In-situ upcycling of severely deteriorated Li_xCoO₂ cathodes into high-voltage-tolerant counterparts

The increasing waste from lithium-ion batteries (LIBs) and the reliance on critical metals like lithium and cobalt necessitate efficient and sustainable recycling strategies. Conventional metallurgical recycling methods degrade cathode structures, while direct recycling preserves materials but falls short of meeting the critical requirements for next-generation high-voltage cathodes. Here, we present an upcycling strategy that transforms spent LiCoO₂ (S-LCO) into a high-voltage-tolerant cathode through a solid-state relithiation coupled with an in-situ ZrO₂ coating process. This approach reintegrates lithium while forming a protective surface layer, mitigating severe structural degradation and suppressing side reactions at high voltages. At an elevated cut-off voltage of 4.6 V, upcycled ZrO₂-modified LCO (U-LCO) exhibits superior cycle stability compared to commercial LCO cathodes. Techno-economic analysis highlights the advantage of this upcycling approach over conventional pyrometallurgical and hydrometallurgical recycling processes, offering simplified processing and improving enhanced recovery efficiency. This work provides a viable pathway for upcycling spent LIB cathodes, contributing to sustainable battery management and resource conservation.