Mesoporous NiCo₂O₄ Nanowire Arrays Grown on Carbon Textiles as Binder‐Free Flexible Electrodes for Energy Storage

Abstract

Binary metal oxides has been regarded as a promising class of electrode materials for high‐performance energy storage devices since it offers higher electrochemical activity and higher capacity than mono‐metal oxide. Besides, rational design of electrode architectures is an effective solution to further enhance electrochemical performance of energy storage devices. Here, the advanced electrode architectures consisting of carbon textiles uniformally covered by mesoporous NiCo2O4 nanowire arrays (NWAs) are successfully fabricated by a simple surfactant‐assisted hydrothermal method combined with a short post annealing treatment, which can be directly applied as self‐supported electrodes for energy storage devices, such as Li‐ion batteries, supercapacitors. The as‐prepared mesoporous NiCo2O4 nanowires consist of numerous highly crystalline nanoparticles, leaving a large number of mesopores to alleviate the volume change during the charge/discharge process. Electrode architectures presented here promise fast electron transport by direct connection to the growth substrate and facile ion diffusion path provided by both the abundant mesoporous structure in nanowires and large open spaces between neighboring nanowires, which ensures every nanowire participates in the ultrafast electrochemical reaction. Benefiting from the intrinsic materials and architectures features, the unique binder‐free NiCo2O4/carbon textiles exhibit high specific capacity/capacitance, excellent rate capability, and cycling stability.

Two-dimensional NiCo2O4nanosheet-coated three-dimensional graphene networks for high-rate, long-cycle-life supercapacitors

“…45,46,56 In addition, although good cycling performance has been achieved for NiCo 2 O 4 , it suffers from low capacitance, especially the high-rate capacitance. 14,54,57 In this work, the supercapacitor performances of NiCo 2 O 4 NS/3DGN, especially the rate capability and long-term cycling stability, are much better than those of many other pseudocapacitor electrode materials (Table S1 in ESI †). The excellent electrochemical performances of NiCo 2 O 4 NS/3DGN could be ascribed to the following factors.…”

“…The pseudocapacitor undergoes reversible redox reaction that occurs in the electrode materials, such as metal oxides (RuO 2 , MnO 2 , Co 3 O 4 , NiCo 2 O 4 , CoMoO 4 , etc.) [7][8][9][10][11][12][13][14][15][16] and metal hydroxides (Co(OH) 2 , Ni(OH) 2 , etc. ); [17][18][19] it stores more charges and provides higher specific capacitance than does the EDLC.…”

Three-dimensional-networked NiCo2S4 nanosheet array/carbon cloth anodes for high-performance lithium-ion batteries

“…The irreversible capacity loss for the first cycle can be attributed to the formation of an SEI layer and possible incomplete restoration of metallic Ni and Co into the original sulfide, an effect that has been commonly observed in NiCo 2 O 4 electrode materials. 22,35 In the second and third cycles, the discharge capacities of the electrode decreased to 1912 mAh g − 1 and 1891 mAh g − 1 , respectively, and the corresponding Coulombic efficiency increased to 98.1% and 98.8%, respectively. The sharp increase in Coulombic efficiency indicates that a stable SEI layer had already formed during the initial cycles.…”

“…16,17 Recently, direct growth of self-supported NiCo 2 O 4 nanowires and ZnCo 2 O 4 nanowire arrays on current-collecting substrates has been shown to overcome the drawbacks of mixing active electrode materials with conductive additives and binders and to increase endurance of fast charge and discharge processes. 22,23 Furthermore, it has been reported that 3D network structures (for example, graphene networks, 7 MO/3D graphene network composites 24 and diamond/ carbon nanotubes 25 ) can provide open channels for efficient electron/ ion transport and large surface area for reactions, both of which are favorable properties for materials and devices used in electrochemical applications. In this work, we report the synthesis of 3D-networked NiCo 2 S 4 nanosheet arrays (NSAs) directly on carbon cloth and their application as an anode material in LIBs; to our knowledge, this is the first such demonstration.…”

Integrating large specific surface area and high conductivity in hydrogenated NiCo2O4 double-shell hollow spheres to improve supercapacitors

“…On the one hand, large specific surface area will provide more electroactive sites for the Faradaic reactions, and load more doublelayer charges. Along such idea, many kinds of nanomaterials, [9][10][11] especially hollow spheres, 12 have been developed to improve pseudocapacitors, but the increased contact resistance often emerges in these porous materials. On the other hand, increasing conductivity will greatly favor the Faradaic reactions, which has been demonstrated typically in the integration of oxides with metal foam, 13 carbon cloth, 9 graphene and carbon nanotubes.…”