High‐Performance, Roll‐to‐Roll Fabricated Scaffold‐Supported Solid Electrolyte Separator for Practical All‐Solid‐State Batteries

Abstract All‐solid‐state batteries (ASBs) are promising candidates for next‐generation energy storage systems due to their enhanced safety and potential for higher energy densities. However, achieving practical ASBs with energy densities surpassing those of state‐of‐the‐art lithium‐ion batteries (LIBs) requires the development of thin, mechanically robust solid electrolyte separators (SESs). In this study, a scalable tape casting method is employed to fabricate a thin SES with a thickness of 27 µm and a high ionic conductance of 146 mS cm −2 . The SES, composed of Li 6 PS 5 Cl SE and a laser‐drilled porous polyimide (PI) scaffold with a high porosity of 69%, exhibits a tensile stress of 7.15 MPa at 6% strain, demonstrating the mechanical integrity necessary for commercial roll‐to‐roll fabrication. Due to its reduced thickness, the LiNi 0.83 Co 0.11 Mn 0.06 O 2 ||Li‐In pouch cell achieves outstanding estimated cell‐level gravimetric and volumetric energy densities of 322 Wh kg −1 and 571 Wh L −1 , respectively, demonstrating its practical viability. Additionally, simulation studies highlight the importance of optimizing the porosity and pore distribution of porous scaffolds to minimize Li‐ion flux heterogeneity and prevent non‐uniform Li plating in scaffold‐supported SESs. Finally, a 4 m long, double‐side coated SES is successfully manufactured using an industrial‐level comma coater, demonstrating the feasibility of the approach for large‐scale SES production and the forthcoming commercialization of ASBs.