Membrane-free redox flow cell based on thermally regenerative electrochemical cycle for concurrent electricity storage, cooling and waste heat harnessing of perovskite solar cells

Global climate change requires a significant reduction of greenhouse gas emission through developing sustainable energy technologies such as photovoltaic (PV) devices. However, the inherently variable nature of solar irradiance and consequent electricity generation increase challenges for the system stability of electrical grids. Moreover, the PV devices face significant performance loss under full irradiance conditions with 55–65 °C operating temperature. Herein, we demonstrate a novel solar energy conversion and storage (SECS) system by integrating a perovskite PV device with a low-cost membrane-free Zn/Mn-based redox flow battery (RFB) which has a quite negative temperature coefficient. The proof-of-concept SECS system shows great potential for future large-scale deployment of sustainable energy by three concurrent processes: (1) Liquid electrolyte of RFB provides an effective cooling process for the PV device, mitigating its performance loss at high temperature. (2) Thermally regenerative electrochemical cycle (TREC) allows RFB to generate additional electricity from the low-grade heat gathered from the solar cell at a high absolute thermoelectric efficiency, which adds to the overall system efficiency. (3) RFB timely stores the electricity produced by the solar cell, buffering the fluctuation of solar power, stabilizing the electrical grids, and reducing the energy curtailment.