Improved Cycling Stability of Single-Crystalline Ni-Rich Cathode at High Temperature Via Dual Substitution

Abstract

Despite high specific capacity, Ni-rich cathode materials still face poor cycling stability resulting from structural degradation during cycles, especially at high temperatures. Herein, single-crystalline LiNi0.83Co0.12Mn0.05O2 (NCM) is synthesized using a dual-substitution strategy, where sodium (Na) and tungsten (W) elements are co-doped to effectively inhibit Li+/Ni2+ mixing, delay H2-H3 phase transition, limit the generation of microcracks and enhance the high-temperature performance of single-crystalline Na/W-doped NCM (NWNCM). Notably, when cycled between 2.95 and 4.3 V (vs. Li/Li+) at a high temperature of 55 ºC, the NWNCM exhibits improved capacity retention of 81% at 55 ºC at 1 C, outstanding rate capacity of 182.8 mAh g-1 at 4 C (about of 92.3% the capacity at 1 C) and enhanced thermal stability. More impressively, the pouch-type full cell paired with the as-prepared NWNCM also delivers a high capacity retention of 87% after 1000 charge/discharge cycles at 1 C in the voltage range of 2.8 to 4.25 V at 55 ºC. The synergetic effects of this dual-substitution strategy pave a new pathway for addressing the critical challenges of Ni-rich cathode at high temperatures, which will significantly advance the high-energy-density cathodes to the subsequent commercialization.

Keywords: Ni-rich cathode, Single-crystalline NCM, Dual-substitution strategy, High-temperature cathode, Li-ion batteries