A Surface‐Bulk Integrated Strategy of Ti Doping and LaTiO 3 Coating Achieves Highly Reversible Anionic Redox and Fast‐Charging Cyclability in Cobalt‐Free Lithium‐Rich Layered Oxides

Abstract Cobalt‐free lithium‐rich oxides (LROs) are promising cathode candidates for high‐energy‐density lithium‐ion batteries due to their high specific capacity and cost‐effectiveness, however, still limited by their structural instability and irreversible oxygen‐anionic redox reactions (OARR). Herein, a surface‐bulk integrated strategy is reported, using trace Ti doping into the bulk and perovskite LaTiO 3 coating on the surface of cobalt‐free LRO (LP‐LRO), to exceptionally strengthen the reversibility of OARR. Profited from the electron‐localization effect of Ti doping and the physical‐barrier effect of LaTiO 3 coating, the LP‐LRO achieves an upgraded discharge capacity of 271 mAh g −1 over bare LRO (B‐LRO, 243 mAh g −1 ) at 0.1 C, along with excellent cyclability, maintaining 80% capacity after ultra‐long 700 cycles at 5 C, superior to B‐LRO (60%) and most reported cobalt‐free LROs. The pouch cell of Si/C||LP‐LRO with a capacity of 800 mAh also displays excellent cyclability and energy retention rate, demonstrative of applicability. Using in ‐ situ and ex ‐ situ characterizations, it is disclosed that the boosted reversibility of OARR and enhanced stability of surface‐interface structure are established in LP‐LRO, guiding the formation of robust and conductive cathode electrolyte interphases, resulting in greatly improved Li + storage performance. This work presents an avenue toward high‐energy‐density cobalt‐free LROs for fast‐charging long‐life batteries.