Accurate modeling of sodium-ion batteries (SIBs) plays a vital role in the optimal development of the battery management system (BMS). In this study, the equivalent circuit models (ECMs) with different resistance-capacitance (RC) numbers are thoroughly investigated. The relationship between circuit parameters and state of charge (SOC) is modeled as polynomial functions. The Bayesian information criterion is used to assist in optimal model selection by balancing the trade-off between model accuracy and model complexity. Two typical types of operation conditions, i.e. hybrid pulse power characterization/dynamic stress tests and constant current discharge tests, are conducted to evaluate the model performance. Both fitting and prediction results demonstrate that the ECMs with three-RC network can describe the terminal voltage response of a 1 Ah pouch-type SIB. The accurate modeling strategy provides a promising tool to state monitoring and control in BMS.

钠离子电池 (SIB) 的准确建模在电池管理系统 (BMS) 的优化开发中起着至关重要的作用。在这项研究中，彻底研究了具有不同电阻电容 (RC) 数的等效电路模型 (ECM)。电路参数和荷电状态 (SOC) 之间的关系被建模为多项式函数。贝叶斯信息准则用于通过平衡模型准确性和模型复杂性之间的权衡来帮助优化模型选择。两种典型的运行条件，即混合脉冲功率特性/动态应力测试和恒流放电测试，被用来评估模型的性能。拟合和预测结果均表明具有三 RC 网络的 ECM 可以描述 1 Ah 袋型 SIB 的端电压响应。准确的建模策略为 BMS 中的状态监测和控制提供了一种很有前途的工具。