All-climate state-of-charge estimation and equilibrium management for lithium-ion batteries based on diffusion equivalent model

All-climate application of lithium-ion batteries is of crucial importance for future promotion on transportation and energy storage, which is still suffering from the unprecise model and algorithms. In this article, a coupled diffusion-equivalent circuit model is proposed for solving the problems of all-climate and multi-conditional battery modeling, which is developed based on simplified electrochemical theories. And the simplex sphere-radial particle filter is introduced for delivering the precise method on the estimation for state of charge according to rigorous mathematical demonstration. Moreover, the equilibrium system is established based on original battery management system, and both cell-level and module-level experiments are carried out for validating the effectiveness and precision of proposed method. Maximum error of no more than 3% can be observed both for all-climate (between −20 °C–45 °C) and large depth of discharging, and 1% inconsistency can be achieved within sufficient balancing. The satisfactory results confirm that the proposed method can perform an accurate and robust solution for online state of charge estimation, and deliver great potential on future promotion for energy storage system or remote cloud-controlling system.