Research on Simplification of Simulating the Heat Conduction in the Lithium-ion Battery Core

This paper discusses the model simplifing issue in battery thermal simulation. The paper verifies that for the large power battery simplifying the multilayer battery core as a lumped cuboid is reasonable. So when doing simulation, building a multilayer core is unnecessary. And the calculation cost can be reduced by the lumped model. Specific power battetry of 70Ah is dissembled to be modeld. Thermal models of are established, including models with a lumped core and with multilayer cores. For the lumped core, the anisotropic thermal conductivities are got by equations calculating series and parallel equivalent thermal conductivity. While for the multilayer core models, the core contains numbers of unit cells and the volume of which is equal to that of the lumped. In addition, under the boundary conditions of inner heat source and surface heating, steady state simulations are performed. Simulation results indicate that the temperature distributions of the lumped model and the multilayer model are almost the same. For one thing, large number of multilayers and low shell thermal conductivity contribute to a uniform temperature distribution within the core, so it is reasonable to simplify the multilayer core as a lumped cuboid. For another, due to the size of the battery and the shell property, it is difficult to find a simple curve to fit the simulation temperature on the battery surface. Although minor differences still exist, the lumped core can well subsitute the multilayer core in battery thermal simulation.