Porous Electrodes Research Articles

Effect of Electro-Sprayed Porous Electrodes on the Performance and Stability of Water Electrolysis.

The efficiency of proton exchange membrane water electrolysis (PEMWE) is a critical issue in realizing the production of green hydrogen. The coexistence of three phases in the catalyst layer of PEMWE causes mass transport limitation at the interfaces between them. In particular, the vigorous production of gaseous hydrogen and oxygen derived from liquid water is generated in the form of bubbles that seriously deactivate the membrane electrode assembly (MEA). In this study, we investigated the effect of porous structure in the electrode on the efficiency of hydrogen production at a high current density, which is highly related to the mass transport limitation. A widely used commercial catalyst (IrO2) was directly coated on the membrane by the electro-spray method. Porous electrodes on the membrane were formed by the charged catalyst particles that repulsed each other due to their electrostatic forces. Our membrane electrode assembly (MEA) exhibited outstanding electrolysis performances such as 5.3 A cm-2 and 3.2 A cm-2 at 2.0 and 1.8 V, respectively, which are the highest values compared with the results published in the current studies. In addition to porosity, it was confirmed that optimum binder contents positively affect the hydrophobicity and contact resistance of MEA. Through a simple porosity-controlled technique, the performance of PEMWE, in which three phases coexist, can be improved by more than 60 %. Accordingly, we expect that our systematic study on the role of porosity in the electrodes opens a new era to efficiently produce green hydrogen.

Bioderived Hierarchically Porous Electrode with High Polarity for Lithium–Sulfur Batterties

Bioderived Hierarchically Porous Electrode with High Polarity for Lithium–Sulfur Batterties

Regional Characteristics in Ultradeep MXene Slit Nanopores: Insights from Molecular Dynamics Simulation.

The presence of slit nanopores in MXene materials inevitably influences the electrochemical performance of supercapacitor electrodes. However, most studies focus on experimental approaches, lacking microscopic-scale analysis. Here, we performed molecular dynamics (MD) simulations to thoroughly analyze and predict the ion transport pathways and energy storage mechanisms of MXene/ionic liquid (IL) supercapacitors with ultradeep slit nanopores. The simulation results indicate that during the charging process, counterions migrate from the bulk region into the electrode pores, forming a counterion layer near the electrode surface, while some co-ions gradually exit the pores. When charging is completed, a distinct ion layering structure emerges. As the interlayer spacing varies, the ion distribution in the electrode pores exhibits regional characteristics: in the ordered region near the bulk region, a stable electrical double-layer (EDL) structure is maintained, whereas in the deeper mixed region, persistent co-ion presence and significant disorder are observed. Dominated by the mixed region, the total energy variation of the electrode decreases as the interlayer spacing decreases, with energy changes of 8526.52, 7443.52, and 6640.99 kJ·mol-1 at interlayer spacings of 1.2, 1.0, and 0.8 nm, respectively, representing reductions of approximately 12.7 and 22.1% compared to 1.2 nm. In the mixed region, after compensating for the interaction between counterions, the contribution of the interaction between counterions and electrode increases with decreasing interlayer spacing, reaching 123, 153, and 176% at 1.2, 1.0, and 0.8 nm, respectively. An increasing amount of energy is offset by interactions related to the co-ions, ultimately leading to the observed energy differences. These findings offer new insights into the impact of nanopore structure on supercapacitor performance and provide theoretical guidance for optimizing electrode design.

Modeling Losses in a Three Electrode System Towards Fast Charge Control

Abstract In this work we demonstrate the applicability of a versatile separator-reference mounted electrode in a three-electrode setup to accurately capture the primary current pathway in the battery cell during operation, calibrate a porous electrode model to the individual anode and cathode potential signals, and assign the various resistances to electrochemical phenomena in the battery cell. This calibrated electrochemical model is validated using continuous rate discharges associated with highway driving scenarios in an electric vehicle, and in turn utilized to predict the local anode potential and proximity to lithium plating onset. Finally, we demonstrate the strategy associated with utilization of the model to estimate constant anode potential charging during fast charge scenarios at various rates and starting conditions as a future look to fast charge calibration development and controls.

Investigation of Structural, Optical, Electrical, and Biological Properties of a Porous Platinum Electrode for Neurostimulation Devices

Investigation of Structural, Optical, Electrical, and Biological Properties of a Porous Platinum Electrode for Neurostimulation Devices

Advanced aqueous phenazine redox flow battery enhanced by selective interfacial water behavior on Co/NC modified electrode.

Advanced aqueous phenazine redox flow battery enhanced by selective interfacial water behavior on Co/NC modified electrode.

Energy-efficient and eco-friendly fabrication of a quaternary co-doped porous carbon electrode material for zinc-ion hybrid capacitors via laser technology

Energy-efficient and eco-friendly fabrication of a quaternary co-doped porous carbon electrode material for zinc-ion hybrid capacitors via laser technology

Conductive Polymer Coatings Control Reaction Selectivity in All-Iron Redox Flow Batteries.

Aqueous all-iron redox flow batteries are an attractive and economic technology for grid-scale energy storage owing to their use of abundant and environmentally benign iron as the redox active material and water as solvent. However, the battery operation is challenged by the plating/stripping reactions of iron and the competing hydrogen evolution reaction at the negative electrode, which hinder performance and durability. Here, the reaction selectivity of the negative electrode is tailored by introducing conductive polymer coatings onto porous carbonaceous electrodes. Two conductive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(pyrrole) (PPy) are conformally coated with the dopant poly(4-styrenesulfonate) (PSS) and the resulting electrochemistry is studied on model electroanalytical platforms and redox flow batteries. Both polymers decrease the hydrogen evolution current on rotating disc electrodes, with PPy/PSS strongly inhibiting the reaction at high overpotentials. In full all-iron redox flow cells, PPy/PSS coating extends cyclability and significantly reduces hydrogen evolution, while PEDOT/PSS coating improves the round-trip efficiency, possibly acting as a redox shuttle for the iron stripping reaction. These findings motivate broader investigation and implementation of conductive polymers to engineer reaction selectivity for flow batteries and other electrochemical technologies.

Two-stage 3D porous irregular nanorod electrode for nitrate electrochemical reduction to ammonia: High selectivity and stability

Two-stage 3D porous irregular nanorod electrode for nitrate electrochemical reduction to ammonia: High selectivity and stability

Manganese doped Ni-MOF derived porous carbon-based bifunctional oxygen electrode catalyst for metal air batteries

Manganese doped Ni-MOF derived porous carbon-based bifunctional oxygen electrode catalyst for metal air batteries

Scale-Up Strategies for Redox-Mediated Electrodialysis for Desalination: The Role of Electrode and Channel Stacks.

Redox-mediated electrodialysis (redox-ED) enhances the economic and energy feasibility of conventional electrodialysis by substituting water splitting and costly metal-basedelectrodes with reversible redox reactions and porous carbon electrodes. Despite growing interest, the development of scale-up strategies for redox-ED remains limited, delaying its industrial implementation. This study proposes a scale-up strategy by examining the impact of stacking electrodes and channels on the desalination performance of the system, aiming to enable economically viable desalination. The results show that electrode and channel stacking (up to three stacks) significantly enhances desalination performance, resulting in a 6.8-fold increase in the salt removal rate, and a 30% improvement in productivity. These enhancements can be attributed to synergistic effects of electrode and channel stacking, which improve the redox reaction rate by increasing the surface area and enhancing the system capacity by increasing the volumetric flow rate. Technoeconomic analysis underscores the economic viability of the scale-up strategy proposed in this study, showing18% and 32% reductions in capital and operating costs, respectively,compared with multiple unit cell systems. Overall, incorporating multiple stacks of electrodes and channels offers an effective strategy for scaling up redox-ED systems with high economic viability, thereby providing a pathway for their industrial utilization.

Construction of high-performance sodium ion hybrid capacitors based on MXene surface modulation and electrolyte matching.

Sodium-ion hybrid capacitors have garnered significant attention due to their high power and energy densities, as well as the abundance of sodium reserves. However, the mismatch between anode and cathode dynamics is the biggest barrier to improving their performance. To address this issue, we propose a strategy for the preparation of porous MXene by hydrogen peroxide (H2O2)-controlled etching to solve the capacity degradation and ion diffusion limitation, which are caused by van der Waals forces between MXene nanosheets. This approach facilitates the realization of three-dimensional ion channels with both vertical and horizontal pathways, significantly enhancing the availability of active sites and improving the ion diffusion rate. By adjusting the amount of oxidant, porous MXene (P-MXene-2) with an optimal pore size range was obtained. The assembled half-cell has a capacity of 180 mAh g-1 at a rate of 0.05Ag-1. Furthermore, by combining a porous carbon cathode with porous MXene and electrolyte screening, a SIHC with a high energy density of 110.6 Wh kg-1 at 1000Wkg-1 and 71.1 Wh kg-1 at 20 kW kg-1 was successfully constructed. This study provides useful insights into the design and preparation of porous MXene electrodes and their energy storage applications.

Ultrasensitive detection of 2,4-dichlorophenoxyacetic acid by inhibiting alkaline phosphatase immobilized onto a highly porous gold nanocoral electrode.

Herein, we describe the design and implementation of an ultrasensitive enzyme inhibition-based biosensor for 2,4-dichlorophenoxyacetic acid (2,4-D) detection. The biosensor utilizes alkaline phosphatase (AlP), immobilized on a photo-crosslinked polymer matrix of poly(vinyl alcohol) functionalized with N-methyl-4(4'-formylstyryl)pyridinium (PVA-SbQ), supported by electrodes coated with highly porous gold nanocorals (hPGNCs). After preliminary electrochemical and morphological characterization, the PVA-SbQ/AlP/hPGNC electrode was tested for inhibition studies employing ascorbate 2-phosphate (A2P) as the initial substrate. The biosensor preparation/sensing time from electrode preparation to final results is approximately 45 minutes, which enables the possibility to easily scale up the electrode production process on a daily basis with a reliable analytical result in only 5 minutes of amperometric measurement. Following the initial kinetic studies and evaluation of analytical performance, the PVA-SbQ/AlP/hPGNC platform demonstrated a linear detection range from 0.002 to 22 ppt, with a sensitivity of 0.121 ± 0.006 ppt-1 (RSD = 4.9%, R2 = 0.996, and N = 6) and a limit of detection (LoD) of 0.7 ppq. This sensitivity is 7-8 orders of magnitude below the regulatory thresholds in Europe and the USA. Furthermore, the biosensor was validated using 19 homogenized wheat leaf sample extracts, prepared in line with European Food Safety Authority (EFSA) guidelines, achieving average recoveries exceeding 96% and RSD values under 9.8%. The biosensor also exhibited robust operational and storage stability, maintaining 84% (30 hours of continuous operation) and 94% (120 days) of its initial response, respectively. These results highlight the potential of the PVA-SbQ/AlP/hPGNC biosensor for on-site 2,4-D monitoring in agricultural crops and its feasibility for integration with artificial intelligence for advanced diagnostics.

Laser Beam Machining of Janus Porous Electrodes for Long‐term Electrophysiological Sensing

AbstractFlexible epidermal electrodes have attracted significant attention for their ability to conform to irregular surfaces, with comfortable and non‐invasive sensing performance. However, challenges remain regarding conformality, breathability, and contact interfacial impedance. This work introduces an ultrathin, trim‐paste, and inexpensive Janus porous electrode by laser beam machining. The micron‐pore‐sized electrodes exhibit exceptional breathability with sweat permeability in less than 1s. In addition, the electrodes exhibit ultrathin profiles, with a thickness of only 23 µm, and an ultralight weight of 0.12 g. Porous electrodes can be trimmed and pasted onto the human skin or objects in a variety of shapes and sizes as required. In particular, the Janus porous kirigami electrodes demonstrate stretchability, with an elongation at break up to 350%. The Janus porous electrodes can be used to detect human electromyography and electrocardiogram signals, showing superior performance compared to commercial gel electrodes, especially in a sweat‐rich environment.

Porous Carbon Materials: from Traditional Synthesis, Machine Learning‐Assisted Design, to Their Applications in Advanced Energy Storage and Conversion

AbstractPorous carbon materials (PCMs) have long played key roles in energy storage and conversion fields, known for their abundant raw materials, tunable pore structures, large surface area, and excellent conductivity. Despite significant progress, there remains a substantial gap between the precise design of PCMs and the full utilization of their unique properties for developing high‐performance electrode materials. Herein, this review systematically and comprehensively introduces PCMs from traditional synthesis, machine learning‐assisted design principles to their energy storage and conversion applications. Specifically, the preparation methods for microporous, mesoporous, macroporous, and hierarchically porous carbon materials are thoroughly summarized, with an emphasis on structural control rules and formation mechanisms. It also highlights the unique advantages of PCMs in alkali metal‐ion batteries, metal–sulfur batteries, supercapacitors, and electrocatalysis. Insights from in situ and operando characterizations provide a deep understanding of the correlation between structure and performance. Finally, current challenges and future directions are discussed, emphasizing the need for further advancements to meet evolving energy storage and conversion demands. This review offers valuable guidance for the rational design of high‐performance porous carbon electrode materials, and points out key research directions for future development.

Determination of the Solid State Diffusion Coefficient of Li-ion Battery Single-Phase Materials Using Thin Model Electrodes

Abstract For lithium-ion batteries, the development of physico-chemical battery cell models has gained momentum. A significant challenge is the determination of the solid-state diffusion coefficient D s in the active materials particles, as typically studied porous electrodes are not limited to pure solid-state effects. This work aims to develop an optimized methodology for model parameterization, improving upon the conventional Galvanostatic Intermittent Titration Technique (GITT) on porous electrode systems. Various methods are compared using a single particle model, identifying the GITT-Kang method and Impedance-Fitting as promising advancements. These methods are applied to thin electrodes consisting of a single-layer microstructure of spherical NMC622 particles (model electrodes), demonstrating an almost complete agreement with theoretical principles. For experimental application, the GITT-Kang method is preferred and adapted for the underlying microstructure. Model electrodes with minimal lithium salt concentration in the electrolyte are found to improve the determination of D s and used to investigate the dependency of solid-state diffusion coefficient on lithium stoichiometry and temperature. A comparison with porous electrodes reveals consistent deviations with increasing layer thickness, highlighting the need for methodological advancements for these systems. The presented approach using model electrodes will serve as a reference for future work.

Porous Agglomerate Model for Battery Electrodes and Application to the Lithium-Silicon System

Abstract A treatment is developed for porous electrodes consisting of porous agglomerates, with the porous agglomerates consisting of solid (primary) particles of active material. With the use of the multi-site, multi-reaction formulation, gradients of the chemical potential of Li are the driving force for solid-state diffusion, and the different Li species and reaction sites are employed in the electrochemical kinetics equations. The method is applied to the Li-Si electrode system, including the impact of protective coatings over the active materials. The numerical analysis treats the full pseudo-three-dimensional problem, and histories and profiles of the potentials and concentrations are elucidated. The overall procedure can facilitate rational battery design and construction, including attendant trade-offs for selection of key physical dimensions and material alternatives that govern the cell performance.

Synergistic Enhancement of Capacitive Performance in Porous Carbon by Phenolic Resin and Boric Acid.

The study of pore structure regulation methods has always been a central focus in enhancing the capacitance performance of porous carbon electrodes in lithium-ion capacitors (LICs). This study proposes a novel approach for the synergistic regulation of the pore structure in porous carbon using phenol-formaldehyde (PF) resin and boric acid (BA). PF and BA are initially dissolved and adsorbed onto porous carbon, followed by hydrothermal treatment and subsequent heat treatment in a N2 atmosphere to obtain the porous carbon materials. The results reveal that adding BA alone has almost no influence on the pore structure, whereas adding PF alone significantly increases the micropores. Furthermore, the simultaneous addition of PF and BA demonstrates a clear synergistic effect. The CO2 and H2O released during the PF pyrolysis contribute to the development of ultramicropores. At the same time, BA facilitates the N2 activation reaction of carbon, enlarging the small mesopores and aiding their transformation into bottlenecked structures. The resulting porous carbon demonstrates an impressive capacitance of 144 F·g-1 at 1 A·g-1 and a capacity retention of 19.44% at 20 A·g-1. This mechanism of B-catalyzed N2-enhanced mesopore formation provides a new avenue for preparing porous carbon materials. This type of porous carbon exhibits promising potential for applications in Li-S battery cathode materials and as catalyst supports.

Advancing Porous Electrode Design for PEM Fuel Cells: From Physics to Artificial Intelligence

Advancing Porous Electrode Design for PEM Fuel Cells: From Physics to Artificial Intelligence

3D Printed Low-Tortuosity and Ultra-Thick Hierarchical Porous Electrodes for High-Performance Wearable Quasi-Solid-State Zn-VOH Batteries.

Rechargeable aqueous Zn-ion batteries have received considerable attention in energy storage systems owing to their merits of high safety, low cost, and excellent rate performance. However, the unsatisfactory areal energy density and poor cycling performance hinder their practical applications. Herein, the V5O12·6H2O (VOH) nanosheet arrays and Zn nanoflake arrays growing on the 3D-printed reduced graphene oxide/carbon nanotubes (3DP-rGO/CNTs) microlattices employing the electrodeposition technique, and furtherserve as the cathode and anode for 3D-printed aqueous Zn-VOH battery, respectively. Benefiting from 3D-printed low-tortuosity and ultra-thick hierarchical porous electrodes, the battery-type VOH-based cathode enables fast Zn2+ reaction kinetics and electrodeposited Zn-based anode delivers highly reversible Zn stripping/plating. The button-type 3D-printed aqueous Zn-VOH battery exhibits excellent energy/power densities (364.5Wh kg-1 at 700W kg-1) and remarkable cycling performance over 6500 cycles. Impressively, a customizable 3D-printed quasi-solid-state Zn-VOH battery device is fabricated, which presents ultrahigh areal capacity (≈17.06 mAh cm-2 at 0.2mA cm-2), long-term durability (≈85.6% capacity retention after 10000 cycles), and excellent wearable characters. This work provides a novel strategy to gain high-performance Zn-ion batteries based on 3D-printed electrodes, which may pave a new way for the applications of various high-performance, low-cost, and portable integrated energy storage systems.