Electric Potential Mapping of All-Solid-State Lithium Ion Batteries using A Terahertz Chemical Microscope

A terahertz (THz) chemical microscope has been developed to measure the electric potential distribution of liquid phase lithium ion batteries (LIBs) during charging and discharging. A LIB was fabricated on a sensing plate, which consists of SiO
2
and Si films on a sapphire substrate, to generate THz pulses by a laser irradiation. Since the amplitude of THz is proportional to the electric potential on the sensing plate, the electric potential distribution of the lithium ion battery on the sensing plate could be visualized. In this study, the electric potential distribution across a conventional all-solid-state LIB was measured by immobilizing the LIB on the sensing plate using epoxy resin. The distribution of the electric potentials of the battery was clearly visualized by the TCM. This result indicates that the TCM could be one of useful tools for the development high performance batteries.