草酸钴前驱体热分解制备Co3O4及其超电容性能

Synthesis and Super Capacitive Performance of Co_3O_4 by Thermal Decomposition from Cobalt Oxalate Precursor

以Co(NO_3)_2·6H_2O、草酸铵为原料,采用液相共沉淀法制得钴的草酸盐前驱物,并利用微波进行热处理制得了微米尺寸的Co_3O_4电极材料。通过X射线衍射分析(XRD)、扫描电子显微镜(SEM)研究了产物的物相和微观形貌。通过循环伏安(CV)和恒电流充放电(CD)实验研究了产物在碱性电解质中的超电容性能。结果表明,利用微波加热分解法可制得立方晶系Co_3O_4纯相,其在6 mol/L KOH溶液中具有明显的法拉第赝电容。在2 mV/s扫描速度下,比电容达到91 F/g。Co_3O_4在碱性电解质中的赝电容主要来自于OH^-在Co_3O_4、CoOOH、Co(OH)_2体相中的嵌入和脱嵌过程。Co_3O_4在大循环过程中的比电容衰减主要是由于电极上氧化还原反应的可逆性较差以及发生的副反应而造成的。

Micron-scale Co3O4 electrode materials were prepared by microwave heating a precursor of cobalt oxalate obtained by eoprecipitaion using cobalt nitrate and ammonium oxalate as raw materials. The structure and surface morphology of the as-prepared Co3O4 were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The supercapacitive behaviour of the as-prepared Co3O4 in alkaline electrolyte was studied by cyclic voltammetry （CV） and galvanostatic charge-discharge cycling （CD）. The results indicate that pure Co3O4 of cubic system can be obtained by microwave heat-treatment, the as-prepared Co3O4 show good presupercapaeitive behaviors with a specific capacitance of 91 F/g at 2 mV/s in 6 mol/L KOH. The capacitance of the as-prepared Co3O4 in alkaline electrolyte arised from the intercalation and deintercalation processes of OH- in Co3O4, CoOOH and Co（OH） 2. The capacitance decay of the as-prepared Co3O4 during the long circles was caused by the poor reversibility and the secondary reaction of the faraday processes on the electrode.