Academic literature on the topic 'Protonic conductivity'

Afin de rendre les piles à combustible de type PEMFC réellement compétitives, un certain nombre d'inconvénients liés à l'utilisation du Nafion® restent à contourner, en particulier sa mauvaise conductivité protonique à des températures supérieures à 80°C. Dans l'optique de pouvoir opérer à plus hautes températures (jusqu'à 120°C), le développement de membranes moins sensibles à l'eau s'avère donc déterminant. Les polymères à base de fonctions acide phosphonique sont considérés comme des candidats potentiels pour une intégration en tant que matériau électrolyte dans les PEMFC « hautes températures » (&gt; 80°C) grâce à leur fort caractère amphotère qui leur confère une bonne conductivité protonique dans des conditions d'humidité réduites. Dans ce contexte, la majeure partie de ce travail de thèse concerne l'élaboration par polymérisation plasma (PECVD) de polymères à base de groupements acide phosphonique à partir du monoprécurseur diméthyl allyl phosphonate. Dans un premier temps, nous avons démontré la faisabilité d'élaborer par polymérisation plasma des polymères à base de fonctions acide phosphonique à partir d'un monoprécurseur. Nous avons confirmé par IRTF, EDX et XPS la présence des groupements acide phosphonique favorables au transport protonique et l'homogénéité de la composition chimique de la surface jusqu'au cœur du matériau plasma. Les matériaux plasma montrent une bonne stabilité thermique dans la gamme de température 80°C - 120°C. Ensuite, une optimisation des conditions de synthèse a été réalisée. Les plus importantes valeurs de vitesses de croissance (28 nm.min-1 sur plaquette de silicium, 22 nm.min-1 sur PTFE et 26 nm.min-1 sur Nafion®211), de CEI (4,65 meq.g-1) et de conductivité (0,08 mS.cm-1 à 90°C et 30% RH) sont celles de la membrane synthétisée à 60 W. Des mesures de perméabilité au méthanol, à l'éthanol et au glycérol ont été réalisées et montrent que les films plasma sont intrinsèquement 40 à 235 fois moins perméables au combustible que le Nafion®211 du fait de leur fort taux de réticulation. Les polymères ont été déposés en tant que liants sur des électrodes E-TEK® pour intégration en pile. Nous avons constaté que le liant phosphonique plasma possède une conductivité protonique suffisante pour permettre le transport des protons à l'interface membrane-électrodes. En parallèle, nous avons réalisé le traitement de surface par plasma d'une membrane phosphonique conventionnelle pour en améliorer la stabilité thermique et la rétention au combustible. Les analyses thermogravimétriques montrent une légère amélioration de la stabilité thermique suite au traitement de surface. Des tests de perméabilité au méthanol et à l'éthanol montrent que la membrane traitée par plasma est 2 à 4 fois moins perméable que la membrane vierge. Le traitement à 60 W conduit aux coefficients de diffusion les plus faibles (DMeOH = 9.10-12 m2.s-1 et DEtOH = 6.10-12 m2.s-1). Des tests en pile ont été effectués montrant de meilleures performances de la membrane traitée en comparaison de son homologue non traité<br>The proton exchange membrane is a key component in the PEMFC-type fuel cell; it plays a decisive role as electrolyte medium for proton transport and barrier to avoid the direct contact between fuel and oxygen. The Nafion® is one of the most extensively studied proton exchange membrane for PEMFC applications. However, it has a number of drawbacks that need to be overcome, especially the poor performance at temperature above 80°C. That's why the development of effective and low cost membranes for fuel cell turned to be a challenge for the membrane community in the last years. Phosphonic acid derivatives are considered suitable candidates as ionomers for application in PEMFC at high temperature (&gt; 80°C) thanks to their efficient proton transport properties under low humidity condition due to their amphoteric character.In this work, plasma polymers containing phosphonic acid groups have been successfully prepared using dimethyl allylphosphonate as a single precursor demonstrating the feasibility of plasma process for the manufacture of proton exchange membranes. Moreover, plasma polymers properties have been investigated as a function of the plasma conditions. The evolution of the films growth rate on three different supports as a function of the plasma discharge power is bimodal, with a maximum (close to 30 nm min-1 on Si) at 60 W. The chemical composition of plasma materials (investigated by FTIR, EDX and XPS) is quite homogeneous from the surface to the bulk; it is characterized by a wide variety of bond arrangements, in particular the presence of phosphonate and phosphonic acid groups which are above all concentrated in the plasma film synthesized at 60 W, characterized by the highest ion exchange capacity (4.65 meq g-1) and the highest proton conductivity (0.08 mS cm-1 at 90°C and 30% RH). TGA analysis has shown that phosphonic acid-based plasma polymers retain water and don't decompose up to 150 °C, which reveals a satisfying thermal stability for the fuel cell application. In terms of fuel retention, plasma films are intrinsically highly performing (methanol, ethanol and glycerol permeabilities being 40 to 235 lower than that of Nafion®211). The plasma films were deposited on fuel cell electrodes (E-TEK®) as binding agents. We have noticed that the phosphonic binder has a sufficient proton conductivity to allow proton transport at the electrode-membrane interface.A second part of this work concerns the surface treatment by plasma process of a conventional phosphonated membrane for improvement of thermal stability and fuel retention. TGA analysis has shown a slight improvement of the thermal stability for the treated membrane. Methanol and ethanol permeabilities tests show that the plasma-modified membrane is 2 to 4 times less permeable than the non-modified membrane. The treatment at 60 W shows the lowest fuel diffusion coefficients (DMeOH = 9.10-12 m2.s-1 and DEtOH = 6.10-12 m2.s-1). Fuel cell tests were realized showing better performance for the modified membrane compared to the non-modified one

Doutoramento em Ciência e Engenharia de Materiais<br>Condutores protónicos são o cerne funcional de muitos equipamentos de conversão de energia, sensores e controle de luz. Portanto, é muito importante compreender fenómenos interfaciais. O objectivo desta Tese de Doutoramento é o estudo da condutividade protónica de compósitos nano-iónicos obtidos pela dopagem heterogénea de electrólitos fracos com nanopartículas de óxido e materiais mesoporosos, que são essencialmente dieléctricos, através da formação de interfaces condutoras com elevada concentração de protões. Esta investigação baseia-se na dopagem heterogénea de electrólitos fracos tais como imidazol (Iz), benzimidazol (Bz), 1H-1,2,4-triazol (Tz) e pirazol (Pz) com nanopartículas de óxidos metálicos e os correspondentes óxidos mesoporosos, CeO2, TiO2, ZrO2 e BaZrO3. O princípio subjacente é o da criação de zonas de carga espacial com elevada concentração de protões na interface entre o electrólito e o óxido, configurando assim novos tipos de materiais interfaciais do tipo nano-iónico. Numa primeira fase, o trabalho é dedicado à síntese de CeO2, TiO2, ZrO2 e BaZrO3 mesoporosos por nano replicação utilizando SBA-15 ou CMK-3 como moldes. O material molde foi selecionado de forma a minimizar a interacção química entre o molde e os percursores, maximizando assim a pureza da fase de óxido mesoporoso obtido. O óxido de cério foi obtido usando SBA-15, o óxido de zircónio e o óxido de titânio foram preparadas usando ambos os moldes SBA-15 e CMK-3, e o zirconato de bário foi sintetizado unicamente com CMK-3. Numa segunda etapa, medidas de potencial zeta foram usadas para avaliação da carga superficial dos óxidos em contacto com os vários electrólitos, em suspensões aquosas. O potencial zeta diminui com o aumento da fracção do electrólito, o que pode ser explicado assumindo a adsorção selectiva de aniões na superfície dos óxidos. Este efeito é mais evidente com a adição de Iz e Bz do que com a adição de Tz e Pz, em concordância com a menor constante de dissociação apresentada pelos primeiros electrólitos fracos. O enriquecimento dos aniões à superfície tem de ser compensado pelo estabelecimento de regiões de carga ricas em catiões adjacentes à superfície das partículas, o que leva ao desejado efeito mesoscópico do aumento da condutividade. Este efeito foi verificado pelo estudo detalhado de espectroscopia de impedância, o qual mostra que a condutividade protónica, em condições anidras, para os compósitos óxido/electrólito aumenta com o aumento da fracção volúmica das partículas de óxido e com a mesoporosidade. O aumento da condutividade observado pode alcançar cerca de 3 ordens de magnitude em relação a CeO2 e ao electrólito Bz puros. Embora os resultados do aumento da condutividade sejam impressionantes são ainda insuficientes para aplicação tecnológica. Evidências para a contribuição interfacial encontram-se nos espectros de impedância com o aparecimento de semicírculos adicionais, que podem ser correlacionados à área interfacial óxido/electrólito através da fracção volúmica do óxido e da mesoporosidade.<br>Proton conductors are the functional core of many devices for energy conversion, sensing and light control. Thus, it is very important to understand interfacial phenomena. The main objective of this PhD Thesis is to study the protonic conductivity of nano-ionic composites obtained by heterogeneous doping of weak electrolytes with oxide nanoparticles and mesoporous materials, which are essentially dielectric, via the formation of conducting interfaces with enhanced proton concentration. This investigation is based on the heterogeneous doping of weak proton conducting electrolytes such as imidazole (Iz), benzimidazole (Bz), 1H-1,2,4-triazole (Tz) and pyrazole (Pz) with metal oxide nanoparticles and matching mesoporous counterparts of CeO2, TiO2, ZrO2 and BaZrO3. The underlying principle is the formation of proton-enriched space-charge layers at the electrolyte/particle interface, configuring in this way new types of interfacial materials of nano-ionic type. On a first stage, the work is devoted to the synthesis of mesoporous CeO2, TiO2, ZrO2 and BaZrO3 by nanocasting using suitable SBA-15 silica or CMK-3 carbon hard templates in order to minimize the chemical interaction between the template and the reactant precursors, thus maximizing the phase purity of the obtained mesoporous oxide. Ceria was obtained with SBA-15, zirconia and titania with both SBA-15 and CMK-3, and barium zirconate only with CMK-3. On a second stage, zeta potential measurements were used to assess the oxide surface charge in contact with the various electrolytes, in aqueous suspension. The zeta potential decreases with increasing fraction of electrolyte, which can be explained assuming the selective anion adsorption on the surface of the oxides. This effect is stronger upon addition of Iz and Bz than of Tz and Pz, in agreement with the smaller self-dissociation constants of the former weak electrolytes. The enriched anion surface must be compensated by the establishment of adjacent cation-rich space-charge regions, which produce the desired mesoscopic conductivity enhancement. This effect was verified by detailed impedance spectroscopy studies showing that the proton conductivity in anhydrous conditions of the oxide/electrolyte composites increases with increasing volume fraction of the oxide particle and with the mesoporosity. The observed conductivity enhancement may reach ca. 3 orders of magnitude with respect to pure CeO2 and Bz. While impressive, the attained conductivities are still insufficient for technological application. Evidence for interfacial contribution is found in impedance spectra by additional semicircles, which can be correlated to oxide/electrolyte interfacial area through the oxide volume fraction and mesoporosity.

Ce travail de thèse s'inscrit dans la continuité des travaux de recherche réalisés sur le développent de nouvelles membranes échangeuses de protons pour piles à combustibles de type PEMFC, porteuses de groupements protogènes acides phosphoniques. L'objectif de ces travaux est d'apporter des solutions permettant l'amélioration des propriétés physico-chimiques d'un copolymère phosphoné, le poly(CTFE-alt-VEPA) obtenu à partir de la polymérisation radicalaire de vinyl éthers et de CTFE. La première stratégie employée est une stratégie Blend. Elle consiste à ajouter un polymère fluoré commercial, le poly(VDF-co-CTFE), lors de la mise en forme de la membrane. Les membranes ainsi obtenues montrent d'excellentes propriétés mécaniques et des valeurs de conductivité protonique acceptable. Cependant, lors de l'acidification du polymère phosphoné, une légère dégradation est observée. Une nouvelle technique de réticulation a alors été mise en place afin d'augmenter la stabilité vis-à-vis des acides. La réticulation de ces membranes blend a de plus permis d'améliorer la miscibilité entre le polymère fluoré et le polymère phosphoné. Enfin, les derniers travaux de cette thèse concernent la synthèse de copolymère à bloc à partir d'une stratégie RAFT. Ainsi la polymérisation radicalaire contrôle de monomère phosphoné a pu être réalisée<br>This work is a continuation of research conducted on the development of new proton exchange membrane fuel cell (PEMFC), bearing phosphonic acid as protogenic groups. The aim of this work is to provide solutions with a view to improving the physicochemical properties of a phosphonate copolymer, poly(CTFE-alt-VEPA) obtained from the radical polymerization of vinyl ethers and CTFE. The first strategy used is a Blend strategy. It consists of adding a commercial fluorinated copolymer, poly(VDF-co-CTFE), during the casting of the membrane. The membranes thus obtained show excellent mechanical properties and acceptable values of proton conductivity. However, during the acidification of membrane, a slight degradation of the phosphonate copolymer is observed. A new technique of crosslinking was then established to increase the stability versus acids. The crosslinking of the blend membranes has also helped to improve the miscibility between the fluorinated copolymer and phosphonate polymer. Finally, the last work of this thesis relate to the synthesis of block copolymer from a RAFT strategy. Thus, the controlled radical polymerization of monomer phosphonated was achieved

Philosophiae Doctor - PhD (Physics)<br>In this thesis, some of the challenges experienced by high temperature polymer electrolyte membrane fuel cells are explored through material modelling techniques. A very important aspect for a fuel cell is that it should have high proton conductivity. As hydrogen enters a fuel cell it gets broken down into its constituents, protons and electrons. The electrons travel to an external load, whilst the protons travel through a diffusive layer, catalyst layer and membrane area, before recombining with oxygen to form water and leave the system. In this particular study, polytetrafluoroethylene and carbon form the diffusive layer, platinum the catalyst and poly(2,5-benzimidazole) doped with phosphoric acid the membrane area. The effects to proton conductivity are investigated as a result of the mixing of materials and adsorption of the phosphoric acid on the platinum active sites. A third study as an alternative avenue for proton conductivity improvements, is also explored. The results from these investigations promotes the idea that polytetrafluoroethylene, which is found in the ionomer layer, should be replaced as its mechanical properties decrease significantly with increase in temperature. Increasing pressure would further promote proton transfer over the doped polymer membrane region.

L'état d'hydratation des électrolytes polymères pour piles à combustibles de type PEMFC et donc, la conductivité protonique de ce type d'électrolytes, est le point crucial pour comprendre et expliquer les performances électrochimiques de ce type de système. Le fonctionnement de la pile (création, absorption, diffusion, migration et désorption d'eau) conduit à une forte hétérogénéité de l'état d'hydratation du matériau polymère et donc de sa conductivité.La conductivité protonique des membranes actuellement utilisées comme électrolyte est le fait de la structure du matériau, des mécanismes de diffusion de l'eau et du proton, et des interactions eau-polymère au sein de la membrane. Nous nous sommes intéressés à ces problèmes et avons étudié les mécanismes d'hydratation et de diffusion par les techniques de spectroscopies vibrationnelles Infra-Rouge et Raman.Ce travail démontrera, entre autres, l'apport particulièrement intéressant des spectroscopies vibrationnelles in-situ pour la résolution de la problématique de la distribution de l'eau au sein de la membrane et son influence sur les performances de la pile. Nous proposons ici une étude de deux polymères perfluorosulfonés, le Nafion et l'Aquivion.Les propriétés d'absorption d'eau, de diffusion d'eau et de transport du proton dans ces deux membranes sont étudiées dans diverses conditions d'hydratation : dans les conditions d'équilibre, sous gradient d'activité chimique de l'eau (mesure in situ) et sous l'effet d'un champ électrique (mesure in situ et operando dans une pile en fonctionnement). La spectroscopie Infra-Rouge est utilisée pour étudier les changements structuraux des polymères ainsi que l'état de confinement de l'eau au cours de l'hydratation des membranes soumises à différentes valeurs de pression partielle d'eau et de température. Elle permet également d'étudier les interactions entre l'eau et les différents groupements chimiques présents dans la structure du polymère. L'ensemble des résultats est utilisé pour proposer des mécanismes d'absorption de l'eau ainsi que de dissociation des groupements acides de la membrane. La micro-spectroscopie Raman confocale, grâce à sa résolution spatiale micrométrique, permet de sonder l'épaisseur de la membrane et de déterminer le gradient d'eau transverse. Une cellule micro-fluidique a été développée pour l'étude des phénomènes de transport diffusif. Cette technique est actuellement la seule permettant de calculer les coefficients de diffusion équivalente à partir des gradients de concentration d'eau interne.Une pile à combustible spécialement adaptée aux mesures Raman, nous a permis, pour la première fois avec cette technique, de déterminer la distribution de l'eau à travers l'épaisseur de la membrane dans le système électrochimique en fonctionnement. Les informations ainsi obtenues sont des données primordiales pour comprendre, expliquer et prévoir l'impact de la distribution de l'eau au sein du cœur de pile sur les performances globales de ce système<br>The water content of polymer electrolytes for Proton Exchange Membrane Fuel Cells and, thus, their proton conductivity, is the key issue to understand and to explain the electrochemical performances of the PEMFC electrochemical device. The fuel cell operation (creation, absorption, diffusion, migration and desorption of water) leads the hydration state of the membrane strongly heterogeneous. The proton conductivity of state-of-art polymer electrolytes results from the material structure, the water and proton diffusion mechanisms and the interactions between water and the polymer phase within the membrane. This work deals with these issues and uses vibrational spectroscopy techniques (Infra-Red and Raman) to study hydration and diffusion phenomena. Among others, this work shows the contribution of in-situ vibrational spectroscopies to the understanding of the water management issue and relationships between the water distribution throughout the membrane and the fuel cell electrochemical performances. Two perfluorosulfonated polymers, Nafion and Aquivion, are investigated.The water absorption and diffusion properties of these two membranes are studied under several hydration conditions: at the equilibrium, under external gradient of the water chemical activity and under the effect of an electric gradient (in-situ and operando measurements with the working fuel cell).Infrared spectroscopy is used to study structural modifications of the polymer phase occurring during the hydration process as well as the confinement state of water sorbed within the membrane. The last is submitted to different water vapor pressures and temperatures. This spectroscopy also allows to study interactions between water and the different chemical groups belonging to the polymer structure. Results are used to describe water absorption as well as the proton dissociation mechanism involving the sulfonic groups.Confocal Raman Micro-spectroscopy allows, by the spatial resolution at the micrometric scale, to probe the thickness of the membrane and to measure the inner, through-plane, water gradient. A micro-fluidic cell has been developed for the study of diffusion transport phenomena. This method is currently the only one by which equivalent diffusion coefficients can be calculated from internal water concentration gradients.A fuel cell especially designed for Raman measurements allowed us, for the first time by means of this technique, to determine the water distribution through the thickness of the membrane working in the electrochemical device. The new insights so obtained are essential for understanding, explaining and predicting the effects of the heterogeneous water distribution throughout the fuel cell heart on the electrochemical behavior

This Thesis describes the synthesis and characterisation of novel metal-organic frameworks designed for proton conductivity applications. A new system for impedance measurements was constructed and tested, and the proton conductivity of a variety of MOFs was studied. Additionally, the effect of ligands with phosphonate functional groups, the strategic choice of metal ions and the use of proton carrier guests loaded in the pores of MOFs to obtain conducting materials was investigated. Chapter 1 introduces the current challenges in energy sustainability and endorses fuel cells as an alternative energy source. A careful description of the proton exchange membrane (PEM), key component of fuel cells, with emphasis on the materials currently used in industry is discussed. The need to overcome the limitations of PEMs under the working conditions and understanding the molecular mechanism of proton conduction is crucial for the design of new materials with improved proton conductivity properties. Recently, metal-organic frameworks (MOFs) have been pointed as alternative candidates for proton conduction application. Their crystalline nature combined with the possibility to design their structures by choosing opportune functional groups and proton-carrier guests make them promising candidates as proton conducting materials. Chapter 2 presents a brief introduction of Electrochemical Impedance Spectroscopy (EIS), the main technique used to evaluate the proton conductivity of the MOFs in Chapters 3, 4 and 5. An overview of the physical basis of EIS and the data analysis strategies are discussed. In the second part of Chapter 2 the newly designed experimental set up employed to measure the proton conductivity of MOFs is described with emphasis on the design of the conductivity cell, control of temperature and relative humidity, and sample preparation. The calibration of the experimental set up was performed using imidazole, a readily available linker with known conductivity. In Chapter 3 the synthesis and structural characterisation of two new isostructural phosphonate-based MOFs,[Ni3(H3L1)2(H2O)10.5(DMF)3]and[Co3(H3L1)2(H2O)10.4(DMF)3](H6L1= benzene-1,3,5-p-phenylphosphonic acid), denoted as NOTT-500(Ni) and NOTT-500(Co), are described. X-ray structural analysis revealed that these materials have acidic phosphonate groups (P-OH) and water molecules coordinated to the metal ions (M-OH2) organised in an efficient proton-hopping pathway. TGA, VT-PXRD and solid-state UV-visible analyses showed a reversible structural phase transition associated with a marked change in colour upon dehydration-hydration of NOTT-500(Ni, Co). Proton conductivity measurements were performed exhibiting values of 1.11(03) x 10-4 S cm-1 and 4.42(06) x 10-5 S cm-1 forNOTT-500(Ni) and NOTT-500(Co) respectively, at 99 % RH and 25 o C. The activation energy of the proton transfer process for NOTT-500(Ni) was determined over the temperature range of 18-31 o C at 99 % RH, giving a value of 0.46 eV which indicates the proton conduction occurs through the combination of the Grotthuss and Vehicle mechanisms. Quasi-elastic neutron scattering (QENS) experiments on NOTT-500(Ni) under anhydrous conditions (0 % RH) suggested that the proton transfer in the hopping pathway (regulated by the Grotthuss mechanism) is well described by a “Spherical free diffusion” model, with an activation energy of 0.076 eV. Chapter 4 introduces two novel approaches to enhance the proton conductivity of a new family of lanthanide MOFs, [M (HL2)] (H4L2= biphenyl-4,4'-diphosphonic acid ; M = La, Ce, Nd, Sm, Gd, Ho). The first method aims to increase the concentration of protons in a fixed volume of MOF by using the shorter version of the organic ligand, benzene-1,4-diphosphonic acid, H4L3, with subsequent improvement of the proton conductivity properties in [M(HL3)] (M = La, Ce, Nd, Sm, Gd, Ho). The second method to achieve better proton conductivity was carried out by substituting 3+ metal ions, Ln (III), with a 2+ metal, Ba (II), leading to the synthesis of an isostructural complex [Ba(H2L2)] with increased number of protons in comparison with [M(HL2)]. The proton conductivities of [M (HL3)] (10-4 S cm-1) and [Ba (H2L2)] (10-5 S cm-1) exhibited a significant increase when compared with [M (HL2)] (10-6 S cm-1) at 25 o C and 99 % RH. Extensive impedance studies at different temperatures and relative humidities were performed together with full characterisation of all the materials presented in this Chapter. Chapter 5 describes a preliminary study of two new complexes synthesised through postsynthetic modification of the well-known MOF, NOTT-300(Al). The addition of imidazole (a proton carrier) into the 1D channels was performed using two different approaches; the vapour diffusion (d) and solvation methods(s). Impedance studies of the post-synthetically modified complexes, Im@NOTT-300(Al)-(d) and Im@NOTT-300(Al)-(s), both with formula {Al2(OH)2(C16O8H6)(Al2O3)(CH4O)2(C3N2H4)0.61}∞, were investigated. The experimental results showed that at 20 o C and 99 % RH the proton conductivity of Im@NOTT-300(Al)-(d) (2.39(11) x 10-5 S cm-1) and Im@NOTT-300(Al)-(s)(1.37(13) x 10-5S cm-1) is two orders of magnitude higher compared with NOTT-300(Al) (1.08(10) x 10-7 S cm-1). These preliminary studies suggested the postsynthetic modification of porous MOFs with proton-carrier guest molecules is a promising direction for further research in this area. In Chapter 6 is summarised the work presented in this thesis.

Proton exchange membrane (PEM) fuel cell has the potential to be one of the main energy sources in the future. However, the leading issues when operating the fuel cells are the water and the thermal managements. In this thesis, numerical studies have been developed in order to investigate the sensitivity of the PEM fuel cells performance to the thermal conductivities of the main components in PEM fuel cells, which are the membrane, the gas diffusion layer (GDL) and the catalyst layer. In addition, the effect of the thermal conductivity of these components and the metallic GDL on the temperature distribution and the water saturation was considered conducive to the improvement of the heat and water management in PEM fuel cells. On the other hand, the experimental work was completed to determine the effects of the thermal conductivity and the thermal contact resistance of the components in PEM fuel cells. The thermal conductivity of the GDL was measured in two directions, namely the in-plane and the through-plane directions taking into account the effect of the main parameters in the GDL which are the mean temperature, the compression pressure, the fibre direction, the micro porous layer (MPL) coating and polytetrafluoroethylene (PTFE) loading. Furthermore, the thermal conductivities of the membrane and the catalyst layer were measured in both directions, the in-plane and the through-plane, with considering the effect of the temperature and the Pt loading in the catalyst layer, and the effect of the water content and temperature on the membrane. This study is a comprehensive study on the thermal conductivity of PEM fuel cells and emphasized the importance of the thermal conductivity of the components in PEM fuel cells.