High‐voltage LiCoO 2 cathodes for high‐energy‐density lithium‐ion battery

Abstract As the earliest commercial cathode material for lithium‐ion batteries, lithium cobalt oxide (LiCoO 2 ) shows various advantages, including high theoretical capacity, excellent rate capability, compressed electrode density, etc. Until now, it still plays an important role in the lithium‐ion battery market. Due to these advantages, further increasing the charging cutoff voltage of LiCoO 2 to guarantee higher energy density is an irresistible development trend of LiCoO 2 cathode materials in the future. However, using high charging cutoff voltage may induce a lot of negative effects, especially the rapid decay of cycle capacity. These are mainly caused by rapid destruction of crystal structure and aggravation of interface side reaction at high voltage during the cycle. Therefore, how to maintain a stable crystal structure of LiCoO 2 to ensure the excellent long cycle performance at high voltage is a hot research issue in the further application of LiCoO 2 . In this review, we summarized the failure causes and extensive solutions of LiCoO 2 at high voltage and promoted some new modification strategies. Moreover, the development trend of solving the failure problem of high‐voltage LiCoO 2 in the future such as defect engineering and high‐temperature shock technique is also discussed.