NiCo2S4&KB复合材料的制备及其电化学性能

Preparation and electrochemical property of NiCo2S4&KB composite materials

针对锂-硫电池中活性物质硫和Li2S/Li2S2导电性差,充放电过程中硫的体积膨胀、中间产物多硫化物离子易溶于电解液等问题,以科琴黑(KB)、六水合硝酸镍(Ni(NO3)2·6H2O)、六水合硝酸钴(Co(NO3)2·6H2O)和尿素为原料,经水热和热熔过程制备出均匀分散的NiCo2S4&KB/S正极材料,并将该正极材料应用于锂-硫电池电化学性能研究。结果表明:经过0.5 M硫化钠处理的NiCo2S4&KB/S电极表现出优异的电化学性能;在低电流密度下(0.2 C),初始放电比容量为1278 mAh/g,循环100圈后其比容量仍保持在984 mAh/g,库伦效率达到94.20%;在5.0 C的高电流密度下,首圈放电比容量为437 mAh/g,200圈后容量仍能达到331 mAh/g,平均每圈衰减率为0.12%。该复合材料为锂-硫电池的正极材料的设计与制备提供一种新的思路和方法。

The active substances sulfur and Li2S/Li2S2 in the Lithium-Sulfur battery have poor electrical conductivity. And, sulfur volume expands and the intermediate products polysulfide is dissolved in the electrolyte during charge/discharge process. For these problems, Ketjen black(KB), nickel nitrate hexahydrate(Ni(NO3)2·6 H2O), cobalt nitrate hexahydrate(Co(NO3)2·6 H2O) and urea were used as the raw materials to prepare evenly dispersed NiCo2S4&KB/S anode material by hydrothermal reaction and hot melting. The anode material was used to study the electrochemical property of Lithium-Sulfur battery. The results show that NiCo2S4&KB/S electrode treated by 0.5 M Na2S has excellent electrochemical property: The initial specific discharge capacity is 1278 mAh/g under the low current density(0.2 C) and a high capacity of 984 mAh/g can still be maintained even after 100 cycles. The coulombic efficiency can reach 94.20%. Furthermore, under the high current density of 5.0 C, its initial specific discharge capacity is 437 mAh/g, and its capacity can still reach 331 mAh/g after 200 cycles. Besides, the average attenuation rate of each cycle is only 0.12%. NiCo2S4&KB composite material provides a new through and method for the design and preparation of anode material of Lithium-Sulfur battery.