Materials for advanced Li-O2 batteries: Explorations, challenges and prospects

Rechargeable Li-O-2 batteries have been extensively investigated as one of most promising alternative for next-generation rechargeable batteries. In this review, notable progress of Li-O-2 batteries is discussed. The development process from carbon cathode, which was initially used in Li-O-2 batteries, to carbon-free catalysts, which are employed to avoid side reactions between carbon-based cathode and Li2O2, soluble catalysts, and dual-redox mediators, is discussed. The challenges encountered in different stages are evaluated, and innovative directions for further studies of Li-O-2 batteries are also discussed.