Cryogenic Laser Ablation Reveals Short-Circuit Mechanism in Lithium Metal Batteries
Katherine Jungjohann, Renae N. Gannon, Subrahmanyam Goriparti, Steven Randolph, Laura C. Merrill, David C. Johnson, Kevin R. Zavadil, Stephen J. Harris, Katharine L. Harrison
Abstract
The dramatic 50% improvement in energy density that Li-metal anodes offer in comparison to graphite anodes in conventional lithium (Li)-ion batteries cannot be realized with current cell designs because of cell failure after a few cycles. Often, failure is caused by Li dendrites that grow through the separator, leading to short circuits. Here, we used a new characterization technique, cryogenic femtosecond laser cross sectioning and subsequent scanning electron microscopy, to observe the electroplated Li-metal morphology and the accompanying solid electrolyte interphase (SEI) into and through the intact coin cell battery’s separator, gradually opening pathways for soft-short circuits that cause failure. We found that separator penetration by the SEI guided the growth of Li dendrites through the cell. A short-circuit mechanism via SEI growth at high current density within the separator is provided. These results will inform future efforts for separator and electrolyte design for Li-metal anodes.