A Novel Perovskite Electron-Ion Conductive Coating to Simultaneously Enhance Cycling Stability and Rate Capability of Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 Cathode Material for Lithium-Ion Batteries

Poor cycling stability and rate capability are two key issues needing to be solved for Li- and Mn-rich oxide cathode material for lithium-ion batteries (LIBs). Herein, a novel perovskite electron-ion mixed conductor Nd Sr CoO (NSCO) is used as the coating layer on Li Ni Co Mn O (LNCMO) to simultaneously enhance its cycling stability and rate capability. By coating 3 wt% NSCO, LNCMO-3NSCO exhibits an optimal cycling performance with a capacity retention of 99% at 0.1C (1C = 200 mA g ) after 60 cycles, 91% at 1C after 300 cycles, and 54% at 20C after 1000 cycles, much better than 78%, 63%, and 3% of LNCMO, respectively. Even at a high charge and discharge rate of 50C, LNCMO-3NSCO exhibits a discharge capacity of 53 mAh g and a mid-point discharge voltage of 2.88 V, much higher than those of LNCMO (24 mA h g and 2.40 V, respectively). Benefiting from the high electronic conductivity (1.46 S cm ) and ionic conductivity (1.48 × 10 S cm ), NSCO coating not only suppresses transition metals dissolution and structure transformation, but also significantly enhances electronic conductivity and Li diffusion coefficient of LNCMO by an order of magnitude.