The extensive exploration of energy conversion harvested from the environment into electricity is recently driven by the significant demand to power off-grid electronics, particularly Internet-of-Things (IoT) sensors. This highlight previews the latest advance of a charging-free thermally regenerative electrochemical cycle (TREC) for continuous electricity generation from solar heat and darkness with the aid of dual-mode thermal regulations. Such a spontaneous all-day electricity generation with high power and efficiency shows great potential for powering a wide range of distributed electronics for IoT and other applications.