Regulated Li⁺/H⁺ Co-Insertion of Upcycled LiMn₂O₄ Cathode with Li/Mn Disorder for High-Voltage Aqueous Zn-Based Batteries

Spent lithium manganate batteries are facing severe resource waste and low recovery rate due to the lack of efficient overall recycling methods rather than mere lithium recovery. Notably, upcycled LiMn₂O₄ (U-LMO) is rarely studied as cathodes for aqueous Zn-based batteries, let alone the exploration of the reaction mechanism during battery working. In this study, a novel Li/Mn synergistic repair approach is proposed to convert severely aged LiMn₂O₄ into U-LMO for high-performance aqueous Zn-based batteries using Zn metal anodes. Based on the experimental and theoretical results, the Li/Mn-disordered crystal structure endows the U-LMO with improved electron transfer kinetics and enhanced Li⁺/H⁺ co-storage capacity. Furthermore, the enhanced Li⁺ adsorption and regulated H⁺ deintercalation behavior collectively indicate the increased thermodynamic stability for the meliorative structural integrity. As a result, the Zn//U-LMO battery exhibits the ultrahigh capacity of 157.6 mAh g⁻¹ (over its theoretical 148 mAh g⁻¹), superior rate performance, and good cycling stability, far exceeding that of commercial and spent LiMn₂O₄ cathodes. This research offers insights into the development of high-value recycling of spent lithium manganate batteries for advanced Zn-based batteries based on Li⁺/H⁺ co-insertion chemistry.