Lithium ion battery and negative plate

Abstract

The utility model relates to a lithium ion battery and a negative pole piece, the negative pole piece comprises a base material which is lengthwise arranged and comprises a first surface and a second surface which are oppositely arranged, and a first preset area for mounting a negative pole lug is reserved on the first surface and / or the second surface; the first active layer is arranged on the first surface and the second surface, at least one second preset area is reserved on the first active layer, and a set distance is reserved between the second preset area and the first preset area in the first direction; the first direction is the length direction of the base material; and the second active layer is arranged in the second preset area and is configured to cover at least one side of the first preset area after the negative plate forms the roll core. According to the negative plate, the second active layer is arranged in the second preset area of the first active layer, and the second active layer is configured to cover at least one side of the first preset area for mounting the negative tab after the negative plate forms the roll core, so that the fast charging capacity of the lithium ion battery can be effectively improved, and lithium precipitation at an imprinting position is avoided.

Description

Technical Field

[0001] The utility model relates to the field of lithium ion batteries, in particular to lithium ion batteries and negative electrode sheets. Background Art

[0002] In the related art, the negative electrode sheet of lithium-ion batteries (especially soft-pack lithium-ion batteries) is usually formed by placing a layer of active material on a substrate, and then attaching the negative electrode ear and winding it with the positive electrode sheet to form a winding core. However, the current lithium-ion batteries mostly adopt the production process of pressure formation. When lithium-ion batteries are subjected to pressure, the negative electrode sheet is prone to embossing at the corresponding position near the negative electrode ear. This embossed area is prone to lithium deposition in the lithium-ion battery under fast charging conditions. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide an improved negative electrode sheet, and further provide an improved lithium ion battery.

[0004] The technical solution adopted by the utility model to solve the technical problem is: the utility model constructs a negative electrode sheet, including:

[0005] The substrate is arranged in a longitudinal direction and includes a first surface and a second surface arranged opposite to each other, and a first preset area for installing a negative electrode ear is reserved on the first surface and / or the second surface;

[0006] A first active layer is disposed on the first surface and the second surface, at least one second preset area is reserved on the first active layer, and a set distance is reserved between the second preset area and the first preset area in a first direction; the first direction is the length direction of the substrate;

[0007] The second active layer is disposed in the second preset area and is configured to cover at least one side of the first preset area after the negative electrode sheet forms a winding core.

[0008] In some embodiments, the winding core has at least two negative electrode layers from the inside to the outside, and the minimum distance between the second active layer and the first preset area is configured to be greater than the distance between two adjacent negative electrode layers;

[0009] The set distance is configured to be greater than or equal to a minimum distance between the second active layer and the first preset area.

[0010] In some embodiments, the width of the second active layer in the first direction is greater than the width of the first preset area, and after the winding core is formed, an edge of the second active layer is disposed beyond an edge of the first preset area.

[0011] In some embodiments, the length of the portions of the edges on both sides of the second active layer that extend beyond the edge of the first preset area is greater than 0.5 mm.

[0012] In some embodiments, the thickness of the second active layer is 1-8 um.

[0013] In some embodiments, the first surface and / or the second surface comprises a first edge and a second edge arranged along a second direction; the second direction is a width direction of the substrate;

[0014] The first preset area extends from the first edge to the second edge along a second direction;

[0015] The second preset area extends from the first edge to the second edge along a second direction.

[0016] In some embodiments, in the second direction, the length of the second active layer is greater than or equal to the length of the first preset area.

[0017] In some embodiments, in the second direction, the length of the second active layer is 0.5 mm greater than that of the first preset area.

[0018] The utility model constructs a lithium-ion battery, comprising the negative electrode sheet, the positive electrode sheet, the positive electrode ear and the negative electrode ear described in the utility model, wherein the positive electrode ear is arranged on the positive electrode sheet; the negative electrode ear is arranged in a first preset area of ​​the negative electrode sheet; the positive electrode sheet and the negative electrode sheet are stacked and wound together to form a winding core, and the positive electrode ear and the negative electrode ear extend from one end of the winding core or respectively from both ends of the winding core.

[0019] In some embodiments, in the transverse direction of the winding core, the second active layer on the negative electrode sheet and the negative electrode ear are arranged from inside to outside and cover at least one side of the negative electrode ear.

[0020] The implementation of the lithium-ion battery and negative electrode sheet of the utility model has the following beneficial effects: the negative electrode sheet is configured to cover at least one side of the first preset area for installing the negative electrode ear after the negative electrode sheet forms a roll core, thereby effectively improving the fast charging capability of the lithium-ion battery and avoiding lithium deposition at the stamping site. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0022] Figure 1 It is a partial structural schematic diagram of a lithium-ion battery in some embodiments of the utility model;

[0023] Figure 2 yes Figure 1 A schematic cross-sectional view of a lithium-ion battery is shown. DETAILED DESCRIPTION

[0024] In order to have a clearer understanding of the technical features, purposes and effects of the present utility model, the specific implementation methods of the present utility model are now described in detail with reference to the accompanying drawings.

[0025] It should also be noted that, unless otherwise clearly specified and limited, the terms "connected", "disposed" and the like should be understood in a broad sense, for example, it can be fixedly connected, detachably connected, or integrated; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intervening elements.

[0026] Figure 1 Some preferred embodiments of the lithium-ion battery of the utility model are shown. The lithium-ion battery is a soft-pack lithium-ion battery and can be roughly in the shape of a rectangular parallelepiped, which can be used to power external devices. In some other embodiments, the lithium-ion battery may not be limited to a rectangular parallelepiped shape.

[0027] like Figure 1 and Figure 2 As shown, in some embodiments, the lithium-ion battery may include a negative electrode sheet 100, a negative electrode ear 200, a positive electrode sheet 300, and a positive electrode ear 400. The negative electrode sheet 100 and the positive electrode sheet 300 are stacked, and the two can be separated by a diaphragm, and the two can be wound together to form a rectangular coil. Of course, it can be understood that in some other embodiments, the coil can also be cylindrical. The coil has at least two layers of negative electrode layers from the inside to the outside, the negative electrode ear 200 is arranged on the negative electrode sheet 100, and the positive electrode ear 400 is arranged on the positive electrode ear 400. The negative electrode ear 200 and the positive electrode ear 400 can extend from one end of the coil for connection with an external device. In some embodiments, the negative electrode ear 200 can be located in the innermost negative electrode layer. Of course, in some other embodiments, the negative electrode ear 200 and the positive electrode ear 400 can also extend from both ends of the coil respectively.

[0028] In some embodiments, the negative electrode sheet 100 may include a substrate 10. The substrate 10 may be a longitudinal sheet, specifically, the substrate 10 may be a rectangular sheet. In some embodiments, the substrate 10 may be a copper foil. The length direction of the substrate 10 is the first direction, and the width direction of the substrate 10 is the second direction. The substrate 10 may include a first surface 10a and a second surface 10b, wherein the first surface 10a and the second surface 10b may be disposed opposite to each other, and the first surface 10a and the second surface 10b may be defined as the long side in the length direction and the short side in the width direction. In some embodiments, the first surface 10a may include a first edge 10c, a second edge 10d, a third edge 10e, and a fourth edge 10f. The first edge 10c and the second edge 10d may be located in the second direction and extend along the first direction. That is, in the width direction of the substrate 10. The third edge 10e and the fourth edge 10f may be located in the first direction and extend along the second direction, that is, the length of the length direction of the substrate 10 is less than the length of the first edge 10c or the second edge 10d. In some embodiments, a first preset area 11 is provided on the first surface 10a. The first preset area 11 may be provided close to the third edge 10e of the first surface 10a, and the negative electrode sheet 100 is wound around the third edge 10e during winding. The first preset area 11 may extend from the first edge 10c to the second edge 10d along the second direction. The first preset area 11 may be substantially rectangular.

[0029] In some embodiments, the lithium-ion battery further includes a first active layer 20. The first active layer 20 is disposed on the first surface 10a and the second surface 10b. The first active layer 20 can be formed by coating the first active material on the first surface 10a and the second surface 10b. In some embodiments, the first active material can be graphite, such as natural graphite or artificial graphite. In some other embodiments, the first active material is not limited to graphite, and can be soft carbon, graphene, silicon carbon, tin oxide, etc. The first surface 10a and the second surface 10b can be fully coated with the first active material to form the first active layer 20. In some other embodiments, the first active layer 20 can also be located in partial areas of the first surface 10a and the second surface 10b. In some embodiments, a second preset area 21 is left on the first active layer 20, and a set distance is left between the second preset area 21 and the first preset area 11 in the first direction. The negative electrode sheet 100 can be wound with a layer spacing greater than the set distance when winding, and a winding core having at least two layers of negative electrode layers from the inside to the outside is formed, and the second preset area 21 in the winding core can cover at least one side of the first preset area 11. In some other embodiments, the second preset area 21 is not limited to one, and it can be two or more, and the two or more second preset areas 21 can be arranged at equal intervals. The second preset area 21 can extend from the first edge 10c to the second edge 10d along the second direction. The second preset area 21 can be roughly rectangular.

[0030] In some embodiments, the negative electrode sheet 100 also includes a second active layer 30. The second active layer 30 may be located in the second preset area 21 on the first active layer 20, and it may be coated on the entire second preset area 21. The second active layer 30 may be formed by coating a second active material in the second preset area 21, and the fast charging capability of the second active layer 30 is greater than the fast charging capability of the first active layer 20. In some embodiments, the second active material may be lithium titanate or hard carbon. Specifically, the minimum distance between the second active layer 30 and the first preset area 11 may be configured to be greater than the spacing between two adjacent negative electrode layers, that is, the set distance between the first preset area 11 and the second preset area 21 may be configured to be greater than or equal to the minimum distance between the second active layer 30 and the first preset area 11, so that the second active layer 30 can cover at least one side of the first preset area 11 after the negative electrode sheet 100 is wound to form a core, thereby effectively improving the fast charging capability of the lithium-ion battery and avoiding lithium precipitation at the stamping site.

[0031] In some embodiments, the width of the second active layer 30 in the first direction is greater than the width of the first preset area 11, and the length of the second active layer 30 in the second direction is greater than or equal to the length of the first preset area 11. Specifically, the width of the second active layer 30 is at least 1 mm greater than the width of the first preset area 11, and the length of the portion of the edge of the second active layer 30 on both sides exceeding the edge of the first preset area is greater than 0.5 mm, that is, the edge of both sides can be set beyond the negative electrode ear 200, and the length of the second active layer 30 in the second direction is at least 0.5 mm greater than the first preset area, so as to ensure that after winding, the second active layer 30 can cover one side of the negative electrode ear 200. In some embodiments, the thickness of the second active layer can be 1 to 8 um.

[0032] In some embodiments, the negative electrode tab 200 may be a nickel electrode tab, which may be fixed to the first predetermined area 11 by welding, and may extend from the first edge 10 c.

[0033] It can be understood that the above embodiments only express the preferred implementation methods of the utility model, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the utility model. It should be pointed out that, for ordinary technicians in this field, without departing from the concept of the utility model, the above-mentioned technical features can be freely combined, and several deformations and improvements can be made, which all belong to the protection scope of the utility model. Therefore, all equivalent changes and modifications made to the scope of the claims of the utility model should belong to the scope covered by the claims of the utility model.

Claims

1. A negative electrode sheet (100), characterized in that: include: The substrate (10) is arranged in a longitudinal direction and comprises a first surface (10a) and a second surface (10b) arranged opposite to each other, wherein the first surface (10a) and / or the second surface (10b) is provided with a first preset area (11) for mounting a negative electrode tab (200); A first active layer (20) is arranged on the first surface (10a) and the second surface (10b); at least one second preset area (21) is left on the first active layer (20); a set distance is left between the second preset area (21) and the first preset area (11) in a first direction; the first direction is the length direction of the substrate (10); The second active layer (30) is disposed in the second preset area (21) and is configured to cover at least one side of the first preset area (11) after the negative electrode sheet (100) forms a winding core.

2. The negative electrode sheet (100) according to claim 1, characterized in that: The winding core has at least two negative electrode layers from the inside to the outside, and the minimum distance between the second active layer (30) and the first preset area (11) is configured to be greater than the distance between two adjacent negative electrode layers; The set distance is configured to be greater than or equal to a minimum distance between the second active layer (30) and the first preset area (11).

3. The negative electrode sheet (100) according to claim 1, characterized in that: The width of the second active layer (30) in the first direction is greater than the width of the first preset area (11), and after the winding core is formed, the edge of the second active layer (30) is arranged beyond the edge of the first preset area (11).

4. The negative electrode sheet (100) according to claim 3, characterized in that: The length of the portions of the edges on both sides of the second active layer (30) that extend beyond the edge of the first preset area (11) is greater than 0.5 mm.

5. The negative electrode sheet (100) according to claim 1, characterized in that: The thickness of the second active layer (30) is 1 to 8 um.

6. The negative electrode sheet (100) according to claim 1, characterized in that: The first surface (10a) and / or the second surface (10b) comprises a first edge and a second edge arranged along a second direction; the second direction is a width direction of the substrate (10); The first preset area (11) extends from the first edge to the second edge along a second direction; The second preset area (21) extends from the first edge to the second edge along a second direction.

7. The negative electrode sheet (100) according to claim 6, characterized in that: In the second direction, the length of the second active layer (30) is greater than or equal to the length of the first preset area (11).

8. The negative electrode sheet (100) according to claim 7, characterized in that: In the second direction, the length of the second active layer (30) is 0.5 mm greater than that of the first preset area (11).

9. A lithium ion battery, characterized in that: The invention comprises a negative electrode sheet (100), a positive electrode sheet (300), a positive electrode ear (400) and a negative electrode ear (200) as claimed in any one of claims 1 to 8, wherein the positive electrode ear (400) is arranged on the positive electrode sheet (300); the negative electrode ear (200) is arranged in a first preset area (11) of the negative electrode sheet (100); the positive electrode sheet (300) and the negative electrode sheet (100) are stacked and wound together to form a winding core, and the positive electrode ear (400) and the negative electrode ear (200) extend from one end of the winding core or respectively from both ends of the winding core.

10. The lithium ion battery according to claim 9, characterized in that: In the transverse direction of the winding core, the second active layer (30) on the negative electrode sheet (100) and the negative electrode tab (200) are arranged from inside to outside and cover at least one side of the negative electrode tab (200).

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