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The stack is the core component of large-scale flow battery system. Based on the leakage circuit, mass and energy conservation, electrochemicals reaction in porous electrode, and also the effect of electric field on vanadium ion cross permeation in membrane, a model of kilowatt vanadium flow battery stack was established. The electro chemical reaction parameters, ion concentration and temperature of each single cell in the stack were calculated respectively. The imbalance of vanadium ion concentration and the effects of current density and electrolyte temperature on the electrolyte imbalance in the stack were studied. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rattan is converted to 3D current collector via a facile and cost-effective strategy. • The CR owns hierarchical structure, directional channels, and superior stability. • 3D MnO 2 cathode with a large mass loading of 10 mg cm−2 is successfully constructed. • Interfacial charge transfer kinetics can be significantly improved by 3D structure. • The cathode offers substantial areal capacity of 3.65 mAh cm−2 and good cyclability. Aqueous zinc-ion batteries (AZIBs) have emerged as prospective candidates for wide-scale energy storage, benefiting from their exceptional reliability and budget-friendliness. To tackle the challenge of limited energy density of AZIBs, it is pivotal to explore cathodes with substantial mass loadings. In this study, rattan is converted into a three-dimensional (3D) current collector with directional channels, high compressive strength, good electrolyte affinity, and superior electrochemical stability through a process involving ultraviolet light irradiation-assisted delignification followed by high-temperature carbonization. Using this current collector and a straightforward slurry pasting method, a 3D MnO 2 cathode featuring substantial loading amount of 10 mg cm−2 for active material can be constructed. This cathode's rich channel structure allows the carbon nanotube/MnO 2 composite material to establish full contact with the electrolyte, significantly facilitating interfacial charge transfer. The optimized cathode achieves an outstanding areal capacity of 3.65 mAh cm−2 at 0.1 A/g and sustains 1.52 mAh cm−2 at 1 A/g. Besides, the capacity retention remains at 60.2 % after 1000 cycles, even under such large mass loading. Notably, the fabrication procedure of the 3D cathode is simple, and the associated costs are relatively low compared to other 3D cathodes for AZIBs. These findings present an effective strategy for developing cost-effective and high-performance electrodes with large areal capacities, advancing energy storage technologies. [ABSTRACT FROM AUTHOR]

The synthesis of self-assembled composite materials via a one-pot technique offers a promising strategy for designing modernized electrodes for use in solid oxide electrochemical cells based on both oxygen-ionic and proton-conducting electrolytes. Within the present work, a BaCe 0.5 Fe 0.5 O 3–δ composite (extensively investigated in the literature as a triple conductor) was prepared as both dense and porous ceramics. The thermal properties of these materials were subsequently characterized via a range of complimentary techniques, including high-temperature X-ray diffraction, thermogravimetry, and dilatometry analyses. The employed methods allow for the refinement of the compositions for both Ce- and Fe-enriched phases, as well as the determination of the thermal expansion behaviors of both the basic components and the composite as a whole. The experimental results demonstrate that the Ce- and Fe-based phases exhibit markedly disparate thermomechanical responses, which represents a significant limitation for the joint application of BaCe 0.5 Fe 0.5 O 3–δ -derived electrodes with a range of electrolyte representatives. While the thermomechanical discrepancy can be reduced for the porous state of the electrodes, greater attention should be paid to the microstructural integrity of such electrodes and the quality of the electrolyte/electrode interface under long-term and cycling operating conditions. Therefore, this work provides complementary information on the various functional properties of dual-phase BaCe 0.5 Fe 0.5 O 3–δ composites. [Display omitted] • Dual-phase BaCe 0.5 Fe 0.5 O 3–δ composite materials were studied. • Porous and dense BaCe 0.5 Fe 0.5 O 3–δ -based ceramics were fabricated. • A complex of complimentary high-temperature techniques was used. • Insights in their thermomechanical behavior were provided. [ABSTRACT FROM AUTHOR]

This paper reports on the study of the electrochemical behavior of porous Bi 3 Ru 3 O 11 – 40 wt% Bi 1.6 Er 0.4 O 3 electrodes on a Bi 2 O 3 – 10 wt% Bi 24 B 2 O 39 electrolyte in a symmetric cell configuration by impedance spectroscopy. The dependence of the area specific resistance (ASR) for electrode polarization on the partial pressure of oxygen replaced from P O 2 − 1 / 2 to P O 2 − 3 / 4 with decreasing thickness of the layer, which inhibited wetting. This indicates a change in the rate-limiting oxidation-reduction reactions of oxygen. It is assumed that the dissociation of adsorbed oxygen molecules on the active catalytic centers of the triple phase boundary (TPB) is the limiting stage of a surface oxygen exchange, and with a decrease in the layer thickness, additional difficulty in the transfer of gaseous oxygen molecules from the gas phase to these active catalytic centers is observed. [ABSTRACT FROM AUTHOR]

This work aims to analyze the effect of pore size on the catalytic reaction of 316L stainless steel electrodes. Porous compacts were fabricated using the space holder technique and sintering at low temperatures. The fabricated porous compacts were characterized using computed tomography and the hydrogen evolution reaction was evaluated under 0.5 M and 1.5 M NaOH. Results indicate that porosity is well controlled by the pore formers, which allows different pore size distributions of pores with similar relative density values to be obtained. The pores are fully interconnected, allowing the passing of fluid throughout the compacts. Permeability is sensitive to the pore size, increasing as the pore size does. The catalytic activity of hydrogen evolution reaction HER is improved as the pore volume and pore size increase concerning the compact fabricated without pore formers. The compact that showed higher Cdl and Rf values was fabricated with S100 pore formers, which means a higher active area that favors the HER. It can be concluded that porosity enhances HER reactivity. However, larger pores are not beneficial due to a more significant permeability value. [ABSTRACT FROM AUTHOR]

A comprehensive, three-dimensional, macro-scale model was developed to simulate non-aqueous deep eutectic solvent (DES) electrolyte flow batteries. The model's feasibility was validated by comparing the simulated polarization data with the experimental results. Utilizing this model, the work reported here compared the flow characteristics and electrochemical properties of electrolytes with different redox couples within the porous electrodes of the batteries. Despite variations in the active materials, the distribution of the electrolyte flow rate showed uniformity due to consistent electrode and flow channel designs, indicating that the structural design of electrodes and channels has a more significant impact on electrolyte flow than the physicochemical properties of the electrolytes themselves. This study also highlighted that TEMPO and Quinoxaline DES electrolytes exhibited less flow resistance and more uniform concentration distributions, which helped reduce overpotentials and enhance battery energy efficiency. Furthermore, this research identified that the highest average overpotentials occurred near the membrane for all the redox couples, demonstrating that electrochemical reactions in DES electrolyte flow batteries primarily occur in the region close to the membrane. This finding underscores the importance of optimizing active redox ions transport in electrolytes to enhance electrochemical reactions in the proximal membrane region, which is crucial for improving flow battery performance. [ABSTRACT FROM AUTHOR]

This study presents a prototype non-aqueous redox flow battery that advances the capabilities of conventional systems by achieving a wide operational voltage range, high efficiency, and prolonged cycle life. Leveraging the redox pair 10-[2-(2-methoxy ethoxy)ethyl]-10H-phenothiazine and 2-ethylterephthalonitrile, the system delivers a discharge cell voltage ranging from approximately 2.25 V to 1.9 V. To address the economic challenges associated with non-aqueous redox flow batteries, this work explores a cost-efficient design using a symmetric cell architecture and a low-cost, porous separator. To evaluate the feasibility and scalability of this approach, a 2D time-transient reactive transport model is developed, integrating Nernst–Planck electroneutrality principles and porous electrode kinetics. The model is optimized and validated against experimental charge/discharge cycles, accurately predicting voltage behavior. Additionally, the study provides crucial insights into the crossover phenomenon, elucidating the transport dynamics and spatial distribution of active species within the cell. This comprehensive framework establishes a robust foundation for future efforts to scale and optimize non-aqueous redox flow batteries for large-scale energy storage applications, bringing them closer to commercial viability. [ABSTRACT FROM AUTHOR]

[Display omitted] Although aqueous organic redox flow battery (RFBs) is a highly promising energy storage device, the redox reaction kinetics of the anode organic electrolyte material, especially for phenazine derivatives, are limited by low electrochemical activity of traditional porous carbon electrodes. Herein, Co/NC composite electrocatalyst was elaborated to significantly enhance the redox reaction kinetics of phenazine derivatives, in which Co/NC electrocatalyst could improve energy efficiency of aqueous phenazine RFBs by 43.2 % compared to pure carbon felt electrodes at current density of 100 mA/cm2. Control experiments combined with density functional theory calculations identified that in addition to the more reactive sites provided by relatively large electrochemical active surface area accelerate the redox reaction of phenazine derivatives, the Co and Co N C reaction sites provided by Co modification not only reduce the energy barrier, but also provide new convenient reaction pathways based on selective interfacial water behavior, further promoting the reduction reaction of phenazine derivatives. This study gives an in-depth understanding of the synergistic effects between phases in composite electrocatalysts and proposes a new behavioral mechanism for the redox reactions of organic electroactive species on the surface of catalytic electrodes. [ABSTRACT FROM AUTHOR]

The issue of long charging time for electric vehicles has been a matter of serious concern, and the problem is mainly stemmed from the graphite anode. The slow kinetics of pure graphite can lead to the formation of the lithium metal during fast charging, which triggers cycle degradation and safety issues of electric vehicles. In order to ameliorate the fast charging issue, a spherical hard carbon/graphite porous electrode is devised. Based on this, the discharge capacity ratio at 3C shows an improvement of about 40% at 25°C and at 1C shows an improvement of about 18% at 0°C. Additionally, the 300-cycle capacity retentions exhibit increases of 12% and 14% at temperature of 25°C and 50°C, respectively. Generally, the analysis shows that the spherical hard carbon/graphite porous electrode has more uniform porous structure, shorter transport path, less nano-scale powder and a certain voltage buffer ability compared to the pure graphite powder system, which enhance the ion transport kinetics, and reduce the side reactions under the high temperature, so as to effectively improve the fast charging performance and cycle life of the LIBs. It is also proved that the kinetics improvement is not only attributed to the high kinetics inherited from the instinct of hard carbon, but also the porous electrode structures constructed by the two-size powder system of graphite and hard carbon. [ABSTRACT FROM AUTHOR]

The deployment of solid and quasi‐solid electrolytes in lithium metal batteries is envisioned to push their energy densities to even higher levels, in addition to providing enhanced safety. This article discusses a set of hybrid solid composite electrolytes which combine functional properties with electrode compatibility and manufacturability. Their anodic stability >5 V versus Li+/Li and compatibility with lithium metal stem from the incorporated ionic liquid electrolyte, whereas the organic‐inorganic hybrid host structure boosts their conductivity up to 2.7 mS cm−1 at room temperature. The absence of strong acids enables compatibility with porous NMC811 electrodes. Liquid precursor solutions can be readily impregnated into porous electrodes, facilitating cell assembly. Electrolytes containing TFSI− as the only anion have a superior compatibility toward high‐voltage positive electrode materials, whereas electrolytes containing both FSI− and TFSI− have a better compatibility toward lithium metal. Using the former as catholyte and the latter as anolyte, NMC811/Li coin cells retain up to 100% of their initial capacity after 100 cycles (0.2 C, 3.0–4.4 V vs Li+/Li). Because of their unprecedented combination of functional properties, electrode compatibility, and manufacturability, these hybrid solid composite electrolytes are potential candidates for the further development of lithium metal battery technology. [ABSTRACT FROM AUTHOR]

Aqueous organic redox flow batteries (AORFBs), which exploit the reversible redox reactions of water-soluble organic electrolytes to store electricity, have emerged as a promising electrochemical energy storage technology. Organic electrolytes possess fast electron-transfer rates that are two or three orders of magnitude faster than those of their inorganic or organometallic counterparts; therefore, their performance at the electrode is limited by mass transport. Direct adoption of conventional cell stacks with flow fields designed for inorganic electrolytes may compromise AORFB performance owing to severe cell polarization. Here, we report the design of a flow field for flow-through type AORFBs based on three-dimensional multiphysics simulation, to realize the uniform distribution of electrolyte flow and flow enhancements within a porous electrode. The electrolyte flow is visualized by operando imaging. Our results show that multistep distributive flow channels at the inlet and point-contact blocks at the outlet are crucial geometrical merits of the flow field, significantly reducing local concentration overpotentials. The prototype pH-neutral TEMPTMA/MV cell at 1.5 M assembled with the optimized flow field exhibits a peak power density of 267.3 mW cm-2. The flow field design enables charging of the cell at current densities up to 300 mA cm-2, which is unachievable with the conventional serpentine flow field, where immediate voltage cutoff of the cell occurs. Our results highlight the importance of AORFB cell stack engineering and provide a method to visualize electrolyte flow, which will be appealing to the field of aqueous flow batteries. [ABSTRACT FROM AUTHOR]

Supercapacitor/pseudocapacitor structures with electrodes and electrolytes based on conductive polymers, but not only, have been analyzed using advanced molecular dynamics simulation techniques. Results indicated in the literature were used to confirm the results obtained for the specific capacitance and energetic performances of the systems. New material classes like Polymer-MXene electrodes ((PANI)/Ti3C2, PFDs/Ti3C2Tx) present increased capacitance in comparison with simple polymeric composites (PETC or PTh). Combinations of polymers and metallic oxide, like PANI/V2O5, present high capacitance, but new variants can provide improved performance. Different techniques, like electrode doping, adding different salts in the electrolyte (gel electrolyte), and using porous electrodes, can also improve performance. Steps for the non-invasive simulation method with HFSS (Ansys) are defined, and the materials are described at the molecular level as well as the interactions between atomic groups. Macroscopic properties of the system are determined (conductivity, specific energy) and represented on parametric graphs. A complex set of parameters is varied in order to optimize the structures through parameter correlation. Different stages of correlation are considered in order to establish the final sample design and improve energetic performance. An increase of about 8–28% can be obtained concerning the specific energy of the supercapacitor. Prediction, design, atypical behavior, and resonance are addressed using this technique. [ABSTRACT FROM AUTHOR]

In this work, a nanoporous ultrananocrystalline diamond film (B-UNCDWS/TDNT/Ti) was obtained and compared with a commercial electrode in the degradation of methomyl, a recalcitrant pesticide. The morphological and structural differences between the materials were highlighted by SEM and XRD analysis: while the commercial electrode presented a regular and planar surface with microcrystalline grains, supported by XRD features, the B-UNCDWS/TDNT/Ti electrode presented a porous morphology with DRX features indicating a high film renucleation rate. Those differences affected the electrooxidation of methomyl; B-UNCDWS/TDNT/Ti was responsible for faster and more economic degradation of the pollutant, achieving a methomyl degradation of 78% (against 35% by the commercial electrode). The highly porous surface of UNCDWS/TDNT/Ti provides an electrochemical area threefold greater than the one found in the commercial electrode, justifying the better efficiency in the formation of persulfate, which can be singled out as the main mechanism in methomyl degradation. [ABSTRACT FROM AUTHOR]

The electrochemical performances of an oxygen-evolving anode produced by the reactivation of waste Ti substrate by a typical IrO2-Ta2O5 coating are correlated to the textural (non)uniformities of the coating and its exhaustion state. Coating degradation is considered operational loss of the activity in a metal electrowinning process. It was found that (pseudo)capacitive performances can vary over the coating surface by 20–30% and depend on the type of dynamics of the input perturbation: constant through cyclic voltammetry (CV) or discontinuous time-dependent through electrochemical impedance spectroscopy (EIS). CV-EIS data correlation enabled profiling of the capacitive properties through the depth of a coating and over its surface. The correlation was confirmed by the findings for the analysis of coating activity for an oxygen evolution reaction, finally resulting in the reliable proposition of a mechanism for the operational loss of the anode. It was found that the less compact and thicker coating parts performed better and operated more efficiently, especially at lower operational current densities. [ABSTRACT FROM AUTHOR]

This study presents a novel application-oriented approach to the mechanical characterization and subsequent modeling of porous electrodes and separators in lithium-ion cells to gain a better understanding of their real mechanical operating behavior. An experimental study was conducted on the non-linear stiffness of LiNi0.8Co0.15Al0.05O2 and graphite electrodes as well as PE separators, harvested from large-format lithium-ion cells, using compression tests. The mechanical response of the components was determined for different operating conditions, including nominal stress levels, mechanical loading rates, and mechanical cycles. The presented work describes the test procedure, the experimental setup, and an objective evaluation method, allowing for a detailed summary of the observed mechanical behavior. A distinct nominal stress level and mechanical cycle dependency of the non-linear stiffnesses of the porous materials were found. However, no clear dependency on compression rate was observed. Based on the experimental data, a poroelastic mechanical model was utilized to predict the non-linear behavior of these porous materials under real mechanical operating scenarios with a normalized root-mean-squared error less than 5.5%. The results provide essential new insights into the mechanical behavior of porous electrodes and separators in lithium-ion cells under real operating conditions, enabling the accelerated development of high-performing and safe batteries for various applications. [ABSTRACT FROM AUTHOR]

The increasing need for electrode materials exhibiting improved performance to meet the requirements of supercapacitors is on the rise. Hybrid electrodes, which combine reduced graphene oxide (rGO) with transition metal-based oxides, have emerged as promising materials due to their impressive specific capacitance and cost-effectiveness, attributed to their synergistic properties. In the present study, a binder-free CoOrGO composite electrode was synthesized using a facile, fast, and simple one-step co-precipitation method. This was done to improve both capacity and stability for supercapacitor applications. The composite materials underwent comprehensive characterization utilizing various surface analytical techniques, including X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), field-emission scanning electron microscopy (FE-SEM), fourier-transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analysis. Electrochemical measurements of the CoOrGO composite revealed at current density of 2 A cm− 2 a specific capacitance of 132.3 mF cm− 2, with an impressive 95.91% retention of capacitance after 7000 cycles. The results from electrochemical impedance spectroscopy (EIS) highlighted a meager low relaxation time constant of 0.53 s for the composite films. The reason behind this can be linked to the synergistic interactions, and minimal charge transfer resistance exhibited by the porous electrode without binders. Based on the obtained results, this work introduces a flexible methodology for crafting advanced energy storage systems. This demonstrates the potential for designing high-efficiency supercapacitors that are suitable for a broad range of large-scale applications. [ABSTRACT FROM AUTHOR]

This study proposes the synthesis of SnO 2 /Ti 3 C 2 T x composites on porous graphene electrodes (PGEs) for high-performance humidity sensors. In the heterojunction structure of SnO 2 /Ti 3 C 2 T x composites, SnO 2 nanoparticles prevented the layered structure of Ti 3 C 2 T x to collapse and restack. Moreover, the high specific surface area of the SnO 2 /Ti 3 C 2 T x composites provided more adsorption sites that improved their response. Porous graphene was fabricated by a fiber laser-induced process on the polyimide film as an electrode layer for flexible humidity sensors. The characteristics of the SnO 2 /Ti 3 C 2 T x composites and PGEs were examined and investigated. SnO 2 /Ti 3 C 2 T x composites were drop-cast on PGEs to fabricate the humidity sensor. Furthermore, the response of humidity sensors was tested in various RHs. The performance of the proposed humidity sensor demonstrated a wide detection range of 11–97 % RH, low hysteresis of 2.8 % RH, low response/recovery times of 14/49 s, high sensitivity of 862.19 kΩ/%RH, excellent long-time stability and repeatability, and good flexibility. In the future, the proposed sensor can be widely applied in human respiration monitoring, non-contact switch, and detection of volatile organic compounds. [ABSTRACT FROM AUTHOR]

This paper reports on the novel composite membrane electrolytes used in Zn/MnO2, Al/MnO2, Al/air, and zinc/air electrochemical devices. The composite membranes were made using poly(vinyl alcohol), poly(acrylic acid), and a sulfonated polypropylene/polyethylene separator to enhance the electrochemical characteristics and dimensional stability of the solid electrolyte membranes. The ionic conductivity was improved significantly by the amount of acrylic acid incorporated into the polymer systems. In general, the ionic conductivity was also enhanced gradually as the testing temperature increased from 20 to 80 °C. Porous zinc gel electrodes and pure aluminum plates were used as the anodes, while porous carbon air electrodes or porous MnO2 electrodes were used as the cathodes. The cyclic voltammetry properties and electrochemical impedance characteristics were investigated to evaluate the cell behavior and electrochemical properties of these prototype cells. The results showed that these prototype cells had a low bulk resistance, a high cell power density, and a unique device stability. The Al/MnO2 cell achieved a density of 110 mW cm−2 at the designated current density for the discharge tests, while the other cells also exhibited good values in the range of 70–100 mW cm−2. Furthermore, the Zn/air cell consisting of the PVA/PAA = 10:5 composite membrane revealed an excellent discharge capacity of 1507 mAh. This represented a very high anode utilization of 95.7% at the C/10 rate. [ABSTRACT FROM AUTHOR]

This study examines the use of surface-modified biochar as a porous electrode material for the capacitive deionization removal of chloride and fluoride ions. Incorporation of titanium dioxide and amine groups on biochar aims to increase surface-active sites, facilitate salt ion diffusion, and improve charge efficiency and cation/anion selectivity in asymmetric capacitive deionization. Titania, amine, and activated biochar are denoted as TB, AmB, and AcB, respectively. Physical and electrochemical characterizations were performed to investigate the surface properties of fabricated materials. At the optimum TiO2 loading of 5% (TB-05), the specific capacitance of TB-05 electrode was improved by 35% at scan rate of 1 mV s–1 in comparison to the AcB electrode, despite a decrease in the specific surface area. Three different asymmetric capacitive deionization cell designs—AmB||TB-05, AcB||TB-05, and AmB||AcB—and two symmetrical cell designs—AcB||AcB and TB-05||TB-05 (anode||cathode)—were tested. A symmetric cell design TB-05||TB-05 had a NaCl removal capacity of 8.51 mg g−1, a 42% improvement in comparison to a symmetric AcB cell (6.01 mg g−1). Further, an asymmetric cell AmB||TB-05 showed 67% charge efficiency improvement over symmetric AcB cell, likely due to a reduced co-ion effect. For fluoride removal, a symmetric TB-05 cell showed a removal capacity of 3.51 mg g−1. This study promotes simple surface-modification methods to make inexpensive commercial biochar into a sustainable, and efficient electrode material available for a scale-up asymmetric capacitive deionization. [ABSTRACT FROM AUTHOR]

Electrodes, which offer sites for mass transfer and redox reactions, play a crucial role in determining the energy efficiencies and power densities of redox flow batteries. This review focuses on various approaches to enhancing electrode performance, particularly the methods of surface etching and catalyst deposition, as well as some other advanced strategies for regulating electrode surface properties. These approaches aim to increase active sites and enhance kinetics for the redox reactions, which are crucial for elevating power density and electrolyte utilization, eventually determining the performance of the flow battery. Highlighting the need for interdisciplinary research, this mini‐review suggests that future advancements in electrode design will significantly impact the commercial viability and adoption of redox flow batteries in sustainable energy storage solutions. [ABSTRACT FROM AUTHOR]

All-solid-state batteries (ASSBs) with adequately selected cathode materials exhibit a higher energy density and better safety than conventional lithium-ion batteries (LIBs). Ni-rich layered cathodes are benchmark materials for traditional LIBs owing to their high energy density. Recent studies have highlighted the advantages of using crack-free, single-crystalline cathode materials in ASSBs. In this study, a scalable infiltration sheet-type process was used to fabricate composite electrodes with different cathode-material morphologies for ASSBs. Typically, crack-free single-crystalline materials exhibit better retention performance and lower rate capability (i.e., slower kinetics in charge‒discharge processes) than polycrystalline cathode materials. Li6PS5Cl-infiltrated polycrystalline electrodes showed excellent retention performance and rate capability. Galvanostatic intermittent titration technique analysis and transmission electron microscopy of the single-crystalline electrode confirmed severe polarization and the presence of a rock-salt-structure layer in the cathode particles; these results indicated side reactions within the layered structure of the material. In contrast, composite electrodes consisting of polycrystalline cathode materials infiltrated with the solid electrolyte Li6PS5Cl showed excellent electrochemical performance owing to intimate electrode–electrolyte interfacial contact. The result from this study confirmed the critical influence of interface engineering and material morphology on the overall performance and stability of ASSBs and could facilitate the development of high-performance ASSBs in the future. This study introduces a technique for utilizing conventional lithium-ion battery electrodes in all-solid-state batteries. By infiltrating a solid electrolyte solution into the porous electrode, the effects based on the morphology of the active material were investigated. In poly-crystalline materials, high coverage and the formation of a thin side reaction layer were observed. Consequently, the infiltration process also confirmed the superior performance of poly-crystalline materials. [ABSTRACT FROM AUTHOR]

The current goals for implementing the hydrogen economy have highlighted a need to further optimize water‐splitting technologies for clean hydrogen production. Proton exchange membrane water electrolysis (PEMWE) is a leading technology, but further optimizations of anode materials including the porous transport layer (PTL) and the adjacent catalyst layer (CL) are required to increase overall cell performance and reduce cost. This literature review describes advances in PTL development and characterization, highlighting early PTL characterization work and most common methods including capillary flow porometry and mercury intrusion porometry, optical imaging, neutron and x‐ray radiography, and x‐ray computed tomography. The article also discusses PTL protective coatings and their characterizations, focusing on platinum group metal (PGM)‐based coatings, alternative non‐PGM‐based coatings, post‐treated PTLs, and investigations into thin PGM‐based coatings. Furthermore, it highlights the integration of the PTL and the adjacent CL along with associated characterization challenges. Lastly, this review discusses future developments in the characterization needed to improve PEMWE's performance and long‐term durability are discussed. [ABSTRACT FROM AUTHOR]

Abstract Recent advances in 3D printing have enabled the manufacture of porous electrodes which cannot be machined using traditional methods. With micron-scale precision, the pore structure of an electrode can now be designed for optimal energy efficiency, and a 3D printed electrode is not limited to a single uniform porosity. As these electrodes scale in size, however, the total number of possible pore designs can be intractable; choosing an appropriate pore distribution manually can be a complex task. To address this challenge, we adopt an inverse design approach. Using physics-based models, the electrode structure is optimized to minimize power losses in a flow reactor. The computer-generated structure is then printed and benchmarked against homogeneous porosity electrodes. We show how an optimized electrode decreases the power requirements by 16% compared to the best-case homogeneous porosity. Future work could apply this approach to flow batteries, electrolyzers, and fuel cells to accelerate their design and implementation.

Recent advances in 3D printing have enabled the manufacture of porous electrodes which cannot be machined using traditional methods. With micron-scale precision, the pore structure of an electrode can now be designed for optimal energy efficiency, and a 3D printed electrode is not limited to a single uniform porosity. As these electrodes scale in size, however, the total number of possible pore designs can be intractable; choosing an appropriate pore distribution manually can be a complex task. To address this challenge, we adopt an inverse design approach. Using physics-based models, the electrode structure is optimized to minimize power losses in a flow reactor. The computer-generated structure is then printed and benchmarked against homogeneous porosity electrodes. We show how an optimized electrode decreases the power requirements by 16% compared to the best-case homogeneous porosity. Future work could apply this approach to flow batteries, electrolyzers, and fuel cells to accelerate their design and implementation. [ABSTRACT FROM AUTHOR]

An electrical double‐layer capacitor (EDLC) comprises two porous electrodes sandwiching an electrolyte‐permeable separator, which prevents the electrodes from short‐circuiting. While previous studies have mainly focused on electrolyte and electrode properties of EDLCs, the device configuration in terms of electrode and separator sizes received less attention, with separators often simplistically modelled as infinitely large reservoirs of ions. Herein, we investigate how the relationship between electrode and separator thicknesses impacts EDLC charging. We find that the assumption of bulk reservoir holds only under specific conditions. Moreover, we identify a tradeoff between stored energy density and pressure variations within the separator, potentially jeopardizing the EDLC durability. We also explore the influence of ionic liquid additives on EDLC charging. While prior research has shown that trace amounts of uncharged additives with strong electrode affinity can significantly enhance energy storage, we observe this effect as negligible for electrodes and separators of comparable sizes. Instead, we show how to optimize EDLC performance by fine‐tuning the concentration of additives and separator‐to‐electrode size ratio to maximize stored energy density. [ABSTRACT FROM AUTHOR]

In polymer membrane fuel cells (PEMFC), the pore microstructure and the effective diffusion coefficient ( D eff ) of the catalytic layer have a significant impact on the overall performance of the fuel cell. In this work, numerical methods to simulate PEMFC catalytic layers were used to study the effect of isotropy ( I xy ) on the D eff . The proposed methodology studies reconstructed systems by Simulated Annealing imaging with different surface fractions of microstructures composed by two diffusive phases: agglomerates and pores. The D eff is determined numerically by the Finite Volume Method solved for Fick's First Law of Diffusion. The results show that the proposed methodology can effectively quantify the effect of isotropy on the D eff for both diffusion phases. Two trends were obtained in the magnitude of the D eff concerning the change in isotropy: (1) an analytical equation is proposed in this article for D eff ≥ 5 % D 0 and (2) numerical solutions are determined for D eff < 5 % D 0. In our analytical equation are both a lineal and a logarithmic sweep. When the surface fraction is ∅ = 50%, the D eff decreases more linearly than ∅ = 10 % at the beginning of the isotropy change, which indicates that small changes in isotropy in the particulate material modify it drastically; under these conditions the diffusion coefficient in the pore is predominant. (3) When the surface fraction is less than 50%, the D eff decreases more exponentially at the beginning and more linearly at the end of the isotropy change, which shows that small isotropy changes in the bar-aligned material drastically alter it. In this trend, diffusion in the agglomerate is less affected by isotropy. The proposed methodology can be used as a design tool to improve the mass transport in porous PEMFC electrodes. [ABSTRACT FROM AUTHOR]

[Display omitted] Supercapacitors have the advantages of fast charging and discharging speeds, high power density, long cycle life, and wide operating temperature range. They are widely used in portable electronic equipment, rail transit, industry, military, aerospace, and other fields. The design and preparation of low-cost, high-performance electrode materials still pose a bottleneck that hinders the development of supercapacitors. In this paper, coal was used as the raw material, and the coal-based porous carbon electrode material was constructed using the iodine intercalation-assisted activation method and used for supercapacitors. The CK-700 electrode exhibits excellent charge storage performance in a 6 M potassium hydroxide (KOH) electrolyte, with a maximum specific capacitance of 350 F/g at a current density of 0.5 A/g. In addition, it has an excellent rate performance (310 F/g at 1 A/g) and cycle stability (capacitance retention up to 91.7 % after 30000 cycles). This work provides a method for realizing high-quality, high-yield and low-cost preparation of coal-based porous carbon, and an idea for improving the performance of supercapacitors. [ABSTRACT FROM AUTHOR]

The use of biomass as carbon precursors has been extensively investigated, with a particular emphasis on examining the properties of derived porous carbon and its application in electrical double‐layer capacitors (EDLCs). Biomass‐derived porous carbon‐based electrodes have shown promising properties that can improve the efficiency of EDLCs. However, despite the extensive research in this field, no definitive solution has been proposed. This review investigates in depth three main factors that impact the electrochemical performance of derived porous carbon‐based electrodes: (1) the initial properties of raw biomass as carbon precursors, (2) operating conditions, and (3) physicochemical properties of biomass‐derived porous carbon materials. Examined operating conditions include synthesis techniques, activating agents, the mass ratio of the activating agent to the raw biomass as porous carbon precursors, carbonization/activation duration, operating temperature, and the mass of the active material in the electrode. The surface morphology and surface functional groups were used to evaluate the physicochemical properties of derived porous carbon materials. Multiple factors influence the properties of porous carbon derived from biomass and, consequently, the efficiency of the electrodes made from these materials. This study reveals that the properties of porous carbon‐based electrodes derived from biomass vary from one biomass to another and are affected by various parameters, conditions, and synthesis techniques. Therefore, it is impossible to rely exclusively on a single factor to improve the electrochemical performance of EDLC electrodes. A thorough consideration of the multiple factors is required to optimize the properties and performance of the electrodes. [ABSTRACT FROM AUTHOR]

The effects of process parameters on the electroless plating of ionic polymer–metal composites (IPMCs) were studied in this work. Specifically, the NaBH4 reduction of platinum onto Nafion-117 was characterised. The effects of the concurrent variation of NaBH4 concentration, stir time and temperature on surface resistance were studied through a full factorial design. The three-factor three-level factorial design resulted in 27 runs. Surface resistance was measured using a four-point probe. A regression model with an R2 value of 97.45% was obtained. Surface resistance was found to decrease with increasing stir time (20 to 60 min) and temperature (20 to 60 °C). These responses were attributed to increased platinisation rates, resulting in more uniform electrode deposition, confirmed by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDAX) analysis. Surface resistance decreased, going from 1% to 5% NaBH4 concentration, but increased from 5% to 10% concentration. This behaviour was attributed to surface morphology: increased grain size inducing porous electrodes, in line with findings in the literature. The maximum tip displacement, measured through a computer vision system, as well as the maximum blocking force, measured through an analytical balance setup, were obtained for all 27 samples. The varying results were discussed with regards to surface and cross-sectional SEMs, alongside EDAX analysis. [ABSTRACT FROM AUTHOR]

Symmetrical solid oxide cells (SSOCs) are very useful for energy generation and conversion. To fabricate the electrode of SSOC, it is very time‐consuming to use the conventional approach. In this work, we design and develop a novel method, extreme heat treatment (EHT), to rapidly fabricate electrodes for SSOC. We show that by using the EHT method, the electrode can be fabricated in seconds (the fastest method to date), benefiting from enhanced reaction kinetics. The EHT‐fabricated electrode presents a porous structure and good adhesion with the electrolyte. In contrast, tens of hours are needed to prepare the electrode by the conventional approach, and the prepared electrode exhibits a dense structure with a larger particle size due to the lengthy treatment. The EHT‐fabricated electrode shows desirable electrochemical performance. Moreover, we show that the electrocatalytic activity of the perovskite electrode can be tuned by the vigorous approach of fast exsolution, deriving from the increased active sites for enhancing the electrochemical reactions. At 900 °C, a promising peak power density of 966 mW cm−2 is reached. Our work exploits a new territory to fabricate and develop advanced electrodes for SSOCs in a rapid and high‐throughput manner. [ABSTRACT FROM AUTHOR]

Miniaturized energy storage devices, such as electrostatic nanocapacitors and electrochemical micro-supercapacitors (MSCs), are important components in on-chip energy supply systems, facilitating the development of autonomous microelectronic devices with enhanced performance and efficiency. The performance of the on-chip energy storage devices heavily relies on the electrode materials, necessitating continuous advancements in material design and synthesis. This review provides an overview of recent developments in electrode materials for on-chip MSCs and electrostatic (micro-/nano-) capacitors, focusing on enhancing energy density, power density, and device stability. The review begins by discussing the fundamental requirements for electrode materials in MSCs, including high specific surface area, good conductivity, and excellent electrochemical stability. Subsequently, various categories of electrode materials are evaluated in terms of their charge storage mechanisms, electrochemical performance, and compatibility with on-chip fabrication processes. Furthermore, recent strategies to enhance the performance of electrode materials are discussed, including nanostructuring, doping, heteroatom incorporation, hybridization with other capacitive materials, and electrode configurations. [ABSTRACT FROM AUTHOR]

A porous electrode material consisting of NiCo2O4/RGO with an approximate diameter of 200 nm has been successfully fabricated. This promising porous material was derived from ZIF-67/RGO (zeolitic imidazolate framework-67 crystals doped with reduced graphene oxide sheets) through an ion exchange and etching process using Ni(NO3)2·6H2O followed by a thermal reaction. The composition was analyzed using spectroscopic and morphological techniques. The obtained porous and hollow structure of NiCo2O4/RGO contains rich active sites. Additionally, its improved performance and stability were demonstrated using potassium ferricyanide (K3[Fe(CN)]6) (PFC) and sodium hydroxide (NaOH) as an electrolyte. NiCo2O4/RGO in NaOH/PFC exhibited a maximum estimated specific capacitance of 212.5 F g−1 at 0.5 A g−1 and demonstrated excellent retention value reaching 91.7% after applying 10,000 cycles at 20 A g−1. This symmetric supercapacitor achieved an outstanding energy density (Ed) of 75.54 Wh kg−1 at a power density (Pd) of 1.6 kW kg−1 at 0.5 A g−1. Surprisingly, there is a 2.5-fold enhancement in Ed (from 32.44 to 75.54 Wh kg−1) of NiCo2O4/RGO through the addition of 0.3 M PFC into 3 M NaOH. The results indicate that the NiCo2O4/RGO electrode could be ideal for supercapacitors. [ABSTRACT FROM AUTHOR]

Highlights: A blade-coated composite paste, composed of a compressible 3D carbon skeleton, PEDOT:PSS, and CNTs, can naturally dry to form a porous electrode on paper with a micro- and nano-structured surface. The all-paper pressure sensor demonstrated an ultrahigh sensitivity of 1014 kPa−1, a wide responsive range up to 300 kPa, and an ultralow operating voltage of 0.01 V. The sensor showcased superior detection capability, ranging from subtle wrist pulses and robust finger taps to large-area spatial force. Flexible and wearable pressure sensors hold immense promise for health monitoring, covering disease detection and postoperative rehabilitation. Developing pressure sensors with high sensitivity, wide detection range, and cost-effectiveness is paramount. By leveraging paper for its sustainability, biocompatibility, and inherent porous structure, herein, a solution-processed all-paper resistive pressure sensor is designed with outstanding performance. A ternary composite paste, comprising a compressible 3D carbon skeleton, conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), and cohesive carbon nanotubes, is blade-coated on paper and naturally dried to form the porous composite electrode with hierachical micro- and nano-structured surface. Combined with screen-printed Cu electrodes in submillimeter finger widths on rough paper, this creates a multiscale hierarchical contact interface between electrodes, significantly enhancing sensitivity (1014 kPa−1) and expanding the detection range (up to 300 kPa) of as-resulted all-paper pressure sensor with low detection limit and power consumption. Its versatility ranges from subtle wrist pulses, robust finger taps, to large-area spatial force detection, highlighting its intricate submillimeter-micrometer-nanometer hierarchical interface and nanometer porosity in the composite electrode. Ultimately, this all-paper resistive pressure sensor, with its superior sensing capabilities, large-scale fabrication potential, and cost-effectiveness, paves the way for next-generation wearable electronics, ushering in an era of advanced, sustainable technological solutions. [ABSTRACT FROM AUTHOR]

Synopsis: This study presents a thiocyanogen-modulated alkali activation strategy for preparing N, S co-doped lignin hierarchical porous carbon (NSLHPC). Thiocyanate acts as a surface modulation mediator to introduce nitrogen and sulfur heteroatoms via oxygen replacement reaction. NSLHPC exhibits excellent electrochemical performance and long cycling lifespan in both symmetric supercapacitors and zinc-ion hybrid capacitors. [Display omitted] • Thiocyanogen-modulated alkali activation strategy for the preparation of NSLHPC. • Oxygen replacement reaction between KSCN and lignin carbon for N, S co-doping. • NSLHPC exhibits an impressive SSA of 2705.3 m2/g and a pore volume of 3.27 cm3/g. • NSLHPC presents remarkable electrochemical performance in aqueous supercapacitors. • DFT calculations reveal that N, S co-doping reduces the adsorption energy barrier of Zn2+. Constructing heteroatom-doped porous carbons with distinct charge storage properties is significant for high-energy–density supercapacitors, yet it remains a formidable challenge. Herein, we employed a thiocyanogen-modulated alkali activation strategy to synthesize N and S co-doped lignin hierarchical porous carbon (NSLHPC). In this process, thiocyanogen serves as a surface modulation mediator to substitute oxygen with nitrogen and sulfur species, while the combination of KOH activation and MgO template generates numerous nanopores within the carbon structure. The three-dimensional interconnected nanosheet architecture facilitates rapid ion transfer and enhances accessibility to active sites. Density functional theory (DFT) calculations demonstrate that introducing N and S heteroatoms through oxygen substitution reduces the adsorption energy barrier of Zn2+. Consequently, the optimized NSLHPC exhibits a remarkable specific capacitance of 438F/g at 0.5 A/g in 6 M KOH, delivering an energy density of 10.4 Wh/kg in the symmetric supercapacitor and an impressive energy density of 104.9 Wh/kg in the zinc-ion hybrid capacitor. The NSLHPC cathode also shows an excellent lifespan with capacitance retention of 99.0 % and Columbic efficiency of 100 % over 10,000 cycles. This study presents innovative strategies for engineering high-performance porous carbon electrode materials by emphasizing pore structure modulation and N, S co-doping as crucial approaches. [ABSTRACT FROM AUTHOR]

Two-layer microfluidic devices with porous membranes have been widely used in bioapplications such as microphysiological systems (MPS). Porous electrodes, instead of membranes, have recently been incorporated into devices for electrochemical cell analysis. Generally, microfluidic channels are prepared using soft lithography and assembled into two-layer microfluidic devices. In addition to soft lithography, three-dimensional (3D) printing has been widely used for the direct fabrication of microfluidic devices because of its high flexibility. However, this technique has not yet been applied to the fabrication of two-layer microfluidic devices with porous electrodes. This paper proposes a novel fabrication process for this type of device. In brief, Pluronic F-127 ink was three-dimensionally printed in the form of sacrificial layers. A porous Au electrode, fabricated by sputtering Au on track-etched polyethylene terephthalate membranes, was placed between the top and bottom sacrificial layers. After covering with polydimethylsiloxane, the sacrificial layers were removed by flushing with a cold solution. To the best of our knowledge, this is the first report on the sacrificial approach-based fabrication of two-layer microfluidic devices with a porous electrode. Furthermore, the device was used for electrochemical assays of serotonin and could successfully measure concentrations up to 5 µM. In the future, this device can be used for MPS applications. [ABSTRACT FROM AUTHOR]

The presented paper characterized the molten salt-modified Ni electrode with excellent catalytic activity towards alkaline urea electrooxidation reaction. The electrodes were modified by electrodeposition of Al from molten salt electrolytes containing NaCl-KCl-AlF3 at a temperature of 750 °C and applied potential of −1.9 V. The porous surface was obtained by anodic polarization with a potential of −0.4 V until the anodic current was equal to 0 mAcm−2. The prepared deposits' structure, surface morphology, and composition were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Anodic polarization was applied to assess the electrocatalytic activity and elucidate the urea electrooxidation mechanism in 1 M KOH + 0.33 M urea solution. The nanocrystalline structure, fine grain size, and microcracks on the surface of the studied electrodes contributed to their notably high electrochemically active surface area (ECSA). The cyclic voltammetry in the non-Faradaic regions of the samples shows that molten salt modification can increase the double layer capacitance of bare Ni plates by around ten times, from 0.29 mFcm−2 to 2.16 mFcm−2. Polarization of the electrodes in urea-containing KOH solution with potential of +1.52 V shows a significant difference in catalytic performance. For the bare nickel sample, the registered current density from the urea electrooxidation reaction was around +1 mAcm−2, and for the molten salt-modified one, it was +38 mAcm−2, which indicates the fact that the molten salt surface treatment can be a promising tool in tailoring the electrochemical properties of materials. [ABSTRACT FROM AUTHOR]

Designing and optimizing the pore structure of porous carbon electrodes is essential for diverse energy storage systems. In this study, an innovative approach spray phase‐inversion strategy was developed for the rapid and efficient fabrication of controlled porous carbon aerogel. Moreover, the aggregation structure of polyacrylonitrile is controlled by adjusting the Hansen's solubility parameter, thereby regulating the electrode material structure. Furthermore, the theoretical analysis of the spray phase‐inversion process revealed that this regulation process is jointly regulated by solvent hydrodynamic diameter and phase‐inversion kinetics. Through optimization, a novel porous carbon material was obtained that exhibited excellent performance as an electrode material. When utilized in supercapacitors for energy storage, it demonstrated a high specific capacitance of 373.1 F g−1 in a 6 M KOH electrolyte solution. Simultaneously, it has been observed that the preparation strategy for porous electrodes offers notable advantages in terms of excellent designability, broad universality, simplicity, and high efficiency, thereby holding promise for large‐scale fabrication of diverse porous electrode materials and various types of electrodes for diverse energy storage applications. [ABSTRACT FROM AUTHOR]

Thermo‐electrochemical cells (TECs) provide a new potential for self‐powered devices by converting heat energy into electricity. However, challenges still remain in the fabrication of flexible and tough gel electrolytes and their compatibility with redox actives; otherwise, contact problems exist between electrolytes and electrodes during stretching or twisting. Here, a novel robust and neutral hydrogel with outstanding stretchability was developed via double‐network of crosslinked carboxymethyl chitosan and polyacrylamide, which accommodated both n‐type (Fe2+/Fe3+) and p‐type ([Fe(CN)6]3−/[Fe(CN)6]4−) redox couples and maintained stretchability (>300%) and recoverability (95% compression). Moreover, poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) textile electrodes with porous structure are integrated into gel electrolytes that avoid contact issues and effectively boost the Pmax of n‐ and p‐type thermocell by 76% and 26%, respectively. The optimized thermocell exhibits a quick current density response and is continually fully operational under deformations, which satisfies the working conditions of wearable devices. Multiple thermocells (four pairs) are effectively connected in alternating single n‐ and p‐type cells in series and outputted nearly 74.3 mV at ΔT = 10°C. The wearable device is manufactured into a soft‐pack thermocells to successfully harvest human body heat and illuminate an LED, demonstrating the potential of the actual application of the thermocell devices. [ABSTRACT FROM AUTHOR]

In solid oxide fuel cell (SOFC), sintering of YSZ and NiO powders into porous anode plays a crucial role in determining its overall performance. In this study, a coarse-graining (CG) molecular dynamics (MD) model is developed to capture sintered half-cell composed of porous functional layer with NiO/YSZ particles and dense YSZ ceramic electrolyte layer with applied in anode-supported SOFC. The sintering process is simulated in two stages, i.e., heating process followed by temperature-holding process. This study also explores effects of sintering parameters (e.g., temperature, powder size and material compositions) on structural characteristics, including distribution of sintered triple-phase boundary (TPB) length, porosity, and pore size. It is found that structural properties vary mainly during the heating stage of sintering, while a higher sintering temperature leads to a larger TPB length and a lower porosity, while increasing in diameter ratio of the NiO powders to YSZ powders is advantageous for increasing TPB length, porosity and size pores for promoting electrode electrochemical activity. This work provides a bottom-up approach for potential optimization of SOFC fabrication condition and parameters. [ABSTRACT FROM AUTHOR]

Electrolytic capacitors store larger amounts of energy thanks to their thin dielectric layers and enlarged surface area. However, the benefits of using a liquid electrolyte are at the expense of the possibility of leakage, evaporation, or rupture of the device over time. As a solution, solid electrolytes, such as conductive polymers, substitute the liquid ones decreasing the internal resistance and enlarging the lifetime of these devices. PEDOT:PSS is a widely used conductive polymer in the formation of solid electrolytic capacitors. However, using the enlarged surface of the porous electrodes efficiently requires industrial processes, the efficacy of which has not been explored. In this work, porous aluminium electrodes with dielectric layers of different thicknesses were coated with PEDOT:PSS at different levels of doping in order to study the efficiency of the production of solid electrolytic capacitors in industry. The combination of odd random phase electrochemical impedance spectroscopy (ORP-EIS) with surface characterization techniques (SEM-EDX, GDOES) formed a methodology that allowed the study of both the electrical properties and the level of impregnation for these model systems. All samples consisting of a porous aluminium electrode with an amount of PEDOT:PSS deposited on top resulted in an inefficient degree of penetration between the two electrodes. However, the electrochemical analysis proved that the use of dopants produces systems with the highest capacitive properties. Consequently, the evolution towards better solid electrolytic capacitors does not rely solely on the proper coverage of the porous electrodes, but on the proper electrical properties of the PEDOT:PSS within the pores. [ABSTRACT FROM AUTHOR]

Sulfurized polyacrylonitrile (SPAN) is a promising cathode material for lithium-sulfur batteries owing to its reversible solid–solid conversion for high-energy-density batteries. However, the sluggish reaction kinetics of SPAN cathodes significantly limit their output capacity, especially at high cycling rates. Herein, a CNT-interpenetrating hierarchically porous SPAN electrode is developed by a simple phase-separation method. Flexible self-supporting SPAN cathodes with fast electron/ion pathways are synthesized without additional binders, and exceptional high-rate cycling performances are obtained even with substantial sulfur loading. For batteries assembled with this special cathode, an impressive initial discharge capacity of 1090 mAh g−1 and a retained capacity of 800 mAh g−1 are obtained after 1000 cycles at 1 C with a sulfur loading of 1.5 mg cm−2. Furthermore, by incorporating V2O5 anchored carbon fiber as an interlayer with adsorption and catalysis function, a high initial capacity of 614.8 mAh g−1 and a notable sustained capacity of 500 mAh g−1 after 500 cycles at 5 C are achieved, with an ultralow decay rate of 0.037% per cycle with a sulfur loading of 1.5 mg cm−2. The feasible construction of flexible SPAN electrodes with enhanced cycling performance enlists the current processing as a promising strategy for novel high-rate lithium-sulfur batteries and other emerging battery electrodes. [ABSTRACT FROM AUTHOR]

Redox Flow Batteries (RFBs) offer a promising solution for energy storage due to their scalability and long lifespan, making them particularly attractive for integrating renewable energy sources with fluctuating power output. This study investigates the performance of a prototype Zinc-Chlorine Flow Battery (ZCFB) designed for low-cost and readily available electrolytes. The ZCFB utilizes a saltwater electrolyte containing ZnCl2 and NaCl, paired with a mineral spirits catholyte. The electrolyte consists of a 4 M ZnCl2 and a 2 M NaCl solution, both with a pH of 4.55. The anode was a zinc metal electrode, while the cathode comprised a porous carbon electrode on a titanium grid current collector. The cell volume was approximately 4.0 mL, with separate reservoirs for the NaCl/H2O and mineral spirits electrolytes. Experiments were conducted under constant current conditions, with a 0.2 A charging current and a 5 mA discharge current chosen for optimal cell voltage. The study analyzed the relationship between voltage, current, power, and capacity during both charging and discharging cycles. Results from multiple charge/discharge cycles found that the current density of the battery is around 62.658 mA/cm2 with an energy capacity average of 1.2 Wh. These findings can contribute to the development of more efficient and practical ZCFBs, particularly for applications requiring low-cost and readily available electrolytes. [ABSTRACT FROM AUTHOR]

The goal of this research is to fabricate a novel type of highly active porous electrode material, based on stainless steel and dedicated to water electrolyzers. The main novelty of the presented work is the innovative application of the molten salts treatment, which allows the design of a highly developed porous structure, which characterizes significantly higher catalytic activity than untreated steel substrates. The equimolar mixture of NaCl and KCl with 3.5 mol% AlF3 was used as the molten salt. The surface modification procedure includes the deposition of an Al layer with application at the potential of −1.8 V and following dissolution at −0.9 V, to create a porous alloy surface. The cathodic polarization measurements of the prepared porous stainless steel electrodes were measured in a 10 mass% KOH solution. Moreover, the amount of hydrogen generated during constant voltage electrolysis with a hydrogen sensor in situ was also measured. The porous stainless steel alloy showed higher current density at lower potentials in the cathodic polarization compared to untreated stainless steel. The cathodic polarization measurements in alkaline solution showed that the porous 304 stainless steel alloy is an excellent cathode material. [ABSTRACT FROM AUTHOR]

The electrochemical performance of microsupercapacitors with graphene electrodes is reduced by the issue of graphene sheets aggregation, which limits electrolyte ions penetration into electrode. Increasing the space between graphene sheets in electrodes facilitates the electrolyte ions penetration, but sacrifices its electronic conductivity which also influences the charge storage ability. The challenging task is to improve the electrodes' electronic conductivity and ionic diffusion simultaneously, boosting the device's electrochemical performance. Herein, we experimentally realize the enhancement of both electronic conductivity and ionic diffusion from 2D graphene nanoribbons assisted graphene electrode with porous layer‐upon‐layer structure, which is tailored by graphene nanoribbons and self‐sacrificial templates ethyl cellulose. The designed electrode‐based device delivers a high areal capacitance of 71 mF cm−2 and areal energy density of 9.83 μWh cm−2, promising rate performance, outstanding cycling stability with 97% capacitance retention after 20 000 cycles, and good mechanical properties. The strategy paves the way for fabricating high‐performance graphene‐based MSCs. [ABSTRACT FROM AUTHOR]

The 3D structure (i.e., microstructure) of porous electrodes governs the performance of emerging electrochemical technologies such as fuel cells, electrolysis, and batteries. Sustaining electrochemical reactions and convective‐diffusive mass transport at high efficiency is complex and motivates the search for sophisticated microstructures with multimodal pore size distributions and pore size gradients. Here a new synthesis route for porous, metallic layers is presented that combines the characteristics of carbon structures (i.e., pore size, porosity) with the properties of metals (i.e., recyclability, conductivity). Building on the method of dynamic hydrogen bubble templating, a novel approach is engineered to manufacture thin, free‐standing layers using an electrochemical flow cell through the introduction of an intermediate layer and optimization of the synthesis parameters. Mechanically stable layers are created with thicknesses ranging from ≈50 to ≈200 µm comprising porous, dendritic structures, arranged to form a vascular network of larger pores with a gradient in radii from ≈5 µm at the bottom and up to ≈36 µm at the top of the material. Using X‐ray tomographic data, the morphology is analyzed, and the diffusive transport through the material as a function of liquid filling is simulated and compared to state‐of‐the‐art carbon fiber‐based electrodes, showing significantly higher mass transfer properties. [ABSTRACT FROM AUTHOR]

This work describes a novel methodology for measuring the potential distribution within the porous copper foam electrode of a zinc‐air/silver hybrid (ZASH) flow battery by using local potential probes. The suitability of dynamic hydrogen electrodes (DHEs) and a quasi‐reference electrode as probes is evaluated, with the latter chosen in view of stability. Liquid and solid‐phase potentials are recorded at varying applied current densities over multiple charge‐discharge cycles. Various zinc structures are found within specific overpotential ranges, with moss‐like structures appearing between 7.8 mV and 13.2 mV and the desired boulder structures in the range of 22 mV to 100 mV. Regardless of the current density, the highest liquid‐phase potentials are always measured in the outermost region of the porous foam near to the separator. In practice, this means that increasing the thickness of the copper foam over about 5 mm does not provide significant performance benefits. Conversely, solid‐phase potentials across the copper foam remain nearly uniform, resulting in negligible effects on local overpotential. The presented technique provides unique insights into the behavior of porous electrodes in electrochemical energy conversion technologies, facilitating the determination of the optimal properties for maximum efficiency, such as electrode thickness. [ABSTRACT FROM AUTHOR]

In the current work, we report the binder-free hydrothermal one-pot synthesis of a cobalt oxide hierarchical nanostructure (3O4-HNS) onto a highly conductive carbon fiber substrate (CFS/Co3O4-HNS) as an efficient electrode for energy storage devices. The fabricated electrode and synthesized 3O4-HNS were structurally characterized using SEM, EDAX, XRD, and FTIR techniques. Electrochemical characterization of the fabricated CFS/3O4-HNS electrode was also performed and showed that the electrical double-layer capacitance and pseudo-capacitance mechanisms both play roles in the charge storage of the CFS/3O4-HNS electrode. The obtained results exhibited the electrochemical-specific capacitance of 715 F=g at a current density of 3A=g for the CFE/Co3O4-HNS electrode. The fabricated electrode remains at 96% of its initial capacitance after 3000 cycles, showing the excellent cyclability of the fabricated CFS/3O4 -HNS electrode. These results paved the way for using the proposed facile, one-pot synthesized CFE/3O4 -HNS as an efficient electrode for use in electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]