Battery cell structure, battery and power utilization device

Abstract

The utility model relates to a battery cell structure, a battery and an electric device. The battery cell structure comprises composite pole pieces and a diaphragm, the composite pole pieces and the diaphragm are arranged by adopting a winding structure, and the diaphragm is wound between two adjacent composite pole pieces; the composite pole piece comprises a positive electrode material layer, a composite foil layer and a negative electrode material layer which are sequentially stacked, and the width of the negative electrode material layer is larger than that of the positive electrode material layer. The utility model also provides a battery which comprises the battery cell structure disclosed by the utility model. The utility model also provides an electric device which comprises the battery disclosed by the utility model. According to the utility model, the problems that the alignment degree is poor and the quality and the consistency of the battery cell are influenced due to the adoption of a diaphragm-negative plate-diaphragm-positive plate winding structure in the traditional battery cell are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium batteries, and in particular to a battery core structure, a battery and an electrical device. Background Art

[0002] New energy vehicles are increasingly becoming the first choice of consumers due to their excellent environmental performance, low noise characteristics and high energy efficiency. Among these advantages, lithium-ion batteries undoubtedly play a vital role. As the main power source of new energy vehicles, it has been widely used and deeply studied.

[0003] The internal structure of the battery cell, as the "heart" of the lithium-ion battery, has a decisive influence on the overall performance of the battery. Traditional battery cell designs often adopt a winding structure of diaphragm-negative electrode sheet-diaphragm-positive electrode sheet, and are formed through a precise winding process. However, in this process, the precise alignment between the layers is crucial to ensure the quality and performance consistency of the battery, because it is directly related to the safety and stability of the battery. Alignment, a seemingly minor technical detail, actually contains huge challenges. Because even a slight deviation may lead to unstable battery performance and even cause safety hazards.

[0004] For example, a wound cell, preparation process and lithium-ion battery disclosed in CN110380136A include a positive electrode sheet, a negative electrode sheet and a separator, wherein the positive electrode sheet and the negative electrode sheet are arranged in a winding structure, the separator is wound between the positive electrode sheet and the negative electrode sheet, and the negative electrode sheet is wound outside the positive electrode sheet. Each circle of negative electrode sheet and / or positive electrode sheet is provided with a tape that can be dissolved in the electrolyte at the bending position and on the side facing the center of the wound cell, and the tape is located between the corresponding negative electrode sheet and the separator or the corresponding positive electrode sheet and the separator. Although the tape dissolves in the electrolyte after the wound cell is placed in the electrolyte, so that a gap is formed between the negative electrode sheet and / or the positive electrode sheet and the corresponding separator, reducing the internal stress of the negative electrode sheet and the positive electrode sheet at the corner, the alignment problem between the layers is not solved. Therefore, how to effectively improve the alignment between the layers inside the cell has become a key point that needs to be broken through in the current development of new energy battery technology. Utility Model Content

[0005] In view of this, the purpose of the utility model is to provide a battery cell structure, a battery and an electrical device to solve the problem that the winding structure of the traditional battery cell using a diaphragm-negative electrode sheet-diaphragm-positive electrode sheet has poor alignment, which affects the quality and consistency of the battery cell.

[0006] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0007] A battery cell structure, comprising a composite pole piece and a diaphragm, wherein the composite pole piece and the diaphragm are arranged in a winding structure, and the diaphragm is wound between two adjacent composite pole pieces;

[0008] The composite electrode sheet comprises a positive electrode material layer, a composite foil material layer and a negative electrode material layer which are stacked in sequence, and the width of the negative electrode material layer is greater than the width of the positive electrode material layer.

[0009] According to the above technical means, a battery cell is made by directly using a composite electrode sheet having a positive electrode material layer, a composite foil layer and a negative electrode material layer and winding with a separator. Since the positive electrode material layer and the negative electrode material layer on the composite electrode sheet are completely aligned when preparing the composite electrode sheet, there is no need to perform alignment settings during winding, thereby effectively ensuring the alignment of the battery cell winding structure and improving the quality and consistency of the battery cell; at the same time, setting the width of the negative electrode material layer to be greater than the width of the positive electrode material layer effectively avoids the problem of positive electrode lithium plating, further improving the quality of the battery cell and the electrochemical performance of the battery cell. This solves the problem that the winding structure of the traditional battery cell using a separator-negative electrode sheet-separator-positive electrode sheet has poor alignment, affecting the quality and consistency of the battery cell.

[0010] Preferably, the composite foil layer comprises a positive electrode current collector, an insulating layer and a negative electrode current collector which are stacked in sequence, the positive electrode material layer is arranged on the surface of the positive electrode current collector, and the negative electrode material layer is arranged on the surface of the negative electrode current collector.

[0011] Preferably, the surfaces of the positive electrode current collector and the negative electrode current collector have empty foil areas.

[0012] By arranging an empty foil area on the surface of the positive electrode collector and the negative electrode collector, the arrangement of the electrode tabs is effectively facilitated.

[0013] Preferably, the empty foil region of the positive electrode current collector and the empty foil region of the negative electrode current collector are staggered.

[0014] By arranging the empty foil area of ​​the positive electrode collector and the empty foil area of ​​the negative electrode collector in a staggered arrangement, the arrangement and assembly of the electrode tabs are facilitated.

[0015] Preferably, the positive electrode material layer is not provided on the outer surface of the composite electrode sheet located at the outermost circle of the wound battery cell.

[0016] Since there is only a separator on the outermost layer of the wound battery cell, it is assumed that no positive electrode material layer is provided on the outer surface of the outermost circle of the composite electrode, thereby ensuring that all positive electrode material layers have corresponding negative electrode material layers to avoid the risk of lithium plating.

[0017] The separator is located on the surface of the negative electrode material layer, and is wound along the inner side of the negative electrode material layer.

[0018] Preferably, the winding starting end of the diaphragm exceeds the winding starting end of the composite pole piece.

[0019] By setting the winding starting end of the diaphragm beyond the winding starting end of the composite electrode sheet, the positive electrode material layer and the negative electrode material layer in the composite electrode sheet are effectively isolated, and the sealing, stability, performance and safety of the battery cell are guaranteed.

[0020] Preferably, the winding termination end of the diaphragm exceeds the winding termination end of the composite pole piece.

[0021] By setting the winding end of the diaphragm beyond the winding end of the composite electrode, the positive electrode material layer and the negative electrode material layer in the composite electrode are effectively isolated, and the sealing, stability, performance and safety of the battery cell are guaranteed.

[0022] Preferably, the positive electrode current collector is aluminum foil.

[0023] Preferably, the negative electrode current collector is copper foil.

[0024] Preferably, the insulating layer is an insulating polymer layer.

[0025] The utility model also provides a battery, comprising the battery core structure as described in the utility model.

[0026] The utility model also provides an electric device, comprising the battery as described in the utility model.

[0027] Beneficial effects of the utility model:

[0028] The battery cell structure of the utility model is made into a battery cell by directly using a composite electrode sheet having a positive electrode material layer, a composite foil material layer and a negative electrode material layer and winding with a diaphragm. Since the positive electrode material layer and the negative electrode material layer on the composite electrode sheet are completely aligned when preparing the composite electrode sheet, there is no need to align them during winding, thereby effectively ensuring the alignment of the battery cell winding structure and improving the quality and consistency of the battery cell. At the same time, the width of the negative electrode material layer is set to be greater than the width of the positive electrode material layer, which effectively avoids the problem of positive electrode lithium plating and further improves the quality of the battery cell and the electrochemical performance of the battery cell. It solves the problem that the traditional battery cell adopts a winding structure of a diaphragm-negative electrode sheet-diaphragm-positive electrode sheet, which has poor alignment and affects the quality and consistency of the battery cell. It has the advantages of simple structure and low cost, and has promotion and application value in the field of lithium battery technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the battery core structure of the utility model;

[0030] Figure 2 It is a partial schematic diagram of the composite electrode at the end of the wound battery cell along the length direction;

[0031] Figure 3 is a cross-sectional view of the composite pole piece along the width direction;

[0032] Figure 4 is a cross-sectional view of the composite foil layer along the width direction;

[0033] Among them, 1-composite electrode sheet, 11-positive electrode material layer, 12-composite foil material layer, 121-positive electrode current collector, 122-insulating layer, 123-negative electrode current collector, 124-empty foil area, 13-negative electrode material layer; 2-diaphragm. DETAILED DESCRIPTION

[0034] The following will describe the implementation of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, not for limiting the scope of protection of the present invention.

[0035] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.

[0036] In the following description, numerous details are discussed to provide a more thorough explanation of the embodiments of the present application. However, it is obvious to those skilled in the art that the embodiments of the present application can be implemented without these specific details. Example

[0037] like Figures 1 to 4 As shown, a battery cell structure includes a composite pole piece 1 and a diaphragm 2, the composite pole piece 1 and the diaphragm 2 are arranged in a winding structure, and the diaphragm 2 is wound between two adjacent composite pole pieces 1;

[0038] The composite electrode sheet 1 comprises a positive electrode material layer 11 , a composite foil layer 12 and a negative electrode material layer 13 which are stacked in sequence. The width of the negative electrode material layer 13 is greater than that of the positive electrode material layer 11 .

[0039] By directly using a composite electrode sheet with a positive electrode material layer, a composite foil layer and a negative electrode material layer and winding it with a separator to form a battery cell, since the positive electrode material layer and the negative electrode material layer on the composite electrode sheet are completely aligned when preparing the composite electrode sheet, there is no need to perform alignment settings during winding, thereby effectively ensuring the alignment of the battery cell winding structure and improving the quality and consistency of the battery cell; at the same time, setting the width of the negative electrode material layer to be greater than the width of the positive electrode material layer effectively avoids the problem of positive electrode lithium plating, further improving the quality of the battery cell and the electrochemical performance of the battery cell. This solves the problem that the traditional battery cell uses a separator-negative electrode sheet-diaphragm-positive electrode sheet winding structure with poor alignment, which affects the quality and consistency of the battery cell.

[0040] In some embodiments, the composite foil layer 12 includes a positive electrode current collector 121 , an insulating layer 122 and a negative electrode current collector 123 stacked in sequence, the positive electrode material layer 11 is disposed on the surface of the positive electrode current collector 121 , and the negative electrode material layer 13 is disposed on the surface of the negative electrode current collector 123 .

[0041] Exemplarily, in order to improve the alignment and overall consistency of the composite electrode sheet, the positive electrode material layer 11 on the surface of the positive electrode current collector 121 is set as a positive electrode material coating layer.

[0042] Exemplarily, in order to improve the alignment and overall consistency of the composite electrode sheet, the negative electrode material layer 13 on the surface of the negative electrode current collector 123 is set as a negative electrode material coating layer.

[0043] In some embodiments, in order to facilitate the arrangement of the tabs, a hollow foil area 124 is arranged on the surface of both the positive electrode collector 121 and the negative electrode collector 123 .

[0044] In some embodiments, in order to facilitate the arrangement and assembly of the tabs, the empty foil region 124 of the positive electrode current collector 121 and the empty foil region 124 of the negative electrode current collector 123 are staggered. It can be understood that the empty foil region 124 of the positive electrode current collector 121 is close to one end along the width direction of the composite foil 12, and the empty foil region 124 of the negative electrode current collector 123 is close to the other end along the width direction of the composite foil 12.

[0045] In some embodiments, since there is only a separator in the outermost layer of the wound battery cell, in order to avoid the risk of lithium plating and improve the safety performance of the battery cell, no positive electrode material layer 11 or negative electrode material layer 13 is provided on the outer surface of the composite electrode 1 located at the outermost circle of the wound battery cell.

[0046] For example, when the separator 2 located at the innermost layer of the wound cell contacts the negative electrode material layer 13 of the composite electrode sheet 1, the outer surface of the composite electrode sheet 1 located at the outermost circle of the wound cell is not provided with the positive electrode material layer 11, that is, Figure 1 and Figure 2In the figure, S indicates that the outer surface of the composite foil 12 of this section of the composite electrode sheet 1 is not provided with the positive electrode material layer 11.

[0047] In some embodiments, in order to ensure effective isolation of the positive electrode material layer and the negative electrode material layer in the composite electrode sheet, and to ensure the sealing, stability, battery performance and safety of the battery cell, the winding starting end of the diaphragm 2 is set to exceed the winding starting end of the composite electrode sheet 1.

[0048] In some embodiments, in order to ensure effective isolation of the positive electrode material layer and the negative electrode material layer in the composite electrode sheet, and to ensure the sealing, stability, battery performance and safety of the battery cell, the winding end of the diaphragm 2 is set to extend beyond the winding end of the composite electrode sheet 1.

[0049] Illustratively, the positive electrode current collector 121 is aluminum foil.

[0050] Illustratively, the negative electrode current collector 123 is copper foil.

[0051] In some embodiments, insulating layer 122 is an insulating polymer layer.

[0052] Exemplarily, the insulating polymer is selected from at least one of polyethylene, polyvinyl chloride, polystyrene and polytetrafluoroethylene.

[0053] In some embodiments, a battery comprising the battery cell structure in any of the above embodiments is also provided.

[0054] In some embodiments, an electrical device including the battery in the above embodiments is also provided.

[0055] In summary, the battery cell structure of the utility model is made into a battery cell by directly using a composite electrode sheet having a positive electrode material layer, a composite foil material layer and a negative electrode material layer and winding with a diaphragm. Since the positive electrode material layer and the negative electrode material layer on the composite electrode sheet are completely aligned when preparing the composite electrode sheet, there is no need to perform alignment settings during winding, thereby effectively ensuring the alignment of the battery cell winding structure and improving the quality and consistency of the battery cell; at the same time, setting the width of the negative electrode material layer to be greater than the width of the positive electrode material layer effectively avoids the problem of positive electrode lithium plating, further improving the quality of the battery cell and the electrochemical performance of the battery cell. It solves the problem that the traditional battery cell adopts a winding structure of a diaphragm-negative electrode sheet-diaphragm-positive electrode sheet, which has poor alignment and affects the quality and consistency of the battery cell, and has the advantages of simple structure and low cost. It has promotion and application value in the field of lithium battery technology.

[0056] The above embodiments are merely illustrative of the principles and effects of the present utility model, and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. A battery cell structure, characterized in that: It comprises a composite pole piece (1) and a diaphragm (2), wherein the composite pole piece (1) and the diaphragm (2) are arranged in a winding structure, and the diaphragm (2) is wound between two adjacent composite pole pieces (1); The composite electrode sheet (1) comprises a positive electrode material layer (11), a composite foil layer (12) and a negative electrode material layer (13) which are stacked in sequence, and the width of the negative electrode material layer (13) is greater than the width of the positive electrode material layer (11).

2. The battery cell structure according to claim 1, characterized in that: The composite foil layer (12) comprises a positive electrode current collector (121), an insulating layer (122) and a negative electrode current collector (123) which are stacked in sequence, the positive electrode material layer (11) being arranged on the surface of the positive electrode current collector (121), and the negative electrode material layer (13) being arranged on the surface of the negative electrode current collector (123); The surfaces of the positive electrode current collector (121) and the negative electrode current collector (123) have empty foil areas (124).

3. The battery cell structure according to claim 2, characterized in that: The empty foil region (124) of the positive electrode current collector (121) and the empty foil region (124) of the negative electrode current collector (123) are arranged in a staggered manner.

4. The battery cell structure according to claim 1, characterized in that: The positive electrode material layer (11) is not provided on the outer surface of the composite electrode (1) located at the outermost circle of the wound battery core.

5. The battery cell structure according to claim 1, characterized in that: The winding start end of the diaphragm (2) exceeds the winding start end of the composite pole piece (1).

6. The battery cell structure according to claim 1, characterized in that: The winding end of the diaphragm (2) exceeds the winding end of the composite pole piece (1).

7. The battery cell structure according to claim 2, characterized in that: The positive electrode current collector (121) is aluminum foil; And / or, the negative electrode current collector (123) is copper foil.

8. The battery cell structure according to claim 2, characterized in that: The insulating layer (122) is an insulating polymer layer.

9. A battery, characterized in that: Comprising the battery core structure according to any one of claims 1 to 8.

10. An electrical device, characterized in that: Comprising the battery as claimed in claim 9.

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