Housing for a secondary battery

Abstract

The application provides a secondary battery shell, which is configured to include an outer box body and a fireproof inner shell; an accommodation space is arranged in the inner part of the outer box body to accommodate the fireproof inner shell therein; a breakable wall is arranged on the outer box body; the fireproof inner shell is arranged on the inner side of the outer box body and can accommodate the secondary battery and a battery management system therein; the fireproof inner shell is configured to include at least one fireproof body, which is a porous structure when in action; the fireproof inner shell of the application is arranged on the inner side of the outer box body and completely surrounds the secondary battery therein; when the fireproof body is in action, the passing of open fire and smoke can be reduced, the impact resistance can be achieved, and a secondary battery shell with excellent open fire, heat and smoke blocking effect, impact resistance and passive fire resistance function is provided.

Description

Technical Field

[0001] This application belongs to the technical field of battery casings and battery boxes, and in particular to a casing for a secondary battery. Background Technology

[0002] Rechargeable batteries originated with lead-acid batteries produced in 1859. They have accompanied human civilization for over a century, undergoing countless technological improvements, and remain the most technologically mature type of rechargeable battery. However, driven by environmental goals and the rapid development of new energy technologies, lithium-ion batteries have become the mainstream rechargeable battery. Lithium-ion polymer batteries (also commonly referred to as "lithium polymer batteries") are essentially lithium-ion batteries, but are improvements on ordinary lithium-ion batteries. They utilize gel or solid polymers instead of liquid organic solvents to create rechargeable lithium-ion batteries. They offer better safety, do not explode, and can be molded into various cell shapes, making them the current mainstream form of rechargeable lithium batteries. The term "lithium-ion battery" in this specification also includes lithium-ion polymer batteries.

[0003] Lithium-ion batteries are widely used in various electronic products and electric vehicles due to their advantages such as fast charging, high energy density, small size, and mature technology. However, due to the highly reactive nature of lithium, it also carries considerable risks, and news of lithium-ion battery fires is frequently reported. In particular, the recent spate of electric vehicle fires and their difficulty in extinguishing them have raised serious concerns about the safety of lithium-ion batteries. Thermal runaway is known to be one of the main causes of lithium-ion battery fires. Thermal runaway occurs when the rate of heat generation from an internal short circuit in the battery far exceeds the rate of heat dissipation, leading to a large accumulation of heat that is not dissipated in time. Furthermore, the temperature increases further, creating a vicious cycle and spreading the heat. Thermal runaway in a lithium-ion battery triggers a series of irreversible chain reactions, causing the internal temperature to rise rapidly within milliseconds. The energy stored in the lithium-ion battery is suddenly released, generating internal temperatures of approximately 500°C to 1000°C. Simultaneously, the high temperature causes some materials in the lithium-ion battery to release flammable high-temperature gas, resulting in a fire that is almost impossible to extinguish using conventional methods.

[0004] Known methods for preventing thermal runaway in lithium batteries include: using high-temperature resistant plastic materials for insulation to increase the spacing between battery cells; encasing lithium batteries in carbon steel to form battery packs, as a means of preventing thermal runaway and its propagation; and using heat-insulating two-dimensional planar materials, such as mica, ceramic plates, silica sheets, carbon fiber fabrics, and steel plates, as heat insulation and heat-blocking materials to prevent heat transfer. Regarding the application of heat-insulating two-dimensional planar materials, their effect cannot prevent the generation of impact gas in lithium battery cells under thermal runaway. For high-temperature resistant and melt-preventing two-dimensional planar materials only attached to the inner side of the casing, once subjected to an internal impact from the lithium battery cell, the casing is easily punctured / broken, leading to the entry of external air, such as oxygen, into the lithium battery, causing reignition or deflagration. Furthermore, such materials lack the ability to prevent the propagation and diffusion of high-temperature gases within the lithium battery (pile).

[0005] A published Chinese invention patent application (publication number CN 101894930 A) proposes a battery box with good ventilation and heat dissipation, which includes a box body and a battery pack placed inside the box body. The battery pack is fixed to the box body by clamps on both sides. There is a gap between each battery in the battery pack. The two side plates of the box body, which are perpendicular to the plane of the gap, are an air inlet plate and an air outlet plate, respectively. The air inlet plate is provided with an air inlet, and the air outlet plate is provided with an exhaust fan. A diversion plate is provided on the side of the battery pack facing the air inlet plate, and the gap between each diversion plate corresponds to the gap between each battery.

[0006] An improved battery box is proposed in a Chinese invention patent that has been granted and announced (authorization announcement number CN 101894926 B). The battery box includes a box body and two battery modules disposed on opposite sides of the box body. The box body consists of four side plates, a box cover and a box bottom. Two parallel side plates serve as air inlets of the battery box, and the other side plate, which is perpendicular to the air inlets and farther away from the battery modules, serves as the air outlet of the battery box. The battery module includes a battery pack, a baffle and a guide plate. A fan is mounted on the baffle. An air inlet is provided on the air inlet plate, and an air outlet is provided on the air outlet plate. An outlet fan and a guide plate are installed at the air outlet, and the guide plates are symmetrically arranged on both sides of the fan.

[0007] The aforementioned patented technology is an active heat dissipation technology for secondary batteries. Its function is to quickly remove heat from the battery, thereby improving safety during use and extending the lifespan of the battery module. Utility Model Content

[0008] The technical problem to be solved by this application is to provide a casing for a secondary battery that has excellent flame, heat, and smoke blocking effects, impact resistance, and passive flame retardant function.

[0009] To solve the above-mentioned technical problems, a preferred embodiment of the casing of the secondary battery of this application includes: an outer casing and a fireproof inner casing; wherein the outer casing comprises: a first annular side plate, a first bottom plate, and a first top cover plate, the first bottom plate being disposed at the bottom edge of the first annular side plate, and the first top cover plate being disposed at the top of the first annular side plate via a connecting means, the first annular side plate, the first bottom plate, and the first top cover plate together forming an outer casing having an accommodating space, and a partially breakable wall being provided on the first annular side plate; wherein the fireproof inner casing is disposed on the outer casing. The inner side of the box body, and the fireproof inner shell can accommodate a secondary battery and a battery management system therein; the fireproof inner shell structure includes: a second annular side plate, a second bottom plate and a second top cover plate, the second bottom plate is located at the bottom edge of the second annular side plate, the second top cover plate is located at the top of the second annular side plate, the second annular side plate, the second bottom plate and the second top cover plate together form a fireproof inner shell with an accommodating space, the structure of the second annular side plate, the second bottom plate and the second top cover plate includes at least one fireproof body, the fireproof body is a porous structure when it is in action.

[0010] In a preferred embodiment of the casing of the secondary battery of this application, the thickness of the fragile wall is less than the thickness of the remaining parts of the first annular side plate, the first bottom plate, and the first top cover plate.

[0011] In a preferred embodiment of the casing of the secondary battery of this application, the outer casing is made of metal, and the connection means include any one of bolts, welding and gluing.

[0012] As a preferred embodiment of the casing of the secondary battery of this application, the outer casing is made of plastic, and the connection means includes any one of bolts, welding and gluing.

[0013] In a preferred embodiment of the casing of the secondary battery of this application, the outer casing is made of either metal or plastic.

[0014] In a preferred embodiment of the casing of the secondary battery of this application, the second annular side plate, the second bottom plate and the second top cover plate are constructed including two metal meshes and a fireproof body between the two metal meshes.

[0015] Preferably, the material of the fireproof body is selected from the group consisting of: worm graphite sheets, coatings comprising worm graphite material, worm graphite that has expanded into a porous structure, and foam metal, wherein the foam metal material includes any one of: steel, silver, iron, copper, aluminum, and nickel.

[0016] The advantages and benefits of this application are that the fireproof inner shell is disposed inside the outer casing and completely surrounds the secondary battery. The porous fireproof material used to make the fireproof inner shell can reduce the passage of open flames and smoke and has impact resistance, thereby providing a secondary battery shell with excellent open flame, heat and smoke blocking effect, impact resistance and passive flame retardant function.

[0017] The other effects and embodiments of this application are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application 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 recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a structural diagram of one embodiment of the casing of the secondary battery of this application;

[0020] Figure 2 yes Figure 1 An exploded view of the construction of an embodiment;

[0021] Figure 3 Figure 1 Cross-sectional structural diagram at location AA;

[0022] Figure 4 Figure 1 Cross-sectional structural diagram at location BB;

[0023] Figure 5 This is a structural schematic diagram of a preferred embodiment of a fireproof structure;

[0024] Figure 6 yes Figure 5 Cross-sectional structural diagram at position CC.

[0025] Symbol Explanation

[0026] M: Battery Management System 10: Outer Housing

[0027] 11: First annular side plate 111: Fragile wall

[0028] 12: First base plate 13: First top cover plate

[0029] 14: Connection method 20: Fireproof inner shell

[0030] 21: Second annular side plate; 22: Second bottom plate

[0031] 23: Second upper cover plate; 31: Positive end plate

[0032] 32: Negative extreme polarity; 40: Fireproof body

[0033] 41: Metal mesh; 50: Secondary battery Detailed Implementation

[0034] In the embodiments described below, the positional relationships include: up, down, left, and right. Unless otherwise specified, they are all based on the direction shown by the components in the diagram.

[0035] The casing of the secondary battery described in this application can be used as the casing for most commercially available secondary battery products, including: Backup Battery Units (BBUs), car starter batteries, electric bicycle batteries, electric vehicle batteries, robot vacuum cleaner batteries, and scooter batteries.

[0036] Please refer to the following first. Figure 1 and Figure 2 This is a structural diagram and exploded view of one embodiment of the casing of the secondary battery of this application. The casing of the secondary battery proposed in this application is basically used to house the secondary battery 50 and the battery management system M (BMS). The BMS is an electronic system specifically used to manage, monitor and control the battery pack. It can ensure the safety and stability of the secondary battery or battery pack, and improve the battery's lifespan and efficiency.

[0037] A preferred embodiment of the secondary battery casing proposed in this application comprises: an outer casing 10 and a fireproof inner casing 20.

[0038] The outer casing 10 comprises a first annular side plate 11, a first bottom plate 12, and a first top cover plate 13. The first bottom plate 12 is disposed at the bottom edge of the first annular side plate 11. In other words, the first bottom plate 12 and the first annular side plate 11 together constitute a container with an opening, while the first top cover plate 13 is used to close the opening. Preferably, the first top cover plate 13 is disposed at the top of the first annular side plate 11 by a connecting means 14. The first annular side plate 11, the first bottom plate 12, and the first top cover plate 13 together form an outer casing 10 with an accommodating space. In a preferred embodiment, the outer casing 10 is made of metal, and the connecting means include any one of bolts, welding, and gluing. Preferably, the first top cover plate 13 is openable. Therefore, it is ideal to use bolts or other equivalent components or assemblies to allow maintenance operations to be performed on the secondary battery 50 and the battery management system M placed therein when necessary. In another preferred embodiment, the outer casing 10 is made of plastic, and the connection means 14 includes any one of bolts, welding, and gluing.

[0039] In a preferred embodiment of this application, a partially fractured wall 111 is provided on the first annular side plate 11 (see...). Figure 3 The thickness of the fragile wall 111 is less than the thickness of the remaining parts of the first annular side plate 11, and the thickness of the fragile wall 111 is less than the thickness of the first bottom plate 12 and the first top cover plate 13. For example, if the outer box body 10 is made of plastic, the thickness of the fragile wall 111 can be controlled by controlling the mold thickness when manufacturing the first annular side plate 11, the first bottom plate 12 and the first top cover plate 13 using plastic injection technology.

[0040] After the secondary battery 50 inside the outer casing 10 experiences thermal runaway, the fragile wall 111 will be ruptured by pressure before the rest of the outer casing 10, providing a pressure relief vent. This reduces the internal pressure inside the outer casing 10 and guides open flames, smoke, and heat out of the outer casing. Even if the secondary battery 50 experiences thermal runaway, from the outside of the secondary battery casing, no open flames will be seen, only smoke will be released, thus preventing more severe and widespread damage to the outer casing.

[0041] The fireproof inner shell 20 is disposed inside the outer casing 10, preferably as close as possible to the inner surface of the outer casing 10, and the fireproof inner shell 20 can accommodate the secondary battery 50 and the battery management system M therein (see...). Figure 4 In other words, the fireproof inner shell 20 is located between the outer casing 10 and the secondary battery 50 and the battery management system M.

[0042] A preferred embodiment of the fireproof inner shell 20 includes: a second annular side plate 21, a second bottom plate 22, and a second top cover plate 23. The second bottom plate 22 is disposed at the bottom edge of the second annular side plate 21, and the second top cover plate 23 is disposed at the top edge of the second annular side plate 21. The second annular side plate 21, the second bottom plate 22, and the second top cover plate 23 together form a fireproof inner shell 20 having an accommodating space, thereby encapsulating the secondary battery 50 and the battery management system M within the fireproof inner shell 20 (see...). Figure 4 Basically, the battery management system M typically has a positive terminal 31 and a negative terminal 32. Preferably, the fireproof inner shell 20 and outer casing 10 only allow the positive terminal 31 and negative terminal 32 to pass through the fireproof inner shell 20 and outer casing 10. In other embodiments, some other necessary electrical components of the battery management system M, such as wires or electrical connectors, may also pass through the fireproof inner shell 20 and outer casing 10 to make electrical connections with external devices.

[0043] As a preferred embodiment of the casing of the secondary battery of this application, the second annular side plate 21, the second bottom plate 22 and the second top cover plate 23 are constructed including at least one fireproof body 40. The fireproof body 40 is a porous structure when it is in operation. Specifically, the fireproof body 40 has the effect of blocking open flame, heat and smoke and has impact resistance.

[0044] Please see Figure 5 and Figure 6 In a preferred embodiment of the secondary battery casing of this application, the second annular side plate 21, the second bottom plate 22, and the second top cover plate 23 are constructed comprising two metal meshes 41 and a fire-resistant body 40 between the two metal meshes 41. The fire-resistant body 40 is made of a group consisting of: worm-shaped graphite sheets, coatings comprising worm-shaped graphite materials, worm-shaped graphite that has expanded into a porous structure, and foamed metals, wherein the foamed metals include any one of: steel, silver, iron, copper, aluminum, and nickel. The worm-shaped graphite sheets, after expanding into a porous structure when heated, have an outer layer of velvety carbide structure, which can reduce the kinetic energy of impact and reduce the damage caused by fire.

[0045] The expanded worm-shaped graphite, through a pre-treatment process involving heating, transforms into a porous fire-resistant material. When exposed to high temperatures or open flames, this expanded, porous worm-shaped graphite exhibits excellent flame, heat, and smoke blocking properties, as well as impact resistance. On the other hand, foamed metal possesses superior physical, chemical, and mechanical properties, offering impact resistance, excellent anti-aging performance, and reduced transmission of open flames and smoke.

[0046] The embodiments and / or implementation methods described above are merely preferred embodiments and / or implementation methods for implementing the technology of this application, and are not intended to limit the implementation methods of the technology of this application in any way. Any person skilled in the art may make some modifications or alterations to other equivalent embodiments without departing from the scope of the technical means disclosed in this application, but these should still be regarded as the technology or embodiments that are substantially the same as those of this application.

Claims

1. A casing for a secondary battery, used to house the secondary battery and a battery management system. Wherein, it is characterized by, The casing of the secondary battery includes the following components: An outer box, comprising: a first annular side plate, a first bottom plate, and a first top cover plate. The first bottom plate is disposed at the bottom edge of the first annular side plate, and the first top cover plate is disposed at the top of the first annular side plate via a connecting means. The first annular side plate, the first bottom plate, and the first top cover plate together form the outer box having an accommodating space. A portion of the first annular side plate is provided with a breakable wall. A fireproof inner shell is disposed inside the outer casing, and the fireproof inner shell can accommodate the secondary battery and the battery management system therein; the fireproof inner shell includes a second annular side plate, a second bottom plate and a second top cover plate, the second bottom plate is disposed at the bottom edge of the second annular side plate and the second top cover plate is disposed at the top of the second annular side plate, the second annular side plate, the second bottom plate and the second top cover plate together form the fireproof inner shell having an accommodating space, and the structure of the second annular side plate, the second bottom plate and the second top cover plate includes at least one fireproof body, which is a porous structure when in action.

2. The casing of the secondary battery according to claim 1, characterized in that, The thickness of the fragile wall is less than the thickness of the remaining parts of the first annular side plate, the first bottom plate, and the first top cover plate.

3. The casing of the secondary battery according to claim 1, characterized in that, The outer casing is made of metal, and the connection method includes any one of bolts, welding, and gluing.

4. The casing of the secondary battery according to claim 1, characterized in that, The outer casing is made of plastic, and the connection method includes any one of bolts, welding, and gluing.

5. The casing of the secondary battery according to claim 1, characterized in that, The outer box is made of either metal or plastic.

6. The casing of the secondary battery according to claim 1, characterized in that, The second annular side plate, the second bottom plate, and the second top cover plate are constructed of two metal meshes and a fireproof body between the two metal meshes.

7. The casing of the secondary battery according to claim 6, characterized in that, The material of the fireproof body is selected from the group consisting of: worm graphite sheets, coatings containing worm graphite material, worm graphite that has expanded into a porous structure, and foam metal, wherein the foam metal material includes any one of: steel, silver, iron, copper, aluminum, and nickel.

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