Stabilizing Ni‐rich Single‐crystalline LiNi0.83Co0.07Mn0.10O2 Cathodes using Ce/Gd Co‐doped High‐entropy Composite Surfaces

Abstract

AbstractNi‐rich layered oxides are promising lithium‐ion batteries (LIBs) cathode materials for their high reversible capacity, but they suffer from fast structural degradation during cycling. Here, we report the Ce/Gd incorporated single‐crystalline LiNi0.83Co0.07Mn0.10O2 (SC‐NCM) cathode materials with significantly enhanced cycling stability. The Gd ions are adequately incorporated in SC‐NCM while Ce ions are prone to aggregate in the outer surface, resulting in the formation of a high‐entropy zone in the near‐surface of SC‐NCM, including a Gd doped LiCeO2 (LCGO) shell and Ce/Gd dopant‐concentrated layer. The high‐entropy zone can effectively inhibit the oxygen evolution and prevent the formation of oxygen vacancies. Meanwhile, it leads to a greatly improved H2‐H3 phase transformation reversibility and mitigated stress/strain caused by Li‐ion extraction/insertion during (de)lithiation process. The synergetic effects of reduced oxygen vacancies concentration and mitigated stress/strain can effectively prevent the in‐plane migration of TM ions, lattice planar gliding as well as the formation of intragranular nanocracks. Consequently, Ce/Gd incorporated SC‐NCM (SC‐NCM@CG2) delivers a high initial discharge specific capacity of 219.7 mAh g−1 at 0.1 C and an excellent cycling stability with a capacity retention of 90.2 % after 100 cycles at 1.0 C.