Investigation of mechanisms for forming uniform gel-polymer electrolyte layers for electrochemical devices

Abstract This study investigates the deposition mechanisms of lignin-based gel polymer electrolyte (GPE) solution using dimethyl sulfoxide (DMSO) as the main solvent, with glycerol (10 vol%) introduced as a co-solvent to suppress CRE. The evaporation dynamics of sessile droplets were systematically analyzed at temperatures ranging from 30 to 90 °C, revealing that the addition of glycerol reduced the volatility of the solvent and stabilized the contact line, mitigating the non-uniform deposition. The internal flow dynamics, including Marangoni flows and capillary flows, were modeled to elucidate their roles in deposition. The results indicate that glycerol enhances the dominance of Marangoni flow, counteracting the radial capillary flow and reducing the accumulation of material at the droplet edges. The coffee ring index (CRI) increased from 0.27 (pure DMSO) to 0.51 (DMSO-glycerol) at 90 °C, with optimal homogeneity already achieved at 70 °C. This study extends the fundamental understanding of GPE deposition processes and offers practical solutions for optimizing the performance and reliability of devices based on them.