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以天然硅酸盐矿物还原制备硅负极材料，即可以继承天然矿物结构来提高硅材料的电化学性能，又具有低成本的特点。以天然埃洛石铝热还原的产物为原料，沥青为碳源，采用简单的蒸发溶剂的方法制备了硅碳复合材料。结果表明：硅是以直径为30 nm左右的纳米管形式存在，碳层均匀地包覆在硅纳米管上，使得硅碳复合材料的直径增大，碳层厚度约为7 nm，碳以无定形结构存在，碳包覆还导致比表面积下降。电化学测试表明，与硅纳米管相比，当包覆碳含量(质量分数)为15%时电化学性能最好，首次充放电容量分别为1 387.8 mA·h/g和1 615.7 mA·h/g，首次Coulombic效率达到85.9%。不但保持住了硅纳米管的首次充放电效率，循环性能得到大幅度提升，与硅纳米管的循环200次容量保持率38%相比，包覆碳含量为15%的循环200次容量保持率提高了45.8%。包覆碳含量为15%的硅/碳复合材料的500次循环后比容量为1 065.6 mA·h/g。容量保持率为76.8%。
Abstract：The preparation of silicon anode materials via reduction of silicate minerals can improve the electrochemical properties and reduce the production cost. In this paper, silicon-carbon composites were prepared by a simple evaporation solvent method with natural halloysite aluminothermic reductive product as a raw material and asphalt as a carbon source. The results show that silicon exists in the form of nanotubes with a diameter of approximately 30 nm. The carbon layer is uniformly coated on the silicon nanotubes, which increases the diameter of the silicon carbon composite. The thickness of the carbon layer is approximately 7 nm.The carbon exists in an amorphous structure, and the carbon coating leads to the decrease of the specific surface area. According to the results of electrochemical tests, the optimum electrochemical performance of silicon-carbon composites can be obtained at a mass fraction of coated carbon of 15%, i.e., the first charge and discharge capacities of 1 387.8 mA·h/g and 1 615.7 mA·h/g, respectively,and the first coulomb efficiency of 85.9%. The silicon-carbon composites maintain the first charge discharge efficiency of silicon nanotubes, and greatly improve the cycle performance. Compared with the 200 cycles capacity retention rate of silicon nanotubes of 38%, the 200 cycles capacity retention rate of silicon-carbon composites coated with a carbon content of 15% is increased by 45.8%.The specific capacity of silicon-carbon composites coated with a carbon content of 15% is 1 065.6 mA·h/g after 500 cycles. The capacity retention rate is 76.8%.
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基本信息:
DOI：10.14062/j.issn.0454-5648.20210937
中图分类号:TM912;TB332
引用信息:
[1]杨绍斌,赵玲敏,赵明远,等.低成本硅纳米管/碳复合材料的制备及储锂性能[J].硅酸盐学报,2022,50(07):1875-1882.DOI:10.14062/j.issn.0454-5648.20210937.
基金信息:
国家自然科学基金(51774175,51874167,21808095)
2022-05-30
2022-05-30
2022-05-30