Preventing lithium ion battery failure during high temperatures by externally applied compression

Abstract

Lithium-ion cells can unintentionally be exposed to temperatures outside manufacturers recommended limits without triggering a full thermal runaway event. The question addressed in this paper is: Are these cells still safe to use? In this study, externally applied compression has been employed to prevent lithium ion battery failure during such events. Commercially available cells with Nickel Cobalt Manganese (NCM) cathodes were exposed to temperatures at 80 °C, 90 °C and 100 °C for 10 h, and electrochemically characterised before and after heating. The electrode stack structures were also examined using x-ray computed tomography (CT), and post-mortems were conducted to examine the electrode stack structure and surface changes. The results show that compression reduces capacity loss by −0.07%, 4.95% and 13.10% respectively, measured immediately after the thermal testing. The uncompressed cells at 80 °C showed no swelling, whilst 90 °C and 100 °C showed significant swelling. The X-ray CT showed that the uncompressed cell at 100 °C suffered de-lamination at multiple locations after test, and precipitations were found on the electrode surface. The post-mortem results indicates the compressed cell at 100 °C was kept tightly packed, and the electrode surface was uniform. The conclusion is that externally applied compression reduces delamination due to gas generation during high temperature excursions

Online internal short circuit detection method considering equalization electric quantity for lithium‐ion battery pack in electric vehicles

“…(2) according to the difference between the cell voltage and the minimum voltage, the equalizer is controlled. For example, if the voltage difference between the cell i and the cell with minimum voltage (V min ) is greater than the threshold value (ie, 0.1 V), then the switch S i is closed, and the equalization current of the cell i can be obtained by Equation (11), while the EEQ can be obtained by the Equation (12). (3) When the voltage difference between cells is reduced to a certain extent (ie, 20 mV) or the equalization opening time is more than 5 hours, the equalization is stopped.…”

“…[7][8][9] To further improve the operational range of EVs, LIBs are being developed to have higher energy densities 9,10 ; however, in case of an accident, the significant energy release can cause severe damage. 11,12 In recent years, EV ignition accidents caused by thermal runaway of LIBs have occurred frequently; hence, LIB safety has attracted considerable attention globally. [13][14][15] An internal shortcircuit (ISC) commonly causes LIB thermal runaway; the process from an ISC to thermal runaway required a specific amount of time.…”

“…Lithium‐ion batteries (LIB) are widely used in EVs and energy storage industries due to their high energy and power density, 6 long lifespan, high efficiency, and low self‐discharge 7‐9 . To further improve the operational range of EVs, LIBs are being developed to have higher energy densities 9,10 ; however, in case of an accident, the significant energy release can cause severe damage 11,12 . In recent years, EV ignition accidents caused by thermal runaway of LIBs have occurred frequently; hence, LIB safety has attracted considerable attention globally 13‐15 .…”

Numerical Simulation of Manifold Microchannel Heat Sinks for Thermal Management in a Li‐Ion Battery

“…Li‐ion batteries often work at high temperatures for a long time due to poor thermal management during operation. At high temperatures, a Li‐ion battery degrades rapidly 5, damaging the battery and shortening its service life. When the temperature is lower than the operating temperature range, the internal resistance of the battery increases, thus raising the internal voltage of the battery and the load characteristics become worse.…”

How to Cool Lithium Ion Batteries: Optimising Cell Design using a Thermally Coupled Model

“…thermal runaway. [2][3][4][5][6][7][8] To counter these challenges, the temperature of the EV battery pack is normally managed by using thermal management system (TMS). [9][10][11][12][13][14] The main purpose of the TMS is to maintain the overall temperature in an optimal window as well as maintain a uniform temperature between cells and within the cells.…”