CN219917515U - Pole piece, battery cell, battery module and vehicle - Google Patents

Abstract

The utility model relates to the technical field of batteries, in particular to a pole piece, an electric core, a battery module and a vehicle, and aims to solve the problem that a diaphragm is scalded when a current collector and a pole lug are welded. For this purpose, the pole piece of the utility model comprises a plurality of pole lugs, and after the pole piece is wound, the pole lugs are folded and laminated to form a plurality of pole lug groups, and the thickness of at least part of the pole lug groups is not less than 108 mu m. The current collector is welded in the region with the thickness of not less than 108 mu m, heat radiation can be generated in the welding process of the electrode lugs and the current collector, and the electrode lug group with the thickness of more than 108 mu m can weaken the spreading speed of the heat radiation to the diaphragm, so that the temperature of the upper edge of the diaphragm is reduced, and the diaphragm cannot be damaged by the heat radiation generated by welding.

Description

Pole piece, battery cell, battery module and vehicle

Technical Field

The utility model relates to the technical field of batteries, and particularly provides a pole piece, an electric core, a battery module and a vehicle.

Background

The power battery is an important component of the new energy automobile, and comprises a plurality of sequentially arranged battery cells, wherein the battery cells are divided into cylindrical battery cells and square battery cells according to the shape.

At present, a full-lug cylindrical battery cell comprises a current collector and a battery cell. The battery cell is formed by winding a pole piece unit, and the pole piece unit comprises a negative pole piece, a diaphragm and a positive pole piece which are sequentially stacked. The negative pole piece is connected with a negative pole lug, the positive pole piece is connected with a positive pole lug, and for convenience in description, the negative pole piece and the positive pole piece are collectively called as a pole piece, and the negative pole lug and the positive pole lug are collectively called as a lug. The pole lugs are arranged at intervals along the length direction of the pole piece where the pole lugs are located, and the interval distance is smaller. After the pole piece units are wound to form the battery core, a plurality of tab groups are formed, and a plurality of tabs are arranged in each tab group. Each tab group is arranged along the radial direction of the battery core, and a plurality of tab groups are arranged at intervals along the circumferential direction of the pole piece unit. The tabs in each tab group are bent along the radial direction of the battery cell, so that the tabs in the tab group are mutually laminated. The laminated tab groups are welded with the current collector to transmit electrons through the current collector. Compared with the traditional cylindrical battery cell, the electrode lugs are arranged more densely, so that the electron transmission distance is greatly reduced, and the internal resistance is obviously reduced.

The solar cell has the defects that in the welding process of the current collector and the laminated tab group, heat radiation generated by welding is conducted to the diaphragm, so that the diaphragm is damaged due to high temperature. The diaphragm can produce thermal contraction after being damaged by high temperature, so that the negative electrode can exceed the diaphragm, and the positive electrode and the negative electrode are in short-circuit contact, thereby affecting the safety and the reliability of the battery cell.

Therefore, there is a need for a pole piece, a battery cell, a battery module and a vehicle to solve the problem that the separator is damaged due to high temperature caused by heat radiation generated when the current collector and the tab are welded.

Disclosure of Invention

The utility model aims to solve the technical problems, namely, the problem that the diaphragm is damaged due to high temperature caused by radiating heat generated when the current collector and the tab are welded to the diaphragm.

In a first aspect, the present utility model provides a pole piece, where the pole piece includes a plurality of tabs, and after the pole piece is wound, the tabs are folded and laminated to form a plurality of tab groups, and at least a portion of the tab groups has a thickness not less than 108 μm.

In the specific embodiment of the pole piece, the ratio of the length of the tab along the first direction to the length along the second direction is less than or equal to 2.3.

In a second aspect, the utility model provides a battery cell, which comprises an anode pole piece and a cathode pole piece formed by the pole pieces, and a first diaphragm and a second diaphragm, wherein the cathode pole piece, the first diaphragm, the anode pole piece and the second diaphragm are sequentially laminated; the negative pole piece comprises a plurality of negative pole lugs, and a lug group at the negative side of the battery cell is formed by stacking the negative pole lugs; the positive pole piece comprises a plurality of positive pole lugs, and the lug group at the positive side of the battery core is formed by laminating the positive pole lugs.

In the specific embodiment of the battery cell, the length of the negative electrode tab along the first direction is greater than or equal to 4.5mm.

In the specific embodiment of the battery cell, the length of the positive electrode tab along the first direction is greater than or equal to 5.5mm.

In the specific embodiment of the battery cell, the thickness of the positive electrode tab is 8 μm to 20 μm.

In the specific embodiment of the battery cell, the thickness of the negative electrode tab is 3 μm to 10 μm.

In a third aspect, the present utility model provides a battery comprising: a housing; the battery cell is arranged in the shell; the negative electrode current collector is arranged in the shell and is welded and connected with the tab group at the negative electrode side; and the positive electrode current collector is arranged in the shell and is welded and connected with the lug group at the positive electrode side.

In a fourth aspect, the present utility model provides a battery module comprising: a case; a plurality of the above batteries are provided in the case.

In a fifth aspect, the present utility model provides a vehicle comprising: the battery module comprises a vehicle body and a battery module arranged on the vehicle body.

Compared with the prior art, the utility model has the following beneficial effects:

the pole piece provided by the utility model comprises a plurality of pole lugs, and after the pole piece is wound, the pole lugs are bent and laminated to form a plurality of pole lug groups, and the thickness of at least part of the pole lug groups is not less than 108 mu m. The current collector is welded in the region with the thickness of not less than 108 mu m, heat radiation can be generated in the welding process of the electrode lugs and the current collector, and the electrode lug group with the thickness of more than 108 mu m can weaken the spreading speed of the heat radiation to the diaphragm, so that the temperature of the upper edge of the diaphragm is reduced, and the diaphragm cannot be damaged by the heat radiation generated by welding.

Furthermore, the ratio of the length of the tab along the first direction to the length along the second direction is smaller than or equal to 2.3, so that the tab is not easy to turn over again or reverse-plug in the bending process, the stability of the bent tab is better, the arrangement is more ordered, and the reliability of the battery cell manufacturing process is higher.

Drawings

Preferred embodiments of the present utility model are described below with reference to the accompanying drawings, in which:

fig. 1 is a top view of a cell provided by the present utility model;

FIG. 2 is a cross-sectional view of a pole piece unit provided by the present utility model;

FIG. 3 is a block diagram of the pole piece provided by the utility model after being unfolded;

fig. 4 is a schematic view of lamination of tab groups provided by the present utility model.

Reference numerals illustrate:

2. a tab; 3. a battery cell; 4. a negative electrode plate; 41. copper foil; 42. a negative electrode active layer; 5. a positive electrode sheet; 51. aluminum foil; 52. a positive electrode active layer; 61. a first diaphragm; 62. a second diaphragm; d. a welding area; x, a first direction; y, second direction.

Detailed Description

Preferred embodiments of the present utility model are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are merely for explaining the technical principles of the present utility model, and are not intended to limit the scope of the present utility model.

It should be noted that, in the description of the present utility model, terms such as "upper," "lower," "left," "right," "inner," "outer," and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, which are merely for convenience of description, and do not indicate or imply that the apparatus or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present utility model. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Furthermore, it should be noted that, in the description of the present utility model, unless explicitly specified and limited otherwise, the terms "mounted," "configured," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be directly connected, can be indirectly connected through an intermediate medium, and can also be communicated with the inside of two elements. The specific meaning of the above terms in the present utility model can be understood by those skilled in the art according to the specific circumstances.

Heat generated when the current collector is welded to the tab is radiated to the separator, which may cause the separator to be damaged by high temperature. In order to solve the technical problems, the utility model provides a battery, in particular a cylindrical battery, which comprises a shell, an electric core, a negative current collector, a positive current collector and electrolyte. The negative electrode current collector, the battery cell and the positive electrode current collector are sequentially arranged in the shell from top to bottom, and electrolyte is injected into the shell to enable the battery cell to be soaked in the electrolyte.

As shown in fig. 1 to 3, the battery cell 3 is formed by winding a pole piece unit, the pole piece unit comprises a negative pole piece 4, a first diaphragm 61, a positive pole piece 5 and a second diaphragm 62 which are sequentially stacked, the first diaphragm 61 can isolate the negative pole piece 4 from the positive pole piece 5 so as to avoid short circuit, and after the pole piece unit is wound, the second diaphragm 62 can isolate the positive pole piece 5 of the pole piece unit and the negative pole piece 4 of the adjacent pole piece unit so as to avoid short circuit. The negative pole piece 4 comprises a plurality of negative pole lugs, the positive pole piece 5 comprises a plurality of positive pole lugs, and the positive pole lugs and the negative pole lugs are respectively positioned at two ends of the battery cell 3. The positive electrode tab and the negative electrode tab are collectively referred to as tab 2. Specifically, for the positive electrode tab or the negative electrode tab, a plurality of tabs 2 are arranged on the pole piece at intervals, after the pole piece is wound, the plurality of tabs 2 are distributed on the same or different turns, and a plurality of tabs which are positioned on different turns and are mutually laminated are defined as tab groups. The positive electrode tab is folded and laminated on the positive electrode side, and the negative electrode tab is folded and laminated on the negative electrode side.

The negative electrode tab 4 includes a copper foil 41 and a negative electrode active layer 42, and the negative electrode active layer 42 is coated on the copper foil 41. The positive electrode sheet 5 includes an aluminum foil 51 and a positive electrode active layer 52, and the positive electrode active layer 52 is coated on the aluminum foil 51. The first separator 61 is located between the anode active layer 42 and the cathode active layer 52 to isolate the anode tab 4 from the cathode tab 5.

The battery cell 3 is provided with a plurality of tab groups at both ends, and the negative pole side is negative pole tab group, and the positive pole side is anodal tab group, and wherein the quantity of the tab group of negative pole side and the quantity of the tab group of anodal side can be different, also can be the same. Specifically, the number of tab groups on the positive electrode side is the same, and is ten. The plurality of tab groups are arranged at intervals along the circumferential direction of the battery cell 3, and are preferably uniformly arranged along the circumferential direction of the battery cell 3 in this embodiment.

The tab group comprises a plurality of tabs 2 which are bent and stacked, wherein the tab group on the negative electrode side is composed of negative electrode tabs, and the tab group on the positive electrode side is composed of positive electrode tabs. The tab 2 is bent inward or outward along the radial direction of the cell, and is preferably bent inward in this embodiment. Any two adjacent tabs 2 of the tab group are stacked and lapped together.

The tab group is welded with the current collector so as to facilitate electron transmission through the current collector; specifically, the tab group on the negative electrode side is welded with the negative electrode current collector, and the tab group on the positive electrode side is welded with the positive electrode current collector. The battery cell with the structure is called a full-tab battery cell, electrons can be transmitted through the current collector and the densely arranged tabs 2 in the process of electrochemical reaction of the negative electrode pole piece 4 and the positive electrode pole piece 5 in the electrolyte, so that the transmission path of the electrons on the pole piece is shortened, the transmission path of the electrons is shortened, the internal resistance of the battery cell is reduced, and the performance of the battery cell is improved.

In the process of welding the tab group and the current collector, only a few layers of tabs 2 close to the current collector are generally directly welded with the current collector, and the rest of tabs 2 are in mutual lamination contact for electron transmission.

As shown in fig. 4, since the positions of the tabs 2 in the tab group are different and the lengths of the tabs 2 are the same, each tab 2 spans at least one layer of pole piece unit after being bent, and then overlaps and overlaps with the adjacent tabs 2 in the tab group, and so on, until all the tabs 2 in the tab group are bent and overlapped.

The tab 2 is generally bent inward in the radial direction of the cell 3, and the number of layers in which the tab 2 is laminated in the tab group decreases as the tab is positioned closer to the outer side of the cell 3. After the tabs 2 in each tab group are laminated, the lamination layer number of the tab 2 at the outermost side is 1, and the lamination layer number of the tab 2 at the innermost side is the largest. The greater the height of the tabs 2, the greater the number of lamination layers of the innermost tabs 2 in the tab group, and in a limit case, the number of lamination layers thereof may be the same as the number of tabs 2 in the tab group. Of course, in most cases, the number of stacked layers of the innermost tabs 2 is smaller than the number of tabs 2 in the tab group, and specifically, when the length of the tab 2 is smaller than the radius of the cell 3, the number of the innermost tabs 2 is smaller than the number of tabs 2 in the tab group.

The thickness of at least part of the region of the tab group is not smaller than a preset value, and the current collector is welded in the region of the tab group with the thickness not smaller than the preset value. The larger the preset value is, the better the reduction effect of heat radiation generated in the welding process of the tab assembly is, the lower the temperature which can be transmitted to the diaphragm is, so that the possibility of diaphragm heat shrinkage is reduced, and the safety and reliability of the battery cell are improved.

The tabs 2 in the tab group have a certain gap between adjacent tabs 2 before lamination. For the positive electrode tab, the gap is the sum of the thicknesses of the positive electrode active layer 52, the negative electrode active layer 42, the first separator 61, the second separator 62, and the negative electrode tab; the gap is the sum of the thicknesses of the positive electrode active layer 52, the negative electrode active layer 42, the first separator 61, the second separator 62, and the positive electrode tab for the negative electrode tab. As shown in fig. 4, after the tabs 2 in the tab group are stacked, due to a certain gap between adjacent tabs 2, the thickness of the stacked tabs 2 in the tab group gradually increases along the bending direction, then tends to be stable, and finally gradually decreases. The thickness of the laminated electrode lugs 2 at the initial end and the tail end of the electrode lug group is the thickness of a single-layer electrode lug 2, the laminated number of the electrode lugs 2 can be stabilized above a certain number in the area of the middle part of the electrode lug group, and the thickness of the area of the middle part of the electrode lug group is not less than a preset value on the premise that the thickness of the electrode lugs 2 is certain. The current collector is welded in a region where the tab group thickness is not less than a preset value (i.e., a region of the tab group middle portion), and a region where the lamination number of the tab 2 layers of the tab group middle portion is stabilized above a certain number is called a welding region d. At least a part of the tabs 2 are laminated in the welding zone d in a number of layers not smaller than a set value, that is, the tab 2 is laminated in a number of layers not smaller than the set value at any point in the welding zone d. On the premise that the thickness of the tab 2 is constant, the number of layers of the tab 2 stacked in the welding area d is not smaller than a set value, which means that the thickness of the welding area d is not smaller than a preset value.

In addition, the thicker the welding area d is, the better the effect of reducing heat radiation generated in the welding process is, and the lower the temperature which can be transmitted to the diaphragm is, so that the possibility of diaphragm heat shrinkage is reduced, and the safety and reliability of the battery cell are improved.

The relationship between the thickness of the welding zone d of each tab group and the upper edge temperature of the separator is shown in table 1, and the welding temperature of the tab 2 and the current collector is set to X, specifically, 150 to 170 ℃. As can be seen from Table 1, when the thickness of the land d is greater than 108. Mu.m, the effect of reducing the temperature rise of the upper edge of the separator by increasing the equivalent thickness is reduced (i.e., the temperature reduction value is less than 0.2 ℃ C.). The thickness of the welding area d should be greater than or equal to 108 μm from the viewpoint of safety, so as to reduce the possibility that the heat radiation generated by welding burns the diaphragm.

TABLE 1 correspondence between the thickness of the weld zone and the upper edge temperature of the diaphragm

The number of lap layers of tab 2 in weld zone d is related to the length of the individual tab 2, the thickness of the pole piece unit and the number of winding layers of the pole piece unit. Specifically, the greater the length of a single tab 2, the greater the number of overlapping layers of the tab 2 in the welding zone d; the thinner the thickness of the pole piece unit is, the shorter the distance between two adjacent layers of pole lugs 2 in the radial direction of the battery core 3 is, and the more the number of lap layers of the pole lugs 2 in the welding area d is; the more the number of winding layers of the pole piece units is, the more the number of pole lugs 2 in a single pole lug group is, and the more the number of lap layers of the pole lugs 2 in the welding area d is. The lap thickness is the product of the number of lap layers and the thickness of the tab 2.

The positive electrode tab is generally the same thickness as the aluminum foil 51, and the negative electrode tab is generally the same thickness as the copper foil 41. The thinner the aluminum foil 51 and the copper foil 41, the greater the thickness of the negative electrode active layer 42 that can be coated on the copper foil 41, and the greater the thickness of the positive electrode active layer 52 that can be coated on the aluminum foil 51, on the premise of a certain pole piece unit, contributing to the improvement of the energy density of the battery. Of course, the thickness of the aluminum foil 51 and the copper foil 41 cannot be too thin, otherwise the structural strength of the tab and the pole piece is affected; meanwhile, the thickness of the aluminum foil 51 and the copper foil 41 cannot be too thick, otherwise the energy density of the battery is affected. Specifically, the thickness of the positive electrode tab is generally 8 μm to 20 μm, and the thickness of the negative electrode tab is 3 μm to 10 μm.

In the example of the present embodiment, the thickness of the aluminum foil 51 is 12 μm, the thickness of the positive electrode active layer 52 is 140 μm, the thickness of the separator is 10 μm, the thickness of the negative electrode active layer 42 is 160 μm, the thickness of the copper foil 41 is 6 μm, and the total thickness of the pole piece units is about 328 μm. The thickness of the positive electrode tab is consistent with the thickness of the aluminum foil 51, the thickness of the negative electrode tab is consistent with the thickness of the copper foil 41, the lap joint number of the positive electrode tab of the welding area d on the positive electrode side is more than or equal to 9 layers, and the lap joint number of the negative electrode tab of the welding area d on the negative electrode side is more than or equal to 18 layers on the premise that the thickness of the welding area d is not less than 108 mu m. Of course, this example is not intended to limit the utility model and one skilled in the art could use pole piece units of other thickness parameters to provide tabs in the weld zone d with a lap joint thickness of greater than or equal to 108 μm without departing from the principles of the utility model.

The pole piece units are unfolded to form a first direction X and a second direction Y, wherein the first direction X is the width direction of the pole piece units, the second direction Y is the length direction of the pole piece units, and the first direction X and the second direction Y are mutually perpendicular.

When the pole piece unit is unfolded, the length of the pole lug 2 along the first direction X is not too small, otherwise the length of the welding area d is affected. Specifically, the length of the positive electrode tab along the first direction X is not less than 5.5mm, and the length of the negative electrode tab along the first direction X is not less than 4.5mm.

In addition, the ratio of the length of the tab 2 along the first direction X to the length along the second direction X is smaller than or equal to 2.3, so that the tab 2 is not easy to turn over again or reverse-insert in the bending process, the stability of the tab 2 in each tab group after bending is better, the arrangement is more ordered, and the reliability of the battery cell manufacturing process is higher. Specifically, the length of the positive electrode tab is 6.5mm, and the width is 4mm; the length of the cathode tab is 5.5mm and the width is 4mm.

The working principle of the utility model is as follows: the pole piece units are wound to form a column shape, the negative pole lugs are inwards bent to form a lug group at the negative side, and the positive pole lugs are inwards bent to form a lug group of the positive pole lugs. The thickness of the tab group welding region d after lamination is 108 μm or more. And heat radiation can be generated in the welding process of the tab 2 and the current collector, and the tab 2 in the welding area d can weaken the spreading speed of the heat radiation to the diaphragm, so that the temperature of the upper edge of the diaphragm is reduced, and the diaphragm cannot be damaged by the heat radiation generated by welding.

The embodiment also discloses a battery module, and it includes box and a plurality of foretell cylinder battery, and a plurality of cylinder batteries set up in the box, outwards supply power through the mode of series-parallel. The battery module can be applied to a vehicle, is arranged on a vehicle body, can be a fuel vehicle, supplies power for starting and electricity utilization facilities of the vehicle, and is used as a power source of the vehicle except for supplying power for the electricity utilization facilities if the battery module is a plug-in hybrid vehicle, a fuel-electric hybrid vehicle or an electric vehicle.

Thus far, the technical solution of the present utility model has been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of protection of the present utility model is not limited to these specific embodiments. Equivalent modifications and substitutions for related technical features may be made by those skilled in the art without departing from the principles of the present utility model, and such modifications and substitutions will fall within the scope of the present utility model.

Claims (10)

1. The pole piece is characterized by comprising a plurality of pole lugs (2), wherein after the pole piece is wound, the pole lugs (2) are folded and laminated to form a plurality of pole lug groups, and at least part of the pole lug groups have the thickness not smaller than 108 mu m.

2. Pole piece according to claim 1, characterized in that the ratio of the length of the pole tab (2) in the first direction to the length in the second direction is less than or equal to 2.3.

3. A battery cell, characterized by comprising a positive electrode sheet (5) and a negative electrode sheet (4) formed by the electrode sheets according to claim 1 or 2, and a first separator (61) and a second separator (62), wherein the negative electrode sheet (4), the first separator (61), the positive electrode sheet (5) and the second separator (62) are sequentially stacked;

the negative electrode plate (4) comprises a plurality of negative electrode lugs, and the lug group at the negative electrode side of the battery cell (3) is formed by stacking the negative electrode lugs;

the positive pole piece (5) comprises a plurality of positive pole lugs, and the lug group on the positive pole side of the battery core (3) is formed by stacking the positive pole lugs.

4. The cell of claim 3, wherein the length of the negative tab in the first direction is greater than or equal to 4.5mm.

5. The cell of claim 3, wherein the positive tab has a length in the first direction that is greater than or equal to 5.5mm.

6. The cell of claim 3, wherein the positive tab has a thickness of 8 μm to 20 μm.

7. The cell of claim 3, wherein the negative tab has a thickness of 3 μm to 10 μm.

8. A battery, comprising:

a housing;

the cell (3) of any one of claims 3 to 7, disposed within the housing;

the negative electrode current collector is arranged in the shell and is welded and connected with the tab group at the negative electrode side;

and the positive electrode current collector is arranged in the shell and is welded and connected with the tab group on the positive electrode side.

9. A battery module, comprising:

a case;

a plurality of batteries as claimed in claim 8, disposed within the case.

10. A vehicle, characterized by comprising:

a vehicle body and the battery module according to claim 9 provided on the vehicle body.