Designing advanced P3-type K0.45Ni0.1Co0.1Mn0.8O2 and improving electrochemical performance via Al/Mg doping as a new cathode Material for potassium-ion batteries

Developing stable and advanced cathode materials that accommodate larger K-ions becomes a serious challenge for potassium-ion batteries (KIBs). Herein, we propose a new layered oxide K0.45Ni0.1Co0.1Mn0.8O2 (pristine) without phase transition during the cycling process as a cathode material for KIBs. The pristine material is further doped with Mg2+ and Al3+ (K0.45Ni0.1Co0.1Mg/Al0.05Mn0.75O2) into Mn site to pursue better electrochemical performances. A detailed insight into the structural stability, charge compensation mechanism, and K+ kinetics study is clearly provided. The Mg/Al-doped electrodes exhibit outstanding cycling performance and rate capability because of the enhanced layered structure stability, enlarged K+ diffusion layer and optimized Jahn-Taller distortion of Mn3+. Furthermore, the Mg-doped electrode shows better effect in the suppression of Jahn-Taller distortion of Mn3+ by comparison with that of Al-doped electrode, but at the expanse of lower capacity as the decreased content of active redox of Mn3+/Mn4+.This research provides new insight into the future design of advanced cathode materials for KIBs.