Strain Engineering of Ni‐Rich Cathode Enables Exceptional Cyclability in Pouch‐Type Full Cells

Abstract Ni‐rich layered oxides are at the forefront of the development of high‐energy Li‐ion batteries, yet the extensive applications are retarded by the deteriorative capacity and thermal instability. Herein, an in situ co‐precipitation strategy is implemented to achieve the novel super‐dispersed Nb‐doped Ni‐rich cathode that consists of the elongated and radially aligned primary particles with increased oxygen stable {001} planes. The unique microstructure homogenizes the intragranular and intergranular strain distribution and stabilizes the spherical secondary particles, effectively inhibiting microcrack formation and propagation and surface degradation. The super‐dispersed Nb doping prevents the Li/Ni disordering and lattice oxygen escape, thereby further strengthening the crystal structure and thermal stability. Accordingly, this cathode delivers a high reversible capacity of 229.0 mAh g −1 at 0.1 C with much better retention at 55 °C and 5 C after 100 cycles than the conventional Nb‐doped Ni‐rich cathodes. In a pouch‐type full cell, it exhibits exceptionally long life with a capacity retention of 91.9% at 1 C after 500 cycles and 80.5% at 5 C after 2000 cycles within 3.0–4.2 V, greatly prolonging the service period to cater to the lightweight and intelligence of electric vehicles.