CN111009681A

CN111009681A - Energy storage device

Info

Publication number: CN111009681A
Application number: CN201911403010.9A
Authority: CN
Inventors: 童焰; 陈志勇
Original assignee: Guangdong Mic Power New Energy Co Ltd
Current assignee: Guangdong Mic Power New Energy Co Ltd
Priority date: 2019-12-30
Filing date: 2019-12-30
Publication date: 2020-04-14

Abstract

The embodiment of the invention discloses an energy storage device. This energy storage device includes: a housing and an energy conversion element, the housing comprising a first half-housing and a second half-housing; the first half shell and the second half shell respectively comprise a sunken structure and an edge part, the edge part is arranged around a mouth part of the sunken structure and is connected with the mouth part, the sunken structure of the first half shell and the sunken structure of the second half shell together enclose a cavity, the energy conversion element is arranged in the cavity, the edge part of the first half shell is hermetically connected with the edge part of the second half shell to form a sealing edge, one part of the sealing edge is bent towards a first side of the shell, and the other part of the sealing edge is bent towards a second side of the shell in a direction opposite to the first side.

Description

Energy storage device

Technical Field

The invention relates to the technical field of energy conversion, in particular to an energy storage device.

Background

Energy storage devices, such as pouch cells, typically include a jelly roll and two half shell jelly rolls that snap together and are assembled into the space enclosed by the two half shells. The two tabs of the winding core extend outwardly from the edges of the two half shells. The two half shells are insulated from each other. The half shells are, for example, aluminium-plastic films. The tab is also insulated from the two half shells. The edges of the two half shells are joined together by means of heat pressing. The plastic layer on the surface of the aluminum plastic film is made of thermoplastic materials, when the plastic layer is heated to a set temperature, the plastic layer on the aluminum plastic film obtains viscosity, the two edges are bonded together under the action of external pressure, and the lug and the two edges are bonded together.

In general, the edges that are bonded together protrude outward in such a way that the energy storage device is large in size and not conducive to assembly to other equipment. In some embodiments, the edges that are bonded together are bent toward one side and fit over the side walls of the housing. Traditional laminate polymer battery, packaging film banding all are to one side bending, but in this scheme, because the edge is cyclic annular banding, if towards one side bending, the casing can buckle usually and form the elastic deformation structure, so the easy size rebound of part of buckling influences size uniformity and assembly use, and the buckle still can occupy great space to the energy space utilization of restriction battery, battery energy density is lower. In addition, if the structural casing is made of a packaging material with high hardness and thickness, such as stainless steel foil, the strength is too high to form a good crease, and structural breakage may occur during the crease forming process to destroy the sealing performance.

Therefore, a new technical solution is needed to solve at least one of the above technical problems.

Disclosure of Invention

An object of the present invention is to provide a new solution for an energy storage device.

According to a first aspect of the invention, an energy storage device is provided. This energy storage device includes: a housing and an energy conversion element, the housing comprising a first half-housing and a second half-housing; the first half shell and the second half shell respectively comprise a sunken structure and an edge part, the edge part is arranged around a mouth part of the sunken structure and is connected with the mouth part, the sunken structure of the first half shell and the sunken structure of the second half shell together enclose a cavity, the energy conversion element is arranged in the cavity, the edge part of the first half shell is hermetically connected with the edge part of the second half shell to form a sealing edge, one part of the sealing edge is bent towards a first side of the shell, and the other part of the sealing edge is bent towards a second side of the shell in a direction opposite to the first side.

Optionally, the sealing rim is conformed over the outer surface of the housing.

Optionally, the conducting part is arranged on the recessed structure, and the conducting part is connected with the energy conversion element.

Optionally, the sealing edge is bonded to the outer surface of the housing by glue.

Optionally, the housing is a rectangular parallelepiped, at least one of four corners of the sealing edge is bent toward the first side, and a portion of the sealing edge other than the corner is bent toward the second side.

Optionally, at least two positions of the sealing edge are bent towards the first side, and the parts of the sealing edge, which are located outside the at least two positions, are bent towards the second side.

Optionally, the at least two locations are evenly distributed along a circumference of the sealing edge.

Optionally, the edge portion of the first half shell and the edge portion of the second half shell are connected by a thermoplastic material.

Optionally, the first half shell and the second half shell have the same height, and the sealing edge has the same width as the first half shell.

Optionally, at least one of the first half shell and the second half shell comprises a metal layer and two thermoplastic material layers, the metal layer is located between the two thermoplastic material layers, the two thermoplastic material layers form a hollow structure at a corresponding position to expose the metal layer, and the metal layer is connected with the energy conversion element.

According to one embodiment of the present disclosure, a portion of the sealing edge is bent toward the first side and another portion is bent toward the second side, rather than being bent toward one side as a whole. In this way, the resilience of the two side bends can be cancelled out, thereby preventing the sealing edge from coming off the side wall of the housing.

Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.

Fig. 1 is an exploded view of a pouch cell during assembly according to an embodiment of the present disclosure.

Fig. 2 is an exploded view of one half shell according to an embodiment of the present disclosure.

Fig. 3 is a cross-sectional view of a pouch cell that has not been evacuated according to an embodiment of the present disclosure.

Fig. 4 is a cross-sectional view of a pouch cell after evacuation in accordance with an embodiment of the present disclosure.

Fig. 5 is a perspective view of another pouch battery according to an embodiment of the present disclosure

Fig. 6 is a cross-sectional view of a pouch cell according to an embodiment of the present disclosure.

Fig. 7 is a perspective view of yet another pouch battery according to an embodiment of the present disclosure.

Fig. 8 is a side view of yet another pouch cell in accordance with an embodiment of the present disclosure.

Detailed Description

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

According to one embodiment of the present disclosure, an energy storage device is provided. As shown in fig. 1-4, the energy storage device may be, but is not limited to, a capacitor, a battery, or the like. The battery is a primary battery or a secondary battery. The following description will be given by taking a lithium ion battery as an example. For example, the lithium ion battery is a pouch battery or a button battery.

The energy storage device includes a housing and an energy conversion element. The energy conversion element is used for conversion between chemical energy and electrical energy. For example, the energy conversion element includes a winding core 11. The core 11 is a wound structure or a laminated structure. The wound structure, i.e., the entire electrode sheet (e.g., the electrode sheet includes a positive electrode sheet, a negative electrode sheet, and a separator between the positive and negative electrode sheets) is wound into a spiral structure. The laminated structure, i.e., the electrode sheet, is divided into a plurality of sheets. A plurality of sheets are laminated together.

The energy conversion element is of a block structure. Such as a rectangular parallelepiped structure, a cylindrical structure, an elliptical cylinder structure, etc. An electrode terminal is bonded to at least one surface of the energy conversion element. The electrode terminals are connected to the electrodes of the energy conversion element. The electrode terminals are, for example, tabs 111. The tab 111 is a nickel plate or the like. The electrode terminals may be empty foil areas of the pole pieces of the winding core 11. The empty foil area is the part of the pole piece which is not covered with the electrode active material.

The housing comprises a first housing half 12 and a second housing half 13. The inside of the shell forms a closed cavity. The first half shell 12 and the second half shell 13 each include a recessed feature 14 and an edge portion 155. The rim portion 155 is disposed around and connected to the mouth of the recessed feature 14. The recessed structure 14 of the first half shell 12 and the recessed structure 14 of the second half shell 13 together enclose a cavity.

The energy conversion element is disposed within the cavity. The edge portion 155 of the first half shell 12 is sealingly connected 15 to the edge portion 155 of the second half shell 13 to form a sealing edge 15. The sealing connection 15 is formed, for example, by means of gluing, welding, hot-melt connection or the like.

A portion of the sealing edge 15 is bent towards a first side 15a of the housing and another portion is bent towards a second side 15b of the housing opposite to the first side 15 a. For example, the first side 15a is the side near the side wall of the first housing half 12; the second side 15b is the side adjacent to the second half-shell side wall.

As shown in fig. 4 and 5, the housing has a rectangular parallelepiped structure, a cylindrical structure, an elliptic cylindrical structure, or the like. The setting can be carried out by the person skilled in the art according to the actual need.

In the disclosed embodiment, a portion of the sealing edge 15 is bent toward the first side 15a and another portion is bent toward the second side 15b, rather than being bent entirely toward one side. In this way, the resilience of the two lateral bends can cancel each other out, preventing the sealing edge 15 from coming off the side wall of the housing.

Furthermore, the two-sided bending results in a larger circumferential distance of the sealing edge 15 than the one-sided bending, and a part of the sealing edge 15 is overlapping. In this way, the sealing edge 15 can be uniformly applied to the outer surface of the shell after bending without forming wrinkles. The surface of the energy storage device is flat.

In other examples, the sealing edge 15 is a set distance from the outer surface of the housing after bending, rather than abutting against the outer surface.

In one example, as shown in fig. 1, the conducting portion is provided on the recessed structure 14, and the conducting portion is connected to the energy conversion element. For example, the conductive part is a metal sheet 115, and the energy conversion element is connected to an external device through the metal sheet 115. The conducting part is used as an electrode of the energy storage device.

Of course, the conductive portion may be an exposed metal layer, as described below.

In one example, the sealing edge 15 is glued to the outer surface of the housing by glue. In this way, the sealing edge 15 can be more firmly fixed to the outer surface of the housing.

In one example, as shown in fig. 5, the housing is a rectangular parallelepiped. At least one of the four corners of the sealing edge 15 is bent towards the first side 15 a. The portion of the sealing edge 15 other than the corner portion is bent toward the second side 15 b.

For example, four corners are each bent toward the first side 15 a. In this example, the corner portions are bent in a direction opposite to the bending direction of the other portions. In this way, the sealing edge 15 is spaced further apart in the circumferential direction and overlaps a greater area. The sealing edge 15 fits more tightly against the outer surface of the housing.

In one example, at least two portions of the sealing edge 15 are bent toward the first side 15a, and portions of the sealing edge 15 other than the at least two portions are bent toward the second side 15 b. For example, as shown in fig. 7-8, the housing is generally cylindrical in shape. The two portions of the sealing edge 15 are bent toward the first side 15a, and the two portions are disposed opposite to each other. This makes the bending of the sealing edge 15 more stable.

For example, the at least two points are evenly distributed along the circumferential direction of the sealing edge 15. In this way, the sealing edge 15 is more evenly stressed throughout and retains a higher ability to bend.

In one example, the first half-shell 12 and the second half-shell 13 are equal in height. The width of the sealing edge 15 is equal to the height of the first half shell 12 (shown as b in fig. 5). In this way, the outer edge of the sealing edge 15 can be flush with the upper and lower surfaces of the housing after bending, which makes the appearance of the housing more regular.

According to another embodiment of the present disclosure, a method of manufacturing an energy storage device is provided. The manufacturing method comprises the following steps:

placing the energy conversion element into the cavity with the electrode terminal opposite the conductive portion of the housing;

and vacuumizing the cavity, and pressing the conduction part on the electrode terminal by utilizing atmospheric pressure. When the vacuum is pumped, the air pressure in the cavity is less than the atmospheric pressure. The local deformation of the shell is generated under the action of atmospheric pressure. The conduction part is gradually close to the electrode terminal, finally contacts with the electrode terminal and is tightly attached together. During charging and discharging, the winding core 11 is electrically connected to an external circuit through the electrode terminal and the conductive portion.

In the embodiment of the present disclosure, the conducting portion of the case is brought into contact with the electrode terminal by atmospheric pressure by evacuating the cavity. Compared with the method of connecting the two by welding. In this way, the energy conversion element is not affected by high temperatures, thereby maintaining good energy conversion performance.

Furthermore, when gas is present in the energy storage device, for example when the internal pressure is greater than atmospheric pressure, the housing gradually expands due to the internal pressure. The conduction part gradually moves away from the energy conversion element until being separated from the electrode terminal. Thus, the conducting part and the electrode terminal are disconnected, and the charging and discharging are stopped. In this way, explosion of the energy storage device can be effectively avoided.

Fig. 1 is an exploded view of a pouch cell during assembly according to an embodiment of the present disclosure. In this example, the housing comprises a first half-housing 12 and a second half-housing 13 sealingly connected together. The first half shell 12 and the second half shell 13 each include a recessed feature 14 and an edge portion 155 formed by extending outwardly around an edge of the recessed feature 14. The edge portion 155 is configured to be used for sealing connection, the recessed structure 14 constitutes at least a part of the cavity, and the conduction portion is provided on the recessed structure 14. In one example, the two recessed features 14 are opposed when assembled. The rim portions 155 of the first half shell 12 and the second half shell 13 are brought together to form a sealed rim. For example, thermoplastic material is provided at the edge portion 155, and the edge portions 155 of the first half shell 12 and the second half shell 13 are joined together by heat-pressing.

For example, the first half-shell 12 and the second half-shell 13 are both made of a metal plastic film, such as an aluminum plastic film, a steel plastic film, or the like. The plastic material on the metal plastic film can form sealing connection in a hot pressing mode.

It is also possible that the first half-shell 12 and the second half-shell 13 are plastic, such as Polyetherketone (PEK), Polyetheretherketone (PEEK), polypropylene (PP), etc. The materials are thermoplastic materials and can be connected in a hot pressing mode.

In one example, before the evacuating the cavity, the method further comprises: and injecting electrolyte into the cavity. For example, the cavity has a rectangular parallelepiped shape, and after the energy conversion element is placed in the cavity, edge portions 155 on three sides (e.g., three short sides 155b) of the rectangular parallelepiped are sealed. The pouring outlet 151 is formed in the edge portion 155 of the other side (for example, the long side 155 a). The liquid injection port 151 is configured to inject an electrolyte.

For example, the short sides 155b of the edge portions 155 of the two half shells are sealed. The long side 155a is not completely sealed to form the pouring outlet 151. For example, the edges of the long sides 15a are connected to form a pocket. The bag part is used for containing gas generated during activation. The electrolyte is a carrier for ion transport. For example, lithium ions migrate in the electrolyte solution to perform charge and discharge.

After the electrolyte is injected, the shell is sealed for the first time. For example, the electrolyte is injected into the chamber at the injection port 151. After the filling is completed, the first sealing is performed to seal the filling opening 151.

And a formation step of pressing the conductive part against the electrode terminal by mechanical pressure. For example, the conductive portion is pressed outward toward the electrode terminal to bring the conductive portion into contact with the electrode terminal. The winding core 11 is charged and discharged under the condition of maintaining the contact, so that the energy storage device is subjected to a formation process.

In this example, since the conductive portion and the electrode terminal are opposed to each other, the conductive portion and the electrode terminal can be electrically connected to each other only by applying mechanical pressure. The operation is easy in the formation.

In addition, in the case where the winding core 11 is defective, the conductive part and the electrode terminal can be separated from each other at any time, so that the winding core 11 can be easily replaced.

In one example, after the evacuation of the cavity, a second sealing of the housing is included. For example, after the formation step is completed, the first sealing portion is opened, and for example, the first sealing portion is cut on the side close to the core 11 to form the opening 152. A vacuum is drawn at the opening 152. At this time, the gas in the chamber and the excess electrolyte are exhausted from the opening 152. Due to the action of atmospheric pressure, the conduction part and the electrode terminal are pressed together to make contact.

After the evacuation is completed, a second seal is made on the long side 155a to close the case. And finally forming the complete energy storage device.

In one example, as shown in fig. 3-4, the cavity is cylindrical. The energy conversion element is cylindrical. Electrode terminals are provided on both end faces of the energy conversion element, respectively. And conduction parts are respectively arranged at the parts of the shell corresponding to the two end surfaces of the cavity.

For example, the bottoms of the first half case 12 and the second half case 13 are each provided with a conduction portion. The electrode terminals correspond to the conduction parts one to one. In this example, the two conduction portions are disposed opposite to each other, which makes it easy to connect the energy storage device to the external apparatus.

In one example, as shown in fig. 3-4, at least one of the first half shell and the second half shell includes a metal layer and two layers of thermoplastic material. The metal layer is located between two of the thermoplastic material layers. And hollow structures are formed at corresponding positions of the two thermoplastic material layers to expose the metal layer. The metal layer is connected to the energy conversion element. Forming a window structure 121 on the thermoplastic material layer, wherein the part of the metal layer located in the window structure 121 is the conducting part. For example, the housing is a multi-layer composite structure. The thermoplastic material layer is made of PP, PEEK, PEK and the like. Thermoplastic material layers are arranged on the upper surface and the lower surface of the metal layer. The window structure 121 is formed at a predetermined portion of the thermoplastic material layer by etching or scraping, so that the conductive portion is exposed in the window structure 121. In this way, the conduction portion is directly formed on the housing, which makes the provision of the conduction portion easy.

In one example, as shown in fig. 2-4, the fenestration 121 is a via. The conductive part is a metal sheet 115, and for example, the metal sheet 115 is circular, rectangular, elliptical, semicircular, or the like. At the edge of the metal sheet 115 a ring of thermoplastic material, for example plastic ring 116, is arranged. When hot pressing is performed, the rings of thermoplastic material melt and acquire tackiness. The ring of thermoplastic material is bonded to the edge of the through hole thereby closing the metal sheet 115 off the through hole. The metal sheet 115 serves as a conduction portion.

In one example, as shown in fig. 6, a stem 112 is provided inside the energy conversion element. The end of the stem 112 is opposite to the electrode terminal. For example, the stem 112 is made of an insulating material, such as plastic, ceramic, or glass. The stem 112 is shaped as a cylinder, a square column, an elliptical column, a polygonal column, or the like.

For example, the winding core 11 is wound around the stem 112. Electrode terminals are provided at both ends of the winding core 11 in the axial direction. The two electrode terminals are respectively abutted against both ends of the stem 112. When the vacuum is drawn, the stem 112 can press the electrode terminal together with the conduction part, so that the electrode terminal and the conduction part can be in good contact.

The core column 112 can also play a supporting role, and the core column 112 enables the shell not to be easily deformed due to external force extrusion, so that the structural strength of the energy storage device is improved.

In other examples, the core 11 is a laminated structure. The stems 112 are perpendicular to the surface of each layer. A core leg 112 penetrating each layer is provided in the middle of the winding core 11. The stem 112 also functions as a support for the electrode terminals.

In one example, as shown in fig. 6, a bump 118 is provided at a portion of the conductive portion and/or the electrode terminal for contact. For example, bumps 118 are provided on the electrode terminals. The plurality of bumps 118 are arranged in a matrix. When the evacuation is performed, the bumps 118 are first brought into contact with the conductive portions. The conductive portion forms a pit due to the action of atmospheric pressure. The bumps 118 are fitted into the recesses, and the electrode terminals can be effectively prevented from moving relative to the conductive portion.

Further, the bump 118 can increase the contact area of the conduction portion and the electrode terminal when the conduction portion and the electrode terminal are completely press-fitted, and the conduction portion and the electrode terminal are brought into contact spatially, not only in a plane. This makes the electrical connection of the two more stable.

In one example, as shown in fig. 1, a metal having an atomic number of nickel or more in the periodic table or an alloy of the above metal, for example, a sheet made of gold, silver or the like is provided between the electrode terminal and the conductive portion, and by providing an intermediate metal layer 119, the connection between the electrode terminal and the conductive portion is made stronger and the conductive action is more remarkable; or

The electrode terminal is a metal with an atomic number of more than nickel in the periodic table or an alloy of the metal, and the type of the metal is as described above. In this example, the tab 111 or the electrode sheet is made of a metal of nickel or more, which has a low resistance, generates a small amount of heat during charge and discharge, and is safe and reliable; or

The electrode terminal is a composite structure of multiple layers of metals, wherein one layer is a metal with an atomic number of nickel or more in a periodic table of elements or an alloy of the metal, for example, the tab 111 or the electrode sheet is formed by compounding at least two metal layers. In this way, the conductivity and structural strength of the electrode terminal are higher; or

And the electrode terminal is doped with metal with the atomic number more than nickel in the periodic table. The material has good conduction effect.

In one example, as shown in fig. 1, an insulating member 117 is disposed between the electrode terminals and the energy conversion elements. For example, the insulating member 117 is made of plastic, rubber, silicone, or the like. The insulating member 117 prevents the electrode terminal from contacting the jelly roll 11, thereby preventing the formation of a short circuit.

Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. An energy storage device, comprising: a housing and an energy conversion element, the housing comprising a first half-housing and a second half-housing;

the first half shell and the second half shell respectively comprise a sunken structure and an edge part, the edge part is arranged around a mouth part of the sunken structure and is connected with the mouth part, the sunken structure of the first half shell and the sunken structure of the second half shell together enclose a cavity, the energy conversion element is arranged in the cavity, the edge part of the first half shell is hermetically connected with the edge part of the second half shell to form a sealing edge, one part of the sealing edge is bent towards a first side of the shell, and the other part of the sealing edge is bent towards a second side of the shell in a direction opposite to the first side.

2. The energy storage device of claim 1, wherein said sealing edge is conformed to an outer surface of said housing.

3. The energy storage device according to claim 1, wherein the conduction portion is provided on the recessed structure, the conduction portion being connected to the energy conversion element.

4. The energy storage device of claim 1, wherein: the sealing edge is bonded to the outer surface of the housing by glue.

5. The energy storage device of claim 1, wherein: the casing is the cuboid, at least one in four corners of sealed edge to first side bending, the position that is located outside this bight of sealed edge is to second side bending.

6. The energy storage device of claim 1, wherein: at least two positions of the sealing edge are bent towards the first side, and the parts of the sealing edge, which are positioned outside the at least two positions, are bent towards the second side.

7. The energy storage device of claim 6, wherein: the at least two locations are evenly distributed along the circumference of the sealing edge.

8. The energy storage device of claim 1, wherein: the edge portion of the first half shell and the edge portion of the second half shell are connected by a thermoplastic material.

9. The energy storage device of claim 1, wherein: the first half shell and the second half shell are equal in height, and the width of the sealing edge is equal to the height of the first half shell.

10. The energy storage device of claim 1, wherein: at least one of the first half shell and the second half shell comprises a metal layer and two thermoplastic material layers, the metal layer is located between the two thermoplastic material layers, hollow structures are formed on the two thermoplastic material layers at corresponding positions to expose the metal layer, and the metal layer is connected with the energy conversion element.