Electrode assembly and battery

Abstract

The utility model provides an electrode assembly and a battery, the electrode assembly comprises a positive plate, a diaphragm and a negative plate which are sequentially stacked, when the positive plate partially punctures the diaphragm, an insulating layer is arranged between the part, punctured by the diaphragm, of the positive plate and the negative plate to form insulating protection between the positive plate and the negative plate. According to the electrode assembly disclosed by the utility model, the insulating layer is arranged between the positive plate and the negative plate when the positive plate pierces the diaphragm, so that the positive plate and the negative plate are not in direct contact, the short circuit condition is not easy to generate, and the electrode assembly has higher safety performance.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to an electrode assembly. The utility model also relates to a battery equipped with the above electrode assembly. Background Art

[0002] A lithium battery mainly consists of a positive electrode, a negative electrode, a separator, an electrolyte, a structural member, etc. Among them, the material area on the main body of the negative electrode sheet is larger than that on the main body of the positive electrode sheet, so as to receive the lithium ions released by the positive electrode during charging. The electrolyte is responsible for serving as a medium for lithium ion transfer, the separator plays a role in separating the positive and negative electrodes to avoid short circuit, and the structural members such as the housing mainly play a role in protecting the internal positive and negative electrodes, etc. and providing a sealed environment.

[0003] The electrode assembly is a general term for the combination of the positive electrode, the negative electrode and the separator, and is the core component in a lithium battery. The working principle of a lithium battery is based on the intercalation and deintercalation of lithium ions through the separator between the positive and negative electrodes. During charging, lithium ions are deintercalated from the positive electrode material, migrate through the electrolyte to the negative electrode and are intercalated into its structure; during discharging, this process proceeds in the reverse direction, and lithium ions return from the negative electrode to the positive electrode and release electrical energy.

[0004] The biggest problem plaguing lithium ion batteries is safety, and among them, the short circuit between the positive and negative electrodes is one of the most serious failure causes in the battery failure mode. In the traditional battery electrode sheet design, the positive electrode sheet is very easy to be pulled and puncture the separator during the assembly process, and then contact the negative electrode sheet to cause a short circuit, with poor safety performance. Summary of the Utility Model

[0005] In view of this, the utility model aims to propose an electrode assembly to improve the safety performance of the electrode assembly.

[0006] To achieve the above object, the technical solution of the utility model is realized as follows:

[0007] An electrode assembly includes:

[0008] A positive electrode sheet, a separator and a negative electrode sheet stacked in sequence;

[0009] When a part of the positive electrode sheet pierces the separator, an insulating layer is provided between the pierced part of the positive electrode sheet and the negative electrode sheet to form insulation protection between the positive electrode sheet and the negative electrode sheet.

[0010] Further, the positive electrode sheet includes a positive electrode main body and a positive electrode tab connected to the top end of the positive electrode sheet, and the insulating layer is coated on the corner of the positive electrode main body.

[0011] Further, the insulating layer is coated on both the top edge and the bottom edge of the positive electrode main body.

[0012] Further, the root of the positive electrode tab is coated with the insulating layer.

[0013] Further, the tabs of the positive electrode plate and the tabs of the negative electrode plate face in opposite directions. The negative electrode plate includes a negative electrode main body and a negative electrode tab connected to the top end of the negative electrode plate. The insulating layer is coated on the edge of the end of the negative electrode main body connected to the negative electrode tab. The projection of the other end edge of the positive electrode plate opposite to its tab on the negative electrode plate is located within the insulating layer area on the negative electrode main body.

[0014] Further, the root of the negative electrode tab is coated with the insulating layer. When the negative electrode tab is bent and abuts against the positive electrode plate, the abutting position is within the insulating layer area on the negative electrode tab.

[0015] Further, in the connection direction of the negative electrode tab and the negative electrode main body, both ends of the separator respectively extend beyond both ends of the negative electrode main body by 2 mm to 3.4 mm.

[0016] Further, in the direction perpendicular to the orientation of the negative electrode tab, both ends of the separator respectively extend beyond both ends of the negative electrode main body by 1 mm to 2 mm.

[0017] Further, the insulating layer is made of a ceramic material.

[0018] Compared with the prior art, the present utility model has the following advantages:

[0019] In the electrode assembly of the present utility model, by providing the insulating layer, when the positive electrode plate pierces the separator, an insulating layer is provided between the positive electrode plate and the negative electrode plate, and the positive electrode plate and the negative electrode plate will not be in direct contact, so it is not easy to generate a short circuit, making the electrode assembly have higher safety performance.

[0020] The situation where the positive electrode plate pierces the separator basically occurs at the corners. By coating the insulating layer at the corners of the positive electrode main body, effective insulation can be achieved when the corners of the positive electrode main body pierce the separator, and the materials required for providing the insulating layer can be reduced.

[0021] When laser die-cutting the positive electrode plate, beads, burrs, etc. may be generated at its top and bottom ends. By coating the insulating layer on the top edge and the bottom edge of the positive electrode plate respectively, the ceramic layer can fill the corresponding edges of the positive electrode plate, making the edges smooth and reducing the probability of the positive electrode plate piercing the separator.

[0022] Coating the insulating layer on the root of the positive electrode tab can maintain an insulating state when the positive electrode tab is folded and overlaps with the negative electrode tab.

[0023] By providing the insulating layer on the negative electrode main body, the positive electrode plate can be prevented from directly contacting the negative electrode main body after piercing the separator, maintaining the insulation between the positive electrode plate and the negative electrode plate, and improving the use safety of the electrode assembly.

[0024] Coating an insulating layer on the root of the negative electrode tab can maintain insulation between the negative electrode tab and the positive electrode plate when the negative electrode tab is bent and overlapped with the positive electrode plate, avoiding short circuit.

[0025] Both ends of the separator exceed the two ends of the negative electrode body by 2 mm to 3.4 mm in the connection direction between the negative electrode tab and the negative electrode body, which can preferably maintain insulation between the positive electrode plate and the negative electrode plate during the assembly and use of the electrode assembly, and keep the ion conduction channel between the positive electrode plate and the negative electrode plate unobstructed.

[0026] Both ends of the separator exceed the two ends of the negative electrode body by 1 mm to 2 mm in the direction perpendicular to the orientation of the negative electrode tab, which can preferably maintain insulation between the positive electrode plate and the negative electrode plate during the assembly and use of the electrode assembly, and keep the ion conduction channel between the positive electrode plate and the negative electrode plate unobstructed.

[0027] The insulating layer made of ceramic material not only has good insulation effect, but also can enhance the surface strength of the electrode plate, and can also fill defects such as molten beads and burrs, making the corners of the positive electrode plate not easy to warp and pierce the separator.

[0028] Another object of the present utility model is to provide a battery equipped with the electrode assembly as described above.

[0029] The battery of the present utility model has the same beneficial effects as the electrode assembly as described above compared with the prior art, and will not be elaborated herein. Description of the Drawings

[0030] The drawings constituting a part of the present utility model are used to provide a further understanding of the present utility model. The schematic embodiments of the present utility model and their descriptions are used to explain the present utility model and do not constitute an improper limitation to the present utility model. In the drawings:

[0031] Figure 1 is an exploded view of the electrode assembly according to Embodiment 1 of the present utility model;

[0032] Figure 2 is a schematic diagram of the stacked structure of the electrode assembly according to Embodiment 1 of the present utility model;

[0033] Figure 3 is a schematic diagram of the structure when the bottom end of the positive electrode body of the electrode assembly according to Embodiment 1 of the present utility model pierces the separator;

[0034] Figure 4 is a schematic diagram of the structure of the electrode assembly according to Embodiment 1 of the present utility model when the negative electrode tab overlaps the positive electrode plate.

[0035] Description of the Reference Numerals:

[0036] 1. Positive electrode plate;

[0037] 101. Positive electrode body; 102. Positive electrode tab;

[0038] 2. Negative electrode sheet;

[0039] 201. Negative electrode body; 202. Negative electrode tab;

[0040] 3. Separator;

[0041] 4. Insulating layer. Detailed implementation manners

[0042] It should be noted that, without conflict, the embodiments and features in the embodiments of the present utility model can be combined with each other.

[0043] In the description of the present utility model, it should be noted that if terms indicating orientation or positional relationship such as "upper", "lower", "inner", "outer", etc. appear, they are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model. In addition, if terms such as "first", "second", etc. appear, they are also only for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0044] In addition, in the description of the present utility model, unless otherwise clearly defined, the terms "installation", "connection", "connection", "connecting member" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood in combination with specific situations.

[0045] The present utility model will be described in detail below with reference to the drawings and in combination with embodiments.

[0046] Embodiment 1

[0047] This embodiment relates to an electrode assembly to improve the safety of the electrode assembly during use.

[0048] In terms of the overall structure, an electrode assembly in this embodiment includes a positive electrode sheet, a separator, and a negative electrode sheet stacked in sequence. When a part of the positive electrode sheet pierces the separator, an insulating layer is provided between the pierced part of the positive electrode sheet and the negative electrode sheet to form insulation protection between the positive electrode sheet and the negative electrode sheet.

[0049] With the above settings, in the electrode assembly of this embodiment, by providing an insulating layer, when the positive electrode sheet pierces the separator, the insulating layer is provided between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet and the negative electrode sheet do not come into direct contact, so it is not easy to generate a short - circuit situation, making the electrode assembly have higher safety performance.

[0050] Based on the above overall introduction, referring to Figure 1 and Figure 2 As shown, specifically, the positive electrode sheet 1, the negative electrode sheet 2 and the separator 3 of this embodiment are all rectangular structures and are stacked. In the use of a conventional electrode assembly, the positive electrode sheet 1 usually uses a metal foil as a current collector, and positive electrode active materials are provided on both side surfaces of the metal foil. During the assembly operation of the electrode assembly, the positive electrode sheet 1 will be pulled, which easily causes the corners of the positive electrode sheet 1 to warp and pierce the separator 3, contacting the negative electrode sheet 2 on the other side of the separator 3, destroying the insulation relationship of the electrode assembly and resulting in a short - circuit. In this embodiment, after the positive electrode sheet 1 pierces the separator 3, the insulation between the positive electrode sheet 1 and the negative electrode sheet 2 can still be relied on the insulating layer 4, so that the electrode assembly has better short - circuit prevention performance and the use safety is improved.

[0051] Among them, regarding the specific structure of the positive electrode sheet 1, the positive electrode sheet 1 of this embodiment includes a positive electrode main body 101 and a positive electrode tab 102 connected to the top end of the positive electrode sheet 1. The corners of the positive electrode main body 101 are coated with an insulating layer 4. One end of the positive electrode main body 101 connected to the positive electrode tab 102 is the top end of the positive electrode main body 101, and the other end relative to the top end of the positive electrode main body 101 is the bottom end of the positive electrode main body 101. Except for the area coated with the insulating layer 4 on the positive electrode main body 101, other areas are coated with positive electrode active materials to ensure the content of positive electrode active materials in the positive electrode sheet 1.

[0052] In the actual production of the battery, when the electrode assembly is installed in the housing, it is inevitable that the positive electrode main body will be pulled and squeezed, and this situation more often occurs at the corners of the positive electrode main body. The corner structure is relatively sharp. After warping, the tip abuts against the separator, and then the separator may be pierced with a relatively small force, contacting the negative electrode sheet on the other side of the separator and generating a short - circuit phenomenon. Referring to Figure 2 and Figure 3 As shown, after coating the insulating layer 4 at the corners of the positive electrode main body 101, when the corners of the positive electrode main body 101 pierce the separator 3, they will not directly contact the negative electrode sheet 2, thereby reducing the occurrence of short - circuit phenomena and improving the safety performance of the electrode assembly. The positive electrode main body 101 in this embodiment is rectangular, and the insulating layer 4 is coated at its four corners to reduce the possible short - circuit situation caused by the corners of the positive electrode main body 101 piercing the separator 3.

[0053] In addition, in order to further improve the insulation performance between the positive electrode main body 101 and the negative electrode sheet 2, referring to Figure 1 and Figure 2As shown, insulating layers 4 are coated on both the top edge and the bottom edge of the positive electrode body 101. The outer shape of the positive electrode body 101 is usually formed by laser die-cutting. In the laser die-cutting process, bead melting and burrs may occur at the top and bottom of the positive electrode body 101 due to laser cutting parameters. This may cause the part of the top edge and the bottom edge of the positive electrode body 101 that is not at the corner to pierce the separator 3, damaging the insulation of the separator 3 and thus resulting in a short-circuit situation. Therefore, after the insulating layers 4 are coated on the top edge and the bottom edge of the positive electrode body 101, the insulating layers 4 can level the top edge and the bottom edge of the positive electrode body 101, making the surface of the cut positive electrode body 101 smooth without bead melting and burrs.

[0054] During the actual assembly of the electrode assembly, the positive electrode tab 102 needs to be folded. After the positive electrode tab 102 is folded, it may come into contact with the negative electrode sheet 2, resulting in a short-circuit situation. Therefore, in this embodiment, an insulating layer 4 is also coated on the root of the positive electrode tab 102. When the electrode assembly is assembled, even if the positive electrode tab 102 abuts against the negative electrode sheet 2, there is the insulating layer 4 for insulation protection, and it is not easy to have a short-circuit situation, improving the safety performance of the electrode assembly.

[0055] As a preferred implementation form, the tabs of the positive electrode sheet 1 and the tabs of the negative electrode sheet 2 face in opposite directions. The negative electrode sheet 2 includes a negative electrode body 201 and a negative electrode tab 202 connected to the top of the negative electrode sheet 2. An insulating layer 4 is coated on the edge of the end where the negative electrode body 201 is connected to the negative electrode tab 202. The projection of the other edge of the positive electrode sheet 1 opposite to its tab on the negative electrode sheet 2 is located within the area of the insulating layer 4 on the negative electrode body 201. By providing the insulating layer 4 on the negative electrode body 201, the positive electrode sheet 1 can be prevented from directly contacting the negative electrode body 201 after piercing the separator 3, maintaining the insulation between the positive electrode sheet 1 and the negative electrode sheet 2 and improving the use safety of the electrode assembly. Except for the area coated with the insulating layer 4 on the negative electrode body 201, other areas are coated with negative active material to ensure the content of the negative active material of the negative electrode sheet 2, which is beneficial to increasing the capacity of the battery using the electrode assembly of this embodiment.

[0056] It should be noted that the tabs of the positive electrode plate 1 and the tabs of the negative electrode plate 2 face in opposite directions, which can be used in common blade-shaped battery cells. One end of the negative electrode body 201 connected to the negative electrode tab 202 is the top end of the negative electrode body 201, and the opposite end is the bottom end of the negative electrode body 201. By providing an insulating layer 4 in the area of the negative electrode body 201 corresponding to the bottom edge position of the positive electrode body 101, even if the bottom edge of the positive electrode body 101 is not provided with the insulating layer 4, it can play an insulating role between the positive electrode body 101 and the negative electrode body 201 when the bottom part of the positive electrode body 101 pierces the separator 3. When the bottom edge of the positive electrode body 101 is coated with the insulating layer 4 and the bottom end of the negative electrode body 201 is also coated with the insulating layer 4, it can provide two layers of protection between the bottom end of the positive electrode body 101 and the negative electrode body 201 after the positive electrode body 101 pierces the separator 3, making the insulation more reliable.

[0057] In addition, as shown in Figure 2 and Figure 4 the root of the negative electrode tab 202 is coated with the insulating layer 4. When the negative electrode tab 202 is bent and abuts against the positive electrode plate 1, the abutting position is within the area of the insulating layer 4 on the negative electrode tab 202. During the assembly process of the electrode assembly, the negative electrode tab 202 needs to be folded and assembled into the housing. After the negative electrode tab 202 is bent, it may come into contact with the positive electrode plate 1, resulting in a short circuit. By coating the root of the negative electrode tab 202 with the insulating layer 4, the insulating layer 4 can block when the negative electrode tab 202 abuts against the positive electrode plate 1, maintaining an insulating state and thus avoiding a short circuit. At the same time, because the bottom end of the positive electrode body 101 is also coated with the insulating layer 4, there is a double insulating layer 4 protection between the negative electrode tab 202 and the positive electrode plate 1 when the negative electrode tab 202 abuts against the positive electrode plate 1, making the short-circuit prevention reliability of the electrode assembly higher.

[0058] Based on the consideration of the insulating performance of the insulating layer 4, in this embodiment, the insulating layer 4 is preferably made of a ceramic material, that is, the positive electrode body 101 or the negative electrode body 201 is coated with ceramic powder. The ceramic powder is nano-sized alumina and boehmite particles, which have a series of excellent properties such as high thermal stability, chemical stability, corrosion resistance, and high hardness. Among them, the surface of boehmite is smooth. After being coated on the positive electrode body 101, it can fill the edge of the positive electrode body 101, making the surface of the cut positive electrode body 101 smooth and free of burrs. The surface of the negative electrode plate 2 is rough. After coating ultra-small particle size boehmite, the pore formation of the negative electrode plate 2 can become uniform, which can improve the wettability of the electrolyte, making the lithium ions more smooth during the charge and discharge process. Of course, the insulating layer 4 can also be made of insulating tape or insulating film, but due to process problems, the production efficiency is relatively low, and various performances are weaker than those of the ceramic insulating layer 4.

[0059] Regarding the specific dimensions of the separator 3, in this embodiment, in the connection direction of the negative electrode tab 202 and the negative electrode main body 201, the distances a by which both ends of the separator 3 exceed both ends of the negative electrode main body 201 are 2 mm to 3.4 mm. In the direction perpendicular to the orientation of the negative electrode tab 202, the distances b by which both ends of the separator 3 exceed both ends of the negative electrode main body 201 are 1 mm to 2 mm. Such a setting can enable the separator 3 to better maintain insulation between the positive electrode sheet 1 and the negative electrode sheet 2 during the assembly and use of the electrode assembly, and keep the ion conduction channel between the positive electrode sheet 1 and the negative electrode sheet 2 unobstructed, making the ion conduction between the positive electrode sheet 1 and the negative electrode sheet 2 more efficient.

[0060] In this embodiment, by coating the insulating layer 4 on the positive electrode sheet 1 and the negative electrode sheet 2, when the positive electrode sheet 1 pierces the separator 3, the insulating layer 4 can separate the positive electrode sheet 1 and the negative electrode sheet 2, improving the insulation performance between the positive electrode sheet 1 and the negative electrode sheet 2. When the positive electrode tab 102 is folded and overlapped with the negative electrode main body 201 or the negative electrode tab 202 is folded and overlapped with the positive electrode main body 101, the insulating layer 4 can also separate the positive electrode sheet 1 and the negative electrode sheet 2, keeping the insulation between the positive electrode sheet 1 and the negative electrode sheet 2, reducing the possibility of short circuit occurrence, and improving the safety performance of the electrode assembly.

[0061] Embodiment Two

[0062] This embodiment relates to a battery equipped with the electrode assembly in Embodiment One.

[0063] By assembling the electrode assembly in Embodiment One, when the positive electrode sheet pierces the negative electrode sheet inside the battery in this embodiment, the insulation between the positive electrode sheet and the negative electrode sheet can still be maintained, and short circuit is not likely to occur, improving the safety performance of the battery. When the positive electrode tab is folded and overlapped with the negative electrode main body or the negative electrode tab is overlapped with the positive electrode main body inside the battery, the insulation relationship between the positive electrode sheet and the negative electrode sheet can also be maintained, similarly improving the safety performance of the battery.

[0064] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An electrode assembly, characterized in that: include: A positive electrode sheet, a separator and a negative electrode sheet are stacked in sequence; An insulating layer is provided between the positive electrode sheet and the negative electrode sheet. When the positive electrode sheet pierces the separator, the insulating layer constitutes insulation between the positive electrode sheet and the negative electrode sheet.

2. The electrode assembly according to claim 1, characterized in that: The positive electrode sheet comprises a positive electrode body and a positive electrode tab connected to the top of the positive electrode sheet, and the corner of the positive electrode body is coated with the insulating layer.

3. The electrode assembly according to claim 2, characterized in that: The top edge and the bottom edge of the positive electrode body are both coated with the insulating layer.

4. The electrode assembly according to claim 2, characterized in that: The root of the positive electrode tab is coated with the insulating layer.

5. The electrode assembly according to claim 1, characterized in that: The tab of the positive electrode sheet and the tab of the negative electrode sheet face opposite directions. The negative electrode sheet comprises a negative electrode body and a negative electrode tab connected to the top of the negative electrode sheet. The edge of one end of the negative electrode body connected to the negative electrode tab is coated with the insulating layer. The projection of the other end edge of the positive electrode sheet opposite to its tab on the negative electrode sheet is located within the insulating layer area on the negative electrode body.

6. The electrode assembly according to claim 5, characterized in that: The root of the negative electrode tab is coated with the insulating layer. When the negative electrode tab is bent and overlapped with the positive electrode sheet, the overlapping position is located in the insulating layer area on the negative electrode tab.

7. The electrode assembly according to claim 5, characterized in that: In the connection direction between the negative electrode tab and the negative electrode body, both ends of the separator extend beyond both ends of the negative electrode body by 2 mm to 3.4 mm respectively.

8. The electrode assembly according to claim 5, characterized in that: In a direction perpendicular to the direction of the negative electrode tab, two ends of the separator extend beyond two ends of the negative electrode body by 1 mm to 2 mm respectively.

9. The electrode assembly according to any one of claims 1 to 8, characterized in that: The insulating layer is made of ceramic material.

10. A battery, characterized in that: The battery is equipped with the electrode assembly according to any one of claims 1 to 9.

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