Prevention of lithium-ion battery thermal runaway using polymer-substrate current collectors

Abstract

Isolating electronically conducting material from internal short circuits is a promising way to prevent the onset of thermal runaway within lithium-ion cells. Here, a metal-coated polymer current collector, which is designed to disconnect internal short circuits by withdrawing from the heating region, is tested in 18650 cells. In addition to having lower mass and manufacturing costs, cells with metal-coated polymer current collectors demonstrate a reduced risk of thermal runaway during nail penetration. High-speed synchrotron X-ray radiography of 18650 cells during nail-penetration testing, in tandem with pre- and post-mortem X-ray computed tomography, provides insights into the function of the current collectors. The results are compared with those of 18650 cells with standard commercial aluminum and copper current collectors. Cells with aluminum-coated polymer current collectors demonstrated 100% success in thermal runaway prevention during nail penetration, retaining a cell voltage >4.00 V, while standard cells consistently experienced thermal runaway. Polymer current collectors prevented thermal runaway in Li-ion 18650 cells abuse Operando high-speed X-ray radiography evaluation of nail-penetration abuse experiments Post-mortem 3D X-ray CT has been applied for visual analysis of the cells after abuse The mechanism of short-circuit isolation in novel current collectors has been explained Most instances of thermal runaway in lithium-ion batteries stem from an internal short circuit. One approach to reducing risk of thermal runaway is isolation of internal short circuits as soon as they occur. Pham et al. describe a current collector that consists of metal coated onto a polymer substrate that can isolate internal short circuits and consistently prevent thermal runaway during mechanical abuse.