Expanding the Boundaries—Exploring the Impact of Temperature on Electrochemistry in Liquid Cell Scanning Transmission Electron Microscopy

In-situ, or operando, transmission electron microscopy (TEM) has proven itself to be an invaluable tool for correlating bulk-scale electrochemical measurements to nanoscale phenomena while simulating real working conditions. The introduction of closed-cell holders allows microscopists to perform liquid experiments isolated from the high-vacuum of the microscope, protecting the sample from the vacuum as well as the microscope from the liquid. These cells, consisting of micro-electromechanical systems (MEMS) based silicon nitride chips (or E-chips) have allowed a variety of experimental stimuli to be introduced, including temperature control and electrostatic potentials.[1-2] This has enabled researchers to make strides in understanding the behavior of batteries, including the analysis of the solid-electrolyte interphase (SEI) layer during lithium-ion battery cycling to dendritic growth and analysis of failure mechanisms at room temperature.[3]<br/><br/>Recent studies have focused on expanding the life cycle and efficiency of automotive batteries in more extreme climates, resulting in the need for these next generation batteries[4] to have their formation, failure mechanisms, and material properties studied at varying working temperatures.[5] As such, the in-situ systems used to study these phenomena must be adapted through modifications of the E-chips, holder, and experimental design, in order to push these systems to similar extremes; in not just the chemical or electrostatic conditions of operation, but also by the full range of temperatures they may experience. By studying these materials in-situ, valuable information can be determined about the structural changes that are reflected in the material performance observed in bulk testing.<br/><br/>In this presentation, we will discuss experimental refinements as well as the hardware and E-chip design improvements that have allowed researchers to push the temperature boundaries during electrochemical testing in operando, as well as the challenges and solutions to working at these extreme conditions. We will discuss the impact of temperature on redox kinetics and electrochemical measurements such as cyclic voltammetry, comparing bulk results to nanoscale experiments to demonstrate the applicability of the in-situ TEM technique to real working conditions. We will additionally discuss the implications of this technique on further expanding the range of real world conditions that users can explore in the microscope, including spectroscopic analysis, experimental stimuli, and sample design.<br/><br/>[1] S, Sturm, <i>et al.</i> <i>European Microscopy Congress 2016: Proceedings</i>.<br/>[2] R. Unocic, <i>et al</i>. <i>Microsc. Microanal.</i> <b>2014</b>, <i>20</i> (2), 452–461.<br/>[3] W. Dachraoui, <i>et al.</i> <i>ACS Nano</i> <b>2023</b> <i>17</i>(20), 20434-20444<br/>[4] Y, Kaname, <i>et al. </i> <i>Microscopy</i> <b>2024 </b>73 (2): 154–68.<br/>[5] X, Hu, <i>et al</i>. Progress in Energy and Combustion Science, 77, 2020, 100806