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 (LNMOd@CC) by an electrodeposition combined with low‐temperature calcination route using spent lithium manganate as a raw material. The obtained LNMOd@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 LNMOd@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. Fabrication of manganese oxides with cationic predoped and oxygen defects to facilitate the zinc storage in wide‐temperature workable. The high reversible capacity of 152 mAh g−1 was achieved even after 9000 cycles at a high current density of 5 A g−1, which is comparable to other cathodes of zinc‐ion batteries. The Zn//LNMOd@CC batteries with attractive cycling performance are stable for more than 850 cycles at a low temperature of 0°C.