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Advanced cathode materials for high power and great cycle stability have attracted much attention. Layer-structured NH4V3O8 (NVO) has been intensively studied because by their large distance between the layers and high discharge capacity. Nevertheless, the cycling stability of NVO is seriously restrained by the low electrical conductivity and poor lithium-ion diffusion ability. In this research, reduced graphene oxide nanosheets decorated carbon-coated NH4V3O8 (G-NVO@C) were synthesized through a facile one-step solvothermal method. As the cathode material for lithium-ion batteries, the G-NVO@C electrode exhibits outstanding cycling stability. The first discharge capacity is 220.6 mAh g−1 at a current density of 15 mA g−1. After 200 cycles, the discharge capacity is still maintained as high as 172.6 mAh g−1, and a retention of 78.2% was achieved. It is noteworthy that the specific discharge capacity decreased rapidly only in the first five cycles and then stabilized. These characteristics indicate that the G-NVO@C electrode has a broad application as cathode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Self-assembled cactus-like NH 4 V 3 O 8 is prepared through polyethylene glycol (PEG)-assisted hydrothermal synthesis method. The samples are characterized by X-ray diffraction and scanning electron microscopy techniques. Adjusting the pH value of the solution can effectively control the morphology of NH 4 V 3 O 8. The electrochemical measurements indicate that the sample which pH value is 3.7, shows the best cycling performance. It delivers an initial discharge capacity is 228 mAh g−1 and maintains at 156 mAh g−1 under 15 mA g−1 after 50 cycles. The proposed synthetic method can also be developed to address other electrode materials with inferior electronic conductivity and lithium ion diffusion. Schematic illustration of cactus-like NH 4 V 3 O 8 by PEG4000-assisted hydrothermal method Image, graphical abstract [ABSTRACT FROM AUTHOR]