Solvent sieving separators implement dual electrolyte for high-voltage lithium-metal batteries

Lithium-metal batteries (LMBs) based on high-voltage cathodes would deliver high specific energy density to meet the demand of future energy storage. However, developing liquid electrolytes with wide electrochemical window for high-energy LMBs is intrinsically challenging. Herein, we demonstrate metal-organic framework-functionalized separators (PE@MOF) with solvent sieving capability that implement dual electrolyte for LMBs. The capability of PE@MOF separator to block the diffusion of liquid electrolytes has been investigated. The PE@MOF separator notably suppresses solvents shuttling, enabling the independent optimization of cathode–electrolyte and anode–electrolyte interfaces. By adapting commercial carbonate and ether electrolytes on cathode and anode sides, respectively, robust cathode–electrolyte interphase (CEI) and solid electrolyte interface (SEI) have been built on both electrodes. The lifespan of LiCoO₂ (LCO)|Li full cell has been notably extended when using dual electrolyte and the solvent-sieving PE@MOF separator. This work demonstrates a new strategy to separately optimize the local environments at electrodes and to develop high-energy LMBs using low-cost and commercially available electrolytes.