In Situ Constructed Spinel Layer Stabilized Upcycled LiCoO2 for High Performance Lithium‐Ion Batteries

Abstract With ever‐increasing requirements for cathodes in the lithium‐ion batteries market, an efficiency and eco‐friendly upcycling regeneration strategy is imperative to meet the demand for high‐performance cathode materials. Herein, a facile, direct and upcycling regeneration strategy is proposed to restore the failed LiCoO 2 and enhance the stability at 4.6 V. Double effects combination of relithiation and outside surface reconstruction are simultaneously achieved via a facile solid‐phase sintering method. The evolution process of the Li‐supplement and grain‐recrystallization is systematically investigated, and the high performance of the upcycled materials at high voltage is comprehensively demonstrated. Thanks to the favorable spinel LiCo x Mn 2−x O 4 surface coating, the upcycled sample displays outstanding electrochemical performance, superior to the pristine cathode materials. Notably, the 1% surface‐coated LiCoO 2 achieves a high discharge‐specific capacity of 207.9 mA h g −1 at 0.1 C and delivers excellent cyclability with 77.0% capacity retention after 300 cycles. Significantly, this in situ created spinel coating layer can be potentially utilized for recycling spent LiCoO 2 , thus providing a viable, promising recycling strategy insights into the upcycling of degraded cathodes.