阅读说明：本技术 电芯及电池 (Battery core and battery ) 是由 胡贤飞 陈博 余正发 彭冲 李俊义 徐延铭 于 2021-03-09 设计创作，主要内容包括：本申请提供一种电芯及电池,其中,电芯包括正极片、负极片和隔膜,正极片和负极片层叠设置,正极片和负极片之间具有至少一片隔膜,负极片设有至少两个间隔设置的第一极耳。通过在负极片上间隔设置多个第一极耳,可以使电流较均匀的分布在负极片上。负极片上各处电流密度相差较小,可以降低负极耳附近析锂风险,从而降低了电池的安全隐患。(The application provides an electric core and battery, wherein, electric core includes positive plate, negative pole piece and diaphragm, and positive plate and the range upon range of setting of negative pole piece have an at least diaphragm between positive plate and the negative pole piece, and the negative pole piece is equipped with the first utmost point ear that two at least intervals set up. Through set up a plurality of first utmost point ears at the interval on the negative pole piece, can make the more even distribution of electric current on the negative pole piece. The current density difference of each part on the negative pole piece is small, the risk of lithium precipitation near the negative pole ear can be reduced, and therefore the potential safety hazard of the battery is reduced.)

1. The battery cell is characterized by comprising a positive plate, a negative plate and a diaphragm;

the negative plate is provided with at least two first tabs arranged at intervals;

the positive plate comprises a positive current collector and a second tab, wherein a first active material layer is arranged on each of a first surface and a second surface of the positive current collector, a groove for exposing the positive current collector is formed in each first active material layer, the second tab is arranged in each groove, and the second tab is electrically connected with the positive current collector;

the positive plate and the negative plate are arranged in a stacked mode, and at least one diaphragm is arranged between the positive plate and the negative plate.

2. The battery cell of claim 1, wherein the positive electrode sheet and the negative electrode sheet are stacked and then wound according to a preset number of turns, and the number of the first tabs is less than or equal to the preset number of turns.

3. The electrical core of claim 2, wherein the number of the preset folds is 2 to 3 times the number of the first tabs.

4. The cell of claim 1, wherein the negative plate comprises a negative current collector provided with a plurality of raised areas.

5. The cell of claim 1, wherein the groove is a quadrilateral area, and wherein three sides of the groove adjoin the first active material layer.

6. The cell of claim 5, wherein the difference between the distance from the groove to the first edge of the first active material layer and the distance from the groove to the second edge of the first active material layer is no more than one-tenth of the longest length of the first active material layer;

wherein the first edge of the first active material layer and the second edge of the first active material layer are opposite edges, and both the first edge of the first active material layer and the second edge of the first active material layer are outermost edges of the first active material layer.

7. The electrical core of claim 6, wherein the groove is equidistant from a first edge of the first active material layer as the groove is equidistant from a second edge of the first active material layer.

8. The cell of claim 5, wherein the positive tab comprises at least two of the second tabs.

9. The battery cell of claim 1, wherein the positive electrode sheet and the negative electrode sheet are stacked and wound to form the battery cell, and the outermost layer of the battery cell is a positive electrode current collector which is not covered by the first active material layer.

10. A battery comprising a cell according to any of claims 1 to 9.

Technical Field

The application relates to the field of lithium ion batteries, in particular to a battery core and a battery.

Background

With the development of battery technology, the application of batteries in human life is increasingly wide, and the requirements of people on the performance of batteries are also increasingly high. In order to increase the charging speed of the battery, a structure with a middle-arranged negative electrode tab is generally adopted. However, because the current of the negative electrode plate passes through the centrally-arranged electrode lug, the current density at the position of the negative electrode lug is higher than the current density at other positions on the negative electrode plate, lithium precipitation easily occurs in the area near the negative electrode lug in the charging process, and the potential safety hazard is high.

Content of application

The embodiment of the application provides an electric core and a battery, and solves the problems that lithium separation easily occurs in the area near a negative electrode tab and the potential safety hazard is high in the battery charging process.

In order to achieve the above object, in a first aspect, an embodiment of the present application provides a battery cell, where the battery cell includes a positive plate, a negative plate, and a separator;

the negative plate is provided with at least two first tabs arranged at intervals;

the positive plate comprises a positive current collector and a second lug, wherein a first active material layer is arranged on each of a first surface and a second surface of the positive current collector, a groove for exposing the current collector is formed in each first active material layer, and the second lug is arranged in each groove;

the positive plate and the negative plate are arranged in a stacked mode, and at least one diaphragm is arranged between the positive plate and the negative plate.

Optionally, the first tabs are uniformly arranged on the negative plate at intervals.

Optionally, the positive electrode sheet and the negative electrode sheet are wound according to a preset number of turns after being stacked, and the number of the first tabs is smaller than or equal to the preset number of turns.

Optionally, the number of the preset folds is 2 to 3 times of the number of the first tabs.

Optionally, the negative electrode plate includes a negative electrode current collector, and the negative electrode current collector is provided with a plurality of protruding regions.

Optionally, the groove is a quadrilateral area, three sides of the groove are adjacent to the first active material layer, and the second tab is disposed in the groove.

Optionally, the difference between the distance from the groove to the first edge of the first active material layer and the distance from the groove to the second edge of the first active material layer is not more than one tenth of the longest length of the first active material layer;

wherein the first edge of the first active material layer and the second edge of the first active material layer are opposite edges, and both the first edge of the first active material layer and the second edge of the first active material layer are outermost edges of the first active material layer.

Optionally, the distance from the groove to the first edge of the first active material layer is equal to the distance from the groove to the second edge of the first active material layer.

Optionally, the positive plate includes at least two second tabs.

Optionally, the positive electrode plate and the negative electrode plate are stacked and wound to form the battery cell, and the outermost layer of the battery cell is a positive electrode current collector which is not covered with the first active material layer.

In a second aspect, an embodiment of the present application provides a battery, which includes the battery cell according to the first aspect.

In the embodiment of the application, the battery cell comprises a positive plate, a negative plate and a diaphragm, the positive plate and the negative plate are stacked, at least one diaphragm is arranged between the positive plate and the negative plate, and the negative plate is provided with at least two first tabs arranged at intervals. Through set up a plurality of first utmost point ears at the interval on the negative pole piece, can make the more even distribution of electric current on the negative pole piece. The current density difference of each part on the negative pole piece is small, the risk of lithium precipitation near the negative pole ear can be reduced, and therefore the potential safety hazard of the battery is reduced.

Drawings

For a clear explanation of the technical solutions in the embodiments of the present application, the drawings of the specification are described below, it is obvious that the following drawings are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the listed drawings without any inventive effort.

Fig. 1 is one of schematic structural diagrams of a negative electrode sheet provided in an embodiment of the present application;

fig. 2 is a second schematic structural diagram of a negative electrode sheet provided in the embodiment of the present application;

fig. 3 is one of schematic structural diagrams of a positive electrode sheet provided in an embodiment of the present application;

fig. 4 is a second schematic structural diagram of a positive electrode plate provided in the embodiment of the present application;

fig. 5 is a schematic structural diagram of a battery cell provided in an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. On the basis of the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without any creative effort belong to the protection scope of the present application.

Referring to fig. 1, 2, 3, 4 and 5, an embodiment of the present application provides a battery cell including a positive electrode tab, a negative electrode tab and a separator 30;

the negative plate is provided with at least two first tabs 12 arranged at intervals;

the positive plate comprises a positive current collector 21 and a second tab 23, wherein a first active material layer 22 is arranged on each of a first surface and a second surface of the positive current collector 21, a groove 24 for exposing the current collector is formed in each first active material layer, and the second tab 23 is arranged in each groove 24;

the positive plate and the negative plate are arranged in a laminated manner, and at least one diaphragm 30 is arranged between the positive plate and the negative plate.

Specifically, referring to fig. 1 and 2, the negative electrode sheet includes a negative electrode current collector 11, the material of the negative electrode current collector 11 may be a copper foil, a second active material layer 13 is coated on the negative electrode current collector 11, and the material of the second active material layer 13 may be graphite, hard carbon, silicon oxide, etc. A plurality of first tabs 12 may be arranged at intervals on the first surface 1a of the negative electrode sheet by means of die cutting. The intervals between the adjacent first tabs 12 may be equal or unequal. The material of the positive electrode collector 21 may be an aluminum foil, and the groove 24 is a region not covered with the first active material layer 22. The first surface of the positive electrode collector 21, i.e., the first surface 2a of the positive electrode sheet, may be provided with a groove 24, and the second surface 2b of the positive electrode sheet may be provided with a groove 24 at a position corresponding to the groove 24. Referring to fig. 5, the positive electrode sheet, the separator 30, and the negative electrode sheet are stacked and wound to form a cell.

The separator 30 provided herein may be a conventional lithium battery separator, which includes a substrate and a coating layer, wherein the substrate may be a Polyethylene (PE) single-layer film, a polypropylene (PP) single-layer film, or a PP/PE/PP three-layer composite film, and the coating layer may be at least one of porous silicon dioxide, aluminum oxide, titanium dioxide, and zirconium dioxide. The diaphragm 30 is an insulator of the positive and negative pole pieces, and the diaphragm 30 is arranged between the positive and negative pole pieces, so that the resistance value in short circuit can be increased, the short-circuit current can be reduced, and the local heat balance failure can be prevented.

In the prior art, the negative plate usually adopts a tab middle-arranged structure. The current of the negative plate passes through the tab arranged in the middle, so that the current density at the tab is higher than those at other positions on the negative plate, lithium separation easily occurs in the area near the tab in the charging process, the lithium separation reaction is a fatal radical which causes the increase of the internal resistance of the battery, the attenuation of the capacity and the reduction of the coulombic efficiency, and in severe cases, potential safety hazards such as fire hazard, explosion and the like can be caused.

In the embodiment of the application, the battery cell comprises a positive plate, a negative plate and a diaphragm 30, the positive plate and the negative plate are stacked, at least one diaphragm 30 is arranged between the positive plate and the negative plate, and the negative plate is provided with at least two first tabs 12 arranged at intervals. The first tabs 12 are arranged on the negative plate at intervals, so that the current can be uniformly distributed on the negative plate. The current density difference of each part on the negative pole piece is small, the risk of lithium precipitation near the negative pole ear can be reduced, and therefore the potential safety hazard of the battery is reduced.

It should be noted that a plurality of the first tabs 12 may be disposed on the negative electrode sheet at relatively uniform intervals. Through setting up the comparatively even interval of a plurality of first utmost point ears 12 in the negative pole piece, can make the electric current distribute more evenly on the negative pole piece, further reduce the difference of each current density on the negative pole piece, reduce near the negative pole ear and educe lithium risk to reduce the potential safety hazard of battery.

Optionally, the positive electrode sheet and the negative electrode sheet are stacked and then wound according to a preset number of turns, and the number of the first tabs 12 is less than or equal to the preset number of turns.

Referring to fig. 5, it should be understood that after the positive and negative electrode sheets are wound in a predetermined number of turns, the plurality of first tabs 12 provided on the negative electrode sheet should be aligned so as to weld the plurality of first tabs 12 together into a final negative electrode tab. If the number of the first tabs 12 is greater than the preset fold number, some first tabs 12 cannot be aligned with other first tabs 12, and the final number of the negative tabs needs to be increased, so that the cost is increased. In order to reduce the cost, the number of the first tabs 12 is less than or equal to the preset number of turns, so that a plurality of first tabs 12 can be welded together to form a final negative tab.

Optionally, the number of the preset folds is 2 to 3 times of the number of the first tabs 12.

It should be understood that when the number of the first tabs 12 is less than or equal to the preset number of folds, in order to align the first tabs 12, at most one first tab 12 is disposed on each fold of the wound battery cell. During the charge and discharge of the battery, the volume of the battery expands, and the plurality of first tabs 12 welded together receive a force for separating the plurality of first tabs 12 from each other as the battery expands. Referring to fig. 5, the number of the first tabs 12 is half of the number of the preset folds or one third of the number of the preset folds, and the first tabs 12 may be all disposed on the first side of the center of the battery cell, so as to reduce the force generated by the expansion of the battery to separate the first tabs 12 from each other, thereby enhancing the connection reliability of the first tabs 12 and improving the safety of the battery cell.

Optionally, referring to fig. 2, the negative electrode tab includes a negative electrode collector 11, and the negative electrode collector 11 is provided with a plurality of convex regions 14.

Specifically, the convex region 14 is a region where the second active material layer 13 is not coated, and the convex region 14 may be formed by cutting the negative electrode collector 11. The raised area 14 is the first tab 12.

Alternatively, referring to fig. 3 and 4, the groove 24 is a quadrangular region, and the groove 24 has three sides adjacent to the first active material layer 22.

Specifically, the groove 24 is a region not covered with the first active material layer 22. The first surface of the positive electrode collector 21, i.e., the first surface 2a of the positive electrode sheet, may be provided with a groove 24, and the second surface 2b of the positive electrode sheet may be provided with a groove 24 at a position corresponding to the groove 24.

The recess 24 may be rectangular in shape, and the recess 24 has three sides adjacent to the first active material layer 22, in general, the recess 24 is disposed in the middle of the first active material layer 22. By providing the groove 24 in the middle of the first active material layer 22, the roll yield can be improved.

Optionally, the difference between the distance from the groove 24 to the first edge of the first active material layer 22 and the distance from the groove 24 to the second edge of the first active material layer 22 is not more than one tenth of the longest length of the first active material layer 22;

wherein the first edge of the first active material layer 22 and the second edge of the first active material layer 22 are opposite edges, and the first edge of the first active material layer 22 and the second edge of the first active material layer 22 are both the outermost peripheral edges of the first active material layer 22.

Specifically, the difference between the distance from the center point of the groove 24 to the first edge of the first active material layer 22 and the distance from the center point of the groove 24 to the second edge of the first active material layer 22 is not more than one tenth of the longest length of the first active material layer 22. That is, the groove 24 should be formed at the middle position of the first active material layer 22 as much as possible, by which the positive electrode tab resistance can be reduced, thereby increasing the battery charging speed.

Preferably, the center point of the groove 24 is located at the same distance from the first edge of the first active material layer 22 as the center point of the groove 24 is located at the same distance from the second edge of the first active material layer 22. The groove 24 is positioned at the middle of the first active material layer 22, and the impedance of the positive plate is lowest, so that the charging speed of the battery can be further improved.

Optionally, the positive plate includes at least two of the second tabs 23.

Specifically, there may be more than one groove 24, a plurality of grooves 24 may be provided on the positive plate, and a second tab 23 is provided on each groove 24, and the manner of providing the second tab 23 may be to adhere the second tab 23 by coating tab glue on the grooves 24.

Optionally, the positive electrode sheet and the negative electrode sheet are stacked and wound to form the battery cell, and the outermost layer of the battery cell is a positive electrode current collector 21 which is not covered by the first active material layer 22.

It should be understood that in the case that the outermost layer of the cell is the positive electrode current collector 21 not covered by the first active material layer 22, the rolling yield of the positive electrode sheet can be improved by interposing the second tab 23, that is, by disposing the second tab 23 in the groove 24 of the first active material layer, in which the current collector is exposed.

In a second aspect, an embodiment of the present application provides a battery, where the battery includes the battery cell provided in the foregoing embodiment. The structure and the working principle of the battery core may refer to the above embodiments, and are not described herein again. Because the battery provided by the embodiment of the present application includes the battery cell of the above embodiment, the battery provided by the embodiment of the present application has all the beneficial effects of the battery cell in the above embodiment.

The following briefly describes a manufacturing process of the battery provided in the embodiment of the present application.

Firstly, coating an active material layer on a positive plate and a negative plate;

secondly, cleaning and rolling the positive plate, and attaching a positive tab to obtain the positive plate shown in the figure 3;

thirdly, rolling and die cutting are carried out on the negative plate to obtain the negative plate shown in figure 2;

fourthly, stacking and winding the positive plate, the diaphragm and the negative plate to form the battery cell shown in fig. 5;

and fifthly, packaging, injecting liquid and forming the winding core to obtain the battery.

While the present embodiments have been described with reference to the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiments described above, which are meant to be illustrative and not restrictive, and that various changes may be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.