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a-c Various examples of electronic devices powered by two wire-type hybrid supercapacitors in series: a digital image of a the green, white, and red LED indicators, b LCD devices with various colors, and c a thermometer and hygrometer and a wearable electrical watch. d CV curves at a scan rate of 50 mV s −1 and e capacitance retention (the inset is the galvanostatic discharge curves at a current density of 5 A g −1 ) of single wire supercapacitor when subjected to various bending conditions. f-i Digital camera images of two wire-type supercapacitors connected in series at different bending conditions: f flat, g bent at > 150°, h crumpled, and i recovered condition
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The flexible 3D porous structure with a large surface area provides pathways for rapid ion/electron transport and ion diffusion as well as numerous electroactive sites.The wire-shaped supercapacitor exhibits a high energy density of 153.3 Wh kg−1 and a power density of 8810 W kg−1.The hybrid device demonstrates excellent durability under various me...
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... surface of the electrode and lower interfacial resistance, which is beneficial for abundant electrochemical reactions with gel polymer electrolyte ions in the compact electrode. A cross-sectional view of the NiCo LDH/3D-Ni nanostructure electrode at different magnifications is shown in Figs. S2, S3. XRD and XPS spectra of NiCo LDH are shown in Fig. ...
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... ability of the supercapacitor for powering various portable electronic devices (The electrochemical data are shown in Fig. S31). The device efficiently powered 5-mm-diameter green (3.5 V, 20 mA), white (3.5 V, 20 mA), and red (2.3 V, 20 mA) round light-emitting diode (LED) indicators after being charged for tens of seconds at 3.6 V, as shown in Fig. 4a. In addition, the red LED remained very bright after 30 min and was even able to operate as an indicator after 80 min (Movie S1 and Fig. S22). Figure 4b shows the LCD devices operating as indicators for temperature, time, alarm, and stop watch, which verifies that our devices are operating perfectly. The flexible supercapacitor also ...
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... addition, the red LED remained very bright after 30 min and was even able to operate as an indicator after 80 min (Movie S1 and Fig. S22). Figure 4b shows the LCD devices operating as indicators for temperature, time, alarm, and stop watch, which verifies that our devices are operating perfectly. The flexible supercapacitor also successfully powered an electrical watch and a thermometer and hygrometer, as shown in Fig. 4c, suggesting the strong potential of our supercapacitor in any portable and wearable device. ...
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... able to operate as an indicator after 80 min (Movie S1 and Fig. S22). Figure 4b shows the LCD devices operating as indicators for temperature, time, alarm, and stop watch, which verifies that our devices are operating perfectly. The flexible supercapacitor also successfully powered an electrical watch and a thermometer and hygrometer, as shown in Fig. 4c, suggesting the strong potential of our supercapacitor in any portable and wearable device. In order to demonstrate the flexibility of our device for smart wearable and implantable applications, we obtained the CV curves of the hybrid supercapacitors at 50 mV s −1 with a bending angle from 0° to 150°, as shown in Figs. 4d and S23. The ...
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... of our supercapacitor in any portable and wearable device. In order to demonstrate the flexibility of our device for smart wearable and implantable applications, we obtained the CV curves of the hybrid supercapacitors at 50 mV s −1 with a bending angle from 0° to 150°, as shown in Figs. 4d and S23. The shape of the CV curves and FE-SEM images ( Fig. S24) with various bending angles reveals that there is no significant difference, indicating the excellent mechanical stability for flexible energy storage system. When the flat wire supercapacitor device was severely bent at over 150°, crumpled, and recovered back to 0° in sequence, over 88% capacitance of the recovered device was ...
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... various bending angles reveals that there is no significant difference, indicating the excellent mechanical stability for flexible energy storage system. When the flat wire supercapacitor device was severely bent at over 150°, crumpled, and recovered back to 0° in sequence, over 88% capacitance of the recovered device was retained as shown in Figs. 4e and S25, S26. Furthermore, we measured charge/ discharge profiles in the device with/without bending conditions and calculated coulombic efficiency as a function of the current density as shown in Fig. S27. As a demonstration of the practical potential of our flexible supercapacitor, we powered green LED lights by the hybrid supercapacitors under ...
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... discharge profiles in the device with/without bending conditions and calculated coulombic efficiency as a function of the current density as shown in Fig. S27. As a demonstration of the practical potential of our flexible supercapacitor, we powered green LED lights by the hybrid supercapacitors under various deformation conditions, as shown in Fig. 4fi. All the devices successfully lit the LED, and the light was still bright when the device was returned to the initial condition, revealing that deformation had nearly no effect on the high performance of the flexible hybrid supercapacitor. These results prove the superior electrochemical performance and mechanical endurance of the ...
Citations
... The corresponding highresolution spectra of Ni 2p, Co 2p and O 1 s are given in Fig. 3e, respectively. There are two major peaks located at 855.5 eV (Ni 2p 3/2 ) and 873.1 eV (Ni 2p 1/2 ) in the Ni 2p spectrum together with two shake-up satellite peaks (Fig. 3c), which indicate the existence of Ni 2? [32,33]. For the XPS spectrum of Co 2p in Fig. 3d, there are also two shake-up satellite peaks, and the peaks at 781.9 and 797.3 eV are attributed to Co 2? while the peaks at 780.4 and 796.1 eV belong to Co 3? , suggesting the coexistent of Co 2? and Co 3? in the sample [34][35][36]. ...
For wearable electronics, flexible supercapacitors with shape memory function can better meet the needs of practical applications. Herein, the porous Ni and NiCo-layered double hydroxide (NiCo-LDH) nanosheets were electrodeposited on the shape memory alloy wire (SMAW) to obtain the wire-shaped NiCo-LDH@Ni@SMAW electrodes with excellent electrochemical performance and shape memory ability. The maximum specific capacity of the electrode reaches 515.0 C g–1 at 0.2 A g–1. The shape memory supercapacitor (SMSC) assembled by the NiCo-LDH@Ni@SMAW positive electrode and the activated carbon fiber yarn negative electrode exhibits good flexibility and excellent shape memory performance, which can return to the original shape within a few seconds and has a high capacitance retention of 81.5% after 50 shape recovery cycles. In addition, the SMSC also shows high energy density (136.6 μWh cm–2), power density (36 mW cm–2) and cycling stability (92.5% capacitance retention after 10,000 cycles).
Graphical Abstract
... Emerging flexible electronic devices are well developed in recent years, such as smart textiles, soft robotics and biosensors [220][221][222][223]. Further paradigm shift should be the seamless integration of flexible devices with flexible ESSs. ...
As a new generation of Zn-ion storage systems, Zn-ion hybrid supercapacitors (ZHSCs) garner tremendous interests recently from researchers due to the perfect integration of batteries and supercapacitors. ZHSCs have excellent integration of high energy density and power density, which seamlessly bridges the gap between batteries and supercapacitors, becoming one of the most viable future options for large-scale equipment and portable electronic devices. However, the currently reported two configurations of ZHSCs and corresponding energy storage mechanisms still lack systematic analyses. Herein, this review will be prudently organized from the perspectives of design strategies, electrode configurations, energy storage mechanisms, recent advances in electrode materials, electrolyte behaviors and further applications (micro or flexible devices) of ZHSCs. The synthesis processes and electrochemical properties of well-designed Zn anodes, capacitor-type electrodes and novel Zn-ion battery-type cathodes are comprehensively discussed. Finally, a brief summary and outlook for the further development of ZHSCs are presented as well. This review will provide timely access for researchers to the recent works regarding ZHSCs.
... The Ragone plot, i.e. energy density (Wh kg −1 ) vs power density (W kg −1 ), is a chart used to compare the performance of various energy storage devices. Hence, it is needless to say that the improvement of energy density, without sacrificing the power output and cyclic stability, remains a crucial turning point in realizing the potential of ECs as primary power sources [6,7]. Generally, ECs comprise of electrode materials, negative and positive electrodes, electrolyte and separators. ...
Development of novel nanostructured composites is of current interest for application as electrode materials. In this regard, an attempt has been made to synthesize NiCo 2 O 4 @V 2 O 5 nanocomposite and compare its charge storage performance with pristine NiCo 2 O 4 nanoparticles. HR-SEM micrographs reveal a mesoporous nanobelt like morphology of the nanocomposite with a BET surface area of ~65 m ² g ⁻¹ and average mesopore size centered on ~7.55 nm. Electrochemical measurements performed on both samples anticipate capacitive behavior with quasi-reversible redox reactions. However, NiCo 2 O 4 @V 2 O 5 is found to demonstrate strikingly high specific capacity of 194 mAh g ⁻¹ (1742 F g ⁻¹ ) at 1 A g ⁻¹ along with a notable capacity retention of ~90 % even after 3000 charge –discharge cycles and Coulombic efficiency >97 % at 5 A g ⁻¹ . These features are much superior to the properties of pristine NiCo 2 O 4 nanoparticles. The results obtained in this work ascertain functional robustness of NiCo 2 O 4 @V 2 O 5 nanocomposites as electrode materials in supercapacitors.
... Nickel foam (Ni foam) can be used as a substrate, since it possesses higher surface area and enhanced electrical conductivity [52][53][54][55]. The porous nature of nickel provides excellent mechanical strength and allows the usage of the electrolyte in supercapacitor devices for charge transportation [56]. Also, the substrate allows high mass loading by enhancing the bond strength. ...
Supercapacitors appear to be attractive options for energy storage due to their high power density and lengthy cycling life. This work is focused on the design of reduced graphene oxide/hexagonal boron nitride (rGO/h-BN), via a hydrothermal method, as electrode materials for supercapacitor applications. Interestingly, the composite with rGO/h-BN 50:50 showed good capacity when compared to other ratios. Similarly, asymmetric supercapacitor devices were made up of rGO/h-BN and rGO as positive and negative electrodes, respectively, and nickel foam and stainless steel were used as a substrate. The nickel foam as substrate exhibits a high capacitance retention of 90% after 1000 cycles in a coin-cell configuration compared to stainless-steel substrate (71% after 500 cycles). Interestingly, a significant enhancement in the capacitance of Co3O4 was observed when incorporated with rGO/h-BN composite. The asymmetric supercapacitor made up of rGO/h-BN/Co3O4 delivered a good capacitance retention of 78% at 150 mA/g, after 5,000 cycles. As a result, h-BN/rGO-based composites with superlattice were synthesized using a hydrothermal approach as prospective materials for next-generation supercapacitor applications.
Graphical abstract
... As a key electrode, transition metal oxide-based materials have been commonly employed to produce parallel-structured fiber-shaped SCs [47]. For example, Kang et al. [50] fabricated a hybrid flexible fiber-shaped SCs with a parallel structure based on nickel-cobalt layered double hydroxide (NiCo LDH)/3D Ni and 3D-manganese oxide (Mn 3 O 4 /3D-Ni). The fabrication process and structure configuration of (NiCo LDH)/3D Ni is schematically illustrated in Figure 4.3a [50]. ...
... For example, Kang et al. [50] fabricated a hybrid flexible fiber-shaped SCs with a parallel structure based on nickel-cobalt layered double hydroxide (NiCo LDH)/3D Ni and 3D-manganese oxide (Mn 3 O 4 /3D-Ni). The fabrication process and structure configuration of (NiCo LDH)/3D Ni is schematically illustrated in Figure 4.3a [50]. Initially, 3D-Ni porous structures were constructed on Ni wire surfaces by electrodeposition using the hydrogen bubble template process. ...
This chapter summarizes the recent developments in flexible fiber‐shaped supercapacitors (FFSCs). It discusses the emerging techniques for the fabrication of fiber‐shaped electrodes and highlights the three kinds of active materials for the fabrication of fiber electrodes, including carbon‐based materials, single/bi‐metal oxide‐based materials, and composite/hybrid materials. FFSCs have immense promise to be conveniently combined with other fiber‐shaped energy harvesting devices such as nanogenerators, solar cells, sensors into multipurpose systems. The chapter introduces recent strategies for the production of binder‐free 1D fiber electrodes based on wet‐spinning, electro‐spinning, spray/cast‐coating methods, electrodeposition method, and hydrothermal methods. It describes common electrode and electrolyte designs, device specifications, and manufacturing methods. To attain outstanding strength and good electrochemical efficiency with small size, carbon‐based fibers are commonly used as current collectors and also active materials to produce FFSCs. Improving electrochemical performance is indeed an important step for the revelation of feasible FFSCs implementations.
... It is important to highlight that the main advantage of our 3D porous architecture is that it offers a much higher interior surface area compared to other substrates such as Ni foams or bers. This principle is evidenced by the value of volumetric capacity of our NiCo-LDH@Ni-NTNW electrode which was 2.5-fold that of the NiCo LDH/3D-Ni electrode (13.56 mAh cm À3 ) at 0.5 mA, which is based on thick Ni wires as a substrate, as recently reported in ref. 63 . The outstanding volumetric capacities of our NiCo-LDH@Ni-NTNW electrode are markedly superior and surpass most of the recently reported NiCo-based battery-type electrodes; moreover, it delivers higher/comparable gravimetric and areal capacities as presented in Table S1. ...
High-performancing yet thin hybrid supercapacitors (HSC) are urgently needed to meet the increasing demands of wearable and portable electronic devices. Nevertheless, most of the current electrode designs employed to enhance...
... LDH//Mn3O4 hybrid supercapacitor exhibits a specific capacitance of 342 F·g -1 , keeps 80.7% after 10000 cycles (Kang and Ramadoss 2020). Although a gel electrolyte commonly has a lower conductivity than an aqueous one, it can stop the structural damage of electrode materials, improving long-time cycling performance. ...
Layered double hydroxides (LDH) possess anionic lamellar structures whose surface properties are strongly depending on the types and contents of their trivalent (M3+) bivalent metal (M2+). They can be synthesized by almost similar procedures, but specific operating conditions and chemical composition of the starting gels are determined by the targeted applications. This chapter is an attempt to provide fundamentals for researchers and both academic and industrial scientists. It contains 28 pages text with four tables and twelve figures that allow correlating the surface properties to these applications based on an ample literature.
... The obtained initial equivalent resistance of the Ni 10 /NCO/RGO electrode is lower than the initial resistances obtained for NiCo 2 O4 and NiCo 2 O 4 /MnO 2 hierarchical nanostructure electrodes in our previous research work [60]. Moreover, the initial equivalent resistance of the Ni 10 /NCO/RGO electrode is comparable with that of 3D-nickel cobalt-layered double hydroxide onto the 3D-nickel wire (NiCo LDH/3D-Ni) and the Co(OH) 2 @Ni(OH) 2 /3D-Ni/NW electrode reported by Kang et al. [61] and Sharifi et al. [62], respectively. The initial resistance of the Ni 10 /NCO/RGO electrode is much smaller than the Ni/NCO electrode ( Figure S9), which shows the importance of RGO in lowering the resistance of RGO. ...
In this work, we report surface-modified nickel (Ni) wire/NiCo2O4/reduced graphene oxide (Ni/NCO/RGO) electrodes fabricated by a combination of facile solvothermal and hydrothermal deposition methods for wire-shaped supercapacitor application. The effect of Ni wire etching on the microstructural, surface morphological and electrochemical properties of Ni/NCO/RGO electrodes was investigated in detail. On account of the improved hybrid nanostructure and the synergistic effect between spinel-NiCo2O4 hollow microspheres and RGO nanoflakes, the electrode obtained from Ni wire etched for 10 min, i.e., Ni10/NCO/RGO exhibits the lowest initial equivalent resistance (1.68 Ω), and displays a good rate capability with a volumetric capacitance (2.64 F/cm3) and areal capacitance (25.3 mF/cm2). Additionally, the volumetric specific capacitance calculated by considering only active material volume was found to be as high as 253 F/cm3. It is revealed that the diffusion-controlled process related to faradaic volume processes (battery type) contributed significantly to the surface-controlled process of the Ni10/NCO/RGO electrode compared to other electrodes that led to the optimum electrochemical performance. Furthermore, the wire-shaped supercapacitor (WSC) was fabricated by assembling two optimum electrodes in-twisted structure with gel electrolyte and the device exhibited 10 μWh/cm3 (54 mWh/kg) energy density and 4.95 mW/cm3 (27 W/kg) power density at 200 μA. Finally, the repeatability, flexibility, and scalability of WSCs were successfully demonstrated at various device lengths and bending angles.
... However, there are many advantages, but energy density savings in supercapacitors are much lower than batteries. Various efforts have been devoted to high quality research to transform these supercapacitors into primary power sources and increase their power and energy efficiency [3,4]. The specific capacitance of suitable electrode materials and their increasing voltage is a common approach used to improve the energy density of supercapacitors. ...
New attractive advances in electrode preparation for supercapacitor applications with rGO based composite materials are eye-catching attention of researchers. Cobalt oxide is considered as an effective electrode for full cell fabrication due to its high specific capacitance. Cost effective solvothermal method was used to prepare pristine Co3O4 nanorods, NiCo2O4 nanorods and NiCo2O4/rGO urchin like nanocilia structure composite materials. The complete electrochemical studies were used to check the obtained product electrochemical activity. The high specific capacitance values are obtained for NiCo2O4/rGO urchin like nanocilia composite electrode material which leads to design a full cell and make use as practical applications with illuminating red, green, blue LED source. The capacitive retention of 92.28% even after 5000 cycles achieved in GCD cyclic performance at a high current density implies its excellent stability.
