In-Situ Liquid Cell TEM Studies of Electrochemical reactions in Lithium-ion Batteries

Lithium-ion batteries (LIBs) are the preferred energy storage devices for portable electronics and electric vehicles due to the long cycle life and high energy density [1]. The development of new electrodes for next-generation batteries requires better understanding how electrodes function by realtime tracking the electrochemical reactions in individual particles and the collective behavior of particles assembled in an electrode. Various available characterization methods, such as in-situ X-ray techniques, are powerful for real time tracking charge/discharge dynamics of electrodes in liquid electrochemical system, but with limited spatial resolution. Recently the development of in-situ TEM techniques enables real time observation of structural and chemical evolutions of electrodes during battery operation at high spatial and temporal resolution [2]. However, due to the use of an open-cell configuration in these platforms, solid or ionic liquid electrolyte needs to be used for compatibility with high vacuum in the TEM column. In order to study the lithium reaction with electrodes in liquid electrolyte as generally used in LIBs, we developed a liquid electrochemical cell with thin membrane windows to seal the liquid electrolyte, allowing for both TEM and X-ray measurements with the sample in liquid environments. Here, we present our recent results from the development and application of the liquid electrochemical cells for in-situ TEM studies of lithium transport and reaction in individual particles upon lithiation and delithiation.