium-based alloys face huge volume change resulted in poor cycle life. Furthermore, the poor wettability of liquid metals on many kinds of substrates (carbon materials, stainless steel, etc.) and their strong ability to form alloys with many metallic current collectors (Cu, Al foil) make them hard to be designed into electrode with excellent electrochemical performance. One objective of this paper is to investigate Young's modulus of Ga discharged to different cut-off potentials, in order to gain a further understanding of mechanical property attenuation of Ga in the process of lithiation. Moreover, a three-dimensional (3D) free-standing electrode is fabricated by confining Ga-based liquid metal, EGaIn, in the matrix of carbon nanofibers/carbon nanotubes paper (CNF/CNT@EGaIn NPs). The network structure provides effective pathways for electrons and ions, as well as enough space to contain the volume expansion of EGaIn. The dense CNT layer plays a further role on preventing EGaIn from shedding of the conductive substrates. Obtained CNF/CNT@EGaIn NPs exhibits a good ionic/electronic conductivity and mechanical stability, delivers capacity of 351 mAh g−1 at 1.6 A g−1 and remains a reversible capacity of ∼420 mAh g−1 after 100 cycles at 800 mA g−1. This work could provide valuable insights into the development of Ga-based liquid metal anodes. [ABSTRACT FROM AUTHOR]

Developing scalable, simple and low-cost synthesis approach for Si nanoparticles and fabricating Si/carbon composites with specific microstructure to improve the Li storage ability are of great significance for practical application of Si-based Li-ion battery anode. In this report, we employed a facile method to synthesize Si nanoparticles via acid-etching Al-Si alloy powder. The etching process was fully investigated. The as-synthesized Si nanoparticles (∼10 nm) were further embedded into graphene sheets to form a flexible, free-standing paper with “sandwich-like” structure. The Si/graphene paper was directly applied as anode for Li-ion batteries without adding any binder and conductive additive. The graphene sheets not only increase the conductivity of Si material, but also function as a flexible scaffold for strains/stresses release and volume expansion during charge/discharge cycling process, resulting in much higher cycling stability (1500 mAh g −1 after 100 cycles at a current density of 100 mA g −1 with Coulombic efficiency >99%) compared to the native Si nanoparticles. It provides a scalable Si nanoparticles synthesis approach and a promising high-performance Si/graphene anode material. [ABSTRACT FROM AUTHOR]

Graphene paper that exhibits an excellent stabilized capacity, as high as 1300 mAh g-1 at a current rate of 60 mA g-1, as a lithium ion battery anode is fabricated and evaluated. The few-layer graphene used to make the graphene paper is prepared via the thermal reduction of graphite oxide. The graphene is then modified by a novel method utilizing inherent defects, namely epoxy groups, on the graphene as active sites for a reaction with methanol, 1-butanol, 1-hexanol, and 1-octanol. The density values and X-ray diffraction patterns obtained for the graphene paper demonstrate that the alkyl brushes on the graphene sheets expand the d-spacing and hinder close restacking of the sheets, thereby inducing the formation of extra cavities within the paper. This loose packing due to the alkyl brushes increases sensitively as the alkyl chain length of the alcohol becomes longer. The lithium ion insertion capacity of a graphene paper electrode at the first cycle also increases with the alkyl chain length. However, fading of the capacity at early charge/discharge cycles is accelerated by the modification process because of electrolyte penetration into the gallery and the acceleration of protective solid electrolyte interface film formation due to looser packing. The paper composed of graphene modified with 1-butanol rather than shorter or longer alcohols exhibits the best reversible storage capacity, more than two-fold higher when compared to that of pristine graphene paper, due to a compromise between two conflicting effects on the reversible storage capacity by long alkyl brushes. The tensile properties and electrical conductivity of the graphene papers are also examined. [ABSTRACT FROM AUTHOR]

Abstract: This paper focuses on an understanding of the influence of paper thickness on the electrochemical performances of graphene papers as an anode for lithium ion batteries. Three types of graphene papers, with thickness of ∼1.5, 3 and 10μm, respectively, were fabricated by vacuum-assisted filtration of reduced graphene nanosheets suspended in water. These papers deliver evidently different lithium storage capacities, with thinner papers always outperform thicker ones. The 1.5μm paper gives rise to initial reversible specific capacities (the first 10 cycles) of ∼200mAhg−1 at a current density of 100mAg−1, while the 10μm paper only presents ∼80mAhg−1 at a current density of 50mAg−1. After 100 cycles, a specific capacity of ∼180mAhg−1 is retained for the 1.5μm paper; in contrast, only ∼65mAhg−1 remains for the 10μm paper. The capacity decline with the paper thickness is associated with the dense restacking of graphene nanosheets and a large aspect ratio of the paper. The effective Li+ diffusion distance in graphene paper is mainly controlled by the thickness of the paper, and the diffusion proceeds mainly in in-plane direction, cross plane diffusion is restrained. As such, the effective contact of graphene nanosheets with electrolyte is limited and the efficiency of carbon utilization is very low in the thick papers. [Copyright &y& Elsevier]

Tin oxide/Multi Walled Carbon nano tube nanocomposite (SnO 2 /MWCNT) is synthesized using ethylene glycol mediated industrially viable simple process. Binder free, self-supporting and flexible SnO 2 /MWCNT nanocomposite paper has been prepared by employing the vacuum filtration technique. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy (RS), and thermal gravimetric analysis (TGA) to evaluate the structure of anode and tested for its performance in a Lithium rechargeable cell. Electrochemical measurements demonstrate that the SnO 2 /MWCNT composite paper anode with 30% of SnO 2 by weight delivers a specific discharge capacity of ∼420 mAh g −1 up to the investigated 50 cycles at a current density of 100 mA g −1 which is ∼200 % increase in capacity as compared to pristine MWCNT anode tested under similar conditions. The application of the developed anode is demonstrated by fabricating a lithium ion pouch cell. [ABSTRACT FROM AUTHOR]

Abstract: Rice paper (RP) is thermally carbonized in nitrogen to prepare three-dimensionally porous carbon films, which are used for the first time as both a free-standing active anode material and a current collector of a cathode (LiFePO4 here) for lithium-ion batteries. The latter is fabricated through a one-step co-sintering of a Li–Fe–P–O precursor top layer supported on the rice paper. The rate and cycling performances of both these electrodes are found to be rather good or even better than the traditional electrodes due to the three-dimensionally porous structure of the RP-derived carbon. We also design and fabricate an RP-based full cell constructed with the above mentioned anode and cathode together with an RP membrane as the separator. Without using traditional metallic current collectors and separator membranes, such a cell exhibits reversible cycling performance. [Copyright &y& Elsevier]

Abstract: Nano-Si/(multi-wall carbon nanotube) (Si/MWCNT) composite paper was prepared as flexible electrode for lithium ion batteries by a simple filtration method using sodium carboxymethyl cellulose (CMC) as a dispersing/binding agent, followed by a thermal sintering process. Scanning electron microscopy (SEM) showed that nanosized Si particles were dispersed homogeneously and intertwined by the MWCNT throughout the whole paper electrode. After thermal sintering, Si/MWCNT paper electrode exhibited a significantly improved flexibility with a high Si content of 35.6wt% as compared with before sintering, and retained a specific capacity of 942mAhg−1 after 30 cycles with a capacity fade of 0.46%/cycle. [Copyright &y& Elsevier]

Here, controlled growth of vertically aligned carbon nanotubes (VACNTs) on free-standing porous activated reduced graphene oxide (a-rGO) paper was fabricated using plasma-enhanced chemical vapor deposition method. The electrochemical performance of prepared film was investigated to provide effective electrode for 3D flexible high-performance lithium-ion batteries (LIBs) and supercapacitors. The results revealed that the prepared electrode exhibited a high specific capacitance of 347 F/g at 0.5 A/g in 1 M KOH electrolyte, 60% more than non-activated rGO-paper (218 F/g). The VACNTs on a-rGO have increased the accessible surface area and acted as efficient electrical conducting paths, which improved the power density. The free-standing flexible supercapacitor fabricated using such a film exhibited a sufficient electrochemical behaviour with high power density of 407 kW kg−1 at 5 Wh.kg−1 at a current density of 0.5 A/g. Since VACNTs with low sp2 hybridization defect lead to cyclic stability, suitable for high-performance LIB anodes. This 3D flexible anode electrode demonstrated a high initial discharge capacity of 1401 mAhg−1 with a large reversible charge capacity of 958 mAhg−1 at 150 mAg−1. The charge and discharge capacity have reached a stable value of 459 mAhg−1 after 100 cycles with a coulombic efficiency of ∼100% which is much higher than most carbon structures. Image 1 • Fabricating the activated reduced GO paper at lower temperatures of 80 and 400 °C. • Controllable growth of vertically aligned CNT on free-standing activated reduced GO. • Achieving the specific capacitance of 412 F/g and power density of 407 kW.kg-1. • The activating process is performed at a reduced temperature of 80 °C as opposed to reported works. It was also managed to reduce the activation temperature by half in the reduction process under the flow of 20 sccm of H 2 gas at 400 °C for 50 min. Additionally, the activation temperature is reduced to 400 °C, while in other studies the temperature ranges of 800–1000 °C has been reported. • Our developed 3D flexible full-carbon binder-free structure, has provided more ionic absorption and conduction routes. Consequently, more power at constant energy could be provided due to its porous substrates and grown VACNT. • Overall, the presented structure could be utilized as a high-performance high-power environment-friendly supercapacitor package, due to less consumed energy at the activation and reduction stages, thanks to its 3D structure and more energy at constant power. • Apart from supercapacitors, such flexible electrodes have been used to realize lithium ion batteries with excellent charge and discharge performance. A high initial discharge capacity of 1401 mAhg−1 with a large reversible charge capacity of 958 mAhg−1 at current density of 150 mAg−1 has been observed. • The charge and discharge capacity has reached a stable value of 459 mAhg−1 after 100 cycles which is much higher than reported Carbon-based electrodes. • In addition, other advantages of as-fabricated VACNT/a-rGO electrode are a much lower total electrode weight and a cheaper manufacturing cost made possible by removal of the binder and metallic substrate as in conventional electrodes. Moreover, all the methods applied in this study are applicable for industry utilizations and roll-to-roll thin film fabrication technology. [ABSTRACT FROM AUTHOR]

• A columnar liquid-crystalline triazine-based dendrimer has been incorporated as Li-ion battery anode. • The additional 1% carbon filler (CNT paper) in the triazine-based anode successfully boost the battery performance. • Systematical spectroscopic studies reveal that Li+ insertion in triazine and piperazine functional groups plays an important role in the Li+ storage mechanism. • The charge storage evaluation and kinetical studies unleashed the role of carbon filler on boosting capacitive contribution and accelerating Li+ transport. Owing to their highly tunable molecular structure and chemical stability, dendrimers consisting of triazine and piperazine moieties have been investigated. The present work describes the electrochemical performance of a columnar liquid-crystalline triazine-based dendrimer containing the linker with diaminopropane (DAP) as a lithium-ion battery anode. To elucidate the impact of conductive carbon filler in the electrode, a tiny amount of carbon nanotube (CNT) paper has been incorporated in the DAP anode. The battery performance revealed that the DAP anode has shown a high specific capacity of up to 444 mA h g−1 at 0.5 A g−1 after 200 cycles. Surprisingly, with an additional 1% CNT, the Li+ storage capacity of the dendrimer-based composite anode (DAP/CNT1%) significantly enhanced up to 656 mA h g−1. To the best of our knowledge, this is the first time that a triazine-based dendrimer has been utilized as an anode material in conjunction with a small amount of CNT to further boost its energy-storing capabilities through a synergy of capacitive storage mechanisms and improve Li+ transport. The efficient lithium storage of DAP/CNT composite further shows its amenability as organic electrode material for next-generation organic Li-ion batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

• An unsupervised feature extraction method of Li-ion batteries' EIS is proposed. • The latent variables are extracted automatically without prior knowledge. • The extracted latent variables are related to battery aging. • The capacity of batteries for uneven usage during degradation is estimated. • The proposed method generates reliable EIS data. In this paper, we propose an unsupervised feature extraction technique using a variational autoencoder and generative adversarial network (VAEGAN) that automatically extracts meaningful latent variables from the electrochemical impedance spectra (EIS) of lithium-ion (Li-ion) batteries. These variables accurately reflect the degree of Li-ion battery degradation and are closely related to its capacity. By analyzing the latent variables, it was found that the network can learn the effect of Li-ion battery capacity degradation on the EIS. The extracted latent variables are then used as input features for Gaussian Process Regression (GPR) to estimate the capacity of Li-ion batteries under uneven usage and with unknown historical data. The results show that the capacity prediction method proposed in this paper can significantly reduce prediction errors compared to the current state-of-the-art methods. The method not only provides a more reliable capacity estimation but is also robust to highly noisy EIS data, making it more suitable for practical application scenarios. [Display omitted] [ABSTRACT FROM AUTHOR]

• The proposed method can detect lithium plating earlier in the charging process. • Compared with other methods, this method is more sensitive and simple. • Combined with the model, the source of lithium plating signal is analyzed. • The universality of the method is verified by model simulation. Lithium plating is one of the most severe problems threatening the durability and safety of lithium-ion batteries. Therefore, accurate detection of lithium plating is crucial for the health management and charging control of lithium-ion batteries. In this paper, an impedance-based method is proposed to detect lithium plating of lithium-ion battery by comparing the normalized charing internal resistance profiles. After verifying that the model-based method is effective and feasible, it was used to analyze the reason and internal mechanism of the detection signal compared with the more frequently used lithium plating detection procedures today. The proposed detection method is more sensitive and accurate and expected to detect lithium plating in real-time during the charging process. Finally, the model showed that the method remained effective and reliable for lithium plating detection when the charging conditions changed. This paper, through the analysis, simulation, and experimental verification of online lithium plating detection method based on charging internal resistance, provides innovative ideas for the subsequent development of lithium plating detection and stimulates potential technologies for future development. [ABSTRACT FROM AUTHOR]

Lithium-ion battery (LIB) occupies a major position in rechargeable batteries. However, if the state of charge (SOC) estimation of LIB is not accurate, it will lead to the decline of battery life. SOC is often estimated by the extended Kalman filter (EKF) algorithm, but this method depends on the accuracy of model parameters. The sampling point interval time can affect the accuracy of SOC estimation. In this paper, the first-order RC model parameters are identified by two methods and the SOC is estimated by the EKF algorithm. Using this method, the battery parameters are received more accurate and the SOC estimation error is smaller. When the sampling interval is 0.03 s, the SOC estimation error is the smallest. And the second-order RC model can receive the same result. When the sampling interval is 0.03 s, the SOC estimation error of the 1RC-1 method is less than 1.4 %, the SOC estimation error of the 1RC-2 method is less than 0.017, and the root mean square error (RMSE) is 0.0087 and 0.01084. The conclusion is also used in the second-order RC model and contributes to the improvement of the SOC estimation accuracy. An effective method to estimate the battery SOC range is also proposed. This paper provides an effective method for obtaining more accurate SOC. [ABSTRACT FROM AUTHOR]

• Synthesis of MIL-100 (Fe) from Fe(OH) 3 slag from hydrometallurgy. • Porous structure improves the rate-multiplying performance of PIBs. • The porous structure improves the K+ migration reaction kinetics. • Incomplete coordination leads to higher carbon content. Recycling spent cathode materials is crucial for sustainably developing lithium-ion battery technology. To achieve the high-value utilization of spent LiFePO 4 (LFP) cathodes, this paper proposes a method for preparing MIL-100(Fe) based on solid waste residues from spent LFP cathodes. R-FeS 2 @C derived from MIL-100(Fe) can serve as an anode material for potassium-ion batteries featuring a porous structure. Electrochemical tests demonstrate that the R-FeS 2 @C exhibits more stable cycling performance compared with the FeS 2 @C derived from the traditional MIL-100(Fe), reaching 525 mAh g−1 after 100 cycles at a current density of 100 mA g−1. Impressively, R-FeS 2 @C also showcases excellent rate performance (343 mAh g−1 specific capacity at 5 A g−1). Furthermore, full cells assembled with PI@rGO cathodes also exhibit excellent rate performance and stable cycling performance. The porous structure of R-FeS 2 @C provides numerous voids to accommodate volume changes and introduces sufficient channels for electrolyte penetration. The higher carbon content enhances the electrical conductivity improving the kinetics of the K+ migration reaction. These researches can provide guidance for the recycling of spent lithium-ion batteries and the design of sulfide electrodes for PIBs. [Display omitted] [ABSTRACT FROM AUTHOR]

• Variations of battery expansion force during charge and discharge are quantified. • Variation patterns of expansion force during thermal runaway are compared. • Time series of expansion force versus T, V during thermal runaway are compared. • Feasibility of expansion force and its growth rate as warning signals are verified. In recent years, lithium-ion batteries have been widely adopted by the automotive industry because of their high energy density and environmentally friendly nature. However, the thermal runaway of lithium-ion batteries poses a significant risk of explosions, fires, and other hazards. Therefore, it is crucial to have effective thermal runaway warning systems to enhance the safety of battery applications. Currently, the main warning signals for thermal runaway include voltage, temperature, internal resistance, gas composition, and smoke. However, these signals suffer from issues such as low accuracy and delayed warnings. During thermal runaway, voltage, temperature, internal resistance, expansion force, and smoke undergo abnormal changes at varying times, with expansion force abnormalities detected notably earlier. To improve the accuracy and timeliness of thermal runaway warnings, it is crucial to quantitatively measure the changes in expansion force and signal progression related to voltage and temperature during thermal runaway through experiments. In this study, the 51 Ah LiNi 0.5 Co 0.2 Mn 0.3 O 2 /Graphite commercialized Li-ion batteries were used to study the characteristics of thermal runaway expansion force at different states of charge (SOCs) (25%, 50%, 100%, 110%). The variation patterns of thermal runaway parameters such as temperature, voltage, internal resistance, expansion force, and flame were analyzed. The test results indicate that the expansion force in lithium-ion batteries is related to the lithium-ion concentration in the negative electrode and remains below 2000 N with a rate of change under 1.8 N/s during normal charging and discharging. However, it surpasses 5000 N for thermal runaway. This paper suggests using a 2000 N expansion force as an early warning signal for thermal runaway, which precedes approximately 11.6 s earlier than the voltage signal and 10 s earlier than the internal resistance and temperature signals. Adopting a 1.8 N/s growth rate can further enhance warning time, issuing alerts 134.2 s before thermal runaway. Research confirms that using expansion force as the main signal significantly improves warning time and alarm accuracy in lithium-ion battery safety. [ABSTRACT FROM AUTHOR]

Li-ion batteries exhibit high energy density, while supercapacitors demonstrate high power density and long cycle life. A series of unimpeachable studies show that adding capacitive carbon to cathodes can construct a new type of capacitor batteries to greatly improve the rate capability and cycle life of Li-ion batteries without significantly reducing the energy density, so as to realize the technology integration of capacitor and battery. In this paper, with the aim of preparing high performance cathode material for capacitor battery, the cathode material with high speed electron, ion channels and high specific power and capacity is constructed by controlling the surface functional group of carbon additives, particle size and the characteristics of ion electron transport. The results show that although the presence of oxygen-containing functional groups on the surface of capacitive carbon can improve the capacity of capacitive carbon itself, it has adverse effects on the rate capability of cathode material of Li-ion batteries, and the more the oxygen content, the greater the internal resistance of the hybrid electrode, and the worse the electrochemical stability of the electrolyte. The size matching between the capacitive carbon particles and the cathode material can not only ensure good electron close contact and vibration density, but also the appropriate size of carbon additives can alleviate the volume expansion of the cathode electrode to enhance the cycle stability. Hybrid cathode electrodes constructed by LiNi 0.6 Co 0.2 Mn 0.2 O 2 and capacitive carbon with different oxygen-containing functional groups were prepared. By reasonably regulating the functional groups of capacitive carbon additives, high-rate performance is achieved while reducing system resistance and suppressing gas production to realize safe and efficient service of the battery. Moreover, we proposes a principle criterion of what size carbon additive should be selected for the particle size of cathode material. This paper can provide a theoretical guidance for building a capacitive lithium-ion battery with good rate capabilty and long endurability, especially under a high current charge/discharge. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C 3 N 4) is characterized by easy synthesis, high porosity and high nitrogen doping level. It has good application prospects as an negative electrode material for metal-ion batteries. However, graphitic carbon nitride (g-C 3 N 4) cannot be directly used as negative electrode material (NEMs) for lithium-ion batteries due to poor electrical conductivity and poor cycling performance. To solve this problem, in this paper, g-C 3 N 4 is synthesized on the surface of reduced graphene oxide by in situ synthesis method. The prepared rGO-g-C 3 N 4 composites have high surface capacitance process occupancy due to the presence of a large amount of pyridinic-N and pyrrolic-N, and various defects and pores generated during the synthesis process provide a large lithium-ion mobility rate for the rGO-g-C 3 N 4 composites. The rGO-g-C 3 N 4 composites have excellent electrochemical properties and excellent lithium storage performance, the capacity of 1 A/g after cycling 300 laps to maintain a high lithium storage capacity of 708.6 mAh/g, and is still in the rising state, even if the current density of 15 A/g under the cycle of 10,000 laps, the highest lithium storage capacity of up to can still be up to 423.6 mAh/g, and stabilized in the 306.8 mAh/g. This work provides a new idea for the preparation of new negative electrode materials with low cost and high capacity. [ABSTRACT FROM AUTHOR]

Accurate assessment of SOE and SOH is a critical issue in the battery management system. This paper proposes an improved variable forgetting factor recursive least square-double extend Kalman filtering algorithm based on global mean particle swarm optimization to obtain a stable and accurate SOE and SOH at different aging levels and temperatures. Firstly, this paper establishes a framework for the parameter identification of variable forgetting factors recursive least squares algorithm based on the global mean particle swarm optimization. Then, proposing a global mean particle swarm optimization search mechanism centered on variable time double extended Kalman filtering. Finally, The proposed algorithm is validated on the hybrid pulse power characterization (HPPC) and Beijing bus dynamic stress test (BBDST) datasets. The experimental results show that the MAE and RMSE of the SOE results based on the HPPC condition are less than 0.0096 and 0.0153 at -5 °C and 15 °C. Similarly, the estimation results based on the BBDST condition are less than 0.0094 and 0.0102, respectively. The SOH estimation errors are less than 0.02. Therefore, the variable forgetting factor recursive least square-double extend Kalman filtering based on global mean particle swarm optimization algorithm can achieve accurate and stable SOE and SOH at different aging levels and temperatures. [ABSTRACT FROM AUTHOR]

Micro pore-clogging in the electrodes due to SEI growth and other side reactions can cause adverse effects on the performance of a Lithium-ion battery. The fundamental problem of volume fraction variation and particle radius change during the charge-discharge process in a lithium-ion battery is modelled in this paper with the help of mass transfer based formulation and demonstrated on a battery with LiCoO 2 chemistry. The model can handle the volume fraction change due to intercalation reaction, solvent reduction side reaction and the electrolyte density change due to side reaction contamination in the battery. The entire calculation presented in this paper models particle radius and volume fraction together and therefore gives greater accuracy in calculating the volume-specific-area of the reacting particles which is an important parameter controlling the Butler-Volmer kinetics. The mass deposit on the electrode (or loss of lithium) gives an indication of the amount of pre-lithiation required to maintain cell performance while the amount of mass deposited on the SEI helps to decide the safe operating condition for which the clogging of pores and capacity fade will be minimal. Moreover the model presented in this paper has wide applicability in analysing the stress development inside the battery due to irreversible porous filling. [ABSTRACT FROM AUTHOR]

We design a macroscopic structure composing of porous carbon and graphene sheets, which are coated onto a cellulose paper as an interlayer inserted between electrode and separator. The interlayer mainly acts as a divertor to accommodate the discharge products breaking away from the electrode by mechanical degradation or cathode dissolution during cycling and keeps the close contact with current collector. Iron fluoride is a new-type lithium storage material developed in recent years, which can act as a cathode material candidate for the rechargeable lithium ion battery due to their large theoretical capacity and relatively high operating potential. Specifically, FeF 3 ·0.33H 2 O, which possesses unusual tunnel structure, is attracting more and more attentions. However, FeF 3 ·0.33H 2 O suffers from the poor electronic conductivity and volume effect during cycling, causing the large capacity fading. In this study, we design a macroscopic structure composing of porous carbon and graphene sheets, which are coated onto a cellulose paper as an interlayer inserted between electrode and separator. The interlayer can not only enhance the electronic conductivity, but also absorb the FeF 3 ·0.33H 2 O nanoparticles breaking away from the Al foil due to the volume effect upon cycling. When the interlayer is applied in battery, discharge capacities of 600 and 460 mAh g −1 can be achieved at the rates of 100 and 600 mA g −1 after 60 cycles, respectively. Furthermore, the capacity of 435 mAh g −1 can be still retained at a high rate of 1000 mA g −1 after 250 cycles. The results demonstrate a potential feasibility for the porous carbon/graphene sheets to be applied to obtain a high-performance lithium-iron fluoride battery. [ABSTRACT FROM AUTHOR]

• The structures of graphdiyne-based electrodes are modulated and diffusion kinetics of lithium ions are analyzed. • The lithium-ion diffusion coefficient is highly correlated with affinity of heteroatoms and porous structure of graphdiyne. • The diffusion behavior of lithium ions is verified by the proportion of diffusion processes in the storage contribution. The diffusion of lithium ions is highly related to the chemical structure, packing mode, and pore size distribution of the electrode materials. In this paper, a multiscale modification strategy is performed to investigate the correlation between the chemical structure and diffusion kinetics of lithium ions in graphdiyne (GDY) based electrodes. Various electrochemical tests show consistent results that hydrogen-substituted GDY has the fastest lithium-ion diffusion rate, and the doping of Cl and F atoms with large atomic radii leads to slower lithium-ion diffusion in the system. The functional groups (H, Cl, F) introduced in the GDY-based electrodes not only regulate the pore size of the materials but also modulate the binding energy with lithium ions. chlorine-substituted GDY shows a higher diffusion coefficient than that of fluorine-substituted GDY for proper affinity to lithium. In addition, the specific surface area and the pore size distribution also collectively contribute to the differences in lithium-ion diffusion. Finally, the lithium storage mechanism of substituted GDY electrodes is explored. Our strategy sheds some light on the design and fabrication of anode materials for lithium-ion batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

Although the application of lithium-ion batteries in the marine environment such as electric ships and other energy storage equipment, has gradually flourished in recent years, the effect of the special salt spray environment on the cells has not been carefully revealed since it may pose a corrosive threat to the metallized cells. In this paper, the electrochemical performance, aging mechanism, and thermal behavior of the cells after subjecting to different salt spray times are investigated experimentally. The results show that the corrosion morphology of cells is increasingly serious with the salt spray time, destroying the internal structure of the battery and accelerating its aging. The capacity decay mechanism is mainly due to the loss of active material (LAM), while the contribution of the loss of available lithium inventory (LLI) gradually increases and tends to prevail upon the former as the corrosion time prolongs. Findings also show both a larger state of charge and longer salt spray time will result in a much higher battery temperature during the cycling process. The maximum temperature of LIBs with 100 % SOC and salt spray time of 40 h reaches 36.23 °C during the 50th cycle, while that for 0 % SOC is only 30.56 °C. Therefore, the corroded cells age faster, generates more heat, exhibits worse safety performance, and is more likely to cause thermal runaway and other safety issues than the normal ones. [ABSTRACT FROM AUTHOR]

• Almost all the Al-ion batteries' cathode materials were evaluated with the approach. • The normalization/standardization approach was applied to the charge-discharge data. • The carbon-based cathodes present excellent performance and rate-capability. • The cathode substrate plays role in the properties. • The electrolyte type affects the activity of the cathode particles. The improvement of the intercalation electrodes for Al-ion batteries needs a deep understanding of the relation of charge-discharge parameters, especially the specific capacity (C) and the charge-discharge rate (R). In this paper, we extract many experimental charge-discharge data (C and R) from the literature. Evaluating the data, we employ an approach which has been proposed for the normalization and standardization of the intercalation batteries' data. The approach presents an appropriate manner for assessing the goodness of a given electrode and cell performance. The data of Al-ion batteries' electrode materials show more distribution in comparison with Li-ion and Na-ion batteries. We find that the distribution of the curves is due to three main parameters, namely synthesis method, electrolyte type, and substrate of the electrode. It is found that among the considered materials the carbon-based electrodes including graphene, carbon nanotube, and graphite provide the best performance and rate-capability, while the MoS 2 electrode shows the poorest one. It is concluded that (de)intercalation of AlCl 4 − ions has a faster kinetic than Al3+ ions. Accordingly, an insight for the perspective of the future researches of the intercalation batteries is suggested. This study helps finding appropriate materials (electrode, electrolyte, and substrate), and paves the way for optimization of the cells. Noteworthy, this paper is vanguard for this kind of evaluations and its methodology can be used for other kind of cells and electrodes. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper describes a method for the preparation of composite cathodes for lithium ion-batteries by using poly vinyl acetate (PVAc) as a binder. PVAc is a non-fluorinated water dispersible polymer commonly used in a large number of industrial applications. The main advantages for using of this polymer are related to its low cost and negligible toxicity. Furthermore, since the PVAc is water processable, its use allows to replace the organic solvent, employed to dissolve the fluorinated polymer normally used as a binder in lithium battery technology, with water. In such a way it is possible to decrease the hazardousness of the preparation process as well as the production costs of the electrodes. In the paper the preparation, characterization and electrochemical performance of a LiFePO 4 electrode based on PVAc as the binder is described. Furthermore, to assess the effect of the PVAc binder on the electrode properties, its performance is compared to that of a conventional electrode employing PVdF-HFP as a binder. [ABSTRACT FROM AUTHOR]

Porous tin films as anode for lithium-ion batteries are electrodeposited on graphite paper. Homogeneous tin films with significant void space accommodate the volume change during tin lithiation/delithiation. Through adjusting the electrodeposition currents and time, the morphologies and void space of tin films on graphite paper are controllable. At fixed electrodeposition current densities, the prolonged electrodeposition time plays the role in growing big tin particles and resulting the disappearance of void space among tin particles. The increased electrodeposition current plays the role to increase the quantity of tin seeds in thickness of tin film, and the void space among tin particles remains but the thick film limits its electrochemical performance. The tin films electrodeposited at an optimized current densities and for an optimized electrodeposition time, present the best electrochemical performance, because the tin nanoparticles are well dispersed on graphite substrate including void space. The tin film electrodeposited at 0.2 A cm −2 for 2 min shows the capacity of 1.0 mAh cm −2 after 50 charge/discharge cycles. The void space of tin film is very important for the best capacity and cyclic ability. The metallic tin film produced at 0.4 A cm −2 for 3 min remains the uniform and microporous structure after charge/discharge for 50 cycles. [ABSTRACT FROM AUTHOR]

Magnesium ion batteries (MIBs) and magnesium/lithium hybrid ion batteries (MLIBs) are promising candidates for next-generation energy storage, due to the large capacity, abundant magnesium reserves, and safe operation. Nevertheless, the use of MIBs and MLIBs is limited by sluggish Mg2+ kinetics and Li+-dependent storage in cathode materials, respectively. Herein, an efficient interlayer expansion strategy is employed to deal with the problems in both MIBs and MLIBs based on VS 2. The interlayer spacing of VS 2 is enlarged to 1.0 nm by octylamine intercalations via one-pot solvothermal reaction, generating dramatically enhanced electrochemical performance in MIBs and MLIBs. Moreover, various ex situ methods are used to confirm a Li+/Mg2+ co-intercalation in the expanded VS 2 , with most of the capacity controlled by pseudo-capacitance. This work expands the application of interlayer expansion strategy to enhance magnesium ion and lithium/magnesium hybrid ion storage. An interlayer-expanded, binder-free VS 2 nanosheets assemblies on carbon paper is prepared via a facile solvothermal method for both MIBs and MLIBs. The intercalations of octylamine and/or NH4+ into VS 2 produces a largely expanded interlayer spacing of 1.0 nm, which widens the ion diffusion channel, alleviates the electrostatic interaction between ions and S–V–S monolayers, and mitigates the volume changes during cycling. As a result, dramatically enhanced electrochemical performance is observed in both MIBs and MLIBs. Image 1 [ABSTRACT FROM AUTHOR]

Lithium-ion battery (LIBs) applications using antimony (Sb) based anodes with high specific capacity and suitable operating voltage have showed tremendous potential. However, the large volume variation during electrochemical cycling limits their application. In this paper, M-Sb (M=Co, Ni) nanoparticles embedded in nitrogen doped carbon nanofibers have been prepared by an electrospinning method, 3D interconnected M-Sb@CN (NiSb@CN and Sb/CoSb 2 @CN) fiber composites are obtained finally. M-Sb nanoparticles are uniformly distributed in N-doped carbon nanofibers, which can prevent their direct exposure to the electrolyte. Compared with bare Sb-M and Sb-C binary electrodes, the M-Sb-C three-component composite electrodes show smaller volume change and stronger charge transport ability. The introduction of the transition metal (Co, Ni) not only serves as buffer substrate for volume change, but also regulates the properties of carbon fibers as a catalyst. High reversible capacities of 647.4 and 620.2 mA h g−1 of NiSb@CN and Sb/CoSb 2 @CN fiber composites can be maintained after 600 cycles at a current rate of 500 mA g−1. First principles calculation demonstrates that N-doping and the incorporation of transition metal M have favorable effect on the improved Li binding energy, offering a possibility for the material design of the high-performance LIBs. [ABSTRACT FROM AUTHOR]

• The link between the current densities and the spatial derivatives of the overvoltage is clarified. • An explicit closed-form solution for the distribution of in-plane electrochemical current density is derived for cylindrical batteries. • The effects of tabbing design and the resistance of current collectors on the current density distribution are investigated. • The influence of electrochemical kinetic parameters of electrodes is studied separately. • The variations of electronic current densities along the battery are studied as well. Reaction rate distribution and current density distribution of Li-ion batteries largely determine the local aging and heat generation. Homogenous distribution contributes to better durability and safety of Li-ion batteries. This paper focuses on modeling the in-plane distribution of electrochemical reaction current, and the general equation relating space derivatives of the overvoltage to the electrochemical and electronic current densities is derived. Furthermore, this work investigates the impact of various battery parameters on the distribution by considering the cylindrical battery, one of the most used battery types. An explicit closed-form solution for a short time after the current supplied is obtained. It is found that the dimensions of cylindrical batteries, tabbing design, parameters of current collectors, and electrode materials are all indicated to affect the current density distribution. The electronic current density distribution is also demonstrated. This model and related analyses are incredibly beneficial for further optimizing Li-ion batteries' electronic and electrode properties and as interesting cases for testing battery modeling tools. [ABSTRACT FROM AUTHOR]

• A natural cellulose derived fibrous WO 3 /carbon composite was fabricated. • The composite has a 3D structure with WO 3 microspheres anchored on the carbon fibers. • As an anodic material, the composite shows improved electrochemical performances. To meet the ever-growing demands over electrochemical energy storage, tungsten trioxide (WO 3) has aroused substantial attention as a promising anodic material for lithium-ion batteries due to its high theoretical capacity, abundant earth storage, and eco-friendliness. However, developing high-performance WO 3 -based electrodes is hampered by its restrictive conductivity and tremendous structural as well as the volumetric changes during the charge/discharge processes. Herein, a novel bio-inspired nanofibrous WO 3 /carbon composite was synthesized via a facile hydrothermal method employing pre-carbonized cellulose substrate (e.g., ordinary filter paper) as both the structural scaffold and the carbon source. The urchin-like WO 3 microspheres with diameters of 3–6 μm assembled by nanorods were uniformly anchored on the surfaces of the cellulose-derived carbon fibers. The three-dimensional network structure of the composite was beneficial in alleviating the volume expansion of WO 3 nanorods and enhanced the charge-transport kinetics of the electroactive materials. The composite with an optimized content of WO 3 (26.36 wt%) exhibited superior lithium storage properties with an initial discharge capacity of 1470 mAh g−1 and an extraordinary long-term cycling performance of 682 mAh g−1 capacity retention after 300 cycles at 100 mA g−1. Furthermore, cyclic voltammetry, ex-situ XRD, and SEM measurements for mechanism studies were carried out to yield deeper insights into the synergism in the WO 3 /carbon electrodes, revealing the predominance of reversible pseudocapacitive intercalation of lithium-ions during the electrochemical reaction inside the WO 3 /carbon anode. A natural cellulose derived WO 3 /carbon nanofibrous composite was fabricated, showing enhanced electrochemical performances as an anodic material for lithium-ion batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

As the cathode material of lithium-ion batteries, Li-rich ternary layered oxides usually suffer from high first cycle irreversible capacity, low rate capability, and structural instability during charge–discharge. Recent studies show that Ni-rich Li 1.20 Mn 0.44 Ni 0.32 Co 0.04 O 2 material has good structural stability. In this paper, the electrochemical performance of Li 1.20 Mn 0.44 Ni 0.32 Co 0.04 O 2 and its oxygen-deficient phase Li 1.20 Mn 0.44 Ni 0.32 Co 0.04 O 1.83 are studied by the first-principles calculations. The results show that, for the pristine phase Li 1.20 Mn 0.44 Ni 0.32 Co 0.04 O 2 , the theoretical delithiation capacity is 380 mAh/g and the highest charging voltage platform is 4.99 V. The O ions are found to participate in the charge compensation significantly. Ni ions can only contribute 118 mAh/g of the delithiation capacity, and the remaining charging capacity is contributed by O ions. For the oxygen-deficient phase Li 1.20 Mn 0.44 Ni 0.32 Co 0.04 O 1.83 , the highest voltage platform is reduced by 0.21 V, O ions are also found to participate in the charge compensation obviously. Compared to the pristine phase, transition metal (TM) ions in the oxygen-deficient phase exhibit higher chemical activity, while the contribution of O ions to charge compensation is relatively reduced. The oxygen-deficient phase has a slightly higher theoretical capacity (392 mAh/g) than the pristine phase. [Display omitted] [ABSTRACT FROM AUTHOR]

• A Box-Behnken design for graphite anodes slurries optimization was presented to highlight the importance of the component's interactions to obtained higher performed anodes of lithium-ion batteries customization. • The carbon black content is the most significant effect in both materials which is reflected in higher capacities and coulombic efficiencies. • For the overall behavior, the binder/carbon black interactions are relevant in terms not only of electrochemical performance but also in the obtention of more homogeneous and better adhesion anodes. The technological application of lithium-ion batteries (LIB) grows constantly, making customization of the batteries a current necessity and sometimes a challenge. In this paper we described carbon-slurry optimization process for anodes of lithium-ion batteries customization by using a surface response statistical experiment with four response variables such specific discharge capacity, coulombic efficiency, anodes mass deviation, and capacity retention. We studied two commercial graphite active materials by characterizing the materials via Raman spectroscopy, SEM, and electrochemical techniques. We corroborate the graphite structure for both materials but with morphological differences such as shape and particle size. The binder composition seems to interfere with the active carbon materials capabilities while it generates better performance for one of them. Although the chemical structure of both materials was confirmed to be the same via Raman experiments, SEM images shows critical morphological differences that interferes with the final slurry thus, affecting the electrochemical performance of the anodes. Further studies are required to understand ECSA and its possible effect on the charge/discharge capacities of the anodes. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: An effective method of using cellulosic substances (filter paper) as template was employed to prepare SiO x nanotubular materials examined as anode for Li-ion battery. According to XRD, SEM, TEM and HR-TEM analysis, the synthesized nanotubular materials retained the morphological hierarchy of the filter paper, and each nanotube was composed of nanosized SiO x ranged from 5 to 20nm. It exhibits a stable reversible capacity of 940mAhg−1 at constant current density of 100mAg−1, and capacity retention keeps over 91.5% after 50 cycles. The nano-scale characteristics of SiO x particle embed in the nanotube ensures the fast Li-ion diffusion in the electrode. The nanotube came from cellulose fiber template provides the electrode with firm framework, and thus avoids the electrode to pulverize in the charge–discharge process. Moreover, the hollow structure offers a sufficient void space, which sufficiently alleviates the mechanical stress caused by volume change. All these factors are responsible for the stable electrochemical performance of SiO x electrode. [Copyright &y& Elsevier]

Abstract: Li-ion batteries are frequently modeled using variants of the one-dimensional approach that was initially developed by Newman and colleagues (e.g., ). Necessarily such an approach is based upon assumptions about the electrode microstructure, and quantitative predictions depend upon empirical parameters such as effective conductivities and diffusion coefficients. The present paper develops a three-dimensional model that can resolve electrode structure at the submicron scale. Although the three-dimensional model is capable of representing arbitrary electrode microstructure, the present paper considers regular arrays of spherical particles. The model is applied to evaluate approximations in one-dimensional models and to assist in establishing empirical relationships that can be used in reduced-dimension models. General relationships for effective particle radius in one-dimensional models are derived from the three-dimensional simulations. The results also provide a basis for estimating the empirical Bruggeman exponents that affect Li-ion transport within electrolyte solutions. [Copyright &y& Elsevier]

In this paper we report a comprehensive analysis and tracking of the variabilities associated to multiscale simulations coupling a Coarse Gained Molecular Dynamics (CGMD) model of Lithium Ion Battery (LIB) electrodes fabrication with a 3D-resolved performance model at the cell scale. We quantify the impact on the final electrode mesostructure of the initial conditions in the CGMD simulations in terms of initial random distribution in the slurry of the active material and carbon binder domain particles (CBD). This study is carried out with a batch of simulations at different slurry active material/CBD compositions. Results show that for each electrode composition there is a statistical dispersion in the predicted cell performance curves, in agreement with in house experimental results. Furthermore, in house experiments revealed a different correlation regime depending on the C-rate at which the cathode is operating. The proposed methodology and findings allows us to pave the way towards the design of reliable approaches to control the variables correlations in the multiscale modeling of electrodes fabrication and its impact on LIB performance. Image 1 [ABSTRACT FROM AUTHOR]

The key to accurate simulation the thermal characteristics of lithium-ion batteries is to develop a reliable estimation model of the battery calorific value, which is very useful to design the thermal management system of the battery pack. This paper proposes a semi-empirical thermal model with virtues of high computational efficiency and precision for thermal analysis of the lithium-ion battery. In this model, a generalized and simple equation is developed to calculate the heat generation rate of the battery on the basis of its thermogenesis mechanisms. Two experimental fitting equations are acquired to estimate the battery ohmic resistance and entropy change coefficient, and a general formula is derived for the polarization resistance based on an approximate model of lithium diffusion process. Then, the semi-empirical thermal model is established for the battery by using the proposed computational method of the heat generation rate. The galvanostatic discharging and charging processes of a prismatic lithium-ion battery are separately simulated at the different currents and temperatures, and the corresponding experiments are conducted for the model validation. The results show that the battery temperatures simulated by the proposed model are good agreement with the experimental data. According to the calculation, the mean absolute deviations of the simulated battery temperatures are 0.27 °C for the discharging processes and 0.17 °C for the charging process under the orthogonal conditions of the operation currents (0.3C, 1.0C and 2.0C) and the ambient temperatures (10 °C，25 °C and 35 °C). Compared with the theoretically based model, the proposed model exhibits a higher computational accuracy in the most operating regions and improves calculation speed by more than 4.0 times at the same grid density and time step setups. Consequently, the semi-empirical model proposed in this work is well-suited to pre-assess thermal characteristics and thermal management system schemes of the large-scale battery pack due to its superiorities of easy implementation, high computational efficiency and high precision. • An accurate and simple heat estimation method is built for lithium-ion batteries. • A general formula is derived for the polarization resistance of the battery. • An improved semi-empirical model is developed for thermal analysis of the battery. • The proposed model improves calculation rate greatly without compromising precise. [ABSTRACT FROM AUTHOR]

Abstract Accurate parameter identification and state of charge (SoC) estimation of a Li-ion battery are a critical issue for efficient monitoring, control and utilization of advanced battery management system (BMS) in electric vehicles. The existing single-particle model with electrolyte dynamics (SPMe) can accurately describe the Li-ion cell's macro-micro scale dynamic behaviors, but they are vulnerable as predictive tools under specific operating conditions, which is more prone to erroneous estimation results. To overcome this problem, this paper proposes a parameter identification scheme with its systematic validation for an enhanced electrochemical aging model of the cylindrical 18650 Li-ion nickel manganese cobalt oxide (NMC) cell under the typical experimental testing scenarios. First, a SPMe-based aging degradation model is developed through including Solid-Electrolyte-Interface (SEI) layer formation at the negative electrode, denoted as eSPMA model. Next, the dozens of parameters in this eSPMA model are evaluated using the conventional genetic algorithm and the validation of these identified parameters is conducted under different operating conditions, and simultaneously, this eSPMA model is used to estimate Li-ion batteries SoC under the same operation scenarios. Finally, the effectiveness of the identified parameter is validated by a comparative study of the simulated and experimental voltage and SoC under the same input current profile based on the eSPMA and the Doyle–Fuller–Newman (DFN) model. The results of this study can assist in the experiment design of battery capacity degradation and facilitate the accurate estimation of state-of-health for advanced battery management system in the electrified vehicle applications. Highlights • An eSPMA model of Li-ion batteries is presented to perform the parameter identification and its systematic validation. • The dozens of parameters are identified based on GA and the validation is conducted under different operating conditions. • The comparative study on the eSPMA and P2D model with the identified parameters is performed to make SoC estimation. [ABSTRACT FROM AUTHOR]

Abstract State-of-health evaluation of lithium ion batteries is one of the key challenges to construct efficient battery system with enhanced performance. In this paper, we demonstrate a facile evaluation method which is based on the voltage stabilization behaviour during relaxation. A second-order equivalent circuit is employed to describe the voltage relaxation. By simulating the voltage relaxation curves, the characteristic parameters that can distinguish the ohmic, activation and concentration depolarizations are acquired. The obtained parameters are sensitive to electrochemical states, which provide comprehensive evaluation to the state-of-health of batteries and aging mechanism analysis. As an example, the proposed method identifies two aging stages of Li(Ni 1/3 Co 1/3 Mn 1/3) O 2 /graphite pouch cells during accelerated aging. Namely, a loss of lithium inventory in the first stage of aging, and the loss of active material in the next stage. Postmodern analysis including X-ray diffraction and high-resolution transmission electron microscope well agrees with the voltage relaxation simulation. The proposed state-of-health evaluation method is non-destructive and accessible for on-board aging diagnosis, which is of great significance for developing better battery management system. Highlights • A facile and in-depth state-of-health (SOH) evaluation method is developed. • We accurately model the VR behaviour using a second-order RC model. • The VR method is non-destructive and accessible for on-board aging diagnosis. • The aging mechanisms are distinguished by VR method. [ABSTRACT FROM AUTHOR]

Abstract A simple strategy which combines the treatment of industrial wastewater with the preparation of electrode materials was proposed in this work. And the industrial wastewater is the only iron source for the material preparation. The preparation method in this work is facile, economical and environment-friendly which includes two simple steps of low-temperature aqueous solution and one-step calcination. Moreover two kinds of high performance Fe 2 O 3 anode materials (α-/γ-Fe 2 O 3 nano spheres, respectively) with isomerism can be obtained by simply adjusting calcination temperatures. Both of the α-Fe 2 O 3 and γ-Fe 2 O 3 nanospheres show good lithium storing reversibility when used as anode materials in LIBs. Furthermore the as-prepared α-Fe 2 O 3 nano-electrode with lower electrochemical impedance exhibit a far better electrochemical performance (about 74.1% capacity retention (calculated based on the lithiation) from the 1st to 5th cycle) than the γ-one (only 39.0% capacity retention from the 1st to 5th cycle). The results here provide economical yet environment-friendly strategies for developing advanced anode material demanding both high energy and long lifespan for full-cell lithium battery. Highlights • Waste utilization and material preparation are effectively combined in this paper. • The industrial wastewater is the only iron source for the material preparation. • Isomeric Fe 2 O 3 anode materials can be obtained by simply adjusting calcination temperature. • The α-Fe 2 O 3 electrode exhibits a relatively high and stable reversible capacity. [ABSTRACT FROM AUTHOR]

Abstract Further modification of carbon and transition metal composites has become a hot spot in the preparation of anode materials for lithium ion battery, including various morphologies, nitrogen doping and porous introduction. However, the synergistic effect of specific surface area and nitrogen doping content of composite materials on the electrochemical performance as anode materials for lithium ion batteries has not been revealed. In this paper, the carbon nanofibers loaded with titanium dioxide are fabricated via electrospinning method followed by calcination process with simple addition admixture of diisopropyl azodiformate in precursor solution. The pores are introduced into the composite with controllable nitrogen doping and surface area simultaneously. The specific capacity of titanium dioxide @carbon nanofibers has been increased from 192.2 mAh g−1 to 336 mAh g−1 due to the increased nitrogen content of the composite from 7.18% to 10.21%, and elevated specific surface area from 67.23 to 111.15 m2 g−1, which can endow the composite superior conductivity and more active sites. The capacity contribution of the total specific capacity has decreased from 60.8% to 44.7% compared with original sample, proving that increasing diffusion controlled Faradaic Li-ion insertion origins from nitrogen doping. Graphical abstract Image 1 Highlights • Composite with controllable nitrogen doping and surface area simultaneously is fabricated with addition of DIPA. • The electrochemical performance of the composite with improved surface area and nitrogen doping content is studied. • Superior electrochemical performance of freestanding TiO 2 @CNFs as anodes for lithium-ion batteries is exhibited. [ABSTRACT FROM AUTHOR]

Abstract The tungsten niobium oxides that belong to the well-known Wadsley-Roth shear structure have been already studied as the high-performance anode materials over the past several years since these materials can provide the additional vacuum site for accommodating lithium ions. Now, a novel anode material Nb 18 W 16 O 93 which has a tetragonal tungsten bronze type structure is firstly reported in this paper. This material exhibits the good electrochemical performance. Upon the modification of its surface morphology, the electrochemical performance for Nb 18 W 16 O 93 nanowire has been greatly improved. Nb 18 W 16 O 93 nanowire shows the reversible specific capacity of 195 mAh g−1 when the current density is 100 mA g−1 and it can reach 153 mAh g−1 even at 1000 mA g−1. Meanwhile, the lithiation/delithiation mechanism and its corresponding structural change during the charge and discharge process are also carried out by an in-situ XRD technique. The result shows that Nb 18 W 16 O 93 nanowire has excellent electrochemical reversibility and structural stability. Consequently, Nb 18 W 16 O 93 nanowire can be employed as a novel anode material for lithium ion batteries. Graphical abstract Image 1 Highlights • Nb 18 W 16 O 93 nanowires are prepared by a facile electrospinning method. • Nb 18 W 16 O 93 nanowires show better electrochemical performance than the bulks. • Nb 18 W 16 O 93 nanowires deliver a capacity of 153 mAh g−1 at 1000 mA g−1. • Structural evolution of Nb 18 W 16 O 93 during lithiation is analyzed by in-situ XRD. [ABSTRACT FROM AUTHOR]

Abstract Metal-organic frameworks can provide excellent templates for the preparation of nanomaterials for green energy storage. However, it is still a formidable challenge for the synthesis of MOF-templated Sn-based nanomaterials with controllable morphologies and structures. Here, Sn-based MOFs with different morphologies are synthesized by a facial and controllable method, then SnO/C polyhedrons with shapes of cube and stellated octahedron are obtained using the Sn-based MOFs as template by further heat treatment, respectively. Benefited from the composite structures, the SnO/C polyhedrons exhibit excellent electrochemical performances in lithium storage. A high reversible capacity of 950 mA h g−1 is obtained at a current density of 50 mA g−1 after 100 cycles, together with superior cyclic stability and remarkable rate capacity. This paper provides an effective route to prepare high-performance Sn-based anode materials from the morphology-controlled MOFs for lithium-ion batteries. Graphical abstract Image 1 Highlights • A facile method was provided to synthesize Sn-based MOF polyhedrons and their derived pyrolytic SnO/C composites.. • SnO nanorods are dispersed in the carbon matrix uniformly, which enhances the energy storage properties of the composites.. • The product exhibited a high reversible capacity of 950 mA h g−1 at 50 mA g−1, together with superior rate capacity. [ABSTRACT FROM AUTHOR]

Abstract: This paper is particularly concerned with the elementary reactions and transport processes that are responsible for Li-ion battery performance. The model generally follows the widely practiced approach developed by Newman and co-workers (e.g., Doyle et al., J. Electrochem. Soc. 140 (1993) 1526 ). However, there are significant departures, especially in modeling electrochemical charge transfer. The present approach introduces systems of microscopically reversible reactions, including both heterogeneous thermal reactions and electrochemical charge-transfer reactions. All reaction rates are evaluated in elementary form, providing a powerful alternative to a Butler–Volmer formalism for the charge-transfer reactions. The paper is particularly concerned with the influence of non-ideal thermodynamics for evaluating reversible potentials as well as charge-transfer rates. The theory and modeling approach establishes a framework for extending chemistry models to incorporate detailed reaction mechanisms that represent multiple competitive reaction pathways. [Copyright &y& Elsevier]

Electrochemical impedance spectroscopy (EIS) is a widely used experimental technique for characterising materials and electrode reactions by observing their frequency-dependent impedance. Classical EIS measurements require the electrochemical process to behave as a linear time-invariant system. However, electrochemical processes do not naturally satisfy this assumption: the relation between voltage and current is inherently nonlinear and evolves over time. Examples include the corrosion of metal substrates and the cycling of Li-ion batteries. As such, classical EIS only offers models linearised at specific operating points. During the last decade, solutions were developed for estimating nonlinear and time-varying impedances, contributing to more general models. In this paper, we review the concept of impedance beyond linearity and stationarity, and detail different methods to estimate this from measured current and voltage data, with emphasis on frequency domain approaches using multisine excitation. In addition to a mathematical discussion, we measure and provide examples demonstrating impedance estimation for a Li-ion battery, beyond linearity and stationarity, both while resting and while charging. [ABSTRACT FROM AUTHOR]

Understanding the contribution of internal direct current resistance (DCR) is crucial to the design and optimization of lithium-ion batteries (LIBs). However, the complex dynamic processes existing inside the battery pose great challenges to the decomposition of DCR, especially in large size cylindrical lithium-ion batteries with composite electrodes. In this paper, we achieve a comprehensive decomposition of DCR through a combination of experiments and simulations, and study the change of DCR with different discharge rates and different temperature conditions. By decoupling the internal resistance of different components and different kinetic processes inside the battery, the main limited factors of the battery in different working conditions are revealed. Our study clarifies the change of DCR with temperature and rates and provides essential guidance for the reasonable selection and design of materials in high-performance batteries. [ABSTRACT FROM AUTHOR]

The Tesla model 3 has rapidly become one of the most popular electric vehicles (EV), being the best selling EV in 2020 and the second best selling in 2021. In this paper the ageing implications of varying time scales in usage of the battery are investigated for the 2170 cells used in the Tesla model 3. It is shown that dynamic usage in the range of approximately 0.01 to 0.1 Hz has a statistically significant impact on ageing, while dynamic usage in range 0.1 to 1 Hz does not show significant impact on ageing. Furthermore the individual electrode ageing is investigated by non-invasive electrochemical techniques, revealing the profound impact on ageing from Si addition to the negative electrode, where it is shown that substantial part of the ageing comes from loss of Si in the negative electrode. [ABSTRACT FROM AUTHOR]

• An electrochemical method is proposed for the treatment silicon cutting waste. • The uneven and irregular silicon cutting waste is converted into uniform silicon nanorods. • The prepared silicon nanorods exhibits excellent lithium storage performance. This work reports the reconstruction and purification of silicon cutting waste (SCW) through a two-step molten salt electrochemical process, namely, a cathodic polarization mainly for the generation of Mg 2 Si followed by electrolysis of Mg 2 Si. After this process, the original uneven and irregular SCW particles were converted into uniform silicon nanorods (SNR, 30–50 nm in sizes), and the amount of impurity elements in SCW were significantly reduced. The as prepared SNR exhibits high specific capacity, good rate performance and cycle stability. It delivered a capacity of 3269 mAh g−1 at 1 A g−1 with an initial coulomb efficiency of about 91%. After 100 cycles, the SNR retained a capacity of 2429 mAh g−1, equivalent to 74% capacity retention, far superior to that of SCW (273 mAh g−1). This paper presents a simple, green, low cost and environmentally friendly method to convert SCW into value-added nanoscale silicon for lithium-ion battery anodes. [ABSTRACT FROM AUTHOR]

• From the simulation with COMSOL, the reason for the improvement of high-rate performance of through-holed cathodes was discussed. • The structural parameters of the NMC layer in the through-holed cathodes was optimized. • It was considered that the enhancement of the Li+ ion transfer through the sidewall in the through-holes caused the improvement of high-rate performance. • The consideration of the structural parameter distribution around a through-hole lead to reasonable agreements between the experimental data and calculated values. In previous papers, we reported that the through-holing of lithium iron phosphate cathodes for lithium - ion batteries with a picosecond pulsed laser efficiently improved the high-rate performance. The enhancement of the Li+ ion transfer was caused by the increase in the pathway of the Li+ ions to/from the lithium metal oxide LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC) particle surfaces through the sidewall in the through-holes, and this potentially caused the improvement in the high-rate performance. To clarify our deduction, the structural parameters that caused similar experimental results and calculated values were determined by changing the structural parameters of the NMC layer in the through-holed cathodes. The consideration of the structural parameter distribution around a through-hole lead to an agreement between the experimental data and calculated values. From the structural parameters determined, the through-holed structure had negative factors caused by laser irradiation and disrupted the electronically conductive paths within the NMC layer. However, the high-rate performance improvement could be achieved due to the increased area accessible to lithium ions in the through-holes. [Display omitted] [ABSTRACT FROM AUTHOR]