Thermoelectrically separated lithium battery module

Abstract

The utility model provides a kind of lithium battery module of thermoelectric separation, the box cover is covered on the box bottom and is surrounded to form the cavity with containing module, the module includes multiple battery cell of rectangular arrangement arrangement;At least one row of grooves is opened in the upper surface of the box cover top plate, a row of through pressure relief hole is opened in the bottom surface of the groove, the position of the pressure relief hole and the explosion-proof valve of the battery cell inside the box body one-to-one corresponds;The bottom surface of the groove is sealed and pasted with the gas-liquid-solid mixture directional pressure relief of the pressure relief pipe that battery cell thermal runaway spouts;The utility model breaks through the limit of traditional pack group, meets the thermoelectric separation demand after battery cell thermal runaway, can effectively avoid the secondary harm caused by arc, short circuit etc. of gas-liquid-solid mixture spouted when battery cell thermal runaway;Cancel the pressure relief valve of Pack level simultaneously, reduce Pack material cost.

Description

Technical Field

[0001] This utility model relates to the field of lithium-ion batteries, and in particular to a lithium battery module with thermoelectric separation. 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 challenges of thermoelectric separation after thermal runaway in lithium-ion battery systems, the high cost of battery system components, and how to improve the structural strength of the pack have always been difficult and painful issues in the industry. This patent provides corresponding solutions to these challenges, offering new ideas for achieving thermoelectric separation of the pack, improving the mechanical strength of the battery system, and reducing costs. Utility Model Content

[0004] 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: A thermoelectrically separated 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 a plurality of battery cells arranged in a rectangular array; at least one row of grooves is formed on the upper surface of the top plate of the cover, and a row of through-hole pressure relief holes is formed 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; a pressure relief pipe is sealed and affixed to the bottom surface of the grooves to directionally relieve the pressure of the gas-liquid-solid mixture ejected during thermal runaway of the battery cells; when the battery cells inside the housing experience thermal runaway and the valves open, the gas-liquid-solid mixture is ejected from the explosion-proof valves of the battery cells, then discharged into the pressure relief pipe through the pressure relief holes designed on the top of the cover, and then directionally discharged through the pressure relief pipe.

[0005] More preferably, the cross-sectional shape of the pressure relief pipe is a hollow trapezoidal structure, and the side of the pressure relief pipe near the groove has an oblong hole that communicates with the pressure relief hole.

[0006] More preferably, one end of the pressure relief pipe is sealed, and the other end extends out of the box cover and is covered with a waterproof and breathable film.

[0007] More preferably, the pressure relief pipe and the groove, and the box cover and the battery cell are all sealed and connected by a sealing strip and structural adhesive, and the sealing strip is provided with a clearance hole corresponding to the pressure relief hole or the explosion-proof valve.

[0008] 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.

[0009] More preferably, the size of the waist-shaped hole is greater than or equal to the outer ring size of the pressure relief hole.

[0010] 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 the outer edge of the top plate.

[0011] More preferably, the lid is a C-shaped frame structure with the opening facing downwards.

[0012] 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, meets the thermoelectric separation requirements after thermal runaway of the battery cell, and can effectively avoid secondary hazards caused by electric arcs, short circuits, etc. caused by 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. Attached Figure Description

[0013] 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 structure; Figure 4 This is a schematic diagram of the pressure relief pipe.

[0014] In the diagram: 1. Box bottom; 2. Module; 3. Box cover; 4. Pressure relief pipe; 5. Membrane; 6. Sealing strip; 31. Top plate; 32. Groove; 33. Pressure relief hole; 41. Waist-shaped hole. Detailed Implementation

[0015] 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.

[0016] Reference Figures 1-4 A thermoelectrically separated 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 an embodiment, such as Figure 1 and Figure 2 As shown, module 3 uses a 1P26S assembly method, employing prismatic lithium iron phosphate cells. The cell explosion-proof valve is located precisely in the middle of the two terminals at the top of the cell. During assembly, a certain gap is maintained between the cells to accommodate thermal safety protection material and buffer material to absorb cell expansion. Two high-strength metal or non-metal end plates are designed at both ends of the module. After the end plates and cells are stacked sequentially, two steel straps are used to tighten the cells and end plates, ensuring the overall module strength meets national standard mechanical performance requirements. The module is bonded to the cells using thermally conductive structural adhesive on the surface of the liquid cooling plate of the housing, and both ends of the module are bolted to the housing via the end plates.

[0017] The top plate 31 of the box cover 3 has at least one row of grooves 32 on its upper surface. A row of through pressure relief holes 33 is opened on the bottom surface of the grooves 32. The pressure relief holes 33 correspond one-to-one with the positions of the explosion-proof valves of the battery cells inside the box. A pressure relief pipe 4 is sealed and affixed to the bottom surface of the grooves 32 to directionally relieve the pressure of the gas-liquid-solid mixture ejected when the battery cells thermally run away.

[0018] In one embodiment, the cell explosion-proof valve is designed in the middle of the two poles on the top of the cell. The pressure relief hole 33 on the box cover 3 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 into the pressure relief pipe 4 through the pressure relief hole 33 designed on the top of the box cover. The gas-liquid-solid mixture is then discharged in a directional manner through the pressure relief pipe 4.

[0019] In one embodiment, the module 3 adopts a 1P26S grouping method, and four groups of modules are placed inside the box. Correspondingly, on each group of modules, four rows of corresponding grooves 32 are opened on the upper surface of the top plate 31 of the box cover 3, and a pressure relief pipe 4 is fixedly installed in each groove 32.

[0020] The pressure relief pipe 4 has a hollow trapezoidal cross-section. The side of the pressure relief pipe 4 near the groove has an oblong hole 41 that communicates with the pressure relief hole. One end of the pressure relief pipe 4 is sealed, and the other end extends out of the box cover 3 and is covered with a waterproof and breathable film 5.

[0021] In one embodiment, the hollow structure inside the pressure relief pipe 4 serves as a pressure relief channel for discharging the gas-liquid-solid mixture. The waist-shaped hole 41 on the pressure relief pipe 4 is a channel that matches and corresponds to the pressure relief hole 33 on the cover, so that the gas-liquid-solid mixture ejected during thermal runaway of the battery cell can be smoothly discharged from the pipeline. The cross-sectional area of ​​the inner cavity of the pressure relief pipe 4 is designed to meet the straight-through area requirements during thermal runaway of the battery cell.

[0022] In one embodiment, the membrane 5 has waterproof and breathable functions, and the membrane 4 is made of expanded polytetrafluoroethylene. The main function of the membrane 5 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 5 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.

[0023] The pressure relief pipe 4 and the groove, as well as the box cover 3 and the battery cell, are sealed and connected by a sealing strip 6 and structural adhesive. The sealing strip 6 has a clearance hole corresponding to the pressure relief hole or the explosion-proof valve.

[0024] In this embodiment, the first interface is the seal between the inner surface of the cover 3 and the top cover of the battery cell, which is composed of structural adhesive and sealing strip. Its main purpose is to prevent the gas-liquid-solid mixture after thermal runaway of the battery cell from being discharged from this sealed interface to other components in the box, thereby avoiding secondary damage and playing a key role in thermal-electric separation. The second interface is the seal between the outer surface of the cover and the pressure relief pipeline, which is also composed of structural adhesive and sealing strip. Its main function is to prevent the discharge after thermal runaway from being sprayed out from this interface and losing the guiding function of the channel.

[0025] In this embodiment, the cover is designed with a pressure relief hole 33 corresponding to the pressure relief valve of the battery cell. A certain gap is left between the cover and the battery cell for filling with structural adhesive. On the one hand, this ensures the sealing performance between the cover and the battery cell, and on the other hand, it provides a larger Z-direction constraint force to the cover, thereby improving the rigidity of the entire package.

[0026] In this embodiment, the sealing strip 6 has an avoidance hole to ensure that the sealing strip does not block the cell explosion-proof valve and the pressure relief hole 33. Then, structural adhesive is evenly applied to the connection position of the sealing strip 6 and bonded and fixed by the structural adhesive.

[0027] The size of the pressure relief hole 33 is greater than or equal to the outer ring size of the cell explosion-proof valve.

[0028] 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 the gas-liquid-solid mixture ejected from the cell explosion-proof valve can all enter the pressure relief hole 33.

[0029] The size of the waist-shaped hole 41 is greater than or equal to the outer ring size of the pressure relief hole 33.

[0030] In this embodiment, the size of the waist-shaped hole 41 is greater than or equal to the outer ring size of the pressure relief hole 33, ensuring that the gas-liquid-solid mixture ejected from the cell explosion-proof valve can directly enter the waist-shaped hole 41 through the pressure relief hole 33.

[0031] 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 extends through the outer edge of the top plate.

[0032] In one embodiment, one end of the groove 32 extends through the outer edge of the top plate 31, while the other end does not. At the end where the groove extends, the pressure relief pipe 4 protrudes from the groove 32, which can directionally guide the gas-liquid-solid mixture ejected by the cell explosion-proof valve out of the housing. Structural adhesive is evenly applied at the contact position between the pressure relief pipe 4 and the groove 32. The pressure relief pipe 4 is installed directly above the sealing strip inside the groove 32, and the top surface of the pressure relief pipe 4 is pressed with a tool to maintain pressure. At the same time, adhesive is applied to the top surface of the pressure relief pipe to bond the pressure relief pipe to the housing cover. Finally, a waterproof and breathable membrane 5 is installed at the outlet of the pressure relief pipe.

[0033] The box cover 3 is a C-shaped frame structure with an opening facing downwards.

[0034] In this embodiment, the cover 3 is placed on the bottom 1 of the box, which accommodates the module 2 in the internal cavity. The module 2 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.

[0035] To better understand this application, the embodiments of this patent are described below.

[0036] 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.

[0037] 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.

[0038] Installation of pressure relief pipe: Sealing installation between the inside of the box cover and the top cover of the battery cell: After the modules are installed and secured in the enclosure, a sealing foam strip with through holes is attached to the top of each module. Double-sided adhesive is applied to both sides of the foam strip, ensuring that the explosion-proof valve of the battery cell is not obstructed. Structural adhesive is then applied to both sides of the foam strip, ensuring that the adhesive does not seep into the surface of the explosion-proof valve. Next, the enclosure cover is placed from the top down and pressed down with a tool to maintain pressure and ensure the adhesive has cured completely. While maintaining pressure, bolts are used to secure the enclosure cover to the outer side beam of the enclosure.

[0039] Sealing installation of the tank cover and pressure relief pipe: After completing the above pressure holding operation, attach the top sealing strip with the through hole to the top surface of the box cover, ensuring that the sealing strip does not obstruct the explosion-proof valve of the battery cell. Then, apply structural adhesive evenly to the connection position between the pressure relief pipe and the surface of the box cover. Next, install the pressure relief pipe directly above the top sealing strip and use a tool to press the top surface of the pressure relief pipe to hold the pressure. At the same time, apply adhesive to the top surface of the pressure relief pipe to bond the pressure relief pipe to the box cover. Finally, install a waterproof and breathable membrane at the outlet of the pressure relief pipe.

[0040] This patented solution breaks through the limitations of traditional pack assembly, meets the thermoelectric separation requirements after thermal runaway of the battery cell, and can effectively avoid secondary hazards caused by electric arcs, short circuits, etc. caused by 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.

Claims

1. A thermoelectrically separated 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; A pressure relief pipe is installed on the outer surface of the enclosure. At least one row of grooves is provided on the upper surface of the enclosure top plate. 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 enclosure. A pressure relief pipe for directional pressure relief of the gas-liquid-solid mixture ejected when the battery cells undergo thermal runaway is sealed and adhered to the bottom surface of the grooves.

2. The thermoelectrically separated lithium battery module according to claim 1, characterized in that, The pressure relief pipe has a hollow trapezoidal cross-section, and an oblong hole communicating with the pressure relief hole is provided on the side of the pressure relief pipe near the groove.

3. The thermoelectrically separated lithium battery module according to claim 1, characterized in that, One end of the pressure relief pipe is sealed, and the other end extends out of the box cover and is covered with a waterproof and breathable membrane.

4. A thermoelectrically separated lithium battery module according to claim 1, characterized in that, The pressure relief pipe and the groove, as well as the box cover and the battery cell, are sealed and connected by sealing strips and structural adhesive. The sealing strip has clearance holes corresponding to the pressure relief hole or the explosion-proof valve.

5. A thermoelectrically separated 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.

6. A thermoelectrically separated lithium battery module according to claim 2, characterized in that, The size of the waist-shaped hole is greater than or equal to the outer ring size of the pressure relief hole.

7. A thermoelectrically separated lithium battery module according to claim 1, 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 the outer edge of the top plate.

8. A thermoelectrically separated lithium battery module according to claim 1, characterized in that, The lid is a C-shaped frame structure with an opening facing downwards.

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