CN112563651A

CN112563651A - Connection structure of tab and bus bar, electrochemical device and electric device

Info

Publication number: CN112563651A
Application number: CN202011574390.5A
Authority: CN
Inventors: 谭志谋
Original assignee: Dongguan Poweramp Technology Ltd
Current assignee: Dongguan Poweramp Technology Ltd
Priority date: 2020-12-25
Filing date: 2020-12-25
Publication date: 2021-03-26

Abstract

The application discloses connection structure, electrochemical device and power consumption device of utmost point ear and busbar, it can improve the problem that welding that utmost point ear and busbar adopted laser welding to lead to is bad and can not do over again. The connection structure of the lug and the bus bar comprises a groove arranged in the bus bar; the pressing piece is used for pressing one part of the tab in the groove of the bus bar and attaching the tab to the groove; and the fastening piece is used for fixing the lug, the pressing piece and the bus bar together.

Description

Connection structure of tab and bus bar, electrochemical device and electric device

Technical Field

The application relates to the technical field of electrochemistry, in particular to a connection structure of a lug and a bus bar, an electrochemical device and an electric device.

Background

In recent years, with the popularization and development of new energy automobiles, the cost and reliability of lithium batteries are receiving more and more attention.

In the manufacturing process of the lithium battery, the battery cells are formed first, and then the battery cells are grouped to generate the module. The cell grouping module is mainly used for completing mechanical connection and electrical connection between cells, wherein the electrical connection directly affects the performance of the module, and therefore, more importantly, the electrical connection between the cells on the module is completed through a structural member called a bus bar. For a soft package battery, the connection between a bus bar and a tab on a module is mainly completed through laser welding, but poor welding between the tab and the bus bar is easy to occur. Products with poor welding are put into use, which can cause larger internal resistance, higher temperature and even welding falling in the using process to strike fire, which can cause great influence on the performance and safety of the power battery.

The poor welding caused by the existing laser welding mainly has the following reasons: because the tab material and the bus bar material are made of high-reflectivity materials such as aluminum alloy or red copper, the absorptivity of the high-reflectivity materials to the optical fiber laser is not high, and the stability of the welding process is poor; meanwhile, the materials such as aluminum alloy, red copper and the like are very good in heat conductivity, welding seams are difficult to form, and air holes are easy to generate; the laser welding has higher requirement on the surface roughness of the tab due to different material reflectivity with different roughness, so that the requirement on the surface of the incoming material tab is very high; the requirement of laser welding on the surface tension of the tab is high, and any pollution on the surface of the tab has a certain influence on the welding effect. When a single electric core breaks down, the lug and the busbar adopt a welded connection structure, and the disassembly is difficult. The battery cell belongs to a high-cost accessory, and can not be reworked by adopting a welding process, so that the manufacturing cost is greatly increased.

Disclosure of Invention

The application provides a connection structure, electrochemical device and with electric installation of utmost point ear and busbar, it can improve the problem that welding that utmost point ear and busbar adopted laser welding to lead to is bad and can not do over again.

The embodiment of the application provides a connection structure of utmost point ear and busbar, includes recess, compresses tightly piece and fastener. The groove is provided on the bus bar. The pressing piece presses a part of the tab in the groove of the bus bar and is attached to the groove. The fastening piece fixes the tab, the pressing piece and the bus bar together.

The connection structure of utmost point ear and busbar that this application embodiment provided is through setting up the recess at the busbar to press partial utmost point ear in the recess of busbar and laminate and fix through the fastener with the recess through compressing tightly the piece, thereby guaranteed the reliable connection of utmost point ear and busbar, avoided adopting the welding that laser welding leads to bad and can not rework the problem.

Wherein the grooves extend in the width direction of the tab. In the width direction of the whole lug, the lug and the groove of the bus bar form a contact strip, so that reliable electric connection can be ensured, and the contact resistance can be reduced.

Wherein the cross section of the groove is arc-shaped or V-shaped. The arc-shaped or V-shaped groove can increase the connection area of the pole lug and the bus bar, so that the connection resistance of the pole lug and the bus bar is reduced.

And the lug is provided with a sunken part, and the sunken part is matched with the groove of the busbar. Can suppress the depressed part with the recess adaptation in advance on the utmost point ear, can guarantee the laminating of utmost point ear and recess, reduce the installation degree of difficulty.

The pressing piece is provided with a protruding portion pointing to the groove, and the protruding portion is used for applying pressure pointing to the groove to the tab under the action of the fastener. The pressure pointing to the groove is applied to the pole lug through the protruding part, and the fitting degree of the pole lug and the groove is guaranteed.

The pressing piece is an elastic pressing piece, and a part of area of the elastic pressing piece is sunken downwards to form the protruding portion, or the elastic pressing piece is a V-shaped stainless steel elastic piece. The protruding part of the elastic pressing sheet can be formed in a pressing forming mode, and the method is simple and low in cost. In addition, the V-shaped stainless steel elastic sheet has the advantages of simple structure and low cost.

The pressing piece is a strip-shaped V-shaped pressing piece, one end of the pressing piece is fixed in the groove through a clamping structure, and the other end of the pressing piece is fixed through the fastener. One end is fixed through the clamping structure, so that the using quantity of fasteners can be reduced, and the assembly efficiency is improved.

The bus bar comprises a bus bar support and a drainage bar, and the groove is formed in the drainage bar. The drainage bar needs to be made of a high-conductivity material, the bus bar support does not need, and the bus bar is designed into the drainage bar and the bus bar support for accommodating the drainage bar, so that the cost of the bus bar can be reduced.

The fastener comprises a screw, the bracket and the drainage bar of the busbar are provided with corresponding threaded holes, and the pressing piece is provided with corresponding through holes.

The battery pack comprises a compression piece, a busbar and a battery core, wherein a first tab and a second tab which are stacked are arranged between the compression piece and the busbar, and the first tab and the second tab are connected to two adjacent battery cells respectively. At same tie point, can be connected the utmost point ear and the busbar of two adjacent electric cores simultaneously, reduce the tie point of utmost point ear and busbar, improve assembly efficiency.

And the bus bar is provided with lug lead holes at two sides of the groove for the first lug and the second lug to pass through. The direction and the position of the pole lug can be fixed through the pole lug lead hole, so that the pole lug is arranged orderly, and the risk of short circuit between the pole lug and other components is reduced.

The embodiment of the application also provides an electrochemical device, which comprises a plurality of battery cells and the connecting structure of the tab and the bus bar. The tab is electrically connected with the pole piece of the battery cell.

The embodiment of the application also provides an electric device, which comprises the electrochemical device and a load, wherein the electrochemical device is used for supplying power to the load.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings used in the description of the embodiments will be briefly introduced below. It is obvious that the drawings in the following description are only some embodiments of the application, and that other drawings may be derived from these drawings by a person skilled in the art.

FIG. 1 is a schematic view of an electrochemical device according to an embodiment of the present application;

fig. 2 is a schematic view of a connection structure of a tab and a busbar according to an embodiment of the application;

FIG. 3 is a schematic view of a drainage bank according to an embodiment of the present application;

FIG. 4 is a schematic view of a compression member according to an embodiment of the present application;

fig. 5 is a schematic view of the assembly of a tab with a busbar according to an embodiment of the present application;

FIG. 6 is a schematic structural view of another hold-down member provided in example 1 in a comparative test provided herein;

FIG. 7 is a schematic structural view of another drainage bank of example 1 in a comparative experiment provided in accordance with the present application;

fig. 8 is a schematic view showing the assembly of the tab with the busbar of example 1 in a comparative test provided according to the present application.

Detailed Description

The technical solutions in the embodiments of the present application are clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. The following embodiments and their technical features may be combined with each other without conflict.

The electrochemical device of the present application includes all devices in which electrochemical reactions occur. By way of example, electrochemical devices include, but are not limited to, all kinds of primary, secondary, fuel cells, solar cells, and capacitor (e.g., supercapacitor) electrochemical devices. The electrochemical device is particularly preferably a lithium secondary battery including, but not limited to, a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, and a lithium ion polymer secondary battery.

Some embodiments according to the present application are described below with reference to fig. 1-5, taking a lithium ion battery as an example.

As shown in fig. 1 and 2, an embodiment of the present application provides a connection structure of a tab 1 and a busbar 2, the connection structure including: a groove 21 provided on the busbar 2, a pressing member 3 and a fastening member 4. The tab 1 is electrically connected with a pole piece of the battery cell 10. And the pressing piece 3 presses a part of the tab 1 in the groove 21 and is jointed with the groove 21 arranged on the female bus bar 2, so that the tab 1 is electrically connected with the bus bar 2. The fastening member 4 is used to fix the pressing member 3, the tab 1, and the bus bar 2 together, so that the tab 1 maintains a state of being attached to the groove 21.

As shown in fig. 2, in some embodiments, bus bar 2 may include a bus bar bracket 20 and a drain bar 22. The lead rows 22 are provided with grooves 21 extending in the width direction AA' of the tab 1. After the tab 1 is bent, through the pressing piece 3, a part of the tail end of the tab 1 is pressed in the groove 21 of the bus bar 2 and attached to the groove 21, so that the reliable connection between the tab 1 and the bus bar 2 can be ensured. Because all be connected with utmost point ear 1 in the whole length direction of recess 21, form the contact electrical connection area, utmost point ear 1 is less and connect more reliably with the connecting resistance of busbar 2, can satisfy the design demand.

The groove 21 is designed to be used as a connection point of the tab 1 and the bus bar 2, and poor contact caused by contact point drift due to vibration or shaking is avoided. The groove design can maintain reliable connection even if the groove is shaken or vibrated by external influence.

The technical scheme of the embodiment of the application solves the problems that when the lug 1 and the bus bar 2 are mechanically connected, the contact resistance is large and the connection is unreliable.

In addition, due to mechanical connection, when the battery cell 10 is scrapped together with other materials or caused by poor performance, the assembly scheme adopting the connection mode can be repaired normally by disassembling the fastener 4 and the pressing piece 3. For example, when a single battery cell fails, the battery cell with the failure can be quickly disassembled and replaced without scrapping the whole battery pack related to the busbar.

The embodiment of the application adopts a mechanical connection mode, when the cell pole lugs are connected, the cell pole lug connecting structure has the advantages of simple implementation process, reliable effect, detachable rework and the like, and the processing and assembling equipment is low in cost and does not need expensive processing and assembling equipment such as a laser welding machine. And the battery cell scrap caused by unstable welding can be avoided, and the problem that the rework cannot be realized by adopting laser welding is solved.

In some embodiments, the pressing member 3 may apply pressure to the tab 1 by the fastening action of the fastening member 4, so that a portion of the tab 1 enters the groove 21 of the busbar 2 and conforms to the groove 21. For example, the pressing member 3 may be a steel sheet 30 with certain elasticity made of stainless steel or rust-proof carbon steel as shown in fig. 4; the fastener 4 may be a screw or other fastening scheme, which may be a snap fit, for example. When the installation is carried out, the elastic steel sheets 30 press the tab 1 on the busbar and are locked by screws or bolts or other schemes.

In some embodiments, the tab 1 may be provided with a recess, and the recess is adapted to the groove 21 of the bus bar 2. Can suppress the depressed part with recess 21 adaptation in advance on utmost point ear 1, can guarantee utmost point ear 1 and recess 21's laminating degree, reduce the installation degree of difficulty.

In some embodiments, the cross-section of groove 21 may be arcuate or V-shaped. The arc-shaped or V-shaped groove 21 can increase the connection area of the tab 1 and the bus bar 2, and further reduce the connection resistance of the tab 1 and the bus bar 2. The specific shape of the arc or V shape or the shape of the contact surface of the tab and the groove can be further optimized through experiments or simulation experiments, so that the connection resistance of the tab 1 and the bus bar 2 is further reduced.

In some embodiments, as shown in fig. 4, the pressing member 3 may be provided with a protrusion 31 directed to the groove 21, and the protrusion 31 is used to apply a pressing force directed to the groove 21 to the tab 1 under the action of the fastening member 4. The pressure directed to the groove 21 is applied to the tab 1 through the protrusion 31, so that the fitting degree of the tab 1 and the groove 21 is ensured. For example, the pressing member 3 may be an elastic pressing piece, and a partial region of the elastic pressing piece is depressed downward to form the protrusion 31. The protrusion 31 of the elastic pressing sheet can be formed by press molding, and the method is simple and low in cost. Or the elastic pressing sheet is a V-shaped stainless steel elastic sheet, and has the advantages of simple structure and low cost.

In some embodiments, one end of the pressing member 3 may be fixed in the groove 21 by a snap structure, and the other end is fixed by the fastening member 4, so that the number of fastening members used may be reduced, and the assembly efficiency may be improved. For example, as shown in fig. 4, the pressing member 3 is a bar-shaped V-shaped pressing piece. The strip-shaped V-shaped pressing plate 3 can be provided with mounting holes 32 at both ends and fixed by fasteners such as screws. As shown in fig. 6, one end of the strip-shaped V-shaped pressing sheet 3 is fixed by the clamping structure, and the other end is provided with the mounting hole 32 and fixed by the fastening member 4, so that the number of the fastening members 4 can be reduced, and the assembly efficiency can be improved.

The fastener 4 may comprise a screw, for example. At this time, as shown in fig. 3, the bracket 20 and the drainage bar 22 of the busbar 2 are provided with corresponding screw holes 23. The pressing member 3 is provided with a corresponding through hole 32, as shown in fig. 4.

In some embodiments, as shown in fig. 1 and 2, busbar 2 includes busbar mount 20 and drain 22, with groove 21 disposed on drain 22. The drain bar 22 needs to be made of a material with high conductivity, the bus bar support does not need, and the bus bar is designed into the drain bar 22 and the bus bar support 20 for accommodating the drain bar, so that the cost of the bus bar can be reduced, and unnecessary short circuit is avoided.

In some embodiments, a first tab (a left tab 1 in fig. 2) and a second tab (a right tab 1 in fig. 2) are stacked between the pressing member 3 and the bus bar 2, and the first tab and the second tab are respectively connected to two adjacent battery cells 10. At the same tie point, can be connected the utmost point ear 1 and the busbar 2 of two adjacent electric cores 10 simultaneously, reduce the tie point, improve assembly efficiency.

In some embodiments, as shown in fig. 2, the bus bar 2 is provided with tab guiding holes 24 at both sides of the groove 21 for the first and second tabs to pass through. The direction and the position of the tab 1 can be fixed through the tab lead hole 24, so that the tab 1 is orderly arranged and the risk of short circuit between the tab 1 and other parts is reduced.

The above-described connection structure, when assembled, generally comprises the steps of:

the method comprises the following steps: a certain number of cells 10 (as required by the design) are stacked. The number of the battery cells 10 is determined by the design capacity of the product.

Step two: the stent 20 of the drainage bank 22 is designed according to the series requirements. The support 20 may be designed according to the number of cells of each cell string required by the product in the design scheme.

Step three: and (3) bending and fitting the electrode lugs 1 of the battery cell 10 to the drainage bar 22, as shown in fig. 5.

Step four: the pole ear 1 is pressed on the drainage bar 22 by a steel sheet 3 (stainless steel or carbon steel which is processed by rust-proof treatment) with certain elasticity and is locked by a screw or other schemes.

Both ends of this application embodiment all adopt screw locking, in order to improve assembly efficiency, can also unilateral adopt U type draw-in groove, and the other end adopts screw lock to die, or other alternative.

Comparative test

For ease of understanding, some examples using the scheme of the present application and comparative examples without the scheme of the present application for comparison of effects are given below.

Example 1:

busbar 2 includes a bracket 20 and a drain 22. The groove 21 on the drainage row 22 is designed into a circular arc shape, and the corresponding protrusion 31 of the elastic pressing sheet 3 also adopts a circular arc shape. The connection mode of the lug 1 and the bus bar 2 can adopt one side of the lug to be connected by a screw and the other side of the lug to be connected by a U-shaped clamping groove.

As shown in fig. 7, one end of the drainage bar 22 is connected to a T-shaped screw 25 by a press riveting process, and the other end is connected to a nut in the mounting hole by a press riveting process, i.e. a threaded hole 23 is formed. As shown in fig. 8, one end of the elastic pressing piece 30 is provided with a through hole 32, and the other end is provided with a U-shaped slot 33.

As shown in figure 8, during assembly, the U-shaped clamping groove 33 is clamped on the T-shaped screw 25, then the T-shaped screw is pressed down by using an air cylinder or other tools, the elastic pressing sheet is loaded, the drainage bar 22 is pressed flat, and then the screw is locked

Example 2:

the grooves on the drainage bar 22 in the embodiment of the present application are designed in the shape of a circular arc, and the corresponding elastic pressing pieces 30 are also designed in the shape of a circular arc. The difference from the embodiment 1 is that the connection mode of the tab 1 and the bus bar 2 adopts a double-sided screw connection.

Two ends of the drainage bar 22 are respectively connected with a nut in the mounting hole by adopting a press riveting process. The U-shaped end belt of the elastic pressing sheet is designed to be bent. During assembly, the elastic pressing sheet is horizontally placed, screws are placed at two ends of the elastic pressing sheet, and the elastic pressing sheet is locked in a balanced mode.

Example 3:

the groove on drainage row 22 of this application embodiment adopts the V-arrangement design, and the elasticity preforming that corresponds also adopts the V-arrangement, and the angle of V type can adopt 45 degrees to 135 degrees, can carry out angle optimization according to the angle of different electric core models adjustment V types, makes the connection of utmost point ear and busbar reach best joint strength and minimum connecting resistance.

The connection mode of utmost point ear and busbar of this application embodiment can adopt unilateral screwed connection, and another side U type draw-in groove connects. One end of the drainage bar 22 is connected with a T-shaped screw by adopting a press riveting process, and the other end is connected with a nut in the mounting hole by adopting a press riveting process. The U-shaped end belt of the elastic pressing sheet is designed to be bent.

During assembly, the U-shaped groove is clamped on the T-shaped nut, the elastic pressing sheet is loaded by using an air cylinder or other tools, the drainage bar 22 is pressed flatly, and screws are locked.

Example 4:

the groove on drainage row 22 of this application embodiment adopts the V-arrangement design, and the elasticity preforming that corresponds also adopts the V-arrangement, and the angle of V type can adopt 45 degrees to 135 degrees, can be according to different electric core model angle of adjustment, makes it reach best joint strength and minimum connecting resistance.

The connection mode of the embodiment of the application can adopt bilateral screw connection. Two ends of the drainage bar 22 are respectively connected with a nut by adopting a press riveting process. The U-shaped end belt of the elastic pressing sheet is designed to be bent.

The elastic pressing sheet is horizontally placed, screws are placed at two ends of the elastic pressing sheet, and the elastic pressing sheet is locked in a balanced mode.

Comparative example 1:

both the drainage bar 22 and the resilient sheeting are of a slotless design.

The experimental results are as follows:

1. the comparative example adopting the slotless design has the advantages that the installation strength of the lug and the bus bar can not meet the requirement, the position of the lug is changed in the vibration process, and the test drawing force is far smaller than the design scheme of the grooves in the examples 1 to 4.

2. The connection resistance of the comparative example using the non-grooved design was greater than that of the grooved examples 1-4 and was unstable, and there was an unreliable factor in the comparative example connection in view of the flatness of the fitting at the connection of the comparative example.

Comparative example 2:

the pole ear is connected with the bus bar by an elastic clip.

The experimental results are as follows: the elastic clamp needs to be provided with a barb for preventing loosening, when other accessories have quality problems, the assembly mode is irreversible, the joint scrapping is easily caused as welding, and the cost is increased.

The embodiment of the application also provides an electrochemical device, which comprises a plurality of battery cells and a connection structure of the tab and the bus bar of any one of the battery cells. The electrochemical device of the embodiment of the application has the technical effects of reliable connection, reworking, low cost and the like which are described above due to the adoption of the connection structure, and the details are not repeated herein.

The use of the electrochemical device of the embodiment of the present application is not particularly limited, and it may be used for any electronic device known in the art. In some embodiments, the electrochemical device of the present application can be used in, but is not limited to, notebook computers, pen-input computers, mobile computers, electronic book players, cellular phones, portable facsimile machines, portable copiers, portable printers, headphones, video recorders, liquid crystal televisions, portable cleaners, portable CDs, mini-discs, transceivers, electronic organizers, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, mopeds, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, household large batteries, lithium ion capacitors, and the like.

Although the application has been shown and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art based upon a reading and understanding of this specification and the annexed drawings. This application is intended to embrace all such modifications and variations and is limited only by the scope of the appended claims.

That is, the above description is only an embodiment of the present application, and not intended to limit the scope of the present application, and all equivalent structures or equivalent flow transformations made by using the contents of the specification and the drawings, such as mutual combination of technical features between various embodiments, or direct or indirect application to other related technical fields, are included in the scope of the present application.

In addition, in the description of the present application, it is to be understood that the terms "two ends", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.

In addition, structural elements having the same or similar characteristics may be identified by the same or different reference numerals. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

In this application, the words "in some embodiments," exemplary, "and the like are used to mean" serving as an example, instance, or illustration. Any embodiment described in this application is not necessarily to be construed as preferred or advantageous over other embodiments. The previous description is provided to enable any person skilled in the art to make and use the present application. In the foregoing description, various details have been set forth for the purpose of explanation. It will be apparent to one of ordinary skill in the art that the present application may be practiced without these specific details. In other instances, well-known structures and processes are not shown in detail to avoid obscuring the description of the present application with unnecessary detail. Thus, the present application is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

Claims

1. A connection structure of a tab and a bus bar, comprising:

the groove is arranged on the bus bar;

the pressing piece is used for pressing one part of the tab in the groove of the bus bar and is attached to the groove; and

and the fastening piece is used for fixing the lug, the pressing piece and the bus bar together.

2. The connection structure according to claim 1, wherein the grooves extend in a width direction of the tab.

3. The connection structure according to claim 1, wherein the groove has an arc-shaped or V-shaped cross section.

4. The connection structure according to claim 1, wherein a recess is provided on the tab, the recess fitting into a groove of the busbar.

5. The connection structure according to claim 1, wherein the pressing member is provided with a protrusion directed toward the groove, the protrusion being configured to apply a pressing force directed toward the groove to the tab under the action of the fastener.

6. The connecting structure according to claim 5, wherein the pressing member is an elastic pressing piece, a partial region of the elastic pressing piece is depressed downward to form the protrusion, or the elastic pressing piece is a V-shaped stainless steel elastic piece.

7. The connecting structure according to any one of claims 1 to 6, wherein the pressing member is a strip-shaped V-shaped pressing piece, one end of the pressing member is fixed in the groove through a clamping structure, and the other end of the pressing member is fixed through the fastener.

8. The electrochemical device according to any one of claims 1 to 6, wherein said busbar comprises a busbar support and a drain, said groove being provided on said drain.

9. The connecting structure according to any one of claims 1 to 6, wherein the fastening member comprises a screw, the bracket and the drainage bar of the busbar are provided with corresponding threaded holes, and the pressing member is provided with corresponding through holes.

10. The connection structure according to claim 1, wherein a first tab and a second tab are stacked between the pressing member and the busbar, and the first tab and the second tab are connected to two adjacent battery cells respectively.

11. The connection structure according to claim 10, wherein the bus bar is provided with tab lead holes at both sides of the groove for the first tab and the second tab to pass through.

12. An electrochemical device comprising a plurality of cells and the tab-to-busbar connection structure according to any one of claims 1 to 11.

13. An electrical device comprising the electrochemical device of claim 12 and a load, the electrochemical device being configured to provide power to the load.