An Air-Stable High-Nickel Cathode with Reinforced Electrochemical Performance Enabled by Convertible Amorphous Li₂ CO₃ Modification.

Abstract

High-nickel (Ni ≥ 90%) cathodes with high specific capacity hold great potential for next-generation lithium-ion batteries (LIBs). However, their practical application is restricted by the high interfacial reactivity under continuous air erosion and electrolyte assault. Herein, a stable high-nickel cathode is rationally designed via in situ induction of a dense amorphous Li₂ CO₃ on the particle surface by a preemptive atmosphere control. Among the residual lithium compounds, Li₂ CO₃ is the most thermodynamically stable one, so a dense Li₂ CO₃ coating layer can serve as a physical protection layer to isolate the cathode from contact with moist air. Furthermore, amorphous Li₂ CO₃ can be transformed into a robust F-rich cathode electrolyte interphase (CEI) during cycling, which reinforces the cathode's interfacial stability and improves the electrochemical performance. The assembled coin cell with this modified cathode delivers a high discharge capacity of 232.4 mAh g^-1 with a superior initial Coulombic efficiency (CE) of 95.1%, and considerable capacity retention of 90.4% after 100 cycles. Furthermore, no slurry gelation occurs during the large-scale electrode fabrication process. This work opens a valuable perspective on the evolution of amorphous Li₂ CO₃ in LIBs and provides guidance on protecting unstable high-capacity cathodes for energy-storage devices.