Reduced graphene oxide nanosheets decorated carbon-coated NH${}_4$V${}_3$O${}_8$ as cathode materials with superior cycle stabilities for lithium-ion batteries

Advanced cathode materials for high power and great cycle stability have attracted much attention. Layer-structured NH${}_4$V${}_3$O${}_8$ (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 NH${}_4$V${}_3$O${}_8$ (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.