Sealing mechanism and single battery

Abstract

The invention discloses a sealing mechanism and a single battery. The sealing mechanism comprises a cylindrical body formed by an additive which can be dissolved in electrolyte, at least the first end face of the columnar body has a separator which is insoluble in the electrolyte. The sealing mechanism is installed on the shell of the single battery, when electrolyte is injected, the sealing mechanism is dissolved, a through hole is formed in the single battery, unpacking of the single battery is achieved, no special tool is needed in the process, operation is easy, and the manufacturing cost is reduced; and meanwhile, the sealing mechanism is formed by curing an electrolyte additive, so that the performance of the high-capacity battery is improved after the electrolyte additive is dissolved in the electrolyte.

Description

Technical Field

[0001] The invention belongs to the field of batteries, and in particular relates to a sealing mechanism and a single battery. Background Art

[0002] In order to meet the use scenarios of large capacity, existing large-capacity batteries are formed by connecting multiple finished single cells in parallel, series or series-parallel combination to form a battery module. Battery modules connected in series can increase the total voltage, while battery modules connected in parallel can increase the total capacity.

[0003] However, regardless of the above methods, there are differences between the individual cells in the existing battery modules, which results in differences in the consumption of electrolyte and lithium ions in each individual cell after the battery module has been running for a period of time. The uniformity of each individual cell is poor, which will directly lead to the limited cycle life of the battery module. Therefore, how to improve the uniformity of each individual cell in the battery module while ensuring large capacity has become the focus and difficulty of research in this field.

[0004] The related technology provides a large-capacity battery in which the electrolyte areas of each single cell are interconnected, so that each single cell is in a unified shared electrolyte system. Therefore, the electrolyte consumption of each single cell is always kept consistent, thereby improving the uniformity of each single cell, and the cycle life of the large-capacity battery is improved to a certain extent.

[0005] The single cell of the large-capacity battery is provided with a sealing mechanism, which needs to be opened when forming a shared electrolyte system, and then a through hole for sharing the electrolyte is formed on the single cell. When the sealing mechanism recorded in the related art is opened, special tooling is required, which makes the operation more complicated and the production cost higher. Summary of the invention

[0006] In order to avoid the problem in the related art that special tooling is required when unpacking single cells of large-capacity batteries, resulting in complicated operations and high production costs, a first aspect of the present invention provides a sealing mechanism.

[0007] The sealing mechanism includes a columnar body formed by an additive soluble in an electrolyte; at least the first end face of the columnar body has an isolation membrane, which is insoluble in the electrolyte. The sealing mechanism is installed on the shell of the single battery. When the electrolyte is injected, the sealing mechanism is dissolved, and a through hole is formed on the single battery, so that the single battery can be unpacked. The process does not require special tooling, is simple to operate, and reduces the production cost. At the same time, since the sealing mechanism is solidified by the electrolyte additive, it can improve the performance of the large-capacity battery to a certain extent after being dissolved in the electrolyte.

[0008] Furthermore, the columnar body is made of propylene sulfate, ethylene carbonate or diphenyl carbonate.

[0009] Furthermore, in order to enable the sealing mechanism to slowly dissolve in the electrolyte and thus continuously improve the electrolyte performance, the first end face, the second end face and the side face of the column are coated with an isolation film, and a blind hole is provided in the column from the second end face to the first end face.

[0010] Furthermore, in order to achieve both fast opening speed and slow decomposition of the sealing mechanism in the electrolyte, the depth of the blind hole accounts for 90% of the length of the columnar body.

[0011] Furthermore, in order to enhance the sealing reliability of the sealing mechanism for the single battery, a circle of grooves for installing the sealing ring is engraved on the side wall of the columnar body.

[0012] Furthermore, the columnar body comprises a first cylindrical section and a second cylindrical section, the outer diameter of the first cylindrical section is greater than that of the second cylindrical section, and the groove is arranged on the side surface of the second cylindrical section.

[0013] Furthermore, the first end surface, the second end surface and the side surface of the columnar body are covered with an isolation film, and the second end surface is provided with a blind hole.

[0014] Furthermore, the above-mentioned isolation film is a PP film.

[0015] The second aspect of the present invention provides a single cell, comprising a battery housing and the sealing mechanism provided in the first aspect; the battery housing has a convex ring, and the sealing mechanism is fixedly sealed in the convex ring.

[0016] Furthermore, the protruding direction of the convex ring is toward the inner cavity of the battery.

[0017] Furthermore, a clamping portion for clamping the heat transfer tube is provided on the pole of the above-mentioned single battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of the first large-capacity battery;

[0019] Figure 2 is a schematic diagram of the structure of a second large-capacity battery;

[0020] Figure 3 is a cross-sectional view of the sealing mechanism;

[0021] Figure 4 It is a structural schematic diagram of a single battery;

[0022] Figure 5 A cross-sectional view of a single cell.

[0023] The accompanying drawings are marked as follows:

[0024] 100-box, 200-single battery, 300-hollow component, 400-sealing mechanism, 1-column, 11-first cylindrical section, 12-second cylindrical section, 2-first end face, 3-second end face, 4-blind hole, 5-groove, 6-convex ring, 7-sealing ring, 500-heat transfer tube. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "top" or "upper" etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention 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 cannot be understood as a limitation on the present invention.

[0028] The following two large-capacity battery structures are applicable to this embodiment:

[0029] The first structure:

[0030] like Figure 1 As shown, the large-capacity battery includes a box body 100 and N single cells 200; N ≥ 2; the N single cells 200 are connected in parallel in sequence and arranged in the inner cavity of the box body 100; the inner cavity of each single cell 200 includes an electrolyte area and a gas area, and the electrolyte areas of the inner cavities of each single cell 200 are interconnected, so that each single cell is placed in an electrolyte system; a pole avoidance hole is provided on the top of the box body 100 to enable the poles of each single cell 200 to extend out; the poles of each single cell 200 extend out of the pole avoidance hole and the box body area corresponding to the pole avoidance hole is fixedly sealed with the outer shell of the single cell 200.

[0031] In order to ensure the connectivity of the electrolyte in each single cell, an electrolyte channel is provided at the sealing mechanism position of each single cell shell corresponding to the box body (the electrolyte channel is provided at the bottom of the box body), and the electrolyte in each single cell is connected through the electrolyte channel, so that the continuity of the electrolyte liquid level is better.

[0032] The second structure:

[0033] like Figure 2 As shown, the large-capacity battery includes a hollow component 300 and N single cells 200; N ≥ 2; the N single cells 200 are connected in parallel in sequence, and the inner cavity of each single cell 200 includes an electrolyte area and a gas area, and the electrolyte areas in the inner cavities of each single cell 200 are interconnected through the hollow component 300 (the hollow component is an electrolyte channel), thereby placing each single cell in an electrolyte system.

[0034] The hollow component 300 may be a complete circular or rectangular tube; the hollow component may also be formed by extruding and splicing sub-pipelines on each single battery.

[0035] In the above two types of large-capacity batteries, the electrolyte areas of the individual cells need to be connected to each other, and the sealing mechanism 400 on the individual cells needs to be opened, such as Figure 3 As described above, the sealing mechanism 400 in this embodiment uses a columnar body 1 formed by an additive that can be dissolved in the electrolyte; at least the first end face 2 of the columnar body 1 has an isolation membrane, and the isolation membrane is insoluble in the electrolyte. The first end face 2 is the surface close to the inner cavity of the single cell. The reason for providing the isolation membrane is to prevent the electrolyte in the single cell from dissolving the columnar body before the single cell is unpacked.

[0036] The sealing mechanism 400 is installed on the outer shell of the single battery 200. When the electrolyte is injected into the electrolyte channel, the sealing mechanism 400 is dissolved, and a through hole is formed on the single battery 200, so that the single battery can be unpacked. This process does not require special tooling, is simple to operate, and reduces the production cost. At the same time, since the sealing mechanism is formed by an electrolyte additive, it can improve the performance of large-capacity batteries to a certain extent after being dissolved in the electrolyte.

[0037] Specifically, the columnar body is made of propylene sulfate or ethylene carbonate or diphenyl carbonate as an electrolyte additive, and the production process is as follows:

[0038] First, propylene sulfate crystals, ethylene carbonate crystals, or diphenyl carbonate crystals are ground into powder;

[0039] Then, the powder is heated to convert it into a liquid additive;

[0040] Then pour the liquid additive into the prepared mold, and form a column after natural cooling;

[0041] Finally, take out the column.

[0042] Among them, propylene sulfate, as an electrolyte additive, can improve the low-temperature performance of the electrolyte and prevent PC molecules from being embedded in the graphite electrode;

[0043] As an electrolyte additive, ethylene carbonate has the following functions:

[0044] 1. Transferring ions in battery reactions: In a battery, when the positive electrode and the negative electrode react, ions need to move in the battery to complete the reaction. Ethylene carbonate acts as an electrolyte to transfer ions and promote the reaction.

[0045] 2. Maintain charge balance: In the battery reaction, the positive and negative electrodes will consume or release charge. The charge needs to be balanced, otherwise it will affect the battery performance and life. Ethylene carbonate can maintain the charge balance in the battery by transferring ions, ensuring the normal operation of the battery.

[0046] 3. Improve battery performance: improve battery conductivity, enhance battery stability and safety.

[0047] As an electrolyte additive, diphenyl carbonate has good redox stability and thermal stability, can provide high conductivity and extend battery life.

[0048] Therefore, in actual use, any one of the above three substances can be selected as the material to make the column according to the needs, and then the performance of the battery can be improved and enhanced from different aspects.

[0049] The isolation film only needs to meet the requirements of not reacting with the electrolyte and not dissolving in the electrolyte. There are many such film materials. For safety and reliability considerations, the isolation film in this embodiment is preferably a PP film. When making the sealing mechanism, the isolation film can be coated on the column by heat sealing, coating or gluing.

[0050] Preferably, if Figure 3 As shown, since the electrolyte additive is used as the sealing mechanism 400 in this embodiment, in order to enable the sealing mechanism to slowly dissolve in the electrolyte, thereby continuously improving the electrolyte performance, the first end face 2, the second end face 3 and the side of the column 1 are coated with an isolation film (the second end face 3 is the surface away from the inner cavity of the single cell), and the column is provided with a blind hole 4 from the second end face 3 to the first end face 2. When the electrolyte is injected into the electrolyte channel, the electrolyte can only contact the hole wall and the hole bottom of the blind hole due to the existence of the isolation film. First, the bottom of the blind hole is penetrated, and the single cell is opened. Since the rest of the column is covered by the isolation film, the electrolyte is always only in contact with the hole wall, and the electrolyte continues to slowly dissolve the column.

[0051] Preferably, in order to achieve both fast opening speed and slow decomposition of the sealing mechanism in the electrolyte, the depth of the blind hole 4 in this embodiment accounts for 90% of the length of the columnar body 1. That is to say, the bottom of the blind hole is relatively thin, and the bottom of the blind hole will be penetrated in a very short time, thereby realizing the opening of the single battery.

[0052] Preferably, in order to enhance the sealing reliability of the sealing mechanism for the single battery, a groove 5 for installing a sealing ring is provided on the side wall of the columnar body 1 of this embodiment. The groove can be provided in the following manner:

[0053] 1. A circle of annular protrusions is set on the inner wall of the mold, and a groove can be formed on the column after the liquid additive is poured into the mold and cooled.

[0054] 2. After the column is formed, a groove is formed on the column by machining.

[0055] Preferably, if Figure 3 As shown, in order to facilitate the installation of the sealing mechanism and the single battery housing, the columnar body 1 includes a first cylindrical section 11 and a second cylindrical section 12. The outer diameter of the first cylindrical section 11 is larger than that of the second cylindrical section 12, and the groove 5 is provided on the side of the second cylindrical section 12.

[0056] like Figure 4 and Figure 5 As shown, this embodiment provides a single battery 200, including a shell and a battery cell assembly; the battery cell assembly described herein may also be referred to as an electrode assembly, which is composed of a positive electrode, a diaphragm, and a negative electrode arranged in sequence and assembled by a lamination or winding process; the shell includes an upper cover plate, a lower cover plate, and a cylinder; in some cases, the lower cover plate and the cylinder may also be formed as one piece. The shell has a convex ring 6 (in this embodiment, the convex ring 6 is arranged at the bottom, that is, arranged on the lower cover plate), and the sealing mechanism 400 is fixedly sealed in the convex ring 6.

[0057] There are several ways to fix the seal to the convex ring:

[0058] 1. Apply adhesive to the outer wall of the sealing structure 400 or the inner wall of the convex ring 6, and seal and fix them by bonding;

[0059] 2. The sealing mechanism 400 is directly fixed in the convex ring 6 by means of interference fit;

[0060] 3. The sealing mechanism 400 is fixed in the convex ring 6 by means of interference fit with the sealing ring 7.

[0061] Since method 3 is easy to operate and has stronger sealing reliability, method 3 is preferred in this embodiment.

[0062] Preferably, in order to ensure the flatness of the appearance of the single battery, the protruding direction of the convex ring 6 in this embodiment is toward the inner cavity of the battery.

[0063] Since the most concentrated heat in the single cell 200 is at the pole, each single cell pole in this embodiment is provided with a heat transfer pipe clamping portion; see Figure 1 and Figure 2 The heat transfer tube 500 is fixed on the heat transfer tube clamping part of each single battery pole, and the heat transfer tube 500 and the heat transfer tube clamping part of each single battery are insulated. The heat transfer tube not only realizes balanced heat dissipation of each single battery, but also improves the safety of large-capacity batteries. At the same time, the structure is simple, easy to manufacture and assemble, and has low manufacturing cost. The heat transfer tube clamping part can be a groove or a through hole set on the polarity terminal.

[0064] In other embodiments, the sealing mechanism may also be configured in a sheet shape and fixedly sealed on the through hole of the single cell housing by bonding. If a sheet-shaped sealing mechanism is used, the sealing mechanism can be dissolved in a relatively short time, and thus can only improve the electrolyte performance in the initial operation of the large-capacity battery, and the cycle life of the large-capacity battery is not significantly improved.

Claims

1. A sealing mechanism, characterized in that: The invention comprises a columnar body formed by an additive soluble in an electrolyte; at least a first end surface of the columnar body has an isolation film which is insoluble in the electrolyte.

2. A sealing mechanism according to claim 1, characterized in that: The columnar body is made of propylene sulfate, ethylene carbonate or diphenyl carbonate.

3. A sealing mechanism according to claim 2, characterized in that: The first end surface, the second end surface and the side surface of the columnar body are covered with an isolation film, and a blind hole is arranged on the columnar body from the second end surface to the first end surface.

4. A sealing mechanism according to claim 3, characterized in that: The hole depth of the blind hole accounts for 90% of the length of the columnar body.

5. A sealing mechanism according to any one of claims 1 to 4, characterized in that: A circle of grooves for installing a sealing ring is engraved on the side wall of the columnar body.

6. A sealing mechanism according to claim 5, characterized in that: The columnar body comprises a first cylindrical section and a second cylindrical section, the outer diameter of the first cylindrical section is larger than that of the second cylindrical section, and the groove is arranged on the side surface of the second cylindrical section.

7. A sealing mechanism according to claim 6, characterized in that: The isolation film is a PP film.

8. A single cell battery, characterized in that: It comprises a battery housing and a sealing mechanism as claimed in any one of claims 1 to 7; the battery housing is provided with a convex ring, and the sealing mechanism is fixedly sealed in the convex ring.

9. The single cell according to claim 8, characterized in that: The protruding direction of the convex ring faces the inner cavity of the battery.

10. The single cell according to claim 9, characterized in that: The pole of the single cell is provided with a clamping part for clamping the heat transfer tube.

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