Heteroepitaxial Coating Coupled With Interfacial Electric Field Modulation for Drastically Stabilized Original/Repaired Single‐Crystal Ni‐Rich Cathodes

Single crystal Ni‐rich layered cathodes suffer severe capacity fading from interfacial instability and structural deterioration. Herein, a synergistic dual‐coating modification strategy is successfully designed and implemented for single crystal LiNi 0.6 Co 0.2 Mn 0.2 O 2 (SC‐NCM622). This strategy comprises an inner coating layer with a heteroepitaxial structure formed by the coherent growth of spinel Li 4 Ti 5 O 12 (LTO) and layered SC‐NCM622, coupled with an outermost coating layer of Li 4 Ti 5 O 12 /TiO 2 (LTO/TO) composite. The unique dual‐coating effectively suppresses lattice mismatch, oxygen release, structural degradation, and grain cracking, thereby improving Li + reaction kinetics. Concurrently, an interfacial electric field established between LTO and SC‐NCM622 could modulate the inner Helmholtz layer (IHL) through the directional adsorption of PF 6 − anions, thereby forming an inorganic‐rich cathode electrolyte interphase (CEI) film. This significantly enhances electrode/electrolyte interface stability and reduces heat generation during cycling. Benefiting from these, the modified sample exhibits exceptional cycling stability, outstanding rate performance, and superior thermal stability at 45°C. In addition, this novel modification strategy has been proven to be equally applicable to the repair and modification of retired SC‐NCM622 cathode materials. This study provides a straightforward and effective approach to address interfacial, kinetic, and thermal stability limitations of single‐crystal Ni‐rich cathodes.