电极界面微观结构对固态锂离子电池性能的影响  

Effect of electrode interface microstructure on the performance of solid-state lithium-ion battery

作　　者：郝增辉 刘训良 孟缘 孟楠 温治 HAO Zenghui;LIU Xunliang;MENG Yuan;MENG Nan;WEN Zhi(School of Energy and Environmental Engineering,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学能源与环境工程学院,北京100083

出　　处：《储能科学与技术》2023年第7期2095-2104,共10页Energy Storage Science and Technology

基　　金：国家自然科学基金项目(52076012)。

摘　　要：为了研究固态电解质(SE)孔隙率、裂纹形式以及界面接触面积对于固态电池(SLIB)的影响,利用电阻网络方法对固态电解质(SE)微观结构建模,对SLIB采用一维电化学耦合接触面积模型,建立了一维电化学与二维固态电解质电阻网络模型,并基于该物理模型进行了电化学阻抗谱(EIS)仿真分析。通过不同几何模型来表示电解质缺陷和裂纹,用电阻网络模型计算得到离子电导率,将不同的电解质电导率输入到电池模型中,预测微观结构对于电池容量以及阻抗的影响。研究结果表明,在0°~90°范围内,裂纹角度越小,对SE的电导率影响越小;为了更方便对比裂纹形状对电导率的影响,保持裂纹面积保持不变,随着裂纹长度的生长,电导率损失逐渐上升,到达极值点后,随裂纹长度增加,电导率损失开始下降;裂纹无量纲长度小于0.25时,三角形裂纹造成的电导率损失低于矩形缺陷和椭圆形缺陷;而无量纲长度大于0.25时,三角形缺陷的影响超过矩形缺陷和椭圆形缺陷;随孔隙率增加,SE电导率快速下降,近似呈线性关系。电解质缺陷导致电池的放电电压有所下降,在EIS仿真中体现为体相电阻增加。界面接触面积的损失对于电池容量的损失更为显著,且小倍率放电时,接触面积损失对于容量损失的影响显著低于大倍率放电时。不同接触面积(1.0、0.4)下,比容量下降60.08%,而在大倍率(50 C)时,γ=1.0、0.4时,比容量下降81.95%;倍率较小时,界面面积损失的影响相对较小。界面接触面积损失导致电荷转移阻抗增加,γ从1变化至0.2时,电荷转移阻抗增加25倍,接触面积每损失0.1,电荷转移阻抗平均增加118.60Ω。与电解质缺陷相比,界面接触面积损失导致的阻抗增加更为明显。在实际应用中,界面接触面积大于0.7,电池才能保证高容量性能。研究仿真了导致SLIB阻抗增加的电解质与界面接触因素,丰富了相关研究。This study investigated the effects of porosity,crack shape,and interface contact area of solid electrolyte(SE) on solid-state batteries(STFLIBs).We used the resistance network method to model the microstructure of SE and a one-dimensional electrochemical coupled contact area model for SLIB.We established a one-dimensional electrochemical and two-dimensional SE resistance network model based on this physical model and conducted electrochemical impedance spectroscopy(EIS) simulation analysis.By inputting different electrolyte properties into the battery model,we predicted the effect of microstructure on battery capacity and impedance.The results show that within the range of 0° ~90°,smaller crack angles have less impact on the conductivity of SE.To compare the effect of crack shape on electrical conductivity more conveniently,we kept the crack area unchanged.As the crack length increases,the electrical conductivity loss gradually increases until it reaches the extreme point after which the electrical conductivity loss starts to decrease.When the dimensionless length of the crack is 0.25,the conductivity loss caused by triangular cracks is lower than that caused by rectangular and elliptical defects.However,when the dimensionless length is 0.25,the influence of triangular defects exceeds than that of rectangular and elliptical defects.With the increase of porosity,the conductivity of SE rapidly decreases in an approximately linear manner.Electrolyte defects lead to a decrease in the discharge voltage of the battery,which is reflected in the EIS simulation as an increase in bulk resistance.The loss of interface contact area has a more significant impact on the loss of battery capacity,and this impact is significantly lower at low discharge rates compared to high discharge rates.Under different contact areas(γ = 1.0 and 0.4),the specific capacity decreases by 60.08%,while at high magnification(50 C),the specific capacity decreases by 81.95%.The impact of interfacial area loss is relatively small when the magnifica

关 键 词：固态锂离子电池 界面接触面积比值 电解质裂纹 失效机制 电化学阻抗谱模型 

分 类 号：TM911[电气工程—电力电子与电力传动]