Electrochemical impedance characteristics at various conditions for commercial solid–liquid electrolyte lithium-ion batteries: Part 1. experiment investigation and regression analysis

Solid–liquid electrolyte lithium-ion batteries (SLELBs) have good commercial viability in electric vehicle applications because they combine the safety of solid electrolyte lithium-ion batteries with the high ionic conductivity of liquid electrolyte lithium-ion batteries (LELBs). The safe and efficient operation of electric vehicles is inseparable from the key battery management algorithms such as battery state of charge (SOC), state of health and state of power estimation. In the process of designing the battery management algorithms for SLELBs, it is essential to have an accurate understanding of battery behavior under different influencing factors and build a high-fidelity battery model. Electrochemical impedance spectroscopy (EIS) can be used to study the electrode process dynamics and ion transport mechanism in lithium-ion batteries. However, it can be a huge challenge to use EIS to experiment and analyze the characteristic impedances of SLELBs under the full-scale factors, and to construct the battery model and simulate the battery impedance under the premise of a reasonable number of tests. Over a series of two papers, we first propose a regression model of temperature and SOC One-Way factor SLELB characteristic impedances through full-scale experimental design under the theoretical framework of experimental optimization design and statistical analysis. Then, in order to construct the model under the premise of a reasonable number of tests, the orthogonal experiment is designed, and the orthogonal piecewise polynomial Arrhenius - simplified equivalent circuit model for SLELB impedance prediction of the Two-Way factor of temperature and SOC is established. These models can accurately describe SLELB behavior under different factors, improve the understanding of the SLELB electrode process, and predict the impedance spectrum of SLELB, support the key battery management algorithms. In this first paper, EIS is used to analyze the electrode process kinetics of Li7La3Zr2O12 SLELBs at different temperatures and SOCs in a full-scale experimental design. Furthermore, the characteristic impedances in the EIS are identified to facilitate a systematic analysis of the battery performance. The Arrhenius model and polynomial model are used to perform the regression analysis of temperature and SOC One-Way factor SLELB characteristic impedances. Experimental results show that these models can achieve a high precision regression for One-Way factor characteristic impedances.