Solid-state batteries (SSBs) are emerging as a safer, higher-energy alternative to traditional lithium-ion batteries, driven by the demand for advanced energy storage solutions. Despite the potential of inorganic/polymer composite solid-state electrolytes (CSEs) to enhance SSB performance, the mechanisms of ion transport in these systems remain poorly understood. This study aims to elucidate these mechanisms by exploring the formation of bi-percolating ion channels and ion conduction at the interfaces between inorganic and polymer electrolytes in CSEs.We selected a model CSE composed of argyrodite-type Li6PS5Cl (LPSCl) and a gel polymer electrolyte (GPE) containing a Li+-glyme complex for ion conduction and a crosslinked ethoxylated trimethylolpropane triacrylate (ETPTA) polymer for structural support. Our findings reveal that the percolation threshold of the LPSCl phase within the CSE is significantly influenced by the elasticity of the GPE phase. Moreover, by modulating the solvation/desolvation dynamics of the Li+-glyme complex within the GPE, we achieved enhanced ion conduction across the LPSCl-GPE interface.The optimized CSE, incorporating a balance of material chemistry and composition, was integrated with an aramid nonwoven porous substrate to achieve scalability and flexibility in manufacturing. The resultant CSE, with dimensions of 8 × 6 (cm × cm) and a thickness of approximately 40 μm, was paired with a high-mass-loading LiNi0.7Co0.15Mn0.15O2 cathode and a graphite anode to construct an SSB full cell. This assembly, characterized by a bi-cell configuration and a negative (N)/positive (P) capacity ratio of 1.1, exhibited a remarkable volumetric energy density of 480 Wh Lcell -1 and stable cyclability at 25 °C.This study not only advances our understanding of ion transport phenomena in CSEs but also presents a pragmatic approach to the design and fabrication of SSBs with superior performance metrics. By integrating insights into ion channel formation and interfacial conduction with innovative materials engineering, we present a scalable and effective strategy for the development of high-performance SSBs. This research underscores the critical role of CSE design in overcoming the limitations associated with both inorganic and polymer electrolytes, paving the way for the next generation of energy storage technologies. Figure 1
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