External Short Circuit of Lithium‐Ion Battery After Low Temperature Aging

Lithium‐ion battery is important to proliferation of green energy and the solution to environmental pollution. However, safety is always one issue to be solved during its usage. External short circuit (ESC) is a common abuse. Battery aging at low temperature decreases thermal stability of battery. This article studies the ESC behavior and mechanism change of lithium‐ion battery after cycling at low temperature. The results indicated that battery aging at low temperature is mainly caused by lithium plating and cathode degradation. Lithium plating grows more and cathode decays more serious after state of health (SOH) of battery less than 90% SOH. The results of ESC indicate that Joule heat from polarization resistance account for the most heat generation after ESC. Shutdown of battery is caused by separator shrink and micro internal short circuit. Although micro internal short circuit occurs, thermal runaway does not occur for fresh battery. However, thermal runaway occurs to aged battery. The safety of aged batteries decreases much more after SOH of battery less than 90%. This is related to more lithium plating and more serious degradation of cathode materials. The results are important for thermal runaway prevention of aged battery.