Battery pack and energy storage system

Abstract

A battery pack and an energy storage system, relating to the technical field of energy storage. The battery pack comprises: a battery case, a plurality of battery modules, a first transition connecting sheet, a second transition connecting sheet, and a turn-on connecting sheet. The plurality of battery modules are located in the battery case. The plurality of battery modules include a first battery module and a second battery module; the first battery module is provided with a first output electrode base and a first output electrode connecting sheet; and the second battery module is provided with a second output electrode base and a second output electrode connecting sheet. The first transition connecting sheet is located on the first output electrode base and is connected to the first output electrode connecting sheet, and has a resistance less than that of the first output electrode connecting sheet. The second transition connecting sheet is located on the second output electrode base and is connected to the second output electrode connecting sheet, and has a resistance less than that of the second output electrode connecting sheet. The turn-on connecting sheet has a first end connected to the first transition connecting sheet, and a second end connected to the second transition connecting sheet.

Description

Battery pack and energy storage system

[0001] Cross-reference to related applications

[0002] The present disclosure claims priority to Chinese Patent Application No. 202422004051.3, filed on August 16, 2024, the disclosure of which is incorporated herein in its entirety as part of the present disclosure. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of energy storage, and in particular, to a battery pack and energy storage system. BACKGROUND

[0004] A plurality of battery modules are usually included in a battery pack, and electrical connection is usually required between the plurality of battery modules. As the market demand for energy density and energy size of the battery pack continues to rise, the number of battery modules in the battery pack continues to increase. To meet the requirement of high energy density, the current between the battery modules gradually increases, which causes the existing battery module structure to be unable to meet the overcurrent requirement, and even the electrical connection structure is fused and the electrical connection fails.

[0005] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present disclosure, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0006] The purpose of the present disclosure is to provide a battery pack and energy storage system.

[0007] According to one aspect of the present disclosure, a battery pack is provided, comprising:

[0008] a battery box body, the battery box body being formed with a battery compartment;

[0009] a plurality of battery modules, the plurality of battery modules being located in the battery compartment; each of the battery modules comprising a plurality of battery cells arranged along a first direction and end plates clamped at both ends of the plurality of battery cells; the plurality of battery modules at least comprising a first battery module and a second battery module arranged adjacent to each other along the first direction, a first output pole base insulated being provided on a first end plate adjacent to the second battery module in the first battery module, and a first output pole connecting piece being provided on the battery cell adjacent to the first end plate; a second output pole base insulated being provided on a second end plate adjacent to the first battery module in the second battery module, and a second output pole connecting piece being provided on the battery cell adjacent to the second end plate;

[0010] a first transition connecting piece and a second transition connecting piece, the first transition connecting piece is located on the first output pole base and connected with the first output pole connecting piece, and the resistance of the first transition connecting piece is less than the resistance of the first output pole connecting piece; the second transition connecting piece is located on the second output pole base and connected with the second output pole connecting piece, and the resistance of the second transition connecting piece is less than the resistance of the second output pole connecting piece;

[0011] a conducting connecting piece, the conducting connecting piece comprises a first end and a second end which are oppositely arranged along the first direction, the first end is connected with the first transition connecting piece, and the second end is connected with the second transition connecting piece.

[0012] The battery pack provided by the present disclosure is provided with a first transition connecting piece on the first output pole base, a second transition connecting piece on the second output pole base, and a conducting connecting piece, the first end of the conducting connecting piece is connected with the first output pole connecting piece through the first transition connecting piece, and the second end of the conducting connecting piece is connected with the second output pole connecting piece through the second transition connecting piece; since the resistance of the first transition connecting piece is less than the resistance of the first output pole connecting piece, and the resistance of the second transition connecting piece is less than the resistance of the second output pole connecting piece, the overcurrent capacity of the corresponding electrical connecting pieces on the first output pole base and the second output pole base is improved, and the problem that the output pole connecting piece is prone to serious heating and melting, resulting in electrical connection failure, is avoided.

[0013] According to another aspect of the present disclosure, a kind of energy storage system is provided, which comprises the above-mentioned battery pack.

[0014] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0015] The drawings herein are incorporated into the specification and form part of the specification, show embodiments consistent with the present disclosure, and together with the specification, serve to explain the principles of the present disclosure. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained according to these drawings without creative labor for those skilled in the art.

[0016] Fig. 1 is a schematic diagram of an energy storage system according to an embodiment of the present disclosure.

[0017] Fig. 2 is a schematic diagram of a battery pack according to an embodiment of the present disclosure.

[0018] Fig. 3 is an exploded schematic diagram of a battery pack according to an embodiment of the present disclosure.

[0019] Fig. 4 is a schematic diagram of a battery module according to an embodiment of the present disclosure.

[0020] Fig. 5 is a schematic diagram of electrical connection between a first battery module and a second battery module according to an embodiment of the present disclosure.

[0021] Fig. 6 is an enlarged view of a portion of Fig. 5.

[0022] Fig. 7 is a schematic diagram of electrical connection between a first battery module and a second battery module after removing a base cover according to an embodiment of the present disclosure.

[0023] Fig. 8 is an enlarged view of a portion of Fig. 7.

[0024] Fig. 9 is an exploded view of Fig. 8.

[0025] Fig. 10 is a schematic diagram of an electrical connection structure between a first battery module and a second battery module according to an embodiment of the present disclosure.

[0026] Fig. 11 is a schematic diagram of a conductive connecting piece according to an embodiment of the present disclosure.

[0027] Fig. 12 is a schematic diagram of a conductive connecting piece according to another embodiment of the present disclosure.

[0028] Fig. 13 is a schematic diagram of a conductive connecting piece according to yet another embodiment of the present disclosure.

[0029] Fig. 14 is a schematic diagram of a first transition connecting piece and a second transition connecting piece according to an embodiment of the present disclosure.

[0030] Fig. 15 is a schematic diagram of a first transition connecting piece and a second transition connecting piece according to another embodiment of the present disclosure.

[0031] Explanation of reference signs: 10, energy storage device; 20, power grid; 30, first electric energy conversion device; 40, second electric energy conversion device; 100, battery pack; 110, battery box; 111, lower box; 112, box cover; 120, battery module; 121, first battery module; 1211, first battery cell; 1212, first end plate; 1213, first output pole base; 1214, first base cover plate; 1215, first output pole connecting piece; 1216, first cell connecting piece; 1217, first cable tie; 1218, first insulation plate; 122, second battery module; 1221, second battery cell; 1222, second end plate; 1223, second output pole base; 1224, second base cover plate; 1225, second output pole connecting piece; 1226, second cell connecting piece; 1227, second cable tie; 1228, second insulation plate; 123, first transition connecting piece; 1231, first end; 1232, second end; 1233, first connecting part; 1234, second connecting part; 1235, first bending part; 1236, first avoiding gap; 1237, first conductive layer; 1238, second conductive layer; 124, second transition connecting piece; 1241, first end; 1242, second end; 1243, third connecting part; 1244, fourth connecting part; 1245, second bending part; 1246, second avoiding gap; 1247, third conductive layer; 1248, fourth conductive layer; 125, through connecting piece; 1251, first end; 1252, second end; 1253, fifth connecting part; 1254, sixth connecting part; 1255, third bending part; 1256, insulation layer; 126, screw rod. DETAILED DESCRIPTION

[0032] Example embodiments now will be described more fully hereinafter with reference to the accompanying drawings; however, the example embodiments can be implemented in many different forms and should not be construed as limited to the implementations set forth herein; rather, these implementations are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the example embodiments to those skilled in the art. Like reference numerals refer to like elements throughout the figures, and thus description of the same will be simplified or omitted.

[0033] Since the energy required by people has strong time and space, in order to reasonably use energy and improve utilization, it is necessary to store one energy form into the same energy form or convert into another energy form through a medium or device, and then release it in a specific energy form based on future application.

[0034] At present, green energy mainly includes light energy, wind energy, etc., and light energy and wind energy have the problems of strong intermittency and large volatility, which will cause the voltage instability of green power grid (not enough electricity at peak electricity consumption, and too much electricity at low electricity consumption), and the unstable voltage will cause damage to electricity, so it may cause the problem of "abandoning wind and light" due to insufficient electricity demand or insufficient grid accommodation capacity.

[0035] To solve the problem of insufficient electricity demand or insufficient grid accommodation capacity, it is necessary to rely on energy storage devices. That is, through energy storage devices, electric energy is converted into other forms of energy by physical or chemical means for storage, and when needed, the energy stored in the energy storage device is converted into electric energy for release. In simple terms, the energy storage device is similar to a large "power bank", which stores electric energy when light energy and wind energy are sufficient, and releases the stored electric energy when needed.

[0036] The current energy storage (i.e. energy storage) application scenarios are relatively wide, including power generation side energy storage, power grid side energy storage, renewable energy grid-connected energy storage, and user side energy storage, etc. The corresponding types of energy storage devices include:

[0037] (1) Large-scale energy storage power stations applied in wind power, photovoltaic power station and other power generation side energy storage scenarios, which can assist renewable energy power generation to meet grid connection requirements and improve renewable energy utilization rate; energy storage power station as a high-quality active / reactive power regulation power source in the power supply side, realizes the load matching of electric energy in time and space, enhances the renewable energy consumption capacity, reduces the instantaneous power change, reduces the impact on the power grid, improves the new energy power generation consumption problem, and has great significance in power grid system backup, relieving peak load power supply pressure and peak regulation;

[0038] (2) Large-scale energy storage containers applied in power grid side energy storage scenarios, the main functions of which are peak regulation, frequency regulation, and relieving power grid congestion peak regulation, which can realize the peak clipping and valley filling of electricity load, that is, charging the energy storage battery when the electricity load is low, and releasing the stored electric quantity during the peak period of electricity load, so as to realize the balance between power production and consumption, such as energy storage power station system;

[0039] (3) Small and medium-sized energy storage cabinets applied in industrial and commercial energy storage scenarios (banks, shopping malls, etc.) on the user side and small household energy storage boxes applied in household energy storage scenarios on the user side, the functions of which mainly include power self-generation and self-use, peak load shifting, capacity cost management, and improvement of power supply reliability. According to different application scenarios, the power consumption side energy storage can be divided into industrial and commercial energy storage cabinets, household energy storage devices, energy storage charging piles, etc., which are generally used in combination with distributed photovoltaic power. Since there is a large price difference in electricity bills at peak and valley positions according to power consumption demand, after users have energy storage devices, in order to reduce costs, the energy storage devices (energy storage cabinets / boxes) are usually charged at low electricity prices. At the peak of electricity prices, the electricity in the energy storage devices is discharged for use, in order to achieve the purpose of saving electricity bills. In addition, communication base stations, data centers, and other fields need to be equipped with energy storage for backup power. In addition, in remote areas and areas with high incidence of natural disasters such as earthquakes and hurricanes, the existence of household energy storage devices is equivalent to the user providing backup power for himself and the power grid, eliminating the inconvenience caused by frequent power outages due to disasters or other reasons.

[0040] FIG. 1 is a schematic diagram of an energy storage system according to an embodiment of the present disclosure, and the embodiment of the present disclosure takes the power generation / distribution side shared energy storage scenario as an example for illustration. The energy storage system of the present disclosure is not limited to the power generation / distribution side energy storage scenario, but can also be applied to industrial and commercial side or user side scenarios, etc.

[0041] As shown in FIG. 1, the energy storage system includes an energy storage device 10, a power grid 20, a first electric energy conversion device 30, and a second electric energy conversion device 40. In the case of power generation, the first electric energy conversion device 30 and the second electric energy conversion device 40 are used to convert other forms of energy into electric energy, which is connected to the power grid 20 for use by the power consumption side of the distribution network. When the power consumption load is low, the first electric energy conversion device 30 and the second electric energy conversion device 40 generate excess electricity, which is stored in the energy storage device 10, reducing the rate of abandoned wind and light, and improving the problem of new energy power generation consumption. When the power consumption load is high, the power grid issues an instruction to transmit the electricity stored in the energy storage device 10 in cooperation with the power grid 20 in a grid-connected mode to supply the power consumption side, providing peak shaving, frequency modulation, backup, and other services for the operation of the power grid 20, fully utilizing the peak shaving function of the power grid 20, promoting the peak shaving of the power grid 20, and relieving the power supply pressure of the power grid 20.

[0042] Among them, the first electric energy conversion device 30 can be a solar energy conversion device, and the second electric energy conversion device 40 can be a wind energy conversion device. Of course, the electric energy conversion device can also be a device that converts at least one of thermal energy, tidal energy, biomass energy, and mechanical energy into electric energy.

[0043] In combination with the above energy storage by physical or electrochemical means, taking electrochemical energy storage as an example, the energy storage device 10 includes at least one chemical battery, which uses chemical elements in the chemical battery as an energy storage medium to achieve the charging and discharging process through chemical reactions or changes of the energy storage medium. In simple terms, the electrical energy generated by light energy or wind energy is stored in at least one set of chemical batteries through chemical reactions or changes of the energy storage medium. When the use of external electrical energy reaches a peak, the electrical energy stored in the at least one set of chemical batteries is released and used through chemical reactions or changes of the energy storage medium, or transferred to places where electrical energy is in short supply for use.

[0044] The energy storage device 10 can be a battery pack including battery monomers, an energy storage box, an energy storage cabinet, etc. The battery monomers can be lithium ion secondary batteries, lithium-sulfur batteries, sodium lithium ion batteries, sodium ion batteries, magnesium ion batteries, etc., and the battery monomers can be in the form of a cylinder, a flat body, a cuboid, etc., which are not limited by the embodiments of the present disclosure.

[0045] As shown in FIGS. 2 and 3, taking the energy storage device 10 as an example, the battery pack 100 includes a battery box body 110 and a plurality of battery modules 120. The battery box body 110 includes a lower box body 111 and a box cover 112, and the box cover 112 is fixedly / detachably connected with the lower box body 111 to enclose a battery compartment. The plurality of battery modules 120 are located in the battery compartment.

[0046] The battery modules 120 accommodated in the battery compartment of the battery box body 110 can be at least one, such as one, two, four, five, six, seven, eight or more, and the more the number of battery modules 120, the higher the capacity of the battery pack 100, thereby more easily meeting the market demand. For example, as shown in FIG. 4, the battery compartment of the battery box body 110 accommodates two rows along the length direction of the battery box body 110 and four columns along the width direction of the battery box body 110, totaling eight battery modules 120.

[0047] The battery module 120 can include a pair of end plates arranged opposite to each other along the direction of grouping of the battery cells, and a plurality of battery cells located between the pair of end plates. The plurality of battery cells and the pair of end plates can be fixed by a binding tool such as a cable tie. The plurality of battery cells are arranged along the length direction of the battery box body, and the plurality of battery cells are connected by the cell connecting piece to realize the series / parallel electrical connection between the plurality of battery cells. For example, as shown in FIGS. 5 and 6, the first battery module 121 includes a pair of first end plates 1212 arranged opposite to each other, and a plurality of first battery cells 1211 located between the pair of first end plates 1212. The plurality of first battery cells 1211 and the pair of first end plates 1212 are fixed by a first cable tie 1217. The plurality of first battery cells 1211 are arranged along the length direction of the battery box body 110, and the plurality of first battery cells 1211 are connected by a first cell connecting piece 1216 to realize the series / parallel electrical connection between the plurality of first battery cells 1211. The second battery module 122 includes a pair of second end plates 1222 arranged opposite to each other, and a plurality of second battery cells 1221 located between the pair of second end plates 1222. The plurality of second battery cells 1221 and the pair of second end plates 1222 are fixed by a second cable tie 1227. The plurality of second battery cells 1221 are arranged along the length direction of the battery box body 110, and the plurality of second battery cells 1221 are connected by a second cell connecting piece 1226 to realize the series / parallel electrical connection between the plurality of second battery cells 1221.

[0048] The plurality of battery cells are connected in series. In this case, each cell connecting piece is connected to electrode terminals of different polarity of two battery cells. Alternatively, two battery cells are connected in parallel to form a group, and the groups are connected in series. In this case, each cell connecting piece is connected to electrode terminals of the same polarity of two battery cells, and then connected to electrode terminals of opposite polarity of other two battery cells.

[0049] The outer wall of each battery cell can be covered with an insulating film to avoid safety hazards caused by leakage of the battery cell. As shown in FIGS. 5 and 6, the first battery module 121 includes a first insulating plate 1218 located between the first end plate 1212 and the first battery cell 1211 adjacent to the first end plate 1212. The first insulating plate 1218 can prevent the first end plate 1212 from piercing the insulating film of the first battery cell 1211 due to burrs or protruding structures on the first end plate 1212, and can prevent the first end plate 1212 from being electrified due to leakage of the first battery cell 1211. In addition, as the first battery cell 1211 is electrified and the first end plate 1212 is not electrified, the first insulating plate 1218 can increase the creepage distance between the first battery cell 1211 and the first end plate 1212, and can ensure that the first end plate 1212 is not electrified, thereby avoiding electrification of the battery box body 110 and improving the safety of the operator.

[0050] The second battery module 122 includes a second insulating plate 1228 between the second end plate 1222 and the second battery cell 1221 adjacent to the second end plate 1222, so as to avoid that the burr or protruding structure on the second end plate 1222 pierces the insulating film on the second battery cell 1221, and to avoid that the second battery cell 1221 causes the second end plate 1222 to be electrified after leakage. At the same time, since the second battery cell 1221 is electrified and the second end plate 1222 is not electrified, the second insulating plate 1228 can increase the creepage distance between the second battery cell 1221 and the second end plate 1222, so as to ensure that the second end plate 1222 is not electrified, thereby avoiding that the battery box 110 is electrified, and improving the safety of the operation of the staff.

[0051] In the related art, the end plate at both ends of the battery module is usually an aluminum casting end plate, and the end plate is provided with an output pole base, and the output pole connecting piece is placed on the output pole base, and the copper bar is connected to the output pole connecting piece. The output pole base is insulated from the output pole connecting piece and the end plate to prevent short circuit caused by contact between them. Generally, from the perspective of material cost, battery pack weight and space utilization, the width of the output pole base is small. When the output pole connecting piece needs to be placed on the output pole base, the output pole connecting piece needs to be set to a shape with different widths, that is, the width of the output pole connecting piece near the output pole base is reduced to be placed on the output pole base.

[0052] However, in the battery module, when the battery cells are electrically connected in parallel or in series-parallel, the current of the output pole connecting piece at the output end will combine the parallel currents into one, and the current at the output end will be larger than that when only the series connection is used. Therefore, when the width of the output pole connecting piece is narrowed at the output end, the overcurrent channel is also narrowed, which cannot meet the overcurrent requirement of the battery module connected in parallel or in series-parallel, and is prone to cause the output pole connecting piece to heat sharply, even to be fused, and cause the electrical connection to fail.

[0053] To solve the above technical problems, the battery pack provided by the embodiments of the present disclosure includes a battery box 110, a plurality of battery modules 120, a first transition connecting piece 123, a second transition connecting piece 124 and a conduction connecting piece 125, as shown in FIGS. 2-10. Each battery module 120 includes a plurality of battery cells arranged along a first direction X and end plates clamped at both ends of the plurality of battery cells; the plurality of battery modules 120 at least includes a first battery module 121 and a second battery module 122 arranged adjacent to each other along the first direction X; wherein the first direction X is the length direction of the battery pack 100. In the following, the present disclosure takes the first battery module 121 and the second battery module 122 as examples to discuss the electrical connection structure between the adjacent battery modules 120 in detail.

[0054] The first end plate 1212 adjacent to the second battery module 122 is provided with an insulating first output pole base 1213, and the first battery monomer 1211 adjacent to the first end plate 1212 is provided with a first output pole connecting piece 1215.

[0055] The first transition connecting piece 123 is located on the first output pole base 1213 and connected with the first output pole connecting piece 1215, and the resistance of the first transition connecting piece 123 is smaller than that of the first output pole connecting piece 1215; the second transition connecting piece 124 is located on the second output pole base 1223 and connected with the second output pole connecting piece 1225, and the resistance of the second transition connecting piece 124 is smaller than that of the second output pole connecting piece 1225; the conducting connecting piece 125 includes a first end 1251 and a second end 1252 oppositely arranged along the first direction X, the first end 1251 is connected with the first transition connecting piece 123, and the second end 1252 is connected with the second transition connecting piece 124.

[0056] The battery pack 100 provided by the present disclosure is provided with the first transition connecting piece 123 on the first output pole base 1213, the second transition connecting piece 124 on the second output pole base 1223, the first end 1251 of the conducting connecting piece 125 connected with the first output pole connecting piece 1215 through the first transition connecting piece 123, and the second end 1252 of the conducting connecting piece 125 connected with the second output pole connecting piece 1225 through the second transition connecting piece 124; since the resistance of the first transition connecting piece 123 is smaller than that of the first output pole connecting piece 1215, and the resistance of the second transition connecting piece 124 is smaller than that of the second output pole connecting piece 1225, the overcurrent capacity of the corresponding electrical connecting piece on the first output pole base 1213 and the second output pole base 1223 is improved, and the problem that the first output pole connecting piece 1215 is located on the first output pole base 1213 and the second output pole connecting piece 1225 is located on the second output pole base 1223 to narrow the overcurrent capacity relatively low, which causes the output pole connecting piece to easily heat seriously and fuse, resulting in electrical connection failure, is avoided.

[0057] Specifically, the first output pole base 1213 is provided with a first limiting groove, and the first transition connecting piece 123 is located in the first limiting groove; in the third direction Y, the width of at least part of the first output pole connecting piece 1215 is greater than the width of the first limiting groove, that is, the width of the first output pole base 1213 is less than the width of the first output pole connecting piece 1215; when the first output pole connecting piece 1215 needs to be placed on the first output pole base 1213, the first output pole connecting piece 1215 needs to be set to a shape with different widths, that is, the width of one end of the first output pole connecting piece 1215 close to the first output pole base 1213 is reduced to be narrow to be placed on the first output pole base 1213; by setting the first transition connecting piece 123, it is connected with the conduction connecting piece 125 on the first output pole base 1213 instead of the first output pole connecting piece 1215. Wherein, the third direction Y is the width direction of the battery pack 100.

[0058] Wherein, the second output pole base 1223 is provided with a second limiting groove, and the second transition connecting piece 124 is located in the second limiting groove; in the third direction Y, the width of at least part of the second output pole connecting piece 1225 is greater than the width of the second limiting groove, that is, the width of the second output pole base 1223 is less than the width of the second output pole connecting piece 1225; when the second output pole connecting piece 1225 needs to be placed on the second output pole base 1223, the second output pole connecting piece 1225 needs to be set to a shape with different widths, that is, the width of one end of the second output pole connecting piece 1225 close to the second output pole base 1223 is reduced to be narrow to be placed on the second output pole base 1223; by setting the second transition connecting piece 124, it is connected with the conduction connecting piece 125 on the second output pole base 1223 instead of the second output pole connecting piece 1225.

[0059] Specifically, the first output pole connecting piece 1215 and the first output pole base 1213 are arranged at intervals in the first direction X, the first transition connecting piece 123 includes oppositely arranged first end 1231 and second end 1232, and the first end 1231 of the first transition connecting piece 123 extends out of the first output pole base 1213 and is connected with the first output pole connecting piece 1215.

[0060] When the first limiting groove formed by the first output pole base 1213 is of an equal-width structure, the first end 1231 of the first transition connecting piece 123 extends out of the first output pole base 1213 to be connected with the first output pole connecting piece 1215, so that the first output pole connecting piece 1215 is prevented from being narrowed at one end close to the first output pole base 1213, and the first output pole connecting piece 1215 has sufficient width, thereby ensuring the overcurrent capacity of the first output pole connecting piece 1215 and preventing the first output pole connecting piece 1215 from being heated or even fused. When the first limiting groove formed by the first output pole base 1213 is of a non-equal-width structure, for example, the width of the first output pole base 1213 close to the first output pole connecting piece 1215 is relatively large, the first output pole connecting piece 1215 can also be connected with the first transition connecting piece 123 on the first output pole base 1213 with the relatively large width, and in this case, the first end 1231 of the first transition connecting piece 123 does not need to extend out of the first output pole base 1213, and the width of the first output pole connecting piece 1215 is not affected, so that the overcurrent capacity of the first output pole connecting piece 1215 is not reduced.

[0061] Specifically, the second output pole connecting piece 1225 is arranged at a position spaced apart from the second output pole base 1223 in the first direction X, and the second transition connecting piece 124 includes a first end 1241 and a second end 1242 arranged opposite to each other, and the first end 1241 of the second transition connecting piece 124 extends out of the second output pole base 1223 to be connected with the second output pole connecting piece 1225.

[0062] When the first limiting groove formed by the second output pole base 1223 is of an equal-width structure, the first end 1241 of the second transition connecting piece 124 extends out of the second output pole base 1223 to be connected with the second output pole connecting piece 1225, so that the second output pole connecting piece 1225 is prevented from being narrowed at one end close to the second output pole base 1223, and the second output pole connecting piece 1225 has sufficient width, thereby ensuring the overcurrent capacity of the second output pole connecting piece 1225 and preventing the second output pole connecting piece 1225 from being heated or even fused. When the first limiting groove formed by the second output pole base 1223 is of a non-equal-width structure, for example, the width of the second output pole base 1223 close to the second output pole connecting piece 1225 is relatively large, the second output pole connecting piece 1225 can also be connected with the second transition connecting piece 124 on the second output pole base 1223 with the relatively large width, and in this case, the first end 1241 of the second transition connecting piece 124 does not need to extend out of the second output pole base 1223, and the width of the second output pole connecting piece 1225 is not affected, so that the overcurrent capacity of the second output pole connecting piece 1225 is not reduced.

[0063] As shown in FIGS. 7-9, in the second direction Z, the first output pole base 1213 is located on one side of the first end plate 1212, and the second output pole base 1223 is located on one side of the second end plate 1222. The second direction Z is the height direction of the battery pack 100.

[0064] The first output pole connecting piece 1215 and the conduction connecting piece 125 are located on opposite sides of the first transition connecting piece 123 along the second direction Z. By locating the first output pole connecting piece 1215 and the conduction connecting piece 125 on opposite sides of the first transition connecting piece 123 along the second direction Z, i.e., when the first transition connecting piece 123 is arranged, the first output pole connecting piece 1215, the transition connecting piece, and the conduction connecting piece 125 can be arranged in a thickness direction, facilitating the connection between the first output pole connecting piece 1215, the first transition connecting piece 123, and the conduction connecting piece 125. Of course, the first output pole connecting piece 1215 and the conduction connecting piece 125 can also be located on the same side of the first transition connecting piece 123 along the second direction Z, and the present disclosure does not limit this.

[0065] The second output pole connecting piece 1225 and the conduction connecting piece 125 are located on opposite sides of the second transition connecting piece 124 along the second direction Z. By locating the second output pole connecting piece 1225 and the conduction connecting piece 125 on opposite sides of the second transition connecting piece 124 along the second direction Z, i.e., when the second transition connecting piece 124 is arranged, the second output pole connecting piece 1225, the second transition connecting piece 124, and the conduction connecting piece 125 can be arranged in a thickness direction, facilitating the connection between the first output pole connecting piece 1215, the second transition connecting piece 124, and the conduction connecting piece 125. Of course, the second output pole connecting piece 1225 and the conduction connecting piece 125 can also be located on the same side of the second transition connecting piece 124 along the second direction Z, and the present disclosure does not limit this.

[0066] In one embodiment, as shown in FIGS. 8-14, the first transition connecting piece 123 includes oppositely arranged first and second connecting portions 1233 and 1234 along the first direction X, the first connecting portion 1233 is connected with the first output pole connecting piece 1215, and the second connecting portion 1234 is connected with the conduction connecting piece 125, and the second connecting portion 1234 is sunken toward the side of the end plate relative to the first connecting portion 1233 along the second direction Z. By sinking the second connecting portion 1234 on the first transition connecting piece 123 relative to the first connecting portion 1233 along the second direction Z, when the first transition connecting piece 123 is connected with the conduction connecting piece 125, the fifth connecting portion 1253 of the conduction connecting piece 125 connected with the first transition connecting piece 123 is located on the sunken second connecting portion 1234, and the height of the fifth connecting portion 1253 is lowered. Due to the displacement of the cell expansion, the conduction connecting piece 125 will also be pulled / pushed and other displacement phenomena will occur with the displacement of the cell expansion, and the height of the fifth connecting portion 1253 is lowered to reserve a certain space height for the buffer structure design of the conduction connecting piece 125, to avoid the position of the conduction connecting piece 125 being raised due to the setting of the first transition connecting piece 123, which on one hand avoids occupying too much space of the battery pack 100, leading to the reduction of the space utilization rate of the battery pack 100, and further affecting the capacity of the battery pack 100; on the other hand, it avoids the friction between the too high conduction connecting piece 125 and other structures above in the battery pack 100, to affect the structural stability and insulation reliability.

[0067] As shown in FIGS. 8-14, the second transition connecting piece 124 includes oppositely arranged third connecting portions 1243 and fourth connecting portions 1244 along the first direction X, the third connecting portions 1243 are connected with the second output pole connecting piece 1225, the fourth connecting portions 1244 are connected with the conduction connecting piece 125, and the fourth connecting portions 1244 are sunken toward the side of the end plate relative to the third connecting portions 1243 along the second direction Z. By sinking the fourth connecting portions 1244 on the second transition connecting piece 124 relative to the third connecting portions 1243 along the second direction Z toward the side of the end plate, when the second transition connecting piece 124 is connected with the conduction connecting piece 125, the sixth connecting portions 1254 of the conduction connecting piece 125 connected with the second transition connecting piece 124 are located on the sunken fourth connecting portions 1244, and the height of the sixth connecting portions 1254 is lowered. Due to the displacement of the battery cell expansion, the conduction connecting piece 125 will also be pulled / pushed and other displacement phenomena will occur with the displacement of the battery cell expansion, and the height of the fifth connecting portions 1253 is lowered to reserve a certain space height for the buffer structure design of the conduction connecting piece 125, avoiding the position of the conduction connecting piece 125 being raised due to the setting of the second transition connecting piece 124, which on the one hand avoids occupying too much space of the battery pack 100, leading to the reduction of the space utilization rate of the battery pack 100, and further affecting the capacity of the battery pack 100; on the other hand, avoiding the friction between the too high conduction connecting piece 125 and other structures above in the battery pack 100, so as to affect the structural stability and insulation reliability.

[0068] Meanwhile, when the first output pole connecting piece 1215 and the conduction connecting piece 125 are located on the opposite sides of the first transition connecting piece 123 along the second direction Z, and the second output pole connecting piece 1225 and the conduction connecting piece 125 are located on the opposite sides of the second transition connecting piece 124 along the second direction Z, by sinking the second connecting portions 1234 on the first transition connecting piece 123 relative to the first connecting portions 1233 along the second direction Z toward the side of the end plate, and sinking the fourth connecting portions 1244 on the second transition connecting piece 124 relative to the third connecting portions 1243 along the second direction Z toward the side of the end plate, i.e., the surface of the second connecting portions 1234 located on the first output pole base 1213 can be flush or substantially flush with the surface of the first output pole connecting piece 1215, and the surface of the fourth connecting portions 1244 located on the second output pole base 1223 can be flush or substantially flush with the surface of the second output pole connecting piece 1225, so that the conduction connecting piece 125 will not need to be redesigned due to the setting of the first transition connecting piece 123 and the second transition connecting piece 124, and the original conduction connecting piece 125 can be used, thereby saving certain research and development costs and improving research and development efficiency in the product production and research and development process.

[0069] During the operation of the battery cell, the battery cell will expand. When the battery cells are stacked into a module, the expansion of the battery cells will cause the deformation of the battery module 120 as a whole. At this time, the distance between the end plate at the end of the battery module 120 and the battery cell becomes larger, the transition connecting piece is pulled and is prone to deformation, and even causes poor electrical connection.

[0070] In one embodiment, as shown in FIGS. 8 and 14, the first transition connecting piece 123 includes a first connecting portion 1233 and a second connecting portion 1234 arranged oppositely along the first direction X. The first connecting portion 1233 is connected with the first output pole connecting piece 1215, and the second connecting portion 1234 is connected with the conduction connecting piece 125. A first bending portion 1235 is further arranged between the first connecting portion 1233 and the second connecting portion 1234 of the first transition connecting piece 123. By arranging the first bending portion 1235 between the first connecting portion 1233 and the second connecting portion 1234 of the first transition connecting piece 123, when the first transition connecting piece 123 is subjected to a tensile force, the first bending portion 1235 can absorb the tensile force, thereby avoiding the breakage of the first transition connecting piece 123, causing the electrical connection failure between the battery modules 120, and reducing the service life of the battery pack 100.

[0071] When the second connecting portion 1234 of the first transition connecting piece 123 sinks relative to the first connecting portion 1233 along the second direction Z toward the side of the end plate, the first bending portion 1235 is bent to form relative to the first connecting portion 1233 along the sinking. Of course, the first bending portion 1235 can be a curved structure that is arched on a plane, and the present disclosure does not limit this.

[0072] As shown in FIGS. 8 and 14, the second transition connecting piece 124 includes a third connecting portion 1243 and a fourth connecting portion 1244 arranged oppositely along the first direction X. The third connecting portion 1243 is connected with the second output pole connecting piece 1225, and the fourth connecting portion 1244 is connected with the conduction connecting piece 125. A second bending portion 1245 is further arranged between the third connecting portion 1243 and the fourth connecting portion 1244 of the second transition connecting piece 124. Since the battery cell of the battery monomer has the phenomenon of expansion after long-term use, a tensile force in the second direction Z is caused to the second transition connecting piece 124, which is prone to deformation or even breakage of the second transition connecting piece 124. By arranging the second bending portion 1245 between the third connecting portion 1243 and the fourth connecting portion 1244 of the second transition connecting piece 124, when the second transition connecting piece 124 is subjected to a tensile force, the second bending portion 1245 can absorb the tensile force, thereby avoiding the breakage of the second transition connecting piece 124, causing the electrical connection failure between the battery modules 120, and reducing the service life of the battery pack 100.

[0073] When the fourth connecting portion 1244 of the second transition connecting piece 124 sinks relative to the third connecting portion 1243 along the second direction Z towards the side of the end plate, the second bending portion 1245 is bent when the fourth connecting portion 1244 sinks relative to the third connecting portion 1243. Of course, the second bending portion 1245 can be a bending structure that is arched on the plane, and the present disclosure does not limit this.

[0074] As shown in FIGS. 8-12, the conducting connecting piece 125 includes oppositely arranged fifth connecting portions 1253 and sixth connecting portions 1254 along the first direction X, the fifth connecting portions 1253 are connected with the first transition connecting piece 123, and the sixth connecting portions 1254 are connected with the second transition connecting piece 124; the fifth connecting portions 1253 and the sixth connecting portions 1254 of the conducting connecting piece 125 are further provided with third bending portions 1255 therebetween. Due to the expansion phenomenon of the battery cell after long-term use, the conducting connecting piece 125 will be subjected to a stretching force from the first transition connecting piece 123 and the second transition connecting piece 124, which causes the conducting connecting piece 125 to be stretched in the second direction Z, easily leading to deformation or even breakage of the conducting connecting piece 125; by arranging the third bending portions 1255, when the conducting connecting piece 125 is subjected to a stretching force, the third bending portions 1255 can absorb the stretching force, avoiding deformation or even breakage of the conducting connecting piece 125. Of course, the conducting connecting piece 125 can also not be provided with a bending structure as shown in FIG. 11, and the present disclosure does not limit this.

[0075] The first transition connecting piece 123 is provided with the first bending portion 1235, the second transition connecting piece 124 is provided with the second bending portion 1245, and the conducting connecting piece 125 is provided with the third bending portion 1255, that is, three bending structures capable of absorbing the stretching force are formed between the adjacent first battery module 121 and the second battery module 122, further improving the reliability of the electrical connection structure between the first battery module 121 and the second battery module 122.

[0076] In one embodiment, as shown in FIG. 13, an insulating layer 1256 is arranged on the region between the fifth connecting portions 1253 and the sixth connecting portions 1254 of the conducting connecting piece 125. Since the end plates at both ends of the battery module 120 are usually metal end plates capable of conducting electricity, there is a risk of short circuit between the conducting connecting piece 125 and the end plate, seriously affecting the safety performance of the battery pack 100; by arranging the insulating layer 1256 on the region between the fifth connecting portions 1253 and the sixth connecting portions 1254 of the conducting connecting piece 125, the insulation performance between the conducting connecting piece 125 and the metal end plate is improved, reducing the risk of short circuit between the conducting connecting piece 125 and the end plate, and improving the safety performance of the battery pack 100.

[0077] The insulating layer 1256 can be an insulating tape adhered to the surface of the conductive connecting piece 125 that needs to be insulated, or the insulating layer 1256 can be a coating layer for coating the surface of the conductive connecting piece 125 that needs to be insulated with an insulating material. The specific material and arrangement of the insulating layer 1256 are not limited in the present disclosure.

[0078] In one embodiment, as shown in FIGS. 8 and 14, the first transition connecting piece 123 is provided with a first avoiding gap 1236 on one end of the first output pole connecting piece 1215 in the first direction X, which is used to avoid the position where the first output pole connecting piece 1215 is connected with the electrode of the battery monomer. The first output pole connecting piece 1215 and the pole of the first battery monomer 1211 are usually connected together by laser welding. After the first transition connecting piece 123 is arranged, the first avoiding gap 1236 on the first transition connecting piece 123 can form an avoidance for the position where the first output pole connecting piece 1215 is welded with the pole. At the same time, the welding tool for welding the first output pole connecting piece 1215 with the pole can also be avoided through the first avoiding gap 1236, so as to avoid the interference between the first transition connecting piece 123 and the welding tool.

[0079] As shown in FIGS. 8 and 14, the second transition connecting piece 124 is provided with a second avoiding gap 1246 on one end of the second output pole connecting piece 1225 in the first direction X, which is used to avoid the position where the second output pole connecting piece 1225 is connected with the electrode of the battery monomer. The second output pole connecting piece 1225 and the pole of the second battery monomer 1221 are usually connected together by laser welding. After the second transition connecting piece 124 is arranged, the second avoiding gap 1246 on the second transition connecting piece 124 can form an avoidance for the position where the second output pole connecting piece 1225 is welded with the pole. At the same time, the welding tool for welding the second output pole connecting piece 1225 with the pole can also be avoided through the second avoiding gap 1246, so as to avoid the interference between the second transition connecting piece 124 and the welding tool.

[0080] In one embodiment, as shown in FIGS. 8 and 9, the first end 1251 of the conducting connecting piece 125 is fixedly connected to the first output pole base 1213 through a threaded member. After the first transition connecting piece 123 is arranged on the first output pole base 1213, the fifth connecting part 1253 on the conducting connecting piece 125 is then overlaid on the first transition connecting piece 123, and the mounting hole on the fifth connecting part 1253 is aligned with the mounting hole on the first transition connecting piece 123. Then, the threaded rod 126 is threaded through the mounting holes on the fifth connecting part 1253 and the first transition connecting piece 123, and is screwed into the threaded hole on the first output pole base 1213, so as to fix the part connecting the conducting connecting piece 125 and the first transition connecting piece 123 on the first output pole base 1213, facilitating the installation and dismounting of the conducting connecting piece 125 and the first transition connecting piece 123. Of course, the part connecting the conducting connecting piece 125 and the first transition connecting piece 123 can also be connected through welding, bonding, clamping or the like, which is not limited in the present disclosure.

[0081] As shown in FIGS. 8 and 9, the second end 1252 of the conducting connecting piece 125 is fixedly connected to the second output pole base 1223 through a threaded member. After the second transition connecting piece 124 is arranged on the second output pole base 1223, the sixth connecting part 1254 on the conducting connecting piece 125 is then overlaid on the second transition connecting piece 124, and the mounting hole on the sixth connecting part 1254 is aligned with the mounting hole on the second transition connecting piece 124. Then, the threaded rod 126 is threaded through the mounting holes on the sixth connecting part 1254 and the second transition connecting piece 124, and is screwed into the threaded hole on the second output pole base 1223, so as to fix the part connecting the conducting connecting piece 125 and the second transition connecting piece 124 on the second output pole base 1223. Of course, the part connecting the conducting connecting piece 125 and the second transition connecting piece 124 can also be connected through welding, bonding, clamping or the like, which is not limited in the present disclosure.

[0082] In one embodiment, the first transition connecting piece 123 is welded with the first output pole connecting piece 1215. By welding the first transition connecting piece 123 with the first output pole connecting piece 1215, the connection efficiency between the first transition connecting piece 123 and the first output pole connecting piece 1215 is high, and the connection strength is high. At the same time, through welding, the first transition connecting piece 123 and the first output pole connecting piece 1215 can be in full contact, avoiding the existence of gaps between the contact surfaces of the first transition connecting piece 123 and the first output pole connecting piece 1215, so that the contact resistance between the two is relatively low, improving the overcurrent capacity and reducing the heat generation.

[0083] The first protruding part is located in the first recessed part. The first protruding part and the first recessed part can be a welding structure left when the first transition connecting piece 123 and the first output pole connecting piece 1215 are welded. By locating the first protruding part in the first recessed part, the connection reliability of the first transition connecting piece 123 and the first output pole connecting piece 1215 is improved.

[0084] The second transition connecting piece 124 and the second output pole connecting piece 1225 are welded. By welding the second transition connecting piece 124 and the second output pole connecting piece 1225, the connection efficiency between the second transition connecting piece 124 and the second output pole connecting piece 1225 is high, and the connection strength is high. At the same time, through welding, the second transition connecting piece 124 and the second output pole connecting piece 1225 can be in full contact, avoiding the existence of gaps between the contact surfaces of the second transition connecting piece 124 and the second output pole connecting piece 1225, so that the contact resistance between the two is relatively low, the overcurrent capacity is improved, and the heat generation is reduced.

[0085] The second protruding part is located in the second recessed part. The second protruding part and the second recessed part can be a welding structure left when the second transition connecting piece 124 and the second output pole connecting piece 1225 are welded. By locating the second protruding part in the second recessed part, the connection reliability of the second transition connecting piece 124 and the second output pole connecting piece 1225 is improved.

[0086] In one embodiment, the resistance of the first transition connecting piece 123 is less than or equal to the resistance of the conduction connecting piece 125, or the resistance of the second transition connecting piece 124 is less than or equal to the resistance of the conduction connecting piece 125, or the resistance of the first transition connecting piece 123 and the second transition connecting piece 124 is less than or equal to the resistance of the conduction connecting piece 125.

[0087] The first output pole connecting piece 1215 and the second output pole connecting piece 1225 can adopt an aluminum bar, and the conduction connecting piece 125 can adopt a copper bar. The first transition connecting piece 123 can adopt a copper bar, so that the resistance of the first transition connecting piece 123 is less than that of the first output pole connecting piece 1215. The second transition connecting piece 124 can also adopt a copper bar, so that the resistance of the second transition connecting piece 124 is less than that of the second output pole connecting piece 1225. When the first transition connecting piece 123 and the second transition connecting piece 124 adopt a copper bar, the resistance is the same as that of the conduction connecting piece 125. Of course, the first transition connecting piece 123 and the second transition connecting piece 124 can also adopt a conductive piece with a resistance between that of a copper bar and that of an aluminum bar, such as a copper-aluminum composite conductive piece.

[0088] When the first transition connecting piece 123 and the second transition connecting piece 124 adopt copper bars, the first output pole connecting piece 1215 and the second output pole connecting piece 1225 adopt aluminum bars, because the materials of the copper bars and the aluminum bars are different, it is not easy to weld, and the soldering method can be used to realize the electrical connection between copper and aluminum, and generally, the soldering needs to melt additional solder to realize the connection between the welding parts; however, the output pole connecting piece and the transition connecting piece are stacked, and it is not easy to operate and difficult to weld if soldering is used, so the common soldering cannot be used; for this purpose, the molecular diffusion welding is used in the present disclosure to realize the electrical connection of the stacked copper-aluminum structure; however, the molecular diffusion welding has high process requirements.

[0089] For this purpose, in one embodiment of the present disclosure, as shown in FIG. 15, the first transition connecting piece 123 includes a first conductive layer 1237 and a second conductive layer 1238 along the second direction Z, the first conductive layer 1237 is located on the side facing the first output pole connecting piece 1215 and has the same material as the first output pole connecting piece 1215, and the second conductive layer 1238 is located on the side facing the on-connecting piece 125 and has the same material as the on-connecting piece 125, that is, the first transition connecting piece 123 is a composite connecting piece, the lower half layer of the composite connecting piece in contact with the aluminum bar is aluminum, and the upper half part in contact with the copper bar is copper, under the condition of meeting the overcurrent requirement, the welding between the first transition connecting piece 123 and the first output pole connecting piece 1215 becomes easier, and the laser welding method can be used to realize the electrical connection, reducing the welding difficulty.

[0090] As shown in FIG. 15, the second transition connecting piece 124 includes a third conductive layer 1247 and a fourth conductive layer 1248 along the second direction Z, the third conductive layer 1247 is located on the side facing the second output pole connecting piece 1225 and has the same material as the second output pole connecting piece 1225, and the fourth conductive layer 1248 is located on the side facing the on-connecting piece 125 and has the same material as the on-connecting piece 125, that is, the second transition connecting piece 124 is a composite connecting piece, the lower half layer of the composite connecting piece in contact with the aluminum bar is aluminum, and the upper half part in contact with the copper bar is copper, under the condition of meeting the overcurrent requirement, the welding between the second transition connecting piece 124 and the second output pole connecting piece 1225 becomes easier, and the laser welding method can be used to realize the electrical connection, reducing the welding difficulty.

[0091] When the first transition connecting piece 123 and the second transition connecting piece 124 adopt the composite connecting piece with the upper half part of copper and the lower half part of aluminum, the thickness of the upper half part of copper can be greater than the thickness of the lower half part of aluminum to reduce the resistance of the composite connecting piece.

[0092] In one embodiment, as shown in FIGS. 5 and 6, the first output pole base 1213 can be provided with a first base cover plate 1214, both the first base cover plate 1214 and the first output pole base 1213 being made of insulating material. By providing the first base cover plate 1214, an insulating space can be formed together with the first output pole base 1213, so as to form an insulating covering for the first end 1251 of the conduction connecting piece 125, the second end 1232 of the first transition connecting piece 123 and the first threaded member 1261, thereby improving the insulating performance of the first end 1251 of the conduction connecting piece 125, the first end 1231 of the first transition connecting piece 123 and the first threaded member 1261 at the first output pole base 1213.

[0093] As shown in FIGS. 5 and 6, the second output pole base 1223 can be provided with a second base cover plate 1224, both the second base cover plate 1224 and the second output pole base 1223 being made of insulating material. By providing the second base cover plate 1224, an insulating space can be formed together with the second output pole base 1223, so as to form an insulating covering for the second end 1252 of the conduction connecting piece 125, the second end 1242 of the second transition connecting piece 124 and the second threaded member 1262, thereby improving the insulating performance of the second end 1252 of the conduction connecting piece 125, the second end 1232 of the second transition connecting piece 124 and the second threaded member 1262 at the second output pole base 1223.

[0094] In one embodiment, the plurality of battery modules 120 includes a plurality of groups of the first battery module 121 and the second battery module 122, and the plurality of groups of the first battery module 121 and the second battery module 122 are arranged along the third direction Y. The first battery module 121 and the second battery module 122 in each group are connected by the first transition connecting piece 123, the second transition connecting piece 124 and the conduction connecting piece 125. The first transition connecting piece 123, the second transition connecting piece 124 and the conduction connecting piece 125 are used to connect adjacent battery modules 120, which can further improve the safety performance of the battery pack 100.

[0095] In the embodiments of the present disclosure, the terms "first", "second", "third" are only for descriptive purposes, and should not be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise explicitly limited. The terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, "connecting" can be fixed connection, or detachable connection, or integrally connected; "connected" can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to the specific circumstances.

[0096] In the description of the embodiments of the present disclosure, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the embodiments of the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular direction, be constructed and operated in a particular orientation, and therefore, cannot be understood as a limitation on the embodiments of the present disclosure.

[0097] In the description of the present disclosure, the description of the terms "one embodiment", "some embodiments", "a specific embodiment", and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0098] Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The present disclosure is intended to cover any variations, uses, or adaptations of the present disclosure following the general principles thereof and including such departures from the present disclosure that come within known, accepted, or customary practice in the art to which the present disclosure pertains. The specification and examples are to be regarded as illustrative only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

1. A battery pack, comprising: a battery box formed with a battery compartment; a plurality of battery modules located in the battery compartment; each of the battery modules comprises a plurality of battery cells arranged along a first direction and end plates clamped at both ends of the plurality of battery cells; the plurality of battery modules at least comprises a first battery module and a second battery module arranged adjacent along the first direction, a first output pole base insulated is provided on a first end plate adjacent to the second battery module in the first battery module, and a first output pole connecting piece is provided on the battery cell adjacent to the first end plate; a second output pole base insulated is provided on a second end plate adjacent to the first battery module in the second battery module, and a second output pole connecting piece is provided on the battery cell adjacent to the second end plate; a first transition connecting piece and a second transition connecting piece, the first transition connecting piece is located on the first output pole base and connected with the first output pole connecting piece, and the resistance of the first transition connecting piece is smaller than that of the first output pole connecting piece; the second transition connecting piece is located on the second output pole base and connected with the second output pole connecting piece, and the resistance of the second transition connecting piece is smaller than that of the second output pole connecting piece; a conduction connecting piece comprising a first end and a second end oppositely arranged along the first direction, the first end is connected with the first transition connecting piece, and the second end is connected with the second transition connecting piece.

2. The battery pack of claim 1, wherein, The first output pole connecting piece and the first output pole base are spaced apart in the first direction, one end of the first transition connecting piece extends out of the first output pole base and is connected with the first output pole connecting piece; and / or, the second output pole connecting piece and the second output pole base are spaced apart in the first direction, one end of the second transition connecting piece extends out of the second output pole base and is connected with the second output pole connecting piece.

3. The battery pack of claim 1, wherein, In a second direction, the first output pole base is located on one side of the first end plate, and the second output pole base is located on one side of the second end plate; The first output pole connecting piece and the conduction connecting piece are located on two sides of the first transition connecting piece opposite along the second direction, and / or the second output pole connecting piece and the conduction connecting piece are located on two sides of the second transition connecting piece opposite along the second direction.

4. The battery pack of claim 1, wherein, The first transition connecting piece is provided with a first avoiding notch on one end thereof facing the first output pole connecting piece along the first direction, the first avoiding notch is used for avoiding the position where the first output pole connecting piece is connected with the electrode of the battery cell; and / or the second transition connecting piece is provided with a second avoiding notch on one end thereof facing the second output pole connecting piece along the first direction, the second avoiding notch is used for avoiding the position where the second output pole connecting piece is connected with the electrode of the battery cell.

5. The battery pack of claim 1, wherein, In a second direction, the first output pole base is located on one side of the first end plate, and the second output pole base is located on one side of the second end plate; The first transition connecting piece includes oppositely arranged first and second connecting portions along the first direction, the first connecting portion is connected with the first output pole connecting piece, the second connecting portion is connected with the conduction connecting piece, and the second connecting portion is sunken toward the side of the first end plate relative to the first connecting portion along the second direction; and / or the second transition connecting piece includes oppositely arranged third and fourth connecting portions along the first direction, the third connecting portion is connected with the second output pole connecting piece, the fourth connecting portion is connected with the conduction connecting piece, and the fourth connecting portion is sunken toward the side of the second end plate relative to the third connecting portion along the second direction.

6. The battery pack of claim 1, wherein, The first transition connecting piece includes oppositely arranged first and second connecting portions along the first direction, the first connecting portion is connected with the first output pole connecting piece, the second connecting portion is connected with the conduction connecting piece; the first transition connecting piece is further provided with a first bending portion between the first and second connecting portions; and / or the second transition connecting piece includes oppositely arranged third and fourth connecting portions along the first direction, the third connecting portion is connected with the second output pole connecting piece, the fourth connecting portion is connected with the conduction connecting piece; the second transition connecting piece is further provided with a second bending portion between the third and fourth connecting portions.

7. The battery pack of claim 1, wherein, The conduction connecting piece includes oppositely arranged fifth and sixth connecting portions along the first direction, the fifth connecting portion is connected with the first transition connecting piece, the sixth connecting portion is connected with the second transition connecting piece; the conduction connecting piece is further provided with a third bending portion between the fifth and sixth connecting portions.

8. The battery pack of claim 1, wherein, The first output pole base is provided with a first limiting groove, and the first transition connecting piece is located in the first limiting groove; At least part of the first output pole connecting piece has a width greater than that of the first limiting groove along a third direction; and / or the second output pole base is provided with a second limiting groove, and the second transition connecting piece is located in the second limiting groove; at least part of the second output pole connecting piece has a width greater than that of the second limiting groove along the third direction; The first output pole base is located on one side of the first end plate along a second direction, and the third direction intersects the first and second directions.

9. The battery pack of claim 1, wherein, The first end of the conduction connecting piece is fixedly connected with the first transition connecting piece on the first output pole base by a threaded member, and / or the second end of the conduction connecting piece is fixedly connected with the second transition connecting piece on the second output pole base by a threaded member.

10. The battery pack of claim 1, wherein, The first transition connecting piece is welded with the first output pole connecting piece, and / or the second transition connecting piece is welded with the second output pole connecting piece.

11. The battery pack of claim 1, wherein, The first transition connecting piece is provided with a first protruding portion, the first output pole connecting piece is provided with a first recessed portion, and the first protruding portion is located in the first recessed portion; And / or, the second transition connecting piece is provided with a second protruding part, the second output pole connecting piece is provided with a second recessed part, and the second protruding part is located in the second recessed part.

12. The battery pack of claim 1, wherein, The first transition connecting piece and / or the second transition connecting piece has a resistance less than or equal to that of the conducting connecting piece.

13. The battery pack of claim 1, wherein, The first transition connecting piece and / or the second transition connecting piece is made of the same material as the conducting connecting piece.

14. The battery pack of claim 1, wherein, In the second direction, the first output pole base is located on one side of the first end plate, and the second output pole base is located on one side of the second end plate. The first transition connecting piece includes a first conductive layer and a second conductive layer in the second direction, the first conductive layer is located on a side facing the first output pole connecting piece and is made of the same material as the first output pole connecting piece, and the second conductive layer is located on a side facing the conducting connecting piece and is made of the same material as the conducting connecting piece; and / or, the second transition connecting piece includes a third conductive layer and a fourth conductive layer in the second direction, the third conductive layer is located on a side facing the second output pole connecting piece and is made of the same material as the second output pole connecting piece, and the fourth conductive layer is located on a side facing the conducting connecting piece and is made of the same material as the conducting connecting piece.

15. The battery pack of claim 1, wherein, The plurality of battery modules includes a plurality of groups of the first battery module and the second battery module, and the plurality of groups of the first battery module and the second battery module are arranged in a third direction; the first battery module and the second battery module in each group are connected through the first transition connecting piece, the second transition connecting piece and the conducting connecting piece; wherein the first output pole base is located on one side of the first end plate in the second direction, and the third direction intersects the first direction and the second direction.

16. An energy storage system comprising the battery pack of any one of claims 1-15.

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