S含量对S/AB复合正极材料性能影响

Influences of Sulfur Content on Properties of S/AB Composite Cathode Materials

为研究S含量对S/AB复合正极材料的性能影响,将单质硫(S)与乙炔黑(AB)分别以3∶1、4∶1和5∶1比例复合,热处理后制得不同的复合正极材料。分别测试单质硫与乙炔黑的组织结构以及电池的交流阻抗谱、循环伏安特性和充放电特性等电化学性能。结果表明,S∶AB=4∶1时,S/AB复合正极材料在0.1 C的放电倍率下首次放电容量最高,达到899.86 mA·h/g,但20次循环后,库仑效率仅为38.45%,说明乙炔黑(AB)的颗粒状结构不能有效防止锂硫电池活性物质的损失。

To study the influences of sulfur content on properties of S/AB composite cathode materials, we synthesized cathodes of lithium-sulfur batteries by heating sulfur with acetylene black at the ratio of 3： 1, 4：1 and 5： 1. The structures of sulfur and acetylene black, and the electrochemical properties such as electrochemical impedance spectroscopy, cyclic voltammetry property, and charge and discharge characteristics of the lithium-sulphur battery were tested Results show that when the S/AB ratio is 4： 1, the highest initial discharge capacity of the S/AB composite cathode material reaches 899.86 mA. h/g in the current rate of 0.1 C. However the coulombic efficiency is only 38.45% after 20 cycles. It illustrates that acetylene black of granular structure cannot prevent the loss of substance active substances.