Photo-enhanced LiMn₂O₄ lithium-ion batteries: Separating the effects of light and heat

Illumination with visible light is a promising route to enhance the electrochemical energy storage in batteries, with particular importance for the transformation to green energy. For the Li-ion battery cathode LiMn₂O₄, accelerated charging under light was demonstrated and attributed to photo-induced charge carrier dynamics [1]. However, light exposure heats up illuminated battery cells and thus can also increase electrochemical performance by a photothermal effect. Decoupling the effects of light and heat through temperature-controlled experiments, we confirm the reported faster charging under illumination and reveal that light induces improved kinetics in terms of reduced overpotentials beyond a photothermal contribution. We discuss the potential of electron paramagnetic resonance spectroscopy (EPR) to elucidate the underlying light-induced mechanisms based on the temperature dependence of EPR spectra under dark and illuminated conditions, and further address the challenge to discriminate photoelectrical responses from photothermal signal changes.



[1] Lee et al; Nat Commun 10, 4946 (2019): doi.org/10.1038/s41467-019-12863-6