Stainless Steel Current Collectors Research Articles

Multifunctional polymeric coating on stainless steel current collectors in aqueous energy storage devices

Herein, low cost stainless steel foils are employed as current collectors in aqueous Na-ion supercapacitors, while the foils are coated with following conducting polymers, namely, polyimide (PI), Schiff base polymer (SBP), polyanthraquinone sulfide (PAQS) and polyaniline (PANI). The foremost purpose of these polymeric coatings is the prevention of corrosion, and the resultant improvements in device performances. Notwithstanding, these polymeric coatings provide few additional benefits in device characteristics, and these are following: (i) enhancement of electrolyte stability window, (ii) contributing charge storage capacitance, (iii) conversion of 2D pristine substrate to 3D porous current collector. The four coating polymers are electrochemically characterized, and PI is selected for fabricating Na-ion supercapacitor cells. The PI-coating reduces the stainless steel’s corrosion rate ∼ 68 times, expands the electrolyte stability window ∼ 1.2 times, and delivers ∼ 2 times higher capacitance with respect to pristine current collector, whereas no appreciable interfacial resistances are observed. The supercapacitor cell with PI-functionality demonstrates ∼ 6.6 times improved capacitance than that of pristine cell at 25 mA/g current density, while > 95 and ∼ 90 % Faradaic efficiencies are noted for former and latter, respectively. The distinct enhancement of cell performances clearly demonstrates the effectiveness of multifunctional polymeric coating on corrosion-prone metallic current collectors.

Developing High-Purity Sodium Oxychloride Solid-State Electrolyte for Sodium-Ion Batteries

Sodium-ion batteries have attracted significant attention as an alternative energy source to lithium-ion batteries. Solid-state sodium oxyhalides (Na3OX, X = Cl, Br, I) have the advantages of easy synthesis from cheap raw materials. In this study, sodium oxychloride (Na3OCl) antiperovskite was synthesized using a microwave furnace, the first instance in currently available literature. Using the microwave furnace also significantly decreased the reaction time when compared to other published procedures. The ionic conductivity of Na3OCl pellets was determined using electrochemical impedance spectroscopy (EIS). Na3OCl was hot pressed between sodiated hard carbon in a PEEK lined split cell with stainless steel current collectors. The symmetric cell was tested at room temperature with varying external pressures (1 MPa to 12 MPa). Symmetric cells were also tested at constant external pressure (6 MPa) from room temperature to 80˚C.Arrhenius plots demonstrated linear behavior in the whole temperature range with a calculated activation energy of 0.98 eV. The melting and crystallization temperatures were determined using differential scanning calorimetry (DSC). The purity of as-synthesized Na3OCl was evaluated using x-ray diffraction (XRD). The results on chemical composition and crystal-to-glass phase transformations were produced from in-situ X-ray diffraction (XRD) spectroscopy in the temperature range from 25˚C up to the melting point of Na3OCl. Cross-sectional SEM images of the Na3OCl pellets showed regions that were dense, but also regions with many pores (≤ 5 μm). SEM also showed microcracks that ranged from 1-5 μm. Future work will investigate methods of minimizing pores and microcracks during the cell manufacturing process as these surface features can impede efficient ionic movement.

Interfacial Insights into the Polarization Protocol: Toward Reducing Corrosion and Improving the Cycle Life of Electrochemical Capacitors.

The number of scientific publications on the impact of corrosion on current collectors on the working parameters of electrochemical capacitors is very limited. The aim of current research is to search for new, environmentally friendly chemical power sources and energy storage devices and to improve existing ones. Therefore, this article presents a simple and effective way to improve the life of a symmetric electrochemical capacitor by changing the direction of electrode polarization, which in turn inhibits the corrosion of the current collector. This slows the degradation of current collectors of positive electrode over long durations. However, activated carbon electrode corrosion also occurs. Experiments on capacitors with stainless steel and gold current collectors indicate that the lifespan of the latter is much longer than that of the former. Therefore, current collector corrosion has a distinct and detrimental impact on electrochemical capacitor operation. Moreover, the research results indicate that carbon corrosion results from current collector corrosive damage.

The Role of Current Collector Corrosion on the Performance of Thermal Batteries

As a bridge connecting external circuits and electrodes, current collectors are critical for battery performance. While numerous studies have investigated lithium-ion battery current collectors at room temperature, fewer address high-temperature batteries (>500 °C). The interfacial properties of thermal battery collector and cathode at high temperatures remain unclear, and collector selection is more empirical. In this paper, the effects of 304 stainless steel on the discharge performance of NiS2 cathode were investigated. At 500 °C, 100 mA cm−2 and 1.5 V cutoff voltage, NiS2 first-voltage plateau specific capacity with 304 stainless steel current collector exhibits a high specific capacity of 320 mAh g−1 and total specific capacity of 700 mAh g−1, 146% and 17% higher than Ni, respectively. The Ni current collector of the thermal battery underwent severe chemical reactions at high operating temperatures, consuming active mass and increasing interfacial impedance. In contrast, stainless steel formed an iron-chromium sulfide passivation layer inhibiting further chemical reactions and accelerating charge transfer rate at the interface, resulting in effective increase in the discharge capacity of the thermal battery. This study provides theoretical guidance for selecting current collectors for thermal batteries based on high-temperature chemical reactions.

Electrochemical sensor based on PVP coated cobalt ferrite/graphite/PANI nanocomposite for the detection of hydrazine

In this study, we developed a multi-layered electrode as an efficient nanocomposite electrochemical sensor for detecting carcinogenic hydrazine in water. Nano-cobalt ferrite (CoFe2O4) was prepared using poly (vinylpyrrolidone) (PVP), mixed with an optimum quantity of graphite and pasted on a stainless-steel current collector. The nanocomposite was further hybridised by electrodepositing with polyaniline (PANI). The obtained composite was characterized using XRD, FTIR, SEM, and electrochemical techniques. XRD analysis shows the successful formation of composite from individual precursors. According to SEM, wrinkled and layered morphology for graphite and aggregate clusters for cobalt with spike or tubular structure for polyaniline were observed. When subjected to amperometry current, the prepared electrode showed different peaks for different concentrations of hydrazine, such as 1 μM to 100 μM. Cyclic voltammetry studies showed an increase in oxidation and reduction peaks. These studies will lead to a new platform for their potential applications in detecting toxic materials in real samples such as water, plastic bottle, water etc.,

Fabrication of Ni-Cr-FeOx ceramic supercapacitor electrodes and devices by one-step electric discharge ablation

This investigation addresses the need in the development of a facile, low-cost and computer-aided design method to fabricate ceramic supercapacitors, based on patterned metal oxide films. It is motivated by the promising advantages of planar electrode arrangement for the fabrication of ceramic supercapacitors operating at extremely high charge-discharge rates. Herein, one-step electric discharge ablation (EDA) technique is developed for fabricating Ni-Cr-FeOx electrodes using commercial 304 stainless steel current collectors for the first time. The binder-free, noble materials-free, toxic chemical-free and conductive additives-free Ni-Cr-FeOx based in-plane microsupercapacitors (IMSC) are fabricated by the EDA technique. The obtained IMSC delivers a high areal capacitance of 38.3 mF cm−2 at 1 mV s−1 and shows superior capacitive behavior at an ultrahigh scan rate of 152,000 mV s−1, which is >760 times higher than the reported values for ceramic metal oxide based electrodes in the literature. This one-step, low-cost, environmental friendly, and automatic fabrication method is promising for the scale-up synthesis of various ceramic metal oxides and fabrication of supercapacitor devices.

Comparison of Different Current Collector Materials for In Situ Lithium Deposition with Slurry-Based Solid Electrolyte Layers

In this paper, we investigate different current collector materials for in situ deposition of lithium using a slurry-based β-Li3PS4 electrolyte layer with a focus on transferability to industrial production. Therefore, half-cells with different current collector materials (carbon-coated aluminum, stainless steel, aluminum, nickel) are prepared and plating/stripping tests are performed. The results are compared in terms of Coulombic efficiency (CE) and overvoltages. The stainless steel current collector shows the best performance, with a mean efficiency of ηmean,SST=98%; the carbon-coated aluminum reaches ηmean,Al+C=97%. The results for pure aluminum and nickel indicate strong side reactions. In addition, an approach is tested in which a solvate ionic liquid (SIL) is added to the solid electrolyte layer. Compared to the cell setup without SIL, this cannot further increase the CE; however, a significant reduction in overvoltages is achieved.

Enabling metal substrates for garnet-based composite cathodes by laser sintering

In this study, a laser irradiation method developed by Fraunhofer ILT was used to sinter screen-printed cathode layers of LiCoO2 (LCO) and Li7La3Zr2O12 (LLZO) directly on a stainless steel current collector. The laser sintering method was proved to be a promising method to sinter the composite cathode onto steel with greatly reduced side reactions and material degradation. In comparison, conventional sintering and another light-absorption-based sintering method, namely rapid thermal processing (RTP) in a lamp furnace, led to almost complete decomposition of the LLZO phase accompanying with the detrimental formation of LaCoO3 and CoO. Phase and morphology analysis of the laser-sintered cathodes using Raman spectroscopy, X-ray diffraction, and scanning electron microscopy confirmed sintering of LCO and LLZO through the layer with small amounts of secondary phases (LaCoO3, Li0.5La2Co0.5O4 and CoO). The resulting porous matrix of the laser-sintered cathode was infiltrated with a polyethylene oxide (PEO) electrolyte to connect the cathode to an LLZO separator and a Li metal anode without an additional sintering step. This model cell was used to evaluate the electrochemical activity of the laser-sintered composite cathodes, which exhibited a specific discharge capacity of 102 mAh g−1 at 4.0 V in the first electrochemical cycle.

Continuous caustic aqueous phase electrochemical reforming (CAPER) of ethanol for producing compressed hydrogen

Caustic Aqueous Phase Electrochemical Reforming (CAPER) of ethanol produces pure compressed H2 at lower voltages, temperatures, and energy requirements than conventional electrolysis, while capturing carbonaceous products. The CAPER flow reactor consists of stainless steel endplates, stainless steel current collectors, and a Teflon flow field. The electrodes are prepared using commercial palladium nanoparticles on carbon support for the anode and platinum nanoparticles on carbon support for the cathode. The catalyst metal loading was 1 mg cm–2 on a 10 cm2 carbon cloth for both electrodes. Our CAPER reactor produces pure H2 at 80 bar and 80 °C applying voltages at ≤0.5 V. The only gas-phase product detected was H2 and any carbonaceous products were contained in the liquid phase. The H2 was produced with 97 ± 4% faradaic efficiency. Operating at smaller electrode separation distances (4 mm) and 80 °C increased the current density. The highest lower heating value efficiency achieved was 28% at a flow rate of 0.05 mL min–1 and an applied voltage of 0.5 V. The compressed H2 was produced at ≤20 kWh kg–1, which is much lower than electrolysis systems that require upwards of 50 kWh kg–1.

Low-Cost and Scalable Ni-Prussian Blue Analogue//Functionalized Carbon Based Na-Ion Systems for all Climate Operations.

Herein, we have developed a sodium ion based aqueous energy storage device with nickel prussian-blue-analogue (Ni-PBA) positive and functionalized carbon-black negative electrodes in 1 M Na2 SO4 electrolyte solution. The components required to develop the device, i. e., stainless steel (SS) current-collectors, absorbent-glass-mat separator, electrolyte, carbon-black, and precursors of Ni-PBA, are all environmentally benign and inexpensive. To minimize the corrosion of pristine-SS, polyaniline coating on the SS surface is applied by in situ electrodeposition method. The full cell exhibits a specific capacity of 28 mAh g-1 with 90 % Coulomb efficiency (@0.2C), an energy density of 34 Wh kg-1 (@20 W kg-1 ), a power density of 100 W kg-1 (@18 Wh kg-1 ) and a good life cycle (70 % capacity-retention over 500 cycles @1.0C rate) within the 0-1.2 V window. The cell performance is further tested under variable temperatures, and 0-50 °C range is reported to be the working window for this cell.

Stainless steel foil: A more appropriate current collector than titanium foil for the cathodes of aqueous zinc ion batteries

Benefiting from the advantages in safety, reliability, affordability, and energy/power densities, aqueous zinc-ion batteries (AZIBs) with mildly acidic electrolytes have triggered tremendous research interest. However, Ti foil, as the most widely used current collector for cathodes of AZIBs, is rather expensive. In this work, stainless steel (SS) foil, with a much lower price, is proposed to be a more appropriate current collector than Ti, Ni, Al, and Cu foils. Among them, Ti and SS foils are found to own superior wettability with related solvents, excellent anti-corrosion ability, and strong binding with cathode material. In contrast, Al and Cu foils suffer from severe corrosion in aqueous electrolytes even without external potential, and Ni foil is electrochemically unstable in aqueous electrolytes. Further studies show that only Ti and SS current collectors can enable Zn//MnO2 battery to work normally. And SS foil behaves slightly better than Ti foil in both Zn//MnO2 battery and hybrid supercapacitor in terms of specific capacity, rate capability, and cyclability. This work provides guidance for the selection of current collectors for AZIBs and related energy storage devices.

Monolithic All-Solid-State High-Voltage Li-Metal Thin-Film Rechargeable Battery.

The substitution of an organic liquid electrolyte with lithium-conducting solid materials is a promising approach to overcome the limitations associated with conventional lithium-ion batteries. These constraints include a reduced electrochemical stability window, high toxicity, flammability, and the formation of lithium dendrites. In this way, all-solid-state batteries present themselves as ideal candidates for improving energy density, environmental friendliness, and safety. In particular, all-solid-state configurations allow the introduction of compact, lightweight, high-energy-density batteries, suitable for low-power applications, known as thin-film batteries. Moreover, solid electrolytes typically offer wide electrochemical stability windows, enabling the integration of high-voltage cathodes and permitting the fabrication of higher-energy-density batteries. A high-voltage, all-solid-state lithium-ion thin-film battery composed of LiNi0.5Mn1.5O4 cathode, a LiPON solid electrolyte, and a lithium metal anode has been deposited layer by layer on low-cost stainless-steel current collector substrates. The structural and electrochemical properties of each electroactive component of the battery had been analyzed separately prior to the full cell implementation. In addition to a study of the internal solid–solid interface, comparing them was done with two similar cells assembled using conventional lithium foil, one with thin-film solid electrolyte and another one with thin-film solid electrolyte plus a droplet of LP30 liquid electrolyte. The thin-film all-solid state cell developed in this work delivered 80.5 mAh g–1 in the first cycle at C/20 and after a C-rate test of 25 cycles at C/10, C/5, C/2, and 1C and stabilized its capacity at around 70 mAh g–1 for another 12 cycles prior to the start of its degradation. This cell reached gravimetric and volumetric energy densities of 333 Wh kg–1 and 1,212 Wh l–1, respectively. Overall, this cell showed a better performance than its counterparts assembled with Li foil, highlighting the importance of the battery interface control.

Vapor-solid-solid growth of silicon nanowires using magnesium seeds and their electrochemical performance in Li-ion battery anodes

The energy density of next-generation lithium-ion batteries (LIBs) can be considerably improved by replacing traditional graphite anodes with silicon nanowires (Si NWs). However, the synthesis of Si NWs is restricted due to the requirement for expensive and heavy metal catalysts for growth. Herein, for the first time, we successfully demonstrate the growth of Si NWs using magnesium (Mg) as a catalyst material, within a wet-chemical glassware-based setup. Analysis of the Si NWs revealed the presence of Mg2Si at the tips of the Si NWs, indicating that growth proceeds via a vapor–solid-solid (VSS) mechanism. Si NWs were also grown from Mg foil, Mg powder, and from thermally evaporated layers on stainless steel substrates, demonstrating the versatility of Mg as a catalyst material. Mg as a catalyst facilitated high NW mass loadings (up to 0.8 mg/cm2) on planar stainless steel current collectors, coupled with tight diameter control (average diameter of ∼20 nm). Within LIB half-cell testing, they demonstrated high initial coulombic efficiencies (up to ∼81 %) and high gravimetric (up to 2792 mAh/g) and areal capacities (up to 1.58 mAh/cm2). The approach highlights Mg as a catalyst for the development of higher mass loading and binder-free Si NWs anodes for LIBs.

Capacitor lifetime prolonged by addition of organic ammonium salt with cyclohexyl substituent and 2,5-dihydroxybenzenesulfonic anion

It is well known that the electrochemical corrosion negatively affects the functional properties of metal and steel materials that constitute a part of systems conducting electric charge. On the other hand, the phenomenon of corrosion is rarely associated with the degradation of chemical power sources and energy storage devices. This article is aimed to fill this gap by describing the effect demonstrated by a substituted ammonium salt with cyclohexyl substituent and 2,5-dihydroxybenzenesulfonate anion used as a corrosion inhibitor in symmetrical electrochemical capacitor system. The accelerated ageing test of capacitor systems has shown that the addition of substituted ammonium salt to capacitor electrolyte allows to extend the service lifetime of the entire system by inhibiting the corrosion of 316L stainless steel current collectors. The inhibitory effect of substituted ammonium salt additives on the electrochemical corrosion of 316L stainless steel surface has been also confirmed by cyclic potentiodynamic polarization (CPP) tests and X-ray photoelectron spectroscopy (XPS) measurements.

Self-healing action of Bi in high-performance Sb–Bi–Sn positive electrodes for liquid metal batteries

Li||Sb–Bi–Sn liquid metal batteries (LMBs) have comprehensive advantages of a high energy density, excellent rate capability, low material costs, and high cycle performance. However, the corrosion of the positive electrode to the current collector at high temperatures cannot be neglected over the long term. Here, we investigate the corrosion behavior of SS304 in two types of Sb–Bi–Sn alloys under static and cell cycling conditions. Interestingly, we find that the cell performance of Li||Sb–Bi–Sn LMBs are not affected by corrosion between the positive electrode and stainless-steel current collector. The corrosion products and their participation in the cell reaction process are determined using ex situ analyses and electrochemical measurements. Bi not only inhibits the dissolution of SS304 in Sb–Bi–Sn alloy but also spontaneously promotes the decomposition of Fe–Sb and Fe–Cr–Sb corrosion products during lithiation, releasing the active component Sb, and Sb–Bi–Sn alloy is recovered. Encouragingly, even in the event of corrosion, the cell capacity, efficiency, and cycle stability remain almost unaffected due to this self-healing action of Bi. This study represents a new direction toward inhibiting the corrosion of positive electrode and stabilizing cell performance for practical application and commercialization by alloying.

Anticorrosive performance of green deep eutectic solvent for electrochemical capacitor

Reline Deep Eutectic Solvent (DES) is widely recognized as a novel and green electrolyte for industrial applications due to its low cost and tolerance to moisture. It has received significant attention, however, its application in the energy storage system is still in infancy. Generally, aqueous-based electrochemical capacitors (ECs) present an ideal energy storage technology because of several advantages. Yet, high corrosion of the current collector limits their cyclability. Novel Reline DES electrolyte is studied and its anticorrosive electrochemical performance is evaluated in carbon-based ECs using stainless steel current collector (316L). Our findings show that Reline electrolyte and its water mixture display a strong inhibiting corrosion effect for 316L. Furthermore, a few aqueous electrolytes are studied to confirm the effectiveness of Reline DES as a green and anti-corrosive electrolyte for EC. Floating protocol is applied to monitor the stability of the EC performance in Reline and aqueous electrolytes. The devices using pure Reline and its water mixture exhibit higher electrochemical stability with good capacitive performance compared to 1 M Li2SO4 and 1 M KOH based ECs. The study may pave the way to practical Reline DES-based ECs for sustainable, highly stable, environmentally friendly and cost-effective energy storage systems in the future.

Pt nanoflower-poly(aniline) electrode material with the synchronized concept of energy storage in supercapacitor

Electrochemically deposited porous film of poly(aniline) (PANI) on stainless steel (SS) current collector is employed as the support for electrodeposition of platinum (Pt). PANI facilitates the formation of Pt nanoflowers with an enhanced electrochemically active surface area compared with sub-micron size Pt particles deposited on the bare SS electrode. Hence, anew conceptPt nanoflower-PANI electrode materials withsynchronization between redox mode in PANI and double-layer mode of charge storage in Pt nanofloweris discussed. Remarkably, Pt is distributed like a nano-flower on the surface of PANI and prevents PANI from stripping during the charge-discharge process, thereby minimizing the issue of stripping in conducting polymer-based electrodes. Owing to the highly porous surface morphology of Pt nanoflowers as observed in SEM, the Pt-PANI/SS electrode shows excellent electrochemical performance than PANI/SS electrode towards supercapacitor application. The electrode materials are characterized using X-ray and X-ray photon spectroscopy (XPS), which shows dual amorphous and crystalline properties. Dielectric studies of Pt-PANI/SS electrodes were carried out to understand electrode/electrolyte interface behavior. In the fabricated supercapacitor, the cyclic voltammetry studies showed quasi-rectangular shape characteristics at slower scan rates with a specific capacitance of 926 Fg−1. Charge-discharge studies showed good cyclic stability and coulombic efficiency.

Growth Parameters and Diffusion Barriers for Functional High-Voltage Thin-Film Batteries Based on Spinel LiNi0.5Mn1.5O4 Cathodes.

Cobalt-free spinel LiNi0.5Mn1.5O4 is one of the most promising and environmentally friendly cathodes, based on its high specific theoretical capacity (147 mAh·g-1) and high electrochemical potential (4.7 V vs Li+/Li), as well as good electronic and Li-ion conductivities. In this work, we present the fabrication of LiNi0.5Mn1.5O4 thin-film cathodes deposited by the industrially scalable AC magnetron sputtering technique on functional and cost-effective stainless steel current collectors. This is the first step toward battery downscaling, envisioning the fabrication of compact microbatteries for low-power energy supply. The thin-film strategy is crucial also for solid electrolyte fabrication that will allow the integration of high-energy-density batteries while overcoming most of the current battery challenges. In this work, the effect of film thickness on the material's electrochemical performance is discussed, correlating the observed structural and morphological evolution with the final electrochemical response. Moreover, the effect of iron diffusion from the current collector substrate into the cathode film is analyzed. The addition of a stable CrN barrier layer in between the substrate and the film is proposed to prevent Fe diffusion, with a direct positive influence on the electrochemical behavior. All in all, the obtained results will facilitate the practical implementation of LiNi0.5Mn1.5O4 thin films as high-voltage cathodes in functional cost-effective microbatteries.

Effect of baking, humidity and UV radiation on hexagonal boron nitride modified c-MWCNT nanohybrid electrodes

Electrically conducting nanohybrids (NHs) of hexagonal boron nitride (h-BN) with carboxylic functional multiwalled carbon nanotubes (c-MWCNT) have shown growing interest as electrode materials in microelectronics. This has been due to their ability to serve as potential electrically conducting materialsunder harsh environmental conditions of temperature, humidity and radiations. Present investigation demonstrates the development and characterisation of working electrodes (WEs) derived by coating of NHs and polyvinyl butyryl suspension in N-methyl-2-pyrrolidone (NMP) over stainless steel current collector. Field emission scanning electron microscopy (FESEM) and thermogravimetric analysis in air were used to examine the surface morphology and thermal stability of NHs. Effect of baking time (BT), humidity exposure (HE) and photo aging (PA) on functionality and performance of WEs has been investigated. The DC conductivity (σDC) of WEs increased somewhat with BT, reaching 0.97 upto 3 hr. Increasing BT to 6.0 hr resulted in a slight fall in the σDC of WEs to 0.94, which thereafter remained static at 0.92 at 9.0 hr. Under UV exposure for 3 hr, the σDC of WEs reached to 1.12. The σDC of WEs has been reduced to 0.99 after further 6 hr of irradiation and later it has reached to 0.98 after 9 hr of irradiation of WEs. The σDC of NHs under HE conditions was found in increasing order ranging from 0.96 to 1.14 for 0 to 3 hr and further marginal reduction from 1.11 to 1.10 for 6 to 9 hr.

Processing of manganite-based contact layers for stacking of planar solid oxide fuel cells

Quality of the solid oxide fuel cell (SOFC) stack assembly affects power density and lifetime of the power plants. In the case of planar SOFCs, assembling quality depends on electrical contact between the stainless steel current collectors and ceramic electrodes of the membrane-electrode assemblies (MEAs). Whilst Ni meshes and paste are commonly used to provide this contact at the anode side, the cathode contact materials should be stable in oxidizing atmosphere. In this work, mechanical pre-treatment conditions of submicron La0.8Sr0.2MnO3±δ (LSM) cathode powders were optimized in order to sinter mechanically stable contacts in the course of SOFC sealing procedure without use of inorganic sintering aids. Excessive ball-milling time and/or rotating speed was shown to result in partial decomposition of the perovskite phase, which increases electrical resistivity of the porous layers. Testing of the LSM contact layers in model SOFC stack with Crofer 22H current collectors under standard operating conditions demonstrated sufficient adhesion and performance.