Abstract: Soybean protein isolates (SPI) were integrated with polyacrylamide (PAAm) to form an ionic liquid-containing gel polymer as a new quasi-solid-state electrolyte, which could be used in supercapacitor. And the electrochemical performance and compressibility of supercapacitor were studied. The synergistic effect of SPI and PAAm endowed the gel electrolyte with excellent compressive resilience and fatigue resistance. Particularly, the gel electrolyte could maintain structural integrity even under 80% strain for 100 compression cycles, the plastic deformation was less than 15% and the energy loss coefficient was more than 0.1. The symmetric quasi-solid-state supercapacitor based on this gel electrolyte exhibited satisfied electrochemical performance, delivering the maximum energy density of 25.99 W·h/kg and the maximal power density of 3 600 W/kg. And the device could withstand 80% compression strain without structural fracture or damage, showing excellent compressibility and capacitive stability.