In situ co-doping strategy for achieving long-term cycle stability of single-crystal Ni-rich cathodes at high voltage

Abstract

Single-crystal Ni-rich layered cathode (SC-NCM) is economically appealing for high-energy–density lithium-ion battery but its life span in practical application, especially under high-voltage operation, is significantly hindered by its poor structural instability, irreversible phase transitions, and sluggish electrochemical reaction kinetic. Herein, in-situ zirconium and titanium co-doped single-crystal LiNi0.6Co0.1Mn0.3O2 (Z/T@SC-NCM) material is rationally designed as the structurally and electrochemically stable cathodes for high-energy density batteries. Both the experimental analyses and theoretical calculations reveal that the synergistic effect of Zr/Ti co-doping at transition metal (TM) sites of SC-NCM materials. can not only effectively enhance the Li+ diffusion mobility but also release the internal stress concentration as well as reducing the cationic disordering. As a result, the material-level specific energy of 715 Wh kg−1 is achieved for the single-crystal LiNi0.598Co0.08Mn0.3Zr0.002Ti0.002O2 (Z/T@SC-NCM-0.2) cathode at 2.75–4.6 V with a satisfying capacity retention of 88.5 % after 150 cycles. Impressively, the pouch-type full cell of Zr/Ti@SC-NCM||graphite with a practical area capacity of 4.96 mAh cm−2 delivers an superior capacity retention of 80.6 % after 4000 cycles, which could be expected to extend the battery life-span to more than a decade for electric vehicles. It suggests that engineering the dual-doping in SC-NCM cathodes may provide an effective path toward the low-cost, excellent long-term cycling stability, and high energy density of lithium-ion batteries.