In Situ Construction of Gradient Oxygen Release Buffer and Interface Cation Self‐Accelerator Stabilizing High‐Voltage Ni‐Rich Cathode

Abstract Ni‐rich cathodes with superior energy densities have spurred extensive attention for lithium‐ion batteries (LIBs), whereas their commercialization is hampered by structural degradation, thermal runaway, and dramatic capacity fading. Herein, boron (B) with high binding energy to oxygen (O) is gradiently incorporated into each primary particle and piezoelectric Li 2 B 4 O 7 (LBO) is homogeneously deposited on the secondary particles of polycrystalline LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) surface through a facile in situ construction strategy, intending to synchronously enhance electrochemical stabilities and Li + kinetics upon cycling. Particularly, the as‐obtained LBO modified NCM811 cathode exhibits an excellent capacity retention (88.9% after 300 cycles, 1 C) and rate performance (112.2 mAh g −1 , 10 C) with Li metal anode, the NCM811‐LBO/Li 4 Ti 5 O 12 full cell achieves a capacity retention of 92.6% after 1000 cycles (0.5 C). Intensive explorations in theoretical calculation, multi‐scale in/ex situ characterization and finite element analysis ascertain that the improvement mechanism of LBO modification can be attributed to the synergistic contributions of rational designed O release buffer and interface cation self‐accelerator. This study provides a facile and practical method to prevent structural degradation and thermal runaway for high‐energy LIBs.