Polyethylene terephthalate-based cathode current collectors coated by ultrathin aluminum metal layers for commercial lithium-ion batteries with high security and long-term cycling stability

With the rapidly increasing market demand of lithium-ion batteries (LIBs), safety has become the main focus and challenge in realizing high-energy and high-safety LIBs. In this paper, a light-weight composite current collector, which is prepared by sandwiching a polyethylene terephthalate (PET) film between two ultrathin aluminum (Al) layers, is designed to improve the safety performances of the LIBs. The PET film is selected as the supporting film due to its low density, superior mechanical properties, excellent thermal stability, and remarkable flame resistance. The thermal and mechanical stabilities of the PET-Al based electrode systems, as well as the electrochemical performances of the corresponding LIBs, are evaluated. Nail penetration test further is carried out to investigate the internal short-circuit behaviors of the batteries, which is the most extreme and hazardous condition and may cause thermal runaway and catastrophic accidents. The results well demonstrate that the proposed PET-Al current collector can slow down the temperature rise of the entire battery during the nail penetration, and effectively achieve the aim of improving the reliability performances of LIBs. •A composite-based current collector is fabricated by sandwiching a PET film between two ultrathin Al layers.•The PET-Al film possesses good thermal and mechanical stabilities, as well as good electrochemical properties.•The lighter weight of PET-Al current collector can promote the energy density of the LIB.•The PET-Al-based LIB passes the nail penetration test with no flame evidence.•The PET-Al current collector can effectively improve the safety performance of the LIB.