Battery cell structure and method for solving center hole collapse

Abstract

The invention discloses a cell structure and method for solving center hole collapse, an expansion glue stick is inserted in a center hole of a roll core, and the outer diameter of the expansion glue stick which is not infiltrated with electrolyte is smaller than the inner diameter of the center hole; the outer wall of the expansion glue stick extrudes and supports the inner wall of the center hole after electrolyte infiltration, and the center hole does not collapse in the circulation process. In an initial state, the expansion glue stick is dry and not infiltrated with electrode liquid and needs to be inserted into the center hole, so that the outer diameter of the expansion glue stick is smaller than the inner diameter of the center hole, and the expansion glue stick expands after being inserted and infiltrated with the electrolyte, so that the outer wall of the expansion glue stick clings to and extrudes the inner wall of the center hole to provide supporting force for the center hole; in other words, no gap exists between the center hole and the expansion glue stick, lithium ion transmission in the charge-discharge cycle process is facilitated, supporting force can be provided for the center hole, a compressible space is further formed between the expansion glue stick and the center hole, a release space can be provided for the expansion force of the pole piece of the inner ring of the battery cell in the charge-discharge cycle process, and the lithium ion battery is more stable. And the safety performance of the battery cell is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of cylindrical batteries, and in particular relates to a battery cell structure and method for solving the problem of battery cell center hole collapse. Background Art

[0002] Lithium-ion cylindrical batteries are important energy storage devices that are currently widely used in electric vehicles, mobile phones and other fields. However, during use, the center hole of the battery cell will collapse after a cycle, and the large deformation inside the electrode will cause the positive and negative electrodes of the battery to separate, the effective electrochemical reaction area will be reduced, the capacity will decay, and there is a hidden danger of internal short circuit, which will seriously affect the performance, reliability and life of the battery cell. The current method to solve the collapse of the center hole is to add chemical fillers or support tubes to the center hole. The chemical fillers used are generally a mixture of lithium salts, carbon materials and polymer materials, but the operation is relatively complicated, and as the number of cycles increases, the mixture will react, resulting in structural instability and collapse, and there is still a risk of center hole collapse; and the filling support tube body, because it must be inserted into the center hole, there must be a gap between the inner wall of the center hole, that is, the support tube body actually plays a supporting role only after the center hole has collapsed to a certain extent. Summary of the invention

[0003] The present invention provides a battery cell structure and method for solving the problem of battery cell center hole collapse, using a simple and operable structure to solve the problem of center hole collapse, and the center hole will not collapse no matter how many cycles are performed, thereby solving the deficiencies described in the above-mentioned prior art.

[0004] The technical solution adopted by the present invention is: A battery core structure for solving the problem of central hole collapse includes a winding core and an electrolyte. An expandable support body is inserted into the central hole of the winding core. The outer diameter of the expandable support body not soaked in the electrolyte is smaller than the inner diameter of the central hole. After being soaked in the electrolyte, the outer wall of the expandable support body squeezes and supports the inner wall of the central hole. During the cycle, the central hole does not collapse. In the initial state, the expandable support body is dry and not soaked in the electrode liquid. To be inserted into the central hole, the outer diameter of the expandable support body is smaller than the inner diameter of the central hole. After insertion, the expandable support body will expand after being soaked in the electrolyte, so that the outer wall of the expandable support body is tightly attached to and squeezes the inner wall of the central hole, giving the central hole a supporting force. That is, there is no gap between the central hole and the expandable support body, which is convenient for the transmission of lithium ions during the charge and discharge cycle and can provide a supporting force for the central hole. There is also a compressible space between the expandable support body and the central hole, which can provide a release space for the expansion force of the inner ring electrode of the battery cell during the charge and discharge cycle, thereby improving the safety performance of the battery cell.

[0005] As a preferred solution of the present invention, the length of the expandable support body is not shorter than the length of the central hole, and the expandable support body can fully support the length direction of the central hole to achieve full length of the central hole without collapse.

[0006] As a preferred solution of the present invention, the expandable support body is an expansion glue stick or a swelling glue stick. Alternatively, an expansion glue layer or a swelling glue layer is arranged outside the support tube body, and the expansion glue layer or the swelling glue layer expands after being soaked in electrolyte to support the central hole.

[0007] As a preferred solution of the present invention, the expandable support body is provided with exhaust holes. For cylindrical battery cells, the exhaust holes are provided at the center to accelerate the discharge of gas and enhance the safety performance of the battery cells.

[0008] As a preferred solution of the present invention, the exhaust channel is arranged along the axial direction of the expandable support body, and the exhaust channel runs through the expandable support body.

[0009] The present invention also provides a method for solving the problem of central hole collapse, the steps are as follows: Prepare an expandable support body; the expandable support body is an expandable rubber stick or a swelling rubber stick; the expansion tape or the swelling tape is used for winding, which is simple and easy to operate and has low cost; Insert the expandable support into the central hole of the winding core, there is a gap between the expandable support and the wall of the central hole, and in the initial state, the expandable support is inserted into the central hole, and the outer diameter of the expandable support must be smaller than the inner diameter of the central hole; After being soaked in electrolyte, the expandable support body will swell in contact with the electrolyte and there will be no gap between it and the wall of the central hole. Before packaging, the expandable support body must be soaked in electrode liquid to swell, and only after swelling can it play a supporting role, and the expandable support body will not swing in the central hole.

[0010] As a preferred embodiment of the present invention, when an expansion glue stick is used, the expansion glue stick is made of an expansion tape; the length of the expansion glue stick is equal to the length of the center hole. The full length of the expansion glue stick abuts against the support center hole to prevent collapse of any part of the center hole. When a swelling glue stick is used, the swelling glue stick is made of a swelling tape, and the length of the swelling glue stick is equal to the length of the center hole.

[0011] As a preferred solution of the present invention, the outer wall of the expandable support body always abuts against the inner wall of the central hole, and the central hole does not collapse even after multiple cycles of the battery cell.

[0012] The present invention uses an expandable support body to be inserted into the center hole of the battery cell, and the expandable support body is expanded after being soaked in the electrode liquid to play an elastic supporting role for the center hole. The expandable support body will not be displaced or shaken in the center hole, and can support the center hole in all directions. Even if the battery cell is cycled many times, the structure will not be damaged. The expandable support body is simple to manufacture and low in cost, and can effectively improve the collapse of the center hole of the battery cell and increase the service life of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 It is a schematic diagram of the battery cell structure of the present invention.

[0015] Figure 2 It is a schematic diagram of the expansion principle of the expansion glue stick of the present invention.

[0016] Figure 3 It is a schematic diagram of the swelling of the swelling glue stick of the present invention.

[0017] Figure 4 This is the CT diagram of the existing battery cell after cycling.

[0018] Figure 5 This is a CT diagram of the battery cell of the present invention after cycling.

[0019] Figure 6 This is the CT image of the battery cell filled with support tube after cycling. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The present invention provides an embodiment of a battery core structure for solving the problem of central hole collapse, such as Figure 1As shown, it includes a winding core 1 and an electrolyte, an expandable support body 2 is inserted into the central hole of the winding core 1, the length of the expandable support body 2 is not shorter than the length of the central hole, and the expandable support body can fully support the length direction of the central hole to achieve the full length of the central hole without collapse; and the expandable support body 2 can be an expansion rubber stick, which is wound with an expansion tape and can react with the solvent of the electrolyte to expand; The outer diameter of the expansion rubber stick that is not soaked in electrolyte is smaller than the inner diameter of the center hole; after being soaked in electrolyte, the outer wall of the expansion rubber stick squeezes and supports the inner wall of the center hole. During the cycle, the center hole does not collapse. In the initial state, the expansion rubber stick is dry and not soaked in electrode liquid. To be inserted into the center hole, the outer diameter of the expansion rubber stick is smaller than the inner diameter of the center hole. After insertion, the expansion rubber stick will expand after being soaked in electrolyte. The expansion principle is as follows: Figure 2 As shown, the solvent molecules in the electrolyte continuously penetrate into the expansion rubber stick, the molecular orientation stress of the expansion rubber stick is released, the molecular chain shrinks, the volume remains unchanged, the area decreases, and the thickness increases, so that the whole expands, so that the outer wall of the expansion rubber stick is close to and squeezes the inner wall of the center hole, giving support to the center hole, that is, there is no gap at all between the center hole and the expansion rubber stick, which is convenient for the transmission of lithium ions during the charge and discharge cycle, and can provide support for the center hole, and there is also a compressible space between the expansion rubber stick and the center hole, which can provide a release space for the expansion force of the inner ring electrode of the battery cell during the charge and discharge cycle, thereby improving the safety performance of the battery cell.

[0022] When a swelling glue stick is used, the swelling glue stick is made of a swelling tape. The principle diagram of the swelling tape is as follows: Figure 3 As shown, the solvent molecules in the electrolyte continuously penetrate into the swelling tape, and the gaps between the polymer molecular chains increase, causing the volume to expand and swell, which closely squeezes the inner wall of the central hole and provides support for the central hole.

[0023] In the present embodiment, the expandable support body 2 can use either a solid structure or a hollow structure. In the case of a solid structure, it can play a certain exhaust function because of its own pores. However, in order to exhaust more quickly, an exhaust channel can be set in the center of the expandable support body 2. The exhaust channel is arranged axially along the expandable support body 2 and passes through the expandable support body 2. During the specific production, the central channel formed when the swelling tape or the expansion tape is wound can be used as the exhaust channel. Whether to set the central exhaust channel is selected according to the actual application.

[0024] The present invention also provides an embodiment of a method for solving the central hole collapse, the steps are as follows: Prepare an expansion glue stick or a swelling glue stick; when the expansion glue stick is used, the expansion glue stick is made of an expansion tape; the length of the expansion glue stick is equal to the length of the central hole; when the swelling glue stick is used, the expansion glue stick is made of a swelling tape. The use of the expansion tape or the swelling tape is simple and easy to operate, and the cost is also low.

[0025] Insert the expansion glue stick or swelling glue stick into the center hole of the winding core. There is a gap between the expansion glue stick or swelling glue stick and the center hole wall. In the initial state, the expansion glue stick or swelling glue stick needs to be inserted into the center hole. The outer diameter of the expansion glue stick or swelling glue stick must be smaller than the inner diameter of the center hole.

[0026] After the expansion rubber stick or swelling rubber stick is soaked in electrolyte and expands in contact with electrolyte, there is no gap between it and the center hole wall; before packaging, the expansion rubber stick or swelling rubber stick must be soaked in electrode liquid to expand, and only after expansion can it play a supporting role, and the expansion rubber stick or swelling rubber stick will not swing in the center hole. The expansion rubber stick or swelling rubber stick abuts the supporting center hole with its entire length, and the outer wall of the expansion rubber stick or swelling rubber stick always abuts the inner wall of the center hole to avoid collapse of any part of the center hole, and the center hole will not collapse even after the battery cell is cycled many times.

[0027] The effect of the present invention was observed by using batteries of the same capacity and charging and discharging under the same conditions.

[0028] For cells with unsupported center holes, the center holes collapse after cycling, such as Figure 4 As shown, the central hole of the present invention does not collapse after the cycle, as shown in FIG. Figure 5 As shown; for the battery cell with the central hole filled with the support tube, after the cycle, the central hole also collapses slightly, as shown in Figure 6 shown.

[0029] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0030] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A battery core structure for solving the problem of central hole collapse, comprising a winding core (1) and an electrolyte, characterized in that: An expandable support body (2) is inserted into the central hole of the winding core (1); the outer diameter of the expandable support body (2) not soaked in electrolyte is smaller than the inner diameter of the central hole; after soaking in electrolyte, the outer wall of the expandable support body (2) squeezes and supports the inner wall of the central hole, so that the central hole does not collapse during the circulation process.

2. The battery core structure for solving the problem of central hole collapse according to claim 1, characterized in that: The length of the expandable support body (2) is not shorter than the length of the central hole.

3. The battery core structure for solving the problem of central hole collapse according to claim 1 or 2, characterized in that: The expandable support body (2) is an expansion glue stick or a swelling glue stick.

4. The battery core structure for solving the problem of central hole collapse according to claim 3, characterized in that: The expandable support body (2) is provided with an exhaust channel.

5. The battery core structure for solving the problem of central hole collapse according to claim 4, characterized in that: The exhaust duct is arranged along the axial direction of the expandable support body (2), and the exhaust duct runs through the expandable support body (2).

6. A method for solving the central hole collapse, characterized in that: Here are the steps: Prepare an expandable support body, wherein the expandable support body is an expansion glue stick or a swelling glue stick; Inserting the expandable support into the central hole of the winding core, with a gap between the expandable support rod and the wall of the central hole; The support body is soaked in electrolyte, and after the support body is expanded in contact with the electrolyte, there is no gap between the support body and the wall of the central hole.

7. The method for solving the central hole collapse according to claim 6, characterized in that: The expansion glue stick is made of expansion tape, and the length of the expansion glue stick is equal to the length of the center hole; the swelling glue stick is made of swelling tape, and the length of the swelling glue stick is equal to the length of the center hole.

8. The method for solving the central hole collapse according to claim 7, characterized in that: The outer wall of the expandable support body always contacts the inner wall of the center hole, and the center hole does not collapse even after multiple cycles of the battery cell.

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