A Thermally Chargeable Hybrid Supercapacitor with High Power Density for Directly Converting Heat to Electricity

Electrical charging and discharging supercapacitors are well-known and invoke plenty of studies. There exist few publications on thermal-driven electrochemical reactions and storing devices, although such devices are in urgent need for efficiently utilizing waste heat and solar heat. In this work, we propose an innovative method of coupling electric double layer and ion intercalation approaches for developing a thermally chargeable hybrid supercapacitor (TCHS) with a high output power density, which can simultaneously convert heat from different available sources directly to electricity and store it in situ. The working principle of a TCHS is fully different from that of an electrically chargeable supercapacitor. We experimentally verify the feasibility of a TCHS. In the case that the developed device operates under a temperature difference of 50 °C, for example, it can generate a temperature coefficient of up to 12.1 mV K–1 and a maximum output power density of 20.4 W m–2, which is the highest level for a thermally chargeable supercapacitor at the moment. Such a device can realize the electric energy storage at the same time and overcome the instability and intermittent restriction of heat energy supply.