苯甲酸钠改性石墨作为锂离子电池负极材料的性能（英文）

Characterization of Graphite Modified with Sodium Benzoate as Anode Material for Lithium Ion Battery

将不同浓度的苯甲酸钠改性的石墨电极作为锂离子电池的负极备用材料,并使用恒流充放电、循环伏安和交流阻抗等电化学方法表征电池的性能。结果表明,与初始的石墨电极相比,被改性后的石墨电极表现出更好的循环效率和稳定性,且在0.5C条件下,首次的充放电比容量分别为293.9mAh/g和326.4mAh/g。主要原因是改性后的石墨电极的表面形成的SEI膜能有效抑制石墨材料的膨胀,并且更有利于锂离子的迁移。同时,采用量子化学方法计算了溶剂分子和苯甲酸钠的最低空轨道和最高占据轨道能量值。结合电化学表征和量子计算结果,苯甲酸钠改性石墨电极的最佳浓度为1.0%。此外,还研究了最佳浓度改性石墨电极的高温性能。

Graphite electrode was modified with different concentrations of sodium benzoate（C_7H_5O_2 Na）solutions for application as an anode material for lithium ion battery.The electrochemical characterization of graphite modified with sodium benzoate was carried out by galvanostatic charge/discharge test,electrochemical impedance spectroscopy（EIS）and cyclic voltammetry（CV）.Results showed that the graphite modified with C_7H_5O_2 Na exhibits significantly better cycle efficiency and greater reversible capacity than original graphite,and the first reversible charge/discharge specific capacity of modified graphite anode approaches 293.9 mAh/g a nd 326.4 mAh/g at 0.5 C,higher than that of untreated graphite.The reason is that electrolyte interface film formed on the graphite surface could hinder the graphite expansion and benefit Li＋migration.Simultaneously,quantum chemistry method was cited for calculating the lowest-unoccupied（LUMO）and highestoccupied（HOMO）molecular orbital energies.All supporting surface analyses and electrochemical results demonstrated the optimum concentrations of C_7H_5O_2 Na modified graphite electrodes are 1 wt%.Moreover,the effects of modified graphite electrodes on electrochemical properties of batteries also were discussed at elevated temperature and under the optimum C_7H_5O_2 Na concentration.