Reviving Spent NCM Cathodes via Spontaneous Galvanic Corrosion in Ambient Atmospheric Condition

Abstract The recycling of end‐of‐life Li‐ion batteries (EoL LIBs) is critical for maintaining the sustainable LIB industry. In this study, the compositional restoration method for degraded Li _Δ Ni _0.6 Co _0.2 Mn _0.2 O ₂ cathode via spontaneous galvanic corrosion, which can be conducted at room temperature, is demonstrated. Achieving the lithiation of spent Li _Δ Ni _0.6 Co _0.2 Mn _0.2 O ₂ to its pristine state at room temperature requires a strong reducing agent with a redox potential lower than 1.6 V (vs Li/Li ⁺ ), which is very reactive and expensive. In the designed restoration system, spontaneous restoration can be achieved by using an Aluminum (Al) current collector as a reducing agent which has sufficient reducing power (Al/Al ³⁺ , 1.37 V (vs Li/Li ⁺ )). Moreover, through a galvanic reaction design that utilizes Li‐ion in the electrolyte of spent LIBs, the additional Li source required to replenish the Li‐deficient NCM is minimized. The galvanic corrosion‐based restoration mechanism is systematically analyzed, and a spent Li _0.76 Ni _0.6 Co _0.2 Mn _0.2 O ₂ is successfully restored to its pristine state (Li _1.05 Ni _0.6 Co _0.2 Mn _0.2 O ₂ ). Furthermore, restoration strategies accomplishable in not only the cathode state but also the battery state are presented to ensure applicability in practical recycling processes. The proposed strategy suggests a new insight into the direct cathode recycling technology, possessing economic feasibility, and environmental friendliness.