Computer simulation of the negative electrode operation in lithium ion battery: Galvanostatics, the problem of calculating working parameters

Abstract

The work of the negative electrode (anode) of a lithium-ion battery operating in the galvanostatic discharge mode is simulated. Attention was focused on formulating the complete mathematical description of processes occurring on the anode. The most serious complication is associated with taking into account the diffusion limitation arising at the extraction of lithium atoms from grains of the active substance (intercalating agent). The analytical relationship is found between the average lithium concentration in the intercalator grain and the lithium concentration on the contact surface between the intercalator grains and the electrolyte grains. Algorithms of computer-assisted calculations are developed that allow the anode characteristics to be found. The following anode working parameters are determined: the active layer thickness, the complete discharge time, the specific electric capacity, and the final potential at the active layer/interelectrode space boundary. Calculations of the working parameters are carried out in the following two versions: for anodes with a thin active layer (imitation of processes occurring in an individual intercalator grain) and for anodes with the active layer of the optimal thickness. The procedure of selecting the reasonable discharge current, i.e., its maximum value at which virtually all lithium atoms can be removed from the active intercalator grain, is shown.