预处理对热电池阳极材料LiB合金结构和性能的影响

在LiB合金材料的制备中加入冷挤压和热处理两步预处理工艺;采用X射线衍射仪、扫描电镜测试合金的物相组成和微观组织;研究了预处理工艺对材料的密度、硬度、力学性能、热稳定性和放电性能的影响。结果表明:相对直接轧制方法制备的LiB合金材料,采用预处理工艺,提高了合金材料中Li7B6的相对含量,同时使合金结构和成分更均匀、致密,从而提高了合金的密度、硬度,合金的抗拉强度和断裂延伸率也显著提高;预处理使材料骨架孔洞缩小而且分布均匀,因此也促进了材料热稳定性的提高;材料的放电性能显著提高,放电容量由5 244提高至6 552 C/g。此外,与直接轧制工艺相比,采用冷挤压和热处理两道预处理工艺减少了多孔的合金锭与可反应气氛接触的时间,防止了氧化作用,消除了开裂、麻点等缺陷,大大提高了材料的加工成材率,使其成材率由不到50%提高至70%以上。

Effect of pre-treatment procedures on structure and performance of thermal battery anode LiB alloy

Two pre-treatment procedures-cooling extrusion and heat treatment were introduced in preparation procedures of LiB alloy material. By means of X-ray diffractrometry, scanning electron microscopy the phase composition and microstructure characteristics of LiB alloys were observed. The influence of pre-treatment procedure on density, rigidity, mechanics performances, thermal stability and discharging performance were investigated. The results show that compared to the LiB alloy using direct-rolling method, the LiB alloys using after-treat procedures have higher Li7B6 content and more uniform and compact structure and composition. Therefore the density and rigidity of alloys are enhanced. The anti-draw intention and rupture prolongation ratio significantly increase. After treat procedures make the holes of framework smaller and arrangement more uniform, so increases the thermal stability of alloys. The discharging performances are enhanced and the discharging capacity is enhanced from 5 244 to 6 552 C/g. In addition, compared to direct-rolling procedure, the time that porous alloy ingot contacts reaction atmosphere decreases, so the oxidation reaction is prevented; the drawbacks such as perforation and speckle in alloy strip is avoided, so the product rate of LiB alloys is greatly enhanced from below 50 % to above 70 %.