化学还原-球磨法制备Sn-Co-C锂离子电池负极材料的性能

Performance of Sn-Co-C negative electrode material for Li-ion batteries prepared by chemical reduction and ball-milling

采用化学还原法得到纳米级Sn-Co粉末,再经过与硬碳粉混合球磨得到Sn-Co-C复合粉体。能谱测试表明,样品Sn、Co、C原子分数分别为3.89%、1.47%、94.64%。SEM观察显示,50－100 nm锡钴微粒附着在片状的硬碳颗粒上。复合粉体与锂片组成模拟电池,首次放电比容量为558.4 mAh/g,首次充电比容量为338.5 mAh/g。30次循环后,放电比容量保持在348.2 mAh/g,保持率为62.4%;充电比容量保持在335.4 mAh/g,保持率为99.1%。充放电比容量较硬碳提高3倍左右。由分析放电曲线可知,第一次放电后在电极表面形成了固体电解质界面膜（SEI）膜,循环一次后该膜消失。

Sn-Co-C compound powder was prepared by ball milling with hard carbon powder and nanosized Sn-Co powder,prepared by chemical reduction.The EPMA results show that the atomic percentages of Sn/Co/C in Sn-Co-C compound powder are 3.89%,1.47%,94.64% respectively.SEM images show that Sn-Co grains,being 50～100 nm sized,are dispersed on the surface of carbon powder.The simulation cells consist of Sn-Co-C compound powder and Li piece.The initial discharge specific capacity is 558.4 mAh/g and remains 348.2 mAh/g after 30 cycles.The initial charge specific capacity is 338.5 mAh/g and remains 335.4 mAh/g after 30 cycles.The charge-discharge specific capacity is about 3 times higher than that of hard carbon electrode.It was suggested that the solid electrolyte interface（SEI） films were formed on the surface of Sn-Co-C electrode after the first discharge,but disappeared after the first cycle by analysis of the discharge curve.