A flexible and hydrophilic hydrogel film based all-in-one supercapacitor

In recent years, the integrated supercapacitors have made remarkable progress, but it is still considered a huge challenge to obtain an ultra-flexible and stable all-in-one supercapacitor under diverse deformations. Herein, a novel all-in-one supercapacitor is constructed through preparing soft enough and hydrophilic polyacrylamide (PAM/LiCl) hydrogel film, subsequently, polymerizing and depositing of hydrophobic polypyrrole (PPy) nanocomposites onto the two-sided surfaces of the PAM/LiCl hydrogel. It is found that the all-in-one supercapacitor exhibits excellent flexible stretching up to 650 % of original length, high specific capacitance (229.8 mF cm−2 at 0.8 mA cm−2), and high ionic conductivity (29 mS cm−1). Interestingly, the all-in-one supercapacitor can remain 30 days without obvious deterioration in capacitance. Moreover, the all-in-one supercapacitor presents also eminent cycling performance. The capacitance can remain 80 % of initial capacitance after 5000 cycles. This all-in-one flexible supercapacitor provides great potential prospects in wearable energy devices involving mechanical impacts.