Local charge homogenization strategy enables ultra-high voltage tolerance of polyether electrolytes for 4.7 V lithium metal batteries

In-situ fabricated polyether electrolytes have been regarded as one of the most promising solid electrolyte systems. Nevertheless, they cannot match high-voltage cathodes over 4.3 V due to their poor oxidative stability. Herein, we propose an effective local charge homogenization strategy based on the triglycidyl isocyanurate (TGIC) crosslinker, achieving ultra-high-voltage electrochemical stability of polyether electrolytes (viz. PTIDOL) at cutoff voltages up to 4.7 V. The introduction of TGIC optimizes the Li⁺ solvation environment, thereby homogenizing the charge distribution at ether oxygen (EO) sites, resulting in significantly enhanced oxidative stability of the polyether main chain. Consequently, the Li|PTIDOL|LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) cell achieves long-term operation at an ultra-high cutoff voltage with a capacity retention of 81.8% after 400 cycles, one of the best results reported for polyether electrolytes to date. This work provides significant insights for the development of polyether electrolytes with high-voltage tolerance and the advancement of high-energy-density batteries.