Environmentally Friendly and Self-Healable Supercapacitors Realized by a NaCl-Penetrable Polyampholyte Conductive Hydrogel

Environmentally friendly and self-healable supercapacitors (EFSH-supercapacitors) hold promise to support high safety and extend the lifetime when undergoing mechanical loads and, therefore, share great application in flexible wearable electronics. Here, we develop this kind of a supercapacitor through using a polyampholyte (PA) hydrogel that possesses the capability of salt permeation and self-healing. The ionic conductivity of the PA hydrogel is largely enhanced (up to 13.2 mS cm–1) by both bonding and adsorbing NaCl salt. The balanced electrical and mechanical performance of NaCl infiltrated PA hydrogel facilitates strong electrode–electrolyte interfacial linkage and low charge transfer resistance, which enables the EFSH-supercapacitor to have state-of-the-art electrochemical properties. We show that supercapacitor after structural failure as PA hydrogel electrolyte is cut into two pieces, for which stored energy was previously completely damped, can now be rapidly (8 min) and repeatedly repaired (∼54% after four times self-healing). We also prove that the damage of the whole supercapacitor including both electrodes and electrolyte can also be successfully repaired. The electrolyte-dried supercapacitor recovers to efficient work by adding synthetic sweat, demonstrating its practical application in wearable electronics.