A three-dimensional (3D) network structure Si/C anode with large pores is fabricated by using gelatin-PVA as carbon source. Silicon particles are embedded in the 3D network carbon skeleton. Gaussian calculation and FTIR test are employed to analyze the role of molecules interaction in forming the 3D network structure. The modified Si/C anode exhibits a reversible capacity of 830 mA h g−1 after 100 cycles at 400 mA g−1, and a capacity of 810 mA h g−1 at 1.6 A g−1 and 521 mA h g−1 at 3.2 A g−1. The 3D network structure with large pores benefits the electrolyte penetration, and the carbon coating layer avoids the direct contact of silicon particles with the electrolyte. The carbon layer can also help buffer the volume expansion of silicon, which is good to the cycling stability. All these aspects contribute to the enhanced electrochemical performance of the Si anode.

A spherical-like Ni0.6Co0.2Mn0.2(OH)2 precursor was tuned homogeneously to synthesize LiNi0.6Co0.2Mn0.2O2 as a cathode material for lithium-ion batteries. The effects of calcination temperature on the crystal structure, morphology, and the electrochemical performance of the as-prepared LiNi0.6Co0.2Mn0.2O2 were investigated in detail. The as-prepared material was characterized by X-ray diffraction, scanning electron microscopy, laser particle size analysis, charge–discharge tests, and cyclic voltammetry measurements. The results show that the spherical-like LiNi0.6Co0.2Mn0.2O2 material obtained by calcination at 900°C displayed the most significant layered structure among samples calcined at various temperatures, with a particle size of approximately 10 μm. It delivered an initial discharge capacity of 189.2 mAh•g−1 at 0.2C with a capacity retention of 94.0% after 100 cycles between 2.7 and 4.3 V. The as-prepared cathode material also exhibited good rate performance, with a discharge capacity of 119.6 mAh•g−1 at 5C. Furthermore, within the cut-off voltage ranges from 2.7 to 4.3, 4.4, and 4.5 V, the initial discharge capacities of the calcined samples were 170.7, 180.9, and 192.8 mAh•g−1, respectively, at a rate of 1C. The corresponding retentions were 86.8%, 80.3%, and 74.4% after 200 cycles, respectively.

•The electrochemical properties of the LiNi0.6Co0.2Mn0.2O2 cathode are investigated at high voltage of 4.6 V.•The Li2SiO3 suppresses the decomposition of LiPF6 and carbonate solvents.•Li2SiO3 helpfully retards the transition metal dissolution by consuming HF.•The enhanced electrochemical properties of the LiNi0.6Co0.2Mn0.2O2 cathode mixed with Li2SiO3.Developing high-voltage Li ion batteries (LIBs) is an important trend to meet the requirement of high energy density battery. However, high voltage will cause a series of problems harming the cycle performance of LIBs at the same time. This work is to investigate the effect of inorganic substance Li2SiO3 on the electrochemical performance of LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode at high cutoff voltage of 4.6 V. XRD result shows that the structure of NCM622 cathode material is not affected by mixing Li2SiO3. However, XPS and EIS tests indicate that Li2SiO3 has an evident influence on suppressing the decomposition of LiPF6 and carbonate solvents at high voltage, reducing interfacial solid film impedance and modifying electrode/electrolyte interface. In addition, Li2SiO3 retards the transition metal dissolution by consuming HF. Therefore, it enhances the electrochemical properties of the NCM622 cathode significantly. The highest discharge capacity increases to 191.7 mA h g-1 by mixing Li2SiO3, compared with the value of 180 mA h g-1 in the case of NCM622 cathode. The NCM622 electrode mixed with Li2SiO3 also exhibits a better capacity retention of 73.4% after 200 cycles and a high rate capability at 20C with the value of 89 mA h g-1, in contrast with 62.2% and 31 mA h g-1 attained in the NCM622 cathode.

Soluble lithium polysulfide intermediates dissolve and shuttle during the process of charge/discharge, leading to the rapid capacity decline of a Li–S battery. Density functional theory (DFT) computation is used to research the thermodynamic behavior of the polysulfides. The computation indicates that the stable molecular structures tend to be in a ring shape. This is helpful for cathode modification at a molecular level to fix the polysulfides.

•LiCoPO4 submicron single crystals are controlled synthesized by solvothermal method.•Influence of EG/water ratio on the morphology and performance is investigated.•LCP-4/C displays a superior discharge capacity and a good cycling performance.•The energy density is 576 W h kg−1 based on its discharge capacity and voltage.The submicron single crystals of LiCoPO4 with 500 nm diameter are prepared by solvothermal method. The carbon coated sample is obtained using sucrose as carbon source under 650 °C subsequently. It is investigated that the solvent composition has an effect on the morphology and the electrochemical performance of the cathode material. The as-prepared samples are characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopic, dynamic light scattering, and Fourier transform infrared spectra. The electrochemical performance is evaluated by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The LiCoPO4/C cathode can reach an initial discharge capacity of 123.8 mA h g−1 at 0.1C, with a retention of 83% after 100 cycles. A discharge capacity of 84.9 mA h g−1 is still attainable when the rate is up to 2C. The good cycling performance and rate capability are contributed to the decrease of particle size along with the lower antisite defect concentration in the LCP crystals, and uniform carbon coating.

•Gelatin binder is alternatively adopted to modify Si anode.•With a controlled heat-treatment, a carbonized gelatin binder is formed.•The modified Si anode shows a good electrochemical performance.•It is a simple and environmentally friendly approach for Si anode modification.Gelatin is alternatively adopted as the binder to modify Si anode coupling with its carbonization treatment. The binder can provide good bonding and uniform dispersion of the particles besides its environmental benignancy. Importantly, the carbonized binder containing nitrogen will be advantageous to the electrical conductivity of the electrode. In addition, some spaces are formed in the electrode due to the decomposition and shrinkage of the gelatin binder during heat-treatment, which may facilitate electrolyte penetration and accommodate volume change during cycling. All these merits make contribution to the good electrochemical performance of the modified Si electrode. It exhibits a reversible capacity of 990.3 mA h g−1 after 70 cycles at a current density of 100 mA g−1 and 904 mA h g−1 after 100 cycles at 400 mA g−1.

•Facile synthesis of graphitic carbon/α-Fe2O3 nano-sized anode composite.•In situ low temperature catalytic graphitization of biomass material.•Onion-like graphitic carbon layers conformally encapsulating around α-Fe2O3 core.•High lithium storage properties, especially, outstanding cycle performance.A delicate structure of graphitic carbon-encapsulated α-Fe2O3 nanocomposite is in situ constructed via “Absorption–Catalytic graphitization–Oxidation” strategy, taking use of biomass matter of degreasing cotton as carbon precursor and solution reservoir. With the assistance of the catalytic graphitization effect of iron core, onion-like graphitic carbon (GC) shell is made directly from the biomass at low temperature (650 °C). The nanosized α-Fe2O3 particles would effectively mitigate volumetric strain and shorten Li+ transport path during charge/discharge process. The graphitic carbon shells may promote charge transfer and protect active particles from directly exposing to electrolyte to maintain interfacial stability. As a result, the as-prepared α-Fe2O3@GC composite displays an outstanding cycle performance with a reversible capacity of 1070 mA h g−1 after 430 cycles at 0.2C, as well as a good rate capability of ∼ 950 mA h g−1 after 100 cycles at 1C and ∼ 850 mA h g−1 even up to 200 cycles at a 2C rate.

•A single-crystal LiNi0.6Co0.2Mn0.2O2 is prepared by a hydrothermal method.•A high discharge capacity of 183.7 mA h·g−1 at 0.2 C and good cycling stability.•It yields an initial discharge capacity of 153.6 mA h·g−1 at 10 C-rate under 2.8 V–4.3 V.•Superior electrochemical performance may be obtained attributed to the single-crystal structure.Single-crystal nickel-high materials (ST-LNCMO) LiNi0.6Co0.2Mn0.2O2 have been synthesized using a versatile hydrothermal method. The as-prepared samples are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), and selected area electron diffraction (SAED). The results show that the sample annealed at an optimized temperature of 850 °C reveals uniform fine well-crystallized single-particles with diameters of ～800 nm. Electrochemical data demonstrate that the cell using this nickel-high material as the cathode exhibits excellent performance. The sample displays a high capacity of 183.7 mA h·g−1 at 36 mA·g−1 (0.2 C) and excellent cycling stability at different rates. It yields an initial discharge capacity of 153.6 mA h·g−1 at a rate of 10C-rate and a voltage of 2.8 V – 4.3 V. The sample also has an outstanding rate capacity at a high cut-off voltage (4.6 V). This superior performance is attributed to the merits of the single-crystal structure, which may be beneficial to the transportation of the Li+ ion along the grain.

•One step synthesis of LTO/C composite with low cost sucrose as carbon source.•Nanosized LTO composite (13 nm) with high electronic conductivity (10−4 S cm−1).•Outstanding ultrafast charge/discharge performance.Nano-structured Li4Ti5O12 crystals coated with carbon layer are in situ synthesized via one-step liquid process taking advantage of low-cost sucrose as carbon source in this work. The as-prepared LTO/C particles present much larger specific surface area (58 m2 g−1) relative to the value of pure LTO, with a size around 13 nm in average. Its electronic conductivity of 6.56 × 10−4 S cm−1 is over three orders of magnitude higher than the pure one. The composite anode displays a distinguished electrochemical charge/discharge performance, especially, quite high rate capability along with a stable cyclability. It delivers the initial discharge specific capacities of 156.7 and 142.1 mA h g−1 at 40C and 60C respectively, and remains the values of 114.2 and 98.1 mA h g−1 after 200 cycles. Furthermore, a capacity of 132.8 mA h g−1 is delivered even at an 80C rate and the value of 82.7 mA h g−1 can be maintained after 200 cycles. The ultrafast charge/discharge capability may be attributed to the shorten Li+ transport path in the nanosized composite and the enlarged access area with electrolyte. Additionally, the carbon coating may provide an effective conductive network among the particles promoting charge transfer.

We report a novel slurry electrolyte with ultrahigh concentration of insoluble inorganic lithium metasilicate (Li2SiO3) that is exploited for lithium ion batteries to combine the merits of solid and liquid electrolytes. The safety, conductivity, and anodic and storage stabilities of the eletrolyte are examined, which are all enhanced compared to a base carbonate electrolyte. The compatibility of the elecrolyte with a LiNi0.5Mn1.5O4 cathode is evaluated under high voltage. A discharge capacity of 173.8 mAh g–1 is still maintained after 120 cycles, whereas it is only 74.9 mAh g–1 in the base electrolyte. Additionally, the rate capability of the LiNi0.5Mn1.5O4 cathode is also improved with reduced electrode polarization. TEM measurements indicate that the electrode interface is modified by Li2SiO3 with a thinner solid electrolyte interphase film. Density functional theory computations demonstrate that LiPF6 is stabilized against its decomposition by Li2SiO3. A possible path for the reaction between PF5 and Li2SiO3 is also proposed by deducing the transition states involved in the process using the DFT method.Keywords: cycling stability; high voltage; lithium metasilicate; slurry electrolyte; ultrahigh concentration

A novel hierarchical structure carbon/sulfur composite is presented based on carbon fiber matrices, which are synthesized by electrospinning. The fibers are constituted with hollow graphitized carbon spheres formed using catalytic Ni nano-particles as hard templates. Sulfur is loaded to the carbon substrates via thermal vaporization. The structure and composition of the hierarchical carbon fiber/S composite are characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and nitrogen adsorption isotherms. The electrochemical performance is evaluated by cyclic voltammetry and galvanostatic charge–discharge. The results exhibit an initial discharge capacity of 845 mA h g−1 at 0.25 C (420 mA g−1), with a retention of 77% after 100 cycles. A discharge capacity of 533 mA h g−1 is still attainable when the rate is up to 1.0 C. The good cycling performance and rate capability are contributed to the uniform dispersion of sulfur, the conductive network of carbon fibers and hollow graphitized carbon spheres.

The paper reports a novel composite with ZnO and Cu nanocrystals implanted into carbon nanofibers (CNFs) and its lithium storage properties, in particular its high rate performance. Fabrication of the fibrous composite is controllably accomplished utilizing an electrospinning approach. The composite electrode exhibits a high reversible capacity of 812 mA h g−1 at a current density of 100 mA g−1 after 50 cycles. Moreover, it shows good rate capability even when cycled at 5000 mA g−1. This can be attributed to the designed nano-fibrous architecture with active material implantation as well as electroconductive Cu introduction. The interconnected particles of ZnO and Cu on the CNFs ensure a good contact in the composite. Moreover, the one-dimensional CNFs act not only as a supporter with good stability, but also provide a shortened transport pathway for Li ions.

A novel foamlike Fe3O4/C composite is prepared via a sol–gel type method with gelatin as the carbon source and ferric nitrate as the iron source, following a postannealing treatment. Its lithium storage properties as anode material for a lithium-ion battery are thoroughly investigated in this work. With the interaction between ferric nitrate and gelatin, the foamlike architecture is attained through a unique self-expanding process. The Fe3O4/C composite possesses abundant porous structure along with highly dispersed Fe3O4 nanocrystal embedment in the carbon matrix. In the constructed architecture, the 3D porous network property ensures electrolyte accessibility; meanwhile, nanosized Fe3O4 promotes lithiation/delithiation, owing to numerous active sites, large electrolyte contact area, and a short lithium ion diffusion path. As a result, this Fe3O4/C composite electrode demonstrates an excellent cycling stability with a reversible capacity of 1008 mA h g–1 over 400 cycles at 0.2C (1C = 1000 mA g–1), as well as a superior rate performance with reversible capacity of 660 and 580 mA h g–1 at 3C and 5C, respectively.Keywords: anode; foamlike structure; lithium-ion batteries; magnetite; self-expanding process

•A novel sand-like electrolyte is prepared.•The anodic stability of sand-like electrolyte is superior in the presence of Li2SiO3.•Cycling stability of 5 V LiNi0.5Mn1.5O4 is enhanced.•Intensive electrolyte oxidation is supressed during cycling under high potential.•Li2SiO3 can consume the PF5 and HF in electrolyte.The electrochemical performance of LiNi0.5Mn1.5O4 is investigated in a sand-like carbonate electrolyte containing 4 wt.% lithium metasilicate (Li2SiO3). The capacity fading rate of the LiNi0.5Mn1.5O4 electrode working in the sand-like electrolyte (2-5 V) is reduced to 0.171 mAh g−1 per cycle, quite smaller than the value of 0.613 mAh g−1 per cycle in the electrolyte without Li2SiO3. The capacity of 159.5 mAh g−1 is delivered at 0.5 C after 118 cycles while it is only 99.4 mAh g−1 for the Li2SiO3-free counterpart. Cyclic voltammetry, scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopic measurements are conducted to explore the modification mechanism. It is found that the anodic stability of the sand-like electrolyte is improved compared to the base electrolyte. The Li2SiO3 precipitates on the electrode surface make contribution to the performance enhancement of the cathode at high potential.

An electrolyte (LiPF6–EC/PC/DEC) containing a lithium carbonate (Li2CO3) additive is used to enable the high cycling stability of a lithium cobalt oxide (LiCoO2) cathode which is charged to 4.5 V for a higher capacity. A capacity as high as 162.8 mA h g−1 (1 C) is maintained after 116 cycles, which is twice as high as the capacity of 88.5 mA h g−1 which was achieved in the Li2CO3 free instance. The interface properties of the electrode are investigated by cyclic voltammetry, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. It is found that the solid electrolyte interphase (SEI) film tends to be thin and steady, and that the electrolyte decomposition is suppressed with the addition of Li2CO3. A possible mechanism is proposed according to the DFT calculation. The results indicate that the Co4+…CO32− coordination may decrease the oxidizability of Co4+ on the electrode surface so that the electrolyte decomposition could be suppressed.

A new desolvated gel electrolyte (DGE) is investigated for its use in lithium metal sulfurized polyacrylonitrile (S-PAN) battery. Lithium dendrite growth is examined under the DGE by scanning electron microscope (SEM). The electrolyte desolvation is analyzed with IR and 1H NMR spectra as well as density functional theory (DFT) calculation using Gaussian09 package. The electrochemical performance of S-PAN cathode is compared under the DGE and a common electrolyte via galvanostatic charge/discharge. The growth mode of Li dendrite is schematically illustrated to elucidate the role of the DGE during the charge/discharge process. It is shown that the DGE can prevent the growth of dendrite from the Li anode surface. A specific capacity of 1276 mAh/g is retained under the DGE after 50 cycles at 60 mA/g current rate. It is indicated that the as-prepared gel electrolyte is desolvated, which is also confirmed with the theoretical calculation. The DGE weakens the solvation effect of the lithium ions and reduces the resistance of charge transfer at cathode/electrolyte interface; it increases lithium ion transference number as well, so enhancing the electrochemical performance of the cathode.

ZnO-loaded/porous carbon (PC) composites with different ZnO loading amounts are first synthesized via a facile solvothermal method and evaluated for anode materials of lithium ion batteries. The architecture and the electrochemical performance of the as-prepared composites are investigated through structure characterization and galvanostatic charge/discharge test. The ZnO-loaded/PC composites possess a rich porous structure with well-distributed ZnO particles (size range: 30–100 nm) in the PC host. The one with 54 wt % ZnO loading contents exhibits a high reversible capacity of 653.7 mA h g–1 after 100 cycles. In particular, a capacity of 496.8 mA h g–1 can be reversibly obtained when cycled at 1000 mA g–1. The superior lithium storage properties of the composite may be attributed to its nanoporous structure together with an interconnected network. The modified interfacial reaction kinetics of the composite promotes the intercalation/deintercalation of lithium ions and the charge transfer on the electrode. As a result, the enhanced capacity of the composite electrode is achieved, as well as its high rate capability.Keywords: anode material; composite; lithium ion batteries; porous carbon; zinc oxide;

In this study, the sorting of nickel–metal hydride batteries is investigated based on their charging thermal behavior. A self-organization map (SOM) model affiliated to artificial neural network is constructed to conduct the sorting work. The sorting principle is described in detail to support the model. A batch of batteries is charged in various rates to collect training data closely related to battery thermal behavior. It is indicated that the model can master the regulation of sorting well after training. As a result, the batteries are classified by the SOM model into three categories of high heat generation battery, middle heat generation battery, and low heat generation battery, which corresponds well with the training result. The model thus allows the batteries in the same category to be selected for the consistency in thermal behavior as well as discharge performance.Highlights► Ni–MH battery sorting is investigated based on charging thermal behavior. ► An SOM model is constructed to conduct the sorting work. ► Batteries are effectively sorted into three categories by the model. ► Batteries sorted in each category can keep consistency in thermal behavior and discharge performance.

In this study, a prediction model based on artificial neural network is constructed for surface temperature simulation of nickel–metal hydride battery. The model is developed from a back-propagation network which is trained by Levenberg–Marquardt algorithm. Under each ambient temperature of 10 °C, 20 °C, 30 °C and 40 °C, an 8 Ah cylindrical Ni–MH battery is charged in the rate of 1 C, 3 C and 5 C to its SOC of 110% in order to provide data for the model training. Linear regression method is adopted to check the quality of the model training, as well as mean square error and absolute error. It is shown that the constructed model is of excellent training quality for the guarantee of prediction accuracy. The surface temperature of battery during charging is predicted under various ambient temperatures of 50 °C, 60 °C, 70 °C by the model. The results are validated in good agreement with experimental data. The value of battery surface temperature is calculated to exceed 90 °C under the ambient temperature of 60 °C if it is overcharged in 5 C, which might cause battery safety issues.Highlights► We proposed a prediction model for surface temperature simulation of Ni–MH battery. ► It was an ANN model that developed from BP network. ► The model was of excellent training quality and its prediction was accurate. ► The predicted maximum value implied the battery might be in unsafe case. ► The model could be applied to battery thermal management system.

•Advances on layered LiNixCoyMn1−x−yO2 (x ≥ 0.5) positive electrode materials.•Detailed discussion on the preparation, microstructure, modification, etc.•Structure stability, interface compatibility of the positive electrode materials.•The challenges and prospects of nickel-rich layered oxide materials.High energy density lithium-ion batteries are eagerly required to electric vehicles more competitive. In a variety of circumstances closely associated with the energy density of the battery, positive electrode material is known as a crucial one to be tackled. Among all kinds of materials for lithium-ion batteries, nickel-rich layered oxides have the merit of high specific capacity compared to LiCoO2, LiMn2O4 and LiFePO4. They have already become one of the most attractive candidates for the mainstream batteries in industries. In this work, the recent advances on three commonly concerned nickel-rich layered oxides are presented. The preparation, microstructure, electrochemical performances are focused, the modification including coating design as well as dopant selection is specially discussed in details, which is essential to enhance the durability and energy density of lithium-ion batteries. Additionally, the prospects and challenges are also systematically discussed, as well as the potential applications in the field of energy storage technologies.

The paper reports a novel composite with ZnO and Cu nanocrystals implanted into carbon nanofibers (CNFs) and its lithium storage properties, in particular its high rate performance. Fabrication of the fibrous composite is controllably accomplished utilizing an electrospinning approach. The composite electrode exhibits a high reversible capacity of 812 mA h g−1 at a current density of 100 mA g−1 after 50 cycles. Moreover, it shows good rate capability even when cycled at 5000 mA g−1. This can be attributed to the designed nano-fibrous architecture with active material implantation as well as electroconductive Cu introduction. The interconnected particles of ZnO and Cu on the CNFs ensure a good contact in the composite. Moreover, the one-dimensional CNFs act not only as a supporter with good stability, but also provide a shortened transport pathway for Li ions.