Structure Of Current Collector Research Articles

The Fabrication of Freestanding Heterogeneous Copper-Tin Films with Meniscus Brush Plating Electrodeposition

A meniscus brush plating electrodeposition technique was utilized in conjunction with a post deposition heat treatment to formulate freestanding copper-tin alloy films for negative electrodes of lithium-ion batteries. The described fabrication technique intertwined the electrode and current collector for improved cell volume utilization and stability. Two designs were examined to establish the best diffusivity to form electrochemically proficient copper-tin alloys. Fabrication was optimized to promote diffusion of copper and tin and to form the desired intermetallic phase of Cu6Sn5. This improved design fabricated films with competitive areal capacities above 1000 mAh/cc and 2.5 mAh/cm2 for the complete electrode and current collector structure.

Superior high-rate capability of hierarchically structured flower-like magnetite–carbon–graphene composite for Li-ion anode

A nano/micro hierarchical composite structure is prepared by solvothermal synthesis from iron alkoxide in an inert atmosphere. It consists of graphene sheet and flower-like Fe3O4 particle covered by carbon coating (designated as Fe3O4@C). The synthesized composite is an excellent anode for Li-ion batteries. This is attributed to its double structure of current collector. High reversible lithium storage capacity (1439 mA h/g at 0.2 C after 47 cycles) and superior high-rate capability (619 mA h/g at 5 C) are examples of this property. The carbon coating of the Fe3O4@C is in direct contact with the Fe3O4 particles to form local conductive connections, Fe3O4@C tightly covering graphene sheets can be employed as the current collector as well as bridge connection of the Fe3O4@C particles. Therefore, the double structure of current collector can form superior-conductivity networks, providing an efficient electron transport between active materials and Cu current collectors. This double structure prevents the break down of electric connection between the active material and the current collector during protracted cycles of charge and discharge.

Current Collector Based on Thin Metal Layer for Flexible Lithium-Ion Batteries

Flexible lithium battery is an emerging and promising technology for the next generation of flexible devices in various applications such as rollup displays, smart cards, wireless sensors, and wearable computers. Flexible lithium battery requires a mechanical durability against repeated deformation that commonly occurs in flexible electronic devices.Current collector of commercial lithium-ion battery is made of metallic foil. Metallic foil current collector often suffers from the generation of gap between electrode material and current collector interface under the bending and folding situation, resulting in capacity loss or poor performance at high rate. Thus, a novel metallic structure of current collector is highly needed to improve the performance of flexible lithium battery.Here we introduce a novel thin metal layer current collector based on flexible polymeric substrate using RF-magnetron sputtering method. Acknowledgement This research was supported by the Converging Research Center Program through the Ministry of Science, ICT and Future Planning, Korea(2013K000288). Reference 1. J.-Y. Choi, D. J. Lee, Y. M. Lee, Y.-G. Lee, K. M. Kim, J.-K. Park, K. Y. Cho, Adv. Funct. Mater., 2013, 23, 2108.2. J. H. Yun, G.-B. Han, Y. M. Lee, Y.-G Lee, K. M. Kim, J.-K. Park, and K. Y. Cho, Electrochemical and Solid-State Letters, 2011, 14, A116.3. E.-H. Kil, K.-H. Choi, H.-J. Ha, S. Xu, J. A. Rogers, M. R. Kim, Y.-G. Lee, K. M. Kim, K. Y. Cho, and S.-Y. Lee, Adv. Mater., 2013, 25, 1395.

LiB Electrode Ageing Observed from PVdF Binder

Ageing behaviors of the positive electrode of lithium ion battery are characterized by measuring mechanical properties of the electrode reeds, such as resonance frequency and internal friction, as a function of temperature. In the measurements of the electrode reeds with a sandwich structure of active material film and current collector of Al foil, two thermally-activated relaxation processes can be observed on the polyvinylidene difluoride binder in the active material film. Namely, a surface-related relaxation at ~150 K and a relaxation corresponding to the β-phase transition at ~240 K in the polymer binder can be observed at high signal/noise ratio. The resonance frequency decreases and the internal friction increases after charge/discharge cycling. The changes in activation energies of the relaxation processes also indicate that the measurement of mechanical properties of the positive electrode is an effective method for characterizing ageing behaviors of the positive electrode as a whole.

3D aligned-carbon-nanotubes@Li2FeSiO4 arrays as high rate capability cathodes for Li-ion batteries

3D aligned-carbon-nanotubes (ACNTs)@Li2FeSiO4 nanocomposite arrays on Al foil were developed as cathode materials for Li-ion batteries. The ACNTs were grown directly on an Al foil by a chemical vapor deposition method to achieve a 3D current collector structure for direct charge transport. Li2FeSiO4 nanoparticles were deposited on the surface of the ACNTs by a polyvinylalcohol (PVA)-assisted sol–gel method. The 3D samples showed a high degree of alignment of nanotubes with a favorable pore morphology before and after cycling. According to electrochemical measurements, the 3D sample with optimized mass ratio of ACNTs and Li2FeSiO4 (2:1) showed excellent rate capability and capacity retention, delivering a discharge specific capacity of 142 mAh g−1 at a rate of 0.5 C (C = 160 mAg−1) and maintaining 99% of the initial discharge capacity after 50 cycles at 24 ° C. Up to 20 C, the delivered charge/discharge capacity was 94 mAh g−1 after 172 cycles, which is 54% of the value obtained at C/20 (175 mAh g−1). In comparison, carbon coated nanoporous Li2FeSiO4 obtained under analogous conditions by a PVA-assisted sol–gel method can only deliver a capacity of 80 mAh g−1 and showed poor rate capability. In addition, despite amorphization, dissolution and chemical composition changes occurring in the 3D samples upon extended cycling, the 3D samples showed good long-term cycling stability at a high current density (5 C), maintaining ∼80% of the initial discharge capacity after 1000 cycles and ∼70% after 2000 cycles.

Three-dimensional network current collectors supported Si nanowires for lithium-ion battery applications

Three-dimensional (3D) conductive network electrodes based on commercial nickel foam current collector supported Si nanowires (SiNWs) with carbon coating are evaluated as lithium-ion battery anodes. The Ni foam network current collector achieves a high silicon loading up to 5mg/cm2, without using any non-conductive binders. The pressed carbon coated SiNWs–Ni electrode shows outstanding electrochemical performance. It achieves an initial capacity of as high as 2486mAh/g. A reversible capacity of 1500mAh/g is still retained even after 50 cycles of charging and discharging. The good performance could be attributed to the 3D Ni–C network current collector structure that provides flexible room to effectively accommodate the volume change of Si nanowires and minimizes loss of electrical contact after long time cycling. The 3D composite network provides a new design principle of robust and scalable lithium-ion battery electrodes that can effectively relieve the significant volume change problem.

Novel positive electrode architecture for rechargeable lithium/sulfur batteries

The lithium/sulfur battery is a very promising technology for high energy applications. Among other advantages, this electrochemical system has a high theoretical specific capacity of 1675mAhg−1, but suffers from several drawbacks: poor elemental sulfur conductivity, active material dissolution and use of the highly reactive lithium metal electrode. More particularly, the discharge capacity is known to be dictated by the short lithium polysulfide precipitation. These poorly soluble and highly insulating species are produced at the end of discharge, and are responsible for the positive electrode passivation and the early end of discharge. Nevertheless, the discharge capacity can be improved by working on the positive electrode specific surface area and morphology, as well as on the electrolyte composition. In this paper, we focused on the positive electrode issue. To this purpose, various current collector structures have been tested in order to achieve a high positive electrode surface area and a stable morphology during cycling. We demonstrated that the discharge capacity could be increased up to 1400mAhg−1 thanks to the use of carbon foam. As well, the capacity fading could be dramatically decreased in comparison with the one obtained for conventional sulfur composite electrodes.

3D Self‐Supported Nanoarchitectured Arrays Electrodes for Lithium‐Ion Batteries

Three‐dimensional self‐supported nanoarchitectured arrays electrodes (3DSNAEs) consisting of a direct growth of nanoarchitectured arrays on the conductive current collector, including homogeneous and heterogeneous nanoarchitectured arrays structures, have been currently studied as the most promising electrodes owing to their synergies resulting from the multistructure hybrid and integrating heterocomponents to address the requirements (high energy and power density) of superperformance lithium ion batteries (LIBs) applied in portable electronic consumer devices, electric vehicles, large‐scale electricity storage, and so on. In the paper, recent advances in the strategies for the fabrication, selection of the different current collector substrates, and structural configuration of 3DSNAEs with different cathode and anode materials are investigated in detail. The intrinsic relationship of the unique structural characters, the conductive substrates, and electrochemical kinetic properties of 3DSNAEs is minutely analyzed. Finally, the future design trends and directions of 3DSNAEs are highlighted, which may open a new avenue of developing ideal multifunctional 3DSNAEs for further advanced LIBs.

Effect of Anode and Cathode Current-Collector Structure on Performance of a Passive Direct Methanol Fuel Cell

In this work, the effect of the current-collector structure on the performance of a passive direct methanol fuel cell (DMFC) was investigated. Parallel current-collector (PACC) and other two kinds of perforated current collectors (PECC) were designed, fabricated and tested. The studies were conducted in a passive DMFC with active membrane area of 9 cm2, working at ambient temperature and pressure. Two kinds of methanol solution of 2 M and 4 M were used. Results showed that the PACC as anode current-collector has a positive effect on cell voltage and power. For the cathode current-collector structure, the methanol concentration of 2 M for PECC-2 (higher open ratio 50.27 %) increased performance of DMFC. But the methanol concentration of 4 M led to an enhancement of fuel cell performance that used PACC or PECC-2 as cathode current-collector.

Nanostructured materials for the construction of asymmetrical supercapacitors

Mechanically robust power devices of high energy efficiency are one of the keys towards overcoming the challenges from the daunting climate change and the depletion of fossil fuels on the earth. The importance of mechanical engineering has been long recognized in physical type power devices, but less so in those based on electrochemical processes, such as batteries, fuel cells, and electrochemical capacitors (ECs). Particularly, ECs, which are also known as supercapacitors, bridge the crucial performance disparity between fuel cells or batteries with high energy capacities and the traditional capacitors capable of outputting pulsed high power. New materials and advanced configurations are the two essential elements for ECs to cope with mechanical engineering issues at both macro and micro levels. This review describes the design and characteristics of ECs and the emerging asymmetrical construction utilizing nanostructured composites that enable energy storage through both ion adsorptions (interfacial capacitance) and fast and reversible redox reactions (pseudo-capacitance). It is specially intended to rouse interest towards newly reported high-energy and high-power aqueous ECs with nanocomposites of transition metal oxides, nitrides or conducting polymers, and carbon nanotubes or activated carbons. Current collector materials and structures are also examined as important mechanical engineering elements in ECs. The chemical, material, and mechanical issues reviewed here call for more joined efforts among scientists, engineers, and industries to further advance ECs as a promising new energy technology.

Thin Film Nano Solar Cells—From Device Optimization to Upscaling

Stainless steel based dye solar cells have been upscaled from small, laboratory size test cells of 0.32 cm2 active area to 6 cm x 6 cm "mini-modules" with active areas ca. 15 cm2. Stainless steel works as the photoelectrode substrate whilst the counter electrode is prepared on indium-doped tin oxide coated polyethyleneterephtalate or polyethylenenaphtalate plastic foil (fluorine-doped tin oxide coated glass as a reference). Additional current collector structures were deposited on the counter electrode substrate with inkjet-printing of silver nanoparticle ink in order to reduce the lateral resistance of the plastic foil. Flexible substrates enable roll-to-roll type industrial manufacturing of the cells and the steel's superior conductivity compared to the typical substrate materials such as glass and plastic makes it possible to prepare even substantially larger modules. The best efficiencies obtained this far with the "mini-module" using a stainless steel photoelectrode are 2.5% with a platinum-sputtered indium-doped tin oxide coated polyethyleneterephtalate counter electrode and 3.4% with a thermally platinized fluorine-doped tin oxide coated glass counter electrode. These efficiencies are on the same level than those measured with small cells prepared with similar methods and materials (3.4%-4.7%, depending on configuration, which are amongst the highest reported for this kind of a dye solar cell). Replacing expensive conducting glass with steel and plastic foils as the substrate materials leads also to economical savings in the cell production.

Effects of the nickel-coated ferritic stainless steel for solid oxide fuel cells interconnects

In this study, a protective nickel layer was prepared on the SUS430 alloy substrate by the atmospheric plasma spraying technology (APS). Oxidation kinetics, area specific resistance (ASR) and interfacial microstructure of the SUS430 alloy with nickel layers as well as its elemental composition were studied under the flowing humidified hydrogen atmosphere at 800 °C to evaluate the effectiveness of the protective nickel layer. The current collector between the interconnect and the anode was optimized in this paper. Results showed that the oxide growth rate constant of the SUS430 alloy with the APS nickel layer was 1.99 × 10 −14 g 2 cm −4 s −1, which was only one fiftieth of that of the alloy without a protective layer. The ASR of the SUS430 alloy with the APS nickel layer was 12 mΩ cm 2 after being oxidized under the simulated SOFC anode operating atmosphere at 800 °C for 250 h. With the optimized structure of current collector, the contact ASR between the nickel-coated interconnect and the Ni-YSZ anode was only 3 mΩ cm 2 after being oxidized at 800 °C for 100 h.

A high-throughput study of PtNiZr catalysts for application in PEM fuel cells

The effects of adding Zr to PtNi oxygen reduction reaction (ORR) electrocatalyst alloys were examined in a study aimed at probing the possibility of creating catalysts with enhanced resistance to corrosion in a PEM fuel cell environment. Samples consisting of pure Pt or PtNiZr alloys with a range of compositions (not exceeding 11 at.% Zr) were fabricated using co-sputter deposition. A high-throughput fabrication approach was used wherein 18 distinct thin film catalyst alloy samples with varying compositions were deposited onto a large-area substrate with individual Au current collector structures. A multi-channel pseudo-potentiostat allowed for the simultaneous quantitative study of catalytic activity for all 18 electrodes in a single test bath, a first for the study of ORR electrocatalysts. A properly stirred oxygenated 1 M H 2SO 4 electrolyte solution was used to provide each electrode with a steady-state flow of reactants during electrochemical evaluation. The onset potentials, absolute current density values, and Tafel analysis data obtained using this technique were compared with literature reports. The analyses showed that most PtNiZr alloys tested offered improvements over pure Pt, however those surfaces with a high mole fraction (>4 at.%) of Zr exhibited reduced activity that was roughly inversely correlated to the amount of Zr present. Film composition, morphology, and crystallographic properties were examined using X-ray energy dispersive spectroscopy (XEDS), X-ray photoelectron spectroscopy (XPS), SEM, and synchrotron X-ray diffraction. These data were then correlated with electrochemical data to elucidate the relationships between composition, structure, and relative performance for this ternary system.

Effect of current-collector structure on performance of passive micro direct methanol fuel cell

The effect of current-collector structure on the performance of a passive micro direct methanol fuel cell (DMFC) is reported. The system consists mainly of a membrane electrode assembly, two current-collectors, two gaskets and two end-plates. It does not include any pump and the delivery of fuel and air is realized completely by natural convection and diffusion, which significantly decreases the complexity and lowers the cost of the micro DMFC. The performance of the micro DMFC with different current-collectors is tested and compared. The results indicate that the exposure ratio of the anode current-collector should be higher than that of the cathode counterpart to ensure good fuel delivery at the anode and to minimize the contact resistance at the cathode.

Possible improvements in making carbon electrodes for organic supercapacitors

Abstract Properties of an Electrical Double Layer Capacitor depend both on the technique used to prepare the electrode and on the current collector structure. Capacitors can be built in a similar way to prismatic cells, with several electrodes connected in parallel for each polarity. Our Electrical Double Layer Capacitors included several carbon/carbon electrodes and all the components (electrodes and separators) were wetted with an organic liquid solvent containing a quaternary ammonium salt as electrolyte. In the present work, electrodes were prepared by two different ways: the first one consisted in spraying a liquid suspension of the electrode materials on a nickel foil, and the second one which consisted in filtering and pressing the electrode materials on to nickel collectors. The first technique allowed us to build seven capacitors of 600 F–2.5 V, with time constants of 12 s. Two banks with series connected supercapacitor cells, one as a 12 V–100 F bank and the other one as a 15 V–85 F were tested on cycling. In our experiments to test these banks of supercapacitors, we also coupled the 100 F–12 V bank to a 12 V–7 Ah secondary lead–acid battery in order to demonstrate the contribution of the supercapacitors during power peaks. Comparing the two techniques used to make the electrodes in terms of performances obtained on the supercapacitors prepared, we obtained the best results by using the second method of electrode preparation. Moreover, two kinds of nickel collectors were studied: expanded nickel grids—and various grades of nickel foams, nickel foams giving the best results. The Equivalent Series Resistance of the electrodes prepared with nickel foams depends on nickel foam grade; it is observed to be 1.75 Ω for a capacitance of 1.37 F in our experimental set up, leading to a time constant of 2.4 s. The mechanical properties of the electrodes were improved as well.