Proton Exchange Research Articles

Sulfonamide-Sulfonimide Copolymers as Novel, Fluorine-Lean Type of Proton Exchange Membranes for Fuel Cell Application.

In this work, a novel type of fluorine-lean proton exchange membranes is presented, using sulfonamide-sulfonimide functional groups for ion conduction. These groups are constructed on a polystyrene backbone for simple and cost-efficient usage as well as rapid scalability. The polymer is further tailored by adjusting the sulfonamide functionality with various end-groups, namely pentafluorophenyl, 4-fluorophenyl, butyl and octyl groups. These groups affect the pKa, leading to pKa values of 5.7 for the pentafluorophenyl substitution and pKa 10.5 for the alkyl chain. The glass transition temperature of the sulfonamide homopolymers can be reduced from Tg = 151°C (Pentafluorophenyl) to 49°C (Octyl), making the ionomer more flexible at room temperature. The combination of the non-swelling sulfonamide further mitigates the high water uptake of the sulfonimide while maintaining the nominal ion exchange capacity. This combination leads to extremely high proton conductivities with up to σ = 283 mS cm-1 at room temperature, which is clearly outperforming Nafion and approaches values for acid doped systems. This approach can pave the way to a novel type of ion conducting class in proton exchange membrane fuel cells.

Numerical simulation of comprehensive performance of proton exchange membrane electrolytic cell with microporous layer

Proton exchange membrane electrolytic cell (PEMEC) is considered a promising way to produce green hydrogen due to its advantages of high current density, rapid start and stop, and high purity of hydrogen production. However, the existing macroscopic modeling of the PEMEC lacks the consideration of MPLs and the comprehensive study of heat and mass transport. In this paper, a one-dimensional two-phase non-isothermal PEMEC model with microporous layers is established, which accounts for a complete description of mass, charge, and heat transport. The polarization curves of numerical simulation are in good agreement with the experimental data. Then, the model is used to parametric analyze the effects of operating conditions and component parameters on heat and mass transfer, voltage loss, and efficiency for the PEMEC. The results show that operating pressure has a significant influence on the electrolytic performance. Voltage loss reduced of 30.75 mV and maximum temperature of 1.74 K occur when operating pressure increases from 1atm to 3atm, respectively. The characteristics of PTL and MPL mainly affect mass transport, and when PTL thickness and MPL thickness reduce by 100 μm and 20 μm respectively, the oxygen molar fraction reduces by 4.96% and 0.94%, respectively. The application of higher porosity, permeability, and thinner PTL with a thinner microporous layer (MPL) can effectually improve the operation efficiency of PEMEC. The model results presented in this study provide a theoretical basis for the optimization and design of the PEMEC.

Oxygen excess ratio feedforward control based on ESO for PEMFC in DC off-grid hydrogen production systems

Oxygen excess ratio (OER), which is influenced by the air flow input to the cathode, is one of the important factors affecting the performance of fuel cell system. Insufficient oxygen supply will result in a sharp drop in output voltage, while an excessive supply will bring about a large parasitic power load on the air compressor, reducing the net output power of the system and operating efficiency. Both insufficient and excess oxygen supply can adversely affect the operating life of the proton exchange membrane fuel cell (PEMFC). Due to the serious nonlinear, hysteresis, uncertainty and interference in the process of OER control, this paper proposes an OER feedforward control based on extended state observer (ESO) for a PEMFC auxiliary system with the ESO to predict the total disturbance to improve the dynamic response of the system with large time delay utilizing terminal sliding mode control (TSMC). The control strategy is divided into two stages. The first stage constructs an ESO to realize real-time observation of the state variables required for the internal operation of the auxiliary machine system and the PEMFC, and yields the air compressor voltage control signal through terminal sliding mode control. In the second stage, combined with V/f control for the compressor, the transmitted air flow is adjusted, ultimately achieving the goal of changing the OER of the PEMFC and improving operating efficiency. The simulation results show that the proposed control strategy has good anti-interference capabilities, a faster response, and less overshoot. The gas flow transmission in the gas supply system is more robust, the PEMFC operation is safer, and its lifespan is extended.

Pore-Scale Simulation of Tortuosity in the Catalyst Layer of Proton Exchange Membrane Fuel Cells

Pore-Scale Simulation of Tortuosity in the Catalyst Layer of Proton Exchange Membrane Fuel Cells

Enhancing voltage stability through wavelet-fuzzy control of hydrogen flow in OC-PEM fuel cell

Open cathode proton exchange membrane fuel cells (OC-PEM fuel cells) serve as electricity generators, utilizing hydrogen as an input source. While effective for fixed loads like residential applications, challenges arise in dealing with output voltage fluctuations caused by rapid load changes. These fluctuations not only impact fuel cell performance but also introduce instability in the supplied power. To solve this issue, the study proposes an innovative hydrogen flow control system employing a feedforward wavelet- fuzzy method. The primary goal of this control system is to enhance fuzzy control performance using wavelets, mitigating signal fluctuations and achieving optimal stability in fuel cell output voltage under constant load conditions. Wavelet functions act as filters on the fuzzy control input, minimizing fluctuations and refining the entire process. Additionally, a feedforward system is incorporated to maintain hydrogen flow at the set point value. The proposed control system is implemented on a validated model using experimental data. Performance analysis reveals that the proposed method effectively stabilizes voltage by accelerating the recovery time from disturbances.

Energy efficiency and electrochemical characteristic assessment of PEMFC-supercapacitor hybridization via railway profile

Electric trains equipped with efficient electric motors and powered by high-capacity hydrogen fuel cells are a choice of the global transportation industry to accelerate the global transition to a low-carbon transportation system. The operation of distinct vehicle types in varying geographical regions is characterized by unique features. Concurrently, the continually fluctuating demand for electricity necessitates the utilization of fuel cells in conjunction with energy storage devices. Thus, this study centers on examining the role of the PEMFC-supercapacitor direct hybridization system within the authentic driving profile of the subway in the Bangkok metropolitan region. The supercapacitor within the hybridization system serves as an energy management device, enhancing the durability of fuel cells when subjected to diverse load demands associated with train propulsion. In order to validate this hypothesis, an MRT (Mass Rapid Transit) protocol was formulated to emulate and serve as the load demand for the investigation, and then the PEMFC-supercapacitor direct hybridization system was operated using the created profile. Subsequently, the hybridization system undergoes electrochemical characterizations and fuel cell performance tests for diagnostic purposes. Empirical findings validated that the supercapacitor operates as a filter, generating a stable voltage response to varying load requirements, and possesses the capability to assimilate energy originating from regenerative braking. The integration of supercapacitors in stabilizing the operational parameters of proton exchange membrane fuel cells (PEMFCs) has markedly prolonged their operational lifespan. This assertion is substantiated by voltage signal analysis, which demonstrated a negligible increase in surface resistance of merely 0.23%, as depicted by Nyquist plots. Furthermore, cyclic voltammetry revealed that the system attained a peak electrochemical surface area (ECSA) of 0.0089 (106 cm2/mg of Pt). The information presented in this article constitutes data that has been minimally explored in existing research. Specifically, the study concentrates on the practical driving pattern of electric trains. Consequently, experimental results were deemed advantageous for the advancement of heavy-duty electric vehicles.

Exfoliated 2D Nanosheet-Based Conjugated Polymer Composites with P-N Heterojunction Interfaces for Highly Efficient Electrocatalytic Hydrogen Evolution.

They have achieved a significant breakthrough in the preparation and development of two-dimensional nanocomposites with P-N heterojunction interfaces as efficient cathode catalysts for electrochemical hydrogen evolution reaction (HER) and iodide oxidation reaction (IOR). P-type acid-doped polyaniline (PANI) and N-type exfoliated molybdenum disulfide (MoS2) nanosheets can form structurally stable composites due to formation of P-N heterojunction structures at their interfaces. These P-N heterojunctions facilitate charge transfer from PANI to MoS2 structures and thus significantly enhance the catalytic efficiency of MoS2 in the HER and IOR. Herein, by combining efficient sodium-functionalized chitosan-assisted MoS2 exfoliation, electropolymerization of PANI on nickel foam (NF) substrate, and electrochemical activation, controllable and scalable Na-Chitosan/MoS2/PANI/NF electrodes are successfully constructed as non-noble metal-based electrochemical catalysts. Compared to a commercial platinum/carbon (Pt/C) catalyst, the Na-Chitosan/MoS2/PANI/NF electrode exhibits significantly lower resistance and overpotential, a similar Tafel slope, and excellent catalytic stability at high current densities, demonstrating excellent catalytic performance in the HER under acidic conditions. More importantly, results obtained from proton exchange membrane fuel cell devices confirm the Na-Chitosan/MoS2/PANI/NF electrode exhibits a low turn-on voltage, high current density, and stable operation at 2 V. Thus, this system holds potential as a replacement for Pt/C with feasibility for applications in energy-related fields.

Effect of Hierarchical Pores on the Water Transport in Microporous Layer of Proton Exchange Membrane Fuel Cells

Effect of Hierarchical Pores on the Water Transport in Microporous Layer of Proton Exchange Membrane Fuel Cells

Thermo-Economic Comparison between Three Different Electrolysis Technologies Powered by a Conventional Organic Rankine Cycle for the Green Hydrogen Production Onboard Liquefied Natural Gas Carriers

The high demand for natural gas (NG) worldwide has led to an increase in the size of the LNG carrier fleet. However, the heat losses from this type of ship’s engines are not properly managed, nor is the excess boil-off gas (BOG) effectively utilised when generation exceeds the ship’s power demand, resulting in significant energy losses dissipated into the environment. This article suggests storing the lost energy into green H2 for subsequent use. This work compares three different electrolysis technologies: solid oxide (SOEC), proton exchange membrane (PEME), and alkaline (AE). The energy required by the electrolysis processes is supplied by both the LNG’s excess BOG and engine waste heat through an organic Rankine cycle (ORC). The results show that the SOEC consumes (743.53 kW) less energy while producing more gH2 (21.94 kg/h) compared to PEME (796.25 kW, 13.96 kg/h) and AE (797.69 kW, 10.74 kg/h). In addition, both the overall system and SOEC stack efficiencies are greater than those of PEME and AE, respectively. Although the investment cost required for AE (with and without H2 compression consideration) is cheaper than SOEC and PEME in both scenarios, the cost of the H2 produced by the SOEC is cheaper by more than 2 USD/kgH2 compared to both other technologies.

Patterned design of porous carbon materials as microporous layers to enhance fuel cell performance over a wide humidity range

Microporous layers play a crucial role as one of the main components of the membrane electrode assembly (MEA) in facilitating effective water management for proton exchange membrane fuel cells (PEMFCs), which is vital for maintaining optimal performance in a wide humidity range. Herein, Zn-based zeolitic imidazolate framework-8 (ZIF-8)-derived material (ZDM) as a porous carbon material is first developed to construct the microporous layer (MPL). With higher gas permeability, imporved water management, and increased electrical conductivity, the MPL equipped with a ZDM layer, denoted as MPL-Z, exhibits superior performance, surpassing commercial MPLs throughout the range of 30–100% relative humidity (RH). The peak power density of an H2/air PEMFC at 70% RH utilizing a MPL-Z is 3.3 times that of commercial MPL. Furthermore, a unique patterned dual MPL is designed to boost the performance, ultimately achieving a peak power density of 1.50 W cm−2 (H2/air) with a low total Pt loading of 0.3 mgPt cm−2 at 100 % RH. Even at only 30% RH, the peak power density can reach 0.72 W cm−2 (H2/air). The results demonstrate that the material and structural design of the MPL allows for the efficient operation of low Pt loading PEMFCs over a wide humidity range.

Deep learning assisted anode porous transport layer inverse design for proton exchange membrane water electrolysis

Proton exchange membrane water electrolysis cell (PEMEC) offers a clean and promising way for hydrogen production. The spatial internal current density and temperature distribution uniformity significantly determines its reliability and durability, as well as the hydrogen production performance. Here, a non-isothermal 3D computational fluid dynamics (CFD) model for PEMEC with parallel flow fields is employed to investigate the impacts of the heterogeneous porosity distribution within the anode porous transport layer (APTL) on the internal current density and temperature distribution uniformity and energy conversion performance. 800 heterogeneous APTL porosity distributions are applied for CFD calculation, providing dataset for deep learning. The deep operator network (DeepONet) is employed to mapping the heterogeneous APTL porosity distribution to the real physical fields such as temperature, oxygen molar fraction and current density distribution fields. Full-connected neural network is employed to construct the relationship between the heterogeneous APTL porosity distribution to the performance metrics. The gradient descent algorithm is applied to obtain APTL porosity distributions corresponding to the optimal internal current density and temperature distribution uniformity, respectively. Compared with the uniform porosity distribution, the current density and temperature uniformity are improved by 45.544 % and 26.680 %, respectively, at an average APTL porosity of 0.5.

Mass transfer and round-trip efficiency evaluation of unitized regeneration proton exchange membrane fuel cell during bi-directional mode switching cycle

Bi-directional mode switching is a crucial operation in unitized regenerative proton exchange membrane fuel cells (UR-PEMFC). Mass transfer plays a direct role in influencing the performance of both the fuel cell (FC) mode and the electrolytic cell (EC) mode, consequently impacting the round-trip efficiency (RTE). This study enhanced the three-dimensional two-phase model of UR-PEMFC by incorporating the mass transfer dynamics of the flow field. The round-trip efficiency (RTE) was systematically assessed throughout the bidirectional mode switching cycle. The results indicate that UR-PEMFC with triple-serpentine flow fields (TSF) performed well in FC mode, which was attributed to its good oxygen distribution uniformity and liquid water detachment capacity, in EC mode, its poor effective mass transfer coefficient and higher mass transfer resistance led to higher electrolytic energy consumption. However, UR-PEMFCs with TSF and parallel flow field (PFF) had better dynamic response performance during the bidirectional mode switching, and their voltage undershoot (overshoot) and response time were improved, which were attributed to uniform flow field structures. The UR-PEMFC reached optimum RTE operating at 0.1 A/cm2 in FC mode and 1.1 A/cm2 in EC mode, and the RTEs of the UR-PEMFCs with PFF and TSF were more advantageous, their highest RTEs were 36.62% and 36.30%, respectively. This study proposes two switching strategies to enhance the stability of URFC mode switching, offering a viable new approach for optimizing the flow field and improving overall performance.

Enhancing Efficiency in Hybrid Marine Vessels through a Multi-Layer Optimization Energy Management System

Abstract: Configuring green power transmissions for heavy-industry marines is treated as a crucial request in an era of global energy and pollution crises. Following up on this hotspot trend, this paper examines the effectiveness of a modified optimization-based energy management strategy (OpEMS) for a dual proton exchange membrane fuel cells (dPEMFCs)-battery-ultra-capacitors (UCs)-driven hybrid electric vessels (HEVs). At first, the summed power of the dual PEMFCs is defined by using the equivalent consumption minimum strategy (ECMS). Accordingly, a map search engine (MSE) is proposed to appropriately split power for each FC stack and maximize its total efficiency. The remaining power is then distributed to each battery and UC using an adaptive co-state, timely determined based on the state of charge (SOC) of each device. Due to the strict constraint of the energy storage devices’ (ESDs) SOC, one fine-corrected layer is suggested to enhance the SOC regulations. With the comparative simulations with a specific rule-based EMS and other approaches for splitting power to each PEMFC unit, the effectiveness of the proposed topology is eventually verified with the highest efficiency, approximately about 0.505, and well-regulated ESDs’ SOCs are obtained.

Construction of Sulfonated Carbon Nanoflowers for Efficient Proton Transportation of the Proton Exchange Membrane

Construction of Sulfonated Carbon Nanoflowers for Efficient Proton Transportation of the Proton Exchange Membrane

Preparation of Ir/TiO2 Composite Oxygen Evolution Catalyst and Load Analysis as Anode Catalyst Layer of Proton Exchange Membrane Water Electrolyzer

Preparation of Ir/TiO₂ Composite Oxygen Evolution Catalyst and Load Analysis as Anode Catalyst Layer of Proton Exchange Membrane Water Electrolyzer

A novel ‘3D + digital twin + 3D’ upscaling strategy for predicting the detailed multi-physics distributions in a commercial-size proton exchange membrane fuel cell stack

With the rapid development of proton exchange membrane fuel cell (PEMFC) commercialization, a comprehensive knowledge of multi-physics fields in large-scale PEMFC stacks has become ever more critical. Although conventional three-dimensional computational fluid dynamic (CFD) models have achieved great success, the application in the commercial-size stack-scale simulation remains inapplicable due to enormous computational resource requirements. Herein, based on the latest 3D CFD model, multi-physics digital twin (DT) technology and 3D stack flow distribution prediction model, a novel multi-scale upscaling prediction model is proposed. The voltage, water and thermal management characteristics of a 164-cell PEMFC stack with an active electrode area of 292.5 cm2 are studied and analyzed in details. For the analysis of commercial-size PEMFC stacks, the most comprehensive multi-physics fields are covered in this paper to date. And the results suggest that by introducing the DT technology, the time requirement of the multi-physics field prediction for unit scale prediction can be reduced by hundreds of thousands of times with a maximum global relative deviation of 1% under 10 groups of random test conditions, giving a solution from the cell scale to stack scale performance prediction, design, heat and thermal management in the PEMFC research and application.

In Situ-Grown Ultrathin Catalyst Layers for Improving both Proton Exchange Membrane Fuel Cell and Anion Exchange Membrane Fuel Cell Performances.

The mass transport and ion conductivity in the catalyst layer are important for fuel cell performances. Here, we report an in situ-grown ultrathin catalyst layer (UTCL) to reduce the oxygen mass transport and a surface ionomer-coated gas diffusion layer method to reduce the ion conducting resistance. A significantly reduced catalyst layer thickness (ca. 1 μm) is achieved, and coupled with the ionomer introduction method, the ultrathin catalyst layer is in good contact with the membrane, resulting in high ion conductivity and high Pt utilization. This ultrathin catalyst layer is suitable for both proton exchange membrane fuel cells and anion exchange membrane fuel cells, giving peak power densities of 2.24 and 1.11 W cm-2, respectively, which represent an increase of more than 30% compared with the membrane electrode assembly (MEA) fabricated by using traditional Pt/C power catalysts. Electrochemical impedance spectra and limiting current tests demonstrate the reduced charge transfer, mass transfer, and ohmic resistances in the ultrathin catalyst layer membrane electrode assembly, resulting in the promoted fuel cell performances.

Corrosion-Resistant and Conductive a-C/Ta/Cu-Coated Magnesium as Bipolar Plates for Ultralightweight Proton Exchange Membrane Fuel Cells

Corrosion-Resistant and Conductive a-C/Ta/Cu-Coated Magnesium as Bipolar Plates for Ultralightweight Proton Exchange Membrane Fuel Cells

Control Mechanism of a Modified Buffer Layer on Interfacial Mass Transfer Efficiency for a Proton Exchange Membrane Fuel Cell at Varying Humidity

Control Mechanism of a Modified Buffer Layer on Interfacial Mass Transfer Efficiency for a Proton Exchange Membrane Fuel Cell at Varying Humidity

Mesoporous ZrO2/C and ZnO/C nanocomposites derived from MOFs for SPEEK-based proton exchange membrane

Mesoporous ZrO2/C and ZnO/C nanocomposites derived from MOFs for SPEEK-based proton exchange membrane