Current Distribution Analysis in Porous Electrode of Lithium-ion Battery by Transmission Line Model under High Voltage Signal Application

Abstract

In recent years, lithium-ion batteries (LiB), which represent energy storage devices, have been introduced into electric vehicles and power leveling. In power leveling, LiB may be connected to the power grid. In such cases, the possibility of high voltage pulses, such as induced lightning, being applied to LiB must be considered. However, the effects of high voltage pulses on LiB have not been studied or analyzed academically. We analyzed the effects of sine wave pulse application tests on prototype LiB and computational simulations of the current distribution in the porous electrode on LiB. A distributed constant circuit model simulating the structure of a porous electrode was used for the simulation. In the sinusoidal pulse application test, a function generator and a four-quadrant bipolar power supply were used to apply a sinusoidal pulse voltage of one wavelength to a prototype LiB multiple times. Although it was expected that the pulse application would significantly reduce the capacity of LiB. The effect on the capacity reduction was actually small. An equivalent circuit of a LiB porous electrode was also created, and the current and voltage distributions across the electrode’s charge-transfer resistance were analyzed when a step voltage of 100 V was applied to the positive and negative electrodes. The charge transfer resistance on the equivalent circuit was assumed to be a variable resistance based on the Butler-Volmer equation. The voltage distribution indicated that although 100 V was applied to the electrolyte-electrode system, only 0.7 V was applied to the charge transfer resistance of the positive electrode and 0.45 V to the charge transfer resistance of the negative electrode. This suggests that the reason the battery capacity did not decrease significantly when AC pulses were applied was because the voltage applied to the electrode active material did not reach the decomposition voltage of the active material.