A High‐Capacity O2‐Type Li‐Rich Cathode Material with a Single‐Layer Li2MnO3 Superstructure

A high capacity cathode is the key to the realization of high-energy-density lithium-ion batteries. The anionic oxygen redox induced by activation of the Li2MnO3 domain has previously afforded an O3-type layered Li-rich material used as the cathode for lithium-ion batteries with a notably high capacity of 250–300 mAh g−1. However, its practical application in lithium-ion batteries has been limited due to electrodes made from this material suffering severe voltage fading and capacity decay during cycling. Here, it is shown that an O2-type Li-rich material with a single-layer Li2MnO3 superstructure can deliver an extraordinary reversible capacity of 400 mAh g−1 (energy density: ≈1360 Wh kg−1). The activation of a single-layer Li2MnO3 enables stable anionic oxygen redox reactions and leads to a highly reversible charge–discharge cycle. Understanding the high performance will further the development of high-capacity cathode materials that utilize anionic oxygen redox processes.