A collagen-based electrolyte-locked separator enables capacitor to have high safety and ionic conductivity

Abstract

The conventional liquid electrolytes (LEs) have a high level of ionic conductivity; however, they often suffer from the poor processability and safety risks of potential leakage. Although solid-state electrolytes (SSEs) can solve these inherent problems of LEs, the ionic conductivity of most SSEs is several magnitudes lower than these of LEs. Herein, we report a novel strategy by building liquid ion-transport channels in a solid framework and prepared an electrolyte-locked separator (ELS) using a collagen fiber membrane (CFm). The liquid electrolyte was primarily infiltrated in the smaller voids of CFm, and its ionic conductivity could attain to 9.0 × 10−3 S cm−1 when the electrolyte absorption (EA) reached up to 112.0%. After centrifuging treatment, the electrolyte retentions (ER) and ionic conductivities of ELS were 108.93% and 8.37 × 10−3 S cm−1, respectively, which were much higher than those of commercial cellulose separator (CS), exerting excellent liquid-locking performances. In particular, the electrical double-layer capacitors (EDLC) assembled by ELS or CS were characterized and exhibited similar electrochemical performance, demonstrating the satisfactory ability and applicability of ELS for commercial use. In addition, the ELS-based EDLC exhibited favorable flexibility with relative lower loss of capacitance under different angles of bending.