All-in-one energy harvesting and storage devices

Currently, integration of energy harvesting and storage devices is considered to be one of the most important energy-related technologies due to the possibility of replacing batteries or at least extending the lifetime of a battery. This review aims to describe current progress in the various types of energy harvesters, hybrid energy harvesters, including multi-type energy harvesters with coupling of multiple energy sources, and hybridization of energy harvesters and energy storage devices for self-powered electronics. We summarize research on recent energy harvesters based on the piezoelectric, triboelectric, pyroelectric, thermoelectric, and photovoltaic effects. We also cover hybrid cell technologies to simultaneously generate electricity using multiple types of environmental energy, such as mechanical, thermal, and solar energy. Energy harvesters based on the coupling of multiple energy sources exhibit enhancement of power generation performance with synergetic effects. Finally, integration of energy harvesters and energy storage devices is introduced. In particular, self-charging power cells provide an innovative approach to the direct conversion of mechanical energy into electrochemical energy to decrease energy conversion loss.