As demand for high-performance lithium-ion batteries (LIBs) surges across new civilian and military markets, so does demand for increased charging rates and extended battery life. Unfortunately, this push toward improved battery performance is accompanied by an increased risk of internal lithium plating and subsequent short-circuiting. Both introduce an inherent safety hazard which extends beyond the standard safety concerns associated with lithium ion batteries. It is widely accepted that plated lithium both initiates and increases the rate of reaction of runaway events, however its effects have yet to be quantified and isolated from other exothermic reactions occurring in the cell. Due to lithium’s high physical mobility, volatile high-temperature kinetics, and instability in the presence of humidity, it is important to identify and isolate the unique hazards associated with molten lithium during battery failure. This area of study was of interest to the Power Sources Technology Group (PSTG) at Sandia National Laboratories due to our unique cradle-to-grave capabilities, which allowed for every aspect of the cell development and testing process to be closely monitored. This included fabrication of individual cells (>1 Ah) with preferential nucleation sites followed by electrochemical plating and subsequent abuse testing of each cell at the battery abuse testing laboratory (BATlab). The ability to precisely control the extent of lithium plating allowed for facile correlation between the extent of lithium plating and worsened abuse response. Additionally, the ability to monitor cells during thermal runaway allowed for direct observation of the potential hazards associated with high concentrations of molten lithium being dispersed during a failure event.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.