Vat photopolymerization three-dimensional printing of PEGDA/LiClO 4 solid polymer electrolytes with optimised accuracy and electrochemical-mechanical performance

Research on 3D printing of battery materials has grown significantly, but developing an optimised printable electrolyte remains a major challenge for fully conformal Li-ion batteries, due to the need for the electrolyte to be ionically conductive, thin, mechanically strong, and printable in intricate shapes. This study leverages additive manufacturing to create a solid polymer electrolyte (SPE) using a custom UV-curable resin as feedstock for Digital Light Processing (DLP) 3D printing. The resin comprises poly(ethylene glycol) diacrylate (PEGDA) with varying molecular weights as the polymer matrix and LiClO4 as the lithium salt. To identify the optimal PEGDA molecular weight, electrochemical and mechanical properties are assessed using infrared analysis, tensile strength tests, linear sweep voltammetry, and electrochemical impedance spectroscopy. Results reveal a tradeoff between printability and electrochemical performance based on molecular weight. The DLP process enables 3D printing of both discs and complex SPE geometries, showcasing its potential for shape-conformable applications. In addition to offering high conformability and robust performance, these SPEs are expected to enhance the safety of Li-ion batteries by replacing traditional liquid electrolytes containing flammable solvents.