Battery safety sensing protective film and battery pack

Abstract

In order to solve the problem that an existing battery cell safety monitoring device cannot respond in time and effectively prevent thermal runaway, the utility model provides a battery safety sensing protective film and a battery pack, the battery safety sensing protective film comprises a sealing element, a hydrogel block, a buffer layer and at least two electrodes, the sealing element is provided with a containing cavity, and the hydrogel block is arranged in the containing cavity. The hydrogel block is arranged in the accommodating cavity, the hydrogel block has a conformational change point adaptive to the working range of the battery, and when the temperature of the battery reaches the conformational change point, the hydrogel block releases water to form a steam layer; the buffer layer is arranged on at least one side of the hydrogel block. Each electrode at least partially surrounds the hydrogel block, one end of a lead of each electrode extends out of the sealing piece, the electrodes are connected with an external resistor and a volt-ammeter and are used for monitoring a voltage signal and a current signal of the hydrogel block, the voltage signal is used for feeding back a temperature difference between the two electrodes, and the current signal is used for monitoring the temperature difference. The current signal is used for feeding back the deformation amount of the hydrogel block and / or the deformation amount of the to-be-monitored battery.

Description

Technical Field

[0001] This utility model belongs to the field of battery technology, specifically relating to a battery safety sensing protective film and a battery pack. Background Technology

[0002] With the continuous development of battery energy storage technology and the increasing popularity of new energy vehicles, battery thermal runaway is a serious safety accident that can occur in new energy electric vehicles and battery energy storage systems. It can lead to catastrophic fires and explosions of the battery pack. Therefore, battery safety and performance monitoring have become crucial issues. Currently, in the fields of battery energy storage and new energy vehicles, temperature and pressure monitoring of battery cells typically relies on external sensors. However, these methods suffer from problems such as complex installation, high cost, and limited accuracy. Moreover, in emergency situations such as thermal runaway of a battery cell, existing protective measures often cannot effectively prevent heat spread in a timely manner, which can easily lead to catastrophic consequences such as the entire battery pack exploding and burning, posing a serious threat to the lives and property of users.

[0003] Furthermore, with the continuous advancement of battery technology, the requirements for real-time feedback on battery operating status are becoming increasingly stringent, enabling timely analysis of battery health and the implementation of necessary protective measures. Therefore, there is an urgent need to develop a monitoring device capable of self-powered monitoring of temperature and pressure parameters between battery cells, and providing rapid and effective protection in emergency situations. Utility Model Content

[0004] To address the problem that existing battery cell safety monitoring devices cannot respond in a timely manner and effectively prevent thermal runaway, this utility model provides a battery safety sensing and protection film and a battery pack.

[0005] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows:

[0006] In a first aspect, this utility model provides a battery safety sensing protective film, including a sealant, a hydrogel block, a buffer layer, and at least two electrodes. The sealant has a receiving cavity, and the hydrogel block is disposed within the receiving cavity. The hydrogel block has a conformational change point adapted to the battery's operating range. When the battery temperature reaches the conformational change point, the hydrogel block releases moisture to form a vapor layer. The hydrogel block includes ion pairs with a redox potential difference. The buffer layer is disposed on at least one side of the hydrogel block.

[0007] Each of the electrodes at least partially surrounds the hydrogel block, and one end of the lead of each electrode extends out of the seal. The electrodes are connected to an external resistor and a voltmeter and ammeter for monitoring the voltage and current signals of the hydrogel block. The voltage signal is used to provide feedback on the temperature difference between the two electrodes, and the current signal is used to provide feedback on the deformation of the hydrogel block and / or the deformation of the battery to be monitored.

[0008] Optionally, the number of hydrogel blocks is two, each hydrogel block is provided with one electrode, and the buffer layer is disposed between the two hydrogel blocks.

[0009] Optionally, the thickness of the buffer layer is 0.1~2mm.

[0010] Optionally, the buffer layer is one or more of foam, filament felt, and aerogel.

[0011] Optionally, the thickness of the hydrogel block is 0.1~10mm.

[0012] Optionally, the water content in the hydrogel block is ≥80% by mass.

[0013] Optionally, the seal may be provided with a venting valve or a weak point for venting pressure relief.

[0014] Optionally, the sealing element is an aluminum-plastic film or plastic film that isolates water vapor; and / or, the electrode is a carbon paper electrode with leads.

[0015] Secondly, this utility model provides a battery pack, including a battery cell, a battery management system, and a battery safety sensing protective film as described in any one of the above. The battery safety sensing protective film is disposed on one side of the battery cell, and / or, the battery safety sensing protective film is disposed between two adjacent battery cells. The sealing member abuts against the battery cell. The electrode is electrically connected to the battery management system.

[0016] Optionally, the lead extending from the seal on the electrode is connected to the battery management system via a wire, or the electrode is wirelessly connected to the battery management system.

[0017] In this invention, voltage and current signals generated by the migration speed of ion pairs and their concentration per unit length in the hydrogel block provide real-time feedback on the battery's operating status, effectively enabling health monitoring and safety warnings of the battery's operating status. Furthermore, when thermal runaway occurs, the hydrogel block releases moisture in a short time to form a vapor layer, effectively isolating the impact of sudden high temperatures on adjacent batteries. Simultaneously, the vapor breaks through the seals and battery pack, allowing heat to be carried away in the form of water vapor, automatically preventing catastrophic consequences such as a complete battery pack explosion. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a battery safety sensing protective film provided in an embodiment of this utility model;

[0019] Figure 2 This is a schematic diagram of the structure of a battery pack provided in an embodiment of this utility model.

[0020] Labels in the attached diagram:

[0021] 10. Battery safety sensing protective film; 11. Seal; 12. Hydrogel block; 13. Electrode; 131. Lead wire; 14. Buffer layer; 20. Battery cell; 30. Battery management system. Detailed Implementation

[0022] To make the technical problems solved, technical solutions, and beneficial effects of this utility model clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this utility model and are not intended to limit its scope.

[0023] One embodiment of this utility model provides a battery safety sensing protective film, including a sealing element 11, a hydrogel block 12, a buffer layer 14, and at least two electrodes 13. The sealing element 11 has a receiving cavity, and the hydrogel block 12 is disposed within the receiving cavity. The hydrogel block 12 has a conformational change point adapted to the battery's operating range. When the battery temperature reaches the conformational change point, the hydrogel block 12 releases moisture to form a vapor layer. The hydrogel block 12 includes ion pairs with a redox potential difference. The buffer layer 14 is disposed on at least one side of the hydrogel block 12.

[0024] Each of the electrodes 13 at least partially surrounds the hydrogel block 12, and one end of the lead of each of the electrodes 13 extends out of the seal 11. The electrodes 13 are connected to an external resistor and a voltmeter and ammeter for monitoring the voltage and current signals of the hydrogel block 12. The voltage signal is used to provide feedback on the temperature difference between the two electrodes 13, and the current signal is used to provide feedback on the deformation of the hydrogel block and / or the deformation of the battery to be monitored.

[0025] In this invention, voltage and current signals generated by the migration speed of ion pairs and their concentration per unit length in the hydrogel block 12 provide real-time feedback on the battery's operating status, effectively enabling health monitoring and safety warnings of the battery's operating status. Furthermore, when thermal runaway occurs, the hydrogel block 12 releases moisture in a short time to form a vapor layer, effectively isolating the impact of sudden high temperatures on adjacent batteries. Simultaneously, the vapor breaks through the seal 11 and the battery pack, allowing heat to be carried away in the form of water vapor, automatically preventing catastrophic consequences such as a complete explosion of the entire battery pack.

[0026] In one embodiment, the ion pair includes FeCl2 / FeCl3, dicyandiamide / guanidine salt ions, , One or more of them.

[0027] In one embodiment, the hydrogel block 12 is obtained from a precursor solution polymer, the precursor solution comprising water, a polymeric monomer, and the ion pair, wherein the polymeric monomer is a water-soluble polymer and / or a hydrophilic polymer.

[0028] The water content in the hydrogel block is ≥80% by mass, so that the hydrogel block 12 of the same volume can carry away more heat when releasing water vapor.

[0029] Specifically, the monomers are selected from one or more of polysaccharide compounds, polypeptide compounds, acrylic acid and its derivatives. Precursor solution polymerization can be carried out by photopolymerization or thermal polymerization, and different initiators are used under different polymerization conditions to form hydrogel blocks 12.

[0030] In one embodiment, the concentration of ion pairs in the precursor solution is 0.01 mol·L⁻¹. -1 ~1 mol·L -1 Within this concentration range, electrode 13 is highly sensitive in monitoring the voltage and current signals of the hydrogel block 12.

[0031] In one embodiment, there are two hydrogel blocks 12, and each hydrogel block 12 is provided with one electrode 13. The buffer layer 14 is disposed between the two hydrogel blocks 12 to buffer the stress generated by the expansion and contraction of the battery during charging and discharging.

[0032] In one embodiment, the thickness of the hydrogel block 12 is 0.1~10mm.

[0033] In one embodiment, the thickness of the buffer layer 14 is 0.1~2mm.

[0034] In one embodiment, the buffer layer 14 is one or more of foam, filament felt, and aerogel. Specifically, the foam is a material made of foamed plastic particles, which makes the buffer layer 14 compressible.

[0035] In one embodiment, the seal 11 is provided with a vent valve or a weak point for pressure relief. When the battery experiences thermal runaway, if too much vapor is generated, the pressure in the containment cavity will be greater than the external air pressure, which may cause the seal 11 to rupture, exposing the hydrogel block 12 inside the battery pack. By providing a vent valve, when the pressure inside the containment cavity reaches a critical value, the vapor can force open the vent valve to relieve pressure and release heat, preventing the hydrogel block 12 from scattering inside the battery pack.

[0036] In one embodiment, the sealing element 11 is an aluminum-plastic film or plastic film that isolates moisture. And / or, the electrode 13 is a carbon paper electrode 13 with leads.

[0037] In a specific embodiment, the hydrogel block 12 can absorb and retain a large amount of moisture at the normal operating temperature of the battery (-40℃~60℃). When the battery encounters a sudden high temperature (100℃~150℃), the hydrogel block 12 can quickly release moisture, carry away the heat, and form a vapor layer due to the Leidenfrost phenomenon, preventing heat spread and reducing the impact of the sudden high temperature on adjacent cells. When the pressure inside the containment cavity reaches a critical value, the vapor can force open the vent valve to release pressure and heat.

[0038] One embodiment of this utility model provides a battery pack, including a battery cell 20, a battery management system 30, and a battery safety sensing protective film 10 as described above. The battery safety sensing protective film 10 is disposed on one side of the battery cell 20, and / or, the battery safety sensing protective film 10 is disposed between two adjacent battery cells 20. The sealing member 11 abuts against the battery cell 20. The electrode 13 is electrically connected to the battery management system 30.

[0039] Specifically, the size of the battery safety sensing protective film 10 is the same as the area of ​​the side of the battery cell 20 facing the battery safety sensing protective film 10, so that the battery safety sensing protective film 10 completely covers the surface of the battery cell 20.

[0040] It should be noted that the seal 11 can also be bonded to the battery cell 20, and deforms as the battery cell 20 expands or contracts.

[0041] In one embodiment, the lead extending from the seal 11 on the electrode 13 is connected to the battery management system 30 via a wire, or the electrode 13 is wirelessly connected to the battery management system 30.

[0042] Specifically, the redox potential of the ion pair is a function of temperature. The battery safety sensing protective film 10 is disposed on one side of the battery cell 20. The heat of the battery cell 20 is conducted to the hydrogel block 12. When there is a temperature difference ΔT between the two electrodes 13 of the battery safety sensing protective film 10, a certain potential difference ΔV will be generated. Similar to solid thermoelectric materials or thermocouples, the ratio of the two is the Seebeck coefficient S. i :

[0043] ,

[0044] in, It is the entropy change of a redox reaction. n It is the number of electrons in the reaction process. F It is Faraday's constant.

[0045] Electrode 13 feeds this potential difference back to the battery management system 30, enabling the battery management system 30 to acquire temperature sensing capabilities and monitor the temperature of the cell 20. When thermal runaway occurs in the cell, the battery management system 30 monitors it through electrode 13 and takes active measures such as limiting current, isolating, and extinguishing fires to ensure the safety of the battery pack.

[0046] When the battery cell 20 expands, the hydrogel block 12 is subjected to pressure from the battery cell 20, causing deformation. Depending on the magnitude of the pressure from the battery cell 20, the ion concentration per unit length within the hydrogel block 12 changes, thus affecting the resistivity of the hydrogel block. The relationship between the resistance R of the hydrogel block and its deformation and resistivity is as follows:

[0047]

[0048] in, ρ It is the resistivity of the hydrogel block. L It refers to the thickness of the hydrogel block. S It is the cross-sectional area of ​​the hydrogel block.

[0049] Under a certain voltage, the change in the resistance of the hydrogel block manifests as a change in the output current. Electrode 13 feeds back the current change to the battery management system 30, enabling the battery management system 30 to acquire pressure sensing capability and monitor the degree of deformation of the cell 20.

[0050] Furthermore, the deformation degree δ of the battery cell 20 is the amount of change in the thickness of the hydrogel block. Where L0 is the initial thickness of the hydrogel block, and L1 is the thickness of the hydrogel block after the cell is deformed. When δ is between 0% and 60%, the battery pack is in a safe state; when δ exceeds this range, the battery management system 30 takes limiting measures to ensure battery safety.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A battery safety sensing protective film, characterized in that, The battery includes a seal, a hydrogel block, a buffer layer, and at least two electrodes. The seal has a receiving cavity, and the hydrogel block is disposed within the receiving cavity. The hydrogel block has a conformational change point adapted to the battery's operating range. When the battery temperature reaches the conformational change point, the hydrogel block releases moisture to form a vapor layer. The hydrogel block contains ion pairs with a redox potential difference. The buffer layer is disposed on at least one side of the hydrogel block. Each of the electrodes at least partially surrounds the hydrogel block, and one end of the lead of each electrode extends out of the seal. The electrodes are connected to an external resistor and a voltmeter and ammeter for monitoring the voltage and current signals of the hydrogel block. The voltage signal is used to provide feedback on the temperature difference between the two electrodes, and the current signal is used to provide feedback on the deformation of the hydrogel block and / or the deformation of the battery to be monitored.

2. The battery safety sensing protective film according to claim 1, characterized in that, The number of hydrogel blocks is two, and each hydrogel block is provided with one electrode. The buffer layer is disposed between the two hydrogel blocks.

3. The battery safety sensing protective film according to claim 1, characterized in that, The thickness of the buffer layer is 0.1~2mm.

4. The battery safety sensing protective film according to claim 1, characterized in that, The buffer layer is one or more of foam, fine felt, and aerogel.

5. The battery safety sensing protective film according to claim 1, characterized in that, The thickness of the hydrogel block is 0.1~10mm.

6. The battery safety sensing protective film according to claim 4, characterized in that, The water content in the hydrogel block is ≥80% by mass.

7. The battery safety sensing protective film according to claim 1, characterized in that, The sealing element is provided with a venting valve or a weak point for venting pressure relief.

8. The battery safety sensing protective film according to claim 1, characterized in that, The sealing element is an aluminum-plastic film or plastic film that isolates moisture; and / or, the electrode is a carbon paper electrode with leads.

9. A battery pack, characterized in that, The device includes a battery cell, a battery management system, and a battery safety sensing protective film as described in any one of claims 1 to 8, wherein the battery safety sensing protective film is disposed on one side of the battery cell, and / or, the battery safety sensing protective film is disposed between two adjacent battery cells, and the sealing member abuts against the battery cell; the electrode is electrically connected to the battery management system.

10. The battery pack according to claim 9, characterized in that, The electrode extends from the seal and is connected to the battery management system via a wire, or the electrode is wirelessly connected to the battery management system.

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