ABSTRACT

Nano-Li2FeSiO4/C composites (LFS/C-325 and LFS/C-221) and nano-Li2FeSiO4 (LFS-325 and LFS-221) with controlled porosity were prepared from the nano-fumed silicas with similar particle size and different porosity. N2 adsorption/desorption analysis reveals that the porosity of nano-Li2FeSiO4/C composites and nano-Li2FeSiO4 can be tuned by the choosing nano -fumed silica and LFS/C-325 possess the highest specific surface area among the four samples. XRD indicates that both LFS/C-325 and LFS/C-221 are crystalline powders with monoclinic Li2FeSiO4 of P21. FTIR spectra show that Li-O and Si-O bonds are existed in the four samples. SEM images demonstrate that LFS/C-325 and LFS/C-221 have similar particle sizes in the range of 20 ~ 25 nm, which are distinctly smaller than those of LFS-325 and LFS-221. LFS/C-325 features the smallest particle size and largest specific area, which enables LFS/C-325 to exhibit the best electrochemical performance. The initial discharge capacity of LFS/C-325 is as high as 185.2 mAh g⁻¹ at 0.1 C.

摘要

由具有相似粒径和不同孔隙率的纳米气相二氧化硅制备出具有可控孔隙率的纳米Li2FeSiO4/C复合材料（LFS/C-325和LFS/C-221）和纳米Li2FeSiO4（LFS-325和LFS-221） . N2吸附/解吸分析表明，纳米Li2FeSiO4/C复合材料和纳米Li2FeSiO4的孔隙率可以通过选择纳米气相二氧化硅来调节，并且LFS/C-325在四种样品中具有最高的比表面积。XRD 表明 LFS/C-325 和 LFS/C-221 均为结晶粉末，具有 P21 的单斜 Li2FeSiO4。FTIR光谱表明，四种样品中均存在Li-O键和Si-O键。SEM 图像显示 LFS/C-325 和 LFS/C-221 在 20 ~ 25 nm 范围内具有相似的粒径，明显小于 LFS-325 和 LFS-221。LFS/C-325具有最小的粒径和最大的比面积，这使得LFS/C-325能够表现出最佳的电化学性能。LFS/C-325的初始放电容量高达185.2 mAh g^-1在 0.1 摄氏度。