A control oriented reduced order electrochemical model considering variable diffusivity of lithium ions in solid

摘要

Recently, reduced order electrochemical models (ROMs) have been obtained more attention by industries for real-time applications. Its computational efficiency is maximized by regarding particles in electrodes as an equivalent single particle, named ROM-Single Particle Model (SPM). However, the model has a major drawback in the inaccuracy of the predicted terminal voltage, particularly at high currents. Therefore, an advanced ROM-SPM considering variable diffusivity (VD) of lithium ions in solid is proposed that significantly improves the accuracy of the terminal voltage, named as ROM-SPMVD. The model is firstly developed, and the sensitivity analysis of the parameters is performed, which reveals that the diffusivity of lithium ions in solid of cathode (D-s,D-p) is strongly sensitive and identifiable. Next, the relationship between the D-s,D-p, and state of charge (SOC) and temperature is determined by a newly developed nondestructive method. Finally, the ROM-SPMVD is validated against experimental data of a pouch type lithium ion energy cell at different current profiles and at different temperatures. Results show that consideration of variable Du leads to a significant improvement in the accuracy of the ROM-SPM at high currents while maintaining the reduced computational time. The voltage error of ROM-SPMVD is reduced up to 79% compared with that of ROM-SPM.