空间占位法制备的Si-C负极材料及其在锂电池中的应用

Si-C Anode Materials Prepared by Space Occupation Method and Their Application in Lithium Battery

硅基锂离子电池在充放电过程中存在巨大的体积效应,有效抑制硅体积的膨胀以及降低硅的成本是推进硅基锂离子电池商业化应用的关键因素。以低成本的商业用微米硅、空间占位材料Al和沥青为原料,通过常温搅拌粘结、热解复合和酸处理得到空间占位法制备的3种不同碳质量比的复合电极材料,即Si-C-1-1、Si-C-1-2和Si-C-1-3。通过扫描电子显微镜(SEM)、恒流充放电、循环伏安法和电化学阻抗法对不同碳质量比的Si-C复合电极材料进行形貌表征与性能测试,结果表明,Si-C复合电极材料呈多孔的结构,可有效缓解充放电过程中硅的体积膨胀问题,其中Si-C-1-2复合电极材料表现出最优异的性能。Si-C-1-2复合电极材料组装为电池后,在电流密度为200 mA/g时表现出较高的首次库伦效率(84%)和首次比容量1 080 mA·h/g,循环100圈后比容量保持率为57%。

Silicon-based lithium-ion batteries have a huge volume effect during the charging and discharging process.Effective suppression of silicon volume expansion and reducing the cost of silicon are key factors to promote the commercial application of silicon-based lithium-ion batte-ries.With low-cost commercial micron silicon, space occupying material Al and asphalt as raw materials, three composite electrode materials with different carbon mass ratios, namely Si-C-1-1,Si-C-1-2 and Si-C-1-3,were prepared by space occupying method with normal temperature mixing and bonding, pyrolytic compounding and acid treatment.The morphology characterization and performance test of the prepared Si-C composite electrode materials with different carbon mass ratios were carried out by scanning electron microscope(SEM),constant current charge and discharge, cyclic voltammetry and electrochemical impedance.The results show that the Si-C composite electrode materials have a porous structure, which can effectively alleviate the volume expansion of silicon during the charging and discharging processes.Among them, the Si-C-1-2 composite electrode material shows the most excellent performance.The battery assembled with Si-C-1-2 composite electrode material exhibits high first Coulombic efficiency(84%) and first specific capacity of 1 080 mA·h/g at a current density of 200 mA/g, and the specific capacity retention rate is 57% after 100 cycles.