Improving battery safety by early detection of internal shorting with a bifunctional separator

Abstract

Lithium-based rechargeable batteries have been widely used in portable electronics and show great promise for emerging applications in transportation and wind-solar-grid energy storage, although their safety remains a practical concern. Failures in the form of fire and explosion can be initiated by internal short circuits associated with lithium dendrite formation during cycling. Here we report a new strategy for improving safety by designing a smart battery that allows internal battery health to be monitored in situ. Specifically, we achieve early detection of lithium dendrites inside batteries through a bifunctional separator, which offers a third sensing terminal in addition to the cathode and anode. The sensing terminal provides unique signals in the form of a pronounced voltage change, indicating imminent penetration of dendrites through the separator. This detection mechanism is highly sensitive, accurate and activated well in advance of shorting and can be applied to many types of batteries for improved safety.

Study of the Mechanisms of Internal Short Circuit in a Li/Li Cell by Synchrotron X-ray Phase Contrast Tomography

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] For example, the most promising Li metal-based battery technologies such as lithium-sulphur and lithium-air batteries have not been successfully commercialized mainly because of the uncontrolled growth of lithium microstructures (LmSs) such as dendrites, fibers, whiskers, moss, etc., which can cause internal short circuit (ISC) of a cell and result in catastrophic fires or even explosions. [15][16][17] Recent field incidents such as fires on a Boeing 787 Dreamliner flight and in a Tesla electric vehicle (EV) or even in the Samsung Note 7 smartphone are believed to be closely linked to ISCs in LIBs. [18][19][20] Furthermore, the soaring number of EVs in use additionally adds tremendous weight to safety and reliability in presentand next-generation LIB technology.…”

Smart Electrochemical Energy Storage Devices with Self‐Protection and Self‐Adaptation Abilities

“…For example, internal battery health was in situ monitored with the aid of a novel bifunctional separator reported by Wu et al [29] In comparison to traditional battery separators, which are insulating polymer layers with porous structures, the bifunctional separator was in a polymer-metal-polymer triple layer configuration (Figure 1a,b). The incorporated conducting metal intermediary layer offers an additional voltage sensing terminal, so that the extent of dendrite growth can be indicated by the voltage value between the intermediary layer and the negative electrode.…”

“…[24] Different from the multifunctional devices fabricated by integrating several independent functional modules, [25][26][27] delicate designs have been developed to confer innate intelligence onto these advanced devices, including in situ safety monitoring, realtime display of energy storage level, and self-protection capabilities. [28][29][30][31][32] In order to cope with external mechanical damage, self-healing supercapacitors and batteries have been successfully fabricated, and could improve the reliability and lifetime of these devices. [33,34] Moreover, to avoid the irreversible recovery of flexible energy storage devices caused by deformation over time, shape-memory supercapacitors have also been developed.…”

Review—Post-Mortem Analysis of Aged Lithium-Ion Batteries: Disassembly Methodology and Physico-Chemical Analysis Techniques

“…64 Some groups studied Li deposition and dendrite formation during the charging process in situ by optical microscopy. 96,[103][104][105][106][107][108][109] Furthermore, color changes in graphite 96 and rutile 110 electrodes were monitored in situ by optical microscopes.…”