锂电池LixC6偏摩尔体积和弹性性质的分子动力学模拟

Molecular Dynamics Simulation of Partial Molar Volume and Elastic Properties of Li_xC_6 in Li-Ion Battery

采用分子动力学方法,建立包含库仑力的LixC6晶体模型,在应变控制加载的边界条件下,准静态数值模拟石墨嵌锂结构的变形行为,计算了300K温度下锂离子电池阳极材料LixC6的偏摩尔体积和弹性性质,给出了达到弛豫平衡时的LiC6、LiC12和LiC18的分子动力学可视化图像,显示了LixC6晶体的微观结构,表明了锂电池在充放电过程中分别在不同的时间达到阶段稳定结构.研究表明,LixC6体系的偏摩尔体积为常数,LiC6、LiC12和LiC18具有不同的弹性常数,除C11外其余弹性常数随LixC6嵌锂浓度的增大而增加.研究结果为锂电池电极变形的连续尺度模型研究提供了基础数据.

The crystal model containing Coulomb force for LixC6 was built by molecular dynamics method. The quasi-static numerical method was used to simulate the deformation of LixC6 with the boundary conditions based on strain-controlling loading. The partial molar properties and the elastic properties of the lithium-ion battery anode material LixC6 were studied at 300K. The results show the visual images of stable atomic configuration LiC6, LiC12 and LiCIs, which reveal the microstructure of LixC6. It is found that LiC6, LiC12 and LiC18 have different elastic constants. Except Cll, elastic constants rise with the increase of lithium concentrations. The polycrystaUine Young＇s modulus is also calculated to have the relationship between Young＇s modulus and lithium concentrations. The result of research provides data for the continuous model research of the lithium electrode deformation.