Composite Block Copolymer Electrolytes for Lithium Metal Batteries

Lithium metal has been widely investigated for next generation rechargeable batteries due to its extremely high theoretical specfic capacity. However, lithium dendrite formation at the lithium metal anode-electrolyte interfaces is considered to be one of major factors in deteriorating the performance of lithium metal batteries. To suppress the lithium dendrite growth, solid polymer electrolytes (SPE) with high mechanical strength and electrochemical stability have been studied to replace liquid electrolyte. In this case, using SPE in lithium metal batteries, low ionic conductivity and high interfacial resistance of SPEs are still remained critical problems. In order to achieve the high ionic conductivity and mechanical strength simultaneously in solid polymer electrolytes for lithium metal batteries, we applied block copolymer (BCP) composed of structural and ionic conducting domains in this study. In addition, we fabricated organic/inorganic hybrid block copolymer composite electrolytes with ionic liquids and nanoparticles for improving ionic conductivity and mechanical strength. The effects of composite block copolymer electrolytes were evaluated in terms of ionic conductivity as well as mechanical strength. In addition, interfacial resistance and ESW (electrochemical stability window) were also performed to understand the functions of hybrid components. In particular, these properties could be crucially affected by change of composition of block copolymer and hybrid components, which resulted in the different behavior inside polymer matrix and interface between electrode/electrolyte.