A battery pack

Abstract

In order to overcome the problem that the battery pack in the prior art cannot achieve complete thermal isolation between single cells, the present invention provides a battery pack, including a plurality of single cells, the single cells are connected by conductive connecting sheets; wherein, it also includes a heat dissipation composite plate and a plurality of insulation plates; the single cells are embedded between the insulation plates, the insulation plates are used to thermally isolate the single cells; the heat dissipation composite plate is arranged on the outside of the battery pack, and is used to dissipate the heat of each single cell through the heat dissipation composite plate, and each single cell transfers heat to the outside independently. The battery pack provided by the present invention effectively isolates the heat transfer between each single cell through the insulation plates and heat dissipation composite plates, constructs an independent thermal environment centered on the single cell; and independently transfers the heat of each single cell to achieve a good heat dissipation effect for each single cell in the battery pack.

Description

Technical Field

[0001] The present invention relates to the technical field of deep lithium ion batteries. Background Art

[0002] As environmental protection and energy shortage issues become increasingly prominent in modern society, more and more traffic, transportation and engineering vehicles are beginning to adopt energy-saving and clean energy technologies, such as hybrid power, pure electric drive and fuel cell technology. Among them, secondary batteries, especially lithium-ion batteries, as the core power source, have been widely used in practice. At the same time, the requirements for the safety and life of lithium-ion batteries are also getting higher and higher. Among the many issues that need to be considered, battery heat dissipation and thermal isolation are two very important key points.

[0003] First, when lithium-ion batteries are abused or have internal manufacturing defects, an internal short circuit will occur between the positive and negative electrodes, generating a large amount of heat, which will trigger multiple side reactions between the internal components of the battery, further generating more heat and gas, causing the temperature and pressure inside the battery to rise sharply, and eventually causing the battery to catch fire and explode. This process is called thermal runaway of lithium-ion batteries. Common abuse situations include mechanical abuse such as puncture / extrusion / impact, thermal abuse such as heating / fire, and electrical abuse such as overcharging / over-discharging / external short circuit. Thermal runaway is considered to be the root cause of serious safety accidents involving lithium-ion batteries.

[0004] In all kinds of pure electric vehicles and hybrid vehicles driven by lithium-ion batteries, the lithium-ion battery pack is a high-voltage system composed of multiple single cells connected in series (or in parallel and in series). If the heat generated by thermal runaway of a single cell can be quickly transferred to other single cells in the battery pack, it will quickly trigger a chain reaction, causing thermal runaway of other single cells. This is the thermal diffusion and thermal spread of lithium-ion batteries. Therefore, in order to improve the safety of lithium-ion battery packs, it is necessary to effectively isolate the thermal diffusion between single cells to prevent the thermal spread in the battery pack.

[0005] In order to solve the above heat diffusion problem, the battery industry has begun to use the method of placing insulating partitions between single cells to isolate heat diffusion. Commonly used sheet-shaped insulating partitions are close to the single cells on both sides, and the material is usually aerogel, etc. The sheet-shaped insulating partition can effectively isolate the heat transfer between the sides of the single cells, but the single cells must be connected in series and in parallel through conductive connecting pieces made of metal materials in the module. These metal connecting pieces are excellent conductors of heat, and the heat transfer between single cells through them cannot be ignored, and this part of the heat transfer is not effectively isolated by the insulating partition.

[0006] A liquid cooling plate is also used to realize heat transfer. A cooling medium pipeline is arranged in the liquid cooling plate to transmit the cooling medium. However, due to the flow of the cooling medium in the liquid cooling plate, it is difficult to effectively isolate the heat transfer of each single battery through the liquid cooling plate.

[0007] Lithium-ion batteries have internal impedance, which can be divided into ohmic impedance and electrochemical impedance. During the charging and discharging process of the battery, due to the existence of impedance, a certain amount of heat will be generated, which will gradually increase the temperature of the battery, intensify various chemical side reactions inside the battery, and reduce the battery's cycle performance and life. Therefore, the industry usually adopts the method of placing a liquid cooling plate or an air cooling plate at the bottom of the battery to dissipate the heat of the battery, take away the heat generated by the battery operation, and keep the battery temperature below a certain value. However, these metal liquid cooling plates or air cooling plates are also excellent conductors of heat, and the heat transfer between single cells through them is also not negligible, and this part of the heat transfer is also not effectively isolated by the insulating partition. Summary of the invention

[0008] In order to overcome the problem that the battery pack in the prior art cannot achieve complete thermal isolation between single cells, the present invention provides a battery pack having an independent thermal environment and an independent heat dissipation channel, which effectively isolates the heat transfer between each single cell and achieves effective heat dissipation of each single cell.

[0009] The present invention provides a battery pack, comprising a plurality of single cells, wherein the single cells are connected by conductive connecting sheets; wherein the battery pack also comprises a heat dissipation composite plate and a plurality of heat insulation plates;

[0010] The single cells are embedded between the insulation plates, and the insulation plates are used to thermally isolate the single cells from each other;

[0011] The heat dissipation composite plate is arranged outside the battery pack, and is used to dissipate the heat of each single battery through the heat dissipation composite plate, and each single battery transfers heat to the outside independently.

[0012] The battery pack provided by the present invention, through the above-mentioned insulation plate and heat dissipation composite plate, on the one hand isolates the heat transfer between adjacent single cells, isolates the heat spread between single cells when thermal runaway occurs, effectively isolates the heat transfer between each single cell, and constructs an independent thermal environment centered on the single cell; the heat of each single cell is independently transferred out, so as to achieve a good heat dissipation effect for each single cell in the battery pack.

[0013] Furthermore, the heat dissipation composite plate includes a plurality of insulating support plates and two heat transfer plates arranged up and down between the insulating support plates; an independent heat transfer space is formed between the two heat transfer plates and each of the insulating support plates; and each heat transfer space performs heat transfer and heat dissipation for a single cell.

[0014] Furthermore, the heat transfer space is filled with a phase change material. Since the phase change material is used, the heat released by the battery is absorbed by its huge phase change latent heat, so that the heat from the single battery can be effectively absorbed, thereby improving the heat transfer and heat dissipation effect.

[0015] Furthermore, the heat transfer plate is a metal plate, which has a better heat transfer effect.

[0016] Furthermore, the metal plate is an aluminum plate.

[0017] Furthermore, at least one of the aluminum plates is a through-hole foam aluminum layer. Using the through-hole foam aluminum layer as a skeleton can improve the thermal conductivity of the heat transfer plate as a whole, improve the heat dissipation effect of the heat dissipation composite plate, timely absorb the heat generated in the independent space of the single battery, and improve the heat dissipation efficiency.

[0018] Furthermore, the heat dissipation composite plate is arranged at the bottom of the battery pack.

[0019] Furthermore, a heat drainage tube is provided on the conductive connecting sheet; a heat dissipation composite plate is also provided on the top of the battery pack; and the heat drainage tube is connected to the heat dissipation composite plate on the top of the battery pack. Since the single cells are connected through the conductive connecting sheet, and the conductive connecting sheet itself will also transfer a certain amount of heat, under the action of the heat drainage tube, the heat transferred to the conductive connecting sheet is transferred to the heat dissipation composite plate through the heat drainage tube, thereby blocking the heat diffusion on the conductive connecting sheet and reducing the heat diffusion between the single cells or the conductive connecting sheet.

[0020] Furthermore, a heat dissipation composite plate is also provided on the side of the battery pack, so that the performance of independent heat dissipation of each single battery can be further improved.

[0021] Furthermore, an explosion-proof valve is provided on the single cell, and an exhaust branch pipe is installed on the exhaust valve; the exhaust branch pipe on each single cell is connected to the exhaust main pipe. When the battery pack is in use, it is protected by the installed explosion-proof valve. When the battery pack is overheated, the explosion-proof valve on the single cell opens to release the hot gas generated by the single cell. Under the action of the exhaust branch pipe, the explosion-proof valve is connected to the exhaust branch pipe, so that the hot gas discharged from the explosion-proof valve can be discharged through the exhaust branch pipe. The exhaust branch pipe provides an exhaust channel, so that when the hot gas is discharged to the outside, the heat will not be diffused to the battery pack again, so as to achieve stable control of heat and achieve good heat dissipation protection for the entire battery pack. The hot gas discharged from the explosion-proof valve of each single cell can be further discharged from the battery pack through the exhaust main pipe.

[0022] Furthermore, each exhaust branch pipe is provided with a one-way exhaust valve, so that the hot gas released from the explosion-proof valve on the single cell can be discharged in one direction through the one-way exhaust valve, and the gas released from the other single cells will not reversely transfer heat through the exhaust branch pipe to affect the other single cells.

[0023] Further, BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of a single cell provided in a specific embodiment of the present invention;

[0025] Figure 2 is a schematic diagram of explosion and decomposition of a battery pack provided in a specific embodiment of the present invention;

[0026] Figure 3 is a three-dimensional schematic diagram of a heat dissipation composite plate provided in a specific embodiment of the present invention;

[0027] Figure 4 is a schematic diagram of a first preferred battery pack provided in a specific embodiment of the present invention;

[0028] Figure 5 is a schematic front view of a second preferred battery pack provided in a specific embodiment of the present invention;

[0029] Figure 6 It is a schematic side view of a third preferred battery pack provided in a specific embodiment of the present invention.

[0030] Among them, 1. Single battery; 2. Insulation board; 3. Conductive connecting sheet; 4. Heat dissipation composite board; 6. Exhaust system; 5. Heat drainage pipe;

[0031] 1a, adjacent side surface; 1b, end surface; 1c, intersection side surface; 1d, bottom surface; 11, explosion-proof valve; 12, electrode terminal; 121, first electrode terminal; 122, second electrode terminal;

[0032] 40. heat transfer space; 41. heat insulation support plate; 42. heat transfer plate; 43. phase change material; 4a. bottom composite plate; 4b. top composite plate; 4c. side composite plate;

[0033] 61. Exhaust main pipe; 62. Exhaust branch pipe. DETAILED DESCRIPTION

[0034] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] In the description of the present invention, it should be understood that the terms "longitudinal", "radial", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0036] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] Example 1

[0038] like Figure 1 As shown, as is well known, the single cell 1 is known to the public. In this example, a battery with a square shell is mainly used as an example for explanation. For the sake of distinction, it usually includes two large side surfaces, two small side surfaces, a top surface and a bottom surface 1d. When the single cells 1 are combined into a battery pack, their large side surfaces are usually arranged adjacent to each other. Therefore, in this patent, the large side surfaces are named adjacent side surfaces 1a, and the small side surfaces are named intersecting side surfaces 1c, and they are marked as such for the convenience of subsequent explanation. An electrode terminal 12 is generally provided on the end surface 1b of the single cell 1; the electrode terminal 12 includes a first electrode terminal 121 and a second electrode terminal 122; the first electrode terminal 121 and the second electrode terminal 122 have different polarities, for example, the first electrode terminal 121 is a positive terminal, and the second electrode terminal 122 is a negative terminal; conversely, the first electrode terminal 121 is a negative terminal, and the second electrode terminal 122 is a positive terminal; generally, an explosion-proof valve 11 is also provided on the single cell 1, which is used to quickly discharge a large amount of hot gas when a safety failure occurs inside and a large amount of hot gas is generated instantly, so as to prevent the battery from exploding.

[0039] like Figure 2As shown, this example provides a battery pack, including a plurality of single cells 1, the single cells 1 are connected by conductive connecting sheets 3; it also includes a heat dissipation composite plate 4 and a plurality of insulation plates 2; the single cells 1 are embedded between the insulation plates 2; the insulation plates 2 are used to thermally isolate the single cells 1; the connection of the single cells 1 can be series connection, parallel connection, or first series connection and then parallel connection, or first parallel connection and then series connection, etc. The specific connection method is not limited, and this example takes the series connection as an example for explanation.

[0040] The heat dissipation composite plate 4 is arranged outside the battery pack, and is used to dissipate the heat of each single battery 1 through the heat dissipation composite plate 4, and each single battery 1 transfers heat to the outside independently. In this example, the outside includes space other than the insulation plate 3, which can be used to achieve heat dissipation of each single battery 1 while isolating each single battery 1.

[0041] After the battery pack is assembled by combining individual single batteries 1, a shell is usually provided to protect it, which will not be described in detail in this article.

[0042] The specific structure of the heat dissipation composite plate 4 is not limited, as long as it can achieve independent heat transfer to each single battery 1 and does not transfer heat between the single batteries 1. As a preferred method, Figure 2 , Figure 3 As shown, the heat dissipation composite plate 4 includes a plurality of heat-insulating support plates 41 and two heat transfer plates 42 arranged up and down between each heat-insulating support plate 41; the heat-insulating support plate 41 and the heat transfer plate 42 are connected by embedding, which can ensure the stability of the structure. A heat transfer space 40 is formed between the two heat transfer plates 42 and each of the heat-insulating support plates 41. The heat-insulating support plate 41 isolates the heat between the single cells 1, and the heat transfer space 40 is formed by the two heat transfer plates 42 and the plurality of heat-insulating support plates 41. The heat transfer space 40 corresponds to each single cell 1 one by one, and the heat on the single cell 1 can be transferred to the heat dissipation space 40 through the heat transfer plate 42 for heat dissipation; the material used by the heat-insulating support plate 41 is a heat-insulating material, which prevents the heat between the two heat transfer plates 42 from being transferred through the heat-insulating support plate 41, but due to the separation of the heat-insulating support plate 41, each heat transfer space 40 is isolated from each other, and its heat will only enter the heat transfer space 40 for heat dissipation, so that it cannot be heat-transferred, and effectively achieves thermal isolation of the single cell 1.

[0043] The battery pack provided by the present invention reduces the heat transfer between adjacent single cells 1 through the above-mentioned heat dissipation composite plate 4, isolates the heat spread between single cells 1 when thermal runaway occurs, effectively isolates the heat transfer between each single cell 1, and constructs an independent thermal environment centered on the single cell 1; the heat of each single cell 1 is independently transferred out, so as to achieve a good heat dissipation effect for each single cell 1 in the battery pack.

[0044] In this example, the heat transfer space 40 is filled with a phase change material 43. Since the phase change material 43 is used, the heat released by the battery can be absorbed by its huge phase change latent heat, so that the heat from the single battery 1 can be effectively absorbed, thereby improving the heat transfer and heat dissipation effect.

[0045] It should be noted that the phase change material 43 (PCM-Phase Change Material) refers to a material that changes its state of matter and can provide latent heat without changing the temperature. The process of changing physical properties is called a phase change process. At this time, the phase change material 43 will absorb or release a large amount of latent heat. The phase change material 43 has the ability to change its physical state within a certain temperature range. Taking the solid-liquid phase change as an example, when heated to the melting temperature, a phase change from solid to liquid occurs. During the melting process, the phase change material 43 absorbs and stores a large amount of latent heat; when the phase change material 43 cools, the stored heat must be dissipated to the environment within a certain temperature range, and a reverse phase change from liquid to solid is performed. In these two phase change processes, the energy stored or released is called the phase change latent heat. When the physical state changes, the temperature of the material itself remains almost unchanged before the phase change is completed, forming a wide temperature platform. Although the temperature remains unchanged, the latent heat absorbed or released is quite large.

[0046] Classification of phase change materials 43 Phase change materials 43 mainly include three categories: inorganic PCM, organic PCM and composite PCM. Among them, inorganic PCM mainly includes crystalline hydrated salts, molten salts, metals or alloys, etc.; organic PCM mainly includes paraffin, acetic acid and other organic substances; the emergence of composite phase change thermal storage materials can not only effectively overcome the shortcomings of single inorganic or organic phase change thermal storage materials, but also improve the application effect of phase change materials 43 and expand its application range. Therefore, the development of composite phase change thermal storage materials has become a hot research topic in the field of thermal storage materials.

[0047] In a possible implementation manner, the phase change material 43 layer is paraffin or other phase change materials 43 with similar functions.

[0048] The heat transfer plate 42 can be made of solid or hollow plates with various heat transfer properties. For example, in this example, the heat transfer plate 42 is a metal plate. In this example, the material of the metal plate is not limited. For example, it can be made of aluminum plate, copper plate, etc., as long as it has good heat transfer effect. The heat transfer effect of the metal plate is better.

[0049] In this example, if Figure 2 , Figure 3 As shown, as a preferred mode, the metal plate is an aluminum plate. Furthermore, at least one of the aluminum plates is a through-hole foam aluminum layer. For example, in this example, one heat transfer plate 42 is an aluminum plate, and the other heat transfer plate 42 is a through-hole foam aluminum layer. The through-hole foam aluminum layer is used as a skeleton to improve the overall thermal conductivity of the heat transfer plate 42, improve the heat dissipation effect of the heat dissipation composite plate 4, and timely absorb the heat generated in the independent space of the single battery 1 to improve the heat dissipation efficiency.

[0050] In this example, if Figure 4 As shown, as a preferred mode, the heat dissipation composite plate 4 is arranged at the bottom of the battery pack. That is, it is arranged on one side of the bottom surface 1d of the single battery 1, and is in contact with the bottom surface 1d of each single battery 1. For convenience, the heat dissipation composite plate arranged at the bottom of the battery pack is called a bottom composite plate 4a; the bottom composite plate 4a is directly in contact with the bottom surface 1d of each single battery 1, so that it can transfer the heat of the single battery 1 to the heat transfer space 40 in the bottom composite plate 4a through its bottom surface 1d.

[0051] In this example, if Figure 5 As shown, a heat drainage pipe 5 is also provided on the conductive connecting sheet 3, and the heat drainage pipe 5 is connected to the heat dissipation composite plate 4. Since the single cells 1 are connected through the conductive connecting sheet 3, and the conductive connecting sheet 3 itself also transfers a certain amount of heat, under the action of the heat drainage pipe 5, the heat transferred to the conductive connecting sheet 3 is transferred to the outside through the heat drainage pipe 5, thereby blocking the heat diffusion on the conductive connecting sheet 3 and reducing the heat diffusion between the single cells 1 or the conductive connecting sheet 3.

[0052] like Figure 4 As shown, the heat drainage pipe 5 can be directly led to the bottom composite plate 4a arranged at the bottom of the battery pack, or a heat dissipation composite plate 4 can be arranged on the top of the battery pack, and the heat dissipation composite plate 4 is named as the top composite plate 4b; the heat drainage pipe 5 is connected to the top composite plate 4b at the top of the battery pack. In this example, the top of the battery pack is also the end surface 1b of each single battery 1, and the heat drainage pipe 5 on the end surface 1b of the single battery 1 is connected to the top composite plate 4b.

[0053] In this example, the heat pipe 5 is preferably a heat pipe. The heat pipe technology is well known to the public. As early as 1963, the Los Alamos National Laboratory in the United States invented a heat transfer element called a "heat pipe". It fully utilizes the principle of heat conduction and the rapid heat transfer properties of phase change media. Through the heat pipe, the heat of the heating object is quickly transferred to the outside of the heat source. Its thermal conductivity exceeds the thermal conductivity of any known metal. The heat pipe mainly relies on the vapor and liquid phase change of the working fluid to transfer heat. The thermal resistance is very small, so it has a very high thermal conductivity. A typical heat pipe consists of a tube shell, a liquid wick and an end cap. After the tube is evacuated to a negative pressure, it is filled with an appropriate amount of working liquid, so that the capillary porous material of the liquid wick close to the inner wall of the tube is filled with liquid and then sealed. Generally, one end of the heat pipe is an evaporation section (heating section) and the other end is a condensation section (cooling section). According to application needs, an insulation section can be arranged between the two sections. When one end of the heat pipe is heated, the liquid in the wool core evaporates and vaporizes. The steam flows to the other end under a small pressure difference, releasing heat and condensing into liquid. The liquid then flows back to the evaporation section along the porous material by capillary force. This cycle continues, and heat is transferred from one end of the heat pipe to the other end. The structure of the heat pipe itself is well known to the public and will not be described in detail.

[0054] When a lithium-ion battery is in thermal runaway, its explosion-proof valve 11 will open, releasing a large amount of hot gas generated by the side reaction, which will transfer a large amount of heat between the single cells 1 and must also be effectively thermally isolated and discharged from the battery pack and battery package through an insulated fixed channel. This gas is highly flammable, so its discharge channel must be sealed and must be ensured not to come into contact with electronic components. Therefore, if Figure 5 As shown, as a preferred method, an exhaust system 6 is also provided in this example, and the exhaust system 6 includes an exhaust branch pipe 61 and an exhaust main pipe 62; in this example, an explosion-proof valve 11 is provided on the single cell 1, and an exhaust branch pipe 61 is installed on the explosion-proof valve 11. When the battery pack is in use, it is protected by the installed explosion-proof valve 11. When the battery pack is overheated inside, the explosion-proof valve 11 on the single cell 1 opens to release the burning gas generated by the single cell 1, and under the action of the exhaust branch pipe, the explosion-proof valve 11 is connected with the exhaust branch pipe 61, so that the burning gas discharged from the explosion-proof valve 11 can be discharged through the exhaust branch pipe 61, and the exhaust branch pipe 61 provides an exhaust channel, so that when the burning gas is discharged to the outside, the heat will not be diffused to the battery pack again, so as to achieve stable control of heat and achieve good heat dissipation protection for the entire battery pack. The above-mentioned exhaust branch pipe 61 can be discharged from the battery pack through a separately set exhaust channel, or the exhaust branch pipe 61 on each single cell 1 can be connected to the exhaust main pipe 62 as in this example. In this way, the hot gas discharged from the explosion-proof valve 11 of each single battery 1 can be further discharged through the exhaust main pipe 62 .

[0055] As a preferred embodiment, a one-way exhaust valve is provided in each exhaust branch pipe 61. In this way, the hot gas released from the explosion-proof valve 11 on the single battery 1 can be discharged in one direction through the one-way exhaust valve, and the gas released from the other single batteries 1 will not reversely transfer heat through the exhaust branch pipe 4 to affect the other single batteries 1.

[0056] As a preferred method, Figure 6 As shown, a heat dissipation composite plate 4 is also provided on the side of the battery pack. For the sake of distinction, the heat dissipation composite plate here is named as a side composite plate 4c. The so-called side of the battery pack here refers to the side of the intersection side 1c of each single battery, that is, the side composite plate 4c is placed on the intersection side 1c of each single battery 1, and the heat transfer plate 42 in the side composite plate 4c is attached to the intersection side 1c of each single battery 1, and transfers heat to the corresponding heat transfer space 40 in the side composite plate 4c. Heat is dissipated through the phase change material 43 in the heat transfer space 40 in each side composite plate 4c.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A battery pack, comprising a plurality of single cells, wherein the single cells are connected by conductive connecting sheets; characterized in that: It also includes heat dissipation composite panels and several insulation panels; The single cells are embedded between the insulation plates, and the insulation plates are used to thermally isolate the single cells from each other; The heat dissipation composite plate is arranged outside the battery pack, and is used to dissipate the heat of each single battery through the heat dissipation composite plate, and to make each single battery independently transfer heat; The heat dissipation composite plate comprises a plurality of heat-insulating support plates and two heat transfer plates arranged above and below each of the heat-insulating support plates; an independent heat transfer space is formed between the two heat transfer plates and each of the heat-insulating support plates; each heat transfer space is used to transfer heat and dissipate heat for a single battery; The heat dissipation composite plate is arranged at the bottom of the battery pack; A heat drainage tube is arranged on the conductive connecting sheet; a heat dissipation composite plate is also arranged on the top of the battery pack; and the heat drainage tube is connected to the heat dissipation composite plate on the top of the battery pack.

2. The battery pack according to claim 1, characterized in that: The heat transfer space is filled with phase change material.

3. The battery pack according to claim 2, characterized in that: The heat transfer plate is a metal plate.

4. The battery pack according to claim 3, characterized in that: The metal plate is an aluminum plate.

5. The battery pack according to claim 4, characterized in that: At least one of the aluminum plates is a through-hole foam aluminum layer.

6. The battery pack according to claim 1, characterized in that: The side of the battery pack is also provided with a heat dissipation composite plate.

7. The battery pack according to claim 1, characterized in that: The single cell is provided with an explosion-proof valve, and an exhaust branch pipe is installed on the explosion-proof valve; the exhaust branch pipe on each single cell is connected to the exhaust main pipe.

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