Co-estimating the state of charge and health of lithium batteries through combining a minimalist electrochemical model and an equivalent circuit model

• Published in: Energy (Oxford) Vol. 240; p. 122815
• Main Authors: Xu, Zhicheng, Wang, Jun, Lund, Peter D., Zhang, Yaoming
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2022; Elsevier BV
• Subjects: Electric vehicles; Electrochemistry; energy; Energy storage; Equivalent circuit model; Equivalent circuits; Estimation; Kalman filters; Lithium; Lithium batteries; Lithium-ion batteries; Lithium-ion battery; management systems; Minimalist electrochemical model; Parameter identification; Product safety; Rechargeable batteries; State of charge; State of health; Storage systems; System effectiveness; Lithium-ion battery; State of charge; Equivalent circuit model; State of health; Minimalist electrochemical model
• ISSN: 0360-5442; 1873-6785; 1873-6785
• DOI: 10.1016/j.energy.2021.122815

Accurate estimation of the state of charge (SOC) and state of health (SOH) is a fundamental requirement for the management system of a lithium-ion battery, but also important to the safety and operational effectiveness of electric vehicles and energy storage systems. Here a model-based method is implemented to assess the SOC and SOH simultaneously. An equivalent circuit model is employed to describe the battery dynamics with recursive least squares online identifying model parameters and unscented Kalman filter estimating battery state. A minimalist electrochemical model is proposed to describe the distribution of the lithium content inside the battery relating the SOH to the capacity fading due to irreversible loss of Li. Based on the real-time capacity value, the state of charge could further be estimated. Comparing the experimental results shows that the battery capacity, i.e., SOH could be predicted timely with a mean error around 2%, which confirms the validity of the proposed co-estimation method for SOC and SOH. •Method for co-estimating the SOC and SOH in lithium-ion battery.•Minimalist electrochemical model for simulating the distribution of lithium.•SOH is related to capacity fade through irreversible loss of lithium.•The accuracy of the method for estimating SOC and SOH is very good.