硅/Ag/碳复合负极材料的制备、结构及其电化学性能研究

Preparation, Structure and Electrochemical Performance of Silicon/Ag/Carbon Composite Anode Materials for Lithium Ion Batteries

研究了银包覆和银-碳复合包覆对硅的结构和电化学性能的影响。采用XRD和TEM等手段分析了样品的结构和形貌,并采用恒电流充放电测试、循环伏安法和电化学阻抗法研究了改性处理前后硅负极的电化学性能。结果表明,硅/Ag/碳复合负极材料中,Ag纳米微粒以晶体的形式分布在硅颗粒的表面,一层无定形沥青炭包覆在硅/Ag复合颗粒的表面,这有利于提高硅颗粒的结构稳定性。电化学测试表明,与硅相比,硅/Ag/炭复合负极材料的电化学阻抗减小,电化学极化减弱,电化学反应的可逆性和循环寿命显著提高,第40次循环的比容量保持在390 m Ah g-1。

Effects of silver coating and silver/carbon coating on the structure and electrochemical performance of silicon are investigated. The structure and surface profile of the samples is characterized by XRD and TEM analysis, respectively. The electrochemical behaviors of the samples are studied by using galvanostatic charge/discharge test, electrochemical impedance spectra and cyclic voltammograms. The experiment results indicate that the silicon/Ag/carbon composite is obtained by the deposition of silver nanopariticles on the surface of silicon particles in crystalline form, and a layer of pitch carbon is coated on the surface of silicon/silver particles. So it is beneficial for improving the structure stability of the silicon particles.Electrochemical measures show that the silicon/Ag/carbon composite anode exhibits lower electrochemical resistance and weaker polarization, and the electrochemical reversibility and cycling are obviously improved,while the reversible capacity of the composite retains 390 mAh g-1 after 40 cycles.