Temperature sensing pressure release valve structure of cylindrical power battery and cylindrical power battery

Abstract

The invention provides a temperature-sensing pressure release valve structure of a cylindrical power battery and the cylindrical power battery, and belongs to the technical field of batteries, aiming at solving the problems that a pressure release structure in an existing cylindrical power battery cannot release pressure in time and is relatively low in sensitivity. The temperature sensing pressure release valve structure of the cylindrical power battery comprises a pressure release part, nick grooves are formed in the corresponding positions of the surface, facing the outer side of the metal shell, of the pressure relief part or the surfaces of the two sides of the pressure relief part at the same time; the pressure relief part is further provided with a hollow pressure relief groove from the surface, facing the outer side of the metal shell, of the pressure relief part. And the hollow pressure relief groove is filled with a sealing resin layer. By arranging the nick groove and matching the hollowed-out pressure relief groove and the resin sealing layer, dual pressure relief safeguard measures are taken, the safety of the explosion-proof valve when the internal pressure is increased when the high temperature inside the battery is abnormal is considered, the high-temperature pressure relief sensitivity when the high temperature of the shell is abnormal is also considered, the safety of the battery is ensured, and the service life of the battery is prolonged. And the safety risk that the nick of the explosion-proof valve is opened by internal pressure is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a temperature-sensitive pressure relief valve structure of a cylindrical power battery and the cylindrical power battery. Background Art

[0002] At present, lithium-ion / sodium-ion cylindrical power batteries have gradually become mainstream products in the new energy industry due to their high energy density, good capacity consistency, and ability to support high-rate charge and discharge. While more and more battery manufacturers continue to improve the energy density of cylindrical batteries, they are also continuously pursuing their high safety.

[0003] Common problems in the manufacturing or use of lithium-ion / sodium-ion cylindrical power batteries are as follows:

[0004] 1. Generally, cylindrical power batteries give priority to resistance welding or penetration welding of the shell bottom, so the pressure relief valve can only be set on the top cover. In addition, thin and long cylindrical power batteries can only be equipped with a smaller pressure relief valve. When the battery is short-circuited or stored at high temperature, the valve cannot be opened in time to release the pressure, which is prone to explosion problems and brings safety risks to customers.

[0005] 2. The cylindrical power battery ternary system generally prefers a steel shell structure, which is not easy to deform when the abnormal internal pressure inside the battery increases. However, due to the hardness of the steel material, the explosion-proof valve opening pressure is generally high, and the valve opening consistency is poor (low sensitivity), which brings safety risks to the battery;

[0006] 3. New energy vehicles often catch fire after a collision. The explosion-proof valves of the batteries around the high-temperature baking module only open when they sense the internal pressure of the battery, causing the battery to explode and endanger the personal safety of the car owner. Summary of the invention

[0007] In order to solve the problem that the pressure relief structure in the existing cylindrical power battery cannot relieve pressure in time and has low sensitivity, the present invention provides a temperature-sensitive pressure relief valve structure of a cylindrical power battery and a cylindrical power battery. By setting a notched groove and coordinating a hollow pressure relief groove and a resin sealing layer, double pressure relief protection measures are taken, which not only take into account the safety of the explosion-proof valve when the internal pressure increases when the temperature inside the battery is abnormally high, but also take into account the high-temperature pressure relief sensitivity when the temperature of the shell is abnormal, thereby ensuring the safety of the battery and avoiding the safety risk of relying solely on the internal pressure to open the notch of the explosion-proof valve.

[0008] The technical solution adopted by the present invention is:

[0009] A temperature-sensitive pressure relief valve structure for a cylindrical power battery comprises a pressure relief portion; the pressure relief portion is located at the bottom of a metal shell of the cylindrical power battery and is a part of the metal shell, or the pressure relief portion is an independent metal plate and is welded to the metal shell as a whole; the surface of the pressure relief portion facing the outside of the metal shell or the corresponding positions of the two side surfaces are simultaneously provided with notched grooves; the pressure relief portion is also provided with a hollow pressure relief groove starting from the surface of the pressure relief portion facing the outside of the metal shell; the hollow pressure relief groove is filled with a sealing resin layer.

[0010] Furthermore, along the groove width direction of the notched groove, the cross section is U-shaped or V-shaped.

[0011] Furthermore, the thickness T of the pressure relief portion and the groove depth H of the notched groove satisfy: TH=0.03~0.08mm.

[0012] Furthermore, the notched groove and the hollow pressure relief groove are both arc-shaped, and the centers of the two circles coincide.

[0013] Furthermore, the curvature of the notched groove is 325°~350°, and the curvature of the hollow pressure relief groove is 325°~350°.

[0014] Furthermore, the curvature of the hollow pressure relief groove is the same as the curvature of the notched groove, and the starting point and the end point of the arc length direction corresponding to the two are respectively in the same diameter direction.

[0015] Furthermore, the radius of the hollow pressure relief groove is larger than the radius of the scored groove.

[0016] Furthermore, a surface of the resin sealing layer facing the outer side of the metal shell is a U-shaped or V-shaped concave surface, or both the upper and lower surfaces of the resin sealing layer are U-shaped or V-shaped concave surfaces.

[0017] Furthermore, the main material of the resin sealing layer is PPS, PP, PVC or PET.

[0018] Based on the same inventive concept, the present invention also provides a cylindrical power battery, including the temperature-sensitive pressure relief valve structure of the cylindrical power battery as described above.

[0019] The beneficial effects of the present invention are:

[0020] In the present invention, a double pressure relief protection measure is adopted by providing a notched groove and cooperating with a hollow pressure relief groove and a resin sealing layer, which not only takes into account the safety of the explosion-proof valve when the internal pressure increases when the temperature inside the battery is abnormally high, but also takes into account the high-temperature pressure relief sensitivity when the temperature of the shell is abnormally high, thereby ensuring the safety of the battery and avoiding the safety risk of relying solely on the internal pressure to open the notch of the explosion-proof valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 Schematic diagram of the three-dimensional structure of the metal shell of the cylindrical power battery in the embodiment.

[0023] Figure 2 It is a front view of the temperature-sensitive pressure relief valve structure of the cylindrical power battery in the embodiment.

[0024] Figure 3 for Figure 2 AA section view.

[0025] Figure 4 It is a schematic diagram of the state of the temperature-sensitive pressure relief valve structure of the cylindrical power battery in the embodiment when it is releasing pressure.

[0026] The accompanying drawings are marked as follows:

[0027] 100 - pressure relief portion, 110 - notched groove, 120 - hollow pressure relief groove, 130 - resin sealing layer. DETAILED DESCRIPTION

[0028] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0029] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention.

[0030] The embodiments of the invention are described in detail below with reference to the accompanying drawings.

[0031] Figure 1 Schematic diagram of the three-dimensional structure of the metal shell of the cylindrical power battery in the embodiment. Figure 2Schematic diagram of the temperature-sensitive pressure relief valve structure of the cylindrical power battery in the embodiment. Figure 3 for Figure 2 AA section view. Figure 1~Figure 3 As shown in the figure, the temperature-sensitive pressure relief valve structure of the cylindrical power battery includes a pressure relief portion 100, which is located at the bottom of the metal shell of the cylindrical power battery and is a part of the metal shell, or the pressure relief portion 100 is an independent metal plate made of the same material as the metal shell and is welded to the metal shell as a whole. Figure 2 and Figure 3 As an example, the pressure relief portion 100 shown in the figure is located at the bottom of the metal shell of the cylindrical power battery, which is a circular plate-shaped protruding portion at the bottom of the metal shell. Figure 2 The circular arc-shaped notched groove 110 is punched out by stamping with the point B of the cylindrical power battery as the center, that is, the thickness at the notched groove 110 is smaller than the thickness at other positions of the pressure relief part 100, forming a weak area. For example, the thickness T of the pressure relief part 100 and the groove depth H of the notched groove 110 satisfy: TH=0.03~0.08mm; along the groove width direction of the notched groove 110, the cross section of the notched groove 110 is U-shaped or V-shaped. When the internal pressure of the cylindrical power battery exceeds the threshold, the pressure relief part 100 opens to release pressure from the notched groove 110 to avoid explosion. It should be noted that, in this embodiment, arc-shaped notched grooves 110 may be simultaneously provided on both side surfaces of the pressure relief portion 100 with its own geometric center as the center of the circle, and the radius of the notched grooves 110 simultaneously provided on both side surfaces of the pressure relief portion 100 is the same. When the notched grooves 110 are provided on both sides at the same time, the thickness T of the pressure relief portion 100 and the groove depth H of the notched grooves 110 satisfy: TH=0.03~0.08mm, wherein the groove depth H is the sum of the groove depths on both sides.

[0032] like Figure 2 and Figure 3 As shown in , the arc of the notched groove 110 in this embodiment is 325°~350°, that is, the valve opening angle is 10°~35°. On the one hand, the notched groove 110 has a large arc to ensure that the pressure relief part 100 can be directed outward to release pressure, and the opening generated after the pressure relief part 100 is opened is roughly circular, which ensures that the cylindrical power battery has sufficient pressure relief area and improves the safety of the cylindrical power battery; on the other hand, under the same valve opening area, the circumference of the notched groove 110, which is roughly circular, is smaller than that of the square and triangle, and has a relatively small impact on the strength of the metal shell, making the strength of the metal shell relatively large. Further, in this embodiment, the area of ​​the whole circle surrounded by the notched groove 110 is 50% or more of the area of ​​the pressure relief part 100, so that the area surrounded by the notched groove 110 has a larger area; when the internal pressure of the cylindrical power battery exceeds the threshold, the larger area is conducive to tearing the notched groove 110 to open the pressure relief and avoid explosion.

[0033] like Figure 2 and Figure 3 As shown in FIG. 1 , the pressure relief portion 100 is formed from a side facing the outside of the metal shell along its thickness direction with its geometric center ( Figure 2 An arc-shaped hollow pressure relief groove 120 is opened with point B of the hollow pressure relief groove 120 as the center, and the center of the hollow pressure relief groove 120 coincides with the center of the scored groove 110; at the same time, a resin sealing layer 130 is filled in the hollow pressure relief groove 120 to seal the hollow pressure relief groove 120. When the temperature inside and outside the cylindrical power battery is too high, the resin sealing layer 130 melts and fails at high temperature, making the inside and outside of the metal shell conductive and pressure-relieving, thus avoiding the common fire and explosion accidents after collisions of new energy vehicles; when the pressure inside the cylindrical power battery is too high and the notch groove 110 fails (i.e., affected by the material of the metal shell, such as a steel shell, the notch groove 110 fails to open normally to release pressure), compared with the metal shell as a whole, the resin sealing layer 130 and the hollow pressure relief groove 120 are physically combined, and the sharp increase in pressure inside the cylindrical power battery can destroy the physical combination interface between the resin sealing layer 130 and the hollow pressure relief groove 120, and the glass of the resin sealing layer 130 falls off, making the inside and outside of the metal shell conductive and pressure-relieving, thus avoiding explosions. In this embodiment, the main material of the resin sealing layer 130 can be PPS (polyphenylene sulfide), PP (polypropylene), PVC (polyvinyl chloride), PET (polyester resin), etc. The melting point range of PPS is 280℃~300℃, the melting point range of PP is 148℃~176℃, the melting point range of PVC is 150℃~200℃, and the melting point range of PET is 140℃~150℃. Therefore, resin sealing layers 130 with different melting points can be selected according to different models or sizes of cylindrical power batteries to adapt to actual conditions.

[0034] In this embodiment, by setting the notched groove and cooperating with the hollow pressure relief groove and the resin sealing layer, the double pressure relief protection measures are applicable to the scenario where the pressure inside the cylindrical power battery exceeds the limit and / or the temperature is too high, reducing the influence of the metal shell material, improving the valve opening sensitivity, and ensuring the safety of the cylindrical power battery. The temperature-sensitive pressure relief valve structure of the cylindrical power battery in this embodiment takes into account the safety of the explosion-proof valve when the internal pressure increases when the temperature inside the battery is abnormal, and also takes into account the high-temperature pressure relief sensitivity when the temperature of the shell is abnormal, ensuring the safety of the battery and avoiding the safety risk of relying solely on the internal pressure to open the notch of the explosion-proof valve.

[0035] As 2 and Figure 3As shown in , the curvature of the hollow pressure relief groove 120 is 325°~350°, and is the same as the curvature of the notched groove 110; the starting point and end point of the arc length direction of the hollow pressure relief groove 120 and the corresponding starting point and end point of the arc length direction of the notched groove 110 are respectively in the same diameter direction. Therefore, on the one hand, the curvature of the hollow pressure relief groove 120 has a longer curvature, and the pressure relief size is relatively large under the same radius; on the one hand, the arrangement of the hollow pressure relief groove 120 and the notched groove 110 is similar, which can reduce the impact on the structural strength of the bottom of the metal shell; on the other hand, under the same arrangement of the hollow pressure relief groove 120 and the notched groove 110, the direction of opening the pressure relief is the same, and there will be no interference between each other. At the same time, the radius of the hollow pressure relief groove 120 is larger than that of the notched groove 110; preferably, the radius of the hollow pressure relief groove 120 is 1.05~1.3 times the radius of the notched groove 110, and the positions of the hollow pressure relief groove 120 and the notched groove 110 are relatively close. Figure 4 Schematic diagram of the state of the temperature-sensitive pressure relief valve structure of the cylindrical power battery in the embodiment when it is releasing pressure. Figure 4 As shown in , when the internal pressure of the cylindrical power battery increases, the area surrounded by the notch groove 110 will gradually arch and protrude toward the outside of the metal shell, and synchronously drive the area between the notch groove 110 and the hollow pressure relief groove 120 to protrude and deform. In this process, the distance between the notches of the notch groove 110 (points P1 and P2 in the figure) will increase, and the distance between the notches of the hollow pressure relief groove 120 (points P3 and P4 in the figure) will decrease. Therefore, on the one hand, the hollow pressure relief groove 120 can provide a space for avoiding deformation to increase the distance between the notches of the notch groove 110, which is conducive to the tearing and opening of the notch groove 110 under the pressure inside the cylindrical power battery, and further improves the sensitivity of valve opening; on the other hand, the main material of the resin sealing layer 130 filled in the hollow pressure relief groove 120 is a high molecular polymer, and its hardness is much lower than that of the metal shell. When ensuring the sealing performance under normal conditions, it does not affect the deformation and tearing opening process of the notch groove 110.

[0036] like Figure 2 and Figure 3 As shown in , in this embodiment, the thickness t (minimum value of the filling thickness) of the resin sealing layer 130 is less than or equal to the thickness T of the pressure relief portion 100; at the same time, the side of the resin sealing layer 130 facing the outside of the metal shell is a U-shaped or V-shaped concave surface, or the upper and lower surfaces of the resin sealing layer 130 are both U-shaped or V-shaped concave surfaces. Therefore, in this embodiment, by changing the morphology of the surface layer of the resin sealing layer 130, the contact area with the environment outside the metal shell can be improved to improve the temperature-sensitive pressure relief characteristics; at the same time, the upper surface of the resin sealing layer 130 is a U-shaped or V-shaped concave surface, which can provide appropriate deformation transfer space for the deformation and tearing of the notch groove 110, further improving the valve opening sensitivity.

Claims

1. A temperature-sensitive pressure relief valve structure for a cylindrical power battery, characterized in that: It includes a pressure relief part; the pressure relief part is located at the bottom of the metal shell of the cylindrical power battery and is a part of the metal shell, or the pressure relief part is an independent metal plate and is welded to the metal shell as a whole; the surface of the pressure relief part facing the outside of the metal shell or the corresponding positions of the two side surfaces are simultaneously provided with notched grooves; starting from the surface of the pressure relief part facing the outside of the metal shell, the pressure relief part is also provided with a hollow pressure relief groove; the hollow pressure relief groove is filled with a sealing resin layer.

2. The temperature-sensitive pressure relief valve structure of a cylindrical power battery according to claim 1, characterized in that: Along the groove width direction of the notched groove, the cross section is U-shaped or V-shaped.

3. The temperature-sensitive pressure relief valve structure of a cylindrical power battery according to claim 1, characterized in that: The thickness T of the pressure relief portion and the depth H of the notched groove satisfy: TH=0.03~0.08mm.

4. The temperature-sensitive pressure relief valve structure of a cylindrical power battery according to claim 1, characterized in that: The notched groove and the hollow pressure relief groove are both arc-shaped, and the centers of the two circles coincide.

5. The temperature-sensitive pressure relief valve structure of a cylindrical power battery according to claim 4, characterized in that: The curvature of the notched groove is 325°~350°, and the curvature of the hollow pressure relief groove is 325°~350°.

6. The temperature-sensitive pressure relief valve structure of a cylindrical power battery according to claim 4 or 5, characterized in that: The curvature of the hollow pressure relief groove is the same as that of the notched groove, and the starting point and the end point of the arc length direction corresponding to the two are respectively in the same diameter direction.

7. The temperature-sensitive pressure relief valve structure of a cylindrical power battery according to claim 6, characterized in that: The radius of the hollow pressure relief groove is larger than the radius of the scored groove.

8. The temperature-sensitive pressure relief valve structure of a cylindrical power battery according to any one of claims 1 to 5 and 7, characterized in that: The surface of the resin sealing layer facing the outer side of the metal shell is a U-shaped or V-shaped concave surface, or the upper and lower surfaces of the resin sealing layer are both U-shaped or V-shaped concave surfaces.

9. The temperature-sensitive pressure relief valve structure of a cylindrical power battery according to any one of claims 1 to 5 and 7, characterized in that: The main material of the resin sealing layer is PPS, PP, PVC or PET.

10. A cylindrical power battery, characterized in that: A temperature-sensitive pressure relief valve structure for a cylindrical power battery comprising any one of claims 1 to 9.

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