Turn "Waste" into Wealth: A Facile Reviving Strategy for Degraded Ni-Rich LiNi0.8Co0.1Mn0.1O2 Cathodes

Ni-rich layered cathodes have been regarded as one of the high-priority materials, but their commercial application was limited by the highly active surfaces, poor thermal stability, and irreversible phase transition. Furthermore, when they are stored in moist air, the particles can easily form an impurity layer of Li2CO3/LiOH. This inert substance hinders the transmission of lithium ions and electrons, leading to electrochemical performance deterioration. Herein, we report a simple method, namely, metaphosphate repair, which can successfully restore the degraded LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode materials and form an in situ multifunctional hybrid repaired layer of Li3PO4-YPO4-Y(PO3)(3) on the secondary particle. The repaired NCM811 delivers a discharge capacity of 171.7 mAh g(-1) after 100 cycles, which is much higher than those of pristine (147.6 mAh g(-1)) and stored degraded (116.2 mAh g(-1)) samples. Moreover, the restored sample could deliver a capacity retention of 92.3% after 100 cycles at 1C along with a better initial Coulombic efficiency (CE) of 88.4%. This study provides a facile strategy to revive degraded Ni-rich cathode materials and other similar layered oxide cathodes for advanced batteries.