A liquid flow battery press mounting heat preservation system and a press mounting method

Abstract

The application discloses a kind of liquid flow battery press mounting heat preservation systems and press mounting methods, purpose is to solve the technical problem that existing electric pile sealing method makes electric pile air tightness be poorer, technical scheme is: heat preservation system includes electric pile to be pressed, hot air machine, total hot air pipe, positive and negative electrode inlet and outlet pipe, heat preservation cover, warm air machine and control system, electric pile to be pressed is placed in heat preservation cover inside, hot air machine is set in the outside of heat preservation cover one side, one end of total hot air pipe is connected with hot air machine, other end is communicated with the inside of heat preservation cover, warm air machine is set on the side wall of heat preservation cover and the air outlet of warm air machine is communicated with the inside of heat preservation cover, one end of positive and negative electrode inlet and outlet pipe is connected with the import and export of press mounting electric pile, other end of positive and negative electrode inlet pipe is inserted into total hot air pipe, hot air machine and warm air machine are electrically connected with control system. Press mounting method is first pre-pressing, then heating preservation, in repeatedly pressing 12h, the air tightness, coulomb efficiency and energy efficiency of electric pile of the application have greater promotion.

Description

Technical Field

[0001] This invention belongs to the field of vanadium redox flow battery technology, and particularly relates to a flow battery press-fitting and heat preservation system and press-fitting method. Background Technology

[0002] Flow batteries are energy storage devices used in conjunction with renewable energy generation systems such as photovoltaic power plants and wind farms, as well as power user systems such as microgrids, for peak shaving, valley filling, frequency regulation, and voltage regulation on the grid side. The key feature of flow battery technology is that the stack serves solely as the site of electrochemical reactions. After the charge-discharge reaction, electrical energy is converted into chemical energy and stored as a liquid in the electrolyte. The power unit stack and the capacity unit electrolyte storage tank are independent of each other, forming a circulation system through pipelines and pumps. Each flow battery stack consists of several battery cells connected in series.

[0003] In existing technologies, the outer end plate of the fuel cell stack assembly structure is generally pressed onto the fuel cell elements using fasteners. The encapsulation frame plate is equipped with a labyrinth seal structure, or a seal is achieved between the encapsulation frame plates or between the outer perimeter of the frame and the sealing plate via laser fusion welding. While this method achieves a seal, it requires a special structure at the weld joint and a dedicated welding mold. As the number of stacked layers and accumulated errors increase, the method becomes increasingly difficult to control, resulting in a high scrap rate. Furthermore, the significant heat generated during welding can cause varying degrees of deformation to the frame, bipolar plates, and membrane modules, thereby affecting the fluid flow distribution within the fuel cell stack and ultimately impacting its performance. Summary of the Invention

[0004] The purpose of this invention is to provide a flow battery press-fitting and insulation system and a press-fitting method to solve the above-mentioned technical problems.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A flow battery stack press-fit insulation system includes a stack to be press-fitted, a hot air blower, a main hot air duct, several positive and negative electrode inlet / outlet pipes, an insulation cover, a heater, and a control system. The stack to be press-fitted is placed inside the insulation cover. The hot air blower is located on the outside of the insulation cover. One end of the main hot air duct is connected to the hot air blower, and the other end is connected to the inside of the insulation cover. The heater is located on the side wall of the insulation cover, and its outlet is connected to the inside of the insulation cover. One end of each of the several positive and negative electrode inlet / outlet pipes is connected to the inlet and outlet of the press-fitted stack. The other end of the positive and negative electrode inlet / outlet pipes extends into the main hot air duct. Both the hot air blower and the heater are electrically connected to the control system.

[0007] Preferably, a hot melt film is adhered to both sides of the electrode integrated frame of the stack to be pressurized.

[0008] Preferably, the thickness of the hot melt film is 0.15-0.25 mm.

[0009] Preferably, the inner wall of the heat insulation cover is provided with a heat insulation cotton lining.

[0010] Preferably, the insulation cover is equipped with several temperature sensors around its perimeter, and the temperature sensors are electrically connected to the control system.

[0011] A method for press-fitting a flow battery stack includes the following steps:

[0012] S1. Pre-compression: Place the stack to be pressurized onto the moving station of the press, pre-compress the stack to be pressurized with 60-80 tons of pressure for 30 minutes, and tighten it with a wrench at the same time.

[0013] S2. Heating and heat preservation: After the pre-compression is completed, the battery stack to be pressurized is placed in the heat preservation cover. The positive and negative inlet pipes are inserted into the main hot air pipe. The valves on the positive and negative outlet pipes are opened. The hot air blower is turned on to heat the positive and negative inlet pipes to 50-55℃. Then the warm air blower is turned on to heat to 50-55℃, so that the temperature inside the heat preservation cover is kept constant for 4-5 hours.

[0014] S3. Pressing: After the heat preservation is completed, place the fuel cell stack to be pressed on the press and press it with 60 tons of pressure, while tightening it at the same time, for 1 hour.

[0015] S4. Adjust the pressure of the press to 80 tons, press and tighten the bolts every 1 hour, and repeat the pressing for 12 hours.

[0016] Preferably, the pressure range in step S4 is 75-80 tons.

[0017] The beneficial effects of this invention are:

[0018] 1. Before the fuel cell stack of the present invention is press-fitted, it is first kept at 50℃-55℃, which greatly improves the airtightness, coulombic efficiency and energy efficiency of the fuel cell stack. After a certain period of operation, no performance degradation has been observed.

[0019] 2. In this invention, a hot melt film is adhered to both sides of the integrated electrode frame of the fuel cell stack. The hot melt film softens after being heated to 50 degrees Celsius, has good fluidity, and undergoes rapid creep under pressure. The film side of the fuel cell stack frame plate expands due to heat, and the hot melt film is redistributed in the sealing rib surface of the frame plate and the overflow groove, so that the fuel cell stack frame plates are pressed more tightly together, which greatly improves the sealing performance of the liquid flow fuel cell stack. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the press-fit insulation system of the present invention;

[0021] Figure 2 This is a schematic diagram of the exploded structure of the fuel cell stack of the present invention;

[0022] Reference numerals in the attached drawings: 1. Electrode frame; 2. Electrode stack to be pressurized; 3. Hot air blower; 4. Main hot air pipe; 5. Inlet and outlet liquid pipes; 6. Insulation cover; 7. Warm air blower. Detailed Implementation

[0023] To make the technical means, creative features, achieved objectives, and effects of this invention easier to understand, the invention is further described below with reference to specific embodiments and accompanying drawings. However, the following embodiments are merely preferred embodiments of this invention and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are all within the protection scope of this invention.

[0024] Specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0025] A flow battery stack press-fit insulation system includes a stack to be press-fitted 2, a hot air blower 3, a main hot air duct 4, several positive and negative electrode inlet / outlet pipes 5, an insulation cover 6, a heater 7, and a control system. The electrode frame 1 of the stack to be press-fitted 2 has a 0.2mm thick hot melt film adhered to both sides. The stack to be press-fitted 2 is placed inside the insulation cover 6, which has an inner lining of insulating cotton. Several temperature sensors are arranged around the inside of the insulation cover 6, and these temperature sensors are electrically connected to the control system. The blower 3 is located on the outside of the insulation cover 6. One end of the main hot air pipe 4 is connected to the blower 3, and the other end is connected to the inside of the insulation cover 6. The heater 7 is located on the side wall of the insulation cover 6, and the air outlet of the heater 7 is connected to the inside of the insulation cover 6. One end of each of the plurality of positive and negative inlet and outlet liquid pipes 5 is connected to the inlet and outlet of the press-fitted fuel cell stack 2. The other end of the positive and negative inlet liquid pipes 5 extends into the main hot air pipe 4. Both the blower 3 and the heater 7 are electrically connected to the control system.

[0026] The thickness of the hot melt film can also be any value between 0.15-0.25 mm;

[0027] A method for press-fitting a flow battery stack includes the following steps:

[0028] S1. Pre-compression: Place the fuel cell stack 2 to be press-loaded onto the moving station of the press, and pre-compress the fuel cell stack 2 with a pressure of 60-80 tons for 30 minutes, while simultaneously tightening it with a wrench.

[0029] S2. Heating and heat preservation: After the pre-compression is completed, the stack to be pressurized 2 is placed in the heat preservation cover 6. The positive and negative inlet pipes in the positive and negative inlet and outlet pipes 5 are inserted into the main hot air pipe 4. The valves on the positive and negative outlet pipes are opened. The hot air blower 3 is turned on to heat the positive and negative inlet pipes to 50°C. Then the warm air blower 7 is turned on to heat to 50°C, so that the temperature inside the heat preservation cover 6 is kept constant for 4.5 hours.

[0030] S3. Pressing: After the heat preservation is completed, place the fuel cell stack 2 to be pressed on the press and press it with 60 tons of pressure, while tightening it at the same time, for 1 hour.

[0031] S4. Adjust the pressure of the press to 80 tons, press and tighten the bolts every 1 hour, and repeat the pressing for 12 hours.

[0032] The heating temperature in step S2 can be any value between 50-55℃, and the heat preservation time of the heat preservation cover 6 can be any value between 4-5h.

[0033] The pressure value in step S4 can also be any value between 75 and 80 tons.

[0034] To verify the effectiveness of the present invention, three sets of tests were conducted to test the sealing performance of the press-fitted fuel cell stack of the present invention.

[0035] The experimental fuel cell stack consists of 64 stacked plates, with the plate and frame made of polyethylene and glass fiber.

[0036] Leakage test procedure: During the external leakage test, a compressed air hose with a digital pressure gauge was connected to the inlet of the fuel cell stack. Compressed air was introduced into the three fuel cell stacks, and the pressure was set to 3.5 kg / cm². 2 After maintaining the pressure for 60 minutes, the final pressure gauge readings on the air hoses of each fuel cell stack were observed. The results showed that the final pressure value for external leakage tightness did not change.

[0037] Internal leakage test: Connect a compressed air hose with a digital pressure gauge to the inlet of the fuel cell stack, and fill the three fuel cell stacks with compressed air at a pressure of 0.3 kg / cm². 2 After maintaining the pressure for 30 minutes, the final pressure gauge readings on the air hoses of each fuel cell stack were observed. The results showed that the final pressure value for internal leakage tightness did not change.

[0038] Electrochemical performance testing: Using an electrolyte containing 1.7 mol / L VOSO4, the average voltage efficiency was 83.34% and the average energy efficiency was 80.17% under constant power charge and discharge conditions of 32 kW. Testing was conducted using an electrolyte containing 1.7 mol / L VOSO4 at a charging cutoff voltage of 1.55 V and a discharging cutoff voltage of 1.0 V. After a certain period of continuous operation, the stack was tested, and the data are shown in Table 1.

[0039] Table 1: Experimental Test Results of the Experimental Stack

[0040]

[0041] The test results showed that the control sample fuel cell stack, without an insulation system, was directly pressed into the press, reaching a pressing height of 262mm, which was difficult to achieve the predetermined height. The appearance of excess adhesive was not obvious, and the pressing time reached 24 hours. After a certain period of operation, slight electrolyte leakage occurred. In contrast, the experimental fuel cell stack, after being pressed into the press using a 50℃ or 55℃ insulation system, reached the predetermined pressing height. Obvious excess adhesive was observed, and the encapsulation time was 12 hours. This improved the pressing efficiency of the fuel cell stack, and the operational sealing reliability, coulombic efficiency, and energy efficiency were all significantly improved. No electrolyte leakage or performance degradation was observed after a certain period of operation.

[0042] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0043] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A flow battery stack press-fit insulation system, characterized in that, The device includes a fuel cell stack to be pressurized (2), a hot air blower (3), a main hot air pipe (4), several positive and negative electrode liquid inlet and outlet pipes (5), an insulation cover (6), a heater (7), and a control system. The fuel cell stack to be pressurized (2) is placed inside the insulation cover (6). The hot air blower (3) is located on the outside of the insulation cover (6). One end of the main hot air pipe (4) is connected to the hot air blower (3), and the other end is connected to the inside of the insulation cover (6). The heater (7) is located on the side wall of the insulation cover (6), and the air outlet of the heater (7) is connected to the inside of the insulation cover (6). One end of each of the several positive and negative electrode liquid inlet and outlet pipes (5) is connected to the inlet and outlet of the pressurized fuel cell stack (2). The other end of the positive and negative electrode liquid inlet pipes (5) extends into the main hot air pipe (4). The hot air blower (3) and the heater (7) are both electrically connected to the control system. Among them, hot melt film is attached to both sides of the electrode integrated frame (1) of the battery stack (2) to be pressed, and the thickness of the hot melt film is 0.15-0.25mm; before the battery stack (2) to be pressed is pressed, it is kept at 50℃-55℃. During the heat preservation, the battery stack (2) to be pressed after pre-pressing is placed in the heat preservation cover (6). The positive and negative electrode inlet pipes (5) are inserted into the main hot air pipe (4). The valves on the positive and negative electrode outlet pipes are opened, and the hot air blower (3) is turned on to heat the positive and negative electrode inlet pipes to 50-55℃. Then the warm air blower (7) is turned on to heat to 50-55℃, so that the temperature inside the heat preservation cover (6) is kept constant for 4-5 hours.

2. The flow battery stack press-fit insulation system according to claim 1, characterized in that, The inner wall of the heat insulation cover (6) is lined with heat insulation cotton.

3. The flow battery stack press-fit insulation system according to claim 1, characterized in that, The insulation cover (6) is equipped with several temperature sensors around its interior, and the temperature sensors are electrically connected to the control system.

4. A pressing method using the flow battery stack pressing and insulation system according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Pre-compression: Place the stack to be pressurized (2) on the moving station of the press and pre-compress it with a pressure of 60-80 tons for 30 minutes, while using a wrench to tighten it. S2, heating and heat preservation: After the pre-compression is completed, the stack to be pressurized (2) is placed in the heat preservation cover (6). The positive and negative electrode inlet pipes (5) are inserted into the main hot air pipe (4). The valves on the positive and negative electrode outlet pipes are opened. The hot air blower (3) is turned on to heat the positive and negative electrode inlet pipes to 50-55℃. Then the warm air blower (7) is turned on to heat to 50-55℃, so that the temperature inside the heat preservation cover (6) is kept constant for 4-5 hours. S3, Pressing: After the heat preservation is completed, place the stack (2) to be pressed on the press and press it with 60 tons of pressure, while tightening it at the same time, for 1 hour; S4. The pressure range of the press is 75-80 tons. Adjust the pressure of the press to 80 tons, press and tighten the bolts every 1 hour, and repeat the pressing for 12 hours.

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