Review—Li-Ion Photo-Batteries: Challenges and Opportunities

Humanity's greatest challenge in the 21st century consists in transitioning from fossil fuels towards renewable energy technologies. Since all renewable are intermittent, the common challenge for all renewables is storage. In this context, designing and realizing hybrid devices that combine energy conversion with storage represents a major opportunity. Among renewables, solar energy is particularly important, because in one hour the Sun sends towards us enough energy to power the whole planet for one year; nevertheless, our current global use of solar energy is only about 1%, The aim of this short review is to describe the current state of the art and perspectives in the emerging area of photo-rechargeable batteries. This hybrid device consists in a photo-electrochemical system that combines solar energy conversion with electrochemical storage, storing energy during the day and allowing release at night. While the opportunity of combining solar and battery technologies into a single system is promising, major challenges are yet to be overcome. Here we summarize the most promising architectures developed so far and potential research directions in this exciting area of technology.