Supercapacitors have attracted enormous attention for energy storage in both academic and industrial sectors in the past years. In this study, all‐solid‐state flexible asymmetric supercapacitors (ASCs) without any binder, incorporated with the hydrophilic carbon cloth (HCC) with MnO2nanocomposite (HCC@MnO2) as the positive electrode, the HCC with polypyrrole (PPy) (HCC@PPy) as the negative electrode, and polyvinyl alcohol (PVA)–LiCl gel as both gel electrolyte and separator, are reported. The HCC@MnO2and HCC@PPy electrodes are prepared by direct deposition of either MnO2nanoparticles or PPy nanofilms on the HCC through a simple, facile, and controllable electrochemical deposition method, respectively. The HCC@MnO2and HCC@PPy electrodes provide rich contact area for gel electrolyte, facilitating the rapid delivery of electrolyte ions, and also minimize the resistance of ASCs. As a result, all‐solid‐state flexible binder‐free HCC@MnO2//HCC@PPy ASCs exhibit a large operating voltage of 1.8 V, high energy density of 28.2 Wh kg−1at the power density of 420.5 W kg−1, and excellent cycling stability (91.2% capacitance retention after 5000 cycles). The present study provides a facile, scalable, and efficient approach to fabricate all‐solid‐state ASCs with high electrochemical storage performance for flexible electronics.
A three‐dimensional (3D) hollow CoWO4composite grown on Ni‐foam (3D−H CoWO4/NF) based on a flower‐like metal‐organic framework (MOF) is designed by utilizing a facile dipping and hydrothermal approach. The 3D−H CoWO4/NF not only possesses large specific areas and rich active sites, but also accommodates volume expansion/contraction during charge/discharge processes. In addition, the unique structure facilitates fast electron/ion transport of 3D−H CoWO4/NF. Meanwhile, a series of characterization measurements demonstrate the appropriate morphology and excellent electrochemical performance of the material. The 3D−H CoWO4/NF possesses a high specific capacitance of 1395 F g−1, an excellent cycle stability with 89% retention after 3000 cycles and superior rate property. Furthermore, the 3D−H CoWO4/NF can be used as a cathode to configurate an asymmetric supercapacitor (ASC), and 3D−H CoWO4/NF//AC shows a good energy density (29.0 W h kg−1). This work provides a facile method for the preparation of 3D‐hollow electrode materials with high electrochemical capability for advanced energy storage devices.
more » « less- NSF-PAR ID:
- 10154578
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Chemistry – An Asian Journal
- Volume:
- 15
- Issue:
- 11
- ISSN:
- 1861-4728
- Page Range / eLocation ID:
- p. 1750-1755
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
null (Ed.)Lithium metal–selenium (Li–Se) batteries offer high volumetric energy but are limited in their cycling life and fast charge characteristics. Here a facile approach is demonstrated to synthesize hierarchically porous hollow carbon spheres that host Se (Se@HHCS) and allow for state-of-the-art electrochemical performance in a standard carbonate electrolyte (1 M LiPF 6 in 1 : 1 EC : DEC). The Se@HHCS electrodes display among the most favorable fast charge and cycling behavior reported. For example, they deliver specific capacities of 442 and 357 mA h g −1 after 1500 and 2000 cycles at 5C and 10C, respectively. At 2C, Se@HHCS delivers 558 mA h g −1 after 500 cycles, with cycling coulombic efficiency of 99.9%. Post-mortem microstructural analysis indicates that the structures remain intact during extended cycling. Per GITT analysis, Se@HHCS possesses significantly higher diffusion coefficients in both lithiation and delithiation processes as compared to the baseline. The superior performance of Se@HHCS is directly linked to its macroscopic and nanoscale pore structure: the hollow carbon sphere morphology as well as the remnant open nanoporosity accommodates the 69% volume expansion of the Li to Li 2 Se transformation, with the nanopores also providing a complementary fast ion diffusion path.more » « less
-
more » « less
Abstract A local electric field is induced to engineer the interface of vanadium pentoxide nanofibers (V2O5‐NF) to manipulate the charge transport behavior and obtain high‐energy and durable supercapacitors. The interface of V2O5‐NF is modified with oxygen vacancies (Vö) in a one‐step polymerization process of polyaniline (PANI). In the charge storage process, the local electric field deriving from the lopsided charge distribution around Vö will provide Coulombic forces to promote the charge transport in the resultant Vö‐V2O5/PANI nanocable electrode. Furthermore, an ≈7 nm porous PANI coating serves as the external percolated charge transport pathway. As the charge transfer kinetics are synergistically enhanced by the dual modifications, Vö‐V2O5/PANI‐based supercapacitors exhibit an excellent specific capacitance (523 F g−1) as well as a long cycling lifespan (110% of capacitance remained after 20 000 cycles). This work paves an effective way to promote the charge transfer kinetics of electrode materials for next‐generation energy storage systems.
-
more » « less
Abstract A simple and facile method was developed to fabricate functional bulk barium titanate (BaTiO3,
BT ) ceramics using the paste extrusion 3D printing technique. TheBT ceramic is a lead‐free ferroelectric material widely used for various applications in sensors, energy storage, and harvesting. There are several traditional methods (eg, tape casting) to process bulkBT ceramics but they have disadvantages such as difficult handing without shape deformation, demolding, complex geometric shapes, expansive molds, etc. In this research, we utilized the paste extrusion 3D printing technique to overcome the traditional issues and developed printable ceramic suspensions containingBT ceramic powder, polyvinylidene fluoride (PVDF ), N,N‐dimethylformamide (DMF ) through simple mixing method and chemical formulation. ThisPVDF solution erformed multiple roles of binder, plasticizer, and dispersant for excellent manufacturability while providing high volume percent and density of the final bulk ceramic. Based on empirical data, it was found that the maximum binder ratio with good viscosity and retention for desired geometry is 1:8.8, while the maximumBT content is 35.45 vol% (77.01 wt%) in order to achieve maximum density of 3.93 g/cm3(65.3%) for 3D printedBT ceramic. Among different sintering temperatures, it was observed that the sinteredBT ceramic at 1400°C had highest grain growth and tetragonality which affected high performing piezoelectric and dielectric properties, 200 pC/N and 4730 at 103 Hz respectively. This paste extrusion 3D printing technique and simple synthesis method for ceramic suspensions are expected to enable rapid massive production, customization, design flexibility of the bulk piezoelectric and dielectric devices for next generation technology. -
more » « less
Abstract The electrochemical nitrate reduction reaction (NO3RR) to ammonia is an essential step toward restoring the globally disrupted nitrogen cycle. In search of highly efficient electrocatalysts, tailoring catalytic sites with ligand and strain effects in random alloys is a common approach but remains limited due to the ubiquitous energy-scaling relations. With interpretable machine learning, we unravel a mechanism of breaking adsorption-energy scaling relations through the site-specific Pauli repulsion interactions of the metal
d -states with adsorbate frontier orbitals. The non-scaling behavior can be realized on (100)-type sites of ordered B2 intermetallics, in which the orbital overlap between the hollow *N and subsurface metal atoms is significant while the bridge-bidentate *NO3is not directly affected. Among those intermetallics predicted, we synthesize monodisperse ordered B2 CuPd nanocubes that demonstrate high performance for NO3RR to ammonia with a Faradaic efficiency of 92.5% at −0.5 VRHEand a yield rate of 6.25 mol h−1g−1at −0.6 VRHE. This study provides machine-learned design rules besides thed -band center metrics, paving the path toward data-driven discovery of catalytic materials beyond linear scaling limitations.
