Two-dimensional Nb₂O₅ holey nanosheets prepared by a graphene sacrificial template method for high performance Mg²⁺/Li⁺ hybrid ion batteries

Mg²⁺/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 Nb₂O₅ 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^-1 at 100 mA g^-1), excellent rate performance (72.1 mA h g^-1 at 2000 mA g^-1) and a long cycling life (exhibiting a capacity fading rate of 0.032% per cycle at 2000 mA g^-1 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.