A new Mg-ion intercalation host of LiNi0.5Co0.2Mn0.3O2 as cathode materials for rechargeable Mg batteries

Abstract

Mg rechargeable battery is one of the most promising next-generation batteries on the merits of its high theoretical capacity, low cost and safety. However, searching new cathode materials with high energy density has been a great challenge so far due to the sluggish diffusion kinetics of divalent Mg2+ ions in the crystal structure of electrode materials. In this study, we utilize LiNi0.5Co0.2Mn0.3O2 (NCM523), which is widely used electrode material for Li-ion batteries (LIBs), as a cathode material for Mg rechargeable battery. We first discover that NCM523 can be a Mg intercalation host with high energy density along with the water-induced phase transformation from O3 to P3 layered structure. The water-intercalated P3 phase delivers the highest Ni2+/Ni3+/Ni4+ redox potential of 3.1 V vs. Mg/Mg2+ yet reported for Mg cathode materials, with high energy density of 589 Wh kg-1. This unusual behavior in NCM layered oxide, proposed in this work, provides an insight into designing promising cathode materials for Mg rechargeable battery.