Sustainable Upcycling of Spent Lithium-Ion Batteries Cathode Materials: Stabilization by In Situ Li/Mn Disorder

The non-destructive repair of spent lithium-ion batteries cathode materials has been the holy grail in the field of waste-to-resource research due to the potential for optimal environmental and economic benefits. Here, Mn deficiency and cationic disorder in degraded materials are discovered for the first time and the degraded crystal structure is repaired by the in situ upcycling process using a low-carbon and economical technique. The repaired disordered LiMn₂O₄ (LMO) material can contribute higher capacity and greater stability than ordered LMO materials. This unexpected behavior is attributed to the in-situ upcycling process that enhances the Li/Mn atomic disorder, thereby altering the electrochemical activity as well as the structural stability of the cathode material. Specifically, the Li/Mn disorder can effectively suppress the Jahn–Teller distortion and two-phase phase transition and activate the activity of disordered Li, contributing to a stable high discharge capacity of upcycled material. The discovery of the Mn-deficiency mechanism solves many doubts as to the conventional repair technology and can provide a more adequate theoretical guidance of the development of recycling technology together with the Li-deficiency mechanism. The atomic disorder structure also provides guidance for the design of battery materials and promotes the sustainable development of future green lithium-ion batteries.