Thermal-Electrochemical Coupled Simulations for Cell-to-Cell Imbalances in Lithium-Iron-Phosphate Based Battery Packs

磷酸鋰鐵電池具有高能量密度、無記憶效應與極低之自放電率等優點，適用於電動車及各種儲能系統。本研究根據質量守恆、電荷守恆、電化學反應機制與能量守恆等方程式建構之熱電化學耦合模型，藉以模擬磷酸鋰鐵電池於不同電流下之性能。同時考量多電芯串並聯下，搭接銅板上電流分布與焦耳熱生成之影響。並進一步利用 MATLAB, 2010 建立耦合於COMSOL Multiphysics, 2014負責模組間參數傳遞之管理流程，計算個別電芯對於溫度與電化學之響應。模擬所得之電位與溫度分布結果與相對應之實驗量測進行比較驗證。此電化學耦合模型可進一步應用於模擬溫度與電流分布不均對於磷酸鋰鐵電池組性能之影響。本研究所建立之磷酸鋰鐵電池組於放電過程中熱生成與溫昇預測模型，將有助於電池組配置設計、充放電控制、與熱管理。Lithium-iron-phosphate (LFP) battery is one of the ideal energy storage devices owing to its outstanding characteristics such as high power output, no memory effect, and only a small degree of self-discharge over time. Thermal-electrochemical coupled analysis considering mass balance, charge balance, reaction kinetics, and energy balance is further adopted to evaluate discharge behaviors of the cell. Current distribution and joule heat generation of copper alloy sheets connecting several cells are also considered in the simulation. Values of material parameters employed in the thermal-electrochemical model are acquired from experimental measurements and previous studies. A running management built in MATLAB, 2010 is applied to deliver the coupling parameters of the thermal-electrochemical model such as operating current, heat generation and temperature of the battery cells connected in various configurations among different modulus of COMSOL Multiphysics, 2014. Calculation results of the voltage and temperature distributions of the individual cell are validated by the corresponding experiments. The developed model is further applied to study the effect of non-uniform temperature distribution and pack electrical imbalance among cells within the 4S6P LFP battery pack. Simulation results can facilitate the understanding of the electrical imbalance and assist the thermal management of the LFP battery pack