CN109540662B - Square full-lug battery cell welding tension testing method - Google Patents
Square full-lug battery cell welding tension testing method Download PDFInfo
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- CN109540662B CN109540662B CN201811204290.6A CN201811204290A CN109540662B CN 109540662 B CN109540662 B CN 109540662B CN 201811204290 A CN201811204290 A CN 201811204290A CN 109540662 B CN109540662 B CN 109540662B
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- G—PHYSICS
- G01—MEASURING; TESTING
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Abstract
The invention provides a method for testing welding tension of a square full-lug battery cell, and belongs to the technical field of battery testing. The method comprises the following steps: 1) preparing a battery cell testing body, wherein the battery cell testing body comprises a lug and a flexible connection welded on the lug; the tab comprises more than two layers of current collectors which are arranged in a stacked mode, and the flexible connection is welded on the outermost surface of the tab; 2) the parts at two sides of the flexible connection on the battery cell testing body are respectively stretched towards opposite directions, and the tensile force when the flexible connection is tested to be disconnected with the lug or the tensile force when the lug is disconnected with the lug is the welding tensile force. The invention prepares the battery cell test body by cutting the actual battery cell or uses the same process and material to prepare the battery cell test body which has the same layer number and the consistent welding form of the lug with the actual battery cell pole piece; the prepared electric core testing body is equivalent to an actual electric core, so that the welding tension testing result of the electric core testing body can truly reflect the welding effect of the actual electric core.
Description
Technical Field
The invention relates to a method for testing welding tension of a square full-lug battery cell, and belongs to the technical field of battery testing.
Background
In modern society, lithium batteries are widely used in the fields of mobile phones, computers, electric vehicles and the like. In the production process of lithium batteries, the welding effect of the lithium battery core has a significant influence on the performance of the lithium battery, for example: the welding effect of the cell flexible connection and the tab directly determines the over-flow and the internal resistance of the battery, so that the welding effect of the lithium battery cell needs to be effectively tested.
For the welding effect verification of the lithium battery core with the full-lug structure, due to the limitation of the structure of the lithium battery core, a common test method in the battery industry is to use a sample to replace an actual battery core for testing, and reflect the welding effect of the actual battery core by the welding effect of the sample, but the currently used sample test method has the following defects: firstly, the copper and aluminum foil materials used by the sample piece for simulating the lug of the battery cell are not always in a uniform batch with the actual copper and aluminum foil materials of the battery cell, and if the copper and aluminum foil materials of the sample piece are oxidized, the test result and the actual welding effect of the battery cell are distorted; simulating that copper foil layers and aluminum foil layers stacked on the battery cell lug are parallel surfaces, and forming a welding surface by multiple layers of parallel copper foil layers in the welding process, wherein the actual battery cell lug is a conical surface under the condition of pressure, and the copper foil on the outermost layer of the battery cell lug is an inclined surface, so that the welding effect is influenced; and thirdly, both prewelding and formal welding of the sample piece are manual discharging, so that prewelding and formal welding marks are often not overlapped, the actually produced battery cell is accurately positioned on the clamp, the overlap ratio of the prewelding and the formal welding marks is higher, and the welding mark overlap ratio has certain influence on the welding effect.
In summary, in the sample piece testing method commonly used in the battery industry at present, there is an error between the testing result and the actual welding effect of the battery cell, and the actual welding effect of the battery cell cannot be accurately reflected.
Disclosure of Invention
The invention aims to provide a method for testing the welding tension of a square full-lug battery cell, which is used for solving the problem that the actual welding effect of the battery cell cannot be accurately reflected by using a sample piece testing method in the prior art.
In order to achieve the purpose, the invention provides a method for testing the welding tension of a square full-lug battery cell, which comprises the following steps:
1) preparing a battery cell testing body, wherein the battery cell testing body comprises a lug and a flexible connection welded on the lug; the tab comprises more than two layers of current collectors which are arranged in a stacked mode, and the flexible connection is welded on the outermost surface of the tab;
2) the parts at two sides of the flexible connection on the battery cell testing body are respectively stretched towards opposite directions, and the tensile force when the flexible connection is tested to be disconnected with the lug or the tensile force when the lug is disconnected with the lug is the welding tensile force.
The invention has the beneficial effects that: preparing a battery cell test body by cutting an actual battery cell or preparing the battery cell test body with the same layer number and the same lug welding form as the actual battery cell pole piece by using the same process and material; the prepared electric core testing body is equivalent to an actual electric core, so that the welding tension testing result of the electric core testing body can truly reflect the welding effect of the actual electric core.
In order to enable the welding tension test result of the cell test body to truly reflect the actual cell welding effect, the cell test body in the step 1) is prepared by adopting a method comprising the following steps as an improvement of the square full-lug cell welding tension test method: and cutting the square full-lug battery cell along the position between the positive lug and the negative lug to obtain a battery cell testing body.
For the above manner of obtaining the battery cell test body by cutting, the cutting position is located at a position between the tabs at the two ends of the battery cell and including the electrode material. Specifically, the cutting line is parallel to a center line between the tabs at the two ends of the battery cell and is close to the tab at one end.
In order to test the tensile force between the flexible connection and the lug, as another improvement of the method for testing the welding tensile force of the square full lug battery cell, the stretching in the step 2) is performed along the extension direction of the long edge of the full lug on the battery cell testing body.
In order to enable the welding tension test result of the cell test body to truly reflect the actual cell welding effect, as another improvement of the square full-lug cell welding tension test method, the cell test body in the step 1) is prepared by adopting a method comprising the following steps: preparing two half-cells by adopting the same pole pieces and diaphragms as the square full-lug cell and adopting the same preparation method as the square full-lug cell, wherein the number of the pole pieces of each half-cell is half of that of the pole pieces of the square full-lug cell; and welding the lugs at one ends of the two half-cells with the same polarity together in the same direction, and then unfolding the non-welding ends of the two half-cells towards opposite directions to obtain the cell testing body.
In order to test the tension between the lug and the lug, the step 2) is performed along the unfolding direction of two non-welding ends of the cell test body as a further improvement of the square full-lug cell welding tension test method.
In order to test the welding tension of the battery cell test body, as a further improvement of the method for testing the welding tension of the square full-lug battery cell, the stretching in the step 2) is carried out, two clamps are used for clamping the parts at two sides of the flexible connection on the battery cell test body respectively during stretching, and then the two clamps are stretched towards opposite directions respectively.
Drawings
Fig. 1 is a schematic diagram of a cutting of a square full tab cell of the present invention;
fig. 2 is a schematic view of a first tension testing method of the present invention for a flexible connection and tab;
fig. 3 is a schematic diagram of a second tension testing method of the flexible connection and tab of the present invention;
fig. 4 is a schematic diagram of a tab and a tab first tension testing method of the present invention.
In the figure, 1, a first battery cell; 2. a second cell; 3. a negative electrode full tab; 4. soft connection; 5. a cover plate assembly; 6. cutting a line; 6-1, the center line of the battery core; 6-2, the upper edge of the tab; 7. an upper clamp; 8. a lower clip; 9. a half-cell; 10. welding the lug; 11. and (6) welding and then performing flexible connection.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Before the method provided by the invention is used for testing the welding tension of the square full-lug battery cell, a battery cell testing body is prepared. The square full-lug battery cell is a winding battery cell.
Example 1
Fig. 1 is a schematic diagram of cutting a square full tab cell of the present invention, as shown in the figure: the battery comprises a first battery cell 1, a second battery cell 2, a negative pole full lug 3, a flexible connection 4, a cover plate assembly 5, a cutting line 6, a battery cell central line 6-1 and a lug upper edge 6-2.
The first battery cell 1 and the second battery cell 2 are square winding type full-lug battery cells which are formed by stacking and winding a positive plate, a diaphragm, a negative plate and a diaphragm; the positive plate and the negative plate are both provided with full tabs; the positive plate comprises a positive current collector and a positive material layer coated on the positive current collector, one side of the positive current collector along the winding extension direction is provided with a positive pole blank area which is not coated with a positive material, and the positive pole blank area forms a positive pole full lug. After winding, the positive electrode full tab forms a multi-layer tab overlapping structure, and the structure is welded with the positive electrode flexible connection at the outermost side to form a welding structure of the positive electrode full tab and the positive electrode flexible connection. The negative pole piece includes that the negative pole mass flow body and coating are on the negative pole mass flow body negative material layer, and the negative pole mass flow body is equipped with the negative pole of uncoated negative material along coiling extending direction's one side and leaves white the district, and the negative pole leaves white the district and has formed the full utmost point ear of negative pole. After winding, the negative electrode full tab forms a multi-layer tab overlapping structure, and the structure is welded with the negative electrode flexible connection at the outermost side to form a welding structure of the negative electrode full tab and the negative electrode flexible connection.
As other embodiments, the square full tab cell may include only 1 cell, or include more than 3 cells.
In fig. 1, the first battery cell 1 and the second battery cell 2 are provided with positive full tabs at the upper ends thereof and negative full tabs 3 at the lower ends thereof, and the outermost surface of the negative full tabs 3 is welded with a flexible connection 4. And an electrode terminal is arranged on the cover plate component 5, penetrates through the cover plate component 5, one end of the electrode terminal is connected with the cathode full-tab 3 through a flexible connection 4, and the other end of the electrode terminal is led out to be used as a cathode.
When the battery cell test body is prepared, a square full-lug battery cell produced on site is randomly extracted, then the square full-lug battery cell is cut along a cutting line 6 shown in figure 1 by a cutting machine, a negative full-lug 3, a flexible connection 4 and a welding part between the negative full-lug and the flexible connection 4 are completely reserved, and a part with less electrode materials is used as the battery cell test body, so that the reliability of a test result is improved.
The cutting line 6 is perpendicular to the axis direction of the square full-lug battery cell and is positioned between the battery cell center line 6-1 of the square full-lug battery cell and the lug upper edge 6-2; preferably, the cutting line 6 should be as close as possible to the upper edge 6-2 of the tab, so that the cell test body contains as little electrode material as possible.
In this embodiment, the square full tab cell includes a cover plate assembly; in other embodiments, the square full tab cell may not contain a cover plate assembly.
As shown in fig. 2: during testing, the two chucks of the tensile machine are used for respectively clamping the cathode full-lug 3 on two sides of the flexible connection 4, and the tensile force F is applied to test the tensile force between the flexible connection 4 and the cathode full-lug 3.
In the testing process, the welding seal between the flexible connection 4 and the negative pole full lug 3 can be drawn open in one region, the measured tension value is the maximum tension value capable of bearing between the flexible connection 4 and the negative pole full lug 3, and the larger the maximum tension value is, the better the welding effect is.
The testing method of the embodiment uses the actually produced battery cell for testing, and can reflect the welding effect of the battery cell more truly.
Example 2
As shown in fig. 3: during the test, the negative pole full tab 3 and the electrode material part of 4 both sides of flexible coupling are cliied respectively with two splint, and every splint comprises upper clamp 7 and lower clamp 8, cliies two splint respectively with two chucks of pulling force machine again, applys pulling force F, and the tensile force when testing the welding seal between flexible coupling 4 and the negative pole full tab 3 and being pulled open is as the biggest pulling force value that can bear between flexible coupling 4 and the negative pole full tab 3, and the biggest pulling force value is big more, and the welding effect is better.
According to the testing method, the clamping plates are used for clamping the lug and the electrode material at the same time, the stress area is increased, in the testing process, the electrode material is directly stressed, when the electrode material is stressed and elastically deforms, the tensile force is indirectly transmitted to the flexible connection, the situation that welding marks between the flexible connection and the lug are not pulled open, the lug is directly torn to interfere with the testing result is effectively avoided, and the obtained testing result is more accurate and reliable.
Example 3
As shown in fig. 4: when the cell test body is prepared, the same pole pieces and diaphragms as those of the square full-lug cell are adopted, the same winding mode is adopted to prepare two half-cells 9, and the number of the pole pieces of each half-cell 9 is half of that of the square full-lug cell; each half cell 9 has its own tab and flexible connection; and welding the lugs at the ends with the same polarity of the two half-cells 9 together in the same direction, and then unfolding the non-welding ends of the two half-cells 9 in opposite directions to obtain the cell testing body. Fig. 4 shows a welded tab 10 and a welded flexible joint 11.
During testing, the two half-cell 9 are respectively clamped, tension F is applied, tension when welding marks between the lug and the lug of the two half-cell 9 are pulled is tested, and the maximum tension value which can be borne between the lug and the lug is used, and the larger the maximum tension value is, the better the welding effect is.
In this embodiment, a cell testing body is prepared by using the same process and material as those used for producing an actual cell, and tabs at one end of two half-cells with the same polarity are welded together in the same direction during preparation, and the sum of the number of pole pieces of the two half-cells is ensured to be equal to the number of pole pieces of the actual cell, so that the tabs of the cell testing body form a conical surface consistent with the actual cell, and therefore, the prepared cell testing body is equivalent to the actual cell; and carrying out welding tension test on the battery cell test body, wherein the test result can be regarded as the welding tension test result of the actual battery cell.
The square full-lug battery cell can also be a laminated battery cell, and for the laminated battery cell, the method for preparing the battery cell test body by using the cutting mode and the welding mode and the corresponding test method are the same as those of a winding battery cell, and are not repeated here.
Claims (3)
1. A method for testing welding tension of a square full-lug battery cell comprises the following steps:
1) preparing a battery cell testing body, wherein the battery cell testing body comprises a lug and a flexible connection welded on the lug; the tab comprises more than two layers of current collectors which are arranged in a stacked mode, and the flexible connection is welded on the outermost surface of the tab;
2) respectively stretching the parts at two sides of the flexible connection on the battery cell testing body in opposite directions, wherein the tensile force when the flexible connection is disconnected with the lug or the tensile force when the lug is disconnected with the lug is the welding tensile force;
the battery cell test body in the step 1) is prepared by adopting a method comprising the following steps: preparing two half-cells by adopting the same pole pieces and diaphragms as the square full-lug cell and adopting the same preparation method as the square full-lug cell, wherein the number of the pole pieces of each half-cell is half of that of the pole pieces of the square full-lug cell; and welding the lugs at one ends of the two half-cells with the same polarity together in the same direction, and then unfolding the non-welding ends of the two half-cells towards opposite directions to obtain the cell testing body.
2. The method for testing the welding tension of the square full-tab battery cell according to claim 1, wherein the method comprises the following steps: and 2), stretching along the unfolding direction of the two non-welding ends of the battery cell test body.
3. The square full-tab battery cell welding tension test method according to claim 1 or 2, characterized in that: and 2) stretching, wherein the two clamps are used for clamping the parts at the two sides of the soft connection on the battery cell testing body respectively during stretching, and then the two clamps are stretched towards opposite directions respectively.
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| CN201811204290.6A CN109540662B (en) | 2018-10-16 | 2018-10-16 | Square full-lug battery cell welding tension testing method |
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| CN201811204290.6A CN109540662B (en) | 2018-10-16 | 2018-10-16 | Square full-lug battery cell welding tension testing method |
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| CN109540662B true CN109540662B (en) | 2021-07-30 |
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| CN110057671B (en) * | 2019-05-08 | 2021-07-02 | 浙江锋锂新能源科技有限公司 | Method for detecting ultrasonic welding peeling strength of lithium battery tab |
| CN110426282A (en) * | 2019-08-06 | 2019-11-08 | 惠州亿纬锂能股份有限公司 | A kind of lithium ion battery Laser Welding effect testing method and fixture |
| CN111650043B (en) * | 2020-03-23 | 2023-05-05 | 万向一二三股份公司 | Ultrasonic welding quality detection method |
| CN111584941B (en) * | 2020-05-26 | 2021-10-26 | 苏州凌威新能源科技有限公司 | Method for testing welding effect of battery tab |
| CN113466033A (en) * | 2021-05-28 | 2021-10-01 | 曙鹏科技（深圳）有限公司 | Lithium battery tab welding tension testing method |
| CN114034575B (en) * | 2021-10-08 | 2023-11-21 | 珠海华冠科技股份有限公司 | Battery welding detection mechanism and battery welding detection method |
| CN114544336B (en) * | 2021-11-08 | 2023-08-15 | 万向一二三股份公司 | Method for representing welding tension of soft-package battery cell lugs of multi-layer lamination |
| CN114935541A (en) * | 2022-07-25 | 2022-08-23 | 楚能新能源股份有限公司 | Lithium ion battery lug welding effect evaluation method |
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| CN202582999U (en) * | 2012-02-08 | 2012-12-05 | 东莞市理士奥电源技术有限公司 | Weld strength detector for surface patch of storage battery |
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