Regulation of Interface Ion Transport by Electron Ionic Conductor Construction toward High‐Voltage and High‐Rate LiNi0.5Co0.2Mn0.3O2 Cathodes in Lithium Ion Battery

Abstract Simultaneously achieving high‐energy‐density and high‐power‐density is a crucial yet challenging objective in the pursuit of commercialized power batteries. In this study, atomic layer deposition (ALD) is employed combined with a coordinated thermal treatment strategy to construct a densely packed, electron‐ion dual conductor (EIC) protective coating on the surface of commercial LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) cathode material, further enhanced by gradient Al doping (Al@EIC‐NCM523). The ultra‐thin EIC effectively suppresses side reactions, thereby enhancing the stability of the cathode‐electrolyte interphase (CEI) at high‐voltages. The EIC's dual conduction capability provides a potent driving force for Li + transport at the interface, promoting the formation of rapid ion deintercalation pathways within the Al@EIC‐NCM523 bulk phase. Moreover, the strategic gradient doping of Al serves to anchor the atomic spacing of Ni and O within the structure of Al@EIC‐NCM523, curbing irreversible phase transitions at high‐voltages and preserving the integrity of its layered structure. Remarkably, Al@EIC‐NCM523 displays an unprecedented rate capability (114.7 mAh g −1 at 20 C), and a sustained cycling performance (capacity retention of 74.72% after 800 cycles at 10 C) at 4.6 V. These findings demonstrate that the proposed EIC and doping strategy holds a significant promise for developing high‐energy‐density and high‐power‐density lithium‐ion batteries (LIBs).