阅读说明：本技术 一种锂离子电池特殊集流体与外接电极焊接的方法 (Method for welding special current collector and external electrode of lithium ion battery ) 是由 王灵君 于 2021-07-12 设计创作，主要内容包括：本发明公开了一种锂离子电池特殊集流体与外接电极焊接的方法,涉及新能源电池领域,包括三个步骤：更换圆形焊头；调节超声波焊接的设备参数,即调节焊接压力、能量、振幅和时间；将特殊集流体放置在焊座上方,外接电极放置于特殊集流体上方,然后踩下超声波焊接开关,进行焊接,本发明使用圆形焊头有效解决了带有塑料夹层的高安全特殊集流体无法连接外接电极的问题,这一工艺难点的解决大大提升了特殊集流体电芯的生产优率,使用圆形焊头后生产优率从之前的10％提升至95％。使用导热凝胶一方面弥补了由于极片层数多导致的焊接不牢,另一方面保护了由于焊接引起的焊渣或毛刺掉入到电芯内部,大大降低了电芯内短路的风险。(The invention discloses a method for welding a special current collector and an external electrode of a lithium ion battery, which relates to the field of new energy batteries and comprises the following three steps: replacing the circular welding head; adjusting equipment parameters of ultrasonic welding, namely adjusting welding pressure, energy, amplitude and time; the invention uses the circular welding head to effectively solve the problem that the high-safety special current collector with the plastic interlayer cannot be connected with the external electrode, the solution of the process difficulty greatly improves the production yield of the special current collector cell, and the production yield is improved to 95 percent from the previous 10 percent after the circular welding head is used. The heat-conducting gel is used for compensating the infirm welding caused by the large number of layers of the pole pieces, and on the other hand, welding slag or burrs caused by welding are prevented from falling into the battery cell, so that the risk of short circuit in the battery cell is greatly reduced.)

1. A method for welding a special current collector of a lithium ion battery and an external electrode is characterized by comprising the following steps:

step one, replacing a circular welding head;

step two, adjusting the equipment parameters of ultrasonic welding, namely adjusting the welding pressure, energy, amplitude and time;

and step three, placing the special current collector above the welding seat, placing the external electrode above the special current collector, and then stepping on the ultrasonic welding switch to weld.

2. The method for welding the special current collector of the lithium ion battery and the external electrode as claimed in claim 1, wherein: when welding the interlayer current collectors with 1-30 layers, adjusting the parameters of ultrasonic welding equipment as follows: the welding pressure is 30-70 PSI, the energy is 70-150J, the amplitude is 15-45 mu m, and the time is 0.1-0.5 s.

3. The method for welding the special current collector of the lithium ion battery and the external electrode as claimed in claim 1, wherein: when welding 31-102 layers of interlayer current collectors, adjusting the parameters of the ultrasonic welding equipment as follows: welding pressure is 70-110 PSI, energy is 200-400J, amplitude is 30-60 mu m, time is 1-3 s, in the third step, a metal sheet ring which is the same as the metal material of the current collector is firstly sleeved on the special current collector, then the special current collector is directly placed above the welding seat, the external electrode is placed above the special current collector, then the ultrasonic welding switch is stepped down, and heat-conducting structural adhesive which is rapidly gelled is brushed on the welding surface and the welding end surface, so that the ultrasonic splashing welding process is completed.

4. The method for welding the special current collector of the lithium ion battery and the external electrode as claimed in claim 2 or 3, wherein: the circular welding head is of a customized size, and the welding tooth specification is 8mm x 12 mm.

Technical Field

The invention relates to the field of new energy batteries, in particular to a method for welding a special current collector of a lithium ion battery and an external electrode.

Background

The lithium ion battery as an environment-friendly battery has the advantages of high energy density, high working voltage, high safety performance, long service life and the like.

In order to improve the safety performance of the lithium ion battery in the preparation process of the lithium ion battery, special high-safety materials are often introduced, such as special interlayer current collector materials (aluminum foils or copper foils commonly used in the lithium battery industry), an insulating plastic interlayer is contained in a current collector, so that various short-circuit modes caused by failure can be effectively blocked, and the energy density of a battery cell can be obviously improved due to light weight of plastic.

In the production process of the battery core, one side of the current collector needs to be coated with an electrode material, the other side of the current collector needs to be left as an electrode of an external circuit, and an empty current collector area which is not coated with the electrode material needs to be led out of an exposed positive electrode tab and a negative electrode tab of the battery core through welding, but if a conventional welding head is used for the special interlayer current collector, the special interlayer current collector cannot be welded at all, and the special current collector material contains an insulated plastic interlayer component, so that the conventional ultrasonic welding method cannot connect an aluminum foil with the external electrode, and the phenomena of insufficient welding and external electrode fracture can occur in a large scale.

Disclosure of Invention

In order to solve the technical problems, the invention provides the following technical scheme:

a method for welding a special current collector of a lithium ion battery and an external electrode comprises the following steps:

step one, replacing a circular welding head;

step two, adjusting the equipment parameters of ultrasonic welding, namely adjusting the welding pressure, energy, amplitude and time;

and step three, placing the special current collector above the welding seat, placing the external electrode above the special current collector, and then stepping on the ultrasonic welding switch to weld.

When welding the interlayer current collectors with 1-30 layers, adjusting the parameters of ultrasonic welding equipment as follows: the welding pressure is 30-70 PSI, the energy is 70-150J, the amplitude is 15-45 mu m, and the time is 0.1-0.5 s.

When welding 31-102 layers of interlayer current collectors, adjusting the parameters of the ultrasonic welding equipment as follows: welding pressure is 70-110 PSI, energy is 200-400J, amplitude is 30-60 mu m, time is 1-3 s, in the third step, a metal sheet ring which is the same as the metal material of the current collector is firstly sleeved on the special current collector, then the special current collector is directly placed above the welding seat, the external electrode is placed above the special current collector, then the ultrasonic welding switch is stepped down, and heat-conducting structural adhesive which is rapidly gelled is brushed on the welding surface and the welding end surface, so that the ultrasonic splashing welding process is completed.

The circular welding head is of a customized size, and the welding tooth specification is 8mm x 12 mm.

The invention has the beneficial effects that: the problem that a high-safety special current collector (aluminum foil or copper foil commonly used in lithium battery) with a plastic interlayer cannot be connected with an external electrode is effectively solved by using the circular welding head, the production yield of the special current collector battery cell is greatly improved by solving the process difficulty, and the production yield is improved to 95% from the previous 10% after the circular welding head is used. The heat-conducting gel is used for compensating the infirm welding caused by the large number of layers of the pole pieces, and on the other hand, welding slag or burrs caused by welding are prevented from falling into the battery cell, so that the risk of short circuit in the battery cell is greatly reduced.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.

A method for welding a special current collector of a lithium ion battery and an external electrode comprises the following steps:

step one, replacing a circular welding head;

step two, adjusting the equipment parameters of ultrasonic welding, namely adjusting the welding pressure, energy, amplitude and time;

and step three, placing the special current collector above the welding seat, placing the external electrode above the special current collector, and then stepping on the ultrasonic welding switch to weld.

When welding 31-102 layers of interlayer current collectors, adjusting the parameters of the ultrasonic welding equipment as follows: welding pressure is 70-110 PSI, energy is 200-400J, amplitude is 30-60 mu m, time is 1-3 s, in the third step, a metal sheet ring which is the same as the metal material of the current collector is firstly sleeved on the special current collector, then the special current collector is directly placed above the welding seat, the external electrode is placed above the special current collector, then the ultrasonic welding switch is stepped down, heat-conducting structural adhesive which is rapidly gelled is brushed on the welding surface and the welding end surface, one-step forming is carried out, operation time is not more than 0.5s, and the ultrasonic splashing welding process is completed.

When welding the interlayer current collectors with 1-30 layers, adjusting the parameters of ultrasonic welding equipment as follows: the welding pressure is 30-70 PSI, the energy is 70-150J, the amplitude is 15-45 mu m, and the time is 0.1-0.5 s.

The circular welding head is in a customized size, the welding tooth specification is 8mm by 12mm, and the welding area and the whole structure of the welding head need to be matched with the existing ultrasonic welding. The structure size can refer to the size of the existing ultrasonic welding head and welding seat.

The following is illustrated by four sets of comparative examples and examples, and the specific results are detailed in table 1 (mean tensile force at weld comparison table):

one, a, comparative example 1 (common 8 μm copper current collector + common bonding tool +15 layers):

1. preparing materials: preparing a common copper current collector with the diameter of 8 mu m;

2. winding: manually winding a common copper current collector with the thickness of 8 mu m, and controlling the number of layers to be 15;

3. hot pressing: carrying out simple hot pressing on the wound current collector by using a hot press, wherein the hot pressing parameter is 0.8Mpa, the temperature is 80 ℃, the time is 10s, and the current collector is tightly attached after the hot pressing;

4. ultrasonic welding: the welding is carried out by ultrasonic welding equipment, a common tip welding head is used, and a common 8-micron copper current collector can be connected with a 0.1mm Ni external electrode by adjusting welding parameters. The weld appearance was good, 3 samples were tested in parallel, and the mean tensile force was 74N.

b. Example 1 (special interlayer 8 μm copper current collector + round horn +15 layers):

1. preparing materials: preparing a copper current collector with a special interlayer of 8 mu m;

2. winding: manually winding a special copper current collector with an interlayer of 8 microns, wherein the number of layers is controlled to be 15;

3. hot pressing: carrying out simple hot pressing on the wound current collector by using a hot press, wherein the hot pressing parameter is 0.8Mpa, the temperature is 80 ℃, the time is 10s, and the current collector is tightly attached after the hot pressing;

4. ultrasonic welding: welding is carried out by ultrasonic welding equipment, a special circular welding head is used, and a special interlayer 8-micron copper current collector can be connected with a 0.1mm Ni external electrode by adjusting welding parameters, wherein the welding parameters are as follows: welding pressure 50PSI, energy 120J, amplitude 30 μm, time 0.2 s. The welding appearance is good, and the tensile test is done to the sample spare after will welding, 3 samples of parallel test, and the pulling force mean value is 67N.

Second, a, comparative example 2 (ordinary 12 μm aluminum current collector + ordinary horn +15 layers):

1. preparing materials: preparing a common 12-micron aluminum current collector;

2. winding: manually winding a common 12-micron aluminum current collector, wherein the number of layers is controlled to be 15;

3. hot pressing: carrying out simple hot pressing on the wound current collector by using a hot press, wherein the hot pressing parameter is 0.8Mpa, the temperature is 80 ℃, the time is 10s, and the current collector is tightly attached after the hot pressing;

4. ultrasonic welding: the welding is carried out by ultrasonic welding equipment, a common tip welding head is used, and a common 12-micron aluminum current collector can be connected with a 0.1mm Al external electrode by adjusting welding parameters.

The weld appearance was good, 3 samples were tested in parallel, and the mean tensile force was 61N.

b. Example 2 (special interlayer 10 μm aluminum current collector + round horn +15 layers):

1. preparing materials: preparing a special aluminum current collector with an interlayer of 10 mu m;

2. winding: manually winding a special aluminum current collector with an interlayer of 10 mu m, wherein the number of layers is controlled to be 15;

3. hot pressing: carrying out simple hot pressing on the wound current collector by using a hot press, wherein the hot pressing parameter is 0.8Mpa, the temperature is 80 ℃, the time is 10s, and the current collector is tightly attached after the hot pressing;

4. ultrasonic welding: welding is carried out by ultrasonic welding equipment, a special round welding head is used, and a special interlayer 10 mu m aluminum current collector can be connected with a 0.1mm Al external electrode by adjusting welding parameters, wherein the welding parameters are as follows: welding pressure 45PSI, energy 80J, amplitude 30 μm, time 0.1 s. The welding appearance is good, and the tensile test is carried out on the welded sample piece, 3 samples are tested in parallel, and the mean tensile force is 65N.

Thirdly, a, comparative example 3 (special interlayer 8 μm copper current collector + common welding head +15 layers):

1. preparing materials: preparing a copper current collector with a special interlayer of 8 mu m;

2. winding: manually winding a special copper current collector with an interlayer of 8 microns, wherein the number of layers is controlled to be 15;

3. hot pressing: carrying out simple hot pressing on the wound current collector by using a hot press, wherein the hot pressing parameter is 0.8Mpa, the temperature is 80 ℃, the time is 10s, and the current collector is tightly attached after the hot pressing;

4. ultrasonic welding: the welding is carried out by ultrasonic welding equipment, a common pointed welding head is used, and the special copper current collector with the interlayer of 8 microns cannot be connected with the 0.1mm Ni external electrode by adjusting welding parameters.

b. Example 3 (special interlayer 8 μm copper current collector + round horn +50 layers):

1. preparing materials: preparing a copper current collector with a special interlayer of 8 mu m;

2. winding: manually winding a special copper current collector with an interlayer of 8 microns, wherein the number of layers is controlled to be 50;

3. hot pressing: carrying out simple hot pressing on the wound current collector by using a hot press, wherein the hot pressing parameter is 0.8Mpa, the temperature is 80 ℃, the time is 10s, and the current collector is tightly attached after the hot pressing;

4. ultrasonic welding: welding is carried out by ultrasonic welding equipment, a special circular welding head is used, and a special interlayer 8-micron copper current collector with more than 30 layers (50 layers) can be connected with a 0.1mm Ni external electrode by adjusting welding parameters, wherein the welding parameters are as follows: welding pressure 90PSI, energy 350J, amplitude 40 μm, time 1 s. The welding appearance is good, and the tensile test is carried out to the sample after welding, 3 samples of parallel test, and the tensile mean value is 59N.

Fourth, a, comparative example 4 (special interlayer 10 μm aluminum current collector + common bonding tool +15 layers):

1. preparing materials: preparing a special aluminum current collector with an interlayer of 10 mu m;

2. winding a special aluminum current collector with an interlayer of 10 mu m by manual winding, wherein the number of layers is controlled to be 15;

3. hot pressing: carrying out simple hot pressing on the wound current collector by using a hot press, wherein the hot pressing parameter is 0.8Mpa, the temperature is 80 ℃, the time is 10s, and the current collector is tightly attached after the hot pressing;

4. ultrasonic welding: the aluminum current collector with the special interlayer of 10 microns cannot be connected with the 0.1mm Al external electrode by using an ordinary pointed welding head and adjusting welding parameters.

b. Example 4 (special interlayer 10 μm aluminum current collector + round horn +50 layers):

1. preparing materials: preparing a special aluminum current collector with an interlayer of 10 mu m;

2. winding: manually winding a special aluminum current collector with an interlayer of 10 mu m, wherein the number of layers is controlled to be 50;

3. hot pressing: carrying out simple hot pressing on the wound current collector by using a hot press, wherein the hot pressing parameter is 0.8Mpa, the temperature is 80 ℃, the time is 10s, and the current collector is tightly attached after the hot pressing;

4. ultrasonic welding: welding by ultrasonic welding equipment, using a special circular welding head, and adjusting welding parameters, the 10-micron aluminum current collector with the special interlayer of more than 30 layers (50 layers) can be connected with the 0.1mm Al external electrode, wherein the welding parameters are as follows: welding pressure 85PSI, energy 250J, amplitude 30 mu m, welding appearance is good within 2s, a welded sample is subjected to tension test, 3 samples are tested in parallel, and the mean tension is 55N.

TABLE 1 comparison table of mean values of tension at welding position

Comparative example	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4
					Mean value of tensile force	74	61	/	/
Examples of the invention	Example 1	Example 2	Example 3	Example 4
					Mean value of tensile force	67	63	59	55

Through the four groups of comparative examples and the embodiment, the problem that a high-safety special current collector (aluminum foil or copper foil commonly used in lithium battery) with a plastic interlayer cannot be connected with an external electrode is effectively solved by using the circular welding head, the production goodness of the special current collector battery cell is greatly improved by solving the process difficulty, and the production goodness is improved after the circular welding head is used.

It will be appreciated by those skilled in the art that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed above are therefore to be considered in all respects as illustrative and not restrictive. All changes which come within the scope of or equivalence to the invention are intended to be embraced therein.