KR20240069108A - A method for enhancing the performance of GDL through electroless composite plating - Google Patents

Abstract

The present invention relates to high-performance, high-durability GDL and a method of manufacturing the same through a nickel-Teflon composite plating coating method. More specifically, the first electroless nickel plating on the surface of PEMFC GDL is followed by secondary nickel-Teflon composite plating or secondary nickel TiO ₂ This relates to a PEMFC GDL with improved durability through strengthening hydrophobicity and hydrophilicity using composite plating and a method of manufacturing the same.

Description

A method for enhancing the performance of GDL through electroless composite plating}

The present invention relates to a highly durable PEMFC GDL and a manufacturing method thereof. More specifically, the present invention relates to a highly durable PEMFC GDL and a method of manufacturing the same. More specifically, the first nickel electroless plating on the surface of the PEMFC GDL is followed by a hydrophobic plating using a secondary nickel Teflon composite plating or a secondary nickel TiO ₂ composite plating. and PEMFC GDL with improved durability through enhanced hydrophilicity and a method of manufacturing the same.

A fuel cell is a power generation system that directly converts chemical energy generated by electrochemically reacting fuel (hydrogen or methanol) and an oxidizing agent (oxygen) into electrical energy. It is a next-generation energy source with high energy efficiency and eco-friendly characteristics with low pollutant emissions. Research and development are underway. Fuel cells can be used by selecting high-temperature or low-temperature fuel cells depending on the field of application, and are usually classified according to the type of electrolyte. For high-temperature use, solid oxide fuel cells (SOFC) and molten carbonate fuel cells are used. There are fuel cells (Molten Carbonate Fuel Cell, MCFC), and for low temperature applications, alkaline electrolyte fuel cells (AFC) and polymer electrolyte membrane fuel cells (PEMFC) are being developed.

Polymer Electrolyte Membrane Fuel Cell (PEMFC) can be subdivided into Proton Exchange Membrane Fuel Cell (PEMFC), which uses hydrogen gas as fuel, and Proton Exchange Membrane Fuel Cell (PEMFC), which uses liquid methanol as fuel directly. There is a direct methanol fuel cell (DMFC) that is supplied and used for.

Polymer Electrolyte Membrane Fuel Cell (PEMFC) has advantages such as a low operating temperature of less than 100°C, exclusion of water leakage problems due to the use of solid electrolytes, fast start-up and response characteristics, and excellent durability, making it a portable, automotive, and home power source. The device is in the spotlight. In particular, it is a high-output fuel cell with a higher current density than other types of fuel cells, and because it can be miniaturized, research into portable fuel cells continues to progress.

In a polymer electrolyte membrane fuel cell (PEMFC), the main component, the membrane-electrode assembly (MEA), is located at the innermost part, and catalyst layers for the fuel electrode and air electrode are usually placed on both sides around the electrolyte membrane. The positioned state is referred to as a 3-layer membrane-electrode assembly, and the state in which a gas diffusion layer (GDL) is further laminated on the outer portion of the catalyst layer is referred to as a 5-layer membrane-electrode assembly. When separators with a flow field are stacked to supply fuel to the outer part of the gas diffusion layer of the membrane-electrode assembly constructed in this way and discharge water generated by the reaction, it becomes one unit cell, and several such unit cells are stacked. This creates a fuel cell stack of the desired size.

The Gas Diffusion Layer (GDL) is a very important component in the water management system, not only for the diffusion and delivery of fuel gas, but also for facilitating the discharge of water generated during operation or affecting membrane humidification. In order to facilitate the discharge of generated water, PTFE coating is applied to make it hydrophobic. However, in the case of existing hydrophobic coatings, there is a major problem of carbon and PTFE loss during operation.

The existing PTFE coating method has the disadvantage of reducing water repellency due to carbon corrosion under low current and low humidification conditions, which reduces the contact angle, and under conditions of high current and high humidification, water repellency is reduced due to loss of PTFE, resulting in flooding. there is.

Accordingly, in order to overcome the problems of existing GDL, the present inventors developed a high-performance and highly durable GDL through a nickel Teflon composite plating coating method. Specifically, by imparting hydrophilicity to the surface of existing GDL using a two-step method of nickel Teflon composite plating after nickel electroless plating on GDL, or by imparting hydrophilicity to the surface of existing GDL using a two-step method of nickel TiO ₂ composite plating after nickel electroless plating, metal and hydrophobic (hydrophilic) coating at the same time to increase electrical conductivity, allow free control of surface properties of hydrophobicity and hydrophilicity, facilitate water management, and increase coating film adhesion due to the plating process. The invention was completed.

Jayakumar, A. et al., Ionics, 21(1), 1-18, 2015 (https://doi.org/10.1007/s11581-014-1322-x) Chen, T. et al., International Journal of Heat and Mass Transfer, 128, 1168-1174, 2019 (https://doi.org/10.1016/j.ijheatmasstransfer.2018.09.097) Yu, S. et al., RSC Adv., 4(8), 3852-3856, 2014 (https://doi.org/10.1039/c3ra45770b)

The purpose of the present invention is to provide a high-performance, highly durable GDL and a method of manufacturing the same through a nickel-Teflon composite coating method.

Specifically, in the present invention, the composite plating coating process that imparts hydrophobicity consists of two steps: (first electroless nickel plating process) and (secondary nickel-PTFE composite plating coating process), and the composite plating coating that imparts hydrophilicity. The process consists of a two-step nickel Teflon composite coating process (primary electroless nickel plating process) and (secondary nickel-TIO ₂ composite plating coating process), and high-performance, highly durable GDL coated with the nickel Teflon composite coating method. It is provided.

In order to achieve the above object, the present invention provides a high-performance and high-durability gas in which a nickel plating layer is formed on the surface of a gas diffusion layer (GDL), and a nickel-Teflon composite plating layer is formed on the top of the nickel plating layer. A diffusion layer (GDL) is provided.

In addition, the present invention provides a high-performance and high-durability gas diffusion layer (GDL) in which a nickel plating layer is formed on the surface of the gas diffusion layer (GDL), and a nickel-TiO ₂ composite plating layer is formed on the top of the nickel plating layer. provides.

In addition, the present invention includes the steps of a) performing primary electroless nickel plating on the surface of the gas diffusion layer (GDL); and, b) applying a secondary nickel-PTFE composite plating coating after the first electroless nickel plating.

In addition, the present invention includes the steps of i) performing primary electroless nickel plating on the surface of the gas diffusion layer (GDL); and, ii) applying a secondary nickel-TIO ₂ composite plating coating after the first electroless nickel plating.

In addition, the present invention provides a polymer electrolyte fuel cell (PEMFC) including a high-performance and high-durability gas diffusion layer (GDL) according to the present invention.

In addition, the present invention includes a hydrophobic composite coated GDL in which a primary nickel plating layer is formed on the anode and a secondary nickel-Teflon composite plating layer is formed on the first nickel plating layer, and a cathode ( Provides a polymer electrolyte fuel cell (PEMFC) including a hydrophilic composite coated GDL in which a primary nickel plating layer is formed on the cathode and a secondary nickel-TiO ₂ composite plating layer is formed on top of the primary nickel plating layer. do.

High-performance, high-durability GDL using the nickel Teflon composite coating method according to the present invention has the following effects.

In the first-step electroless nickel plating process, the carbon surface of the porous carbon paper is wrapped with nickel to a thickness of several microns. At this time, during secondary plating, a surface to which PTFE or TiO ₂ can adhere well is formed. Additionally, since nickel is applied as a primary coating, conductivity can be imparted.

This solves the problem of existing PTFE coating not adhering well to the carbon surface or not coating evenly. PTFE coating can only impart hydrophobicity, but if TiO ₂ is added instead of PTFE, hydrophilicity can be imparted, controlling from hydrophobicity to hydrophilicity in one process. It has the advantage of being possible.

In the secondary nickel-PTFE composite plating coating process or the secondary nickel-TiO ₂ composite plating coating process, the nickel plating solution uses a high phosphorus content nickel plating solution to increase the adhesion of PTFE or TiO ₂ added with the P component. Therefore, durability is higher than that of the existing dip coating method.

Existing PTFE dip coating GDL also provides hydrophobicity, enabling water management, but through the method used in the present invention, PTFE or TiO ₂ adheres evenly to the porous carbon surface, reduces agglomeration, and improves durability with good adhesion. there is.

In addition, since nickel plating is also performed, electrical conductivity is greatly improved, which can contribute to improving the cell performance of fuel cells.

In addition, because hydrophilicity and hydrophobicity can be controlled in one way, GDL with a hydrophobic composite coating can be used on the anode side where water discharge must be easy in the fuel cell, and hydrophilic GDL can be used on the cathode where humidification of the electrolyte membrane is important.

Figure 1 is a schematic diagram of a composite plated GDL according to the present invention.
Figure 2 is a diagram showing the principle and purpose of GDL composite plating according to the present invention.
Figure 3 is a diagram showing the first electroless nickel plating process according to one embodiment of the present invention.
Figure 4 is a diagram showing a secondary nickel Teflon composite plating coating process (providing hydrophobicity) according to an embodiment of the present invention.
Figure 5 is a diagram showing a secondary nickel TiO2 composite plating coating process (imparting hydrophilicity) according to one embodiment of the present invention.
Figure 6 is a diagram showing the components and morphology of nickel Teflon composite plating GDL according to one embodiment of the present invention.
Figure 7 is a diagram showing the contact angle of nickel Teflon composite plating GDL according to one embodiment of the present invention.
Figure 8 is a graph showing the electrical resistance of the nickel Teflon composite plating GDL according to one embodiment of the present invention (GDL electrical resistance by stage and GDL electrical resistance change according to composite plating time).
Figure 9 is a graph showing the gas permeability of nickel Teflon composite plating GDL according to one embodiment of the present invention (change in GDL electric potential according to gas permeability by stage and composite plating time).
Figure 10 is a diagram showing the components and morphology of nickel TiO ₂ composite plating GDL according to one embodiment of the present invention.
Figure 11 is a diagram showing the contact angle of nickel TiO ₂ composite plating GDL according to one embodiment of the present invention.
Figure 12 is a graph showing the electrical resistance of the nickel TiO ₂ composite plating GDL according to one embodiment of the present invention (GDL electrical resistance by stage)
Figure 13 is a graph showing the electrical resistance of nickel TiO ₂ composite plating GDL according to one embodiment of the present invention (gas permeability by stage).

Hereinafter, the present invention will be described in detail.

The present invention is a high-performance and high-durability device in which a nickel plating layer is formed on the surface of a gas diffusion layer (GDL), and a nickel-Teflon composite plating layer or nickel-TiO ₂ composite plating layer is formed on the top of the nickel plating layer. Provides GDL.

The high-performance and high-durability GDL is produced through a secondary nickel-PTFE composite plating coating process after primary electroless nickel plating on the GDL surface, or a secondary nickel-TIO ₂ composite plating coating process after primary electroless nickel plating on the GDL surface. can be formed.

In the high-performance and high-durability GDL, it is preferable that the nickel plating layer and the composite plating layer each have a thickness of 0.1 to 20 μm.

In addition, the present invention includes the steps of a) performing primary electroless nickel plating on the surface of the gas diffusion layer (GDL); and, b) applying a secondary nickel-PTFE composite plating coating after the first electroless nickel plating.

In addition, the present invention includes the steps of i) performing primary electroless nickel plating on the surface of the gas diffusion layer (GDL); and, ii) applying a secondary nickel-TIO ₂ composite plating coating after the first electroless nickel plating.

In the above composite plating coating method, the composite plating coating process for imparting hydrophobicity largely consists of two steps: (first electroless nickel plating process) and (secondary nickel-PTFE composite plating coating process).

In the above composite plating coating method, the composite plating coating process for imparting hydrophilicity largely consists of two steps: (first electroless nickel plating process) and (secondary nickel-TIO ₂ composite plating coating process).

In the above composite plating coating method, in the first step electroless nickel plating process, the carbon surface of the porous carbon paper is wrapped with nickel to a thickness of several microns. At this time, during secondary plating, a surface to which PTFE or TIO ₂ can adhere is formed. Additionally, since nickel is applied as a primary coating, conductivity can be imparted. This solves the problem of existing PTFE coating not adhering well to the carbon surface or not coating evenly. PTFE coating can only impart hydrophobicity, but if TIO ₂ is added instead of PTFE, hydrophilicity can be imparted, controlling from hydrophobicity to hydrophilicity in one process. It has the advantage of being possible.

In the above composite plating coating method, the first electroless nickel plating process used a general electroless nickel process, and in the second nickel-PTFE composite plating coating process, PTFE, which can impart hydrophobicity, or nano, which can impart hydrophilicity, was used. The most characteristic feature is that TIO ₂ is added to produce a coating solution and a plating process is performed.

In the above composite plating coating method, a special feature in the secondary nickel-PTFE composite plating coating process or the secondary nickel-TIO ₂ composite plating coating process is that a nickel plating solution with a high phosphorus content is used. This increases the adhesion of the PTFE or TIO ₂ added with the P component, thereby increasing durability compared to the existing dip coating method.

In the above composite plating coating method, the existing PTFE dip coating GDL is also hydrophobic and can manage water, but through the method used in the present invention, PTFE or TIO ₂ adheres evenly to the porous carbon surface and agglomeration phenomenon is reduced, It has good adhesion and can improve durability. In addition, since nickel plating is also performed, electrical conductivity is greatly improved, which can contribute to improving the cell performance of fuel cells.

In the above composite plating coating method, since hydrophilicity and hydrophobicity can be controlled in one method, GDL with hydrophobic composite coating is used on the anode side where water discharge must be easy in the fuel cell, and hydrophilic GDL is used on the cathode where humidification of the electrolyte membrane is important. You can.

In addition, the present invention provides a polymer electrolyte fuel cell (PEMFC) including a high-performance and high-durability gas diffusion layer (GDL) according to the present invention.

The polymer electrolyte fuel cell includes a hydrophobic composite coated GDL in which a primary nickel plating layer is formed on an anode and a secondary nickel-Teflon composite plating layer is formed on the first nickel plating layer, and a cathode ( It is preferable to include a hydrophilic composite coated GDL in which a primary nickel plating layer is formed on the cathode and a secondary nickel-TiO ₂ composite plating layer is formed on top of the first nickel plating layer.

Hereinafter, the present invention will be described in detail through the following examples and experimental examples.

However, the following examples and experimental examples are merely illustrative of the present invention, and the content of the present invention is not limited by the following examples and experimental examples.

<Example 1> First electroless nickel plating process

<1-1> Process 1: Alklaine Cleaner/Conditioner

It is a pretreatment process that removes organic substances, oxides, and metal salts attached to the plating material to create a clean surface and improves adhesion and corrosion resistance in post-plating.

Alklaine Cleaner/Conditioner solution preparation: M-Condition HA Part A :50ml/L, M-Condition HA Part B :50ml/L

It was prepared by filling 500ml of DI water in a beaker, adding 50ml of Part A, stirring for 5 minutes with a magnetic bar stirrer, adding 400ml of DI water, stirring for 5 minutes, then adding 50ml of Part B and stirring for 5 minutes.

Alklaine Cleaner/Conditioner experiment process: The experiment was conducted at 60°C by slowly raising the temperature while stirring with a magnetic bar. Cleaning was performed by soaking the untreated GDL for 5 minutes.

<1-2> Process 2: Hot Rinse

The basic conditioner was washed in water at 45°C and then washed in DI water for 3 minutes.

<1-3> Process 3: Predip

This is a process that prevents contamination of catalyst chemicals that play an auxiliary role so that the catalyst can be well adsorbed.

Preparation of Predip solution: Weigh 100g of M-Predip P and add it to 500ml of DI water, then stir with a magnetic bar to slowly dissolve M-PredipP.

Predip experiment process: The GDL sample cleaned previously was immersed in the prepared pre dip solution for 1 minute (25°C).

<1-4> Process 4: Activator

This is a catalytic step that adsorbs small, highly charged colloids (PdCl ₂ ).

Preparation of Activator solution: 1.75ml of M-Activation HA was added to 500mL DI water and stirred magnetically at 450rpm to dissolve well to prepare an activation solution.

Activator experiment process: After raising the temperature from 30℃, the GDL sample was impregnated for 3 minutes and then underwent a rinse process.

<1-5> Process 5: Accelerate

This is a process to optimize catalyst activity.

Accelerate solution preparation: 5 g of M-Accelerate A was added to 500 mL of DI water and dissolved with a magnetic bar at 300 rpm for 5 minutes. 5 ml of M-Accelerate B was added and stirred at 300 rpm for 10 minutes.

Accelerate experiment process: After raising the temperature to 50℃ with a hot plate, the GDL sample was impregnated for 3 minutes to accelerate.

<1-6> Process 6: Electroless nickel plating

This is a process of performing electroless nickel electrolysis (electroless nickel process during polishing) using the chemical Entech MP-909.

Preparation of electroless nickel plating solution: Add 125ml of Entech MP 909 Make up to 250ml DI water. After stirring using a magnetic bar at 300 rpm for 5 minutes, 125 ml of DI water was added. Finally, 0.5 ml of Entech 909 starter was added and stirring was performed using a magnetic bar at 300 rpm for 5 minutes.

Electroless nickel experiment process: The temperature was raised through a hot plate and the temperature was measured through a glass thermometer. The temperature was set to 88°C, and the pH was measured using a pH meter and adjusted to 4.7 to 5.2. The pH was adjusted by adding 10 wt% sulfuric acid solution and 10 wt% ammonia water little by little. After coating for 10 minutes under optimal conditions, it was washed from side to side about 5 times with water and then dried in a dry oven at 60°C for about 30 minutes.

parameter range optimal Temperature (℃) 85 - 92℃ 88℃ pH 4.7 - 5.2 4.9 Loading of solution (dm ² /L) 0.3 - 2.5 1.2 Nickel concentration (g/L) 5.3 - 6.2 5.8

Physical Properties (Typical Results) Phosphorus content (% by weight) 6 - 9% Hardness (DPH) After being plated 600 - 650 During heat treatment 850 - 900 Thermal expansion coefficient m/m/℃ 13 - 15 Thermal conductivity Cal/cm/sec/C 0.010 - 0.011

<Example 2> Secondary nickel-PTFE composite plating coating process (imparting hydrophobicity)

Preparation of secondary nickel-PTFE composite plating solution: Since the weight of the nickel-PTFE composite plating solution is used as a standard, first put 2.25g of 20Wt% PTFE solution, fill it with 250ml DI water, and stir with a magnetic bar while stirring with Entech 512 HP- 25ml of A was added and stirred for 5 minutes. 60ml of Entech 512 HP-B was added and mixed for 5 minutes. When the total solution in the beaker reached 500ml, DI water was added and stirred to complete the solution (based on PTFE 20wt% coating).

Secondary nickel-PTFE composite plating experiment method: The temperature of the nickel-PTFE composite plating solution was raised to 85°C and the pH was adjusted to 4.7 to prepare for plating. At this time, the pH was adjusted using 10 wt% sulfuric acid solution and 10 wt% ammonia water. Once the temperature and pH were ready, nickel-PTFE composite plating was performed by placing the first electroless plated GDL sample for 10 minutes.

parameter range optimal Temperature (℃) 82 - 90℃ 85℃ pH 4.4 - 5.0 4.7 Loading of solution (dm ² /L) 0.5 - 1.5 1.0 Nickel concentration (g/L) 4.8 - 5.2 5.0

<Example 3> Secondary nickel-TiO ₂ Composite plating coating process (grants hydrophilicity)

Preparation of secondary nickel-TiO ₂ composite plating solution: The solution was prepared in the same manner as in the secondary nickel-PTFE composite plating process except that nano TiO ₂ was added instead of PTFE solution.

Secondary nickel-TiO2 composite plating experiment method: The temperature of the nickel- _TiO2 composite plating solution was raised to 85°C and the pH was adjusted to 4.7 to prepare for plating. At this time, the pH was adjusted using 10 wt% sulfuric acid solution and 10 wt% ammonia water. Once the temperature and pH were ready, nickel-PTFE composite plating was performed by placing the first electroless plated GDL sample for 10 minutes.

<Experimental Example 1> Confirmation of composition changes and morphology of nickel Teflon composite plating GDL

The composition changes and morphology of JNT20 (JNTG), a carbon paper GDL, were confirmed through electroless nickel plating and composite plating coating on bare GDL without PTFE and MPL treatment. As a result, it appeared as shown in Figure 6 (Figure 6).

<Experimental Example 2> Confirmation of contact angle of nickel Teflon composite plating GDL

Coating was performed over time for 5 minutes, 10 minutes, and 15 minutes by varying the concentration of the N slip D solution (20wt%->3.0ml/L, 30wt%->4.5ml/L) through the existing hydrophobic GDL composite plating. . Contact angles for composite plating with different Teflon concentrations were measured. Hydrophobicity can be adjusted depending on the amount. As a result, it appeared as shown in Figure 7 (Figure 7).

<Experimental Example 3> Confirmation of electrical resistance and gas permeability of nickel Teflon composite plating GDL

Electrical resistance and gas permeability were measured for composite plating with different Teflon concentrations. As a result, the results were shown in Figures 8 and 9 (Figures 8 and 9). The electrical resistance of the nickel Teflon composite plating GDL was relatively improved compared to the carbon GDL, and changes in gas permeability depending on the coating were observed. The electrical resistance decreased according to the compression rate, increasing the electrical conductivity, and gas permeability was slightly lower during composite plating, but it was confirmed that there was no problem with gas permeation.

<Experimental Example 4> Nickel-TiO ₂ Confirmation of composition changes and morphology of composite plating GDL

The changes in composition and morphology of JNT20 (JNTG), a carbon paper GDL, were confirmed through electroless nickel plating and composite plating coating on bare GDL. As a result, it appeared as shown in Figure 10 (Figure 10).

<Experimental Example 5> Nickel-TiO ₂ Checking the contact angle of composite plating GDL

As a result of measuring the contact angle of nickel TiO ₂ GDL, it was impossible to measure the contact angle due to absorption, so the degree of hydrophilicity was confirmed according to the composite plating time using a carbon plate used for a PVC welder. As a result, it appeared as shown in Figure 11 (Figure 11). Through this, it was seen that the amount of TiO ₂ plated was saturated starting from 10 minutes.

<Experimental Example 6> Nickel-TiO ₂ Check the electrical resistance and gas permeability of composite plating GDL

Electrical resistance and gas permeability for composite plating were measured. As a result, the results were shown in Figures 12 and 13 (Figures 12 and 13). Nickel TiO ₂ composite plating coating improved electrical conductivity and gas permeability compared to the existing GDL coating. Even though the overall thickness was thicker than commercial GDL, gas permeability was good. The gas permeability of commercial GDL was about 8 to 9 on average, but the gas permeability was about 15 to 18.

Claims (8)

A high-performance and high-durability GDL in which a nickel plating layer is formed on the surface of the gas diffusion layer (GDL), and a nickel-Teflon composite plating layer or nickel-TiO ₂ composite plating layer is formed on the top of the nickel plating layer.
According to paragraph 1,
High performance and high performance, characterized by being formed through a secondary nickel-PTFE composite plating coating process after primary electroless nickel plating on the GDL surface, or a secondary nickel-TIO ₂ composite plating coating process after primary electroless nickel plating on the GDL surface. Highly durable GDL.
According to paragraph 1,
High-performance and high-durability GDL, characterized by the nickel plating layer and composite plating layer forming a thickness of 0.1 to 20 μm.
a) performing primary electroless nickel plating on the GDL surface; and
b) applying a secondary nickel-PTFE composite plating coating after the first electroless nickel plating; GDL composite plating coating method for imparting hydrophobicity, comprising:
i) performing primary electroless nickel plating on the GDL surface; and
ii) applying a secondary nickel-TIO ₂ composite plating coating after the first electroless nickel plating; GDL composite plating coating method for imparting hydrophilicity, comprising:
A polymer electrolyte fuel cell (Polymer Electrolyte Membrane Fuel) comprising a composite coated GDL in which a nickel plating layer is formed on the surface of the GDL, and a nickel-Teflon composite plating layer or a nickel-TiO ₂ composite plating layer is formed on the top of the nickel plating layer. Cell, PEMFC).
According to clause 6,
The composite-coated GDL is formed through a secondary nickel-PTFE composite plating coating process after primary electroless nickel plating on the GDL surface, or a secondary nickel-TIO ₂ composite plating coating process after primary electroless nickel plating on the GDL surface. A polymer electrolyte fuel cell (PEMFC), characterized in that.
According to clause 6,
The anode includes a hydrophobic composite coated GDL in which a primary nickel plating layer is formed on the surface of the GDL and a secondary nickel-Teflon composite plating layer is formed on top of the first nickel plating layer,
The cathode is characterized in that it includes a hydrophilic composite coated GDL in which a primary nickel plating layer is formed on the surface of the GDL and a secondary nickel-TiO ₂ composite plating layer is formed on the first nickel plating layer. ,
Polymer ElectrolyteMembrane Fuel Cell (PEMFC).