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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]

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]

Fast charging of Lithium ion batteries (LIBs) is expected to boost the extensive electrification of transportation sector. However, fast charging a LIB comes at the cost of increased internal heat generation that results in higher reaction rates of both the necessary as well as unwanted reactions at the electrode–electrolyte interface. This can trigger a chain of events that can possibly lead to thermal runaway. Electrolyte has a critical effect on the internal heating of a LIB and thus plays an inherent role in its safety. We elucidate the role of electrolyte salt in reducing internal heating by evaluating two different salts—Lithium bis(fluorosulfonyl)imide (LiFSI) and Lithium hexafluorophosphate ( LiPF 6 ). Using a physics-based electrochemical–thermal model, we study these electrolyte salts individually in LiCoO 2 (Cathode)/Graphite (Anode) LIB system. Under fast charging conditions, internal heating and polarization were studied in each of the LIB system. The temperature rise seen in the two systems shows that LiFSI is a better electrolyte salt for fast charging application as compared to LiPF 6 . This is primarily due to better transport properties of LiFSI compared to LiPF 6 , as elaborated using polarization studies. This study can aid in choosing the appropriate electrolyte salt for mitigating the internal heating and thermal issues during fast charging. [ABSTRACT FROM AUTHOR]

• Strength–ductility synergy is achieved by lithiation in sulfur cathodes. • Brittle-to-ductile transition in amorphous lithiated sulfur is governed by cavitation nucleation mechanism. • Atomic chain bridging behind the crack tip enhances crack resistance at lower lithium concentrations. As an eminent candidate for next-generation cathode materials, sulfur undergoes severe volume changes during electrochemical cycling, resulting in material fractures and performance degradation. Although the electrochemical characteristics of lithiated sulfur have been rigorously studied, their mechanical properties, particularly fracture mechanisms, remain insufficiently understood. To address this gap, we conducted comprehensive atomistic simulations to investigate the fracture behavior of amorphous lithiated sulfur (a-Li x S). Our findings reveal that as lithium concentration increases, the fracture mechanism transits from brittle governed by nanoscale cavitation instability to ductile dominated by plastic shear bands launched at the crack tip. This transition is contingent upon local hydrostatic stress exceeding the cavitation strength, elucidated through atomic-level bonding dynamics including rupture, reformation and rotation. At low lithium concentrations, atomic chain bridging posterior to the crack tip is simultaneously identified to enhance crack resistance. The lithiation-induced fracture toughness enhancement is further quantified via domain J -integral analysis. Notably, a unique strength–ductility synergy is identified for a-Li x S, attributed to cooperation between lithiation induced heterogeneous bonding environments and atomic chain bridging. This study provides valuable atomic-scale insights into the fracture mechanisms of sulfur cathodes, thereby informing the design of high-energy and durable electrode materials for future applications. [Display omitted] [ABSTRACT FROM AUTHOR]

A simple and facile approach to synthesis Co 3 O 4 nanocrystals by a two–step pyrolysis process of bis (8–hydroxyquinoline) cobalt complex under Ar and air atmospheres successively. The structures and physical properties of the complex, Co@C intermediate and the Co 3 O 4 nanocrystals are characterized by the following techniques: FTIR, XRD, TGA–DTG, Raman, FESEM, HRTEM, N 2 adsorption/desorption measurement and XPS. As anode materials in lithium ion batteries, the Co 3 O 4 nanocrystals exhibit high charge/discharge specific capacity, excellent rate performance and remarkable cycle stability. The superior electrochemical properties of the Co 3 O 4 nanocrystals could be attributed to the nanoscaled particle size, high crystallinity and high specific surface area, which is helpful to increase the number of active sites, shorten the diffusion path of lithium ions and electrons, alleviate the volume expansion effect as well as improve the dynamic characteristics during cycling. Co 3 O 4 nanocrystals are synthesized by a two–step pyrolysis process of bis (8–hydroxyquinoline) cobalt complex. As the anode materials of lithium ion batteries, the as–obtained Co 3 O 4 active material shows high discharge specific capacities, outstanding cyclic stability and excellent rate capability. The excellent lithium storage performance could be attributed to the nanoscaled particle size, high crystallinity, high specific surface area as well as excellent dynamic characteristics of the Co 3 O 4 nanocrystals during charge/discharge cycle. [Display omitted] [ABSTRACT FROM AUTHOR]

Oxides based on vanadium redox couple, such as orthorhombic Li 3 VO 4 , has drawn great attentions due to its high theoretical capacity and moderate operating voltage. However, the rate property is largely hindered by the slow interfacial dynamics of Li 3 VO 4. Here we synthesized the lotus stem-like Li 3 VO 4 wrapped in N-doped carbon fibers (Li 3 VO 4 /C NF) stemmed from the chemical lithiation of V 2 O 3 /C NF. The knobbly Li 3 VO 4 rooted in the interconnected carbon fibers provides abundant active sites and well-developed conductive networks. Thus, this anode delivers high specific capacity of 558.9 mAh g−1 at 0.2 A g−1 and excellent rate capacity of 419 mAh g−1 at 2 A g−1 sustaining 900 cycles with an average potential of 0.7 V vs. Li+/Li. Furthermore, the kinetic analysis reveals that the pseudocapacitance dominants the lithium storage process and the favorable interfacial ion and electronic transport is responsible for the enhanced rate performance. The full cell (Li 3 VO 4 /C NF||LiFePO 4) also shows a competitive performance for commercialization. This work boosts the development of vanadium-based anode materials with desired electrochemical properties meeting devices requirements. [Display omitted] • Lotus stem-like structure enhances the interfacial dynamics. • Pseudocapacitance dominants the lithium storage of this anode. • Li 3 VO 4 /C NF delivers excellent rate capacity of 419 mAh g−1 at 2 A g−1. [ABSTRACT FROM AUTHOR]

State-of-health (SOH) estimation is necessary for lithium ion batteries due to ineluctable battery ageing. Existing SOH estimation methods mainly focus on voltage characteristics without considering temperature variation in the process of health degradation. In this article, we propose a novel SOH estimation method based on battery surface temperature. The differential temperature curves during constant charging are analyzed and found to be strongly related to SOH. Part of the differential temperature curves in a voltage range is adopted to establish a relationship with SOH using support vector regression. The influence of battery discrepancy, voltage range, and sampling step are systematically discussed and the best combination of voltage range and sampling step is determined using leave-one-out validation. The proposed method is then validated and compared with an incremental capacity analysis (ICA)-based SOH estimation method using the Oxford and NASA datasets, which were collected from different cells under different conditions, respectively. The results show that the proposed method is capable of estimating SOH with the root-mean-square error less than 3.62% and 2.49%, respectively. In addition, the proposed method can improve the overall SOH estimation accuracy and robustness by combining with the ICA-based method with little computational burden. [ABSTRACT FROM AUTHOR]

In this study, lithium terephthalate by solvothermal method with low energy consumption and simple preparation process were synthesized. To obtain the lithium terephthalate with best electrochemical properties, the effects of different organic solvents, reaction temperature and lithium source were investigated and compared. The electrochemical performance of lithium terephthalate prepared from various processing methods as lithium ion battery was furtherly analyzed and discussed. The compositions lithium terephthalate of were confirmed by XRD and FTIR, the morphologies were observed by SEM, and the electrochemical properties were analyzed by cycle charge-discharge tests. The results show that the first discharge capacity of the battery prepared by lithium hydroxide in DMF at a reaction temperature of 175 °C presented the best performance, reaching a maximum capacity of 235/74 mA⋅h/g. [ABSTRACT FROM AUTHOR]

Herein, we report a direct recycling process of the spent LiFePO 4 by direct room temperature chemical lithiation. A fine characterization of a recovered LFP cathode from a spent commercial battery demonstrates that the end of life of the battery is mainly due to the lithium loss, while the structure of the LFP cathode material is globally preserved. It is shown here that such a cathode can be efficiently recovered by direct lithiation in solution using LiI in different solvents (acetonitrile, ethanol, cyclohexane, methanol, DMSO and propan-1,2-ol) with optimized experimental parameters. The best electrochemical performance is obtained with ethanol, one of the greenest and cheapest solvents, without any additional heat treatment. More interestingly, the regeneration of LFP can be achieved directly with the material cast onto its aluminum collector, which paves the way to more efficient recycling preserving the whole electrode formulation and avoiding a new electrode casting. The chemically lithiated LFP cathode in ethanol exhibits a full reversible capacity of ∼168 mAh/g vs. Li metal with a stable coulombic efficiency exceeding 98% for 25 cycles. In addition, this recovery process produces regenerated electrodes showing good electrochemical performance also at high current density. [Display omitted] • Spent LiFePO4 is regenerated at room temperature via DCL. • No heat treatment is required. • Regenerated electrodes show excellent performance, even at high current density. • Optimal performance is achieved using cost-effective, eco-friendly ethanol solvent. • With DCL, LFP cathode is regenerated without removing aluminum collector. [ABSTRACT FROM AUTHOR]

Polypyrrole (PPy) used as popular coatings can improve the electrochemical performance of electrodes greatly; however, uniform coatings of PPy on nanostructures is a challenging task in a solution system. Substitution for liquid phase polymerization reaction, herein a developed evaporation method is reported to make pyrrole vapor in situ polymerization on CuO arrays for the uniform PPy coatings. With the help of this uniform PPy coatings, the unique structure of arrayed CuO film can well maintain the stability of mechanical structures and has rapid transmission of lithium ions and electrons during charge/discharge processes, hence harvesting a high lithium storage. Electrochemical tests indicate that PPy can not only enhance the specific capacities of CuO anodes greatly but also improve the cyclic stability at a high-current density. The specific capacity of the CuO@PPy integrated anode can be up to 561 mAh g−1 at 1 C after 100 cycles, which is increased by almost 33% than that of the pure CuO anode. [ABSTRACT FROM AUTHOR]

Abstract Four LiNi 0.8 Co 0.15 Al 0.05 -based Li-ion-battery cathode materials, i.e., the pristine LiNi 0.8 Co 0.15 Al 0.05 , Li-excess Li 1+ x Ni 0.8 Co 0.15 Al 0.05 , SnO 2 -coated LiNi 0.8 Co 0.15 Al 0.05 and SnO 2 -coated Li-excess Li 1+ x Ni 0.8 Co 0.15 Al 0.05 are prepared via a facile oxalate coprecipitation route, and are studied with respect to the effects of Li excess and SnO 2 coating on the structure and electrochemical properties. X-ray diffraction and X-ray photoelectric spectroscopy demonstrate that a small amount of Li+ and/or Sn2+ ions are incorporated into the transition-metal slabs of the modified materials, and hence reduce the cationic disorder of Li+/Ni2+. High-resolution transmission electron microscopy and scanning electron microscopy confirm the formation of a SnO 2 surface layer that prevents the growth and aggregation of the primary particles during high-temperature solid reaction, and therefore results in formation of the SnO 2 -coated materials with nano/submicron sphere-like morphology. Lithium excess and SnO 2 coating enhance the electrochemical performance. The SnO 2 -coated Li-excess Li 1+ x Ni 0.8 Co 0.15 Al 0.05 exhibits not only higher specific capacity and better rate capability but also excellent cycling stability. After 400 cycles at 1C rate, the capacity is decreased from 123.7 to 86.7 mAh g−1, giving capacity retention of 70.1%. Li excess is believed to decrease the cationic mixing and SnO 2 modification is deemed to restrict the undesirable side reaction between the active material and electrolyte. Graphical abstract Image 1 Highlights • A Ni-rich NCA material with Li excess and SnO 2 coating was synthesized. • The material has the morphology of nano/submicron sphere-like particles. • The material exhibits improved performance over the pristine NCA material. • Li excess can significantly reduce the cationic mixing. • Surface SnO 2 coating can remarkably improve the cycling stability. [ABSTRACT FROM AUTHOR]

Abstract The binding configurations of the nitrogen have a great influence on the performance of the doped graphene-based lithium ion batteries anode, while the mechanism of lithium storage is still unclear. In this paper, the binding configuration of the nitrogen is controlled in doped graphene by introducing little sulfur atoms to produce more proportion of graphite nitrogen, which have an excellent cyclic performance with delivering 589 mAh g−1 at 5 A g−1 after 1000 cycles in the lithium ion batteries anode. What's more, the kinetics is improving with higher lithium ion diffusion coefficient and a smaller impedance of charge-transfer compared to the samples which do not regulated the binding configurations of the nitrogen. The characteristic electronic structure of graphite nitrogen is considered to reveal the lithium storage mechanism. Consequently, this work can provide a new insight for regulating binding configurations of nitrogen to improving lithium storage kinetics of the doping graphene electrodes. Graphical abstract Image 1 Highlights • The binding configurations of nitrogen are controlled by a facile method. • The kinetics mechanism of lithium storage for graphite nitrogen is revealed. • The material affords a high capacity of 589 mAh g−1 after 1000 cycles at 5 A g−1. [ABSTRACT FROM AUTHOR]

Abstract High performance lithium iron phosphate (LFP) cathode materials were synthesized using amorphous carbon, carbon nanotubes (CNTs), and graphene (G) as conductive materials via sand milling and spray drying processes and followed by calcination. The structural characterizations indicated that CNTs and G can well connected with LFP nanoparticles (NPs), which was coated with a thin layer of amorphous carbon, benefiting the construction of three-dimensional efficient conductive network. The electrochemical measurements confirmed that the introduction of CNTs and G can obviously decrease the charge transfer impedance of lithium ion battery and increase the discharge special capacity. The initial discharge special capacity increases in the order of LFP/C (150.3 mAh/g) < LFP/C/CNTs (155.7 mAh/g) < LFP/C/G (159.7 mAh/g) < LFP/C/G/CNTs (164.5 mAh/g) at 0.1 C. LFP/C/G/CNTs also exhibited considerable discharge special capacity (99.5 mAh/g) at high current of 5 C. Compared with LFP/C (248 Ω), LFP/C/G/CNTs (50 Ω) showed obviously decreased charge transfer impedance. Cycle performance test indicated that the specific capacity retention for LFP/C/G/CNTs was 99% after 200 cycles, displaying good cycle stability. The superior electrochemical performance of LFP/C/G/CNTs is attributed to the significantly synergistic effect of CNTs and G on decreasing charge transfer impedance by constructing highly three-dimensional conductive network. Besides, the effect of G to CNTs mass ratio and the calcination temperature on the electrochemical performance of LIBs were also discussed. [ABSTRACT FROM AUTHOR]

Abstract The three-dimensional conductive skeleton plays an important role for silicon-based anode materials to achieve good electrochemical performance in lithium ion batteries with high energy density. Here, we prepared a three-dimensional silicon/N-doped graphitized carbon composite (3D Si/NGC) from ZIF-67 precursor by magnesiothermic reduction reaction. The N-doped and graphitized conductive carbon acts as a robust three-dimensional configuration for the silicon nanoparticles, not only improving the conductivity of electrode, but also buffering the volume expansion of silicon nanoparticles. The 3D Si/NGC electrode exhibits good long-term cycle stability and impressive rate performance, delivering reversible capacity of 900 mA h g−1 at 0.2 A g−1 after 300 cycles with a capacity retention of 85.5% and a high discharge capacity of 880 mA h g−1 at 1 A g−1. The 3D Si/NGC with good electrochemical performance shows great potential as the next generation anode material for lithium ion batteries. Graphical abstract Image 1 Highlights • 3D Si/NGC composite derived from ZIF-67 is prepared by the magnesiothermic reduction. • Si/NGC composite displays a robust porous three-dimensional structure. • The N-doping and the graphitization enhance the electronic conductivity of composite. [ABSTRACT FROM AUTHOR]

Abstract The electrochemical property of a silicon electrode in a half-cell was investigated using the mixture of monoglyme-based solvents and lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) with 2:1 stoichiometry. The solvents used in this study are monoglyme (G1), 1,2-diethoxyethane (DEE), 1,2-dibutoxyethane (DBE), and 1,2-dimethoxypropane (P-G1). When Li (DEE) 2 or Li(P-G1) 2 was used, the cell retained ca. 20% capacity at a rate of 3 C, while the other samples showed almost no capacity under the same conditions. Raman spectroscopy measurement revealed that Li+ exists as two forms in the mixture, that is, a solvent shared ion pair (SSIP) [ Li+ ··· solvent ··· TFSA– ] and a contact ion pair (CIP) [ Li+ ··· TFSA– ]. According to the spectroscopic analysis, SSIP is the dominant species for Li (DEE) 2 and Li(P-G1) 2 , and CIP for Li (G1) 2 and Li (DBE) 2. The order of the rate property was Li(P-G1) 2 ∼ Li (DEE) 2 > Li (DBE) 2 ∼ Li (G1) 2 , which is almost consistent with the stability of free energy levels of Li+ in the respective monoglymes against CIP Li+ ··· TFSA– evaluated from the Raman spectra. Graphical abstract Image 1 Highlights • Monoglyme-based solvent can be a good electrolyte for Li-ion batteries. • Raman spectroscopy measurement revealed the form of Li+ in the electrolyte. • The rate property depends on the stability of Li+–solvent–anion in the electrolyte. [ABSTRACT FROM AUTHOR]

Abstract VO 2 as one of the most prospective cathode materials applied for lithium-ion batteries, has appealed increasing attentions owing to its high theoretical specific capacity, unique tunnel structure, as well as low cost. Among multiple methods to optimize the electrochemical performances of VO 2 (B), heteroatom-doping has attracted increasing interests owing to its efficiently adjusting the microstructure and interplanar distances of VO 2 (B). Here, W-doped VO 2 (B) nanosheets-built 3D networks are obtained readily via a hydrothermal route by oxalic acid reduction of vanadium pentoxide. The resultant 3D networks possess ultrathin nanowalls, interconnected structure and enlarged tunnels, which are advantageous for the easy access of electrolyte and fast diffusion of lithium ions. As a consequence, high reversible specific capacity of 304 mAh g−1, ultrahigh rate capability (200 mAh g−1 at 2 A g−1), and high-temperature electrochemical performances are achieved as the 3D networks are applied for lithium storage. [ABSTRACT FROM AUTHOR]

A fully coupling model for the diffusion induced finite elastoplastic bending of bilayer electrodes in lithium-ion batteries is proposed. The effect of the mechanical stress on the lithium diffusion is accounted for by the mechanical part of the chemical potential derived from the Gibbs free energy along with the logarithmic stress and strain. Eight dimensionless parameters, governing the stress-assisted diffusion and the diffusion induced elastoplastic bending, are identified. It is found that the finite plasticity starting from the interface of the bilayer increases the chemical potential gradient and thereby facilitates the lithium diffusion. The full plastic flow makes the abnormal lithium concentration distribution possible, i.e., the concentration at the lithium inlet can be lower than the concentration at the interface (downstream). The increase in the thickness of the active layer during charging is much larger than the eigen-stretch due to lithiation, and this excess thickening is found to be caused by the lithiation induced plastic yield. [ABSTRACT FROM AUTHOR]

Layered Ni-rich Li[Ni 0.6 Mn 0.2 Co 0.2- x Sn x ]O 2 cathode active materials with x  = 0–0.05 are synthesized via a co-precipitation synthesis route and the effect of doping content on the structural behavior and electrochemical performance are investigated. All synthesized materials show a well-defined layered structure of the hexagonal α -NaFeO 2 phase (space group R 3 ¯ m ) analyzed by X-ray diffraction (XRD). Electrochemical Li-metal/cathode cell studies exhibit that a Sn-content of 1%–2% is beneficial regarding specific discharge capacity and cycle life (≥20%). Detailed electrochemical investigations of Li-metal and lithium ion cells with cathodes consisting of LiNi 0.6 Mn 0.2 Co 0.2 O 2 and LiNi 0.6 Mn 0.2 Co 0.18 Sn 0.02 O 2 are conducted. Post mortem analyses by means of ICP-OES and TXRF show beneficial effects of the Sn-doping with regard to a lower transition metal dissolution and a higher available Li content in the cathode active material. The thermal analyses (TGA, DSC, ARC) show a stabilizing effect of Sn-doping, which results from a lower mass loss and less heat evolution of the charged cathode active materials at elevated temperatures. [ABSTRACT FROM AUTHOR]

Li[Ni 1/3 Co 1/3 Mn 1/3 ]O 2 cathode active materials are synthesized from co-precipitated hydroxide precursors Li x [Ni 1/3 Co 1/3 Mn 1/3 ] 1-x (OH) 2 , and the effect of residual Li in the precursors on the lithium-ion battery (LIB) performance of their corresponding cathode active materials is investigated. Three kinds of precursors that contain different amounts of Li are selected depending on different conditions of the solution composition for the co-precipitation and washing process. It is confirmed that the introduction of Li to the precursors reduces the degree of structural perfection by X-ray diffraction analysis. Undesirable cation mixing occurs with the increasing Li content of the precursors, which is inferred from a decline in lattice parameters and the calculated intensity ratio of (003) and (104) peaks. In the voltage range of 3.0–4.3 V, the initial charge/discharge capacities and the rate capability of the cathode active materials are aggravated when Li exists in the precursors. Therefore, it could be concluded that the strict control of Li in a solution for co-precipitation of precursors is necessary in the resynthesis of cathode active materials from spent LIBs. [ABSTRACT FROM AUTHOR]

Silicon monoxide (SiO x , 0 < x < 2) has been one of the new directions of scientific researchers because of some characteristics, such as higher theoretical specific capacity and lower volume expansion efficiency. However, its disadvantages such as the volume expansion effect and poor conductivity still exist in the process of charge and discharge, which limit its commercialization process. In this paper, cuprous oxide and carbon coated silicon monoxide (SiO x /C/Cu 2 O) composites were obtained by high temperature heat treatment. In the SiO x /C/Cu 2 O anodes, carbon can buffer the volume expansion of the lithium intercalation, enhance the conductivity of the material, reduce the contact between the electrolyte and the active substance, Cu 2 O can further reduce the contact between the electrolyte and the active substance, greatly buffer the change of electrode structure and improve the overall cycling performance. After the rate of 0.5C (1C = 2100 mA g−1) for 500 cycles, the discharge specific capacity is 704.0 mAh g−1, about 350 mAh g−1 higher than SiO x , which shows excellent long-cycle ultra-high stability. • Hard carbon coating and cuprous oxide coating technology are novelly superimposed. • The wettability of electrolyte to SiO x anode is improved. • SiO x /C/Cu 2 O shows better electrochemical performance, especially cycle performance. [ABSTRACT FROM AUTHOR]

• TiO 2 nanoflowers percolated with carbon nanotubes (CNTs) are designed by solution method. • CNTs improve the electronic conductivity of TiO 2 nanoflowers. • The optimized TiO 2 @CNTs hybrids exhibit excellent cycle performance for lithium storage. Titanium dioxide (TiO 2) is a promising anode materials for lithium-ion batteries due to its advantages such as good safety, reliability, reversible capacity, high content and environmental friendliness. However, its inherent defects such as low ion diffusion coefficient and poor electrical conductivity seriously limit its practical application. In this study, we designed a unique hybrid structure of TiO 2 nanoflowers percolated with carbon nanotubes (CNTs) by a low cost solution method. The hierarchical structure of TiO 2 increases the specific surface area and shortens the ion/electron transport distance. CNTs are uniformly embedded in the interior of TiO 2 nanoflowers to improve the overall conductivity and flexibility. As a result, the optimized TiO 2 @CNTs as lithium ion battery (LIBs) anode, showed excellent long-term cycle performance (177.5 mA h g−1, at 1.0 A g−1 after 600 cycles). The excellent reversibility and electrochemical kinetic performance are also studied by CV and EIS measurements. This work provides a new perspective for exploring efficient lithium storage for high performance anode materials. [ABSTRACT FROM AUTHOR]

A new bimetal coordination polymer composed of Li + , Zn 2+ and 4,5‑imidazole dicarboxylic acid (idca) with a molecular formula of Li 5 Zn 6 C 25 H 11 N 10 O 24 (LiZn1) was prepared via a simple hydrothermal method. The single crystal structure shows that LiZn1 has a 3-D framework consisting of three independent four coordinated Li + and three independent five coordinated Zn 2+ cations, respectively. Topological study indicates the network of LiZn1 is 9-nodal, 3,3,3,3,3,4,5,5,6-connected net, with a point symbol of {4.6.7} 2 {4.6 2 } 4 {4 2 .6 2 .7 2 .9 3 .11}{4 2 .6} 2 {4 3 .6 3 .7 2 .8 5 .9 2 } 2 {4 3 .6 3 } 2 {6 2 .8}{6 5 .7 2 .8.9 2 } 2 . The graphene composite (LiZn1/gr, gr stands for graphene.) was prepared via a sonication treatment of the mixture of LiZn1 and graphene. LiZn1 was employed as the anode of a lithium ion battery, the initial discharge capacity was obtained for 558 mAh/g, after 100 cycles the discharge capacity was decreased to around 75 mAh/g. However, the graphene composite (LiZn1/gr) has improved very much the performance with the initial discharge capacity of 1090 mAh/g and after 100 cycles the discharge capacity could remain about 133 mAh/g. [ABSTRACT FROM AUTHOR]

This paper aims to computationally investigate the thermal effect, combining the internal heat and the ambient temperature, on the lithium (Li) dendrite growth process. To achieve this, the recently developed phase-field Li-dendrite model is further extended by coupling with a heat transfer model. The two models are linked via a temperature-dependent ion diffusion coefficient to investigate the evolution of the morphology and size of dendrites. Three levels of cases are used to progressively investigate the thermal effect on Li dendrites: (1) uniform ambient temperature, (2) temperature gradient along the charging direction, and (3) internal heat-induced spatially distributed temperature. The results show that the normalized dendrite length decreases as the ambient temperature increases, which agrees well with the published experimental measurements. The temperature gradient is applied in the 2-D system showing that the formation of lateral branches can be prevented with the presence of the temperature gradient. The third case shows that the temperature significantly increases at the dendrite-electrolyte interface, and the dendrite deviates from the tree-type shape to a nearly rhombic shape. The simulation results provide valuable bases for the future comprehensive studies of the temperature-dependent Li dendrite growth process. [ABSTRACT FROM AUTHOR]

Iron fluorides based on conversion chemistry are developed as alternative cathode materials for Li-ion batteries due to their high capacity, also suffering from some drawbacks, such as poor electrical conductivity and structural instability. In order to improve the electrochemical performance of iron fluoride, in this work, we focus on the enhancement of the lithium extraction capability of FeF 3 by introducing extra C@LiF additive. FeF 3 /C@LiF composites are fabricated by high energy ball milling. Due to the compact connection between LiF and conductive carbon in FeF 3 /C@LiF composites, LiF can not only act as high-active reactant for lithium extraction process, but also provide active sites for subsequent charge/discharge reaction. Electrochemical study results suggest that a suitable content of LiF enables FeF 3 /C@LiF composite to deliver a satisfactory electrochemical performance, which retain a capacity of 229 mAh g − 1 at a current rate of 40 mA g − 1 after 50 cycles (10% higher than that of FeF 3 /C composite). [ABSTRACT FROM AUTHOR]

In this work we present a simple and scalable approach to fabricate highly-active, self-supported molybdenum dioxide (MoO 2 ) film for lithium storage. The fabrication is based on a thermal oxidation of Mo foil under air atmosphere and a subsequent sulfurization treatment. A hybrid film composed of partially sulfurized MoO 2 can be produced by controlling the sulfurization conditions. This hybrid film can be directly adapted as binder-free electrode for lithium storage, displaying a reversible capacity of 899 mAh g −1 and a high initial Coulombic efficiency (CE) of 75%. More importantly, the hybrid film sustains 250 successive cycles at a high rate of 10C without evident capacity decay, thereby suggesting its potential for durable battery application. [ABSTRACT FROM AUTHOR]

Germanium dioxide/reduced graphene oxide (GeO 2 /RGO) nanocomposites are promising anode materials for applications in lithium ion batteries because they have ultrahigh lithium ion storage capacity and high structural stability. However, the design of GeO 2 based anodes with satisfactory cycling ability and high capacity still presents a big challenge because of strict requirements in the need for a special type of solvent, a complicated preparation process, high energy and material costs, and/or difficulty in process upscaling. In the present work, GeO 2 /RGO nanocomposite is successfully synthesized as an anode material by a simple and green method, which stacked the GeO 2 nanoparticles directly on the reduced graphene oxide sheets in an in situ process. The sample exhibits high specific capacity and enhanced rate capacity as an electrode material for lithium ion batteries. GeO 2 /RGO nanocomposite shows a higher storage capacity of 1020.4 mA h g −1 (theoretical capacity 1125 mA h g −1 ) after 30 cycles with a current density of 0.1 A g −1 , and a long-term cycle capacity of 464 mA h g −1 even after 100 cycles at 1 A g −1 . This good electrochemical performance is due to the superior properties of non-aggregated graphene sheets and homogeneously dispersed GeO 2 nanoparticles in GeO 2 /RGO nanocomposite. [ABSTRACT FROM AUTHOR]

Chromium nitride (CrN) synthesized by heating at 550 °C under a continuous stream of ammonia has been investigated as anode material for lithium electrochemistry. Due to its low lithium insertion potential, Cr is an attractive material for lithium–ion battery application, but the usual volume variation effect obstructs its practical use. In this study, different concentrations of carbon nanotubes doped with nitrogen (NCNTs) are combined with CrN to attain high electrochemical performance. The synthesized CrN/0.08%–NCNTs nanocomposite demonstrates network structure with 30–40 nm CrN nanoparticles anchored to specific sites on 40–60 nm diameter NCNTs. Upon electrochemical testing, CrN/0.08%–NCNTs nanocomposite displays a discharge capacity of 1172 mAh g −1 after 200 cycles with high coulombic efficiency (∼100%) and rate capability. The electrode can deliver a reversible capacity of 1042.9 mAh g −1 at 20 C. The n-type concentration, along with the conductive CNTs framework, mesoporous channels, appropriate surface area and buffering capability of CNTs, are together responsible for the excellent electrochemical performance. The electrochemical reaction mechanism of CrN with lithium is explored by investigating the structural changes using ex situ X-ray photoelectron spectroscopy, X-ray diffraction, selected area electron diffraction, and high-resolution transmission electron microscopy. The reversible conversion reaction of CrN into Cr metal and Li 3 N is revealed. [ABSTRACT FROM AUTHOR]

Two-dimensional V 2 C (MXene) derived from layered V 2 AlC phase attracts increasing interest due to its various promising applications such as lithium-ion batteries. Yet it is a great challenge to obtain completely exfoliated V 2 C MXene by etching Al from V 2 AlC. Here, in this work, we highlight that alloying Ti can significantly enhance the exfoliation of (V 1- x Ti x ) 2 C MXene from (V 1- x Ti x ) 2 AlC based on our systematic studies of experiments and first-principles calculations. Furthermore, the exfoliated (V 1- x Ti x ) 2 C MXene shows better multilayered morphology characterized by X-ray diffraction and scanning electron microscopy. Meanwhile, by analyzing the exfoliation process and electron localization functions, we have demonstrated that the micro-origin of Ti enhancement effect on the exfoliation of (V 1- x Ti x ) 2 AlC is due to the significantly weakened interlayer bonding between the VC and Al layers in (V 1- x Ti x ) 2 AlC induced by alloying Ti. Finally, we have shown that the performance of (V 1- x Ti x ) 2 C as anode materials for Li-ion batteries is improved with the increase of Ti content. Our results provide a useful way to improve the synthesis of V-based MXenes and are beneficial to the applications as well. [ABSTRACT FROM AUTHOR]

The structural optimization of TiO2 materials has a significance for improving the electrochemical performance since TiO2 suffers from poor electronic conductivity. For this purpose, ultrathin N-doped carbon-coated TiO2 coaxial nanofibers have been designed and synthesized by a facile electrospinning approach. Microstructure analysis indicates that the TiO2 nanofibers can be coated by the ultrathin carbon layers. Electrochemical tests reveal that the rate performance and cycling ability of TiO2@C nanofibers have been enhanced obviously. The TiO2@C6 nanofibers carbonized at 600°C exhibit superior features with a specific discharge capacity of 284 mAh g−1 at a current density of 100 mA g−1 after 100 cycles. Besides improved rate performance of 117 mAh g−1 at a high current density of 2000 mA g−1 and excellent cycling stability with only about 0.008% capacity loss per cycle were also obtained in the sample TiO2@C6 after 500 cycles at the current density of 1000 mA g−1. Such remarkable performance may be ascribed to the unique one-dimensional nanofibers as flexible carbon matrix. [ABSTRACT FROM AUTHOR]

Lithium-rich layered compound cathode materials recently attract ever-growing attention in lithium ion batteries for electric vehicles and energy storage devices due to their high discharge capacities of over 250 mAh g −1 and low cost. However, they still suffer from capacity fade, voltage decay and poor rate capability and thermal stability. In this paper, the Al&F co-doped Li 1.2 Ni 0.13 Co 0.13- x Mn 0.54 Al x O 2(1- y ) F 2 y cathode material has been successfully prepared via a co-precipitation reaction and a subsequent solid phase calcination. The resulting material combines the advantages of both Al-doping and F-doping, which can effectively mitigate the intrinsic layered-to-spinel phase transformation, and as a consequence, inhibits the capacity fade and voltage decay: delivering a discharge capacity of 217 mAh g −1 with retention of 88.21% and an average discharge voltage decay of 0.4019 V upon 150 cycling at 0.5 C. On the other side, with an increased electronic and ionic conductivity, this co-doping practice enhances the rate capability by a considerable extent that it delivers a discharge capacity of 157 mAh g −1 at 10 C, thus facilitating its application for quick charging devices. In addition, the thermal stability related with battery safety is significantly meliorated. Specifically, the co-doped cathode material exhibits an initial exothermal peak at a higher temperature of 273 °C and a much less overall heat generation of 221 J g −1 compared to the 210 °C and 755 J g −1 for the pristine one. In conclusion, the anion/cation co-substitution strategy has been demonstrated to be of great promise for the improvement of lithium-rich layered cathode materials. [ABSTRACT FROM AUTHOR]

A series of LiV(PO)/C composites with different amounts of carbon are synthesized by a combustion method. The physical and electrochemical properties of the LiV(PO)/C composites are investigated by X-ray diffraction, element analysis, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and electrochemical measurements. The effects of carbon content of LiV(PO)/C composites on its electrochemical properties are conducted with cyclic voltammetry and electrochemical impedance. The experiment results clearly show that the optimal carbon content is 4.3 wt %, and more or less amount of carbon would be unfavorable to electrochemical properties of the LiV(PO)/C electrode materials. The results would provide some basis for further improvement on the LiV(PO) electrode materials. [ABSTRACT FROM AUTHOR]

A lithium-vanadium-molybdenum-oxide composite has been prepared by a soft chemical route with mechanical activation assistance followed by low-temperature heat treatment in argon atmosphere. The X-ray diffraction reveals that the synthesized sample is made up of Li 3 V(MoO 4 ) 3 and LiVOMoO 4 crystal phases. The SEM images show the fine particles ~300 nm in size. HRTEM image shows a clear crystal boundary between the two phases. The composite possesses good electrochemical performance as anode material. Particularly, it delivers an initial charge capacity of 927 mAh g −1 at 50 mA g −1 with a high initial coulombic efficiency of 81.2% and maintains 87.8% of its initial capacity after 50 cycles. Even if tested at 1000 mA g −1 , it can deliver a reversible capacity of 542 mA h g −1 . [ABSTRACT FROM AUTHOR]

A novel composite of layered lithium-rich oxide, Li-Rich@Li 3 PO 4 , coated with Li 3 PO 4 is synthesized through polydopamine template method. Physical characterizations reveal that Li-Rich@Li 3 PO 4 is composed of nanoparticles of 100–200 nm that are coated with a uniform Li 3 PO 4 layer of about 5 nm in thickness. Galvanostatic charge/discharge tests demonstrate enhanced cycling stability and largely increased rate capability of the material after Li 3 PO 4 coating. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of Mg-birnessite (Mg x MnO 2 ) with different crystallite sizes, prepared though low temperature precipitation and ion exchange was demonstrated. The influence of crystallite size on electrochemical performance of Mg-birnessite was studied for the first time, where material with smaller crystallite size was demonstrated to have enhanced capacity and rate capability in Li ion, Na ion, and Mg ion based electrolytes. Cation diffusion using GITT type testing demonstrated the ion diffusion coefficient of Mg 2+ was ∼10× lower compared with Li + and Na + . This work illustrates that tuning of inorganic materials properties can lead to significant enhancement of electrochemical performance in lithium, sodium as well as magnesium based batteries for materials such as Mg-birnessite and provides a deliberate approach to improve electrochemical performance. [ABSTRACT FROM AUTHOR]

To improve the stability of LiVPO 4 F electrode/electrolyte interface, Li 3 PO 4 is used to modify LiVPO 4 F composite (P-LVPF) for the first time. Morphological characterization shows that LiVPO 4 F particles are wrapped by amorphous carbon and lithium ionic conductor Li 3 PO 4 as the interlayer and outer layer, respectively. Compared to the pristine sample, the resultant P-LVPF exhibits greatly improved rate capability and elevated-temperature cycle performance when applied as the cathode material for lithium ion batteries. Specifically, the Li 3 PO 4 modified sample specific capacity maintains 77.6% at 1 C after 100 cycles under 55 °C. Such improvement is attributed to the fact that the Li 3 PO 4 coating layer not only acts as a good ionic conductor for LiVPO 4 F, but also serves as a physical barrier between electrode and electrolyte which can build a stable interface. [ABSTRACT FROM AUTHOR]

Highly porous off-stoichiometric tungsten trioxide (WO 3-σ ) with hollow and yolk-shell structures have been successfully synthesized via a selective leaching strategy, following hydrogenation using PbWO 4 spheres as the starting material. It was found that the yolk-shell WO 3-σ could be obtained from hollow WO 3-σ by dividing the continuous leaching process into two intervallic processes. The unique structural features and high conductivity facilitate both ion and electron transport, greatly enhancing reversible lithium storage capacity. In comparisons of the hollow WO 3-σ and yolk-shell WO 3-σ , the yolk-shell structure exhibited more long-term stability due to extra spatial elasticity. [ABSTRACT FROM AUTHOR]

To improve the electrochemical properties of Li(Ni 1/3 Mn 1/3 Co 1/3 )O 2 (NMC) like Lithium-diffusion rate or rate capability one way is to increase the surface between the cathode and electrolyte. By sputter etching of stainless steel substrates the surface topography is varied. Lithium-rich Li-Ni-Mn-Co-O thin film cathodes are deposited onto these modified stainless steel substrates by non-reactive r.f. magnetron sputtering from a ceramic Li 1.14 (Ni 0.37 Mn 0.18 Co 0.32 )O 1.19 target. Microstructure and electrical properties were characterized by X-ray diffraction (GIXRD), Raman spectroscopy, Atomic-force microscopy (AFM) and impedance spectroscopy (IS). The substrate roughness was increased from R a = 4 nm to R a = 63 nm after 180 min of sputter etching. The crystal orientation wasn’t influenced significant by the pre deposition surface topography modification. The results show that the activation energy E A of the conductivity mechanism is 0.23 eV, independent of the pre-deposition sputter etching treatment. Also the pre-deposition sputter etching increases the conductivity from 1.49·10 −11 Scm −1 to 1.75·10 −10 Scm −1 at 20 °C. Correlations between process parameters, microstructure and electrical behaviour are discussed in detail. [ABSTRACT FROM AUTHOR]

The LiF-Li 3 N-rich cathode/electrolyte interphase (CEI) layer is initially nucleated via competitive adsorption of the highly active lithium bisfluorosulfonylimide (LiFSI) on the electrode surface and further evolved to a dense and smooth CEI layer after several cycles. Benefiting from the accelerated Li+ diffusion and blocked shuttling effect functionalized by this CEI layer, the so-synthesized FeS 2 electrodes enables a fast-charge and long lifespan lithium storage. [Display omitted] • The construction of cathode/electrode interphase (CEI) is proposed to prevent polysulfide shuttling. • The optimizations and morphologies of CEI are performed and depicted. • The functions of CEI on metal sulfide electrode are illustrated. • The electrodes with CEI exhibit much higher rate and cycling capacity retentions than the previous reports. Robust cathode/electrolyte interphase (CEI) layer exhibits much importance in capacity retention. However, metal sulfide electrodes with unstable CEI layers suffer from fast capacity fading and poor Coulombic efficiency caused by notorious polysulfide shuttling effect. Herein, different from nanoparticle engineering, the morphology and state of CEI interface engineering are modulated via introducing highly active lithium bisfluorosulfonylimide (LiFSI) in the ether-based electrolyte. The presence and evolution of the uniform and robust LiF-Li 3 N-rich CEI layer in preventing polysulfide shuttling are fully understood by electrochemical measurements, interface-sensitive sum frequency generation spectroscopy, X-ray spectroscopies and electron microscopy. With the aid of the time-of-flight secondary-ion mass spectrometry, the three-dimensional architecture of CEI is re-depicted, showing the uniform coverage and thus inhibiting the polysulfide shuttling. As a result, the so-fabricated metal sulfide electrodes with continuous CEI layer exhibit much higher rate capacity and significantly-improved Coulombic efficiency than the controlled electrode samples. Even cycled at a high-power density of 6700 W kg−1 (5 C), the FeS 2 electrode remains a high initial capacity (512 mA h g−1) and long lifespan up to 1000 cycles, depicting a blue-script of constructing robust CEI on the electrode for achieving the fast-charge electrodes. [ABSTRACT FROM AUTHOR]

This article presents an electro-thermal model of a stack of three lithium ion batteries for automotive applications. This tool can help to predict thermal behaviour of battery cells inside a stack. The open source software OpenFOAM provides the possibility to add heat generation because of Joule losses in a CFD model. Heat sources are introduced at the connectors and are calculated as a function of battery discharge current and internal resistance. The internal resistance is described in function of temperature. Simulation results are validated against experimental results with regard to cooling air flow field characteristic and thermal behaviour of the cell surface. The validation shows that the simulation is capable to anticipate air flow field characteristics inside the battery box. It also predicts correctly the thermal behaviour of the battery cells for various discharge rates and different cooling system conditions. The simulation supports the observation that batteries have a higher temperature close to the connectors and that the temperature increase depends highly on discharge rate and cooling system conditions. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

As an anode active material, Si experiences large deformations during battery cycling, which has been cited as a primary cause for the electrode fracture and thus capacity fading. The problems caused by the electrode deformations can be remedied through electrode design, and the numerical models will greatly facilitate this design process. However, the lack of key material properties for Si/Li x Si, especially the Li diffusivity in Si, has prevented the efficient use of such numerical tools in the design of lithium-ion batteries with Si anodes. In this work, finite element (FE) analysis was used to study the Li diffusivity in amorphous Si (a-Si) anodes. To simulate the large deformation, a large strain based formulation for the concentration induced volume expansion was proposed. The Li diffusion and volume expansion were coupled and solved in COMSOL Multiphysics ® . By comparing with the lithiation experimental observations for the a-Si nanospheres, the Li diffusivity was estimated to be on the order of 2.0 × 10 − 15 m 2 /s for the Li-rich phase and 2.0 × 10 − 17 m 2 /s for the Li-poor phase. These values were further validated by comparing the thickness growth of the Li-rich phase and the lithiation time. [ABSTRACT FROM AUTHOR]

A composite of MoO 2 –Mo 2 C–C is fabricated through a facile ion-exchange route for the first time as an alternative anode material for lithium-ion batteries (LIBs). A macroporous cinnamic anion-exchange resin interacts with ammonium molybdate tetrahydrate in aqueous solution, and the product is then calcined under an inert gas atmosphere. The interaction between the resin and ammonium molybdate tetrahydrate results in an atomic level dispersion of the molybdenum over the organic carbon precursor (resin), while the calcination process allows the formation of MoO 2 and Mo 2 C as well as the pyrolysis of resin to solid carbon. According to field-emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements, ultrafine MoO 2 and Mo 2 C nanoparticles are uniformly dispersed but firmly attached within an amorphous carbon framework. When evaluated as an anode material, the as-synthesized sample exhibits superior electrochemical performance. The specific discharge capacity is as high as 1491 mA h g −1 in the first cycle and 724 mA h g −1 over 50 cycles at a current density of 0.2 A g −1 . This simple, environmentally friendly, low-cost and easily scaled up method, has significant potential for mass industrial production of MoO 2 -based material as next-generation anode material of LIBs with wide application capability. [ABSTRACT FROM AUTHOR]

Triethylborate (TEB) is used as an electrolyte additive to improve the electrochemical performances of LiNi 1/3 Co 1/3 Mn 1/3 O 2 (LNCM) upon cycling at 4.5 V vs. Li/Li + . Charge/discharge tests demonstrate that the cyclic stability of LNCM at room and elevated temperature can be improved effectively by TEB. With addition of 10 wt. % TEB into STD electrolyte (1.0 M LiPF 6 /EC:EMC:DEC), LNCM achieves a capacity retention of 99.8% after 150 cycles and 94.7% after 120 cycles at room and elevated temperature, respectively, comparing to that of 68.9% and 68.8% of STD electrolyte. In addition, 10 wt. % TEB also improves the rate capability of LNCM at room temperature. Physical and electrochemical characterizations from XRD, SEM, TEM, XPS, ICP-MS, LSV, CA, and EIS reveal that the preferential oxidative reaction of TEB generates a thin, uniform and low interfacial resistance film on the LNCM surface. This film not only suppresses the subsequent decomposition of STD electrolyte, but also prevents the dissolution of transition metal ions from LNCM, resulting in improved cyclic stability and rate capability of LNCM. [ABSTRACT FROM AUTHOR]

Vanadium dioxide (VO 2 ) nano-sheets were directly synthesized via a continuous hydrothermal process and were investigated as electrodes in a wide potential range of 0.05–3 V vs. Li/Li + . The nano-sheets showed excellent capacity retention, with a specific capacity of 350 mAh g − 1 at an applied current of 0.1 A g − 1 and 95 mAh g − 1 at 10 A g − 1 . Further electrochemical testing suggested that a significant proportion of the charge storage in the cells was due to pseudocapacitive processes. [ABSTRACT FROM AUTHOR]

Germanium is considered as a promising anode material because of its comparable lithium and sodium storage capability, but it usually exhibits poor cycling stability due to the large volume variation during lithium or sodium uptake and release processes. In this paper, germanium@graphene nanofibers are first obtained through electrospinning followed by calcination. Then atomic layer deposition is used to fabricate germanium@graphene@TiO2 core-shell nanofibers (Ge@G@TiO2 NFs) as anode materials for lithium and sodium ion batteries (LIBs and SIBs). Graphene and TiO2 can double protect the germanium nanofibers in charge and discharge processes. The Ge@G@TiO2 NFs composite as an anode material is versatile and exhibits enhanced electrochemical performance for LIBs and SIBs. The capacity of the Ge@G@TiO2 NFs composite can be maintained at 1050 mA h g−1 (100th cycle) and 182 mA h g−1 (250th cycle) for LIBs and SIBs, respectively, at a current density of 100 mA g−1, showing high capacity and good cycling stability (much better than that of Ge nanofibers or Ge@G nanofibers). [ABSTRACT FROM AUTHOR]

Scrupulous design and fabrication of advanced anode materials are of great importance for developing high-performance lithium ion batteries. Herein, we report a facile strategy for construction of free-standing and free-binder 3D porous carbon coated MoS 2 /nitrogen-doped graphene (C-MoS 2 /N-G) integrated electrode via a hydrothermal-induced self-assembly process. The preformed carbon coated MoS 2 is strongly anchored on the porous nitrogen-doped graphene aerogel architecture. As an anode for lithium ion batteries, the C-MoS 2 /N-G electrode delivers a high first discharge capacity of 1600 mAh g −1 and maintains 900 mAh g −1 after 500 cycles at a current density of 200 mA g −1 . Impressively, superior high-rate capability is achieved for the C-MoS 2 /N-G with a reversible capacity of 500 mAh g −1 at a high current density of 4000 mA g −1 . Furthermore, the lithium storage mechanism of the obtained integrated electrode is investigated by ex-situ X-ray photoelectron spectroscopy and transmission electron microscopy in detail. [ABSTRACT FROM AUTHOR]

This work introduces a simple microwave method for the preparation of α-Fe 2 O 3 nanoparticles with two different sizes. Both the materials were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and Brunauer–Emmett–Teller methods. The lithium storage properties were evaluated and compared in terms of their reversible capacity, rate capability and cycling performance. Interestingly, the electrode made of large particles (200–300 nm) show the reversible capacity of 1012 mA h g −1 , better rate capability and excellent cycling stability than those of the small particles (20–30 nm). The poor electrochemical performances of small particles can be ascribed to their agglomeration during repeated charging and discharge process. The agglomeration of small particles may substantially decrease the surface area, which results in the lack of sufficient electro active sites for electrochemical reaction. [ABSTRACT FROM AUTHOR]

Nitrogen-containing carbon/graphene composite (CGC) nanosheets have been synthesized by the in situ chemical polymerization of pyrrole on both surfaces of graphene oxide combined with high temperature carbonization. The CGC nanosheets show high specific surface area (106.22 m 2 g −1 ), large pore volume (0.382 m 3 g −1 ), and high nitrogen content (7.86 at.%). The nitrogen-containing carbon coating with low graphitization degree on both sides of graphene can prevent effectively from the aggregation of graphene oxide during its thermal reduction process. When evaluated for lithium storage capacity, the CGC nanosheets exhibit enhanced electrochemical performances in comparison with polypyrrole derived nitrogen-containing carbon (NC) nanoparticles, including high reversible capacity (651.5 mAh g −1 at 1 A g −1 ), excellent rate capability (363.7 mAh g −1 at 10 A g −1 ), and good cycling stability (100% capacity retention after 100 cycles at 1 A g −1 ). The high lithium storage performances of the CGC electrodes can be attributed to the high electronic conductivity, abundant lithium adsorption sites, and short diffusion distance of lithium ions arising from the CGC nanosheets with nitrogen-containing carbon on both sides of graphene. [ABSTRACT FROM AUTHOR]

Ultrathin MoSe 2 /graphene hybrids have been successfully synthesized through a facile ionic liquid-assisted hydrothermal approach. The resultant hybrids are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). It is revealed that the MoSe 2 nanosheets in the hybrids exhibit a graphene-like few-layered structural characteristic of 2–3 layers and are well dispersed and anchored on the large flexible graphene sheets. When evaluated as an anode for LIBs, the obtained MoSe 2 /graphene hybrid electrode demonstrates preferable electrochemical performances with high reversible lithium-storage capacity of ∼1100 mAh g −1 , superior cyclic stability and excellent rate capability. The extraordinary electrochemical properties can be ascribed to the novel hybrid structures composed of ultrathin few-layered MoSe 2 nanosheets and highly conductive graphene as well as the resultant maximized synergistic effect between MoSe 2 and graphene. [ABSTRACT FROM AUTHOR]

Synthesis of materials with desirable nanostructures is a hot research topic owing to their enhanced performances in contrast to the bulk counterparts. Herein, dumbbell-shaped cobalt carbonate (CoCO 3 ) nano architectures and the bulk counterpart of CoCO 3 rhombohedra are prepared via a facile hydrothermal route in the presence and absence of ascorbic acid (AA), respectively. By comparison, it has been found that: the addition of AA in the hydrothermal crystallization system changes the shape of the building blocks from Co 2 CO 3 (OH) 2 nanosheets to CoCO 3 nanoparticles, and then further influences the final configuration of the products. When applied as anodes of lithium ion batteries, CoCO 3 dumbbells deliver a 100th capacity of 1042 mAh g −1 at 200 mA g −1 and even exhibit a long-term value of 824 mAh g −1 over 500 cycles at 1000 mA g −1 , which are much higher than the rhombohedral counterparts with corresponding 540 and 481 mAh g −1 respectively. The much higher capacity, better cycling stability and enhanced rate performance of CoCO 3 dumbbells can be attributed to the higher specific surface area, smaller charge transport resistance and better structure stability resulting from the slight doping (∼4.6 wt%) of AA, and also relate with a novel lithium storage mechanism in CoCO 3 . [ABSTRACT FROM AUTHOR]

This study was focused on recycling process newly proposed to recover electrodic powder enriched in cobalt (Co) and lithium (Li) from spent lithium ion battery. In addition, this new process was designed to prevent explosion of batteries during thermal treatment under inert atmosphere. Spent lithium ion batteries (LIBs) were heated over the range of 300°C to 600°C for 2 hours and each component was completely separated inside reactor after experiment. Electrodic powder was successfully recovered from bulk components containing several pieces of metals through sieving operation. The electrodic powder obtained was examined by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and atomic absorption spectroscopy (AA) and furthermore image of the powder was taken by scanning electron microscopy (SEM). It was finally found that cobalt and lithium were mainly recovered to about 49 wt.% and 4 wt.% in electrodic powder, respectively. [ABSTRACT FROM AUTHOR]