Supplementary information files for "Insights Into Lithium‐Ion Battery Cell Temperature and State of Charge Using Dynamic Electrochemical Impedance Spectroscopy"

Supplementary files for article "Insights into lithium‐ion battery cell temperature and state of charge using dynamic electrochemical impedance spectroscopy"<br><br>Understanding and accurately determining battery cell properties is crucial for assessing battery capabilities. Electrochemical impedance spectroscopy (EIS) is commonly employed to evaluate these properties, typically under controlled laboratory conditions with steady‐state measurements. Traditional steady‐state EIS (SSEIS) requires the battery to be at rest to ensure a linear response. However, real‐world applications, such as electric vehicles (EVs), expose batteries to varying states of charge (SOC) and temperature fluctuations, often occurring simultaneously. This study investigates the impact of SOC and temperature on EIS in terms of battery properties and impedance. Initially, SSEIS results were compared with dynamic EIS (DEIS) outcomes after a full charge under changing temperatures. Subsequently, DEIS was analysed using combined SOC and temperature variations during active charging. The study employed a commercial 450 mAh lithium‐ion (Li‐ion) cobalt oxide (LCO) graphite pouch cell, subject to a 1C constant current (CC)–constant voltage (CCCV) charge for SSEIS and CC charge for DEIS, with SOC ranging from 50% to 100% and cell temperatures from 10 to 35°C. The research developed models to interpolate battery impedance data, demonstrating accurate impedance predictions across operating conditions. Findings revealed significant differences between dynamic data and steady‐state results, with DEIS more accurately reflecting real‐use scenarios where the battery is not at equilibrium and exhibits concentration gradients. These models have potential applications in battery management systems (BMSs) for EVs, enabling health assessments by predicting resistance and capacitance changes, thereby ensuring battery cells’ longevity and optimal performance.<br><br>© The Author(s), CC BY-4.0

《基于动态电化学阻抗谱解析锂离子电池电芯温度与荷电状态》论文补充材料

准确理解并精准测定电池电芯性能，是评估电池整体性能的关键前提。电化学阻抗谱（Electrochemical Impedance Spectroscopy, EIS）常被用于评估此类性能，但其常规应用多依托实验室受控环境下的稳态测量手段。传统稳态电化学阻抗谱（Steady-State Electrochemical Impedance Spectroscopy, SSEIS）要求电池处于静置状态，以保证测试信号呈现线性响应特性。然而，在电动汽车（Electric Vehicle, EV）等实际应用场景中，电池往往同时面临荷电状态（State of Charge, SOC）波动与温度变化的双重影响。本研究围绕SOC与温度对电池性能及阻抗的作用，探究二者对EIS测试结果的影响机制。研究初期，先对比了满电状态下不同温度时SSEIS与动态电化学阻抗谱（Dynamic Electrochemical Impedance Spectroscopy, DEIS）的测试结果；随后，针对充电过程中SOC与温度同步变化的动态场景，对DEIS数据展开分析。本次实验采用商用450 mAh锂离子（Lithium-ion, Li-ion）钴酸锂（Cobalt Oxide, LCO）-石墨软包电芯，SSEIS测试采用1C恒流-恒压（Constant Current-Constant Voltage, CCCV）充电制度，DEIS测试则采用1C恒流（Constant Current, CC）充电制度，测试覆盖的SOC区间为50%~100%，电芯温度区间为10~35℃。本研究构建了用于拟合电池阻抗数据的插值模型，可在全运行工况下实现高精度的阻抗预测。研究结果表明，动态测试数据与稳态测试结果存在显著差异，DEIS更能贴合电池非平衡、存在浓度梯度的实际使用场景。上述模型可应用于电动汽车电池管理系统（Battery Management System, BMS），通过预测阻抗与容抗的变化实现电池健康状态评估，进而保障电芯寿命与最优运行性能。

© 作者，CC BY-4.0 许可