Copper niobate nanowires immobilized on reduced graphene oxide nanosheets as rate capability anode for lithium ion...

Binary metal niobium oxides can offer a higher specific capacity compared to niobium pentoxide (Nb₂O₅) and thus are ideal anode candidates for lithium ion capacitors (LICs). However, their lower electronic conductivity limits their ability to achieve high energy and power densities. In this paper, one-dimensional (1D) copper niobate (CuNb₂O₆) nanowires are successfully prepared by electrospinning technology and then immobilized on two-dimensional (2D) reduced graphene oxide (rGO) nanosheets to form a unique 1D nanowire/2D nanosheet CuNb₂O₆/rGO structure. The 1D/2D CuNb₂O₆/rGO electrode exhibits a high specific capacity of 312.2 mAh g^-1 at 100 mA g^-1 as the anode of LICs. The proposed Li⁺ storage mechanism of the CuNb₂O₆ anode involves CuNb₂O₆ decomposition into lithium niobate (Li₃NbO₄) and copper (Cu) during the initial lithium insertion process. The intercalation-type Li₃NbO₄ will further serve as the host to Li⁺ and the inactive Cu phase will act as a conductive network for electron transportation. Furthermore, the energy density of the assembled CuNb₂O₆/rGO//activated carbon (CuNb₂O₆/rGO//AC) device could achieve a value as high as 92.1 Wh kg^-1 and could thus be considered as a possible alternative electrode material for high energy and power LICs.