Polymer Electrolyte Research Articles

Potential capacity and cost assessments for hydrogen production from marine sources

The current study comprehensively examines the application of wave, tidal and undersea current energy sources of Turkiye for green hydrogen fuel production and its cost analysis. The estimated potential capacity of each city in the country is derived from official data and acceptable assumptions and is subject to discussion and evaluation in the context of a viable hydrogen economy. According to the findings, the potential for green hydrogen generation in Turkiye is projected to be 7.33 million tons using a proton exchange membrane electrolyser (PEMEL). Cities with the highest hydrogen production capacities from marine applications are Mugla, Izmir, Antalya, and Canakkale with 998.10 kt, 840.31 kt, 605.46 kt, and 550.42 kt, respectively. The study calculations obviously show that there is a great potential by using excess power in producing hydrogen which will result in an economic value of 3.83 billion US dollars. This study further helps develop a detailed hydrogen map for every city in Turkiye, using the identified potential capacities of renewable energy sources and the utilization of electrolysers to make green hydrogen by green power. The potentials and specific capacities for every city are also highlighted. Furthermore, the study results are expected to provide clear guidance for government authorities and industries to utilize such a potential of renewable energy for investment and promote clean energy projects by further addressing concerns caused by the usage of carbon-based (fossil fuels dependent) energy options. Moreover, green hydrogen production and utilization in every sector will help achieve the national targets for a net zero economy and cope with international targets to achieve the United Nation's sustainable development goals.

Electrical behavior and water phase transformation in multi‐walled carbon nanotube/polytetrafluoroethylene composite films

AbstractMulti‐walled carbon nanotubes (MWCNTs) with excellent physiochemical properties have been recently applied to energy/power generation and storage systems encompassing polymer electrolyte membrane fuel cells (PEMFCs). However, there is a lack of investigations of the properties of MWCNT composites themselves under the actual operating conditions of systems. In this paper, MWCNTs/polytetrafluoroethylene (PTFE) composites were fabricated as electric and hydrophobic components for energy/power systems. The electrical properties, heating behavior, hydrophobicity, and water evaporation behavior of the composites are characterized within the operating voltage ranges of PEMFC. With 50% MWCNT content, the conductivity and the contact angle were 11.83 S/cm, and the contact angle 128.1°, respectively. The MWCNT/PTFE composite film showed a linear temperature rise with voltages and rapid temperature saturation within 40 s. The rate in the initial heating range was measured at 0.5°C/s for the voltage of 0.5 V. The voltage increase induced an exponential decrease in the height of water droplets on the composite surface. The evaporation rate increased almost 10‐fold, from 0.013 mm/min at 0.0 V to 0.12 mm/min at 1.0 V. The proposed characteristics of the functional composite provide insights into the material requirements for electrochemical devices, including PEMFC.Highlights Multi‐walled carbon nanotube/polytetrafluoroethylene composites can be applied to energy storage and power generation. Key properties of the composites are proposed for polymer electrolyte membrane fuel cell (PEMFC) operating conditions. The composite has a fast heating by high conductivity and temperature uniformity. Water‐vapor transformation under PEMFC operating voltage is quantified.

Enhancing ionic conductivity and controlling lithium dendrite growth via ferroelectric ceramic Bi4Ti3O12

BackgroundSolid polymer electrolytes (SPEs) have gained numerous research interest in the field of lithium metal batteries. Solid polymer electrolytes have improved safety compared to liquid electrolytes. Despite this, their low ionic conductivity remains a major barrier to practical applications. To overcome the challenge of low ionic conductivity in SPEs, our study introduces a novel approach that integrates ferroelectric ceramics with polymer solid electrolytes. MethodsWe used a one-step molten salt method to synthesize Bi4Ti3O12 (BIT), combined with a poly (vinylidene difluoride) matrix to form the composite solid-state electrolyte. Through various electrochemical characterizations and COMSOL Multiphysics simulations, we discovered that the ferroelectric properties of BIT significantly increase the dissociation of lithium salts, leading to a greater concentration of mobile lithium ions and more efficient ion transport. Significant findingsThis electrolyte showed a remarkable improvement in lithium-ion conductivity, reaching a value of 8.5 × 10−4 S cm−1 at room temperature. Batteries made with these composite electrolytes demonstrate superior cycling stability, the capacity retention rates for LFP/SPEs/Li cells remain high, reaching 95 % even after 1,000 cycles at room temperature (25 °C). These findings highlight the promising applications of ferroelectric ceramics in solid-state batteries.

Building Flame-Retardant Polymer Electrolytes via Microcapsule Technology for Stable Lithium Batteries.

Flame retardants could improve the safety properties of lithium batteries (LBs) with the sacrifice of electrochemical performance due to parasitic reactions. To concur with this, we designed thermal-response clothes for hexachlorophosphazene (HCP) additives by the microcapsule technique with urea-formaldehyde (UF) resin as the shell. HCP@UF combines with polyacrylonitrile (PAN) by hydrogen bonds successfully to form PAN-HCP@UF as the flame-retardant solid polymer electrolyte. The hydrogen bonds ensure excellent mechanical properties of the polymer electrolyte. The multiscale free radical-annihilating agent HCP effectively eliminates hydrogen free radicals of electrolytes under high temperature, showing excellent flame retardation. During the operation of the battery, functional groups on the UF resin act as active sites to promote the migration of lithium ions, while the internal HCP is protected from electrochemical reaction. With 25% HCP@UF addition, the limiting oxygen index of the PAN-HCP@UF increases to 28% and the Li+ transfer number up to 0.80. By UF protection, the initial capacity retention rate of the Li||LFP battery that assembles with PAN-HCP@UF is 88.8% after 500 cycles at 0.5 C. Thus, the microcapsule-encapsulated approach is deemed to provide an innovative strategy to prepare high-safety solid-state LB with a stable long cycle life.

Three-Dimensional Metal-Organic Framework@Cellulose Skeleton-Reinforced Composite Polymer Electrolyte for All-Solid-State Lithium Metal Battery.

High-safety and high-energy-density solid-state lithium metal batteries (SSLMBs) attract tremendous interest in both academia and industry. Especially, composite polymer electrolytes (CPEs) can overcome the limitations of single-component solid-state electrolytes. In this work, a strategy of combining a rigid functional skeleton with a soft polymer electrolyte to prepare reinforced CPEs was adopted. The in situ grown zeolitic imidazolate frameworks (ZIFs) with three-dimensional cellulose fiber skeleton (ZIF-67@CF) and succinonitrile (SN) plasticizer into poly(ethylene oxide) (PEO) together form ZIF-67@CF/PEO-SN CPEs. The addition of ZIF-67@CF and SN to PEO synergistically enhanced the physical and electrochemical properties of CPEs. Furthermore, the conduction mechanism of lithium-ion (Li+) in CPEs was studied using density functional theory. It is impressive that the ZIF-67@CF/PEO-SN CPEs at 30 °C exhibit a high ionic conductivity of 1.17 × 10-4 S cm-1, a competitive Li+ transference number of 0.40, a wide electrochemical window of 5.0 V, a notable tensile strength of 18.7 MPa, and superior lithium plating/stripping stability (>550 h at 0.1 mA cm2). Such favorable features endowed LiFePO4/(ZIF-67@CF/PEO-SN)/Li cell at 30 °C with a high discharging capacity (152.5 mA h g-1 at 0.2 C), a long cycling lifespan (>150 cycles with 99% capacity retention), and superior operating safety. This work provides insights and promotes the application of functionalized CPEs for SSLMBs.

Substrate-Free Gas Diffusion Layer Based on a Nonsolvent-Induced Phase Inversion Approach for High-Performance Proton Exchange Membrane Fuel Cells

Substrate-Free Gas Diffusion Layer Based on a Nonsolvent-Induced Phase Inversion Approach for High-Performance Proton Exchange Membrane Fuel Cells

Sensitivity analysis and optimization of operating conditions of proton exchange membrane fuel cell

Sensitivity analysis and optimization of operating conditions of proton exchange membrane fuel cell

Multiscale study of reactive transport and multiphase heat transfer processes in catalyst layers of proton exchange membrane fuel cells

Improving the performance of proton exchange membrane fuel cells (PEMFCs) requires deep understanding of the reactive transport processes inside the catalyst layers (CLs). In this study, a particle-overlapping model is developed for accurately describing the hierarchical structures and oxygen reactive transport processes in CLs. The analytical solutions derived from this model indicate that carbon particle overlap increases ionomer thickness, reduces specific surface areas of ionomer and carbon, and further intensifies the local oxygen transport resistance (Rother). The relationship between Rother and roughness factor predicted by the model in the range of 800-1600 s m-1 agrees well with the experiments. Then, a multiscale model is developed by coupling the particle-overlapping model with cell-scale models, which is validated by comparing with the polarization curves and local current density distribution obtained in experiments. The relative error of local current density distribution is below 15% in the ohmic polarization region. Finally, the multiscale model is employed to explore effects of CL structural parameters including Pt loading, I/C, ionomer coverage and carbon particle radius on the cell performance as well as the phase-change-induced (PCI) flow and capillary-driven (CD) flow in CL. The result demonstrates that the CL structural parameters have significant effects on the cell performance as well as the PCI and CD flows. Optimizing the CL structure can increase the current density and further enhance the heat-pipe effect within the CL, leading to overall higher PCI and CD rates. The maximum increase of PCI and CD rates can exceed 145%. Besides, the enhanced heat-pipe effect causes the reverse flow regions of PCI and CD near the CL/PEM interface, which can occupy about 30% of the CL. The multiscale model significantly contributes to a deep understanding of reactive transport and multiphase heat transfer processes inside PEMFCs.

Thermal enhancement of PEM fuel cell cooling with novel configurations of Tesla valve and hybrid nanofluids: A numerical study

The operating temperature and thermal distribution play a significant role in the appropriate performance of the proton exchange membrane fuel cell (PEMFC). A suitable cell cooling method can guarantee uniform temperature distribution and preservation of membrane water content under harsh conditions in a PEMFC. The compact structure of PEM fuel cells and the size of the cooling system impose a great challenge to achieve a proper design of cooling plate. In this numerical study, four designs of the multi-stage Tesla valve with straight and reverse configuration are proposed to be employed as a cooling channel in which three different hybrid nanofluids such as TiO2–Cu, Al2O3–CuO, and Ag–MgO dispersed in water and Ethylene glycol flow inside the channels. A validated numerical model is developed using a commercial computational fluid dynamics (CFD) code to investigate the effect of inlet temperatures and mass flow rates of cooling fluid and volume fraction of nanoparticles on heat transfer coefficient, pressure drop, index of uniform temperature (IUT), and performance evaluation criteria (PEC). The results demonstrated that the reverse configuration of the Tesla valve (CASE E) experienced outstanding uniform thermal distribution while the heat transfer coefficient increased by 15% in this case compared to the straight-line cooling channel. The Ag–MgO hybrid nanoparticles showed better thermal performance than the two other nanoparticles with a 4% reduction in temperature difference in the cooling plate.

A pore scale model study of mass transfer and electrochemical reaction in cathode catalytic layer of high-temperature polymer electrolyte membrane fuel cells

The mass transfer and related electrochemical reactions in the catalytic layer (CL) are crucial for the performance of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs), but there is a lack of understanding of the optimal phosphoric acid content and Pt/C catalyst loading in the CL. In this work, we investigate the influences of Pt/C catalyst numbers (NPt/C) and phosphoric acid film thickness (δPA) on mass transfer and electrochemical reactions of the cathode CL using a pore-scale model (300 × 300 × 300 nm3). The results reveal that larger NPt/C and δPA can impede oxygen diffusion, while lower NPt/C and δPA lead to fewer reaction active sites and lower conductivity, both of which result in lower current density. Therefore, the balance of three-phase transport is extremely important for CL. There is a 3D volcanic relationship between current density, Pt/C catalysts, and phosphoric acid film. At NPt/C = 200 (7407 per μm3) and δPA = 4 nm (the volume fractions of 37.22 % and 17.87 %), the highest current density can be achieved at a potential of 0.5 V (vs. RHE), which increased with the decrease of potential. This work is valuable for understanding the optimizing the microstructure and three-phase transport pathway of the CL to improve the performance of HT-PEMFCs.

Change of Mechanical Properties of e-PTFE Support by Electrochemical Degradation in Polymer Electrolyte Membrane Fuel Cell

Change of Mechanical Properties of e-PTFE Support by Electrochemical Degradation in Polymer Electrolyte Membrane Fuel Cell

New Approach to Synthesizing Cathode PtCo/C Catalysts for Low-Temperature Fuel Cells

The presented study is concerned with a new multi-step method to synthesize PtCo/C materials based on composite CoxOy/C that combines the advantages of different liquid-phase synthesis methods. Based on the results of studying the materials at each stage of synthesis with the TG, XRD, TEM, SEI, TXRF, CV and LSV methods, a detailed overview of the sequential changes in catalyst composition and structure at each stage of the synthesis is presented. The PtCo/C catalyst synthesized with the multi-step method is characterized by a uniform distribution of bimetallic nanoparticles of about 3 nm in size over the surface of the support, which result in its high ESA and ORR activity. The activity study for the synthesized PtCo/C catalyst in an MEA showed better current–voltage characteristics and a higher maximum specific power compared with an MEA based on a commercial Pt/C catalyst. Therefore, the results of the presented study demonstrate high prospects for the developed approach to the multi-step synthesis of PtM/C catalysts, which may enhance the characteristics of proton-exchange membrane fuel cells (PEMFCs).

A Dielectric MXene-Induced Self-Built Electric Field in Polymer Electrolyte Triggering Fast Lithium-Ion Transport and High-Voltage Cycling Stability.

Quasi-solid polymer electrolyte (QPE) lithium (Li)-metal battery holds significant promise in the application of high-energy-density batteries, yet it suffers from low ionic conductivity and poor oxidation stability. Herein, a novel self-built electric field (SBEF) strategy is proposed to enhance Li+ transportation and accelerate the degradation dynamics of carbon-fluorine bond cleavage in LiTFSI by optimizing the termination of MXene. Among them, the SBEF induced by dielectric Nb4C3F2 MXene effectively constructs highly conductive LiF-enriched SEI and CEI stable interfaces, moreover, enhances the electrochemical performance of the QPE. The related Li-ion transfer mechanism and dual-reinforced stable interface are thoroughly investigated using ab initio molecular dynamics, COMSOL, XPS depth profiling, and ToF-SIMS. This comprehensive approach results in a high conductivity of 1.34 mS cm-1, leading to a small polarization of approximately 25 mV for Li//Li symmetric cell after 6000 h. Furthermore, it enables a prolonged cycle life at a high voltage of up to 4.6 V. Overall, this work not only broadens the application of MXene for QPE but also inspires the great potential of the self-built electric field in QPE-based high-voltage batteries.

A Dielectric MXene‐Induced Self‐Built Electric Field in Polymer Electrolyte Triggering Fast Lithium‐Ion Transport and High‐Voltage Cycling Stability

AbstractQuasi‐solid polymer electrolyte (QPE) lithium (Li)‐metal battery holds significant promise in the application of high‐energy‐density batteries, yet it suffers from low ionic conductivity and poor oxidation stability. Herein, a novel self‐built electric field (SBEF) strategy is proposed to enhance Li+ transportation and accelerate the degradation dynamics of carbon‐fluorine bond cleavage in LiTFSI by optimizing the termination of MXene. Among them, the SBEF induced by dielectric Nb4C3F2 MXene effectively constructs highly conductive LiF‐enriched SEI and CEI stable interfaces, moreover, enhances the electrochemical performance of the QPE. The related Li‐ion transfer mechanism and dual‐reinforced stable interface are thoroughly investigated using ab initio molecular dynamics, COMSOL, XPS depth profiling, and ToF‐SIMS. This comprehensive approach results in a high conductivity of 1.34 mS cm−1, leading to a small polarization of approximately 25 mV for Li//Li symmetric cell after 6000 h. Furthermore, it enables a prolonged cycle life at a high voltage of up to 4.6 V. Overall, this work not only broadens the application of MXene for QPE but also inspires the great potential of the self‐built electric field in QPE‐based high‐voltage batteries.

Ex-situ Characterization of Nb-Ti Alloy/Pt Coated Stainless Steel Bipolar Plates for Proton Exchange Membrane Fuel Cells

Metallic bipolar plates are crucial for the development of compact and lightweight proton exchange membrane fuel cell stacks; however, most of them encounter durability and conductivity challenges in the fuel cell environment. In this study, Nb-Ti alloy/Pt coatings are deposited on SS316L plates to enhance corrosion resistance, surface wettability, electrical and thermal conductivity, with reduced interfacial contact resistance. Corrosion resistance is assessed by exposing test samples to a 1M H2SO4 acidic environment at 25 °C and 80 °C, respectively, via potentiostatic and potentiodynamic polarization tests. It is found that Nb-Ti alloy/Pt coatings exhibit exceptional stability, with corrosion potential increased by 2.5 (at 25 °C) and 0.5 (at 80 °C) times and corrosion current density reduced by orders of magnitude; and their anti-corrosion performance far exceeds the technical targets set by the US Department of Energy, with a protective efficiency of 99.98 % at both temperatures tested. The coated samples have reduced water affinity, indicated by significantly larger contact angle values compared to the uncoated samples in both pre-and post-corrosion tests. The incorporation of Nb-Ti alloy/Pt coatings on SS316L increases the in-plane electrical conductivity by 42.6 % and thermal conductivity by 3.5 %; surpassing the US Department of Energy's technical targets in these categories as well. At a compaction force of 140 N/cm2, the interfacial contact resistance for the coated samples is about 2.5 times lower than the Department of Energy's requirements. These results indicate the viability of Nb-Ti alloy/Pt coated SS316L bipolar plates for fuel cell applications.

Enhancing Performance and Stability of High-Temperature Proton Exchange Membranes through Multiwalled Carbon Nanotube Incorporation into Self-Cross-Linked Fluorenone-Containing Polybenzimidazole.

Addressing critical challenges in enhancing the oxidative stability and proton conductivity of high-temperature proton exchange membranes (HT-PEMs) is pivotal for their commercial viability. This study uncovers the significant capacity of multiwalled carbon nanotubes (MWNTs) to absorb a substantial amount of phosphoric acid (PA). The investigation focuses on incorporating long-range ordered hollow MWNTs into self-cross-linked fluorenone-containing polybenzimidazole (FPBI) membranes. The absorbed PA within MWNTs and FPBI forms dense PA networks within the membrane, effectively enhancing the proton conductivity. Moreover, the exceptional inertness of MWNTs plays a vital role in reinforcing the oxidation resistance of the composite membranes. The proton conductivity of the 1.5% CNT-FPBI membrane is measured at 0.0817 S cm-1 at 160 °C. Under anhydrous conditions at the same temperature, the power density of the 1.5% CNT-FPBI membrane reaches 831.3 mW cm-2. Notably, the power density remains stable even after 200 h of oxidation testing and 250 h of operational stability in a single cell. The achieved power density and long-term stability of the 1.5% CNT-FPBI membrane surpass the recently reported results. This study introduces a straightforward approach for the systematic design of high-performance and robust composite HT-PEMs for fuel cells.

Optimal parameters identification for PEMFC using autonomous groups particle swarm optimization algorithm

The precise model for Polymer Electrolyte Membrane Fuel Cells (PEMFCs) is vital for simulation, control, and performance analysis of PEMFCs. It is crucial to accurately estimate the model parameters. Over the past decade, the extraction of unknown parameters of PEMFCs model is formulated as optimization problem and several meta-heuristic techniques have emerged to solve this problem. Despite the development of these techniques to tackle the problem, the slow convergence rate and susceptibility to being trapped in local minima are regarded as weaknesses of these methods. Additionally, because the PEMFC model is a nonlinear and complex model, not all optimization algorithms are suitable for solving it. This article introduces a novel approach that utilizes the Autonomous Groups Particle Swarm Optimization (AGPSO) algorithm for extracting precise values for uncertain parameters inherent in PEMFC model of 250Wstack and BCS-500W stack utilized significantly in the literature. The optimization problem's fitness function is formulated as the total squared errors (TSEs) between the voltage datasets measured and estimated. Three different versions of AGPSO algorithm are presented. Statistical analysis is performed on these three versions to assess their robustness, and the most robust version is identified. Furthermore, the performance of the most robust version is extensively tested and analyzed through a complete comparison with recent optimization algorithms findings from the updated state-of-the-art literature such as BO, QOBO, TGA, HHO and ASO. Further, a statistical analysis was carried out that ensured the reliability and robustness of the introduced AGPSO. The results highlight the efficacy and feasibility of AGPSO-based approach across all compared algorithms, demonstrating an enhancement in the accuracy of the PEMFC model. A two-phase sensitivity analysis, conducted through Monte Carlo Simulation (MCS), was employed to assess how variations in optimized parameters affect the objective function (TSEs). Furthermore, the uncertainty in the maximum power reference current is identified.

Electrolytic performance of sodium alginate-poly vinyl alcohol matrix with ammonium bromide for proton conduction: Applications in electrochemical systems

Polymer blend electrolytes based on poly(vinyl alcohol) (PVA) and sodium alginate (NaAlg) were prepared using the solution casting method. These electrolytes were doped with varying amounts of ammonium bromide (NH4Br). The compatibility of NH4Br with PVA:NaAlg polymers was examined through X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) studies. The FTIR assessment confirmed the formation of a complex between PVA:NaAlg and the added salt, as evidenced by modifications and reductions in the intensity of FTIR bands related to functional groups. The conductivity and dielectric behavior of the samples were analyzed using AC impedance spectroscopy. The sample with 20 wt% of added salt exhibited a higher ionic conductivity of 1.661×10−5 Scm−1. Activation energy and relaxation time were estimated, and dielectric studies revealed a non-Debye nature. The conduction mechanism was best described by the correlated overlapping large polaron tunneling model (OLPT). The highest conducting sample was found to be suitable for electrochemical devices, as demonstrated by transference number (TNM), cyclic volumetric (CV), and linear sweep voltammetry (LSV) analyses. This high-conductivity sample can be employed in electrochemical devices such as EDLC. The cyclic voltammetry (CV) curve exhibited a nearly rectangular shape with non-faradaic peaks. GCD(Galvanostatic charge-discharge) analysis yielded specific capacitance, power density, and energy density values of 125.01 Fg−1, 1037 WKg−1, and 14.06 WhKg−1 respectively. These results indicate that polymer electrolytes show great promise as electrolytes in proton-conducting electrochemical devices.

Operando Scanning Small-/Wide-Angle X-ray Scattering for Polymer Electrolyte Fuel Cells: Investigation of Catalyst Layer Saturation and Membrane Hydration- Capabilities and Challenges.

Polymer electrolyte fuel cells are an essential technology for future local emission-free mobility. One of the critical challenges for thriving commercialization is water management in the cells. We propose small- and wide-angle X-ray scattering as a suitable diagnostic tool to quantify the liquid saturation in the catalyst layer and determine the hydration of the ion-conducting membrane in real operating conditions. The challenges that may occur in operando data collection are described in detail─separation of the anode and cathode, cell alignment to the beam, X-ray radiation damage, and the possibility of membrane swelling. A synergistic development of experimental setup, data acquisition, and data interpretation circumvents the major challenges and leads to practical and reliable insights.

Extracting Accurate Parameters from a Proton Exchange Membrane Fuel Cell Model Using the Differential Evolution Ameliorated Meta-Heuristics Algorithm

The electrochemical proton exchange membrane fuel cell (PEMFC) is an electrical generator that utilizes a chemical reaction mechanism to produce electricity, serving as a sustainable and environmentally friendly energy source. To thoroughly analyze and develop the features and performance of a PEMFC, it is essential to use a precise model that incorporates exact parameters to effectively suit the polarization curve. In addition, parameter extraction plays a crucial role in the simulation analysis, evaluation, optimum control, and fault detection of the proton exchange membrane fuel cell (PEMFC) system. Despite the development of many algorithms for parameter extraction in PEMFC, obtaining accurate and trustworthy results rapidly remains a challenge. This study presents a hybridized algorithm, namely differential evolution ameliorated (DEA) for reliably estimating PEMFC model parameters. To evaluate the proposed DEA-based parameter identification, a comparison analysis with previously published methods is conducted using MATLAB/SimulinkTM (R2016b, MathWorks, Natick, MA, USA) in terms of system correctness and convergence process. The proposed DEA algorithm is tested to extract the parameters of two PEMFC models: SR-12,500 W and 250 W. The sum of the squared errors (SSE) between the experimental and the obtained voltage data is defined as an objective function. The simulation results prove that the suggested DEA algorithm is capable of identifying the optimal PEMFC parameters rapidly and accurately in comparison with other optimization algorithms.