An electrochemical energy converter integrating multiple energy conversion and transport modes

Low-grade thermal energy utilization plays an important role in addressing escalating energy demand and environmental challenges. However, primary low-grade thermal energy harvesting technologies are currently only capable of their own single and fixed energy conversion and transport modes, which limits their further application. To break this bottleneck, we innovatively propose an electrochemical energy converter (EEC(s)) cycle model, which consists of three isothermal processes and three open-circuit heating (or cooling) processes and operates between three heat reservoirs. Notably, the proposed EEC(s) integrates and enables flexible switching of thermal-to-electricity and thermal-to-refrigeration harvesting strategies. Moreover, the complementary roles of thermal energy and electricity are enabled to meet different levels of cooling demand. Significantly, its extraordinary thermal-to-refrigeration conversion efficiency and great potential as an alternative to conventional thermally driven refrigerators are emphasized. Specifically, when the EEC(s) operates at maximum cooling power density, a thermal-to-refrigeration conversion performance coefficient of 0.498 and a Carnot-relative efficiency of 32.3% are predicted for the given operating temperatures. Additionally, the different roles of the cell parameters in enhancing the EECs performance are specified. This work demonstrates the feasibility of integrating multiple energy conversion and transport modes into a novel electrochemical cycle configuration and provides a promising solution for efficient and comprehensive low-grade thermal energy utilizations.