Revealing the Limitations of the Thermocapacitive Cycle

While thermoelectric conversion by a thermocapacitive cycle has been considered a promising green technology for low-grade heat recovery, our study finds that its practical feasibility is overestimated. During thermal charging, the coexistence and dynamic competition between thermal-induced voltage rise and self-discharge lead to the limitations of the thermocapacitive cycle. Therefore, the operational conditions in the charge-heat-discharge steps seriously restrict the thermal charging performance. The calculation of energy efficiency further confirms the economic infeasibility of the thermocapacitive cycle. This study provides insights into comprehending the principle and process of thermoelectric conversion by thermocapacitive cycle and will guide the rational development of capacitive heat-to-current converters.