CN212182380U

CN212182380U - Secondary battery, cap assembly thereof, battery module and device using the same

Info

Publication number: CN212182380U
Application number: CN202021204450.XU
Authority: CN
Inventors: 蒙万秋; 刘倩; 叶永煌
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2020-06-24
Filing date: 2020-06-24
Publication date: 2020-12-18
Anticipated expiration: 2030-06-24

Abstract

The utility model provides a secondary battery and lid subassembly, battery module and use secondary battery's device thereof. The cap assembly includes: a cover plate having a first through hole; a fixture for connecting the cover plate, the fixture having a second through-hole configured to be in gaseous communication with the first through-hole; and the breathable film is connected with the fixing piece through a chemical bond, and the breathable film is used for covering the second through hole.

Description

Secondary battery, cap assembly thereof, battery module and device using the same

Technical Field

The utility model relates to a battery field especially relates to a secondary battery and lid subassembly, battery module and the device of using secondary battery thereof.

Background

Secondary batteries such as lithium ion batteries are widely used in electronic devices such as mobile phones and notebook computers because of their advantages such as high energy density and environmental friendliness. In recent years, in order to cope with environmental issues, gasoline price issues, and energy storage issues, the application of lithium ion batteries has been rapidly expanded to gasoline-electric hybrid vehicles, ships, and energy storage systems, and the like.

A secondary battery generally includes a case, an electrode assembly and an electrolyte solution contained in the case, the electrode assembly including a positive electrode tab, a negative electrode tab, and a separator separating the positive electrode tab and the negative electrode tab, and a cap assembly connected to the case. To avoid leakage of the electrolyte solution, the cap assembly typically seals the case. However, gas is generated in the electrode assembly during the charge and discharge processes, and the internal pressure inside the case increases with the accumulation of the gas, which easily causes the deformation of the battery and the deterioration of the performance of the electrode assembly.

SUMMERY OF THE UTILITY MODEL

In view of the problems in the prior art, an object of the present invention is to provide a secondary battery and a cap assembly thereof, a battery module and a device using the same, which can discharge gas inside the battery, prevent gas from accumulating inside a case, improve the performance of an electrode assembly, and prolong the life of the secondary battery.

In order to accomplish the above object, in some embodiments, the present invention provides a cap assembly of a secondary battery, including: a cover plate having a first through hole; a fixture for connecting the cover plate, the fixture having a second through-hole configured to be in gaseous communication with the first through-hole; and the breathable film is connected with the fixing piece through a chemical bond, and the breathable film is used for covering the second through hole.

In a cap assembly according to some embodiments, at least a portion of the gas permeable membrane is sandwiched between the fixing member and the cover plate.

In the cap assembly according to some embodiments, the first through hole includes a receiving section and an extending section extending from the receiving section, and the receiving section has a larger aperture than the extending section and is at least partially received in the receiving section.

In the cap assembly according to some embodiments, the accommodating section has a bottom wall surrounding the extension section, and at least a portion of the air permeable membrane is sandwiched between the fixing member and the bottom wall to separate the second through hole and the extension section.

In the cap assembly according to some embodiments, an aperture of the second through hole is smaller than an aperture of the extension section.

In a cap assembly according to some embodiments, the fixing member has a groove disposed around the second through hole, and the gas permeable membrane is at least partially accommodated in the groove.

In the cap assembly according to some embodiments, the fixing member is welded to the cap plate, and a minimum distance between the gas permeable membrane and an outer edge of the fixing member is greater than 3 mm.

In the cap assembly according to some embodiments, the cap assembly further includes a protective film disposed on a side of the fixing member away from the gas permeable film and covering the second through hole, and the gas permeable film has a gas permeability smaller than that of the protective film.

In the cap assembly according to some embodiments, the bonding surface of the gas permeable membrane and the fixing member is formed with a functional group bonded by chemical bond.

The present application also provides a secondary battery. In some embodiments, the secondary battery includes: a housing having an opening; an electrode assembly accommodated in the case and including a positive electrode tab, a negative electrode tab, and a separator separating the positive electrode tab and the negative electrode tab; and the cover assembly is connected to the shell and covers the opening of the shell.

The present application also provides a battery module including a plurality of secondary batteries as described above.

The present application also provides a device using a secondary battery, which includes the secondary battery as described above, the secondary battery providing electric energy.

The utility model has the advantages as follows: in the present application, the second through hole is in gas communication with the first through hole, and the gas permeable membrane has a gas permeable function, and therefore, the generated gas can be discharged to the outside of the secondary battery via the first through hole, the gas permeable membrane, and the second through hole, avoiding gas accumulation inside the case, improving the performance of the electrode assembly, and increasing the life of the secondary battery. The ventilated membrane is directly connected with the fixing piece through a chemical bond, so that the connection strength of the ventilated membrane and the fixing piece can be effectively increased, the risk that the ventilated membrane breaks away from the fixing piece under the gas impact is reduced, and the sealing performance of the secondary battery is improved.

Drawings

Fig. 1 is a schematic view of a device using a secondary battery according to some embodiments of the present application.

Fig. 2 is a schematic diagram of a battery pack according to some embodiments of the present application.

Fig. 3 is a schematic diagram of a battery module according to some embodiments of the present application.

Fig. 4 is a schematic view of a secondary battery according to a first exemplary embodiment of the present application.

Fig. 5 is a sectional view of the secondary battery of fig. 4.

Fig. 6 is an enlarged view of the secondary battery of fig. 5 at block a.

Fig. 7 is a schematic view of the parts of fig. 6 in an exploded state.

Fig. 8 is a sectional view of a secondary battery according to a second exemplary embodiment of the present application.

Fig. 9 is an enlarged view of the secondary battery of fig. 8 at block B.

Fig. 10 is a sectional view of a secondary battery according to a third exemplary embodiment of the present application.

Fig. 11 is an enlarged view of the secondary battery of fig. 10 at block C.

Fig. 12 is a sectional view of a secondary battery according to a fourth exemplary embodiment of the present application.

Fig. 13 is an enlarged view of the secondary battery of fig. 12 at block D.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "including" and "having," and any variations thereof, in the description and claims of this application and the description of the above figures are intended to cover non-exclusive inclusions. The terms "first," "second," and the like in the description and claims of this application or in the above-described drawings are used for distinguishing between different elements and not for describing a particular sequential or chronological order.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

The term "and/or" herein is merely an association describing an associated object, meaning that three relationships may exist, e.g., a and/or B, may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

The "plurality" in the present application means two or more (including two), and similarly, "plural" means two or more (including two) and "plural" means two or more (including two).

The cap assembly, the secondary battery, and the battery module described in the embodiments of the present application are applicable to various devices using a battery, for example, mobile phones, portable devices, notebook computers, battery cars, electric vehicles, ships, spacecraft, electric toys, electric tools, and the like, for example, spacecraft including airplanes, rockets, space shuttle, and spacecraft, and the like, electric toys including stationary or mobile electric toys, for example, game machines, electric automobile toys, electric ship toys, and electric airplane toys, and the like, electric tools including metal cutting electric tools, grinding electric tools, assembly electric tools, and electric tools for railways, for example, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers.

The cap assembly, the secondary battery, and the battery module described in the embodiments of the present application are not limited to be applied to the above-described devices, but may be applied to all devices using a battery.

For example, as shown in fig. 1, which is a schematic structural diagram of an automobile 500 according to an embodiment of the present application, the automobile 500 may be a fuel automobile, a gas automobile, or a new energy automobile, and the new energy automobile may be a pure electric automobile, a hybrid electric automobile, or an extended range automobile. The battery pack 510 may be disposed inside the automobile 500, for example, the battery pack 510 may be disposed at the bottom or the head or tail of the automobile 500. The battery pack 510 may be used to power the vehicle 500, for example, the battery pack 510 may be used as an operating power source for the vehicle 500, and used for the circuitry of the vehicle 500, for example, for power requirements during start-up, navigation, and operation of the vehicle 500. In another embodiment of the present application, the battery pack 510 may be used not only as an operating power source of the vehicle 500, but also as a driving power source of the vehicle 500, instead of or in part of fuel or natural gas, to provide driving power for the vehicle 500.

In order to meet different power requirements, the battery pack 510 may include one battery module or a plurality of battery modules, wherein the plurality of battery modules may be connected in series or in parallel or in a series-parallel manner, and the series-parallel manner refers to a mixture of series connection and parallel connection. For example, as shown in fig. 2, a schematic structural diagram of a battery pack 510 according to an embodiment of the present disclosure is provided, where the battery pack 510 includes a first case 511, a second case 512, and a plurality of battery modules 513, where shapes of the first case 511 and the second case 512 are determined according to a shape of a combination of the plurality of battery modules 513, each of the first case 511 and the second case 512 has an opening, for example, each of the first case 511 and the second case 512 may be a hollow rectangular parallelepiped and only one surface of each of the first case 511 and the second case 512 is an open surface, that is, the surface does not have a case wall so as to communicate between the inside and the outside of the case, the first case 511 and the second case 512 are fastened to each other at the opening to form a closed outer case of the battery pack 510, and the plurality of battery modules 513 are connected to each other in parallel, in series, or in a combination of parallel and parallel with each other.

In another embodiment of the present application, when the battery pack 510 includes one battery module 513, the battery module 513 is disposed in an outer case formed by fastening the first case 511 and the second case 512.

Electricity generated by the one or more battery modules 513 is drawn through the housing by conductive means (not shown).

Fig. 3 is a schematic diagram of a battery module according to some embodiments of the present application. Referring to fig. 3, the battery module 513 includes a plurality of secondary batteries 100. In some embodiments, the plurality of secondary batteries 100 are arranged in sequence. The battery module 513 further includes two end plates and two side plates, the two end plates are respectively located at two ends of the plurality of secondary batteries 100 in the arrangement direction, the two side plates are respectively located at two sides of the plurality of secondary batteries 100, the two end plates and the two side plates are connected together and form a frame structure that is approximately rectangular, and the frame structure supports and fixes the plurality of secondary batteries 100.

The present application also provides a secondary battery. Fig. 4 is a schematic view of a secondary battery according to a first exemplary embodiment of the present application. Fig. 5 is a sectional view of the secondary battery of fig. 4.

Referring to fig. 4 and 5, the secondary battery 100 according to the first exemplary embodiment includes: a housing 11 having an opening; an electrode assembly 12 housed in the case 11; and a cap assembly 10 connected to the case 11 and covering the opening of the case 11.

The secondary battery 100 according to the first exemplary embodiment illustrates a rectangular-shaped lithium-ion rechargeable battery. However, the present application is not limited thereto, and embodiments of the present application may include various forms of batteries, such as a lithium polymer battery or a cylindrical battery.

The electrode assembly 12 includes a positive electrode tab, a negative electrode tab, and a separator separating the positive electrode tab and the negative electrode tab, and in the present embodiment, the electrode assembly 12 may be formed by spirally winding the positive electrode tab, the negative electrode tab, and the separator. The electrode assembly 12 may be pressed flat to form a flat shape. In one embodiment, the electrode assembly 12 is multiple and stacked.

The case 11 is formed in a substantially cubic shape and has an opening at one surface thereof, and a plurality of electrode assemblies 12 are inserted into the case 11.

The cap assembly 10 includes: a cover plate 14 covering the opening of the case 11; two electrode terminals 15 protruding to the outside of the cap plate 14 and electrically connected to the positive electrode tab and the negative electrode tab, respectively; and a rupture disk 16 configured to rupture when the pressure inside the housing 11 reaches a set value. In one embodiment, the two electrode terminals 15 are electrically connected to the positive and negative electrode tabs, respectively, through the two current collecting members 13.

The cap plate 14 is formed as a thin metal plate provided with a filling hole for filling an electrolyte solution and a sealing plug for sealing the filling hole. The cap plate 14 is further provided with a through terminal hole, and the electrode terminal 15 is provided on one side of the cap plate 14 to cover the terminal hole. The electrode terminal 15 is formed in a cylindrical shape and is fixed to the cap plate 14 by a connection member around the outer circumference thereof.

The lid plate 14 is provided with a through-hole 141, and the explosion-proof sheet 16 is fixed to the lid plate 14 so as to cover the hole 141. The explosion-proof sheet 16 has a weak region where the gas pressure inside the secondary battery 100 increases and the explosion-proof sheet 16 is broken when a large amount of gas is generated from the electrode assembly 12 due to overcharge, short circuit, or the like, and the gas is discharged to the outside of the secondary battery 100 through the gas discharge hole 141, thereby reducing the risk of explosion of the secondary battery.

Fig. 6 is an enlarged view of the secondary battery of fig. 5 at block a. Fig. 7 is a schematic view of the parts of fig. 6 in an exploded state.

Referring to fig. 6 and 7, the cap plate 14 has a first through hole 142. The first through hole 142 penetrates the cap plate 14 to communicate spaces at both sides of the cap plate 14. In one embodiment, the first through hole 142 penetrates the cover plate 14 along the thickness direction Z of the cover plate 14, that is, the axis of the first through hole 142 is parallel to the thickness direction Z of the cover plate 14.

The cap assembly 10 further includes a fixing member 17, and the fixing member 17 is used to connect the cap plate 14. In some embodiments, the fixing member 17 is connected to the cover plate 14, and specifically, the fixing member 17 is fixed to the cover plate 14 by welding.

The fixing member 17 has a second through hole 171, and the second through hole 171 is configured to be in gas communication with the first through hole 142. The gas in the first through hole 142 can freely flow into the second through hole 171, and of course, the gas in the second through hole 171 can also freely flow into the first through hole 142.

The cover assembly 10 further includes a gas permeable membrane 18, the gas permeable membrane 18 being adapted to cover the second through hole 171. The gas permeable membrane 18 is made of a polymer material (e.g., PP) having gas permeable characteristics, and is capable of blocking liquid. The permeable membrane 18 and the fixing member 17 are connected as a whole and block the first through hole 142, so that the permeable membrane 18 and the fixing member 17 can block the electrolyte solution and prevent the electrolyte solution from leaking.

The electrode assembly 12 generates gas (e.g., CO) during charging and discharging₂，CH₄，C₂H₆，H₂Etc.) as the gas accumulates, the internal pressure inside the housing 11 increases, and electricity is easily inducedThe cell is deformed and the performance of the electrode assembly is deteriorated. In the secondary battery 100 according to the first example embodiment, the second through-hole 171 is in gas communication with the first through-hole 142, and the gas permeable membrane 18 has a gas permeable function, and therefore, the generated gas can be discharged to the outside of the secondary battery 100 via the first through-hole 142, the gas permeable membrane 18, and the second through-hole 171, avoiding accumulation of gas inside the case 11, improving the performance of the electrode assembly 12, and increasing the life of the secondary battery 100.

The gas permeable membrane 18 and the fixing member 17 are connected by a chemical bond (ionic bond or covalent bond). Specifically, the surface treatment is performed on the breathable film 18 and the fixing member 17 to form functional groups on the surface of the breathable film 18 and the surface of the fixing member 17, then the breathable film 18 and the fixing member 17 are connected in a thermal compounding manner, and the functional groups of the breathable film 18 and the fixing member 17 are connected at the joint surface of the breathable film 18 and the fixing member 17 through chemical bonds.

The breathable film 18 is directly connected with the fixing member 17 through a chemical bond, so that the connection strength of the breathable film 18 and the fixing member 17 can be effectively increased, the risk that the breathable film 18 is separated from the fixing member 17 under the gas impact is reduced, and the sealing performance of the secondary battery is improved.

The gas permeable membrane 18 is at least partially sandwiched between the fixing member 17 and the cover plate 14. The fixing piece 17 and the cover plate 14 can clamp the breathable film 18, so that the risk of falling of the breathable film 18 is further reduced.

The first through hole 142 includes a receiving section 143 and an extending section 144 extending from the receiving section 143, and the aperture of the receiving section 143 is larger than that of the extending section 144. The receiving section 143 and the extending section 144 are coaxial holes. The extension section 144 is located at a side of the receiving section 143 near the electrode assembly 12. The holder 17 is at least partially received in the receiving section 143 to reduce the space occupied by the holder 17 and reduce the overall height of the secondary battery 100.

The receiving section 143 has a bottom wall 145 surrounding the extending section 144, and the fixing member 17 is located at one side of the bottom wall 145. The receiving section 143 and the extending section 144 of different apertures form a stepped surface (i.e., a bottom wall 145) capable of supporting the fixing member 17 to facilitate positioning of the fixing member 17 when welding the fixing member 17 and the cover plate 14. The receiving section 143 further has a side wall 146 surrounding the fixing member 17, and the bottom wall 145 and the side wall 146 enclose the receiving section 143.

At least a portion of the gas permeable membrane 18 is sandwiched between the fixing member 17 and the bottom wall 145 to separate the second through hole 171 and the extension section 144. The air permeable membrane 18 is entirely located outside the extension section 144, and an annular edge portion 181 of the outer periphery thereof is sandwiched between the fixing member 17 and the bottom wall 145. In order to improve the sealing performance, the edge portion 181 is in a compressed state, preventing the electrolyte solution from flowing out from between the bottom wall 145 and the gas permeable membrane 18.

During the use of the secondary battery 100, the gas permeable membrane 18 may be deformed by the gas generated, and the edge portion 181 may be pulled outward. If the gas permeable membrane 18 is not directly attached to the fixing member 17, the edge portion 181 may be drawn out from between the fixing member 17 and the cover plate 14 by a tensile force, resulting in the gas permeable membrane 18 coming off and the sealing failure, causing a risk of leakage of the electrolyte solution. In the present application, the gas permeable membrane 18 is directly connected to the fixing member 17 by a chemical bond, which can effectively increase the connection strength between the gas permeable membrane 18 and the fixing member 17, reduce the risk that the gas permeable membrane 18 is separated from the fixing member 17 under the action of gas, and improve the sealing performance of the secondary battery.

The maximum vent rate of the vent membrane 18 depends on the exposed area of the vent membrane 18, i.e., the area of the second through hole 171, and if the pore diameter of the extension section 144 is smaller than that of the second through hole 171, the cover plate 14 blocks the vent gas and reduces the vent area, and therefore, the pore diameter of the second through hole 171 is preferably smaller than that of the extension section 144. The second through hole 171 and the extension 144 are preferably coaxial holes.

In addition, if the aperture diameter of the extension section 144 is smaller than the aperture diameter of the second through hole 171, the area of the gas permeable membrane 18 covered by the bottom wall 145 is larger than the area of the gas permeable membrane 18 covered by the fixing member 17, and there is a portion of the gas permeable membrane 18 that overlaps the bottom wall 145 and does not overlap the fixing member 17; when the gas permeable membrane 18 bulges and deforms towards the inside of the second through hole 171 under the action of gas generation, the part can be separated from the bottom wall 145; at this time, the electrolyte solution may flow between the portion and the bottom wall 145, and the electrolyte solution may be crystallized to break the gas permeable membrane 18, which may affect the sealing performance, and may clog the gas permeable membrane 18, which may decrease the gas release rate. Therefore, the second through hole 171 preferably has a smaller hole diameter than the extension section 144. At this time, the area of the gas permeable membrane 18 covered by the bottom wall 145 is smaller than the area of the gas permeable membrane 18 covered by the fixing member 17, and even if the gas permeable membrane 18 bulges and deforms toward the inside of the second through hole 171 under the action of the generated gas, the gas permeable membrane 18 does not separate from the bottom wall 145, thereby reducing the risk of the electrolyte solution flowing between the gas permeable membrane 18 and the bottom wall 145.

The fixing member 17 has a recess 172, the recess 172 is disposed around the second through hole 171, and the air permeable membrane 18 is at least partially accommodated in the recess 172. By arranging the groove 172, the space occupied by the breathable film 18 can be reduced, and the overall thickness of the fixing member 17 and the breathable film 18 can be reduced. The thickness of the air permeable membrane 18 can be slightly larger than the depth of the groove 172, when the fixing member 17 and the cover plate 14 are assembled, the fixing member 17 is attached to the bottom wall 145, and the air permeable membrane 18 is compressed, so that the sealing performance is improved.

The fixing member 17 is welded to the cover plate 14. Specifically, welding is performed along the interface of sidewall 146 and the outer edge of anchor 17. When the fixing member 17 and the cover plate 14 are welded, heat is conducted from the outer edge of the fixing member 17 to the breathable film 18, and the smaller the distance between the breathable film 18 and the outer edge of the fixing member 17 is, the more heat is conducted to the breathable film 18, and if the heat is too large, the bonding surface between the breathable film 18 and the fixing member 17 is damaged, and the connection strength between the breathable film 18 and the fixing member 17 is reduced. Therefore, the minimum distance of the air permeable membrane 18 from the outer edge of the fixing member 17 is preferably more than 3 mm.

Fig. 8 is a sectional view of a secondary battery according to a second exemplary embodiment of the present application. Fig. 9 is an enlarged view of the secondary battery of fig. 8 at block B.

Referring to fig. 8 and 9, the secondary battery 200 according to the present embodiment includes: a housing 21 having an opening; an electrode assembly 22 accommodated in the case 21; and a cap assembly 20 connected to the case 21 and covering the opening of the case 21.

The cap assembly 20 includes: a cover plate 24 covering the opening of the case 21; two electrode terminals 25 protruding to the outside of the cap plate 24 and electrically connected to the electrode assembly 22; and a rupture disk 26 configured to rupture when the internal pressure of the case 21 reaches a set value. In one embodiment, the two electrode terminals 25 are electrically connected to the positive and negative electrode tabs of the electrode assembly 22 through the two current collecting members 23, respectively.

The cap plate 24 has a first through hole 242. The first through hole 242 penetrates the cap plate 24 to communicate spaces at both sides of the cap plate 24. The cap assembly 20 further includes a fixing member 27, and the fixing member 27 is used to connect the cap plate 24. In some embodiments, the fixing member 27 is fixed to the cover plate 24 by welding.

The fixing member 27 has a second through hole 271, and the second through hole 271 is configured to be in gas communication with the first through hole 242. The gas in the first through hole 242 can freely flow into the second through hole 271, and of course, the gas in the second through hole 271 can freely flow into the first through hole 242.

The cover assembly 20 further includes a gas permeable membrane 28, the gas permeable membrane 28 being adapted to cover the second through hole 271. The gas permeable membrane 28 is made of a polymer material (e.g., PP) having gas permeable characteristics, and is capable of blocking liquid. The gas permeable membrane 28 and the fixing member 27 are connected as a whole and block the first through hole 242, and therefore, the gas permeable membrane 28 and the fixing member 27 can block the electrolyte solution, and the electrolyte solution is prevented from leaking.

The secondary battery 200 according to the present embodiment is formed to be identical or similar to the secondary battery 100 according to the first exemplary embodiment, except for the fixing member 27 and the gas permeable film 28. Therefore, description of the structure equivalent to or similar to that of the first exemplary embodiment will be omitted.

In the secondary battery 200 according to the present embodiment, the gas permeable membrane 28 is provided on the side of the fixing member 27 away from the lid plate 24, and in fig. 8 and 9, the gas permeable membrane 28, the fixing member 27, and the lid plate 24 are provided up and down. At this time, the second through hole 271 is in direct communication with the first through hole 242.

The fixing member 27 has a groove 272, the groove 272 is disposed around the second through hole 271, and the air permeable membrane 28 is at least partially accommodated in the groove 272. The recess 272 is located on the side of the fixing member 27 remote from the cover plate 24. Through setting up recess 272, can reduce the space that ventilated membrane 28 took up, reduce the whole thickness of mounting 27 and ventilated membrane 28.

Fig. 10 is a sectional view of a secondary battery according to a third exemplary embodiment of the present application. Fig. 11 is an enlarged view of the secondary battery of fig. 10 at block C.

Referring to fig. 10 and 11, the secondary battery 300 according to the present embodiment includes: a housing 31 having an opening; an electrode assembly 32 housed in the case 31; and a cap assembly 30 connected to the case 31 and covering an opening of the case 31.

The cap assembly 30 includes: a cover plate 34 covering the opening of the case 31; two electrode terminals 35 protruding to the outside of the cap plate 34 and electrically connected to the electrode assembly 32; and a rupture disk 36 configured to rupture when the pressure inside the housing 31 reaches a set value. In one embodiment, the two electrode terminals 35 are electrically connected to the positive and negative electrode tabs of the electrode assembly 32 through the two current collecting members 33, respectively.

The cover plate 34 has a first through hole 342. The first through hole 342 penetrates the cap plate 34 to communicate the spaces at both sides of the cap plate 34. The cover assembly 30 further includes a fixing member 37, and the fixing member 37 is used to connect the cover plate 34. In some embodiments, the fixing member 37 is fixed to the cover plate 34 by welding.

The fixing member 37 has a second through hole 371, and the second through hole 371 is configured to be in gas communication with the first through hole 342. The gas in the first through hole 342 can freely flow into the second through hole 371, but of course, the gas in the second through hole 371 can freely flow into the first through hole 342.

The cover assembly 30 further includes a gas permeable membrane 38, the gas permeable membrane 38 being adapted to cover the second through-hole 371. The gas permeable film 38 is made of a polymer material (for example, PP) having gas permeable properties, and is capable of blocking liquid. The permeable membrane 38 and the fixing member 37 are connected as a whole and block the first through hole 342, so that the permeable membrane 38 and the fixing member 37 can block the electrolyte solution and prevent the electrolyte solution from leaking.

The cover assembly 30 further includes a protective film 39, and the protective film 39 is disposed on the side of the fixing member 37 away from the gas permeable membrane 38 and covers the second through hole 371. The gas permeable membrane 38 is located between the cover plate 34 and the fixing member 37, and the protective membrane 39 is located on the side of the fixing member 37 remote from the cover plate 34. In the secondary battery 300, the protective film 39 is exposed. The protective film 39 can prevent external impurities (such as liquid drops, particles, and the like) from entering the second through hole 371, prevent the impurities from adhering to the surface of the gas permeable membrane 38, prevent the reduction of the air permeability of the gas permeable membrane 38, and prevent the gas permeable membrane 38 from being damaged by machinery.

The gas permeability of the gas permeable membrane 38 is smaller than that of the protective film 39, and therefore, the gas release rate of the secondary battery 300 is determined by the gas permeable membrane 38.

In addition, the secondary battery 300 according to the present embodiment is formed to be identical or similar to the secondary battery 100 according to the first exemplary embodiment except for the protective film 39. Therefore, the description of the structure equivalent to or similar to that of the first exemplary embodiment is omitted here.

Fig. 12 is a sectional view of a secondary battery according to a fourth exemplary embodiment of the present application. Fig. 13 is an enlarged view of the secondary battery of fig. 12 at block D.

Referring to fig. 12 and 13, the secondary battery 400 according to the present embodiment includes: a housing 41 having an opening; an electrode assembly 42 housed in the case 41; and a cap assembly 40 connected to the case 41 and covering an opening of the case 41.

The cap assembly 40 includes: a cover plate 44 covering the opening of the case 41; two electrode terminals 45 protruding to the outside of the cap plate 44 and electrically connected to the electrode assembly 42; and a rupture disk 46 configured to rupture when the internal pressure of the housing 41 reaches a set value. In one embodiment, the two electrode terminals 45 are electrically connected to the positive and negative electrode tabs of the electrode assembly 42 through the two current collecting members 43, respectively.

The cover plate 44 has a first through hole 442. The first through hole 442 penetrates the cover plate 44 to communicate spaces at both sides of the cover plate 44. The cover assembly 40 further includes a fixing member 47, and the fixing member 47 is used to connect the cover plate 44. In some embodiments, the fixing member 47 is fixed to the cover plate 44 by welding.

The fixing member 47 has a second through hole 471, and the second through hole 471 is configured to be in gas communication with the first through hole 442. The gas in the first through hole 442 can freely flow into the second through hole 471, but the gas in the second through hole 471 can also freely flow into the first through hole 442.

The cover assembly 40 further includes a gas permeable membrane 48, the gas permeable membrane 48 being adapted to cover the second through hole 471. The gas permeable film 48 is made of a polymer material (for example, PP) having gas permeable characteristics, and is capable of blocking liquid. The gas permeable membrane 48 and the fixing member 47 are connected as a whole and block the first through hole 442, and therefore, the gas permeable membrane 48 and the fixing member 47 can block the electrolyte solution, and the electrolyte solution is prevented from leaking.

The secondary battery 400 according to the present embodiment is formed to be identical or similar to the secondary battery 100 according to the first exemplary embodiment, except for the cap plate 44. Therefore, description of the structure equivalent to or similar to that of the first exemplary embodiment will be omitted.

The cap plate 44 of the secondary battery 400 according to the present embodiment includes a main body portion 447 and a protrusion 448 protruding from the main body portion 447. The first through hole 442 penetrates the body portion 447 and the projection 448. By providing the protruding portion 448, the depth of the first through hole 442 can be increased, and the thickness of the air permeable membrane 48 and the fixing member 47 can be increased accordingly.

In some embodiments, the tab 448 protrudes beyond a side of the electrode assembly relative to the body portion 447; in an alternative embodiment, the tab 448 may also protrude beyond a side of the electrode assembly with respect to the body portion 447.

Claims

1. A cap assembly of a secondary battery, comprising:

a cover plate having a first through hole;

a fixture for connecting the cover plate, the fixture having a second through-hole configured to be in gaseous communication with the first through-hole;

and the breathable film is connected with the fixing piece through a chemical bond, and the breathable film is used for covering the second through hole.

2. The cover assembly of claim 1, wherein at least a portion of the vented membrane is sandwiched between the securing member and the cover plate.

3. The cover assembly of claim 1, wherein the first through-hole includes a receiving section and an extending section extending from the receiving section, the receiving section having a larger bore diameter than the extending section, the securing member being at least partially received in the receiving section.

4. The cover assembly of claim 3, wherein the receiving section has a bottom wall surrounding the extension section, and at least a portion of the gas permeable membrane is sandwiched between the fixing member and the bottom wall to separate the second through hole and the extension section.

5. The cover assembly of claim 3, wherein an aperture of the second through hole is smaller than an aperture of the extension section.

6. The lid assembly of any one of claims 1-5, wherein the fixture has a recess disposed around the second through-hole, the vented membrane being at least partially received in the recess.

7. The lid assembly as claimed in any one of claims 1 to 5, wherein the fixing member is welded to the cover plate, and a minimum distance between the gas permeable membrane and an outer edge of the fixing member is greater than 3 mm.

8. The cover assembly according to any one of claims 1 to 5, further comprising a protective film disposed on a side of the fixing member remote from the gas permeable film and covering the second through hole, and wherein the gas permeable film has a gas permeability smaller than that of the protective film.

9. The cover assembly as claimed in any one of claims 1 to 5, wherein the bonding surface of the gas permeable membrane and the fixing member is formed with a functional group bonded by chemical bond.

10. A secondary battery, characterized by comprising:

a housing having an opening;

an electrode assembly accommodated in the case; and

the cap assembly of any one of claims 1-9, attached to the housing and covering an opening of the housing.

11. A battery module characterized by comprising a plurality of secondary batteries according to claim 10.

12. A device using a secondary battery, comprising the secondary battery according to claim 10, which supplies electric energy.