||Sodium ion battery (SIB) has been highlighted for one of energy storage systems to replace lithium ion battery (LIB). However, safety and stability of such devices are problems to be solved, and glass fiber as conventional separator with large and irregular morphology for SIB has critical weak point about safety and cell stability. To solve these, many approaches have been researched, such as inorganic/organic separator, solid electrolyte, etc. Though, these results have difficulties to solve interfacial compatibility between electrolyte and electrode. In this study, we propose a strategy to control morphology of polymer phase for gel electrolyte via uniform pore inducing and appropriate positioning. Designed gel electrolyte enables improved interfacial stability between electrolyte and electrode with high thermal/mechanical stability and ionic conductivity, and it stabilizes cell characteristic with high current density and long cycles.