Investigating Sealing Methods for Three-Electrode Coin Cells

With rising CO₂ emissions, it is critical that we decarbonize the energy sector. Renewable energy resources offer a sustainable solution, but their intermittency reveals the need for better energy storage systems. Improving energy storage requires the study of the side reactions and transport limitations that happen inside of batteries. By isolating the anode and cathode potentials, three electrode-cells allow for a better understanding of these processes. However, they have low durability due to the opening at the junction of the third electrode, which allows moisture into the cell. In this study, we investigated three different epoxies (5-minute epoxy, Permabond 737, and Permabond 940) to determine the most effective sealing method. We used lithiated graphite inside of three-electrode cells as an indicator of the moisture content, and assembled four batches of cells to open at varying intervals. The resulting graphite was photographed to compare its color, since it is correlated to contact with water. The average RGB values of the images were extracted and compared statistically. Our study found that Permabond 940 allowed the most moisture inside the cell, while Permabond 737 and 5-minute epoxy improved cell longevity. There was not a significant difference between the Permabond 737 and the 5-minute epoxy. While this study provides valuable insights into sealing methods for three-electrode cells, further research with improved imaging and analytical methods is needed for conclusive results.