SOC-Aware Thermal Runaway Modeling for Lithium-Ion Batteries
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Solution Overview
Problem
Existing thermal runaway models for lithium-ion batteries do not adequately consider the change in state of charge (SOC) during charging and discharging, leading to inaccuracies in predicting thermal runaway characteristics.
Innovation Solution
A modeling method is developed to establish a thermal runaway-electrochemical coupling model by integrating a three-dimensional thermal runaway model with a one-dimensional electrochemical model, using energy conservation equations and heat transfer coefficients to account for SOC changes, and defining SOC based on lithium concentration ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a thermal runaway model is established without considering SOC changes during charging and discharging, then the model structure is simpler, but the prediction accuracy of thermal runaway characteristics deteriorates
Solution Approach 1:
The patent applies parameter changes by incorporating SOC as a dynamic parameter in the thermal runaway model. The model equations include SOC-dependent terms such as the heat generation rate q_gen = Q·(dSOC/dt) and the Arrhenius reaction rate k = A·exp(-Ea/RT) which varies with SOC. This allows the model to adapt thermal runaway predictions to different charging and discharging states, resolving the contradiction between model simplicity and prediction accuracy.
2Measurement precision
If a thermal runaway model considering SOC changes is established, then the prediction accuracy of thermal runaway characteristics is improved, but the coupling complexity between thermal and electrochemical models increases
Solution Approach 1:
The patent uses temperature T as an intermediary variable to couple the thermal runaway model with the electrochemical model. The thermal model provides temperature evolution that drives the electrochemical reactions, while the electrochemical model provides heat generation that feeds back to the thermal model. This intermediary coupling approach achieves accurate SOC-dependent predictions while managing model complexity through a clear cause-effect relationship.
Solution Approach 2:
The patent merges the thermal runaway model and electrochemical model into a unified coupled system. The governing equations are integrated such that the energy conservation equation includes both thermal conduction terms and electrochemical heat generation terms. This merging allows the models to work together synergistically, improving prediction accuracy while avoiding the need for separate independent analyses.
3Measurement precision
If extensive experimentation is conducted to establish accurate thermal runaway models under different SOC conditions, then the model accuracy is improved, but the time and resource consumption increases
Solution Approach 1:
The patent applies preliminary action by establishing the coupled thermal-electrochemical model framework in advance, with all necessary governing equations and parameter relationships defined beforehand. The model structure预先 incorporates SOC dependence through the electrochemical reactions, eliminating the need for separate experiments at each SOC level. This preliminary model development allows rapid prediction of thermal runaway characteristics under any SOC condition without extensive repeated experimentation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The model accurately predicts battery temperature changes from normal operation to thermal runaway, reducing the need for extensive experimentation and providing precise thermal runaway risk analysis under varying conditions.
Implementation Method 1
The one-dimensional electrochemical model describes lithium ion diffusion and electrochemical reactions inside the battery
Implementation Method 2
The one-dimensional electrochemical model describes lithium ion diffusion and electrochemical reactions inside the battery
Implementation Method 3
generating heat through irreversible reactions
Implementation Method 4
The three-dimensional thermal runaway model focuses on heat conduction and exothermic chemical reactions
Implementation Method 5
The three-dimensional thermal runaway model focuses on heat conduction and exothermic chemical reactions
Data Source
AI summary
The present invention relates to a modeling method for a thermal runaway-electrochemical coupling model for a change in state of charge of a lithium-ion battery during charging and discharging, and belongs to the technical field of safety of lithium-ion batteries. The method includes the following steps: S1: establishing a three-dimensional thermal runaway model of the battery under different states of charge; S21: assembling half-cells of battery cathode and anode materials; S22: testing equilibrium potentials and entropy thermal coefficients of a cathode and an anode; S23: acquiring a heat transfer coefficient between a battery surface and an ambient temperature; S24: measuring temperature and voltage change curves of the battery; S25: establishing an electrochemical model plugging electrochemical parameters into the model to obtain simulation results, and comparing the simulation results with real experimental results; and S3: making the temperatures in the electrochemical model to be consistent with an average temperature in the three-dimensional thermal runaway model under different states of charge for coupling, and setting restriction conditions after coupling. The method can achieve coupling of the thermal runaway model for the change in state of charge and electrochemistry, and can explore the thermal runaway phenomenon of batteries more comprehensively.