Ionic liquid assisted multi-heteroatom doping in core-shell ZnFe2O4@rGO with highly reversible lithiation/delithiation kinetics

Abstract

Mixed transition metal oxides with low-cost elements such as ZnFe2O4 have been considered as the promising candidate as anode materials for Li-ion batteries (LIBs) owing to the high capacity originated from versatile redox reactions. However, poor conductivity and huge volume expansion during charging/discharging cause drastic capacity decay, which hinders their commercial application. Herein, we designed a unique core-shell N doped ZnFe2O4 embedded in B, N doped graphene network (B/N-ZFO@rGO) using ionic liquids as multi-heteroatom source through facile hydrothermal reaction. Benefiting from the enhanced conductivity and structural stability, the B/N-ZFO@rGO as anode material for LIBs not only shows significantly improved specific capacity (668.1 mAh g−1 at 1 A g−1 after 100 cycles), but also remarkable rate capacity and long cycle life (377.4 mAh g−1 at 5 A g−1 after 1200 cycles), demonstrating great potential in future applications. Moreover, such rational design of structure as well as multiple elements doping using ionic liquids can be extensively applied in other electrode materials.