CN201364917Y - Power battery pack - Google Patents

Abstract

The utility model provides a power battery pack with reliable connection and good power output performance. The power battery pack includes a plurality of single cells (5), and the plurality of single cells (5) are connected by electrode terminals (1, 2) connected in series or in parallel, the electrode terminals (1, 2) are sheets, and the electrode terminals (1, 2) are connected through an intermediate connector (3) with a buffer function, and the electrodes The connection relationship between the terminals (1, 2) and the intermediate connector (3) is a snug connection. The intermediate connector (3) with a buffer function can buffer stress when the electrode terminals (1, 2) are impacted by a load, so as to ensure reliable connection of the electrode terminals (1, 2). In addition, the utility model can also use the memory alloy material or the bimetal sheet structure for the intermediate connecting piece (3), so that it has an automatic disconnection function when the power battery pack is overheated. The utility model is mainly used for electric/hybrid vehicles.

Description

Power battery pack

technical field

The utility model relates to a power battery pack. The power battery pack includes a plurality of single cells connected in series or in parallel through electrode terminals to form a power battery pack.

Background technique

In today's society, with the improvement of people's living standards, the number of cars is also increasing year by year. Exhaust emissions caused by fuel vehicles are an important factor in environmental pollution. Therefore, new energy vehicles such as electric vehicles or hybrid vehicles emerge as the times require, and they represent a development direction of future automobiles.

In electric vehicles, the core is the power battery pack as the power source. At present, lithium-ion batteries have become the preferred power source for people due to their advantages such as high energy density, safety, and small size. The single cells of the power battery pack can be connected in series or in parallel to form a power battery pack to meet various power demands of the vehicle. The electrode terminals of each single battery are connected correspondingly so that the single batteries are connected in series or in parallel, thereby forming a power battery pack. Obviously, since the power output of the power battery is extremely dependent on the connection structure of the electrode terminals, the connection structure between the electrode terminals of each single battery has a great influence on the performance of the power battery, the reliability of the connection structure, internal resistance, etc. It is closely related to the stability and power output performance of the power battery.

Traditional power batteries are generally connected to the electrode terminals by screw fastening, and the two single cells are connected together through the connecting piece. This electrode extraction method has disadvantages such as large output internal resistance and heavy weight. In view of this, Chinese utility model patent CN201051525 discloses a power battery pack. As shown in FIG. 1 , each single battery of the power battery pack adopts sheet-shaped electrode terminals 1 and 2 , and the connection relationship between the sheet-shaped electrode terminals 1 and 2 is a bonding connection. This utility model patent replaces the traditional electrode terminals with sheet electrode terminals 1 and 2, which greatly reduces the output internal resistance, improves the power output performance of the battery pack, and at the same time reduces the weight of the battery pack. However, in this patent, since the sheet electrode terminals 1 and 2 are directly connected together by welding, there is no buffer between the two, so when the battery pack is hit by an external force, due to the electrode terminals 1, 2 2 The load borne cannot be buffered, and the connected electrode terminals 1 and 2 will interact with each other, so that the electrode terminals 1 and 2 are easily damaged and the connection will be loosened or even disconnected, which will affect the output performance of the battery. Reliability is also greatly reduced.

Utility model content

The technical problem to be solved by the utility model is to provide a power battery pack with reliable connection and good power output performance.

In order to solve the above technical problems, the utility model provides a power battery pack, the power battery pack includes a plurality of single cells, the multiple single cells are connected in series or in parallel through electrode terminals, and the electrode terminals are sheet Shaped body, the electrode terminals are connected through an intermediate connector with a buffer function, and the connection relationship between the electrode terminal and the intermediate connector is a snug connection.

As a preferred solution of the present invention, the middle part of the intermediate connector is at least one layer of metal foil or a metal wire with a cross-linked structure.

The material of the intermediate connector is copper aluminum alloy.

The intermediate connecting piece is a plate processing piece.

形)。The shape of the intermediate connector is U-shaped, inverted U-shaped, or N-shaped mirror image (

shape).

The electrode terminal and the intermediate connector are connected by cold pressure welding, ultrasonic welding, laser welding, brazing, flash butt welding, friction welding, or resistance welding.

The electrode terminals are configured to be bent and led out from the battery cover, and then connected to the intermediate connector after being bent one or more times.

The bending angle of the electrode terminals is preferably 90°.

As another preferred solution of the present invention, the adhesive connection between the electrode terminal and the intermediate connector of the present invention is configured to have an automatic disconnection function when the power battery pack is overheated.

The intermediate connecting piece is formed of memory alloy material.

The memory alloy can be a copper-based or iron-based metal alloy

The intermediate connector is a double-layer metal sheet, and the thermal expansion coefficients of the metal sheets in the double-layer metal sheet are different from each other.

A metal having a melting point lower than that of the electrode terminal and the intermediate connector may be filled between the contact surfaces where the intermediate connector and the electrode terminal are snugly connected.

The low-melting-point metal to be filled is tin alloy.

Compared with the prior art, the utility model has the following advantages: the stress of the electrode terminals in the collision process can be buffered by introducing an intermediate connector with a buffer function between the electrode terminals. When the power battery pack is impacted by an external force, once a load acts on the electrode terminal, the electrode terminal will transmit the load to the intermediate connector. Since the intermediate connector is a thin plate or similar structural member, Therefore, the intermediate connector can produce a certain deformation to attenuate the load. At the same time, because the connection between the intermediate connector and the electrode terminal is a snug connection, the connection area is relatively large, and the intermediate connector buffers the load. A small amount of deformation at the time cannot damage its connection with the electrode terminals, thereby effectively ensuring the reliability of the power battery pack. Moreover, since the electrode terminal is a sheet-shaped body, the connection between it and the intermediate connector is an adhesive connection, and the internal resistance is small, which can optimize the power output performance of the power battery pack. Therefore, through the above-mentioned technology of the utility model The solution is to form a power battery pack with reliable connection and excellent power output performance.

In a preferred solution of the present utility model, the middle part of the intermediate connector is at least one layer of soft metal foil or a metal wire with a cross-linked structure. When the power battery pack is impacted by external force, once the electrode terminal is impacted by the load, the electrode terminal will transfer the load to the intermediate connector, and the intermediate connector itself has the function of attenuating the load through a certain deformation. When the intermediate portion is designed as at least one layer of soft metal foil or metal wire with a cross-linked structure, since the soft metal foil or metal wire with a cross-linked structure has excellent flexibility, the intermediate portion can effectively absorb the gap between the battery pack. impact stress, so that the electrode terminals are protected from damage, thereby further enhancing the connection reliability of the power battery pack of the utility model.

In addition, in another improvement of the utility model, the intermediate connector is designed in the form of a memory alloy sheet or a bimetallic sheet, or a low melting point metal is filled between the intermediate connector and the electrode terminal , so that the battery pack can avoid a series of safety hazards caused by excessive temperature. When the battery is abnormal and the temperature rises sharply, the memory alloy or bimetal sheet will play a role, or the low-melting point metal will automatically melt, so that the intermediate connector and the electrode terminal will be disconnected, so that the battery pack will be disconnected and the battery pack will not be damaged due to overheating. The performance changes or side reactions of the positive and negative materials inside the battery will lead to dangerous consequences such as battery explosion.

Description of drawings

Fig. 1 is a schematic diagram of a power battery pack in the prior art.

Fig. 2a-Fig. 2d are schematic diagrams of the connection of the electrode terminals of the power battery pack of the utility model through intermediate connectors;

Fig. 3 is a connection schematic diagram of an embodiment of a power battery pack with an automatic disconnection function;

Fig. 4 is a connection schematic diagram of another embodiment of a power battery pack with an automatic disconnection function;

Fig. 5 is a connection schematic diagram of another embodiment of a power battery pack with self-use disconnection function;

Fig. 6 is a perspective view of the power battery pack of the present utility model.

Detailed ways

The specific embodiment of the utility model will be described in detail below in conjunction with the accompanying drawings.

As shown in FIG. 5 , the power battery pack includes a plurality of single cells 5 , and the single cells 5 may be various single cells suitable for forming a power battery pack, such as alkaline secondary batteries, lithium-ion batteries, and the like. Each single battery 5 has a positive terminal 1 and a negative terminal 2, and the single batteries 5 can be connected in series or in parallel by various known methods or connection sequences. In FIG. 5 , the single cells 5 are connected in series, one electrode terminal of one single cell 5 is connected to the opposite polarity electrode terminal of another adjacent single cell 5 , and the other single cell The other electrode terminal of 5 is connected to the opposite polarity electrode terminal of the next adjacent single battery 5, and so on. Specifically, in FIG. 5 , the single cells 5 are connected in series as follows: the positive terminal 1 of the single cell 5 at one end is connected to the negative terminal 2 of the adjacent single cell 5 , and the adjacent single cell The positive terminal 1 of 5 is connected to the negative terminal 2 of the next adjacent single battery 5, and so on, and the electrode terminals 1 and 2 with opposite polarities of two adjacent single batteries 5 are connected to each other, finally forming There is an electrode terminal at both ends of the power battery pack for connection, and the polarities of the two electrode terminals 1 and 2 are opposite, so as to serve as the positive and negative poles of the power battery pack.

The electrode terminals 1 and 2 of each single battery 5 in Fig. 5 are both sheet-shaped bodies, but different from the Chinese utility model patent CN201051525, in this utility model, the electrode terminals of adjacent single battery 5 have opposite polarities 1, 2 are not directly connected, but are connected through an intermediate connector 3.

型)，其同样插在两个极性相反的电极端子1，2之间进行连接。在图2d中，中间连接件3形成为倒U型，该中间连接件3的中间开口相对宽一些，将两个极性相反的电极端子1，2夹持在中间开口内，也就是将两个极性相反的电极端子1，2插在该中间连接件3的中间开口内进行连接。当然，中间连接件3可以形成为各种形状，并不限于上述附图中显示的中间连接件3的形状。As shown in Figure 2a, Figure 2b, Figure 2c and Figure 2d, wherein, in Figure 2a, the intermediate connector 3 is U-shaped, which is inserted between two electrode terminals 1, 2 with opposite polarities to connect the two Each electrode terminal 1,2. In Fig. 2b, among Fig. 2c, intermediate connector 3 is respectively formed as the mirror image figure of inverted U shape, N shape (

type), which are also inserted between two oppositely polarized electrode terminals 1, 2 for connection. In Fig. 2d, the intermediate connector 3 is formed in an inverted U shape, and the middle opening of the intermediate connector 3 is relatively wider, and the two electrode terminals 1 and 2 with opposite polarities are clamped in the middle opening, that is, the two Two electrode terminals 1 and 2 with opposite polarities are inserted into the middle opening of the middle connector 3 for connection. Of course, the intermediate connecting piece 3 can be formed in various shapes, and is not limited to the shape of the intermediate connecting piece 3 shown in the above-mentioned figures.

型)等形状。因为中间连接件3为板材加工件，而电极端子1，2亦为片状体，因而它们之间能够容易地形成贴合连接，从而所述电极端子1，2与中间连接件3形成面接触，并使得有效焊接面积为该电极端子相应连接部位截面积的0.5倍～4倍。当然，中间连接件3并不必然为板材加工件，只要能保证与电极端子1，2形成贴合连接，各种结构都是可以的，例如，所述中间连接件3可以是由细圆形的金属型材折弯为U型，再在该U型件两端各焊接一个连接片，以与电极端子1，2形成贴合连接。中间连接件的材质可为同种金属如铜、镍等，也可为Cu-Al、Cu-Ni等复合金属。In Figure 2a, Figure 2b, Figure 2c and Figure 2d, in order to ensure the reliability of the connection between the electrode terminals 1, 2 and the intermediate connector 3, the connection method between the electrode terminals 1, 2 and the intermediate connector 3 is a bonding connection . The so-called bonding connection refers to a connection in which the electrode terminals 1, 2 and the intermediate connector 3 form surface contact. The bonding connection between the electrode terminals 1, 2 and the intermediate connector 3 can not only ensure the connection strength of the electrode terminals 1, 2, but also cooperate with the sheet-like electrode terminals 1, 2 to reduce the internal pressure of the power battery connection structure. Resistance, improve power output performance. Correspondingly, in order to form a bonded connection with the electrode terminals 1 and 2 of the sheet body and facilitate processing, the intermediate connectors 3 shown in the figure are all plate parts, and the plates are formed into U by known processes such as bending. The mirror images of type, inverted U, N type (

type) and other shapes. Because the intermediate connecting piece 3 is a processed piece of plate material, and the electrode terminals 1, 2 are also sheet-shaped bodies, they can easily form a bonding connection between them, so that the electrode terminals 1, 2 form surface contact with the intermediate connecting piece 3 , and the effective welding area is 0.5 to 4 times the cross-sectional area of the corresponding connection part of the electrode terminal. Certainly, the intermediate connecting piece 3 is not necessarily a sheet material processing piece, as long as it can ensure the formation of a bonded connection with the electrode terminals 1, 2, various structures are all possible, for example, the intermediate connecting piece 3 can be made of a thin round The metal profile is bent into a U-shape, and then a connecting piece is welded at both ends of the U-shaped piece to form a bonding connection with the electrode terminals 1 and 2. The material of the intermediate connector can be the same metal such as copper, nickel, etc., or composite metals such as Cu-Al, Cu-Ni, etc.

The electrode terminals 1, 2 are bent and led out from the battery cover, and then connected to the corresponding electrode terminals 1, 2 through the intermediate connector 3 after one or more bends. The bending angle of the electrode terminals 1 and 2 may be 0°-180°, preferably 90°.

The electrode terminals 1, 2 and the intermediate connector 3 are connected together by cold pressure welding, ultrasonic welding, laser welding, brazing, flash butt welding, friction welding, resistance welding and the like.

It can be seen that the power battery pack of the utility model is characterized by the connection structure of the electrode terminals 1 and 2, and the performance of the power battery pack is optimized by introducing an intermediate connector 3 between the electrode terminals 1 and 2. The function of the intermediate connector 3 is that when the power battery pack is impacted by an external force, once a load acts on the electrode terminals 1 and 2, the electrode terminals 1 and 2 will transmit the load to the intermediate connector 3, because the intermediate connector 3 is thin Thin plate or similar structural parts, so the intermediate connector 3 can produce a certain deformation to attenuate the load. At the same time, because the connection between the intermediate connector 3 and the electrode terminals 1 and 2 is a fit connection, the connection area is relatively small. Large, the slight deformation of the intermediate connector 3 when the load is attenuated cannot damage its connection with the electrode terminals 1, 2, thereby effectively ensuring the reliability of the power battery pack. Moreover, since the electrode terminals 1 and 2 are sheet-shaped bodies, the connection between them and the intermediate connector 3 is an adhesive connection, and the internal resistance is small, which can optimize the power output performance of the power battery pack. Therefore, through the above-mentioned technology of the utility model The solution is to form a power battery pack with reliable connection and excellent power output performance.

Further preferred implementations of the power battery pack of the present utility model are described below.

In order to further improve the cushioning function of the intermediate connecting piece 3, the load can be effectively damped. As shown in Fig. 2a, the middle part 3a of the U-shaped intermediate connector 3 has an enhanced cushioning function, and the middle part 3a is at least one layer of soft metal foil or a metal wire with a cross-linked structure, and the metal foil or metal wire The material is preferably Cu foil or Cu wire. Also in Fig. 2b, Fig. 2c and Fig. 2d, the intermediate parts 3b, 3c, 3d of the intermediate connector 3 can also be at least one layer of soft metal foil or metal wire with a cross-linked structure. When the power battery pack is impacted by external force, once the electrode terminals 1 and 2 are impacted by the load, the electrode terminals 1 and 2 will transfer the load to the intermediate connector 3, and the intermediate connector 3 itself has the function of attenuating the load through slight deformation. When the middle part 3a, 3b, 3c, 3d is designed as at least one layer of soft metal foil or a metal wire with a cross-linked structure, since the soft metal foil or the metal wire with a cross-linked structure has excellent flexibility, the The middle parts 3a, 3b, 3c, 3d can effectively absorb the impact stress between the battery packs and protect the electrode terminals from damage, thereby further enhancing the connection reliability of the power battery pack of the present invention.

In addition, the intermediate connector 3 of the power battery pack of the present invention can be further improved to prevent the battery from thermal runaway and other dangerous consequences, thereby improving the safety and reliability of the battery pack. For example, the intermediate connector 3 can be designed in the form of a memory alloy sheet or a bimetal sheet. When the battery is abnormal and the temperature rises sharply, the memory alloy or bimetal sheet will play a role, so that the intermediate connector 3 and the electrode terminal 1, 2 Disconnect, so that the power battery pack is disconnected, avoiding the performance change or side reaction of the positive and negative electrode materials inside the battery due to overheating of the battery pack, which will lead to dangerous consequences such as battery explosion. The typical implementation of the power battery pack with automatic disconnection function will be specifically described below with reference to FIG. 3 , FIG. 4 , and FIG. 5 .

As shown in FIG. 3 , the intermediate connecting piece 3 is U-shaped, which is inserted between the electrode terminals 1 and 2 for connection, and the intermediate connecting piece is made of memory alloy. Memory alloys can be Cu-based or Fe-based metal alloys. Such as Cu-Zn, Cu-Zn-Al alloy, Cu-Al-Ni or Fe-Mn-Si alloy. In this embodiment, a Cu-Al-Ni alloy is used. First, the intermediate connector 3 is pre-processed into a shape with a bending angle of less than 90°, and then heat-treated at a high temperature of 300-1000° C. for several minutes to make it have a memory effect. Furthermore, the bending angle of the intermediate connector 3 is formed to be 90°, and it is connected to the electrode terminals 1 and 2 by a known welding technique. When the temperature of the battery rises, the memory alloy automatically exerts its memory function when heated, and recovers to a bending angle of less than 90°, that is, the two ends of the U-shaped intermediate connector 3 shrink inward, thereby detaching from the electrode terminals 1 and 2 and falling off , to avoid further heating of the battery pack.

型等形状并插在电极端子1，2进行连接时，可以进行类似的记忆效果处理，以使中间连接件3具有自动断开功能。当中间连接件3为倒U型，并且将电极端子1，2夹持在中间开口内进行连接时(参照图2d)，可以首先将将中间连接件3预先加工成弯折角度大于90°的形状，然后在300-1000℃高温下热处理几分钟，使其具有记忆效应。进而再使中间连接件3的弯折角度形成为90°，将其通过公知的焊接技术连接在电极端子1，2上。当电池温度升高后，记忆合金受热自动发挥其记忆功能，向大于90°的弯折角度恢复，即U型中间连接件3的两端向外伸展，从而使中间连接件3与电极端子1，2脱离，避免电池组进一步发热，为防止在图2d中的情形下，倒U型中间连接件3与电极端子1，2脱离后继续挂在电极端子1，2上，可类似于图5中那样，在电极端子1，2的上端与中间连接件3之间，即4处增设橡胶类绝缘件。Similarly, when the intermediate connector 3 is inverted U-shaped,

When plugged into the electrode terminals 1 and 2 for connection, similar memory effect processing can be performed so that the intermediate connector 3 has an automatic disconnection function. When the intermediate connecting piece 3 is inverted U-shaped, and the electrode terminals 1 and 2 are clamped in the middle opening for connection (refer to FIG. 2d), the intermediate connecting piece 3 can be pre-processed into a bending angle larger than 90°. Shape, and then heat treatment at 300-1000°C for a few minutes to make it have a memory effect. Furthermore, the bending angle of the intermediate connector 3 is formed at 90°, and it is connected to the electrode terminals 1 and 2 by a known welding technique. When the temperature of the battery rises, the memory alloy automatically exerts its memory function when heated, and recovers to a bending angle greater than 90°, that is, the two ends of the U-shaped intermediate connector 3 stretch outward, so that the intermediate connector 3 and the electrode terminal 1 , 2 is disengaged to avoid further heating of the battery pack. In order to prevent the situation in Figure 2d, the inverted U-shaped intermediate connector 3 is separated from the electrode terminals 1 and 2 and continues to hang on the electrode terminals 1 and 2, which can be similar to Figure 5 In the same way, between the upper ends of the electrode terminals 1, 2 and the intermediate connector 3, that is, rubber-type insulating parts are added at 4 places.

As shown in Fig. 4, the intermediate connector 3 is made of two layers of metal sheets 31, 31' with different coefficients of thermal expansion firmly bonded to each other, such as bimetal sheets such as Fe-Ni or Fe-Cu. The intermediate connector 3 is U-shaped, and is inserted between the electrode terminals 1 and 2 for connection. When the temperature of the battery rises, the bimetallic strips 31, 31' are heated, and the metal layer 31 with a high coefficient of thermal expansion is subjected to heat when it is freely elongated. Contained by the metal layer 31 ′ with a small thermal expansion coefficient, it actively bends inward. When this inward bending stress exceeds the connection force between the electrode terminals 1, 2 and the intermediate connector 3, the bimetallic strips 31, 31' are separated from the electrode terminals 1, 2, causing the battery pack to be disconnected, preventing the battery pack from further fever. Similarly, as shown in Fig. 5, the intermediate connector 3 is made of two layers of metal sheets 32, 32' with different thermal expansion coefficients firmly bonded to each other, such as bimetal sheets such as Fe-Ni or Fe-Cu. The intermediate connector 3 is an inverted U shape, and the electrode terminals 1 and 2 are clamped in the middle opening for connection. When the temperature of the battery rises and the bimetallic strips 32 and 32' are heated, the metal layer 32 with a high thermal expansion coefficient is free. When stretched, it is constrained by the metal layer 32' with a small thermal expansion coefficient, and actively bends outward. When the stress of this outward bending exceeds the connection force between the electrode terminals 1, 2 and the intermediate connector 3, the bimetallic strips 32, 32' are separated from the electrode terminals 1, 2, causing the battery pack to be disconnected, preventing the battery pack from further fever. In Fig. 5, in order to ensure that the bimetallic strips 32, 32' are completely disconnected from the electrode terminals 1, 2, a rubber insulating piece is added at the contact point 4 between the metal strip 32' and the electrode terminals 1, 2 to ensure After the bimetal strip 32 ′ is separated from the electrode terminals 1 and 2 , it is insulated from the upper ends of the electrode terminals 1 and 2 .

The power battery pack of the utility model is not limited to adopting the above-mentioned method to make the power battery pack have an automatic disconnection function under overheating conditions, but can adopt other various methods, for example, between the intermediate connector 3 and the electrode terminals 1, 2 The interspace is filled with a metal whose melting point is lower than that of the electrode terminals 1, 2 and the intermediate connector 3. The melting temperature of the low melting point metal is 150-250°C. Such as Sn, gold-20%Sn, lead-5%Sn, Ag-Sn, etc. When the battery is overheated, the low-melting-point metal is melted in advance, so that the intermediate connecting piece and the lead-out piece are disconnected or fall off, and the dangerous consequences such as explosion caused by further heating of the battery pack are avoided.

The utility model has been described above in conjunction with the preferred embodiment of the utility model, but the utility model is not limited to the specific shape of the above-mentioned components, for example, the shape of the intermediate connector 3, the series and parallel relationship of the single cells 5, etc. Modifications can be made as required, and the protection scope of the utility model is defined by the claims.

Claims (14)

1. A power battery pack, which comprises a plurality of single cells (5), connected in series or in parallel by electrode terminals (1, 2) between the multiple single cells (5), the electrodes The terminals (1, 2) are sheet-shaped bodies, characterized in that the electrode terminals (1, 2) are connected through an intermediate connector (3) having a buffer function, and the electrode terminals (1, 2) The connection relationship with the intermediate connector (3) is a fit connection. 2. The power battery pack according to claim 1, characterized in that, the middle part (3a, 3b, 3c, 3d) of the intermediate connector (3) is at least one layer of metal foil or a metal with a cross-linked structure Silk. 3. The power battery pack according to claim 2, characterized in that, the material of the intermediate connector (3) is copper-aluminum alloy. 4. The power battery pack according to claim 3, characterized in that, the intermediate connecting piece (3) is a plate processed piece. 5. The power battery pack according to claim 4, characterized in that, the intermediate connector (3) is formed in a U-shape, an inverted U-shape, or a mirror image of an N-shape. 6. The power battery pack according to claim 5, characterized in that, the electrode terminals (1, 2) and the intermediate connector (3) are welded by cold pressure welding, ultrasonic welding, laser welding, brazing, or flash welding. Connections are made by butt welding, friction welding, or resistance welding. 7. The power battery pack according to claim 6, characterized in that, the electrode terminals (1, 2) are configured to be bent and drawn out from the battery cover, and then connected to the said electrode terminals after one or more bends. The intermediate connector (3) is connected. 8. The power battery pack according to claim 7, characterized in that, the bending angle of the electrode terminals (1, 2) is 90°. 9. The power battery pack according to claim 1, characterized in that, the adhesive connection between the electrode terminals (1, 2) and the intermediate connector (3) is configured to be It has an automatic disconnect function when it is overheated. 10. The power battery pack according to claim 9, characterized in that, the intermediate connector (3) is formed of a memory alloy material. 11. The power battery pack according to claim 10, wherein the memory alloy is a copper-based metal alloy or an iron-based metal alloy. 12. The power battery pack according to claim 9, characterized in that, the intermediate connector (3) is a double-layer metal sheet (31, 31'; 32, 32'), and the double-layer metal sheet (31, 31'; 32, 32') the thermal expansion coefficients of the metal sheets are different from each other. 13. The power battery pack according to claim 9, characterized in that, the contact surface between the intermediate connector (3) and the electrode terminals (1, 2) is filled with a material with a melting point lower than The metal of the electrode terminals (1, 2) and the intermediate connecting piece (3). 14. The power battery pack according to claim 13, characterized in that, the low-melting-point metal filled is a tin alloy.

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