A comparative study of supercapacitive performances of nickel cobalt layered double hydroxides coated on ZnO nanostructured arrays on textile fibre as electrodes for wearable energy storage devices

Abstract

We demonstrated an efficient method for the fabrication of novel, flexible electrodes based on ZnO nanoflakes and nickel-cobalt layered double hydroxides (denoted as ZnONF/NiCoLDH) as a core-shell nanostructure on textile substrates for wearable energy storage devices. NiCoLDH coated ZnO nanowire (denoted as ZnONW/NiCoLDH) flexible electrodes are also prepared for comparison. As an electrode for supercapacitors, ZnONF/NiCoLDH exhibits a high specific capacitance of 1624 F g(-1), which is nearly 1.6 times greater than ZnONW/NiCoLDH counterparts. It also shows a maximum energy density of 48.32 W h kg(-1) at a power density of 27.53 kW kg(-1), and an excellent cycling stability with capacitance retention of 94% and a Coulombic efficiency of 93% over 2000 cycles. We believe that the superior performance of the ZnONF/NiCoLDH hybrids is due primarily to the large surface area of the nanoflake structure and the open spaces between nanoflakes, both of which provide a large space for the deposition of NiCoLDH, resulting in reduced internal resistance and improved capacitance performance. Our results are significant for the development of electrode materials for high-performance wearable energy storage devices.

Integration of nickel–cobalt double hydroxide nanosheets and polypyrrole films with functionalized partially exfoliated graphite for asymmetric supercapacitors with improved rate capability

“…The good charge storage kinetics of FEG/Ni-Co DH was also supported by CV results (Figure S3a). This superior rate capability of FEG/Ni-Co DH electrode is better or comparable to those of other reported Ni-Co DH composites which integrated with carbon or other 3D substrates with comparable loading density, such as Co x Ni 1-x (OH) 2 integrated in graphene foam (1847 F/g at 5 A/g and 1268 F/g at 60 A/g with 68.6% retention, ~0.09 mg/cm 2 ), 16 NiCoAl-LDH nanoplates/NiCo-carbonate hydroxide on graphite paper (1297 F/g at 1A/g and 764 F/g at 30 A/g, with 59% retention, 1~1.5 mg/cm 2 ), 28 Ni-Co LDHs on ZnO nanowires (1624 F/g at 10 A/g and 1331 F/g at 50 A/g with 82% retention, 0.9 mg/cm 2 ), 29 and Ni-Co LDH nanoflakes/ZnO nanowires integrated with carbon cloth (1927 F/g at 2 A/g and 1546 at 30 A/g with 81% retention, 0.98 mg/cm 2 ). This is scarcely observed with scan rate higher than 100 mV/s for Ni and Co hydroxides, as well as their double hydroxides.…”

Hierarchical Ni–Co layered double hydroxide nanosheets entrapped on conductive textile fibers: a cost-effective and flexible electrode for high-performance pseudocapacitors

“…[13][14][15][16][17][18] In fact, pseudocapacitors are able to store more charge and offer higher specific capacitance values than the EDLCs due to the continuous reversible redox reactions in electroactive materials. [25][26][27][28][29] However, they are somewhat expensive, and a relatively complicated fabrication process would be required to manufacture these substrates which may impede their practical applications in wearable energy storage devices. [21][22][23][24] To date, versatile and flexible electrodes including carbon textile, carbon fiber, gold layered fabric, and CNT coated cotton textile/paper substrates have been used as electrodes in pseudocapacitors owing to their good flexibility, light weight, good sustainability, and foldable nature.…”

Hierarchical layered double hydroxide nanocomposites: structure, synthesis and applications

“…Researchers have found that the synthesised 3D hierarchical core@LDH architectures possess these properties, and show excellent supercapacitive performance in terms of capacitance, energy density, and the cycling rate. 44,54,70 With different synthesis methods applied (such as deposition and sol-gel), these core@LDH architectures always have vertically orientated or mixed platelet morphology which allows the nanocomposite to form porous structure and enlarge the surface area to the maximum extent. 44,54,70 The different interior hierarchy structures (SiO 2 @LDH core-shell, yolk-shell, and hollow LDH shell) have also been compared in their supercapacitive performance.…”

“…44,54,70 With different synthesis methods applied (such as deposition and sol-gel), these core@LDH architectures always have vertically orientated or mixed platelet morphology which allows the nanocomposite to form porous structure and enlarge the surface area to the maximum extent. 44,54,70 The different interior hierarchy structures (SiO 2 @LDH core-shell, yolk-shell, and hollow LDH shell) have also been compared in their supercapacitive performance. Shao et al showed that the hollow NiAl-LDH structure had greatly improved faradaic redox reaction and mass transfer, and exhibited excellent pseudocapacitance performance because of the large surface area of the hollow structure, which provides effective diffusion channels for the electrolyte ions.…”