Proton Exchange Membrane Fuel Cell Vehicles Research Articles

Application of template method in fabricating ordered gas diffusion layer of PEMFC

ABSTRACT As a core component of proton exchange membrane fuel cell (PEMFC), gas diffusion layer (GDL) takes an important role in the migration of gas, liquid, heat, and electrons. Optimizing GDL microstructure is crucial to improve the gas-liquid flowing behavior and enhance PEMFC performance. Therefore, an ordered GDL is designed by coupling the template method and stacking multiple fiber layers method to provide the large holes for water elimination and the small pores for gas delivery. The ordered GDL possesses excellent mass transfer capacity, which can improve the PEMFC performance compared with commercial GDL under high relative humidity (RH). At RH 100% and 70°C, the PEMFC with ordered GDL achieves the maximum peak power density of 0.92 W cm−2, which realizes an increment of 10.8% compared with commercial GDL. However, with a decrease in RH, the ohmic loss gradually occupies the primary contribution to the performance compared with the mass transfer capacity, resulting in a downward trend of the performance of PEMFC with ordered GDL. This work provides a simple and efficient strategy to design the ordered pore structure of GDL, and the outcomes have the potential of being implemented in the future PEMFC vehicles.

Adaptive Anti-Surge Control Strategy for PEM Fuel Cell Vehicle With Online Surge Detection

In this study, an online adaptive anti-surge control (OAASC) strategy is proposed for proton exchange membrane (PEM) fuel cell system. Insufficient attention has been given to the issue of the surge in the air supply system, which can damage the compressor and stack, reducing the fuel cell vehicle’s efficiency and lifespan. The OAASC approach employs a multiple time-domain sliding window technique and characteristic energy-based correction to detect and adaptively contain surges before they become serious. A dynamic model of the fuel cell air supply system with surge prediction is established using a two-stage parameter identification process and is verified through 60 kW fuel cell engine experiments. Simulation and experimental comparisons between OAASC and standard industrial methods are conducted to evaluate the proposed method’s performance. The experimental results demonstrate that the proposed strategy improves control performance, with surges being detected within 0.2 s and recovering within 0.5 s.

Multi-time-step and multi-parameter prediction for real-world proton exchange membrane fuel cell vehicles (PEMFCVs) toward fault prognosis and energy consumption prediction

Proton exchange membrane fuel cell vehicle (PEMFCV) is considered to be a promising way to cope with the environment pollution and energy exhaustion. But PEMFCV is also suffering from some difficulties for the real-world application, including different kinds of faults and hydrogen refueling. This raises requirement for timely and accurate fault prognosis and energy consumption prediction. However, limited and sparse parameters obtained by onboard sensors and random influencing factors during the real-world vehicular operation make the PEMFCV hardly be modelled. To cope with the issue, this study firstly puts forward a vehicle state-driving behavior factor (VDF) construction of PEMFCV to consider as comprehensive factors as possible and uses maximal information coefficient (MIC) to extract related factors for model training. Then a data-driven model is constructed to achieve synchronous multi-time-step and multi-parameter prediction for the fuel cell and hydrogen system in real-world PEMFCVs. The model considers noise denoising, spatial feature processing and temporal feature processing by combining convolutional neural network (CNN) and gated recurrent unit neural networks (GRU). To optimize numerous hyperparameters of constructed data-driven model, a “discrete gradient-based optimization” method (DGO) is first proposed to achieve local-optimized hyperparameters as well as reduce the time complexity of grid searching. Based on the predicted parameters of PEMFCVs, a scheme is designed for fault prognosis and energy consumption prediction. All the procedure is trained and verified by real-world operation data to reflect the real-world applicable conditions for different seasons and vehicles. Results show that the proposed model can achieve accurate 30-time-step synchronous fuel cell temperature, hydrogen temperature, and hydrogen pressure prediction with mean-relative-errors (MREs) of 0.54%, 0.85% and 0.71%; The fault can be accurately prognosed five minutes ahead with MRE of 0.71% to provide driver sufficient time to deal with the fault; The small MRE of 6.3% for energy consumption prediction also indicates the effectiveness of proposed model. The proposed whole method can be applied in the real-world PEMFCVs for long-time-step parameter prediction, fault prognosis, and energy consumption prediction. The proposed DGO can be used to optimize other data-driven methods.

Performance evaluation on thermodynamics-economy-environment of PEMFC vehicle power system under dynamic condition

Proton exchange membrane fuel cell (PEMFC) has the merits of fast starting speed, zero pollution, high efficiency and high reliability, which is gradually applied to new energy vehicles. In this paper, a vehicle PEMFC power system model is established, which is mainly consisted of PEMFC stack, air compressor, hydrogen circulation pump, cooling water pump and humidifier. The influence of auxiliary equipment energy consumption on fuel cell power system efficiency and total system cost under dynamic conditions is studied. Moreover, the mapping relationship between operating parameters (operating temperature, inlet humidity of anode and cathode) and thermodynamic system performance (electrical power, electrical efficiency, thermal efficiency) is analyzed. The auxiliary equipment energy consumption and system thermal performance output of the vehicle PEMFC system model at the 180-300A step current is obtained. Furthermore, total system cost and pollutant emissions quality under transient response and dynamic operation are estimated. The results show that in a 30 kW vehicle PEMFC system model, the net output power of the system can reach 22.5 kW. The maximum electrical efficiency and thermal efficiency of the system reach 41 % and 52.1 %, respectively. After 2400 h operation, the total system cost reaches 62616$. Wind energy hydrogen production shows the lowest pollutant emission.

Graphene-nanopocket-encaged PtCo nanocatalysts for highly durable fuel cell operation under demanding ultralow-Pt-loading conditions.

The proton exchange membrane fuel cell (PEMFC) as an attractive clean power source can promise a carbon-neutral future, but the widespread adoption of PEMFCs requires a substantial reduction in the usage of the costly platinum group metal (PGM) catalysts. Ultrafine nanocatalysts are essential to provide sufficient catalytic sites at a reduced PGM loading, but are fundamentally less stable and prone to substantial size growth in long-term operations. Here we report the design of a graphene-nanopocket-encaged platinum cobalt (PtCo@Gnp) nanocatalyst with good electrochemical accessibility and exceptional durability under a demanding ultralow PGM loading (0.070 mgPGM cm-2) due to the non-contacting enclosure of graphene nanopockets. The PtCo@Gnp delivers a state-of-the-art mass activity of 1.21 A mgPGM-1, a rated power of 13.2 W mgPGM-1 and a mass activity retention of 73% after an accelerated durability test. With the greatly improved rated power and durability, we project a 6.8 gPGM loading for a 90 kW PEMFC vehicle, which approaches that used in a typical catalytic converter.

An efficient cold start strategy for proton exchange membrane fuel cell stacks

Starting the proton exchange membrane fuel cell (PEMFC) stack from subfreezing temperatures is a remaining challenge for the commercialization of PEMFC vehicles. This paper aims to provide an efficient cold start strategy for PEMFC stacks to meet the requirements of rapid, safe and efficient startup in a wide range of subfreezing temperatures. Herein, an efficient cold start strategy combines the advantages of self-starting and coolant heating is proposed and validated in terms of startup time, voltage consistency and energy consumption. Results demonstrate that self-starting from −20 °C is achieved within 30 s. Rapid and safe cold-start from −30 °C and −40 °C is also realized within 82 s and 100 s, respectively. The target heating temperature of −20 °C is optimal for this strategy. The voltage consistency of the stack during cold start is closely related to cold start performance, and is affected by the starting temperature and the heating power. The stack voltage consistency increases with the increase of starting temperature and heating power. Energy conservation calculations indicate that the heating power should match the stack temperature to avoid excessive energy consumption and insufficient heating. This paper provides an efficient solution for cold starting of a hybrid PEMFC system.

Strategy optimization of proton exchange membrane fuel cell cold start

<p indent="0mm">Under the background of “carbon peaking and carbon neutrality” goals, the proton exchange membrane fuel cell (PEMFC) vehicle attracts extensive attention due to its high energy conversion efficiency, long range and zero emission. However, the challenge of cold start in low temperature environments becomes a large obstacle to its commercialization and application. The current cold start performance of typical commercial fuel cell vehicles cannot reach the optimal target yet. Several problems such as the lack of complete mechanical systems of water transport and phase change and the absence of simulation models for on-board fuel cells at system level still exist. Thus, researchers have carried out a great number of experiments and simulations to study the mechanism of degradation, water transport, phase change and heat transfer as well as start-up strategy optimization of PEMFC cold start. By measuring the output performance, it is found that the degradation of performance is attributed to the formation of ice which covers the reaction active region, blocks the gas channel and increases the electrical contact resistance. Researchers also believe that the reduction of durability is owing to the volume change of water-ice phase change which leads to the damage of the structure by characterizing the microstructure of the fuel cell. With the help of transparent cells, neutron imaging and simulations of multiphase PEMFC models, the distribution, transport and phase change of water and ice during cold start have been studied. The results indicate that the electrochemical product water first saturates the PEM and the catalyst layer (CL) as membrane water. Then the water remains liquid in the form of supercooled water at low temperatures, and finally flows out of the cell or freezes suddenly. By studying the heat transfer process both in plane and through plane during cold start, researchers find that at central regions of the single cell and in the middle part of the stack, the temperature rises fastest. They also find that the irreversible reaction heat generated by cathodic oxygen reduction reaction (ORR) is the main source of heat generation. Based on the cold start mechanism of PEMFCs, researchers have developed various self-start and auxiliary start strategies. The start-up mode and control strategies have been optimized. The internal structure and materials of each part have been improved. And a series of auxiliary startup strategies such as gas purging, heater heating, reaction heating, gas heating as well as coolant heating have been proposed. A large number of simulations and experiments are carried out to verify the advantages of these strategies. Through these excellent cold start strategies, the commercialization and promotion process of PEMFC vehicles can be accelerated.

Novel structural designs of fin-tube heat exchanger for PEMFC systems based on wavy-louvered fin and vortex generator by a 3D model in OpenFOAM

Heat management is crucial to the stable and high-efficiency operation of proton exchange membrane fuel cell (PEMFC) system. However, fin-tube heat exchangers (FTHE) of traditional internal combustion engine vehicles require further optimizations to be applicable to PEMFC vehicles. In the paper, a three-dimensional steady-state radiator model is developed in OpenFOAM to investigate three novel structural designs based on wavy-louvred (WL) fin and vortex generators (VGs). The established model has been carefully validated against experimental data and correlation reference. To comprehensively evaluate radiator performances, the air side heat transfer coefficient, pressure drop, outlet air temperature, heat flux, and JF factor are adopted. It is found that the FTHE with L-VGs has the highest heat transfer coefficient while the FTHE with WL-VGs has the highest pressure drop. The temperature, velocity, and pressure distribution are further demonstrated to reveal performance enhancement mechanisms. It is seen that the heat exchangers with additional VGs produce two sections of high-temperature wakes near the wall, which not only promotes the heat convection but also contributes to the heat exchange in the nearby area. Meanwhile, a low-speed vortex zone behind VGs appears and generates longitude vortex, making the air stream stay longer at fin surfaces. The air flow in FTHE with WL is not as much separated as the conventional FTHE since the zigzag wavy louver restricts flow separation. The paper gives valuable suggestions for cooling capability improvement and radiator volume diminution.

Research on Economic and Operating Characteristics of Hydrogen Fuel Cell Cars Based on Real Vehicle Tests

With the increase of the requirement for the economy of vehicles and the strengthening of the concept of environmental protection, the development of future vehicles will develop in the direction of high efficiency and cleanliness, and the current power system of vehicles based on traditional fossil fuels will gradually transition to hybrid power. As an essential technological direction for new energy vehicles, the development of fuel cell passenger vehicles is of great significance in reducing transportation carbon emissions, stabilizing energy supply, and maintaining the sustainable development of the automotive industry. To study the fuel economy of a passenger car with the proton exchange membrane fuel cell (PEMFC) during the operating phase, two typical PEMFC passenger cars, test vehicles A and B, were compared and analyzed. The hydrogen consumption and hydrogen emission under two operating conditions, namely the different steady-state power and the Chinese Vehicle Driving Conditions-Passenger Car cycle, were tested. The test results show the actual hydrogen consumption rates of vehicle A and vehicle B are 9.77 g/kM and 8.28 g/kM, respectively. The average hydrogen emission rates for vehicle A and vehicle B are 1.56 g/(kW·h) and 5.40 g/(kW·h), respectively. By comparing the hydrogen purge valve opening time ratio, the differences between test vehicles A and B in control strategy, hydrogen consumption, and emission rate are analyzed. This study will provide reference data for China to study the economics of the operational phase of PEMFC vehicles.

Disturbance and Uncertainty-Immune Onboard Charging Batteries With Fuel Cell by Using Equivalent Load Fuzzy Logic Estimation-Based Backstepping Sliding-Mode Control

Proton exchange membrane fuel cell (PEMFC)/battery hybrid electric vehicle is considered as promising transportation due to its eco-friendly characteristics. This article investigates a fuzzy logic (FL)-based adaptive backstepping sliding-mode control (BSMC) approach to generate stable charging current and voltage for battery charging applications on a non-plug-in PEMFC vehicle. An adaptive BSMC is proposed to address nonlinearities and disturbances caused by dc/dc buck converter, PEMFC, and equivalent load variations of batteries. Moreover, an FL-based approximation is utilized to estimate the time-varying equivalent load of batteries through the adaptive laws obtained by the defined Lyapunov function and can offer assistance estimating the state of charge (SOC) of batteries. Simulation comparisons between a proportional-integral (PI) control and the proposed FL-based adaptive BSMC were executed subsequently under certain conditions to validate the efficacy. Finally, experiments on the PEMFC/battery hybrid power system scaling prototype via NI (PCI-6229)-LabVIEW platform were implemented to test the charging performance of the proposed approach. The comparative results indicated that the FL-based adaptive BSMC method could regulate charging current and voltage against disturbance and uncertainty and estimate the equivalent load of batteries accurately.

Determination of the optimal battery capacity of a PEM fuel cell vehicle taking into account recuperation and supercapacitors

Proton exchange membrane (PEM) fuel cell vehicles require an electrical intermediate storage system to compensate for dynamic load requirements. That storage system uses a battery and has the task to increase tolerance to dynamic operation. In addition, energy can be recuperated and stored in supercapacitors to increase the fuel cell vehicle’s efficiency. To determine the optimal battery capacity according to the recuperation potential and possible use of a supercapacitor, a reference vehicle with PEM fuel cell was transferred to the simulation environment Matlab/Simulink. The model is based on a cell model describing the electrochemical and physical interactions within the cell. It has been implemented in a complete vehicle model for the representation of a fuel cell vehicle. Various legal driving cycles, such as the WLTP (“Worldwide harmonized Light Vehicles Test Procedure”), were used for the calculations. A further step sets the optimal battery capacity depending on the dynamic of the fuel cell system. With this simulation model, dynamic requirements—for the fuel cell and the associated system components—can be determined in the future, scalable for each vehicle depending on the battery capacity and recuperation potential.

Control logics and strategies for air supply in PEM fuel cell engines

Proton exchange membrane (PEM) fuel cells have been a long pursuit due to its high efficiency and environmental benign, and PEM fuel cell vehicles have already been commercialized and are being pushed on the market worldwide. One of key components, fuel cell compressors in the balance of plant, and the air supply were thoroughly reviewed in this paper. Following the governing laws and fundamental theory about compressors, the type and characteristics of various fuel cell compressors were summarized. Roots, screw, centrifugal compressors and some supercharger or turbocharger among most positive displacement and dynamic compressors were considered as the best options for the on board application. Their application by automotive manufacturers was briefly introduced. Due to the autonomous air supply in PEM fuel cell engine, various control logics and strategies for the air supply were extensively reviewed. The sole control including PID control, model predictive control, sliding mode control, fuzzy control, neural control, etc, and the hybrid or hierarchical structures of control like parenting, parallel, and combined structures were systematically discussed, which might shed light on the future research.

Modelling and control of vehicle integrated thermal management system of PEM fuel cell vehicle

An effective vehicle integrated thermal management (VITM) system is critical for the safe and efficient operation of proton exchange membrane fuel cell (PEMFC) vehicles. The objectives of this paper are to model the VITM system and develop control strategies for the VITM system of fuel cell vehicles (FCVs). To do that, the VITM system model, based on the heating principle of each key component and heat transfer theory, was developed in KULI. The VITM system includes 5 loops for a prototype of range extender sport utility vehicle (SUV), which is powered by a 36 kW PEMFC stack and an 11 kW h Li-ion battery. Then, three steady-state and two transient working conditions of FCVs were selected to simulate. The results showed that the temperatures of all components were controlled within the required ranges, indicating that the VITM system achieves relatively positive cooling capacity and satisfies the requirements of thermal management control effect. It showed that the developed VITM system could analyse the impact on one loop and the integrated impact on the whole vehicle when the thermal state of one or several components changes, which is useful to guide the VITM system design of the PEMFC vehicles.

Using harmonised life-cycle indicators to explore the role of hydrogen in the environmental performance of fuel cell electric vehicles

This work uses harmonised life-cycle indicators of hydrogen to explore its role in the environmental performance of proton exchange membrane fuel cell (PEMFC) passenger vehicles. To that end, three hydrogen fuel options were considered: (i) conventional, fossil-based hydrogen from steam methane reforming; (ii) renewable hydrogen from biomass gasification; and (iii) renewable hydrogen from wind power electrolysis. In order to increase the robustness of the life-cycle study, the environmental profile of each hydrogen option was characterised by three harmonised indicators: carbon footprint, non-renewable energy footprint, and acidification footprint. When enlarging the scope of the assessment according to a well-to-wheels perspective, the results show that the choice of hydrogen fuel significantly affects the life-cycle performance of PEMFC vehicles. In this regard, the use of renewable hydrogen –instead of conventional hydrogen from steam methane reforming– is essential when pursuing low carbon and energy footprints. Nevertheless, the identification of the most favourable renewable hydrogen option was found to be conditioned by the prioritised life-cycle indicators.

Cathode Loading Impact on Voltage Cycling Induced PEMFC Degradation – a Voltage Loss Analysis

Proton exchange membrane fuel cell (PEMFC) based vehicles are on the verge of commercialization. However, significant hurdles for further market penetration of PEMFC vehicles are cost reductions by decreasing the amount of platinum catalysts while meeting long term durability targets. The durability of catalysts is usually estimated by accelerated stress tests (ASTs) using voltage cycling.[1] Generally, the electrochemically active surface area (ECSA) and mass activity of the cathode catalyst is analyzed over the course of 30000 voltage cycles, while effects of O2 mass transport related losses, especially for varying cathode catalyst loadings have not yet been systematically studied. To better understand the influence of voltage cycling based ASTs on the development of mass transport resistances and on the extent to which they can be captured by currently available in situ diagnostics (ORR kinetics in H2/O2, cathode proton conduction resistance by impedance, oxygen transport resistance via limiting current measurements), we conducted a comprehensive voltage loss analysis on MEAs with high- and low-loaded cathodes (0.4 and 0.1 mgPt/cm2) over the course of ASTs conducted in H2/N2 (anode/cathode) at ambient pressure, 80 °C, and 100% RH, using different voltage cycling profiles: i) triangular wave (TW) and square wave (SW) cycles between 0.6 and 1.0 VRHE; ii) TW cycles between 0.6 and a lowered upper potential limit of 0.85 VRHE (TW-LUPL); and, iii) a combination of a triangular sweep between 0.6 and 1.0 VRHE with potential hold periods at the upper and lower potential (TW-H). For all ASTs, the O2 transport resistance scaled inversely to the cathode electrode roughness factor (rf). Since the ECSA decreases in the course of potential cycling and two different loadings were used, a wide range of rf values with their corresponding pressure-independent O2 transport resistance was analyzed, proving its dependence on the available Pt surface area (Figure 1) as shown also by other researchers.[2] The pressure dependent transport resistance remained essentially constant. Furthermore, ex situ thickness measurements of catalyst layers showed no cathode thinning, indicating the absence of significant carbon corrosion. While 30000 TW or SW cycles dramatically decreased the H2/air performance for low- and high-loaded MEAs, only a negligible degradation in performance was observed when a lower upper potential limit of 0.85 VRHE was applied, providing a guideline to limit MEA degradation under automotive conditions. Figure 1: Pressure independent O2 transport resistance vs the electrode’s roughness factor, rf, for high-loaded (0.4 mgPt/cm2, blue) and low-loaded (0.1 mgPt/cm2, orange) catalyst layers over the course of different voltage cycling ASTs. Figure 1

(Invited) Advancement of Thin, Reinforced Membranes for High-Performing, Long-Lasting Proton Exchange Membrane Fuel Cells

After decades of research and development, commercialization of proton-exchange membrane fuel cell (PEMFC) vehicles is now a reality, and several production scale vehicles have been launched. GORE-SELECT® Membranes (GSMs) enable the Toyota Mirai (2015), Honda Clarity (2016), and Hyundai Nexo (2018)1. However, mass deployment of PEMFC vehicles is hindered by lack of hydrogen infrastructure and higher cost than internal combustion engines2. W. L. Gore and Associates, Inc. (Gore) is committed to supplying the fuel cell market with the highest performance and most durable membranes to support the lowest $/kW system. One approach to simultaneously increase power density and decrease membrane cost (by reducing material content) is to use thinner membranes, ca. 10 µm or less. Thin membranes facilitate high performance systems by means of higher proton conductance and faster water transport properties, yet durability remains a challenge. Gore is uniquely positioned to deliver high-strength reinforcement layers for the most mechanically durable thin membranes at high volume with superior uniformity. Expertise in engineering fluoropolymer composites has allowed Gore to develop thin membranes that mechanically outlast thicker membranes while exceeding performance, Figure 1. The remaining challenge to address is chemical durability. Higher gas permeance of thin membranes can result in increased radical generation through multiple mechanisms3. As shown in Figure 2, Gore is working to increase the selectivity of protons relative to gas crossover, which is critical for maintaining performance while extending chemical lifetime. Additionally, chemical degradation can be mitigated through advanced additive strategies. In this talk we discuss Gore’s understanding and advancements of thin membrane technology culminating with the introduction of new state-of-the-art membranes that break the cost / performance trade-off. ACKNOWLEDGMENTS The authors gratefully acknowledge the contribution of the Electrochemical Products team of W. L. Gore and Associates, Inc. REFERENCES W. L. Gore & Associates, (2018) https://www.gore.com/news-events/press-release/gore-s-fuel-cell-technology-helps-power-latest-hyundai-fuel-cell-vehicle.D. L. Greene and G. Duleep, Status and Prospects of the Global Automotive Fuel Cell Industry and Plans for Deployment of Fuel Cell Vehicles and Hydrogen Refueling Infrastructure, Oak Ridge, Tennessee, (2013).M. Zaton, J. Rozière, and D. J. Jones, Sustain. Energy Fuels, 1, 409–438 (2017). Figure 1

Numerical Simulation of the Power Performance a Proton Exchange Membrane Fuel Cell Under Dynamic Loading Conditions

Proton exchange membrane fuel cell (PEMFC) is an ideal form of power generator, but its performance is drastically compromised under dynamic loading conditions. For the purpose of correctly understanding and accurately predicting the power performance of PEMFC under dynamic loading conditions so as to facilitate the rational design of PEMFC vehicles, this paper first built a high-fidelity 3D model of a PEMFC, then precisely calculated the dynamic voltage response during the non-steady stages, and finally identified the influential factors that can moderate the dynamic response. Results suggest that avoiding extremely large rate of current density change can keep the PEMFC running in steady state, which is beneficial to the lifetime of the PEMFC. Meanwhile, raising the anode/cathode pressure to 2.0 atm, maintaining the excess H2/O2 coefficients above 2.0/2.5, or keeping the anode/cathode inlet sufficiently humidified to 100% R.H. help the PEMFC to quickly reach new equilibrium in response to dynamic loading. The novelty of this paper is embedded in the detailed modeling of the PEMFC micro structure as well as the systematic parametric analysis of the potential moderating factors and mechanisms of the dynamic response.

(Plenary) Electrochemical Diagnostics and Modeling in Developing the PEMFC Cathode

One key challenge to enable a wide spread adoption of proton-exchange membrane fuel cell vehicles is the reduction of Pt use to a level comparable to the incumbent internal combustion engine vehicles (<5 gPM/vehicle). Great progress in recent years in improving the activity and durability of Pt-based catalysts, particularly Pt alloy catalysts, has enabled a reduction of Pt loading in the cathode approaching 0.15 mgPt/cm2 or about 15 gPt/vehicle. However, as we attempt to go below 10-15 g/vehicle, a large performance loss is often observed at high-current density (high power). In the cathode, where oxygen molecules meet protons and electrons to produce water, one must create as much interface as possible in order to minimize the transport resistances. As Pt loadings are reduced, performance losses due to these transport phenomena become more localized to the Pt and ionomer interface, posing new challenges to diagnose and understand these electrodes. In this talk, we will discuss how we use in-situ electrochemical diagnostics and modeling to understand the performance of low-Pt electrodes, identify their key limiting factors, and guide our catalyst layer development. Diagnostics used to quantify the kinetic terms, proton conduction, oxygen transport resistance, and Pt-ionomer interaction will be introduced. Moreover, because non-noble metals leach out from Pt alloy catalysts and can replace protons in the ionomer, we will also consider the resulting impact on low-Pt electrode performance. This work was partially supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy under grant DE-EE0007271.

A Comprehensive Review of Solutions and Strategies for Cold Start of Automotive Proton Exchange Membrane Fuel Cells

Proton exchange membrane fuel cell (PEMFC) can be a significant eco-friendly alternative power source for vehicles. However, under subfreezing conditions, cell degradation and irreversible performance decay can occur because of ice formation and repetitive thaw/freeze cycles. These problems have limited the further commercialization of PEMFC in cold weather countries. Thus, many improvements have been made to repair the freeze protection and rapid cold startup problems in PEMFC vehicles. In this paper, a comprehensive review dedicated to engineers of the recent research progress on the PEMFC cold start problems is presented. Systems and methods for fuel cell shutdown are summarized and classified into two categories: purge solution and material to avoid freezing. Regarding the system and solutions for PEMFC cold startup, different heating solutions are classified into two main groups depending on their heating sources and categorized as internal and external heating methods. This paper concludes with a detailed review of cold startup strategies based on an exhaustive survey of journal papers and patents.

Traction Control for a Fuel Cell Hybrid Vehicle (FCHV)

Traction control for the proton exchange membrane (PEM) fuel cell hybrid vehicle is studied. The traction control denotes the anti-slipping action when the vehicle meets sudden road surface friction changes. Slip ratio is utilized to analyze the slipping action, and optimum value is chosen for controlling the motor speed to prevent the slip. A one-dimensional longitudinal model of a fuel cell vehicle is constructed to prove the traction control effectiveness. The model includes a fuel cell system, a battery, an inverter and permanent synchronous motor, a bi-directional converter and a vehicle dynamics. Two three-phase permanent magnet synchronous motors (PMSM) are utilized to generate the required power for the vehicle traction. Maximum transmissible torque estimation (MTTE) control and sliding mode control are utilized for the PEM fuel cell vehicle traction control algorithms. The simulation results show that the proposed control algorithm effectively prevents vehicle slipping when a PEM fuel cell vehicle meets a sudden road friction change by distributing appropriate powers between battery and fuel cell.