Preparation of polyacrylamide/calcium alginate@Ti3C2Tx composite hydrogels with high adhesive performance for flexible supercapacitor electrolytes

Polymer hydrogels are a promising electrolyte for flexible superconductors (FSCs) due to their excellent flexibility, ions transportations and interfacial compatibility. However, the large internal resistance will decrease the power density (PD) and energy density (ED) of FSCs. In this work, Ti3C2Tx was introduced to polyacrylamide/calcium alginate (PC) hydrogel electrolyte to decrease the internal resistance (IR) and improve the interfacial adhesion. The polyacrylamide/calcium [email protected]3C2Tx (PCT) composite hydrogels were successfully prepared by in-situ polymerization. Their mechanical property and adhesive property to various substrates were investigated, respectively, and a flexible supercapacitor was assembled with composite hydrogels as electrolyte and two self-made Ti3C2Tx sheets as electrode. It was found composite hydrogels can adhere to various substrates, which make the voltage drop of FSCs from 163 mV to 78.9 mV. The FSCs show a good performance, whose specific capacitance is 1051.9 mF cm−2 with a current density of 1.07 mA cm−2, and the ED reaches 32.3 Wh kg−1 and the capacitance retention rate is as high as 96% at a high current density of 18.7 mA cm−2. Meanwhile, it can sensitively monitor human movements such as finger bending, frowning, swallowing, etc. This work is expected to be applied in the field of energy storage and sensing.