Modeling of Lead-Acid Battery Grid Geometry by Comsol Multiphysics

摘要

The lead-acid battery is a reversible battery used in generally automotive industry. A cell of lead-acid battery contains a positive and a negative electrode coated with the active material, an electrolyte, and a separator. A cell gives 2 Volts. Electrode transmits current with electrons whereas electrolyte transmits current with ions. A grid is a solid electrode called as a current collector. It has a lug located usually top of the grid frame. Strap connecting the lugs where is on the negative and positive electrodes transmits and collects the current. An electrolyte consists of sulfuric acid that carries ions. A grid is affected by some parameters while conducting current. The parameters can be the conductivity of grid material, grid shape, internal resistance, thickness, temperature, and active material mass. In order to obtain uniform current and potential distribution on a grid, a test setup is needed, but it can be expensive and also more time is required. Thus, a grid model can be developed to understand current and potential behavior on the grid by saving cost and time before manufacturing. The aim is to improve the shape of the grid of the most commonly used in lead-acid battery in order to obtain the more uniform distribution of the current and potential. Additionally, when the current and potential drop are obtained at a minimum, it makes its performance more efficient. 3D mathematical grid models have been designed with Comsol Multiphysics to estimate the behavior of the grid under certain conditions so as to save time and cost. In this model, firstly, five electrodes have been made with pasted active material and by adding electrolyte part adjacent to the electrode. Later, the models have been run by considering the thermodynamics behaviors of the grid, and then the optimum grid design and optimum active material mass have been found. In the literature, some grid geometries have been calculated by considering with the porous material and without porous material, however; we also have been developed a 3D lead-acid cell by adding porous electrode shapes modeled and drawn by us to understand grid geometry effect on whole lead acid battery cell. In conclusion, the 3D mathematical model of the lead-acid battery has been simulated by taking into account the thermodynamic and kinetic effects of the battery under certain conditions in order to measure the effect of the obtained grid geometries on the performance of the battery.