Abstract

Every lithium-ion battery cell produced today that is either wound or stacked contains tape. This tape serves the mechanical purpose of holding together the wound jellyroll or stacked electrodes before inserting it into the cell casing, after which the tape serves no purpose. Battery manufacturers often test inactive cell parts for their physical parameters, i.e., elongation, water absorption, and temperature resistance.1 However, their chemical stability is often overlooked. Recently, it was demonstrated that polyethylene terephthalate (PET) tape can partially dissolve in the harsh lithium-ion battery cell chemistry into its monomer dimethyl terephthalate (DMT). This molecule can act as an unwanted redox shuttle in LFP/graphite or NMC811/graphite cells, inducing self-discharge of the battery.2 Figure 1 shows Fourier-transform infrared (FTIR) spectra of tapes obtained from discarded cellphone batteries. Many well-known lithium-ion battery producers use PET tape in their products. In addition, the FTIR spectra show that after the cells have been cycled, the surface layer of these tapes is severely corroded. This study will show open circuit storage, Ultra-High Precision Coulometry, and long-term cycling results from LFP/graphite cells with PET tape. The study will also show how swapping PET tape for a more stable alternative can significantly improve the performance and reduce the self-discharge of LFP/graphite pouch cells.Figure caption: Figure 1 . FTIR spectra of jellyroll closing tapes (a) extracted from discarded cellphone batteries (b).

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.