Electrochemical device and electronic device

Abstract

The invention discloses an electrochemical device and an electronic device. The electrochemical device comprises a pole piece and a pole lug, wherein the pole piece comprises a current collector, a first active material layer and a first insulating layer; the current collector comprises a first part of a first region, a second region and a third region, the first region is provided with a first active material layer, and the second region is provided with a first insulating layer. The orthographic projection of the second region at least partially surrounds the orthographic projection of the first part of the third region in the thickness direction of the current collector, and the first region and the second region are arranged in the length direction of the current collector. According to the pole piece disclosed by the invention, the exposed conductive area is relatively small, so that the safety risk can be reduced, for example, the risk of short circuit is reduced when an electrochemical device is punctured.

Description

[0001] This application is a divisional of the invention patent (application number 2021800061446, application date 2021-07-06, invention name "Electrochemical device and electronic device"). Technical Field

[0002] The present application relates to the field of battery technology, and in particular to an electrochemical device and an electronic device. Background Art

[0003] With the widespread application of 4G and the advent of the 5G era, lithium-ion batteries have been widely used in mobile phones, smart bracelets, AR, VR and other fields. The application scenarios are becoming more and more complex, and the interaction with people is becoming more and more frequent. The new scenarios have higher and higher requirements for the safety performance of the battery cells, especially the mechanical safety performance, such as needle puncture and heavy object impact.

[0004] A lithium-ion battery includes a current collector and a tab electrically connected to the current collector. As an example, the tab may be welded to the current collector. In the manufacturing process of lithium-ion batteries, in order to reserve a position for the tab welding, the current collector has a large area of ​​exposed aluminum foil, which is a safety weakness. A solution is needed to solve the above problem. Summary of the invention

[0005] In view of the prior art, the embodiments of the present application provide an electrochemical device and an electronic device to improve the problem of a larger exposed conductive area of ​​an electrode resulting in a higher safety risk.

[0006] In the first aspect, an embodiment of the present application provides an electrochemical device, including a pole piece and a pole ear, wherein the pole piece includes a current collector, a first active material layer and a first insulating layer. The current collector includes a first surface and a second surface arranged opposite to each other; the first surface of the current collector includes a first region, a second region and a first part of a third region, the first region is provided with a first active material layer, the second region is provided with a first insulating layer, the orthographic projection of the second region along the thickness direction of the current collector at least partially surrounds the orthographic projection of the first part of the third region along the thickness direction of the current collector, the first part of the third region where the first insulating layer is not provided is the conductive region exposed by the pole ear, and the first region and the second region are arranged along the length direction of the current collector. The technical effects included in the embodiments of the present application are as follows: the exposed area of ​​the current collector (including the first part of the third region) is small, so that the conductive area exposed by the pole piece is small, which can reduce safety risks, for example, reduce the risk of short circuit when the electrochemical device is punctured.

[0007] In some embodiments of the present application, the pole tab is arranged on the current collector, and the orthographic projection of the first part of the third region along the thickness direction of the current collector partially surrounds the orthographic projection of the pole tab along the thickness direction of the current collector. The current collector includes: a first end, a second end, a third end, and a fourth end. The first end and the second end are arranged along the first direction, the first direction is the width direction of the current collector, the first end includes the first side of the current collector, and the second end includes the second side of the current collector; the third end and the fourth end are arranged along the second direction, the second direction is the length direction of the current collector, the third end includes the third side of the current collector, and the fourth end includes the fourth side of the current collector. Along the first direction, the first part of the third region is arranged at the first end, and along the second direction, the first part of the third region is arranged at the third end. The pole tab includes the first side of the pole tab, the second side of the pole tab, the third side of the pole tab, and the fourth side of the pole tab. The first side of the pole tab and the second side of the pole tab are arranged oppositely along the first direction, and along the first direction, the distance between the second side of the pole tab and the second side of the current collector is less than the distance between the first side of the pole tab and the second side of the current collector. The third side of the pole lug and the fourth side of the pole lug are arranged relative to each other along the second direction, and along the second direction, the distance between the third side of the pole lug and the third side of the current collector is less than the distance between the fourth side of the pole lug and the third side of the current collector. The first part of the third region includes: the first side of the first part, the second side of the first part, the third side of the first part, and the fourth side of the first part. The first side of the first part and the second side of the first part are arranged relative to each other along the first direction, and along the first direction, the second side of the first part is adjacent to the second side of the pole lug. The third side of the first part and the fourth side of the first part are arranged relative to each other along the second direction, wherein, along the second direction, the third side of the first part is adjacent to the third side of the pole lug, and the fourth side of the first part is adjacent to the fourth side of the pole lug. Some embodiments of the present application include the following technical effects: a certain distance is provided between each side edge of the pole lug and each side edge of the first portion of the third region; by controlling the distance, for example, reducing the distance between two adjacent side edges, the conductive area exposed by the pole piece can be further reduced; in addition, when the pole lug is connected to the first portion of the third region, contact between the pole lug and the first insulating layer of the first portion adjacent to the third region is avoided, which is beneficial to improving the stability of the connection between the pole lug and the first portion of the third region.

[0008] In some embodiments of the present application, along the first direction, the distance between the second side of the first part and the second side of the pole ear is L2, the distance between the third side of the first part and the third side of the pole ear is L3, and the distance between the fourth side of the first part and the fourth side of the pole ear is L4, which satisfies at least one of the following conditions: a1) L2≤10mm; b1) L3≤10mm; c1) L4≤10mm. Some embodiments of the present application include technical effects: the distance between each side of the pole ear and each side of the first part of the third region is small, which can further reduce the conductive area exposed by the pole piece.

[0009] In some embodiments of the present application, the orthographic projection of the second region along the thickness direction of the current collector surrounds the orthographic projection of the third region along the thickness direction of the current collector. Technical effects included in some embodiments of the present application: The exposed region of the current collector only includes a first part of the third region, such that the conductive region exposed by the electrode tab is relatively small, which can reduce safety risks. For example, when performing a puncture operation on the electrochemical device, the risk of short circuit can be reduced.

[0010] In some embodiments of the present application, the distance W1 between the first side of the first part and the first side of the current collector satisfies 0 < W1 ≤ 10 mm. Technical effects included in some embodiments of the present application: In the scenario of cutting a single electrode tab from a whole electrode tab blank, the existence of cutting process errors is allowed, and the cutting process precision is reduced.

[0011] In some embodiments of the present application, along the second direction, the difference degree between the length of the first side of the first part and the length of the second side of the first part is not greater than 5%. Technical effects included in some embodiments of the present application: While improving the electrical connection stability between the tab and the electrode tab, the conductive region exposed by the electrode tab is relatively small.

[0012] In some embodiments of the present application, the orthographic projection of the second region along the thickness direction of the current collector and a part of the orthographic projection of the first side of the current collector along the thickness direction of the current collector jointly surround the orthographic projection of the first part of the third region along the thickness direction of the current collector. Technical effects included in some embodiments of the present application: When observing along the thickness direction of the current collector, the first side of the first part coincides with the first side of the current collector. In the scenario of cutting a single electrode tab from a whole electrode tab blank, the cutting process is precise, such that the conductive region exposed by the electrode tab conforms to the design.

[0013] In some embodiments of the present application, the difference degree between the length of the first side of the first part and the length of the second side of the first part is greater than 5%. Technical effects included in some embodiments of the present application: While improving the electrical connection stability between the tab and the electrode tab, the conductive region exposed by the electrode tab is relatively small.

[0014] In some embodiments of the present application, the length of the first side of the first part is less than the length of the second side of the first part. Technical effects included in some embodiments of the present application: The superposition of the tab and the first insulating layer is reduced, the thickness of the electrochemical device is decreased, which is beneficial to improving the energy density of the electrochemical device.

[0015] In some embodiments of the present application, each of the third side and the fourth side of the first part independently includes an arc portion or a quasi-arc portion, and the arc portion or the quasi-arc portion is disposed at the first end. Technical effects included in some embodiments of the present application: The superposition of the tab and the first insulating layer at the third end of the current collector is reduced, the thickness of the electrochemical device is decreased, which is beneficial to improving the energy density of the electrochemical device.

[0016] In some embodiments of the present application, along the first direction, the extension length of the arc portion or quasi-arc portion is not greater than 10 mm. Technical effects included in some embodiments of the present application: By controlling the extension length of the arc portion or quasi-arc portion to be relatively small and the area of the arc-shaped notch to be small, the arc-shaped notch will not affect the stability of the connection between the tab and the first part of the third region.

[0017] In some embodiments of the present application, the third region further includes a second part. Along the first direction, the second part of the third region is disposed at the second end. Technical effects included in some embodiments of the present application: In the scenario of cutting a single electrode from a whole electrode blank, the existence of cutting process errors is allowed, and the cutting process precision is reduced.

[0018] In some embodiments of the present application, along the thickness direction of the current collector, the orthographic projection of the second region and the orthographic projection of the second side of the current collector together surround the orthographic projection of the second part of the third region. Technical effects included in some embodiments of the present application: There is a certain distance between the second part of the third region and the first part of the third region, and a first insulating layer is provided between these two parts. Even if there are cutting process errors, the exposed conductive area of the electrode can be made relatively small, thereby still reducing the safety risk.

[0019] In some embodiments of the present application, the second part of the third region includes: a first side of the second part, a second side of the second part, a third side, and a fourth side of the second part. The first side of the second part and the second side of the second part are oppositely disposed along the first direction. Along the first direction, the first side of the second part is adjacent to the second side of the current collector, and the second side of the second part coincides with the second side of the current collector; the third side of the second part and the fourth side of the second part are oppositely disposed along the second direction. The second part of the third region satisfies at least one of the following conditions: a2) Along the first direction, the distance W2 between the first side of the second part and the second side of the current collector satisfies 0 < W2 ≤ 10 mm; b2) Along the second direction, the difference degree between the length of the first side of the second part and the length of the second side of the first part is not greater than 5%; c2) The third side of the second part and the third side of the first part are on a straight line; d2) The fourth side of the second part and the fourth side of the first part are on a straight line. Technical effects included in some embodiments of the present application: The size of the second part of the third region is made relatively small, further reducing the exposed conductive area of the electrode.

[0020] In some embodiments of the present application, the pole piece includes a second active material layer and a second insulating layer, the second surface of the current collector includes a fourth region, a fifth region and a sixth region, the fourth region is provided with a second active material layer, the fifth region is provided with a second insulating layer, and the orthographic projection of the fifth region along the thickness direction of the current collector at least partially surrounds the orthographic projection of the sixth region along the thickness direction of the current collector. Some embodiments of the present application include the following technical effects: the sixth region allows single-sided welding and double-sided forming during welding, which is conducive to improving the stability of welding between the pole ear and the first part of the third region.

[0021] In some embodiments of the present application, the sixth region and the third region satisfy one of the following conditions: a3) the orthographic projection of the sixth region along the thickness direction of the current collector falls within the orthographic projection of the third region along the thickness direction of the current collector; b3) the orthographic projection of the third region along the thickness direction of the current collector falls within the orthographic projection of the sixth region along the thickness direction of the current collector; c3) the orthographic projection of the sixth region along the thickness direction of the current collector coincides with the orthographic projection of the third region along the thickness direction of the current collector. Some embodiments of the present application include the following technical effects: along the thickness direction of the current collector, the sixth region and the third region at least partially overlap, which is conducive to improving the stability of welding the tab to the third region.

[0022] In some embodiments of the present application, the third region includes a blank area where the current collector is exposed. Some embodiments of the present application include technical effects: the current collector is directly connected to the tab, which is conducive to reducing the overlap of the tab at the third end of the current collector, reducing the thickness of the electrochemical device, and improving the energy density of the electrochemical device.

[0023] In some embodiments of the present application, the third region is provided with a coating, and the tab is connected to the current collector through the coating. Some embodiments of the present application include the following technical effects: the coating can facilitate the stable connection between the tab and the current collector, and facilitate the realization of good electrical contact between the two.

[0024] In some embodiments of the present application, the thermal conductivity of the coating is greater than the thermal conductivity of the current collector. Some embodiments of the present application include the following technical effects: it is beneficial to conduct the heat generated inside the current collector and the electrochemical device to the tab and to the outside through the coating, which is beneficial to the heat dissipation of the electrochemical device.

[0025] In some embodiments of the present application, the first insulating layer includes a first insulating material, and the first insulating material includes at least one of a combination of aluminum oxide, aluminum hydroxide, silicon oxide, boehmite, titanium oxide, and zirconium oxide. Some embodiments of the present application include technical effects: good electrical insulation performance.

[0026] In some embodiments of the present application, the first active material layer includes an active material, and the active material includes at least one of a combination of a lithium transition metal composite oxide and a lithium transition metal phosphate compound. Some embodiments of the present application include technical effects: it is conducive to electrochemically absorbing and releasing metal ions.

[0027] In a second aspect, an embodiment of the present application provides an electronic device, comprising a load and an electrochemical device as described in any one of the above items, wherein the electrochemical device supplies power to the electronic device.

[0028] In the electrochemical device and electronic device of the present application, along the thickness direction of the current collector, the orthographic projection of the second area of ​​the current collector at least partially surrounds the orthographic projection of the first part of the third area, so that along the width direction of the current collector of the electrode, the length of the conductive area exposed by the electrode is less than the length of the electrode, the conductive area exposed by the electrode is smaller, and after the electrode is connected to the electrode ear, the area of ​​the electrode not covered by the electrode ear is smaller, which can reduce safety risks, for example, reduce the risk of short circuit when performing a puncture operation on the electrochemical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of the structure of an electrochemical device according to an embodiment of the present application;

[0030] Figure 2 This is a schematic diagram of the structure of the pole piece blank of the first embodiment of the present application;

[0031] Figure 3 Yes Cut Figure 2 A schematic diagram of the structure of a single pole piece obtained from the pole piece blank shown;

[0032] Figure 4 It is the ear and Figure 3 The schematic diagram of the structure of the pole piece connection shown;

[0033] Figure 5 is along Figure 1 The schematic cross-sectional view of the connection between the pole ear and the pole piece in the A-A' direction shown;

[0034] Figure 6 is along Figure 1 The schematic cross-sectional view of the connection between the pole ear and the pole piece in the BB' direction shown;

[0035] Figure 7 2 is a schematic diagram of the structure of the pole piece blank of the second embodiment of the present application;

[0036] Figure 8 Yes Cut Figure 7 A schematic diagram of the structure of a single pole piece obtained from the pole piece blank shown;

[0037] Fig. 9 It is the ear and Figure 8 The schematic diagram of the structure of the pole piece connection shown;

[0038] Fig.10 is a schematic structural diagram of a single pole piece of the third embodiment of the present application;

[0039] Fig.11 It is the ear and Fig.10 The schematic diagram of the structure of the pole piece connection shown;

[0040] Fig.12 2 is a schematic diagram of the structure of a pole piece blank according to a fourth embodiment of the present application;

[0041] Fig.13 Yes Cut Fig.12 A schematic diagram of the structure of a single pole piece obtained from the pole piece blank shown;

[0042] Fig.14 It is the ear and Fig.13 The schematic diagram of the structure of the pole piece connection shown;

[0043] Fig.15 is a schematic structural diagram of the second surface of a pole piece according to an embodiment of the present application;

[0044] Fig.16 It is a schematic structural diagram of the second surface of a pole piece of another embodiment of the present application.

[0045] The reference numerals are described as follows:

[0046] Electrochemical device 1

[0047] Pole piece 10 Pole piece blank 10a Dotted line O1 Dotted line O2 Dotted line O3

[0048] First active material layer 12 First insulating layer 13 Second active material layer 12a Second insulating layer 13a

[0049] Current collector 11

[0050] First zone Z1 Second zone Z2 Third zone Z3

[0051] Fourth zone Z4 Fifth zone Z5 Sixth zone Z6

[0052] The first part Z31 of the third area Z3

[0053] First part first side Z311 First part second side Z312

[0054] The third side of the first part Z313 The fourth side of the first part Z314

[0055] The second part Z32 of the third area Z3

[0056] Second part first side Z321 Second part second side Z322

[0057] The third side of the second part Z323 The fourth side of the second part Z324

[0058] Tab 20

[0059] Tab first side 21 Tab second side 22

[0060] The third side of the tab 23 The fourth side of the tab 24

[0061] Packaging bag 30

[0062] Accommodating cavity 31 Main body 30a Packaging portion 30b Tab glue 32

[0063] First direction x Second direction y DETAILED DESCRIPTION

[0064] The electrochemical device provided in the embodiment of the present application includes a pole piece and a pole ear. The pole piece of the present application has the following configuration: the current collector of the pole piece includes a first region, a second region and a first part of a third region, the first region is provided with a first active material layer, the second region is provided with a first insulating layer, and the orthographic projection of the second region along the thickness direction of the current collector at least partially surrounds the orthographic projection of the first part of the third region along the thickness direction of the current collector, that is, along the width direction of the current collector, the length of the first part of the third region of the current collector is less than the length of the pole piece, so that the exposed conductive area of ​​the current collector is smaller, thereby reducing safety risks, for example, reducing the risk of short circuit when the electrochemical device is punctured.

[0065] An electrochemical device is a device that generates electrical energy using a chemical reaction. In a specific scenario, the electrochemical device includes, but is not limited to, all types of primary batteries, secondary batteries, fuel cells, solar cells, and capacitors (e.g., supercapacitors) batteries. The electrochemical device may preferably be a lithium secondary battery, including but not limited to a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, and a lithium ion polymer secondary battery. The electrochemical device of the embodiment of the present application may exist in the form of a single battery or a battery module.

[0066] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be clearly and completely described below in combination with various embodiments and the drawings of various embodiments. Obviously, the described embodiments are only part of the embodiments, not all. Based on the embodiments in the present application, the following embodiments and their technical features can be combined with each other without conflict.

[0067] It should be understood that in the description of the embodiments of the present application, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc. to indicate the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the technical solutions and simplified descriptions of the corresponding embodiments of the present application, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0068] See also Figure 1 , is a schematic diagram of the structure of an electrochemical device 1 according to an embodiment of the present application. The electrochemical device 1 includes an electrode assembly (not shown), a tab 20 and a packaging bag 30 .

[0069] The packaging bag 30 forms a receiving cavity 31 , and the internal components of the electrochemical device 1 (such as electrode components, electrolyte, etc.) are built into the receiving cavity 31 . The packaging bag 30 is used to protect these internal components, which is beneficial to improving the protection effect and safety of the electrochemical device 1 .

[0070] The packaging bag 30 includes a main body 30a and a packaging portion 30b. The electrode assembly and the electrolyte are arranged in a receiving cavity 31 formed by the main body 30a, and the packaging portion 30b and the pole lug 20 extend from one end of the main body 30a. The packaging portion 30b is used to seal the end of the main body 30a, so as to prevent the electrolyte from leaking from the end and impurities such as water and oxygen outside the packaging bag 30 from entering the packaging bag 30. It should be understood that the packaging portion 30b also seals the protruding area of ​​the pole lug 20. For example, a pole lug glue 32 is provided at the junction of the packaging bag 30 and the pole lug 20, so as to achieve the sealing of the junction of the packaging bag 30 and the pole lug 20. The packaging area where the pole lug 20 protrudes from the packaging portion 30b can be called the top sealing area. Figure 5 In the illustrated scenario, the tab 20 extends from the upper end of the main body 30 a , and the top sealing area is disposed at the upper end of the main body 30 a .

[0071] The electrode assembly can be formed by winding a plurality of pole pieces 10. In the case where the electrochemical device 1 includes positive and negative polarities, the electrode assembly includes a positive pole piece and a negative pole piece, and a separator disposed between the positive pole piece and the negative pole piece. One end of the pole tab 20 extends into the packaging bag 30 and is electrically connected to the pole piece 10 of the corresponding polarity, and the other end of the pole tab 20 extends from one side of the packaging bag 30.

[0072] The pole lug 20 includes a first pole lug and a second pole lug, the first pole lug is a negative pole lug, and the second pole lug is a positive pole lug. The first pole lug is electrically connected to the negative pole piece and extends from the inside of the packaging bag 30 to the outside of the packaging bag 30, and the second pole lug is electrically connected to the positive pole piece and extends from the inside of the packaging bag 30 to the outside of the packaging bag 30. In other embodiments, the first pole lug can be a positive pole lug, and the second pole lug is a negative pole lug. Some parts of this article take one of the pole lugs as an example to describe the structure of the pole lug 20 of the present application. In addition, some parts of this article take one of the polarity pole pieces as an example to describe the structure of the pole piece 10 of the present application.

[0073] First embodiment

[0074] Please also read Figures 1 to 6 As shown, the pole piece 10 includes a current collector 11, and a first active material layer 12 and a first insulating layer 13 disposed on the surface of the current collector 11. The current collector 11 includes a first surface and a second surface disposed opposite to each other. The first surface is shown in the figure.

[0075] The first surface of the current collector 11 includes a first region Z1, a second region Z2, and a first portion Z31 of the third region Z3. The first region Z1 is provided with a first active material layer 12, the second region Z2 is provided with a first insulating layer 13, and the orthographic projection of the second region Z2 along the thickness direction of the current collector 11 surrounds the orthographic projection of the first portion Z31 of the third region Z3 along the thickness direction of the current collector 11. That is, when observed along the thickness direction of the current collector 11, the second region Z2 surrounds the first portion Z31 of the third region Z3. In some embodiments, the insulating layer (for example, at least one of the first insulating layer 13 or the second insulating layer 13a) can be coated on the current collector 11 by gravure printing. The present application can adopt publicly known gravure printing technology, which is not limited here.

[0076] The current collector 11 includes a first end, a second end, a third end, and a fourth end. The first end and the second end are arranged along the first direction x, the first end includes the first side 111 of the current collector, and the second end includes the second side 112 of the current collector. The third end and the fourth end are arranged along the second direction y, the second direction y is the length direction of the current collector 11, the third end includes the third side 113 of the current collector, and the fourth end includes the fourth side 114 of the current collector. Along the first direction x, the first part Z31 of the third region Z3 is arranged at the first end, and along the second direction y, the first part Z31 of the third region Z3 is arranged at the third end.

[0077] In this embodiment, the so-called end portion can be understood as: taking a certain component as an example, the end portion is an edge portion of the component with a side edge, and the ratio of the length of the edge portion to the length of the component along the side edge toward the center of the component is less than a predetermined threshold, for example, the predetermined threshold is d, and satisfies: 10%≤d≤30%. For this, please refer to Figure 3 In the scenario shown, the first end of the current collector 11 is: the first end is the upper edge portion of the current collector 11, and along the first direction x, the ratio of the length of the upper edge portion to the width of the current collector 11 (that is, the length of the current collector 11 along the first direction x) is less than a predetermined threshold, for example, the predetermined threshold d is 10%.

[0078] See also Figure 4 , the pole tab 20 is arranged on the first part Z31 of the third region Z3, and the orthographic projection part of the first part Z31 of the third region Z3 along the thickness direction of the current collector 11 surrounds the orthographic projection of the pole tab 20 along the thickness direction of the current collector 11. The pole tab 20 includes a first side edge 21 of the pole tab, a second side edge 22 of the pole tab, a third side edge 23 of the pole tab, and a fourth side edge 24 of the pole tab. The first side edge 21 of the pole tab and the second side edge 22 of the pole tab are arranged opposite to each other along the first direction x, and along the first direction x, the distance between the second side edge 22 of the pole tab and the second side edge 112 of the current collector is less than the distance between the first side edge 21 of the pole tab and the second side edge 112 of the current collector, that is, the second side edge 22 of the pole tab is close to the second side edge 112 of the current collector. The third side 23 of the pole tab and the fourth side 24 of the pole tab are arranged opposite to each other along the second direction y. Along the second direction y, the distance between the third side 23 of the pole tab and the third side 113 of the current collector is smaller than the distance between the fourth side 24 of the pole tab and the third side 113 of the current collector, that is, the third side 23 of the pole tab is close to the third side 113 of the current collector.

[0079] The first part Z31 of the third region Z3 includes a first part first side Z311, a first part second side Z312, a first part third side Z313, and a first part fourth side Z314. The first part first side Z311 and the first part second side Z312 are arranged opposite to each other along the first direction x, and along the first direction x, the first part second side Z312 is adjacent to the pole ear second side 22, and the distance between the two is L2; ​​the first part third side Z313 and the first part fourth side Z314 are arranged opposite to each other along the second direction y, and along the second direction y, the first part third side Z313 is adjacent to the pole ear third side 23, and the distance between the two is L3, and the first part fourth side Z314 is adjacent to the pole ear fourth side 24, and the distance between the two is L4.

[0080] exist Figure 4 In the illustrated scenario, each side edge of the first portion Z31 of the third region Z3 and each side edge of the tab 20 may be a straight line, and two adjacent sides are parallel, for example, the second side edge Z312 of the first portion is parallel to the second side edge 22 of the tab, the third side edge Z313 of the first portion is parallel to the fourth side edge Z314 of the first portion, and the fourth side edge Z314 of the first portion is parallel to the fourth side edge 24 of the tab. The distance between two adjacent sides may be the length of a line segment perpendicular to and connecting the two sides.

[0081] In the scenario where two adjacent sides are not parallel, that is, in other embodiments of the present application, the shapes of the first portion Z31 of the third region Z3 and the tab 20 may not be Figures 4 to 16 The rectangle shown in the figure may be a trapezoid or other irregular shapes. The first part Z31 of the third area Z3 and the side of the tab 20 may include a straight line extending along the first direction x and / or along the second direction y, or an oblique line not extending along the first direction x and the second direction y, or even an arc, a curve, etc. For this, the method of obtaining the distance between two adjacent side edges includes but is not limited to one of the following:

[0082] 1. It can be the minimum distance along the corresponding direction. For example, along the first direction x, the minimum distance between the second side Z312 of the first portion and the second side 22 of the tab is the distance L2 between the two sides.

[0083] Second, it can be the average distance between two adjacent sides. Still taking the measurement of the distance L2 between the second side Z312 of the first part and the second side 22 of the pole lug as an example, the second side Z312 of the first part and the second side 22 of the pole lug are respectively divided into multiple sections with equal distances along the second direction y. The more sections are divided, the more accurate the measurement result is. In each section, two sampling points a1 and a2 are set along the first direction x. The two sampling points a1 and a2 are respectively located on the second side Z312 of the first part and the second side 22 of the pole lug. The sampling points a1 and a2 are two points located on the first direction x. The distance between each section along the first direction x is the distance between the two sampling points a1 and a2. Taking this as an example, the distance between the two sampling points a1 and a2 in all sections is measured, and the average value is calculated, and the average value is used as the distance between the two adjacent sides.

[0084] There is a certain distance between each side of the pole lug 20 and each side of the first part Z31 of the third region Z3. By controlling the distance, for example, by reducing the distance between two adjacent sides, the conductive area exposed by the pole piece 10 can be further reduced. In addition, when the pole lug 20 is connected to the first part Z31 of the third region, the pole lug 20 is prevented from contacting the first insulating layer 13 adjacent to the first part Z31 of the third region Z3, which is beneficial to improve the stability of the connection between the pole lug 20 and the first part Z31 of the third region Z3. In some embodiments, at least one of the following conditions is met: L2≤10mm; L3≤10mm; L4≤10mm. The distance between the adjacent sides is beneficial to improve the stability of the electrical connection between the pole lug 20 and the pole piece 10, while making the conductive area of ​​the pole piece 10 not covered by the pole lug 20 smaller. Optionally, the ratio of the pole lug 20 to the first part Z31 of the third region Z3 can be 0.3 to 1, and the conductive area exposed by the pole piece 10 is smaller.

[0085] The electrode sheet 10 can be obtained by cutting a whole electrode sheet blank 10a. For example, please refer to Figure 2 and Figure 4 As shown, theoretically, by cutting the electrode sheet blank 10a along the dotted line O1, two electrode sheets 10 can be obtained. It should be understood that in the actual cutting process, due to process errors and other reasons, the actual cutting route is not the dotted line O1, but can be along the dotted line O2, so as to obtain Figure 3 and Figure 4 the electrode sheet 10 shown.

[0086] Please refer to Figure 4 As shown, the distance W1 between the first side Z311 of the first part and the first side 111 of the current collector satisfies 0 < W1 ≤ 10 mm. W1 can be adaptively set according to the size, type, etc. of the electrochemical device 1. For example, the value of W1 can be 8 mm, 5 mm, 3 mm, 2 mm, etc. Herein, this embodiment allows the existence of cutting process errors, which is beneficial to reducing the cutting process accuracy.

[0087] The first part Z31 of the third region Z3 can be a regular rectangle or other shapes, which is not limited in this application. For example, due to errors such as the manufacturing process, along the second direction y, the length of the first side Z311 of the first part is not equal to the length of the second side Z312 of the first part. In some embodiments, the difference between the length of the first side Z311 of the first part and the length of the second side Z312 of the first part is within a certain threshold, for example, not greater than 5%, which is beneficial to improving the electrical connection stability between the tab 20 and the electrode sheet 10 while making the conductive area of the electrode sheet 10 not covered by the tab 20 smaller. The difference can be understood as the percentage of the length difference between the two sides and the longest one of the first side Z311 of the first part and the second side Z312 of the first part. In Figures 2 to 4 the scenario shown, the length of the first side Z311 of the first part is equal to the length of the second side Z312 of the first part, and the difference between the lengths of these two sides is zero.

[0088] Please refer to Figures 1 to 6As shown, the first insulating layer 13 is a film formed of an insulating material, and the first insulating layer 13 is disposed in the second region Z2 and is used to electrically insulate the second region Z2 from other conductive elements (such as the pole ear 20, the electrolyte, etc.). Along the thickness direction of the current collector 11, the orthographic projection of the second region Z2 surrounds the orthographic projection of the first part Z31 of the third region Z3. The first part Z31 of the third region Z3 may be a region where the pole piece 10 is electrically connected to the pole ear 20, and the region is a conductive region. Here, along the first direction x, which is the width direction of the current collector 11, the length of the conductive region exposed by the pole piece 10 is less than the length of the pole piece 10, and the conductive region exposed by the pole piece 10 is small. After the pole piece 10 is connected to the pole ear 20, the area of ​​the pole piece 10 not covered by the pole ear 20 is small, thereby reducing safety risks, for example, reducing the risk of short circuit when the electrochemical device 1 is punctured.

[0089] Further optionally, a sealant (not shown) may be provided in the area where the tab 20 is electrically connected to the pole piece 10, and the sealant not only covers the connection area between the tab 20 and the pole piece 10 to prevent welding burrs in the connection area from piercing the packaging bag 30, but also covers the first part Z31 of the entire third area Z3. In one embodiment, the sealant includes but is not limited to insulating members such as adhesive tape or sealant.

[0090] Second embodiment

[0091] This application uses the same reference numerals to identify structural elements with the same names. Based on the description of the above embodiment, but different from it, refer to Figures 7 to 9 In this embodiment, the orthographic projection of the second region Z2 along the thickness direction of the current collector 11 and a part of the orthographic projection of the first side edge 111 of the current collector along the thickness direction of the current collector 11 jointly surround the orthographic projection of the first part Z31 of the third region Z3 along the thickness direction of the current collector 11. That is, when observed along the thickness direction of the current collector 11, the first side edge Z311 of the first part coincides with the first side edge 111 of the current collector, and W1=0. Compared with the aforementioned Figure 4 See Figure 7 and Fig. 9 As shown, by cutting the pole piece blank 10a along the dotted line O1, two pole pieces 10 of this embodiment can be obtained. The cutting process is precise, so that the exposed conductive area (the first part Z31 of the third area Z3) of the pole piece 10 meets the design.

[0092] Third embodiment

[0093] When preparing the first part Z31 forming the third region Z3, in order to avoid the tab 20 and the first insulating layer 13 overlapping at the third end of the current collector 11, increasing the thickness of the electrochemical device 1, and thus adversely affecting the energy density of the electrochemical device 1, a stamping process can be used to punch out the first insulating layer 13 between the third side Z313 of the first part and the first side 111 of the current collector, and leave an arc-shaped gap. Fig.10 and Fig.11 In this embodiment, the first portion third side Z313 and the first portion fourth side Z314 each independently include an arc portion. The arc portion is disposed at the first end of the current collector 11. Other embodiments may include an arc-like portion. The arc portion is described below as an example.

[0094] In some embodiments, along the first direction x, the extension length of the arc portion is not greater than 10 mm, the extension length of the arc portion is smaller, and the area of ​​the arc gap is smaller, so that the arc gap does not affect the stability of the connection between the tab 20 and the first portion Z31 of the third area Z3. The so-called extension length can be understood as: the straight-line distance between the starting point and the end point of the arc portion along the first direction x. Here, the extension length of the arc portion can be obtained by measuring the straight-line distance between the starting point and the end point of the arc portion along the first direction x.

[0095] The starting point of the arc portion refers to: the leftmost point of the arc portion along the first direction x, that is, the point where the arc portion is closest to the third side 113 of the current collector.

[0096] The end point of the arc portion refers to: the rightmost point of the arc portion along the first direction x, that is, the point where the arc portion is farthest from the third side 113 of the current collector.

[0097] In some embodiments, the difference between the length of the first side Z311 of the first portion and the length of the second side Z312 of the first portion may be greater than 5%. Fig.12 and 13 In the illustrated scene, an arc portion is provided at the upper end of the first portion Z31 of the third area Z3 to form an arc-shaped notch, and the length of the first side Z311 of the first portion is less than the length of the second side Z312 of the first portion. It should be understood that the length of the first side Z311 of the first portion is: along the second direction y, the distance between the end point of the arc portion of the third side Z313 of the first portion and the end point of the arc portion of the fourth side Z314 of the first portion.

[0098] Fourth embodiment

[0099] Based on the description of the second embodiment above, but different from it, refer to Figure 12 to Figure 14, in this embodiment, the third region Z3 further includes a second part Z32, and the first part Z31 and the second part Z32 of the third region Z3 are oppositely arranged along the first direction x. The orthographic projection of the second region Z2 in the thickness direction of the current collector 11 and the orthographic projection of the second side 112 of the current collector in the thickness direction of the current collector 11 together surround the orthographic projection of the second part Z32 of the third region Z3 in the thickness direction of the current collector.

[0100] The second part Z32 of the third region Z3 includes a first side Z321, a second side Z322, a third side Z323, and a fourth side Z324 of the second part. The first side Z321 and the second side Z322 of the second part are oppositely arranged along the first direction x. Along the first direction x, the first side Z321 of the second part is adjacent to the second side 112 of the current collector. The second side Z322 of the second part coincides with the second side 112 of the current collector. The third side Z323 and the fourth side Z324 of the second part are oppositely arranged along the second direction y.

[0101] In some embodiments, the second part Z32 of the third region Z3 satisfies at least one of the following four conditions:

[0102] (1) Along the first direction x, the distance W2 between the first side Z321 of the second part and the second side 112 of the current collector satisfies 0 < W2 ≤ 10 mm. The length of the second part Z32 of the third region Z3 in the first direction x is small, further reducing the exposed conductive region of the pole piece 10.

[0103] (2) Along the second direction y, the difference between the length of the first side Z321 of the second part and the length of the second side Z312 of the first part is not greater than 5%.

[0104] (3) The third side Z323 of the second part and the third side Z313 of the first part are on a straight line.

[0105] (4) The fourth side Z324 of the second part and the fourth side Z314 of the first part are on a straight line.

[0106] Compared with the foregoing Figure 2 and Figure 3 shown, please refer to Fig.12 and Fig.13As shown, by cutting the pole piece blank 10a along the dotted line O3, the portion between two adjacent dotted lines O3 can obtain a pole piece 10 of the present embodiment. In the scenario where a single pole piece 10 is cut from a whole pole piece blank 10a, cutting process errors are allowed to exist, reducing the precision of the cutting process. Based on this cutting process, the two side edges in the aforementioned conditions (3) and (4) are located on a straight line, including: the two side edges are located on a straight line, or are approximately located on a straight line. Approximately located on a straight line can be understood as: along the second direction y, the maximum distance between the two side edges is less than a preset threshold. The preset threshold can be set according to the production process error, for example, 2 mm.

[0107] In addition, for the first part Z31 of the third area Z3 and the second part Z32 of the third area Z3 of other shapes, the part between the two adjacent imaginary lines O3 of the pole piece blank 10a is other shapes, and the two sides in the above conditions (3) and (4) may not be located on a straight line at all. For example, before cutting the pole piece blank 10a, the third side Z323 of the second part and the third side Z313 of the first part are located on an arc line. After cutting, since these two sides are one side of the same figure between the two adjacent imaginary lines O3, along the second direction y, the difference in length between the first side Z321 of the second part and the second side Z312 of the first part should be within a certain threshold range, for example, not more than 5%.

[0108] It should be understood that the structural design of the pole piece 10 in any of the aforementioned embodiments is only for exemplary display. Other embodiments may set the shape of the third area Z3 to be different from the aforementioned, as long as: the orthographic projection of the second area Z2 along the thickness direction of the current collector 11 at least partially surrounds the orthographic projection of the first part Z31 of the third area Z3 along the thickness direction of the current collector 11. Here, along the first direction x, the length of the conductive area exposed by the pole piece 10 is less than the length of the pole piece 10, and the conductive area exposed by the pole piece 10 is smaller. After the pole piece 10 is connected to the pole ear 20, the area of ​​the pole piece 10 not covered by the pole ear 20 is smaller, thereby reducing safety risks, for example, reducing the risk of short circuit when the electrochemical device 1 is punctured.

[0109] Based on the description of any of the above embodiments, please also refer to Figure 15 to Figure 16 As shown, the pole piece 10 further includes a second active material layer 12a and a second insulating layer 13a, and the second surface of the current collector 11 includes a fourth region Z4, a fifth region Z5 and a sixth region Z6. The fourth region Z4 is provided with a second active material layer 12a, the fifth region Z5 is provided with a second insulating layer 13a, and the orthographic projection of the fifth region Z5 along the thickness direction of the current collector 11 at least partially surrounds the orthographic projection of the sixth region Z6 along the thickness direction of the current collector 11.

[0110] The materials of the second active material layer 12a and the first active material layer 12 may be the same or different. The materials of the second insulating layer 13a and the first insulating layer 13 may be the same or different. The insulating materials and insulating properties of the second insulating layer 13a and the first insulating layer 13 may be determined according to actual needs. For example, in some scenarios, the insulating material of any insulating layer may include one or a combination of aluminum oxide and zirconium oxide; in some scenarios, the insulation resistance of any insulating layer may be greater than or equal to 0.1 Gohm, and optionally, the insulation resistance is greater than or equal to 1 Gohm, and the electrical insulation performance is good.

[0111] Here, along the thickness direction of the current collector 11 , the sixth region Z6 and the third region Z3 at least partially overlap, which is beneficial to improving the stability of welding between the electrode tab 20 and the third region Z3 .

[0112] In some embodiments, the sixth zone Z6 and the third zone Z3 satisfy one of the following three conditions:

[0113] (1) The orthographic projection of the sixth region Z6 along the thickness direction of the current collector 11 falls within the orthographic projection of the third region Z3 along the thickness direction of the current collector.

[0114] (2) The orthographic projection of the third region Z3 along the thickness direction of the current collector 11 falls within the orthographic projection of the sixth region Z6 along the thickness direction of the current collector 11 .

[0115] (3) The orthographic projection of the sixth region Z6 along the thickness direction of the current collector 11 coincides with the orthographic projection of the third region Z3 along the thickness direction of the current collector 11, for example Fig.15 and Fig.16 shown.

[0116] In addition, in some embodiments of the present application, the third region Z3 includes a blank area where the current collector 11 is exposed, and the blank area directly exposes the surface of the current collector 11, that is, the current collector 11 is directly connected to the pole ear 20, which is beneficial to reduce the overlap of the pole ear 20 at the third end of the current collector 11, reduce the thickness of the electrochemical device 1, and improve the energy density of the electrochemical device 1.

[0117] In some embodiments of the present application, the third region Z3 is provided with a coating (not shown), and the tab 20 is connected to the current collector 11 through the coating. The coating can be conducive to the stable connection between the tab 20 and the current collector 11, and is conducive to achieving good electrical contact between the two. The specific type of the coating is not limited by the present application. For example, the thermal conductivity of the coating can be greater than the thermal conductivity of the current collector 11, which is conducive to conducting the heat generated inside the current collector 11 and the electrochemical device 1 to the tab 20 and to the outside through the coating, which is conducive to the heat dissipation of the electrochemical device 1. For another example, the electrical conductivity of the coating is greater than the electrical conductivity of the current collector 11, which is conducive to improving the electrical connection between the current collector 11 and the tab 20 and reducing the resistance of the electrical connection.

[0118] The pole piece 10 of any of the aforementioned embodiments may be a positive pole piece or a negative pole piece, or both the positive pole piece and the negative pole piece may be designed using the pole piece 10 of any of the aforementioned embodiments.

[0119] Positive electrode

[0120] The positive electrode sheet may include a positive electrode current collector and a positive electrode active material layer (e.g., a first active material layer 12 and a second active material layer 12a) formed on both surfaces of the positive electrode current collector, and an insulating layer (e.g., a first insulating layer 13 and a second insulating layer 13a), wherein the positive electrode active material layer contains a positive electrode active material.

[0121] The material of the positive electrode current collector (e.g., current collector 11) is not particularly limited, and can be any material suitable for use as a positive electrode current collector. In some examples, the positive electrode current collector includes, but is not limited to: metal materials such as aluminum (Al), stainless steel, nickel (Ni), titanium (Ti), and tantalum (Ta); and carbon materials such as carbon cloth and carbon paper.

[0122] In some implementations, the positive electrode active material layer may be one or more layers, and each layer of the multiple layers of positive electrode active material contains the same or different positive electrode active materials. The positive electrode active material is a material that can reversibly embed and deintercalate metal ions such as lithium ions. Preferably, the chargeable capacity of the positive electrode active material layer is less than the discharge capacity of the negative electrode active material layer to prevent lithium metal from being precipitated on the negative electrode sheet during charging.

[0123] The embodiments of the present application do not limit the type of positive electrode active material, as long as it can electrochemically absorb and release metal ions (e.g., lithium ions). In some implementations, the positive electrode active material can be a material containing lithium and at least one transition metal. Examples of positive electrode active materials may include, but are not limited to: lithium transition metal composite oxides and lithium-containing transition metal phosphate compounds, and transition metals include, but are not limited to, vanadium (V), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), etc.

[0124] The surface of the positive electrode active material may be attached with a substance having a different composition from the positive electrode active material. The attached substance includes, but is not limited to: oxides such as aluminum oxide, silicon dioxide, titanium dioxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate; and carbon.

[0125] Methods for attaching substances to the surface of the positive electrode active material layer include but are not limited to: a method in which the attached substance is dissolved or suspended in a solvent and then infiltrated into the positive electrode active material and dried; a method in which the attached substance is dissolved or suspended in a solvent, then infiltrated into the positive electrode active material and then reacted by heating or the like; a method in which the attached substance is added to the positive electrode active material precursor and then fired simultaneously, etc. In the example of attaching carbon, a method in which a carbon material (such as activated carbon, etc.) is used for mechanical attachment.

[0126] The attached substance on the surface of the positive electrode active material layer can inhibit the oxidation reaction of the electrolyte on the surface of the positive electrode active material layer, which is beneficial to improve the life of the electrochemical device 1. In the description herein, the positive electrode active material layer and the attached substance on the surface thereof can also be referred to as the positive electrode active material layer.

[0127] The positive electrode insulating layer includes but is not limited to at least one of aluminum oxide, zirconium oxide, aluminum hydroxide, silicon oxide, boehmite and titanium oxide, or a combination of multiple materials. Optionally, a binder with a mass ratio of 3-15% is added and mixed.

[0128] Negative electrode

[0129] The negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer (e.g., a first active material layer 12 and a second active material layer 12a) formed on both surfaces of the negative electrode current collector, and an insulating layer (e.g., a first insulating layer 13 and a second insulating layer 13a), wherein the negative electrode active material layer contains a negative electrode active material.

[0130] In some implementations, the negative electrode current collector (eg, current collector 11 ) includes, but is not limited to: metal foil, metal film, metal mesh, stamped metal plate, foamed metal plate, etc.; conductive resin plate.

[0131] In some implementations, the negative electrode active material layer may be one or more layers, and each layer of the multiple layers of negative electrode active material may contain the same or different negative electrode active materials. The negative electrode active material is any material that can reversibly embed and de-embed metal ions such as lithium ions.

[0132] The embodiments of the present application do not limit the type of negative electrode active material, as long as it can absorb and release metal ions electrochemically. In some examples, the negative electrode active material includes, but is not limited to: lithium transition metal composite oxides, lithium-containing transition metal phosphate compounds, graphite, hard carbon, soft carbon and other carbon materials, silicon (Si), silicon oxides represented by SiOx (0<x<2) and other silicon-containing compounds, metallic lithium, metals that form alloys with lithium and their alloys, amorphous compounds with oxides such as tin dioxide as the main body, and lithium titanate.

[0133] The negative electrode insulating layer includes but is not limited to at least one of aluminum oxide, zirconium oxide, aluminum hydroxide, boehmite, silicon oxide and titanium oxide, or a combination of multiple materials. Optionally, a binder with a mass percentage of 3-15% is added and mixed.

[0134] Isolation layer

[0135] The separator is disposed between the positive electrode sheet and the negative electrode sheet to separate the positive electrode sheet from the negative electrode sheet and prevent the electrons in the electrochemical device 1 from passing freely, while allowing the ions in the electrolyte to pass freely. The positive electrode sheet, the negative electrode sheet and the separator are wound to form an electrode assembly of the electrochemical device 1.

[0136] In the scenarios shown in the aforementioned embodiments, the third region Z3 is arranged at the head of the pole piece 10. In the wound electrode assembly, the pole ear 20 electrically connected to the third region Z3 is located at the head of the pole piece 10, that is, located at the innermost circle of the electrode assembly.

[0137] In the wound electrode assembly, the third region Z3 may also be disposed at the tail of the positive electrode sheet, and the tab 20 electrically connected to the third region Z3 is located at the tail of the positive electrode sheet, that is, at the outermost circle of the electrode assembly. Alternatively, in other embodiments, the third region Z3 may be disposed at the head or tail of the negative electrode sheet, which may also achieve the aforementioned beneficial effects.

[0138] Yet another embodiment of the present application provides an electronic device, comprising the electrochemical device 1 of any of the above embodiments.

[0139] Electronic devices can be implemented in various specific forms, for example, unmanned aerial vehicles, electric cleaning tools, energy storage products, electric vehicles, electric bicycles, electric navigation tools and other electronic products. In practical scenarios, electronic devices specifically include but are not limited to: laptop computers, pen-type computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini-discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries and lithium-ion capacitors, etc.

[0140] It can be understood by those skilled in the art that, in addition to components specifically used for mobile purposes, the configuration according to the embodiments of the present application can also be applied to fixed-type electronic devices.

[0141] Since the electronic device includes the electrochemical device 1 of any of the aforementioned embodiments, the electronic device can produce the beneficial effects of the electrochemical device 1 of the corresponding embodiment.

[0142] In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or device including the element. In addition, parts, features, and elements with the same name in different embodiments may have the same meaning or different meanings, and their specific meanings need to be determined by their explanation in the specific embodiment or further combined with the context of the specific embodiment.

[0143] In addition, although the terms "first, second, third" and the like are used herein to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. As used herein, the singular forms "one", "an" and "the" are intended to include plural forms as well. The terms "or" and "and / or" are interpreted as inclusive, or mean any one or any combination. Only when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way, an exception to this definition will occur.

[0144] The technical solution of the present application is described exemplarily below through specific embodiments:

[0145] Example 1

[0146] The positive electrode adopts the above Fig. 9The structure is designed as shown and wound to form an electrode assembly, L2 is 2 mm, L3 and L4 are both 2 mm, and the first insulating layer 13 is composed of 90% by mass of aluminum oxide and 10% by mass of a binder.

[0147] Embodiment 2:

[0148] The positive electrode adopts the above Fig. 9 The structure is designed as shown and wound to form an electrode assembly, L2 is 1.5 mm, L3 and L4 are both 2 mm, and the first insulating layer 13 is composed of 90% by mass of aluminum oxide and 10% by mass of a binder.

[0149] Embodiment 3:

[0150] The positive electrode adopts the above Fig. 9 The structure is designed as shown and wound to form an electrode assembly, L2 is 2 mm, L3 and L4 are both 1.5 mm, and the first insulating layer 13 is composed of 90% by mass of aluminum oxide and 10% by mass of a binder.

[0151] Embodiment 4:

[0152] The positive electrode adopts the above Fig. 9 The structure is designed as shown and wound to form an electrode assembly, L2 is 2 mm, L3 and L4 are both 2 mm, and the first insulating layer 13 is composed of 85% by mass of aluminum oxide and 15% by mass of a binder.

[0153] Embodiment 5:

[0154] The positive electrode adopts the above Fig. 9 The structure is designed as shown and wound to form an electrode assembly, L2 is 1.5 mm, L3 and L4 are both 2 mm, and the first insulating layer 13 is composed of 85% by mass of aluminum oxide and 15% by mass of a binder.

[0155] Embodiment 6:

[0156] The positive electrode adopts the above Fig. 9 The structure is designed as shown and wound to form an electrode assembly, L2 is 2 mm, L3 and L4 are both 1.5 mm, and the first insulating layer 13 is composed of 85% by mass of aluminum oxide and 15% by mass of a binder.

[0157] Embodiment 7:

[0158] The positive electrode adopts the above Fig.14 The structure is designed and wound to form an electrode assembly. The first part Z31 of the third area Z3 is rectangular. The length of the first part Z31 of the third area Z3 is 2 mm and the width is 8 mm. The first insulating layer 13 is composed of 90% aluminum oxide and 10% binder by mass.

[0159] Embodiment 8:

[0160] The positive electrode adopts the above Fig.14 The structure is designed and wound to form an electrode assembly. The first part Z31 of the third area Z3 is rectangular. The length of the first part Z31 of the third area Z3 is 1.5 mm and the width is 8 mm. The first insulating layer 13 is composed of 90% aluminum oxide and 10% binder by mass.

[0161] Embodiment 9:

[0162] The positive electrode adopts the above Fig.14 The structure is designed and wound to form an electrode assembly. The first part Z31 of the third area Z3 is rectangular. The length of the first part Z31 of the third area Z3 is 3 mm and the width is 8 mm. The first insulating layer 13 is composed of 90% aluminum oxide and 10% binder by mass.

[0163] Embodiment 10:

[0164] The positive electrode adopts the above Fig.14 The structure is designed and wound to form an electrode assembly. The first part Z31 of the third area Z3 is rectangular. The length of the first part Z31 of the third area Z3 is 2 mm and the width is 10 mm. The first insulating layer 13 is composed of 90% aluminum oxide and 10% binder by mass.

[0165] Embodiment 11:

[0166] The positive electrode adopts the above Fig.14 The structure is designed and wound to form an electrode assembly. The first part Z31 of the third area Z3 is rectangular. The length of the first part Z31 of the third area Z3 is 2 mm and the width is 12 mm. The first insulating layer 13 is composed of 90% aluminum oxide and 10% binder by mass.

[0167] Embodiment 12:

[0168] The positive electrode adopts the above Fig.14 The structure is designed and wound to form an electrode assembly. The first part Z31 of the third area Z3 is rectangular. The length of the first part Z31 of the third area Z3 is 2 mm and the width is 14 mm. The first insulating layer 13 is composed of 90% aluminum oxide and 10% binder by mass.

[0169] Comparative Example:

[0170] The positive electrode sheet adopts the existing technology and is wound to form an electrode assembly. The active material of the positive electrode sheet includes lithium cobalt oxide, and the current collector is aluminum foil with a thickness of 9 mm.

[0171] Acupuncture test method

[0172] 1) Charge the lithium-ion battery to 4.2V-4.4V;

[0173] 2) using a steel nail with a diameter of 2.5 mm to penetrate the entire lithium-ion battery (i.e., electrochemical device 1);

[0174] 3) Measure the temperature of the whole process and observe the phenomenon;

[0175] The passing standard is that lithium-ion batteries will not catch fire or explode.

[0176] The performance test results of Examples 1-12 and the comparative example are shown in the following table. In the following table, the needle penetration rate is the ratio of lithium-ion batteries that pass the needle penetration test, expressed as "m / n", where n is the number of lithium-ion batteries tested, and m is the number of lithium-ion batteries that pass the needle penetration test without short circuit.

[0177] Acupuncture pass rate Example 1 10 / 10 Example 2 10 / 10 Example 3 10 / 10 Example 4 10 / 10 Example 5 10 / 10 Example 6 10 / 10 Example 7 10 / 10 Example 8 10 / 10 Example 9 10 / 10 Example 10 10 / 10 Embodiment 11 10 / 10 Example 12 10 / 10 Comparative Example 4 / 10

[0178] The results show that compared with the traditional lithium-ion battery (comparative example), the electrochemical device 1 of the embodiment of the present application has the following characteristics: when the electrochemical device 1 is punctured, the risk of short circuit can be reduced, thereby reducing the safety risk.

[0179] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of this specification and drawings are also included in the patent protection scope of the present application.

Claims

1. An electrochemical device, comprising a pole piece and a pole ear, wherein the pole piece comprises: A current collector, the current collector comprising a first surface and a second surface disposed opposite to each other; a first active material layer; and A first insulating layer, wherein The first surface of the current collector includes a first region, a second region and a third region, the third region includes a first portion, the first region is provided with the first active material layer, and the second region is provided with the first insulating layer. The orthographic projection of the second region along the thickness direction of the current collector at least partially surrounds the orthographic projection of the first portion of the third region along the thickness direction of the current collector, and the first region and the second region are arranged along the length direction of the current collector.

2. The electrochemical device according to claim 1, wherein: The tab is disposed on the current collector, and the orthographic projection of the first portion of the third region along the thickness direction of the current collector partially surrounds the orthographic projection of the tab along the thickness direction of the current collector, wherein: The current collector comprises: a first end and a second end arranged along a first direction, wherein the first direction is a width direction of the current collector, the first end includes a first side of the current collector, and the second end includes a second side of the current collector; and A third end and a fourth end are arranged along a second direction, wherein the second direction is the length direction of the current collector, the third end includes a third side of the current collector, and the fourth end includes a fourth side of the current collector, wherein: Along the first direction, the first portion of the third region is arranged at the first end portion, Along the second direction, the first portion of the third region is arranged at the third end portion, The tab comprises: A first side edge of the pole tab and a second side edge of the pole tab are arranged opposite to each other along the first direction, and a distance between the second side edge of the pole tab and the second side edge of the current collector along the first direction is smaller than a distance between the first side edge of the pole tab and the second side edge of the current collector; and The third side of the pole lug and the fourth side of the pole lug are arranged opposite to each other along the second direction, and along the second direction, the distance between the third side of the pole lug and the third side of the current collector is smaller than the distance between the fourth side of the pole lug and the third side of the current collector, The first part of the third area includes: A first side edge of the first portion and a second side edge of the first portion are arranged opposite to each other along the first direction, wherein the second side edge of the first portion is adjacent to the second side edge of the tab along the first direction; and The third side edge of the first part and the fourth side edge of the first part are arranged opposite to each other along the second direction, wherein along the second direction, The third side of the first portion is adjacent to the third side of the pole lug, and the fourth side of the first portion is adjacent to the fourth side of the pole lug.

3. The electrochemical device according to claim 2, wherein: Along the first direction, the distance between the second side of the first part and the second side of the tab is L2, the distance between the third side of the first part and the third side of the tab is L3, and the distance between the fourth side of the first part and the fourth side of the tab is L4, satisfying at least one of the following conditions: a1)L2≤10mm; b1) L3 ≤ 10 mm; c1)L4≤10mm.

4. The electrochemical device according to claim 2, wherein: An orthographic projection of the second region along the thickness direction of the current collector surrounds an orthographic projection of the third region along the thickness direction of the current collector.

5. The electrochemical device according to claim 4, wherein: The distance W1 between the first side of the first portion and the first side of the current collector satisfies 0 <W1≤10mm。 6. The electrochemical device according to claim 4, wherein: Along the second direction, a difference between a length of a first side of the first portion and a length of a second side of the first portion is no more than 5%.

7. The electrochemical device according to claim 2, wherein: An orthographic projection of the second region along the thickness direction of the current collector and a portion of an orthographic projection of the first side of the current collector along the thickness direction of the current collector jointly surround an orthographic projection of a first portion of the third region along the thickness direction of the current collector.

8. The electrochemical device according to claim 4, wherein: The difference between the length of the first side of the first portion and the length of the second side of the first portion is greater than 5%.

9. The electrochemical device according to claim 8, wherein: The length of the first side of the first portion is smaller than the length of the second side of the first portion.

10. The electrochemical device according to claim 6, wherein: The third side of the first portion and the fourth side of the first portion each independently include an arc portion or an arc-like portion, and the arc portion or the arc-like portion is arranged at the first end portion.

11. The electrochemical device according to claim 10, wherein: Along the first direction, the extension length of the arc-shaped portion or the arc-like portion is no more than 10 mm. 12 . The electrochemical device according to claim 2 , wherein the third region further comprises a second portion, and along the first direction, the second portion of the third region is disposed at the second end portion.

13. The electrochemical device according to claim 12, wherein: The orthographic projection of the second region along the thickness direction of the current collector and the orthographic projection of the second side of the current collector along the thickness direction of the current collector together surround the orthographic projection of the second portion of the third region along the thickness direction of the current collector.

14. The electrochemical device according to claim 13, wherein: The second part of the third area includes: a first side of the second portion and a second side of the second portion disposed opposite to each other along the first direction, wherein the first side of the second portion is adjacent to the second side of the current collector along the first direction, and the second side of the second portion coincides with the second side of the current collector; and Along the third side of the second portion and the fourth side of the second portion which are arranged opposite to each other along the second direction, the second portion of the third region satisfies at least one of the following conditions: a2) along the first direction, the distance W2 between the first side of the second portion and the second side of the current collector is not greater than 0 <W2≤10mm; b2) along the second direction, the difference between the length of the first side of the second portion and the length of the second side of the first portion is no more than 5%; c2) the third side edge of the second portion and the third side edge of the first portion are located on a straight line; d2) The fourth side edge of the second portion and the fourth side edge of the first portion are located on a straight line.

15. The electrochemical device according to claim 1, wherein The pole piece includes a second active material layer and a second insulating layer, the second surface of the current collector includes a fourth region, a fifth region and a sixth region, the fourth region is provided with the second active material layer, the fifth region is provided with the second insulating layer, and the orthographic projection of the fifth region along the thickness direction of the current collector at least partially surrounds the orthographic projection of the sixth region along the thickness direction of the current collector.

16. The electrochemical device according to claim 15, wherein: The sixth area and the third area meet one of the following conditions: a3) the orthographic projection of the sixth region along the thickness direction of the current collector falls within the orthographic projection of the third region along the thickness direction of the current collector; b3) the orthographic projection of the third region along the thickness direction of the current collector falls within the orthographic projection of the sixth region along the thickness direction of the current collector; c3) The orthographic projection of the sixth region along the thickness direction of the current collector coincides with the orthographic projection of the third region along the thickness direction of the current collector.

17. The electrochemical device according to claim 1, wherein: The third region includes a blank area where the current collector is exposed.

18. The electrochemical device according to claim 1, wherein: The third region is provided with a plating layer, and the electrode tab is connected to the current collector through the plating layer.

19. The electrochemical device according to claim 18, wherein: The thermal conductivity of the coating is greater than the thermal conductivity of the current collector.

20. The electrochemical device according to claim 1, wherein The first insulating layer includes a first insulating material, and the first insulating material includes at least one of the group consisting of aluminum oxide, aluminum hydroxide, silicon oxide, boehmite, titanium oxide, and zirconium oxide.

21. The electrochemical device according to claim 1, wherein: The first active material layer includes an active material, and the active material includes at least one of the group consisting of a lithium transition metal composite oxide and a lithium transition metal phosphate compound.

22. An electronic device, wherein: The electronic device comprises a load and an electrochemical device as claimed in any one of claims 1 to 21, wherein the electrochemical device supplies power to the electronic device.

Images