Secondary battery

Abstract

A secondary battery, comprising a battery cell, a casing internally provided with a chamber, and a cover plate for sealing the casing. The battery cell is accommodated in the chamber; the bottom of the casing protrudes outwards in the direction towards the cover plate to form an explosion-proof chamber, the explosion-proof chamber being internally provided with an explosion-proof device; the explosion-proof chamber comprises a top wall close to the cover plate and a peripheral wall connected to the top wall; the explosion-proof device comprises an explosion-proof valve and a fire retardant, the explosion-proof valve being arranged on the top wall, and the fire retardant being contained in the explosion-proof chamber. Such structure can gather gas generated inside a power battery in the vicinity of the explosion-proof chamber, so as to enable the explosion-proof valve to directionally burst, thus improving the bursting timeliness; after the explosion-proof valve bursts, the fire retardant contained in the explosion-proof chamber can treat rushing heat, sparks, etc. so as to achieve a fire retardation effect, thus preventing spread outside the power battery from affecting an adjacent power battery in a battery module or battery pack.

Description

secondary batteries Technical Field

[0001] The present application relates to the technical field of energy storage devices, and in particular to a secondary battery. Background Art

[0002] Secondary batteries are new, environmentally friendly energy storage components and are currently widely used in energy storage, hybrid vehicles, communications, home appliances, military, aerospace, and other technical fields. However, as electric vehicle technology continues to improve and electric and hybrid vehicles become increasingly commonplace in people's daily lives, the industry is placing higher demands on the safety performance of the secondary batteries that power electric vehicles.

[0003] The battery cells of secondary batteries can usually be of a wound structure or a stacked structure. For the wound structure, a certain amount of space is usually left in the middle after winding to buffer the expansion of the electrode during subsequent battery charging and discharging, alleviate the stress on the wound structure battery cell, and thus improve safety.

[0004] Additionally, secondary batteries generate heat during charging, especially under extreme conditions such as high voltage, overcharging, and fast charging. The growth of lithium dendrites on the graphite negative electrode can cause perforation of the polymer separator. Once the separator loses its blocking function, the direct contact between the positive and negative electrodes causes a short circuit within the battery, generating even more heat, further increasing the internal temperature and triggering a series of unwanted, violent chemical reactions, producing large amounts of flammable gases and potentially causing a fire. Similarly, the electrolyte may also decompose and produce gas due to impurities such as water and metal impurities. Alternatively, the electrolyte may have a low electrochemical window or come into contact with the active surfaces of the positive or negative electrode materials, decomposing to produce low-boiling-point hydrocarbons, esters, ethers, or carbon dioxide.

[0005] Because the cover and casing of secondary batteries are typically characterized by high temperature resistance, tight sealing, and high safety, if the gas inside the battery cannot be released, it can cause explosions and other serious safety accidents. Currently, most battery cover bodies are equipped with explosion-proof valves. When the internal pressure of the battery exceeds a preset value, the explosion-proof valve opens to release the pressure, thus preventing explosion accidents. However, because the gas inside the battery is in a disordered state under high heat and high voltage, it moves throughout the casing. Therefore, the explosion-proof valve installed on the cover is difficult to open in time, which increases safety risks.

[0006] Application Contents

[0007] In response to the above-mentioned issues, the present application aims to provide a secondary battery. The explosion-proof device of the secondary battery of the present application is located in a specific position, which can concentrate the gas in the battery, thereby achieving a directional explosion of the explosion-proof valve. The special structural setting of the explosion-proof device can also provide a flame retardant effect after the explosion of the explosion-proof valve, thereby preventing the spread of heat and sparks to the outside world and affecting the adjacent power batteries in the battery module or battery pack.

[0008] To achieve the above-mentioned purpose, the present application provides a secondary battery, comprising a battery cell, a shell having a cavity therein, and a cover plate for sealing the shell, wherein the battery cell is accommodated in the cavity, and the bottom of the shell bulges outward toward the cover plate to form an explosion-proof cavity, wherein an explosion-proof device is arranged in the explosion-proof cavity, wherein the explosion-proof cavity comprises a top wall close to the cover plate and a peripheral wall connected to the top wall, wherein the explosion-proof device comprises an explosion-proof valve and a fire retardant, wherein the explosion-proof valve is arranged on the top wall, and the fire retardant is accommodated in the explosion-proof cavity.

[0009] In the secondary battery of this application, an explosion-proof chamber is formed at the bottom of the housing, bulging outward toward the cover. An explosion-proof valve is installed on the top wall of the explosion-proof chamber near the cover. This design directs gases generated within the power battery toward the chamber, allowing the valve to blast in a targeted manner, improving the timeliness of the blast. After the explosion-proof valve blasts, the fire retardant contained in the explosion-proof chamber treats the heat and sparks emitted, providing a flame retardant effect and preventing them from spreading outside the power battery and affecting adjacent power batteries in the battery module or battery pack.

[0010] As a technical solution of the present application, the explosion-proof valve and the top wall are integrally formed.

[0011] As a technical solution of the present application, an explosion-proof hole is opened on the top wall, and the explosion-proof valve is sealed and welded to the explosion-proof hole.

[0012] As a technical solution of the present application, in the vertical direction, the size of the peripheral wall is less than half the size of the shell.

[0013] As a technical solution of the present application, in the horizontal direction, the area of ​​the top wall is less than one quarter of the area of ​​the cover plate.

[0014] As a technical solution of the present application, the outer contour of the explosion-proof cavity is a cylinder, and the outer contour of the shell is a cylinder.

[0015] As a technical solution of the present application, the fire retardant is at least one of chlorinated paraffin, chlorinated rubber, polyvinyl chloride, phosphorus-containing resin, tetrabromophthalic anhydride, tetrachlorophthalic anhydride, hexabromobenzene, decabromobiphenyl, decachlorobiphenyl, halogen-containing aliphatic phosphate, dimerized hexachlorocyclopentadiene, hexabromocyclododecane, ammonium chloride, ammonium bromide, borax, boric acid, ammonium phosphate, sodium phosphate, sodium tungstate, water glass and antimony trioxide.

[0016] As a technical solution of the present application, a sealing plate is provided at one end of the explosion-proof cavity away from the explosion-proof valve, and the fire retardant is sealed in the explosion-proof cavity by the sealing plate.

[0017] As a technical solution of the present application, an opening is provided at one end of the explosion-proof cavity away from the explosion-proof valve, a breathable bag is fixed in the explosion-proof cavity, and the breathable bag is filled with the fire retardant.

[0018] As a technical solution of the present application, a first pole electrically connected to one of the poles of the battery cell is provided on the cover plate, and an injection hole connecting the outside and the cavity is provided on the first pole. A sealing member is provided in the injection hole, and the cavity is provided with a liquid storage chamber located below the injection hole and connected to the injection hole, and the liquid storage chamber is suspended on the upper part of the explosion-proof device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG1 is a perspective view of a secondary battery of the present application.

[0020] FIG2 is a top view of the secondary battery of the present application.

[0021] FIG3 is a bottom view of the secondary battery of the present application.

[0022] FIG4 is a front view of the secondary battery of the present application.

[0023] FIG5 is a variation diagram of FIG4 .

[0024] FIG6 is a cross-sectional view of the secondary battery of the present application along the central axis.

[0025] FIG. 7 is a variation of FIG. 6 .

[0026] FIG8 is another variation of FIG6 .

[0027] FIG9 is an enlarged view of the explosion-proof device in FIG6 .

[0028] FIG10 is a variation of FIG9 .

[0029] FIG11 is an enlarged view of the circled portion in FIG9 .

[0030] FIG12 is an enlarged view of the liquid storage chamber portion in FIG7 .

[0031] FIG13 is an enlarged view of the circled portion in FIG8 .

[0032] Component Symbol Description

[0033] 100 - secondary battery; 10 - housing; 30 - cover; 31 - first electrode; 33 - injection hole; 35 - seal; 37 - second electrode; 50 - battery cell; 70 - liquid storage chamber; 71 - through hole; 73 - bracket; 75 - notch; 90 - explosion-proof device; 91 - explosion-proof chamber; 911 - top wall; 913 - peripheral wall; 915 - opening; 93 - explosion-proof valve; 95 - fire retardant; 97 - sealing plate; 99 - breathable bag; X - horizontal direction; Y - vertical direction DETAILED DESCRIPTION

[0034] To better illustrate the purpose, technical solutions and beneficial effects of this application, the following will further illustrate this application with reference to specific drawings and implementation methods. It should be noted that the following implementation methods are further explanations of this application and should not be regarded as limitations on this application.

[0035] As shown in FIGS. 1 to 8 , a secondary battery 100 includes a battery cell 50 , a housing 10 having a cavity therein, and a cover plate 30 that seals the housing 10 .

[0036] The battery cell 50 can be wound or laminated. If wound, the battery cell 50 comprises a wound body formed by stacking a first electrode sheet, a separator, and a second electrode sheet in sequence. If laminated, the battery cell 50 comprises a plurality of laminated bodies formed by stacking a first electrode sheet, a separator, and a second electrode sheet in sequence.

[0037] The cover plate 30 is provided with a first terminal 31 electrically connected to one of the electrodes in the battery cell 50. The first terminal 31 can be integrally formed with the cover plate 30 or insulated and fixed to the cover plate 30. The housing 10 can serve as a second electrode for output, electrically connected to the other electrode in the battery cell 50. Alternatively, a second terminal 37 can be further protruded from the cover plate 30, with at least one of the first terminal 31 and the second terminal 37 being electrically insulated from the cover plate 30.

[0038] The interior of the shell 10 has a cavity (not shown in the figure), in which the battery cell 50 is accommodated. The upper end opening of the shell 10 is sealed by the cover plate 30, and the shell 10 and the cover plate 30 can be fixed by welding, bonding or interlocking. The bottom and the surrounding wall of the shell 10 can be stamped into one piece, or it can be a split structure. If it is a split structure, its bottom and the surrounding wall are fixed by welding. The shell 10 can be made of stainless steel, aluminum, carbon steel, magnesium alloy, etc., or it can be made of insulating materials such as ceramics.

[0039] Furthermore, as shown in Figures 9 to 11, the bottom of the housing 10 bulges outward toward the cover plate 30 to form an explosion-proof cavity 91, and an explosion-proof device 90 is installed in the explosion-proof cavity 91. The explosion-proof cavity 91 includes a top wall 911 adjacent to the cover plate 30 and a peripheral wall 913 connected to the top wall 911. The explosion-proof device 90 includes an explosion-proof valve 93 and a fire retardant 95. The explosion-proof valve 93 is located on the top wall, and the fire retardant is contained in the explosion-proof cavity 91. This design can gather the gas generated inside the power battery 100 near the explosion-proof cavity 91, thereby allowing the explosion-proof valve 93 to be directionally exploded to improve the timeliness of the explosion. After the explosion-proof valve 93 explodes, the fire retardant 95 contained in the explosion-proof cavity 91 can process the heat and sparks that are ejected to play a flame retardant role, thereby preventing the spread of the heat and sparks outside the power battery 100 and affecting the adjacent power batteries in the battery module or battery pack.

[0040] Fire retardant 95 can be a conventional flame retardant, including but not limited to at least one of chlorinated paraffin, chlorinated rubber, polyvinyl chloride, phosphorus-containing resin, tetrabromophthalic anhydride, tetrachlorophthalic anhydride, hexabromobenzene, decabromobiphenyl, decachlorobiphenyl, halogenated aliphatic phosphate esters, dimerized hexachlorocyclopentadiene, hexabromocyclododecane, ammonium chloride, ammonium bromide, borax, boric acid, ammonium phosphate, sodium phosphate, sodium tungstate, water glass, and antimony trioxide. To secure the fire retardant within explosion-proof chamber 91, as shown in FIG9 , a sealing plate 97 is provided at one end of explosion-proof chamber 91 away from explosion-proof valve 93. Fire retardant 95 is sealed within explosion-proof chamber 91 via sealing plate 97. Alternatively, as shown in Figure 10, an opening 915 can be provided at one end of the explosion-proof chamber 91 away from the explosion-proof valve 93, and a breathable bag 99 can be fixed in the explosion-proof chamber 91, and the breathable bag 99 can be filled with a fire retardant 95. This method can also replace the fire retardant 95 in time to prevent the fire retardant 95 from becoming ineffective due to moisture or heat.

[0041] Furthermore, the explosion-proof valve 93 and the top wall 911 in the explosion-proof device 90 are integrally formed, and this method is simple to process. Alternatively, an explosion-proof hole is opened on the top wall 911, and the explosion-proof valve 93 is sealed and welded to the explosion-proof hole. The shell 10 of the present application can be a cylindrical structure as shown in Figures 1 to 4, or a rectangular parallelepiped structure as shown in Figure 5. In the vertical direction Y, the size of the peripheral wall 913 is less than half the size of the shell 10. In the horizontal direction X, the area of ​​the top wall 911 is less than one-quarter of the area of ​​the cover plate 30, thereby controlling the volume occupied by the explosion-proof device 90 in the shell 10 to maintain sufficient volume energy density of the secondary battery 100.

[0042] To further utilize the cavity space of the housing 10 in addition to the explosion-proof device 90, as shown in Figures 7-8 and 12-13, a liquid injection hole 33 is provided on the first electrode 31, connecting the cavity with the outside world. A sealing member 35 is provided in the liquid injection hole 33. A liquid storage chamber 70 is provided in the cavity, located below and connected to the liquid injection hole 33. The liquid storage chamber 70 is suspended above the explosion-proof device 90 and defines a plurality of through-holes 71 connecting the cavity with the liquid injection hole 33. Therefore, when the secondary battery 100 is assembled, after the electrolyte fills the entire battery cell 50, the excess electrolyte is stored in the liquid storage chamber 70. Therefore, even after the liquid injection hole 33 is sealed with the sealing member 35, if the electrolyte in the battery cell 50 is insufficient due to consumption, the electrolyte in the liquid storage chamber 70 can seep into the battery cell 50 through the through-holes 71, thereby replenishing the electrolyte. This can extend the service life of the secondary battery 100 and reduce its operating costs. After the secondary battery is filled with liquid, the sealing member 35 seals the liquid injection hole 33. The sealing member 35 can be an aluminum nail or the like and is fixed to the liquid injection hole 33 by welding. In addition, the vertical projections of the explosion-proof device 90 and the liquid storage chamber 70 are aligned to avoid occupying a large amount of volume in the housing 10, thereby ensuring that the secondary battery 100 has a sufficient volumetric energy density.

[0043] Furthermore, the through holes 71 are provided at least on the peripheral wall of the liquid storage chamber 70. Alternatively, the through holes 71 are provided at least on the bottom wall of the liquid storage chamber 70. That is, the through holes 71 may be provided only on the peripheral wall of the liquid storage chamber 70, only on the bottom wall of the liquid storage chamber 70, or both on the peripheral wall and the bottom wall of the liquid storage chamber 70. Preferably, the through holes 71 are provided only on the peripheral wall of the liquid storage chamber 70, and there are multiple through holes 71, the multiple through holes 71 being regularly arranged on the peripheral wall of the liquid storage chamber 70, and the sum of the areas of the multiple through holes 71 accounting for at least 1 / 5 of the surface area of ​​the liquid storage chamber 70, to ensure that the electrolyte can quickly fill the battery cell during injection. Furthermore, to increase the injection rate, as shown in Figures 8 and 13, a bracket 73 is provided on the side of the liquid storage chamber 70 near the cover plate 30. The liquid storage chamber 70 is fixed to the cover plate 30 by the bracket 73. A notch 75 is provided on the bracket 73 to connect the cavity and the injection hole 33. During injection, if the electrolyte is slowly flowing through the through hole 71 to fill the battery cell 50, it can overflow from the notch 75 and enter from the top of the battery cell 50, thereby greatly improving the injection rate. The orthographic projection of the liquid storage chamber 70 on the cover plate 30 is larger than the orthographic projection of the injection hole 33 on the cover plate 30. The horizontal dimension of the liquid storage chamber 70 is large to ensure that the electrolyte can fill the liquid storage chamber 70, ensuring a sufficient amount for subsequent electrolyte replenishment. The liquid storage chamber 70 can be welded or welded to the lower portion of the cover plate 30 using the bracket 73.

[0044] If the battery cell 50 is cylindrical, a through hole is provided on the winding core shaft of the battery cell 50, and the liquid storage chamber 70 is inserted into the through hole. This method is convenient for assembly, and the outer contour of the liquid storage chamber 70 is also cylindrical. This method can make the liquid storage chamber 70 and the battery cell 50 in close contact, so as to fully utilize the space in the cavity. Based on the cylindrical structure of the battery cell 50, due to its winding structure, a certain amount of space is usually left in the middle after winding. The liquid storage chamber 70 is provided in the middle, which does not take up too much space and has a very low impact on the volume energy density of the battery cell 50. A certain distance is provided between the liquid storage chamber 70 and the explosion-proof device 90, so that the liquid storage chamber 70 can play a role in replenishing fluid while not affecting the convergence of the gas generated by the secondary battery 100 around the explosion-proof chamber 91. The through hole 71 on the liquid storage chamber 70 is preferably only provided on the peripheral wall to avoid affecting the performance of the explosion-proof valve 93 in the explosion-proof device 90. Of course, the battery cell 50 may also have other structures, such as a square or flat shape. In this case, the first electrode 31 and the second electrode 37 of the secondary battery 100 are both located on the cover plate 30, and are respectively adjacent to opposite sides of the cover plate 30. For a square or flat battery cell 50, a liquid injection hole 33 may be provided on the first electrode 31 and / or the second electrode 37. The liquid injection hole 33 may be provided on one electrode or on both electrodes. If a liquid injection hole 33 is provided on both electrodes, there may be two liquid storage chambers 70, each fixed below the cover plate 30. In this case, there may also be two explosion-proof devices 90. As shown in FIG5 , the two explosion-proof devices 90 are located directly below the liquid storage chamber 70. Furthermore, the vertical projections of the explosion-proof devices 90 and the liquid storage chamber 70 are aligned to avoid occupying a large amount of volume within the housing 10.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A secondary battery, characterized in that: The invention comprises a battery cell, a shell having a cavity therein and a cover plate sealing the shell, wherein the battery cell is accommodated in the cavity, the bottom of the shell protrudes outward toward the cover plate to form an explosion-proof cavity, an explosion-proof device is arranged in the explosion-proof cavity, the explosion-proof cavity comprises a top wall close to the cover plate and a peripheral wall connected to the top wall, the explosion-proof device comprises an explosion-proof valve and a fire retardant, the explosion-proof valve is arranged on the top wall, and the fire retardant is accommodated in the explosion-proof cavity.

2. The secondary battery according to claim 1, characterized in that: The explosion-proof valve and the top wall are integrally formed.

3. The secondary battery according to claim 1, characterized in that: An explosion-proof hole is provided on the top wall, and the explosion-proof valve is sealed and welded to the explosion-proof hole.

4. The secondary battery according to claim 1, characterized in that: In the vertical direction, the size of the peripheral wall is less than half of the size of the shell.

5. The secondary battery according to claim 1, characterized in that: In the horizontal direction, the area of ​​the top wall is less than one quarter of the area of ​​the cover plate.

6. The secondary battery according to claim 1, characterized in that: The outer contour of the explosion-proof cavity is a cylinder, and the outer contour of the shell is a cylinder.

7. The secondary battery according to claim 1, characterized in that: The fire retardant is at least one of chlorinated paraffin, chlorinated rubber, polyvinyl chloride, phosphorus-containing resin, tetrabromophthalic anhydride, tetrachlorophthalic anhydride, hexabromobenzene, decabromobiphenyl, decachlorobiphenyl, halogen-containing aliphatic phosphate, dimerized hexachlorocyclopentadiene, hexabromocyclododecane, ammonium chloride, ammonium bromide, borax, boric acid, ammonium phosphate, sodium phosphate, sodium tungstate, water glass and antimony trioxide.

8. The secondary battery according to claim 1, characterized in that: A sealing plate is provided at one end of the explosion-proof cavity away from the explosion-proof valve, and the fire retardant is sealed in the explosion-proof cavity by the sealing plate.

9. The secondary battery according to claim 1, characterized in that: An opening is arranged at one end of the explosion-proof cavity away from the explosion-proof valve, a breathable bag is fixed in the explosion-proof cavity, and the fire retardant is filled in the breathable bag.

10. The secondary battery according to claim 1, characterized in that: The cover plate is provided with a first pole electrically connected to one of the poles of the battery cell, the first pole is provided with an injection hole connecting the outside and the cavity, a sealing member is provided in the injection hole, the cavity is provided with a liquid storage chamber located below the injection hole and connected to the injection hole, and the liquid storage chamber is suspended on the upper part of the explosion-proof device.

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