Energy materials for transient power sources

Transient energy supply remains one of the key challenges limiting the development of transient implantable medical devices for monitoring, diagnosis, and treatment of diseases within a predetermined time frame. A key feature of such devices is their controllable degradation during service life. An on-board transient energy supply with predictable performance over time is required to drive transient electronics. In this article, we present recent advances in the development of materials for biodegradable energy-storage devices (batteries and supercapacitors) and biodegradable energy-harvesting systems (enzymatic biofuel cells and triboelectric nanogenerators). Future perspectives, challenges, and opportunities related to energy materials for transient power sources will also be summarized.