提出一种逐步炭化法,以稀硫酸、蔗糖和单质硫为原料,制备碳/硫复合正极材料。扫描电镜、透射电镜结果显示:复合材料为粒度分布均匀的核壳结构球体,直径约为3μm;单质硫均匀填充在球体内部。此种结构有利于提高其电化学性能。在0.1C倍率下碳/硫复合正极材料首次放电比容量为1065mAh/g,60次循环之后,放电比容量趋于稳定,150次循环后的比容量仍可达到510mAh/g,库仑效率始终保持在90%以上。表明逐步炭化法可以制备适宜的锂硫电池正极材料。
Carbon/sulfur composites were prepared by a gradual carbonization method using sulfur,sucrose and diluted sulfuric acid as the reagents.SEM and TEM results showed that the as-prepared samples were evenly scatted spheres with core-shell structure in a diameter of about 3μm and the sulfur was loaded fully in these spheres.This kind of configuration offered an enhanced electrochemical performance with a discharge specific capacity of 1065mAh/g.After 60 cycles,the discharge specific capacity faded slowly and tended to be stable with a discharge capacity of about 510mAh/g and a fade rate of about 0.066% after 150 cycles.The coulombic efficiency remained at above 90% during long calendar cycles.These results indicated that the gradual carbonization method could be a suitable way to prepare the core-shell structured carbon/sulfur composite material for lithium-sulfur battery.
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基金资助
国家自然科学基金(51273027)
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