CN213340432U

CN213340432U - Negative pole piece and battery and object using same

Info

Publication number: CN213340432U
Application number: CN202021457624.3U
Authority: CN
Inventors: 张磊; 王晓明; 杨浩田; 解金库; 韩冰; 魏凤杰; 周予坤
Original assignee: Jiangsu Zhuogao New Material Technology Co Ltd
Current assignee: Jiangsu Zhuogao New Material Technology Co Ltd
Priority date: 2020-07-22
Filing date: 2020-07-22
Publication date: 2021-06-01
Anticipated expiration: 2030-07-22

Abstract

The application discloses a negative pole piece and a battery and an object using the negative pole piece, and relates to the technical field of lithium batteries. The negative pole piece comprises: a current collector having a width m, the current collector comprising: a support layer; a first conductive layer disposed at one side of the support layer; a second conductive layer disposed at the other side of the support layer; the active material is arranged on two sides of the current collector, and a blank area is reserved at one end of the current collector; the electrode lug is welded on the blank area, the width between the edge of the electrode lug and the edge of the current collector is m, and the following relational expression is satisfied between m and h: m is not less than 1/4h and not more than 3/4 h. According to the method, a certain space is reserved by controlling the relation between m and h, and in the negative electrode expansion process, even if the current collector is broken, a B-C connection area is reserved, so that the current collector is unlikely to be broken completely, the proportion of invalid batteries can be effectively reduced, and the qualification rate and the service life of battery products are improved.

Description

Negative pole piece and battery and object using same

Technical Field

The application relates to the technical field of lithium batteries, in particular to a negative pole piece and a battery and an object using the same.

Background

As shown in fig. 1, the negative electrode of the lithium ion battery is composed of a negative electrode current collector 1 (generally made of copper foil), an active material 2 coated on both sides of the current collector, and a tab 3 welded on the current collector. During charge and discharge, the negative electrode active material expands and contracts. Particularly in a cylindrical battery, the pole piece is wound into a cylinder shape, and the negative pole piece positioned in the inner ring can be transversely pulled under the expansion action of the active material; the negative pole tab can be welded on the shell and is fixed and immovable. The stress caused by the expansion can generate great stress on the joint of the lug and the copper foil of the current collector. The tab welding can damage the current collector, resulting in a large number of defects. As shown in fig. 2, the tensile stress easily causes the current collector 1 (copper foil) to break at the edge (a-B) of the welding area 31 of the tab 3 and to expand along a-B, and finally forms a-C to completely break, which causes the tab and the pole piece to open circuit, thereby causing no voltage output of the lithium battery and battery failure.

The existing solution is mainly to reduce the expansion of the pole piece by adjusting the structure of the active substance and increase the strength of the copper foil to resist the fracture. Since the current commercial lithium battery employs a graphite negative electrode, the graphite undergoes volume expansion during lithium deintercalation. This expansion is inevitably due to a change in the atomic-level structure of the material. Meanwhile, in order to increase the energy density of the battery, some companies add a silicon material to the negative electrode. The volume expansion of the silicon material is larger during lithium extraction. Therefore, as lithium battery technology advances, the negative electrode swelling condition becomes more severe. On the other hand, in order to increase the energy density of a lithium battery, it is necessary to increase the proportion of active materials for storing lithium ions and to reduce inactive materials such as copper foil. This requires the use of thinner copper foil, which results in a reduction in the fracture resistance of the copper foil. Furthermore, due to the poor plastic deformation capability of the copper foil, when the tab welding area A-B is broken, the breakage port is easily expanded to the whole copper foil area, and the A-C is easily broken.

SUMMERY OF THE UTILITY MODEL

The application aims at providing a negative pole piece, which solves the problem that a negative pole current collector is easy to break and causes battery failure in the prior art.

In order to achieve the above purpose, the embodiments of the present application adopt the following technical solutions: a negative electrode tab, comprising: a current collector having a width m, the current collector comprising: a support layer; a first conductive layer disposed at one side of the support layer; a second conductive layer disposed at the other side of the support layer; the active material is arranged on two sides of the current collector, and a blank area is reserved at one end of the current collector; the electrode lug is welded on the blank area, the width between the edge of the electrode lug and the edge of the current collector is m, and the following relational expression is satisfied between m and h: m is not less than 1/4h and not more than 3/4 h.

In the technical scheme, the composite current collector is adopted, the relation between m (the width between the edge of the tab and the edge of the current collector) and h (the width of the current collector) is controlled, namely m is not less than 1/4h and not more than 3/4h, and a certain space is reserved, so that a B-C connection area can be reserved even if the current collector is broken in the expansion process of the negative electrode, the current collector is not broken completely, the proportion of failed batteries can be effectively reduced, and the qualification rate and the service life of battery products are improved. Meanwhile, the support layer has high elongation at break, so that the whole current collector has high elongation at break. Under the condition, when the current collector is broken by A-B (tab welding edge), because the current collector is high in breakage elongation rate, large plastic deformation can be generated, the continuous expansion of breakage can be inhibited, and the breakage of B-C can be further avoided, so that the current collector can still be kept on, and the failure of the battery can not occur.

Further, according to the embodiment of the present application, wherein the support layer is made of a polymer.

Further, according to the embodiment of the present application, wherein the thickness of the support layer is 2 micrometers to 5 micrometers.

Further, according to the embodiment of the present application, wherein the first conductive layer and the second conductive layer use copper or a copper alloy.

Further, according to the embodiment of the present application, the thickness of the first conductive layer and the second conductive layer is 0.2 micrometers to 3 micrometers.

In order to achieve the above purpose, the following technical solutions are further adopted in the embodiments of the present application: a negative electrode tab, comprising: a current collector, the current collector comprising: a support layer; a first conductive layer disposed at one side of the support layer; a second conductive layer disposed at the other side of the support layer; the active material is arranged on two sides of the current collector, and a blank area is reserved at one end of the current collector; and the lug is welded on the blank area, and a suppression area is arranged below the lug.

In the technical scheme, the composite current collector is adopted, and the defects are made on the current collector, so that the A-B fracture is diffused to the fracture expansion inhibition area and cannot be extended continuously to be expanded, and the current collector is protected from the B-C fracture. Meanwhile, the support layer has high elongation at break, so that the whole current collector has high elongation at break. Under the condition, when the current collector is broken by A-B (tab welding edge), because the current collector is high in breakage elongation rate, large plastic deformation can be generated, the continuous expansion of breakage can be inhibited, and the breakage of B-C can be further avoided, so that the current collector can still be kept on, and the failure of the battery can not occur.

Further, according to the embodiment of the present application, wherein the inhibition zone is disposed on the current collector by cutting.

Further, according to the embodiment of the application, the inhibition area is arranged on the current collector by means of punching.

Further, according to the embodiment of the present application, wherein the shape of the inhibition zone is a square or an arc.

Further, according to the embodiment of the application, the width of the restraining area is larger than the width of the tab.

Further, according to the embodiment of the application, a guide area is arranged between the tab and the active material.

Further, according to the embodiment of the present application, wherein the guiding region is disposed on the current collector by punching or pressing.

In order to achieve the above purpose, an embodiment of the present application further discloses a battery, where the battery has a negative electrode tab as described above.

In order to achieve the purpose, the embodiment of the application also discloses an object, and the object is provided with the battery.

Further, according to the embodiment of the present application, wherein the object is an electronic device or a vehicle.

Compared with the prior art, the method has the following beneficial effects:

(1) according to the method, the relation between m (the width between the edge of the tab and the edge of the current collector) and h (the width of the current collector) is controlled, so that m is not less than 1/4h and not more than 3/4h, a certain space is reserved, a B-C connecting area is reserved even if the current collector is broken in the expansion process of the negative electrode, the current collector is not completely broken, the failure of the battery can be effectively avoided, and the qualification rate and the service life of the battery product are improved;

(2) the method has the advantages that the defects are manufactured on the current collector, so that the A-B fracture is diffused to the fracture expansion inhibition area, and the A-B fracture cannot continue to extend to expand, and the current collector is protected from the B-C fracture;

(3) this application is through adopting compound mass flow body, because the supporting layer has very high fracture elongation, consequently this mass flow body's whole has very high fracture elongation. Under the condition, when the current collector is broken by A-B (tab welding edge), because the current collector is high in breakage elongation rate, large plastic deformation can be generated, the continuous expansion of breakage can be inhibited, and the breakage of B-C can be further avoided, so that the current collector can still be kept on, and the failure of the battery can not occur.

Drawings

The present application is further described below with reference to the drawings and examples.

Fig. 1 is a schematic structural view of a conventional negative electrode tab.

Fig. 2 is a schematic view of the principle of fracture of the negative electrode current collector.

Fig. 3 is a schematic structural diagram of a negative electrode tab in the first embodiment of the present application.

Fig. 4 is a schematic view of a current collector structure used in the first embodiment of the present application.

Fig. 5 is a schematic structural diagram of a negative electrode tab in the second embodiment of the present application.

Fig. 6 is a schematic structural diagram of a negative electrode tab in the third embodiment of the present application.

Fig. 7 is a schematic structural diagram of a negative electrode tab in the fourth embodiment of the present application.

Fig. 8 is a schematic structural diagram of a negative electrode tab in example five of the present application.

In the attached drawings

1. Current collector 11, first conductive layer 12, support layer

13. Second conductive layer

2. Active material

3. Tab 31, welding area 32, suppression area one

33. Guide area

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clear and fully described, embodiments of the present invention are further described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of some embodiments of the invention and are not limiting of the invention, and that all other embodiments obtained by those of ordinary skill in the art without the exercise of inventive faculty are within the scope of the invention.

In the description of the present invention, it should be noted that the terms "center", "middle", "upper", "lower", "left", "right", "inner", "outer", "top", "bottom", "side", "vertical", "horizontal", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "a," "an," "first," "second," "third," "fourth," "fifth," and "sixth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

For the purposes of simplicity and explanation, the principles of the embodiments are described by referring mainly to examples. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, to one skilled in the art that the embodiments may be practiced without these specific details. In some instances, well-known methods and structures have not been described in detail so as not to unnecessarily obscure the embodiments. In addition, all embodiments may be used in combination with each other.

[ example 1 ]

Fig. 3 is a schematic structural diagram of a negative electrode tab in this embodiment, fig. 4 is a schematic structural diagram of a current collector used in this embodiment, and the technical solution in this embodiment is described with reference to fig. 3 and 4.

As shown in fig. 3, the negative electrode tab structure in this embodiment includes a current collector 1, both sides of the current collector 1 are coated with active materials 2, and a blank area for welding a tab 3 is left at one end of the current collector. Wherein the width of current collector 1 is h. A tab 3 is welded to the current collector 1, and the width between the edge of the tab 3 and the edge of the current collector 1 is m.

In order to prevent the battery from failing due to the fracture of the current collector 1, the current collector 1 is prevented from spreading to the B-C section by controlling the relationship between m and h when the fracture of the current collector 1 occurs, as shown in fig. 2, a-B (tab welding edge) occurs, and the conduction of the current collector 1 is maintained. Specifically, m and h satisfy the following relationship:

1/4h≤m≤3/4h；

if m is too large (greater than 3/4h), the welding area between the tab and the blank area is small, the conductive performance is poor, and the tab is easy to fall off. m should not be too small (less than 1/4h) to allow a space for the current collector to break during expansion of the negative electrode, but the B-C connection region is left so as not to completely break.

As shown in fig. 4, the current collector 1 in the present embodiment employs a composite current collector having a support layer 12 and a first conductive layer 11 and a second conductive layer 13 composited on both sides of the support layer 12. The support layer 12 may be made of a polymer for providing a supporting capability, and may specifically be made of PET, PI, PU, PSI, PP, PE, and the like, without limiting the present application. The first conductive layer 11 and the second conductive layer 13 are generally made of the same conductive material, and are used for conducting current out. Preferably, as a current collector of the negative electrode, the first conductive layer 11 and the second conductive layer 13 may be made of copper or a copper alloy.

In the above technical solution, the thickness of the supporting layer 12 is 2 micrometers to 15 micrometers, and the thickness of the first conductive layer 11 and the second conductive layer 13 is 0.2 micrometers to 3 micrometers. Since the support layer 12 has a high elongation at break, the entire current collector 1 has a high elongation at break. In this case, when the current collector 1 is broken as shown in fig. 2, a-B (tab welding edge) is broken, since the current collector 1 itself has a high breaking elongation rate, a large plastic deformation occurs, which can inhibit the breakage from continuing to expand, and avoid the breakage of B-C, so that the current collector 1 can still be kept on, and the battery cannot fail.

[ example two ]

Fig. 5 is a schematic structural diagram of the negative electrode tab in this embodiment. As shown in the figure, in the present embodiment, a suppression area 32 is provided below the tab 3, and the suppression area 32 is provided on the current collector 1 by cutting (i.e., making a cutting line). The present embodiment protects the current collector 1 from B-C fracture by creating defects on the current collector 1, so that the a-B fracture shown in fig. 2 propagates to the fracture propagation inhibition zone and cannot continue to extend to propagate. Preferably, the width of the restraining region 32 is greater than the width of the tab 3.

In addition, the composite current collector adopted in the present embodiment is the same as that in the first embodiment, and has the same technical effect.

[ EXAMPLE III ]

Fig. 6 is a schematic structural diagram of the negative electrode tab in this embodiment. As shown in fig. 6, in the present embodiment, a suppression area 32 is provided below the tab 3, and the suppression area 32 is provided on the current collector 1 by punching, so as to form a square punched area. The present embodiment protects the current collector 1 from B-C fracture by creating defects on the current collector 1, so that the a-B fracture shown in fig. 2 propagates to the fracture propagation inhibition zone and cannot continue to extend to propagate. Preferably, the width of the restraining region 32 is greater than the width of the tab 3.

Other structures of the present embodiment are the same as those of the above embodiments, and have the same technical effects.

[ EXAMPLE IV ]

Fig. 7 is a schematic structural diagram of the negative electrode tab in this embodiment. As shown in fig. 7, in the present embodiment, a suppression area 32 is provided below the tab 3, and the suppression area 32 is provided on the current collector 1 by punching, so as to form a circular-arc-shaped punched area. The present embodiment protects the current collector 1 from B-C fracture by creating defects on the current collector 1, so that the a-B fracture shown in fig. 2 propagates to the fracture propagation inhibition zone and cannot continue to extend to propagate. Preferably, the width of the restraining region 32 is greater than the width of the tab 3.

[ EXAMPLE V ]

Fig. 7 is a schematic structural diagram of the negative electrode tab in this embodiment. As shown in fig. 7, in the present embodiment, a suppression area 32 is provided below the tab 3, and the suppression area 32 is provided on the current collector 1 by cutting (i.e., making one cutting line). The present embodiment protects the current collector 1 from B-C fracture by creating defects on the current collector 1, so that the a-B fracture shown in fig. 2 propagates to the fracture propagation inhibition zone and cannot continue to extend to propagate. Preferably, the width of the restraining region 32 is greater than the width of the tab 3.

Meanwhile, a guide area 33 is arranged between the tab 3 and the active material 2, and the strength of the guide area 33 is lower than that of a current collector at the welding position of the tab 3. During the expansion of the negative electrode, the lead region 33 is broken under stress in preference to a-B, so that the formed broken region is aligned and can be suppressed by the suppression region 32. After the occurrence of the fracture a-B as shown in fig. 2, the guiding region 33 can effectively avoid the fracture propagation direction from bypassing the restraining region 32 under the expansion stress. Preferably, the length of the lead-in area 33 corresponds to the length of the welding area of the tab, the lead-in area 33 being arranged parallel to the tab.

To further illustrate the effect of the present application, 3 examples are listed in table 1 for comparison.

TABLE 1

In table 1, the cycle failure ratio refers to the ratio of the failed battery with no voltage output after different cycle times in 100 batteries, which is subjected to a 1C/1C charge and discharge test at 25 ℃.

As shown in table 1, the composite current collector has a very high elongation at break and a lower tensile strength than the copper foil. The mechanical property determines that the composite current collector has good plastic deformation capacity, when a part of area is broken, the tip of a crack is easy to passivate, and the crack is difficult to expand, so that the whole current collector is prevented from being broken. Meanwhile, m is not less than 1/4h and not more than 3/4h by controlling the relation between m and h, so that the proportion of the failed battery can be effectively reduced, the qualification rate of the battery product is improved, and the service life of the battery product is prolonged.

Although the illustrative embodiments of the present application have been described above to enable those skilled in the art to understand the present application, the present application is not limited to the scope of the embodiments, and various modifications within the spirit and scope of the present application defined and determined by the appended claims will be apparent to those skilled in the art from this disclosure.

Claims

1. A negative electrode sheet, comprising:

a current collector having a width m, the current collector comprising:

a support layer;

a first conductive layer disposed on one side of the support layer;

a second conductive layer disposed at the other side of the support layer;

the active material is arranged on two sides of the current collector, and a blank area is reserved at one end of the current collector;

utmost point ear, utmost point ear welding is in on the blank area, the edge of utmost point ear with width between the edge of mass flow body is m, satisfies the following relational expression between m and the h:

1/4h≤m≤3/4h。

2. the negative electrode plate of claim 1, wherein the support layer is made of a polymer.

3. The negative electrode tab of claim 1, wherein the support layer has a thickness of 2 to 5 microns.

4. The negative electrode plate of claim 1, wherein the first conductive layer and the second conductive layer are copper or copper alloy.

5. The negative electrode tab of claim 1, wherein the first and second conductive layers have a thickness of 0.2-3 microns.

6. A negative electrode sheet, comprising:

a current collector, the current collector comprising:

a support layer;

a first conductive layer disposed on one side of the support layer;

a second conductive layer disposed at the other side of the support layer;

and the lug is welded on the blank area, and a suppression area is arranged below the lug.

7. A negative electrode tab according to claim 6, wherein the restraint region is provided on the current collector by cutting.

8. A negative electrode sheet according to claim 6, wherein said restraint region is provided on said current collector by punching.

9. The negative electrode plate of claim 6, wherein the restraining region is square or arc in shape.

10. The negative electrode tab of claim 6, wherein the width of the restraining area is greater than the width of the tab.

11. A negative electrode tab according to claim 6, wherein a lead region is provided between the tab and the active material.

12. A negative electrode tab according to claim 11, wherein the lead region is provided on the current collector by punching or pressing.

13. The negative pole piece of claim 6, wherein the support layer is made of a polymer.

14. The negative electrode tab of claim 6, wherein the support layer has a thickness of 2 to 5 microns.

15. The negative electrode plate of claim 6, wherein the first conductive layer and the second conductive layer are made of copper or copper alloy.

16. The negative electrode plate of claim 6, wherein the thickness of the first conductive layer and the second conductive layer is 0.2 microns to 3 microns.

17. A battery having a negative electrode tab according to any one of claims 1 to 16.

18. An object having a battery according to claim 17, wherein the object is an electronic device or a vehicle.