Battery cell top cover structure and battery cell

Abstract

The utility model relates to lithium battery technical field, propose a kind of electric core top cover structure and electric core, structure includes lower plastic plate, explosion-proof valve, container and several cooling units, wherein, explosion-proof valve is set on lower plastic plate, for battery thermal runaway time exhaust pressure relief;Container is set on the side of lower plastic plate away from pole, and located the outside of explosion-proof valve;Several cooling units are hermetically sealed in container, container breaks when battery thermal runaway, and release cooling unit inside electric core heat inhibition, this structure is integrated to electric core inside, simple and compact structure does not need external equipment, and can promptly respond battery thermal runaway and release cooling unit in time, control thermal runaway chain reaction, reduce the risk of safety accident, improve the safety performance of electric core.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, and in particular to a cell top cover structure and a cell. Background Technology

[0002] Lithium-ion batteries are highly susceptible to thermal runaway under conditions such as overcharging, short circuits, or mechanical damage. This causes a rapid increase in internal temperature and pressure, triggering a series of irreversible thermochemical reactions that can lead to serious safety accidents such as combustion and explosion. Currently, traditional safety designs for lithium-ion batteries mainly include passive protection devices such as pressure relief valves and positive temperature coefficient materials. While these devices can slow down the thermal runaway process or provide localized cooling to some extent, some are designed to operate irreversibly and may actually exacerbate electrolyte leakage or external short circuits, failing to fundamentally prevent the thermal runaway chain reaction.

[0003] A thermal runaway protection device for battery cells and a battery cell are disclosed in CN219642909U. The thermal runaway protection device for battery cells includes an installation body, a thermal runaway detection unit, and a fire extinguishing unit disposed inside the battery cell. The installation body has an open installation cavity. The thermal runaway detection unit is disposed on the installation body and is used to detect the pressure and / or temperature information inside the battery cell. The fire extinguishing unit is located in the installation cavity and can be triggered when the temperature or pressure value inside the battery cell exceeds a preset threshold, thereby spraying a fire extinguishing medium into the battery cell.

[0004] Current active cooling systems, such as liquid cooling pipelines, mostly rely on external circulation pumps and other equipment to drive coolant circulation for cooling. This not only increases system complexity but also results in slow response speed due to delays in signal transmission and fluid delivery between devices. In emergency situations such as battery thermal runaway, slow response may miss the best time to suppress the problem, thereby reducing the safety performance of the battery cell. Utility Model Content

[0005] In view of this, the present invention proposes a battery cell top cover structure and a battery cell, which are integrated into the battery cell. The structure is simple and compact, requires no external equipment, and can quickly respond to battery thermal runaway and release the cooling unit in time to control the thermal runaway chain reaction, reduce the risk of safety accidents, and improve the safety performance of the battery cell.

[0006] The technical solution of this utility model is achieved as follows: This utility model provides a battery cell top cover structure, including a lower plastic plate, an explosion-proof valve, a container, and several cooling units, wherein... The explosion-proof valve is located on the lower plastic plate and is used to release pressure and vent air in case of battery thermal runaway. The container is positioned on the side of the lower plastic plate away from the pole post and is located outside the explosion-proof valve; Several cooling units are sealed inside the container. When the battery experiences thermal runaway, the container ruptures and releases the cooling units to suppress internal heat in the battery cell.

[0007] Based on the above technical solutions, preferably, the container is fixedly connected to the lower plastic plate by hot melting, and the sides and bottom of the container are both ruptured membranes, forming an integral structure.

[0008] Based on the above technical solutions, preferably, the container is arranged along the width direction of the lower plastic plate and is arranged in parallel, and the length of the container matches the width of the lower plastic plate.

[0009] Based on the above technical solutions, preferably, the lower plastic plate is provided with a liquid injection hole for injecting liquid into the battery cell; the number of containers is multiple, and the multiple containers are symmetrically distributed on both sides of the explosion-proof valve and located between the liquid injection hole and the explosion-proof valve.

[0010] Based on the above technical solutions, preferably, the outer side of the ruptured diaphragm is coated with a heat-sensitive coating, which melts when a temperature threshold is reached.

[0011] Based on the above technical solutions, preferably, the ruptured membrane is a polyimide film, and the thickness of the ruptured membrane is 1~3mm.

[0012] Based on the above technical solutions, preferably, a plurality of cooling units are arranged in a rectangular array inside the container, and the cooling unit includes a capsule shell, the capsule shell being filled with a cooling substance.

[0013] Based on the above technical solutions, preferably, the capsule shell is a polystyrene capsule, and the thickness of the capsule shell is 1~3mm.

[0014] Based on the above technical solutions, preferably, the cooling substance is at least one of phase change material, flame retardant, or endothermic reactant.

[0015] Secondly, this utility model also provides a battery cell, including a battery cell top cover structure.

[0016] The battery cell top cover structure and battery cell of this utility model have the following advantages over the prior art: Through the explosion-proof valve and container rupture mechanism, it can quickly respond to battery thermal runaway and release the cooling unit in time, rapidly control the thermal runaway chain reaction, reduce the risk of safety accidents caused by battery thermal runaway, improve the safety performance of the cell, and through the built-in structure, the structure is simple and compact, requiring no external equipment; it does not occupy extra cell space and improves energy density. By employing both pressure-triggered and temperature-triggered mechanisms, the battery can accurately assess the risk of thermal runaway, effectively preventing serious safety accidents such as battery combustion and explosion, and providing more comprehensive thermal runaway protection. By selecting solid phase change materials as cooling agents, the risk of cell contamination from liquid materials is avoided, thus improving the battery's environmental performance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a perspective view of the battery cell top cover structure of this utility model; Figure 2 This is a perspective view of the container of the battery cell top cover structure of this utility model; Figure 3 This is a cross-sectional view of the container of the battery cell top cover structure of this utility model; Figure 4 This is an exploded view of the battery cell of this utility model. Detailed Implementation

[0019] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments of this utility model. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0020] like Figure 1-3 As shown, the present invention provides a battery cell top cover structure, including a lower plastic plate 1, an explosion-proof valve 2, a container 3, and several cooling units 4. The explosion-proof valve 2 is disposed on the lower plastic plate 1 for venting and depressurizing in the event of battery thermal runaway. The container 3 is disposed on the side of the lower plastic plate 1 away from the terminal post and located outside the explosion-proof valve 2. Several cooling units 4 are sealed inside the container 3. The container 3 ruptures in the event of battery thermal runaway and releases the cooling units 4 to suppress internal heat in the battery cell.

[0021] It should be noted that under normal operating conditions, the explosion-proof valve 2 is in a tightly closed state, ensuring complete isolation between the battery's interior and the external environment, preventing external moisture, dust, and other impurities from entering the battery. The cooling unit 4 is sealed inside the container 3 and is in a standby state, ready to deal with battery thermal runaway at any time. When the battery cell experiences thermal runaway, and the internal gas pressure rises to a certain threshold, the explosion-proof valve 2 opens to release the accumulated gas inside, reducing the internal pressure and preventing the battery from exploding. At the same time, the container 3 ruptures during battery thermal runaway, releasing the sealed cooling unit 4 inside to suppress heat inside the battery cell.

[0022] In this embodiment, the rupture mechanism of the explosion-proof valve 2 and the container 3 can quickly respond to battery thermal runaway and release the cooling unit 4 in a timely manner, rapidly control the thermal runaway chain reaction, reduce the risk of safety accidents caused by battery thermal runaway, improve the safety performance of the battery cell, and through the built-in design, the structure is simple and compact, requiring no external equipment; it will not occupy extra battery cell space, and the module can reduce or even eliminate fire-fighting equipment, save space, and improve energy density.

[0023] In this embodiment, the container 3 is fixedly connected to the lower plastic plate 1 by hot melting, and the sides and bottom of the container 3 are both ruptured membranes 31, forming an integral structure.

[0024] It should be noted that the container 3 is fixedly connected to the lower plastic plate 1 by heat fusion. This utilizes the properties of thermoplastic materials, which soften and become malleable after being heated to a certain temperature, and form a strong connection after cooling. This ensures the tightness and stability between the container 3 and the lower plastic plate 1. The sides and bottom of the container 3 are both ruptured membranes 31 and are integrated into one structure. This allows the container 3 to rupture rapidly in the event of internal pressure or temperature rise caused by battery thermal runaway, thereby releasing the internally sealed cooling unit 4. This achieves a balance between structural stability and reliable rupture.

[0025] In addition, the preset pressure threshold setting range of the rupture diaphragm 31 is 0.5 to 0.65 MPa, and the pressure threshold must be equal to or slightly lower than the explosion resistance capability of the explosion-proof valve 2. Specifically, in this embodiment, the ruptured membrane 31 is a polyimide film with a thickness of 1-3 mm. When the battery experiences thermal runaway, the internal pressure or temperature rises rapidly. When the preset pressure threshold of the ruptured membrane 31 is reached, the ruptured membrane 31 is subjected to the impact force of the internal pressure and rapidly disintegrates, thereby releasing the cooling unit 4 sealed inside the container 3. This ensures both the mechanical strength and chemical stability of the membrane under normal operating conditions and ensures that it can rupture rapidly and reliably during battery thermal runaway, thereby quickly responding to and controlling the thermal runaway chain reaction and significantly improving the safety and reliability of the battery.

[0026] In this embodiment, the container 3 is arranged along the width direction of the lower plastic plate 1 and is arranged in parallel. The length of the container 3 matches the width of the lower plastic plate 1.

[0027] In addition, in this embodiment, the outer side of the ruptured diaphragm 31 is coated with a thermosensitive coating 310, which melts when the temperature threshold is reached.

[0028] It should be noted that this embodiment also includes a temperature triggering mechanism with a preset temperature triggering threshold. When the temperature exceeds the temperature triggering threshold, the heat-sensitive coating 310 melts, the mechanical strength of the container 3 decreases, and it ruptures prematurely under pressure, releasing the cooling unit 4.

[0029] This embodiment combines pressure triggering and temperature triggering mechanisms, enabling the battery to more accurately assess the risk of thermal runaway, effectively preventing serious safety accidents such as battery combustion and explosion, and providing more comprehensive thermal runaway protection.

[0030] In this embodiment, the lower plastic plate 1 is provided with a liquid injection hole 100 for injecting liquid into the battery cell; there are multiple containers 3, and the multiple containers 3 are symmetrically distributed on both sides of the explosion-proof valve 2, and located between the liquid injection hole 100 and the explosion-proof valve 2.

[0031] It should be noted that by symmetrically arranging containers 3 on both sides of the explosion-proof valve 2, it is ensured that the cooling unit 4 can evenly and rapidly diffuse to the critical areas inside the battery during battery thermal runaway, which can more effectively cover and control the thermal runaway area inside the battery.

[0032] In this embodiment, several cooling units 4 are arranged in a rectangular array inside the container 3, and each cooling unit 4 includes a capsule shell 41, which is filled with a cooling substance.

[0033] Specifically, in this embodiment, the capsule shell 41 is a polystyrene capsule, and the thickness of the capsule shell 41 is 1~3mm.

[0034] It should be noted that under normal operating temperature, the polystyrene capsule shell 41 can maintain its structural integrity, effectively encapsulate and protect the internal cooling material. When the preset rupture threshold is reached, the polystyrene material will release the internal cooling material due to softening or rupture, so that it can respond quickly and release the cooling material in the event of battery thermal runaway, thereby suppressing the heat inside the cell.

[0035] The cooling substance in this embodiment is at least one of phase change material, flame retardant, or endothermic reactant.

[0036] The phase change materials include nitrates, carbonates, fatty acids, paraffin derivatives, polyols, or eutectic mixtures, with melting points controlled between 120 and 200°C. This temperature range matches the temperature during thermal runaway of lithium-ion batteries, effectively absorbing heat and delaying or preventing the process of thermal runaway. The flame retardant includes a mixed powder of lithium hexafluorophosphate and perfluorohexanone, which releases flame-retardant gas during battery thermal runaway, isolating oxygen and effectively suppressing the spread of flames. The endothermic reactant includes carbonate substances that decompose upon heating to produce CO2 and absorb heat. This not only absorbs a large amount of heat and lowers the internal temperature of the battery, but the generated CO2 gas also further dilutes the oxygen concentration inside the battery, helping to suppress combustion. Furthermore, using solid phase change materials as cooling substances avoids the risk of cell contamination that liquid substances may cause, improving the environmental performance of the battery.

[0037] like Figure 4 As shown, in a second aspect, this utility model also provides a battery cell, including a battery cell top cover structure.

[0038] Working principle: When the internal temperature of the battery exceeds the preset temperature trigger threshold, the thermal coating 310 melts, causing the mechanical strength of the ruptured diaphragm 31 to decrease. If the temperature does not reach the threshold but the internal pressure rises sharply due to thermal runaway, the pressure acts directly on the ruptured diaphragm 31, causing it to reach the rupture critical point. Under temperature or pressure, the rupture membrane 31 breaks, the inner capsule shell 41 disintegrates due to airflow impact, the cooling substance diffuses into the inside of the battery cell, the phase change material absorbs heat, the flame retardant isolates oxygen, and the heat-absorbing reactant further reduces the local temperature, thus achieving multi-path thermal suppression.

[0039] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A battery cell top cover structure, characterized in that, It includes a lower plastic sheet (1), an explosion-proof valve (2), a container (3), and several cooling units (4), among which, An explosion-proof valve (2) is installed on the lower plastic plate (1) for venting and depressurizing when the battery thermally runs away; The container (3) is located on the side of the lower plastic plate (1) away from the pole post and is located outside the explosion-proof valve (2); Several cooling units (4) are sealed inside the container (3). The container (3) ruptures when the battery thermally runs away and releases the cooling units (4) to suppress the internal heat of the battery cell.

2. The cell top cover structure as described in claim 1, characterized in that: The container (3) is fixedly connected to the lower plastic plate (1) by hot melting, and the side and bottom surfaces of the container (3) are both ruptured membranes (31) and form an integral structure.

3. The cell top cover structure as described in claim 1, characterized in that: The container (3) is arranged along the width direction of the lower plastic plate (1) and is arranged in parallel. The length of the container (3) matches the width of the lower plastic plate (1).

4. The cell top cover structure as described in claim 1, characterized in that: The lower plastic plate (1) is provided with a liquid injection hole (100) for injecting liquid into the battery cell; there are multiple containers (3), and the multiple containers (3) are symmetrically distributed on both sides of the explosion-proof valve (2) and located between the liquid injection hole (100) and the explosion-proof valve (2).

5. The cell top cover structure as described in claim 2, characterized in that: The outer side of the ruptured diaphragm (31) is coated with a thermosensitive coating (310), which melts when a temperature threshold is reached.

6. The cell top cover structure as described in claim 2, characterized in that: The ruptured membrane (31) is a polyimide film, and the thickness of the ruptured membrane (31) is 1~3mm.

7. The cell top cover structure as described in claim 1, characterized in that: Several cooling units (4) are arranged in a rectangular array inside the container (3), and the cooling unit (4) includes a capsule shell (41) filled with a cooling substance.

8. The cell top cover structure as described in claim 7, characterized in that: The capsule shell (41) is a polystyrene capsule, and the thickness of the capsule shell (41) is 1~3mm.

9. The cell top cover structure as described in claim 7, characterized in that: The cooling substance is at least one of phase change material, flame retardant, or endothermic reactant.

10. A battery cell, characterized in that: Includes the cell top cover structure as described in any one of claims 1-9.

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