CN109786593B

CN109786593B - Rechargeable battery and method for manufacturing the same

Info

Publication number: CN109786593B
Application number: CN201711113239.XA
Authority: CN
Inventors: 叶敏华
Original assignee: Chung Pak Guangdong Battery Industrial Co ltd; CHUNG PAK INVESTMENT Ltd
Current assignee: Chung Pak Guangdong Battery Industrial Co ltd; CHUNG PAK INVESTMENT Ltd
Priority date: 2017-11-10
Filing date: 2017-11-10
Publication date: 2022-02-22
Anticipated expiration: 2037-11-10
Also published as: CN109786593A

Abstract

The present invention provides a rechargeable battery, comprising: the side wall of the negative electrode tank body is provided with a three-stage step structure, and the negative electrode tank body comprises a first stage step, a second stage step and a third stage step with gradually reduced inner diameters from the tail end; the positive current collector is nested in the negative electrode tank body; the sealing ring is arranged between the side wall of the negative electrode tank body and the side wall of the positive current collector and isolates the negative electrode tank body from the positive current collector so as not to contact with the positive current collector and generate short circuit; wherein the seal ring is tightly attached to the second step of the negative can to form a seal part of the battery; the end part of the first step is bent inwards to be attached to the sealing ring to form a sealing position; and the lower portion of the seal ring abuts against the connection between the second step and the third step, thereby obtaining support. The invention also provides a method of manufacturing a rechargeable battery.

Description

Rechargeable battery and method for manufacturing the same

Technical Field

The present invention relates to the field of small batteries, and more particularly, to a rechargeable battery and a method of manufacturing the same.

Background

There are many types of small rechargeable batteries available today. Taking a commonly used lithium ion battery as an example, the housing of the lithium ion battery is usually a cylindrical can. The material of the tank body is iron nickel plating or stainless steel.

Fig. 1 is a cross-sectional view of a small rechargeable lithium ion battery fabricated according to the prior art. Rechargeable lithium ion batteries are generally manufactured by:

after the positive and negative pole pieces are cut as required, the ends are respectively spot-welded with a positive pole tab 106 and a negative pole tab 103. And (3) adding a diaphragm between the positive and negative plates, and rolling the positive and negative plates added with the diaphragm into the cell roll pack 102 through rolling. The lower insulating sheet 104 is placed at the bottom of the can (i.e., the negative terminal 1023), and the cell coil 102 is packed into the can. The negative electrode tab 103 is connected to the side wall of the can body by spot welding. Rolling a circle at a position of about 1-3 mm (e.g., 3mm) below the opening of the can body to form a groove having a width of about 0.8-2.5 mm (e.g., 2mm) and a depth of 0.5-1.5 mm (e.g., 1mm) and protruding inward in the radial direction, and placing the upper insulation sheet 105 below the groove and above the cell wrap 102. Then, the positive electrode current collector including the external contact piece (positive electrode terminal 1020 serving as the top cap), the internal contact piece (positive electrode aluminum cap 1022), and the gasket 108 is put into the can body. The positive current collector is supported by the protrusion of the groove. The outer contact sheet material is a nickel-plated iron sheet, the inner contact sheet is an aluminum sheet, and the sealing ring material is PP (polypropylene) or other plastic materials. Then, the positive tab 106 wrapped with the positive adhesive tape 1021 passes through the upper insulation sheet 105 and is connected with the positive current collector in a spot welding manner.

And (3) after spot welding of the positive current collector, baking the whole battery in an oven at 85 ℃ for 24-36 hours. After cooling, the electrolyte is added into the environment with the relative humidity below 1%. Then, the positive electrode current collector is inserted from the opening of the can and combined with the can. And bending the opening part of the tank body by using a sealing machine die to finish the sealing of the battery.

The lithium ion battery has the advantages that the assembly technology is mature, and the operation is easy. However, as can be seen from the structure of fig. 1, the positive electrode current collector occupies a large space, and thus the entire battery has a small space, resulting in a small battery capacity.

In addition, when the lithium ion battery is excessively charged and discharged, a large amount of gas may be generated inside the battery. When the gas reaches a certain pressure, the gas can burst the positive seal or the negative tank body, and an explosion phenomenon is generated. Generally, the lithium ion battery with a large volume is provided with an explosion-proof device on the positive current collector, but the small lithium ion battery cannot be provided with the explosion-proof device because the positive current collector is too small. Therefore, the small lithium ion battery is likely to explode during the charging and discharging process, and thus has potential safety hazards.

Therefore, there is a need in the art for a rechargeable battery and a method of manufacturing the same that can efficiently utilize space, maximize the use of battery capacity, and avoid explosion during charging and discharging.

Disclosure of Invention

An object of the present invention is to provide a small-sized rechargeable battery capable of maximizing the use of battery capacity by effectively utilizing space, and a method for manufacturing the same. Additionally, it is a further object of the present invention to provide a small-sized rechargeable battery and a method of manufacturing the same, which can effectively utilize space, maximize the use of battery capacity, and prevent explosion during charge and discharge.

According to an aspect of the present invention, there is provided a rechargeable battery including: the negative electrode tank body is provided with a three-stage step structure at the opening part and comprises a first stage step, a second stage step and a third stage step with gradually reduced inner diameters from the tail end; the positive current collector is nested in the negative electrode tank body; the sealing ring is arranged between the opening part of the negative electrode tank body and the opening part of the positive current collector and isolates the negative electrode tank body from the positive current collector so as not to contact with the positive current collector and generate short circuit; wherein the seal ring is tightly attached to the second step of the negative can to form a seal part of the battery; the end part of the first step is bent inwards to be attached to the sealing ring to form a sealing position; and the lower portion of the seal ring abuts against the connection between the second step and the third step, thereby obtaining support.

Preferably, the negative electrode can has at least one hole on a side wall of the first step.

Preferably, the seal ring has a U-shaped groove in which the mouth of the positive electrode current collector is received. Preferably, the material of the sealing ring is an insulating compressible material.

Preferably, the positive electrode current collector has an inverted cup-shaped structure, and a diameter of a mouth of the cup-shaped structure is equal to or greater than a diameter of a bottom of the cup-shaped structure.

Preferably, the battery further comprises a cell coil formed by winding the positive plate, the negative plate and the separation mechanism between the positive plate and the negative plate.

Preferably, a positive electrode tab extends from the tail end of the positive electrode plate and is connected with the positive electrode current collector; and a negative tab extends from the end of the negative plate and is connected with the negative can.

Preferably, the battery further comprises an upper insulation sheet arranged above the battery cell coil and a lower insulation sheet arranged below the battery cell coil.

Preferably, when the positive electrode current collector moves upward, a positive electrode tab connected with the positive electrode current collector is broken.

Preferably, the battery is a cylindrical battery, for example a cylindrical battery.

Preferably, the battery is a lithium ion battery, more preferably a cylindrical lithium ion battery.

According to another aspect of the present invention, there is provided a method of manufacturing the rechargeable battery according to the present invention.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a cross-sectional view of a small rechargeable lithium-ion battery made in accordance with the prior art; and

fig. 2 is a cross-sectional view of a rechargeable lithium-ion battery according to one embodiment of the present invention.

Detailed Description

The following description is of exemplary embodiments of the invention and is not intended to limit the scope or applicability of the invention in any way. Rather, the following description is intended to provide examples for implementing various embodiments of the invention.

Hereinafter, the concept and concept of the present invention will be specifically described by taking a small pillar-shaped rechargeable lithium ion battery as an example. However, as will be appreciated by those skilled in the art, the rechargeable battery of the present invention is not limited to small lithium ion batteries, nor to pillar structures, and other battery structures (e.g., button structures) and materials commonly used in the art may be used.

The small lithium ion battery of the invention comprises a negative electrode tank body, and the inside of the negative electrode tank body is configured to accommodate positive and negative pole piece wrappings (namely, battery cell wrappings). The positive and negative pole pieces are wrapped and comprise positive pole pieces and negative pole pieces, and the positive pole pieces and the negative pole pieces are isolated by a diaphragm. The positive and negative pole pieces separated by the diaphragm are wound into a cylindrical roll, and then can be bound by adhesive paper. And a positive electrode tab extends from the tail end of the positive electrode piece and is connected with a positive electrode current collector. And a negative pole tab extends from the tail end of the negative pole piece and is connected with the can body. The positive and negative pole piece wrapping can also be provided with an upper insulating piece and a lower insulating piece.

As shown in fig. 2, in a preferred embodiment, the negative electrode can 1 of the present invention has three steps at the mouth portion thereof, and includes a first step 9, a second step 10, and a third step 11 having inner diameters decreasing in order from the end. For example, the second-stage step 10 may have an inner diameter about 0.05 to 0.20mm smaller than the first-stage step 9 and about 0.05 to 0.20mm smaller than the third-stage step 11. Preferably, the inner diameter of the second-stage step 10 may be about 3 to 18mm depending on the size of the battery. The junction between the second step 10 and the third step 11 may be used to support the bottom of the seal ring 8 when the battery is installed.

Since the second step 10 presses the sealing ring 8 inwards, a good seal between the negative can 1 and the positive fluid 7 is ensured, so that there may be a gap between the first step 9 and the sealing ring and no glue may need to be filled in the gap. Of course, to further enhance the sealing, the gap may also be filled with sealing glue.

In a further preferred embodiment, there may be at least one hole in the first step 9, which passes through the negative can 1. In one aspect, 2 to 6 holes, preferably 4 holes, may be provided in the first step 9. Preferably, the plurality of apertures are circumferentially symmetrical. In one aspect, the hole diameter may be 0.10 to 0.8 mm. The holes may be circular, rectangular, square, prismatic or irregular, preferably irregular.

The thickness of the negative electrode can body 1 can be about 0.10-0.30 mm, and the material can be iron nickel plating or stainless steel.

In one embodiment, the positive current collector 7 may be in the shape of an inverted cup, and the diameter of the cup mouth may be equal to or greater than the diameter of the cup bottom, preferably greater than the diameter of the cup bottom, for example, about 0.05 to 0.30mm, preferably about 0.10 to 0.15mm greater. The material of the positive electrode current collector may be iron nickel plating or stainless steel, and the thickness may be about 0.1 to 0.35 mm.

A sealing ring 8 can be arranged between the side wall of the positive current collector 7 and the opening of the negative electrode can body 1 to play a role of sealing the battery and prevent the negative electrode can body 1 from contacting with the positive electrode top cover 7 to cause short circuit. Preferably, the sealing ring 8 is a ring structure with a U-shaped groove. Preferably, the material of the sealing ring 8 is compressible.

More specifically, in one embodiment, the seal ring 8 may have a U-shaped groove, and the thickness may be about 0.05 to 0.30mm, and preferably about 0.08 to 0.20 mm. The mouth of the cup can be inserted into the U-shaped groove of the sealing ring 8. The inner surface of the sealing ring 8 can be tightly attached to the outer surface of the cup mouth part of the positive current collector 7. The outer diameter of the sealing ring 8 is preferably substantially the same as the inner diameter of the second step 10 of the negative electrode can 1, for example, the outer diameter of the sealing ring 8 is the same as or smaller than the second step 10 of the negative electrode can 1 by 0.01-0.03 mm, and the maximum diameter is not more than 0.10mm, otherwise the sealing performance of the battery will be affected. The sealing ring material can be polypropylene (PP) or Polyetheretherketone (PEEK), and can also be other elastic insulating materials which can be used.

Before the seal ring 8 is combined with the positive current collector 7, epoxy resin or other glue can be coated on the groove of the seal ring to enable the seal ring and the positive current collector to be tightly combined.

When the battery is assembled after the electrolyte is added, the positive current collector 7 is inserted from the opening of the negative can 1, and the seal ring 8 combined with the positive current collector 7 is brought into close contact with the second step of the negative can 1 by, for example, pressing from the top, thereby forming a main seal portion of the battery. The lower portion of the seal ring 8 abuts against the junction between the second step 10 and the third step 11, thereby being supported.

And then narrowing the first-stage step 9 by using a sealing machine mould, so that the tail end of the first-stage step 9 is bent inwards to be attached to the sealing ring 8 to form a sealing position. At this time, the second step 10 of the negative electrode can 1 is also stretched inward by a radial force to compress the seal ring 8, so that the seal ring 8 is more closely attached to the can wall, and the sealing performance is better. After such assembly, the sealing ring 8 is compressed to a thickness of between 10% and 90%, in particular between 30% and 70%, and particularly preferably about 50%, of the original thickness, thereby achieving a good sealing effect.

The lithium ion battery manufactured by the structure has the internal volume which can be increased by at least about 10-12% or even higher compared with the lithium ion battery with the traditional structure with the same volume, so that the capacity is greatly improved without increasing the size of the battery.

In addition, the lithium ion battery manufactured by the structure can improve the battery capacity and simultaneously ensure that the battery is safer and more reliable. When the battery is excessively charged and discharged, the gas generated in the battery pushes the positive current collector upwards, the positive current collector can be separated from the second-stage step of the negative electrode tank body, when the positive current collector reaches the first-stage step, the cup opening part can be clamped by the sealing position formed by the first-stage step, and the gas can be discharged from the gas hole of the first-stage step, so that the explosion danger of the battery due to the overlarge gas pressure is eliminated. Furthermore, the provision of a hole in the first step prevents the glue from blocking the hole due to the presence of the gap between the first step and the sealing ring 8 and normally no glue is added, and the presence of the gap also allows the internal gas pressure to be initially released.

In addition, in order to avoid excessive charge and discharge of the battery, the positive electrode tab connected to the positive electrode current collector or the negative electrode tab connected to the negative electrode can may be broken when the positive electrode current collector moves upward. For example, a tearing portion (e.g., a tearing line structure) may be disposed between the positive electrode current collector and the positive electrode tab, and the tearing portion is broken when the positive electrode current collector moves outward by a predetermined distance, so as to cut off the connection between the positive electrode tab and the positive electrode current collector, thereby preventing more gas from being generated to cause explosion of the battery.

The invention is described in more detail below with reference to fig. 2. Fig. 2 is a cross-sectional view of a rechargeable lithium-ion battery according to an exemplary embodiment of the present invention. As shown in fig. 2, the rechargeable lithium ion battery includes a negative housing, a positive cap, and an insulating sealing ring.

Example 1

The negative electrode shell is a cylindrical can body, namely a negative electrode can body 1. The material of the negative electrode can body 1 is stainless steel, the thickness of the negative electrode can body is 0.15mm, and the height of the negative electrode can body is 24 mm. The negative electrode can 1 as shown in fig. 2 can be produced by, for example, a press machine. The opening part of the negative electrode tank body 1 is provided with a three-stage ladder structure which comprises a first-stage ladder 9, a second-stage ladder 10 and a third-stage ladder 11 with the inner diameters decreasing in sequence. The second step 10 has an inner diameter 0.15mm smaller than the first step 9 and 0.20mm larger than the third step 11. The inner diameter of the second step 10 is 10mm and the inner wall is coated with sealing glue. The side wall of the opening of the negative electrode can 1 is also provided with at least one air hole 16. In this embodiment, the number of the air holes 16 is four and symmetrically arranged. The diameter of the air holes 16 is 0.5 mm.

And cutting the positive plate 13 and the negative plate 14 according to requirements, and respectively performing spot welding on the positive plate and the negative plate to the positive electrode tab 6 and the negative electrode tab 3. And a discharge diaphragm 15 is added between the positive plate and the negative plate. And (3) winding the positive and negative pole pieces into a columnar wrapping 2, and wrapping with adhesive paper. The height of the rolling package 2 is the total height of the battery minus the thicknesses of the positive and negative current collectors 7 and the two insulation sheets, and a space of about 0.5-1 mm is reserved.

The lower insulating sheet 4 is firstly placed at the inner bottom of the negative electrode can body 1, and then the rolling bag 2 is placed. And welding the negative pole tab 3 with the can body. An upper insulation sheet 5 is placed on the upper part of the winding bag 2, and a positive electrode tab 6 penetrates through the upper insulation sheet 5 and is welded with a positive electrode current collector 7.

The positive electrode current collector 7 had an inverted cup-shaped structure, the outer diameter of the cup mouth portion thereof was 0.15mm larger than the outer diameter of the cup bottom portion thereof, and the material thereof was stainless steel with a thickness of 0.15 m.

And a sealing ring 8 is sleeved at the cup mouth part of the positive current collector 7. The sealing ring 8 is in a ring shape with a U-shaped groove and is made of PP. Before being combined with the positive current collector 7, the groove is coated with sealing glue 12 to enable the positive current collector and the groove to be tightly combined. The thickness of the seal ring 8 is 0.15mm, and the outer diameter thereof is the same as or smaller than the inner diameter of the second step 10 of the negative electrode can 1 by 0.02 mm.

And (3) after spot welding of the positive current collector 7, baking the whole battery in an oven at 85 ℃ for 24-36 hours. After cooling, the electrolyte is added into the environment with the relative humidity below 1%. Then, the positive current collector 7 is inserted from the opening of the negative electrode tank 1, combined with the negative electrode tank 1, and pressurized from the upper part, so that the sealing ring 8 is tightly attached to the second step 10 of the negative electrode tank 1 and abuts against the connecting support between the second step and the third step 11 of the negative electrode tank 1. And then, the first-stage step 9 is narrowed inwards by using a sealing machine die, so that the opening part of the first-stage step 9 of the tank body is bent inwards to be attached to the sealing ring 8, and the sealing ring 8 is further extruded.

Example 2

And a sealing ring 8 is sleeved at the cup mouth part of the positive current collector 7. The sealing ring 8 is a ring with a U-shaped groove and is made of PEEK. Because the sealing ring is tubular before being combined with the positive current collector 7, the sealing ring is firstly sleeved at the opening of the positive current collector 7 and then is bent inwards by hot air to shrink, so that a U-shaped groove is formed and is tightly combined with the positive current collector 7. The thickness of the seal ring 8 is 0.08mm, and the outer diameter thereof is the same as or smaller than the inner diameter of the second step 10 of the negative electrode can 1 by 0.02 mm.

Comparative example (existing Structure)

Fig. 1 is a cross-sectional view of a small lithium ion battery manufactured by a conventional method.

The negative electrode can body of the battery is a columnar can body, the material of the can body is a stainless steel sheet with the diameter of 0.15mm, and the diameter and the height of the can body are respectively 10mm and 24 mm.

After the positive and negative pole pieces are cut as required, the ends are respectively spot-welded with a positive pole tab 106 and a negative pole tab 103. And (3) adding a diaphragm between the positive and negative plates, and rolling the positive and negative plates added with the diaphragm into the cell roll pack 102 through rolling. The lower insulating sheet 104 is placed at the bottom of the can (i.e., the negative terminal 1023), and the cell coil 102 is packed into the can. The negative electrode tab 103 is connected to the side wall of the can body by spot welding.

And rolling a circle of groove with the width of about 2mm and the depth of 1mm at a position about 3mm below the opening of the tank body, and then rolling the lower part of the upper insulation sheet 105 and the upper part of the cell wrapping bag 102. The positive pole lug penetrates through the upper insulation sheet 105 to be connected with the positive pole current collector 7 in a spot welding mode.

The positive electrode collector 7 includes an external contact piece 1020 and an internal contact piece 1022, and a sealing ring 108. The external contact piece is made of a nickel-plated iron sheet, the internal contact piece is made of an aluminum sheet, and the sealing ring is made of PP. A positive current collector including an external contact piece (positive terminal 1020 serving as a top cap), an internal contact piece (positive aluminum cap 1022), and a gasket 108 is put into the can body. The positive current collector is supported by the protrusion of the groove. The outer contact sheet material is a nickel-plated iron sheet, the inner contact sheet is an aluminum sheet, and the sealing ring material is PP (polypropylene) or other plastic materials. Then, the positive tab 106 wrapped with the positive adhesive tape 1021 passes through the upper insulation sheet 105 and is connected with the positive current collector in a spot welding manner.

Comparison of results

As can be seen from the comparison between the small lithium ion batteries (fig. 2) manufactured in examples 1 and 2 and the small lithium ion battery (fig. 1) manufactured in comparative example (conventional structure), the volumes of the two batteries are substantially the same, but the internal space of the battery in examples 1-2 is significantly larger than that of the comparative example, and is increased by about 10 to 12%. In other words, the internal space of the battery of the present invention is about 10-12% larger than that of the battery of the conventional structure under the same external volume. Correspondingly, under the condition that materials and a formula are not changed, the battery capacity can be improved by 10-12%.

In addition, the lithium ion battery manufactured by the structure can improve the battery capacity and simultaneously ensure that the battery is safer and more reliable. When the battery is excessively charged and discharged, the gas generated in the battery pushes the positive current collector upwards, the positive current collector can be separated from the second-stage step of the negative electrode tank body, when the positive current collector reaches the first-stage step, the cup opening part can be clamped by the sealing position formed by the first-stage step, and the gas can be discharged from the gas hole of the first-stage step, so that the explosion danger of the battery due to the overlarge gas pressure is eliminated.

While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications and substitutions may be made to the invention to adapt to a particular situation or requirement without departing from the scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A rechargeable battery, characterized in that the rechargeable battery comprises:

the negative electrode tank body is provided with a three-stage step structure at the opening part and comprises a first stage step, a second stage step and a third stage step with gradually reduced inner diameters from the tail end of the opening part;

the positive current collector is nested in the negative electrode tank body; and

the sealing ring is arranged between the opening part of the negative electrode tank body and the opening part of the positive current collector and isolates the negative electrode tank body from the positive current collector so as not to contact with the positive current collector and generate short circuit;

wherein the seal ring is tightly attached to the second step of the negative can to form a seal part of the battery;

the end part of the first step is bent inwards to be attached to the sealing ring to form a sealing position;

and the lower part of the sealing ring is abutted against the connecting part between the second-stage step and the third-stage step, so that the support is obtained;

wherein a gap is formed between the first step and the sealing ring.

2. The rechargeable battery according to claim 1, wherein the negative electrode can has at least one hole on a side wall of the first step.

3. The rechargeable battery according to claim 1 or 2, wherein the sealing ring has a U-shaped groove in which a mouth of the positive electrode current collector is received.

4. The rechargeable battery according to claim 1 or 2, wherein the material of the sealing ring is an insulating compressible material.

5. The rechargeable battery according to claim 1 or 2, wherein the positive electrode current collector has an inverted cup-shaped structure, and a diameter of a mouth of the cup-shaped structure is equal to or larger than a diameter of a bottom of the cup-shaped structure.

6. The rechargeable battery according to claim 1 or 2, further comprising a cell wrap wound with the positive plate, the negative plate and the separation mechanism therebetween.

7. The rechargeable battery according to claim 6, wherein a positive tab extends from a distal end of the positive tab and is connected to the positive current collector; and a negative tab extends from the end of the negative plate and is connected with the negative can.

8. The rechargeable battery of claim 7, further comprising an upper insulating sheet disposed above the cell wrap and a lower insulating sheet disposed below the cell wrap.

9. The rechargeable battery according to claim 7, wherein a positive electrode tab connected with the positive electrode current collector is broken when the positive electrode current collector moves upward.

10. The rechargeable battery according to claim 1, wherein the battery is a lithium ion battery.

11. The rechargeable battery according to claim 1, wherein the battery is a cylindrical battery.

12. A method of manufacturing a rechargeable battery according to any of claims 1-11.