锂离子电池负极材料PSi@GO的制备及其电化学性能

Preparation and electrochemical performance of Lithium-ion battery negative electrode material PSi@GO

具有高能量密度的硅材料是锂离子电池负极的优选材料之一。但是,低电导率和在充放电过程中伴随的巨大体积变化而导致循环过程中容量迅速衰减,阻碍了硅材料商业化。本文以商业化的铝硅合金为硅源,通过冷冻干燥方法将氧化石墨烯(GO)包覆在其表面,制备了微米级的多孔硅(PSi)与GO的复合材料PSi@GO。该复合材料核层多孔硅内部丰富的孔隙提供充足的空间以适应硅的体积变化,外层的氧化石墨烯可以加速离子和电子传输,并再次缓冲硅的体积变化,从而可以有效地改善硅负极的循环稳定性和倍率性能。研究结果表明,电流密度为500 mA/g时,PSi@GO-2(PSi与GO质量比为10∶5)复合电极材料循环100次后,比容量仍可达到1275 mAh/g;在电流密度为4 A/g时,该复合材料也可达到980 mAh/g的高比容量。该PSi@GO-2复合材料显示了优异的倍率性能,具有良好的应用前景。

The high energy density of silicon makes it one of the preferred materials for the negative electrode of lithium-ion batteries.However,the low conductivity and the accompanying large volume changes during charging and discharging process led to the rapid decay of the capacity during the cycle,which hindered its commercialization.In this paper,a commercialized aluminum-silicon alloy is used as the silicon source,and graphene oxide is coated on the surface by freeze-drying method to prepare micron-scale PSi@GO composite materials.The rich pores inside the porous silicon core layer of the composite material provide sufficient space to accommodate the volume changes of silicon,and the graphene oxide in the outer composite layer can accelerate the transmission of ions and electrons and buffer the volume change of silicon again,thereby effectively improving the cycle stability and multiplier performance of the silicon negative electrode.The research results show that when the PSi@GO-2(with a mass ratio of 10∶5)composite electrode material has a current density of 500 mAh/g,the specific capacity is still 1290.60 mAh/g after 100 cycles.In addition,it still has a high specific capacity of 979.78 mAh/g when the current density is 4 A/g.The PSi@GO composite material shows excellent multiplier performance and has good application prospects.