Evaluation Of Fuel Cell Performance Research Articles

Evaluation of the Performance and Mechanical Stability of PEMFC Single Cell Considering Vibration Characteristics in the Construction Equipment Working Environment

As the global demand for eco-friendly power sources increases, the adoption of hydrogen fuel cells as a sustainable and environmentally friendly alternative is gradually expanding in the construction equipment sector. Fuel cell technology has already gained significant attention with successful applications in various mobility sectors, including cars, buses, railways, and trucks. However, research in areas requiring extreme environmental conditions, such as construction equipment, is relatively scarce. Construction equipment often operates under high vibration and harsh climatic conditions, necessitating studies on fuel cell performance evaluation in similar environments. Previous studies have shown that applying vibration to hydrogen fuel cells can directly affect their performance, but research targeting construction equipment is very limited. Since vibration is an inevitable aspect of construction sites, research on this topic is essential for the practical application of hydrogen construction equipment. Based on this background, this study aimed to obtain basic data for the development of hydrogen fuel cells for construction equipment that can maintain stable performance even in a vibrational environment, by understanding the performance degradation and structural stability changes of fuel cells under vibration conditions. The fuel cells used in this study were 5 cm × 5 cm PEMFC single cells, and vibration tests were conducted in vertical, longitudinal, and lateral directions using a laboratory-scale shaker. The PEMFC single cells were kept in an operating (ON) state during the experiments, and vibrations that could occur in construction equipment were applied. The performance changes of the fuel cells according to vibration intensity and frequency were measured using constant current analysis, current-voltage (I-V) curves, and impedance analysis methods. Constant current analysis was used to evaluate the voltage stability of the single cell, I-V curves for assessing electrochemical efficiency and optimal operating conditions, and impedance analysis for evaluating electrical properties in electrodes and electrolytes.

Mechanically Tough Polymer Electrolyte Membranes Prepared By Radiation-Induced Graft Polymerization of Poly (ether ether ketone) Film

The development of state-of-the-art polymer electrolyte membranes is indispensable for solid polymer fuel cells. To make a desired membrane, we have reported the radiation-induced graft polymerization (RGP) method in our previous studies, which is a fascinating technique with great advantages of low-cost fabrication and imparting new functionality via graft polymers to commercially available substrate polymer films, whose excellent mechanical/thermal properties are maintained. Among various substrate polymers, poly (ether ether ketone) (PEEK) is regarded as the most promising aromatic hydrocarbon material for the long life-time operation requirement of fuel cells due to its excellent mechanical stability and high gas barrier property at high temperature. However, graft polymerization on PEEK substrate is rather difficult. To successfully obtain PEEK-based polymer electrolyte membranes with suitably-balanced properties, we have extensively investigated the graft polymerization and irradiation conditions. In this work, we will report the synthesis of both PEEK-based proton- and anion-exchange membranes (PEEK-PEMs and PEEK-AEMs, respectively), and the fuel cell performance using these two types of membranes.1)RGP for making PEEK-PEMs and PEEK-AEMs. The PEEK base films used for RGP was previously immersed in (1, 4-dioxane) DOX at 50°C for 18 hours as a solvent annealing treatment. Ethyl styrene sulfonate (ETSS) and chloromethyl styrene (CMS) are used as precursors for PEMs and AEMs, respectively (Scheme 1).For the synthesis of PEEK-PEMs, the solvent-annealed PEEK films were pre-irradiated with 60Co ϒ-ray at room temperature in argon atmosphere with a total dose 160 kGy. Then the samples were immersed in ETSS/DOX solution (1/1 v/v) at 80°C under the argon atmosphere. The resultant grafted-PEEK membranes has a grafting degree (GD) of 150%. After hydrolysis treatment, the final PEEK-PEM shows an ion-exchange capacity (IEC) of 2.5 mmol/g and a proton conductivity of 0.1 S/cm at 25 °C. For the synthesis of PEEK-AEMs, the same irradiation and polymerization procedures as in the synthesis of PEEK-PEMs were performed, by using CMS as monomers instead of ETSS. The CMS-grafted PEEK with high GD of 66% was obtained in tetraethylenglycol as a solvent. The grafted PEEK was converted to AEM by treating in trimethylamine with a quaternization degree of 76%. The obtained AEM has an IEC of 1.7 mmol/g and an anion conductivity of 0.128 S/cm at 60°C. The mechanical strength and elongation of the resulting PEEK-PEM at 80°C and 100%RH were measured to be 22 MPa and 50%, respectively, which are superior to those of Nafion (10 MPa and 200%, respectively). PEEK-AEM also shows good mechanical strength and elongation of 94 MPa and 18%, respectively, at room temperature and 70% RH.2)Fuel cell performance evaluation. Fuel cell test using PEEK-PEMs and AEMs was carried out according to previous reports [1]. The membrane was sandwiched by anode and cathode electrodes (Pt or Pt/Ru loading 0.5 mg/cm2) and hot-pressed, and then obtained membrane/electrodes assembly (MEA) was then set into a 5 cm2 fuel cell for testing. The cell was fed with pure hydrogen and oxygen gases at a flow rate of 0.05 L/min each to the anode and cathode, respectively, under atmosphere pressure. The cell condition was 80°C and 100%RH.Fuel cell test with an MEA incorporating 16 μm PEEK-PEM shows a good performance of an open circuit of 0.9 V and a power density of 860 mW/cm2 at a current density of 2240 mA/cm2 (Figure 1(a)). Using the PEEK-g-AEM membrane, it shows an open circuit voltage value of more than 0.9 V and a power density of 673 mW/cm2 at a current density of 1199 mA/cm2 (Figure 1(b)). As described above, utilizing radiation-induced graft polymerization, we have for the first time successfully developed two types of polymer electrolyte membranes, PEEK-PEM and PEEK-AEM, using the mechanically tough and chemically stable aromatic hydrocarbon polymer PEEK as the substrate.[1] J. Chen, et al. J.Membr. Sci. 2008, 319, 1-4. Figure 1

Potentiostatic lithium plating as a fast method for electrolyte evaluation in lithium metal batteries

One of the most crucial factors to enable metallic lithium anodes is having an electrolyte that allows stable and safe battery cycling, however, the commonly used carbonate electrolytes typically perform poorly, highlighting the need for the development of new electrolyte compositions. Evaluating potential electrolyte candidates is typically a lengthy procedure that does need time-consuming long-term cycling experiments. To speed this process up, we have investigated potentiostatic lithium plating, inspired from hydrogen-pumping performed for fuel cell performance evaluation, as a potential method for fast electrolyte suitability investigation. First, scanning electron microscopy was used to establish a link between lithium surface coverage and measured current response in a model carbonate electrolyte. Afterwards, a selection of carbonate and ether electrolytes was used for validation of our testing procedure, showing that individual, characteristic patterns can be distinguished. Apart from giving an insight into Li transport in each electrolyte, a correlation to physical electrolyte properties can be found. Consequently, our findings may be a first step towards using potentiostatic plating as a fast, easy and high-throughput method to investigate suitability of new electrolyte formulations for lithium metal batteries and beyond.

Enhancing water uptake and hydroxide ion conductivity of alkali fuel cell electrolyte membrane by layered double hydroxide

Novel hydroxide ion-conductive composite membranes were fabricated through incorporating coprecipitation-synthesized magnesium (Mg)–aluminum (Al)-type layered double hydroxides (LDHs) into a potassium hydroxide (KOH)-doped polybenzimidazole (PBI) membrane to improve the hydroxide ion conductivity for the application to alkali fuel cells. The addition of LDH was essential for improving the water affinity of the PBI–KOH membranes. Although the KOH uptake of the LDH-incorporated PBI membranes decreased with increasing amounts of LDHs in the water uptake test, thermal analysis showed that the water content in the membrane increased with increasing amounts of added LDHs. LDH-incorporated PBI membranes showed the high hydroxide ion conductivity and the reduced dependent of the humidity because of the high amount of adsorbed water and high ionic conductivity of LDHs. The alkaline fuel cell performance evaluation test showed that the prepared PBI–KOH membrane with 30 wt% LDH had the highest power output, exhibiting a maximum power density of 210 mW cm−1 at 80 °C, which is more than double that of the cell device without LDH. Improved performance due to the high-water adsorption and hydroxide ion conductivity was achieved by incorporating LDHs into the KOH-doped PBI membranes.

Data-driven modeling and monitoring of fuel cell performance

A mathematical framework that provides practical guidelines for user adoption is proposed for fuel cell performance evaluation. By leveraging the mathematical framework, two measures that describe the average and worst-case performance are presented. To facilitate the computation of the performance measures in a practical setting, we model the distribution of the voltages at different current points as a Gaussian process. Then the minimum number of samples needed to estimate the performance measures is obtained using information-theoretic notions. Furthermore, we introduce a sensing algorithm that finds the current points that are maximally informative about the voltage. Observing the voltages at the points identified by the proposed algorithm enables the user to estimate the voltages at the unobserved points. The proposed performance measures and the corresponding results are validated on a fuel cell dataset provided by an industrial user whose conclusion coincides with the judgement from the fuel cell manufacturer.

Novel platinum group metal-free catalyst ink deposition system for combinatorial polymer electrolyte fuel cell performance evaluation

A new system for rapid and precise fabrication of polymer electrolyte fuel cell (PEFC) membrane-electrode assemblies (MEAs) is introduced to facilitate rapid testing and characterization of platinum group metal-free (PGM-free) catalysts, with minimal waste of materials, using commercial combinatorial hardware and multi-channel potentiostat. The commercial combinatorial system, designed for high-throughput catalyst activity evaluation (i.e., low overpotential and current densities) using gas-diffusion electrodes (GDEs), has been further developed to enable simultaneous evaluation of the high current density performance on air of twenty-five cathodes prepared by coating catalyst-ionomer inks directly onto the membrane using a newly-developed deposition system. A nanopipette or micropipette coupled to a precise peristaltic pump is being used for precise and even catalyst ink deposition onto the membrane in each of twenty-five circular electrodes with areas of <1 cm2 and in the precise locations required by the commercial combinatorial MEA hardware. The automated ink deposition system is coupled with a custom-designed heated vacuum table mounted on a computer-controlled XY stage to prevent deformation of the membrane and electrode layers during ink deposition onto the membrane. This system was utilized to evaluate the impact of ionomer to catalyst ratio on the hydrogen-air fuel cell performance of the PGM-free catalyst.

Parameter optimization of polymer electrolyte membrane fuel cell using moment-based uncertainty evaluation technique

Finding the optimal operational parameters of polymer electrolyte membrane (PEM) fuel cells is very critical for improving its efficiency. The incorporation of uncertainties in the operational parameters during the optimization process is very important to ensure that the fuel cell can operate reliably in real-life deployment. Unfortunately, no attention has been given thus far on studying the effects of parameter uncertainties on the fuel cell performance. In this paper, the output power and hydrogen flow rate are being optimized under uncertain conditions of the stack current, stack temperature, oxygen excess ratio, hydrogen excess ratio and inlet air humidity of the PEM fuel cell. The effective application of a new analytical moment-based uncertainty evaluation technique proposed in combination with response surface methodology provides an accurate and numerically efficient evaluation of the fuel cell performance. The paper has demonstrated that the optimal mean output power under uncertainty is 1329.56W and its corresponding operating point is different from that of the optimal output power 1545.25W calculated assuming all parameters are fixed. The results show that, for the selected PEM fuel cell model, meeting probabilistic constraints makes the fuel cell less susceptible to input variations, but this can only be achieved at the expense of optimal output power. The useful framework, analyses and discussions presented in the paper can be adapted into any fuel cell performance evaluation and design optimization.

A selective hybrid stochastic strategy for fuel-cell multi-parameter identification

Abstract The in situ identification of fuel-cell material parameters is crucial both for guiding the research for advanced functionalized materials and for fitting multiphysics models, which can be used in fuel cell performance evaluation and optimization. However, this identification still remains challenging when dealing with direct measurements. This paper presents a method for achieving this aim by stochastic optimization. Such techniques have been applied to the analysis of fuel cells for ten years, but typically to specific problems and by means of semi-empirical models, with an increased number of articles published in the last years. We present an original formulation that makes use of an accurate zero-dimensional multi-physical model of a polymer electrolyte membrane fuel cell and of two cooperating stochastic algorithms, particle swarm optimization and differential evolution, to extract multiple material parameters (exchange current density, mass transfer coefficient, diffusivity, conductivity, activation barriers …) from the experimental data of polarization curves (i.e. in situ measurements) under some controlled temperature, gas back pressure and humidification. The method is suitable for application in other fields where fitting of multiphysics nonlinear models is involved.

Enhanced electrochemical activity of hybrid composite membranes and their proton conductivity

This study presents a new type of proton-conducting membrane with good structural and electrochemical properties when used as an electrolyte for low-temperature proton-exchange membrane fuel cells. The cross-linking agents, glutaraldehyde and poly(vinyl alcohol), were reacted with tetraethyl orthosilicate and 3-glycidyloxypropyltrimethoxysilane. The obtained membranes demonstrated large proton conductivity, in the order of 10−2S/cm at -20 to 140°C and a relative humidity of 50%. The fuel cell performance evaluation was performed at 70°C, and a maximum current density of ~401 mA/cm2was obtained at a cell voltage of 0·6 V. The cell stability was constant during the measurement. The swelling ratio was calculated in dry and wet conditions; it was determined that the membrane had a significant swelling capability. Moreover, the thermal, mechanical and electrochemical stabilities were good. The structural characterization of the composites was investigated using various techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry analysis and impedance measurements.

Development of Ultra-Low Pt Alloy Cathode Catalyst for PEM Fuel Cells

Two approaches are described for the synthesis of ultra-low platinum loading catalysts for polymer electrolyte membrane fuel cell (PEMFC). The first approach is the synthesis of a hybrid cathode catalyst (HCC) which combines a non-platinum carbon based composite catalyst (CCC) with active catalytic sites for oxygen reduction reaction (ORR) as a support and highly active Pt/Pt-alloy catalysts. The activity of HCC is found to be 1.3 times higher than that of Pt/C in the platinum loading range of 0.1-0.4 mg cm-2, while it is 2.6 times that of Pt/C at platinum loading of 0.04 mg cm-2. The goal of our second strategy is the development of activated graphitic carbon (AGC) supported Pt3M1 (M=non-precious transition metal) catalyst (Pt3M1/AGC). The Pt3M1/AGC catalyst showed mass activity of 0.41 A mgPt-1 and specific activity of 1023 µA/cm2 at 0.9 ViR-free. Fuel cell performance evaluation under H2/air exhibited a high current density performance of 1.45 A at 0.56 ViR-free.

Evaluation of Fuel Cell Performance and Degradation

The concepts of area specific resistance (ASR) and degradation are developed for different fuel cell operating modes. The concepts of exergetic efficiency and entropy production were applied to ASR and degradation. It is shown that exergetic efficiency is a time-dependent function useful describing the thermal efficiency of a fuel cell and the change in thermal efficiency of a degrading fuel cell. Entropy production was evaluated for the cases of constant voltage operation and constant current operation of the fuel cell for a fuel cell undergoing ohmic degradation. It was discovered that the Gaussian hypergeometric function describes the cumulative entropy and electrical work produced by fuel cells operating at constant voltage. The Gaussian hypergeometric function is found in many applications in modern physics. This paper builds from and is an extension of several papers recently published by the authors in the Journal of The Electrochemical Society (ECS), ECS Transactions, Journal of Power Sources, and the Journal of Fuel Cell Science and Technology.

Evaluation of Fuel Cell Performance and Degradation

not Available.

고분자전해질형 연료전지의 효율향상에 대한 연구

연료전지의 안정성 여부를 장시간에 걸쳐 측정하기 위한 stability test logic을 LabVIEW 기반으로 설계하여 개선된 평가 system을 구성하였다. 일반적으로 사용되어온 logic에서 탈피하여 다량의 데이터 수집을 통한 평균값과 표준편차를 도출함으로서 연료전지 성능 데이터의 안정성 검증과 신뢰도를 대쪽 향상시킬 수 있었다. 가습의 새로운 개념인 water injection system방법을 제시하였으며 양측가습의 경우와 비교할 때 4% 이하의 미미한 성능 차이를 보였다. Water injection system의 경우 가습에 필요한 에너지를 최소화할 수 있으므로 전체적인 에너지효율을 높일 수 있고 system을 소형화할 수 있다는 장점이 있다. 영하의 조건에 연료전지를 방치한 후 실험을 수행한 경우 성능이 다소 감소하였으며, 이와 같은 현상은 MEA의 구조 및 제조사에 따라 영향을 받는 것으로 사료된다. 연료전지 운전 후 영하의 상태로 내려가기 전에 가스를 사용하여 내부의 물을 제거하는 방법에 대한 실험을 수행하였다. 저온방치 전 건조실험에서 전극면적이 <TEX>$25cm^2$</TEX>인 경우에 성능저하가 거의 없었다. Fuel cell performance evaluation logic was developed using G-language (LabVIEW) to measure performance stability. Degree of stability and reliability of performance data were improved with averaged value and standard deviation method. Water injection system was introduced and the performance using this method was comparable to that of conventional humidification method. Water injection system has advantage of lowering operation energy consumption, reducing the number of parts needed in humidification, therefore increasing efficiency of fuel cell system. Fuel cell performance was decreased in case of low temperature operation such as sub freezing condition. Air purge method was tested to reduce the water content in cell fixture before sub freezing condition. The performance degradation due to low temperature operation was minimized by air purge method in medium size cell fixture (<TEX>$25cm^2$</TEX>) case.

XRD and XPS Analysis of As-Prepared and Conditioned DMFC Array Membrane Electrode Assemblies

Catalysts prepared by the Adams and Reetz method were ranked against a Johnson Matthey PtRu catalyst in an array fuel cell in the direct methanol fuel cell (DMFC) mode. The Reetz and Johnson Matthey PtRu catalysts were found to be equivalent. The catalysts were analyzed in membrane and electrode assemblies (MEA) before and after fuel cell performance evaluation. The X-ray diffraction (XRD) analysis showed no changes of the crystalline phases before and after fuel cell evaluation. However, the X-ray photoelectron spectroscopy (XPS) showed that in the electrode containing the Reetz catalyst, substantial loss of Ru at the MEA surface occurred during fuel cell operation. Loss of Ru also occurred at the MEA surface containing the Johnson Matthey catalyst while an enrichment of Ru on the electrode surface containing the Adams catalyst was observed. A lattice parameter analysis of all catalysts showed Pt enrichment in the alloy phase, with the largest enrichment in the Adams catalyst. © 2004 The Electrochemical Society. All rights reserved.