Over-discharge Phenomenon Caused by Corona Discharge in Lithium-ion Batteries (LiB) and its Effect on Copper Dissolution from the Negative Current Collector

Abstract

Assuming that a lithium-ion battery (LiB) is left in the vicinity of a high-voltage device, we generated corona discharge in the prototype LiB and verified that over-discharge occurs. During an over-discharge test using a constant current with a similar average current (18 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mu \mathrm{A})$</tex> , the voltage did not maintain a constant value near 0 V, and a drop in voltage below -0.9 V was observed. After the test, the prototype cell was disassembled and the separator and electrodes were observed. It was found that copper dissolution from the negative current collector was hardly observed in the case of over-discharge by corona discharge However, in the case of over-discharge with constant current, copper dissolution was significant. This difference is suggested to be caused by the fact that the corona discharge current is in the form of pulses. And as a result of an over-discharge test using a pulse current of 100 kHz duty 10%, a phenomenon was observed in which the voltage remained constant around 0 V as in the case of corona discharge. Furthermore, the current distribution inside the negative porous electrode during the application of pulsed current was analyzed using a transmission line model. The current distribution in the electrodes is different for pulsed currents from constant currents. It was found that current inversion occurs through the electric double layer and the current distribution through the charge transfer resistance becomes smaller during the quiescent period of the current.