Flexible and compressible electrochemical capacitors based on polypyrrole/carbon fibers integrated into sponge

Electrochemical capacitors with flexible and compressible properties have attracted lots of attention due to the development of wearable electronic devices. Here the melamine sponge (MS) has been chosen as the carrier to integrate the electrodes of capacitors because of its compressible and porous structure. Two bunches of carbon fibers sewn into the middle of the MS are used as electrodes to electrochemically deposit the polypyrrole doped with anion of dodecyl benzene sulfonate, then the symmetric capacitors are obtained after the gel electrolyte of LiClO4/polyvinyl alcohol (LiClO4/PVA) is added into the pores of the MS. The performances of the electrochemical capacitor with electrodes integrated in the MS have been evaluated by electrochemical methods in different electrolytes. The results show that the capacitors exhibit better performance in LiClO4/PVA than in LiCl/PVA, and that the optimal capacitor can retain 98.2% capacitance after 10000 cycles, and the capacitances of the capacitors become slightly bigger under bending and compressing states compared with their normal state. The capacitors connected in parallel and series show a good electrical relationship, four cells connected in series can turn on a light emission device after being charged, indicating that the flexible capacitor exhibits potential practical application. (C) 2017 Elsevier B.V. All rights reserved.