高容量MgCo_(2)O_(4)纳米线的制备及电化学性能研究

Preparation and Electrochemical Properties of High-Capacitance MgCo_(2)O_(4) Nanowires

尖晶石型钴基金属氧化物MgCo_(2)O_(4)拥有超高理论比电容值(3122 F/g),成为超级电容器的研究热点。为了获得高容量的MgCo_(2)O_(4)超级电容器电极材料,通过加入不同剂量的表面活性剂十二烷基磺酸钠(SDS)在泡沫镍上水热合成MgCo_(2)O_(4)前驱体,低温煅烧获得MgCo_(2)O_(4)纳米线。研究表明,表面活性剂SDS不但对MgCo_(2)O_(4)电极材料的形貌有微观调控作用,同时间接影响了其电化学性能。当加入1 mmol的表面活性剂SDS时,所合成的MgCo_(2)O_(4)纳米线在电流密度为1 mA/cm^(2)时,比电容值高达4914 F/g;把它作为一种无粘结剂的超级电容器电极材料以20 mA/cm^(2)循环1000圈后比电容保持了53.48%。将MgCo_(2)O_(4)纳米线和活性炭分别作为正极和负极组装成非对称超级电容器,其在电流密度为1 A/g时比电容值达72.59 F/g,同时在功率密度为920.86 W/kg下能量密度可达25.8 Wh/kg。另外,对该非对称超级电容器循环1000圈后比电容保持了94.77%,说明MgCo_(2)O_(4)可作为能量存储的电极材料。

MgCo_(2)O_(4),cobalt-based metal oxides with spinel-type,possesses ultra-high theoretical specific capacitance(3122 F/g),becoming a hot topic for supercapacitors.To get high-capacitance MgCo_(2)O_(4)electrode materials for supercapacitors,MgCo_(2)O_(4)precursor on nickel foam was synthesized by hydrothermal route with different amounts of surfactant sodium dodecyl sulphate.Then MgCo_(2)O_(4)nanowires were obtained through a lower temperature calcination process in this work.It showed that the surfactant sodium dodecyl sulphate affected not only the micromorphology of MgCo_(2)O_(4)electrode material,but also its electrochemistry performance.When 1 mmol of surfactant sodium dodecyl sulphate was added,the as-prepared MgCo_(2)O_(4)nanowires exhibited a superior specific capacitance of 4914 F/g at the current density of 1 mA/cm^(2).After 1000 cycles at the current density of 20 mA/cm^(2),53.48%of initial capacitance was retained when it was used as a binder-free electrode material for supercapacitors.The asymmetric supercapacitor was assembled with MgCo_(2)O_(4)nanowires and activated carbon respectively set as the positive and negative electrode,which exhibited 72.59 F/g at the current density of 1 A/g,meanwhile,the energy density can reach 25.8 Wh/kg at the power density of 920.86 W/kg.Additionally,after 1000 cycles of the asymmetric supercapacitor,the specific capacitance was maintained at 94.77%,manifesting the great potential of MgCo_(2)O_(4)as excellent material for energy storage.