Suppressed Lattice Oxygen Release via Ni/Mn Doping from Spent LiNiMnCoO toward High-Energy Layered-Oxide Cathodes.

LiCoO has suffered from poor stability under high voltage as a result of insufficient Co-O bonding that causes lattice oxygen release and lattice distortions. Herein, we fabricated a high-voltage LiCoO at 4.6 V by doping with Ni/Mn atoms, which are obtained from spent LiNiMnCoO cathode materials. The as-prepared high-voltage LiCoO with Ni/Mn substitutional dopants in the Co layer enhances Co-O bonding that suppresses oxygen release and harmful phase transformation during delithiation, thus stabilizing the layered structure and leading to a superior electrochemical performance at 4.6 V. The pouch cell of modified LiCoO exhibits a capacity retention of 85.1% over 100 cycles at 4.5 V (vs graphite). We found that our strategy is applicable for degraded LiCoO, and the regenerated LiCoO using this strategy exhibits excellent capacity retention (84.1%, 100 cycles) at 4.6 V. Our strategy paves the way for the direct conversion of spent batteries into high-energy-density batteries.