Tailoring the Composite Polymer Electrolytes with Metal-Organic Framework for High-Performance Li-O₂ Batteries

Lithium-oxygen (Li-O₂) batteries with high energy density have given rise to tremendous advances in developing highly efficient energy storage devices. However, the barrier of Li dendrite growth and the liquid electrolyte volatilization under semi-open architectures still restrict their future applications. Poly(vinylidene fluoride) (PVDF)-based polymer electrolytes are considered to be an effective solution to these issues, but the presence of highly reactive residual solvents severely disrupts the long-term cycling stability of the battery. Herein, a tailoring strategy to confine and redistribute the solvent molecules by introducing porous metal-organic framework (MOF) is proposed. The Lewis acid sites and functional groups on MOFs offer more binding sites for residual solvents, leading to more involved anions in Li⁺ solvation. Benefiting from the tailored coordination environment of polymer electrolytes, the Li dendrite growth and liquid electrolyte volatilization are effectively suppressed in the composite polymer electrolyte (MOF@PVDF). As a result, the MOF@PVDF enables the Li//Li symmetrical cells ultra-stable cycling over 800 h at  0.2 mA cm^-2. Meanwhile, the MOF@PVDF-based Li-O₂ battery has realized a long life above 1100 h at 200 mA g^-1. This work opens a direction in developing stable polymer electrolytes for high energy density Li-O₂ batteries by tailoring the solvation structures of polymer electrolytes.