Highly conductive PANI/ATMP/AgNO3 composite hydrogel electrodes for all-hydrogel-state supercapacitors

Abstract

High electronic conductivity and excellent specific capacitance still remain challenge for the practical application of hydrogel electrodes. Herein, a novel polymer composite hydrogel electrode, PANI/PVA/ATMP/Ag (PPA-Ag), has been successfully constructed through in situ polymerization of aniline (ANI) in solution of polyvinyl alcohol (PVA), amino trimethylene phosphonic acid (ATMP) and silver nitrate (AgNO3). The incorporation of AgNO3 is expected to enhance the electronic conductivity and excellent specific capacitance of PPA hydrogel electrodes. The AgNO3 incorporated PPA-Ag hydrogel electrode exhibited a superior specific capacitance (510 F g-1 at 0.5 A g-1), which was much higher than the pristine one without introducing AgNO3 (317 F g-1 at 0.5 A g-1). Additionally, the PPA-Ag hydrogel electrode also showed excellent flexibility (93.43% capacitance retention after 200 cycles of bending) and excellent cyclic stability (81.41 % of initial capacitance after 10000 cycles). The energy storage mechanism originated from the three-dimensional porous structure of hydrogel, the multiple redox structures of polyaniline and the Ag+/Ag of silver nitrate. The all-hydrogel-state supercapacitor was assembled based on the PPA-Ag hydrogel electrode, which delivered a high energy density of 13.3 W h kg-1 at a power density of 125 W kg-1. Meanwhile, the supercapacitors can also maintain above 77% of the initial capacitance after 10000 charge-discharge cycles. This work constructed polymer hydrogel electrodes with high electronic conductivity and excellent specific capacitance for flexible supercapacitors, which demonstrated the great potential within the field of flexible energy storage.