Abstract
Recent economic and productivity gains of rechargeable batteries have cemented their dominance in energy-intensive societies. With demand soaring, enhancing battery performance through continuous monitoring is essential to limiting their environmental footprint. While some benefits of sensing have been known for a century, the convergence of fiber optic techniques with new battery platforms is poised to change the industry as a wealth of chemical, thermal, and mechanical data will transform the utilization strategies for new and used lithium-ion devices alike. This Review highlights recent advances and associated benefits with a focus on optical sensors that could improve the sustainability of batteries.