Flexible pressure sensor for battery swelling force detection and preparation method thereof

Abstract

The application discloses a flexible pressure sensor for battery swelling force detection, which comprises an upper substrate, a dielectric layer, an electrode layer and a lower substrate arranged in sequence from top to bottom; the electrode layer is a metal electrode with an interdigital structure, and the electrode layer is attached to a set area of the lower substrate; the dielectric layer is adhered to a set area of the upper substrate by using a sensitive structure; the upper substrate and the lower substrate are fixedly attached around the set area; when no pressure is applied, a gap exists between the dielectric layer and the electrode layer, and the metal electrode with the interdigital structure outputs resistance value information; when pressure is applied to the upper substrate or the lower substrate, the dielectric layer and the electrode layer are in contact and the contact area gradually increases, and the resistance value information output by the metal electrode with the interdigital structure gradually decreases. The application improves the stability and resolution of the pressure sensor and reduces the manufacturing cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flexible pressure sensors, in particular to a flexible pressure sensor for battery swelling force detection and a preparation method thereof. BACKGROUND

[0002] Flexible array pressure sensors, as an important part of the flexible electronics field, have shown great development prospects in recent years. With the rapid development of the Internet of Things and artificial intelligence technology, and the increasing demand for high-performance flexible sensors, the research on flexible pressure sensors has been greatly promoted.

[0003] In particular, in the field of new energy batteries today, the application of flexible pressure sensors is particularly significant. They are not only used to monitor the swelling state of the battery to ensure the safety of the battery, but also help to achieve battery health management and predict battery life. For example, through real-time monitoring by flexible pressure sensors, problems such as overcharging, overdischarging, and thermal runaway can be prevented, thereby ensuring the safety of equipment and users. However, such flexible sensors usually have high sensitivity and flexibility, can adapt to changes in battery shape, and can maintain contact even when the battery swells. They can detect small pressure changes and provide key data for the battery management system, thereby achieving real-time monitoring of the health of the battery. In addition, the durability and reliability of flexible array pressure sensors ensure long-term stable operation and provide a strong guarantee for battery safety.

[0004] To achieve battery swelling force detection, various microstructure designs of flexible sensitive media have been proposed on the market, but most of them are based on sandwich structures, which have complex preparation processes, high costs, low integration of sensitive units, and poor stability, making it difficult to be widely used in battery swelling force detection.

[0005] In summary, in order to reduce the complexity of the process, improve the long-term stability and detect smaller changes in battery swelling pressure, it is necessary to design and develop a flexible high-integration interdigital array pressure sensor for battery swelling force detection. SUMMARY

[0006] The main purpose of the present application is to overcome the above-mentioned defects in the prior art, and to provide a flexible pressure sensor for battery swelling force detection and a preparation method thereof, which improves the stability and resolution of the pressure sensor while reducing the manufacturing cost.

[0007] The present application adopts the following technical solutions:

[0008] The application discloses a flexible pressure sensor for battery swelling force detection, which comprises an upper substrate, a dielectric layer, an electrode layer and a lower substrate arranged in sequence from top to bottom; the electrode layer is a metal electrode with an interdigital structure, and the electrode layer is attached to a set area of the lower substrate; the dielectric layer is attached to a set area of the upper substrate by using a sensitive structure; the upper substrate and the lower substrate are fixedly attached around the set area; when no pressure is applied, a gap exists between the dielectric layer and the electrode layer, and the metal electrode with the interdigital structure outputs resistance value information; when pressure is applied to the upper substrate or the lower substrate, the dielectric layer is in contact with the electrode layer, and the contact area gradually increases, and the resistance value information output by the metal electrode with the interdigital structure gradually decreases.

[0009] The dielectric layer is opposite to the interdigital structure of the electrode layer, and when no pressure is applied, a gap exists between the dielectric layer and the interdigital structure of the electrode layer, and the metal electrode with the interdigital structure outputs a resistance signal; when pressure is applied, the dielectric layer is in contact with the interdigital structure, and the contact area gradually increases, and the resistance signal output by the metal electrode with the interdigital structure gradually decreases.

[0010] The upper substrate is at least one of a PI film, a PET film and a TPU film.

[0011] The lower substrate is at least one of a PI film, a PET film and a TPU film.

[0012] The dielectric layer is at least one of carbon paste, carbon nanotube, carbon powder and TPU solution or boron nitride.

[0013] The electrode layer material can be at least one of copper foil, conductive silver paste, liquid metal and nickel cloth.

[0014] The interdigital structure comprises a plurality of first fingers and a plurality of second fingers, and the plurality of first fingers and the plurality of second fingers are staggered and distributed, and the distance between adjacent first fingers and second fingers is 0.1-0.5 mm; the electrode layer is provided with an array-distributed interdigital structure, and the array-distributed interdigital structure on the electrode layer comprises any one of 4x4, 8x8 and 16x16.

[0015] A preparation method of a flexible pressure sensor for battery swelling force detection, comprising the following steps:

[0016] 1) An electrode layer is prepared by a laser etching process or an FPC process, and is attached to a set area of a lower substrate;

[0017] 2) A slurry of a dielectric layer is prepared, the slurry is fully stirred, and the slurry is repeatedly brushed on a set area of an upper substrate by a screen printing process, and is dried after each brushing to form a dielectric.

[0018] 3) Finally, the upper substrate and the lower substrate are hot-pressed and cooled after brushing hot glue around the set area of the upper substrate and the lower substrate by a silk screen printing process, to obtain a flexible pressure sensor.

[0019] The laser etching process is to draw the pattern of the interdigital structure to be processed on a laser processing platform, and then etch the electrode layer material, and transplant the etched electrode layer to the lower substrate coated with hot glue; the FPC process is to directly process the electrode layer and the lower substrate layer into a soft plate circuit through a circuit processing process.

[0020] From the above description of the present application, compared with the prior art, the present application has the following beneficial effects:

[0021] The flexible high-integration interdigital array pressure sensor provided by the present application is composed of a single dielectric layer and an electrode layer and a substrate layer arranged on one side of the dielectric layer. In a first aspect, the overall structure of the present application is simple, and all are made of flexible materials, which improves the flexibility of the sensor. In a second aspect, the sensor provided by the present application has a high integration degree of the sensitive unit compared with the existing design, has a high resolution for a small pressure, can measure more point positions on the same size area, and is more light and thin. In a third aspect, the preparation process of the sensor provided by the present application is simple, the raw materials are widely available, and is conducive to actual mass production. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a schematic diagram of the composition structure of the pressure sensor of the present application;

[0023] Figure 2 It is a schematic diagram of the structure of each part of the pressure sensor of the present application;

[0024] Figure 3 It is a schematic diagram of the working principle of the pressure sensor of the present application;

[0025] Figure 4 It is a schematic diagram of the force measurement device structure using the pressure sensor of the present application;

[0026] Figure 5 It is a schematic diagram of a single interdigital structure of the pressure sensor of the present application

[0027] Figure 6 It is a schematic diagram of the actual measurement of the pressure sensor of the present application;

[0028] Figure 7 It is the test data of a single sensitive point of the pressure sensor of the present application.

[0029] Among them:

[0030] 1 - upper substrate, 2 - dielectric layer, 3 - electrode layer, 31 - first electrode, 32 - second electrode, 33 - first body, 34 - second body, 35 - first finger, 36 - second finger, 4 - lower substrate.

[0031] The application will be further described in the following with reference to the accompanying drawings and specific embodiments. DETAILED DESCRIPTION

[0032] The application will be further described in the following with reference to the accompanying drawings and specific embodiments.

[0033] Reference Figure 1 , Figure 2 , the application provides a flexible pressure sensor for detecting battery swelling force, which comprises, from top to bottom, an upper substrate 1, a dielectric layer 2, an electrode layer 3 and a lower substrate 4. The electrode layer 3 is a metal electrode with interdigital structure, and the electrode layer 3 is attached to a set area of the lower substrate 4. The dielectric layer 2 is adhered to a set area of the upper substrate 1 using a sensitive structure; the upper substrate 1 and the lower substrate 4 are fixedly pasted around the set area. When no pressure is applied, there is a gap between the dielectric layer 2 and the electrode layer 3, i.e. the dielectric layer 2 almost does not contact the electrode layer 3, so the resistance of the interdigital structure of the electrode layer 3 is large, and the metal electrode of the interdigital structure outputs a stable and large resistance value information. When pressure is applied to the upper substrate 1 or the lower substrate 4, the dielectric layer 2 gradually contacts the electrode layer 3, the contact area gradually increases, the resistance of the interdigital structure gradually decreases, and the resistance value information output by the metal electrode of the interdigital structure gradually decreases. As shown in Figure 7 , the applied pressure and the measured resistance value present a log curve distribution.

[0034] , the sensitive unit of the dielectric layer 2 and the electrode layer 3 is opposite, i.e. the interdigital structure. When no pressure is applied, there is a gap between the dielectric layer 2 and the interdigital structure of the electrode layer 3, and the metal electrode of the interdigital structure outputs a resistance signal; when pressure is applied, the dielectric layer 2 contacts the interdigital structure and the contact area gradually increases, and the resistance signal output by the metal electrode of the interdigital structure gradually decreases. As shown in Figure 3 , the change of pressure makes the contact area of the interdigital structure of the dielectric layer 2 and the electrode layer 3 increase, and then makes the resistance value output by the interdigital structure decrease, and the resistance value signal is output through the electrode pin.

[0035] In the application, reference is made to Figure 2The upper substrate 1 is made of at least one of PI film, PET film and TPU film. The lower substrate 4 is made of at least one of PI film, PET film and TPU film. The periphery of the set region on the opposite side of the upper substrate 1 and the lower substrate 4 is bonded together by heat curing adhesive. The dielectric layer 2 is made of at least one of carbon paste, carbon nanotube, carbon powder and TPU solution or boron nitride. The electrode layer 3 is made of at least one of copper foil, conductive silver paste, liquid metal and nickel cloth. The upper substrate 1, the lower substrate 4, the dielectric layer 2 and the electrode layer 3 are all flexible materials, which improves the flexibility of the whole sensor.

[0036] Further, referring to Figure 5 Each interdigital structure includes a first electrode 31 and a second electrode 32. The first electrode 31 is provided with a first body 33 and two groups of first fingers 35, and the two groups of first fingers 35 are symmetrically arranged relative to the first body 33. Each group includes two first fingers 35 connected to the first body 33 and parallel and spaced apart. The second electrode 32 is provided with a second body 34 and two groups of second fingers 36. The second body 34 is arranged outside the periphery of the first electrode 31. The second body 34 is a square ring and is provided with a notch to accommodate the first body 33. The two groups of second fingers 36 are respectively connected to two opposite sides of the second body 34 and are symmetrically arranged relative to the first body 33. Each group includes two parallel and spaced apart second fingers 36. The two first fingers 35 of each group of first fingers 35 are arranged in cross with the two second fingers 36 of the corresponding group of second fingers 36.

[0037] In the interdigital structure, the distance between the first finger 35 and the second body 34 in the length direction of the first finger 35 is l, the width of the first finger 35 and the distance between the adjacent first finger 35 and the second finger 36 are also l. The distance l is in the range of 0.1-0.5mm. The distance l is set in this size range after considering the processing cost, processing technology and sensing performance. On the one hand, if l is less than 0.1mm, the screen printing process cannot achieve this processing effect, but if other processes are used, the process processing cost will increase, and if l is less than 0.1mm, the sensitivity of the sensor will also be improved. On the other hand, if l is greater than 0.5mm, the contact area between the two electrodes of the sensitive unit will be smaller without changing the overall size of the single interdigital structure, which will significantly reduce the sensitivity of the sensor. Therefore, considering comprehensively, the distance l of the present application is in the range of 0.1-0.5mm.

[0038] Further, the width of the first finger 35 and the second body 34 is also l. The first body 33 is divided into two parts. One part is connected to the two groups of first fingers 35 and its width is l. The other part passes through the notch of the second body 34 and its width is 3l.

[0039] The electrode layer 3 of the present application is provided with an array distribution of interdigital structures, and the array distribution of the interdigital structures on the electrode layer 3 includes any one of 4x4, 8x8, 16x16. That is, the integration of the interdigital structures of the electrode layer 3 can be selected from any one of 4x4, 8x8, 16x16. Among them, the integration represents the number of the array distribution of the interdigital structures on the electrode layer 3. Taking 16x16 as an example, it means that there are 16 rows and 16 columns of interdigital structures on the electrode layer 3. By setting high-density interdigital structures, the resolution of micro pressure is significantly enhanced.

[0040] When the flexible pressure sensor of the present application is used for pressure detection, the resistance value signal output by the electrode layer 3 of the pressure sensor is input into the MCU through a multi-way switch, and then the ADC set in the MCU processes the analog signal into a digital signal and sends it to the PC end through a serial port for display on the host computer. The displayed information is the pressure value processed by the internal algorithm, that is, the resistance value collected from the sensitive unit is converted into a pressure value through the resistance and pressure curve relationship, as shown in Figure 7 .

[0041] In actual application, the host computer processes the digital signal by algorithm, and displays the pressure data measured by the flexible pressure sensor through different colors, which is simple and intuitive. As shown in Figure 6 , which is the actual test result graph of the pressure sensor. Figure 7 , which is the data measured by a single interdigital structure of the sensor.

[0042] The specific arrangement method of the flexible pressure sensor of the present application in actual application is as follows:

[0043] The flexible pressure sensor is placed between adjacent batteries in the battery module. Since the total thickness of the flexible pressure sensor is thin and is composed of flexible materials, the overall performance of the original battery module is slightly affected. The signal output pin of the flexible pressure sensor is exposed outside and connected to the related acquisition circuit through the terminal.

[0044] As a specific embodiment, the overall shape and size of the flexible array pressure sensor can be adjusted as needed during use, which is not limited here.

[0045] Based on this, the present application further provides a preparation method of a flexible pressure sensor for detecting battery swelling force, comprising the following steps:

[0046] 1) The electrode layer 3 is made by laser etching process or FPC process, and is pasted to the set area of the lower substrate 4.

[0047] The laser etching process is to draw the pattern of the interdigital structure to be processed on a laser processing platform, and then etch the electrode layer 3 material, and then transplant the etched electrode layer 3 to the lower substrate 4 coated with thermosetting glue.

[0048] 2) The slurry of the dielectric layer 2 is prepared, the slurry is fully stirred on a stirring table, and the dielectric is formed by repeatedly brushing the slurry on the set area of the upper substrate 1 through a screen printing process, and drying treatment is performed after each brushing. The slurry of the dielectric layer 2 is brushed at least one of 2-4 times, the brushing times affect the initial value, and the more the times, the smaller the initial resistance value.

[0049] 3) Finally, the thermosetting glue is brushed around the set area of the upper substrate 1 and the lower substrate 4 through a screen printing process, and the upper substrate 1 and the lower substrate 4 are hot-pressed and cooled to obtain the flexible pressure sensor.

[0050] The flexible pressure sensor and the preparation method thereof improve the stability and resolution of the pressure sensor, and also reduce the manufacturing cost.

[0051] In the present application, the terms "first", "second", "third" and the like are only used to distinguish similar objects, and do not have to be used to describe a specific order or sequence, and cannot be understood as indicating or implying relative importance. In the description, the directions or positions indicated by "up", "down", "left", "right", "front" and "back" are based on the directions or positions shown in the drawings, and are only for the convenience of describing the present application, and do not indicate or imply that the devices must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application. For ordinary skilled persons in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0052] In addition, in the description of the present application, "a plurality of" means two or more, unless otherwise specified. The association relationship between the associated objects is described as "and / or", which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0053] The above is only a specific embodiment of the present application, but the design concept of the present application is not limited thereto, and any non-essential modification of the present application using this concept shall be regarded as an act of infringing the protection scope of the present application.

Claims

1. A flexible pressure sensor for battery swelling force detection, characterized by, The flexible pressure sensor comprises an upper substrate, a dielectric layer, an electrode layer and a lower substrate arranged in sequence from top to bottom; the electrode layer is a metal electrode with interdigital structure, and is attached to a set area of the lower substrate; the dielectric layer is adhered to a set area of the upper substrate with a sensitive structure; the upper substrate and the lower substrate are fixed around the set area; when no pressure is applied, there is a gap between the dielectric layer and the electrode layer, and the metal electrode with interdigital structure outputs resistance value information; when pressure is applied to the upper substrate or the lower substrate, the dielectric layer is in contact with the electrode layer, and the contact area gradually increases, and the resistance value information output by the metal electrode with interdigital structure gradually decreases; the dielectric layer is opposite to the interdigital structure of the electrode layer, and when no pressure is applied, there is a gap between the dielectric layer and the interdigital structure of the electrode layer, and the metal electrode with interdigital structure outputs resistance signal; when pressure is applied, the dielectric layer is in contact with the interdigital structure, and the contact area gradually increases, and the resistance signal output by the metal electrode with interdigital structure gradually decreases. The interdigital structure comprises a plurality of first fingers and a plurality of second fingers, and the plurality of first fingers and the plurality of second fingers are staggered and distributed, and the distance between adjacent first fingers and second fingers is 0.1-0.5mm; the electrode layer is provided with an array of interdigital structures, and the array of interdigital structures on the electrode layer comprises any one of 4x4, 8x8 and 16x16. The preparation steps of the flexible pressure sensor for battery swelling force detection are as follows: 1) An electrode layer is prepared by a laser etching process or an FPC process, and is attached to a set area of a lower substrate; 2) A slurry of the dielectric layer is prepared, the slurry is fully stirred, and the slurry is repeatedly brushed on a set area of an upper substrate by a screen printing process, and is dried after each brushing to form a dielectric; 3) Finally, a thermosetting glue is brushed around the set areas of the upper substrate and the lower substrate by a screen printing process, and the upper substrate and the lower substrate are hot-pressed and cooled to obtain a flexible pressure sensor.

2. The flexible pressure sensor for battery swelling force detection according to claim 1, wherein The upper substrate is at least one of PI film, PET film and TPU film.

3. The flexible pressure sensor for battery swelling force detection according to claim 1, wherein The lower substrate is at least one of PI film, PET film and TPU film.

4. The flexible pressure sensor for battery swelling force detection according to claim 1, wherein The dielectric layer is at least one of carbon slurry, carbon nanotube, carbon powder and TPU solution or boron nitride.

5. The flexible pressure sensor for battery swelling force detection according to claim 1, wherein The material of the electrode layer can be at least one of copper foil, conductive silver paste, liquid metal and nickel cloth.

6. The flexible pressure sensor for battery swelling force detection according to claim 1, wherein The laser etching process is to first draw the pattern of the interdigital structure to be processed on a laser processing platform, and then etch the electrode layer, and transplant the etched electrode layer to the lower substrate coated with thermosetting glue; the FPC process is to directly process the electrode layer and the lower substrate layer into a soft board circuit by a circuit processing process.

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