Lithium battery cover assembly

Abstract

The lithium battery cover assembly comprises a top cover, an anti-explosion piece, an insulating washer, a pore plate and a sealing ring, the anti-explosion piece is provided with a bending part, an annular scribed line is arranged on the inner side of the bending part, the insulating washer is provided with a wrapping part and a first extending part, the wrapping part wraps the bending part of the anti-explosion piece and the outer edge of the pore plate, and the first extending part is arranged on the outer edge of the pore plate. The first extending part is located between the anti-explosion piece and the pore plate, and a second extending part is arranged at the bottom of the sealing ring. According to the utility model, the hole plate and the bending part of the anti-explosion sheet are coated through the insulating washer structure, and an enough gap is formed between the insulating washer structure and the sealing ring, so that the area of the pressure relief through hole of the cover assembly is increased to the greatest extent under the condition that interference does not occur after sealing, the top pressure relief rate during thermal runaway of the battery cell is improved, and the safety performance of the battery cell is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium batteries, in particular to a lithium battery cover assembly. Background Art

[0002] The current cylindrical lithium battery has the advantages of high operating voltage, high energy density, long cycle life, low self-discharge rate, and small monomer volume, and is rapidly applied and developed. During the assembly and sealing process of cylindrical lithium batteries, the sealing ring of the combination cap is squeezed and deformed to ensure the sealing of the battery to prevent leakage or direct contact with the outside world.

[0003] The cover assembly of the lithium battery is equipped with an explosion-proof valve. When the internal pressure of the battery cell reaches the threshold of the explosion-proof valve, the explosion-proof valve opens to release pressure, and the pressure relief rate is directly related to the area of ​​the pressure relief hole of the cover assembly. Under the conventional cover assembly structure, the edge of the orifice plate exceeds the bending part of the explosion-proof plate. In order to avoid interference with the sealing ring, the outer diameter of the pressure relief hole of the orifice plate and the diameter of the explosion-proof line are restricted; for example, the outer diameter of the pressure relief hole of the orifice plate and the diameter of the explosion-proof line of the 21700 cylindrical battery cell in the conventional structure are difficult to exceed 11mm, resulting in the overall pressure relief hole area of ​​the cover assembly being limited, and the pressure relief rate is insufficient when the battery cell has thermal runaway, which may cause the side wall of the outer shell to rupture. Therefore, the present application proposes a lithium battery cover assembly structure for increasing the top pressure relief rate when the battery cell has thermal runaway, thereby improving the safety performance of the battery cell. Utility Model Content

[0004] The purpose of the utility model is to overcome the shortcomings of the prior art and provide a lithium battery cover assembly.

[0005] The purpose of the utility model is achieved through the following technical solutions: a lithium battery cover assembly, comprising a top cover, an explosion-proof piece, an insulating gasket, a orifice plate and a sealing ring, the explosion-proof piece is provided with a bending portion, the inner side of the bending portion is provided with an annular score line, the insulating gasket has a covering portion and a first extension portion, the covering portion covers the bending portion of the explosion-proof piece and the outer edge of the orifice plate, the first extension portion is located between the explosion-proof piece and the orifice plate, and the bottom of the sealing ring is provided with a second extension portion.

[0006] A further technical solution is that edge-wrapped welding areas are provided on both sides of the top cover.

[0007] A further technical solution is that the insulating gasket is formed by injection molding of plastic particles, and the cross section of the insulating gasket is T-shaped.

[0008] A further technical solution is that the orifice plate is formed by metal stamping and is provided with through holes.

[0009] A further technical solution is that the sealing ring is formed by injection molding of plastic particles, and the second extension portion is a support extending inwardly.

[0010] The utility model has the following advantages:

[0011] (1) The utility model designs the covering portion and the first extension portion through the insulating gasket, thereby covering the orifice plate and the bending portion of the explosion-proof plate, and having a sufficient gap between the sealing ring, so that there will be no interference after sealing, and the pressure relief hole area of ​​the cover assembly is increased to the greatest extent, thereby increasing the top pressure relief rate when the battery cell is thermally runaway, and improving the safety performance of the battery cell.

[0012] (2) The utility model realizes covering of the orifice plate by designing the second extension part of the sealing ring, so that the orifice plate after being broken will not move to contact the steel shell or damage the pole group, which is safer. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is an exploded view of the cover assembly of the utility model;

[0014] Figure 2 It is a cross-sectional view of the cover assembly of the utility model;

[0015] Figure 3 It is a partial cross-sectional view of the cover assembly of the utility model.

[0016] In the figure, 1, top cover; 2, explosion-proof plate; 3, insulating gasket; 4, orifice plate; 5, sealing ring; 6, edge welding area; 7, bending part; 8, engraved line; 9, covering part; 10, first extension part; 11, through hole; 12, second extension part. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0019] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features thereof may be combined with each other.

[0020] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0021] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the utility model product is usually placed when in use, or the positions or positional relationships commonly understood by those skilled in the art, which are only for the convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0022] like Figures 1 to 3 As shown, a lithium battery cover assembly includes a top cover 1, an explosion-proof disc 2, an insulating gasket 3, an orifice plate 4 and a sealing ring 5, the explosion-proof disc 2 is provided with a bending portion 7, the inner side of the bending portion 7 is provided with an annular score line 8, the insulating gasket 3 has a covering portion 9 and a first extension portion 10, the covering portion 9 covers the bending portion 7 of the explosion-proof disc 2 and the outer edge of the orifice plate 4, the first extension portion 10 is located between the explosion-proof disc 2 and the orifice plate 4, and the bottom of the sealing ring 5 is provided with a second extension portion 12.

[0023] The top cover 1 is made of a metal with a large yield strength and a small resistance to meet the requirements of PACK welding and a large current path, and has a through-hole design at the stretching part, which meets the requirements of explosion-proof pressure relief without affecting welding.

[0024] The explosion-proof disc 2 is made of metal stamping, and is provided with a bending portion 7 to enhance the overall strength and prevent deformation during sealing. The bending portion 7 is provided with an annular score line 8 inwardly, and the thickness at the score line 8 is smaller than that at other positions to ensure that the rupture and pressure relief can be achieved when the internal pressure of the battery is too high. The explosion-proof disc 2 bulges downward inwardly of the score line 8, and when the internal pressure is too high, the bulge deforms upward, disconnects from the orifice plate 4, and completes power failure. The total height of the bulge is designed to be 0-0.20 mm, which can increase the longitudinal space of the battery.

[0025] The insulating gasket 3 is made of injection-molded plastic particles and should have insulation and high resistance to thermal deformation to ensure that the combined cap can cut off the power after the explosion-proof aluminum sheet is deformed due to internal pressure, and will not fail due to thermal deformation when the battery has thermal runaway.

[0026] The insulating gasket 3 is characterized by a "T"-shaped cross section, which has a covering portion 9 and an extension portion, wherein the covering portion 9 covers the bending portion 7 of the explosion-proof disc 2 and the outer edge of the orifice plate 4, and the extension portion is located between the explosion-proof disc 2 and the orifice plate 4. The "T"-shaped isolation ring not only meets the insulation requirements between the explosion-proof disc 2 and the orifice plate 4, but also minimizes the space occupation, saving space for the score line 8 of the explosion-proof disc 2 and the through hole 11 of the orifice plate 4.

[0027] The orifice plate 4 is formed by metal stamping, and a through hole 11 is provided on the orifice plate 4. The center position and the raised center bottom of the orifice plate 4 can be connected together by welding. The thickness of the welding area is adjustable to meet the needs of different power-off pressures. Sufficient space should be reserved between the welding area with the explosion-proof valve and the exhaust hole to meet the needs of pole ear welding.

[0028] The sealing ring 5 is formed by injection molding of plastic particles, and an inwardly extending support platform should be provided at the bottom thereof to ensure that the broken orifice plate 4 will not move to contact the steel shell or damage the pole group.

[0029] Optionally, because the sealing ring 5 will not be deformed after sealing, the bottom can be in contact with the positive electrode insulating pad in a flat surface, and the sealing height can be adjusted to allow the sealing ring 5 to press the core without damaging it, thereby preventing the battery core from loosening or other abnormalities in a high vibration environment.

[0030] Optionally, the outer diameter of the positive electrode protection assembly cap may be between 10 mm and 60 mm, and the shell size thereof varies with the change of the outer diameter of the assembly cap.

[0031] In this embodiment, the top cover 1 is stamped and formed using a 0.4-0.8mm thick cold-rolled steel plate, and is electroplated with nickel to increase its corrosion resistance. The top cover 1 is provided with three through holes, with an inner diameter of 5-10mm and an outer diameter of 12-16mm. The explosion-proof disc 2 is stamped and formed using a 0.2-0.5mm aluminum or aluminum alloy plate, and the diameter of the explosion-proof scale line 8 is ≥12mm. The orifice plate 4 is stamped and formed using a 0.4-0.8mm aluminum or aluminum alloy plate, and the orifice plate 4 is provided with 3-5 through holes 11, with an inner diameter of 8-10mm and an outer diameter equal to the diameter of the explosion-proof scale line 8. The insulating gasket 3 is injection molded using high temperature resistant plastics such as PBT or PFA, with a thickness of 0.2-0.4mm and a "T"-shaped cross section. The sealing ring 5 is injection molded using plastics such as PP or PBT.

[0032] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A lithium battery cover assembly, comprising a top cover (1), an explosion-proof disk (2), an insulating gasket (3), an orifice plate (4) and a sealing ring (5), characterized in that: The explosion-proof disc (2) is provided with a bent portion (7), the inner side of which is provided with an annular score line (8), the insulating gasket (3) has a covering portion (9) and a first extension portion (10), the covering portion (9) covers the bent portion (7) of the explosion-proof disc (2) and the outer edge of the orifice plate (4), the first extension portion (10) is located between the explosion-proof disc (2) and the orifice plate (4), and the bottom of the sealing ring (5) is provided with a second extension portion (12).

2. A lithium battery cover assembly according to claim 1, characterized in that: Edge-wrapped welding areas (6) are provided on both sides of the top cover (1).

3. A lithium battery cover assembly according to claim 1, characterized in that: The insulating gasket (3) is formed by injection molding of plastic particles, and the cross section of the insulating gasket (3) is T-shaped.

4. A lithium battery cover assembly according to claim 1, characterized in that: The orifice plate (4) is formed by stamping metal, and a through hole (11) is provided on the orifice plate (4).

5. A lithium battery cover assembly according to claim 1, characterized in that: The sealing ring (5) is formed by injection molding of plastic particles, and the second extension portion (12) is a support platform extending inwardly.

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