Open vented pressure relief lithium battery module

Abstract

This utility model provides an open-type pressure relief lithium battery module. The cover is a C-shaped frame structure with an opening facing downwards. At least one row of grooves is provided on the upper surface of the top plate of the cover. A row of through pressure relief holes is provided on the bottom surface of the grooves. The pressure relief holes correspond one-to-one with the positions of the explosion-proof valves of the battery cells inside the box. A membrane is located in the grooves and covers the upper surface of the pressure relief holes. The membrane has waterproof and breathable functions. When the battery cell experiences thermal runaway, the gas-liquid-solid mixture is ejected from the battery cell explosion-proof valve and then discharged directly upwards through the through holes designed on the top of the cover. This achieves rapid release of the internal pressure of the battery cell over the shortest distance while avoiding contact between the flammable mixture and the internal components of the box, ultimately achieving a thermoelectric separation effect.

Description

Technical Field

[0001] This utility model relates to the field of lithium-ion batteries, and in particular to an open-type pressure-relief lithium battery module. Background Technology

[0002] When designing lithium-ion battery system integration, it is necessary to consider the possibility of thermal runaway or other abnormal situations occurring within the battery cell. In such cases, a large amount of high-temperature, high-pressure gas will be generated inside the battery pack. To prevent the battery pack from exploding, a certain number of pressure relief and explosion-proof valves need to be installed on the battery pack. This solution has been successfully implemented in numerous power and energy storage battery systems. However, this solution cannot completely prevent the casing from exploding in extreme situations (multiple or all cells experiencing simultaneous thermal runaway). Furthermore, the gas-liquid-solid mixture ejected during cell thermal runaway can easily cause secondary hazards such as arcing and short circuits within the casing.

[0003] The implementation of thermoelectric separation technology after thermal runaway in lithium-ion battery systems, the high cost of battery system components, and how to improve the structural strength and volumetric energy density of the battery pack have always been challenging issues in the industry. This patent addresses these challenges by providing corresponding solutions, offering new ideas for achieving thermoelectric separation of the battery pack, improving the mechanical strength of the battery system, reducing costs, and increasing the volumetric energy density of the battery pack. (Utility Model Content) The purpose of this utility model is to overcome the shortcomings of the existing technology. To achieve the above objective, this utility model adopts the following technical solution: An open-type pressure-relief lithium battery module includes: a housing, comprising a bottom and a cover, the cover fitting over the bottom and forming a cavity for accommodating the module, the module comprising multiple battery cells arranged in a rectangular array; the cover having a downward-opening U-shaped frame structure; at least one row of grooves on the upper surface of the top plate of the cover, and a row of through pressure relief holes on the bottom surface of the grooves, the pressure relief holes corresponding one-to-one with the positions of the explosion-proof valves of the battery cells inside the housing; and a membrane located within the grooves and covering the upper surface of the pressure relief holes, the membrane having waterproof and breathable functions.

[0004] The main function of the membrane is to prevent corrosive water vapor molecules from the outside of the battery pack from penetrating into the surface of the cell explosion-proof valve and causing the cell explosion-proof valve to fail. When the cell experiences thermal runaway, the gas-liquid-solid mixture is ejected from the cell explosion-proof valve and then discharged directly upward through the through hole designed on the top of the box cover. This achieves the shortest distance for rapid release of the internal pressure of the cell while avoiding contact between the flammable mixture and the internal components of the box, ultimately achieving the effect of thermoelectric separation.

[0005] More preferably, the film is made of expanded polytetrafluoroethylene.

[0006] More preferably, the size of the pressure relief hole is greater than or equal to the outer ring size of the battery cell explosion-proof valve.

[0007] More preferably, one end of the groove is located within the area defined by the outer edge contour of the top plate, and the other end of the groove extends through and beyond the outer edge of the top plate.

[0008] More preferably, the top cover of the battery cell is fixedly mounted with studs.

[0009] More preferably, the box cover has a through hole that mates with the stud; the box cover is locked and fixed to the stud by a nut.

[0010] More preferably, the explosion-proof valve is located in the middle of the two poles at the top of the battery cell.

[0011] Compared with the prior art, the beneficial effects of this utility model are as follows: This invention breaks through the limitations of traditional pack assembly, meeting the thermoelectric separation requirements after thermal runaway of the battery cell. It can effectively avoid secondary hazards caused by arcing, short circuits, etc., resulting from the gas-liquid-solid mixture ejected during thermal runaway of the battery cell. At the same time, it eliminates the pressure relief valve at the pack level, reducing the material cost of the pack. This solution rigidly connects the cover and the module, which can effectively improve the mechanical strength performance of the pack. Furthermore, this solution can reduce the height of the cover by about 10mm compared to the traditional solution, thereby increasing the volumetric energy density of the pack. Attached Figure Description

[0012] Figure 1 This is an exploded view of the present invention; Figure 2 This is an assembly diagram of the present invention; Figure 3 This is a schematic diagram of the box lid.

[0013] In the diagram: bottom of the box 1, module 2, box cover 3, film 4, nut 5, stud 21, top plate 31, groove 32, pressure relief hole 33. Detailed Implementation

[0014] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0015] Reference Figures 1-3 An open-type pressure-relief lithium battery module, comprising: The box body includes a box bottom 1 and a box cover 3. The box cover 3 covers the box bottom 1 and forms a cavity for accommodating a module 2. The module 2 includes a plurality of battery cells arranged in a rectangular array. In one embodiment, such as Figure 1 and Figure 2 As shown, module 3 adopts a 1P26S assembly method, using square-shell lithium iron phosphate cells. The cell explosion-proof valve is designed in the middle of the two terminals on the top of the cell. During assembly, a certain gap is maintained between the cells to fill thermal safety protection material and buffer material to absorb cell expansion. Two high-strength metal or non-metal end plates 2 are designed at both ends of the module. After the end plates 2 and the cells are stacked in sequence, the cells and end plates are tightened by two steel straps to ensure that the strength of the entire module meets the national standard mechanical performance requirements. The module is bonded to the cells by thermally conductive structural adhesive on the surface of the liquid cooling plate of the housing, and the two ends of the module are fixed to the housing by bolts through the end plates.

[0016] The cover 3 is a U-shaped frame structure with the opening facing downwards; at least one row of grooves 32 is provided on the upper surface of the top plate 31 of the cover 3, and a row of through pressure relief holes 33 is provided on the bottom surface of the grooves 32, and the pressure relief holes 33 correspond one-to-one with the positions of the explosion-proof valves of the battery cells inside the box. In one embodiment, the cell explosion-proof valve is designed at the middle position of the two poles on the top of the cell, and the pressure relief hole 33 on the box cover 4 is located directly above the explosion-proof valve. When the cell inside the box experiences thermal runaway and opens the valve, the gas-liquid-solid mixture is sprayed out from the cell explosion-proof valve and then discharged upward through the pressure relief hole 43 designed on the top of the box cover.

[0017] In one embodiment, the module 3 adopts a 1P26S grouping method, with 4 groups of modules placed inside the box. Correspondingly, on each group of modules, the upper surface of the top plate 31 of the box cover 3 has four rows of corresponding grooves 32.

[0018] In one embodiment, the cover 4 is placed on the bottom 1 of the box, which accommodates the module 3 in the internal cavity; the module is bonded to the battery cell by the thermally conductive structural adhesive on the surface of the liquid cooling plate of the box, and the two ends of the module are fixed to the box by bolts through the end plate.

[0019] The film 4 is located within the groove 32 and covers the upper surface of the pressure relief hole 33. The film 4 has waterproof and breathable functions.

[0020] In this embodiment, the membrane 4 has waterproof and breathable functions. The main function of the membrane 4 is to prevent corrosive water vapor molecules from the outside of the battery pack from penetrating into the surface of the cell explosion-proof valve and causing the cell explosion-proof valve to fail. The membrane 4 needs to achieve the effect of "free passage of gas and complete blockage of liquid water" through a precise microporous structure design. In addition, the material of the membrane 4 needs to meet the requirements of high temperature resistance >600℃, resistance to electrolyte corrosion, flame retardancy, and sufficient tear resistance and puncture resistance to avoid damage during installation or vibration.

[0021] In this embodiment, the ejection of the battery cell is completely isolated from the battery cells and metal components inside the enclosure, preventing the aforementioned secondary hazards. When thermal runaway occurs in the battery cell, the gas-liquid-solid mixture is ejected from the battery cell explosion-proof valve and then discharged directly upwards through the through-hole designed on the top of the enclosure cover. This achieves rapid release of the internal pressure of the battery cell over the shortest distance while preventing the flammable mixture from contacting the internal components of the enclosure, ultimately achieving a thermoelectric separation effect.

[0022] In one embodiment, the film 4 is made of expanded polytetrafluoroethylene.

[0023] The size of the pressure relief hole 33 is greater than or equal to the outer ring size of the cell explosion-proof valve.

[0024] In this embodiment, the size of the pressure relief hole 33 is larger than the outer ring size of the cell explosion-proof valve, ensuring that all the gas-liquid-solid mixture ejected from the cell explosion-proof valve can enter the pressure relief hole 33; the membrane 4 only has waterproof and breathable functions and does not have the ability to block the gas-liquid-solid mixture. When the gas-liquid-solid mixture rushes towards the membrane 4, the membrane 4 will be torn by the force of the gas-liquid-solid mixture, causing the mixture to be directly ejected outside the box.

[0025] One end of the groove 32 is located within the area defined by the outer edge contour of the top plate 31, and the other end of the groove 32 extends through and beyond the outer edge of the top plate 31.

[0026] In this embodiment, to facilitate the installation of the film 4, one end of the groove 32 extends through the outer edge of the top plate 31, while the other end does not extend through. Glue is evenly applied at the contact position between the film 4 and the box cover 3, and then the film 4 is finally installed above the pressure relief hole 33 of the box cover by adhesive.

[0027] A stud 21 is fixedly installed on the surface of the top cover of the battery cell; the box cover 3 is provided with a through hole that mates with the stud 21; the box cover 3 is locked and fixed to the stud 21 by a nut 5.

[0028] In this embodiment, studs 21 are welded to the surface of the cell top cover. When the cover 3 is placed from top to bottom, the studs 21 pass through the through holes on the cover 3 and are then locked in place by nuts 5. The cover and the module are rigidly connected, which can effectively improve the mechanical strength performance of the pack. Furthermore, this solution does not require the reservation of vibration space for the module, and the height of the cover can be reduced by about 10mm compared to the traditional solution, thereby improving the volumetric energy density of the pack.

[0029] The explosion-proof valve is located in the middle of the two poles at the top of the battery cell.

[0030] To better understand this application, the embodiments of this patent are described below.

[0031] Module grouping: The square-shell battery cells first undergo preliminary testing, cleaning, and sheet bonding pre-processing. Then, the modules are pre-stacked according to the stacking sequence of end plate assembly - battery cell material assembly * 26 - end plate assembly. The stacked modules are then tightened with two steel strips, followed by welding of the CCS assembly. Finally, the module's off-line performance is tested.

[0032] Module into box: Before the module is placed into the box, thermally conductive structural adhesive must be applied to the surface of the liquid cooling plate of the box and electrical accessories must be installed. Then the module will be hoisted into the box. The bottom of the module is connected to the liquid cooling plate of the box through thermally conductive structural adhesive, and the two ends of the module are connected and fixed to the box module mounting beam with bolts.

[0033] Film installation: After the modules are installed and fixed in the box, a sealing foam strip with through holes is pasted on the top of each module. The bottom of the foam strip is backed with double-sided adhesive. When pasting, ensure that the explosion-proof valve of the battery cell is not blocked by the foam strip. Then, put the box cover on from the top of the box body downwards, and use hexagonal flange nuts to lock and fix the box cover by studs welded to the surface of the battery cell top cover. Finally, the waterproof and breathable membrane is installed on the top of the box cover vent hole with adhesive.

[0034] This invention breaks through the limitations of traditional pack assembly, meeting the thermoelectric separation requirements after thermal runaway of the battery cell. It can effectively avoid secondary hazards caused by arcing, short circuits, etc., resulting from the gas-liquid-solid mixture ejected during thermal runaway of the battery cell. At the same time, it eliminates the pressure relief valve at the pack level, reducing the material cost of the pack. This solution rigidly connects the cover and the module, which can effectively improve the mechanical strength performance of the pack. Furthermore, this solution can reduce the height of the cover by about 10mm compared to the traditional solution, thereby increasing the volumetric energy density of the pack.

Claims

1. An open vented lithium battery module, characterized in that, include: The housing includes a bottom and a lid, the lid being fitted onto the bottom and forming a cavity for accommodating a module, the module including multiple battery cells arranged in a rectangular array; The box cover is a C-shaped frame structure with the opening facing downwards; the upper surface of the top plate of the box cover is provided with at least one row of grooves, and the bottom surface of the grooves is provided with a row of through pressure relief holes, and the pressure relief holes correspond one-to-one with the positions of the explosion-proof valves of the battery cells inside the box. A thin film is located within the groove and covers the upper surface of the pressure relief hole; the thin film is waterproof and breathable.

2. The open-type pressure-relief lithium battery module according to claim 1, characterized in that, The film is made of expanded polytetrafluoroethylene.

3. The open-type pressure-relief lithium battery module according to claim 1, characterized in that, The size of the pressure relief hole is greater than or equal to the outer ring size of the cell explosion-proof valve.

4. An open-type pressure-relief lithium battery module according to claim 3, characterized in that, One end of the groove is located within the area defined by the outer edge contour of the top plate, and the other end of the groove extends through and beyond the outer edge of the top plate.

5. An open-type pressure-relief lithium battery module according to claim 1, characterized in that, The top cover of the battery cell is fixedly mounted with studs.

6. An open-type pressure-relief lithium battery module according to claim 5, characterized in that, The box cover has a through hole that mates with the stud; the box cover is locked and fixed to the stud by a nut.

7. An open-type pressure-relief lithium battery module according to claim 1, characterized in that, The explosion-proof valve is located in the middle of the two poles at the top of the battery cell.

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