Solid‐State Li Batteries via Masked‐SLA 3D Printing

Solid‐state and quasi‐solid‐state lithium metal batteries are widely regarded as a promising solution to overcome the energy density and safety limitations of conventional lithium‐ion technology. However, their practical implementation is critically hindered by the lack of scalable manufacturing strategies capable of producing thin, uniform, and lithium‐compatible solid (or gel polymer) electrolyte layers with excellent interfacial contact. Here, a paradigm shift is demonstrated by using stereolithography (SLA) 3D printing to directly print a ready‐to‐use gel polymer electrolyte without any post‐processing. The proposed approach enables the fabrication of dense, nonporous electrolyte layers with precisely controlled thickness and conformal deposition onto substrates such as lithium metal and LiFePO 4 cathodes. Unlike previously reported SLA‐based strategies limited to ceramic precursors or sacrificial templates, the printed electrolyte is immediately functional and compatible with battery assembly. This area‐parallel, solvent‐free manufacturing route offers intrinsic scalability and eliminates material waste associated with conventional processing methods. Beyond the specific demonstrations reported here, the printing procedure provides a versatile platform adaptable to other polymer electrolytes and polymer–inorganic composites, opening new opportunities for additive manufacturing of advanced energy storage devices.