Correlating Electrode-Electrolyte Interface and Battery Performance in Hybrid Solid Polymer Electrolyte–Based Lithium Metal Batteries*

Solid polymer electrolytes (SPEs) are desirable in lithium metal batteries (LMBs) since they are nonflammable and show excellent lithium dendrite growth resistance. However, fabricating high performance polymer LMBs is still a grand challenge because of the complex battery system. In this work, a series of tailor-designed hybrid SPEs were used to prepare LMBs with a LiFePO4–based cathode. High performance LMBs with both excellent rate capability and long cycle life were obtained. The well–controlled network structure in this series of hybrid SPEs offers a model system to study the relationship between the SPE properties and the LMB performance. We show that the cycle life of the polymer LMBs is closely correlated with the SPE-Li interface ionic conductivity, underscoring the importance of the solid electrolyte interface in LMB operation. LMB performance was further correlated with the molecular network structure. We anticipate that results from this study will shed light on designing SPEs for high performance LMB applications.