Understanding Shelf Life of Electrolytes with LiPF6 Under Commercially Relevant Storage Conditions

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Lithium hexafluorophosphate (LiPF6) salt is the most commonly used lithium salt in commercial Li-ion batteries due to its high conductivity, passivation of Al current collectors for positive electrodes, and participation in SEI layer formation at graphite anodes.1 However, LiPF6 suffers from poor thermal stability and poor stability toward protic species (like water) leading to decomposition that can significantly reduce Li-ion battery performance especially under the extreme conditions demanded by today’s industrial applications. Specifically, LiPF6 decomposition leads to HF generation, especially in the presence of water,2 which results in multiple negative outcomes in Li-ion cells including dissolution of cathode materials and gas generation.3 Conditions during electrolyte blending, transport, and/or storage often exacerbate LiPF6 instability and increase HF generation.To date, efforts to replace LiPF6 have not proven to be commercially successful, therefore strategies to improve the stability of LiPF6 electrolytes under relevant storage conditions are critical to support the deployment of Li-ion batteries. Orbia Fluor and Energy Materials has extensively characterized the degradation of LiPF6 as a function of multiple conditions, including temperature, water content, electrolyte composition, and container materials to inform the design of strategies to improve stability.This poster will illustrate the understanding of LiPF6 decomposition (and HF generation) under conditions relevant to the Li-ion electrolyte supply chain and will present data showing a series of fluorinated materials that improve the thermal stability of LiPF6 electrolyte through the elimination of existing HF and suppression of additional formation. In addition, Orbia Fluor and Energy Materials has launched a custom electrolyte blending business to provide high quality, domestically produced lithium-ion battery electrolytes to enable the clean energy transition.