Development of a Laser Scanning Measurement System for Battery Cell Characterization

Abstract

A precise understanding of the physical properties of lithium-ion cells including cell thickness distribution and its connection with lifetime is important for cell improvement. A laser scanning instrument was developed to perform contact-free thickness measurements for small 250 mAh lithium-ion pouch cells and a large 60 Ah automotive pouch cell. LiNi0.83Mn0.07Co0.10O2/silicon-graphite cells with 20 and 10 wt% micron-sized silicon particles, a LiNi0.8Mn0.1Co0.1O2/natural graphite cell, and a medium-Ni/graphite automotive cell were cycled on the laser scanner with continuous operando thickness mapping or aged at elevated temperature on separate battery cyclers with intermittent operando thickness mapping using the laser scanner. During operando, cell thickness was measured every 1 hour, and a graphing method was developed to determine the reversibility of cell swelling. The high-resolution laser scanner correlated irreversible swelling with capacity loss for silicon-containing cells. Graphite-based cells with mature interface like the automotive cell showed reversible swelling indicative of a long-lived cell.