阅读说明：本技术 寻找软包绝缘不良电芯腐蚀点的方法 (Method for searching corrosion point of soft package poor-insulation battery cell ) 是由 张业军 彭升政 陈俊梯 于 2020-05-15 设计创作，主要内容包括：本发明公开了寻找软包绝缘不良电芯腐蚀点的方法。该方法包括：(1)分别在绝缘不良电芯的负极耳上和电芯铝塑膜封边上打孔,以便在所述负极耳上形成第一孔洞,在所述铝塑膜封边上形成第二孔洞；(2)采用金属丝将所述第一孔洞和所述第二孔洞连接,以便使所述负极耳与所述铝塑膜封边的铝层接触；(3)将步骤(2)得到的绝缘不良电芯置于高温环境下,观察所述铝塑膜封边的腐蚀位置。该方法通过在绝缘不良电芯上人为外部短接负极与铝塑膜,制造电子通道,可以在高温环境下实现快速腐蚀,从而快速找出绝缘不良的根本原因并进行分析改善。(The invention discloses a method for searching a soft package poor-insulation battery cell corrosion point. The method comprises the following steps: (1) respectively punching holes on a negative electrode lug of a poorly insulated battery cell and a sealing edge of an aluminum plastic film of the battery cell so as to form a first hole on the negative electrode lug and a second hole on the sealing edge of the aluminum plastic film; (2) connecting the first hole and the second hole by using a metal wire so as to enable the negative electrode tab to be in contact with the aluminum layer of the edge sealed aluminum-plastic film; (3) and (3) placing the poor-insulation battery cell obtained in the step (2) in a high-temperature environment, and observing the corrosion position of the edge sealing of the aluminum-plastic film. According to the method, the cathode and the aluminum-plastic film are artificially and externally short-circuited on the electric core with poor insulation to manufacture the electronic channel, and rapid corrosion can be realized in a high-temperature environment, so that the root cause of the poor insulation can be rapidly found out and analyzed and improved.)

1. A method for searching a soft package poor-insulation battery cell corrosion point is characterized by comprising the following steps:

(1) respectively punching holes on a negative electrode lug of a poorly insulated battery cell and a sealing edge of an aluminum plastic film of the battery cell so as to form a first hole on the negative electrode lug and a second hole on the sealing edge of the aluminum plastic film;

(2) connecting the first hole and the second hole by using a metal wire so as to enable the negative electrode tab to be in contact with the aluminum layer of the edge sealed aluminum-plastic film;

(3) and (3) placing the poor-insulation battery cell obtained in the step (2) in a high-temperature environment, and observing the corrosion position of the edge sealing of the aluminum-plastic film.

2. The method of claim 1, wherein the poorly insulated cells are cells in a soft-packed lithium ion battery, and the lithium ion battery comprises a power battery and a 3C digital battery.

3. The method of claim 1 or 2, wherein a ratio of a distance from any point on the second hole to an inner edge of the edge seal of the aluminum-plastic film to a width of the edge seal of the aluminum-plastic film is (0.1-0.7): 1.

4. the method of claim 3, wherein the second hole is provided on the aluminum plastic film side seal edge and is disposed adjacent to the negative tab.

5. The method of claim 1 or 4, wherein the number of the second holes is one; alternatively, the first and second electrodes may be,

the number of the second holes is multiple, the second holes correspond to one first hole, or the second holes correspond to different first holes respectively, each second hole is connected with the first holes through the metal wires respectively and independently, and the metal wires connected with the second holes are not in contact with each other.

6. The method of claim 5, wherein the wire is made of silver, copper, iron, aluminum or nickel, and the diameter of the wire is not greater than 1 mm.

7. The method according to claim 1 or 6, wherein the ratio of the pore diameter of the first pores and the second pores to the wire diameter is (1.05-1.2): 1.

8. the method according to claim 7, wherein the temperature of the high temperature environment is 30 to 60 ℃.

9. The method of claim 1 or 8, further comprising, prior to performing step (3): and respectively carrying out adhesive tape sticking insulation protection on the positive electrode lug and the negative electrode lug of the electric core with poor insulation.

10. The method of claim 9, wherein the wire is connected to the first and second apertures by an external power source.

Technical Field

The invention belongs to the field of batteries, and particularly relates to a method for searching a soft package poor-insulation battery cell corrosion point.

Background

When the soft package lithium battery is used for a long time, corrosion of a certain battery cell can be found. The corrosion spot is usually located at the seal position. This kind of electricity core later stage uses and has the potential safety hazard, especially power electricity core, and a corresponding module of electricity core corruption will be disassembled, and the seepage of electrolyte can corrode mechanical components moreover. At present, an insulation defective product is selected by testing the voltage between a negative electrode and an aluminum-plastic film or testing the voltage between a positive electrode and the aluminum-plastic film through an insulation tester, but a problem battery cell cannot be completely selected through insulation testing, the battery cell cannot puncture the aluminum-plastic film to perform insulation testing after the edge folding is finally sealed, and a poor insulation battery cell after the edge folding cannot be selected. Therefore, the insulation short circuit point is checked according to the defective products of the insulation test, and the root cause of corrosion is solved. However, conventional disassembly is difficult to find short circuit problems, requires a long time at high temperature and high humidity, and may require several months or longer of standing time.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, the invention aims to provide a method for searching the soft package poor insulation cell corrosion point. According to the method, the cathode and the aluminum-plastic film are artificially and externally short-circuited on the electric core with poor insulation to manufacture the electronic channel, and rapid corrosion can be realized in a high-temperature environment, so that the root cause of the poor insulation can be rapidly found out and analyzed and improved.

According to a first aspect of the invention, the invention provides a method for searching for a soft package poor insulation cell corrosion point. According to an embodiment of the invention, the method comprises:

(1) respectively punching holes on a negative electrode lug of a poorly insulated battery cell and a sealing edge of an aluminum plastic film of the battery cell so as to form a first hole on the negative electrode lug and a second hole on the sealing edge of the aluminum plastic film;

(2) connecting the first hole and the second hole by using a metal wire so as to enable the negative electrode tab to be in contact with the aluminum layer of the edge sealed aluminum-plastic film;

(3) and (3) placing the poor-insulation battery cell obtained in the step (2) in a high-temperature environment, and observing the corrosion position of the edge sealing of the aluminum-plastic film.

The inventors have found that the occurrence of corrosion in the cell requires the simultaneous presence of two conditions: and the ion channel and the electron channel indicate that the ion channel appears because the cell is tested to be poor in insulation. According to the method for searching the corrosion point of the soft package poor-insulation battery core, on one hand, an electronic channel is manufactured by short-circuiting the negative electrode and the aluminum-plastic film through the artificial outside, an ion channel is formed between the inside of the battery negative electrode and the aluminum layer of the aluminum-plastic film, the aluminum layer starts to corrode, the aluminum layer of the aluminum-plastic film is packaged after the electronic channel is formed outside, the aluminum layer is continuously consumed, the rapid corrosion can be realized in a high-temperature environment, and the corrosion point can be found within one week (1-3 days in common); on the other hand, the external short circuit is connected with the negative electrode by adopting the aluminum-plastic film, and because the potential of the negative electrode is low, the aluminum in the low-potential aluminum-plastic film can be corroded. Therefore, the method is simple and easy to implement, and the corrosion point can be quickly found without an external high-voltage power supply, so that the corrosion point can be analyzed, the process improvement can be carried out according to the analysis reason, the generation of the insulation defective products is reduced, and the defective products flowing into a client side are reduced.

In addition, the method for finding the soft package poor insulation cell corrosion point according to the above embodiment of the present invention may further have the following additional technical features:

in some embodiments of the present invention, the poorly insulated battery cell is a battery cell in a soft-package lithium ion battery, and the lithium ion battery includes a power battery and a 3C digital battery.

In some embodiments of the present invention, a ratio of a distance from any point on the second hole to the inner edge of the edge seal of the aluminum-plastic film to a width of the edge seal of the aluminum-plastic film is (0.1-0.7): 1.

in some embodiments of the present invention, the second hole is disposed on the side sealed edge of the aluminum plastic film and adjacent to the negative electrode tab.

In some embodiments of the present invention, the number of the second holes is one; or, the number of the second holes is multiple, the second holes correspond to one of the first holes, or the second holes correspond to different first holes, each of the second holes independently passes through the metal wire and is connected with the first holes, and the metal wires connected with the second holes are not in contact with each other.

In some embodiments of the present invention, the metal wire is made of silver, copper, iron, aluminum or nickel, and the diameter of the metal wire is not greater than 1 mm.

In some embodiments of the present invention, the ratio of the pore diameter of the first pore and the second pore to the diameter of the metal wire is (1.05-1.2): 1.

in some embodiments of the present invention, the temperature of the high temperature environment is 30-60 ℃.

In some embodiments of the present invention, before performing step (3), further comprising: and respectively carrying out adhesive tape sticking insulation protection on the positive electrode lug and the negative electrode lug of the electric core with poor insulation.

In some embodiments of the present invention, the wire is connected to the first hole and the second hole via an external power source.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic diagram of an external electronic channel formed on a poorly insulated cell according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

According to a first aspect of the invention, the invention provides a method for searching for a soft package poor insulation cell corrosion point. According to an embodiment of the invention, as shown with reference to fig. 1, the method comprises: (1) respectively punching holes on a negative electrode lug of a poorly insulated battery cell and a sealing edge of an aluminum plastic film of the battery cell so as to form a first hole on the negative electrode lug and a second hole on the sealing edge of the aluminum plastic film; (2) connecting the first hole and the second hole by using a metal wire so as to enable the negative electrode tab to be in contact with the aluminum layer with the edge sealed by the aluminum-plastic film; (3) and (3) placing the poor-insulation battery cell obtained in the step (2) in a high-temperature environment, and observing the corrosion position of the edge sealing of the aluminum-plastic film. The inventors have found that the occurrence of corrosion in the cell requires the simultaneous presence of two conditions: the method is simple and easy to implement, corrosion points can be found quickly in one week (common 1-3 days), the corrosion points can be found quickly without an external high-voltage power supply, further the corrosion points can be analyzed, process improvement can be carried out according to analysis reasons, and the generation of insulation defective products is reduced, so that the defective products are reduced and flow into a client side.

The method for finding the soft package poor insulation cell corrosion point according to the above embodiment of the present invention is described in detail with reference to fig. 1.

According to the embodiment of the invention, the corrosion principle of the aluminum-plastic film is as follows: inside and the plastic-aluminum membrane aluminium lamination of laminate polymer core negative pole form ion channel, and the aluminium lamination begins to corrode, uses the aluminium foil as anodal, copper foil as the negative pole as the example, corrodes the potential: al (Al)³⁺+3e＝Al E＝-1.66V，Cu²⁺+ 2E-Cu E-0.3419V, the aluminum layer of the edge seal of the aluminum-plastic film is consumed continuously after the electronic channel is formed outside: AL + xe^-+xLi⁺→Li_xAl, late corrosion: li_xAl+O₂→Li₂O+Al₂O₃，LixAl+2H₂O→H₂+LiAlO₂。

According to a specific embodiment of the present invention, a source of the cell with poor insulation in the present invention is not particularly limited, and a person skilled in the art may select the cell according to actual needs, for example, the cell with poor insulation may be a cell in a soft package lithium ion battery, and the lithium ion battery may further include a power battery and a 3C digital battery, so that detection of corrosion points of the cell with poor insulation in different batteries may be achieved.

According to another embodiment of the invention, a ratio of a distance from any point on the second hole to the inner edge of the edge seal of the aluminum-plastic film to a width of the edge seal of the aluminum-plastic film is (0.1-0.7): 1, wherein, the interior edge of plastic-aluminum membrane banding refers to the boundary line of plastic-aluminum membrane banding and electric core encapsulation district, the distance that arbitrary one point on the second hole reaches the interior edge of plastic-aluminum membrane banding refers to the shortest distance between arbitrary one point on the second hole and the interior edge of plastic-aluminum membrane banding at this hole place, arbitrary one point on the second hole reaches electric core encapsulation district promptly. When the second hole is formed on the aluminum-plastic film edge sealing, the closer the second hole is to the electric core packaging area, the more easily an external electronic channel is formed, and the faster the corrosion rate of the aluminum-plastic film is, however, if the distance between the second hole and the boundary line between the aluminum-plastic film edge sealing and the electric core packaging area is too close, the edge sealing of the aluminum-plastic film is easily damaged during punching, so that the liquid leakage phenomenon occurs at the second hole, and the judgment of the corrosion point is influenced.

According to another embodiment of the invention, the second holes may be formed on the side edge of the aluminum-plastic film and disposed adjacent to the negative electrode tab, and the inventor finds that only aluminum in the low-potential aluminum-plastic film is corroded.

According to another embodiment of the present invention, the number of the second holes may be one, and at this time, the number of the first holes is also one, and the aluminum layer edge-sealed by the aluminum plastic film is connected to the negative electrode tab through the metal wire.

According to another embodiment of the present invention, the number of the second holes may be multiple, and the multiple second holes may correspond to one first hole; or the plurality of second holes may also correspond to different first holes, that is, each first hole corresponds to one second hole, so that a plurality of external electronic paths can be formed simultaneously, and the efficiency of finding the etch pits can be further improved. Further, when the number of the second holes can be multiple, each second hole is connected with the first hole through the metal wire independently, and the metal wires connected with the second holes are not in contact with each other, so that the accuracy of the corrosion point searching method can be further improved.

According to another embodiment of the present invention, the material of the wire in the present invention is not particularly limited, and those skilled in the art can select the wire according to actual needs only to satisfy the requirement that the wire has better conductivity, for example, the material of the wire may be silver, copper, iron, aluminum, nickel, or the like. Further, the diameter of the metal wire can be not larger than 1mm, so that the metal wire can be more favorably connected with the first hole and the second hole, and the operation is convenient.

According to another embodiment of the present invention, the ratio of the diameter of the first hole to the diameter of the wire may be (1.05-1.2): 1, if the apertures of the first hole and the second hole are too large, the contact area between the metal wire and the negative electrode lug and between the metal wire and the aluminum layer of the aluminum plastic film is too small, and the corrosion efficiency of the aluminum plastic film is affected.

According to another embodiment of the present invention, the second hole may be located in an area 3mm outside the cell encapsulation area, so that the accuracy and efficiency of the corrosion point finding method may be further improved. For example, the poorly insulated battery cell may be a battery cell in a power battery, the negative electrode tab of the battery cell and the side edge seal of the aluminum-plastic film are punched, the size of the hole is slightly larger than that of the metal wire, so as to ensure that metal can normally pass through the hole, and based on that the side edge seal of the aluminum-plastic film of a general power battery is larger than 5mm, the position of a second hole in the battery cell of the power battery is located within 3mm of the outer side of the packaging area, so that the second hole is adjacent to the first hole; or, insulating bad electric core is 3C digital electric core, punches to electric core negative pole ear and plastic-aluminum membrane side banding, and the hole size is slightly bigger than the wire, guarantees that the metal can normally pass, is greater than 3mm based on general 3C digital electric core plastic-aluminum membrane side banding, makes the position of second hole be located the regional outside 2mm of encapsulation in the digital electric core of 3C within, makes the neighbouring first hole setting of second hole.

According to another embodiment of the present invention, the temperature of the high temperature environment may be 30 to 60 ℃, so that the corrosion efficiency may be further improved, and preferably, the temperature of the high temperature environment may be 40 to 50 ℃. According to a specific example of the invention, the poor-insulation electric core with the external electronic path can be placed in a high-temperature box for standing, and batteries with different systems and sizes can be properly adjusted in temperature in the high-temperature box according to actual conditions. Further, the storage time of the poor-insulated battery cell in a high-temperature environment can be not more than 7 days.

According to another specific embodiment of the present invention, before performing step (3), the method may further include: and the positive electrode lug and the negative electrode lug of the poor-insulation battery cell are respectively subjected to adhesive tape sticking insulation protection, so that the short circuit phenomenon can be avoided.

According to another embodiment of the invention, the metal wire may be connected to the first hole and the second hole through an external power source, and specifically, two metal wires may be used to connect the positive electrode and the negative electrode of the external power source to the first hole and the second hole, so that the external power source may be further used to improve the corrosion efficiency of the aluminum plastic film, thereby improving the efficiency of finding the corrosion point. Wherein, the voltage of the external power supply can be not more than 200V.

In summary, according to the method for finding the corrosion point of the soft package poor-insulation battery core in the embodiment of the invention, on one hand, the negative electrode and the aluminum-plastic film are short-circuited artificially outside to manufacture the electronic channel, the ion channel is formed between the inside of the battery negative electrode and the aluminum layer of the aluminum-plastic film, the aluminum layer starts to corrode, the aluminum layer of the aluminum-plastic film is packaged after the electronic channel is formed outside, the aluminum layer is continuously consumed, the rapid corrosion can be realized in a high-temperature environment, and the corrosion point can be found within one week (usually 1 to 3 days); on the other hand, the external short circuit is connected with the negative electrode by adopting the aluminum-plastic film, and because the potential of the negative electrode is low, the aluminum in the low-potential aluminum-plastic film can be corroded. Therefore, the method is simple and easy to implement, and the corrosion point can be quickly found without an external high-voltage power supply, so that the corrosion point can be analyzed, the process improvement can be carried out according to the analysis reason, the generation of the insulation defective products is reduced, and the defective products flowing into a client side are reduced.

The invention will now be described with reference to specific examples, which are intended to be illustrative only and not to be limiting in any way.

And providing a plurality of power soft package battery cells with the same specification and the same batch, and analyzing the influence of different factors on the occurrence time of corrosion points.

Example 1

1) Punching holes on a negative electrode lug of a poor-insulation battery cell of the power soft package battery and a side sealing edge of an aluminum-plastic film of the battery cell respectively, forming a first hole on the negative electrode lug, forming a second hole on the side sealing edge of the aluminum-plastic film, wherein the hole diameters of the first hole and the second hole are both 1.1mm, the width of the side sealing edge of the aluminum-plastic film is 6mm, and the second hole is positioned within 3mm of the outer side of a packaging area;

2) connecting the first hole and the second hole by using a copper wire with the diameter of 1mm, and enabling the negative electrode tab to be in contact with the aluminum layer with the edge sealed by the aluminum-plastic film;

3) and (3) carrying out adhesive tape pasting protection on the positive and negative lugs of the poor-insulation battery cell obtained in the step 2), placing the poor-insulation battery cell in a high-temperature box, standing for 7 days, controlling the temperature in the high-temperature box to be 45 ℃, and observing whether the edge sealing of the aluminum-plastic film has corrosion points within 7 days.

Example 2

The difference from example 1 is that the first and second holes each have a hole diameter of 1.2 mm.

Comparative example 1

The difference from example 1 is that the first and second holes each have a hole diameter of 1.3 mm.

Example 3

The difference from example 1 is that the temperature in the high temperature chamber was controlled to 30 ℃.

Example 4

The difference from example 1 is that the temperature in the high temperature chamber was controlled to 60 ℃.

Comparative example 2

The difference from example 1 is that the temperature in the high temperature chamber was controlled to 20 ℃.

Comparative example 3

The difference from embodiment 1 is that the second hole is located in an area outside the encapsulation area by 4mm and inside 5.4 mm.

Example 5

The difference from embodiment 1 is that two first holes and two second holes are included, and the two first holes and the two second holes are respectively connected by two wires.

Results and conclusions:

in the embodiment 1, macroscopic corrosion points begin to appear after the edge sealing of the aluminum-plastic film is carried out for 15 hours, and no new corrosion points are added after 48 hours; in the embodiment 2, macroscopic corrosion points begin to appear after the edge sealing of the aluminum-plastic film is carried out for 24 hours, and no new corrosion points are added after 60 hours; in the comparative example 1, macroscopic corrosion spots begin to appear after the edge sealing of the aluminum-plastic film is carried out for 48 hours, and new corrosion spots appear after 6 days; in the embodiment 3, macroscopic corrosion points appear after the edge sealing of the aluminum-plastic film is carried out for 32 hours, and no new corrosion points are added after 72 hours; in the embodiment 4, macroscopic corrosion points appear after the edge sealing of the aluminum-plastic film is carried out for 12 hours, and no new corrosion points are added after 36 hours; in the comparative example 2, the aluminum-plastic film edge sealing starts to generate macroscopic corrosion spots after 48 hours, and new corrosion spots appear after 5.5 days; in the comparative example 3, macroscopic corrosion spots begin to appear after the aluminum-plastic film edge sealing is carried out for 72 hours, and new corrosion spots appear after 6 days; in the embodiment 5, macroscopic corrosion points begin to appear after the edge sealing of the aluminum-plastic film is carried out for 15 hours, and no new corrosion points are added after 32 hours; furthermore, by combining the samples of the examples 1 to 5 and the samples of the comparative examples 1 to 3, the aluminum-plastic film seal of any one of the cells of the examples 1 to 5 includes all the corrosion points appearing in the samples of the comparative examples 1 to 3.

In summary, the ratio of the aperture of the first hole to the diameter of the metal wire, the corrosion temperature, and the position of the second hole all affect the efficiency of finding the corrosion point, and the method for finding the corrosion point of the soft package poor insulation cell according to the embodiment of the invention can quickly find the corrosion point within one week (usually 1 to 3 days) without an external high voltage power supply.

In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. In addition, in the present invention, unless otherwise explicitly specified or limited, the terms "connected" and "connected" should be interpreted broadly, e.g., as a fixed connection, a detachable connection, or an integral part; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.