Black TiO₂ Nanoparticle/Carbonized Melamine Sponge Photothermal Conversion Layers for Improved Low-Temperature Performance of Supercapacitors

Abstract

Energy storage devices for example supercapacitors suffer from severe capacitance decay at low temperature, which limits their application in extreme conditions. In spite of great efforts dedicated to develop a low-temperature-resistant electrolyte, the problem is still not solved satisfactorily. In this work, to address the problem, black TiO 2 / carbonized melamine sponge (CMF) was designed and prepared by adjusting the band gap of TiO 2 nanoparticles due to the excellent photothermal conversion ability of black TiO 2 nanoparticles. Benefiting from its excellent photothermal conversion ability, the performance of flexible supercapacitors at low temperatures has been greatly improved. A supercapacitor based on activated carbon electrodes is encapsulated in black TiO 2 /CMF serving as a photothermal conversion layer at low temperature. The specific capacitance of a supercapacitor is improved by 287.67% at −15 °C and improved by 187.51% at −50 °C under solar illumination. The proposed photothermal conversion material in this work shows great potential under a low-temperature environment and can be extended to other energy storage devices.