WO2024183210A1 - Battery pack - Google Patents

Abstract

A battery pack, relating to the technical field of batteries. The battery pack comprises a housing and a battery module provided in a mounting cavity of the housing; the battery module comprises a lower support and a lower connecting piece that are attached to each other, and comprises an upper support and an upper connecting piece that are attached to each other; the lower support and the lower connecting piece are each provided with heat dissipation openings; the lower connecting piece and the upper connecting piece are each provided with conductors; and each conductor is located in a corresponding heat dissipation opening. The conductor is attached to a polar end of a battery cell in the mode of not wrapping the polar end of the battery cell, and compared with a traditional mode of connecting the polar end of the battery cell in a welding mode, blocking of a welding layer to thermal energy generated by the polar end of the battery cell is reduced, thereby facilitating improvement of the heat dissipation effect on the polar end of the battery cell. Moreover, when the battery pack is used for supplying power or storing power, the thermal energy generated by the portion of the polar end of the battery cell that is in contact with the conductors, and the thermal energy generated by an edge portion (which is not in contact with the conductors) of the polar end of the battery cell can also be dissipated in the heat dissipation openings, thereby facilitating further improvement of the heat dissipation effect.

Description

Battery Pack Technical Field

The present invention relates to the technical field of batteries, and in particular to a battery pack.

Background Art

The application of battery technology makes it inseparable from people's lives. With the development of science and technology, the requirements for battery capacity and voltage have also increased. As a result, battery packs have been developed. The composition of a battery pack is generally to connect several battery cells in series and in parallel by welding equipment to form a welding fixation, and then assemble it with accessories such as battery cover, battery bracket and battery shell.

In the existing battery pack assembly process, several battery cells are connected in series and parallel by welding, which will cause the polar ends of the battery cells to be wrapped and covered by the welding layer. The heat generated is easily concentrated on the polar ends of the battery cells, which is not conducive to the heat dissipation of the polar ends of the battery cells and affects the stable use of the battery pack.

Technical issues

The purpose of the present invention is to solve the problem in the prior art that the battery pack uses welding to connect battery cells in series and in parallel, which causes the polar ends of the battery cells to be wrapped and covered, and the heat generated by the battery cells is concentrated at the polar ends of the battery cells, which is not conducive to the heat dissipation of the polar ends of the battery cells and affects the stable use of the battery pack.

Technical Solutions

To achieve the above-mentioned purpose, the present invention adopts the following technical solution: a battery pack, comprising a shell and a battery module arranged in the mounting cavity of the shell, wherein at least two battery packs with opposite electrode directions are arranged in the battery module, and the two battery packs are connected in series, and the battery pack contains a plurality of battery cells with the same electrode direction.

The battery module includes a lower bracket and a lower connecting plate that fit together, and an upper bracket and an upper connecting plate that fit together.

The lower bracket and the upper bracket are both provided with heat dissipation holes, the lower connecting plate and the upper connecting plate are both provided with conductors, the conductors are located in the heat dissipation holes and contact the polarity ends of the battery cells, and the lower connecting plate and the upper connecting plate respectively connect the battery cells with the same electrode directions in parallel.

The polarity end of the battery cell refers to the electrode, and the conductor can be a copper sheet or a nickel sheet.

Furthermore, in an embodiment of the present invention, the upper connecting plate and the lower connecting plate are respectively provided with a plurality of conductors, the upper connecting plate is a conductive metal part or the upper connecting plate is provided with a circuit for connecting the conductors, the lower connecting plate is a conductive metal part or the lower connecting plate is provided with a circuit for connecting the conductors, and the upper connecting plate and the lower connecting plate are used to electrically connect the plurality of conductors of the upper connecting plate.

Furthermore, in an embodiment of the present invention, the conductor of the lower connecting sheet protrudes from the plane of the lower connecting sheet, and the conductor of the upper connecting sheet protrudes from the plane of the upper connecting sheet. The lower connecting sheet and the upper connecting sheet are provided with heat dissipation holes at positions corresponding to the conductors on each of them, and the heat dissipation holes are communicated with the mounting cavity. The heat energy generated by the battery cell can be directly transferred to the conductor, and the air medium in the heat dissipation holes can conduct heat dissipation to the conductor, and then dissipate it in the heat dissipation holes, and then dissipate it to the mounting cavity of the shell through the heat dissipation holes, which greatly diffuses the heat energy on the polarity end of the battery cell, making it difficult for the heat energy to be concentrated on the polarity end of the battery cell, affecting the stable use of the battery cell.

Furthermore, in an embodiment of the present invention, the conductor is smaller than the heat dissipation port, a heat dissipation gap is left between the conductor and the side wall of the heat dissipation port, the heat dissipation gap is connected to the heat dissipation hole, and the heat dissipation port is connected to the installation cavity through the heat dissipation hole. Therefore, the heat energy generated by the polarity end of the battery cell can be directly dissipated into the heat dissipation port through the heat dissipation gap for heat dissipation, so that the heat energy is not easily concentrated on the polarity end of the battery cell.

Furthermore, in an embodiment of the present invention, the battery module further includes an upper cover plate and a lower cover plate, the upper cover plate is fixedly connected to the upper bracket, and the lower cover plate is fixedly connected to the lower bracket.

The upper cover plate is attached to the upper connecting piece, and the upper connecting piece is pressed and fixed on the upper bracket.

The lower cover plate is attached to the lower connecting piece, and the lower connecting piece is pressed and fixed on the lower bracket.

Furthermore, in an embodiment of the present invention, the upper cover plate and the lower cover plate are each provided with an escape groove, the upper cover plate escape groove corresponds to the upper bracket heat dissipation hole, and the upper bracket heat dissipation hole is connected with the housing installation cavity through the upper cover plate escape groove, so that the heat energy generated by the polarity end of the battery cell can be dissipated through the heat dissipation port and the heat dissipation hole to the housing installation cavity for heat dissipation treatment.

The lower cover plate avoidance groove corresponds to the lower bracket heat dissipation hole, and the lower bracket heat dissipation hole is connected with the shell installation cavity through the lower cover plate avoidance groove.

Furthermore, in an embodiment of the present invention, the lower cover is fixed to the bottom of the shell mounting cavity, and a non-conductive snap-fit structure is provided between the upper cover and the shell, one end of the snap-fit structure is snap-fitted to the shell, and the other end of the snap-fit structure is snap-fitted to the upper cover to fix the shell and the battery module.

Furthermore, in an embodiment of the present invention, a plurality of heat dissipation grooves are arranged at intervals on the side wall of the shell, and the heat dissipation grooves are connected to the installation cavity. The heat energy generated by the battery cell is dissipated in the shell installation cavity, and the heat dissipation grooves connected to the outside world can dissipate the heat energy in the shell installation cavity to the outside world, thereby reducing the temperature in the shell installation cavity, which is beneficial to reducing the temperature of the polarity end of the battery cell.

Furthermore, in an embodiment of the present invention, the lower bracket and the upper bracket are each provided with a raised annular wall, the annular wall constitutes an interlocking cavity for accommodating the polar end of the battery cell, the heat dissipation port is located in the interlocking cavity, the side surface of the battery cell is in contact with the interlocking cavity or a gap is reserved between the side surface of the battery cell and the interlocking cavity, the gap is connected to the space where the polar end of the battery cell is located, and the gap is also connected to the housing installation cavity. The heat energy generated by the polar end of the battery cell is dissipated into the installation cavity through the gap reserved between the side surface of the battery cell and the interlocking cavity for heat dissipation, thereby avoiding the heat energy being concentrated at the polar end of the battery cell.

Furthermore, in an embodiment of the present invention, the bottom surface of the interlocking cavity has a raised heat sink, the heat sink surrounds the heat dissipation port, the polar end edge of the battery cell abuts against the heat sink, a ventilation groove is formed between the outer wall of the heat sink and the inner wall of the interlocking cavity, and the polar end edge of the battery cell is exposed in the ventilation groove. Except for the part of the polar end of the battery cell that contacts the conductor, the other part of the polar end of the battery cell, that is, the polar end edge of the battery cell does not contact the bottom surface of the interlocking cavity, and the polar end edge of the battery cell is exposed in the ventilation groove, which can make the heat energy generated by the polar end edge of the battery cell quickly dissipate in the ventilation groove for heat dissipation, so that the heat energy generated by the polar end edge of the battery cell is not easy to be concentrated together.

Beneficial Effects

The beneficial effect of the present invention is that the conductor of the battery pack of the present invention is attached to the polar end of the battery cell in a non-wrapped covering manner. Compared with the traditional welding method to connect the polar end of the battery cell, the welding layer reduces the blocking of the thermal energy generated by the polar end of the battery cell. Therefore, the present invention is conducive to improving the heat dissipation effect of the polar end of the battery cell. In addition, when the battery pack is used for power supply or storage, the thermal energy generated by the contact part between the polar end of the battery cell and the conductor, and the thermal energy generated by the edge of the polar end of the battery cell (the part not in contact with the conductor) can also be dissipated in the heat dissipation port, which is conducive to further improving the heat dissipation effect. .

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an explosion of a battery pack according to an embodiment of the present invention.

FIG. 2 is a three-dimensional schematic diagram of a lower bracket according to an embodiment of the present invention.

FIG. 3 is a schematic plan view of a lower bracket according to an embodiment of the present invention.

FIG. 4 is a three-dimensional schematic diagram of a lower connecting piece according to an embodiment of the present invention.

10. housing, 11. mounting cavity, 12. heat dissipation slot;

20. battery module, 21. lower bracket, 22. lower connecting piece, 23. lower cover, 24. upper bracket, 25. upper connecting piece, 26. upper cover;

211, a fitting cavity, 212, a heat dissipation port, 213, a heat dissipation platform, 214, a flow slot;

221, conductor, 222, heat dissipation hole;

231, avoidance slot;

30. Battery cells;

40. Snap-fit structural parts.

Embodiments of the present invention

In order to make the purpose and technical solution of the present invention clearly and completely described, and the advantages more clearly understood, the embodiments of the present invention are further described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described here are part of the embodiments of the present invention, not all of the embodiments, and are only used to explain the embodiments of the present invention, not to limit the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

In the description of the present invention, it should be noted that the terms "center", "middle", "upper", "lower", "left", "right", "inner", "outer", "top", "bottom", "side", "vertical", "horizontal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying 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 operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "one", "first", "second", "third", "fourth", "fifth", "sixth" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

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.

For the purpose of simplicity and illustration, the principles of the embodiments are mainly described by reference to examples. In the following description, many specific details are presented to provide a thorough understanding of the embodiments. However, it is obvious. For ordinary technicians in this field, these embodiments may not be limited to these specific details in practice. In some instances, well-known battery pack structures are not described in detail to avoid making these embodiments unnecessarily difficult to understand. In addition, all embodiments can be used in combination with each other.

Example

It should be explained first that the drawings in the specification are the contents of the specification. The structural shapes, connection relationships, matching relationships, and positional relationships that can be obtained without any doubt in the drawings in the specification should be understood as the contents of the specification.

A battery pack, as shown in FIG1 , includes a housing 10 and a battery module 20 disposed in a mounting cavity 11 of the housing 10. The battery module 20 includes at least two battery packs with opposite electrode directions, i.e., one battery pack has a positive electrode facing upwards and the other battery pack has a negative electrode facing upwards. The two battery packs are connected in series, and the battery packs include a plurality of battery cells 30 with the same electrode direction, i.e., the battery cells 30 in the battery pack all have positive electrodes facing upwards or negative electrodes facing upwards.

The plurality of battery cells 30 in the battery pack may be arranged in a side-by-side and/or stacked manner.

The battery module 20 includes a lower bracket 21 and a lower connecting plate 22 that fit together, and an upper bracket 24 and an upper connecting plate 25 that fit together.

As shown in Fig. 1 to Fig. 3, the lower bracket 21 and the upper bracket 24 are both provided with a heat dissipation port 212, and the lower connecting piece 22 and the upper connecting piece 25 are both provided with a conductor 221, and the conductor 221 is located in the heat dissipation port 212 and contacts the polarity end of the battery cell 30 to realize the electrical connection between the conductor 221 and the battery cell 30. The lower connecting piece 22 and the upper connecting piece 25 respectively connect the battery cells 30 with the same electrode direction in parallel.

The polarity end of the battery cell 30 refers to the electrode, and the conductor 221 can be a copper sheet or a nickel sheet.

The conductor 221 of the battery pack of the present invention is attached to the polar end of the battery cell 30 in a non-wrapped manner. Compared with the conventional method of connecting the polar end of the battery cell 30 by welding, the blocking of the welding layer on the thermal energy generated by the polar end of the battery cell 30 is reduced. Therefore, the present invention is conducive to improving the heat dissipation effect of the polar end of the battery cell 30. In addition, when the battery pack is used for power supply or power storage, the thermal energy generated by the contact part between the polar end of the battery cell 30 and the conductor 221, and the thermal energy generated by the edge of the polar end of the battery cell 30 (the part not in contact with the conductor 221) can also be dissipated in the heat dissipation port 212, which is conducive to further improving the heat dissipation effect.

As shown in Figure 4, the upper connecting piece 25 and the lower connecting piece 22 are respectively provided with multiple conductors 221. The upper connecting piece 25 is a conductive metal part or the upper connecting piece 25 is provided with a circuit for connecting the conductors 221. The lower connecting piece 22 is a conductive metal part or the lower connecting piece 22 is provided with a circuit for connecting the conductors 221. The upper connecting piece 25 and the lower connecting piece 22 are used to electrically connect the multiple conductors 221 of the upper connecting piece 25.

As shown in Figures 1 and 4, the conductor 221 of the lower connecting sheet 22 protrudes from the plane of the lower connecting sheet 22, and the conductor 221 of the upper connecting sheet 25 protrudes from the plane of the upper connecting sheet 25. The conductor 221 of the upper connecting sheet 25 extends downward and bends, and contacts the polarity end of the battery cell 30 with a bent structure. The conductor 221 of the lower connecting sheet 22 extends upward and bends, and contacts the polarity end of the battery cell 30 with a bent structure.

The lower connecting piece 22 and the upper connecting piece 25 are provided with heat dissipation holes 222 at positions corresponding to the conductors 221 thereon, and the heat dissipation holes 222 are communicated with the mounting cavity 11. Specifically, the upper connecting piece 25 and the lower connecting piece 22 are provided with heat dissipation holes 222 at positions corresponding to the conductors 221 thereon, the lower connecting piece 22 corresponds to the heat dissipation holes 222 at the lower bracket 21, and the upper connecting piece 25 corresponds to the heat dissipation holes 222 at the upper bracket 24. The heat dissipation holes 222 at the upper bracket 24 are not shown in the figure, but the structure of the heat dissipation holes 222 at the upper bracket 24 is the same as that of the heat dissipation holes 222 at the lower bracket 21.

The heat energy generated by the battery cell 30 can be directly transferred to the conductor 221, and the air medium in the heat dissipation hole 222 can conduct the heat dissipation of the conductor 221, and then dissipate it in the heat dissipation hole 222, and then dissipate it to the installation cavity 11 of the shell 10 through the heat dissipation hole 222, which greatly diffuses the heat energy on the polarity end of the battery cell 30, making it difficult for the heat energy to be concentrated on the polarity end of the battery cell 30, affecting the stable use of the battery cell 30.

As shown in FIG3 and FIG4 , the conductor 221 is smaller than the heat dissipation port 212, and a heat dissipation gap is left between the conductor 221 and the side wall of the heat dissipation port 212, and the heat dissipation gap is connected to the heat dissipation hole 222, and the heat dissipation port 212 is connected to the installation cavity 11 through the heat dissipation hole 222. Therefore, the heat energy generated by the polarity end of the battery cell 30 can be directly dissipated into the heat dissipation port 212 through the heat dissipation gap for heat dissipation, so that the heat energy is not easily concentrated on the polarity end of the battery cell 30.

As shown in FIG. 1 , the battery module 20 further includes an upper cover plate 26 and a lower cover plate 23 . The upper cover plate 26 is fixedly connected to the upper bracket 24 , and the lower cover plate 23 is fixedly connected to the lower bracket 21 .

The upper cover plate 26 is attached to the upper connecting piece 25 , and presses and fixes the upper connecting piece 25 onto the upper bracket 24 .

The lower cover plate 23 is attached to the lower connecting piece 22 , and presses and fixes the lower connecting piece 22 onto the lower bracket 21 .

The upper bracket 24 and the lower bracket 21 are non-conductive plate structures, and the upper bracket 24 and the lower bracket 21 are provided with threaded holes. The upper cover plate 26 is connected to the threaded holes of the upper bracket 24 by bolts passing through the through holes of the upper connecting plate 25 to achieve a fixed connection. The lower cover plate 23 is connected to the threaded holes of the lower bracket 21 by bolts passing through the through holes of the lower connecting plate 22 to achieve a fixed connection. The upper connecting plate 25 and the lower connecting plate 22 do not contact the bolts to prevent the bolts from being charged.

As shown in FIG. 1 , the upper cover plate 26 and the lower cover plate 23 are each provided with an escape groove 231 , and the escape groove 231 of the upper cover plate 26 corresponds to the heat dissipation hole 222 of the upper bracket 24 , and the heat dissipation hole 222 of the upper bracket 24 is connected with the installation cavity 11 of the shell 10 through the escape groove 231 of the upper cover plate 26 .

The avoidance groove 231 of the lower cover plate 23 corresponds to the heat dissipation hole 222 of the lower bracket 21, and the heat dissipation hole 222 of the lower bracket 21 is connected with the installation cavity 11 of the shell 10 through the avoidance groove 231 of the lower cover plate 23. In this way, the heat energy generated by the polarity end of the battery cell 30 can be dissipated through the heat dissipation port 212 and the heat dissipation hole 222 to the installation cavity 11 of the shell 10 for heat dissipation treatment.

As shown in Figure 1, the lower cover plate 23 is fixed to the bottom of the mounting cavity 11 of the shell 10, and a non-conductor 221 snap-fit structure 40 is provided between the upper cover plate 26 and the shell 10. One end of the snap-fit structure 40 is snap-fitted to the shell 10, and the other end of the snap-fit structure 40 is snap-fitted to the upper cover plate 26 to fix the shell 10 and the battery module 20.

As shown in FIG1 , a plurality of heat dissipation slots 12 are arranged at intervals on the side wall of the housing 10, and the heat dissipation slots 12 are connected to the mounting cavity 11. The heat energy generated by the battery cell 30 is dissipated in the mounting cavity 11 of the housing 10, and the heat dissipation slots 12 can dissipate the heat energy in the mounting cavity 11 of the housing 10.

As shown in Figures 2 and 3, the lower bracket 21 and the upper bracket 24 are each provided with a raised annular wall, which constitutes an interlocking cavity 211 for accommodating the polar end of the battery cell 30, and the heat dissipation port 212 is located in the interlocking cavity 211. The side surface of the battery cell 30 is in contact with the interlocking cavity 211 or a gap is reserved between the side surface of the battery cell 30 and the interlocking cavity 211, and the gap is connected to the space where the polar end of the battery cell 30 is located. The gap is also connected to the mounting cavity 11 of the shell 10, so that the heat energy generated by the polar end of the battery cell 30 can be dissipated in the mounting cavity 11 through the gap reserved between the side surface of the battery cell 30 and the interlocking cavity 211 for heat dissipation, thereby avoiding the concentration of heat energy at the polar end of the battery cell 30.

As shown in Figures 2 and 3, the inner bottom surface of the interlocking cavity 211 has a raised heat dissipation platform 213, which surrounds the heat dissipation port 212. The polar end edges of the battery cell 30 abut against the heat dissipation platform 213. A ventilation groove is formed between the outer wall of the heat dissipation platform 213 and the inner wall of the interlocking cavity 211, and the polar end edges of the battery cell 30 are exposed in the ventilation groove.

Except for the part of the polar end of the battery cell 30 that contacts the conductor 221, the other part of the polar end of the battery cell 30, that is, the edge of the polar end of the battery cell 30, does not contact the bottom surface of the inner cavity 211. The edge of the polar end of the battery cell 30 is exposed in the ventilation groove, which can enable the heat energy generated by the edge of the polar end of the battery cell 30 to be quickly dissipated in the ventilation groove for heat dissipation. Therefore, the heat energy generated by the edge of the polar end of the battery cell 30 is not easy to be concentrated together.

As shown in Fig. 2 and Fig. 3, the side of the battery cell 30 and the interlocking cavity 211 have a gap and are connected to the ventilation groove. There is a gap between the battery cells 30, and this gap is located in the installation cavity 11 of the shell 10. The ventilation groove can dissipate the heat energy generated by the polarity end of the battery cell 30 in the installation cavity 11 through the gap, so as to avoid the heat energy generated by the polarity end of the battery cell 30 being too concentrated and difficult to dissipate.

As shown in FIG. 2 and FIG. 3 , the heat sink 213 has a missing part, which is divided into a flow slot 214, and the ventilation slot is connected to the heat dissipation port 212 through the flow slot 214. The ventilation slot is connected to the heat dissipation port 212, so that the heat energy generated by the polarity end of the battery cell 30 and the edge of the polarity end of the battery cell 30 can flow through the ventilation slot and the heat dissipation port 212 (increasing the heat dissipation space, and not easily causing the heat energy to concentrate, which is easy to affect the stable use of the battery cell 30), and the heat dissipation port 212 is used to circulate in the installation cavity 11 of the shell 10 for heat dissipation, which is conducive to improving the heat dissipation of the polarity end of the battery cell 30 and the edge of the polarity end of the battery cell 30.

Although the above describes the illustrative specific embodiments of the present invention so that those skilled in the art can understand the present invention, the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, all inventions and creations using the concepts of the present invention are protected.

Claims (8)

A battery pack, characterized in that it comprises a shell and a battery module arranged in a mounting cavity of the shell, wherein at least two battery packs with electrodes in opposite directions are arranged in the battery module, two of the battery packs are connected in series, and the battery pack comprises a plurality of cells with electrodes in the same direction; The battery module comprises a lower bracket and a lower connecting plate that fit together, and an upper bracket and an upper connecting plate that fit together; The lower bracket is located between the lower connecting plate and the battery core, and the upper bracket is located between the upper connecting plate and the battery core; The lower bracket and the upper bracket are both provided with heat dissipation openings, the lower connecting sheet and the upper connecting sheet are both provided with conductors, the conductors are located in the heat dissipation openings and contact the polarity ends of the battery cells, and the lower connecting sheet and the upper connecting sheet respectively connect the battery cells with the same electrode direction in parallel; The lower bracket and the upper bracket are each provided with a raised annular wall, the annular wall forms an embedding cavity for accommodating the polarity end of the battery cell, the heat dissipation port is located in the embedding cavity, the side surface of the battery cell is in contact with the embedding cavity or a gap is left between the side surface of the battery cell and the embedding cavity, the gap is connected to the space where the polarity end of the battery cell is located, and the gap is also connected to the housing installation cavity; The bottom surface of the embedded cavity has a raised heat dissipation platform, the heat dissipation platform surrounds the heat dissipation port, the polar end edge of the battery cell abuts against the heat dissipation platform, a ventilation groove is formed between the outer wall of the heat dissipation platform and the inner wall of the embedded cavity, and the polar end edge of the battery cell is exposed in the ventilation groove; The side of the battery cell and the fitting cavity retain a gap that is connected to the ventilation groove; The heat dissipation platform has a missing part, which is a flow slot, and the ventilation slot is connected with the heat dissipation port through the flow slot. According to the battery pack according to claim 1, it is characterized in that the upper connecting piece and the lower connecting piece are respectively provided with a plurality of conductors, the upper connecting piece is a conductive metal piece or the upper connecting piece is provided with a circuit for connecting the conductors, the lower connecting piece is a conductive metal piece or the lower connecting piece is provided with a circuit for connecting the conductors, and the upper connecting piece and the lower connecting piece are used to electrically connect the plurality of conductors of the upper connecting piece. The battery pack according to claim 1 is characterized in that the conductor of the lower connecting sheet protrudes from the plane of the lower connecting sheet, the conductor of the upper connecting sheet protrudes from the plane of the upper connecting sheet, heat dissipation holes are provided at the positions of the conductors of both the upper connecting sheet and the lower connecting sheet, the lower connecting sheet corresponds to the heat dissipation holes at the lower bracket, the upper connecting sheet corresponds to the heat dissipation holes at the upper bracket, and the heat dissipation holes are communicated with the mounting cavity. The battery pack according to claim 3 is characterized in that the conductor is smaller than the heat dissipation port, a heat dissipation gap is left between the conductor and the side wall of the heat dissipation port, the heat dissipation gap is connected to the heat dissipation hole, and the heat dissipation port is connected to the mounting cavity through the heat dissipation hole. The battery pack according to claim 3, characterized in that the battery module further comprises an upper cover plate and a lower cover plate, the upper cover plate is fixedly connected to the upper bracket, and the lower cover plate is fixedly connected to the lower bracket; The upper cover plate is attached to the upper connecting piece, and the upper connecting piece is pressed and fixed on the upper bracket; The lower cover plate is attached to the lower connecting piece, and the lower connecting piece is pressed and fixed on the lower bracket. The battery pack according to claim 5, characterized in that the upper cover plate and the lower cover plate are each provided with an avoidance groove, the upper cover plate avoidance groove corresponds to the upper bracket heat dissipation hole, and the upper bracket heat dissipation hole is connected with the shell mounting cavity through the upper cover plate avoidance groove; The lower cover plate avoidance groove corresponds to the lower bracket heat dissipation hole, and the lower bracket heat dissipation hole is connected with the shell installation cavity through the lower cover plate avoidance groove. According to the battery pack of claim 6, it is characterized in that the lower cover is fixed to the bottom of the shell mounting cavity, and a non-conductive snap-fit structure is provided between the upper cover and the shell, one end of the snap-fit structure is snap-fitted to the shell, and the other end of the snap-fit structure is snap-fitted to the upper cover to fix the shell and the battery module. The battery pack according to claim 1 is characterized in that a plurality of heat dissipation grooves are arranged at intervals on the side wall of the shell, and the heat dissipation grooves are connected to the mounting cavity.