纳米晶Li7Si3合金的制备与性能表征

为研究纳米结构锂电池阳极材料的特性,试制了纳米晶Li-Si合金.采用优化的纳米晶合金块体材料制备工艺,即熔炼制备粗晶Li7Si3合金铸锭、高能球磨得到Li7Si3非晶粉末,结合放电等离子烧结(spark plasma sintering,SPS)制备得到了纳米晶Li7Si3合金,并对其进行了Rietveld结构精修和杨氏模量测定.结果表明:纳米晶Li7Si3单胞结构参数为a=b=0.4452 nm(比粗晶增加0.38%),c=1.8239 nm(比粗晶增加0.58%),单胞体积Vo=0.313 070nm3(比粗晶增加1.35%).利用纳米压痕法测定纳米晶Li7Si3合金的杨氏模量为(30.6±2.4)GPa.

Preparation and Characterization of Nanocrystalline Li7Si3 Alloy

To study the characteristics of nanostructured anode materials of Li batteries, the nanocrystalline Li-Si alloy was prepared. Nanocrystalline Li7Si3 alloy was prepared with the optimized processing route including a series of procedures as cast of polycrystalline Li7Si3 ingot,ball milling to obtain the amorphous powder and spark plasma sintering to prepare the nanocrystalline Li7Si3 bulk. The crystal structure was determined using the Rietveld refinement method and the Young's modulus was measured. Results show that the prepared nanocrystalline Li7Si3 has larger lattice constants compared with those of the conventional polycrystalline counterpart,i. e.,a = b = 0. 445 2 nm,c = 1. 823 9 nm,and unit cell volume Vo= 0. 313 070 nm3. The unit cell volume is 1. 35% larger than that of the coarse-grained polycrystalline counterpart with a value of Vo= 0. 308 886 nm3. The Young's modulus of the nanocrystalline Li7Si3 was as( 30. 6 ± 2. 4) GPa.