Ni Current Collector Research Articles

Highly Nanoporous Nickel Foam as Current Collectors in 3D All-Solid-State Microsupercapacitors.

This study reports a streamlined method for producing a highly nanoporous current collector with a substantial specific surface area, serving as an electrode for microsupercapacitors (MSCs). Initially, commercial Ni foams are patterned into an interdigitated structure by laser cutting. Subsequently, the Ni foams are infused with NiO nanopowders through dip coating, sintering, and reduction in an H2 atmosphere, followed by the growth of MnO2 through a redox reaction. The incorporation of NiO within this three-dimensional Ni current collector results in notable porosity within the range of approximately 200-600 nm. Such a 3D, highly nanoporous electrode dramatically increases the specific surface area by 30 times and substantially boosts the amount of active material deposition, surpassing those of commercially available Ni foams. Performance evaluations of this highly nanoporous electrode in a 1 M KOH solution demonstrate an areal capacity of 19.3 F/cm2, retaining more than 95% capacitance at 5 mA/cm2, and exhibiting an energy density of 671 μW h/cm2, 25 times greater than commercial Ni foams. Moreover, in the realm of solid-state applications for MSCs, the remarkably high porous electrode achieves a commendable areal capacity of 7.22 F/cm2 and an energy density of 263.9 μW h/cm2, rendering it exceptionally suitable for use in MSC applications.

Characterization of direct-ammonia solid oxide fuel cells (DA-SOFCs) at 650–750 °C in a single-repeating unit stack: Effects of metallic components and residual ammonia

Ammonia can be directly utilized in solid oxide fuel cells, known as direct-ammonia solid oxide fuel cells (DA-SOFCs), which are among the most efficient technologies for ammonia utilization. Current research efforts are directed towards lowering the operating temperatures of DA-SOFCs by incorporating additional catalysts. However, critical analyses regarding the extent of ammonia decomposition on metallic interconnects and Ni current collectors, as well as the negative effect of residual ammonia on performance, are lacking. In this study, we examine DA-SOFCs with a single-repeating unit stack on a small scale, addressing the effects of metallic interconnects and the Ni-current collector on DA-SOFC operation within the temperature range of 650 °C–750 °C. The anode components, including the metallic interconnect, Ni-current collector, and the SOFC cell, are investigated in powder form and in DA-SOFC operation to determine each component's influence under actual DA-SOFC operating conditions. Both Fe-rich and Ni-rich high-temperature alloys demonstrate high catalytic activity for the ammonia decomposition reaction, playing a significant role in actual cell operations. Furthermore, extensive impedance analysis of DA-SOFC operation under various fuel conditions reveals that residual ammonia significantly increases polarization resistance at lower temperatures, which is the primary factor contributing to negative effect on performance at these temperatures.

Cathode tailoring of micro-tubular protonic ceramic electrochemical reactors for CO2 hydrogenation

Protonic ceramic electrochemical reactors (PCER), having the advantages of high efficiency, adjustability, and scalability, exhibit great potential in energy storage such as conversion of CO2 into high-value chemicals. Designing critical components like the electrolyte and electrodes of electrochemical reactors is essential to widen commercial applications. The present work constructed a three-layer microtubular PCER (MT-PCER) for CO2 hydrogenation. BaCe0.5Zr0.3Y0.2O3-δ (BCZY) was used as the electrolyte material to prepare BCZY/Ni-BCZY/Ni triple-layer hollow fibers (TLHFs) by a phase-inversion based co-spinning/co-sintering process. Porous Ni-BCZY was the catalytic functional (cathode) layer, and the metallic Ni composed the current collector layer. Results indicated that CO2 conversion and CH4 selectivity were significantly enhanced when the NiO content in the cathode layer increased from 40 % to 60 %, while there was no significant change for the content continuously increasing to 80 %. Compared with the reactor employing dual-layer hollow fibers, the Ni collector layer in TLHFs presented a remarkable intensification of the methanation performance. As a result, the MT-PCER with 60 % NiO content in the cathode layer and utilizing the Ni current collector was the recommended reactor structure, which possessed the CO2 conversion of 29.8 %, CH4 selectivity of 50.9 %, CH4 yield of 15.2 %, and faradaic efficiency of 43.6 % at 700 °C and 2 V applied voltage. The adjusted design of the TLHF facilitated the advancement of the performance and efficacy of the MT-PCER, promoting carbon capture, utilization, and storage processes.

Direct ammonia SOFC – A potential technology for green shipping

International shipping carries about 90% of the global trade, thereby emitting significant amounts of greenhouse gasses by using fossil based fuels. Zero-emission technologies using green fuels are crucial to reduce the environmental impact of this important transport sector. Among the considered concepts is green ammonia in a solid oxide fuel cell (SOFC).The present study investigated SOFCs fueled with ammonia regarding cracking, electrochemical performance and durability. Ammonia cracking was for the first time directly measured over a planar, anode supported SOFC at open circuit voltage and during operation, as well as in presence of several balance of plant components. At temperatures around 700 °C, ammonia is significantly cracked when passing over hot metallic low surface area components (like Ni current collectors) even in the absence of the SOFC. The Ni/YSZ SOFC anode is active for the cracking as well. The area specific resistance of the SOFC is larger when using ammonia as compared to a H2/N2 mixture, due to two origins, (i) a decrease of the cell temperature due to the endothermal cracking, which leads to larger ohmic resistance and (ii) presence of unconverted ammonia, which increases the polarisation resistance in the low frequency region. Durability tests reveal increased cell voltage degradation when using ammonia fuel at 700 °C, mainly due to increase of the ohmic contributions. Micro structural analysis suggests nitridation as cause of this degradation. A stable SOFC operation is possible at 750 °C.

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.

Nanoporous Ni current collectors with cone array supported Sn–Co alloys as anodes for high-performance lithium-ion batteries

Template-free electrodeposition creates nanoporous Sn–Co alloy electrodes, serving as binder-free anodes for lithium-ion batteries with enhanced lithium kinetics and stability.

Sustainable Recycling of Spent Ionic Liquid Dual‐Ion Batteries

Ionic liquid (IL) dual‐ion batteries (DIBs) are widely studied as advanced electrochemical systems because of their potential nonflammability, environmental friendliness, and high working voltage. Recycling and reusing valuable IL electrolytes and metallic Ni current collectors might boost the application of IL DIBs. Herein, the preliminary results of the recycling of a spent DIB with 1,2‐dimethyl‐3‐propylimidazolium chloroaluminate (DMPI+)(AlCl4−) electrolyte are reported. Recovery rates of most components (graphite flakes, Ni current collector, and so on) of the DIB reach a range of 84–98%, whereas the IL electrolyte is only 24%. Optimistically, the cost of an IL DIB using recycled components can be reduced by around 68%. Thus, developing the recycling processes might pave the way to increase the competitiveness of IL DIBs for grid‐scale energy storage.

Improvement of Simple Test Cell Design for Cathode Microstructure Study in Tubular-Type Sodium–Metal Chloride Batteries

Sodium–metal chloride batteries are suitable alternatives in battery energy storage systems (BESSs), since they are widely known as a type of high-safety battery. To accurately analyze the cathode microstructure of sodium–metal chloride batteries, in this study, we demonstrate the improved tubular-type simple test cell. This improved tubular-type simple test cell was supplemented from the setbacks of our previous test cell, such as a leak, Ni current collector wavering, and sodium wicking. Through testing of the improved test cells, we focus on cathode microstructure analysis, owing to the elimination of the external failure factors mentioned above. The group of improved test cells have a lower capacity gap of 9.5% in the 1st cycle than the capacity gap of previous test cells (37.2%). This result indicates the advancement of reproducibility. Moreover, the improved test cell has a long life of approximately 7200 h by changing the previous test cell structure. In particular, it is expected that this improved tubular simple test cell can advance the research of tubular-type sodium–metal chloride batteries in a small and academic laboratory.

Multilayered Graphene-Coated Metal Current Collectors with High Electrical Conductivity and Corrosion Resistivity for Flow-Electrode Capacitive Mixing

Flow-electrode capacitive mixing (F-CapMix) is a novel technology, harvesting electric energy from salinity gradient power. A continuously circulating flow-electrode enables constant electrical power generation without any intermittent step. Graphite is a widely used current collector because of its high electrical conductivity and corrosion resistivity to seawater for F-CapMix. However, insulating polyacrylate-based polymers should be employed for shaping the graphite body, resulting in reduced electrical conductivity, hindering efficient charge percolation in flow-electrodes. Metal current collectors are difficult to use because of their low corrosion resistance to seawater despite their good electrical conductivity. Here, we first report high electrical conductivity and corrosion-resistive multilayered graphene as a protective layer on metal current collectors in F-CapMix. The graphene is synthesized on metal current collectors through the chemical vapor deposition process. We study chemical and electrochemical aspects of protective layer-coated current collectors by controlling parameters for graphene growth on metal substrates. The multilayered graphene protective layer can not only prevent corrosion from seawater but also enable efficient charge percolation with high electrical conductivity. By employing multilayered graphene-coated Ni current collectors in the F-CapMix unit cell, an almost twice higher power density of 0.75 W·m–2 and current density of 22.3 A·m–2 could be achieved compared to those of graphite.

The effect different of hydrochloric acid concentrations on the cleaning of Ni foam substrate: Structural and morphological studies

Recently, much attention has been focused on nickel (Ni) as current collectors for supercapacitor applications. The cleaning of Ni current collector is mandatory before it can be utilized in supercapacitor devices. The cleaning of the Ni foam substrate is essential for removing contaminations and modifying the surface morphology of the foam. In this study, Ni foam substrates were cleaned via sonication in different concentrations of HCl solution and the formation of the oxide layer on the surface of the Ni foam was investigated. The formation of oxide layer on the Ni foams was characterized of its morphology, elemental and structural analyses. The cleaning of the Ni foam with HCl solution leads to the formation of oxide layer on the Ni foam surface. The cleaning of Ni foam substrate with a 2.5 M of HCl solution gave an oxide layer with uniform thickness (0.034 μm) before the layer was detached. Cleaning with 5.0 M HCl concentration produced the thickest oxide layer formation (0.327 μm). However, a cracked line (black line) was also observed for 4.0 and 5.0 M HCl concentrations, indicating that the attachment of these oxide layers on the surface of the Ni foam was poor and susceptible to detachment. From the structural analyses, no impurity peaks were detected in the diffraction pattern and the intensity peaks of Ni were decreased and broaden with the increase in the HCl concentration. It is proven that the Ni foam have uniform surface roughness of the oxide layer when cleaned with HCl solution lower than 2.5 M but the thick oxide layer was detached at concentrations higher than 2.5 M which deteriorates the supercapacitor systems.

Controllable 3D Porous Ni Current Collector Coupled with Surface Phosphorization Enhances Na Storage of Ni3 S2 Nanosheet Arrays.

3D porous Ni is fabricated via an easily scalable electroless plating method using a dynamic template formed through in-situ hydrogen bubbles. The pore size in the range of several micrometers is controllable through adjusting the Ni2+ depositing rate and hydrogen bubbles releasing rate. The Ni3 S2 nanosheet arrays anode is then grown on the unique 3D porous Ni current collector followed by subsequent surface phosphorization. The tremendous interconnected pores and rich voids between the Ni3 S2 nanosheet arrays cannot only provide rapid transferring channels for Na+ , but also accommodate volumetric changes of the Ni3 S2 electrode during cycling, guaranteeing the integrity of the active material. In addition, the surface phosphorized layer enhances the electronic conductivity through providing an electron transport highway along the 3D Ni3 S2 , NiP2 layer, and 3D porous Ni current collector, and simultaneously stabilizes the electrode/electrolyte interphase as a protecting layer. Because of these merits, the phosphorized 3D porous Ni3 S2 (3D P-Ni3 S2 ) electrode is capable of delivering an ultra-stable capacity of 387.5 mAh g-1 at 0.1 A g-1 , and a high capacity retention of 85.3% even at a high current density of 1.6 A g-1 .

Design of open-porous three-dimensional starfish-like Co3O4/Ni forest electrode for efficient energy storage devices

A binder-free positive electrode material of 3D starfish-like Co3O4/Ni forest is fabricated via a novel and facile hydrothermal process followed by thermal treatment. The morphological studies clearly showed the construction of starfish-like micro-flowers of Co3O4 nanostructure forest densely covered on the entire Ni current collector. The 3D-Co3O4/Ni electrode displayed an areal capacity as high as 143.28 mC cm−2 at 0.5 mA cm−2 and higher stability of 88.4% after 5000 cycles. Moreover, the fabricated 3D-Co3O4/Ni||3D-Bi2O3/Ti supercapattery delivered a maximum areal capacitance of 24.73 mF cm−2, the energy density of 6.73 μWh cm−2 and power density of 5250 μW cm−2 with good cycling stability> 71% capacity retention after 5000 cycles. The higher electrochemical performance of the electrode is delivered due to the availability of abundant electrochemically active sites in the 3D starfish-like Co3O4 microflower, which facilitates a higher electrochemical reaction. The starfish-like forest architectures allow rapid ion diffusion, and the binder-free electrode reduces the contact resistance, which fasten the electron transport. These tolerable results prompt the as-prepared electrode with 3D starfish-like Co3O4 microflower morphology as an auspicious positive electrode material for electrochemical energy storage devices.

Fabrication and Characterization of Thin-Film SOFC Supported by Microchannel-Structured Zirconia Substrate for Direct Methane Operation

Ni-cermet anode demonstrates excellent catalytic activity and electrical conductivity but suffers from carbon deposition issue. To utilize Ni-cermet anode while preventing carbon deposition, a synergic strategy is employed to design anode electrode. In particular, Zr is incorporated into Ce0.8Sm0.2O2-δ lattice to tailor oxygen storage and catalytic properties of Ni-Ce0.8-xSm0.2ZrxO2-δ anode for improving electrochemical oxidizations of various fuel species. An inert thick YSZ microtubular substrate with radially well-aligned microchannels open at the inner surface is used to support multi thin functional layers of solid oxide cell, i.e., Ni current collector, Ni-Ce0.8-xSm0.2ZrxO2-δ anode, YSZ/SDC electrolyte, and LSCF cathode. The thick YSZ substrate is able to inhibit the ratio of fuel to product gases in the thin anode functional layer, which favors the prevention of carbon buildup in the thin anode layer when synergistically combined with Ni-Ce0.8-xSm0.2ZrxO2-δ anode material. The microchannels embedded in the YSZ substrate can also avoid too much dilutions of the fuel in the anode functional layer. The cell is fabricated and tested with both hydrogen and methane as the fuel. A short-term test is conducted with methane as fuel and good stability is obtained. The fundamental mechanisms for the prevention of carbon buildup in anode functional layer are also discussed.

Phosphotungstic acid assisted growth of nickel hexacyanoferrate on Ni foam for binder-free supercapacitor electrode

• Ni foam was used as both Ni source and current collector. • Ni was oxidized by PTA to Ni 2+ in the presence of K 3 Fe(CN) 6 . • Synthesized Ni-HCF nanocubes were uniformly distributed on Ni foam. • Ni-HCF/Ni foam demonstrates excellent electrochemical performances. The in-situ growth of nickel hexacyanoferrate nanocubes on Ni foam (Ni-HCF/Ni foam) was achieved with a one-step hydrothermal method with Ni foam as both the current collector and the nickel source. Phosphotungstic acid (PTA) acting as the oxidizing agent, oxidized elemental nickel to Ni 2+ cations, which subsequently reacted with K 3 Fe(CN) 6 to produce Ni 3 [ Fe ( CN ) 6 ] 2 nanocubes. The prepared binder-free Ni-HCF/Ni foam was characterized with X-ray diffraction (XRD), X-ray photoelectronic spectroscopy (XPS) and field emission scanning electron microscopy (FE-SEM). The electrochemical performances of Ni-HCF/Ni foam were further investigated with cyclic voltammetry (CV) and galvanostastic charge/discharge technique (GCD). Ni-HCF/Ni foam exhibits areal capacitance of 7200 mF cm −2 (specific capacitance of 535.3F g −1 ) at 10 mA cm −2 , high energy density and long cycling life. An asymmetrical supercapacitor (ASC) was assembled with Ni-HCF/Ni foam and activated carbon (AC) as the positive electrode and negative electrode, respectively. The ASC exhibits remarkable energy density of 5.89 W h m −2 at a high power density of 75 W m −2 .

Converting Fabric to Textile Nickel Current Collector with Ag2s Decoration for Producing Dendrite-Free Lithium Metal Anode

1. Introduction Lithium (Li) metal is regarded as the ideal anode for lithium batteries due to its ultra-high theoretical specific capacity (3860 mAh g-1), low density (0.59 g cm-3) and lowest negative electrochemical potential (-3.04 V vs. Standard Hydrogen Electrode).(1) However, caused by several remaining hurdles, including i) the thermodynamic instability of Li metal and ii) the growth of Li dendrites, the practical application of Li metal anode is still facing challenges from low Coulombic efficiency (CE), insufficient safety performance and poor cyclic stability. To overcome these problems, several strategies have been employed, including the optimization of electrolyte, utilization of solid-state electrolyte and the anode host structure design.(2) The use of hierarchically porous 3D current collector as Li metal host is an effective way to enhance the performance of Li metal anode. In this study, through a simple bio-template method, a textile-structured nickel (Ni) framework is fabricated as current collector for Li metal anode, whose unique micro-nano hierarchical structure is adequate for accommodating Li. With further decoration of uniform silver sulfide nanoparticles (Ag2S NPs), which endows lithiophilicity to the textile-structured Ni framework, a dendrite-free and highly reversible Li metal anode can be achieved after plating Li metal onto the obtained Ni current collector. 2 Experimental Textile-structured Ni current collectors were prepared as follows. Cotton fabric was firstly soaked in aqueous ammonia solution of nickel acetate ((CH3COO)2Ni in NH3·H2O) to form the Ni source coated textile precursor. The precursor was then calcined in air to remove the cotton template and obtain the textile-structured nickel oxide (NiO). Finally, the oxide textile was reduced under hydrogen flow at elevated temperatures to prepare the textile-structured Ni current collector (Textile-Ni). Then, the Textile-Ni was soaked into a prepared silver ammonia solution to form uniformly distributed silver nanoparticles (Ag NPs). After performing a mild sulfidation reaction in a sulfur-dimethyl sulfoxide (S in DMSO) solution, the Ag NPs can be converted to Ag2S NPs without any damage of the Textile-Ni framework.The Li plating/stripping behavior on different current collectors (including planar Cu foil, Textile-Ni, Ag2S decorated Textile-Ni) was firstly examined in a half cell configuration, in which a Li foil was used as the reference and counter electrode and a current collector was used as the working electrode. Li was repeatedly plated/striped to/from the current collectors with controlled capacity and current density. The plating/stripping voltage was monitored and the Coulombic Efficiency (CE) was calculated. Symmetric cells with two identical pre-plated Li@current collector electrodes were also assembled to observe the cycling stability. Finally, full cells consisting of Li@current collector anode and LiCoO2 cathode was also assembled and cycled at specific current densities.The structure and morphology of the current collectors were observed by XRD, SEM and EDS.The morphology and composition of Li plated/stripped current collectors were observed by SEM and XPS. 3. Results and discussion As shown in Fig. 1a, the Textile-Ni was successfully prepared, with the textile structure being similar to the cotton template. Moreover, after the decoration of uniformly distributed Ag2S NPs, the Ag2S decorated Textile-Ni can still maintain the textile structure (Fig. 1b).Fig. 2 shows the dendrites-free morphology of Ag2S decorated Textile-Ni after Li plating. Benefiting from the dendrites-free nature, the Li@Textile-Ni (with Ag2S) supported a Li | LiCoO2 battery to stably cycle for 300 cycles with a high CE (>99%) and a high capacity retention (>140 mAh g-1 for the 1st cycle and maintained 90% capacity after 300 cycles, Fig. 3). As a comparison, the cell using Li foil only maintained a capacity retention of ~30% due to the severe formation of Li dendrites. The electrochemical measurements in symmetric cell and full cell also show that Textile-Ni (with Ag2S) presents superior performance of higher stability and rate capability. The large surface area of Textile-Ni network decreases the local current density and the presence of Ag2S enhance the lithophilicity of the scaffold, which results in uniform deposition of Li.(1) W. Xu, J. Wang, F. Ding, X. Chen, E. Nasybulin, Y. Zhang, J-G. Zhang, Energy Environ. Sci. 2014, 7, 513–537.(2) X. Cheng, R. Zhang, C. Zhao, F. Wei, J. Zhang, Q. Zhang, Adv. Sci. 2016, 3, 1500213. Figure 1

Template-Free Electrochemical Formation of Silicon Nanotubes from Silica.

Silicon, with its elaborate microstructure, plays important roles in energy materials. In operando engineering of microstructure during extraction is an ideal protocol to develop advanced Si‐based materials. A template‐free electrochemical preparation of silicon nanotubes (Si‐NT) is herein achieved by co‐electrolysis of SiO2 and AgCl in molten NaCl–CaCl2 at 850 °C. The in situ electrodeposited Ag facilitates the generation of a liquid Ag–Si intermediate, triggering a liquid–solid mechanism to direct the growth of Si‐NT. An automatic separation of Ag from Si then occurs in the following cooling process, resulting in Ag deposits on the Ni current collector and recycling of Ag. Such a facile and smart preparation of Si‐NT from affordable silica guarantees an enhanced current efficiency of 74%, a decreased energy consumption of 12.1 kW h kgSi −1, and enhanced lithium‐storage capability of the electrolytic Si‐NT. An in situ coating of Ag over the Si‐NT can also be fulfilled by simply introducing soluble AgCl in the melts. The present study provides a template‐free preparation and an in situ surface modification of Si‐NT.

Characterizations of nickel mesh and nickel foam current collectors for supercapacitor application

Nickel (Ni) current collectors having a three-dimensional and porous structure are considered attractive contestants for high-efficiency supercapacitors. Therefore, Ni current collectors have a unique architecture and outstanding electrochemical properties. This study reports the effect of electrochemical characterizations on the electrochemical behavior and physical properties of Ni mesh and Ni foam. Cyclic voltammetry (CV) and galvanostatic charge discharge (GCD) are used to examine the electrochemical properties and life span of the Ni mesh and Ni foam as a current collector in a supercapacitor application. Structural and microstructural characterizations are performed to verify the formation of an oxide layer after 1000 cycles of CV analysis. Results show that Ni foam can increase the yield electrochemical performance of the supercapacitor. Ni foam present better efficiency (35 F g−1) compared to the Ni mesh (12 F g−1) at 10 mV s−1 scan rate by using 2 mg imaginary mass of active material. This result shows that Ni foam has good electrochemical performance and reversibility, higher pseudocapacitance, weaker polarization, and enhance rotating performance as to Ni mesh. The porous structure of Ni foam is in control for improving of the electrochemical properties, therefore, the electrochemical region was increased and shortened ion diffusion. Structural analysis shows that Ni mesh and Ni foam are oxidized after the electrochemical analysis and transformed to nickel oxide hydroxide (NiOOH). Higher specific surface area between the electrode and electrolyte leads to excellent electrochemical and pseudocapacitive performance of the Ni foam compared to the Ni mesh, even if the materials of current collectors are the same. Hence, the physical structure of the current collectors have a critical part in improving the energy density of the supercapacitor.

Supercooled liquid sulfur maintained in three-dimensional current collector for high-performance Li-S batteries.

In lithium-sulfur (Li-S) chemistry, the electrically/ionically insulating nature of sulfur and Li2S leads to sluggish electron/ion transfer kinetics for sulfur species conversion. Sulfur and Li2S are recognized as solid at room temperature, and solid-liquid phase transitions are the limiting steps in Li-S batteries. Here, we visualize the distinct sulfur growth behaviors on Al, carbon, Ni current collectors and demonstrate that (i) liquid sulfur generated on Ni provides higher reversible capacity, faster kinetics, and better cycling life compared to solid sulfur; and (ii) Ni facilitates the phase transition (e.g., Li2S decomposition). Accordingly, light-weight, 3D Ni-based current collector is designed to control the deposition and catalytic conversion of sulfur species toward high-performance Li-S batteries. This work provides insights on the critical role of the current collector in determining the physical state of sulfur and elucidates the correlation between sulfur state and battery performance, which will advance electrode designs in high-energy Li-S batteries.

Novel anode current collector for hydrocarbon fuel solid oxide fuel cells

The current collector is one of the essential and critical components for reliable operation of the solid oxide fuel cell (SOFC). Here a novel anode current collector is proposed to enhance the electrochemical performance stability of the anode supported cell operated under hydrocarbon fuel. A scandium modified nickel fiber felt (Sc: Ni-felt), and a pristine nickel felt (Ni-felt) are employed as the anode current collector to evaluate and compare the electrochemical performance and long-term stability under humidified methane. The maximum power densities of the cell measured using the Sc: Ni-felt current collector are 679, 528, and 389 mW cm−2 at 800, 750, and 700 °C, respectively, under humidified CH4. A significant improvement of ca. 19%, 24%, and 28% in the power density is recorded compared to the cell tested with Ni-felt. A load of 625 mA cm−2 is applied to investigate the long-term stability of both cells. The cell with the novel current collector exhibits excellent stability after 50 h, while the cell tested with Ni-felt gets deteriorated with time under the same operating condition. Finally, the electrochemical impedance analysis under a constant load has been carried out to evaluate the effect of the Sc: Ni current collector on the electrochemical performance and stability of the cell.

In Situ Growth of Hierarchical Ni-Mn-O Solid Solution on a Flexible and Porous Ni Electrode for High-Performance All-Solid-State Asymmetric Supercapacitors.

To endow all-solid-state asymmetric supercapacitors with high energy density, cycling stability, and flexibility, we design a binder-free supercapacitor electrode by in situ growth of well-distributed broccoli-like Ni0.75 Mn0.25 O/C solid solution arrays on a flexible and three-dimensional Ni current collector (3D-Ni). The electrode consists of a bottom layer of compressed but still porous Ni foam with excellent flexibility and high electrical conductivity, an intermediate layer of interconnected Ni nanoparticles providing a large specific surface area for loading of active substances, and a top layer of vertically aligned mesoporous nanosheets of a Ni0.75 Mn0.25 O/C solid solution. The resultant 3D-Ni/Ni0.75 Mn0.25 O/C cathode exhibits a specific capacitance of 1657.6 mF cm-2 at 1 mA cm-2 and shows no degradation of the capacitance after 10 000 cycles at 3 mA cm-2 . The assembled 3D-Ni/Ni0.75 Mn0.25 O/C//activated carbon asymmetric supercapacitor has a high specific capacitance of 797.7 mF cm-2 at 2 mA cm-2 and an excellent cycling stability with 85.3 % of capacitance retention after 10 000 cycles at a current density of 3 mA cm-2 . The energy density and power density of the asymmetric supercapacitor are up to 6.6 mW h cm-3 and 40.8 mW cm-3 , respectively, indicating a fairly promising future of the flexible 3D-Ni/Ni0.75 Mn0.25 O/C electrode for efficient energy storage applications.