多孔硅碳复合材料的制备及性能改善

Synthesis of porous silicon-carbon composites for lithium ion battery anode materials and its property improvement

硅基负极材料存在体积膨胀、表面稳定性差和导电性低的问题。通过硅形貌调控、立体导电网络构筑、多孔结构构造和碳包覆的方法,制备了多孔硅碳复合材料。基于硅不同晶面离解能的不同,球磨获得硅纳米片。将含硅纳米片、碳纳米管(CNT)和石墨的浆料,喷雾干燥,获得硅纳米片和CNT自组装形成多孔结构。对多孔结构进行液相碳包覆,使多孔结构内的纳米硅和整个多孔结构表面形成碳包覆层,获得多孔硅碳复合材料。扣电测试显示,该材料可逆比容量为1000.8 mAh/g,首次循环效率高达93.9%,全电测试显示优异的1 C特性和较好的循环稳定性,这主要得益于立体导电网络的构建、多孔结构的构造和双重碳包覆的形成,提高了硅基材料的导电性,缓解了体积膨胀,提高了表面稳定性。

Silicon-based anode materials have problems of volume expansion,surface instability or low electron conductivity.In this paper,porous silicon-carbon composites are obtained by Si morphology control,conductive net-work design,porous structure construction and carbon coating.Si nanosheets can be obtained via balling based on different cleavage energies in different facets of Si.Spray drying of the well-distributed slurry containing silicon nanosheets,carbon nanotubes,and graphite yields porous structures.Liquid state carbon coating of the porous structures leads to the entire carbon coating on both the surfaces of the silicon nanosheets and the whole composites.Coin test shows the composite deliver a specific capacity of 1000.8 mAh/g and a high initial coulombic efficiency of 93.9%.Full cell tests display high rate property at 1 C and good cycling behavior.These good performances are derived from the conductive net-work structure,the porous structure construction,and the dual-carbon coating of the composite.