Designing reliable electrochemical cells for operando lithium-ion battery study

Operando experiments attract increasing attention in lithium-ion batteries (LIBs) studies for their ability to capture non-equilibrium and fast-transient processes during electrochemical reactions. They provide valuable information and mechanisms that cannot be obtained from ex-situ methods. Designing a suitable and reliable electrochemical cell is the first crucial step for most operando studies. A poorly designed in-situ cell introduces artifacts into the data and might lead to misleading results. Even though many in-situ cells have been designed and applied for operando studies, designing a reliable cell is not trivial, especially for long-term cycling experiments. This study introduces the steps and details of a specific type of in-situ cell, i.e., modified coin cell, that can be applied reliably in various operando experiments. The reliability of the modified coin cell is demonstrated by comparing its electrochemical performance with the standard coin cell. The modified coin cell is then applied in various operando experiments, including operando transmission X-ray microscopy and operando synchrotron X-ray scattering. • Sealing the cell casing window with metal films maintains the overall electrochemical performance of electrodes. • Depending on the operando experiment, the type of the coin cell and the window shape must be selected carefully.