CN113488674B - Assembling method of cylindrical self-breathing fuel cell - Google Patents

Abstract

The invention provides a cylindrical self-breathing fuel cell which comprises an anode current collector, a membrane electrode, a cathode current collector and a tensioning mechanism, wherein the membrane electrode is wound on the anode current collector, the cathode current collector is wound on the membrane electrode, and the tensioning mechanism is tensioned and clamped at a joint of the cathode current collector so that the cathode current collector is wound and attached on the membrane electrode. The invention also provides an assembly method of the cylindrical self-breathing fuel cell. The beneficial effects of the invention are: the problems of membrane electrode contact and sealing of the fuel cell with a cylindrical structure are solved, the cell has high reliability, and higher power density is realized compared with the traditional flat-plate fuel cell.

Description

A kind of assembly method of cylindrical self-breathing fuel cell

technical field

The present invention relates to a fuel cell, in particular to a cylindrical self-breathing fuel cell and an assembling method thereof.

Background technique

Fuel cells are a common way to utilize hydrogen energy, with the advantages of clean products, high power density and high energy conversion rate, and have broad application prospects under the trend of carbon neutrality. For some special application scenarios, the load occupied by the auxiliary equipment of the fuel cell (such as hydrogen circulation pump, reaction gas humidification device, etc.) and the generated parasitic power consumption become unacceptable. Taking drones as an example, self-breathing fuel cells that directly expose the cathode to the atmospheric environment without auxiliary equipment are commonly used. Thanks to the high energy density of hydrogen, fuel cell drones generally have more than three times the battery life compared to traditional lithium battery drones. Existing fuel cell drones are generally industrial-grade drones with a take-off weight of more than 20kg, using kilowatt-level flat-panel self-breathing stacks. However, some low-power application scenarios, such as application scenarios of several watts to ten watts (such as bionic ultra-light drones, etc.), put forward higher requirements on the power density and energy density of the power supply. If the monolithic cell or stack of the traditional flat structure continues to be used, the flat structure requires the end plate to have a certain structural rigidity to achieve contact and sealing, and the end plate will not shrink linearly with the size of the battery, which will cause considerable Part of the volume and weight is wasted. Therefore, the flat structure becomes very uneconomical in this case.

However, the traditional cylindrical structure fuel cells have membrane electrode contact and sealing problems, such as:

CN101587963 proposes a design and manufacturing process of a cylindrical proton exchange membrane fuel cell. The anode is directly fabricated on a cylindrical graphite rod, and the proton exchange membrane and cathode structure are installed by rolling. The cathode uses a tubular current collector and relies on Sealing rings at both ends achieve sealing.

CN105070932A proposes a method for manufacturing a cylindrical proton exchange membrane fuel cell using conductive materials and 3D printing technology. The membrane electrode is prepared by the method of multi-layer coating and curing, and the memory alloy technology is also involved to realize the contact and sealing of the various components of the battery.

The manufacturing process of the solution proposed by CN101587963 is immature, and it has not achieved good sealing, the open circuit voltage is only 0.8V, and the power density is only 8.3mW/cm2. Without solving the contact problem of the current collector, the contact resistance greatly affects the performance of the battery, and the advantages of the cylindrical structure are not exerted.

The solution proposed by CN105070932A mainly relies on 3D printing technology and memory alloy technology, which greatly increases the manufacturing time cost and raw material cost of the product. At the same time, due to the memory properties of memory alloys, it is difficult to maintain a consistent and appropriate contact stress within the temperature range of battery storage and use.

SUMMARY OF THE INVENTION

In order to solve the problems in the prior art, the present invention provides a cylindrical self-breathing fuel cell and an assembly method thereof.

The present invention provides a cylindrical self-breathing fuel cell, comprising an anode current collector, a membrane electrode, a cathode current collector and a tensioning mechanism, wherein the membrane electrode is wound on the anode current collector, and the cathode current collector is wound On the membrane electrode, the tensioning mechanism is tensioned and clamped at the seam of the cathode current collector, so that the cathode current collector is wrapped around and attached to the membrane electrode.

As a further improvement of the present invention, the tensioning mechanism includes a tensioning block assembly, a clamping plate, a clamping plate screw and a tensioning block adjusting screw, the clamping plate is clamped on the cathode current collector by the clamping plate screw, and the tensioning block The adjusting screw is connected with the tensioning block assembly, the tensioning block assembly includes at least two wedge-shaped tensioning blocks that are fitted by inclined surfaces, and the cathode current collector is covered and compressed by the tension of the wedge-shaped tensioning blocks.

As a further improvement of the present invention, the cathode current collector is made of a stainless steel plate with a thickness of 0.1 mm to 0.2 mm, preferably 0.1 mm or 0.2 mm or 0.15 mm.

As a further improvement of the present invention, the anode current collector has a hollow cavity, a hydrogen storage container is installed in the hollow cavity, and the hollow anode structure can be used to place the hydrogen storage container or integrate the hydrogen storage container and the anode.

As a further improvement of the present invention, the anode current collector is made of metal pipes, and the anode current collector is milled with an anode flow channel and an inlet and outlet of the anode flow channel, and the inlet and outlet of the anode flow channel are respectively connected with Intake and outlet lines.

As a further improvement of the present invention, an upper area of the anode current collector is reserved to avoid the joint of the cathode current collector, and the upper area is not provided with an anode flow channel, that is, the anode flow channel does not cover the entire circumference.

As a further improvement of the present invention, an anode side gasket is provided between the anode current collector and the membrane electrode, and a cathode side gasket is provided between the membrane electrode and the cathode current collector.

As a further improvement of the present invention, the anode side gasket is a silicone gasket, and the cathode side gasket is a polytetrafluoroethylene gasket.

The present invention also provides a method for assembling a cylindrical self-breathing fuel cell, comprising the following steps:

S1. Pre-press the membrane electrode and the silicone gasket, and use the adhesiveness of the silicone gasket to attach it to the gasket that comes with the membrane electrode to facilitate assembly;

S2, attach the side of the membrane electrode pre-pressed with the silicone gasket to the anode current collector, and roll it into a cylinder, so that the anode current collector is located inside the membrane electrode;

S3, winding the PTFE gasket on the outside of the membrane electrode;

S4, wrapping the cathode current collector on the outside of the membrane electrode;

S5. Install the splint at the joint of the cathode current collector through the splint screw, and tighten the cathode current collector through the cooperation of the wedge-shaped tension block and the tension block adjustment screw, so that the cathode current collector is wrapped around the membrane electrode and tightened. The plywood screw on the plywood, then remove the wedge-shaped tensioning block and the tensioning block adjusting screw, cut off the excess part on the cathode current collector, and the assembly is completed.

The beneficial effects of the invention are as follows: the problem of membrane electrode contact and sealing of the cylindrical fuel cell is solved, the cell has high reliability, and higher power density is achieved compared with the traditional flat-plate fuel cell.

Description of drawings

FIG. 1 is an exploded schematic view of a cylindrical self-breathing fuel cell of the present invention.

FIG. 2 is a schematic perspective view of a cylindrical self-breathing fuel cell of the present invention.

Figure 3 is a schematic diagram of the contact situation of the membrane electrode of the flat self-breathing battery.

4 is a schematic diagram of the contact situation of the membrane electrodes of a cylindrical self-breathing fuel cell of the present invention.

Figure 5 is a comparison of polarization curves of three different structures of batteries.

Fig. 6 is a polarization curve diagram of a cylindrical self-breathing fuel cell of the present invention under different gas supply amounts.

Figure 7 is a polarization curve diagram of a cylindrical self-breathing fuel cell of the present invention under high humidity and convection.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

As shown in Figures 1 to 2, for a cylindrical self-breathing fuel cell, the anode current collector 3 uses a metal tube, and the flow channel structure is milled and processed, and parallel flow channels or serpentine flow channels can be processed as required. Process (blind) holes in the axial position of the pipe and braze the metal capillary as the inlet and outlet of the flow channel. One end is connected to the silicone hose 2 and the hydrogen cylinder 1 to form the intake pipeline, and the other end is connected to the hose 4 as the exhaust pipeline. For the gasket 5, according to the thickness of the membrane electrode 6, a silicone gasket is used at the anode, and the viscosity and low elastic modulus of the silicone are used to reduce the assembly difficulty and achieve sealing. The gasket material used on the cathode side is polytetrafluoroethylene, which is mainly used for its non-stick and lubricating characteristics, so that the cathode current collector can slip relative to the membrane electrode 6 when it is tensioned, so as to avoid damage to the membrane electrode itself. Belt gasket for better contact and sealing.

When assembling, the membrane electrode 6 and the gasket 5 are pre-pressed first, and the adhesive of the silica gel is used to adhere to the gasket that comes with the membrane electrode 6 to facilitate assembly. First, attach the anode current collector 3 to the side of the membrane electrode silica gel gasket, wind it, and then install the PTFE gasket. Finally, the cathode current collector 7 is wrapped, and the clamping plates 9 and 12 are first installed with the screws 13, and then the tension blocks 8 and 11 are installed, and the tension block screws 10 are adjusted to a suitable strength. Finally, tighten all the screws on the splint, remove the tension block, and cut off the upper part of the battery cathode to complete the battery assembly.

The flow channel of the battery does not cover the entire circumference, and the upper area is reserved to avoid the cathode seam and avoid gas leakage at the seam. The biggest advantage of the battery with this structure is that the tensile force of the cathode thin steel plate is used to realize the contact with the membrane electrode, which can ensure that the stress condition of the cathode structure along the circumferential direction is consistent, and the cathode current collector has only tensile stress on the vertical axial section, almost There is no bending moment. However, the flat plate design will lead to a gradual increase in the bending moment of the end plate from the center to the edge, and even if the cathode thickness of the flat self-breathing battery is increased to 2 mm, good results are not obtained. The cylindrical battery of this design can reduce the thickness of the cathode to 0.1 mm, which can increase the gas convection intensity near the cathode gas diffusion layer, thereby greatly reducing the mass transfer resistance. In addition, the low rigidity of its structure can also be used to correct the machining error by fine-tuning the tension at different positions through the bolts, and further optimize the contact stress distribution. The final contact stress distribution is greatly improved compared with the traditional flat self-breathing battery, as shown in Figures 3 and 4. Show. The cylindrical self-breathing battery of this design has passed the fuel cell sealing test (IEC TS 62282-7-1). The anode is pressurized to 20kPa for 15 minutes and the pressure drop is 3.5kPa, which is less than the standard requirement of 5kPa. The open circuit voltage can reach 0.977V, which proves the excellent sealing effect.

In order to verify the performance improvement brought by the structure, comparative experiments of batteries with different structures were carried out. The experimental test used a five-layer hydrogen-air membrane electrode produced by FuelCellStore, with a total area of 50.41 cm ² . In the actual test, parallel flow channels are used, with a width of 1.2 mm, a depth of 1 mm, and a spacing of 2 mm. Through the previous experiments, the hydrogen flow rate of 400 SCCM was selected as the experimental condition. It can be seen from Figure 5 that the power density of the cylindrical air self-breathing battery is more than double that of the flat self-breathing battery. By setting the hydrogen flow rate reasonably, the maximum power density of the cylindrical battery measured in this experiment can reach 106.2mW/cm ² (measured when the hydrogen flow rate is 100SCCM) as shown in Figure 6. Especially for high humidity or convection conditions, the performance of the battery is significantly improved, as shown in Figure 7. It can be demonstrated that the battery of the present invention can achieve a high power density when used in a daily environment.

The invention designs a cylindrical air self-breathing proton exchange membrane fuel cell, which solves the problem of membrane electrode contact and sealing of the cylindrical structure fuel cell, enables the cell to have high reliability, and achieves high reliability compared with traditional flat-plate fuel cells. higher power density.

In the present invention, a thin stainless steel plate with a thickness of 0.1 mm is used as the current collector in the cathode, and the uniform contact between the current collector and the membrane electrode is realized by using the cylindrical structure of the substrate through tensioning at the end. Excellent contact stress distribution and sealing can be achieved by utilizing tension rather than structural rigidity. In addition, the hollow structure of the anode can also accommodate a hydrogen storage container, which further realizes a compact design and greatly increases the power density of the battery.

Through experimental comparison and verification, the design of the present invention can achieve good contact stress distribution and edge sealing effect for gaskets of different thicknesses, and does not need to precisely control the thickness of the gasket like a flat-panel battery. For the output power test, up to three times the output power of the flat self-breathing fuel cell. Under the same output power, the weight of the cylindrical self-breathing battery is only 1/6 of the traditional flat-plate self-breathing battery, and the volume is only 1/10.

Compared with other prior art, the advantages of the present invention are as follows:

(1) Compared with the traditional flat-plate self-breathing battery, the power density of the membrane electrode surface is more than doubled, and the open circuit voltage is increased by 0.05V to 0.977V. At the same time, the weight of the battery is only 1/6 of the flat-type self-breathing battery, and the volume is only 1/10.

(2) The sealing scheme of the battery is innovatively designed, and the anode adopts a flow channel distribution that does not completely cover the entire circumference. Electricity is generated by directly using purchased finished membrane electrodes. By applying tension to the cathode current collector to make it wrap around the cylindrical anode body to achieve sealing, the sealing effect is good, the contact is uniform, and the contact resistance is greatly reduced.

(3) The thickness of the cathode is greatly reduced, and the mass transfer resistance can be reduced under the condition of equivalent electrical conductivity.

(4) The hollow structure can be used to place the hydrogen storage container, which further improves the overall power density.

The present invention designs a cylindrical air self-breathing proton exchange membrane fuel cell with a novel sealing principle, and compares and tests the performance difference between the cylindrical self-breathing cell and the traditional flat-plate self-breathing cell (using the same membrane electrode). The present invention can directly use the mass-produced commercial five (seven)-layer membrane electrode assemblies, and avoids the complicated process of attaching the membrane electrode assemblies on the cylindrical substrate by means of self-processing.

The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be considered that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deductions or substitutions can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (7)

1. A method of assembling a cylindrical self-breathing fuel cell, comprising: providing a cylindrical self-breathing fuel cell characterized by: the membrane electrode is wound on the anode current collector, the cathode current collector is wound on the membrane electrode, and the tensioning mechanism is tensioned and clamped at the joint of the cathode current collector to enable the cathode current collector to be wound and attached on the membrane electrode;

the tensioning mechanism comprises a tensioning block assembly, a clamping plate screw and a tensioning block adjusting screw, the clamping plate is clamped on the cathode current collector through the clamping plate screw, the tensioning block adjusting screw is connected with the tensioning block assembly, and the tensioning block assembly comprises at least two wedge-shaped tensioning blocks which are attached through inclined planes;

the assembly steps of the cylindrical self-breathing fuel cell are as follows:

s1, prepressing the membrane electrode and the silica gel gasket, and attaching the silica gel gasket to a gasket carried by the membrane electrode by utilizing the self viscosity of the silica gel gasket so as to be convenient for assembly;

s2, attaching the side, pre-pressed with the silica gel gasket, of the membrane electrode to an anode current collector, and winding the anode current collector into a cylinder so that the anode current collector is positioned on the inner side of the membrane electrode;

s3, winding the polytetrafluoroethylene gasket on the outer side of the membrane electrode;

s4, wrapping the cathode current collector on the outer side of the membrane electrode;

s5, installing the clamping plate at the joint of the cathode current collector through the clamping plate screw, tightening the cathode current collector through the matching of the wedge-shaped tensioning block and the tensioning block adjusting screw, enabling the cathode current collector to be wrapped and attached to the membrane electrode, tightening the clamping plate screw on the clamping plate, then detaching the wedge-shaped tensioning block and the tensioning block adjusting screw, cutting off redundant parts on the cathode current collector, and completing assembly.

2. The method of assembling a cylindrical self-breathing fuel cell of claim 1, wherein: the cathode current collector is made of a stainless steel plate with the thickness of 0.1mm to 0.2 mm.

3. The method of assembling a cylindrical self-breathing fuel cell of claim 1, wherein: the anode current collector is provided with a hollow cavity, and the hollow cavity is provided with a hydrogen storage container.

4. The method of assembling a cylindrical self-breathing fuel cell of claim 1, wherein: the positive pole mass flow body adopts metal tubular product to make, there are the import and export of positive pole runner and positive pole runner through milling process on the positive pole mass flow body, the import and export of positive pole runner is connected with air inlet pipeline and air outlet pipeline respectively.

5. The method of assembling a cylindrical self-breathing fuel cell of claim 4, wherein: the anode current collector is reserved with an upper area to avoid the joint of the cathode current collector, and the upper area is not provided with an anode flow passage.

6. The method of assembling a cylindrical self-breathing fuel cell of claim 1, wherein: an anode side gasket is arranged between the anode current collector and the membrane electrode, and a cathode side gasket is arranged between the membrane electrode and the cathode current collector.

7. The method of assembling a cylindrical self-breathing fuel cell of claim 6, wherein: the anode side gasket is a silica gel gasket, and the cathode side gasket is a polytetrafluoroethylene gasket.

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