A transparent and adhesive carboxymethyl cellulose/polypyrrole hydrogel electrode for flexible supercapacitors

The flexible supercapacitor attained increasing attention due to the unique soft and capacitive properties. However, for conductive polymer-based electrode material, the mechanical properties, conductivity and the interface bonding with the electrolyte were all challenging. Here, polypyrrole (PPy) hydrogel electrodes with high stretchability (over 700%), electrical conductivity (11.07 S m-1) and interfacial bonding properties were prepared by doping carboxymethyl cellulose (CMC). Due to the emulsification effect of CMC, PPy could form the hydrophilic CMC/PPy fibers in aqueous solutions. Moreover, during the formation process of PPy hydrogel, the uniformly distributed CMC/PPy particles were in-situ obtained, resulting in the unique visible light transmission and ultraviolet shielding characteristics of PPy hydrogel. As the flexible electrode, PPy hydrogels were assembled the all-solid supercapacitor which exhibited specific capacitance of 126.38 F g-1 and cyclic stability (capacitance retention of 82% after 1000 cycles). The facile method of the transparent PPy hydrogel paved a new way for constructing capacitive electronic skin.