Electrolysis Cell Research Articles

Membrane characterization for electrochemical LiOH production from Li2SO4 with simultaneous H2SO4 valorization

This work characterized different cation- and anion-exchange membranes to improve the efficiency for the electrochemical conversion of Li2SO4 into LiOH and simultaneously recover H2SO4 as a byproduct, an essential process for sustainable alternatives for lithium−ion battery recycling. The membrane’s ability to block H+ and OH− migration over the membrane to the feed stream of the electrolyzer was investigated. Simultaneously, the membrane resistance was measured to assess its impact on the cell voltage and overall energy consumption. The best CEM, Sx-2301-Wn, enabled to concentrate LiOH up to 1.7M with a current efficiency (CE) of 77.3%, while Fumasep FAB-130-PK, the best AEM, was able to concentrate H2SO4 up to 0.6M with a CE of 74.6%. The recirculation of LiOH into the middle compartment to maintain a constant pH was also investigated and showed to improve both Li+ (4.2%–8%) and SO42- (5.1%) migration, but pH higher than 3 led to an increased membrane resistance. The results of this work contributed to the selection of a suited membrane and ideal operational conditions for producing LiOH and H2SO4 through a three-compartment membrane electrolysis cell.

Hydrogen production from energetic poplar and waste sludge by electrohydrogenesis using membraneless microbial electrolysis cells

Membraneless microbial electrolysis cells (MECs) are potentially considered to produce biohydrogen (bioH2) in a green manner and simultaneously minimize agricultural and wastewater facility wastes. However, effective, sustainable, and cost-effective system configuration and improvement of operating variables, working at ambient conditions, are needed to make the MEC a sustainable process. Therefore, this study investigates the bioH2 production from poplar leaves and anaerobic sludge mixture by incorporating nanomaterials comprising Al2O3, MgO, and Fe2O3 metal oxides at various dosages. Moreover, the effects of applied cell voltage (0.5–1.5 V) and inoculum amount (20–40 mL) on bioH2 production and organic matter removal performance are evaluated. The maximum bioH2 production value is 417 mL at an applied voltage of 1.5 V with a chemical oxygen demand (COD) removal efficiency of 37.6 % under operating times of 5 min using 40 ml of inoculum. The bioH2 production of the MEC system is reduced with the decrease in inoculum amount. The highest bioH2 production of 828 mL is obtained at improved conditions in the presence of 1 g of Fe2O3 metal oxide. Overall, this study provides the potentiality of simultaneous waste minimization and bioH2 production under ambient conditions that highlight the waste-to-energy pathway for membraneless and green bioelectrochemical process.

Development of a magnetic rotator to enhance the hydrogen evolution reaction in a proton exchange membrane water electrolysis cell

In this study, a large-scale magnetic rotator for hydrogen production boosting was designed. The study addresses the challenge of selecting and designing mechanical components for a dynamic magnetic field (DMF) magnetic rotator in a green hydrogen electrolysis power plant, focusing on ensuring component reliability and efficiency under operational stresses. The aim is to determine suitable machine element materials (shaft, clutch, gears, etc.), allowable shear stress, and interconnection mechanisms through theoretical and practical evaluations. The method includes calculating the allowable shear stress for the spline based on carbon steel tensile strength, applying safety factors for material properties and load considerations, and determining shaft diameter using torque and shock load factors. Standard catalogs guide the selection of interconnections like clutches, gears, and bearings to ensure compatibility and performance. The results indicate that a 95 mm diameter S30C carbon steel shaft, with an allowable shear stress of 7.8 kg/mm2, meets the design requirements. The chosen spline dimensions and a 12.5 MW, 14-pole induction motor align with the system’s needs, ensuring reliable operation. The discussion highlights the critical balance between theoretical predictions and practical application in design optimization. It underscores the importance of incorporating safety factors and verifying component suitability to ensure robust performance of the magnetic rotator. This study provides a comprehensive approach to design optimization, integrating theoretical analysis with practical considerations to achieve optimal performance and reliability. The design output of this study can be used to boost the hydrogen evolution reaction in the SIEMENS Sylizer 300 electrolysis cell.

Definition of Critical Metrics for Performance Evaluation and Multiphase Flow Modeling in an Alkaline Electrolyzer Using CFD

Gas evolution and flow patterns inside an alkaline electrolyzer cell strongly affect efficiency, although such effects have not been explored in detail to date. The present study aims to critically analyze the dependence of cell performance on the multiphase flow phenomena, defining some key metrics for its assessment using CFD. Six performance indicators, involving gas accumulation, bubble coverage, and flow uniformity, are applied to a 3D CFD model of an alkaline cathodic cell, and possible optimizations of the cell geometry are evaluated. The results demonstrate the complexity of defining the optimal indicator, which strictly depends on the case study and on the analysis at hand. For the cell analyzed herein, the parameters linked to the electrode volume fraction were indicated as the most influential on the cell efficiency, allowing us to define the best geometry case during the optimization. Furthermore, a sensitivity analysis was conducted, which showed that higher mass flow rates are generally preferable as they are linked to higher bubble removal. Higher current densities, allowing enhanced gas production, are instead associated with slightly lower efficiencies and stronger nonuniformity of the electrolyte flow inside the cell.

Applicability of blue algae as an activator for microbial enhanced coal bed methane technologies

The blue algae can be used as a nitrogen agent for promoting biological coalbed methane, but its applicability and microbial mechanism in different microbial enhanced coalbed methane technologies kept unknown. This study evaluated the methanogenic efficiency of blue algae addition with a mass ratio of 10% under fermentative degradation and microbial electrolytic cell technologies, and studied the changes of coal microstructure, surface functional groups, organic components and microbiome. The results showed that the algae addition affected the micro-concave-convex structure, non-uniform distribution of micro-particles and micro-cracks of coals, and finally increased the methanogenic rate by 1.74–2.66 times. The algae addition mainly affected the coal organic components including hydroxyl structure, hydrocarbon structure, aliphatic oxygen-containing functional groups and aromatic structure, as well increased the humus acids and microbial metabolites in fermentation broth; among them, the increased metabolites showed great differences between different technologies. The algae addition mainly increased the genera belonging to phylum Bacillota (such as Bacillus and Clostridium) and methanogens (Methanosarcina and Methanoculleus). These Bacillota groups could degrade organic matter into acetate and methanol via pathways of glycolysis and benzoate degradation, which provided substrates for such methanogens. This study strengthened the effectiveness of blue algae in enhancing technologies for biological coalbed methane.

Shortening the Storage Duration of Food Waste and Adding Ammonia Nitrogen to Food Waste to Increase Hydrogen Yield in Microbial Electrolysis Cells

Shortening the Storage Duration of Food Waste and Adding Ammonia Nitrogen to Food Waste to Increase Hydrogen Yield in Microbial Electrolysis Cells

Enhanced biofilm-dependent biogas upgrading from waste activated sludge fermentation liquor in microbial electrolysis cells

This study demonstrated that metal-organic frameworks (MOFs)-derived Fe-NC cathode improved both methane yield and methane content in a microbial electrolysis cell-coupled anaerobic digestion (MEC-AD) system treating waste activated sludge (WAS) fermentation liquor. Results revealed that Fe-NC maintained a meso‑macroporous structure with a large specific surface area of 1381 m2/g and superior electrochemical properties. Its calculated specific capacitance and electron transfer resistance were 5.7 and 0.4 times of the carbon felt (CF) group. The bacterial and archaeal gene loads of Fe-NC biofilm after multiple acclimation cycles were 5.69E+10 and 1.86E+9 copies/cm2 and Proteiniphilum and Methanobacterium were the most enriched syntrophs from stage Ⅰ to stage Ⅱ acclimation. Corresponding maximum methane yield and content achieved were 0.31 m3 CH4/kg COD and 92.8 %, and its CO2-dependent methane production was improved by 107.6 %. Mechanistic investigations showed that Fe-NC biofilm improved enzyme-associated CO2 reduction pathway companying by promoting the intra- and extracellular electron transfer as well as ATP synthesis, therefore favoring methanogenic energetic metabolism. More importantly, an enhanced proton-coupled electron transfer (PCET) process was proposed within Fe-NC biofilm, providing a synergistic advantage over unbalanced conventional sole electron/proton transfer. This work provides an effective strategy to strengthen the waste-to-energy and biogas upgrading technology, potentially bringing economic benefits to wastewater treatment.

Simple solution immersion for realizing bifunctional catalyzation of water splitting in various electrolytes

Developing cost-effective, highly efficient and scalable bifunctional electrocatalysts for hydrogen production is crucial for advancing hydrogen energy systems. However, current methods are hindered by high energy consumption and material limitations. This work introduces a bifunctional electrocatalyst (NiFe-OH@Co2P@NF), by simply immersing a hierarchical cobalt phosphide electrode in mixed Ni/Fe solution, followed by forming layered nickel-iron hydroxides on the surface. Electrochemical tests reveal that this catalyst enhances active site exposure, accelerates electron transfer, and significantly lowers the overpotential for water electrolysis. It requires minimal overpotentials (79 mV at 10 mA cm−2, 175 mV at 150 mA cm−2) in 1 M KOH solution. In a dual-electrode electrolytic cell system, the catalyst enables efficient hydrogen production at a current density of 10 mA cm−2 with just 1.52 V, demonstrating robust stability during prolonged alkaline water splitting tests. Moreover, the bifunctional electrodes display good performance and durability in simulated alkaline seawater and 1 M KOH + seawater.

Effect of Ta–TiO2 Nanoparticles in Anion Exchange Membranes: Improved Hydroxide Ion Conductivity and Mechanical Strength for Alkaline Water Electrolysis Cells

AbstractTo improve the properties of quaternized QPAF‐4 copolymers as anion exchange membranes, compositing with hydrophilic Ta–TiO2 particles are investigated. Flexible QPAF‐4/Ta–TiO2 composite membranes are obtained using solution‐casting and die coating methods. Cross‐sectional scanning electron microscopy reveals that the die coating method produces a more homogenous and uniform distribution of Ta–TiO2 particles in the composite membranes than the solution‐casting method. The Ta‐TiO2 particles promotes the suppression of water absorbability and dimensional swelling of the composite membranes which is more pronounced in the die coated membranes. The Ta–TiO2 increase hydroxide ion conductivity to 116.9 mS cm−1 at 80 °C for the die‐coated membrane, surpassing that of the pristine QPAF‐4 membrane (92 mS cm−1). Ta–TiO2 with the composite membranes survive in 4 m KOH at 80 °C for 1000 h, maintaining 96–112 mS cm−1 (88–99% remaining) of initial conductivity. All composite membranes exhibit higher mechanical robustness (elongation of >200%), with the die‐coated composite membranes. The optimized die coated composite membrane is fabricated in an alkaline water electrolysis cell achieving 1.63 V at 1.0 A cm−2 (75.5% efficiency).

Microenvironment Manipulation Strategies for Acidic CO2 Electrolysis

AbstractThe electrochemical reduction of CO2 (CO2RR) has gained significant attention due to its potential to reduce carbon emissions and produce valuable fuels and chemicals. CO2RR is typically carried out in neutral or alkaline conditions, while challenges such as the carbon crossover and salt precipitate can hinder the practical application. Conducting CO2RR in acidic media presents a promising method to address these issues, although it faces the problem of low efficiency and poor catalysis stability. Regulating the interface/surface microenvironment near the catalysts is crucial to minimize the competitive hydrogen evolution reaction and enhance CO2RR activity and long‐term stability. This review outlines recent advancements in acidic CO2RR, emphasizing various microenvironment engineering strategies for optimizing the CO2RR kinetics including electrolyte composition manipulation, catalyst design, electrode modification and cell configuration optimization. Additionally, the review addresses challenges into developing practical and cost‐effective CO2RR systems.

A method for configuring hybrid electrolyzers based on joint wind and photovoltaic power generation modeling using copula functions

Considering the specific wind and photovoltaic power characteristics of a certain region, this study investigates the optimal ratio of Alkaline Electrolysis Cells (AEL) to Proton Exchange Membrane (PEM) electrolyzers in a hybrid electrolysis system for hydrogen production. A flexible model for configuring the hybrid electrolysis system is proposed, based on a copula function for joint wind and solar power modeling. This model generates wind and photovoltaic power generation scenarios using the copula function, incorporating a selection mechanism to ensure that the output scenarios are more representative of the actual data characteristics of wind and photovoltaic power output. Consequently, considering both the fluctuation and amplitude, the wind and photovoltaic power data are decomposed using the Ensemble empirical mode decomposition method. The decomposed components are then allocated to the two types of electrolyzers. Furthermore, the optimal configuration of the hybrid electrolysis system is determined by minimizing the costs associated with wasted power, electricity purchases, and other expenses. Finally, a case study of a 100 MW wind farm and a 50 MW photovoltaic power station in Northwest China is presented, concluding that the optimal configuration ratio of AEL to PEM electrolyzers is 2:1. In a Matlab/Simulink platform, the performance metrics of the hybrid electrolysis system were validated. It was found that the hydrogen production rate of the hybrid electrolyzer is comparable to that of the PEM electrolyzer, but with a lower required cost. Additionally, the hydrogen production rate and volume of the optimal configuration for the hybrid electrolyzer determined by the model proposed in this paper are higher than those obtained through the optimization algorithm's optimal configuration.

Full-spectrum solar water decomposition for hydrogen production via a concentrating photovoltaic-thermal power generator-solid oxide electrolysis cell system

This study introduces a novel solar-powered concentrating photovoltaic-thermal power generator-solid oxide electrolysis cell system designed to enhance hydrogen production efficiency by optimizing both electrical and thermal energy utilization. The system incorporates a thermal power generator to convert excess high-temperature thermal energy into electrical energy, addressing energy losses associated with high-temperature water electrolysis. Thermodynamic analysis shows that the integration of the thermal power generator improves energy and exergy efficiencies to 0.60 and 0.52, while lowering the optimal operating temperature to 1173 K. The system’s efficiency is sensitive to the proportion of electrical energy supplied by the thermal power generator, with an optimal range identified between 0.1 and 0.2. Higher temperatures improve hydrogen production and efficiency, but increased voltage negatively impacts thermodynamic efficiency. These findings demonstrate that the proposed system offers substantial improvements over conventional solar hydrogen production methods, making it a promising candidate for sustainable hydrogen production. Further research will focus on system integration, material costs, and scalability for commercial use.

Bifunctional system constructed by NiCu-F/DSA electrode self-coupling for efficient removal of ammonia nitrogen from landfill leachate

ABSTRACT Landfill leachates containing high concentrations of ammonia nitrogen, due to its strong toxicity, large discharge and great environmental hazard, is in urgent need of efficient cleaning treatment. In this work, Ni1Cu0.25-F/DSA catalytic electrode was prepared via electrodeposition by means of fluorination-induced surface reconstruction. The surface of electrode was determined to be a porous sponge-like structure by physical characterizations. The electrode exhibited a superior ammonia oxidation reaction (AOR) activity and stability by a series of electrochemical tests. On this basis, a Ni1Cu0.25-F/DSA || Ni1Cu0.25-F/DSA bifunctional system was developed for efficient removal of ammonia nitrogen in landfill leachate. The results of denitrification experiment indicated that the removal efficiency of NH4 +-N and TN were 99.89% and 68.9%, respectively, when the electrolytic cell potential was 1.7 V, pH was 13 and the initial ammonia concentration was 600 mg L−1. The NH4 +-N removal efficiency remained above 95% after the cyclic denitrification experiment lasting for 6 days, which validates the robust stability of the electrode.

High-Temperature Electrolysis with Superheated Steam Provided by Volumetric-Type Steam Generator

High-temperature steam is essential for operating solid oxide electrolysis cells (SOEC). This paper demonstrated a new type of high-temperature solar steam generator that uses ceramic foam as a porous absorber. Water is sprayed into the porous absorber as microdroplets by using a nozzle. Experiments show that the solar steam generator is capable of generating superheated steam beyond 800 oC. The peak thermal efficiency in the steady state can reach 60.92% under a mass flow rate of 2.359 kg/h corresponding to an outlet temperature of 877.3 oC. The superheated steam will be supplied to a SOEC system to generate hydrogen. Thus, a comprehensive model is developed in this paper to research the performance of the solar SOEC system under fluctuated solar irradiation

Efficient hydrogen production from food waste leachate using single-chamber microbial electrolysis cell

The aim of this study was to develop an efficient strategy for enhancing H2 production in the single-chamber microbial electrolysis cell (MEC) using food waste leachate as a substrate. Different pH (8.5, 9.5, 10.5, and 11.2), applied voltage (0.8, 1.2, 1.5, 1.8, 2.0, 2.2, 2.3, and 2.4 V) and negative pressure control (−50 kPa) were tested in the single-chamber MEC. Suitable pH adjustment could greatly promote electricity generation and H2 production rather than negative pressure control. Under pH of 11.5 and 2.4 V, the maximum current density reached 121.9 ± 10.9 A/m³ with an average H2 concentration of 91.9 ± 3.2% in a 1.2-L single-chamber MEC within 30 continuous cycles of operation (∼607 h), which was constructed with carbon brushes as the anode and stainless steel brushes as the cathode. The maximum H2 production rate reached 853.2 ± 70.3 L/m³•d with an H2 yield of 26.3 mmol•H2/g•COD. The COD removal of 68.3 ± 6.8% and three-dimensional excitation-emission matrix spectra of the effluent in the MEC within 21 ± 3h indicated efficient organics degradation in the leachate. Our results should provide a promising way to enhance the H2 production of MEC during leachate treatment.

Design of a bifunctional prepolymer for simultaneously facile preparation and highly efficient electrodialysis of anion exchange membranes

A facile fabrication process for separation membranes is crucial to decrease the production cost, while the photo-polymerization approach can be conducted at ambient conditions with short processing time and low energy consumption. Herein, this work designs a bifunctional prepolymer for simultaneously facile preparation and highly efficient electrodialysis of poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) anion exchange membranes. PPO is selected as the main skeleton of prepolymer because of the excellent mechanical and thermal stability. The dimethylaminoethyl methacrylate (DMAEMA) is grafted with brominated PPO by quaternization, where it contains cationic groups, i.e. quaternary ammonium, and photopolymerized groups, i.e. methacrylate C = C. This resulting prepolymer can be fast polymerized under UV irradiation via C = C from DMAEMA. This structure is synergistically regulated by the amounts of crosslinker DMAEMA and modifier N-bromosuccinimide. The optimized membrane exhibits an excellent ion exchange capacity of 2.19 mmol g−1, a water uptake of 38.17 %, and a tensile strength of 4.8 MPa. Meanwhile, its electrolyzer cell performance achieves a density of 580 mA cm−2 at an adjusted voltage of 2.1 V, and the desalination rate of seawater during electrodialysis reaches 98.34 %. This work provides a universal and facile fabrication route for high-performance AEMs.

Preformation of Insoluble Solid-Electrolyte Interphase for Highly Reversible Na-Ion Batteries.

A stable solid-electrolyte interphase (SEI) is crucial for cycling reversibility of Na-ion batteries by mitigating continuous side reactions. So far, the severe SEI dissolution leads to low Coulombic efficiency (CE) and short cycle life. Meanwhile, the quantified relationship between SEI components and their solubility remains unclear. In this work, we establish the direct correlation between SEI components and SEI solubility, and quantify that the solubility of organic-rich SEI is 3.26 times of inorganic-rich SEI. We further propose a feasible strategy to preform inorganic-rich insoluble SEI and demonstrate a practical hard carbon (HC)||NaMn0.33Fe0.33Ni0.33O2 full cell in a commercial electrolyte of 1 M NaPF6 in propylene carbonate (PC) with 80.0 % capacity retention for 900 cycles, and achieve a record-high average CE of 99.95 % for a practical Na-ion full cell. This study provides an effective strategy of preforming insoluble SEI to suppress its dissolution towards highly reversible Na-ion batteries.

Evaluation of a mixture of livestock wastewater and food waste as a substrate in a continuous-flow microbial electrolysis cell

While the efficiency of microbial electrolysis cell (MEC) systems has improved remarkably, their application in continuous reactors and wastewater treatment remains poorly understood. This study evaluated the performance of a continuous-flow MEC using livestock wastewater and food waste as substrates. The MEC system achieved a hydrogen production rate of 5.2 L/L/day using acetate as a substrate, and a rate of 2.9–4.6 L/L/day when real wastewater mixtures were used. In terms of chemical oxygen demand (COD) removal, the system demonstrated high efficiency, with values ranging from 42.3 % to 62.2 % depending on the wastewater composition. Volatile fatty acid (VFA) removal reached up to 72.8 %. The current density averaged 9.9 A/m2 with acetate and decreased to 7.0 and 6.1 A/m2 in phases using wastewater, reflecting the adaptation of the microbial community to the more complex substrates. The microbial community was dominated by Firmicutes, Bacteroidetes, Proteobacteria, and Synergistetes, with Proteobacteria showing a particularly high abundance near the anion exchange membrane (AEM) on the anode. The MEC process demonstrates substantial promise as a sustainable technology for both biohydrogen production and wastewater treatment. With further optimization and scaling, MECs could play a crucial role in the circular economy by converting waste into clean energy while simultaneously treating wastewater, offering a pathway toward more sustainable industrial and environmental practices.

Electrophoretic Deposition and Physicochemical Properties of Ni- and Fe-Doped Cu–Mn Spinel Coatings Enhanced with Ce0.9Y0.1O2 Nanoparticles on Fe16Cr Ferritic Stainless Steel Interconnects for SOEC Applications

Cu- and Mn-based spinel coatings are currently among the most promising materials for solid oxide electrolyzer cell (SOEC) interconnects due to their high electrical conductivity and ability to eliminate environmentally hazardous cobalt, which is included in the most widely used coatings. However, their properties are affected by the presence of the Cr2O3 scale and high-temperature corrosion, and to mitigate this they could be doped with elements such as Ni and Fe. In addition, the electrical properties of such steel/shell layered systems can be further improved using rare-earth element nanoparticles (Ce0.9Y0.1O2). In this work, low-chromium steel was modified using nanoparticles and/or spinel coatings and oxidized in air atmosphere at 800 °C for 2000 hours. The oxidized systems were then characterized using diffraction studies, microstructural observations and electrical measurements. Electrical studies in particular showed a significant reduction in area-specific resistance for steels modified using a combination of both nanoparticles and spinel coatings.

Regulating the electronic structure of nickel phosphides via interface engineering and molybdenum doping boosts benzyl alcohol oxidation coupled with hydrogen production

Coupling the electrocatalytic benzyl alcohol oxidation reaction (BAOR) with hydrogen evolution reaction (HER) presents a favorable energy conversion method. However, the development of highly efficient bifunctional electrocatalysts poses significant challenges. In this study, a Mo doped biphasic Ni2P-Ni12P5 heterostructure (Mo-Ni2P/Ni12P5@NF) has been developed to serve as the efficient bifunctional electrocatalyst. The Mo-Ni2P/Ni12P5@NF resulted in exceptional activities for both the BAOR and HER. The electrolyzer cell using Mo-Ni2P/Ni12P5@NF as anode and cathode operates at an impressively low cell voltage of merely 1.38 V to achieve the current density of 10 mA cm−2 in a benzyl alcohol-containing aqueous solution. Experimental results and density functional theory (DFT) calculations indicate that the introduction of Mo can significantly modulate the electronic structure of Ni-based phosphide catalysts and adjust for the d-band center of the active Ni sites. This modulation significantly optimizes the adsorption capabilities for both benzyl alkoxide (Ph-CH2O-) and the H* intermediates on Mo-Ni2P/Ni12P5@NF, thereby increasing electrocatalytic activity toward BAOR and HER respectively. Our work offers a valuable insight into designing bifunctional electrocatalysts and highlights the potential of Mo doping systems to produce hydrogen and value-added products efficiently.