基于Gibbs自由能变的柱形梯度电极扩散应力研究  

Study on diffusion-induced stresses of a cylindrical composition-gradient electrode based on Gibbs free energy change

作　　者：李锦龙[1] 郑百林[1] 彭颖吒 张锴[1] LI Jin-long;ZHENG Bai-lin;PENG Ying-zha;ZHANG Kai(School of Aerospace Engineering and Applied Mechanics,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学应用力学研究所,上海200092

出　　处：《电源技术》2018年第9期1294-1297,1411,共5页Chinese Journal of Power Sources

摘　　要：柱形梯度电极是新型锂电池电极之一。考虑了应力变化对吉布斯自由能的影响,得出梯度电极材料的扩散方程与力学方程。以Li_(1.2)(Mn_(0.62)Ni_(0.38))_(0.8)O_2为例,为了讨论在恒压条件下梯度电极材料非均匀性对应力的演化影响,将电极的扩散系数、杨氏模量和偏摩尔体积三个参数视为柱坐标系下径向坐标的线性函数。结果表明,导致电极材料力学退化的环向拉应力得到了明显的降低。这项研究为降低柱形梯度电极材料的扩散应力提供了有用的理论指导。The novel cylindrical composition-gradient electrode is considered to be one of the potential structure in lithium ion batteries.Both diffusion equation and mechanics equations of a cylindrical composite-gradient electrode are derived.The contribution of the work of the stress to Gibbs free energy change is caused by diffusion and reaction of the lithium ion during the charge-discharge,which is considered as an irreversible process.In order to discuss the effects of inhomogeneous on stress distribution in lithium batteries under potentiostatic operation in composition-gradient electrodes,the three main material parameters of diffusion coefficient,Young's modulus,partial molar volume of solute are assumed to be the linear function of radial coordinate analogy to Li1.2(Mn0.62Ni0.38)0.8O2.The results indicate that tensile stress in composite-gradient electrode,which may lead to mechanical degradation in the electrode material in lithium ion batteries,is greatly reduced.It also provides useful guidance for mitigating the stresses in a cylindrical electrode.

关 键 词：扩散诱导应力 梯度电极 柱形 吉布斯自由能 

分 类 号：TM912[电气工程—电力电子与电力传动]