CN211350858U

CN211350858U - Electrochemical device and electronic device

Info

Publication number: CN211350858U
Application number: CN202020400448.3U
Authority: CN
Inventors: 郭俊杰; 余红明; 周伯林
Original assignee: Ningde Amperex Technology Ltd
Current assignee: Ningde Amperex Technology Ltd
Priority date: 2020-03-25
Filing date: 2020-03-25
Publication date: 2020-08-25
Anticipated expiration: 2030-03-25

Abstract

The application provides an electrochemical device, including electrode assembly, first utmost point ear and second utmost point ear, electrode assembly includes pole piece and barrier film, and the pole piece includes first pole piece and second pole piece. The first pole piece comprises a first current collector and a first membrane arranged on the surface of the first current collector, the second pole piece comprises a second current collector and a second membrane arranged on the surface of the second current collector, and the first pole piece, the isolating membrane and the second pole piece are sequentially stacked and wound to form an electrode assembly. The starting end of the first pole piece is not provided with a blank section, the middle section of the first pole piece is provided with a first empty foil area, and the first tab is located in the first empty foil area and is electrically connected with the first current collector. The second pole piece initial end is not provided with a blank section, the second pole piece tail end is provided with a first blank section, and the second pole piece is positioned in the first blank section and is electrically connected with the second current collector. The electrochemical device has a small thickness and a high energy density. The application also provides an electronic device with the electrochemical device.

Description

Electrochemical device and electronic device

Technical Field

The present disclosure relates to the field of energy storage technologies, and more particularly, to an electrochemical device and an electronic device having the same.

Background

Electrochemical devices, such as batteries, have high energy density and are widely used in various electronic devices, such as mobile communication devices, notebooks, tablet computers, wearable devices, unmanned planes, and the like. As electronic devices tend to be miniaturized and intelligent, higher requirements are placed on the energy density and thickness of electrochemical devices, which requires more energy to be donated in a smaller volume.

At present, a common battery cell of an electrochemical device is a winding structure, and is formed by winding a first pole piece, a second pole piece with a polarity opposite to that of the first pole piece, and a separation film arranged between the first pole piece and the second pole piece. As shown in fig. 1, in the inner ring of the conventional winding type battery cell, blank sections need to be arranged at the starting ends of the first pole piece and the second pole piece, the first tab and the second tab are respectively welded to the blank sections of the first pole piece and the second pole piece, and the inner ring of the battery cell needs to be provided with multiple layers of isolation films, so that the electrochemical device has a large thickness and a low energy density.

Disclosure of Invention

In view of the above-mentioned deficiencies of the prior art, the present application provides an electrochemical device to solve at least one of the problems of the prior art.

The embodiment of the application provides an electrochemical device, including electrode assembly, first utmost point ear and second utmost point ear, electrode assembly includes pole piece and barrier film, and the pole piece includes first pole piece and second pole piece. The first pole piece comprises a first current collector and a first membrane arranged on the surface of the first current collector, the second pole piece comprises a second current collector and a second membrane arranged on the surface of the second current collector, and the first pole piece, the isolating membrane and the second pole piece are sequentially stacked and wound to form an electrode assembly. The first pole piece initiating terminal does not set up blank section, and the first pole piece interlude sets up first empty paper tinsel district, and first utmost point ear is located first empty paper tinsel district and is connected with the first mass flow body electricity, and the second pole piece initiating terminal does not set up blank section, and the second pole piece receipts tail end sets up first blank section, and the second utmost point ear is located first blank section and is connected with the second mass flow body electricity.

The application provides an electrochemical device all does not set up blank section at pole piece coiling initiating terminal, and electrode subassembly inside does not have the blank section that both sides all do not set up the active layer promptly, can reduce the thickness that the blank section occupy, reduces electrochemical device bulk thickness, improves volume utilization, and then improves electrochemical device's energy density. In addition, first utmost point ear setting has improved electrochemical device's high magnification charge-discharge properties at first pole piece interlude position.

In some embodiments, the number of layers of the separator film located at the innermost turn of the pole piece is less than 4. In the embodiment, the number of layers of the innermost ring of the pole piece is limited, so that the overall thickness of the electrochemical device can be further reduced, the volume utilization rate is improved, and the energy density is improved.

In some embodiments, the number of layers of the separator film located at the innermost turn of the pole piece is 2. In the embodiment, the inner ring of the pole piece is ensured to have enough isolating membrane, short circuit is prevented, safety is ensured, the thickness of the electrochemical device can be effectively reduced, and the energy density is improved.

In some embodiments, the first electrode sheet is a negative electrode sheet, the second electrode sheet is a positive electrode sheet, and the first blank section exceeds the tail end of the first current collector by at least half a turn. In the present embodiment, the positive electrode current collector protection waistcoat is formed on the outer ring of the electrochemical device, and the safety performance of the electrochemical device can be improved.

In some embodiments, the first pole piece is a positive pole piece, the second pole piece is a negative pole piece, and the separator extends beyond the first blank section by at least half a turn. In the embodiment, the isolating membrane exceeds the first blank section for at least half a circle, so that the negative current collector is wrapped by the isolating membrane, the negative current collector is prevented from being corroded due to contact with electrolyte, meanwhile, the isolating membrane has a certain buffering effect, and the safety performance of the electrochemical device in mechanical abuse can be improved.

In some embodiments, the first tab and the second tab are not coincident in a thickness direction of the electrode assembly. Thus, the thickness of the electrode assembly can be effectively reduced.

In some embodiments, the thickness of the first tab is less than the thickness of the first diaphragm. Therefore, the thickness of the electrode assembly can be effectively reduced, and the influence on the flatness of the interface can be avoided.

In some embodiments, the surface of the electrical connection portion of the first tab and the first current collector is covered with a first adhesive, and the surface of the electrical connection portion of the second tab and the second current collector is covered with a second adhesive. Thus, the risk of short circuits can be avoided.

In some embodiments, the electrochemical device further comprises a third tab, the middle section of the first pole piece is provided with a second empty foil area, and the third tab is positioned in the second empty foil area and electrically connected with the first current collector. The electrochemical device can further comprise a fourth tab, a fifth tab and the like which are electrically connected with the first current collector, wherein the higher the number of the tabs is, the better the high-rate output performance of the electrochemical device is.

The present application also provides an electronic device comprising the electrochemical device of any of the above embodiments.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic structural diagram of a wound battery cell in the background art.

Fig. 2 is a schematic structural diagram of an electrochemical device according to an embodiment of the present disclosure.

Fig. 3 is a partially enlarged view illustrating a first tab of the electrochemical device shown in fig. 2.

Fig. 4 is a partially enlarged view illustrating a second tab of the electrochemical device shown in fig. 2.

Fig. 5 is a schematic structural view of an electrochemical device according to another embodiment of the present disclosure.

Fig. 6 is a schematic structural view of an electrochemical device according to still another embodiment of the present disclosure.

Description of the main elements

Electrochemical device 100

Electrode assembly 10

First tab 20

Second tab 30

Pole piece 11

Isolation diaphragm 12

First pole piece 111

First current collector 1111

First membrane 1112

Second pole piece 112

Second current collector 1121

Second diaphragm 1122

First empty foil region 1113

First blank segment 1123

First adhesive member 40

Second adhesive member 50

Third pole ear 60

Second empty foil region 1114

The following detailed description will further illustrate the present application in conjunction with the above-described figures.

Detailed Description

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 apparent that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive effort based on the embodiments in the present application are within the scope of protection of the present application.

It is to be noted that, 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 embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application.

Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. Features in the following embodiments may be combined with each other without conflict.

As used herein, "start end" refers to a start position of the current collector, the membrane sheet, or the separator in the winding direction, and "end" refers to an end position of the current collector, the membrane sheet, or the separator in the winding direction, and "middle section" refers to a position of the current collector, the membrane sheet, or the separator between the start end and the end in the winding direction.

Referring to fig. 2, an embodiment of the present invention provides an electrochemical device 100, and the electrochemical device 100 may be a primary battery, a secondary battery, a capacitor, and the like, but is not limited thereto.

The electrochemical device 100 includes an electrode assembly 10, a first tab 20, and a second tab 30. The electrode assembly 10 includes a pole piece 11 and a separator 12, the pole piece 11 including a first pole piece 111 and a second pole piece 112. The first pole piece 111, the separator 12, and the second pole piece 112 are sequentially stacked and wound to form the electrode assembly 10.

Referring to fig. 2 to 4, the first electrode sheet 111 includes a first current collector 1111 and a first film 1112 disposed on a surface of the first current collector 1111. The first membrane 1112 contains a first active material.

The second pole piece 112 includes a second current collector 1121 and a second membrane 1122 disposed on a surface of the second current collector 1121. The second diaphragm 1122 contains a second active material.

The starting end of the first pole piece 111 is not provided with a blank section, the middle section of the first pole piece 111 is provided with a first empty foil area 1113, and the first tab 20 is located in the first empty foil area 1113 and electrically connected to the first current collector 1111.

The beginning end of the second pole piece 112 is not provided with a blank section, the ending end of the second pole piece 112 is provided with a first blank section 1123, and the second pole lug 30 is located in the first blank section 1123 and electrically connected to the second current collector 1121.

In one embodiment, the second pole ear 30 is located at the end of the first blank section 1123.

The 'empty foil area' is an area without a diaphragm on at least one surface of the current collector; the blank section is an area without membranes on both sides of the current collector. That is, the first empty foil region 1113 may be formed by forming a groove on the first film 1112, where the first active material is not disposed on one side of the first current collector 1111; the first empty foil area 1113 may also be formed by disposing no first active material on both sides of the first current collector 1111, and forming grooves on both diaphragms of the first current collector 1111. The groove may be formed by coating the first active material on the first current collector 1111, and then performing laser cleaning on a predetermined region to remove the first active material; the foaming adhesive may be applied to a predetermined region of the first current collector 1111 and heated to remove the foaming adhesive after the first active material is coated, but other ways are also possible, and the application is not limited thereto.

In the electrochemical device 100, no blank segment is disposed at the starting ends of the first and

second pole pieces

111 and 112; a first empty foil area is arranged in the middle section of the first pole piece 111, and the first tab 20 is located in the first empty foil area 1113; a first blank section 1123 is disposed at the end of the second pole piece 112, and the second pole ear 30 is disposed in the first blank section 1123. Compared with the prior art, the electrochemical device 100 reduces the layer of the first current collector 1111 and the layer of the second current collector 1121 of the inner ring, thereby reducing the influence of the hollow foil of the inner ring on the thickness, reducing the overall thickness of the electrochemical device 100, improving the volume utilization rate, and improving the energy density of the electrochemical device 100. In addition, the first tab 20 is disposed at the middle position of the first pole piece 111, so that the high-rate charge and discharge performance of the electrochemical device 100 is improved.

In one embodiment, the number of layers of the separator 12 located at the innermost circumference of the pole piece 11 is less than 4, so as to reduce the thickness of the electrochemical device 100. In this embodiment, limiting the number of layers of the innermost circle of the pole piece 11 can further reduce the overall thickness of the electrochemical device 100, improve the volume utilization rate, and improve the energy density.

In one embodiment, the number of the isolation films 12 located at the innermost circle of the pole piece 11 is 2, which not only ensures that the inner circle of the pole piece 11 has enough isolation films 12 to prevent short circuit and ensure safety, but also effectively reduces the thickness of the electrochemical device 100 and improves the energy density.

In an embodiment, the first pole piece 111 is a negative pole piece, the second pole piece 112 is a positive pole piece, the second pole piece 112 is located at an outermost circle of the electrode assembly 10, and the first blank section 1123 exceeds the ending end of the first current collector 1111 by at least half a circle, which is equivalent to forming a positive current collector vest on an outer circle of the electrochemical device 100, so as to protect a battery cell and improve the safety performance of the electrochemical device 100.

In one embodiment, the first blank section 1123 extends 1-5 circles beyond the trailing end of the first current collector 1111.

In one embodiment, the first blank section 1123 extends beyond the trailing end of the first current collector 1111 by 1-3 turns.

In an embodiment, the first tab 20 and the second tab 30 are not overlapped in the thickness direction of the electrode assembly 10 to effectively reduce the thickness of the electrode assembly 10.

In one embodiment, the first tab 20 is located in a first empty foil region 1113 of the first current collector 1111, and the first empty foil region 1113 is formed by removing a corresponding portion of the first film 1112 disposed on the first current collector 1111.

In one embodiment, the thickness of the first tab 20 is less than the thickness of the first film 1112, so as to effectively reduce the thickness of the electrode assembly 10 and avoid affecting the flatness of the interface.

In an embodiment, the thickness of the first tab 20 ranges from 60 μm to 150 μm, for example, the thickness of the first tab 20 may be 60 μm, 80 μm, 100 μm or 150 μm, but is not limited thereto.

Since the second tab 30 is located in the empty region 1123 of the second current collector 1121, the thickness range of the second tab 30 is not limited, and in an embodiment, the thickness of the second tab 30 may be 60 μm to 400 μm, but is not limited thereto. For example, the thickness of the second tab may be 60 μm, 80 μm, 100 μm, 150 μm, 200 μm, 400 μm, or the like.

Further, the first tab 20 is close to the start end of the first pole piece 111, and the second tab 30 is located at the end of the second pole piece 112, so that the first tab 20 and the second tab 30 are respectively located at two ends of the pole piece 11 in the length direction, and current is shunted when flowing through each layer of pole piece 11, thereby improving the current density distribution of the pole piece 11 in the length direction.

Referring to fig. 3 and 4, the first diaphragm 1112 covers two surfaces of the first current collector 1111, a first empty foil area 1113 without the first diaphragm 1112 exists on at least one surface of the first current collector 1111, and the first tab 20 is disposed in one of the first empty foil areas 1113 and electrically connected to the first empty foil area 1113.

The surface of the electrical connection portion between the first tab 20 and the first current collector 1111 is covered with a first adhesive 40.

In some embodiments, the side of the first current collector 1111 facing away from the first tab 20 is also covered with the first adhesive 40.

The surface of the electrical connection portion between the second tab 30 and the second current collector 1121 is covered with a second adhesive 50.

The first bonding piece 40 and the second bonding piece 50 are made of insulating glue, so that the risk of internal short circuit of the battery cell is avoided. The first adhesive member 40 and the second adhesive member 50 may be acrylate or polypropylene hydrocarbon adhesive, but are not limited thereto. Preferably, to reduce the influence of the adhesive on the thickness of the electrochemical device 100, the thickness of the first adhesive 40 and the second adhesive 50 may be less than 20 μm.

Referring to fig. 5, in another embodiment, the electrochemical device 100 further includes a third tab 60, the middle section of the first tab 111 is provided with a second empty foil region 1114, and the third tab 60 is located in the second empty foil region 1114 and electrically connected to the first current collector 1111.

It is understood that the electrochemical device 100 may further include a fourth tab, a fifth tab (not shown), and the like electrically connected to the first current collector 1111. The more the quantity of the lugs is, the better the high-rate output performance of the battery cell is.

Referring to fig. 6, in another embodiment, the first pole piece 111 is a positive pole piece, the second pole piece 112 is a negative pole piece, and the isolation film 12 extends beyond the first blank section 1123 by at least half a turn. Since the negative electrode tab is positioned at the outermost circle of the electrode assembly 10, the contact area of the copper foil of the negative current collector and the electrolyte is increased, and the copper foil is easy to corrode, and the separator 12 wraps the negative current collector, so that the corrosion of the negative current collector can be prevented.

In the electrochemical device 100 provided by the present application, no blank section is disposed at the starting ends of the first pole piece 111 and the second pole piece 112, and the first tab 20 is located in the first empty foil area 1113 of the first pole piece 111, so that a layer of first current collector 1111 in an inner ring of the electrode assembly 10 can be saved, and the flatness of the interface is improved; the second tab 30 is located in the first empty section 1123 of the second tab 112, which saves a layer of the second current collector 1121 on the inner ring of the electrode assembly 10. In addition, compared with the electrochemical device in the prior art, the electrochemical device 100 provided in an embodiment of the present disclosure can also reduce the number of layers of the inner ring separation film 12, reduce the thickness of the electrochemical device 100, and increase the energy density of the electrochemical device 100.

Further, since the first tab 20 and the second tab 30 are respectively located at two ends of the pole piece 11 in the length direction, the current is shunted when flowing through each layer of the pole piece 11, so as to improve the current density distribution of the pole piece 11 in the length direction and improve the rate capability of the electrochemical device 100.

The present application also provides an electronic device in which the electrochemical device 100 described above is employed. The electronic device may be one of consumer electronics, wearable equipment, unmanned aerial vehicle, power tool, energy storage device, or electric automobile, and the electrochemical device 100 is used to power the electronic device. It is understood that the electrochemical device 100 may be a battery. In yet other embodiments, the electrochemical device 100 may also be a capacitor.

The above disclosure is only for the purpose of illustrating the preferred embodiments of the present application and is not to be construed as limiting the scope of the present application, so that the present application is not limited thereto, and all equivalent variations and modifications can be made to the present application.

Claims

1. An electrochemical device comprises an electrode assembly, a first tab and a second tab, wherein the electrode assembly comprises a pole piece and a separation film, the pole piece comprises a first pole piece and a second pole piece,

the first pole piece comprises a first current collector and a first membrane arranged on the surface of the first current collector,

the second pole piece comprises a second current collector and a second membrane arranged on the surface of the second current collector,

the first pole piece, the separation film and the second pole piece are sequentially laminated and wound to form the electrode assembly,

it is characterized in that the starting end of the first pole piece is not provided with a blank section, the middle section of the first pole piece is provided with a first empty foil area, the first tab is positioned in the first empty foil area and is electrically connected with the first current collector,

the second pole piece initiating terminal does not set up blank section, the second pole piece receives the tail end and sets up first blank section, the second pole ear is located first blank section and with the second mass flow body electricity is connected.

2. The electrochemical device of claim 1, wherein said separator has less than 4 layers at the innermost turn of said pole piece.

3. The electrochemical device of claim 2, wherein the number of layers of said separator film positioned at the innermost circumference of said pole piece is 2.

4. The electrochemical device according to claim 1, wherein the first tab is a negative tab, the second tab is a positive tab, and the first blank section extends beyond the trailing end of the first current collector by at least half a turn.

5. The electrochemical device of claim 1, wherein said first pole piece is a positive pole piece, said second pole piece is a negative pole piece, and said separator extends at least half a turn beyond said first blank segment.

6. The electrochemical device according to claim 1, wherein the first tab and the second tab are not coincident in a thickness direction of the electrode assembly.

7. The electrochemical device of claim 1 wherein the thickness of said first tab is less than the thickness of said first membrane.

8. The electrochemical device according to claim 1, wherein a surface of an electrical connection portion of the first tab and the first current collector is covered with a first adhesive, and a surface of an electrical connection portion of the second tab and the second current collector is covered with a second adhesive.

9. The electrochemical device of claim 1, further comprising a third tab, said first pole piece intermediate section being provided with a second empty foil region, said third tab being located in said second empty foil region and being electrically connected to said first current collector.

10. An electronic device comprising the electrochemical device of any one of claims 1-9.