Battery expansion monitoring sensor

Abstract

The utility model discloses a battery expansion monitoring sensor, and relates to the technical field of battery expansion monitoring. The battery expansion monitoring sensor comprises a coating unit and a sensing unit which are arranged outside a lithium battery body, the coating unit comprises a plastic film base material, and the sensing unit comprises conductive films which are symmetrically arranged. According to the battery expansion monitoring sensor, the conductive films are overlapped to form a capacitance sensor, when the lithium battery body expands to cause deformation of the plastic film base material wrapping the outer wall of the lithium battery body, the two conductive films are pulled to move oppositely, the overlapping area of the two conductive films is changed, and the capacitance change condition of the capacitance sensor is sensed; therefore, whether the lithium battery body has the thermal runaway phenomenon or not is obtained by monitoring the change condition of the capacitance on the capacitance sensor in real time, and the voltage of the lithium battery body is quickly cut off through real-time feedback, so that the swelling and even explosion phenomena of the battery caused by expansion overheating due to the thermal runaway are avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of battery expansion monitoring, in particular to a battery expansion monitoring sensor. Background Art

[0002] Lithium batteries have been widely used in people's daily life and production. Whether it is for 3C electronic products, commonly known as soft-pack lithium batteries, or power lithium batteries, including aluminum or steel shell lithium batteries in energy storage or electric vehicles, thermal runaway may occur. Thermal runaway refers to a chain reaction caused by various factors, causing the battery to emit a large amount of heat and gas in a short period of time, and even cause the battery to catch fire and explode in severe cases. The existing means of detecting thermal runaway mainly use voltage monitoring or temperature sensors.

[0003] With respect to thermal runaway of lithium batteries, both voltage and temperature sensors have hysteresis. When thermal runaway of a battery occurs, the battery will generate huge amounts of heat in less than 5 seconds, and at the same time emit a large amount of gas, causing the battery package to expand rapidly, and even causing the battery to catch fire and explode. However, the detection response of voltage monitoring and temperature sensors has hysteresis, and it is impossible to detect thermal runaway in time and immediately cut off the power supply of the thermal runaway battery. Therefore, for thermal runaway caused by severe collision or rapid needle puncture, it is difficult for existing technical means to quickly and timely monitor the risk. In view of the shortcoming of slow response speed of existing means for detecting thermal runaway of a battery, this application describes a battery expansion monitoring sensor. Utility Model Content

[0004] In view of the deficiencies in the prior art, the utility model provides a battery expansion monitoring sensor, which solves the shortcoming of the existing battery thermal runaway detection means having a slow response speed.

[0005] To achieve the above objectives, the utility model is implemented through the following technical solutions: a battery expansion monitoring sensor, comprising a coating unit arranged outside a lithium battery body, the coating unit comprising a plastic film substrate, the plastic film substrate surrounds the outer wall surface of the lithium battery body in its expansion direction, and both ends of the plastic film substrate are provided with free ends;

[0006] A sensing unit, wherein the sensing unit is connected to the free end, the sensing unit comprises symmetrically arranged conductive films, the conductive films are arranged in an overlapping manner, the sensing unit is monitored by the conductive films, a first fixing mechanism is arranged between the conductive films and the plastic film substrate, an adhesive layer is arranged between the conductive films, the top end of the adhesive layer is connected to the top end of one of the conductive films, and the bottom end of the adhesive layer is connected to the bottom end of another of the conductive films.

[0007] Preferably, the material of the plastic film substrate includes but is not limited to PET, PI, PC, PMMA, polyurethane, silicone or polyvinyl chloride film.

[0008] Preferably, the material of the conductive film includes but is not limited to a metal film, a metal oxide film, a metal nanowire film or a carbon material film.

[0009] Preferably, the first fixing mechanism includes a first fixing adhesive layer, a surface of the first fixing adhesive layer is connected to the surface of the conductive film away from the adhesive layer, the other surface of the first fixing adhesive layer is connected to the side of the plastic film substrate, and a clamping mechanism is provided between the conductive film and the plastic film substrate.

[0010] Preferably, the locking mechanism comprises a connecting frame, the conductive film is inserted into the connecting frame, the side of the plastic film substrate is locked between the conductive film and the connecting frame, and a second fixing mechanism is arranged between the plastic film substrate and the connecting frame.

[0011] Preferably, the second fixing mechanism comprises a second fixing adhesive layer, a surface of the second fixing adhesive layer is connected to the inner wall of the connecting card frame, and another surface of the second fixing adhesive layer is connected to the side of the plastic film substrate away from the first fixing adhesive layer.

[0012] Preferably, the shape of the lithium battery body includes but is not limited to a cylindrical shape and a rectangular block shape, and the thickness of the sensor unit is less than 0.3 mm.

[0013] The utility model discloses a battery expansion monitoring sensor, which has the following beneficial effects:

[0014] The battery expansion monitoring sensor forms a capacitive sensor by overlapping two conductive films. When the lithium battery body expands, the plastic film substrate covering the outer wall of the lithium battery body is deformed. The deformed plastic film substrate pulls the two conductive films to move in opposite directions, thereby changing the overlapping area of ​​the two conductive films. The capacitance change of the capacitive sensor can be sensed, and the change of capacitance on the capacitive sensor can be monitored in real time to determine whether the wrapped lithium battery body has thermal runaway. The voltage of the lithium battery body can be quickly cut off through real-time feedback to avoid expansion, overheating, battery bulging and even explosion caused by thermal runaway. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 This is a schematic diagram of the front structure of a rectangular lithium battery body of the utility model;

[0017] Figure 2 This is a schematic diagram of the top view of the rectangular lithium battery body of the utility model;

[0018] Figure 3 For this utility model Figure 1 A local enlarged structural schematic diagram;

[0019] Figure 4 This is a schematic diagram of the front structure of the cylindrical lithium battery body of the utility model;

[0020] Figure 5 It is a schematic diagram of the top structure of the cylindrical lithium battery body of the utility model.

[0021] In the figure: 101, lithium battery body; 201, conductive film; 301, plastic film substrate; 401, first fixing glue layer; 501, adhesive glue layer; 601, connecting card frame; 701, second fixing glue layer. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiments of the utility model clearer, the technical solution in the embodiments of the utility model is described clearly and completely. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0023] The embodiment of the present application provides a battery expansion monitoring sensor to solve the shortcoming of slow response speed of existing battery thermal runaway detection means. A capacitive sensor is formed by overlapping two conductive films 201. When the lithium battery body 101 expands, the plastic film substrate 301 coated on the outer wall of the lithium battery body 101 is deformed. The deformed plastic film substrate 301 pulls the two conductive films 201 to move away from each other, thereby changing the overlapping area of ​​the two conductive films, and the capacitance change of the capacitive sensor can be sensed. Therefore, by real-time monitoring of the capacitance change on the capacitive sensor, it can be determined whether the wrapped lithium battery body 101 has thermal runaway, and the voltage of the lithium battery body 101 can be quickly cut off through real-time feedback to avoid expansion, overheating, battery bulging or even explosion caused by thermal runaway.

[0024] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0025] The utility model embodiment discloses a battery expansion monitoring sensor.

[0026] Embodiment 1:

[0027] According to the attached Figure 1 -3, comprising a coating unit arranged outside the lithium battery body 101, the coating unit comprising a plastic film substrate 301, the plastic film substrate 301 surrounds the outer wall surface of the lithium battery body 101 in its expansion direction, the coating unit is sleeved on the expansion direction of the outer wall of the lithium battery body 101 through the plastic film substrate 301, and the plastic film substrate 301 is coated on the expansion direction of the outer wall of the lithium battery body 101, so that when the lithium battery body 101 expands, the plastic film substrate 301 can be expanded and deformed. In this embodiment 1, the lithium battery body 101 is in a rectangular block shape, and the length of the plastic film substrate 301 used is related to the size of the rectangular block lithium battery body 101. In actual applications, the plastic film substrate 301 of the required length needs to be cut according to the size of the lithium battery body 101;

[0028] The sensing unit, both ends of the plastic film substrate 301 are provided with free ends, the sensing unit is connected to the free ends, the sensing unit includes symmetrically arranged conductive films 201, the conductive films 201 are arranged in an overlapping manner, the sensing unit is monitored by the conductive film 201, a first fixing mechanism is arranged between the conductive film 201 and the plastic film substrate 301, an adhesive layer 501 is arranged between the conductive films 201, the top of the adhesive layer 501 is connected to the top of one of the conductive films 201, and the bottom of the adhesive layer 501 is connected to the bottom of another conductive film 201, the deformed plastic film substrate 301 pulls the two conductive films 201 to move in opposite directions, thereby changing the overlapping area of ​​the two conductive films, and the capacitance change of the capacitive sensor can be sensed, so as to obtain whether the wrapped lithium battery body 101 has a thermal runaway phenomenon by real-time monitoring of the capacitance change on the capacitive sensor, and quickly cut off the voltage of the lithium battery body 101 through real-time feedback to avoid the thermal runaway caused The expansion, overheating, bulging and even explosion of the battery is caused by a thin film structure, which monitors the deformation of the lithium battery body 101 in real time during thermal runaway. The capacitive sensor converts the displacement signal of the deformation into an electrical signal that can be easily collected and processed, thereby realizing the monitoring of the thermal runaway of the lithium battery body 101. S represents the relative area of ​​the two parallel conductive films 201, d represents the distance between the two conductive films 201, and the capacitance of the parallel plate capacitor C=a*S / d, a is a constant, so the change of S is proportional to the change of the capacitance of the capacitive sensor. The change in the capacitance of the conductive film 201 can be inferred from the change in the relative area between the parallel conductive films 201 caused by the thermal runaway expansion of the lithium battery body 101, so as to quickly make corresponding disposal. The two overlapping conductive films 201 are fixed by the adhesive layer 501, but the two conductive films 201 can stably move laterally with the deformation of the plastic film substrate 301, thereby improving the working stability of the sensing unit.

[0029] The material of the plastic film substrate 301 includes but is not limited to PET, PI, PC, PMMA, polyurethane, silicone or polyvinyl chloride film, which plays the role of tightly wrapping the outer surface of the lithium battery body.

[0030] The material of the conductive film 201 includes but is not limited to metal film, metal oxide film, metal nanowire film or carbon material film. The carbon material film can be graphite, carbon nanotube or graphene. Two conductive films 201 can be overlapped to form a capacitive sensor.

[0031] The first fixing mechanism includes a first fixing adhesive layer 401, a surface of the first fixing adhesive layer 401 is connected to the surface of the conductive film 201 away from the adhesive layer 501, and the other surface of the first fixing adhesive layer 401 is connected to the side of the plastic film substrate 301. A clamping mechanism is provided between the conductive film 201 and the plastic film substrate 301. The first fixing adhesive layer 401 ensures a stable connection between the conductive film 201 and the plastic film substrate 301, thereby improving the working stability.

[0032] The clamping mechanism includes a connecting clamping frame 601, the conductive film 201 is inserted into the inside of the connecting clamping frame 601, the side of the plastic film substrate 301 is clamped between the conductive film 201 and the connecting clamping frame 601, and a second fixing mechanism is arranged between the plastic film substrate 301 and the connecting clamping frame 601, and the second fixing mechanism includes a second fixing glue layer 701, the surface of the second fixing glue layer 701 is connected to the inner wall of the connecting clamping frame 601, and the other surface of the second fixing glue layer 701 is connected to the side of the plastic film substrate 301 away from the first fixing glue layer 401, and the plastic film substrate 301 is fixed to the connecting clamping frame 601 by the second fixing glue layer 701, and the conductive film 201 is clamped in the connecting clamping frame 601, which further improves the stability of the connection between the conductive film 201 and the plastic film substrate 301, so that the expansion of the lithium battery body 101 drives the deformation of the plastic film substrate 301, which can stably drive the two conductive films 201 to move laterally.

[0033] Embodiment 2:

[0034] According to the attached Figure 4 -5, comprising a coating unit arranged outside the lithium battery body 101, the coating unit comprising a plastic film substrate 301, the plastic film substrate 301 surrounds the outer wall surface of the lithium battery body 101 located in its expansion direction, the coating unit is sleeved on the expansion direction of the outer wall of the lithium battery body 101 through the plastic film substrate 301, and the plastic film substrate 301 is coated on the expansion direction of the outer wall of the lithium battery body 101, so that when the lithium battery body 101 expands, the plastic film substrate 301 can be expanded and deformed. In this embodiment 1, the lithium battery body 101 is cylindrical, and the length of the plastic film substrate 301 used is related to the size of the cylindrical lithium battery body 101. In actual applications, the plastic film substrate 301 of the required length needs to be cut according to the size of the lithium battery body 101;

[0035] The sensing unit, both ends of the plastic film substrate 301 are provided with free ends, the sensing unit is connected to the free ends, the sensing unit includes symmetrically arranged conductive films 201, the conductive films 201 are arranged in an overlapping manner, the sensing unit is monitored by the conductive film 201, a first fixing mechanism is arranged between the conductive film 201 and the plastic film substrate 301, an adhesive layer 501 is arranged between the conductive films 201, the top of the adhesive layer 501 is connected to the top of one of the conductive films 201, and the bottom of the adhesive layer 501 is connected to the bottom of another conductive film 201, the deformed plastic film substrate 301 pulls the two conductive films 201 to move in opposite directions, thereby changing the overlapping area of ​​the two conductive films, and the capacitance change of the capacitive sensor can be sensed, so as to obtain whether the wrapped lithium battery body 101 has a thermal runaway phenomenon by real-time monitoring of the capacitance change on the capacitive sensor, and quickly cut off the voltage of the lithium battery body 101 through real-time feedback to avoid the thermal runaway caused The expansion, overheating, bulging and even explosion of the battery is caused by a thin film structure, which monitors the deformation of the lithium battery body 101 in real time during thermal runaway. The capacitive sensor converts the displacement signal of the deformation into an electrical signal that can be easily collected and processed, thereby realizing the monitoring of the thermal runaway of the lithium battery body 101. S represents the relative area of ​​the two parallel conductive films 201, d represents the distance between the two conductive films 201, and the capacitance of the parallel plate capacitor C=a*S / d, a is a constant, so the change of S is proportional to the change of the capacitance of the capacitive sensor. The change in the capacitance of the conductive film 201 can be inferred from the change in the relative area between the parallel conductive films 201 caused by the thermal runaway expansion of the lithium battery body 101, so as to quickly make corresponding disposal. The two overlapping conductive films 201 are fixed by the adhesive layer 501, but the two conductive films 201 can stably move laterally with the deformation of the plastic film substrate 301, thereby improving the working stability of the sensing unit.

[0036] The material of the plastic film substrate 301 includes but is not limited to PET, PI, PC, PMMA, polyurethane, silicone or polyvinyl chloride film, which plays the role of tightly wrapping the outer surface of the lithium battery body.

[0037] The material of the conductive film 201 includes but is not limited to metal film, metal oxide film, metal nanowire film or carbon material film. The carbon material film can be graphite, carbon nanotube or graphene. Two conductive films 201 can be overlapped to form a capacitive sensor.

[0038] The first fixing mechanism includes a first fixing adhesive layer 401, a surface of the first fixing adhesive layer 401 is connected to the surface of the conductive film 201 away from the adhesive layer 501, and the other surface of the first fixing adhesive layer 401 is connected to the side of the plastic film substrate 301. A clamping mechanism is provided between the conductive film 201 and the plastic film substrate 301. The first fixing adhesive layer 401 ensures a stable connection between the conductive film 201 and the plastic film substrate 301, thereby improving the working stability.

[0039] The clamping mechanism includes a connecting clamping frame 601, the conductive film 201 is inserted into the inside of the connecting clamping frame 601, the side of the plastic film substrate 301 is clamped between the conductive film 201 and the connecting clamping frame 601, and a second fixing mechanism is arranged between the plastic film substrate 301 and the connecting clamping frame 601, and the second fixing mechanism includes a second fixing glue layer 701, the surface of the second fixing glue layer 701 is connected to the inner wall of the connecting clamping frame 601, and the other surface of the second fixing glue layer 701 is connected to the side of the plastic film substrate 301 away from the first fixing glue layer 401, and the plastic film substrate 301 is fixed to the connecting clamping frame 601 by the second fixing glue layer 701, and the conductive film 201 is clamped in the connecting clamping frame 601, which further improves the stability of the connection between the conductive film 201 and the plastic film substrate 301, so that the expansion of the lithium battery body 101 drives the deformation of the plastic film substrate 301, which can stably drive the two conductive films 201 to move laterally.

[0040] In summary, the shape of the lithium battery body 101 includes but is not limited to a cylindrical shape and a rectangular block shape. Figure 1 , Figure 2 and Figure 3 This is a schematic diagram of the use of rectangular block lithium batteries, where Figure 4 and Figure 5 This is a schematic diagram of the use of cylindrical batteries. The difference between the two lies in the length of the plastic film substrate 301 wrapped around the outer wall of the battery, and its length is determined by the battery size. The sensor unit structure is the same. The capacitive sensor is very sensitive to the feedback of the battery expansion deformation, which is generally in the order of 1-100ms. At the same time, the monitoring frequency can also reach the corresponding level, so the battery expansion in the case of thermal runaway can be responded to in time, reducing or even completely avoiding the risk of battery expansion or even explosion in the thermal runaway state. The thickness of the sensor unit is less than 0.3 mm, and the volume is very small. It can be close to the battery surface and will not affect the battery volume. There is no need to increase the sensor space, which has the advantage of saving space and low cost. It only needs 2 pieces of conductive film to achieve it, which is economical and affordable. It is not only suitable for thermal runaway sensing of the entire multi-piece battery module, but also can monitor thermal runaway for each battery separately, which can more efficiently handle thermal runaway, find thermal runaway batteries more accurately and handle them in time.

[0041] The above shows and describes the basic principle and main features of the utility model and the advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection claimed by the utility model is defined by the attached claims and their equivalents.

Claims

1. A battery expansion monitoring sensor, characterized in that: The invention comprises a coating unit arranged outside a lithium battery body (101), the coating unit comprising a plastic film substrate (301), the plastic film substrate (301) surrounding an outer wall surface of the lithium battery body (101) in its expansion direction, and both ends of the plastic film substrate (301) are provided with free ends; A sensing unit, wherein the sensing unit is connected to the free end, the sensing unit comprises symmetrically arranged conductive films (201), the conductive films (201) are arranged in an overlapping manner, the sensing unit is monitored by the conductive films (201), a first fixing mechanism is arranged between the conductive films (201) and the plastic film substrate (301), an adhesive layer (501) is arranged between the conductive films (201), the top end of the adhesive layer (501) is connected to the top end of one of the conductive films (201), and the bottom end of the adhesive layer (501) is connected to the bottom end of another of the conductive films (201).

2. A battery expansion monitoring sensor according to claim 1, characterized in that: The material of the plastic film substrate (301) includes, but is not limited to, PET, PI, PC, PMMA, polyurethane, silicone or polyvinyl chloride film.

3. A battery expansion monitoring sensor according to claim 1, characterized in that: The material of the conductive film (201) includes, but is not limited to, a metal film, a metal oxide film, a metal nanowire film or a carbon material film.

4. A battery expansion monitoring sensor according to claim 3, characterized in that: The first fixing mechanism comprises a first fixing adhesive layer (401), a surface of the first fixing adhesive layer (401) being connected to a surface of the conductive film (201) away from the adhesive layer (501), the other surface of the first fixing adhesive layer (401) being connected to a side of the plastic film substrate (301), and a snap-fit ​​mechanism being provided between the conductive film (201) and the plastic film substrate (301).

5. A battery expansion monitoring sensor according to claim 4, characterized in that: The locking mechanism comprises a connecting frame (601), the conductive film (201) is inserted into the interior of the connecting frame (601), the side of the plastic film substrate (301) is locked between the conductive film (201) and the connecting frame (601), and a second fixing mechanism is provided between the plastic film substrate (301) and the connecting frame (601).

6. A battery expansion monitoring sensor according to claim 5, characterized in that: The second fixing mechanism comprises a second fixing adhesive layer (701), a surface of the second fixing adhesive layer (701) being connected to the inner wall of the connecting card frame (601), and another surface of the second fixing adhesive layer (701) being connected to the side of the plastic film substrate (301) away from the first fixing adhesive layer (401).

7. A battery expansion monitoring sensor according to claim 6, characterized in that: The shape of the lithium battery body (101) includes but is not limited to a cylindrical shape and a rectangular block shape, and the thickness of the sensor unit is less than 0.3 mm.

Images