A Guide to Making Highly Reproducible Li-Ion Single-Layer Pouch Cells for Academic Researchers

Abstract

With the growing number of academic researchers focused on lithium-ion batteries, the cell format of choice is often overlooked. Coin cells that utilize either a lithium metal or greatly oversized graphite negative electrode are common but can provide unrealistic testing results when compared to commercial pouch-type cells. Instead, single-layer pouch cells provide a more similar format to those used in industry while not requiring large amounts of active material. Moreover, their assembly process allows for better positive/negative electrode alignment, allowing for assembly of single-layer pouch cells without negative electrode overhang. This work presents a comparison between coin, single-layer pouch, and stacked pouch cells, and shows that single-layer pouch cells without overhang perform best. As well, an Ultra-High Precision Coulometry experiment is performed to show that excess negative or positive electrode coating is detrimental to cell performance. Finally, a guide to assembling reproducible single-layer pouch cells without overhang is presented.