CN116722321A

CN116722321A - Electrode assembly, battery cell, assembly method of battery cell, battery pack and power utilization device

Info

Publication number: CN116722321A
Application number: CN202311002441.0A
Authority: CN
Inventors: 陈锦华; 杨国众; 杨攀; 张伟; 余迎祥
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2023-08-10
Filing date: 2023-08-10
Publication date: 2023-09-08

Abstract

The application relates to the technical field of batteries, and discloses an electrode assembly, a battery cell, an assembly method of the battery cell, a battery pack and an electric device. The electrode assembly comprises a pole piece and at least two lugs protruding from the pole piece and arranged in a mutually laminated mode. Each tab comprises a to-be-bent section and a fixed section which are sequentially connected, wherein the to-be-bent section is connected between the fixed section and the pole piece, the fixed section is used for connecting a conductive piece, and the to-be-bent section is bent relative to the fixed section; the connecting area is arranged in the to-be-bent section, and all the to-be-bent sections of the tabs are fixedly connected in the connecting area. The electrode assembly provided by the application can prevent the bent tab from being inserted into the battery core main body after being forked. The battery pack provided by the application is used for providing electric energy.

Description

Electrode assembly, battery cell, assembly method of battery cell, battery pack and power utilization device

Technical Field

The application relates to the technical field of batteries, in particular to an electrode assembly, a battery cell, an assembling method of the battery cell, a battery pack and an electric device.

Background

New energy batteries are increasingly used in life and industry, for example, mobile phones, notebooks and miniaturized wearable devices which are small enough to carry batteries, and new energy automobiles which are large enough to carry battery packs are widely used; in addition, batteries are increasingly used in the field of energy storage and the like.

Typically, the battery pack includes a battery cell including an electrode assembly. The electrode assembly is mainly formed by winding or laminating a positive electrode plate and a negative electrode plate, and the electrode plate is connected with a tab, so that a plurality of layers of tabs are formed in the multilayer winding or laminating. When the battery cell is inserted into the shell and the tab is bent, the root part of the tab is loose, and the tab is easily bifurcated when the tab is further folded and then is inserted into the battery cell main body, so that the safety performance of the battery is seriously affected.

Disclosure of Invention

The application provides an electrode assembly, a battery cell, an assembling method thereof, a battery pack and an electric device, which can prevent bent tabs from being forked and then inserted into a battery core main body, so as to improve the safety performance of a battery.

The application is realized by the following technical scheme.

A first aspect of the present application provides an electrode assembly comprising: the pole piece and at least two pole lugs are protruded from the pole piece and are mutually overlapped; each tab comprises a to-be-bent section and a fixed section, the to-be-bent section is connected between the fixed section and the pole piece, the fixed section is used for connecting a conductive piece, and the to-be-bent section is bent relative to the fixed section; the connecting area is arranged in the to-be-bent section, and all the to-be-bent sections of the tabs are fixedly connected in the connecting area.

In the above technical scheme, because the connecting area is arranged in the to-be-bent section, the to-be-bent sections of all lugs arranged in a stacking way are fixedly connected at the connecting area, so that at least two lugs which are easy to loosen and originally arranged in a stacking way are fastened and connected into a compacter and laminated whole at the connecting area, namely, the at least two lugs are restrained into a difficultly loosened whole after being folded in the connecting area of the to-be-bent section, the possibility that the to-be-bent sections of the at least two lugs are inserted into the battery core main body is reduced after the to-be-bent sections are bent due to the branching of the lugs, and the improvement of the safety performance of the battery is realized.

In one possible embodiment of the application, the connection region starts at one fifth of the section to be bent and ends at four fifth of the section to be bent in the direction of the conductive element toward the pole piece.

After the fixing section of the tab is connected with the conductive piece and is bent into the shell, the position where bifurcation is easy to occur is in the area from one fifth of the to-be-bent section to four fifth of the to-be-bent section, namely the area is the easy-bifurcation area of the tab, so that the problem of inserting the tab under bifurcation can be prevented by arranging the connection area.

In one possible embodiment of the application, the connection region starts at one third of the section to be bent and ends at two thirds of the section to be bent.

As the range of the connection region is further narrowed, at least two tabs can be further fixed at the position of the region where the tabs are relatively more likely to diverge.

In one possible embodiment of the application, the ratio of the area of the connecting region to the area of the section to be bent is 0.1 to 0.3.

The ratio of the area of the connecting area to the area of the section to be bent is 0.1-0.3, so that the connecting area can occupy a reasonable area on the section to be bent, and the reliability of connection between the lugs can be improved.

In one possible implementation manner of the application, in a state that the fixed section is connected with the conductive piece, the to-be-bent section of each tab forms a first bending part and a second bending part which are connected end to end, the first bending part is connected with the fixed section, and the second bending part is connected with the pole piece; the bending concave part of the first bending part faces the thickness direction of the pole piece, and the bending concave part of the second bending part faces the opposite direction of the bending concave part of the first bending part; the connecting area is located in an area between the bending center line of the first bending part and the bending center line of the second bending part, wherein the area between the bending center line of the first bending part and the bending center line of the second bending part comprises the bending center line of the first bending part and the bending center line of the first bending part.

Because the electrode assembly needs to be put into the shell under the state that the fixed section is connected with the conductive piece, the to-be-bent section of each tab is bent to form a first bending part and a second bending part which are connected end to end, the connecting area is selected in an area between the bending center line of the first bending part and the bending center line of the second bending part, the connecting area comprises the bending center line of the first bending part and the bending center line of the second bending part, the connecting area is generally positioned in the middle area between the fixed section of the tab and the tab, namely, the area where the laminated tab is easy to be forked, and the connecting area is arranged, so that the problem that at least two laminated tabs are forked at the point to cause downward insertion can be avoided as much as possible.

In one possible implementation of the present application, the connection region is located in a region between a connection of the first bending portion and the second bending portion and a bending center line of the second bending portion, wherein the region between the connection and the bending center line of the second bending portion includes the connection and the bending center line of the second bending portion.

As the extent of the connection region is further limited, it may be further possible to fix at least two tabs at a position where the tabs are relatively more bifurcated.

In one possible embodiment of the application, the connection region is arranged on the bending centre line of the second bending part.

The connecting area is further limited on the bending central line of the second bending part, and the central line of the second bending part, namely the position area where the tab is most easy to branch, can solve the problem that the tab is easy to branch to the greatest extent.

In one possible implementation manner of the application, the section to be bent is bent to form a third bending part, one end of the third bending part is connected with the fixed section, and the other end of the third bending part is connected with the pole piece; the bending concave part of the third bending part faces the thickness direction of the pole piece.

Because only one third bending section exists in the to-be-bent section in the connection state of the fixing section and the conductive piece, the position where the tab is easy to be branched is in the central position area of the bending concave part close to the third bending section, and the area is the easy-to-be-branched area of the tab, and therefore the problem of branching and inserting of the sub-tab can be prevented to a great extent by the connection area.

In one possible embodiment of the application, the connection region is arranged on the bending centre line of the third bending part.

The connecting area is further limited on the bending central line of the third bending part, namely the position area where the tab is most easy to branch, so that the problem that the sub-tab is easy to branch can be solved to the greatest extent.

In one possible implementation of the application, the tabs are arranged at one end in the length direction of the pole piece, all the tabs being connected through-going in the width direction of the pole piece.

As all the lugs are connected in the connecting area in a through way along the width direction of the pole piece, compared with the discontinuous connecting area formed by discontinuous connection, the through type connecting mode is more compact and reliable, and the sub-lugs can be prevented from being forked at the position to a greater extent.

In one possible implementation manner of the application, the tab is arranged at one end of the pole piece along the length direction, and at least two connection points which are distributed at intervals along the width direction of the pole piece are arranged in the connection area.

Due to the mode that the connection areas are distributed at intervals, connection materials are saved, meanwhile, the operation space is narrow when at least two laminated lugs are fixedly connected in the connection areas, and the operation is simple and easy to implement when the connection areas are distributed at intervals.

In one possible embodiment of the application, all tabs in the connection region are welded.

The welding and fixing mode has the advantages of high connection reliability and good conductivity after connection.

In one possible embodiment of the application, all the tabs in the connection region are adhesively secured.

The fixing mode of bonding is adopted, so that the operation is easy, and the connection efficiency is high.

A second aspect of the present application provides a battery cell including the electrode assembly provided in any one of the first aspects, a case, and a conductive member. Wherein the case has an opening, and the electrode assembly is accommodated in the case; the conductive member is connected with the fixed section.

Because the electrode assembly that this battery monomer includes is provided with the connecting region at the section of waiting to buckle of two at least utmost point ears, the section of waiting to buckle of all utmost point ears is at connecting region fixed connection to have the advantage that can prevent to insert down in the electric core main part after the utmost point ear bifurcation after bending.

A third aspect of an embodiment of the present application provides a battery pack, including a plurality of battery cells provided in any one of the second aspects and a case, in which the plurality of battery cells are accommodated.

Because this battery package includes among the battery cell's the electrode assembly, the connection region that the section that waits to buckle of utmost point ear set up is arranged in waiting to buckle the section fixed connection with all utmost point ears, consequently have the advantage that can prevent to insert down in the electric core main part after the utmost point ear bifurcation after bending.

A fourth aspect of an embodiment of the present application provides an electrical device comprising a battery pack provided in any one of the above third aspects for providing electrical energy.

Because the battery monomer in the battery pack that this power consumption device included has the connection region that waits to buckle the section setting with utmost point ear fixed connection at the utmost point ear, consequently, power consumption device has the advantage that can prevent to insert down in the electric core main part after the utmost point ear bifurcation after bending.

The fifth aspect of the embodiment of the present application provides an assembling method for assembling a battery unit, where each tab of the battery unit includes a section to be bent and a fixing section, and a connection area is disposed in the section to be bent, and the method includes the following steps: the fixed section is welded with the conductive piece; and welding the to-be-bent sections of all the tabs in the connecting area.

In the assembly method of the battery cell, after the fixing section is welded with the conductive piece, the method of welding the to-be-bent sections of all the tabs in the connecting area of the to-be-bent sections of the tabs is adopted, so that at least two tabs can be restrained into a whole which is not easy to loose after being folded in the connecting area of the to-be-bent sections, and the tabs are prevented from being bifurcated and inserted into the battery cell main body.

In one possible implementation of the application, the welding is ultrasonic welding.

Because the ultrasonic welding is adopted, the metal surfaces of the adjacent lugs can be closely contacted to achieve the combination between atoms, so that higher melting strength is achieved, the welding speed is high, and the welding process has no risk of spark and melting stock contacting the inside of the battery cell.

Drawings

Features, advantages, and technical effects of exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of a part of a battery cell assembly according to some embodiments of the present application;

FIG. 2 is a schematic view of a partial enlarged structure at A in FIG. 1 according to some embodiments of the present application;

FIG. 3 is an enlarged view of the right tab and surrounding components of FIG. 2 according to some embodiments of the present application;

fig. 4 is a front view of a portion of a battery cell assembly according to some embodiments of the present application;

fig. 5 is a top view of a portion of a battery cell assembly according to some embodiments of the present application;

fig. 6 is a side view of a portion of a battery cell assembly according to some embodiments of the present application;

fig. 7 is a top view of a portion of a battery cell assembly with tab structures disposed on only one side according to some embodiments of the present application;

fig. 8 is an electronic computer tomography schematic diagram of a multi-layer tab after being folded under the condition that a connecting area is not provided in a to-be-folded section of the multi-layer tab according to some embodiments of the present application;

fig. 9 is an electronic computer tomography schematic diagram of a multi-layer tab after being folded under the condition that a connecting area is provided at a to-be-folded section in the multi-layer tab according to some embodiments of the present application;

FIG. 10 is a schematic cross-sectional view of a welding head during welding of a multi-layered tab according to some embodiments of the present application;

fig. 11 is a flowchart illustrating an assembling method of a battery cell according to some embodiments of the present application.

Reference numerals:

1-a cell body; a 2-electrode assembly; 21-electrode lugs; 211-a fixed section; 212-a section to be bent; 213-connection point; 2121-first bend; 2122-second bend; 3-conductive members; d-junction region; d1-a fifth of the starting position of the section to be bent; d2-four fifth of the end position of the section to be bent; d3-a third of the section to be bent is positioned at the initial position; d4-two-thirds of the end position of the segment to be bent.

Detailed Description

Embodiments of the technical scheme of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present application, and thus are merely examples, and are not intended to limit the scope of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having" and any variations thereof in the description of the application and in the description of the drawings above are intended to cover non-exclusive inclusions.

In the description of embodiments of the present application, the technical terms "first," "second," "third," etc. are used merely to distinguish between different objects and should not be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, a particular order or a primary or secondary relationship. In the description of the embodiments of the present application, the meaning of "plurality" is two or more unless explicitly defined otherwise.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

In the description of the embodiments of the present application, the term "and/or" is merely an association relationship describing an association object, and indicates that three relationships may exist, for example, a and/or B may indicate: a exists alone, A and B exist together, and B exists alone. In this context, the character "/" generally indicates that the associated object is an "or" relationship.

In the description of the embodiments of the present application, the orientation or positional relationship indicated by the technical terms "length", "width", "thickness", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "circumferential", etc. are orientation or positional relationship based on the drawings, and are merely for convenience of describing the embodiments of the present application and for simplifying the description, and are not intended to indicate or imply that the apparatus or element in question must have a specific orientation, be constructed, operated, or used in a specific orientation, and thus should not be construed as limiting the embodiments of the present application.

In the description of the embodiments of the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured" and the like should be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally formed; or may be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to specific circumstances.

The term "parallel" in the present application includes not only the case of absolute parallelism but also the case of substantially parallelism as is conventionally recognized in engineering; meanwhile, "vertical" includes not only the case of absolute vertical but also the case of substantially vertical as conventionally recognized in engineering.

The present application will be described in detail below.

In the present application, the battery cell may include a lithium ion battery cell, a lithium sulfur battery cell, a sodium lithium ion battery cell, a sodium ion battery cell, or a magnesium ion battery cell, which is not limited in the embodiment of the present application.

The battery unit comprises an electrode assembly and electrolyte, wherein the electrode assembly comprises a positive electrode plate, a negative electrode plate and a separation film. The battery cell mainly relies on metal ions to move between the positive pole piece and the negative pole piece to work.

In addition, the electrode assembly may be a roll-to-roll structure or a laminate structure.

The inventors of the present application have noted that, for a general battery cell, for example, in an electrode assembly of a laminated structure, it is necessary to laminate at least two electrode tabs after punching positive and negative electrode tabs with molds, respectively, before stacking with a separator, and laminate the tabs of at least two electrode tabs in the thickness direction of the electrode tabs to form tabs for inputting or outputting electric power. Or for the electrode assembly with the winding structure, one pole piece can be provided with at least two pole lugs, and the pole pieces can be laminated to form a plurality of layers of pole lugs after winding and forming. In addition, to facilitate connection of the tab and the end cap assembly, the tab is typically of a relatively long length. However, when at least two tabs are stacked together, the root parts of the tabs are loose, and the tabs are easily split when being further bent into the shell, so that the problem that the battery is inserted into the battery core main body under the tabs occurs, and the battery has a large potential safety hazard in the later use process. Therefore, how to insert the battery cell body under the tab bifurcation after the electrode assembly is put into the case is an important issue for improving the safety performance of the battery.

The inventor of the present application has found through researches, for example, referring to fig. 8, fig. 8 is a cross-sectional scan of a multi-layer sub-tab 21 after being put into a case in a case where a connection region D is not provided in a to-be-bent section 212 of the multi-layer tab 21, and it is apparent from fig. 8 that, after the multi-layer tab 21 is bent, a part of the tabs 21 in all the to-be-bent sections 212 are inserted into the cell main body 1 under branching, and the to-be-bent sections 212 of the other part of the non-branched tabs 21 form a bending section having an S shape, and the problem of inserting the tabs 21 under the non-branching tab 21 does not occur. Therefore, the problem of inserting the battery cell main body after the tab 21 is bifurcated can be solved by preventing the tab 21 from being bifurcated, for example, the bifurcated multi-layer tab 21 can be fixedly connected together, but because the tab 21 extends out of the battery cell main body 1, if a proper connection position is not considered to be found, for example, if the connection position is set at a position very close to the connection position of the tab 21 and the end cover, or the connection position is set at a position close to the pole piece from the tab 21, the problem of bifurcation of the tab 21 can not be necessarily solved. Therefore, it is necessary to find an appropriate connection position to ensure that the problem of the bifurcation of the tab 21 can be solved. Through research and finding and can be seen from fig. 8, the portion easy to be bifurcated occurs at the portion between the fixing section 211 and the root of the tab 21 on the tab 21, that is, in the tab folding space of the tab 21 (the portion where the tab is connected with the end cover and the connection position of the tab and the pole piece are removed), by setting the connection area D, at least two loose tabs 21 are fixedly connected, which are stacked, so that a plurality of tabs 21 can be effectively prevented from being inserted into the battery core main body 1 under bifurcation in the tab folding space.

Based on such design concept, the embodiment of the application provides an electrode assembly, wherein a connection region D is arranged in a tab folding space, namely in a to-be-bent section 212 of a tab 21, and the to-be-bent sections 212 of at least two tabs 21 are fixedly connected in the connection region D, so as to prevent the tab 21 from being inserted into a cell main body 1 due to the bifurcation of the multiple layers of tabs 21.

The battery cell provided by the embodiment of the application can be used in an energy storage power supply system, a vehicle, a ship or an aircraft and other electric devices without limitation. In some embodiments, the battery cell may include a housing. The case is used to encapsulate the electrode assembly, the electrolyte, and the like.

The battery monomer provided by the embodiment of the application can prevent the tab from being inserted into the battery core main body due to the bifurcation of the multi-layer tab, so that the battery monomer has higher safety performance. And the use reliability of the energy storage power supply system and the power utilization device can be improved.

The battery monomer provided by the embodiment of the application can be used as a battery pack in groups. The battery pack can also be used in, but not limited to, energy storage power systems, vehicles, boats or aircraft, and other electrical devices.

The technical scheme described by the embodiment of the application is suitable for the electric device of the battery or the battery pack for providing electric energy. The electric device may be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, or the like. The vehicle can be a fuel oil vehicle, a fuel gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or a range-extended vehicle and the like. The embodiment of the application does not limit the electric device in particular.

In the following embodiments, for convenience of explanation, the electric device according to the embodiments of the present application is taken as a portable electric device for illustration. The following description refers to the accompanying drawings.

Fig. 1 to 7 are schematic structural diagrams and partial enlarged structural diagrams of a part of components of a battery cell according to an embodiment of the present application under different viewing angles.

The embodiment of the application provides an electrode assembly, as shown in fig. 1 and 2, the electrode assembly 2 comprises a pole piece and at least two pole lugs 21 protruding from the pole piece and stacked with each other. Each tab 21 includes a to-be-bent section 212 and a fixing section 211, the to-be-bent section 212 is connected between the fixing section 211 and the pole piece, and referring to fig. 8 and 9, the fixing section 211 is used for connecting the conductive member 3, and the to-be-bent section 212 is bent relative to the fixing section 211; a connection area D is provided in the to-be-bent section 212, and all to-be-bent sections 212 of the tabs 21 are fixedly connected in the connection area D.

The electrode sheet in the embodiment of the application can be one and can be used as a positive electrode sheet or a negative electrode sheet in an electrode assembly with a winding structure, and at least two tabs 21 which are arranged in a stacked manner can be formed by winding the positive electrode sheet or the negative electrode sheet. The electrode sheet may also be a sheet comprising at least two positive electrode sheets or at least two negative electrode sheets or a combination of at least two positive electrode sheets and at least two negative electrode sheets, and may be used as a sheet of a laminated electrode assembly. In the embodiment of the present application, the electrode sheet and the separator (not shown) of the electrode assembly 2 are disposed in the cell body 1 in fig. 1, 2 and 3, where the cell body 1 refers to a part of the assembly of the battery cell, and for example, the cell body 1 may specifically be a body having the electrolyte and the electrode assembly 2 disposed therein and the package outside, and may be used as a body portion of the battery cell.

The battery core main body 1 in the embodiment of the application can be a winding type battery core or a laminated type battery core, and at least two electrode lugs 21 are arranged on the electrode plate of the battery core main body 1. In the winding type battery core, the battery core main body 1 may include a continuous positive plate and a continuous negative plate, and the positive plate is taken as an example, and each circle wound by the positive plate may have one positive tab, or each half circle wound by the positive plate may have one positive tab, and at least two stacked positive tabs may be aligned in at least two circles wound by the positive plate. In the laminated battery cell, at least two mutually overlapped positive plates and at least two mutually overlapped negative plates can be arranged in the battery cell main body 1, each positive plate is provided with a positive lug, each negative plate is provided with a negative lug, the positive lugs on all the positive plates can be aligned and laminated to form laminated positive lugs, and the negative lugs on all the negative plates can be aligned and laminated to form laminated negative lugs.

The tab 21 in the embodiment of the application includes a positive tab and a negative tab 21, for example, the tab 21 on the positive plate is a positive tab, and the tab 21 on the negative plate is a negative tab.

In the embodiment of the present application, each tab 21 is formed by stacking each other. For example, at least two positive electrode lugs 21 at the same end of the pole piece are stacked in a direction perpendicular to the plane of the pole piece to form a plurality of layers of positive electrode lugs 21. For another example, at least two negative electrode tabs 21 at the same end of the pole piece are stacked in a direction perpendicular to the plane of the pole piece to form a multi-layer negative electrode tab 21.

In addition, in the embodiment of the present application, fig. 1 and 2 include at least two tabs 21 stacked together, and fig. 1 and 2 only show the overall external profile of the multi-layer tab 21 and a smaller number of stacked tabs 21, and the external profile of the multi-layer tab 21 has at least two tabs 21 stacked together, but for convenience of illustration, all tabs 21 are not shown.

In the embodiment of the present application, the fixing section 211 of the tab 21 refers to a portion of the tab 21 for electrically connecting with the conductive member 3 of the battery cell, and the fixing section 211 may be flat so as to facilitate the bonding connection of the conductive member 3. In addition, here, the conductive member 3 may refer to a tab of a battery cell. The to-be-bent section 212 on the tab 21 refers to a portion of the tab 21 between the connection point of the tab 21 and the pole piece and the connection point of the to-be-bent section 212 facing the connection point of the fixing section 211, that is, a bent section formed by the to-be-bent section 212 after the electrode assembly 2 is put into the casing, which may also be referred to as a tab bending region, except for the fixing section 211 for connecting with the conductive member 3.

The manner of fixing and connecting the to-be-bent sections 212 of all the tabs 21 stacked in the embodiment of the present application is not limited, and for example, all the to-be-bent sections 212 of the tabs 21 may be fixed and connected by welding or bonding.

Through being provided with connecting region D in waiting to buckle section 212, can be in connecting region D department with the section 212 fixed connection of waiting to buckle of the utmost point ear 21 of all range upon range of settings, so make originally range upon range of a plurality of easy loose utmost point ears 21 of setting in connecting region D fastening connection become a compacter laminating whole, be equivalent to with utmost point ear 21 in waiting to buckle section 212 connecting region D draw in the back and retrain into a difficult loose whole, reducible at least two utmost point ears 21 wait to buckle section 212 after being bent like this, appear its possibility of inserting to electric core main part 1 inside because of utmost point ear 21 bifurcation down to promote the security performance of battery.

In an embodiment, with reference to fig. 8 and 9, in the direction along the conductive element 3 towards the pole piece, and with reference to fig. 3, the connection zone D starts at one fifth of the section to be bent 212 and ends at four fifths of the section to be bent 212.

In the embodiment of the present application, referring to fig. 3, fig. 3 is an enlarged schematic view of the right tab 21 and surrounding components in fig. 2. In fig. 3, the starting position D1 of the connecting region D in the direction of the conductive element 3 toward the pole piece is one fifth of the length of the to-be-bent segment 212, and here, the starting position D1 of the to-be-bent segment 212 in one fifth of the length of the to-be-bent segment 212 in the extending direction of the to-be-bent segment 212 can also be understood as the distance from the to-be-bent segment 212 to the connection of the to-be-bent segment 212 and the fixing segment 211. The end position D2 of the connection region D at four fifths of the length of the to-be-bent section 212 in the direction of the conductive member 3 toward the pole piece can also be understood as the position of the to-be-bent section 212 at which the distance from the to-be-bent section 212 to the connection point of the fixing section 211 is four fifths of the length of the to-be-bent section 212 in the extending direction. The connection region D may be located in the region between the fifth start position D1 of the section to be bent 212 and the fifth end position D2 of the section to be bent 212 in fig. 3, such as the connection region D shown in fig. 3, that is, the region between the fifth start position D1 of the section to be bent 212 and the fifth end position D2 of the section to be bent 212.

In the above embodiment, after the fixing section 211 of the tab 21 is connected to the conductive member 3 and is bent into the shell, the position where the bifurcation is likely to occur is in the area from the fifth starting position D1 of the to-be-bent section 212 to the fourth ending position D2 of the to-be-bent section 212, that is, the area is the bifurcation-prone area of the tab 21, so the problem of inserting the tab 21 under the bifurcation can be prevented by setting the connection area D.

Further, in one embodiment, referring to FIG. 3, the connection region D begins at one third of the section to be bent 212 and ends at two thirds of the section to be bent 212.

In the embodiment of the present application, referring to fig. 3, in the direction of the conductive member 3 toward the pole piece, the starting position of the connection region D at one third of the to-be-bent section 212 is D3, and in the direction of the conductive member 3 toward the pole piece, the ending position of the connection region D at two thirds of the to-be-bent section 212 is D4. In fig. 3, the connection region D may be located in a region between the third start position D3 of the section to be bent 212 and the second-third end position D4 of the section to be bent 212, wherein a region between the third start position D3 of the section to be bent 212 and the second-third end position D4 of the section to be bent 212 falls in a region between the fifth start position D1 of the section to be bent 212 and the fourth-fifth end position D2 of the section to be bent 212, i.e. the setting range of the connection region D is further narrowed.

In this way, the range of the connection region D can be further limited to be narrowed, and at least two tabs 21 can be fixed as much as possible at the region position where the tabs 21 are relatively more likely to diverge.

In an embodiment, referring to fig. 1 and 3, the ratio of the area of the connection region D to the area of the to-be-bent section 212 is 0.1-0.3.

In the above embodiment, since the ratio of the area of the connection region D to the area of the to-be-bent section 212 is 0.1-0.3, the connection reliability of the connection between the tabs 21 can be improved when the connection region D occupies a reasonable area on the to-be-bent section 212.

In some embodiments, referring to fig. 3 and fig. 9, fig. 3 is an enlarged schematic structural view of the right tab 21 and surrounding components thereof in fig. 2, and fig. 9 is an electronic computer tomography schematic view after the multi-layer tab 21 is folded into the shell in the case that the to-be-folded section 212 in the multi-layer tab 21 is provided with the connection region D. As shown in fig. 9, after the fixing section 211 is connected to the conductive member 3, the to-be-bent section 212 of each tab 21 forms a first bending portion 2121 and a second bending portion 2122 that are connected end to end, one end of the first bending portion 2121 away from the second bending portion 2122 is connected to the fixing section 211, and the second bending portion 2122 is connected to the fixing section 211; the second bending part 2122 is connected with the pole piece; the bending concave portion of the first bending portion 2121 faces the thickness direction of the pole piece, and the bending concave portion of the second bending portion 2122 faces the bending concave portion of the first bending portion 2121 in the opposite direction; the connection region D is located in a region between the bending center line of the first bending part 2121 and the bending center line of the second bending part 2122, wherein the region between the bending center line of the first bending part 2121 and the bending center line of the second bending part 2122 includes the bending center line of the first bending part 2121 and the bending center line of the first bending part 2121.

In the embodiment of the application, the pole piece has a length direction and a width direction which are perpendicular to each other, the tab 21 is arranged at one end of the pole piece along the length direction, and the bending center line of the first bending part 2121 and the bending center line of the second bending part 2122 are parallel to the width direction of the pole piece; the side of the fixing section 211 connected to the first bending portion 2121 is a first side of the fixing section 211, the side opposite to the first side is a second side, the first direction is perpendicular to the plane of the pole piece, and the first direction is directed from the second side to the first side.

In the embodiment of the present application, referring to fig. 1 and 2, for convenience of explanation, the thickness direction of the pole piece is the X direction, and the width direction of the pole piece is the Y direction, and the length direction of the pole piece is the Z direction, among the length direction and the width direction of the pole piece that are perpendicular to each other.

The fixing sections 211 of at least two tabs 21 in the embodiment of the present application may be fixed together by ultrasonic welding, and the fixing sections 211 of at least two tabs 21 are used for connecting with the conductive member 3 and then converging.

In the embodiment of the present application, after the fixing section 211 is connected to the conductive member 3, for example, the fixing section 211 of each tab 21 may be first formed into a plurality of stacked planes, and then the fixing section 211 and the conductive member 3 are welded or bonded together to make the positive electrode sheet or the negative electrode sheet converge; because the tab 21 is located at the opening side of the battery cell casing, to avoid the risk of short circuit caused by contact between the tab 21 and the casing of the battery cell due to oscillation in the later stage of production, transportation and use of the battery cell after being put into the casing, the tab 21 needs to be bent before being put into the casing, so that the battery cell, the end plate and the like can be smoothly installed in the casing. In the process of bending the tab 21, the tab 21 may exhibit various bending modes due to different factors such as the setting position of the tab 21, the internal space of the housing, and the instant stress during bending.

For example, referring to fig. 2, in fig. 2, the multilayer tab 21 protruding from the left side of the battery core main body 1 and the multilayer tab 21 protruding from the right side of the battery core main body 1 are both located at opposite side edges along one end of the battery core main body 1 in the Z direction, that is, the connection position of the tab 21 is not located in the middle of the battery core main body 1, at this time, the tab 21 located at the edge of the battery core main body 1 needs to be pulled towards the middle of the battery core main body 1, and in the process of pulling the tab 21 towards the middle, a phenomenon that the tab 21 is bent towards the middle away from the battery core main body 1 occurs, that is, the to-be-bent section 212 of the tab 21 is bent reversely, so that the to-be-bent section 212 of the tab 21 after being received into the case may form a single bending curve, for example, the to-be-bent section of the tab 21 is approximately C-shaped or reversely C-shaped, as shown in fig. 2; or the to-be-bent section 212 of the tab 21 after being put into the shell may form two continuous bending curves, referring to the multilayer tab 21 on the right side in fig. 2 and the tab 21 after being put into the shell in fig. 8, the to-be-bent section 212 of the tab 21 is approximately S-shaped or Z-shaped.

The following describes in detail the two modes of forming the section to be bent 212 in the state that the fixing section 211 is connected to the conductive member 3, taking the section to be bent 212 having an approximate C shape or an approximate S shape as an example.

In fig. 9, a cross-sectional view of a multilayer tab 21 after attachment of a fixed segment 211 to a conductive member 3, i.e., after insertion of an electrode assembly 2 into a housing, is shown in accordance with some embodiments of the present application. As shown in fig. 9, after the to-be-bent section 212 of each tab 21 is bent, a first bending portion 2121 and a second bending portion 2122 are formed in an end-to-end connection, the direction of the bending concave portion of the first bending portion 2121 is opposite to that of the second bending concave portion, and the cross-sectional shape of the first bending portion 2121 and the second bending portion 2122 in the end-to-end connection is generally S-shaped. Here, referring to fig. 2 and 9, for example, the multi-layer tab 21 formed by at least two tabs 21 on the right side in fig. 2 protrudes from an edge of one end of the cell body 1 along the Z direction, and the shaped fixing section 211 of the tab 21 should be located directly above one end of the cell body 1 along the Z direction, where the end of the cell body 1 along the Z direction and close to the tab 21 is defined as the first end of the cell body 1. In order to facilitate connection between the fixing section 211 and the conductive member 3, the projection of the plane of the first end of the cell main body 1 of the fixing section 211 is usually located at the right center position thereof, that is, the bending of the tab 21 is equivalent to the need of closing the to-be-bent section 212 to the center position of the first end, so that in the state of attaching and fixedly connecting the conductive member 3 and the fixing section 211, the to-be-bent section 212 is bent to form a generally S-shaped bent section.

As shown in fig. 9, the connection area D is selected in the area between the bending center line of the first bending portion 2121 and the bending center line of the second bending portion 2122, and the connection area D includes the bending center line of the first bending portion 2121 and the bending center line of the second bending portion 2122, and is located approximately in the middle area of the tab 21, compared with fig. 8, the connection area D, that is, the area where the laminated tab 21 is easy to diverge, so that the connection area D can avoid the problem of inserting the laminated tab 21 into the cell body 1 due to the divergence of the laminated tab 21 at the point, and as shown in fig. 9, the situation that the tab 21 is not inserted into the cell body 1 due to the divergence after the bending of the at least two tabs 21 after the connection area D is set can be seen.

In some embodiments, the connection region D is located in a region between a connection of the first bend 2121 and the second bend 2122 and a bend centerline of the second bend 2122, wherein the region between the connection and the bend centerline of the second bend 2122 includes the connection and the bend centerline of the second bend 2122.

By further limiting the extent of the reduced connection region D, it is possible to further fix at least two tabs 21 at a relatively more bifurcated position.

In some embodiments, the connection region D is disposed on the bend centerline of the second bend 2122.

The problem that the tab 21 is easy to be branched can be solved to the greatest extent by further defining the connection region D on the bending center line of the second bending portion 2122, and the center line of the second bending portion 2122 is the position region where the tab 21 is most easy to be branched.

In some embodiments, the to-be-bent section 212 is bent to form a third bending portion (not shown in the figure), one end of the third bending portion is connected to the fixing section 211, and the other end is connected to the pole piece; the bending concave part of the third bending part faces to the first direction; the connection region D is formed in a region between one quarter and three quarters of the side of the bending concave portion of the third bending portion near the fixing section 211; the side of the fixing section 211 connected to the first bending portion 2121 is a first side of the fixing section 211, the side opposite to the first side is a second side, the first direction is perpendicular to the plane where the first pole piece is located, and the first direction is directed from the second side to the first side.

In the embodiment of the present application, the to-be-bent section 212 is bent to form a third bent portion, one end of the third bent portion is connected with the fixing section 211, and the other end of the third bent portion is connected with the pole piece, and in addition, the bending concave portion of the third bent portion faces the first direction, so that the cross section shape of the to-be-bent section 212 is approximately C-shaped. Referring to fig. 2 and 9, for example, the multi-layer tab 21 formed by at least two tabs 21 on the left side in fig. 2 is protruded from the edge of the first end portion of the cell main body 1, so that in order to facilitate connection between the fixing section 211 and the conductive member 3, the projection of the plane of the first end portion of the cell main body 1 of the fixing section 211 is usually located at the right center position, that is, when the tab 21 is bent, the to-be-bent section 212 needs to be close to the center position of the first end portion, that is, the fixing section 211 of at least two tabs 21 on the left side needs to be aligned with the fixing section 211 of the tab 21 on the right side along the Y direction, so that in the state that the conductive member 3 is fixedly connected with the fixing section 211 in a bonding manner, the left to-be-bent section 212 is bent to form a substantially C-shaped bent section.

For example, referring to fig. 1 and 2, one end of the battery cell main body 1 has two multi-layer tabs 21, and the two multi-layer tabs 21 may be configured in different forms, for example, in one multi-layer tab 21 on the left side, the to-be-bent section 212 of the tab 21 may form a third bending portion, that is, a C-shaped bending section formed after the to-be-bent section 212 is bent; in the multilayer tab 21 on the right side, the to-be-bent section 212 of the tab 21 may be formed into a first bending portion 2121 and a second bending portion 2122 that are connected end to end, that is, an S-shaped bending section formed after the to-be-bent section 212 is bent. In addition, referring to fig. 4 to 6, each of opposite ends of the cell main body 1 has a tab 21, for example, the tab 21 at one end may be connected to the positive electrode tab in the electrode assembly 2, and the tab 21 at the other end may be connected to the negative electrode tab in the electrode assembly 2. In addition, as shown in fig. 7, only the same end of the cell body 1 in fig. 7 is provided with two multi-layered tabs 21, and one of the two multi-layered tabs 21 may be connected to the positive electrode tab and the other to the negative electrode tab.

In the state that the fixing section 211 is connected with the conductive member 3, only one third bending section exists in the to-be-bent section 212, and at this time, the position where the tab 21 is easy to be bifurcated should be a quarter to three quarters area of the bending concave portion of the third bending section near one side of the fixing section 211, that is, a central position area of the bending concave portion near the third bending section, and this area is an easy-bifurcated area of the tab 21, so that the connection area D is set at this point and can prevent the tab 21 from being bifurcated and then inserted into the cell main body 1.

In some embodiments, the pole piece has a longitudinal direction and a width direction perpendicular to each other, the tab 21 is disposed at one end of the pole piece along the longitudinal direction, and all the tabs 21 are connected through-hole along the width direction of the pole piece.

In the embodiment of the present application, all the tabs 21 are connected in a through manner along the width direction of the pole piece, specifically, referring to fig. 2, the D region in fig. 2 is the connection region D, and the through connection may be understood that the connection region D covers the whole portion of the to-be-bent section 212 of the tab 21 along the width direction of the pole piece, that is, in the Y direction in fig. 2.

In this way, all the tabs 21 are connected in the connection region D in a through manner along the width direction of the pole piece, so that the connection manner is tight and reliable, and the tabs 21 can be prevented from being bifurcated to a greater extent.

In some embodiments, the pole piece has a longitudinal direction and a width direction perpendicular to each other, the tab 21 is disposed at one end of the pole piece along the longitudinal direction, and at least two connection points 213 spaced apart along the width direction of the pole piece are disposed in the connection region D.

In the embodiment of the present application, all the tabs 21 are connected at intervals along the width direction of the pole piece, specifically, referring to fig. 2, the D region in fig. 2 is a connection region D, and the interval connection may be understood as that at least two connection points 213 are distributed at intervals in the connection region D, and the connection points 213 intermittently and discontinuously cover the to-be-bent sections 212 of the tabs 21. As shown in fig. 2, i.e. at least two connection points 213 are spaced apart within the connection area D.

The above-mentioned mode that the connection region D is arranged at intervals saves the connection material, and simultaneously, because the operation space is narrow when the laminated tab 21 is fixedly connected in the connection region D, when at least two connection points 213 which are arranged at intervals are arranged in the connection region D, the operation is simple and easy.

In some embodiments, all tabs 21 within the connection region D are welded.

The design above, the mode of welded fastening compares with bonding or additionally adds connecting pieces (such as connecting buckles or connecting rings, etc.), has the advantage of strong connection reliability and good conductivity after connection. Meanwhile, new materials are not required to be introduced like bonding, and the risk of pollution to electrolyte caused by the introduction of the new materials can be avoided.

In some embodiments, all tabs 21 within the connection region D are adhesively secured.

The bonding in the embodiment of the application can be tab glue or electric welding glue. For example, a relatively strong and simple to operate welding paste may be used.

The bonding fixing mode is easy to operate and high in connection efficiency compared with welding.

Referring to fig. 11, fig. 11 is a flowchart of a method for assembling a battery cell according to an embodiment of the present application, and according to some embodiments of the present application, there is further provided a method for assembling a battery cell, where each tab 21 includes a to-be-bent section 212 and a fixing section 211, and a connection region D is disposed in the to-be-bent section 212, and the method includes step S10 and step S20.

Step S10, welding the fixed section and the conductive piece;

and S20, welding all the to-be-bent sections of the tabs in the connecting area.

In the embodiment of the present application, in step S10, shaping treatment may be performed on all the fixing sections 211 of the tab 21, for example, the fixing sections 211 of the tab 21 are flattened, so that the plane of the fixing sections 211 is parallel to the plane of the first end of the cell main body 1, and then the fixing sections 211 are welded with the conductive member 3. The fixing section 211 and the conductive member 3 may be welded by ultrasonic welding, laser welding, etc., which is not particularly limited. Then, through step S20, all the sections to be bent 212 of the tab 21 in the connection region D are welded.

Because the fixing section 211 is welded with the conductive piece 3, the situation that the fixing sections 211 among the tabs 21 are different in height after the to-be-bent sections 212 of all the tabs 21 are welded in the connecting area D can be avoided, and therefore the connection with the conductive piece is difficult, and the battery core is difficult to insert into the shell is avoided. In addition, through step S20, at least two tabs 21 are constrained to be a whole that is not easy to loose after being folded in the connection region D of the to-be-folded section 212, so as to prevent the tabs 21 from being bifurcated and inserted into the battery core main body 1.

In some embodiments, the fixing section 211 and the conductive element 3 are welded together and the section 212 to be bent in the connection area D is welded together by ultrasonic welding.

In some embodiments of the present application, for example, referring to fig. 10, in step S10 and step S20, the shape of the welding head during welding is not limited, and the welding form of continuous welding may be adopted by using the shape of the welding head such as the 1 st or the 5 th type in fig. 10, so that the connection area D continuously extends through and covers the Y direction of the section 212 to be bent of the tab 21. For another example, one of the 2 nd, 3 rd, 4 th, 6 th, and 7 th types of fig. 10 may be used to form at least two connection points 213, i.e., at least two welding points, in the connection region D by spot welding. In addition, a combination welding using continuous welding and spot welding may be used. For example, the 1 st wider bonding wire mode can be adopted, the operation is simple, and the connection reliability is high.

In the scheme, the ultrasonic welding mode is adopted, so that the metal surfaces of the adjacent lugs 21 are tightly contacted to achieve the combination between atoms, the higher melting strength is achieved, the welding speed is high, and the risk that sparks and melting materials contact the inside of the battery cell is avoided in the welding process.

The above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application, and they should be included in the scope of the present application. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict.

Claims

1. An electrode assembly, comprising:

a pole piece;

at least two lugs protruding from the pole pieces and arranged in a mutually laminated manner;

each tab comprises a to-be-bent section and a fixed section, the to-be-bent section is connected between the fixed section and the pole piece, the fixed section is used for connecting a conductive piece, and the to-be-bent section is bent relative to the fixed section;

a connecting area is arranged in the to-be-bent sections, and all to-be-bent sections of the tabs are fixedly connected in the connecting area;

The connection region starts at one fifth of the section to be bent and ends at four fifth of the section to be bent in the direction along the conductive member toward the pole piece.

2. The electrode assembly of claim 1, wherein the connection region begins at one third of the segment to be bent and ends at two thirds of the segment to be bent.

3. The electrode assembly of claim 1, wherein the ratio of the area of the connection region to the area of the section to be bent is 0.1 to 0.3.

4. The electrode assembly according to claim 1, wherein in a state in which the fixed section is connected to the conductive member, the section to be bent of each tab forms a first bent portion and a second bent portion connected end to end, the first bent portion being connected to the fixed section, the second bent portion being connected to the pole piece;

the bending concave part of the first bending part faces the thickness direction of the pole piece, and the bending concave part of the second bending part faces the opposite direction of the bending concave part of the first bending part;

the connecting area is located in an area between the bending center line of the first bending part and the bending center line of the second bending part, wherein the area between the bending center line of the first bending part and the bending center line of the second bending part comprises the bending center line of the first bending part and the bending center line of the first bending part.

5. The electrode assembly of claim 4, wherein the connection region is located in a region between a junction of the first bend and the second bend and a bend centerline of the second bend, wherein the region between the junction and the bend centerline of the second bend comprises the junction and the bend centerline of the second bend.

6. The electrode assembly of claim 5, wherein the connection region is disposed on a bend centerline of the second bend.

7. The electrode assembly of claim 1, wherein the to-be-bent segment is bent to form a third bent portion, one end of the third bent portion is connected to the fixed segment, and the other end is connected to the pole piece; the bending concave part of the third bending part faces the thickness direction of the pole piece.

8. The electrode assembly of claim 7, wherein the connection region is disposed on a bend centerline of the third bend.

9. The electrode assembly according to any one of claims 1 to 8, wherein the tab is provided at one end in the length direction of the pole piece, and all the tabs are connected through-type in the width direction of the pole piece.

10. The electrode assembly according to any one of claims 1 to 8, wherein the tab is disposed at one end of the pole piece in the length direction, and at least two connection points are disposed in the connection region and are distributed at intervals in the width direction of the pole piece.

11. The electrode assembly of claim 1, wherein all of the tabs in the connection region are welded.

12. The electrode assembly of claim 1, wherein all of the tabs in the connection region are adhesively secured.

13. A battery cell, comprising:

the electrode assembly of any one of claims 1-8;

a case having an opening, the electrode assembly being accommodated in the case;

and the conductive piece is connected with the fixed section.

14. A battery pack, comprising:

a case;

the battery cell of claim 13, wherein the battery cell is contained within the housing.

15. An assembling method for assembling a battery cell, wherein each tab of the battery cell comprises a section to be bent and a fixed section, and a connecting area is arranged in the section to be bent, and the assembling method is characterized by comprising the following steps:

The fixed section is welded with the conductive piece;

and welding all the sections to be bent of the tab in the connecting area.

16. The method of assembly of claim 15, wherein the fixed segment is ultrasonically welded to the conductive member;

and welding all the sections to be bent of the tab in the connecting area through ultrasonic waves.