Core stacking structure and battery comprising same

Abstract

The utility model relates to a laminated core structure which comprises at least two negative pole pieces, at least one positive pole piece and at least one composite pole piece, the at least two negative pole pieces are sequentially arranged along the first direction; one positive pole piece is arranged between every two adjacent negative pole pieces, or one composite pole piece is arranged between every two adjacent negative pole pieces; the composite pole piece comprises a lithium piece and a polymer, and the high polymer coats the lithium sheet. In the laminated core structure, the lithium sheets can supplement lithium ions consumed by forming a solid electrolyte interface (SEI) film in the formation stage of the battery, so that the loss of active lithium is reduced, the initial coulombic efficiency of the battery is further improved, and the overall performance of the battery is enhanced; meanwhile, the polymer sheet also has a good elastic characteristic and can adapt to volume change caused by lithium ion intercalation and deintercalation in the charging and discharging process of the battery, so that the pressure on the shell is reduced, the deformation of the shell is effectively prevented, and the safety of the battery is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium batteries, and particularly relates to a stacked core structure and a battery including the same. Background Art

[0002] A stacked battery is a square hard-shell battery manufactured based on a high-speed stacking process. This process simplifies the production process and improves the safety performance, energy density, and cycle life of the battery. Due to its excellent performance, the stacked battery shows broad application prospects.

[0003] In order to pursue higher energy density, the stacked batteries in the prior art usually adopt electrode sheets with high tap density and perform cold pressing or hot pressing after stacking to form a stacked core structure in which the positive electrode sheet, the negative electrode sheet, and the separator are closely attached. This closely attached stacked core structure has poor absorption rate of the electrolyte, resulting in a longer time required for sufficient infiltration during the liquid injection stage, which will affect the production efficiency of the battery.

[0004] In addition, during the charge and discharge process of the battery, the insertion and extraction reactions of lithium ions will cause changes in the volume of the electrode sheet. Due to the relatively tight stacked core structure, these volume changes can only be released to the outside, easily causing deformation of the aluminum shell, and further triggering a series of safety risks.

[0005] In view of this, there is an urgent need for a stacked core structure and a battery including the same. Summary of the Utility Model

[0006] The purpose of the utility model is to provide a stacked core structure and a battery including the same for the deficiencies in the prior art.

[0007] To achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0008] The first aspect of the utility model is to provide a stacked core structure, including: at least two negative electrode sheets, at least one positive electrode sheet, and at least one composite electrode sheet; wherein,

[0009] At least two of the negative electrode sheets are arranged in sequence along a first direction;

[0010] One of the positive electrode sheets is arranged between two adjacent negative electrode sheets, or one of the composite electrode sheets is arranged between two adjacent negative electrode sheets;

[0011] Wherein, the composite electrode sheet includes: a lithium sheet and a polymer body;

[0012] Wherein, the polymer body is arranged to coat the lithium sheet.

[0013] Preferably, 20 - 30 of the positive electrode sheets are arranged between two adjacent composite electrode sheets.

[0014] Preferably, the polymer body includes: two polymer sheets and a binder; wherein,

[0015] The lithium sheet and the binder are disposed between the two polymer sheets;

[0016] The binder is disposed around the periphery of the lithium sheet, and the two polymer sheets are connected by the binder.

[0017] Preferably, the length of the composite electrode sheet is the same as the length of the positive electrode sheet.

[0018] Preferably, the width of the composite electrode sheet is the same as the width of the positive electrode sheet.

[0019] Preferably, the length of the lithium sheet is 10 mm - 20 mm shorter than the length of the polymer sheet.

[0020] Preferably, the width of the lithium sheet is 10 mm - 20 mm shorter than the width of the polymer sheet.

[0021] Preferably, the thickness of the lithium sheet is 0.05 mm - 0.1 mm.

[0022] Preferably, the thickness of the polymer sheet is 0.1 mm - 0.2 mm.

[0023] Preferably, the polymer sheet is made of PVA sponge material or EVA sponge material.

[0024] Preferably, the binder is made of PVDF material, SBR material, or PAA material.

[0025] Preferably, it further includes: at least two separator membranes; wherein,

[0026] One separator membrane is disposed between adjacent negative electrode sheets and positive electrode sheets, or between adjacent negative electrode sheets and composite electrode sheets.

[0027] Preferably, it further includes: at least one connecting separator membrane; wherein,

[0028] Adjacent separator membranes are connected by one connecting separator membrane;

[0029] The connecting separator membrane is disposed on one side of the negative electrode sheet, or on one side of the positive electrode sheet, or on one side of the composite electrode sheet.

[0030] Preferably, it further includes: at least two negative electrode tabs and at least one positive electrode tab; wherein,

[0031] The first side of the negative electrode sheet is connected with the negative electrode tab;

[0032] The second side of the positive electrode tab is connected to the positive electrode ear;

[0033] The connecting separator is disposed on the second side of the negative electrode tab, or the first side of the positive electrode tab, or the first side of the composite electrode tab.

[0034] The second aspect of the present invention is to provide a battery, comprising: the stacked core structure as described above.

[0035] The present invention adopts the above technical solutions, and compared with the prior art, has the following technical effects:

[0036] In the stacked core structure of the present invention, the polymer sheet has good electrolyte absorption capacity. When it is distributed in the stacked core structure, it can effectively promote the diffusion of the electrolyte into the interior of the stacked core structure, significantly improve the infiltration rate of the electrolyte, shorten the time required for the liquid injection stage, thereby improving the overall production efficiency of the battery; the lithium sheet can supplement the lithium ions consumed due to the formation of the solid electrolyte interface (SEI) film during the formation stage of the battery, which helps to reduce the loss of active lithium, and further improve the first Coulomb efficiency of the battery and enhance the overall performance of the battery; at the same time, the polymer sheet also has good elastic characteristics and can adapt to the volume change caused by the insertion and extraction of lithium ions during the charge and discharge process of the battery. This elasticity allows the volume change to be buffered inside the stacked core structure, reducing the pressure on the outer shell, effectively preventing the outer shell from deforming, and improving the safety of the battery. Description of the Drawings

[0037] Figure 1 is a schematic structural view of the composite electrode tab in the present invention;

[0038] Figure 2 is a schematic structural view of the stacked core structure in the present invention;

[0039] Among them, the reference numerals include:

[0040] Negative electrode tab 1; negative electrode ear 11; positive electrode tab 2; positive electrode ear 21; composite electrode tab 3; lithium sheet 31; polymer sheet 32; separator 4. Detailed Description of the Invention

[0041] The following will describe the specific embodiments of the present invention in detail.

[0042] Unless otherwise defined, the technical terms or scientific terms used in the claims and the specification should have the ordinary meaning understood by those of ordinary skill in the technical field to which the present invention belongs.

[0043] As used in the description and claims of this utility model patent application, the term "comprising" or similar words are intended to mean that the items appearing before "comprising" cover the items listed after "comprising" or their equivalents, without excluding other items.

[0044] The numerical values mentioned in this utility model include all numerical values that increase one unit at a time from low to high, assuming that there is an interval of at least two units between any lower value and higher value. For example, if it is said that a component amount or a physical quantity ranges from 1 to 100, more preferably from 10 to 90, and most preferably from 20 to 80, it is intended to express that numerical values such as 5 to 95, 14 to 76, 23 to 67, 32 to 58, 41 to 49, etc. are clearly listed in this specification; for numerical values less than 1, 0.0001, 0.001, 0.01 or 0.1 is considered a more appropriate unit. The foregoing examples are for illustrative purposes only. In fact, all numerical combinations between the lowest value and the highest value listed are considered to be clearly listed in this specification in a similar manner.

[0045] Example 1

[0046] As Figure 1 shown, this embodiment first provides a composite electrode sheet 3, comprising: a lithium sheet 31 and a polymer body; wherein,

[0047] The polymer body is disposed to cover the lithium sheet 31, and the polymer body includes: two polymer sheets 32 and a binder;

[0048] Wherein, the lithium sheet 31 and the binder are disposed between the two polymer sheets 32;

[0049] The binder is disposed around the periphery of the lithium sheet 31, and the two polymer sheets 32 are connected by the binder.

[0050] In a preferred embodiment, the polymer sheet 32 is made of PVA sponge material, EVA sponge material, or other polymer materials having similar properties such as being able to improve the infiltration rate of the electrolyte, having a certain softness, a certain elasticity, or / and not hindering the lithium sheet 31 from replenishing lithium ions; the binder is made of PVDF material, SBR material, PAA material, or other similar binder materials that can be used to connect the two polymer sheets 32.

[0051] In a preferred embodiment, the length of the lithium sheet 31 is 10 mm - 20 mm shorter than the length of the polymer sheet 32, and the width of the lithium sheet 31 is 10 mm - 20 mm shorter than the width of the polymer sheet 32, so that the lithium sheet 31 can be completely covered by the polymer body composed of the polymer sheet 32 and the binder, avoiding the lithium sheet 31 from being worn or / and contaminated.

[0052] In a preferred embodiment, the thickness of the lithium sheet 31 is 0.05 mm - 0.1 mm, and the thickness of the polymer sheet 32 is 0.1 mm - 0.2 mm. This thickness will neither increase the difficulty of the lamination process nor increase the material cost.

[0053] As Figure 2 shown, this embodiment further provides a laminated core structure, including: at least two negative electrode sheets 1, at least one positive electrode sheet 2, at least one composite electrode sheet 3 as described above, and at least two separator sheets 4; wherein,

[0054] At least two of the negative electrode sheets 1 are arranged in sequence along the first direction;

[0055] One positive electrode sheet 2 is arranged between two adjacent negative electrode sheets 1, or one composite electrode sheet 3 is arranged between two adjacent negative electrode sheets 1;

[0056] One separator sheet 4 is arranged between the adjacent negative electrode sheet 1 and the positive electrode sheet 2, or between the adjacent negative electrode sheet 1 and the composite electrode sheet 3;

[0057] Wherein, a negative electrode tab 11 is connected to the first side of the negative electrode sheet 1;

[0058] Wherein, a positive electrode tab 21 is connected to the second side of the positive electrode sheet 2.

[0059] Obviously, those skilled in the art can understand that in any laminated core or laminated core structure, as long as it includes: a negative electrode sheet 1, a composite electrode sheet 3, and a negative electrode sheet 1 stacked in sequence, it falls within the protection scope of the aforementioned laminated core structure.

[0060] On this basis, those skilled in the art can easily give multiple examples of the laminated core structure. For example: a negative electrode sheet 1, a positive electrode sheet 2, a negative electrode sheet 1, a composite electrode sheet 3, a negative electrode sheet 1, a positive electrode sheet 2, and a negative electrode sheet 1 stacked in sequence; or for example: a negative electrode sheet 1, a positive electrode sheet 2, a negative electrode sheet 1, a composite electrode sheet 3, a negative electrode sheet 1, a positive electrode sheet 2,... (several negative electrode sheets 1 and positive electrode sheets 2 stacked in sequence, for example: 19 groups of negative electrode sheets 1 and positive electrode sheets 2 stacked in sequence), a negative electrode sheet 1, a composite electrode sheet 3, a negative electrode sheet 1, a positive electrode sheet 2,... (several negative electrode sheets 1 and positive electrode sheets 2 stacked in sequence, for example: 24 groups of negative electrode sheets 1 and positive electrode sheets 2 stacked in sequence), a negative electrode sheet 1, a composite electrode sheet 3, a negative electrode sheet 1, a positive electrode sheet 2,... (several negative electrode sheets 1 and positive electrode sheets 2 stacked in sequence, for example: 29 groups of negative electrode sheets 1 and positive electrode sheets 2 stacked in sequence), a negative electrode sheet 1.

[0061] In a preferred embodiment, 20 - 30 positive electrode plates 2 are arranged between two adjacent composite electrode plates 3. Such an arrangement can enable the lithium sheet to better supplement lithium ions during the formation stage of the battery.

[0062] In a preferred embodiment, the length of the composite electrode plate 3 is the same as that of the positive electrode plate 2, and the width of the composite electrode plate 3 is the same as that of the positive electrode plate 2. In this way, the composite electrode plate 3 can directly match the clamping mechanism of the positive electrode plate 2 without increasing the complexity of the stacking process or / and the stacking equipment.

[0063] In a preferred embodiment, one connecting separator is provided between two adjacent separators 5; thus, the connecting separator is arranged on the second side of the negative electrode plate 1, or the first side of the positive electrode plate 2, or the first side of the composite electrode plate 3.

[0064] Finally, this embodiment provides a battery, including: the stacked core structure as described above.

[0065] In a preferred embodiment, the battery is a secondary battery.

[0066] In a more preferred embodiment, the battery is a lithium-ion aluminum shell secondary battery.

[0067] Embodiment 2

[0068] This embodiment provides a preparation method for the stacked core structure as described in Embodiment 1. The steps include:

[0069] S1. Provide a lithium sheet 31, two polymer sheets 32, and a binder;

[0070] Arrange the lithium sheet 31 at the central position on the first polymer sheet 32;

[0071] Coat the binder around the lithium sheet 31 on the first polymer sheet 32;

[0072] Cover the second polymer sheet 32 onto the lithium sheet 31 and the binder;

[0073] Connect the two polymer sheets 32 through the binder by means of a hot pressing process to obtain the composite electrode plate 3;

[0074] S2. Repeat step S1 to obtain a number of composite electrode plates 3;

[0075] S3. In the feeding mechanism of the positive electrode plate 2 of the stacking equipment, replace the positive electrode plate 2 at this position with one composite electrode plate 3 every 20 - 30 positive electrode plates 2;

[0076] S4. Through the lamination process, the laminated core structure as described in Embodiment 1 is obtained.

[0077] In summary, in the laminated core structure of the present utility model, the polymer sheet has good electrolyte absorption capacity. When it is distributed in the laminated core structure, it can effectively promote the diffusion of the electrolyte into the interior of the laminated core structure, significantly improve the infiltration rate of the electrolyte, shorten the time required for the liquid injection stage, and thus improve the overall production efficiency of the battery; the lithium sheet can supplement the lithium ions consumed due to the formation of the solid electrolyte interface (SEI) film during the formation stage of the battery, which helps to reduce the loss of active lithium, and further improve the first Coulomb efficiency of the battery and enhance the overall performance of the battery; at the same time, the polymer sheet also has good elastic characteristics and can adapt to the volume changes caused by the insertion and extraction of lithium ions during the charge and discharge process of the battery. This elasticity allows the volume changes to be buffered inside the laminated core structure, reduces the pressure on the outer shell, effectively prevents the outer shell from deforming, and improves the safety of the battery.

[0078] The above are only the preferred embodiments of the present utility model, and do not limit the implementation manners and protection scope of the present utility model. For those skilled in the art, it should be realized that all the equivalent replacements and obvious changes made by using the description and illustrations of the present utility model should be included in the protection scope of the present utility model.

Claims

1. A stacked core structure, characterized in that, Comprising: At least two negative electrode plates (1), at least one positive electrode plate (2), and at least one composite electrode plate (3); wherein, At least two of the negative electrode plates (1) are arranged in sequence along a first direction; One of the positive electrode plates (2) is arranged between two adjacent negative electrode plates (1), or one of the composite electrode plates (3) is arranged between two adjacent negative electrode plates (1); Wherein, the composite electrode plate (3) comprises: a lithium sheet (31) and a polymer body; Wherein, the polymer body is arranged to coat the lithium sheet (31).

2. The stacked core structure according to claim 1, wherein, 20 - 30 of the positive electrode plates (2) are arranged between two adjacent composite electrode plates (3).

3. The stacked core structure according to claim 1, wherein The polymer body comprises: two polymer sheets (32) and a binder; wherein, The lithium sheet (31) and the binder are arranged between the two polymer sheets (32); The binder is arranged around the periphery of the lithium sheet (31), and the two polymer sheets (32) are connected by the binder.

4. The stacked core structure according to claim 1 or 3, characterized in that, The length of the composite electrode plate (3) is the same as the length of the positive electrode plate (2), and the width of the composite electrode plate (3) is the same as the width of the positive electrode plate (2).

5. The stacked core structure according to claim 3, characterized in that, The length of the lithium sheet (31) is 10 mm - 20 mm shorter than the length of the polymer sheet (32), the width of the lithium sheet (31) is 10 mm - 20 mm shorter than the width of the polymer sheet (32), the thickness of the lithium sheet (31) is 0.05 mm - 0.1 mm, and the thickness of the polymer sheet (32) is 0.1 mm - 0.2 mm.

6. The stacked core structure according to claim 3, characterized in that, The polymer sheet (32) is made of PVA sponge material or EVA sponge material; the binder is made of PVDF material, SBR material, or PAA material.

7. The stacked core structure according to claim 1, wherein Further comprising: At least two separator membranes (4); wherein, One of the separator membranes (4) is arranged between two adjacent negative electrode plates (1) and positive electrode plates (2), or between two adjacent negative electrode plates (1) and composite electrode plates (3).

8. The stacked core structure according to claim 7, wherein, Further comprising: At least one connecting separator membrane; wherein, two adjacent separator membranes (4) are connected by one of the connecting separator membranes; The connecting separator membrane is arranged on one side of the negative electrode plate (1), or on one side of the positive electrode plate (2), or on one side of the composite electrode plate (3).

9. The stacked core structure according to claim 8, characterized in that, Further comprising: At least two negative electrode tabs (11) and at least one positive electrode tab (21); wherein, The negative electrode tab (11) is connected to the first side of the negative electrode plate (1); The positive electrode tab (21) is connected to the second side of the positive electrode plate (2); The connecting separator membrane is arranged on the second side of the negative electrode plate (1), or on the first side of the positive electrode plate (2), or on the first side of the composite electrode plate (3).

10. A battery, characterized in that, Comprising: The stacked core structure according to any one of claims 1 - 9.

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