石英晶体微天平分析不同介孔二氧化锰材料的电化学性能

Analysis of Electrochemical Performances of Different Mesoporous Manganese Dioxide Materials by Quartz Crystal Microbalance

以碳酸锰(Mn CO_3)为前体,空气氛围下采用不同温度(300℃、350℃、400℃)煅烧,制备了3种介孔二氧化锰(Mn O_2)材料,分别与粘结剂混合喷涂至石英晶片作为电极,利用石英晶体微天平(QCM)监测了3种材料在0.1 mol/L Na_2SO_4溶液中随循环伏安过程的电化学性能变化。分析结果表明,3种材料在首圈循环中都呈现出显著的质量增加,发生了不可逆反应过程;300℃煅烧制备的Mn O_2材料具备更好的电化学稳定性和容量保持能力。将300℃,350℃和400℃煅烧的Mn O_2各自作为正极与活性炭负极组成超级电容器,进行充放电测试,首圈均有35%~40%的容量损失;三者稳定循环时放电容量分别为15.9,12.9和11.7 m A h/g。QCM的分析与充放电测试结果相一致,表明QCM可用于比较不同介孔二氧化锰材料的电化学性能。

The mesoporous manganese dioxide(Mn〇2)materials were synthesized by the calcinations ofmanganese carbonate(MnC〇3)precursors in air atmosphere at300’350and400益.The slurries of Mn〇2and binder were sprayed on the quartz electrodes.Quartz crystal microbalance(QCM)was conducted withcyclic voltammetry to analyze the electrochemical behaviors of the three Mn〇2samples in0.1m ol/L sodiumsulfate(Na2S〇4).The mass of the three samples were generally increased during potential cycling’especiallyin the first stage,which suggested that an irreversible reaction process occurred.The as-synthesized Mn〇2at300益had the better electrochemical stability and capacity retentivity.The three materials were assembled to(-)active carbon/Mn〇2(+)supercapacitors and the charge-discharge tests were conducted.The resultsshowed that35%-40%capacity loss was occurred in the initial cycling,and the total discharge capacities ofMn02formed at300益’350益’400益were15.9,12.9,11.7mA^^g,respectively.The detection resultsof QCM method were consistent with that of the charge-discharge tests’suggesting that this QCM method couldbe used for distinguishing the electrochemical performance of mesoporous Mn〇2materials.