Essay On Electrochemical Supercapacitors

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In recent years, electrochemical supercapacitors (ECs) have been extensively studied as attractive energy storage devices. They have potential applications in portable electronics and electric vehicles because of their high power energy densities and long cyclic life [8, 101, 102]. Based on the nature of the charge-storage mechanism and active materials, electrochemical capacitors can be classified into two types: electrochemical double layer capacitors (EDLCs) and redox supercapacitors (pseudocapacitors). EDLCs utilizing carbon-based active materials, such as activated carbon (AC) and carbon nanotubes (CNTs) with charge stored at electrode-electrolyte interface, are currently the most commonly used devices [2]. On the other hand, pseudocapacitors …show more content…

However, cobalt hydroxide prepared by this technique demonstrated very low specific capacitance (SC) of less than 400 F g−1. Since the major limitation of Co(OH)2 is low conductivity, S. Chen et al. initiated the idea of fabricating graphene-Co(OH)2 nanocomposites by the use of some reducing agents such as HS– and H2S [117]. As a result, this research group managed to achieve specific capacitance of 972.5 F g-1 which is much higher than each individual counterpart. However, in above study, uniform distribution of Co(OH)2 is believed to be the main challenge. On the other hand, most of the reports were more concerned about the enhancement of SC values. Insufficient attention was paid to capacitance degradations of metal oxide/hydroxide materials at high current densities [118]. Our group previously reported the utilization of lyotropic liquid crystal (LLC) template in potentiostatic electrodeposition of Co(OH)2 which led to significant improvement in electrochemical performance [119]. Indium-tin oxide nanowire is known to possess excellent electrical properties and thermal stability [120, 121] which allows great applications in the field of electronics. On top of that, titanium was chosen as current collector owing to its well-known excellent mechanical, chemical and thermal stability as well as abundance in the Earth’s crust. In this study, we first prepared indium-tin oxide nanowires (ITO NWs) by chemical vapor deposition (CVD) on titanium substrate, and then different mesoporous structures such as Co(OH)2 nanoflake (NF) were deposited onto the indium-tin oxide nanowires (ITO NWs) by electrodeposition through lyotropic liquid crystal (LLC) template. In addition, mesoporous Co(OH)2 film, directly deposited on pure Ti substrate, was prepared for

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