Quantitative visualization of ion and thermal distributions in electrolytes during operation of electrochemical devices by Operando phase-contrast X-ray imaging

A fundamental understanding of transport properties (e.g., ion transport, thermal transport, etc.) in electrolytes is important for energy storage/conversion devices such as lithium-ion batteries because poor transport properties in electrolytes cause significant performance degradation, especially for high-power applications. However, few techniques can be used to quantitatively characterize transport behavior in the electrolyte during the device operation. We have determined that the operando phase-contrast X-ray imaging technique allows for simultaneous quantitative characterization of transport phenomena in electrolytes during electrochemical device operation with high temporal (seconds) and spatial (a few 10-microns) resolutions. In this paper, we show the results of quantitative visualization of ion concentration distribution in the electrolyte of an operating lithium-ion battery, electrolyte stratification behavior of an operating lead-acid battery, and dynamic behavior of ion concentration distribution and thermal distribution in the electrolyte of a thermo-electrochemical cell under temperature difference application, respectively. Graphical abstract