In Situ Observation Using Electron Holography of Electric Potential Resulting from Li-ions

Lithium-ion batteries (LIBs) have a key role in reducing CO2 emissions because they efficiently store and release large amounts of electricity [1]. All-solid-state LIBs with nonflammable solid electrolytes offer the possibility of avoiding some of the safety issues associated with conventional LIBs that contain combustible liquid electrolytes. However, they have a lower power density, and this is mostly attributed to the large resistance to Li-ion transfer across the positiveelectrode/solid-electrolyte interface. To date, knowledge of how the local electric potential varies during Li-ion transfer has been unattainable. Here we report how electron holography was used to successfully visualize insitu the electric potential distribution near the interface with nanometer resolution.