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Monodisperse SnO2/Co3O4 nanocubes are designed and prepared via a thermally induced phase separation. X-ray diffraction measurement reveals that the composite is composed of SnO2 and Co3O4 phases. Scanning electron microscopy and transmission electron microscopy bring insight into the morphology of the nanocubes, which have a size of 100–200 nm and consist of tightly contacted SnO2 and Co3O4 grains with a size of 20–30 nm. X-ray photoelectron spectroscopy indicates that the SnO2 and Co3O4 are chemically bound with each other. Comparative study in electrochemical properties is implemented among the SnO2/Co3O4 nanocubes, pure SnO2, Co3O4, and physical mixture of SnO2 and Co3O4. Electrochemical characterizations suggest that the SnO2/Co3O4 nanocomposite has remarkably enhanced electrochemical reversibility, cycling stability, rate capability, and faster charge-transfer than the others. The results highlight the synergistic effect derived from the Sn–Co binding in electrochemical Li-ion storage. In addition, the phase separation method is considered as an effective way to produce heterojunctions within binary or ternary composites. [ABSTRACT FROM AUTHOR]

The dually decorated Na3V2(PO4)2F3 by in‐situ formed carbon and three‐dimensional graphene (NVPF/C@3DG) is prepared via two hydrothermal steps and a high‐temperature calcination. Benefiting from the high electronic conductivity of carbon and 3DG, high surface area and the resulted high diffusion coefficients of Na+, NVPF/C@3DG displays superior electrochemical performance to the control NVPF/C. Between 2.5 and 4.5 V (vs. Na+/Na), NVPF/C@3DG presents the initial discharge capacity of 123.6 mAh g−1 at 0.2 C (25.6 mA g−1) and capacity retention of 92.1 % after 60 cycles, while NVPF/C shows initial discharge capacity of 119 mAh g−1 and capacity retention of 84.1 % under the identical test conditions. Even at 15 C, the initial discharge capacity and capacity retention after 1000 cycles of NVPF/C@3DG are as high as 91.2 mAh g−1 and 82.9 %, respectively, much better than the initial discharge capacity of 71.2 mAh g−1 and the corresponding capacity retention of 76.4 % for NVPF/C, respectively. [ABSTRACT FROM AUTHOR]

Abstract: A novel Li3V2(PO4)3/C nanofibers composite has been first prepared by a facile and environmentally friendly electrospinning method using NH4VO3, CH3COOLi, poly (4-vinyl) pyridine (PVP) and citric acid aqueous solution as raw materials. The composite is investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and electrochemical tests. The Li3V2(PO4)3/C nanofibers composite exhibits excellent cycle performance and good rate capability in the voltage range of 3.0–4.8 V. The composite displays a high discharge capacity of 190 mAh g−1 (close to theoretical capacity of 197 mAh g−1) at 0.1 C (19.7 mA g−1). Even at a high-rate of 20 C, the composite presents the discharge capacity of 132 mAh g−1 and good cycle performance. The outstanding electrochemical performance is attributed to the particular morphology and microstructure of Li3V2(PO4)3/C nanofibers composite that dispersive Li3V2(PO4)3 nanofibers and carbon nanofibers aggregate to form nanofibers composite with mesopores and large surface area. [Copyright &y& Elsevier]

Abstract: The cycle performance of spinel LiMn2O4 at 25 and 55°C is improved by LaF3 modification via a chemical deposition method. The physical and electrochemical performances of pristine and LaF3-coated LiMn2O4 cathode materials are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical measurements. The coated LiMn2O4 with 2.92wt% LaF3 (LaF3-3-LMO) displays capacity retentions of 90.1% and 84.2% at 25 and 55°C, respectively, after 100 cycles, much higher than those of pristine LiMn2O4, 72.7% and 54.8%. The concentration of manganese dissolved from LaF3-3-LMO in electrolyte is much lower than that from pristine LiMn2O4. The analysis of AC impedance indicates that the charge transfer resistance (R ct) and the increase of R ct for LaF3-3-LMO during cycling are much lower than those for pristine LiMn2O4. The significantly improved electrochemical performance of the LaF3-coated LiMn2O4 can be attributed to the reduction of manganese dissolution in electrolyte and charge transfer resistance with the help of LaF3 coating. [Copyright &y& Elsevier]

Abstract: A LiFePO4/C submicrofibers composite was prepared by a facile electrospinning method using LiNO3, Fe(NO3)3·9H2O, NH4H2PO4, citric acid and poly(4-vinyl)pyridine (PVP) as raw materials, and its physical properties and electrochemical performance were investigated by X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), transmission electron microscope (TEM), energy dispersive analysis of X-ray (EDAX), N2 adsorption/desorption measurement and electrochemical tests. The crystal size of LiFePO4 fibers is about 30nm calculated by Debye-Scherrer equation and the LiFePO4 nanofibers aggregate to LiFePO4/C submicrofibers composite with diameters of about 270–372nm. The LiFePO4 submicrofibers are covered by an amorphous carbon layer with a thickness of about 2.6nm and the LiFePO4/C submicrofibers composite with mesopores exhibits amazing high surface area of 167.729m2 g−1. The LiFePO4/C submicrofibers composite displays high initial discharge capacities of 166 and 168mAhg−1 and excellent cycle performance at 0.1C (17mAhg−1) in the voltage range of 2.5–4.5V at 25 and 55°C, respectively. Even at high rate of 5C, the LiFePO4/C submicrofibers composite delivers discharge capacities of 132 and 138mAhg−1 and excellent cycle performance at 25 and 55°C, respectively. The results indicate that the electrospinning method is promising to prepare LiFePO4/C composite with high electrochemical performance. [Copyright &y& Elsevier]

Abstract: The composites of monoclinic Li3−x Na x V2(PO4)3 (x =0, 0.03, 0.05 and 0.07) and carbon are prepared by a sol–gel method. The composites are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical measurements. XRD results show that the cell volumes of the monoclinic Na-doped Li3V2(PO4)3 samples are larger than that of Li3V2(PO4)3. All Na-doped composites exhibit better electrochemical performance than that of pristine one and the Li2.95Na0.05V2(PO4)3/C composite displays highest capacity and best cycle performance. The Li2.95Na0.05V2(PO4)3/C composite presents initial capacities of 187 and 173.1mAhg−1 at 0.2C and 1C between 3.0 and 4.8V, respectively, much higher than that 175.5mAhg−1 (0.2C) and 153.4mAhg−1 (1C) of Li3V2(PO4)3/C composite. The capacity retentions of Li2.95Na0.05V2(PO4)3/C are 95.3% and 91% at 0.2C and 1C after 30 cycles, respectively, while the capacity retentions of Li3V2(PO4)3/C are 90.4% and 87% at 0.2C and 1C after 30 cycles, respectively. The rapid Li+ diffusion due to the doping of Na+ is responsible for the good electrochemical performance of Na-doped Li3V2(PO4)3 cathode materials. [Copyright &y& Elsevier]

Abstract: A carbon coated Li3V2(PO4)3 cathode material for lithium ion batteries was synthesized by a sol–gel method using V2O5, H2O2, NH4H2PO4, LiOH and citric acid as starting materials, and its physicochemical properties were investigated using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), transmission electron microscope (TEM), and electrochemical methods. The sample prepared displays a monoclinic structure with a space group of P21/n, and its surface is covered with a rough and porous carbon layer. In the voltage range of 3.0–4.3V, the Li3V2(PO4)3 electrode displays a large reversible capacity, good rate capability and excellent cyclic stability at both 25 and 55°C. The largest reversible capacity of 130mAhg−1 was obtained at 0.1C and 55°C, nearly equivalent to the reversible cycling of two lithium ions per Li3V2(PO4)3 formula unit (133mAhg−1). It was found that the increase in total carbon content can improve the discharge performance of the Li3V2(PO4)3 electrode. In the voltage range of 3.0–4.8V, the extraction and reinsertion of the third lithium ion in the carbon coated Li3V2(PO4)3 host are almost reversible, exhibiting a reversible capacity of 177mAhg−1 and good cyclic performance. The reasons for the excellent electrochemical performance of the carbon coated Li3V2(PO4)3 cathode material were also discussed. [Copyright &y& Elsevier]

Abstract: LiV3O8–Polypyrrole (LiV3O8–PPy) composite has been chemically synthesized by an oxidative polymerization of pyrrole monomer on the surface of LiV3O8 using ferric chloride as oxidizing agent. The electrochemical properties of LiV3O8–PPy composite were systematically investigated using a variety of electrochemical methods. The LiV3O8–PPy composite electrode exhibited better cycling behavior and superior rate capability as compared with the bare LiV3O8 electrode. Cyclic voltammetry corroborated the galvanostatic cycling tests, with the composite cathode material showing better reversibility than bare material. Finally, fitting the impedance results to an equivalent circuit indicated that the enhanced electrochemical performances of LiV3O8–PPy composite resulted from a facilitated kinetics of interfacial charge transfer in the presence of PPy. [Copyright &y& Elsevier]

Abstract: Orthorhombic structure FeF3 was synthesized by a liquid-phase method using FeCl3, NaOH and HF solution as starting materials, and the FeF3/V2O5 composites were prepared by milling the mixture of as-prepared FeF3 and the conductive V2O5 powder. The properties of FeF3/V2O5 composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), galvanostatic charge/discharge and cyclic voltammetry measurements. Results showed that the FeF3/V2O5 composites can be used as cathode material for lithium-ion battery. Electrochemical measurements in a voltage range of 2.0–4.5V reveal that the addition of conductive V2O5 improves significantly the electrochemical performance of FeF3, and the FeF3/V2O5 composite prepared by milling for 3h exhibits high discharge capacity and good cycle performance, and its discharge capacity maintains about 209mAhg−1 at 0.1C (23.7mAg−1) after 30 cycles. [Copyright &y& Elsevier]

Abstract: Orthorhombic structure FeF3 was synthesized by a liquid-phase method. The FeF3/MoS2 for the application of cathode material of lithium-ion battery was prepared through mechanical milling with molybdenum bisulfide. The structure and morphology of the FeF3/MoS2 were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical behavior of FeF3/MoS2 was studied by charge/discharge, cyclic voltammetry and electrochemical impedance spectra measurements. The results show that the prepared FeF3/MoS2 was typical orthorhombic structure, uniform surface morphology, better particle-size distribution and excellent electrochemical performances. The initial discharge capacity of FeF3/MoS2 was 169.6 mAh·g−1 in the voltage range of 2.0–4.5 V, at room temperature and 0.1 C charge–discharge rate. After 30 cycles, the capacity retention is still 83.1%. [Copyright &y& Elsevier]

LiNiO 2 cathode material for lithium-ion batteries has the advantages of high specific capacity, abundant resources, and low cost, but it suffers from difficulties in preparation, structural instability, and serious capacity decay. In this work, highly pure and layered structural LiNi 0.95 Al a Ti 0.05-a O 2 (a=0, 0.025, 0.05) cathode materials were synthesized by a simply sol-gel method. The cation mixing of Ni 2+ and Li + , structural deterioration, irreversible conversion between H2 and H3 phases and unstable surface and CEI (Cathode-electrolyte interface) film can be effectively suppressed by co-doping with Al 3+ and Ti 4+ . A preferred LiNi 0.95 Al 0.025 Ti 0.025 O 2 sample provides a discharge specific capacity of 223 mAh g -1 at 0.1 C and 148.32 mAh g -1 at 5 C, a capacity retention of 72.7 % after 300 cycles at 1 C and a Li + diffusion coefficient of about 2.0×10 -9  cm 2  s -1 ., (© 2023 Wiley-VCH GmbH.)

The electrochemical performances and process mechanisms of Zn/LiFePO 4 cells in a slightly acidic 1.9 m Li 2 SO 4 -0.5 m ZnSO 4 aqueous solution were investigated. The results showed that the hydrogen depletion side reaction on the surface of the zinc sheet led to an increase in pH of the electrolyte and fluctuations in specific capacity of the cells, and that the dissolution of Fe 2+ ions and the lamination of LiFePO 4 particles resulted in a decrease in the specific capacity of the cells. At pH 5.0, the initial discharge specific capacity of the Zn/LiFePO 4 cell was about 120.0 mAh g -1 at 0.25 C, about 64.4 mAh g -1 at 3 C, with about 60.9 % capacity retention rate after 200 cycles at 1 C, and the Li + ions diffusion coefficient was about 7.75×10 -12  cm 2  s -1 ., (© 2022 Wiley-VCH GmbH.)