Fundamentals

Coin Cells vs. Pouch Cells For Battery Research Coin Cell

Pouch Cell

Process

Electrodes and separator disk punching, then crimping of disks, spacer, and spring into coin cell. For statistical analysis, 310 cells/batch is recommended.

Electrode cutting and stacking, tab welding, pouch sealing, electrolyte injection, formation, degassing and resealing.

Electrode Alignment

Alignment of cathode and anode is important (ideally 100%. Murray et al. show that coin cells built with equal sized electrodes, a single layer of BMF separator, and a vacuum pen instead of tweezers are more repeatable than other coin cell configurations 2.

Major risk of misalignment due to many manual steps. Garayt et al. demonstrate that single layer pouch cells without anode overhang perform better 3.

Cell Pressure

Internal pressure comes from spring and stack thickness.

Fixture provides external pressure.

Electrolyte

Electrolyte amount needs to controlled (excess can lead to spilling during crimping).

Pouch cell drying and electrolyte wetting are more significant given larger surface area.

“To achieve accurate and reliable data on new materials for batteries, repeatability, and quality of cell fabrication are critical to ensure reproducible findingsˮ 1

Source: 1 Dai, F., Cai, M. Best practices in lithium battery cell preparation and evaluation. Commun Mater 3, 64 2022. https://doi.org/10.1038/s43246022002868 2 Vivian Murray et al 2019 J. Electrochem. Soc. 166 A329 3 Matthew D. L. Garayt et al 2023 J. Electrochem. Soc. 170 080516

Extracted from the PDF; charts and images may read imperfectly.