LBM prediction of effective thermal conductivity of lithium-ion battery graphite anode

Study of thermal characteristics of a lithium-ion battery plays a vital role in determining and enhancing the performance and safety of the battery. This paper predicts the effective thermal conductivity of a graphite anode having microstructure reconstructed by an ellipsoid based simulated annealing method. A lattice-Boltzmann (LB) model is established for simulating the thermal diffusion process in the computer-generated 3D microstructure of graphite anode. The effective thermal conductivities derived from LB simulation results indicate evident anisotropic feature of the graphite anode. The numerical results show that the particle size does have some effects on the effective thermal conductivity, but the effects are generally not significant. The real graphite may have particles with particle size following a certain statistical distribution, very probably the normal distribution, which is found to weaken the anisotropy of the electrode. Comparing the numerical data with the theoretical predictions by effective media theory (EMT) suggests that the suitable value of the empirical correction factor (f) for the effective thermal conductivity of graphite anode in the electrode through-plane direction is about 6.0 and in the other direction about 4.5.