Interrogating the Light-Induced Charging Mechanism in Li-Ion Batteries Using <i>Operando</i> Optical Microscopy
Raj Pandya, Angus Mathieson, Buddha Deka Boruah, Hilton B. de Aguiar, Michaël De Volder
Abstract
High Resolution Image Download MS PowerPoint Slide Photobatteries, batteries with a light-sensitive electrode, have recently been proposed as a way of simultaneously capturing and storing solar energy in a single device. Despite reports of photocharging with multiple different electrode materials, the overall mechanism of operation remains poorly understood. Here, we use operando optical reflection microscopy to investigate light-induced charging in Li x V 2 O 5 electrodes. We image the electrode, at the single-particle level, under three conditions: (a) with a closed circuit and light but no electronic power source (photocharging), (b) during galvanostatic cycling with light (photoenhanced), and (c) with heat but no light (thermal). We demonstrate that light can indeed drive lithiation changes in Li x V 2 O 5 while maintaining charge neutrality, possibly via a combination of faradaic and nonfaradaic effects taking place in individual particles. Our results provide an addition to the photobattery mechanistic model highlighting that both intercalation-based charging and lithium concentration polarization effects contribute to the increased photocharging capacity.