Regeneration of spent lithium manganate into cation-doped and oxygen-deficient MnO2 cathodes toward ultralong lifespan and wide-temperature-tolerant aqueous Zn-ion batteries

Manganese-based compounds have been regarded as the most promising cathode materials for rechargeable aqueous zinc-ion batteries (AZIBs) due to their high theoretical capacity. Unfortunately, aqueous Zn–manganese dioxide (MnO₂) batteries have poor cycling stability and are unstable across a wide temperature range, severely limiting their commercial application. Cationic preinsertion and defect engineering might increase active sites and electron delocalization, which render the high mobility of the MnO₂ cathode when operated across a wide temperature range. In the present work, for the first time, we successfully introduced lithium ions and ammonium ions into manganese dioxide (LNMO_d@CC) by an electrodeposition combined with low-temperature calcination route using spent lithium manganate as a raw material. The obtained LNMO_d@CC exhibits a high reversible capacity (300 mAh g⁻¹ at 1 A g⁻¹) and an outstanding long lifespan of over 9000 cycles at 5.0 A g⁻¹ with a capacity of 152 mAh g⁻¹, which is significant for both the high-value recycling of spent lithium manganate batteries and high-performance modification for MnO₂ cathodes. Besides, the LNMO_d@CC demonstrates excellent electrochemical performance across wide temperature ranges (0–50°C). This strategy simultaneously alleviates the shortage of raw materials and fabricates electrodes for new battery systems. This work provides a new strategy for recovering cathode materials of spent lithium-ion batteries and designing aqueous multivalent ion batteries.