A lithium battery module

Abstract

The utility model provides a kind of lithium battery module, the upper surface of the box cover is equipped with at least one row of grooves, the bottom surface of the groove is equipped with a row of pressure relief hole, the position of the pressure relief hole and the explosion-proof valve of the battery inside the box body one-to-one correspondence;Pressure relief device, fixed on the upper surface of the box cover;The pressure relief device has the pressure relief passage and pressure relief accommodating cavity that communicate with pressure relief hole, the pressure relief accommodating cavity has flexible membrane that expands and shrinks and occurs elastic deformation with the variation of fluid or gas content;The utility model breaks through the limit of traditional pack group, meets the demand of thermoelectric separation after battery thermal runaway, can effectively avoid the secondary harm caused by the electric arc, short circuit etc. of gas-liquid-solid mixture produced when battery thermal runaway;Meanwhile, cancel the pressure relief valve of Pack level, reduce Pack material cost;And this scheme rigidly connects box cover and module, can effectively improve the mechanical strength performance of Pack.

Description

Technical Field

[0001] This utility model relates to the field of lithium-ion batteries, and in particular to a 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 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 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; the upper surface of the cover having at least one row of grooves, the bottom surface of the grooves having a row of through pressure relief holes, 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 device fixed to the upper surface of the cover; the pressure relief device having a pressure relief channel communicating with the pressure relief holes and a pressure relief accommodating cavity, the pressure relief accommodating cavity having a flexible membrane that expands and contracts elastically with changes in fluid or gas content.

[0005] When the battery cell inside the enclosure experiences thermal runaway and opens its valve, the gas-liquid-solid mixture is ejected from the battery cell's explosion-proof valve and then discharged upwards through the through-hole designed on the top of the enclosure cover. When a certain pressure difference is reached between the channel between the enclosure cover and the pressure relief device and the inner cavity of the flexible membrane, the one-way pressure relief valve on the pressure relief device opens. Because it is a one-way valve, the gas can only be discharged from bottom to top and cannot be discharged in the reverse direction, which can effectively protect other channels between the pressure relief device and the enclosure cover from being invaded by the mixture ejected from the battery cell. After the gas enters the inner cavity of the flexible membrane through the one-way valve, due to the increase in gas pressure inside the cavity, the flexible membrane expands upwards under pressure, and the volume of the pressure relief device gradually increases with the expansion of the flexible membrane to ensure that the cavity can accommodate more gas-liquid-solid mixture. At the same time, the thin-walled pressure relief structure of the pressure relief device will be quickly ruptured under the influence of pressure and temperature rise to form a pressure relief port, thereby discharging a portion of the gas-liquid-solid mixture from the pressure relief port. This ensures that all sealed channels are not exploded by the rapidly rising gas pressure, while also achieving the effect of thermoelectric separation and avoiding secondary hazards.

[0006] More preferably, the pressure relief device further includes a pressure relief base plate and a pressure relief connector, wherein the pressure relief base plate and the edge of the flexible membrane are together enclosed by the pressure relief connector to form a pressure relief receiving cavity.

[0007] More preferably, the pressure relief base plate has at least one through hole, a one-way valve is installed on the through hole, and a thin-walled area is provided on one side wall of the pressure relief connector. The thin-walled area is used to open when the air pressure in the pressure relief cavity exceeds a preset air pressure. The one-way valve, the pressure relief cavity, and the thin-walled area constitute a pressure relief channel.

[0008] More preferably, the projected profile of the one-way valve falls within the area defined by the edge profile of the groove.

[0009] 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.

[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 and beyond the outer edge of the top plate.

[0011] More preferably, the pressure relief device is provided with a pressure groove that mates with the groove.

[0012] More preferably, the inlet end of the one-way valve is connected to the groove, and the outlet end of the one-way valve is connected to the pressure relief cavity.

[0013] More preferably, the size of the one-way valve is greater than or equal to the outer ring size of the pressure relief orifice.

[0014] More preferably, the lid is a C-shaped frame structure with the opening facing downwards.

[0015] 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 arcing, 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; and this solution rigidly connects the cover and the module, which can effectively improve the mechanical strength performance of the pack. Attached Figure Description

[0016] 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 an explosion of a pressure relief device; Figure 5 This is a schematic diagram of the pressure relief device assembly. Figure 6 for Figure 5 Sectional view at AA; Figure 7 for Figure 6 An enlarged view at point B; Figure 8 This is a schematic diagram of the pressure relief device during pressure relief.

[0017] In the diagram: 1. Box bottom, 2. End plate, 3. Module, 4. Box cover, 5. Pressure relief device, 41. Top plate, 42. Groove, 43. Pressure relief hole, 51. Pressure relief bottom plate, 52. Pressure relief connector, 53. Flexible membrane, 511. One-way valve, 512. Detailed Implementation

[0018] 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.

[0019] Reference Figures 1-3 A lithium battery module, comprising: The box body includes a box bottom 1 and a box cover 4. The box cover 4 covers the box bottom 1 and forms a cavity for accommodating the module 3. The module 3 includes a plurality of battery cells arranged in a rectangular array. In an embodiment, such as Figure 1 and Figure 2As 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.

[0020] The upper surface of the box cover 4 is provided with at least one row of grooves 42, and the bottom surface of the grooves 42 is provided with a row of through pressure relief holes 43, and the pressure relief holes 43 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 of the two poles on the top of the cell, and the pressure relief hole 43 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.

[0021] 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 41 of the box cover 4 has four rows of corresponding grooves 42.

[0022] The pressure relief device 5 is fixed to the upper surface of the box cover 4; the pressure relief device 5 has a pressure relief channel communicating with the pressure relief hole 43 and a pressure relief receiving cavity, the pressure relief receiving cavity has a flexible membrane 53 that expands and contracts elastically with changes in fluid or gas content.

[0023] In one embodiment, the gas-liquid-solid mixture discharged from the pressure relief hole 43 enters the pressure relief containment cavity through the inlet of the pressure relief channel. Due to the increase in air pressure inside the cavity, the flexible membrane expands upward after being compressed, and the volume of the cavity of the pressure relief device 5 gradually increases with the expansion of the flexible membrane to ensure that the cavity can contain more gas-liquid-solid mixture. At the same time, the outlet of the pressure relief channel will be quickly ruptured to form a pressure relief port after being affected by the increase in pressure and temperature, thereby discharging a portion of the gas-liquid-solid mixture from the pressure relief port. This ensures that all sealed channels are not ruptured by the rapidly rising air pressure, while also achieving the effect of thermoelectric separation and avoiding secondary hazards.

[0024] like Figures 4-8 As shown, the pressure relief device 5 also includes a pressure relief base plate 51 and a pressure relief connector 52. The pressure relief base plate 51 and the edge of the flexible membrane 53 are together enclosed by the pressure relief connector 52 to form a pressure relief receiving cavity.

[0025] In one embodiment, the pressure relief base plate 51 can be manufactured using a hard metal or non-metal material with a temperature resistance of >600℃ through sheet metal stamping or molding. For example, the pressure relief base plate 51 and the pressure relief connector 52 can be made of aluminum alloy. The flexible membrane 53 is the most critical component of this device, and the material itself needs to meet the characteristics of high elongation, high melting point, resistance to electrolyte corrosion, good toughness, good puncture resistance, high pressure resistance, and flame retardancy. For example, the flexible membrane 53 can be a carbon nanotube-based composite film, whose main properties are: temperature resistance >600℃, elongation >15%, resistance to electrolyte corrosion, and flame retardancy.

[0026] In one embodiment, the connection between the pressure relief base plate 51 and the flexible membrane 53 and the pressure relief connector 52 can be achieved by adhesive bonding or other composite processes.

[0027] like Figure 6 and Figure 7 As shown, at least one through hole is provided on the pressure relief base plate 51, and a one-way valve 511 is installed on the through hole. A thin-walled area is provided on one side wall of the pressure relief connector 52. The thin-walled area is used to open when the air pressure in the pressure relief cavity exceeds the preset air pressure. The one-way valve 511, the pressure relief cavity and the thin-walled area constitute a pressure relief channel.

[0028] In one embodiment, only one through hole is opened at the position of each groove 42 on the pressure relief base plate 51. Then each through hole is opened at the middle position of each groove 42. Since each groove 42 is a channel for the movement of gas-liquid-solid mixture, if multiple through holes are opened at the position of each groove 42 on the pressure relief base plate 51, then the multiple through holes are evenly distributed at the position of each groove 42.

[0029] In one embodiment, the material of the one-way valve 511 must simultaneously meet the requirements of high temperature resistance and flame retardancy. As it is a one-way valve, gas can only be discharged from bottom to top and cannot be discharged in the opposite direction, which can effectively protect other channels between the pressure relief device 5 and the cover from intrusion by the mixture ejected from the battery cell. After the gas enters the inner cavity of the flexible membrane through the one-way valve, due to the increase in gas pressure inside the cavity, the flexible membrane expands upward under pressure. Thus, the volume of the cavity of the flexible membrane device gradually increases with the expansion of the flexible membrane to ensure that the cavity can accommodate more gas-liquid-solid mixture.

[0030] In one embodiment, the thin-walled area on the sidewall of the pressure relief connector 52 (e.g. Figure 7 As shown), it effectively plays a role in explosion prevention and pressure relief; the thin-walled area on the pressure relief connector 52 will be quickly broken through to form a pressure relief port after being affected by the rise in pressure and temperature, and then a part of the gas-liquid-solid mixture will be discharged from the pressure relief port. This ensures that all sealed channels are not exploded by the rapidly rising gas pressure, while also achieving the effect of thermoelectric separation and avoiding the occurrence of secondary hazards.

[0031] The box cover 4 is a C-shaped frame structure with an opening facing downwards.

[0032] 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.

[0033] The projected profile of the one-way valve 511 falls within the area defined by the edge profile of the groove 42.

[0034] In one embodiment, the groove 42 is a channel for the movement of the gas-liquid-solid mixture, and the one-way valve 511 is located on the groove 42. The gas-liquid-solid mixture in the channel can enter the pressure relief device 5 through the one-way valve 511.

[0035] The size of the pressure relief hole 43 is greater than or equal to the outer ring size of the cell explosion-proof valve.

[0036] In one embodiment, the size of the pressure relief hole 43 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 43.

[0037] One end of the groove 42 is located within the area defined by the outer edge contour of the top plate 41, and the other end of the groove 42 extends through and out of the outer edge of the top plate 41; the pressure relief device 5 is provided with a pressure groove 512 that cooperates with the groove 42.

[0038] In one embodiment, one end of the groove 42 extends through the outer edge of the top plate 41, while the other end does not extend through. At the extended end, the pressure relief device 5 cooperates with the groove 42 through the pressure groove 512. First, sealant silicone is evenly applied to the contact position between the pressure relief device 5 and the box cover 4. Then, the pressure relief device 5 is installed from directly above down, aligned with the box cover. Finally, the upper surface of the pressure relief device 5 is pressed with a tool to maintain pressure. After the adhesive has completely cured, the pressing tool is removed to complete the installation of the pressure relief device 5.

[0039] The inlet end of the one-way valve 511 is connected to the groove 42, and the outlet end of the one-way valve 511 is connected to the pressure relief cavity.

[0040] In this embodiment, the gas can only be discharged from bottom to top and cannot be discharged in the opposite direction, which can effectively protect the other channels between the pressure relief device 5 and the cover from being invaded by the mixture sprayed out by the battery cell.

[0041] The size of the one-way valve 511 is greater than or equal to the outer ring size of the pressure relief hole 43.

[0042] In this embodiment, the gas-liquid-solid mixture ejected from the pressure relief hole 43 can all enter the one-way valve 511.

[0043] To better understand this application, the embodiments of this patent are described below.

[0044] 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.

[0045] 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.

[0046] Installation of pressure relief device 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 and use hexagonal flange nuts to lock and fix the box cover by the studs welded to the surface of the battery cell top cover. Then, apply sealing silicone evenly to the contact area between the box cover and the pressure relief device. Then, install the pressure relief device from the top down, aligning it with the box cover. Finally, use a tool to press the upper surface of the pressure relief device to maintain pressure. After the glue has completely cured, remove the pressing tool to complete the installation of the flexible membrane.

[0047] 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 arcing, short circuits and other issues 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; and this solution rigidly connects the cover and the module, which can effectively improve the mechanical strength performance of the pack.

Claims

1. A 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 upper surface 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. The pressure relief holes correspond one-to-one with the positions of the explosion-proof valves of the battery cells inside the box. A pressure relief device is fixed to the upper surface of the box cover; the pressure relief device has a pressure relief channel communicating with the pressure relief hole and a pressure relief receiving cavity, the pressure relief receiving cavity having a flexible membrane that expands and contracts elastically with changes in fluid or gas content.

2. A lithium battery module according to claim 1, characterized in that, The pressure relief device also includes a pressure relief base plate and a pressure relief connector. The pressure relief base plate and the edge of the flexible membrane are together enclosed by the pressure relief connector to form a pressure relief receiving cavity.

3. A lithium battery module according to claim 2, characterized in that, At least one through hole is provided on the pressure relief base plate, and a one-way valve is installed on the through hole. A thin-walled area is provided on one side wall of the pressure relief connector. The thin-walled area is used to open when the air pressure in the pressure relief cavity exceeds the preset air pressure. The one-way valve, the pressure relief cavity and the thin-walled area constitute a pressure relief channel.

4. A lithium battery module according to claim 3, characterized in that, The projected profile of the one-way valve falls within the area defined by the edge profile of the groove.

5. A 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 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 and beyond the outer edge of the top plate.

7. A lithium battery module according to claim 1, characterized in that, The pressure relief device is provided with a pressure groove that mates with the groove.

8. A lithium battery module according to claim 3, characterized in that, The inlet end of the one-way valve is connected to the groove, and the outlet end of the one-way valve is connected to the pressure relief cavity.

9. A lithium battery module according to claim 3, characterized in that, The size of the one-way valve is greater than or equal to the outer ring size of the pressure relief orifice.

10. A 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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