Fully printed solid-state lithium-ion battery with improved interface between cathode and solid polymer electrolyte

This describes the development of fully printed solid-state lithium-ion batteries via Direct Ink Writing (DIW), demonstrating the elementary role of the processing solvent in engineering/designing the interface between both solid polymer electrolyte (SPE) and the cathode of C-LiFePO 4 (LFP) components. The SPE was fabricated using a high-dielectric P(VDF-TrFE-CFE) matrix, natural clinoptilolite (CPT), the ionic liquid (PMPyrTFSI), and acetone solvent. By varying the cathode processing solvent among DMF, DMSO, and NMP, we demonstrate that the heterostructure's structural, morphological, and electrochemical characteristics can be systematically tuned. Cathodes processed with DMF exhibited the highest surface roughness (244 nm) and crystallinity (>85%), optimizing low-rate performance (120 mAh⋅g−1 at C/5). Conversely, DMSO yielded a lower surface roughness (160 nm), which increased interfacial contact and reduced overall cell resistance to 700 Ω. Meanwhile, NMP enabled high-rate capability and long-term cycling stability exceeding 200 cycles. These outcomes highlight that interfacial relationship between printed layers is as crucial to battery performance as individual material properties, offering a robust pathway regarding stability, adaptability, and sustainability of energy storage systems.