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With the progressively widespread application of lithium‐ion batteries, their energy density and power density are being pursued to the extremely high. However, both cannot be reached simultaneously at present. Tortuosity depicts the relationship in ionic diffusion between bulk electrolyte and the electrolyte in a porous electrode, provides information about channels within electrodes, and correlates the current dilemma between energy density and power capability of the lithium‐ion batteries. It is crucial to upgrade the fast charging and discharging performance of LIBs electrodes without losing volumetric energy density and using tortuosity as a guide is able to achieve this goal fundamentally. Meanwhile, tortuosity can serve as an evaluation parameter for production quality assessment, but this demands a fast, accurate, and cost‐effective measuring method. After the definition and measurement of tortuosity are provided, this article analyzes the structural influencing factors of tortuosity which have impacts on ion transportation and subsequently on tortuosity to facilitate a more systematic and comprehensive picture. Through the discussion of contradictions and influencing factors, a more refined transmission line model (the refined TLM) is perceived as the very first step to drive both aforementioned goals toward success and is discussed in the perspective part. [ABSTRACT FROM AUTHOR]

In this paper, a series of iron oxide/reduced graphene oxide/carbon nanotube composites (K3‐Fe2O3‐rGO/CNT) with well‐dispersedFe2O3 particles are prepared by in situ reaction and then heat‐treatment, and its electrochemical and battery performancesare studied as the anode material of lithium‐ion batteries. The results show that the introduction of reduced graphene oxide/carbon nanotube (rGO/CNT) improves the electrochemical and battery performances of the prepared electrode material. In particular, the K3‐Fe2O3‐rGO/CNT (30 %) composite material has a reversible capacity of 1559 mAh g−1 after 100 charge/discharge cycles at 100 mA g−1. And its specific discharge capacityis 641.1, 639.7, 609.5, 578.6 and 543 mAh g−1at the current density of 100, 200, 500, 1000 and 2000 mA g−1, respectively,with 84.7 % of capacity retention even with a 10 times increase in current density. The research of charge storage indicates that the electrochemical process is a mixed control process of diffusion and capacitance. The improved electrochemical and battery performancesfor the composite electrode material can be attributed to the enhanced dispersion of the Fe2O3 and the enhanced conductive network provided by rGO/CNT composite carbon. It makes a promising way to prepare high performance of anode material for lithium‐ion battery. [ABSTRACT FROM AUTHOR]

The calendering process is used to improve the porosity, energy density and electrochemical performance of the electrodes of lithium-ion batteries. The calendering process is crucial for optimizing the electrodes pore structure. For this reason, NMC and graphite electrodes prepared for pouch-type cells were calendered. After calendering, physical and electrochemical characterizations were made. The electrodes produced were prepared in thicknesses of 150µm and calendered at 10%, 15%, 20%, 30% deformation rates. The electrodes produced were prepared in thicknesses of 150µm and calendered at 10%, 15%, 20%, 30% deformation rates. The surface morphology of the electrodes was characterized using Scanning Electron Microscopy (SEM). The electrochemical performance of pouch-type cells was investigated by impedance, speed capacity and cycle life tests from 2.7V to 4.3V. After calendering, it has been shown that the electrochemically active area increases with smaller pore size and distribution. It has been found that the ability to wet decreases with the increased calendering rate. Calendared electrodes at a rate of 20% deformation in graphite electrodes and 15% in NMC electrodes were found to show balanced discharge capacity at C/10 current speed. [ABSTRACT FROM AUTHOR]

Inspired by dative boron‐nitrogen (B←N) bonds proven to be the promising dynamic linkage for the construction of crystalline covalent organic polymers/frameworks (COPs/COFs), we employed 1,4‐bis(benzodioxaborole) benzene (BACT) and N,N′‐Di(4‐pyridyl)‐1,4,5,8‐naphthalenetetracarboxdiimide (DPNTCDI) as the corresponding building blocks to construct a functional COP (named as CityU‐25), which had been employed as an anode in rechargeable lithium ion batteries. CityU‐25 displayed an excellent reversible lithium storage capability of 455 mAh/g after 170 cycles at 0.1 A/g, and an impressive one of 673 mAh/g after 720 cycles at 0.5 A/g. These findings suggest that CityU‐25 is a standout candidate for advanced battery technologies, highlighting the potential application of this type of materials. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries are becoming more popular due to their superior performance like high power density, long lifespan, broad operating range of temperatures, quick charging capabilities, and low self-discharge. The implementation of a Battery Management System (BMS) is crucial in order to guarantee the secure and optimal functioning of electric vehicle batteries. BMS monitors, controls, and maintains the health and performance of rechargeable batteries by monitoring the State of Charge (SoC), State of Health (SoH), and State of Temperature (SoT). SoC quantifies the amount of energy stored in a battery at a certain moment, and it is employed to approximate the remaining distance that may be covered. SoH describe the overall health or state of a rechargeable battery. It reveals how well a battery performs in comparison to its original state. SoT estimation keeps the battery temperature within a safe range, allowing it to reach a higher age and safety, which is critical for battery reliability. In this paper SoC, SoH, SoT estimation models for a lithium-ion battery have been developed using an improved EP-based R110-BLSTM approach. The Emperor Penguin based Residual Network-110 incorporated Bidirectional Long-Short Term Memory (EP-based R110-BLSTM) is ideal for estimating SoC, SoH, and SoT and features great accuracy, a quick estimation speed, and strong generalization capabilities. However, Extreme Learning Machine performance is heavily reliant on proper feature extraction. In order to enhance estimate performance by extracting the best features, Simulated-Annealing-based Golden Eagle optimization is utilized. Electric vehicle drive cycles are used to test the model's resilience to temperature changes. MATLAB 2018b software is used in the execution of this research. The results demonstrate that the proposed model performs better in terms of accuracy and has lower SoC, SoH, and SoT error rates than existing models. A thorough comparison between the recommended model and existing methods is also made, further demonstrating the proposed model's superiority. [ABSTRACT FROM AUTHOR]

Using titanium tetrachloride as the raw material, TiCl4 was prepared into a 0.5mol/L aqueous solution in an ice water bath under weakly alkaline conditions. The precipitate was obtained by low-temperature hydrolysis, and the precipitate was dried in a vacuum oven at 80 °C and roasted at low temperature of 400 °C for 12 hours to obtain white powder. Structural characterization was carried out through X-ray diffraction (XRD). The morphology was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The obtained sintered products were combined with metal lithium electrode materials and polyethylene separators to construct a semi battery system for battery performance testing. The results showed that titanium tetrachloride was used as the raw material to achieve slow hydrolysis under low temperature conditions, and then subjected to long-term low-temperature calcination to obtain a white powder of nanoscale rutile type TiO2, which has advantages such as small particle size, good dispersibility, narrow particle size distribution, and good sphericity. This product has a first discharge specific capacity of 169 mAh/g at 0.2 charge and discharge, and a discharge specific capacity of 69 mAh/g at 5 C, with a capacity retention rate of 91.69%, respectively. Its electrochemical performance is much higher than that of commercial TO2. Research has shown that the method of preparing TiO2, based on slow hydrolysis low-temperature sintering mechanism is a simple, low-cost, and suitable process for large-scale production. [ABSTRACT FROM AUTHOR]

In this paper, we design a binder GG-CA-GLY (abbreviation: GGC) for silicon negative electrode by guar gum as the backbone chain with self-healing function, combing and straightening the guar molecular chain of guar gum through the plasticizing effect of glycerol. The condensation reactions between the exposed hydroxyl sites of guar gum and the carboxyl groups of citric acid create a stronger hydrogen bond, so as to achieve the effect of self-healing and cope with the serious volume expansion effect of silicone-based materials. [Display omitted] • A easy polycondensation reaction is used to create a mechanically strong self-healing polymer (GGC). • GGC adhesives have excellent mechanical properties and facilitate rapid self-healing. • GGC@Si electrodes were prepared with excellent rate capability and higher cycling stability. • GGC adhesives have the ability to repair cracks and other damage on prepared silicon anodes, returning them to their original state. Silicon is a promising anode material for lithium-ion batteries with its superior capacity. However, the volume change of the silicon anode seriously affects the electrode integrity and cycle stability. The waterborne guar gum (GG) binder has been regarded as one of the most promising binders for Si anodes. Here, a unique steric molecular combing approach based on guar gum, glycerol, and citric acid is proposed to develop a self-healing binder GGC, which would boost the structural stability of electrode materials. The GGC binder is mainly designed to weaken van der Waals' forces between polymers through the plasticizing effect of glycerol, combing and straightening the guar molecular chain of GG, and exposing the guar hydroxyl sites of GG and the carboxyl groups of citric acid. The condensation reaction between the hydroxyl sites of GG and the carboxyl groups of citric acid forms stronger hydrogen bonds, which can help achieve self-healing effect to cope with the severe volume expansion effect of silicone-based materials. Silicon electrode lithium-ion batteries prepared with GGC binders exhibit outstanding electrochemical performance, with a discharge capacity of up to 1579 mAh/g for 1200 cycles at 1 A/g, providing a high capacity retention rate of 96%. This paper demostrates the great potential of GGC binders in realizing electrochemical performance enhancement of silicon anode. [ABSTRACT FROM AUTHOR]

In real life applications, using electronics switch in high voltage and high current applications is very challenging due to limitation of hardware and safety. In this manuscript, a hybrid system is proposed for battery management system (BMS) used in electric vehicle (EV) is a critical part for effective utilization of the energy storage. The proposed hybrid technique is joint performance of fuzzy logic controller (FLC) and Artificial eco-system algorithm (AEO), hence it is called FLTAEO technique. The existing battery management control system is not effective for the Induction motor drive based solar PV powered electric vehicle system. In this manuscript, the control strategies of charging with discharging of Li-ion batteries coupled Induction motor with solar PV power are used with proposed technique. Here, the introduced FLC and AEO are discussed with detailed control abilities for charging/discharging. The simulations are done in MATLAB platform to analyze the superiority of the proposed method. Here, BESS life comparison, fitness function for charging, fitness function for discharging, error Distribution, RMSE calculation for 1 hour and 5 minutes ahead prediction interval (PI) are analyzed and compared with various existing techniques, like Emperor Penguin Algorithm (EPA) and Seagull Optimization Algorithm (SOA). [ABSTRACT FROM AUTHOR]

Antimony（Sb） has high theoretical specific capacity and moderate reaction potential, but poor cycling stability and rate performance caused by large volume expansion and sluggish reaction kinetics limit its development in alkali‐ion batteries. The construction of carbon/Sb composites can solve this problem, but the traditional single carbon composite and poor Sb/carbon interface have limited promotion. Here, under the guidance of theoretical calculations, a strategy of hierarchical double carbon composite is proposed to enhance the performance of Sb anode, and systematically reveal the lithium/sodium ions (Li+/Na+) storage mechanism of Sb in complex composite system. Sb nanoparticles (Sb NPs) are encapsulated in carbon sphere matrix with strong interfacial chemical bond to form the first level composite material, and then the highly conductive and mechanically strong graphene is used as a three‐dimensional skeleton network to connect the first level composite to form the second level composite material. The hierarchical double carbon/Sb composite exhibits excellent rate (228 mAh g−1 @ 20 A g−1) and long cycling performance (373.7 mAh g−1 @ 2 A g−1 after 2200 cycles, capacity retention of 93.1%). This work may expand structural design and interface regulation of Sb/C composites and providing theoretical guidance for metal anodes development. [ABSTRACT FROM AUTHOR]

Smart multi-layer architectures were developed using spray coating of carbon nanotube-rich layers and carbon nanotube-free layers, layer-by-layer, boosting electrochemical charge/discharge kinetics of high mass loading lithium ion battery electrodes. [Display omitted] The ability of lithium ion batteries (LIBs) to provide rapid charging characteristics while retaining a substantial energy storage capacity is of paramount significance for their applicability in portable smart electronic devices. In this research, an effective approach to enhance re-charging rates of LIB cells was developed through incorporating carbon nanotube (CNT) conductivity boosters strategically into Li 4 Ti 5 O 12 (LTO) electrodes. A layer-by-layer spray coating was exploited to manufacture multi-layer architectures that comprise sequential, discrete electrode layers of CNT-rich LTO and CNT-free LTO, aiming at promoting charge transfer kinetics of high mass loading electrodes. Initially, the optimal proportion of a CNT-rich layer and its best location within multi-layer electrode structures were investigated in half-cell configurations. The best performing multi-layer was then paired with a spray-coated LiFePO 4 (LFP) positive electrode in full-cell LIBs, offering attractive power performance of ∼ 1500 W/kg that outperformed conventional LTO || LFP combinations. [ABSTRACT FROM AUTHOR]

The driving and charging behaviours of Electric Vehicle (EV) users exhibit considerable variation, which substantially impacts the battery degradation rate and its root causes. EV battery packs undergo second-life application after first-life retirement, with SoH measurements taken before redeployment. However, the impact of the root cause of degradation on second-life performance remains unknown. Hence, the question remains whether it is necessary to have more than a simple measure of state of health (SoH) before redeployment. This article presents experimental data to investigate this. As part of the experiment, a group of cells at around 80% SoH, representing retired EV batteries, were cycled using a representative second-life duty cycle. Cells with a similar root cause of degradation in the first life (100–80% SoH) exhibited the same degradation rate in second life after being cycled with the same duty cycle during the second life. When the root cause of degradation in the first life is different, the degradation rate in the second life may not be the same. These findings suggest that the root cause of a cell's first-life degradation impacts how it degrades in its second life. Postmortem analysis (photographic and SEM images) reveals the similar physical condition of negative electrodes which have similar degradation rates in their second life cycle. This demonstrates that cells with a similar first life SoH and root cause of degradation indeed experience a similar life during their second life. The experimental results, along with the subsequent postmortem analysis, suggest that relying solely on SoH assessment is insufficient. It is crucial to take into account the root causes of cell degradation before redeployment. [ABSTRACT FROM AUTHOR]

Herein, we propose a comprehensive chemical experiment that include the preparation, characterization and lithium storage performance evaluation of mesoporous carbon-coated iron oxide nanoparticles. Students are guided to acquaint themselves with the characterization methods of material structure, the operation of battery assembly and battery testing technique. This experiment will disclose the interrelationship between material structure and performance to students, and cultivate their experiment skills, scientific literacy, and practical innovation ability. Furthermore, this experiment serves as a gateway for students to explore the frontier in new energy, and stimulate their scientific interest. Therefore, this experiment is recommended as a comprehensive chemical experiment course for senior undergraduates majoring in materials chemistry or applied chemistry. [ABSTRACT FROM AUTHOR]

Separator plays a key role in the safety and performances of lithium-ion batteries with the needs of good thermal stability and wettability. Compared with the commercial separator mainly made by polyolefins in organic solvents, the electrospinning of lignin/polyvinyl alcohol in an aqueous solution has been investigated as a green and economically viable method to produce high-performance separators without any other chemical additives. Lignin/polyvinyl alcohol (mass ratio: 3:7) nanofiber separators outperform commercial polypropylene separators in terms of porosity (71 %), liquid absorption (373 %), and outstanding thermal stability at 200 °C. Additionally, Li-ion battery cells that were constructed using different separators were assessed to demonstrate favorable electrochemical performance. The results showed that fabricated Li-ion battery with Lignin/polyvinyl alcohol (mass ratio: 3:7) nanofiber separators possesses a superior capacitance of 154.1 mA h g−1 at 0.5 C, and maintained outstanding cycle stability after 50 times of charging and discharging process at 0.5 C with the capacitance retention rate up to 98.7 %. The facile and sustainable synthesis strategy of lignin-based separator materials for Li-ion batteries developed in this work provides new perspectives for related research, especially based on environmentally friendly aqueous systems. [ABSTRACT FROM AUTHOR]

Definition: Scanning electrochemical microscopy (SECM) is a type of scanning probe microscopy (SPM) where an electrochemical reaction at a microelectrode is used to generate information about an electrochemically (in)active surface in its immediate vicinity. Careful preparation and knowledge of the microelectrode response as well as the application of a suitable method enable the study of spatially resolved electrochemical kinetics or the electrocatalytic activity of any structure or material. In addition to a wide range of other applications, the method has become particularly well established in the research field of electrochemical energy storage and conversion. [ABSTRACT FROM AUTHOR]

Due to advancements in e-mobility technology, more and more people are opting to use electric vehicles. As there is a lack of a backup power supply, energy storage device is especially important for onboard systems. So, battery management systems become an important aspect for these energy storage devices. State-of-charge (SoC) estimation is a vitally significant assessment index in BMS because it is one of the most critical attributes that represents the working state of power batteries in EVs. In addition to the quick display of the remaining battery capacity to the user, accurate knowledge of SoC exerts further control over the charging/discharging process, which may be used to enhance battery life. This can be done in order to increase the longevity of the battery. According to the findings of this study, the error while estimating the SoC has been reduced to near about zero. The effect of resistance, temperature and C-rate on SoC has been also considered in this study. These findings show that the resistance is proportional to SoC below 80%, and after that, it becomes nonlinear. The SoC calculation using optimized deep learning strategy is proposed in this study. This approach helps to limit the margin of error in the calculation of SoC. It has also taken into account the occurrence of changes in SoC as a result of the changing C-rate, temperature, and resistance. Hence, this study helps to offset the negative effects of inaccurate SoC prediction. [ABSTRACT FROM AUTHOR]

In this paper, manganese is used as a medium to connect pyrolusite with lithium-ion batteries, which not only meets the needs of comprehensive utilization of global strategic mineral resources, but also maximizes the performance of lithium-ion batteries under the goal of global carbon neutralization and carbon peak. Firstly, the optimum experimental conditions for sulfuric acid roasting of pyrolusite were investigated by single factor experiment and orthogonal experiment: the roasting temperature was 650 °C, the roasting time was 4 h, the acid-to-ore ratio was 2:1, and the water-to-ore ratio was 0.6:1. The roasting temperature plays a major role. Then, LMF x P-C (x = 0, 1/4, 1/8, 1/12, 1/24) cathode materials were prepared by adding different mass Fe elements with manganese element purified from pyrolusite as manganese source. Its electrochemical analysis was carried out: the capacity retention rate of LMF 1/4 P–C cathode material is 92.54% after 500 cycles. After a total of 150 times of rate tests at different rates, the discharge specific capacity of LMF 1/4 P–C can still reach 148.5 mAh g−1. At the same time, the EIS results show that the values of R e and R ct of LMF 1/4 P–C cathode material are the smallest compared with other materials. Finally, the LMF x P-C cathode material was analyzed by first-principles, and the optimal Fe doping amount was theoretically predicted. The crystal structure, bonding and density of states of the LMF x P-C cathode material were calculated and discussed. The results show that when the Fe doping amount is 1/4, the LMF x P-C system has the highest conductivity and the best electrochemical performance. The calculation results are consistent with the experimental results. [ABSTRACT FROM AUTHOR]

[Display omitted] • Low-cost melamine-boric acid (MBA) supramolecular hydrogels are self-assembled with a superfast speed in dozens of seconds under room temperature. • In-situ real-time observation of the nucleation and growth of MBA supramolecules is constructed by using polarizing microscope. • The boron nitride and bacterial cellulose (BN/BC) composite aerogel shows excellent flame-retardant performance, electrolyte-wetting ability and high mechanical property. • The BN/BC composite aerogel as the separator enable the derived lithium ion battery with excellent electrochemical property and high safty. Traditional polyolefin separators for lithium-ion batteries (LIBs) often experience limited thermal stability and intrinsic flammability, resulting in great safety risks during their usage. Therefore, it is highly important to develop novel flame-retardant separators for safe LIBs with high performance. In this work, we report a flame-retardant separator derived from boron nitride (BN) aerogel with a high BET surface area of 1127.3 m2 g−1. The aerogel was pyrolyzed from a melamine-boric acid (MBA) supramolecular hydrogel, which was self-assembled at an ultrafast speed. The in-situ evolution details of the nucleation-growth process of the supramolecules could be observed in real-time using a polarizing microscope under ambient conditions. The BN aerogel was further composited with bacterial cellulose (BC) to form a BN/BC composite aerogel with excellent flame-retardant performance, electrolyte-wetting ability and high mechanical property. By using the BN/BC composite aerogel as the separator, the developed LIBs exhibited high specific discharge capacity of 146.5 mAh g−1 and excellent cyclic performance, maintaining 500 cycles with a capacity degradation of only 0.012% per cycle. The high-performance flame-retardant BN/BC composite aerogel represents a promising candidate for separators not only in LIBs but also in other flexible electronics. [ABSTRACT FROM AUTHOR]

Lithium iron silicate (Li 2 FeSiO 4) has high theoretical capacity of 332 mAh∙g-1 upon full extraction of two lithium ions, which is accompanied by high delithiation potential and large volume change. Sulfur modification could be an effective approach for stabilizing Li 2 FeSiO 4 cathodes. A series of carbon-coated Li 2 FeSiO 4 samples were prepared through a hydrothermal and solid-state reaction route at a fixed sucrose content (14 wt% carbon) with varying amounts of sublimed sulfur at 5, 10, 15, 20 and 25 at%. The crystal structures, chemical compositions, microstructures and electrochemical performances of the differently sulfur-modified Li 2 FeSiO 4 /C were systematically investigated. The sulfur-carbon co-modifications and possible existing chemical states of sulfur are discussed in terms of the surface and near-bulk modifications. It was found that all the samples exhibited a monoclinic P 2 1 structural Li 2 FeSiO 4 , while the sulfur contents over 10 at% formed impure phases such as iron sulfides (Fe 1-x S) and lithium metasilicate (Li 2 SiO 3). Furthermore, three types of sulfur states could be found when sulfur and carbon were added simultaneously into Li 2 FeSiO 4. The surfaces were predominated by S–C and S–O–C, indicating the sulfur-carbon co-modification, which would reduce the resistance at the solid/electrode interface (SEI) but increase the charge transfer resistance. Near the bulk, the enhanced interactions between sulfur and iron S–Fe(−S) or sulfur and silicon S–Si(−O) may lead to the formation of possible impurities or oxygen substitution by sulfur. The former is detrimental as the effective sulfur amount is reduced, while the latter is beneficial to improve specific capacity and cycle stability. The overall performance of sulfur-carbon co-modified sample is influenced complicatedly by the sulfur content. The best initial discharge capacity of 152.3 mAh∙g-1 was obtained with 5 at% sulfur modification, while the best overall performance, showing a typical warm-up response and good cycle stability, was observed with 15 at% sulfur modification. [ABSTRACT FROM AUTHOR]

The growing demand for cheap, safe, recyclable, and environmentally friendly batteries highlights the importance of the development of organic electrode materials. Here, we present a novel redox-active polymer comprising a polyaniline-type conjugated backbone and quinizarin and anthraquinone units. The synthesized polymer was explored as a cathode material for batteries, and it delivered promising performance characteristics in both lithium and potassium cells. Excellent lithiation efficiency enabled high discharge capacity values of >400 mA g−1 in combination with good stability upon charge–discharge cycling. Similarly, the potassium cells with the polymer-based cathodes demonstrated a high discharge capacity of >200 mAh g−1 at 50 mA g−1 and impressive stability: no capacity deterioration was observed for over 3000 cycles at 11 A g−1, which was among the best results reported for K ion battery cathodes to date. The synthetic availability and low projected cost of the designed material paves a way to its practical implementation in scalable and inexpensive organic batteries, which are emerging as a sustainable energy storage technology. [ABSTRACT FROM AUTHOR]

In the recent years, MXenes (2D transition metal carbides, carbon nitrides and nitrides) and its precursor MAX phases have been widely investigated in electrochemical research. In this research, we successfully prepared a core-shell structured compound——Ti 3 C 2 @Ti 2 SnC/CNFs (MXene@TSC/C) as an anode material for lithium ion battery via electrospinning method. Results showed that this type of compound has a specific capacity of 288.9 mAh·g−1 at the current density of 0.4 A g−1 after 300 cycles, accompany with a retention rate of capacity of 105.4% in the rate performance test. These performances were benefit from the core-shell structured CNFs and Ti 3 C 2 MXenes. This work supported a novel way to improve the electrochemical property of MXene and MAX phases, which was expected to further explored. [ABSTRACT FROM AUTHOR]

MoO 3 is a kind of promising cathode material for lithium-ion batteries (LIBs), owing to its high specific capacity (279 mA h g−1) and layered structure. However, low electrical conductivity and sluggish reaction kinetics results in poor rate and Li-ions storage capability. The introduction of oxygen vacancies (OVs) can promote Li+ diffusion, and produce great electrical conductivity. Here, we report a strategy to synergize the merits of OVs by pulsed laser deposition (PLD) by adjusting oxygen partial pressures (2～20 Pa). The appropriate OVs concentration not only significantly approves electrochemical performance but also increases pseudocapacitance contribution. The Li-ion diffusion coefficient of MoO 3−x is remarkably improved by one or two orders of magnitude compared with that of MoO 3. Therefore, this facile and efficient strategy on OVs could afford a reference for other metal oxides for high-performance electrode materials. [ABSTRACT FROM AUTHOR]

Hollow Ni 0.75 Zn 0.25 Fe 2 O 4 nanospheres with a diameter of about 250–300 nm and thickness of 30–40 nm have been successfully fabricated through a PVP (polyvinylpyrrolidone)-assisted hydrothermal strategy. PVP plays an important role in the formation of hollow structure and a plausible formation mechanism of hollow Ni 0.75 Zn 0.25 Fe 2 O 4 nanospheres is also proposed in this paper. The as-fabricated hollow Ni 0.75 Zn 0.25 Fe 2 O 4 nanospheres display a good dispersibility and high specific surface area of 34.7 m2 g−1. Hollow Ni 0.75 Zn 0.25 Fe 2 O 4 nanospheres also demonstrate satisfactory cycle life and rate performance when evaluated as a lithium ion battery negative electrode. Namely, after 120 cycles, the discharge specific capacity is 1321.3 mAh g−1 at 200 mA g−1, and the capacity retention rate is as high as 99.2%. Furthermore, the average discharge capacities are 1482.5, 1451.5, 1330.9, 1232.3, 1031.2 and 944.8 mAh g−1 under the current densities of 100, 200, 500, 1000, 2000 and 4000 mA g−1, respectively. The promising electrochemical performance of the hollow Ni 0.75 Zn 0.25 Fe 2 O 4 nanosphere could be attributed to the unique hollow structure of nanospheres, which offers a higher specific surface area and shorten transmission pathways of electrons and ions, buffering the volume expansion during the Li+ insertion/desorption process. • Hollow Ni 0.75 Zn 0.25 Fe 2 O 4 have been fabricated by a hydrothermal strategy. • PVP plays an important role in the formation of hollow structure. • Hollow Ni 0.75 Zn 0.25 Fe 2 O 4 present enhanced electrochemical performance in LIBs. [ABSTRACT FROM AUTHOR]

Li3VO4 (LVO) is a highly promising anode material for lithium-ion batteries, owing to its high capacity and stable discharge plateau. However, LVO faces a significant challenge due to its poor rate capability, which is mainly attributed to its low electronic conductivity. To enhance the kinetics of lithium ion insertion and extraction in LVO anode materials, a conductive polymer called poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is applied to coat the surface of LVO. This uniform coating of PEDOT:PSS improves the electronic conductivity of LVO, thereby enhancing the corresponding electrochemical properties of the resulting PEDOT:PSS-decorated LVO (P-LVO) half-cell. The charge/discharge curves between 0.2 and 3.0 V (vs. Li+/Li) indicate that the P-LVO electrode displays a capacity of 191.9 mAh/g at 8 C, while the LVO only delivers a capacity of 111.3 mAh/g at the same current density. To evaluate the practical application of P-LVO, lithium-ion capacitors (LICs) are constructed with P-LVO composite as the negative electrode and active carbon (AC) as the positive electrode. The P-LVO//AC LIC demonstrates an energy density of 107.0 Wh/kg at a power density of 125 W/kg, along with superior cycling stability and 97.4% retention after 2000 cycles. These results highlight the great potential of P-LVO for energy storage applications. [ABSTRACT FROM AUTHOR]

Ni-rich layered cathode materials LiNixCoyMn(1-x–y)O2 (x ≥ 0.8) suffer from capacity decay due to structural deterioration during electrochemical cycling. To overcome these problems, the fast-ion conductor Li0.33La0.56TiO3 (LLTO) is coated on the surface of LiNi0.83Co0.12Mn0.05O2 (NCM83) cathodes through the sol–gel method, which can stabilize the electrode/electrolyte interface of cathode materials and facilitate Li+ transport and charge transfer. As a result, the LLTO-coated NCM83 exhibits better cycle stability and higher rate performance. The NCM83 modified by 5 wt% LLTO has the discharge capacity of 185.9 mAh g−1 at 1C rate after 100 cycles and with higher capacity retention of 92.9% than the pristine NCM83 of 86.2%, and as well as the 5 wt% LLTO-coated NCM83 has a higher Li+-insert diffusion coefficient of 1.143 × 10−11 cm2 s−1 than the pristine NCM83 of 8.757 × 10−12 cm2 s−1. Therefore, the fast-ion conductor LLTO coating strategy shows great potential in improving the performance of Ni-rich layered cathode materials. [ABSTRACT FROM AUTHOR]

Addressing the oxidation state of functional materials such as transition metal oxides is a current critical challenge and requires new methodologies to characterize their electronic structure within surface to bulk resolution at the nanometer scale. One approach to this issue is the combination of co‐localized soft and hard X‐ray photoelectron spectroscopies for a non‐destructive depth profiling. In this work, we demonstrate the capability to characterize the oxidation state of cobalt in LiCoO2 thin films, a model electrode material in the Li‐ion battery field, within the first 15 nm. The capability of the methodology to address the surface evolution of the cobalt oxidation state is tested through a proof of concept surface modification introduced by Ar‐ion sputtering. To address the cobalt local electronic structure at different depths from the extreme surface, we exploited Auger‐free Hard X‐ray photoelectron spectroscopy (HAXPES) spectra to fit the Co 2p core‐level features in the X‐ray photoelectron spectroscopy (XPS) spectra. This approach may pave the way for a better understanding of the surface electronic structure changes in transition metal oxides driven by their applications in a broad range of technologies. [ABSTRACT FROM AUTHOR]

[Display omitted] Anodes based on silicon/carbon composites promise their commercial prospects for next-generation lithium ion batteries owing to their merits of high specific capacity, enhanced ionic and electronic conductivity, and excellent compatibility. Herein, a series of carbonaceous framework/Si composites are designed and prepared by rational waste utilization. N, P codoped foam-like porous carbon/Si composites (FPC@Si) and N, P codoped carbon coated Si composites (NPC@Si) are fabricated by utilizing expired milk powder as a carbon source with facile treatment methods. The results indicate that the porous carbon skeleton and carbon shell can improve the conductivity of Si and stabilize the solid electrolyte interfaces to avoid direct contact between active material and electrolyte. Moreover, the influence of drastic volume expansion of Si on the anode can be efficiently alleviated during charge/discharge processes. Therefore, the Si/C composite electrodes present excellent long-term cycling stability and rate capability. The electrochemical performance shows that the reversible capacity of FPC@Si and NPC@Si can be respectively maintained at 587.3 and 731.2 mAh g−1 after 1000 charge/discharge cycles under 400 mA g−1. Most significantly, the optimized Si/C composite electrodes exhibit outstanding performance in the full cell tests, promising them great potential for practical applications. This study not only provides a valuable guidance for recycling of waste resources, but also supports a rational design strategy of advanced composite materials for high-performance energy storage devices. [ABSTRACT FROM AUTHOR]

The recovery of critical metals from spent lithium‐ion batteries (LIBs) is important to sustainable development and environment protection. In this paper, sec‐octylphenoxyacetic acid (CA‐12) was first used to recover valuable metals in LIBs. The effects of phase modifier, initial feed pH, extraction kinetics and thermodynamics, CA‐12 concentration and saponification degree were studied and optimized. Under the optimal conditions, 99 % of nickel, cobalt and manganese were co‐extracted to the organic phase, and the loss of lithium was 7 %. The extracted metal ions could be stripped with 0.04 mol/L HCl equivalently. In the spent LIBs powder leaching experiment, leaching efficiencies of all components were greater than 95 %. In the impurity removal stage, extractant N902 was used to remove copper, while iron and aluminum were eliminated by hydrolysis. After two‐stage extraction, the total extraction efficiencies of nickel, cobalt and manganese reached 99.7 %, 99.4 %, 98.45 %, respectively. Finally, lithium in the raffinate was precipitated by saturated Na2CO3, the purity of recovered Li2CO3 was up to 97.7 %. After 5 times cycles, CA‐12 still maintained excellent extraction capacity, showing its potential application prospects for recovering critical metals form spent LIBs. [ABSTRACT FROM AUTHOR]

Silicon-containing polyester from tetramethoxysilane, ethylene glycol, and o-Phthalic anhydride were used as encapsulating materials for silicon nano powders (SiNP) via electrospinning, with Polyacrylonitrile (PAN) as spinning additives. In the correct quantities, SiNP could be well encapsulated in nano fibers (200–400 nm) using scanning electron microscopy (SEM). The encapsulating materials were then carbonized to a Si-O-C material at 755 °C (Si@C-SiNF-5 and Si@C-SiNF-10, with different SiNP content). Fiber structure and SiNP crystalline structure were reserved even after high-temperature treatment, as SEM and X-ray diffraction (XRD) verified. When used as lithium ion battery (LIB) anode materials, the cycling stability of SiNPs increased after encapsulation. The capacity of SiNPs decreased to ~10 mAh/g within 30 cycles, while those from Si@C-SiNF-5 and Si@C-SiNF-10 remained over 500 mAh/g at the 30th cycle. We also found that adequate SiNP content is necessary for good encapsulation and better cycling stability. In the anode from Si@C-SiNF-10 in which SiNPs were not well encapsulated, fibers were broken and pulverized as SEM confirmed; thus, its cycling stability is poorer than that from Si@C-SiNF-5. [ABSTRACT FROM AUTHOR]

Silicon （Si） has become the most promising anode material for the next generation lithium-ion battery because of its ultra-high theoretical specific capacity. However， the intercalation and removal of lithium-ions will cause a great change in the volume of silicon microparticles (SiMP)， which will lead to the pulverization of SiMP and irreversible attenuation of electrode capacity， which seriously limits the wide application of silicon based materials. A large number of reports in the past have shown that polymer binder can effectively overcome the “island effect” caused by the volume expansion of SiMP . It could maintain the integrity of the electrode in the charge-discharge process， and then improve the electrochemical performance of the electrode. According to the structure classification of polymer binders， they can be roughly divided into four categories， linear， branched， cross-linked and conjugated. When the binders with different molecular structures are used as silicon-based negative electrode， the electrodes show different electrochemical properties. Particularly， when polymer binders with multiple molecular structures are designed， the practical application of silicon-based negative electrodes will be greatly promoted. By analyzing the effects of various polymer binders on the electrochemical properties of silicon anode， the differences of binders with different molecular structures can be clearly obtained， and then provide ideas for the development of silicon anode polymer binder in the future. Finally， this paper proposes the design direction of the next-generation polymer binder to promote its development towards large-scale application and industrial production. [ABSTRACT FROM AUTHOR]

Copper phosphide has shown remarkable development potential in the anode materials of lithium ion batteries (LIBs) due to its high mass/volume ratio capacity. Nevertheless, the low conductivity and volumetric expansion in the cycling process restrict its practical application. Herein, we ingeniously designed and successfully prepared copper phosphide (Cu 3 P)@carbon (C) nanocomposite with multi-stage pore inverse opals (Cu 3 P@C MSPIOs), including possessed the ordered macropores with the mean aperture of ∼100 nm induced by polystyrene (PS) sphere templates and the mesoporous structure with the pore size range of 3.0-9.5 nm and 16–27 nm derived from metal-organic framework (MOF) precursor. Compared to the Cu 3 P@C particles prepared without PS sphere templates, the Cu 3 P@C MSPIOs as the anode materials demonstrated exceptional lithium storage performance. At a high current density of 2 A g-1, the discharge specific capacity of Cu 3 P@C MSPIOs was 295 mA h g-1 in the 1st cycle while that dropped to 204 mA h g-1 during the 2nd one, and then gradually stabilized. After 1500 cycles, the discharge specific capacity can still reach to 166.3 mA h g-1, maintaining 81% capacity compared to the 2nd discharge specific capacity, which indicates the Cu 3 P@C MSPIOs as the anode material presented good cycling stability. Apparently, the multi-stage pore structure, which can effectively resolve the volumetric change problem during lithium ion (Li+) intercalation/deintercalation as well as facilitate contact between electrolyte and anode, is primarily responsible of the superior Li-ion storage property of Cu 3 P@C MSPIOs. At the same time, MOF derived carbon can improve electrical conductivity, accelerate the formation of a stable solid electrolyte interface membrane and also provide buffer layers to further alleviate volumetric expansion. [ABSTRACT FROM AUTHOR]

The thermal runaway (TR) of lithium-ion batteries (LIBs) has become a potential danger of serious fire and explosion, which threatens people's life and property safety. Therefore, the timely and effective methods are urgently needed to suppress this hazardous process. Therefore, it is of great significance to develop efficient TR inhibitors. Liquid nitrogen (LN) has been widely concerned as an efficient and environmentally friendly fire extinguishing medium. In this paper, TR device of LIBs in open space is investigated, and the effectiveness of LN in restraining the TR of LIBs is studied under different heating power, spray direction, state of charge (SOC) and spray time. The results show that LN has excellent inhibition effect on TR, and the mean cooling rate of LIBs surface temperature decreases with the increase of heating power. Vertical spraying is better than horizontal spraying for cooling and extinguishing. The average cooling rate of battery surface temperature decreases with the increase of SOC. The average cooling rate of battery surface temperature decreases with the shortening of the time. [ABSTRACT FROM AUTHOR]

In order to explore the thermal safety of lithium ion batteries (LIBs), a series of thermal runaway tests for single 32,650 LIB with different state of charges (SOC) and double 32,650 LIBs with different spacings from 0 to 2 D (D is 32 mm) are conducted in this work. It is clearly shown that the increasing SOC decreases the onset and duration time of the jet fire stages, increasing the mass loss and flame area in the jet fire stages. With the spacing decreases, the thermal effect of the flames on the LIBs is enhanced, which decreases the onset and duration time of the jet fire stages, increasing the mass loss and strengthening the combustion in the two second jet fire stages. In addition, according to the flame surface area and mass loss rate (MLR), the heat of combustion of LIB is estimated as Δ H c = 8.21 kJ g - 1 , and a simplified model is derived to predict the heat release rate (HRR) of LIBs. The above results provide a theoretical foundation for quantitative assessment of the fire risk of the LIBs. [ABSTRACT FROM AUTHOR]

The composite membrane (PDFP-POPM) based on the blending of poly(vinylidene fluoride-co-hexafluoropropylene) (PDFP) and POPM (the copolymer of organic palygorskite and methyl methacrylate) was prepared by the phase-inversion method, and a gel polymer electrolyte (GPE) was obtained when the PDFP-POPM was activated by absorbing liquid electrolyte (LE). The SEM morphologies showed that the PDFP-POPM had a porous structure. The XRD results indicated that PDFP-POPM was an amorphous polymer and that the POPM could effectively suppress the crystallization of PDFP. The lithium ion transference number of GPE was higher than that of pristine POPM- and PDFP-based GPE. When the mass concentration of PDFP was 40%, the uptake of the PDFP-POPM and ionic conductivity of GPE reached the maximum values of 164% and 2.37 mS/cm, respectively. The electrochemical stability window of Li/GPE/SS batteries was over 4.7 V (vs. Li+/Li), and the Li/40PDFP-POPM GPE/LiFePO4 battery exhibited good cycling performance. The discharge capacity of the battery was 145mAh g−1 after 100 cycles and the columbic efficiency was over 95%. [ABSTRACT FROM AUTHOR]

As a potential anode material for lithium-ion batteries (LIBs), metal tin shows a high specific capacity. However, its inherent "volume effect" may easily turn tin-based electrode materials into powder and make them fall off in the cycle process, eventually leading to the reduction of the specific capacity, rate and cycle performance of the batteries. Considering the "volume effect" of tin, this study proposes to construct a carbon coating and three-dimensional graphene network to obtain a "double confinement" of metal tin, so as to improve the cycle and rate performance of the composite. This excellent construction can stabilize the tin and prevent its agglomeration during heat treatment and its pulverization during cycling, improving the electrochemical properties of tin-based composites. When the optimized composite material of C@Sn/NSGr-7.5 was used as an anode material in LIB, it maintained a specific capacity of about 667 mAh g−1 after 150 cycles at the current density of 0.1 A g−1 and exhibited a good cycle performance. It also displayed a good rate performance with a capability of 663 mAh g−1, 516 mAh g−1, 389 mAh g−1, 290 mAh g−1, 209 mAh g−1 and 141 mAh g−1 at 0.1 A g−1, 0.2 A g−1, 0.5 A g−1, 1 A g−1, 2 A g−1 and 5 A g−1, respectively. Furthermore, it delivered certain capacitance characteristics, which could improve the specific capacity of the battery. The above results showed that this is an effective method to obtain high-performance tin-based anode materials, which is of great significance for the development of new anode materials for LIBs. [ABSTRACT FROM AUTHOR]

Development of high-performance lithium-ion batteries (LIBs) is boosted by the needs of the modern automotive industry and the wide expansion of all kinds of electronic devices. First of all, improvements should be associated with an increase in the specific capacity and charging rate as well as the cyclic stability of electrode materials. The complexity of experimental anode material selection is now the main limiting factor in improving LIB performance. Computer selection of anode materials based on first-principles and classical molecular dynamics modeling can be considered as the main paths to success. However, even combined anodes cannot always provide high LIB characteristics and it is necessary to resort to their alloying. Transmutation neutron doping (NTD) is the most appropriate way to improve the properties of thin film silicon anodes. In this review, the effectiveness of the NTD procedure for silicene/graphite (nickel) anodes is shown. With moderate P doping (up to 6%), the increase in the capacity of a silicene channel on a Ni substrate can be 15–20%, while maintaining the safety margin of silicene during cycling. This review can serve as a starting point for meaningful selection and optimization of the performance of anode materials. [ABSTRACT FROM AUTHOR]

LiFePO4 is one of the most widely used cathode materials for lithium‐ion batteries, and the low‐temperature performance of LiFePO4‐based batteries has been widely studied in recent years. Herein, a 3.5 Ah pouch‐type full battery was assembled using LiFePO4 as the cathode and artificial graphite as the anode. For the LiFePO4‐based cathode, carbon‐coated aluminum foil was selected as the current collector, and a 0D–1D–2D multi‐scale conductive network was introduced into the electrode. Notably, both the carbon‐coated current collector and novel conductive network could significantly reduce the internal resistance of the LiFePO4‐based battery, thus improving its electrochemical dynamics and low‐temperature performance. This paper provides a theoretical basis for the development of low‐temperature LiFePO4‐based batteries. [ABSTRACT FROM AUTHOR]

Electromobility makes batteries with a high energy density more and more important. In this context, lithium‐sulfur batteries are among the most promising energy storage devices of the future. However, there are still numerous problems to be solved before lithium‐sulfur batteries can be put into practice. Some of these problems and the general functionality of lithium sulfur batteries can be demonstrated in model experiments. [ABSTRACT FROM AUTHOR]

The Zn-doped LNO cathode material was synthesized by sol-gel method. The effects of doping different amounts of Zn2+ on the properties of LNO were investigated. The results show that the sample doped with 2 mol% Zn (LNO-2Zn) delivers enhanced cycling performance and rate capability. The capacity retention rate for doped sample is 80.0% at 1 C rate after 100 cycles, which is higher than 74.8% for pristine LNO. Pristine LNO delivers a discharge capacity of only 48 mAh/g at 10C, which is much lower than that of 112.1 mAh/g of LNO-2Zn under the same condition. The introduction of Zn2+ ion reduces the degree of Li/Ni mixing, accelerates the lithium ion transfer, and slows down the harmful phase transition, thereby enhancing the electrochemical performance of LNO. [ABSTRACT FROM AUTHOR]

As an olivine‐based cathode with high discharge platform and theoretical capacity, Li3V2(PO4)3's (LVP's) low conductivity and excessive grain size are the important factors hindering its development in the battery field. Halloysite nanotubes (HNTs) is a natural and cheap nanotube‐like material with large specific surface area and abundant surface nucleation sites, which can cooperate with conductive carbon layer to solve the deficiency of LVP. In this paper, we design a cathode material for in‐situ growth of LVP on HNTs (LVP@HNTs) and demonstrate that it has the appropriate particle size and the excellent specific surface area in the mass ratio of LVP to HNTs is 2:1. The capacity retention rate of LVP@HNTs‐2 reached almost 100% (97.0 mAh g−1) after 100 cycles at a low rate of 0.5 C. Moreover, its specific discharge capacity is 89.3 mAh g−1 at a high rate of 20 C and its capacity retention rate is as high as 90.1% (80.5 mAh g−1) after 5,000 cycles, showing that the LVP@HNTs‐2 has marvelous rate capability and cycle stability. This study provides an innovative strategy for the development of the high‐performance cathode materials with low‐cost, excellent rate capability, and cycle stability of lithium ion batteries. [ABSTRACT FROM AUTHOR]

A novel integration of a proton exchange membrane (PEM) fuel cell with lithium ion batteries is presented for a hydrogen electric vehicle. The performance of the PEM fuel cell is affected by the temperature of input air that is drawn from the environment for electrochemical reaction with the hydrogen. Preheating the input air before it enters the PEM fuel cell can potentially improve its performance, especially during cold weather conditions. In addition, removing the heat generated in the lithium ion battery cells is necessary for efficient, safe and long-term operation of the hydrogen electric vehicle. In this context, this study introduces an air-cooled battery thermal management system in which the air is taken from the environment, preheated through cooling of batteries and then used in the PEM fuel cell stack. Both the PEM fuel cell and the lithium ion battery systems are analyzed to investigate the compatibility and applicability of the proposed system. Also, the PEM fuel cell electrical power output and energy efficiency are assessed through varying the operating conditions. It is found that, at a current density of 0.4 A/cm2, the energy efficiency of the PEM fuel cell improves from 45% to 48% by preheating the air from 10 °C to 40 °C. Furthermore, during discharge of the lithium ion battery, the cooling air removes an average heat generation rate of 3.5 W per unit area of the lithium ion battery to maintain the battery temperature at around 25 °C. • A novel PEM fuel cell-battery integration is proposed for a hydrogen vehicle. • Heat generation in lithium ion battery is recovered by preheating fuel cell air. • The applicability and compatibility of the proposed system are investigated. • A parametric study is performed for the integration in hydrogen electric vehicle. [ABSTRACT FROM AUTHOR]

We have studied the effect of doping with tin and titanium cations on the electrochemical performance of lithium-rich cathode materials. Samples for this investigation were prepared via coprecipitation of precursors, followed by solid-state reaction with a lithium and tin (titanium) source. The cathode materials have been characterized by X-ray diffraction, scanning electron microscopy, and X-ray microanalysis and tested in lithium half-cells in galvanostatic cycling mode at various current densities. The titanium-doped material had a considerably higher specific discharge capacity (270 mAh/g) in comparison with the undoped and tin-doped materials (230 mAh/g). As the charge/discharge current was raised, the titanium-doped sample exhibited the best cycling stability among all of the materials. In addition, both doped materials had a smaller voltage hysteresis in comparison with the undoped sample. [ABSTRACT FROM AUTHOR]

The modeling of battery energy storage systems (BESS) remains poorly researched, especially in the case of taking into account the power loss due to degradation that occurs during operation in the power system with a large penetration of generation from renewables and stochastic load from electric vehicles (EV). Meanwhile, the lifetime varies considerably from the manufacturer's claim due to different operating conditions, and also depends on the level of renewable energy sources (RES) penetration, cyclic operation, temperature, discharge/charge rate, and depth of discharge. Choosing a simplistic approach to the degradation model can lead to unreliable conclusions in choosing the best management strategy and significant investment and operating costs. Most existing BESS models in stationary applications either assume zero degradation costs for storage or simplify battery life to a linear function of depth of discharge (DOD), which can lead to additional error in estimating the cost of BESS degradation. The complexity of constructing a lifetime model of BESS is due to the presence of nonlinear degradation of BESS at the beginning and at the end of the lifetime, as well as the difficulty in obtaining a large amount of experimental data that are close to the real-world operating conditions for the construction of most models. This article analyzes the features of BESS that are specific to their operation in microgrids in terms of the influence of the main stress factors on the degree of BESS degradation. This study also provides a review of existing models for assessing battery degradation. [ABSTRACT FROM AUTHOR]

To solve the volume expansion problem of Fe3O4 nanoparticles (nmFe3O4), a facile, green, and industrializable preparation of N-doped carbon–encapsulated nmFe3O4 (nmFe3O4@N-doped C) is designed. This nmFe3O4@N-doped C is prepared through pyrolysis in nitrogen atmosphere of nmFe3O4 encapsulated by polyaniline (PANI@nmFe3O4) which is obtained through oxidative polymerization of aniline on the surface of nmFe3O4. In comparison with the capacity (113 mAh g−1 at 0.1C) of nmFe3O4, the nmFe3O4@N-doped C electrode exhibits a high reversible capacity of 400 mAh g−1 after 500 cycles. Even at 4C, the nmFe3O4@N-doped C electrode presents 160 mAh g−1 capacity, which is much higher than 30 mAh g−1 of the nmFe3O4 electrode. The results suggest that the N-doped carbon shell layer obtained from PANI is effective to inhibit volume expansion of nmFe3O4 core and maintain the electron and ion transport channels after long cycles. [ABSTRACT FROM AUTHOR]

The evolution of α-Fe 2 O 3 nanostructures from pie-like α-Fe 2 O 3 spheres (P-Fe 2 O 3), to hollow bowl-like α-Fe 2 O 3 spheres (B-Fe 2 O 3) and then to α-Fe 2 O 3 nanorings (R-Fe 2 O 3) have been successfully achieved through a facile hydrothermal approach and the designed hollow bowl-like α-Fe 2 O 3 (B-Fe 2 O 3) spheres exhibit great advantages as a LIB anode material. [Display omitted] The design and synthesis of hollow-nanostructured transition metal oxide-based anodes is of great importance for long-term operation of lithium ion batteries (LIBs). Herein, a special hollow bowl-like α-Fe 2 O 3 nanostructure is controllably synthesized through a facile hydrothermal technique and exhibits great electrochemical lithium storage performance when used as LIBs anode. Under a facile hydrothermal condition, α-Fe 2 O 3 nanostructures evolve from solid pie-like structure to hollow bowl-like structure and finally α-Fe 2 O 3 nanorings through the regulation of HPO 4 - derived from ionized Na 3 PO 4 ·12H 2 O and Ostwald ripening process. The designed hollow bowl-like α-Fe 2 O 3 nanostructure not only has the merits of hollow structure, which can accelerate the diffusion of lithium ions and electrons, but also shows great mechanical strength to disperse stress when compared to solid pie-like and ring-like α-Fe 2 O 3 nanostructures, which would avoid collapse during charge/discharge process. As a result, the as-synthesized hollow bowl-like α-Fe 2 O 3 nanostructure displays an initial reversible capacity of 1616 mAh g−1 at a current density of 1 A g−1, an excellent cycling performance with a reversible capacity of 1018 mAh g−1 after 500 cycles and an outstanding rate capability (68.1% capacity retention at current densities from 100 to 2000 mA g−1). This work provides not only a novel hollow bowl-like α-Fe 2 O 3 nanostructure with high specific surface area and stable structure as potential electrode materials for energy storage, but also a facile self-templated strategy free of any surfactants and templates for hollow nanostructures. [ABSTRACT FROM AUTHOR]

With the update of mobile and portable electronic equipment, people have higher requirements for improving the performance of lithium ion battery. As a key factor affecting the electrochemical performance of lithium storage-anode materials, its latest research has become a hot spot of widespread concern. Tn this paper, a-SnCHPOi• H,() was exfoliated into Sn (HPOi)■> nanosheets (SNS) by intercalation method, which retained the layered crystal structure and exposed more active sites for lithium storage. Furthermore, the SNS obtained by stripping were further combined with Sn nanoparticles with high specific capacity of lithium storage by electroless plating method. The results show that the Sn/SNS composite has better electrochemical performance of lithium storage than SNS. The specific capacity of Sn/SNS-111 is 475.7 mAh/g at ().1 A/g current density. The specific discharge capacity is 449.5 m Ah/g after 5()() cycles at ().2 A/g current density, and the capacity retention rate is 63.49% after 1 ()0() cycles at 5 A/g current density. This is mainly attributed to the Sn nanoparticles (〜1() nm) uniformly distributed on the SNS surface can provide additional lithium storage sites, and the effective support of SNS to the nanoparticles can alleviate the volume expansion during the charging and discharging process, thus Sn/SNS composites exhibits high lithium storage capacity and good cyclic stability. [ABSTRACT FROM AUTHOR]

Silicon has been widely concerned for its low delithium potential (about 0,4 V), high theoretical specific capacity (4200 mAh/g), abundant resources and environmental friendly. However, silicon materials have serious volume expansion (>3()()%) in the process of delithium, which leads to poor cyclic performance and low coulomb efficiency, and thus hinders its practical application. Tt has been reported that the electrochemical properties of silicon-based anode composites have been significantly improved by using a new strategy of composite treatment of silicon and metal oxides. Tn this paper, the research achievements in recent years are reviewed from the perspectives of coating silicon by metal oxide and introducing silicide and metal particles by in-situ solidstate reaction with silicon, and the problems to be solved and the development trend of modifying silicon anode materials by metal oxide are also described. [ABSTRACT FROM AUTHOR]

Nano-Li2FeSiO4/C composites (LFS/C-325 and LFS/C-221) and nano-Li2FeSiO4 (LFS-325 and LFS-221) with controlled porosity were prepared from the nano-fumed silicas with similar particle size and different porosity. N2 adsorption/desorption analysis reveals that the porosity of nano-Li2FeSiO4/C composites and nano-Li2FeSiO4 can be tuned by the choosing nano -fumed silica and LFS/C-325 possess the highest specific surface area among the four samples. XRD indicates that both LFS/C-325 and LFS/C-221 are crystalline powders with monoclinic Li2FeSiO4 of P21. FTIR spectra show that Li-O and Si-O bonds are existed in the four samples. SEM images demonstrate that LFS/C-325 and LFS/C-221 have similar particle sizes in the range of 20 ~ 25 nm, which are distinctly smaller than those of LFS-325 and LFS-221. LFS/C-325 features the smallest particle size and largest specific area, which enables LFS/C-325 to exhibit the best electrochemical performance. The initial discharge capacity of LFS/C-325 is as high as 185.2 mAh g−1 at 0.1 C. [ABSTRACT FROM AUTHOR]

As a new two-dimensional carbon material, grapheyne has π conjugated units, SP² and SP hybrid carbon atoms and adjustable pore structure. It has stable structure, good conductivity and strong plasticity. Its structure can be adjusted by hybridization or modification. It has a good application prospect in the field of electrochemistry. This paper briefly introduced different types of graphyne and their structures, such as α-graphyne, β-graphyne, γ-graphyne and 6,6,12-graphyne, as well as graphdiyne. The synthesis strategies of graphyne and its derivatives are described, including wet and dry methods. There are in-situ synthesis methods of different types of graphyne and graphdiyne, and different structures are obtained through different synthesis or growth methods, such as nano films, nano sheets and nano chains. It also includes the preparation strategy of graphyne derivatives, which adjusts the structure by heteroatom doping or metal atom modification, such as nitrogen atom doping, platinum atom modification and so on. The advanced research results of graphyne and its derivatives in the field of energy are reviewed, including the research results of graphyne and its derivatives in lithium-ion batteries, hydrogen oxygen fuel cells, sodium ion batteries, supercapacitor and other electrochemical energy storage devices and materials. As the anode of lithium-ion battery, the coulomb efficiency and cycle performance of the battery are improved, and the stability of the battery is enhanced. It has good catalytic performance for oxygen reduction reaction and has the prospect of being used as a catalyst for hydrogen oxygen fuel cell. It also has good storage performance for sodium, calcium and magnesium, and has good potential in application with sodium ion batteries and multivalent ion batteries. It shows good cycle performance and specific capacity in supercapacitor. In addition, it also has good theoretical capacity in hydrogen storage. It has a good application prospect in a variety of electrochemical energy storage devices. Comprehensive analysis shows that graphyne, as a new allotrope of carbon, has good performance and optimization potential in structure and electrochemical properties. It has a good development prospect in electrochemical energy storage devices in the future. [ABSTRACT FROM AUTHOR]

Carbothermic reduction-roasting tests of NCM (nickel, cobalt, and manganese) cathode active materials with carbon sources such as activated carbon and graphite followed by sulfuric acid leaching were performed to investigate the effects of roasting temperature, molar mixing ratio of cathode active materials and carbon sources, and type of cathode active materials. When the virgin NCM622 materials were roasted with activated carbon, the peaks of Ni and Co metals were observed in the XRD data. The leaching efficiencies of Li, Ni, Co, and Mn increased to over 99.9% within 120 min in all samples roasted at 600 °C–900 °C, but, at the beginning of leaching, the leaching efficiencies increased more slowly with increasing roasting temperature. The leaching efficiencies of Ni and Co decreased with decreasing the molar mixing ratio of active cathode materials and carbon sources, but the leaching efficiencies were more than 99.9% in all ratios. These results indicate that roasting can enhance the leaching of cathode active materials and improve the conventional leaching process using hydrogen peroxide. [ABSTRACT FROM AUTHOR]

Traditional polyolefin separator has the defects of non-degradation and poor wettability with the electrolyte. In this paper, we have designed the porous membrane based on the lignin-containing cellulose nanofibers (LCNFs) from the unbleached pulp by a facile method. In the designed membrane, the amorphous lignin can effectively adjust the dispersion of the cellulose to form a uniform mesoporous structure. And the abundant oxygen-containing functional groups both in cellulose and lignin can promote the affinity of the membrane with the electrolyte. Finally, the prepared the LCNF porous membrane shows a high electrolyte uptake of 276 % and high ionic conductivity of 1.86 mS cm−1. As the separator for LIBs, the batteries with high-voltage Li 3 V 2 (PO 4) 3 as cathode (up to 4.8 V), the batteries displayed 183 mAh g−1 with the energy density of 669 Wh kg−1, indicating the good application potential in high-energy LIBs. More importantly, the LCNF membrane made from the unbleached pulp has low cost and it can degraded in soil only after 16 days, which can largely reduce environment pollution of the LIBs. This research provided an efficient and low-cost method to fabricate a membrane with good biodegradability and high electrochemical performance for LIBs. A degradable membrane with good affinity to electrolyte and fast Li+ transfer was designed from the low-cost lignin-containing cellulose. [Display omitted] [ABSTRACT FROM AUTHOR]