Two-dimensional NbO holey nanosheets prepared by a graphene sacrificial template method for high performance Mg/Li hybrid ion batteries.

Mg/Li hybrid ion batteries (MLIBs) are regarded as promising candidates for electrical energy devices due to their combination of a fast lithium intercalation cathode and a safe magnesium anode. Herein, two-dimensional NbO holey nanosheets are synthesized using a graphene oxide sacrificial template method and these are then used as the cathode of a MLIB for the first time. It exhibits a high discharge capacity (195.9 mA h g at 100 mA g), excellent rate performance (72.1 mA h g at 2000 mA g) and a long cycling life (exhibiting a capacity fading rate of 0.032% per cycle at 2000 mA g over 1000 cycles). The remarkable electrochemical performance can be attributed to the unique two-dimensional holey nanosheet structure, which is beneficial for improving electronic conductivity and lithium ion conductivity.