“一锅法”水热制备CuS/C复合材料及其在超级电容器中的应用

One-pot hydrothermal synthesis of CuS/C composite and its application in supercapacitors

采用三水合硝酸铜为铜源、硫脲为硫源、D-葡萄糖酸钠为络合剂,发展了简单的"一锅法"水热直接一步合成CuS/C复合材料。采用X射线衍射仪(XRD)、激光显微拉曼光谱仪(Raman)、扫描电子显微镜(SEM)和有机元素分析仪对复合材料组成、结构及形貌进行表征。研究发现,样品主要由花状CuS球组成,同时含有质量分数约为6%的光滑炭球,CuS球表面分布有花瓣状褶皱,形成的大量孔道有利于离子传输,并增大活性物质与电解液的接触面积。研究表明,在1 A·g^(-1)电流密度下,比电容高达719 F·g^(-1),与不加络合剂制备得到的CuS(382 F·g^(-1))相比,比电容显著提高,并且在充放电1000次后比电容保持在80%左右,显示出良好的循环稳定性。

In this work, a simple one-pot hydrothermal method was developed to synthetize CuS/C composite in one-step by using copper nitrate trihydrate（Cu（NO3）2·3H2O） as copper source, thiourea as sulfur source and D-glucose sodium as complexing agent. The composition, microstructure and morphology of the CuS/C composite were characterized by X ray diffraction（XRD）, Raman spectroscopy, organic element analyzer and scanning electron microscopy（SEM）. It was found that the as-synthesized composite was mainly composed of novel petaloid CuS microspheres, which provided many paths for ion diffusion and increased specific area with about 6% of amorphous carbon microspheres（mass fraction）. The composite exhibited a maximum specific capacitance of up to 719 F·g-1at 1 A·g-1, while the specific capacitance was 382 F·g-1 at 1 A·g-1 for CuS prepared without using complexing agent. The long-term constant current charge-discharge test showed that the CuS/C composite exhibited excellent long cycle life with capacitance retention of 80% after 1000 cycles at 1 A·g-1. Although due to low melting point（220℃） of CuS, heat treatment at high temperature cannot be employed to transform the amorphous carbon microspheres into crystalline carbon for further improving the electrochemical properties, the one-pot hydrothermal method was likely to open a new way for directly synthetizing transition metal compounds/carbon composite materials by a one-step process, especially for transition metal compounds with high melting point/carbon composites with the possibility of carbonization treatment at high temperature.