Showing papers on "Electroplating published in 2020"

2D Metal Zn Nanostructure Electrodes for High‐Performance Zn Ion Supercapacitors

Abstract: Recent supercapacitors show a high power density with long‐term cycle life time in energy‐powering applications. A supercapacitor based on a single metal electrode accompanying multivalent cations, multiple charging/discharging kinetics, and high electrical conductivity is a promising energy‐storing system that replaces conventionally used oxide and sulfide materials. Here, a hierarchically nanostructured 2D‐Zn metal electrode‐ion supercapacitor (ZIC) is reported which significantly enhances the ion diffusion ability and overall energy storage performance. Those nanostructures can also be successfully plated on various flat‐type and fiber‐type current collectors by a controlled electroplating method. The ZIC exhibits excellent pseudocapacitive performance with a high energy density of 208 W h kg−1 and a power density from 500 W kg−1, which are significantly higher than those of previously reported supercapacitors with oxide and sulfide materials. Furthermore, the fiber‐type ZIC also shows high energy‐storing performance, outstanding mechanical flexibility, and waterproof characteristics, without any significant capacitance degradation during bending tests. These results highlight the promising possibility of nanostructured 2D Zn metal electrodes with the controlled electroplating method for future energy storage applications.

Tailoring desolvation kinetics enables stable zinc metal anodes

Abstract: Low-cost and high-safety aqueous Zn ion batteries have been considered as promising alternatives to Li-ion batteries, provided that a stable Zn metal anode could be developed. Dendrite growth and low coulombic efficiency (CE) are the primary two issues afflicting the design of advanced Zn metal anodes. Inspired by complexing agents in the electroplating industry, acetonitrile (AN) is proposed as an electrolyte additive to guide the smooth growth of Zn. The enhanced intermolecular interactions between Zn2+ and mixed H2O/AN solvents lead to the supersaturating of adatoms on the current collector, as revealed by the complementary theoretical and experimental studies. Consequently, homogeneous nucleation and smooth growth of Zn are enabled for achieving exceptional stability up to 1000 cycles with an excellent CE of 99.64% on average. Application-wise, the incorporation of a complexing agent into the electrolyte is fully compatible with the cathode while maintaining the non-flammable nature for safe operation. The solvation chemistry regulation strategy provides a promising route to stabilize Zn metal anodes.

Revisiting the Electroplating Process for Lithium-Metal Anodes for Lithium-Metal Batteries

Abstract: Electroplating has been studied for centuries, not only in the laboratory but also in industry for machinery, electronics, automobile, aviation, and other fields. The lithium-metal anode is the Holy Grail electrode because of its high energy density. But the recyclability of lithium-metal batteries remains quite challenging. The essence of both conventional electroplating and lithium plating is the same, reduction of metal cations. Thus, industrial electroplating knowledge can be applied to revisit the electroplating process for lithium-metal anodes. In conventional electroplating, some strategies like using additives, modifying substrates, applying pulse current, and agitating electrolyte have been explored to suppress dendrite growth. These methods are also effective in lithium-metal anodes. Inspired by that, we revisit the fundamental electroplating theory for lithium-metal anodes in this Minireview, mainly drawing attention to the theory of electroplating thermodynamics and kinetics. Analysis of essential differences between traditional electroplating and plating/stripping of lithium-metal anodes is also presented. Thus, industrial electroplating knowledge can be applied to the electroplating process of lithium-metal anodes to improve commercial lithium-metal batteries and the study of lithium plating/stripping can further enrich the classical electroplating technique.

Facile and low-cost synthesis route for graphene deposition over cobalt dendrites for direct methanol fuel cell applications

Abstract: In this work, standalone cobalt dendrites are prepared then doped with graphene flakes by a simple electroplating technique. Microstructural examination using SEM with EDX, as well as Raman spectroscopy measurements, verified the successful formation of graphene. The prepared material exhibit a favorably high electrochemical methanol oxidation activity with an onset oxidation potential of 0.07 V vs. Ag/AgCl, which is significantly lower than that of the Ni (0.35 V vs. Ag/AgCl). The doping process causes a decrease in the ohmic resistance of the material from 3.2 Ohm cm−2 to 2 Ohm cm−2, which consequently resulted in a significant increase in the current density from 35 mA cm−2 to 62 mA cm−2 using 1 M methanol at 0.5 V vs. Ag/AgCl. After two hours of current discharge at 0.5 V vs. Ag/AgCl, the catalyst doped with graphene showed a current density of 62 mA cm−2. This is an eight-times higher than that obtained in the case of the Ni nano-powder. An electrode prepared by depositing the catalyst on the surface of a highly conductive porous Ni foam was successfully used as the anode of a passive air cathode direct methanol fuel cell, demonstrating an open circuit voltage of 0.75 V using 0.25 M methanol in 1 M KOH.

Alternative tribological coatings to electrodeposited hard chromium: a critical review

Abstract: The traditional importance of hard chromium electroplating in surface engineering is recognised and the key features of this well-established technology are summarised. Despite the high hardness, c...

Towards improved electroplating of metal-particle composite coatings

Abstract: The electrodeposition of composite coatings containing included particles in a metal matrix dates back, at least, to the 1920s. The process involves both electroplating of metal and electrophoretic...

Development of hybrid metallic coatings on carbon fiber-reinforced polymers (CFRPs) by cold spray deposition of copper-assisted copper electroplating process

Abstract: Metallization of polymeric materials such as carbon fiber-reinforced polymers (CFRPs) by the cold spray technique has gained significant interest to enhance their electrical conductivity. Copper is a very good electrical conductor, which makes it favorable for applications that require high electrical conductivity. However, previous studies showed that continuous copper coatings could not be fabricated directly on CFRPs by cold spraying. In this study, a hybrid fabrication process was used to enable cold spray deposition of copper onto CFRPs, making them electrically conductive. The CFRP substrate was first metallized with an electroless Ni coating; subsequently, a thick copper layer was electroplated onto the Ni interlayer. Copper was then cold spray deposited onto the electroplated CFRP as well as on a Cu control panel. Deposition efficiency (DE) of the cold-sprayed coatings was measured for both the CFRP and the control Cu coupons to determine optimal deposition conditions. Surface and cross-sectional morphologies of the coated CFRP were investigated, and both the electroplated CFRP and control panels were characterized for mechanical properties and surface roughness before cold spray deposition. The electrical resistivity of the cold-sprayed CFRPs was evaluated. It was found that the DE of copper particles is sensitive to the surface characteristics of the substrate. The electrical resistivity of the cold-sprayed coatings was slightly higher than that of the bulk copper due to porosity and small defects on the coating surface. The results suggest that Cu coatings can be successfully fabricated onto CFRPs if a copper inter-layer is present. This layer not only protects the CFRP from any possible damage, but also improves the cold sprayability of copper particles as compared to the conventional cold spraying copper powder/copper panel due to its favorable mechanical, thermal and surface properties. The fabricated coatings can serve as conductive surfaces for application as lightning strike protection coatings.

Kirigami-Inspired Flexible and Stretchable Zinc-Air Battery Based on Metal-Coated Sponge Electrodes.

Abstract: The development of efficient and low-cost flexible metal electrodes is significant for flexible rechargeable zinc–air batteries (ZABs). Herein, we reported a new type of flexible metal (zinc and ni...

Upcycling of Electroplating Sludge to Prepare Erdite-Bearing Nanorods for the Adsorption of Heavy Metals from Electroplating Wastewater Effluent

Abstract: Electroplating sludge is a hazardous waste produced in plating and metallurgical processes which is commonly disposed of in safety landfills. In this work, electroplating sludge containing 25.6% Fe and 5.5% Co (named S1) and another containing 36.8% Fe and 7.8% Cr (S2) were recycled for the preparation of erdite-bearing particles via a facile hydrothermal route with only the addition of Na2S·9H2O. In the sludges, Fe-containing compounds were weakly crystallized and spontaneously converted to short rod-like erdite particles (SP1) in the presence of Co or long nanorod (SP2) particles with a diameter of 100 nm and length of 0.5–1.5 μm in the presence of Cr. The two products, SP1 and SP2, were applied in electroplating wastewater treatment, in which a small portion of Co in SP1 was released in wastewater, whereas Cr in SP2 was not. Adding 0.3 g/L SP2 resulted in the removal of 99.7% of Zn, 99.4% of Cu, 37.9% of Ni and 53.3% of Co in the electroplating wastewater, with residues at concentrations of 0.007, 0.003, 0.33, 0.09 and 0.002 mg/L, respectively. Thus, the treated electroplating wastewater met the discharge standard for electroplating wastewater in China. These removal efficiencies were higher than those achieved using powdered activated carbon, polyaluminum chloride, polyferric sulfate or pure Na2S·9H2O reagent. With the method, waste electroplating sludge was recycled as nanorod erdite-bearing particles which showed superior efficiency in electroplating wastewater treatment.

Selective recovery of Cr from electroplating nanosludge via crystal modification and dilute acid leaching

Abstract: We investigated the selective recovery of Cr from electroplating sludge, which is vital for minimizing environmental pollution and recycling metal resources. In electroplating sludge, Cr, Ni, Cu, and other heavy metals coexist as amorphous nanosized particles, promoting their simultaneous dissolution during traditional concentrated acid leaching and hindering their stepwise recovery. Fortunately, based on their nanosized and amorphous properties, the modification and growth of nanocrystals become practicable, which could cause different solubilities for different metal compound crystals in leaching. Therefore, this study aimed to introduce a calcination and dilute acid leaching method for modifying the crystals/phases of heavy metal compounds and inducing their different acid-dissolution kinetics. The screening revealed NaOH as the optimal additive for recovering 90.2% of Cr from an electroplating sludge with a purity (relative concentration in the leachate) of 96.4%. Investigation of the extraction mechanism demonstrated that calcination of the sludge with NaOH oxidized most Cr(III) compounds to Na2CrO4 and CaCrO4 with high acid solubility. Meanwhile, amorphous Ni and Cu compounds were transformed into NiO and CuO nanocrystals (about 100 nm) with lower kinetics of acid-dissolution. This study indicates the feasibility of “crystal modification” for selective recovery of Cr from electroplating sludge, which overcomes the nonselectivity of the concentrated acid leaching method and highlights a new approach for recovering heavy metals from other nanosludge.

Evaluation of TiO2 Nanoparticles Concentration and Applied Current Density Role in Determination of Microstructural, Mechanical, and Corrosion Properties of Ni–Co Alloy Coatings

Abstract: The goal of the present investigation is to evaluate the influences of plating parameters such as TiO2 nanoparticles concentration in the plating bath and applied current density on the microstructure-related and mechanical properties as well as corrosion behavior of Ni–Co coatings. The coatings were fabricated by different current densities and TiO2 nanoparticles concentration over the range 2–8 A dm–2 and 0–30 g/L, respectively. Results demonstrate that the incorporation of TiO2 nanoparticles into the plating bath coupled with the change in current density can deeply affect the microstructure-related, mechanical properties as well as corrosion resistance of Ni–Co coatings. According to the results, Ni–Co–20 g/L TiO2 coatings electroplated at current density of 4 A dm–2 shows the superior properties. The synergistic effects of higher Co amount coupled with the higher volume fraction of TiO2 throughout the microstructure of the coating is responsible for the above-mentioned improvements.