Solid State Flexible Asymmetric Supercapacitor Based on Carbon Fiber Supported Hierarchical Co(OH)_xCO₃ and Ni(OH)₂

Abstract

Conducting flexible carbon fiber (CF) cloth was used as a substrate for the hydrothermal growth of nickel hydroxide (Ni(OH)2) and cobalt hydroxy carbonate [Co(OH)xCO3] with unique hierarchical flowery architecture and then was used as a flexible supercapacitor electrode. In a three-electrode configuration in 6 M KOH aqueous electrolyte, the CF-Ni(OH)2 and CF-Co(OH)xCO3 electrode showed the maximum specific capacitance of 789 F/g and 550 F/g, respectively, at 2A/g current accompanied by outstanding cycle stability by retaining 99.9% and 99.5% specific capacitance over 1500 consecutive charge-discharge cycles at 5 A/g. However, the low cell voltage (0.4 V) restricted the respective specific energy to 4.38 and 3.05 Wh/kg at a specific power of 100 W/kg. To overcome the issue, two solid state flexible asymmetric supercapacitors were fabricated using the CF-Ni(OH)2 and CF-Co(OH)xCO3 as the anode and sonochemically deposited CNT over carbon fiber as the cathode material in PVA-KOH gel electrolyte. The as-fabricated flexible supercapacitors CF-Ni(OH)2//CF-CNT and CF-Co(OH)xCO3//CF-CNT were able to deliver high specific energy of 41.1 and 33.48 Wh/kg, respectively, at high specific power of 1.4 kW/kg accompanied by excellent cycle stability (retaining 98% and 97.6% specific capacitance, respectively, over 3000 charge-discharge cycle at 5 A/g).

V2O5 and its Carbon‐Based Nanocomposites for Supercapacitor Applications

“…This process can be defined as the growth of the crystals from aqueous solution within Teflon‐coated stainless‐steel autoclave at high temperature under high pressure. A large number of metal oxides, hydroxides and sulfides have been synthesized using hydrothermal technique for various applications reported elsewhere . Several morphologies of V 2 O 5 such as, nanoparticles, nanowires and nanorods, nanofibers, nanosheets, nano‐belts, nano‐plates, flower‐like flakes, nanoballs, nanoflowers, and even microspheres have been synthesized by hydrothermal technique to investigate their electrochemical properties as depicted in Table .…”

Design of Architectures and Materials in In‐Plane Micro‐supercapacitors: Current Status and Future Challenges

“…Recently, an in‐plane micro‐supercapacitor was fabricated through electro‐deposition of mesoporous RuO x : this capacitor showed a maximum specific capacitance of 12.6 mF cm −2 . Besides RuO 2 , other metal oxides, such as iron, vanadium, nickel, cobalt, molybdenum, and manganese have also been investigated. Particularly, manganese oxide has been the subject of maximum attention because of its high theoretical specific capacitance (1370 F g −1 ) and environmentally friendly nature, and the low cost of the raw material.…”

Carbon-Based Electrode Materials for Supercapacitor: Progress, Challenges and Prospective Solutions

“…), metals hydroxide (Ni(OH) 2 /graphene, Co(OH) 2 /graphene, etc.) and other multiplex compound (Ni(OH) 2 -MnO 2 -rGO [31], CFs/Co(OH) x CO 3 and CFs/Ni(OH) 2 [32], etc.) are still being extensively investigated at present.…”