Adamson Anu, Tuul Kenneth, Bötticher Tom, Azam Saad, Garayt Matthew D L, Metzger Michael
Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada.
Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada.
Nat Mater. 2023 Nov;22(11):1380-1386. doi: 10.1038/s41563-023-01673-3. Epub 2023 Sep 21.
Polyethylene terephthalate (PET) tape is widely used by well-known lithium-ion battery manufacturers to prevent electrode stacks from unwinding during assembly. PET tape is selected since it has suitable mechanical and electrical properties, but its chemical stability has been largely overlooked. In the absence of effective electrolyte additives, PET can depolymerize into its monomer dimethyl terephthalate, which is an unwanted redox shuttle that induces substantial self-discharge in a lithium-ion cell. This study presents a chemical screening experiment to probe the PET decomposition mechanism involving in situ generated methanol and lithium methoxide from dimethyl carbonate, one of the most common electrolyte solvents in lithium-ion cells. By screening other polymers, it is found that polypropylene and polyimide (Kapton) are stable in the electrolyte. Finally, it is demonstrated that reversible self-discharge of LiFePO-graphite cells can be virtually eliminated by replacing PET jellyroll tape with chemically stable polypropylene tape.
聚对苯二甲酸乙二酯（PET）胶带被知名锂离子电池制造商广泛用于防止电极堆叠在组装过程中松开。选择PET胶带是因为它具有合适的机械和电气性能，但其化学稳定性在很大程度上被忽视了。在没有有效电解质添加剂的情况下，PET会解聚成其单体对苯二甲酸二甲酯，这是一种有害的氧化还原穿梭剂，会在锂离子电池中引起大量自放电。本研究提出了一项化学筛选实验，以探究PET分解机制，该机制涉及从碳酸二甲酯原位生成甲醇和甲醇锂，碳酸二甲酯是锂离子电池中最常见的电解质溶剂之一。通过筛选其他聚合物，发现聚丙烯和聚酰亚胺（Kapton）在电解质中是稳定的。最后，证明用化学稳定的聚丙烯胶带代替PET卷绕胶带几乎可以消除LiFePO-石墨电池的可逆自放电。
