低热固相法制备纳米MnO2/CNT超电容复合电极的循环稳定性

为了改善纳米MnO2超级电容器电极的充放电循环稳定性,以Mn(OAc)2·4H2O、NH4HCO3和碳纳米管(CNT)为原料,采用低热固相反应得到前驱体,再经焙烧和酸处理,制备了一系列CNT含量不同的纳米MnO2/CNT复合电极材料,并用X射线衍射(XRD)、透射电镜(TEM)和Brunauer-Emmett-Teller(BET)比表面积测定方法对其进行了表征.XRD分析结果表明,复合材料中的MnO2为纳米γ-MnO2.研究了复合电极在1 mol·L-1 LiOH电解质中的电化学性能,并与不含CNT的纯纳米MnO2电极进行了比较.结果表明,含CNTs为10%(w,质最分数,下同)和20%的MnO2/CNT复合电极的循环稳定性远优于纯纳米MnO2电极的循环稳定性,其中含10%CNTs的MnO2/CNT复合电极不仪具有良好的循环稳定性,而且在1000 mA·g-1高倍率充放电条件下仍具有200 F·g-1的高比电容.

Improved Cyclability of Nano-MnO2/CNT Composite Supercapacitor Electrode Derived from Room-Temperature Solid Reaction

To improve the charge/discharge cycle stability of a nanostructured manganese dioxide electrode for supercapacitor applications,a series of nano-MnO2/carbon nanotube(CNT)hybrid electrode materials with different mass fractions of CNTs were prepared.The materials were prepared using a room-temperature solid-grinding reaction between Mn(Oac)2·4H2O and NH4HCO3 in the presence of CNTs to obtain a precursor.This was followed by calcination and all acid-treatment process and the products were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),and Brunauer-Emmett-Teller(BET)surface analysis.XRD results indicated that the MnO2 in the composites was nanostructured γ-MnO2.Electrochemical performance of the MnO2/CNT composite electrodes in 1mol·L-1 LiOH alkaline aqueous electrolyte was studied and compared to a pure nano-MnO2 electrode without CNTs.The MnO2/CNT composite electrodes with 10%or 20%(w,mass fraction)CNTs showed far superior cycle stability than the pure MnO2 electrode.The MnO2/CNT composite electrode with 10%CNTs exhibited good cycling stability and also a high specific capacitance of 200 F·g-1 at a high charge/discharge current rate of 1000 mA·g-1.