阅读说明：本技术 一种圆柱形锂离子电池负极底焊的超声焊接设备及其工艺 (Ultrasonic welding equipment and process for bottom welding of cylindrical lithium ion battery cathode ) 是由 李文 李森林 于 2021-08-24 设计创作，主要内容包括：本发明涉及一种圆柱形锂离子电池负极底焊的超声焊接设备及其工艺,超声焊接工艺包括如下步骤：S1：将卷芯的负极耳朝下,装入电池钢壳；S2：将装填好卷芯的电池钢壳外侧安装所述电池托架；S3：将倒"L"型超声焊接上模头插入卷芯中间的中空部分；S4：控制电池钢壳以及装填好的卷芯,倒"L"型超声焊接上模头一起下行,与超声焊接机底座紧密接触；S5：使倒"L"型超声焊接上模头、负极耳、电池钢壳紧密接触；S6：开启超声焊接机主机；S7：焊接操作开始进行,电池钢壳局部熔化与负极耳成为一体；S8：升起倒"L"型超声焊接上模头,上模头与负极耳分离,完成负极耳与电池钢壳的焊接操作。解决了传统电阻焊炸火的难题,锂离子电池成品的一致性也得到了提高。(The invention relates to ultrasonic welding equipment and a process for welding the bottom of a cylindrical lithium ion battery cathode, wherein the ultrasonic welding process comprises the following steps: s1: the negative pole lug of the winding core faces downwards and is arranged in a battery steel shell; s2: installing the battery bracket on the outer side of the battery steel shell filled with the winding core; s3: inserting an inverted L-shaped ultrasonic welding upper die head into the hollow part in the middle of the winding core; s4: controlling the battery steel shell and the filled winding core, and enabling the battery steel shell and the filled winding core to descend together with the upper die head in the inverted L-shaped ultrasonic welding mode and to be in close contact with the base of the ultrasonic welding machine; s5: the upper die head, the negative electrode lug and the battery steel shell are in close contact by inverted L-shaped ultrasonic welding; s6: starting a main machine of the ultrasonic welding machine; s7: the welding operation is started, and the local melting of the steel shell of the battery and the negative pole lug are integrated; s8: and lifting the inverted L-shaped ultrasonic welding upper die head, and separating the upper die head from the negative electrode lug to complete the welding operation of the negative electrode lug and the battery steel shell. The problem of fire explosion of the traditional resistance welding is solved, and the consistency of the finished lithium ion battery is improved.)

1. The ultrasonic welding equipment for the bottom welding of the cathode of the cylindrical lithium ion battery is characterized by comprising an ultrasonic welding upper die head arranged above the cylindrical lithium ion battery structure, an ultrasonic welding machine host connected with the ultrasonic welding upper die head, an ultrasonic welding machine base arranged below the cylindrical lithium ion battery structure and a battery bracket arranged outside the cylindrical lithium ion battery structure.

2. The ultrasonic welding device for the bottom welding of the negative electrode of the cylindrical lithium ion battery as claimed in claim 1, wherein the cylindrical lithium ion battery structure comprises a battery steel shell and a winding core arranged in an inner cavity of the battery steel shell, and a negative electrode tab is mounted on one side of the bottom of the winding core.

3. The ultrasonic welding device for the bottom welding of the cylindrical lithium ion battery cathode is characterized in that the ultrasonic welding upper die head is an inverted L-shaped ultrasonic welding upper die head.

4. An ultrasonic welding process for bottom welding of a cylindrical lithium ion battery cathode is characterized by comprising the following steps of:

s1: the negative pole lug of the winding core faces downwards and is arranged in a battery steel shell;

s2: installing the battery bracket on the outer side of the battery steel shell filled with the winding core;

s3: inserting an inverted L-shaped ultrasonic welding upper die head into the hollow part in the middle of the winding core;

s4: controlling the battery steel shell and the filled winding core, and enabling the battery steel shell and the filled winding core to descend together with the upper die head in the inverted L-shaped ultrasonic welding mode and to be in close contact with the base of the ultrasonic welding machine;

s5: the upper die head, the negative electrode lug and the battery steel shell are in close contact by inverted L-shaped ultrasonic welding;

s6: starting a main machine of the ultrasonic welding machine;

s7: the welding operation is started, and the local melting of the steel shell of the battery and the negative pole lug are integrated;

s8: and lifting the ultrasonic welding upper die head, and separating the upper die head from the negative electrode lug to complete the welding operation of the negative electrode lug and the battery steel shell.

5. The ultrasonic welding process for the bottom welding of the negative electrode of the cylindrical lithium ion battery according to claim 4, wherein when the number of the negative electrode tabs is multiple, the negative electrode tabs are orderly stacked in sequence, so that the stack of the negative electrode tabs is ensured to be tightly combined with the steel shell of the battery.

6. The ultrasonic welding process for the bottom welding of the negative electrode of the cylindrical lithium ion battery as claimed in claim 4, wherein after the negative electrode tab is welded with the battery steel shell, the welding tensile strength is tested to detect the firmness of the welding of the negative electrode tab with the battery steel shell.

7. The ultrasonic welding process for the bottom welding of the negative electrode of the cylindrical lithium ion battery as claimed in claim 4, wherein the thickness of the negative electrode tab is smaller than that of the steel shell of the battery.

8. The ultrasonic welding process for the bottom welding of the negative electrode of the cylindrical lithium ion battery as claimed in claim 4, wherein the melting point of the negative electrode tab material is less than or equal to the melting point of the steel shell of the battery.

Technical Field

The invention relates to the technical field of lithium ion batteries, in particular to ultrasonic welding equipment and a process for welding the bottom of a cylindrical lithium ion battery cathode.

Background

The lithium ion battery has the advantages of high energy density, long service life, high charge-discharge multiplying power, good environment applicability and the like, and is widely applied to the fields of digital products, passenger vehicles, commercial vehicles, special power supplies and the like. The lithium ion battery can be divided into a cylindrical lithium ion battery, a square lithium ion battery and a special lithium ion battery according to the appearance. The cylindrical lithium ion battery has a very high automation level, a mature process and high safety, and thus the market occupancy of the cylindrical lithium ion battery is continuously increased. In the production and manufacturing process of the lithium ion battery, the process of assembling the segments is crucial to the quality and safety of the product. The welding process of the negative tab is a very critical production step for the charge and discharge performance and safety of the cylindrical lithium ion battery.

At present, the negative electrode lug of most cylindrical lithium ion battery production enterprises and the battery steel shell are welded by adopting a resistance welding process. For example, the invention patent with application number 202110165829.7, named as the welding process of the negative pole tab of the cylindrical lithium ion battery, comprises the following steps:

s1, preparing a cathode tab made of pure copper and a welding needle made of metal tungsten for a welding head;

and S2, butting the negative pole lug with a steel shell, and welding the joint of the negative pole lug and the steel shell through a welding head of the welding pin.

For another example, application No. 201410016749.5, entitled invention patent for a cylindrical lithium ion battery assembly process, includes the following steps: (1) ultrasonically rubbing the two ends of the winding core flat; (2) wrapping bottom adhesive tapes at two ends of the winding core; (3) putting the winding core into a shell; (4) welding the combination of the current collecting disc and the cover plate at the two ends of the winding core; (5) bending the pole ear of the current collecting plate; (6) bending the cover plate; (7) forming a tab; (8) embedding a cover plate; (9) cover-housing laser welding. The flow of the invention is standard and standard, and because the combination form of the current collecting disc and the cover plate is adopted, the combined cover plate is welded to the two ends of the winding core, so that the time for shaping the lug is saved; and welding the two ends of the roll core after the roll core is placed into the shell by adopting a welding mode of ultrasonic kneading and two-end laser welding.

In the above related art, the welding of the negative tab and the steel battery case is performed by a resistance welding process, and the following disadvantages are very obvious: (1) the metal impurity particles are remained due to fire explosion in the welding process, and the extreme safety problem of the lithium ion battery is easily caused when the metal impurity particles are serious; (2) more and more process requirements for performance require multiple negative electrode tabs, and the material is also converted from nickel which is well welded to nickel-copper composite or copper, so welding becomes difficult.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides ultrasonic welding equipment and process for bottom welding of a cylindrical lithium ion battery cathode.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a

The ultrasonic welding equipment for the bottom welding of the cathode of the cylindrical lithium ion battery comprises an inverted L-shaped ultrasonic welding machine upper die head arranged above the cylindrical lithium ion battery structure, an ultrasonic welding machine host connected with the inverted L-shaped ultrasonic welding machine upper die head, an ultrasonic welding machine base arranged below the cylindrical lithium ion battery structure, and a battery bracket arranged outside the cylindrical lithium ion battery structure.

Further, cylindrical lithium ion battery structure includes the battery steel casing, sets up the book core in the battery steel casing inner chamber, roll up core bottom one side and install the negative pole ear.

An ultrasonic welding process for bottom welding of a cylindrical lithium ion battery cathode comprises the following steps:

s1: the negative pole lug of the winding core faces downwards and is arranged in a battery steel shell;

s2: installing the battery bracket on the outer side of the battery steel shell filled with the winding core;

s3: inserting an inverted L-shaped ultrasonic welding upper die head into the hollow part in the middle of the winding core;

s4: controlling the battery steel shell and the filled winding core, and enabling the battery steel shell and the filled winding core to descend together with the upper die head in the inverted L-shaped ultrasonic welding mode and to be in close contact with the base of the ultrasonic welding machine;

s5: the upper die head, the negative electrode lug and the battery steel shell are in close contact by inverted L-shaped ultrasonic welding;

s6: starting a main machine of the ultrasonic welding machine;

s7: the welding operation is started, and the local melting of the steel shell of the battery and the negative pole lug are integrated;

s8: and lifting the inverted L-shaped ultrasonic welding upper die head, and separating the upper die head from the negative electrode lug to complete the welding operation of the negative electrode lug and the battery steel shell.

Further, when the number of the negative electrode lugs is multiple, the negative electrode lugs are orderly stacked in sequence, and the close combination of the negative electrode lug stacking layer and the battery steel shell is ensured.

Further, after the negative electrode tab is welded with the battery steel shell, the welding firmness of the negative electrode tab and the battery steel shell is detected by testing the welding tensile strength.

Further, the thickness of the negative electrode lug is smaller than that of the battery steel shell.

Further, the melting point of the negative electrode tab material is less than or equal to the melting point of the battery steel shell.

The invention has the beneficial effects that: the invention is different from the traditional resistance welding process, realizes the ultrasonic welding of the welding procedure of the negative electrode lug, thoroughly realizes the technical scheme of single or even multiple negative electrode lugs, and ensures that the internal resistance of the battery is lower, the damage of the battery is smaller, and the battery can be better used on new energy automobiles; the energy emitted by the ultrasonic transducer is stable, welding parameters do not need to be adjusted, and output energy is monitored, so that the welding consistency of products is improved, the problem of fire explosion of the traditional resistance welding is solved, the consistency of finished lithium ion batteries is greatly improved, defective products are hardly produced in the operation process of the process, and the production and manufacturing cost is further reduced.

Drawings

FIG. 1 is a diagram illustrating the effect of the ultrasonic welding apparatus of the present invention;

FIG. 2 is a process flow diagram of the present invention.

Detailed Description

As shown in fig. 1, an ultrasonic welding device for bottom welding of a cathode of a cylindrical lithium ion battery comprises an inverted L-shaped ultrasonic welding machine upper die head 2 arranged above the cylindrical lithium ion battery structure, an ultrasonic welding machine host 1 connected with the inverted L-shaped ultrasonic welding machine upper die head 2, an ultrasonic welding machine base 7 arranged below the cylindrical lithium ion battery structure, and a battery bracket 5 arranged outside the cylindrical lithium ion battery structure.

The cylindrical lithium ion battery structure comprises a battery steel shell 4, a winding core 3 arranged in the inner cavity of the battery steel shell 4, and a negative electrode lug 6 arranged on one side of the bottom of the winding core 3.

As shown in fig. 2, an ultrasonic welding process for welding the cathode bottom of a cylindrical lithium ion battery comprises the following steps:

s1: the negative electrode tab 6 of the winding core faces downwards and is arranged in the battery steel shell 4;

s2: inserting the inverted L-shaped ultrasonic welding upper die head 2 into the hollow part in the middle of the winding core 3;

s3: installing a battery bracket 5 on the outer side of the battery steel shell 4 filled with the winding core 3;

s4: controlling the battery steel shell 4 and the filled winding core 3 to move downwards together with the inverted L-shaped ultrasonic welding upper die head 2 and to be in close contact with a base 7 of an ultrasonic welding machine;

s5: the upper die head 2 is welded with the negative electrode lug 6 and the battery steel shell 4 in an inverted L-shaped ultrasonic mode to be in close contact with each other;

s6: starting an ultrasonic welding machine host 1;

s7: the welding operation is started, and the battery steel shell 4 is partially melted and integrated with the negative electrode lug 6;

s8: and lifting the inverted L-shaped ultrasonic welding upper die head 2, and separating the inverted L-shaped ultrasonic welding upper die head from the negative electrode tab 6 to complete the welding operation of the negative electrode tab 6 and the battery steel shell 4.

Further, when a plurality of negative electrode tabs 6 are arranged, the negative electrode tabs 6 are orderly stacked in sequence, so that the negative electrode tab stack is tightly combined with the battery steel shell 4. The ultrasonic welding upper die head 2 is preferably an inverted L-shaped ultrasonic welding upper die head, and after the negative electrode tab 6 is welded with the battery steel shell 4, the welding tensile strength is tested to detect the welding firmness of the negative electrode tab 6 and the battery steel shell 4.

Further, the principle of the ultrasonic welding of the present invention is: the ultrasonic energy acts on the surface to be processed, the workpiece is melted by controlling the parameters of the ultrasonic wave to form a specific melt, in the invention, the upper die head 2 is welded by the inverted L-shaped ultrasonic welding to enable the negative pole lug 6 to be tightly combined with the battery steel shell 4, the purpose is to better conduct energy conduction, as the material thickness of the negative pole lug 6 is smaller than that of the battery steel shell 4, and the melting point of the negative pole lug material is generally close to or smaller than that of the battery steel shell, when the ultrasonic radiation acts on the contact surface of the negative pole lug 6 and the battery steel shell 4, the surface layer of the negative pole lug 6 tightly attached to the battery steel shell 4 and the surface layer of the battery steel shell 4 are melted through the violent oscillation of sound waves, the negative pole lug 6 and the battery steel shell 4 are melted into a whole, and are welded together perfectly, namely the ultrasonic welding of the negative pole lug 6 and the battery steel shell 4 is completed.

In addition, the ultrasonic welding upper die head 2 is replaced by the resistance welding upper die head to serve as a comparative example, the negative electrode tab 6 and the battery steel shell 4 are welded by adopting a resistance welding process, and the specific comparative example is operated as follows:

the resistance welding process for the bottom welding of the cathode of the cylindrical lithium ion battery comprises the following steps of:

s1: the negative pole lug of the winding core faces downwards and is arranged in a battery steel shell;

s2: inserting a copper needle into the hollow part in the middle of the winding core;

s3: fixing the battery steel shell filled with the winding core on a battery bracket;

s4: the battery steel shell, the filled winding core and the copper needle fall together and are in close contact with the resistance welding base;

s5: dropping the resistance welding upper die head, pressing the copper needle, and enabling the upper die head to be in close contact with the copper needle, the copper needle to be in close contact with the negative electrode lug, and the negative electrode lug to be in close contact with the battery steel shell;

s6: starting a resistance welding machine;

s7: the welding operation is started, and the local melting of the steel shell of the battery and the negative pole lug are integrated;

s8: and raising the upper die head for resistance welding, separating the copper needle from the upper die head, extracting the copper needle, separating the copper needle from the negative electrode lug, completing the welding operation of the negative electrode lug and the battery steel shell, and testing the welding tensile strength by the welding firmness degree to characterize the data.

The welding tension values of the negative electrode lug and the bottom of the steel shell of the battery of the samples of the embodiment and the comparative example are as follows:

	sample 1	Sample 2	Sample 3	Sample No. 4	Sample No. 5	Sample No. 6	Sample 7	Sample 8
									Example (N)	35.6	36.1	35.7	35.9	36.0	35.8	35.9	35.8
COMPARATIVE EXAMPLE (N)	29.8	29.7	30.2	30.5	30.9	29.7	31.2	29.5

The above table shows that the effect of ultrasonic welding is better than that of resistance welding under the condition of adopting the same process.

In conclusion, the invention is different from the traditional resistance welding process, realizes the ultrasonic welding of the negative electrode tab welding procedure, thoroughly realizes the technical scheme of single or even multiple negative electrode tabs, and ensures that the internal resistance of the battery is lower, the damage of the battery is smaller, and the battery can be better used on new energy automobiles; the energy emitted by the ultrasonic transducer is stable, welding parameters do not need to be adjusted, and output energy is monitored, so that the welding consistency of products is improved, the problem of fire explosion of the traditional resistance welding is solved, the consistency of finished lithium ion batteries is greatly improved, defective products are hardly produced in the operation process of the process, and the production and manufacturing cost is further reduced.

It will be appreciated that although embodiments of the present invention have been described in detail, those skilled in the art will appreciate that various changes, modifications, substitutions and alterations can be made herein without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.