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Due to the urgency of developing high energy density cathode materials in power batteries, as well as the high price and environmental unfriendliness of cobalt, researchers are working on ultra-high nickel low cobalt and ultra-high nickel cobalt-free layered cathode materials. However, the poor cyclic stability and rate performance of this material resulted from structural instability and severe surface/interface side reactions during cycling seriously hinder its practical application. In this paper, LiNi0.9Mn0.1O2 (NM90) cathode material is modified by La2O3 coating, and La3+ doping caused by thermal diffusion is achieved simultaneously. The synergistic enhancement of the two modifications can effectively improve the layered structure and reduce surface/interface side reactions. The dual-modified material shows good structural stability, the La2O3 coating does not fall off and the active material does not appear fragmentation and collapse after 100 cycles. At the same time, the dual-modified material also shows excellent electrochemical performance, with a capacity retention of 83.19% after 100 cycles at 1 C and a reversible capacity of 129.9 mAh g−1 at 10 C. The electrochemical mechanism reveals that the dual-modified material effectively reduces the charge transfer resistance and greatly increases the Li+ diffusion coefficient. It will provide useful reference and technical support for the research of other electrode materials. The NM90 and La2O3-coated NM90 particles have similar spherical morphology and are formed by the agglomeration of many primary particles; the surface of NM90 material is evenly coated by La2O3 and No obvious boundary between La2O3 and NM90 materials is found; LiNi0.9Mn0.1O2 cathode material coated by 1wt% La2O3 has the best cycle stability. [ABSTRACT FROM AUTHOR]

Regular spherical FePO4/3DG precursor with good dispersion, uniform morphology, and diameters of 2~3 μm was hydrothermally synthesized, followed by synthesizing LiFePO3.98F0.02/3DG/C material via a two-step carbothermal reduction technology with ascorbic acid and glucose as carbon sources. The morphology, structure, and carbon content of the material were characterized by SEM, XRD, XPS, TEM, and thermogravimetric analyzer (TGA). The electrochemical properties of material were systematically studied by means of constant current charge and discharge, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The results revealed that the initial discharge specific capacity of LiFePO0.98F0.02/3DG/C material was 158.7, 144.5, 130.4, 114.8, 96.8, and 80.3 mAh/g at 0.2 C, 0.5 C, 1 C, 2 C, 5 C, and 10 C, respectively, and the capacity retention rate still remained 98.9% after 100 cycles at 0.2 C, indicating excellent rate performance and cycle stability. Obviously, LiFePO3.98F0.02/3DG/C material exhibited remarkable improvement in comparison with the pristine LiFePO4 material. Therefore, the synergy of F− doping and 3DG coating was an effective method in synthesis of high electrochemical performance LiFePO4 composite material. [ABSTRACT FROM AUTHOR]

In this work, we investigate the influence of water content on the lithium storage performance of α-Ni(OH)2 samples prepared by homogeneous precipitation method and subsequent heat treatment at different temperatures. It is found that the adsorbed water in α-Ni(OH)2 has a decisive impact on the cycling stability and rate capability of the electrode; in contrast, the effect of interlayer water contents is not significant. For example, the α-Ni(OH)2 sample with adsorbed water molecules (heat-treated at 100 °C) delivers a reversible specific capacity of 1115 mAh g−1 at 500 mA g−1 after 30 cycles, while the α-Ni(OH)2 sample after removing the adsorbed molecules (heat-treated at 150 °C) gives a capacity of only 516 mAh g−1 under the same measurement condition. EIS and CV analyses reveal that the adsorbed water molecules in α-Ni(OH)2 decrease the electrochemical reaction resistance, increase lithium ion diffusivity, and greatly enhance the pseudocapacitive charge storage behavior, which lead to superior performance in cycle life and rate capability. [ABSTRACT FROM AUTHOR]

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]

V2O5·nH2O/graphene composites have been fabricated via a facile sol–gel method followed with an annealing treatment in air. The influence of incorporation of graphene on the microstructure and sodium storage performance of V2O5·nH2O were investigated. XRD, Raman, and TGA analyses validated that graphene was successfully incorporated in V2O5·nH2O particles; XPS tests revealed that the incorporation of graphene induced more V4+ in the V2O5·nH2O. When evaluated as cathode materials for sodium-ion batteries (SIBs), the V2O5·nH2O/graphene composites exhibited higher sodium storage capacity, better rate capability, enhanced Na+ diffusivity, and lower electrochemical reaction resistance as compared to the pure V2O5·nH2O. However, the incorporation of graphene had no improvement of the cycling stability of V2O5·nH2O. Ex situ XRD demonstrated that the layered structure of V2O5·nH2O collapsed upon cycling, which accounts for the capacity decay of the samples. [ABSTRACT FROM AUTHOR]