Solid and Solid‐Like Composite Electrolyte for Lithium Ion Batteries: Engineering the Ion Conductivity at Interfaces

Abstract The development of solid composite electrolytes or solid composite electrolytes (SCEs) consisting of an ionic conductor and a dielectric matrix offers an elegant strategy to enhance the ionic conductivity of electrolytes by engineering the interface conduction. At the conductor/matrix interface, the ionic conductivity can be enhanced by the enriched charge carrier concentration and/or the changed molecular structure of the ionic conductor. This review deals with the interfacial ion conduction mechanisms of the inorganic particle‐based SCE, polymer‐SCE, and ionic liquid electrolyte‐based SCE (ILE‐SCE). In the first part of this review, an overview is given of the space‐charge theory developed to describe the increased vacancy concentration at the interface of inorganic particle‐based SCE. In the second part, the proposed interface interactions and structural changes associated with interface conduction for the polymer‐SCE and ILE‐SCE are reviewed. For the ILE‐SCE, the preparation methods and interface characterization are discussed together with the proposed conductivity models. The use of mesoporous matrix materials with high internal surface area for ILE‐SCE is reviewed here for the first time.