Understanding and Controlling Anionic Electrochemical Activity in High-Capacity Oxides for Next Generation Li-Ion Batteries

Rechargeable Li-ion batteries with higher energy density are in urgent demand to address the global challenge of energy storage. In comparison with anode materials, the relatively low capacity of cathode oxides, which exhibit classical cationic redox activity, has become one of the major bottlenecks to reach higher energy density. Recently, anionic activity, such as oxygen redox reaction, has been discovered in the electrochemical processes, providing extra reversible capacity for certain transition-metal oxides. Consequently, a more complete understanding and precise controlling on anionic electrochemical activity in these highcapacity oxides have become a flourishing, yet challenging subject. This perspective highlights (1) key features of the anionic electrochemical activities; (2) computational and experimental tools to characterize and quantify the anionic activity; and (3) design principles that correlate the chemical and structural compositions with high reversible capacity to accelerate the discovery of novel cathode oxides for next generation Li-ion batteries.