CN215988907U

CN215988907U - Roll core and battery

Info

Publication number: CN215988907U
Application number: CN202122410535.4U
Authority: CN
Inventors: 徐腾飞; 彭宁
Original assignee: Zhuhai Cosmx Battery Co Ltd
Current assignee: Zhuhai Cosmx Battery Co Ltd
Priority date: 2021-09-30
Filing date: 2021-09-30
Publication date: 2022-03-08
Anticipated expiration: 2031-09-30

Abstract

The embodiment of the disclosure provides a winding core and a battery, wherein the winding core comprises a negative plate and a diaphragm, and the negative plate comprises a negative current collector; the distance between the inner concave point of the first bending area of the negative current collector along the winding direction and the inner concave point of the second bending area of the negative current collector along the winding direction is a first size L1; the distance from the inner concave point of the first bending area of the negative current collector along the winding direction to the winding head end of the negative current collector is a second size L2; the relationship between the first dimension L1 and the second dimension L2 includes: l2 is less than or equal to (0.5 multiplied by L1); the first bending area of the separator along the winding direction is at least partially overlapped with the first bending area of the negative current collector along the winding direction. Therefore, the thickness of the winding core is uniform, the space utilization effect inside the battery is improved, and the energy density of the battery is improved.

Description

Roll core and battery

Technical Field

The embodiment of the disclosure relates to the technical field of lithium batteries, in particular to a winding core and a battery.

Background

With the development of science and technology, the technology of lithium ion batteries is rapidly developed. Meanwhile, users also put higher demands on the quick charging capability and energy density of the lithium ion battery, and the quick charging lithium battery becomes the development trend of consumer lithium ion batteries.

The lithium ion battery with quick charge mainly adopts a tab middle-arranged structure, namely: the tab is welded in the middle of the pole piece, and the structure is favorable for reducing the internal resistance of the pole piece, reducing the polarization phenomenon of the battery during high-rate charge and discharge, and further improving the quick charging performance of the battery. High energy density lithium ion batteries are mainly embodied in the efficient use of the internal space of the battery.

However, in the prior art, the thickness of the winding core of the battery is not uniform, so that the space utilization effect in the battery is not good, and the energy density of the battery is influenced.

SUMMERY OF THE UTILITY MODEL

The embodiment of the disclosure provides a roll core and a battery, so that the thickness of the roll core is uniform, the space utilization effect inside the lithium ion battery is favorably improved, and the energy density of the lithium ion battery is favorably improved.

In a first aspect, an embodiment of the present disclosure provides a winding core, including a negative electrode sheet and a separator, where the negative electrode sheet includes a negative electrode current collector; the distance between the inner concave point of the first bending area of the negative current collector along the winding direction and the inner concave point of the second bending area of the negative current collector along the winding direction is a first size L1; the distance from the inner concave point of the first bending area of the negative current collector along the winding direction to the winding head end of the negative current collector is a second size L2; the relationship between the first dimension L1 and the second dimension L2 includes: l2 is less than or equal to (0.5 multiplied by L1); the first bending area of the separator along the winding direction is at least partially overlapped with the first bending area of the negative current collector along the winding direction.

The winding core provided by the embodiment of the disclosure comprises a negative plate, and the negative plate comprises a negative current collector. The distance between the inner concave points of the first bending area of the negative current collector along the winding direction and the inner concave points of the second bending area of the negative current collector along the winding direction is set to be a first size L1; setting the distance from the inner concave point of the first bending area of the negative current collector along the winding direction to the winding head end of the negative current collector to be a second size L2; and setting the relationship between the first dimension L1 and the second dimension L2 includes: l2 is less than or equal to (0.5 XL 1). Thereby can control the diaphragm at the in-process of coiling and overlap along the first district of buckling of direction of coiling and the first district of buckling of negative pole mass collector along the direction of coiling at least part, reduce the diaphragm and roll over a number of times at the center of rolling up the core, and then not only be favorable to reducing the whole thickness of rolling up the core, can avoid the diaphragm to roll over to turn over and overlap the thickness that increases the core part region moreover, so that the whole thickness of rolling up the core is more even, be favorable to improving the inside space utilization effect of battery, be favorable to improving the energy density of battery.

In the winding core as described above, optionally, the distance from the inner concave point of the first bending region of the separator in the winding direction to the winding head end of the separator is a third dimension L3; the relationship between the first dimension L1 and the third dimension L3 includes: l3 ≧ (0.5 XL 1).

The winding core as described above, optionally, the relationship between the first dimension L1 and the second dimension L2 further includes: l2 ≧ (0.1 × L1).

The winding core as described above, optionally, the relationship between the first dimension L1 and the third dimension L3 further includes: l3 is less than or equal to (0.9 XL 1).

The winding core as described above, optionally, the winding core further includes a positive electrode sheet, the first bending region of the positive electrode sheet along the winding direction and the second bending region of the negative electrode sheet along the winding direction at least partially overlap, and the winding head end of the positive electrode sheet extends to be close to the first bending region of the negative electrode sheet along the winding direction.

According to the winding core, optionally, the negative electrode sheet further includes a first negative electrode active layer and a second negative electrode active layer, the first negative electrode active layer is coated on one surface of the negative electrode current collector, which is away from the winding center of the winding core, and the second negative electrode active layer is coated on one surface of the negative electrode current collector, which is towards the winding center of the winding core; the winding head end of the first negative electrode active layer and the winding head end of the second negative electrode active layer both exceed the winding head end of the positive plate.

According to the winding core, optionally, the first negative electrode active layer covers the first bending region of the negative electrode current collector in the winding direction, and the projection of the winding head end of the first negative electrode active layer in the thickness direction of the winding core is connected with or has a distance from the projection of the winding head end of the positive electrode plate in the thickness direction of the winding core.

The winding core as described above, optionally, a distance between a winding head end of the first negative electrode active layer and an inner concave point of the first bending region of the negative electrode current collector in the winding direction is a fourth dimension L4; the distance between the winding head end of the positive plate and the inner concave point of the second bending area of the negative current collector along the winding direction is a fifth dimension L5; the relationship between the fourth dimension L4, the fifth dimension L5, and the first dimension L1 is: l4+ L5 ═ L1.

According to the winding core, optionally, the second negative electrode active layer covers the third bending region of the negative electrode current collector in the winding direction, and the projection of the winding head end of the second negative electrode active layer in the thickness direction of the winding core is connected with or has a gap with the projection of the winding head end of the positive electrode plate in the thickness direction of the winding core.

The winding core as described above, optionally, a distance between a winding head end of the second negative electrode active layer and an inner concave point of the first bending region of the negative electrode current collector in the winding direction is a sixth dimension L6; the distance between the winding head end of the positive plate and the inner concave point of the second bending area of the negative current collector along the winding direction is a fifth dimension L5; the relationship between the sixth dimension L6, the fifth dimension L5, and the first dimension L1 is: l6+ L5 ═ L1.

In the winding core described above, optionally, the winding head end of the first negative electrode active layer is aligned with the winding head end of the second negative electrode active layer.

In a second aspect, embodiments of the present disclosure provide a battery including a case and a jelly roll as described above, the jelly roll being enclosed in the case.

The battery provided by the embodiment of the disclosure comprises a shell and a winding core, wherein the winding core is packaged in the shell. Under the condition that the unevenness of the surface of the roll core is improved, the flatness of the battery is also improved, so that the interface bonding effect of the formed battery is improved, and the purposes of prolonging the cycle life, solving the expansion problem and solving the deformation problem of the battery are finally achieved.

The winding core comprises a negative plate, and the negative plate comprises a negative current collector. The distance between the inner concave points of the first bending area of the negative current collector along the winding direction and the inner concave points of the second bending area of the negative current collector along the winding direction is set to be a first size L1; setting the distance from the inner concave point of the first bending area of the negative current collector along the winding direction to the winding head end of the negative current collector to be a second size L2; and setting the relationship between the first dimension L1 and the second dimension L2 includes: l2 is less than or equal to (0.5 XL 1). Thereby can control the diaphragm at the in-process of coiling and overlap along the first district of buckling of direction of coiling and the first district of buckling of negative pole mass collector along the direction of coiling at least part, reduce the diaphragm and roll over a number of times at the center of rolling up the core, and then not only be favorable to reducing the whole thickness of rolling up the core, can avoid the diaphragm to roll over to turn over and overlap the thickness that increases the core part region moreover, so that the whole thickness of rolling up the core is more even, be favorable to improving the inside space utilization effect of battery, be favorable to improving the energy density of battery.

In addition to the technical problems solved by the embodiments of the present disclosure, the technical features constituting the technical solutions, and the advantages brought by the technical features of the technical solutions, further technical problems solved by the winding core and the battery provided by the embodiments of the present disclosure, other technical features included in the technical solutions, and advantages brought by the technical features will be further described in detail in the detailed description.

Drawings

In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present disclosure, and for those skilled in the art, other drawings can be obtained according to the drawings without inventive labor.

Fig. 1 is a schematic cross-sectional view of a winding core in the related art;

fig. 2 is a first schematic cross-sectional view of a winding core provided in the embodiment of the present disclosure;

fig. 3 is a schematic cross-sectional view of a core according to an embodiment of the present disclosure.

Description of reference numerals:

100-negative pole piece;

110 — first negative active layer;

120-a second negative active layer;

130-a negative current collector;

200-a membrane;

300-positive plate.

Detailed Description

Fig. 1 is a schematic cross-sectional view of a winding core in the related art. Referring to fig. 1, in the related art, the winding core mainly includes a negative electrode tab 10, a positive electrode tab 30, a separator 20, a negative electrode tab 11, and a positive electrode tab 31, the negative electrode tab 11 is welded at a middle position of the negative electrode tab 10, the positive electrode tab 31 is welded at a middle position of the positive electrode tab 30, and the negative electrode tab 10, the positive electrode tab 30, and the separator 20 are stacked in a predetermined order and wound in the same direction from a winding head end to finally form the winding core. In the related art, because the empty foil area at the winding head end of the negative electrode sheet 10 extends relatively long, the separator 20 needs to be folded once more at the center of the winding core to better cover the empty foil area of the negative electrode sheet 10, and meanwhile, the winding is convenient for the winding equipment; moreover, the membrane which is turned over once more usually only extends half of the inner width W of the winding core, namely, the membrane 20 which is turned over once more increases the thickness of the partial area of the winding core, so that the thickness of the winding core is not uniform, the whole thickness of the winding core is increased, the space utilization effect inside the battery is poor, and the energy density of the battery is influenced.

In order to solve the technical problem, an embodiment of the present disclosure provides a winding core, which includes a negative electrode tab including a negative electrode current collector. The distance between the inner concave points of the first bending area of the negative current collector along the winding direction and the inner concave points of the second bending area of the negative current collector along the winding direction is set to be a first size L1; setting the distance from the inner concave point of the first bending area of the negative current collector along the winding direction to the winding head end of the negative current collector to be a second size L2; and setting the relationship between the first dimension L1 and the second dimension L2 includes: l2 is less than or equal to (0.5 XL 1). Thereby can control the diaphragm at the in-process of coiling and overlap along the first district of buckling of direction of coiling and the first district of buckling of negative pole mass collector along the direction of coiling at least part, reduce the diaphragm and roll over a number of times at the center of rolling up the core, and then not only be favorable to reducing the whole thickness of rolling up the core, can avoid the diaphragm to roll over to turn over and overlap the thickness that increases the core part region moreover, so that the whole thickness of rolling up the core is more even, be favorable to improving the inside space utilization effect of battery, be favorable to improving the energy density of battery.

In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure will be described clearly and completely with reference to the drawings in the embodiments of the present disclosure, and it is obvious that the described embodiments are some, but not all, embodiments of the present disclosure. All other embodiments, which can be obtained by a person skilled in the art without making creative efforts based on the embodiments of the present disclosure, belong to the protection scope of the embodiments of the present disclosure.

The winding core comprises a positive plate, a diaphragm and a negative plate, wherein the positive plate, the diaphragm and the negative plate are arranged in a laminated mode, and the diaphragm is arranged between the positive plate and the negative plate to separate the positive plate from the negative plate and prevent the positive plate from contacting with the negative plate and from short circuit. The diaphragm can make lithium ions in the electrolyte pass through so as to ensure the normal operation of the lithium ion battery. The positive electrode sheet, separator, and negative electrode sheet, which are stacked, are wound from one end to the other end to form a winding core. The winding head end refers to the end at which winding starts, and the winding tail end refers to the end at which winding ends. After winding, the winding head end is located in the central area of the winding core, and the winding tail end is located on the outer surface of the winding core. The positive plate, the negative plate and the diaphragm are provided with winding head ends and winding tail ends, the positive plate comprises a positive current collector and a positive active layer, and the positive current collector and the positive active layer are provided with winding head ends and winding tail ends; the negative plate comprises a negative current collector and a negative active layer, wherein the negative current collector and the negative active layer are both provided with a winding head end and a winding tail end.

Example one

Fig. 2 is a first schematic cross-sectional view of a winding core provided in the embodiment of the present disclosure; fig. 3 is a schematic cross-sectional view of a core according to an embodiment of the present disclosure.

Referring to fig. 1 to 3, the present embodiment provides a jelly roll including a negative electrode sheet 100 and a separator 200, the negative electrode sheet 100 including a negative electrode collector 130. For example, the negative current collector 130 may be made of copper foil, and of course, the negative current collector 130 may be made of other materials according to actual needs as long as the requirement of the winding core can be met.

A distance between the inner concave point of the first bent region of the negative electrode current collector 130 in the winding direction and the inner concave point of the second bent region of the negative electrode current collector 130 in the winding direction is a first dimension L1. The distance from the inner concave point of the first bending region of the negative electrode current collector 130 in the winding direction to the winding head end of the negative electrode current collector 130 is a second dimension L2. The relationship between the first dimension L1 and the second dimension L2 includes: l2 is less than or equal to (0.5 XL 1). Illustratively, the size of L2 may be (0.1 × L1), (0.2 × L1), (0.3 × L1), (0.4 × L1), or (0.5 × L1), and the like.

The winding head end of the negative electrode current collector 130 generally has a blank foil area where no negative electrode active layer is disposed, and the length of the second dimension L2 of the winding head end of the negative electrode current collector 130, that is, the length of the blank foil area, is limited, so that the material saving and the cost saving are facilitated; but also facilitates shortening the length of the separator 200 to ensure an even thickness of the jelly roll.

The first bending region of the separator 200 along the winding direction is at least partially overlapped with the first bending region of the negative current collector 130 along the winding direction, that is, the first bending region of the separator 200 along the winding direction and the first bending region of the negative current collector 130 along the winding direction may be completely overlapped, or may be partially overlapped, it can be understood that the first bending region of the separator 200 along the winding direction and the first bending region of the negative current collector 130 along the winding direction are located on the same side of the winding core, so that the winding head end of the separator 200 may not be folded as one extra edge in the prior art scheme of fig. 1, thereby avoiding partial overlapping of the separator 200, and facilitating keeping the thickness of the winding core uniform.

In some alternative embodiments, the distance from the inner concave point of the first bending region of separator 200 in the winding direction to the winding head end of separator 200 is third dimension L3. The relationship between the first dimension L1 and the third dimension L3 includes: l3 ≧ (0.5 XL 1). Illustratively, the size of L3 may be (0.5 × L1), (0.6 × L1), (0.7 × L1), (0.8 × L1), or (0.9 × L1), and the like. Setting the distance from the inner concave point of the first bending area of the diaphragm along the winding direction to the winding head end of the diaphragm to be a third size L3; and setting the relationship between the first dimension L1 and the third dimension L3 includes: l3 is not less than (0.5 xL 1), so that the diaphragm can cover the empty foil area at the winding head end of the negative current collector, and the safety and the reliability of the battery are guaranteed.

Optionally, the relationship between the first dimension L1 and the second dimension L2 further comprises: l2 ≧ (0.1 xl 1), so that a sufficient length is reserved from the concave point of the first bending region of the negative current collector 130 along the winding direction to the second dimension L2 of the winding head end of the negative current collector 130, so as to facilitate the winding of the winding core and the coating of the negative active layer on the negative current collector 130.

Optionally, the relationship between the first dimension L1 and the third dimension L3 further includes: l3 is less than or equal to (0.9 × L1), so that the length from the inner concave point of the first bending region of the separator 200 in the winding direction to the third dimension L3 of the winding head end of the separator 200 is limited within a certain range, the winding head end of the separator 200 is prevented from extending too long, the winding head end of the separator 200 and the second bending region of the negative electrode sheet 100 are prevented from interfering and turning over, and the thickness of the winding core is kept uniform.

Referring to fig. 2 and 3, the winding core further includes a positive electrode sheet 300, and a first bending region of the positive electrode sheet 300 along the winding direction and a second bending region of the negative electrode sheet 100 along the winding direction at least partially overlap each other, that is, the first bending region of the positive electrode sheet 300 along the winding direction and the second bending region of the negative electrode sheet 100 along the winding direction may completely overlap each other or partially overlap each other, and it can be understood that the first bending region of the positive electrode sheet 300 along the winding direction and the second bending region of the negative electrode sheet 100 along the winding direction are located on the same side of the winding core. The winding head end of the positive electrode sheet 300 extends to be close to the first bending region of the negative electrode sheet 100 in the winding direction.

Exemplarily, the positive plate 300 includes a positive current collector, a first positive active layer and a second positive active layer, the positive current collector may be made of aluminum foil, and of course, the positive current collector may be made of other materials according to actual needs, as long as the requirement of the winding core can be satisfied. The first positive electrode active layer and the second positive electrode active layer are made of the same material. The first positive electrode active layer is arranged to be coated on one surface of the positive electrode current collector, which faces to the center of the roll core, and the winding head end of the first positive electrode active layer can be flush with the winding head end of the positive electrode current collector; set up the coating of the anodal active layer of second simultaneously and draw back to the one side at the center of core of anodal mass flow body, the coiling head end of the anodal active layer of second can with the coiling head end parallel and level of anodal mass flow body to make first anodal active layer and the anodal active layer of second cover the coiling head end of anodal mass flow body completely, so that make full use of the length of anodal mass flow body.

Referring to fig. 2 and 3, the negative electrode sheet 100 further includes a first negative electrode active layer 110 and a second negative electrode active layer 120, and the first negative electrode active layer 110 and the second negative electrode active layer 120 are made of the same material. The first negative electrode active layer 110 is coated on one surface of the negative electrode collector 130 facing away from the winding center of the winding core, and the second negative electrode active layer 120 is coated on one surface of the negative electrode collector 130 facing the winding center of the winding core.

Illustratively, the winding head of first negative electrode active layer 110 and the winding head of second negative electrode active layer 120 each extend beyond the winding head of the positive electrode sheet. That is, the first negative electrode active layer 110 and the second negative electrode active layer 120 may completely cover the positive electrode sheet 300, thereby facilitating to ensure the performance of the roll core. It is understood that the length of the winding head end of the first negative electrode active layer 110, and the winding head end of the second negative electrode active layer 120 beyond the winding head end of the positive electrode sheet 300 may not be too long as it can completely cover the positive electrode sheet 300.

For example, the winding head end of the first negative electrode active layer 110 may be indented inward in the winding direction to leave a void foil region on the side of the negative electrode collector 130 facing away from the winding center of the winding core. The winding head end of the second negative electrode active layer 120 may be indented inward in the winding direction to leave a void foil region on the side of the negative electrode collector 130 facing the winding center of the winding core.

Referring to fig. 3, the first negative active layer 110 may cover a first bending region of the negative current collector 130 in the winding direction, and a projection of a winding head end of the first negative active layer 110 in the thickness direction of the winding core is connected to or spaced apart from a projection of a winding head end of the positive electrode sheet 300 in the thickness direction of the winding core.

Illustratively, a distance between a winding head end of the first negative electrode active layer 110 and an inner concave point of the first bending region of the negative electrode current collector 130 in the winding direction is a fourth dimension L4. The distance between the winding head end of the positive electrode tab 300 and the concave point of the second bent region of the negative electrode collector 130 in the winding direction is a fifth dimension L5. The relationship between the fourth dimension L4, the fifth dimension L5, and the first dimension L1 is: l4+ L5 ═ L1. The winding head end of the first negative electrode active layer 110 and the thickness of the fourth dimension L4 between the concave points of the first bending area of the negative electrode current collector 130 along the winding direction can compensate the thickness of the winding core at one end of the first bending area of the negative electrode plate 100, so that the thickness difference of the surface of the winding core is favorably reduced, and the thickness of the winding core tends to be uniform.

Referring to fig. 3, the second negative active layer 120 covers the third bending region of the negative current collector 130 in the winding direction, and a projection of the winding head end of the second negative active layer 120 in the thickness direction of the winding core is connected to or spaced apart from a projection of the winding head end of the positive electrode sheet 200 in the thickness direction of the winding core.

Illustratively, the distance between the winding head end of the second negative electrode active layer 120 and the concave point of the first bent region of the negative electrode collector 130 in the winding direction is a sixth dimension L6. The distance between the winding head end of the positive electrode tab 300 and the concave point of the second bent region of the negative electrode collector 130 in the winding direction is a fifth dimension L5. The relationship between the sixth dimension L6, the fifth dimension L5, and the first dimension L1 is: l6+ L5 ═ L1. The winding head end of the second negative electrode active layer 120 and the thickness of the sixth dimension L6 between the concave points of the first bending region of the negative electrode current collector 130 along the winding direction can compensate the thickness of the winding core at one end of the first bending region of the negative electrode sheet 100, thereby being beneficial to reducing the thickness difference of the surface of the winding core and leading the thickness of the winding core to tend to be uniform.

Optionally, the winding head end of first negative electrode active layer 110 aligns with the winding head end of second negative electrode active layer 120, thereby being favorable to making the winding head end of first negative electrode active layer 110 and the winding head end of second negative electrode active layer 120 can be better with the butt joint of the winding head end of positive plate 300, so that the better thickness of the core of making up at the one end of the first bending region of negative plate 100, thereby being favorable to reducing the thickness difference on the core surface, the thickness of the core of making roll tends to be even.

In summary, the winding core provided by the embodiment of the present disclosure includes the negative electrode sheet 100, and the negative electrode sheet 100 includes the negative electrode collector 130. By setting the inner concave point of the first bending area of the negative current collector 130 along the winding direction and the distance between the inner concave points of the second bending area of the negative current collector 130 along the winding direction to be the first size L1; setting the distance from the inner concave point of the first bending area of the negative current collector 130 along the winding direction to the winding head end of the negative current collector 130 to be a second size L2; and setting the relationship between the first dimension L1 and the second dimension L2 includes: l2 is less than or equal to (0.5 XL 1). Thereby can control diaphragm 200 along the first district of buckling of direction of coiling and negative current collector 130 along the first district of buckling of direction of coiling at least part overlap at the in-process of coiling, reduce diaphragm 200 and roll up a number of times at the center of rolling up the core, and then not only be favorable to reducing the whole thickness of rolling up the core, can avoid diaphragm 200 to roll up a thickness that overlaps and increase the core part region, so that the whole thickness of rolling up the core is more even, be favorable to improving the inside space utilization effect of battery, be favorable to improving the energy density of battery.

Meanwhile, the distance from the inner concave point of the first bending region of the separator 200 in the winding direction to the winding head end of the separator 200 is set to be a third dimension L3; and setting the relationship between the first dimension L1 and the third dimension L3 includes: l3 is not less than 0.5 xL 1, so that the separator 200 can cover the empty foil area at the winding head end of the negative current collector 130, and the safety and reliability of the battery can be guaranteed.

The specific embodiment is as follows:

taking 475477 as an example, referring to fig. 1, the width in the roll core is 47mm, the thickness of the positive plate is 127um, the thickness of the negative plate with the negative active layer coated on one side is 57um, the thickness of the negative current collector is 6um, the thickness of the diaphragm is 11um, and the size of the negative active layer longer than the head of the positive and negative electrode is 5 mm.

When a conventional structure is adopted, referring to fig. 1, the first bending region of the negative plate is not covered by the negative active layer, the distance between the head of the negative active layer and the first bending region of the negative plate is 0.5mm, the length of the negative current collector extending from the first bending region of the negative plate to the winding head end is 25mm, and the length of the diaphragm extending from the first bending region of the negative plate to the winding head end is 78mm (with a reverse fold).

After optimization, referring to fig. 3, the fourth dimension L4 of the first negative active layer is 4mm, the sixth dimension L6 of the second negative active layer is 3.5mm, the empty foil at the head of the negative current collector is 12mm, and the length of the separator extending from the first bending region of the negative electrode sheet to the head of the winding is 28 mm.

By contrast, referring to fig. 3, compared to the conventional structure, by providing the first negative electrode active layer to extend a fourth dimension L4 toward the winding head end of the negative electrode current collector, where L4 is a distance between the winding head end of the first negative electrode active layer 110 and the concave point of the first bending region of the negative electrode current collector 130 in the winding direction; set up the winding head end extension sixth size L6 of second negative pole active layer orientation negative pole mass flow body, wherein, L6 is the winding head end of second negative pole active layer 120, and, the distance between the indent point of the first bending region of negative pole mass flow body 130 along the direction of convoluteing, and the head of first negative pole active layer and second negative pole active layer covers and is longer than the head of positive plate, thereby make the thickness of the first bending region that is close to the negative plate of book core increase 2 (57-6) ═ 102um thickness, so that the thickness range of the book core is reduced to 25um by 127um, the battery inner circle thickness uniformity has been promoted, be favorable to becoming the interface uniformity.

Through the comparison discovery, refer to fig. 2 and 3, compare in conventional structure, through the length of optimizing the empty foil of negative current collector head and the length that the diaphragm is turned back, make the diaphragm of negative electrode head reduce 4 layers, 4 x 11 ═ 44um promptly, effectively reduce the whole thickness of book core, be favorable to make full use of battery inner space, have certain promotion to battery volume density.

Example two

On the basis of the first embodiment, the embodiment provides a battery, which comprises a shell and a winding core, wherein the winding core is packaged in the shell. Illustratively, the housing may be an aluminum plastic film housing.

The winding core provided by the present embodiment has the same structure as the winding core in the first embodiment, and can bring the same or similar technical effects, specifically referring to the first embodiment.

The battery provided by the embodiment comprises a shell and a winding core, wherein the winding core is packaged in the shell. The whole thickness of the roll core is reduced, and the whole thickness of the roll core is uniform, so that the whole thickness of the battery is reduced, the uniformity of the whole thickness of the battery is improved, the space utilization effect inside the battery is improved, and the energy density of the battery is improved.

In the description of the embodiments of the present disclosure, it should be noted that the terms "mounted," "connected," and "connected" are used broadly and can be, for example, either fixedly or detachably connected unless explicitly stated or limited otherwise; can be mutually contacted or integrated; can be mechanically or electrically connected; either directly or indirectly through intervening media, or through the communication between two elements. The specific meanings of the above terms in the embodiments of the present disclosure can be understood by those of ordinary skill in the art through specific situations.

The terms "first" and "second" in the description and claims of the present application and the description of the above-described figures are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the embodiments of the present disclosure, and not for limiting the same; although embodiments of the present disclosure have been described in detail with reference to the foregoing embodiments, those skilled in the art will appreciate that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. The winding core is characterized by comprising a negative plate and a diaphragm, wherein the negative plate comprises a negative current collector; the distance between the inner concave point of the first bending area of the negative current collector along the winding direction and the inner concave point of the second bending area of the negative current collector along the winding direction is a first size L1; the distance from the inner concave point of the first bending area of the negative current collector along the winding direction to the winding head end of the negative current collector is a second size L2; the relationship between the first dimension L1 and the second dimension L2 includes: l2 is less than or equal to (0.5 multiplied by L1);

the first bending area of the separator along the winding direction is at least partially overlapped with the first bending area of the negative current collector along the winding direction.

2. The winding core according to claim 1, wherein the distance from the concave point of the first bending region of the separator in the winding direction to the winding head end of the separator is a third dimension L3; the relationship between the first dimension L1 and the third dimension L3 includes: l3 ≧ (0.5 XL 1).

3. The winding core of claim 1, wherein the relationship between the first dimension L1 and the second dimension L2 further comprises: l2 ≧ (0.1 × L1).

4. The winding core of claim 2, wherein the relationship between the first dimension L1 and the third dimension L3 further comprises: l3 is less than or equal to (0.9 XL 1).

5. The winding core according to claim 1, further comprising a positive electrode sheet, wherein a first bending region of the positive electrode sheet along the winding direction and a second bending region of the negative electrode sheet along the winding direction at least partially overlap, and the winding head end of the positive electrode sheet extends to be close to the first bending region of the negative electrode sheet along the winding direction.

6. The winding core according to claim 5, wherein the negative electrode sheet further comprises a first negative electrode active layer and a second negative electrode active layer, the first negative electrode active layer is coated on one surface of the negative electrode current collector, which is far away from the winding center of the winding core, and the second negative electrode active layer is coated on one surface of the negative electrode current collector, which is far towards the winding center of the winding core;

the winding head end of the first negative electrode active layer and the winding head end of the second negative electrode active layer both exceed the winding head end of the positive plate.

7. The winding core according to claim 6, wherein the first negative electrode active layer covers a first bending region of the negative electrode current collector in a winding direction, and a projection of a winding head end of the first negative electrode active layer in the thickness direction of the winding core is connected with or has a distance from a projection of a winding head end of the positive electrode sheet in the thickness direction of the winding core.

8. The winding core according to claim 6, wherein a distance between a winding head end of the first negative electrode active layer and an inner concave point of a first bending region of the negative electrode current collector in a winding direction is a fourth dimension L4; the distance between the winding head end of the positive plate and the inner concave point of the second bending area of the negative current collector along the winding direction is a fifth dimension L5; the relationship between the fourth dimension L4, the fifth dimension L5, and the first dimension L1 is: l4+ L5 ═ L1.

9. The winding core according to claim 6, wherein the second negative electrode active layer covers a third bending region of the negative electrode current collector in the winding direction, and a projection of a winding head end of the second negative electrode active layer in the thickness direction of the winding core is connected to or spaced from a projection of a winding head end of the positive electrode sheet in the thickness direction of the winding core.

10. The winding core according to claim 6, wherein a distance between one end of the second negative electrode active layer close to the winding head end of the negative electrode current collector and the concave point of the first bending region of the negative electrode current collector in the winding direction is a sixth dimension L6; the distance between the winding head end of the positive plate and the inner concave point of the second bending area of the negative current collector along the winding direction is a fifth dimension L5; the relationship between the sixth dimension L6, the fifth dimension L5, and the first dimension L1 is: l6+ L5 ═ L1.

11. The winding core according to any one of claims 6 to 10, characterized in that a winding head end of the first negative electrode active layer is aligned with a winding head end of the second negative electrode active layer.

12. A battery comprising a can and the jellyroll of any of claims 1-11, wherein the jellyroll is enclosed within the can.