Three-dimensional hierarchical self-supported NiCo₂O₄/carbon nanotube core–shell networks as high performance supercapacitor electrodes

Abstract

Three-dimensional (3D) hierarchical self-supported NiCo 2 O 4 /carbon nanotubes/nickel foam (NiCo 2 O 4 /CNT/NF) electrode has been developed by electrodepositing NiCo layered double hydroxides (LDH) on self-supported CNT layer grown on macroporous NF substrate followed by a simple post-annealing process. The resulting 3D hierarchical self-supported NiCo 2 O 4 /CNT/NF electrode delivered high specific capacitances of 1533 F g -1 and 1335 F g -1 at current densities of 3 A g -1 and 30 A g -1 , respectively, vastly superior to those of NiCo 2 O 4 /NF electrode at same current density.The NiCo 2 O 4 /CNT/NF electrode also had good cycling stability and showed 102% initial capacitance retention after 2500 cycles at progressively varying current densities. The performance of NiCo 2 O 4 /CNT/NF electrode was further evaluated by two-electrode asymmetric supercapacitor device. The asymmetric device delivered a high energy density of 48.3 Wh kg -1 at a power density of 799.9 W kg -1 and still remained an energy density of 17.1 Wh kg -1 as power density increase up to 7995 W kg -1 . Remarkably, the asymmetric device also exhibited good cycling stability with capacitance retention of 78.9% after 2000 cycles at current density of 2 A g -1 ,indicating the promising applications in supercapacitors. Results of this study also provide an alternative strategy for constructing high performance supercapacitor electrode with high specific capacitance, good rate capability and cycling stability.

Self-standing carbon nanotube forest electrodes for flexible supercapacitors

“…Hence these are effectively utilized in variety of applications such as electromechanical actuators, 1 field-effect transistors, 2 sensors, 3 catalyst support materials for proton exchange membrane fuel cells, 4 electrodes for supercapacitors, 5 etc. Hence these are effectively utilized in variety of applications such as electromechanical actuators, 1 field-effect transistors, 2 sensors, 3 catalyst support materials for proton exchange membrane fuel cells, 4 electrodes for supercapacitors, 5 etc.…”

Carbon Transition‐metal Oxide Electrodes: Understanding the Role of Surface Engineering for High Energy Density Supercapacitors

“…Among the various hybrid electrode materials, C-TMO composite has gained particular interest since it combines the advantages of both components while reducing their shortcomings. [36,60,[72][73][74][75] Here, we present recent development on the preparation of C-TMO composite material as an active electrode towards SCs. This section will give insight on the specific role of carbon as well as TMOs, with particular emphasis on the carbon as active support, core element, and conductive substrate.…”

“…In particular, the distinct rectangular CV curve at lower potential window was due to the electric double layer formed between the electrode and hydroxyl ions, and the pair of clear redox peaks displayed at higher potential is an indication of the rapid and reversible redox reactions between metal and hydroxyl ions. [74,81] Attributed to the synergistic effects of CNF and NCO, the hybrid material displays high specific capacitance and energy density of 1188.19 F g À 1 and 37.23 W. h kg À 1 , respectively even at high current density of 50 A g À 1 . Similarly, Nitin et al reported the facile and efficient glycine-assisted hydrothermal route for the cube-like iron oxide nanoparticles supported on ordered multimodal porous carbon (OMPC).…”

Lamellar-crossing-structured Ni(OH)2/CNTs/Ni(OH)2 nanocomposite for electrochemical supercapacitor materials

“…Carbon nanotubes (CNTs), have been introduced to increase the conductivity and cycle life of Ni(OH) 2 due to theirs well-defined nanostructure, high electrical conductivity and chemical stability, [21][22]. Recently, many works of CNTs/NiO or CNTs/Ni(OH) 2 have been reported, such as three-dimensional hierarchical self-supported NiCo 2 O 4 /carbon nanotube core-shell networks [23], ultrathin β Ni(OH) 2 nanoplates vertically grown on nickel-coated carbon nanotubes [24], and carbon nanotube/NiO x (OH) y nanocomposite [25]. But, the degradation in specific capacitance caused by the materials aggregation is also a handicap to provide excellent electrochemical stability and cycle life [26].…”