硅功能化石墨烯负极材料的最优化初始构形

The optimum initial configuration of silicon functionalized graphene

硅功能化石墨烯作为锂离子电池的阴极材料,其最优化的初始构形会提高电池的可逆容量、充放电速率和使用寿命.文中应用分子动力学方法,采用Tersoff势函数与LJ势函数,结合速度形式的Verlet算法,对硅功能化石墨烯进行了弛豫和拉伸等力学性能模拟,提出了材料最优化的构形.通过对不同硅原子分布、不同硅碳比、不同空位缺陷率、不同拉伸速度和不同温度对材料的体积、势能、弹性模量、拉伸应变、强度等性能的影响进行了模拟.研究表明,硅原子随机分布时的系统势能最大,体积变化介于横向分布和交叉分布之间,模型的力学性能参数也最高;硅原子数目越多,模型表面褶皱越明显,系统的势能越低,体积也越大;当硅碳比为3.28%时,力学性能参数最大;空位缺陷率越大,模型系统势能越高,体积越大;当缺陷率为1%时,材料的力学性能参数最高;力学性能参数随着拉伸速率和拉伸温度的变大而减小;当速率为0.5 nm·s^(-1),温度为300 K时,材料的力学性能最好.

As the cathode material of Li-ion batteries,the optimized initial configuration of silicon-functionalized graphene can improve the reversible capacity,charging and discharging speed and service life of the batteries.In this paper,the mechanical properties of silicon-functionalized graphene are simulated by using the molecular dynamics method with Tersoff potential,the LJ potential and the velocity Verlet time stepping algorithm.The effects of different silicon atom distribution,different silicon-carbon ratio,different vacancy defect rate,different tensile velocity and different temperature on material volume,potential energy,elastic modulus,tensile strain and strength were simulated.It is found that:the system potential energy is the maximum when silicon atoms are randomly distributed,and the volume change is between the transverse distribution and the cross distribution,and the mechanical property parameters of the model are also the highest;the higher of the number of silicon atoms,the more of the model surface folds,the lower of the system potential energy,and the larger of the volume;the larger of the vacancy defect rate,the higher of the potential energy of the model system and the larger of the volume.When the defect rate is 1%,the mechanical property parameters of the material are the highest;the mechanical property parameter decreases with the maximum stretching rate and temperature.When the rate is 0.5 nm ·s^-1 and the temperature is 300 K,the mechanical property of the material is the best.