Explosion-proof valve plate for power battery and its preparation method

Abstract

This invention discloses an explosion-proof valve plate for a power battery, comprising a steel sheet and a copper sheet stacked inside the steel sheet, the steel sheet and copper sheet being integrally formed. The explosion-proof valve plate also has explosion-proof markings, including a first marking and a second marking. Both the first and second markings have a groove-shaped cross-section. The first marking extends from the outer surface of the steel sheet to the inner surface without penetrating the steel sheet. The second marking extends from the bottom of the first marking towards the inner surface of the copper sheet without penetrating the copper sheet. The distance between the bottom of the second marking and the inner surface of the copper sheet is greater than or equal to 0.03 mm and less than 0.08 mm. This invention, by placing a copper sheet at the bottom of the steel sheet, combining the harder steel with the softer copper and incorporating the first and second markings, balances the structural strength of the explosion-proof valve plate with its precision, improves valve opening sensitivity, ensures the safety of the power battery, and avoids the leakage risk associated with simply thinning the markings on the explosion-proof valve plate.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicles, and in particular to an explosion-proof valve plate for a power battery and its preparation method. Background Technology

[0002] Currently, lithium-ion or sodium-ion power batteries are gradually becoming mainstream products in the new energy industry due to their advantages such as high energy density, good capacity consistency, and ability to support high-rate charging and discharging. Conventional power battery structures generally only have one electrolyte filling hole, and their common problems are:

[0003] 1. Cylindrical power batteries with a ternary system generally prefer a steel shell structure, which is less prone to deformation when the internal pressure of the battery increases abnormally. However, due to the hardness of the steel material, the opening pressure of the explosion-proof valve is generally high and the opening consistency is poor, which brings safety risks to the battery.

[0004] 2. A few manufacturers have attempted to reduce the opening pressure by scoring and thinning the steel explosion-proof valve, which has resulted in a significant weakening of the structural strength and a risk of leakage after vibration and impact. Summary of the Invention

[0005] The purpose of this invention is to provide an explosion-proof valve plate for a power battery and its preparation method, so as to solve the problems of poor valve opening consistency and leakage in the prior art.

[0006] To achieve the above objectives, the present invention provides an explosion-proof valve plate for a power battery, comprising a steel sheet and a copper sheet stacked on the inner side of the steel sheet, wherein the steel sheet and the copper sheet are integrally formed. The explosion-proof valve plate is further provided with explosion-proof markings, including a first marking and a second marking. The cross-section of the first marking and the second marking is groove-shaped. The first marking extends from the outer surface of the steel sheet to the inner side of the steel sheet without penetrating the steel sheet. The second marking extends from the bottom of the first marking to the inner side of the copper sheet without penetrating the copper sheet. The distance between the bottom of the second marking and the inner surface of the copper sheet is greater than or equal to 0.03 mm and less than 0.08 mm.

[0007] Preferably, both the first and second engravings are arc-shaped structures, and the central angle of each arc-shaped structure is greater than or equal to 325 degrees and less than or equal to 350 degrees.

[0008] Preferably, the distance between the bottom of the first notch and the inner side of the steel sheet is greater than or equal to 0.05 mm and less than or equal to 0.15 mm, and the thickness of the copper sheet is greater than or equal to 0.08 mm and less than or equal to 0.2 mm.

[0009] Preferably, the cross-sections of both the first and second notches are U-shaped or V-shaped.

[0010] The present invention also provides a method for preparing an explosion-proof valve plate for a power battery, comprising the following steps: providing a steel sheet, forming a first groove on the steel sheet, the first groove having a groove-shaped cross-section, the first groove extending from the outer surface of the steel sheet to the inner surface of the steel sheet without penetrating the steel sheet; providing a copper sheet, and bonding the copper sheet to the inner surface of the steel sheet; forming a second groove at the bottom of the first groove, the second groove having a groove-shaped cross-section, the second groove extending towards the inner surface of the copper sheet without penetrating the copper sheet, the distance between the bottom of the second groove and the inner surface of the copper sheet being greater than or equal to 0.03 mm and less than 0.08 mm.

[0011] Preferably, both the first and second engravings are arc-shaped structures, and the central angle of each arc-shaped structure is greater than or equal to 325 degrees and less than or equal to 350 degrees.

[0012] Preferably, the first notch is formed by a first stamping process, and the second notch is formed by a second stamping process.

[0013] Preferably, the distance between the bottom of the first notch and the inner side surface of the steel sheet is greater than or equal to 0.05 mm and less than or equal to 0.15 mm.

[0014] Preferably, in the step of providing the copper sheet, the thickness of the copper sheet is greater than or equal to 0.08 mm and less than or equal to 0.2 mm.

[0015] Preferably, the cross-sections of both the first and second notches are U-shaped or V-shaped.

[0016] Compared with existing technologies, this invention sets a copper sheet at the bottom of the steel sheet, combining the harder steel and the softer copper material together and setting a first and a second notch. This approach balances the structural strength of the explosion-proof valve plate with its precision, improving the valve opening sensitivity. It solves the problem of low valve opening sensitivity in pure steel explosion-proof valve plates and improves the consistency of valve opening in steel-shell power battery explosion-proof valve plates, ensuring the safety of the power battery and avoiding the leakage risk caused by simply thinning the explosion-proof valve plate notch. Attached Figure Description

[0017] Figure 1 This is a structural diagram of the explosion-proof valve plate and the power battery casing after welding in an embodiment of the present invention.

[0018] Figure 2 This is a structural diagram of the explosion-proof valve plate at one angle in an embodiment of the present invention.

[0019] Figure 3 This is a structural diagram of the explosion-proof valve plate from another angle in an embodiment of the present invention.

[0020] Figure 4 This is a cross-sectional view of the explosion-proof valve plate in an embodiment of the present invention, in which no second notch is provided.

[0021] Figure 5 for Figure 4 Enlarged view of point A in the middle.

[0022] Figure 6 This is a cross-sectional view of the explosion-proof valve plate in an embodiment of the present invention, where a second notch has been provided. Detailed Implementation

[0023] To illustrate the technical content, structural features, and effects of the present invention in detail, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0024] like Figures 1 to 6 As shown, this embodiment of the invention provides an explosion-proof valve plate 1 for a power battery, including a steel sheet 11 and a copper sheet 12 stacked inside the steel sheet 11. The steel sheet 11 and the copper sheet 12 are integrated into one piece. The explosion-proof valve plate 1 is also provided with explosion-proof markings 13. The explosion-proof markings 13 include a first marking 131 and a second marking 132. The cross-section of the first marking 131 and the second marking 132 is groove-shaped. The first marking 131 extends from the outer surface of the steel sheet 11 to the inner surface of the steel sheet 11 without penetrating the steel sheet 11. The second marking 132 extends from the bottom of the first marking 131 to the inner surface of the copper sheet 12 without penetrating the copper sheet 12. The distance t between the bottom of the second marking 132 and the inner surface of the copper sheet 12 is greater than or equal to 0.03 mm and less than 0.08 mm. Specifically, the power battery can be a cylindrical power battery, and the explosion-proof valve plate 1 is generally circular. The explosion-proof valve plate 1 of the power battery can be set on the top cover of the battery, or on the bottom of the housing, or on an independent steel plate 11. The steel plate 11 is then welded to the housing with openings at both ends of the power battery. In this embodiment of the invention, as shown... Figure 1 As shown, the explosion-proof valve plate 1 is mounted on an independent steel plate 11 and welded to the housing 2. An injection hole 14 is also provided in the middle of the explosion-proof valve plate 1. A first notch 131 and a second notch 132 are arranged around the injection hole 14. The bottom dimension of the first notch 131 is larger than the top opening dimension of the second notch 132, and the depth of the first notch 131 is greater than the depth of the second notch 132. The distance t between the bottom of the second notch 132 and the inner surface of the copper plate 12 is greater than or equal to 0.03 mm and less than 0.08 mm, ensuring a relatively thick gap between the bottom of the second notch 132 and the inner surface of the copper plate 12, effectively preventing leakage of the power battery. Moreover, the copper plate 12 is softer than the steel plate 11, and with the same thickness, the copper plate 12 is easier to open, resulting in higher valve opening sensitivity.

[0025] This invention, through the placement of a copper sheet 12 at the bottom of the steel sheet 11, combines the relatively hard steel with the relatively soft copper and sets a first notch 131 and a second notch 132. This approach balances the structural strength of the explosion-proof valve plate 1 with its precision, improving valve opening sensitivity. It solves the problem of low valve opening sensitivity in pure steel explosion-proof valve plates 1 and improves the consistency of valve opening in steel-cased power battery explosion-proof valve plates 1, ensuring the safety of the power battery and avoiding the risk of leakage caused by simply thinning the notch of the explosion-proof valve plate 1.

[0026] In this embodiment of the invention, both the first notch 131 and the second notch 132 are arc-shaped structures, and the central angle of each arc structure is greater than or equal to 325 degrees and less than or equal to 350 degrees. Specifically, for example... Figure 3 As shown, the central angle α of the part without explosion-proof markings 13 is greater than or equal to 10 degrees and less than or equal to 35 degrees. The sum of the central angle of the arc structure and the central angle α of the part without explosion-proof markings 13 is 360 degrees. Adjusting the central angle of the arc structure can help fine-tune the structural strength of the explosion-proof valve plate 1.

[0027] In embodiments of the present invention, such as Figures 4 to 5 As shown, the distance T1 between the bottom of the first notch 131 and the inner side of the steel sheet 11 is greater than or equal to 0.05 mm and less than or equal to 0.15 mm; the thickness T2 of the copper sheet 12 is greater than or equal to 0.08 mm and less than or equal to 0.2 mm; and the distance t between the bottom of the second notch 132 and the inner side of the copper sheet 12 is greater than or equal to 0.03 mm and less than 0.08 mm. Specifically, the thickness of the steel sheet 11 is greater than 0.15 mm and less than or equal to 0.5 mm. The first notch 131 can be formed by a stamping process. The distance T1 between the bottom of the first notch 131 and the inner side of the steel sheet 11 is greater than or equal to 0.05 mm and less than or equal to 0.15 mm, ensuring that the steel sheet 11 has a certain structural strength. Based on the first notch 131, the notch is further corrected by fine stamping to form the second notch 132, ensuring the accuracy of the second notch 132, thereby ensuring the consistency of the opening of the explosion-proof valve plate 1.

[0028] In this embodiment of the invention, the cross-sections of both the first notch 131 and the second notch 132 are U-shaped or V-shaped, specifically, as shown below. Figures 5 to 6 As shown, the cross-sections of both the first notch 131 and the second notch 132 are U-shaped.

[0029] This invention also provides a method for preparing the explosion-proof valve plate 1 for manufacturing the above-mentioned power battery, comprising the following steps:

[0030] S1. A steel sheet 11 is provided, on which a first notch 131 is formed. The cross-section of the first notch 131 is groove-shaped. The first notch 131 extends from the outer surface of the steel sheet 11 to the inner surface of the steel sheet 11 and does not penetrate the steel sheet 11; specifically, as shown... Figures 4 to 5 As shown, the thickness of the steel sheet 11 is greater than 0.15 mm and less than or equal to 0.5 mm. A first notch 131 can be pre-formed on the steel sheet 11. The first notch 131 does not penetrate the steel sheet 11, ensuring that the steel sheet 11 has a certain structural strength.

[0031] S2. Provide a copper sheet 12, and laminate the copper sheet 12 onto the inner surface of the steel sheet 11; specifically, as shown in... Figures 4 to 5 As shown, steel sheet 11 and copper sheet 12 can be formed by copper-steel composite process. Specifically, they can be firmly bonded together by physical metallurgical processes such as hot rolling.

[0032] S3. A second notch 132 is formed at the bottom of the first notch 131. The cross-section of the second notch 132 is groove-shaped. The second notch 132 extends inward toward the copper sheet 12 but does not penetrate the copper sheet 12. The distance t between the bottom of the second notch 132 and the inner surface of the copper sheet 12 is greater than or equal to 0.03 mm and less than 0.08 mm. Specifically, as shown... Figure 6 As shown, the bottom dimension of the first notch 131 is larger than the top opening dimension of the second notch 132, the depth of the first notch 131 is greater than the depth of the second notch 132, and the bottom of the second notch 132 has a thicker gap with the inner side of the copper sheet 12, which effectively prevents leakage of the power battery.

[0033] In this embodiment of the invention, the explosion-proof valve plate 1 of the power battery can be disposed on the top cover of the battery, on the bottom of the housing, or on an independent steel plate 11. The steel plate 11 is then welded to the housing with openings at both ends of the power battery. In this embodiment of the invention, as shown... Figure 1 As shown, the explosion-proof valve plate 1 is mounted on an independent steel plate 11 and welded to the housing 2. The explosion-proof valve plate 1 also has an injection hole 14 in the middle, and the first groove 131 and the second groove 132 are arranged around the injection hole 14.

[0034] In this embodiment of the invention, a first notch 131 is first set on the steel sheet 11 without penetrating it. Then, the steel sheet 11 is combined with the copper sheet 12 and a second notch 132 is set. This method of preparing the explosion-proof valve plate 1 in this embodiment of the invention takes into account both the structural strength of the explosion-proof valve plate 1 and the precision of the explosion-proof valve plate 1, and improves the valve opening sensitivity. It solves the problem of low valve opening sensitivity of the pure steel explosion-proof valve plate 1 with notch, and improves the valve opening consistency of the steel shell power battery explosion-proof valve plate 1, ensuring the safety of the power battery and avoiding the risk of leakage caused by simply thinning the notch of the explosion-proof valve plate 1.

[0035] In this embodiment of the invention, the first notch 131 is formed by a first stamping process, and the second notch 132 is formed by a second stamping process. Specifically, the distance T1 between the bottom of the first notch 131 and the inner side of the steel sheet 11 is greater than or equal to 0.05 mm and less than or equal to 0.15 mm. Therefore, the first notch 131 is relatively deep and can be roughed by the first stamping process. The first stamping process has relatively lower precision requirements. The equipment and stamping dies for the first and second stamping processes are different. The first stamping process is a roughing process, and the second stamping process is a fine stamping process. For example, the first stamping process can use pneumatic equipment and pneumatic dies. Due to factors such as air source fluctuations and high speed, it can only be used for roughing. The second stamping process can use hydraulic equipment, which has stable pressure and slow speed, making it suitable for fine stamping.

[0036] Further, in step S2, the thickness T2 of the copper sheet 12 is greater than or equal to 0.08 mm and less than or equal to 0.2 mm.

[0037] In this embodiment of the invention, the cross-sections of the first notch 131 and the second notch 132 are both U-shaped or V-shaped, which makes it easier to form the first notch 131 and the second notch 132.

[0038] This invention achieves the following by performing pre-marking of the explosion-proof valve, copper-steel composite processing, secondary correction marking, and control of the central angle of the arc structure on the steel sheet 11 of the steel-shell power battery: firstly, stamping a thinner first mark 131 on the steel sheet 11; then, composite processing of the steel sheet 11 and the copper sheet 12; finally, stamping and cutting the copper-steel composite sheet, and performing secondary correction marking at the first mark position to form a second mark 132; controlling the central angle of the arc structure can assist in fine-tuning the structural strength of the explosion-proof valve; and finally... Ultimately, the combination of a harder steel sheet 11 and a softer copper sheet 12 results in the following: the first notch 131 of the steel explosion-proof valve plate 1 takes into account the structural strength of the explosion-proof valve plate 1 during the later stamping process; the second stamping correction notch, namely the second notch 132, ensures the accuracy of the explosion-proof valve plate 1 and improves its valve opening sensitivity. This not only solves the problem of low valve opening sensitivity of pure steel explosion-proof valves, but also improves the valve opening consistency of steel-cased battery explosion-proof valves, ensuring battery safety and avoiding the risk of leakage caused by simply thinning the explosion-proof valve notch.

[0039] The above-disclosed examples are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention shall still fall within the scope of the present invention.

Claims

1. An explosion-proof valve plate for a power battery, characterized in that, The device includes a steel sheet and a copper sheet stacked inside the steel sheet. The thickness of the copper sheet is greater than or equal to 0.08 mm and less than or equal to 0.2 mm. The steel sheet and the copper sheet are integrated into one piece. The explosion-proof valve plate is also provided with explosion-proof markings, including a first marking and a second marking. The cross-section of the first marking and the second marking is groove-shaped. The first marking extends from the outer surface of the steel sheet to the inner surface of the steel sheet without penetrating the steel sheet. The distance between the bottom of the first marking and the inner surface of the steel sheet is greater than or equal to 0.05 mm and less than or equal to 0.15 mm. The second marking extends from the bottom of the first marking towards the inner surface of the copper sheet without penetrating the copper sheet. The distance between the bottom of the second marking and the inner surface of the copper sheet is greater than or equal to 0.03 mm and less than 0.08 mm.

2. The explosion-proof valve plate of the power battery as described in claim 1, characterized in that, Both the first and second engravings are arc-shaped structures, and the central angle of each arc-shaped structure is greater than or equal to 325 degrees and less than or equal to 350 degrees.

3. The explosion-proof valve plate of the power battery as described in claim 1, characterized in that, Both the first and second notches have U-shaped or V-shaped cross sections.

4. A method for preparing an explosion-proof valve plate for a power battery, characterized in that, Includes the following steps: A steel sheet is provided, on which a first notch is formed. The first notch has a groove-shaped cross-section and extends from the outer surface of the steel sheet to the inner surface of the steel sheet without penetrating the steel sheet. The distance between the bottom of the first notch and the inner surface of the steel sheet is greater than or equal to 0.05 mm and less than or equal to 0.15 mm. A copper sheet is provided, the thickness of which is greater than or equal to 0.08 mm and less than or equal to 0.2 mm, and the copper sheet is laminated onto the inner surface of the steel sheet; A second groove is formed at the bottom of the first groove. The cross-section of the second groove is groove-shaped. The second groove extends toward the inside of the copper sheet but does not penetrate the copper sheet. The distance between the bottom of the second groove and the inner side of the copper sheet is greater than or equal to 0.03 mm and less than 0.08 mm.

5. The method for preparing the explosion-proof valve plate of the power battery as described in claim 4, characterized in that, Both the first and second engravings are arc-shaped structures, and the central angle of each arc-shaped structure is greater than or equal to 325 degrees and less than or equal to 350 degrees.

6. The method for preparing the explosion-proof valve plate of the power battery as described in claim 4, characterized in that, The first notch is formed by a first stamping process, and the second notch is formed by a second stamping process.

7. The method for preparing the explosion-proof valve plate of the power battery as described in claim 4, characterized in that, Both the first and second notches have U-shaped or V-shaped cross sections.

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