Areal Resistance Research Articles

Fumed silica additives enables tunable wettability of the resin for improved composite bipolar plate

Composite bipolar plates (CBP) composed of resin and conductive filler are critical components in proton exchange membrane fuel cell (PEMFC) for achieving mechanical strength and electrical conductivity. The conductive filler entirely enveloped by resin is of significance for the flexibility of the CBP; while connected resin blocks the continued conductive channels and thus weakens the electrical properties of CBP. Herein, we propose a trade-off method between flexibility and conductivity of the CBP by wettability regulations of the resin, in which fumed silica additives are introduced into epoxy as composite adhesives. The abundant hydrogen bonds are demonstrated to be well-formed between epoxy and fumed silica for decreasing surface free energy (SFE) between resin and graphite. As a result, the composite adhesive with 2 % fumed silica delivers moderate wettability enabling much improved CBP, which exhibits high electrical conductivity of 233.33 S cm−1 as well as flexural strength of 66.4 MPa. Moreover, the CBP also delivers improved areal specific resistance (5.34 mΩ cm2), thermal conductivity (10.58 W (m K)−1), and corrosion behaviors (0.0701 A cm−2) which guarantee the operation of the PEMFC. This work provides new insight from the wettability regulation of resins for improved CBP, which is an easy-operating method and has great potential for application in practical CBP fabrication.

Highly conductive and stable iodine doped argyrodite electrolyte for all-solid-state lithium batteries

Lithium argyrodites with high ionic conductivity and low cost are considered as one of the most prospective solid electrolytes for all-solid-state lithium batteries. However, the poor chemical stability and compatibility with lithium metal limit their application. Herein, Li5.4PS4.4Cl1.4I0.2 solid electrolyte with high ionic conductivity of 11.49 mS cm−1 and improved chemical stability is synthesized by iodine doping. An ultra-thin Li5.4PS4.4Cl1.4I0.2 membrane with thickness of 10 μm can be obtained by wet coating process, exhibiting a high ionic conductivity of 2.09 mS cm−1 and low areal resistance of 1.17 Ω cm−2. Moreover, iodine doping could in-situ form LiI at the lithium/electrolyte interface and improve the critical current density of Li5.4PS4.4Cl1.6 from 0.8 to 1.35 mA cm−2. The resultant LiCoO2/Li5.4PS4.4Cl1.4I0.2/Li battery shows excellent cycling stability at 1 C, with a reversible specific capacity of 110.1 mA h g−1 and a retention of 80.5% after 1000 cycles. In addition, the assembled LiCoO2/Li5.4PS4.4Cl1.4I0.2 membrane/Li pouch cell delivers an initial discharge capacity of 110.4 mA h g−1 and 80.5% capacity retention after 100 cycles.

Surfactant Effects in Porous Electrodes for Microemulsion Redox Flow Batteries

The effect of surfactant additives on electrochemical behavior in porous electrodes was investigated using vanadium redox flow battery half-cells and the dependence of volumetric kinetics and mass transport on electrolyte, surfactant, and electrode type was explored. Without surfactant added, carbon paper electrodes demonstrated greater kinetics and transport compared to carbon felt, for a given electrolyte. Additionally, posolyte kinetics are greater than negolyte kinetics by one to three orders of magnitude, depending on the electrode type. Addition of surfactant increased electrode wettability and possibly electrochemical surface area. However, this was accompanied by a decrease in volumetric mass transport, due to stronger electrolyte-electrode interactions. The presence of sodium dodecyl sulfate (SDS) influenced posolyte and negolyte kinetics differently. Kinetics showed a dependence on electrode type and surfactant. On carbon felt, volumetric kinetics decreased for both posolyte and negolyte with SDS addition. On carbon paper, SDS decreased volumetric kinetics for the posolyte but increased (>2X) kinetics for the negolyte! This kinetic enhancement depends on surfactant chemistry: cetyltrimethylammonium bromide, a cationic surfactant, failed to increase kinetics. Furthermore, SDS did not increase areal specific resistance. These findings show the superior performance of carbon paper compared to carbon felt and suggest SDS as a possible VRFB negolyte additive.

Design of high-performance electro-driven nanofiltration membrane via facile co-deposition of pyrogallol and polyethyleneimine for sustainable resource recovery from landfill leachate concentrate

Conventional treatment methods of landfill leachate concentrate mainly focus on the degradation or removal of humic substance, which are prone to secondary pollution and fail to meet the requirements of current sustainable development. The key to sustainable management of landfill leachate concentrate is to precisely fractionate the existing humic substance and inorganic salts as individual resources. Here, electro-driven nanofiltration membranes were fabricated by sodium periodate inducing co-deposition of pyrogallol and polyethyleneimine on the loose polyamide-based nanofiltration substrate membranes as high-performance anion conducting membrane. The pyrogallol/polyethyleneimine composite coating layer endowed the electro-driven nanofiltration membranes with reduced surface negative charge and specific areal electric resistance for enhanced anion transfer. During the electro-driven nanofiltration process, the fabricated membrane with a 30-min co-deposition exhibited an extremely fast anion transfer rate and outstanding fractionation performance with 99.08 ​% humic substance recovery of 99.08 ​%. Particularly, the fabricated membrane showed stable separation capacity over an 8-cycle electro-driven nanofiltration operation, demonstrating a low fouling propensity. Our study sheds light on the strategy to fabricate high-performance electro-driven nanofiltration membranes via co-deposition of pyrogallol and polyethyleneimine, paving the way to sustainable treatment of landfill leachate concentrate.

Tailoring flexible-segment-rich resin network structure by multi-step copolymerization for improved composite bipolar plate of proton exchange membrane fuel cell

Composite bipolar plates composed of conductivity fillers and resins are widely employed in stationary proton exchange membrane fuel cell (PEMFC) due to their high corrosion resistance in acidic environments. Phenol-formaldehyde resin is a commonly used adhesive in composite bipolar plates; while numerous benzene rings in phenol-formaldehyde resin result in the poor flexibility of composite bipolar plates. Embedding the flexible segment (–CHOH–CH2-O-) in the resin network structure of phenol-formaldehyde resin by copolymerization with epoxy resin is an effective method for improving the defects of phenol-formaldehyde resin. In this contribution, to tailor flexible-segment-rich (–CHOH–CH2-O-) resin network structure, the co-polymerization mechanism of phenol-formaldehyde resin and epoxy resin is investigated in detailed by in-situ Fourier Transform Infrared (FTIR), based on which an Alter-T strategy is proposed for flexible-segment-rich (–CHOH–CH2-O-) resin network structure during composite bipolar plates fabrication process. The obtained composite bipolar plates consisted of graphite and flexible-segment-rich resin network structure delivers improved flexural strength (86.97 MPa), electrical conductivity (203.22 S cm−1) and areal resistance (3.41 mΩ cm2) in comparison to previously reported composite bipolar plates with same components, which are also over the technical standard of the DOE. It is further demonstrated that enriching the flexible segment for improving the poor flexibility of resin network structure is of great importance to enhance the performance of the composite bipolar plates.

Tuning the performance of composite bipolar plate for proton exchange membrane fuel cell by modulating resin network structure

Composite bipolar plates (CBPs) are promising candidates in proton exchange membrane fuel cell (PEMFC) for achieving mechanical strength and electrical conductivity as well as chemical stability in acidic environments simultaneously. While widely-explored CBPs composed with Phenol-Formaldehyde (PF) resin as adhesive (donated as PF-CBP) deliver poor flexibility due to the numerous hard π-conjugation (benzene ring) in PF network structure, which is becoming the main bottleneck index and largely hindering the practical applications of CBP. Herein, we propose a co-polymerization method by introducing Epoxy (EP) into PF resin as adhesive for CBP (donated as PF-EP-CBP), by which abundant flexible segments (-CHOH-CH2-O-) from EP are demonstrated to be well embedded into the structure of PF resin for enhanced flexibility. The obtained PF-EP-CBP exhibits significantly improved flexural strength of 46.20 MPa, 1.57 times higher than pristine PF-CBP (29.58 MPa), which is also higher than the 2025 DOE targets (40 MPa). Moreover, the detailed areal specific resistance, thermal conductivity, H2 permeability and corrosion behaviors are conducted systematically to support the single cell of PEMFC. The results provide a novel insight and convenient method on the adhesive tailoring by incorporating flexible linkers into resin network structure, which is of significance to drive the practical development of the CBPs in PEMFC fields.

Development of High Durable Pore-Filling Anion Exchange Membranes for Water Electrolysis Application

Water electrolyzer is a device that converts renewable electrical energy into environmentally friendly chemical energy, hydrogen. Water electrolysis is mainly categorized into proton exchange membrane water electrolysis (PEMWE) and anion exchange membrane water electrolysis (AEMWE). Non-precious electrocatalysts and hydrocarbon-based polymeric membranes are used for two different systems. It is advantageous for AEMWE in terms of cost. However, low current density and chemical stability for current anion exchange membrane technology (AEM) restricts early market penetration. Thus, thedevelopment of low resistance and high durable AEMs is of importance. In this study, superior ion conductivity and high durable pore-filling AEMs were developed for AEMWE. Pore-filling AMEs with different contents of crosslinking monomers were prepared by the monomers using chemically stable anion exchangeable functional groups in a porous polyethylene(PE) substrate. Properties of the AEMs were characterized through areal resistance, ionic conductivity, ion exchange capacity, water uptake, swelling ratio, mechanical strength and hydrogen crossover. In addition, AEMWE performance and durability tests were also conducted. Acknowledgments This research was supported in part by Cooperative Research Program for Agriculture Science and Technology Development (Project No. PJ016253), Rural Development Administration, Republic of Korea and by 2021 Green Convergence Professional Manpower Training Program of the Korea Environmental Industry and Technology Institute funded by the Ministry of Environment.

Imidazolium-Based Anion Exchange Membranes for Electrochemically Converted Liquid Organic Hydrogen Carrier

Liquid organic hydrogen carrier (LOHC) is a technology that uses renewable energy for hydrogen transportation, storage and utilization. LOHC have advantages that can store and utilize hydrogen rapidly in the lack of transportation infrastructure. A membrane-based LOHC system is a promising technology due to the dynamic operation using electrochemistry. Anion exchange membranes are widely used as electrolyte for electrochemical devices. The performance of LOHC could be determined by the properties of anion exchange membranes. Thus, high anion conducting ionomers must be developed for the superior conversion rates on the electrochemical reduction of liquid toluene to methylcyclohexane. In this study, anion exchangeable polymers containing imidazolium salt as anion-conducting group were synthesized to achieve good conduction of hydroxide ions and their chemical stability. Anion exchange membranes were prepared by a pore-filling method using porous polyethylene substrate. The pore-filling anion exchange membranes were characterized in terms of ion conductivity, areal resistance, ion exchange capacity, water uptake, swelling ratio and mechanical strength. Acknowledgment This research was supported in part by the Korea Institute of Science and Technology (No. 2E31871) and by 2021 Green Convergence Professional Manpower Training Program of the Korea Environmental Industry and Technology Institute funded by the Ministry of Environment.

Adverse Effects of Trace Non-polar Binder on Ion Transport in Free-standing Sulfide Solid Electrolyte Separators

Sulfide solid-state electrolyte (SE) possesses high room-temperature ionic conductivity. However, fabrication of the free-standing, sheet-type thin sulfide SE film electrolyte to enable all-solid-state batteries to deliver high energy and power density remains challenging. Herein we show that argyrodite sulfide (Li6PS5Cl) SE can be slurry cast to form free-standing films with low (≤5 wt%) loadings of poly(isobutylene) (PIB) binder. Two factors contribute to a lower areal specific resistance (ASR) of the thin film SEs benchmarked to the pristine powder pellet SSE counterparts: i) 1–2 orders reduced thickness and ii) reasonably comparable ionic conductivity at room temperature after the isostatic pressing process. Nevertheless, an increasing polymer binder loading inevitably introduced voids in the thin film SEs, compromising anode/electrolyte interfacial ion transport. Our findings highlight that electrolyte/electrode interfacial stability, as well as the selection of slurry components, including sulfide SE, binder, and solvent, play essential roles in thin film sulfide electrolyte development.

Fabrication and Performance Evaluation of a Cation Exchange Membrane Using Graphene Oxide/Polyethersulfone Composite Nanofibers.

Ion exchange membranes, especially cation exchange membranes (CEMs), are an important component in membrane-based energy generation and storage because of their ability to transport cations via the electrochemical potential gradient while preventing electron transport. However, developing a CEM with low areal resistance, high permselectivity, and stability remains difficult. In this study, electrospun graphene oxide/polyethersulfone (GO/PES) composite nanofibers were prepared with varying concentrations of GO. To fabricate a CEM, the pores of the electrospun GO/PES nanofiber substrates were filled with a Nafion ionomer. The pore-filled PES nanofiber loaded with 1% GO revealed a noticeable improvement in hydrophilicity, structural morphology, and mechanical properties. The 1% GO/PES pore-filled CEM was compared to a Nafion membrane of a varying thickness and without a nanofiber substrate. The CEM with a nanofiber substrate showed permselectivity of 85.75%, toughness of 111 J/m3, and areal resistance of 3.7 Ω cm2, which were 12.8%, 4.3 times, and 4.0 times better, respectively, than those of the Nafion membrane at the same thickness. The development of a reinforced concrete-like GO/PES nanofiber structure containing stretchable ionomer-enhanced membrane surfaces exhibited suitable areal resistance and reduced the thickness of the composite membrane without compromising the mechanical strength, suggesting its potential application as a cation exchange membrane in electrochemical membrane-based systems.

Toluene Tolerated Li9.88GeP1.96Sb0.04S11.88Cl0.12 Solid Electrolyte toward Ultrathin Membranes for All-Solid-State Lithium Batteries

Sulfide solid electrolyte membranes employed in all-solid-state lithium batteries generally show high thickness and poor chemical stability, which limit the cell-level energy density and cycle life. In this work, Li9.88GeP1.96Sb0.04S11.88Cl0.12 solid electrolyte is synthesized with Sb, Cl partial substitution of P, S, possessing excellent toluene tolerance and stability to lithium. The formed SbS43- group in Li9.88GeP1.96Sb0.04S11.88Cl0.12 exhibits low adsorption energy and reactivity for toluene molecules, confirmed by first-principles density functional theory calculation. Using toluene as the solvent, ultrathin Li9.88GeP1.96Sb0.04S11.88Cl0.12 membranes with adjustable thicknesses can be well prepared by the wet coating method, and an 8 μm thick membrane exhibits an ionic conductivity of 1.9 mS cm-1 with ultrahigh ionic conductance of 1860 mS and ultralow areal resistance of 0.68 Ω cm-2 at 25 °C. The obtained LiCoO2|Li9.88GeP1.96Sb0.04S11.88Cl0.12 membrane|Li all-solid-state lithium battery shows an initial reversible capacity of 125.6 mAh g-1 with a capacity retention of 86.3% after 250 cycles at 0.1 C under 60 °C.

Development of Pore-Filling Anion Exchange Membranes for Anion Exchange Membrane Water Electrolysis: Enhancement of Resistance

Water electrolysis is a process that uses electricity to decompose water into oxygen and hydrogen. There are several types of ion exchange membrane can be used, anion exchange membrane, proton exchange membrane and bipolar membrane for water electrolysis. Alkaline based water electrolysis has several advantages to use non-precious electrocatalysts. However, the development of low resistance and durable anion-exchange membranes is of importance. In this study, several anion-exchange membranes were developed to enhance areal resistance, in other words, to minimize areal resistance. Pore-filling anion exchange composite membranes with different contents of cross-linkers were prepared by mixing an electrolyte having good anion conducting ability. The mixture of monomers into a porous polyethylene (PE) substrate were polymerized by UV curing. The pore-filling reinforced composite membranes have been investigated in terms of good electrochemical properties, in particular, areal resistance. The conductivity and areal specific resistance were measured in both in-plane cell and through-plane cell at 80 ℃ and at room temperature, respectively. Characterization in terms of ion exchange capacity, water uptake, swelling ratio, and mechanical strength were also investigated. Acknowledgments This research was supported in part by "Cooperative Research Program for Agriculture Science and Technology Development (Project No. PJ016253)" Rural Development Administration, Republic of Korea, by the New and Renewable Energy of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20213030040520) and by 2022 Green Convergence Professional Manpower Training Program of the Korea Environmental Industry and Technology Institute funded by the Ministry of Environment.

Swelling-induced ethylmorpholinium-functionalized adamantane-containing poly(aryl ether ketone) membranes with high conductivity and selectivity for vanadium redox flow batteries

Novel swelling-induced ethylmorpholinium-functionalized adamantane-containing poly(aryl ether ketone) (EMAPEK) membranes are prepared for vanadium redox flow batteries (VRFBs). Ethylmorpholinium groups are grafted onto the rigid adamantane-containing backbone, and then the membranes are swelling-induced with concentrated H3PO4 to generate microphase separation and enhance membrane conductivity. The EMAPEK membranes exhibit a low swelling ratio (<4.4%, in-plane) and lower areal resistance (e. g., EMAPEK-160, 0.12 Ω cm2) than the Nafion212 membrane (0.14 Ω cm2). EMAPEK membranes exhibit impressive battery performance in VRFB (e.g., EMAPEK-160 membrane, at 80 mAcm−2, coulombic efficiency = 98.3%, energy efficiency = 92.7%; and at 200 mAcm−2, coulombic efficiency = 98.5%, energy efficiency = 85.2%). These energy efficiencies are the highest reported values for dense ion-exchange membranes. Furthermore, the VRFB with EMAPEK membrane exhibits excellent long-term stability at high current density (≥200 mAcm−2) for 3000 cycles. This work provides a facile and practical method for high-performance membrane preparation and available promising membranes for VRFB.

From Powder to Sheets – a Comparative Study for Solution-Cast Solid Electrolyte/Binder-Sheets As Separators in All-Solid-State Batteries

Sulfidic all-solid-state batteries (ASSBs) are considered as one of the next-generation energy storage systems.[1,2] Most of the previous research studies have investigated ASSBs that are based on a pellet-type separators, i.e., a highly compressed solid electrolyte (SE) powder, with thicknesses of several hundreds of microns.[3] However, their applicability is limited to small electrode area single-layer lab-scale cells, as large-format cells would require separator pellets with a large area that are difficult to produce. Furthermore, in order to be competitive or superior to state-of-the-art lithium-ion batteries based on liquid electrolytes, the thickness of the solid electrolyte separator in ASSBs should be less than 100 μm.[4] Consequently, a key for the industrialization of large-format and high energy density ASSBs is the development of sheet-type cell components. Up to date, only a few publications focus on sheet-type SE separators, investigating appropriate solvents and binders for wet-processed SE/binder composites.[4-7] In the present study, we report on the preparation of composite sheet-type separators for ASSBs by a slurry-based process, investigating three different sulfidic solid electrolyte systems (Li6PS5Cl, Li7P3S11 and Li10SnP2S12) in combination with different volume fractions of hydrogenated nitrile butadiene rubber (HNBR, φHNBR = 1.7 – 16.0 vol.-%) binder.By means of the analysis of top-view and cross-sectional scanning electron microscopy (SEM) images of the prepared sheet-type separators, combined with energy dispersive X-ray spectroscopy (EDX), we characterize the influence of the slurry-coating process conditions as well as of the binder volume fraction on their morphology. Densification of the obtained separator sheets is easily possible by uniaxial compression at room temperature, resulting in residual pore volume fractions of ≈ 3 – 12 %, depending on the respective solid electrolyte. While increasing fabrication pressures lead to a reduction of void volume and an increasing contacting between the solid electrolyte particles, very high fabrication pressures (> 200 MPa) lead to a fusing of the SE particles and to nearly pore-free separator sheets.Besides the micromorphology and porosity of the SE/HNBR separator sheets, we investigate the dependence of binder content and processing conditions on their ionic conductivity by means of potentiostatic electrochemical impedance spectroscopy (PEIS) measurements that are performed using a novel, in-house designed cell setup. As one would expect, the Li+-ion conductivity of the SE/HNBR separator sheets decreases with increasing binder volume fraction (see Figure 1a). Interestingly, however, the relationship between Li+-ion conductivity and binder volume fraction (φ HNBR) is essentially identical for the three different sulfidic electrolytes that are examined in our study (see Figure 1b). To obtain mechanically stable and free-standing SE/HNBR separator sheets, an HNBR volume fraction of approximately 8 vol.-% is required for all three SEs, yielding in a separator sheet conductivity of ≈ 0.5 mS/cm at 70 MPa, which is ≈ 3-fold lower than that of the pure, binder-free SE powder conductivity measured at the same conditions. Nevertheless, by considering the currently achievable thicknesses of these solution-cast separator sheets of ≈ 50 µm, their overall areal resistance (in unit of Ω·cm2) is equal or even lower than that of the typically substantially thicker pellet-type separators, so that these separator-sheets can be used for the assembly of large-format cells with competitive separator resistances.[1] J. Janek and W. G. Zeier, Nature Energy, 1, 16141 (2016).[2] W. Zhang, D. A. Weber, H. Weigand, T. Arlt, I. Manke, D. Schroder, R. Koerver, T. Leichtweiss, P. Hartmann, W. G. Zeier and J. Janek, ACS Appl Mater Interfaces, 9, 17835 (2017).[3] M. R. Busche, D. A. Weber, Y. Schneider, C. Dietrich, S. Wenzel, T. Leichtweiss, D. Schröder, W. Zhang, H. Weigand, D. Walter, S. J. Sedlmaier, D. Houtarde, L. F. Nazar and J. Janek, Chemistry of Materials, 28, 6152 (2016).[4] N. Riphaus, P. Strobl, B. Stiaszny, T. Zinkevich, M. Yavuz, J. Schnell, S. Indris, H. A. Gasteiger and S. J. Sedlmaier, Journal of the Electrochemical Society, 165, A3993 (2018).[5] K. Lee, S. Kim, J. Park, S. H. Park, A. Coskun, D. S. Jung, W. Cho and J. W. Choi, Journal of the Electrochemical Society, 164, A2075 (2017).[6] A. Sakuda, K. Kuratani, M. Yamamoto, M. Takahashi, T. Takeuchi and H. Kobayashi, Journal of the Electrochemical Society, 164, A2474 (2017).[7] F. Shen, M. B. Dixit, W. Zaman, N. Hortance, B. Rogers and K. B. Hatzell, Journal of the Electrochemical Society, 166, A3182 (2019). Acknowledgements: This work was carried out as part of the research project “Industrialisierbarkeit Festkörperelektrolyte”, funded by the Bavarian Ministry of Economic Affairs, Regional Development and Energy. This work was also supported by the BMW Group. Figure 1

Galvanically Displaced Noble Metal Nanoparticles Onto Electrosprayed Graphene-CNT Electrodes for Lithium-Ion and Fuel Cell Applications

Advanced lithium-ion batteries (LIB) and Fuel Cells demonstrate promise as the next generation energy storage and conversion (ESC) technology especially as it pertains to wearable technology and electric vehicles. Although LIB dominate the battery market (>90%) due its reliability, long cycle life, and market maturity, different and more innovative ways to improve the chemistry of the electrode structure must be discovered in order to reduce the cost of materials, dendritic issues at the solid-electrolyte interphase (SEI) layer, and improve upon the limited anode capacity (graphite theoretical capacity 372 mAh g-1). Fuel cells are also promising renewable energy sources due to their high energy densities and scalability. However, both LIB and Fuel Cells are limited by the 3D materials that enable their enhanced electrochemical and catalytic performance. We propose a platform methodology for the synthesis of 3D electrodes with carbon nanomaterials and noble metals. The enhanced electrical, thermal, chemical, and mechanical stability of graphene and carbon nanotubes (CNTs) offer an ideal platform for electrode design for energy storage applications. Here we utilize spontaneous galvanic displacement driven by reduction potential difference to produce three-dimensional (3D) graphene-CNT-noble metal nanoparticle 3D electrode without the use of any harsh chemical reducing agents. A graphene-CNT slurry with a poly(acrylic acid) (PAA) binder is air-controlled electrosprayed onto copper foil to create 3D composite thin film electrodes. Although noble metals are expensive materials to be used in LIB, we propose a new approach for synthesizing conductive electrochemically stable electrodes. We demonstrate a spontaneous technique to reduce the noble metal salts by galvanically displacement with the copper substrate to deposit noble metal nanoparticles onto the graphene-CNT electrode. The noble metal salt solutions (HAuCl4, K2PtCl4, and Na2PdCl4) are drop casted onto the resulting copper supported graphene-CNT electrodes to enable electroless noble metal nanoparticle deposition. Scanning electron microscopy (SEM) imaging confirms that the carbon nanomaterials are integrated with noble metal nanoparticles forming an overall 3D electrode structure. Raman spectroscopy verifies the characteristic D-band, G-band, and 2D-band peaks from the graphitic structure within the 3D carbon and noble metal nanostructure. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) are used to characterize the electrochemical properties of the electrodes. We demonstrate that the use of an energy-free and spontaneous process based on the difference in thermodynamic reduction potentials as the driving force for producing carbon nanomaterial/noble metal nanostructured electrodes for batteries and fuel cells. This process is a more simple, scalable, and cost-efficient alternative to current methods for developing lightweight and catalytic electrodes for energy storage applications, such as lithium-ion batteries, lithium-air batteries, and fuel cells. Raman Spectroscopy is used to confirm the presence defects on the oxidized carbon nanotube and graphene oxide surface. Scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), and x-ray diffraction (XRD) were used to characterize the morphology of the 3D carbon-noble metal structure and the surface elemental composition. Electrochemical characterization techniques such as electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), performance testing for oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and potentiostatic measurements are used to characterize the areal specific resistance (ASR), areal capacitance, electrochemical surface area, initial Coulombic efficiency (ICE), rate capability and cycling performance, and electrochemical stability, respectively.

Thin Nasicon Sodium-Ions Solid State Electrolyte By Tape Casting Method

In recent years, sodium ion batteries have shown its potential to compliment lithium ion batteries, especially in stationary energy storage system. Additionally, all-solid-state battery is perceived as the holy-grail battery. While numerous research efforts have been devoted to the search of solid-state materials with high ionic conductivity, it is paramount to reduce the thickness of the electrolyte to achieve a high energy density. In this study, the NASICON electrolyte is prepared by tape casting method and its thickness is controlled by the scrapper height during casting. It is realised that the areal specific resistance of the electrolyte is proportional to the thickness of the electrolyte and the 60 μm thick electrolyte shows an extremely low resistance of 42.7 Ω cm2. More importantly, such process is highly repeatable for large-scale production of thin freestanding solid-state electrolyte, which can be used in conventional bulk battery, redox-flow batteries, or metal-air batteries.

Improving the electrical performance of a carbon fiber reinforced polymer bipolar plate using a resin squeeze-out preprocess

Carbon fiber reinforced polymer (CFRP) is attracting attention as a bipolar plate (BP) material for proton-exchange membrane fuel cells (PEMFCs) due to its high specific stiffness, strength and chemical resistance. However, the low electrical conductivity of CFRP acts as an obstacle in its application, and various studies have been conducted to improve its areal specific resistance (ASR). In particular, the electrical performance of channel-shaped BPs has been dramatically reduced because the resin flow of CFRP was blocked by the groove shape. In this study, the electrical conductivity of a channel-shaped CFRP BP was improved by a preprocess of resin squeezing out. Resin squeeze-out conditions were determined based on the resin viscosity and degree of cure (DoC). Using the resin squeeze-out process, extra resin was removed, and the carbon fiber volume fraction increased by inducing proper resin flow. The mechanical properties and electrical performance of the CFRP BPs were evaluated according to a 2025 Department of Energy (DOE) technical target. Through the optimal resin squeeze-out process, the electrical and mechanical properties of the channel-shaped CFRP BP were improved to satisfy the 2025 DOE target.

Robust Adamantane-Based Membranes with Enhanced Conductivity for Vanadium Flow Battery Application.

Membranes with high conductivity, high selectivity, and high stability are urgently needed for high-power-density vanadium flow batteries (VFBs). Enhancing membrane conductivity presents many challenges, often resulting in sacrificing membrane selectivity and mechanical strength. To overcome this, new robust adamantane-based membranes with enhanced conductivity are constructed for VFB. Low-content basic piperazine (IEC = 0.78 mmol g−1) and hydrophilic hydroxyl groups are introduced into highly rigid, hydrophobic adamantane containing poly(aryl ether ketone) backbone (PAPEK) and then selectively swelled to induce microphase separation and form ion transport pathways. The highly rigid and hydrophobic PAPEK exhibits high swelling resistance and provides the membranes with slight swelling, high selectivity, and high mechanical strength. The selective swelling temperature has a significant influence on the areal resistance of the resulting membrane, e.g., the PAPEK-130 membrane, when selectively swelled at 130 °C, has low areal resistance (0.22 Ω∙cm2), which is approximately two-fifths that of the PAEKK-60 membrane (treated at 60 °C, 0.57 Ω∙cm2). Consequently, the resulting PAPEK membranes exhibit low swelling, high selectivity, and low areal resistance, with the VFB constructed with a PAPEK-90 membrane exhibiting excellent energy efficiency (91.7%, at 80 mA∙cm−2, and 80.0% at 240 mA∙cm−2) and stable cycling performance for 2000 cycles.

Practically Accessible All‐Solid‐State Batteries Enabled by Organosulfide Cathodes and Sulfide Electrolytes

AbstractThe combination of organic electrode materials and sulfide electrolytes is expected to enable the development of all‐solid‐state organic batteries featuring high energy density, safety, and sustainability. Here, thiuram hexasulfide is first reported as a low‐cost and high‐capacity cathode material for solid‐state organic batteries based on sulfide electrolytes. Notably, a capacity of ≈600 mA h g−1 is delivered and the capacity retention is 80.8% after 500 cycles. An electrochemically reversible change of the cathode interface is revealed upon cycling. The full cell displays an oscillating stress change of up to 0.6 MPa during cycling, predominated by the anode side. The energy density is 1140 Wh kg−1 at the material level and 376 Wh kg−1 at the electrode level, which are among the best‐reported organic cathodes to date. A high areal capacity of 10.4 mA h cm−2 is reached with a high mass loading cathode. A dry‐film approach is further explored to manufacture sheet‐type cells. The free‐standing Li6PS5Cl film with a thickness of only 48 µm demonstrates an ultralow areal resistance of 3.9 Ω cm2, which significantly boosts the cell‐level energy density and reduces the cell internal resistance.

Polyimide as a durable cathode for all-solid-state Li(Na)−organic batteries with boosted cell-level energy density

The integration of organic electrode materials (OEMs) with solid-state electrolytes (SSEs) is expected to build an all-solid-state battery (ASSB) with long-term sustainability, high safety, and high energy density. Despite this great promise, the cell-level energy density is still far from practically applicable, which stems from the ultrathick SSE layer and thin cathode layer used in a pellet-type ASSB design. Here, a cost-effective polyimide (PI) material was first exploited as an organic cathode for sulfide-based ASSBs. A capacity of ~190 mAh g−1 was delivered with almost no capacity decay over 300 cycles. Moreover, for the first time, a dry-film approach was introduced to manufacture a sheet-type Li−organic ASSB with an ultrathin SSE layer and a high-areal-loading PI cathode. Notably, PI is a perfect candidate for dry-film technology due to its high thermal stability and extraordinary chemical inertness toward sulfide SSEs. Remarkably, the free-standing SSE membrane was merely 46 µm thick, and an ultralow areal resistance of 3.3 Ω cm2 was achieved, more than tenfold lower than that of reported SSE pellets. One order of magnitude boost in the cell-level energy density was achieved. This work presents a significant leap in transferring organic ASSB technology from laboratory research to factory manufacturing.