Impact of active material ion diffusion coefficient on overpotential in lithium-ion batteries

Simulating battery performance is crucial for effectively developing lithium-ion batteries (LIBs). However, ensuring the accuracy of the input parameters remains a significant challenge. Key parameters of active materials, including the exchange current density and ion diffusion coefficient, mutually affect each other, posing challenges for independent measurement. This study utilized single-particle measurements and battery performance simulations to evaluate the impact of the diffusion coefficient on the exchange current density in LiCoO2, the active material of LIBs. The findings revealed that diffusion coefficients below 10-8 cm2 s−1 influence the Tafel plot, representing the exchange current density. Fitting analysis of the LiCoO2 single-particle measurement by Simcenter Battery Design Studio (BDS) yielded an exchange current density of 6.6 × 10-4 A cm−2, a diffusion coefficient of 5.9 × 10-11 cm2 s−1, and a charge transfer coefficient of 0.55.