摘要
超级电容器比能量密度的提高可以通过提高比电容或电压窗口来实现,然而在高电压窗口下水的分解大大限制了水系超级电容器的储能潜力。以高锰酸钾(KMnO_(4))为原料,在硝酸钠(NaNO_(3))熔盐体系中经过高温化学反应制备了片状Na_(2)Mn_(3)O_(7)。用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)和X射线光电子能谱仪(XPS)分析了样品的物相、形貌和化学状态,结果表明将Na^(+)引入锰氧结构中可使其电压窗口显著变宽。采用循环伏安法(CV)、三电极恒电流充放电和电化学阻抗研究了样品的电化学性能。在三电极体系中得到了0~1.3 V的高电压窗口,当电流密度为1 A·g^(-1)时,比电容可达到137 F·g^(-1)。以Na_(2)Mn_(3)O_(7)作为非对称超级电容器正极、活性炭作为负极、1 mol/L Na_(2)SO_(4)作为电解液构建电压窗口为2.4 V的非对称超级电容器,该电容器在607 W·kg^(-1)时,能量密度为77.2 Wh·kg^(-1)。在电流密度为10 A·g^(-1)循环5000次以后,容量保持率可达75.6%。相较于锰氧化物,Na_(2)Mn_(3)O_(7)有着更高的极化电位,说明Na^(+)离子的嵌入使锰氧结构在相对高电位时更为稳定。
The energy density of supercapacitor can be improved by increasing the specific capacitance or voltage window.However,water decomposition at high voltage window greatly limits the energy storage potential of supercapacitor in practical application.In this work,potassium permanganate(KMnO_(4))was used as raw material to prepare Na_(2)Mn_(3)O_(7) sheet in sodium nitrate(NaNO_(3))molten salt system at high temperature.The phase,morphology and chemical states of the samples were analyzed by powder X-ray diffraction(XRD),scanning electron microscope(SEM),and X-ray photoelectron spectroscopy(XPS).The results show that the working potential window can be broadened by introducing Na^(+)into the lattice of manganese oxides.The electrochemical properties of the samples were investigated by cyclic voltammetry(CV),galvanostatic charge-discharge and electrochemical impedance.A wide voltage window of 0-1.3 V and 137 F·g^(-1) at 1 A·g^(-1)were obtained in three-electrode system.Furthermore,an asymmetric supercapacitor was assembled using Na_(2)Mn_(3)O_(7),activated carbon and 1 mol/L Na_(2)SO_(4)as positive electrode,negative electrode and electrolyte respectively at a voltage window of 2.4 V.The energy density of the asymmetric capacitor was 77.2 Wh·kg^(-1) at 607 W·kg^(-1).After 5000 cycles at current density of 10 A·g^(-1),the capacity retention was~75.6%.Compared with manganese oxide,Na_(2)Mn_(3)O_(7) has a higher polarization potential,namely,the introduction of Na^(+)ions makes the manganese structure more stable at relatively high potential.
作者
刘慧
黄贤敏
李紫薇
范馨予
高红艳
LIU Hui;HUANG Xianmin;LI Ziwei;FAN Xinyu;GAO Hongyan(College of Chemistry and Environmental Science,Yili Normal University,Yining 835000,Xinjiang Uygur Autonomous Region,China)
出处
《电子元件与材料》
CAS
CSCD
北大核心
2022年第6期574-581,共8页
Electronic Components And Materials
基金
伊犁师范大学污染物化学与环境治理重点实验室开放课题科研项目(2020HJZD002)
伊犁师范大学2020年研究生科研创新项目(YSD202022)。
