Redox electrodes for electrochemical energy storage and thermal energy conversion

ABSTRACT: Thermo-electrochemical cells (TECs) are a new kind of energy conversion device that can convert thermal energy into electricity. TECs can be integrated with supercapacitors (SCs) to store the generated electricity. TECs consist of two major components namely electrodes and electrolyte. The selection of appropriate electrode materials with rational nanostructured design should improve the thermoelectrochemical performance of the TECs. In this study, bilayer of nickel cobalt selenide nanowires was successfully grown on activated carbon cloth (NCS/ACC) via one step hydrothermal method and its electrochemical performance was evaluated and compared with nickel selenide (NS/ACC) and cobalt selenide on activated carbon cloth (CS/ACC). NCS/ACC exhibited the best electrochemical performance compared to other electrodes, leading to its further investigation in an asymmetric supercapacitor (ASC) configuration with activated carbon (AC) as the cathode. The NCS/ACC ASC demonstrated superior rate capability with 85% capacitive retention after 10,000 cycles, along with a high specific energy (28 Wh kg-1) and specific power (646 W kg-1). Subsequently, the NCS/ACC electrode was employed in a thermo-electrochemical cell (TEC) for heat to electricity conversion, revealing a Seebeck coefficient of -2 mV/K with high reversibility. Thereby, NCS/ACC electrode can be a suitable candidate for bi-functional applications, showcasing its efficacy in both supercapacitors and heat to electricity conversion technologies. KEYWORDS: Heat to electricity conversion; Supercapacitors; Electrodes; Metal selenide; Thermo-Electrochemical Cell.