CN113922003A - Ultrasonic welding effect evaluation method and lithium ion battery - Google Patents
Ultrasonic welding effect evaluation method and lithium ion battery Download PDFInfo
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- CN113922003A CN113922003A CN202111154023.4A CN202111154023A CN113922003A CN 113922003 A CN113922003 A CN 113922003A CN 202111154023 A CN202111154023 A CN 202111154023A CN 113922003 A CN113922003 A CN 113922003A
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- 238000003466 welding Methods 0.000 title claims abstract description 311
- 230000000694 effects Effects 0.000 title claims abstract description 82
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 27
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 27
- 238000011156 evaluation Methods 0.000 title claims abstract description 20
- 239000011888 foil Substances 0.000 claims abstract description 52
- 238000000034 method Methods 0.000 claims abstract description 42
- 238000013461 design Methods 0.000 claims abstract description 16
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 8
- 239000011889 copper foil Substances 0.000 claims description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 7
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- 238000005498 polishing Methods 0.000 claims description 4
- 239000011347 resin Substances 0.000 claims description 4
- 229920005989 resin Polymers 0.000 claims description 4
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 3
- 229910052737 gold Inorganic materials 0.000 claims description 3
- 239000010931 gold Substances 0.000 claims description 3
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 230000000007 visual effect Effects 0.000 description 12
- 238000010998 test method Methods 0.000 description 9
- 241001016380 Reseda luteola Species 0.000 description 6
- 239000012071 phase Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 3
- 238000009864 tensile test Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 239000005030 aluminium foil Substances 0.000 description 1
- 238000012854 evaluation process Methods 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/50—Current conducting connections for cells or batteries
- H01M50/531—Electrode connections inside a battery casing
- H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- General Physics & Mathematics (AREA)
- Biochemistry (AREA)
- Immunology (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Pathology (AREA)
- General Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
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- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Pressure Welding/Diffusion-Bonding (AREA)
- Connection Of Batteries Or Terminals (AREA)
Abstract
The invention discloses an ultrasonic welding effect evaluation method and a lithium ion battery, and belongs to the technical field of lithium ion batteries. The method for evaluating the ultrasonic welding effect comprises the following steps: s1: cutting a welding sample through metallographic phase; s2: observing the welding area of the foil and the tab of the welding sample, and measuring the effective connection length L of the section of the welding areaiIn mm; s3: effective connection length L according to the cross section of the welding zoneiObtaining effective over-current coefficient
And according to the obtained effective overcurrent coefficient
And judging the overcurrent capacity of the welding sample to evaluate the ultrasonic welding effect of the welding sample. The invention has the beneficial effects that: the method is used for evaluating the ultrasonic welding effect and guiding the over-current design of the pole lug.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to an ultrasonic welding effect evaluation method and a lithium ion battery.
Background
Ultrasonic welding, as a solid-phase connection technique, has been widely used in connection between foils and tabs of lithium ion batteries to allow flow guidance between the foils and the tabs, thereby allowing the lithium ion batteries to be charged and discharged. When the overcurrent capacity of a welding area formed by welding the foil and the tabs is insufficient, the temperature of the tabs is high, the safety risk of the lithium ion battery is greatly increased, and the reliability of the lithium ion battery is low; the overcurrent capacity between the foil and the pole lug is closely related to the welding effect between the foil and the pole lug. Therefore, it is necessary to evaluate and judge the welding effect of the welding region formed by welding between the foil and the tab.
At present, the evaluation mode of the welding effect of a welding area formed by welding a foil and a tab is mainly a visual method and a tension test method; wherein, the visual method is to directly observe the welding condition between the foil and the tab to evaluate the welding effect; the tensile test method is used for testing the welding tensile force between the foil and the tab so as to evaluate the welding effect.
Because the subjectivity of the visual method is large, a tension test method cannot establish a uniform measurement standard between welding tension and welding effect; and the visual method and the tension test method do not give consideration to the overcurrent design of the lug of the product for evaluating the welding effect between the foil and the lug, so that the visual method and the tension test method have limitations on the evaluation of the welding effect between the foil and the lug.
In view of the above, a method for evaluating the ultrasonic welding effect and a lithium ion battery are needed to solve the above problems.
Disclosure of Invention
The invention aims to provide an evaluation method of ultrasonic welding effect, which is used for evaluating the ultrasonic welding effect and guiding the over-current design of a tab.
In order to achieve the purpose, the invention adopts the following technical scheme:
an ultrasonic welding effect evaluation method is used for evaluating the welding effect of a welding sample, the welding sample is obtained by ultrasonically welding a foil and a tab, and the ultrasonic welding effect evaluation method comprises the following steps:
s1: cutting the welding sample in a metallographic mode;
s2: observing the welding area of the foil and the electrode lug in the welding sample, and measuring the effective connection length L of the section of the welding areaiIn mm;
s3: according to the effective connection length L of the section of the welding areaiObtaining effective overcurrent coefficient, and obtaining the effective overcurrent coefficient
And judging the overcurrent capacity of the welding sample so as to evaluate the ultrasonic welding effect of the welding sample.
Further, in the step S3, the effective overcurrent coefficient
The acquisition is calculated according to the following formula:
wherein n is the number of welding teeth of the welding head, L0The total length of the welding teeth of the welding head is in mm.
Further, the method for evaluating the ultrasonic welding effect further comprises the following steps:
s4: obtaining a current carrying capacity I of the welding areaxIn the unit of
S5: according to the overcurrent capacity of the welding area
Calculating a specific over-current capacity value I of the welding area; wherein s is the area of the welding head in mm2And I is an overcurrent value and has a unit of A.
Further, the step S4 includes the following steps:
s41: determining an upper limit value T of a target temperature of the welding sample0In units of;
s42: the welding samples are led with currents I with different values0In units of A, and recording the respective currents I0The temperature value T of the corresponding welding areax；
S43: compare each TxAnd T0Taking and T0And TxT having the smallest difference therebetweenxCorresponding to I0And through
Calculating to obtain the current-carrying capacity I of the welding areax(ii) a Wherein s isAIs the welding area of the welding area, and the unit is mm2。
Further, in the step S2, the cross-sectional effective connection length L of the welding sampleiThe length value of the part without interface gap formed by the fusion of the foil and the pole lug at the atomic level in the welding area is indicated.
Further, when the effective overcurrent coefficient
The flow capacity of the weld area of the weld sample did not reach the target flow capacity.
Further, the foil comprises a copper foil, and the effective overcurrent coefficient
And then, the copper foil and the lug are welded through ultrasonic to form the welding area of the welding sample, and the overcurrent capacity of the welding area of the welding sample reaches the target overcurrent capacity.
Further, the air conditioner is provided with a fan,the foil material also comprises an aluminum foil, and the effective overcurrent coefficient
And when the aluminum foil and the lug are welded through ultrasonic welding, the overcurrent capacity of the welding area of the welding sample reaches the target overcurrent capacity.
Further, the number n of the welding teeth of the welding head, and the total length L of the welding teeth of the welding head0And the welding area s of the welding head can be obtained through the design specification of the welding head.
Further, before the step S1, the method further includes:
s01: carrying out resin curing on the welding sample so as to facilitate metallographic cutting; and further comprising, between the step S1 and the step S2:
s02: grinding, polishing and corroding the welding sample subjected to the gold phase cutting in the step S1 to enable a cutting surface interface formed by cutting the welding sample to be clear, so that the effective connection length L of the section can be observed and measured convenientlyi。
Another object of the present invention is to provide a lithium ion battery with high safety and reliability.
In order to achieve the purpose, the invention adopts the following technical scheme:
a lithium ion battery comprises a foil and a tab, and the ultrasonic welding effect between the foil and the tab is evaluated by the ultrasonic welding effect evaluation method.
The invention has the beneficial effects that:
cutting a welding sample through a metallographic phase, observing a welding area of a foil material and a lug in the welding sample, and measuring the effective connection length L of the section of the welding areai(ii) a Then according to the effective connection length L of the section of the welding areaiObtaining effective over-current coefficient
According to the obtained effective overcurrent coefficient of the welding area
Judging the overcurrent capacity of the welding sample, and evaluating the ultrasonic welding effect of the welding sample according to the quality of the overcurrent capacity; when effective over-current coefficient
When the value of (2) meets the required value, the overcurrent capacity of the welding area is better, and the ultrasonic welding effect can be evaluated to be better; when effective over-current coefficient
When the value of (3) does not meet the required value, the overcurrent capacity of the welding area is poor, and the ultrasonic welding effect can be evaluated to be poor; thereby realizing the effective connection length L according to the section of the welding areaiObtaining effective overcurrent coefficient of welding area
And can be based on the effective overcurrent coefficient of the welding area
The ultrasonic welding effect is evaluated, and the problem that the evaluation of the welding effect of a welding sample by adopting a visual method and a tension test method has limitation is solved.
The lithium ion battery adopts the ultrasonic welding effect evaluation method to evaluate the welding effect, and can provide guidance for the lug overcurrent design, so that the situation that the temperature of the lug is higher due to the fact that the lug continues to work when the overcurrent capacity of a welding area is insufficient can be avoided, the safety risk of the lithium ion battery is reduced, the use reliability of the lithium ion battery is improved, the risk possibly generated by the lithium ion battery can be identified and prevented in advance, and the safety and the use reliability of the lithium ion battery are higher.
Drawings
FIG. 1 is a schematic structural view of a weld sample provided by the present invention;
FIG. 2 is a first schematic flow chart of the method for evaluating the ultrasonic welding effect provided by the present invention;
FIG. 3 shows the current carrying capacity I for obtaining the bonding area provided by the present inventionxA schematic flow diagram of (a);
fig. 4 is a schematic flow chart diagram of the method for evaluating the ultrasonic welding effect according to the present invention.
In the figure:
1-a tab; 2-a foil material; and 3-welding teeth.
Detailed Description
All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.
Any feature disclosed in this specification may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features. Like reference numerals refer to like elements throughout the specification.
In order to make the technical problems solved, the technical solutions adopted and the technical effects achieved by the present invention clearer, the technical solutions of the present invention are further described below by way of specific embodiments with reference to the accompanying drawings.
At present, the evaluation mode of the welding effect of a welding area formed by welding between a foil and a tab is mainly a visual method and a tensile test method. Wherein, the visual method is to directly observe the welding condition between the foil and the tab to evaluate the welding effect; the tension test method is used for testing the welding tension between the foil and the tab so as to evaluate the welding effect; however, the visual method has a large subjectivity, and a tension test method cannot establish a uniform measurement standard between welding tension and welding effect; and the visual method and the tension test method do not give consideration to the overcurrent design of the lug of the product for evaluating the welding effect between the foil and the lug, so that the visual method and the tension test method have limitations on the evaluation of the welding effect between the foil and the lug.
In contrast, the present embodiment proposes a method for evaluating an ultrasonic welding effect and a lithium ion battery. As shown in fig. 1, the method for evaluating the ultrasonic welding effect is used for evaluating the ultrasonic welding effect of a welding sample, and the welding sample is obtained by ultrasonically welding a foil 2 and a tab 1. The lithium ion battery comprises a foil 2 and a tab 1, wherein the ultrasonic welding design adopted between the foil 2 and the tab 1 is the welding design adopted by a welding sample with a better welding effect evaluated by the ultrasonic welding effect evaluation method, so that guidance is provided for the over-current design and the welding reliability of the lithium ion battery.
Specifically, as shown in fig. 1 and 2, the method for evaluating the ultrasonic welding effect includes the steps of: s1: cutting a welding sample through metallographic phase to obtain a metallographic section of a welding area; s2: observing the cutting surface so as to observe the welding area of the foil 2 and the tab 1 in the welding sample and measuring the effective connection length L of the section of the welding areaiIn mm; s3: effective connection length L according to the cross section of the welding zoneiObtaining effective over-current coefficient
And according to the obtained effective overcurrent coefficient
And judging the overcurrent capacity of the welding sample so as to evaluate the ultrasonic welding effect of the welding sample according to the quality of the overcurrent capacity.
Compared with the prior art, the evaluation method of the ultrasonic welding effect in the embodiment is based on the effective overcurrent coefficient of the welding area
Evaluating the ultrasonic welding effect of the welding sample; firstly, a welded sample is cut through metallographic phase, the welding area of a foil 2 and a tab 1 in the welded sample is observed, and the effective connection length L of the section of the welding area is measuredi(ii) a Then according to the effective connection length L of the section of the welding areaiObtaining effective over-current coefficient
According to the obtained effective overcurrent coefficient
Judging the overcurrent capacity of the welding sample, and evaluating the ultrasonic welding effect of the welding sample according to the quality of the overcurrent capacity; when effective over-current coefficient
When the value of (2) meets the required value, the overcurrent capacity of the welding area is better, and the ultrasonic welding effect can be evaluated to be better; when effective over-current coefficient
When the value of (3) does not meet the required value, the overcurrent capacity of the welding area is poor, and the ultrasonic welding effect can be evaluated to be poor; thereby realizing the effective connection length L according to the section of the welding areaiThe effective overcurrent coefficient of the welding area is obtained, the ultrasonic welding effect can be evaluated according to the effective overcurrent coefficient of the welding area, and the problem that the welding effect evaluation of a welding sample is limited by adopting a visual method and a tensile test method is solved.
And the lithium ion battery adopts the ultrasonic welding effect evaluation method to evaluate the welding effect so as to provide guidance for the over-current design of the tab, so that the problem that the temperature of the tab 1 is higher due to the fact that the tab continues to work when the over-current capacity of a welding area is insufficient can be avoided, the safety risk of the lithium ion battery is reduced, the use reliability of the lithium ion battery is improved, the risk possibly generated by the lithium ion battery can be identified and prevented in advance, the safety and the use reliability of the lithium ion battery are higher, and the over-current design of the tab can be guided.
Further, the effective overcurrent coefficient of the welding area
Is calculated according to the following formula
Wherein n is the number of 3 welding teeth of the welding head, L0The total length of the tooth 3 of the welding head is in mm.
Specifically, in step S2, the cross-sectional effective connection length L of the welded sampleiThe length value of a part without obvious interface clearance formed by the fusion of the foil 2 and the tab 1 in an atomic level in a welding area is shown; wherein, the number of the welding teeth 3 of the welding head is n, and the total length L of the welding teeth 3 of the welding head0The welding mark area s of the welding head can be obtained through the design specification of the welding head; the design of the welding head needs to be matched with the size of the tab 1 and the size of the foil 2 so as to ensure the welding effect; when the design of the welding head is determined, the number n of the welding teeth 3 of the welding head and the total length L of the welding teeth 3 of the welding head0The specific numerical value of the welding mark area s of the welding head can be obtained.
Further, the method for evaluating the ultrasonic welding effect further comprises the following steps: s4: obtaining current carrying capacity I of welding areaxIn the unit of
S5: according to the flow capacity of the welding area
Calculating to obtain a specific numerical value of the overcurrent capacity I of the welding area; wherein s is the area of the weld mark of the welding head and is in mm2. Wherein the cross-sectional effective connection length L of the welding regioniAnd the total length L of the tooth 3 of the welding head0The dimensions of (a) are as indicated in the notation in fig. 1.
Specifically, as shown in fig. 3, step S4 specifically includes the following steps: s41: determining an upper limit value T of a target temperature of a weld specimen0In units of; s42: the welding samples are led with currents I with different values0In units of A, and recording the respective currents I0Temperature value T of lower corresponding welding areax(ii) a S43: compare each TxAnd T0Taking and T0And TxT having the smallest difference therebetweenxRelative to each otherShould be I0And through
Calculating to obtain the current-carrying capacity I of the welding areax(ii) a Wherein s isAIs the welding area of the welding area, and the unit is mm2And a welding area s of the welding regionACan be calculated by measuring the length and width of the weld zone and from an area formula. Wherein the upper limit value T of the target temperature of the welding area of different products0Possibly different, upper limit value T of target temperature of welding sample0The method needs to be specifically determined according to actual working conditions.
In particular, when the effective overcurrent coefficient
When the overcurrent capacity of the welding area of the welding sample cannot reach the target overcurrent capacity, the overcurrent capacity of the welding area is poor, and the welding effect of the welding sample is poor.
Further, the foil 2 comprises a copper foil, having an effective overcurrent coefficient
When the overcurrent capacity of the welding area of the welding sample formed by ultrasonically welding the copper foil and the tab 1 reaches the target overcurrent capacity, the overcurrent capacity of the welding area is better, and the welding effect of the welding sample is better.
In particular, the foil 2 also comprises an aluminium foil, when the effective overcurrent coefficient is
When the overcurrent capacity of the welding area of the welding sample formed by ultrasonically welding the aluminum foil and the tab 1 reaches the target overcurrent capacity, the overcurrent capacity of the welding area is better, and the welding effect of the welding sample is better.
Further, as shown in fig. 4, before step S1, the method further includes step S01: and carrying out resin curing on the welding sample so as to carry out metallographic cutting to obtain a section of a welding area, thereby avoiding the problem of poor cutting effect of the welding sample.
Specifically, as shown in fig. 4, between step S1 and step S2, S02 is further included: polishing, burnishing and corroding the cutting surface of the welding sample obtained after the gold phase is cut in the step S1, so that the cutting surface formed by cutting the welding sample is smooth and flat, and the interface is clear, the cutting surface can be observed clearly, the welding area of the foil 2 and the lug 1 in the welding sample can be observed clearly, and the effective connection length L of the section of the welding area can be measured accuratelyiTo ensure the effective connection length L of the cross sectioniThe accuracy of (2). Wherein the welded area is observed by a 3D microscope.
The specific evaluation process of the evaluation method of the ultrasonic welding effect in the present embodiment is as follows, as shown in fig. 4:
firstly, resin curing is carried out on a welding sample so as to facilitate cutting; performing metallographic cutting on the welding sample to form a cutting surface with a welding area exposed to the outside; grinding, polishing and corroding the cut surface to enable the cut surface to be smooth and flat so as to observe the cut surface more clearly;
then, determining the number n of the welding teeth 3 of the welding head and the total length L of the welding teeth 3 of the welding head according to the design of the welding head0The specific numerical value of the welding-printed area s of the welding head;
then, the welding area is observed and the effective connection length L of the section of the welding area is measuredi(ii) a And according to the effective overcurrent coefficient
Calculate out
And according to calculation
Evaluating the welding effect of the welding sample;
secondly, by passing different values of current I to the welding sample0And recording the respective currents I0Lower phaseTemperature value T of corresponding welding areax(ii) a Then compare each TxAnd T0Taking and T0And TxT having the smallest difference therebetweenxCorresponding to I0And through
Calculating to obtain the current-carrying capacity I of the welding areax；
Finally, the overcurrent capacity of the welding area
And calculating a specific numerical value of the overcurrent capacity I of the welding area.
Wherein, when the effective over-current coefficient
In the meantime, the overcurrent capacity of the welding area is poor, and the welding effect of the welding sample is poor;
when the foil 2 is a copper foil and the effective overcurrent coefficient phi is larger than 0.55, the overcurrent capacity of a welding area formed by welding the copper foil and the tab 1 is better, and the welding effect of a welding sample is better;
when the foil 2 is aluminum foil and the effective overcurrent coefficient
During the process, the overcurrent capacity of a welding area formed by welding the aluminum foil and the tab 1 is better, and the welding effect of a welding sample is better.
The above description is only a preferred embodiment of the present invention, and for those skilled in the art, the present invention should not be limited by the description of the present invention, which should be interpreted as a limitation.
Claims (11)
1. An ultrasonic welding effect evaluation method is used for evaluating the ultrasonic welding effect of a welding sample, and the welding sample is obtained by ultrasonic welding of a foil (2) and a tab (1), and is characterized by comprising the following steps:
s1: cutting the welding sample in a metallographic mode;
s2: observing the welding area of the foil (2) and the tab (1) in the welding sample, and measuring the effective connection length L of the section of the welding areaiIn mm;
s3: according to the effective connection length L of the section of the welding areaiObtaining effective over-current coefficient
And according to the obtained effective overcurrent coefficient
And judging the overcurrent capacity of the welding sample so as to evaluate the ultrasonic welding effect of the welding sample.
2. The method of evaluating the effect of ultrasonic welding according to claim 1, wherein in said step S3, said effective overcurrent coefficient
The acquisition is calculated according to the following formula:
wherein n is the number of welding teeth (3) of the welding head, L0The total length of the welding teeth (3) of the welding head is in mm.
3. The method of evaluating the effect of ultrasonic welding according to claim 2, further comprising the steps of:
s4: obtaining a current carrying capacity I of the welding areaxIn the unit of
S5: according to the overcurrent capacity of the welding area
Calculating a specific over-current capacity value I of the welding area; wherein s is the area of the welding head in mm2And I is an overcurrent value and has a unit of A.
4. The method of evaluating the effect of ultrasonic welding according to claim 3, wherein said step S4 includes the steps of:
s41: determining an upper limit value T of a target temperature of the welding sample0In units of;
s42: the welding samples are led with currents I with different values0In units of A, and recording the respective currents I0The temperature value T of the corresponding welding areax；
S43: compare each TxAnd T0Taking and T0And TxT having the smallest difference therebetweenxCorresponding to I0And through
Calculating to obtain the current-carrying capacity I of the welding areax(ii) a Wherein s isAIs the welding area of the welding area, and the unit is mm2。
5. The method of evaluating the effect of ultrasonic welding according to claim 1, wherein in said step S2, the cross-sectional effective joining length L of said welding sampleiRefers to the length value of the part between the foil (2) and the pole lug (1) in the welding area, which is fused at the atomic level and has no interface clearance.
6. The method of evaluating the effect of ultrasonic welding according to claim 1, wherein when the effective overcurrent coefficient is set
The flow capacity of the weld area of the weld sample did not reach the target flow capacity.
7. The method of evaluating the effect of ultrasonic welding according to claim 6, wherein the foil (2) comprises a copper foil, and the effective overcurrent coefficient
And then, the copper foil and the lug (1) are welded through ultrasonic to form the welding area of the welding sample, and the overcurrent capacity of the welding area reaches the target overcurrent capacity.
8. The method of evaluating the effect of ultrasonic welding according to claim 6, wherein the foil (2) further comprises an aluminum foil, and the effective overcurrent coefficient
And when the aluminum foil and the electrode lug (1) are welded through ultrasonic welding to form the welding area of the welding sample, the overcurrent capacity of the welding area reaches the target overcurrent capacity.
9. The method for evaluating the effect of ultrasonic welding according to claim 2, wherein the number n of the teeth (3) of the horn, and the total length L of the teeth (3) of the horn are0And the welding area s of the welding head can be obtained through the design specification of the welding head.
10. The method of evaluating the effect of ultrasonic welding according to claim 1, further comprising, before said step S1:
s01: carrying out resin curing on the welding sample so as to facilitate metallographic cutting;
and further comprising, between the step S1 and the step S2:
s02: striking the welding sample after the gold phase is cut in the step S1Grinding, polishing and corroding to make the interface of the cut surface formed by cutting the welding sample clear so as to observe and measure the effective connection length L of the sectioni。
11. A lithium ion battery comprising a foil (2) and a tab (1), and an ultrasonic welding effect between the foil (2) and the tab (1) is evaluated by the method for evaluating an ultrasonic welding effect according to any one of claims 1 to 10.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111154023.4A CN113922003B (en) | 2021-09-29 | 2021-09-29 | Ultrasonic welding effect evaluation method and lithium ion battery |
Applications Claiming Priority (1)
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| CN112924544A (en) * | 2021-01-25 | 2021-06-08 | 江西志浩电子科技有限公司 | Ultrasonic treatment effect detection device and circuit board production method |
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| CN112222596A (en) * | 2020-10-20 | 2021-01-15 | 天津市捷威动力工业有限公司 | Ultrasonic welding method for soft package lithium battery tab |
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