[目的]重卡换电站能解决换电重卡充电时间长,续航里程短等痛点,但其动力电池存在容量大、使用频率高、热失控风险高等问题。[方法]为解决以上问题,文章建立了耦合双向充电机的电池热-电耦合模型,对电动重卡动力电池热特性进行研究,应用C...[目的]重卡换电站能解决换电重卡充电时间长,续航里程短等痛点,但其动力电池存在容量大、使用频率高、热失控风险高等问题。[方法]为解决以上问题,文章建立了耦合双向充电机的电池热-电耦合模型,对电动重卡动力电池热特性进行研究,应用COMSOL-SIMULINK进行联合仿真。[结果]仿真结果表明:所提出耦合模型,可以有效控制电池车辆到电网(Vehicle to Grid,V2G)工况下的电压电流。在V2G工况前期,最大电流密度在负极与负极极耳的交界处,最小电流密度在正极与正极极耳的交界处,正极极耳温度比负极极耳高4.1℃;在V2G工况后期,最大局部电流密度从极耳向电池下端转移,底部区域因浓度的影响有利于电化学反应,电芯温度高于极耳温度;热滥用工况下,副反应发生顺序为SEI膜分解、负极分解、正极与电解液反应,其中,电极副反应生热是导致电池进入无法返回的热失控的主要原因,SEI膜的分解反应是电池开始热失控的标志。[结论]所提外电路-热电耦合模型能有效反映在重卡换电站双向充电机激励下,电池热电耦合模型的温度分布与热失控影响。展开更多
The aging characteristics of lithium-ion battery(LIB)under fast charging is investigated based on an electrochemical-thermal-mechanical(ETM)coupling model.Firstly,the ETM coupling model is established by COMSOL Multip...The aging characteristics of lithium-ion battery(LIB)under fast charging is investigated based on an electrochemical-thermal-mechanical(ETM)coupling model.Firstly,the ETM coupling model is established by COMSOL Multiphysics.Subsequently,a long cycle test was conducted to explore the aging characteristics of LIB.Specifically,the effects of charging(C)rate and cycle number on battery aging are analyzed in terms of nonuniform distribution of solid electrolyte interface(SEI),SEI formation,thermal stability and stress characteristics.The results indicate that the increases in C rate and cycling led to an increase in the degree of nonuniform distribution of SEI,and thus a consequent increase in the capacity loss due to the SEI formation.Meanwhile,the increases in C rate and cycle number also led to an increase in the heat generation and a decrease in the heat dissipation rate of the battery,respectively,which result in a decrease in the thermal stability of the electrode materials.In addition,the von Mises stress of the positive electrode material is higher than that of the negative electrode material as the cycling proceeds,with the positive electrode material exhibiting tensile deformation and the negative electrode material exhibiting compressive deformation.The available lithium ion concentration of the positive electrode is lower than that of the negative electrode,proving that the tensile-type fracture occurring in the positive material under long cycling dominated the capacity loss process.The aforementioned studies are helpful for researchers to further explore the aging behavior of LIB under fast charging and take corresponding preventive measures.展开更多
文摘[目的]重卡换电站能解决换电重卡充电时间长,续航里程短等痛点,但其动力电池存在容量大、使用频率高、热失控风险高等问题。[方法]为解决以上问题,文章建立了耦合双向充电机的电池热-电耦合模型,对电动重卡动力电池热特性进行研究,应用COMSOL-SIMULINK进行联合仿真。[结果]仿真结果表明:所提出耦合模型,可以有效控制电池车辆到电网(Vehicle to Grid,V2G)工况下的电压电流。在V2G工况前期,最大电流密度在负极与负极极耳的交界处,最小电流密度在正极与正极极耳的交界处,正极极耳温度比负极极耳高4.1℃;在V2G工况后期,最大局部电流密度从极耳向电池下端转移,底部区域因浓度的影响有利于电化学反应,电芯温度高于极耳温度;热滥用工况下,副反应发生顺序为SEI膜分解、负极分解、正极与电解液反应,其中,电极副反应生热是导致电池进入无法返回的热失控的主要原因,SEI膜的分解反应是电池开始热失控的标志。[结论]所提外电路-热电耦合模型能有效反映在重卡换电站双向充电机激励下,电池热电耦合模型的温度分布与热失控影响。
基金funded by the National Natural Science Foundation of China(Grant No.12272217)。
文摘The aging characteristics of lithium-ion battery(LIB)under fast charging is investigated based on an electrochemical-thermal-mechanical(ETM)coupling model.Firstly,the ETM coupling model is established by COMSOL Multiphysics.Subsequently,a long cycle test was conducted to explore the aging characteristics of LIB.Specifically,the effects of charging(C)rate and cycle number on battery aging are analyzed in terms of nonuniform distribution of solid electrolyte interface(SEI),SEI formation,thermal stability and stress characteristics.The results indicate that the increases in C rate and cycling led to an increase in the degree of nonuniform distribution of SEI,and thus a consequent increase in the capacity loss due to the SEI formation.Meanwhile,the increases in C rate and cycle number also led to an increase in the heat generation and a decrease in the heat dissipation rate of the battery,respectively,which result in a decrease in the thermal stability of the electrode materials.In addition,the von Mises stress of the positive electrode material is higher than that of the negative electrode material as the cycling proceeds,with the positive electrode material exhibiting tensile deformation and the negative electrode material exhibiting compressive deformation.The available lithium ion concentration of the positive electrode is lower than that of the negative electrode,proving that the tensile-type fracture occurring in the positive material under long cycling dominated the capacity loss process.The aforementioned studies are helpful for researchers to further explore the aging behavior of LIB under fast charging and take corresponding preventive measures.
