Synthesis and electrochemical supercapacitive performance of copper cobaltspinel hollow spheres

سال انتشار: 1395
نوع سند: مقاله کنفرانسی
زبان: انگلیسی
مشاهده: 250

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شناسه ملی سند علمی:

ELECTROCHEMISTRY012_143

تاریخ نمایه سازی: 5 آذر 1397

چکیده مقاله:

Supercapacitor is a rapidly growing industry that is revolutionizing the energy storage technologytoday. Their high power density and excellent low temperature performance have made them thetechnology of choice for back-up power, cold starting, flash cameras and regenerative braking.They also play an important role in the progress of hybrid and electric vehicles, consumerelectronics, military and space applications [1]. Supercapacitors are expected to have moreindustrial applications if their energy density could be improved. This has triggered tremendousresearch efforts in order to develop new electrode materials that are capable of providing a hugeamount of energy in a short period of time [2]. Metal oxides have a higher capacitance/energythan carbonaceous materials due to Faradaic redox reactions [3]. Among them, binary metaloxides such as spinels are more efficient than single metal oxides owning to their richer redoxreactions [4]. Herein, for the first time, we report mesoporous copper cobaltite (CuCo2O4) hollowspheres prepared by a facile method as a high-performance supercapacitor electrode material.Mesoporous CuCo2O4 hollow spheres was prepared as follow: 0.5 mmol of Co(NO3)2·6H2O,0.25 mmol of Cu(NO3)2·6H2O, and 16 mL of glycerol were dissolved into 80 mL of isopropanol.The solution was then transferred to a Teflon-lined stainless steel autoclave and kept at 180 °Cfor 6 h. After cooling, the brown precipitate (CuCo-glycerate) was centrifuged, washed withseveral times with ethanol and dried in an oven at 80 °C. In order to obtain the CuCo2O4 hollowspheres, the as-synthesized CuCo-glycerate was annealed at 350 °C for 2 h. XRD, XPS, SEM andTEM images confirm the preparation of CuCo2O4 hollow spheres. Also, BET and BJH isothermsconfirm mesoporous structure of sample. The electrodes were prepared by the painting of mixingactive material, acetylene black, and polyvinylidene fluoride (PVDF) (with a mass ratio of85:10:5) on the Ni foams. The half-cell electrochemical performance of the electrodes were investigated in a 6 M KOH solution. The Mesoporous CuCo2O4 hollow spheres electrodes exhibitexcellent electrochemical performance, including an ultra-high specific capacitance of 1212 F g−1at 2 A g−1 and 605 F g−1 at ultra-high current density of 60 A g−1 (50% retention) and excellentcycle life (only 7 % capacitance loss after 5000 cycles at current density of 5 A g−1).Thisoutstanding electrochemical performance of these electrodes can be attributed to their hollowsphere morphology with unique properties, such as mesoporous structure, high surface area andnano-scale shell thickness. Mesoporous structures minimize the diffusion distance from theexternal electrolyte to the interior surfaces by acting as ion-buffering reservoirs which enhancesthe accessibility of electrolyte not only at its surface but also throughout the entire material [5].High specific surface area improves the utilization of the active material by providing moreactive sites with larger interfacial area between the electrode material and the electrolyte ions [6].Nanosized shell thickness lead to faster kinetics and higher conductivity by providing shorttransport pathways for electrons [5]. We envision these electrodes to be useful in a broad range ofapplications such as supercapacitors, lithium ion batteries, fuel cells, gas sensors, biosensors,catalysis, and other electronic devices.

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نویسندگان

Saeid kamari kaverlavani

Department of Physics, Tarbiat Modares University, Tehran, Iran

Seyyed Ebrahim Moosavifard

Young Researchers and Elite Club, Central Tehran Branch, Islamic Azad University

Ali bakouei

Department of Physics, Tarbiat Modares University, Tehran, Iran.