水热法制备绒花状NiCo2O4及其电容性能研究

Hydrothermal Synthesis of Velvet Flowers-Like NiCo2O4 for Supercapacitors

目前有关钴-镍硝酸盐浓度对水热法制备NiCo2O4电极材料的形貌和电化学性能的影响研究鲜见报道。以不同镍、钴硝酸盐浓度的水溶液为反应体系,通过水热法在泡沫镍上制备了NiCo2O4电极材料,并对材料进行了结构和形貌表征以及电化学性能测试。结果表明:在镍、钴硝酸盐溶液中,水热反应使泡沫镍表面生长出由纳米丝自组装形成的绒花状NiCo2O4晶体,比表面积增大有利于电解质离子渗透和电子传输;不同镍、钴硝酸盐浓度条件下制备的NiCo2O4材料的欧姆电阻Rs和电荷传质电阻Rct均较小;相比其他浓度条件,镍钴硝酸盐浓度为0.25g Ni(NO3)2·6H2O-0.50g Co(NO3)2·6H2O/30mL、0.35g Ni(NO3)2·6H2O-0.70g Co(NO3)2·6H2O/30mL时制备的NiCo2O4材料具有更好的氧化还原可逆性和赝电容特性,在恒电流密度40mA/cm^2的充放电下,其比电容值分别为668,650 F/g。

NiCo2O4 electrode materials were prepared on nickel foam by hydrothermal method in Co(NO3)2 and Ni(NO3)2 system with different concentrations.Subsequently,the structure,morphologies and electrochemical properties of samples were investigated.Results showed that the velvet flowers-like NiCo2O4 was self-assembled from nano-silk on Ni foam owing to hydrothermal reaction,which proved large surface area to facilitate the permeation of ion and the transform of electronic.Moreover,Rs and Rct of NiCo2O4 electrode materials prepared at different concentrations were small.In the comparison of other concentrations,the NiCo2O4 electrode material prepared under the conditions of 0.25g Ni(NO3)2·6H2O-0.50g Co(NO3)2·6H2O/30 mL and 0.35g NiCo2O4(NO3)2·6H2O-0.70g Co(NO3)2·6H2O/30 mL performed the optimal redox reversibility and pseudocapacitance characteristics,and the specific capacitance value was 668 F/g and 650 F/g at 40 mA/cm^2 during charge and discharge processes,respectively.