Nickel Template Research Articles

Lightweight, freestanding hybrids of graphene and hexagonal boron nitride foams

Lightweight boron carbon nitride foams which are a hybrid of graphene and hexagonal boron nitride (hBN), are produced using the nickel template method and remain freestanding after the etching of nickel without the stabilization of a polymer during etching. Chemical vapor deposition (CVD) precursors with varying carbon content were utilized, but only a 10% range of carbon atomic percentage variation is observed in the resulting boron carbon nitride foams due to the high carbon solubility of nickel. However, the cooling rate during the CVD process has a much more significant effect on the carbon content. Moreover, a 6.5-fold increase in resistivity is observed for our foams compared to a graphene foam with an overall trend of decreasing resistance with increasing carbon content. Furthermore, when the foam is infiltrated with epoxy to form a composite at 0.3% volumetric percentage concentration, there is a 27% increase in the thermal conductivity over hBN foam composites. These foams are suitable to use as a substitute for graphene foams when a lower electrical conductivity is desired and could potentially be used as a thermal interface material if a higher pore density nickel template is utilized.

Multilayer Si@SiOx@void@C anode materials synthesized via simultaneously carbonization and redox for Li-ion batteries

In the development of high-performance lithium-ion batteries (LIBs), the composition and structure of electrode materials are of critical importance. Silicon has a theoretical specific capacity 10 times that of graphite, nonetheless, its application as an anode material confronts challenge as it undergoes huge volume change and pulverization amidst the alloying and dealloying processes. Herein, a novel method to prepare a multilayer Si-based anode was proposed. Three layers, SiO2, nickel and triethylene glycol (TEG), were coated successively on Si nanoparticles, which served respectively as the sources of SiOx, sacrificial templates and carbon. Nickel can not only serve as a hollow template, but also play a catalytic role, which makes carbonization and redox reactions occur synchronously under a mild condition. Amid the carbonization process of TEG at 450 °C, several-nm-thick SiO2 layer can react with the as-derived carbon to form a silicon suboxides (SiOx (0 < x < 2)) intermedium layer. After removing the nickel template, a micro-nano scaled Si@SiOx@void@C with conformal multilayer-structure can be obtained. The BET specific surface area and pore volume of powders were increased dramatically because of the derivation of abundant voids, which can not only buffer the swelling effect of silicon, but also provide richer ionic conductivity. The as-assembled half-cell with Si@SiOx@void@C as the anode material possesses high capacity (∼1000 mAh g−1 at 3 A g−1), long cycle life (300 cycles with 77% capacity retention) and good rate performance (558 mAh g−1 at 5 A g−1).

Electrodeposition of palladium-dotted nickel nanowire networks as a robust self-supported methanol electrooxidation catalyst

Mass activity and long-term stability are two major issues in current fuel cell catalyst designs. While supported catalysts normally suffer from poor long-term stability but show high mass activity, unsupported catalysts tend to perform better in the first point while showing deficits in the latter one. In this study, a facile synthesis route towards self-supported metallic electrocatalyst nanoarchitectures with both aspects in mind is outlined. This procedure consists of a palladium seeding step of ion track-etched polymer templates followed by a nickel electrodeposition and template dissolution. With this strategy, free-standing nickel nanowire networks which contain palladium nanoparticles only in their outer surface are obtained. These networks are tested in anodic half-cell measurements for demonstrating their capability of oxidising methanol in alkaline electrolytes. The results from the electrochemical experiments show that this new catalyst is more tolerant towards high methanol concentrations (up to {5},hbox{mol},hbox{L}^{-1}) than a commercial carbon supported palladium nanoparticle catalyst and provides a much better long-term stability during potential cycling.Graphical

Si nanoparticles veiled with ultrathin rGO film reduced directly by precoated Ni template: Fabrication and electrochemical performance

Si/graphene composite has been considered as a promising structure to limit the volume expansion and improve poor conductivity of silicon anode. Herein, a novel method to prepare Si/reduced graphene oxide (Si/rGO) composite anode was proposed. With this approach, nickel shell was pre-coated on Si particles via electroless deposition before used as a template to in-situ reduce GO. During the reduction process, the nickel template can as well promote the self-assembly of graphene sheets on the surface of Si nanoparticles. Following these facile and convenient processes, a Si/rGO hybrid-structure can be directly fabricated. Compared with pure Si anode, this Si/rGO composite displays a greatly improved electrochemical performance in both cycling stability and rate capability. It delivers a reversible capacity as high as 975 mA h g−1 and 717 mA h g−1 after 300 cycles under the current densities of 1 A g−1 and 3 A g−1, respectively. Meanwhile, its capacity can still maintain at 602 mA h g−1 even at a rather higher current of 5 A g−1.

Assembly of Si@Void@Graphene Anodes for Lithium‐Ion Batteries: In Situ Enveloping of Nickel‐Coated Silicon Particles with Graphene

AbstractIn this report, a yolk‐shell‐structured Si/graphene (Si/GR) material has been designed and successfully fabricated as an anode for lithium‐ion batteries (LIBs). With this approach, Si@Ni composite particles were fabricated by electroless deposition of a nickel template directly on silicon; then, three‐dimensional (3D) graphene layers were grown in situ around the composite particles to obtain a Si@Ni@GR structure. After removing the nickel interlayer, some voids were generated between the silicon particles and the graphene layers, thus forming a Si@void@GR structure. The coexistence of voids and the graphene layer may provide a synergistic effect. The voids may reserve space for silicon particles during volume expansion and buffer the mechanical pressure of the graphene layer. Meanwhile, the graphene cover may enhance lithium‐ion transport efficiency and electron transport rate, thereby improving the electrical conductivity of the anode. The well‐coated layers can also prevent the Si particles from being directly exposed to electrolyte, which can promote the formation of a stable SEI film and reduce the irreversible consumption of Li+. Therefore, such unique yolk‐shell structures offer the resultant Si@void@GR electrode a high reversible discharge capacity (1595 mAh g−1 after 100 cycles at a current density of 500 mA g−1) and the capacity to deliver a discharge capacity of 990 mAh g−1 even at a high current density of 4.8 A g−1.

Biomimetic fabrication of micro-/nanostructure on polypropylene surfaces with high dynamic superhydrophobic stability

Recently, the biomimetic replication of micro-/nanostructure present on lotus leaves has attracted great interest. Unfortunately, the nanostructure on the surfaces of lotus leaves, which play a critical role in making them superhydrophobic and self-cleaning, are difficult to precisely replicate. Herein, a nickel replica is fabricated by electroless plating and electroplating with natural lotus leaf as natural template. Using the nickel template, lotus leaf-like structure is fabricated on polypropylene (PP) surfaces by injection molding, an industrially feasible technique for fast mass-fabrication. It is demonstrated that the micropapillae on the lotus leaf are successfully fabricated on the PP replica, especially nanohairs with sharp tips and high aspect ratio are developed without additional surface coating or chemical modification. The PP replicas exhibit a highly similar wettability with the lotus leaf. More interestingly, the nanohairs on the PP replica are superior to the nanotubules on the lotus leaf in terms of the dynamic superhydrophobic stability and superhydrophobic thermal durability. Impact droplet exhibits shorter contact time on the PP replica than the lotus leaf. Mechanisms for the functionalities of the nanohairs on the PP replica are analyzed. Such superior properties are expected to have industrial applications, such as anti-icing, microdroplet transfer, and self-cleaning.

Large-area flexible infrared nanowire grid polarizer fabricated using nanoimprint lithography.

We fabricated a 4-in large-area flexible infrared nanowire grid polarizer using a nanoimprint and metal thermal evaporation process. To protect the Si master template, as well as to prolong the service life of it, we first fabricated a nickel template as an alternative by an electroforming process. Then, the nanowire grid structure was transferred from this template to IPS substrate by a thermal nanoimprint process. Finally, Al was deposited on the IPS nanowire structure by vertical thermal evaporation technology. The results of the infrared optical test reveal that the TM transmittance of the polarizer is greater than 60% in the 4-5.71μm and 5.73-6.7μm wavelength ranges, and, especially, it is greater than 70% in the wavelength ranges of 4.70-5.69μm and 5.75-6.59μm. The extinction ratio is more than 20dB in the wavelength range of 3.6-6.7μm, proving that the polarizer has good polarization characteristics. The flexible infrared nanowire grid polarizer has potential applications in the fields of curved surface monitoring equipment and polarized imaging equipment.

Powder metallurgy template growth of 3D N-doped graphene foam as binder-free cathode for high-performance lithium/sulfur battery

Here, we present a facile technique to design self-supported 3D N-doped graphene foam (NGF) via simply annealing in chemical vapor deposition furnace which used powder metallurgy nickel template and melamine as both carbon and nitrogen source. The NGF possesses highly conductive and interconnected mesoporous network. Particularly nitrogen-doping provided strong polysulfide immobilization ability, significantly suppressing the shuttle effect. The NGF was directly used as binder-free electrode which delivered a high initial discharge capacity of 987 mA h g−1 and maintains at 819 mA h g−1 after 200 cycles at 0.2 C, corresponding to 82.9% capacity retention. Specifically, even at high current density of 2 C, it still possesses a good long life cycle performance (from 633.8 mA h g−1 to 440.3 mA h g−1 after 500 cycles, with ultralow capacity fading rate of 0.061% per cycle). 7Li nuclear magnetic resonance (7Li NMR) suggested strong interaction between NGF and polysulfide. Moreover, X-ray photoelectron spectroscopy and density function theory calculation further revealed the strong interaction mostly ascribed to chemisorption and physisorption of polysulfide by pyridinic and pyrrolic nitrogen, respectively. As we know this method-based NGF as binder free electrode was first reported, which provided an effective strategy for developing high-performance Li/S batteries.

Enhanced specific surface area and thermal conductivity in ultrathin graphite foams grown by chemical vapor deposition on sintered nickel powder templates

The specific surface area and effective thermal conductivity of ultrathin graphite foams (UGFs) grown by chemical vapor deposition (CVD) have been limited by the large pore sizes of reticulated nickel foam templates. Here we show that nickel templates formed by sintering of low-cost nickel powder can reduce pore size and increase specific surface area. Accordingly, the effective density of a free-stranding graphite foam grown on the high-surface area templates can be increased by an order of magnitude relative to one grown on a reticulated nickel foam template. This increase is accomplished without increasing the thickness of the CVD graphite or decreasing the structural quality of the graphite. Based on experiments with nickel powder with and without the reticulated nickel template present, we found that both the particle size and sintering temperature influenced template morphology. Because of a 68-times increase in the volumetric specific surface area of a graphite foam synthesized on a sacrificial sintered powder template compared to a UGF grown on a reticulated template, we have been able to increase the relative graphite density and effective thermal conductivity from 0.87 ± 0.09% to 8.4 ± 0.3% and from 2.1 ± 0.3 Wm−1K−1 to 16.3 ± 1.1 Wm−1K−1, respectively.

Three-Dimensional Porous Nickel Frameworks Anchored with Cross-Linked Ni(OH)2 Nanosheets as a Highly Sensitive Nonenzymatic Glucose Sensor

A facile and scalable in situ microelectrolysis nanofabrication technique is developed for preparing cross-linked Ni(OH)2 nanosheets on a novel three-dimensional porous nickel template (Ni(OH)2@3DPN). For the constructed template, the porogen of NaCl particles not only induces a self-limiting surficial hot corrosion to claim the "start engine stop" mechanism but also serves as the primary battery electrolyte to greatly accelerate the growth of Ni(OH)2. As far as we know, the microelectrolysis nanofabrication is superior to the other reported Ni(OH)2 synthesis methods due to the mild condition (60 °C, 6 h, NaCl solution, ambient environment) and without any post-treatment. The integrated Ni(OH)2@3DPN electrode with a highly suitable microstructure and a porous architecture implies a potential application in electrochemistry. As a proof-of-concept demonstration, the electrode was employed for nonenzymatic glucose sensing, which exhibits an outstanding sensitivity of 2761.6 μA mM-1 cm-2 ranging from 0.46 to 2100 μM, a fast response, and a low detection limit. The microelectrolysis nanofabrication is a one-step, binder-free, entirely green, and therefore it has a distinct advantage to improve clean production and reduce energy consumption.

Novel flower-like graphene foam directly grown on a nickel template by chemical vapor deposition

Novel dense graphene foams were fabricated by directly growing graphene on nickel templates by chemical vapor deposition. The as-grown graphene foam showed a hierarchical structure consisting of graphene microspheres with nano pores as flower-like morphology. The high quality of the graphene foam was confirmed by Raman spectrum and conductivity measurement as high as 5100 S m−1. To test its potential application in lithium ion battery, the monolithic graphene foam hybridized with TiO2 nanoparticles as anode material was synthesized via atomic layer deposition. The electrode exhibited high specific capacity (204 mAh g−1, 91 mAh g−1) even at high current (20 C, 60 C, respectively, 1 C = 335 mA g−1) with good stability and reversibility. The outstanding electrical performance could be attributed to the flower-like dense porous nanostructure in the graphene foam, which would work not only as a highly conductive host matrix for ion and electron transportation, but also effectively buffer the volume expansion during the lithiation and delithiation process.

Centimeter-sized epitaxial h-BN films

We report the growth and transfer of centimeter-sized, epitaxial hexagonal boron nitride (h-BN) few-layer films using Ni(111) single-crystal substrates. The h-BN films were heteroepitaxially grown on 10 × 10 mm2 or 20 × 20 mm2 Ni(111) substrates using atmospheric pressure chemical vapor deposition with a single ammonia-borane precursor. The grown films were transferred to arbitrary substrates via an electrochemical delamination technique, and the remaining Ni(111) substrates were repeatedly re-used. A careful analysis of the growth parameters revealed that the crystallinity and area coverage of the h-BN films were mostly sensitive to the sublimation temperature of the ammonia-borane source. Moreover, various physical characterizations confirmed that the grown films exhibited the typical characteristics of hexagonal boron nitride layers over the entire area. Furthermore, the heteroepitaxial relationship between h-BN and Ni(111) and the overall crystallinity of the film were thoroughly investigated using a synchrotron radiation X-ray diffraction analysis including θ–2θ scans, grazing incident diffraction, and reciprocal space mapping. The crystallinity at the microscopic scale was further investigated using transmission electron microscopy (TEM)-based techniques, including selective area electron diffraction pattern mapping, electron back-scattered diffraction, and high-resolution TEM. Transparent and flexible ceramic films for electronic devices can now be made at centimetre scales by a low-cost technique. Hexagonal boron nitride (h-BN) crystals are attractive platforms for building next-generation circuits because their flat, graphite-like surfaces resist mechanical and chemical damage while offering excellent signal isolation. Gyu-Chul Yi from Seoul National University and colleagues have developed a way to improve large-scale manufacturing of these films using a reusable nickel template. Nickel has a surface structure that helps h-BN films grow with high crystallinity following chemical vapor deposition, but detaching the resulting ceramic layer has always proved troublesome. The Korean team solved this problem through an electrochemical delamination process that seamlessly separates h-BN films with dimensions up to 20 × 20 square millimetres using a stream of hydrogen bubbles. Centimeter-sized, epitaxial hexagonal boron nitride (h-BN) few-layer films were heteroepitaxially grown on Ni(111) single-crystal substrates using atmospheric pressure chemical vapor deposition with ammonia-borane single precursor. The grown films were transferred to arbitrary substrates via an electrochemical delamination technique, and the remaining Ni(111) substrates were repeatedly re-used. Over repeated growth and transfer after the initial annealing, no significant degradation of Ni(111) substrates was observed and the crystallinity of h-BN layers was reproduced reliably. The grown h-BN films showed typical physical characteristics of h-BN, with a high uniformity over a wide area. The large-area synthesis and transfer of atomically thin uniform epitaxial h-BN layers can be applied in various fields where high quality two-dimensional insulating layers are required.

Activity and Durability of Iridium Nanoparticles in the Oxygen Evolution Reaction

Although electrochemical water splitting currently represents a small amount of the US hydrogen supply, its role is expected to grow with the emergence of a hydrogen-based infrastructure.[1] Electrolysis is reasonably cost-competitive with a variety of technologies, including batteries (solid state and flow), pumped hydro, and compressed air.[2] When coupled with renewable energy sources, such as wind and solar, electrochemical water splitting can produce hydrogen using a nearly carbon free pathway.[3] The commercial progress of electrolyzers is limited in part by the cost of the catalyst layer. The oxygen evolution reaction is the focus of electrocatalyst development due to slow kinetics relative to hydrogen evolution; iridium nanoparticles are commonly used to catalyse oxygen evolution, with platinum added to ensure conductivity throughout the catalyst layer. Extended surface nanostructures have previously been developed as electrocatalysts in hydrogen fuel cells, where they have produced an order of magnitude higher specific activity than nanoparticles in oxygen reduction and demonstrated a potential benefit in accelerated stress tests.[4] Extended nanostructures have recently been developed for the oxygen evolution reaction, where a similar specific activity improvement was observed in rotating disk electrode (RDE) half-cells. Catalysts formed by spontaneous galvanic displacement are ideally situated, being able to take advantage of the specific activities generally associated with the catalyst type, while significantly improving upon the traditionally low surface areas of extended surfaces. This approach has been used in forming iridium-nickel and iridium-cobalt nanowires.[5] While nanoparticles have modest site-specific activity in oxygen reduction and evolution, nanoparticle evolution catalysts are at a particular disadvantage with regards to surface area, since carbon supports cannot be used at high potentials. Iridium-cobalt and iridium-nickel nanowires have been synthesized with surface areas of 70 m2 gIr ‒ 1, more than double the nanoparticles. In RDE half-cells, the extended nanostructures produce an oxygen evolution mass activity 7 to 8 times greater throughout the kinetic region. Accelerated stress tests were completed by potential holds and cycling over a variety of conditions to study catalyst degradation and establish standardized testing protocols. Acid treatment has been used to remove excess nickel and cobalt template, improving catalyst durability. Following accelerated stress tests in RDE half-cells, iridium-cobalt and iridium-nickel nanowires exceed the mass activity of nanoparticles by more than an order of magnitude. Membrane electrode assembly (MEA) fabrication of these materials has produced electrolyzers with higher performance than the benchmark device. Recent improvements in MEA performance suggest that the promise of extended surface catalysts observed in half-cells can be realized in the application. [1] R. Forgie, G. Bugosh, K.C. Neyerlin, Z. Liu, P. Strasser, Electrochemical and Solid-State Letters, 13 (2010) B36-B39. [2] K. Harrison, M. Peters, in: U.S. Department of Energy (Ed.), http://www.hydrogen.energy.gov/pdfs/review13/pd031_harrison_2013_o.pdf, 2013. [3] K. Harrison, M. Peters, C. Ainscough, in: U.S. Department of Energy (Ed.), http://www.hydrogen.energy.gov/pdfs/progress13/ii_a_2_harrison_2013.pdf, 2013. [4] S.M. Alia, Y.S. Yan, B.S. Pivovar, Catalysis Science & Technology, 4 (2014) 3589-3600. [5] H. Xu, High-Performance, Long-Lifetime Catalysts for Proton Exchange Membrane Electrolysis, in: U.S. Department of Energy (Ed.), http://www.hydrogen.energy.gov/pdfs/review14/pd103_xu_2014_o.pdf, 2014. Figure 1. Surface areas (x-axis) and site-specific oxygen evolution activities (y-axis) of iridium-cobalt nanowires, iridium-nickel nanoparticles, and iridium nanoparticles prior to (red, blue, black) and following (dark red, dark blue, grey) durability testing in RDE half cells. Arbitrary mass activities (1, 4, 7 A mgIr ‒ 1) are included as solid black lines. Figure 1

Three-Dimensional Bicontinuous Graphene Monolith from Polymer Templates.

The two-dimensional single-layer and few-layered graphene exhibit many attractive properties such as large specific surface area and high charge carrier mobility. However, graphene sheets tend to stack together and form aggregates, which do not possess the desirable properties associated with graphene. Herein, we report a method to fabricate three-dimensional (3D), bicontinuous graphene monolith through a versatile hollow nickel (Ni) template derived from polymer blends. The poly(styrene)/poly(ethylene oxide) were used to fabricate a bicontinuous gyroid template using controlled phase separation. The Ni template was formed by electroless metal depositing on the polymer followed by removing the polymer phase. The resulting hollow Ni structure was highly porous (95.2%). Graphene was then synthesized from this hollow Ni template using chemical vapor deposition and the free-standing bicontinuous graphene monolith was obtained in high-throughput process. Finally, the bicontinuous graphene monolith was used directly as binder-free electrode in supercapacitor applications. The supercapacitor devices exhibited excellent stability.

Three-Dimensional Bi-Continuous Graphene Monolith from Hollow Ni Templates Via Polymer Templates

The stack of graphene sheets greatly reduces its exceptionally high specific surface area, which limits the potential utilization of graphene. Here in this work, we report a method to fabricate three-dimensional, bi-continuous graphene monolith through a controllable hollow Ni templates derived from polymer blends. The poly(styrene)/poly (ethylene oxide) were used to fabricate a bi-continuous gyroid template with controllable phase separation. The nickel template was formed by electroless depositing metal on the polymer and the resulting hollow nickel structure exhibited very high porosity of 95.15%. Graphene was synthesized from this hollow nickel template by chemical vapor deposition and the free-standing bi-continuous graphene monolith was obtained in high throughput. The bi-continuous graphene monolith was used in the energy storage devices and exhibited promising results. Figure 1

Fabrication of Microstructure on Nickel Template by Femtosecond Laser

This paper presents an experimental investigation into microfabrication of nickel template by femtosecond laser in air at atmospheric pressure. The laser pulses used for the study are 800 nm in wavelength, 100fs in pulse duration, and the repetition rate used is 1KHz. Micro-hole ablation experiments are carried out in air by focusing the femtosecond laser beam on the nickel target surface at normal incidence with the long-focus objective lens of enlargement factor 50 and NA=0.7. Dependence of the diameter, depth and depth-to-diameter ratio of the fabricated holes on the laser power and number of pulses are revealed experimentally. Microgrooves with good uniformity are fabricated on nickel template with femtosecond laser by optimizing the process parameters.

Investigation of Femtosecond Laser Ablation Threshold for Nickel Template

This paper presents a theoretical and experimental investigation into the ablation threshold of nickel template by femtosecond laser in air at atmospheric pressure. The laser pulses used for the study are 800 nm in wavelength, 100fs in pulse duration, and 1KHz in repetition rate. The two-temperature model is used to predict the single-pulse ablation threshold for nickel theoretically. Micro-hole ablation experiments are carried out in air by focusing the femtosecond laser beam on the nickel target surface at normal incidence with the long-focus objective lens of enlargement factor 50 and NA=0.7 to determine the single-pulse and multi-pulse ablation thresholds for nickel by setting up the relationship between the measured hole diameters and the pulse energies. The single pulse ablation threshold of 4132.98 Jm-2obtained experimentally is very close to that of 3907.99 Jm-2predicted by two-temperature model. The incubation factorξ, which describes the changes of the multi-pulse ablation thresholds with the number of pulses, is determined to be 0.812 for nickel.

Fabrication of Periodic Microstructures on Nickel Template by Multi-Beam Laser Interference

Complex microstructures can be fabricated on nickel template directly by femtosecond laser. But the efficiency is low and much time is inevitable when large scale microstructures are fabricated. The multi-beam interference provides an effective method for fabrication of large scale microstructures. This paper mainly focuses on direct ablation of nickel template by four-beam interference and fabricating periodic microstructures by laser interference lithography. Experimental results show that submicron periodic stripes and column structures can be produced on the nickel template by laser interference, laying the foundation of making nickel molds for microfluidic chips.

3D-graphene for electrocatalysis of oxygen reduction reaction: Increasing number of layers increases the catalytic effect

Oxygen reaction reaction (ORR) is of enormous importance for energy storage and generation devices. Graphene offers catalytic properties towards ORR; however, its performance is often hindered by restacking of the graphene sheets. Here we show that mechanically rigid 3D graphene deposited on nickel template can act as efficient catalyst for ORR. We compare electrocatalytic activity of double, triple and few-layer 3D graphene. We show that the multilayer 3D graphene exhibits higher electrocatalytic activity than the other two samples towards ORR. These findings shall have a dramatic impact on the construction of graphene based fuel cells and batteries.

Solid flexible electrochemical supercapacitor using Tobacco mosaic virus nanostructures and ALD ruthenium oxide

An all-solid electrochemical supercapacitor has been developed using a nanostructured nickel and titanium nitride template that is coated with ruthenium oxide by atomic layer deposition (ALD). The electrode morphology was based on a high surface area biotemplate of genetically modified Tobacco mosaic virus. The biotemplate automatically self-assembles at room temperature in aqueous solution. Nafion® perfluorosulfonate ionomer dispersion was cast on the electrodes and used as a solid proton-conducting electrolyte. A 5.8 F g−1 gravimetric capacity (578 µF cm−2 based on footprint) was achieved in Nafion electrolyte, and the device retained 80% of its capacity after 25 000 cycles. The technology presented here will enable thin, solid, flexible supercapacitors that are compatible with standard microfabrication techniques.