A Thermally Chargeable Supercapacitor based on the g-C₃N₄-Doped PAMPS/PAA Hydrogel Solid Electrolyte and 2D MOF@Ti₃C₂T_x MXene Heterostructure Composite Electrode

With the development of individual wearable electronics, the requirements of self-energy harvest devices from human skin or motion have increased. A thermal harvest device that receives thermal energy naturally existed in human skin is more attractive than a mechanical energy harvester that needs human motion or walking. Herein, a thermal-chargeable supercapacitor (TCSC) is proposed, which can convert thermal energy into electrical energy and then store the energy only by occurring the temperature difference between the two ends of the TCSC. The all-solid-state g-C₃N₄-modified hydrogel electrolyte in the TCSC provides more free protons and energy for proton migration by the electrostatic interaction and hydrogen bond interaction between g-C₃N₄ and the acid group. The 2D MOF@Ti₃C₂T_x MXene heterojunction electrodes with the advantages of large pore size, adjustable and abundant REDOX sites of MOFs, and high conductivity of Ti₃C₂T_x MXene also ensure the high performance of the TCSC. As a result, the assembled TCSC exhibits excellent ionic thermal-voltage (55.68 mV), Seebeck coefficient (18.56 mV K⁻¹), and energy exchange efficiency (3.4%) upon a temperature difference of 3 K, and successfully drives the pressure sensor work.