Utility of Deactivation By Saltwater Immersion for End-of-Life Processing of Lithium-Ion Cells
Authors: Waller Gordon Henry , Carter Rachel E. , Love Corey T. 
Published: November 2022

Recycling of lithium-ion batteries is envisioned to become an important aspect of ensuring future access to the critical materials used in lithium-ion batteries (LIB) (1). This is particularly true for nickel, cobalt, and lithium, which have experienced extreme price fluctuations and projections of supply shortfalls in the near future. Current recycling efforts are focused on recovering the most valuable components like those mentioned above, however emerging efforts have also demonstrated the feasibility of recovering intact active materials and even direct recycling of electrode composites. All recycling efforts have a common logistical challenge – cells and batteries must be aggregated at recycling facilities once they reach the end of their useful life. This aggregation also introduces safety challenges due to the possibility for residual or stranded energy in lithium-ion cells. A 2021 report from the United State Environmental Protection Agency (US EPA) highlighted this issue, reporting that 89% of 245 fires reported from U.S. materials recycling facilities between 2013-2020 were attributed to lithium metal or lithium-ion batteries (2). Energetic failures including thermal runaway has been reported in lithium-ion cells of various chemistries at states-of-charge (SOC) as low as 15% in response to thermal abuse, and cells experienced temperatures above 100 °C in response to external short-circuiting at SOC as low as 30% (3). Saltwater immersion has been reported as an effective method to remove residual energy from lithium-ion cells (4) (5) (6). However, most efforts have focused on the discharge rate of various solution conditions as determined by cell voltage, and offer limited insight into safety impacts and the recoverability of active materials. Qualitative descriptions of corrosion during saltwater immersion, which can be severe, have also been reported in academic literature. This presentation will focus on demonstrating the role of various immersion solution parameters (e.g. solute and other additives, temperature) on the efficacy of removing residual energy from LIB as measured by electrochemical testing of representative systems as well as commercial lithium-ion cells. Impacts of corrosion and cell safety will be discussed through materials analysis (X-ray Photoelectron Spectroscopy, Scanning Electron Microscopy + Energy Dispersive X-ray Spectroscopy) and battery calorimetry (Accelerating Rate Calorimetry).

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