摘要
Layered metal oxides are promising cathode materials for sodium-ion batteries(SIBs)due to their high theoretical specific capacity and wide Na^(+)diffusion channels.However,the irreversible phase transitions and cationic/anionic redoxes cause fast capacity decay.Herein,P2-type Na_(0.67)Mg_(0.1)Mn_(0.8)Fe_(0.1)O_(2)(NMMF-1)cathode material with moderate active Fe^(3+)doping has been designed for sodium storage.Uneven Mn^(3+)/Mn^(4+)distribution is observed in NMMF-1 and the introduction of Fe^(3+)is beneficial for reducing the Mn^(3+)contents both at the surface and in the bulk to allevi-ate the Jahn-Teller effect.The moderate Fe^(3+)/Fe^(4+)redox can realize the best tradeoff between capacity and cycla-bility.Therefore,the NMMF-1 demonstrates a high capacity(174.7 mAh g^(-1)at 20 mA g^(-1))and improved cyclability(78.5%over 100 cycles)in a wide-voltage range of 1.5-4.5 V(vs.Na^(+)/Na).In-situ X-ray diffraction reveals a complete solid-solution reaction with a small volume change of 1.7%during charge/discharge processes and the charge com-pensation is disclosed in detail.This study will provide new insights into designing high-capacity and stable layered oxide cathode materials for SIBs.
基金
supported by the National Natural Science Foundation of China(U23A20684)
Independent Innovation Project of Hubei Longzhong Laboratory(2022ZZ-18).
