Method for preventing thermal runaway in thermoelectric separation

Abstract

The invention provides a method for preventing thermal runaway in thermoelectric separation, and belongs to the technical field of secondary batteries. According to the method, all-around thermoelectric isolation protection is carried out on the battery module, the electrical circuit and the control element, and suitable insulating materials are selected for different parts for physical isolation, so that the battery can be effectively protected, and thermal runaway of the battery is prevented.

Description

Technical Field

[0001] The invention belongs to the technical field of secondary batteries, and in particular relates to a method for preventing thermal runaway in thermoelectric separation. Background Art

[0002] Lithium battery thermal runaway is caused by a short circuit inside the battery or interference from external forces (such as mechanical interference, electrical abuse, thermal abuse, etc.), which causes the diaphragm to melt, the positive and negative electrodes to short-circuit, and a violent chemical reaction inside the battery. The temperature rises sharply, and the increased temperature makes the chemical reaction more intense, forming a chain reaction, a vicious cycle, and eventually the battery catches fire and explodes. In this case, high-temperature eruption is easy to accumulate in the pressure relief channel, causing a high-voltage short circuit, and it is very easy to spread to adjacent batteries or electrical units.

[0003] The current thermoelectric separation technology is to separate the thermal runaway zone from the high and low voltage lines. The specific measure is to change the position of the explosion-proof valve so that the explosion-proof valve and the pole are far away. The explosion-proof valve is set on the side perpendicular to the pole, and this side is placed downward in the battery pack. This design has two advantages: one is that it can prevent the high-temperature objects ejected during thermal runaway from contacting the electrical connectors, causing further safety accidents; the second is the design of the bottom of the explosion-proof valve, which can transform the originally reserved bottom anti-collision channel design into an exhaust channel to further ensure thermoelectric separation. The explosion-proof valve and the pole are on the same side, but the battery cell is placed flat, with the positive and negative poles and the explosion-proof valve facing the side. When thermal runaway occurs, the high-temperature gas-liquid-solid mixture will be ejected to both sides of the module, minimizing the impact of "heat" on "electricity".

[0004] In addition, the current thermoelectric separation technology also uses the thermal management system integration method to achieve thermoelectric separation. Specifically, install thermal management components such as liquid cooling plates and heat pipes to efficiently transfer the heat generated by the battery to the thermal management components first, and at the same time reasonably arrange the positions of electrical components such as the battery management system (BMS) to avoid them being affected by heat transfer. During assembly, strictly follow the process to ensure that each component is firmly connected and functions normally, so as to achieve the thermoelectric separation effect.

[0005] However, for battery packs with a fixed structure, physical isolation is generally used to achieve thermal and electrical separation. The physical isolation method is to use specific insulating materials, such as high-performance insulating tapes and insulating sheets, to physically separate the heat-generating parts of the battery pack (such as battery modules) from key electrical components such as electrical connection lines. These insulating materials are precisely laid and wrapped to achieve thermal and electrical separation, and during operation, it is necessary to ensure that there are no omissions and that the fit is tight. However, existing physical isolation methods may not be able to cope with some extreme thermal environments or long-term thermal cycles. Over time, the insulating materials may age and cause thermal runaway. Summary of the invention

[0006] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, an embodiment of the present invention proposes a method for preventing thermal runaway in thermoelectric separation.

[0007] The embodiment of the present invention provides a method for preventing thermal runaway in thermoelectric separation, comprising the following steps:

[0008] S1. Preliminary preparation: Understand the internal structure of the battery pack, determine the layout and position of the battery module, electrical circuit, and control components, and design a cutting plan based on the size specifications of the selected insulating material, and prepare cutting tools and high-temperature resistant glue;

[0009] S2. Physical isolation operation:

[0010] For the battery module, using the high temperature resistant glue to lay the cut ceramic fiber paper and / or mica sheet on the outer surface of the battery module;

[0011] For the electrical circuit, use glass fiber cloth to wrap the electrical circuit;

[0012] For the control element, the cut ceramic fiber paper is laid on the bottom of the control element using the high temperature resistant glue, and then the cut mica sheets are placed around the control element using the high temperature resistant glue, and finally the control element is wrapped with glass fiber cloth;

[0013] S3. Subsequent inspection and improvement: After completing the physical isolation operation, the battery pack should be inspected to see whether the insulating material is tightly fitted and whether there is any damage or gap. Any problems found should be repaired and improved in a timely manner.

[0014] The advantages and technical effects brought by the method of the embodiment of the present invention are as follows:

[0015] (1) The method of the embodiment of the present invention provides all-round thermal and electrical isolation protection for the battery module, electrical circuits, and control elements, thereby preventing thermal runaway of some components from affecting other components.

[0016] (2) For the battery module, ceramic fiber paper and / or mica sheets are selected and laid on the outer surface of the battery module, which can effectively provide thermal and electrical isolation protection for the battery module.

[0017] (3) For the electrical circuit, glass fiber cloth is used to wrap the electrical circuit. The glass fiber cloth has good flexibility and is easy to wrap. The glass fiber cloth can maintain stable insulation performance over a wide temperature range. Wrapping the electrical circuit can prevent thermal and electrical interference between the electrical circuit and surrounding heat-generating or conductive components, thereby ensuring the thermal and electrical separation effect.

[0018] (4) For the control element, using a combination of ceramic fiber paper, mica sheet, and glass fiber cloth for isolation and protection is more effective than using only one material for isolation and protection.

[0019] (5) The method of the embodiment of the present invention also includes a subsequent inspection and improvement in step S3 to avoid omissions in physical isolation operations and further reduce the risk of thermal runaway of the battery.

[0020] According to the method of the embodiment of the present invention, in step S2, if there are gaps between the battery modules, the cut insulating sheets and / or mica sheets are filled into the gaps between the battery modules.

[0021] According to the method of an embodiment of the present invention, in step S2, the shape of the insulating sheet and / or mica sheet is the same as the shape of the side of the battery module, and the area of ​​the insulating sheet and / or mica sheet is greater than or equal to the area of ​​the side of the battery module.

[0022] According to the method of an embodiment of the present invention, in step S2, if the electrical circuit is relatively thin, the glass fiber cloth is cut into strips, and then the strip-shaped glass fiber cloth is tightly wrapped around the electrical circuit in multiple layers, and the interface of the glass fiber cloth is fixed with the high temperature resistant glue.

[0023] According to the method of the embodiment of the present invention, in step S2, the electrical circuit is wrapped with glass fiber cloth so as to cover the entire electrical circuit from the starting end to the end.

[0024] According to the method of the embodiment of the present invention, the electrical circuit includes a bus bar connected to the battery module and a lead-out power line.

[0025] According to the method of an embodiment of the present invention, in step S2, the area and shape of the ceramic fiber paper are the same as the area and shape of the bottom of the control element; and / or the area and shape of the mica sheet are the same as the area and shape of the side of the control element.

[0026] According to the method of the embodiment of the present invention, the control element includes a battery management system. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0028] The embodiment of the present invention provides a method for preventing thermal runaway in thermoelectric separation, comprising the following steps:

[0029] S1. Preliminary preparation: Understand the internal structure of the battery pack, determine the layout and position of the battery module, electrical circuit, and control components, and design a cutting plan based on the size specifications of the selected insulating material, and prepare cutting tools and high-temperature resistant glue;

[0030] S2. Physical isolation operation:

[0031] For the battery module, using the high temperature resistant glue to lay the cut ceramic fiber paper and / or mica sheet on the outer surface of the battery module;

[0032] For the electrical circuit, use glass fiber cloth to wrap the electrical circuit;

[0033] For the control element, the cut ceramic fiber paper is laid on the bottom of the control element using the high temperature resistant glue, and then the cut mica sheets are placed around the control element using the high temperature resistant glue, and finally the control element is wrapped with glass fiber cloth;

[0034] S3. Subsequent inspection and improvement: After completing the physical isolation operation, the battery pack should be inspected to see whether the insulating material is tightly fitted and whether there is any damage or gap. Any problems found should be repaired and improved in a timely manner.

[0035] The method of the embodiment of the present invention provides all-round thermal and electrical isolation protection for battery modules, electrical circuits, and control elements, and selects suitable insulating materials for different components for physical isolation, which can effectively protect the battery and prevent thermal runaway of the battery.

[0036] According to the method of the embodiment of the present invention, in step S2, if there are gaps between the battery modules, the cut insulating sheets and / or mica sheets are filled into the gaps between the battery modules. This can insulate and isolate adjacent battery modules from each other, preventing thermal runaway of one battery from spreading to adjacent battery modules.

[0037] According to the method of the embodiment of the present invention, in step S2, the shape of the insulating sheet and / or mica sheet is the same as the shape of the side of the battery module, and the area of ​​the insulating sheet and / or mica sheet is greater than or equal to the area of ​​the side of the battery module. In this way, the coverage area can completely isolate the battery module from possible conductive and thermal conduction paths in the surrounding area.

[0038] According to the method of the embodiment of the present invention, in step S2, if the electrical circuit is relatively thin, the glass fiber cloth is cut into strips, and then the strips of glass fiber cloth are tightly wound on the electrical circuit in multiple layers, and the interface of the glass fiber cloth is fixed with the high temperature resistant glue. Using the strips of glass fiber cloth makes it easier to tightly wind the electrical circuit.

[0039] According to the method of the embodiment of the present invention, in step S2, the electrical circuit is wrapped with glass fiber cloth, and the electrical circuit is covered from the starting end to the end. Compared with wrapping only part of the electrical circuit, wrapping the entire electrical circuit can form a more effective isolation protection.

[0040] According to the method of the embodiment of the present invention, the electrical circuit includes a bus bar connected to the battery module and a lead-out power line.

[0041] According to the method of the embodiment of the present invention, in step S2, the area and shape of the ceramic fiber paper are the same as the area and shape of the bottom of the control element; and / or the area and shape of the mica sheet are the same as the area and shape of the side of the control element. This is more conducive to the bonding of the ceramic fiber paper, the mica sheet and the control element, and reduces the gap between the outer glass fiber cloth and the inner control element.

[0042] According to the method of the embodiment of the present invention, the control element includes a battery management system.

[0043] The present invention is described in detail below with reference to embodiments.

[0044] Example 1

[0045] Preliminary preparation: Before performing physical isolation operations, you need to have a clear understanding of the internal structure of the battery pack, determine the layout and position of key components such as battery modules, electrical circuits, and control elements, and design a cutting plan based on the size specifications of the selected insulating material, prepare cutting tools such as scissors, utility knives, etc., as well as auxiliary materials such as high-temperature resistant glue for pasting and fixing.

[0046] Isolation Operation:

[0047] - For battery modules, ceramic fiber paper or mica sheets can be used to lay along the edge of the module and cover the outer surface of the battery module. If there are gaps between modules, cut insulation sheets and / or mica sheets can also be used to fill them in. The coverage area must ensure that the module can be completely isolated from possible conductive and thermal conduction paths around it. For example, in a battery pack composed of square battery modules, the insulation sheets and / or mica sheets are cut into shapes that match the size of the module side and inserted into the gaps between the modules one by one for isolation.

[0048] - For the electrical circuits, such as the busbars connecting the battery modules and the power cables, they can be wrapped with glass fiber cloth. It is necessary to ensure that the wrapping is tight and covers the entire circuit from the beginning to the end to avoid partial exposure that may cause heat and electricity to affect each other. For example, for thinner power cables, the glass fiber cloth can be cut into strips, tightly wrapped in multiple layers, and the interface can be fixed with glue.

[0049] -For control components such as battery management systems (BMS), a combination of multiple layers of insulating materials can be used for isolation and protection. For example, a layer of ceramic fiber paper is first laid on the bottom of the component as a basic insulation layer, then surrounded by mica sheets, and finally wrapped with glass fiber cloth to form a full range of thermal and electrical isolation protection.

[0050] Subsequent inspection and improvement: After completing the physical isolation operation, the entire battery pack should be carefully inspected to see whether the insulating materials are tightly fitted and whether there are any damage or gaps. Any problems found should be repaired and improved in a timely manner, such as re-pasting and fixing loose insulating sheets, replacing damaged materials, etc., to ensure that the physical isolation achieves the expected thermal and electric separation effect and ensures the safe and stable operation of the battery pack.

[0051] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0052] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preventing thermal runaway in thermoelectric separation, characterized in that: The following steps are involved: S1. Preliminary preparation: Understand the internal structure of the battery pack, determine the layout and position of the battery module, electrical circuit, and control components, and design a cutting plan based on the size specifications of the selected insulating material, and prepare cutting tools and high-temperature resistant glue; S2. Physical isolation operation: For the battery module, using the high temperature resistant glue to lay the cut ceramic fiber paper and / or mica sheet on the outer surface of the battery module; For the electrical circuit, use glass fiber cloth to wrap the electrical circuit; For the control element, the cut ceramic fiber paper is laid on the bottom of the control element using the high temperature resistant glue, and then the cut mica sheets are placed around the control element using the high temperature resistant glue, and finally the control element is wrapped with glass fiber cloth; S3. Subsequent inspection and improvement: After completing the physical isolation operation, the battery pack should be inspected to see whether the insulating material is tightly fitted and whether there is any damage or gap. Any problems found should be repaired and improved in a timely manner.

2. The method according to claim 1, characterized in that In step S2, if there are gaps between the battery modules, the cut insulating sheets and / or mica sheets are filled into the gaps between the battery modules.

3. The method according to claim 2, characterized in that In step S2, the shape of the insulating sheet and / or mica sheet is the same as the shape of the side surface of the battery module, and the area of ​​the insulating sheet and / or mica sheet is greater than or equal to the area of ​​the side surface of the battery module.

4. The method according to claim 1, characterized in that: In step S2, if the electrical circuit is relatively thin, the glass fiber cloth is cut into strips, and then the strip-shaped glass fiber cloth is tightly wound on the electrical circuit in multiple layers, and the interface of the glass fiber cloth is fixed with the high temperature resistant glue.

5. The method according to claim 1, characterized in that In step S2, the electrical circuit is wrapped with glass fiber cloth to cover the electrical circuit from the starting end to the end.

6. The method according to claim 1, characterized in that The electrical circuit includes a bus bar connected to the battery module and a lead-out power line.

7. The method according to claim 1, characterized in that In step S2, the area and shape of the ceramic fiber paper are the same as the area and shape of the bottom of the control element; and / or the area and shape of the mica sheet are the same as the area and shape of the side of the control element.

8. The method according to claim 1, characterized in that The control element includes a battery management system.