High-Performance Polymer Electrolytes for Lithium Metal Batteries : Current Trends and Applications

초록

Traditional liquid electrolytes in lithium-ion batteries face critical limitations due to flammability and lithium dendrite growth. Consequently, flexible and highly processable polymer electrolytes have gained significant attention as a safer alternative. This review explores four key research trends aimed at overcoming the poor high-voltage oxidation stability and weak mechanical strength of current polymer electrolytes. First, introducing fluorine functional groups into monomers enhances high-voltage stability and suppresses dendrites by forming a robust lithium fluoride (LiF)-based solid electrolyte interphase (SEI). Second, inducing phase separation between polymer and ion-conducting phases creates elastic polymer electrolytes that secure both high ionic conductivity and mechanical elasticity, effectively mitigating lithium volume changes during cycling. Third, incorporating phosphate- and bromine-based monomers develops non-flammable polymer electrolytes that suppress fires through radical scavenging and char formation. Finally, in-situ ring-opening polymerization (ROP) using lithium salts as initiators maximizes interfacial compatibility and prevents long-term electrolyte depletion without requiring complex manufacturing steps. In the future, research on polymer-based solid electrolytes is expected to place increasing emphasis not only on materials design but also on validating their applicability under practical battery operating conditions. To this end, integrated optimization strategies involving functional monomers, lithium salts, additives, and crosslinked structures will be required. Such approaches are expected to contribute to accelerating the practical implementation of lithium metal batteries with high safety and energy density.

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