Bimodal sensor based on pressure and strain, and battery expansion detection device and method

Abstract

The invention discloses a bimodal sensor based on pressure and strain and a battery expansion detection device and method.The bimodal sensor comprises a first substrate thin film, pressure sensing units distributed in an array are arranged in the middle area of the first substrate thin film, and strip-shaped strain sensing units are arranged on the two side edges of the first substrate thin film; the pressure sensing unit is used for detecting changes of expansion force on the surface of the battery, and the strain sensing unit is used for detecting deformation of the side face of the battery. A bimodal sensor is designed, an integrally-designed film sensor is adopted, the bimodal sensor comprises an array type pressure sensing unit in the middle area and a strip-shaped strain sensing unit on the side edge, the expansion state of the battery can be sensed in multiple directions, and the accuracy of battery expansion detection is improved.

Description

Technical Field

[0001] This invention belongs to the field of battery safety management technology. It relates to a dual-modal sensor based on pressure and strain, a battery expansion detection device and method. Background Technology

[0002] With the widespread application of lithium-ion batteries in electric vehicles, energy storage systems, and other fields, their safety issues are becoming increasingly prominent. Battery swelling is one of the important precursors to battery failure (such as lithium plating, gas production, and thermal runaway). Early detection of battery swelling can effectively prevent thermal runaway, extend battery life, and improve system safety. Timely and accurate monitoring of battery swelling has gradually become an important issue in battery safety management.

[0003] Early detection technologies for battery expansion primarily relied on MEMS pressure sensors. These sensors were typically mounted in expansion force testing fixtures, which clamped the battery with a certain pre-tightening force to detect changes in expansion force during the charging and discharging process. However, due to space constraints, this technology could not be deployed in actual battery usage scenarios.

[0004] With the development of flexible sensing technology, expansion force detection technology based on thin-film force sensors has gradually been applied. Thin-film pressure sensors are typically attached to the surface of the battery to sense pressure changes, while thin-film strain sensors are typically attached to the side of the battery to sense expansion changes on the side. However, since battery expansion can occur not only on the front but also on the sides, a single pressure sensor cannot comprehensively detect the expansion, especially when expansion occurs on the side, as the expansion force cannot be effectively transmitted to the sensor itself. Furthermore, due to the significant pre-tightening force between the battery surface and the clamps or other batteries, strain sensors are unsuitable for detecting surface expansion, and in extreme cases, may even be damaged. How to effectively detect battery expansion using thin-film force sensors and comprehensively understand the deformation characteristics of the battery during use has become a bottleneck in technological development. Summary of the Invention

[0005] The purpose of this invention is to provide a dual-modal sensor based on pressure and strain, a battery expansion detection device and method. A dual-modal sensor is designed, which adopts an integrated thin-film sensor, including an array-type pressure sensing unit in the middle region and a strip-shaped strain sensing unit on the side, which can sense the battery expansion state from multiple directions and improve the accuracy of battery expansion detection.

[0006] The technical solution to achieve the purpose of this invention is as follows: A dual-mode sensor based on pressure and strain includes a first substrate film, wherein an array of pressure sensing units is disposed in the middle region of the first substrate film, and strip-shaped strain sensing units are disposed on both sides.

[0007] In a preferred embodiment, the pressure sensing unit includes an electrode layer disposed on a first substrate thin film and a pressure-sensitive thin film layer disposed on the electrode layer, with a cavity provided between the electrode layer and the pressure-sensitive thin film layer.

[0008] In a preferred embodiment, the electrode layer and the pressure-sensitive film layer are bonded together by a double-sided adhesive gasket of a certain thickness. The double-sided adhesive gasket has a hollow structure in the middle, which allows the electrode layer and the corresponding pressure-sensitive film layer to adhere to each other at their edges, and forms a cavity in the central area.

[0009] In a preferred embodiment, the electrode layer is an interdigitated electrode.

[0010] In a preferred embodiment, the strain sensing unit includes a strain-sensitive thin film and electrodes disposed at both ends of the strain-sensitive thin film.

[0011] In a preferred embodiment, the electrodes of the pressure sensing unit and the strain sensing unit are made of conductive materials; the pressure-sensitive film of the pressure sensing unit and the strain-sensitive film of the strain sensing unit are obtained by doping carbon-based polymers, metal particles, and conductive polymer materials, and their conductivity is between that of a conductor and an insulator.

[0012] In a preferred embodiment, at least one strain sensing unit is provided, and adjacent strain sensing units are connected by a hollow electrode. The hollow electrode adopts a hollow design, and the strain sensing units are connected to their own signal lines through a common electrode line, and the signal lines are arranged on the hollow electrode.

[0013] In a preferred embodiment, the strain sensing unit is bent and attached to the side of the same battery or the side of adjacent batteries to detect outward or inward deformation, respectively.

[0014] This invention also discloses a method for fabricating a dual-mode battery expansion detection device based on pressure and strain, comprising the following steps: The electrode array of the pressure sensing unit and the electrodes of the strain sensors on both sides are printed / deposited on the first substrate film, and then dried to obtain the electrode part of the sensor. Strain-sensitive material is printed / deposited between the electrodes of the two strain sensors and then dried to obtain the strain sensors on both sides. A pressure-sensitive conductive material corresponding to the shape and position of the pressure sensing unit electrode array is printed / deposited on the second substrate film, and then dried to form a pressure-sensitive layer array. The two substrate films, which are respectively printed / deposited pressure sensing unit electrode array and pressure-sensitive conductive film, are bonded face to face using double-sided adhesive gaskets.

[0015] The present invention also discloses a dual-mode battery expansion detection device based on pressure and strain, which adopts the dual-mode sensor based on pressure and strain described in any of the above claims. The pressure sensing unit is attached to the battery surface, and the strain sensing unit is bent and attached to the side of the same battery or the side of an adjacent battery, respectively detecting outward or inward deformation. The pressure sensing unit is used to detect changes in the expansion force on the battery surface, and the strain sensing unit is used to detect deformation on the side of the battery.

[0016] This invention also discloses a dual-mode battery expansion detection method based on pressure and strain, comprising the following steps: The pressure sensing units distributed in an array are attached to the surface of the battery, and the changes in the expansion force on the battery surface are detected by the pressure sensing units. The two strip-shaped strain sensing units are bent and attached to the side of the same battery or the side of adjacent batteries. The deformation of the same battery side or the side of adjacent batteries is detected by the strain sensing units.

[0017] Abnormal battery expansion can be located based on changes in surface expansion force and the magnitude of deformation.

[0018] Compared with the prior art, the significant advantages of this invention are: 1. Pressure / strain sensing units are set on the same thin film. The integrated thin film sensor includes an array of pressure sensing units in the middle area and strip-shaped strain sensing units on the side. It combines the characteristics of a pressure sensor to detect the magnitude of the expansion force on the battery surface and a strain sensor to detect the expansion of the battery side. It can sense the battery expansion state from multiple directions and improve the accuracy of battery expansion detection.

[0019] 2. When detecting the expansion of a single battery, the strain sensors on both sides can be bent and pasted on both sides of the same battery; when two batteries are closely attached, such as in the battery arrangement structure inside the module, the strain sensors can be pasted on the two batteries respectively. At this time, the squeezing force between the batteries and the expansion characteristics of the two batteries can be detected separately, and the abnormal expansion of the battery can be accurately located. 3. The side strain sensor array adopts a hollow shape design, which allows the hollow area to withstand a certain degree of tensile strain, so that the connection of the sensor will not warp or break under tensile strain, thus enhancing the reliability of the strain sensor. Attached Figure Description

[0020] Figure 1 This is a structural diagram of the dual-mode sensor based on pressure and strain in this embodiment; Figure 2This is a schematic diagram of the pressure sensing unit structure in the dual-modal sensor of this embodiment; Figure 3 This is a schematic diagram of the strain sensing unit structure in the dual-modal sensor of this embodiment; Figure 4 This is a schematic diagram illustrating the dual-modal sensor attached to the battery in this embodiment to detect the battery's expansion state; Figure 5a This is a schematic diagram illustrating the method of using a dual-modal sensor for detecting the expansion force of a single battery cell in this embodiment. Figure 5b This is a schematic diagram illustrating the method of using a dual-modal sensor for detecting the expansion force of adjacent batteries in this embodiment. Figure 6 This is a schematic diagram of the strain sensing unit structure in another embodiment of a dual-modal sensor. Detailed Implementation

[0021] The principle of this invention is as follows: a pressure / strain sensing unit is set on the same thin film. The thin film sensor with integrated design includes an array of pressure sensing units in the middle area and strip-shaped strain sensing units on the side. It has the characteristics of both a pressure sensor to detect the magnitude of the expansion force on the battery surface and a strain sensor to detect the expansion of the battery side. It can sense the battery expansion state from multiple directions and improve the accuracy of battery expansion detection.

[0022] Example: like Figure 1 As shown, a dual-mode sensor based on pressure and strain includes a first substrate film 10. The middle region of the first substrate film 10 is provided with an array of pressure sensing units 20, and the two sides are provided with strip-shaped strain sensing units 30. The lead-out electrodes 40 between each sensing unit extend to one point.

[0023] A preferred embodiment, such as Figure 2 As shown, the pressure sensing unit 20 includes an electrode layer 21 disposed on the first substrate thin film 10 and a pressure-sensitive thin film layer 22 disposed on the electrode layer 21, with a cavity between the electrode layer 21 and the pressure-sensitive thin film layer 22. In the initial pressureless state, the upper and lower layers (21, 22) are separated, and the pressure sensing unit 20 behaves as an open circuit, with infinite resistance. When pressure is applied, contact resistance is generated between the upper and lower layers, and the sensing unit exhibits a relatively large initial resistance. As the applied pressure further increases, the contact between the upper and lower layers becomes tighter, and due to the parallel effect of the electrodes, the overall resistance of the device circuit decreases rapidly.

[0024] In a specific implementation, the electrode layer 21 and the pressure-sensitive film layer 22 are bonded together by a double-sided adhesive gasket (not shown in the figure) of a certain thickness. The double-sided adhesive gasket has a hollow structure in the middle, so that the edges of the electrode layer 21 and the corresponding pressure-sensitive film layer 22 are bonded to each other, and a cavity is formed in the central area.

[0025] In a specific implementation, electrode layer 21 is an interdigitated electrode, that is, an electrode structure composed of two sets of cross-arranged metal conductive strips.

[0026] Preferably, each pressure sensing unit is circular or square in shape; at least m×n pressure sensing units form an array of m rows and n columns, where m and n are both positive integers greater than 1.

[0027] A preferred embodiment, such as Figure 3 As shown, the strain sensing unit 30 includes a strain-sensitive thin film 31 and electrodes 32 disposed at both ends of the strain-sensitive thin film 31.

[0028] The strain sensing unit 30 can be fabricated by first preparing electrodes and then preparing a strain-sensitive thin film on the electrodes. In this case, the upper layer at the interface is the strain-sensitive thin film, and the lower layer is the electrode, forming a step at the interface. Alternatively, the strain-sensitive thin film can be prepared first, and then electrodes can be prepared on both sides of the strain-sensitive thin film. In this case, the upper layer at the interface is the electrode, and the lower layer is the strain-sensitive thin film. This connection method makes the connection between the electrode and the strain-sensitive thin film tighter.

[0029] A preferred embodiment, such as Figure 6 As shown, multiple strain sensing units 30 are provided, and adjacent strain sensing units 30 are connected by hollowed-out electrodes 33. The hollowed-out electrodes 33 adopt a hollowed-out design and have rounded corners. Multiple strain sensing units are connected to their own signal lines 322 through a common electrode line 321, and the signal lines are set on the hollowed-out electrodes 33. The advantage of this is that the hollowed-out parts have a certain tensile strength and will not peel or break when subjected to tensile strain.

[0030] The strain sensing unit 30 can be transformed into a strain sensing array by splitting and adding electrodes. The strain sensing array remains strip-shaped and consists of at least one strain sensing unit. This strain sensing array is attached to the side of the battery in a partitioned manner. Each unit is connected to its own signal line via a common electrode line, and the signal line is fabricated on a perforated substrate film. The advantage of this design is that when the sensing unit detects lateral strain caused by battery expansion, only the resistance of the printed strain-sensitive area changes, thus detecting the strain distribution at different locations on the side of the battery. Simultaneously, the perforated design allows the leads to withstand a certain amount of tension without warping or breaking, thereby preventing additional resistance changes and enhancing the tensile reliability of the strain sensor.

[0031] Another embodiment, a method for fabricating a dual-mode battery expansion detection device based on pressure and strain, includes the following steps: (a) The electrode array of the pressure sensing unit and the electrodes of the strain sensors on both sides are printed / deposited on the first substrate film, and the electrode part of the sensor is obtained by drying. (b) Print / deposit strain-sensitive material between the two strain sensor electrodes and dry it to obtain the two strain sensors; (c) Print / deposit pressure-sensitive conductive material corresponding to the shape and position of the pressure sensing unit electrode array on the second substrate film, and dry it to form a pressure-sensitive layer array; (d) The two substrate films, which are respectively printed / deposited pressure sensing unit electrode array and pressure-sensitive conductive film, are glued face to face with double-sided adhesive gaskets to obtain a dual-mode sensor.

[0032] Specifically, the electrodes of the pressure sensing unit and the strain sensing unit are made of highly conductive materials such as silver and copper.

[0033] The pressure-sensitive film of the pressure sensing unit and the strain-sensitive film of the strain sensing unit are made of one or more conductive fillers, including polymer-doped carbon-based materials, metal particles, and conductive polymer materials, and their conductivity is between that of a conductor and an insulator.

[0034] The fabrication process of the strain sensing unit involves first printing electrodes on both sides, drying them, then printing strip-shaped strain-sensitive material between the electrodes, and finally drying and curing to obtain the strain sensing unit. This method results in a 15-30 micrometer thick step at the interface between the electrodes and the strain-sensitive film. This step, caused by the height difference between the conductive film and the printed electrodes, leads to stress concentration at the interface under long-term tensile strain.

[0035] Preferably, a strip-shaped strain-sensitive film is first printed, and after drying, electrodes are printed at both ends. At this time, the step is obtained by bending the silver electrode. Since the conductivity of silver is much higher than that of the strain-sensitive film, the resistance change rate is small under long-term bending, thus the stability of this scheme is higher under long-term cycling.

[0036] The size, number, and distribution of pressure sensing units, as well as the size, number, and distribution of strain sensing units, can be adjusted according to the size specifications of the prismatic battery under test and specific testing requirements. Specifically, Figure 1 The pressure / strain dual-mode sensor is sized to match a 280Ah prismatic battery with dimensions of 71mm × 173mm × 204mm. The sensor unit design must ensure that the pressure sensing unit essentially covers the battery surface, and that the bent strain sensing units on both sides are positioned in the center of the side profile and firmly adhered to the side of the housing.

[0037] Another embodiment, a dual-mode battery expansion detection method based on pressure and strain, includes the following steps: The pressure sensing units distributed in an array are attached to the surface of the battery, and the changes in the expansion force on the battery surface are detected by the pressure sensing units. The two strip-shaped strain sensing units are bent and attached to the side of the same battery or the side of adjacent batteries. The deformation of the same battery side or the side of adjacent batteries is detected by the strain sensing units.

[0038] Accurately locate abnormal battery expansion based on changes in surface expansion force and deformation magnitude.

[0039] In another embodiment, a dual-mode battery expansion detection device based on pressure and strain employs the dual-mode sensor based on pressure and strain described in any of the above embodiments. The pressure sensing unit 20 is attached to the battery surface, and the strain sensing unit 30 is bent and attached to the side of the same battery or the side of an adjacent battery, respectively detecting outward or inward deformation. The pressure sensing unit 20 is used to detect changes in the expansion force on the battery surface, and the strain sensing unit 30 is used to detect deformation on the side of the battery.

[0040] like Figure 4 As shown, the pressure sensing unit 20 array is attached to the surface of the battery 100, and the strain sensors 30 on both sides are bent and attached to the sides of the battery. When the battery expands, both the surface and sides of the battery will undergo expansion deformation, and due to the internal structure of the lithium battery and its casing, the expansion deformation of the battery surface is much greater than that of the sides. Therefore, the changes that occur when the battery expands and the response mechanism of the sensors are as follows: When the battery is clamped in the expansion force fixture and expands during charging, the pressure sensor array attached to the battery surface detects the compressive force on the battery surface, and the resistance of each sensing unit decreases. Simultaneously, the strain sensors attached to the sides of the battery detect the outward expansion of the battery sides. At this time, the strain sensors also bend outward with the expansion of the casing, and their resistance increases. As the battery expands further, the resistance of the surface-mounted pressure sensor units decreases further under pressure, while the resistance of the side-mounted strain sensors increases. When the battery is charged to 100% SOC, the changes in pressure and strain sensor values ​​reach their maximum. During discharge, the battery expands and contracts to some extent, at which point the signals from the pressure and strain sensor units gradually recover. As the battery discharges to its initial state, the pressure and strain sensor signals return to their initial levels.

[0041] In a preferred embodiment, the strain sensing unit 20 is bent and attached to the side of the same battery or the side of an adjacent battery to detect outward or inward deformation, respectively.

[0042] like Figure 5aAs shown, for a single battery cell 100, pressure sensing units 20 are arrayed and attached to the surface of the square battery, and strip-shaped strain sensing units 30 on both sides are bent and attached to the side of the battery. When the battery expands, both the surface and the side of the battery expand and bend. At this time, the pressure sensing unit is subjected to a change in pressure resistance, and at the same time, the strain sensing unit senses the deformation of the battery casing and also produces a corresponding change.

[0043] In particular, such as Figure 5b As shown, for two prismatic batteries 200 in contact with each other, an array of pressure sensing units 20 can be attached to one of the batteries, while a strain sensing unit 30 on one side is also attached to that battery, and a strain sensor on the other side is attached to the other battery. In this case, the sensors can simultaneously detect and locate the expansion state of the two batteries.

[0044] Specifically, since the strain sensors on both sides are fabricated on the same side of the substrate film, after bending and pasting, one side of the two strain sensors faces outwards and the other side faces inwards (the strain sensor pasted on the other battery faces inwards). When the battery expands, in addition to the decrease in resistance of the central pressure sensor array due to the compression of the two batteries, the resistance of the outward-facing sensor increases as the battery expands, while the resistance of the inward-facing sensor decreases as it bends inwards. Therefore, the battery expansion characteristics can be judged by the signal change trends of the two strain sensors. When the central pressure sensor changes drastically and the resistance change on one side is significantly greater than that on the other side, it can be determined that the battery on the side with the larger change has an abnormality. Power should be cut off immediately and appropriate measures should be taken to prevent accidents.

[0045] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A dual-modal sensor based on pressure and strain, characterized in that, It includes a first substrate film, wherein an array of pressure sensing units is disposed in the middle region of the first substrate film, and strip-shaped strain sensing units are disposed on both sides.

2. The dual-mode sensor based on pressure and strain according to claim 1, characterized in that, The pressure sensing unit includes an electrode layer disposed on a first substrate thin film and a pressure-sensitive thin film layer disposed on the electrode layer, with a cavity provided between the electrode layer and the pressure-sensitive thin film layer.

3. The dual-mode sensor based on pressure and strain according to claim 2, characterized in that, The electrode layer and the pressure-sensitive film layer are bonded together by a double-sided adhesive gasket of a certain thickness. The double-sided adhesive gasket has a hollow structure in the middle, which allows the electrode layer and the corresponding pressure-sensitive film layer to adhere to each other at their edges, and forms a cavity in the central area.

4. The pressure and strain-based dual-mode sensor according to claim 2, characterized in that, The electrode layer is an interdigitated electrode.

5. The dual-mode sensor based on pressure and strain according to claim 1, characterized in that, The strain sensing unit includes a strain-sensitive thin film and electrodes disposed at both ends of the strain-sensitive thin film.

6. The dual-mode sensor based on pressure and strain according to claim 1, characterized in that, The electrodes of the pressure sensing unit and the strain sensing unit are made of conductive materials; the pressure-sensitive film of the pressure sensing unit and the strain-sensitive film of the strain sensing unit are obtained by doping carbon-based polymers, metal particles and conductive polymer materials, and their conductivity is between that of a conductor and an insulator.

7. The dual-mode sensor based on pressure and strain according to claim 1, characterized in that, The strain sensing unit is provided with at least one, and adjacent strain sensing units are connected by a hollow electrode. The hollow electrode adopts a hollow design, and the strain sensing units are connected to their own signal lines through a common electrode line, and the signal lines are arranged on the hollow electrode.

8. A method for fabricating a dual-mode battery expansion detection device based on pressure and strain, characterized in that, Includes the following steps: The electrode array of the pressure sensing unit and the electrodes of the strain sensors on both sides are printed / deposited on the first substrate film, and then dried to obtain the electrode part of the sensor. Strain-sensitive material is printed / deposited between the electrodes of the two strain sensors and then dried to obtain the strain sensors on both sides. A pressure-sensitive conductive material corresponding to the shape and position of the pressure sensing unit electrode array is printed / deposited on the second substrate film, and then dried to form a pressure-sensitive layer array. The two substrate films, which are respectively printed / deposited pressure sensing unit electrode array and pressure-sensitive conductive film, are bonded face to face using double-sided adhesive gaskets.

9. A dual-mode battery expansion detection device based on pressure and strain, characterized in that, The dual-modal sensor based on pressure and strain according to any one of claims 1-7 is used, wherein the pressure sensing unit is attached to the surface of the battery, and the strain sensing unit is bent and attached to the side of the same battery or the side of an adjacent battery, respectively detecting outward or inward deformation. The pressure sensing unit is used to detect changes in the expansion force of the battery surface, and the strain sensing unit is used to detect deformation of the side of the battery.

10. A dual-mode battery expansion detection method based on pressure and strain, characterized in that, Includes the following steps: The pressure sensing units distributed in an array are attached to the surface of the battery, and the changes in the expansion force on the battery surface are detected by the pressure sensing units. The two strip-shaped strain sensing units are bent and attached to the side of the same battery or the side of adjacent batteries. The deformation of the same battery side or the side of adjacent batteries is detected by the strain sensing units. Abnormal battery expansion can be located based on changes in surface expansion force and the magnitude of deformation.

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