Dual-anion synergy in solvation structure manipulation for high-voltage gel polymer electrolyte

High Li + conductivity and excellent interfacial contact properties have made gel polymer electrolytes (GPEs) a promising candidate for high-voltage lithium metal batteries. However, their further development has been hindered by instability at the electrolyte/electrode interface. In this study, we propose a strategy to optimize the solvation structure of GPEs through competitive coordination and anion synergy, thereby stabilizing the electrolyte-electrode interface. By introducing nitrate ion (NO₃ − ), which exhibits strong binding with Li + , the interaction between Li + and solvent molecules is weakened, resulting in an anion-rich solvation structure co-driven by NO₃ − and bis(trifluoromethanesulfonyl)imide (TFSI − ). This dual-anion-driven solvation structure not only enhances the Li + transport kinetics within the GPE but also facilitates the formation of robust solid electrolyte interphase/cathode electrolyte interphase (SEI/CEI) layers with superior ionic conductivity and mechanical stability. On the one hand, the optimized GPE demonstrates superior rate property when paired with a LiFePO₄ (LFP) cathode. The assembled full cell maintains stable cycling for over 300 cycles at rates of 0.2C, 0.5C, 1.0C, and even 2.0C. On the other hand, when the GPE paired with an NCM811 cathode, the assembled full cell achieves a capacity retention rate of 75.91% after 200 stable cycles at a rate of 1.0C, exhibiting the exceptional high-voltage tolerance. This work proposes a novel strategy through solvation structure manipulation for the design of next-generation high-voltage gel electrolytes.