Safety valve protective film integrated with pressure, temperature and liquid leakage sensor

Abstract

The utility model relates to a safety valve protective film integrated with a pressure, temperature and liquid leakage sensor, which comprises a bonding layer, an isolation layer, a sensing layer and a packaging layer which are sequentially attached and connected from bottom to top, and the sensing layer is provided with a safety valve liquid leakage sensor and a flexible film type pressure and temperature composite sensor. Whether electrolyte flows out of the safety valve or not and the pressure and temperature values of the safety valve in the whole charging and discharging process of the lithium battery can be monitored in real time through the safety valve leakage sensor and the flexible film type pressure and temperature composite sensor, and the conditions are used as early warning judgment conditions for thermal runaway of the battery.

Description

Technical Field

[0001] The utility model belongs to the technical field of battery detection, and particularly relates to a safety valve protective film with an integrated pressure and temperature leakage sensor. Background Art

[0002] Lithium batteries have the advantages of light weight, small size, high energy density and long service life. In recent years, they have been widely used in new energy vehicles and large-scale energy storage technology with electricity as the core. Large-scale energy storage technology can promote the development of smart grids, alleviate the volatility of new energy, and has a bright development prospect. It is currently the most widely used energy storage technology. Lithium battery energy storage systems are usually container-type, which are a collection of units composed of several lithium-ion battery clusters and electrical equipment and placed in a confined space. Because the entire system is relatively closed and heat is not easy to dissipate, lithium batteries are prone to heat accumulation during operation, especially under extreme conditions, such as overcharging, short circuit, etc. The large amount of heat accumulated inside the battery will cause the battery to thermally run away, thereby causing fire and explosion accidents. The existing safety protection facilities cannot completely prevent the occurrence of fire accidents in lithium battery energy storage systems.

[0003] In order to ensure the safe and efficient operation of the battery, the battery status is mainly detected and managed through the battery management module (BMS). At present, the BMS mainly monitors the working status of the lithium battery in real time by collecting information such as the voltage, temperature, and discharge rate of the battery body, so as to judge thermal runaway. A safety valve is set on the top of the lithium battery shell. When the battery has thermal runaway, the internal compounds react with heat to produce a large amount of gas. When the internal pressure of the lithium battery rises to exceed the rated value, the safety valve quickly ruptures to release the internal pressure and heat, reducing the risk of explosion. The temperature and pressure changes inside the lithium battery are one of the most direct and effective means to judge the battery charging and discharging and thermal runaway. Since the built-in sensors of lithium batteries will affect the energy density and capacity of the battery, the sensors outside the battery are currently used to manage and analyze the health of the battery.

[0004] At present, in the existing technology, the safety valve detection sensor monitors whether the safety valve is open and the NTC temperature sensor (negative temperature coefficient thermistor) monitors the temperature of the lithium battery. Among them, the NTC temperature sensor is a rigid sensor, which is larger and cannot be bent compared with the flexible film sensor, making it inconvenient to detect the safety valve, and there is also a lack of pressure sensors to monitor the pressure state of the lithium battery in real time. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide a safety valve protective film with an integrated pressure and temperature leakage sensor. The safety valve leakage sensor and the flexible film pressure and temperature composite sensor can be used to monitor in real time whether the electrolyte flows out of the safety valve and the pressure and temperature values ​​of the lithium battery on the safety valve during the whole charging and discharging process, so as to serve as early warning conditions for battery thermal runaway.

[0006] The utility model provides a safety valve protective film with an integrated pressure temperature leakage sensor, which comprises an adhesive layer, an insulating layer, a sensing layer and a packaging layer which are sequentially connected from bottom to top. The sensing layer is provided with a safety valve leakage sensor and a flexible film type pressure temperature composite sensor.

[0007] Preferably, the safety valve leakage sensor is integrated in the packaging layer by 3D printing, and the safety valve leakage sensor includes a first detection line and a second detection line, both of which are made of conductive materials and are not connected to each other; the first detection line includes a first main detection line terminal, a first main detection line and several first branch detection lines connected to the first main detection line; the second detection line includes a second main detection line terminal, a second main detection line and several second branch detection lines connected to the second main detection line; a detection area is provided in the middle of the packaging layer, and the first branch detection lines and the second branch detection lines are correspondingly staggered in the detection area, in the shape of open rings that are not connected to each other.

[0008] Preferably, the flexible thin film pressure-temperature composite sensor comprises two electrode wires, electrode terminals and a sensitive material connected to the tails of the two electrode wires, the sensitive material is a piezoelectric polymer PVDF-TrFE material, the sensitive material is located at the center of the detection area, the electrode wires do not intersect with the first detection wire and the second detection wire, and are located between the first main detection wire and the second main detection wire; the front end areas of the two electrode wires in the flexible thin film pressure-temperature composite sensor are fixed in the packaging layer, and the tail area hangs down due to the gravity of the sensitive material, and the first main detection wire terminal, the second main detection wire terminal and the electrode terminal are all located outside the detection area.

[0009] Preferably, the sensing layer is further provided with an annular fixing member, which fixedly connects the first main detection line and the second main detection line and wraps the first branch detection line and the second branch detection line.

[0010] Preferably, the adhesive layer consists of an annular film.

[0011] Preferably, the insulating layer is composed of an annular insulating plate and a special-shaped insulating plate matching the flexible film type pressure-temperature composite sensor, one end of the special-shaped insulating plate is located inside the annular insulating plate and is in a downward hanging state, and the other end is located outside the annular insulating plate and is in a horizontal state; the flexible film type pressure-temperature composite sensor is located above the special-shaped insulating plate, the annular fixing piece is located above the annular insulating plate, and the annular film is located below the annular insulating plate.

[0012] Preferably, the encapsulation layer is composed of an elliptical encapsulation plate and a rectangular encapsulation plate, one end of the rectangular encapsulation plate is connected to the side of the elliptical encapsulation plate, the elliptical encapsulation plate is located above the annular fixing piece, and the rectangular encapsulation plate is located above the front end area of ​​the first main detection line, the first main detection line, and the electrode line.

[0013] Preferably, the annular film, the annular isolation plate, the annular fixing member and the elliptical packaging plate have the same outer contours and are sequentially fitted and connected, and the annular fixing member, the annular film and the annular isolation plate have the same width.

[0014] Preferably, the overall thickness of the adhesive layer is 0.2 mm; the overall thickness of the insulating layer is 10-40 μm; and the overall thickness of the encapsulation layer is 20-40 μm.

[0015] The utility model has the following technical effects:

[0016] 1. The safety valve leakage sensor and the flexible film pressure-temperature composite sensor can monitor in real time whether the electrolyte flows out of the safety valve and the pressure and temperature of the lithium battery during the whole process of charging and discharging, which can be used as the early warning condition for battery thermal runaway;

[0017] 2. Since the first branch detection line in the first detection line and the second branch detection line in the second detection line are staggered, when the safety valve is in a closed state, the first detection line and the second detection line are not connected to each other, and the resistance at both ends of the safety valve leakage sensor is infinite; when the battery safety valve is opened, the electrolyte inside the battery sprays out from the safety valve and adheres to the safety valve leakage sensor, connecting the first detection line and the second detection line, and the resistance at both ends of the safety valve leakage sensor is close to zero. Therefore, by detecting the potential difference or current change between the first detection line and the second detection line of the safety valve leakage sensor, it is possible to monitor in real time whether the safety valve is opened;

[0018] 3. Since the sensitive material in the flexible film pressure-temperature composite sensor hangs down due to gravity and is attached to the battery safety valve, it is in indirect contact with the battery safety valve through the isolation layer. The sensitive material senses the state changes of the pressure and temperature of the battery safety valve, and transmits the signal through two electrode wires. Since the sensitive material is a piezoelectric polymer PVDF-TrFE material, it has the advantages of light weight, high sensitivity, large range, good flexibility, and sensitivity to pressure and temperature, and can quickly realize real-time monitoring of lithium battery temperature and pressure.

[0019] 4. It is tightly attached to the lithium battery safety valve through the adhesive layer, without the need for additional adhesives, and is easy and quick to use;

[0020] 5. A closed cavity is formed by the bonding layer, the insulating layer, the sensing layer, the encapsulation layer and the lithium battery safety valve, which can minimize the pollution during the production, transportation, installation and use, enhance the sensitivity of sensing the status of the lithium battery safety valve, and thus effectively improve the measurement accuracy and speed of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is an exploded view of a safety valve protective film with an integrated pressure and temperature leakage sensor;

[0022] Figure 2 A bottom view of a safety valve protective film with an integrated pressure and temperature leakage sensor;

[0023] Figure 3 A schematic diagram of a sensing layer of a safety valve protective film with an integrated pressure and temperature leakage sensor;

[0024] Figure 4 A schematic diagram of a safety valve protective film with an integrated pressure temperature leakage sensor for a battery housing top cover;

[0025] Figure 5 A top view of a safety valve protective film with an integrated pressure temperature leakage sensor for a battery housing top cover;

[0026] Figure 6 A schematic diagram of placing a safety valve protective film with an integrated pressure temperature leakage sensor on a safety valve;

[0027] Figure 7 The present invention is a cross-sectional view of a safety valve protective film with an integrated pressure and temperature leakage sensor for use on a battery housing top cover.

[0028] In the figure: 1. Adhesive layer; 11. Detection area; 2. Insulation layer; 21. Annular isolation plate; 22. Special-shaped isolation plate; 3. Sensing layer; 4. Packaging layer; 5. Safety valve leakage sensor; 51. First main detection line terminal; 52. First main detection line; 53. First branch detection line; 54. Second main detection line terminal; 55. Second main detection line; 56. Second branch detection line; 6. Flexible film pressure-temperature composite sensor; 61. Electrode line; 62. Electrode terminal; 63. Sensitive material; 7. Annular fixing piece. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model is described in detail below with reference to the accompanying drawings.

[0030] like Figure 1 , Figure 2 As shown, a safety valve protective film with an integrated pressure temperature leakage sensor comprises an adhesive layer 1, an insulating layer 2, a sensing layer 3, and a packaging layer 4 which are sequentially connected from bottom to top, and the sensing layer 3 is provided with a safety valve leakage sensor 5 and a flexible film type pressure temperature composite sensor 6. The safety valve leakage sensor 5 and the flexible film type pressure temperature composite sensor 6 can be used to monitor in real time whether the electrolyte flows out of the safety valve and the pressure and temperature values ​​of the lithium battery during the whole process of charging and discharging, which can be used as early warning conditions for battery thermal runaway.

[0031] The safety valve leakage sensor 5 is integrated into the packaging layer 4 by 3D printing. The safety valve leakage sensor 5 includes a first detection line and a second detection line. The first detection line and the second detection line are both made of conductive materials and are not connected to each other. The first detection line includes a first main detection line 52 terminal 51, a first main detection line 52 and a plurality of first branch detection lines 53 connected to the first main detection line 52. The second detection line includes a second main detection line 55 terminal 54, a second main detection line 55 and a plurality of second branch detection lines 56 connected to the second main detection line 55. A detection area 11 is provided in the middle of the packaging layer 4. The first branch detection line 53 and the second branch detection line 56 are correspondingly staggered and distributed in the detection area 11, forming an open ring shape that is not connected to each other. Since the first branch detection line 53 in the first detection line and the second branch detection line 56 in the second detection line are staggered, when the safety valve is in a closed state, the first detection line and the second detection line are not connected to each other, and the resistance at both ends of the safety valve leakage sensor 5 is infinite; when the battery safety valve is opened, the electrolyte inside the battery sprays out from the safety valve and adheres to the safety valve leakage sensor 5, connecting the first detection line and the second detection line, and the resistance at both ends of the safety valve leakage sensor 5 is close to zero. Therefore, by detecting the potential difference or current change between the first detection line and the second detection line of the safety valve leakage sensor 5, it is possible to monitor in real time whether the safety valve is opened.

[0032] The flexible thin film pressure-temperature composite sensor 6 includes two electrode wires 61, electrode terminals 62 and a sensitive material 63 connected to the tails of the two electrode wires 61. The sensitive material 63 is a piezoelectric polymer PVDF-TrFE material. The sensitive material 63 is located at the center of the detection area 11. The electrode wires 61 do not intersect with the first detection wire and the second detection wire, and are located between the first main detection wire 52 and the second main detection wire 55. The front end areas of the two electrode wires 61 in the flexible thin film pressure-temperature composite sensor 6 are fixed in the packaging layer 4, and the tail areas hang down due to the gravity of the sensitive material 63. Since the sensitive material 63 in the flexible film pressure-temperature composite sensor 6 hangs down due to gravity, it is in indirect contact with the battery safety valve through the insulation layer 2, and the state changes of the pressure and temperature of the battery safety valve are sensed by the sensitive material 63, and the signal is transmitted through the two electrode wires 61; since the sensitive material 63 is a piezoelectric polymer PVDF-TrFE material, it has the advantages of light weight, high sensitivity, large measuring range, good flexibility, sensitivity to pressure and temperature, etc., and can quickly realize real-time monitoring of the temperature and pressure of the lithium battery.

[0033] The first main detection line 52 terminal 51, the second main detection line 55 terminal 54, and the electrode terminal 62 are all located outside the detection area 11. The first main detection line 52 terminal 51, the second main detection line 55 terminal 54, and the electrode terminal 62 are all used for external wiring.

[0034] The sensing layer 3 is further provided with an annular fixing member 7 , which is fixedly connected to the first main detection line 52 and the second main detection line 55 , and wraps the first branch detection line 53 and the second branch detection line 56 .

[0035] The adhesive layer 1 is composed of an annular film, and is tightly attached to the lithium battery safety valve through the adhesive layer, without the need for additional adhesive, and is convenient and quick to use.

[0036] The insulating layer 2 is composed of an annular insulating plate 21 and a special-shaped insulating plate 22 matching the flexible film type pressure-temperature composite sensor 6. One end of the special-shaped insulating plate 22 is located inside the annular insulating plate 21 and is in a downward hanging state, and the other end is located outside the annular insulating plate 21 and is in a horizontal state; the flexible film type pressure-temperature composite sensor 6 is located above the special-shaped insulating plate 22, the annular fixing member 7 is located above the annular insulating plate 21, and the annular film is located below the annular insulating plate 21.

[0037] The encapsulation layer 4 is composed of an elliptical encapsulation plate and a rectangular encapsulation plate, one end of the rectangular encapsulation plate is connected to the side of the elliptical encapsulation plate, the elliptical encapsulation plate is located above the annular fixing member 7, and the rectangular encapsulation plate is located above the front end area of ​​the first main detection line 52, the first main detection line 52, and the electrode line 61.

[0038] The annular film, the annular isolation plate 21, the annular fixing member 7, and the elliptical packaging plate have the same outer contours and are sequentially fitted and connected. The annular fixing member 7, the annular film, and the annular isolation plate 21 have the same width.

[0039] The overall thickness of the adhesive layer 1 is 0.2 mm. The adhesive layer 1 is made of a film material with good air tightness, such as epoxy resin or rubber. Since the height of the safety valve protective film pasted on the top of the battery shell is 0.2 mm, the thickness of the adhesive layer 1 needs to be maintained at 0.2 mm, so that the four leads of the first main detection line 52, the second main detection line 55, and the two electrode lines 61 in the sensing layer 3 can be led out without affecting the sealing between the battery shell and the safety valve protective film.

[0040] The overall thickness of the insulating layer 2 is 10-40 μm. The insulating layer 2 is made of corrosion-resistant and high-temperature-resistant flexible materials such as ETFE, PVDF, PET, PP, PI or polyparaxylene. The function of the insulating layer 2 is to press and insulate the flexible film-type pressure-temperature composite sensor 6 and its electrodes. In order to ensure the sensitivity of the flexible film-type pressure-temperature composite sensor 6, the thickness of the insulating layer 2 needs to be controlled within 10-40 μm.

[0041] The overall thickness of the encapsulation layer 4 is 20-40 μm. The encapsulation layer 4 is made of corrosion-resistant and high-temperature-resistant flexible materials such as ETFE, PVDF, PET, PP, PI or polyparaxylene.

[0042] The working principle of a safety valve protective film with an integrated pressure and temperature leakage sensor is:

[0043] The safety valve protection film of the present application is tightly attached to the lithium battery safety valve through an adhesive layer to form a closed cavity with the lithium battery safety valve. When the safety valve is in a closed state, the first detection line and the second detection line are not connected to each other. At this time, the resistance at both ends of the safety valve leakage sensor 5 is infinite; when the battery safety valve is opened, the electrolyte inside the battery is sprayed out from the safety valve and adheres to the safety valve leakage sensor 5, connecting the first branch detection line 53 in the first detection line and the second branch detection line 56 in the second detection line, and the resistance at both ends of the safety valve leakage sensor 5 is close to zero. Therefore, by detecting the potential difference or current change between the first detection line and the second detection line of the safety valve leakage sensor 5, it is possible to monitor in real time whether the safety valve is open.

[0044] Since the sensitive material 63 in the flexible film pressure-temperature composite sensor 6 droops downward due to gravity, it is in indirect contact with the battery safety valve through the isolation layer 2. The sensitive material 63 senses the state changes of the pressure and temperature of the battery safety valve, and the signal is transmitted through the two electrode wires 61. The pressure monitoring principle is the piezoelectric effect: when the external force acts on the sensor, the internal lattice of the sensitive material 63 is deformed, resulting in the separation of the positive and negative charges inside. The positive and negative charges are respectively concentrated on the surface of the material to form a potential difference, and the voltage signal is output. The temperature monitoring principle is the pyroelectric effect: the residual polarization intensity of the material changes with the change of temperature, and free charges appear on the upper and lower surfaces of the film to form an electric field, and the voltage signal is output. The piezoelectric signal caused by the pressure change is a pulse, and the pyroelectric response signal caused by the temperature has a certain delay. Therefore, the pressure and temperature signals can be separated by an oscilloscope and peak separation software, thereby realizing real-time monitoring of the temperature and pressure of the lithium battery.

[0045] The embodiments described above are only descriptions of the preferred methods of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the protection scope determined by the claims of the present invention.

Claims

1. A safety valve protective film with an integrated pressure and temperature leakage sensor, characterized in that: It comprises an adhesive layer, an insulating layer, a sensing layer and a packaging layer which are sequentially connected from bottom to top. The sensing layer is provided with a safety valve leakage sensor and a flexible film type pressure and temperature composite sensor.

2. The safety valve protective film with integrated pressure and temperature leakage sensor according to claim 1, characterized in that: The safety valve leakage sensor is integrated in the packaging layer by 3D printing. The safety valve leakage sensor includes a first detection line and a second detection line. The first detection line and the second detection line are both made of conductive materials and are not connected to each other. The first detection line includes a first main detection line terminal, a first main detection line and a plurality of first branch detection lines connected to the first main detection line. The second detection line includes a second main detection line terminal, a second main detection line and a plurality of second branch detection lines connected to the second main detection line. A detection area is provided in the middle of the packaging layer, and the first branch detection line and the second branch detection line are correspondingly staggered in the detection area, forming an open ring shape that is not connected to each other.

3. The safety valve protective film with integrated pressure and temperature leakage sensor according to claim 2, characterized in that: The flexible thin film pressure-temperature composite sensor comprises two electrode wires, electrode terminals and a sensitive material connected to the tails of the two electrode wires, wherein the sensitive material is a piezoelectric polymer PVDF-TrFE material, and the sensitive material is located at the center of a detection area, and the electrode wires do not intersect with the first detection wire and the second detection wire, and are located between the first main detection wire and the second main detection wire; the front end areas of the two electrode wires in the flexible thin film pressure-temperature composite sensor are fixed in the packaging layer, and the tail areas hang down due to the traction of the gravity of the sensitive material, and the first main detection wire terminal, the second main detection wire terminal and the electrode terminal are all located outside the detection area.

4. The safety valve protective film with integrated pressure and temperature leakage sensor according to claim 1, characterized in that: The sensing layer is further provided with an annular fixing piece, which is used to fixedly connect the first main detection line and the second main detection line and to wrap the first branch detection line and the second branch detection line.

5. The safety valve protective film with integrated pressure and temperature leakage sensor according to claim 4, characterized in that: The adhesive layer is composed of an annular film.

6. The safety valve protective film with integrated pressure and temperature leakage sensor according to claim 5, characterized in that: The insulating layer is composed of an annular insulating plate and a special-shaped insulating plate matching the flexible film type pressure-temperature composite sensor. One end of the special-shaped insulating plate is located inside the annular insulating plate and is in a downward hanging state, and the other end is located outside the annular insulating plate and is in a horizontal state. The flexible film type pressure-temperature composite sensor is located above the special-shaped insulating plate, the annular fixing piece is located above the annular insulating plate, and the annular film is located below the annular insulating plate.

7. The safety valve protective film with integrated pressure and temperature leakage sensor according to claim 6, characterized in that: The packaging layer is composed of an elliptical packaging plate and a rectangular packaging plate, one end of the rectangular packaging plate is connected to the side of the elliptical packaging plate, the elliptical packaging plate is located above the annular fixing piece, and the rectangular packaging plate is located above the front end area of ​​the first main detection line, the first main detection line, and the electrode line.

8. The safety valve protective film with integrated pressure and temperature leakage sensor according to claim 7, characterized in that: The annular film, the annular isolation plate, the annular fixing piece and the elliptical packaging plate have the same outer contours and are sequentially fitted and connected. The annular fixing piece, the annular film and the annular isolation plate have the same widths.

9. The safety valve protective film with integrated pressure and temperature leakage sensor according to claim 1, characterized in that: The overall thickness of the adhesive layer is 0.2 mm; the overall thickness of the insulating layer is 10-40 μm; and the overall thickness of the encapsulation layer is 20-40 μm.

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