Challenges of thermal stability of high-energy layered oxide cathode materials for lithium-ion batteries: A review

With the growing market demand for higher energy density in power supplies, the further industrialization of high-energy cathode materials for lithium-ion batteries (LIBs) is imminent. Lithium-rich and nickel-rich oxides, as the most promising layered cathode materials with high energy potential, are capable of achieving higher capacity in a high state of charge (SOC), but are prone to safety problems due to poor thermal stability, which restricts the further marketable application of both. To enhance the thermal instability of these two high-energy cathode materials requires an in-depth comprehension of their associated failure mechanisms and improvement mechanisms. This review presents the current status of the development of high energy layered oxide cathode materials with thermal instability in existing laboratories. Firstly, several failure mechanisms of thermal instability of the two materials are clarified; secondly, the mechanisms of the three major modification on the materials, which are bulk doping, surface modification, morphological and structural design, are introduced respectively; finally, the significant challenges and prospects worth exploring for the commercialization of the two high-energy layered oxides are summarized to promote the development of safe high-energy LIBs.