F.S. Gray, E. Cheever, W.S. Tang, J. Jeevarajan
UL Research Institutes: Electrochemical Safety Research Institute,
United States
Keywords: lithium-ion batteries, grid storage, cycle life, FMEA, safety
Summary:
In the past decade, lithium-ion batteries (LIBs) have grown to prominence in the field of energy storage, dominating the market share for powering consumer electronics and vehicle electrification due to their energy density and long cycle life. Along with this widespread implementation, improving infrastructure and economies of scale have drastically reduced costs and are paving the way for an increased adoption of LIBs for grid storage as well. This stationary application shifts the focus away from energy density toward cycle life. One of the primary routes for improving cycle life is to perform a failure modes and effects analysis (FMEA) on an end-of-life battery and identifying the underlying failure mechanisms. This allows the cell to be designed not only for performance, but also to eventually fade in a safe and predictable manner, and circumvent any risk of thermal runaway. However, the destructive physical analysis (DPA) process, in which a battery is disassembled to study the inner components, has very little standardization and the question of procedural impact is often glossed over, which potentially affects conclusions. This work aims to demonstrate the impacts that variations in the rinsing and handling practices have on the subsequent analyses of lithium-ion cylindrical cells and provide suggestions for optimization.