Electrochemical device and electronic device

Abstract

The application discloses an electrochemical device and an electronic device. The electrochemical device comprises a pole piece and a pole lug. The pole piece comprises a current collector, a first active material layer and a first insulating layer. The current collector comprises a first region, a second region and a first part of a third region. The first region is provided with the first active material layer, and the second region is provided with the first insulating layer. The second region is at least partially surrounded by the first part of the third region in the thickness direction of the current collector. The first region and the second region are arranged along the length direction of the current collector. The pole piece disclosed in the application has a small exposed conductive area, which can reduce the safety risk, for example, the risk of short circuit when the electrochemical device is punctured.

Description

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

[0002] This application relates to the field of battery technology, specifically to an electrochemical device and an electronic device. Background Technology

[0003] With the widespread application of 4G and the arrival 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 increasingly complex and the interaction with people is becoming more frequent. New scenarios place higher demands on the safety performance of battery cells, especially mechanical safety performance, such as resistance to needle penetration and heavy object impact.

[0004] A lithium-ion battery includes a current collector and tabs electrically connected to the current collector. As an example only, the tabs can be soldered onto the current collector. During the manufacturing process of lithium-ion batteries, to allow space for tab soldering, the current collector has a significant area of ​​exposed aluminum foil, creating a safety vulnerability. A solution is needed to address the aforementioned problem. Summary of the Invention

[0005] In view of the prior art, this application provides an electrochemical device and an electronic device to improve the problem of high safety risks caused by the large exposed conductive area of ​​the electrode.

[0006] In a first aspect, embodiments of this application provide an electrochemical device, including an electrode and a tab. The electrode 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 disposed opposite to each other. The first surface of the current collector includes a first region, a second region, and a first portion of a third region. 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. The first portion of the third region, without the first insulating layer, is the conductive region exposed by the tab. The first region and the second region are arranged along the length direction of the current collector. The technical advantages of embodiments of this application include: a smaller exposed area of ​​the current collector (including the first portion of the third region), resulting in a smaller exposed conductive area of ​​the electrode, which can reduce safety risks, such as reducing the risk of short circuits during puncture operations on the electrochemical device.

[0007] In some embodiments of this application, the electrode 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 surrounds the orthographic projection of the electrode 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 disposed along a first direction, which is the 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. The third end and the fourth end are disposed along a second direction, which 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. Along the first direction, the first portion of the third region is disposed at the first end, and along the second direction, the first portion of the third region is disposed at the third end. The electrode tab includes a first side, a second side, a third side, and a fourth side. The first side and the second side are disposed opposite each other along the first direction, and along the first direction, the distance between the second side of the electrode tab and the second side of the current collector is less than the distance between the first side of the electrode tab and the second side of the current collector. The third and fourth sides of the electrode tab are arranged opposite to each other along a second direction. Along the second direction, the distance between the third side of the electrode tab and the third side of the current collector is less than the distance between the fourth side of the electrode tab and the third side of the current collector. The first part of the third region includes: a first side, a second side, a third side, and a fourth side. The first and second sides of the first part are arranged opposite to each other along a first direction, and along the first direction, the second side of the first part is adjacent to the second side of the electrode tab. The third and fourth sides of the first part are arranged opposite to each other along a second direction, wherein along the second direction, the third side of the first part is adjacent to the third side of the electrode tab, and the fourth side of the first part is adjacent to the fourth side of the electrode tab. Some embodiments of this application include the following technical effects: there is a certain distance between each side of the electrode tab and each side of the first part of the third region. By controlling this distance, for example, by reducing the distance between two adjacent sides, the exposed conductive area of ​​the electrode can be further reduced. In addition, when the electrode tab is connected to the first part of the third region, contact between the electrode tab and the first insulating layer of the first part of the adjacent third region is avoided, which helps to improve the stability of the connection between the electrode tab and the first part of the third region.

[0008] In some embodiments of this application, along the first direction, the distance between the second side of the first portion and the second side of the electrode is L2, the distance between the third side of the first portion and the third side of the electrode is L3, and the distance between the fourth side of the first portion and the fourth side of the electrode is L4, satisfying at least one of the following conditions: a1) L2 ≤ 10 mm; b1) L3 ≤ 10 mm; c1) L4 ≤ 10 mm. The technical effect of some embodiments of this application is that the smaller distance between each side of the electrode and each side of the first portion of the third region further reduces the exposed conductive area of ​​the electrode.

[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 sheet 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 sheet from a whole electrode sheet 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 sheet, the conductive region exposed by the electrode sheet 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 together 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 observed 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 sheet from a whole electrode sheet blank, the cutting process is precise, such that the conductive region exposed by the electrode sheet meets the design requirements.

[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 sheet, the conductive region exposed by the electrode sheet 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 provided 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 portion. Technical effects included in some embodiments of the present application: In the scenario of cutting a single pole piece from a whole pole piece blank, the existence of cutting process errors is allowed, and the cutting process accuracy 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 conductive area exposed by the pole piece can be made smaller, thereby still reducing the safety risk.

[0019] In some embodiments of the present application, the second part of the third region includes: the first side of the second part, the second side of the second part, the third side, and the 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 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 the same straight line; d2) The fourth side of the second part and the fourth side of the first part are on the same straight line. Technical effects included in some embodiments of the present application: The size of the second part of the third region is made smaller, further reducing the conductive area exposed by the pole piece.

[0020] In some embodiments of this application, the electrode 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, and the fifth region is provided with the second insulating layer. 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 this application include the following technical advantages: the sixth region allows for single-sided welding and double-sided forming during soldering, which is beneficial for improving the stability of the soldering between the electrode tab and the first part of the third region.

[0021] In some embodiments of this 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. The technical effect of some embodiments of this application is that the sixth region and the third region at least partially overlap along the thickness direction of the current collector, which is beneficial to improving the stability of the welding between the electrode tab and the third region.

[0022] In some embodiments of this application, the third region includes a blank area where the current collector is exposed. Some embodiments of this application include the following technical advantages: the current collector is directly connected to the tab, which helps reduce the overlap of the tab at the third end of the current collector, reduces the thickness of the electrochemical device, and increases the energy density of the electrochemical device.

[0023] In some embodiments of this application, a coating is provided in the third region, and the electrode tab is connected to the current collector through the coating. Some embodiments of this application include the following technical advantages: the coating facilitates a stable connection between the electrode tab and the current collector, and promotes good electrical contact between them.

[0024] In some embodiments of this application, the thermal conductivity of the coating is greater than that of the current collector. Some embodiments of this application include the following technical advantages: they facilitate the conduction of heat generated inside the current collector and the electrochemical device to the tab and then to the outside through the coating, thus improving heat dissipation in the electrochemical device.

[0025] In some embodiments of this application, the first insulating layer comprises a first insulating material, which includes at least one combination of alumina, aluminum hydroxide, silicon oxide, boehmite, titanium oxide, and zirconium oxide. Some embodiments of this application offer the following technical advantages: excellent electrical insulation performance.

[0026] In some embodiments of this application, the first active material layer includes an active material, which comprises at least one of a combination of lithium transition metal composite oxides and lithium transition metal phosphate compounds. Some embodiments of this application include the following technical advantages: facilitating the electrochemical adsorption and release of metal ions.

[0027] Secondly, embodiments of this application provide an electronic device including a load and an electrochemical device as described in any of the preceding claims, wherein the electrochemical device supplies power to the electronic device.

[0028] In the electrochemical and electronic devices of this application, along the thickness direction of the current collector, the orthographic projection of the second region of the current collector at least partially surrounds the orthographic projection of the first part of the third region, such 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 smaller exposed conductive area of ​​the electrode results in a smaller area of ​​the electrode not covered by the tab after the electrode is connected to the tab, which can reduce safety risks, such as reducing the risk of short circuit when puncturing the electrochemical device. Attached Figure Description

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

[0030] Figure 2 This is a schematic diagram of the structure of the electrode blank according to the first embodiment of this application;

[0031] Figure 3 It is cutting Figure 2 The diagram shows the structure of a single electrode obtained from the electrode blank.

[0032] Figure 4 It is the extreme ear and Figure 3 The diagram shows the structure of the electrode connection.

[0033] Figure 5 It is along Figure 1 The diagram shows a cross-sectional view of the electrode tab connected to the electrode plate in the A-A' direction.

[0034] Figure 6 It is along Figure 1 A schematic diagram of the cross-section after the electrode tabs in the B-B' direction are connected to the electrode plates;

[0035] Figure 7 This is a schematic diagram of the structure of the electrode blank according to the second embodiment of this application;

[0036] Figure 8 It is cutting Figure 7 The diagram shows the structure of a single electrode obtained from the electrode blank.

[0037] Figure 9 It is the extreme ear and Figure 8 The diagram shows the structure of the electrode connection.

[0038] Figure 10 This is a schematic diagram of the structure of a single electrode sheet according to the third embodiment of this application;

[0039] Figure 11 It is the extreme ear and Figure 10 The diagram shows the structure of the electrode connection.

[0040] Figure 12 This is a schematic diagram of the structure of the electrode blank according to the fourth embodiment of this application;

[0041] Figure 13 It is cutting Figure 12 The diagram shows the structure of a single electrode obtained from the electrode blank.

[0042] Figure 14 It is the extreme ear and Figure 13 The diagram shows the structure of the electrode connection.

[0043] Figure 15 This is a schematic diagram of the structure of the second surface of an electrode sheet according to an embodiment of this application;

[0044] Figure 16 This is a schematic diagram of the structure of the second surface of the electrode sheet according to another embodiment of this application.

[0045] The reference numerals in the attached figures are explained as follows:

[0046] Electrochemical device 1

[0047] Electrode 10, Electrode blank 10a, Dashed line O1, Dashed line O2, Dashed 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] Region 1 Z1 Region 2 Z2 Region 3 Z3

[0051] Area 4 Z4 Area 5 Z5 Area 6 Z6

[0052] The first part of the third region Z3, Z31

[0053] First side of the first part Z311 Second side of the first part Z312

[0054] Part 1, Third Side Z313; Part 1, Fourth Side Z314

[0055] The second part of the third region Z32

[0056] Part Two, First Side Z321; Part Two, Second Side Z322

[0057] Part Two, Third Side Z323; Part Two, Fourth Side Z324

[0058] JE20

[0059] First side of the electrode 21; Second side of the electrode 22

[0060] Third side of the electrode 23; Fourth side of the electrode 24

[0061] Packaging bag 30

[0062] Containing cavity 31, main body 30a, encapsulation part 30b, tab adhesive 32

[0063] First direction x, second direction y Detailed Implementation

[0064] The electrochemical device provided in this application includes an electrode and a tab. The electrode of this application has the following configuration: the current collector of the electrode includes a first region, a second region, and a first portion of 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 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. That is, along the width direction of the current collector, the length of the first portion of the third region of the current collector is less than the length of the electrode, so that the exposed conductive area of ​​the current collector is smaller, thereby reducing safety risks, such as reducing the risk of short circuit when puncturing the electrochemical device.

[0065] An electrochemical device is a device that generates electrical energy using chemical reactions. In specific scenarios, electrochemical devices include, but are not limited to, all types of primary batteries, secondary batteries, fuel cells, solar cells, and capacitors (e.g., supercapacitors). Electrochemical devices are preferably lithium secondary batteries, including but not limited to lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, and lithium-ion polymer secondary batteries. The electrochemical devices in this application embodiment can exist in the form of a single battery or a battery module.

[0066] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to various embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments, and not all of them. Based on the embodiments in this 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 this application, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the technical solutions of the corresponding embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0068] Please see Figure 1 This is a schematic diagram showing the structure of an electrochemical device 1 according to an embodiment of this application. The electrochemical device 1 includes an electrode assembly (not shown), tabs 20, and a packaging bag 30.

[0069] The packaging bag 30 has a receiving cavity 31, in which the internal components of the electrochemical device 1 (such as electrode assembly, electrolyte, etc.) are built into the receiving cavity 31. The packaging bag 30 protects these internal components, which helps to improve the protection effect and safety of the electrochemical device 1.

[0070] The packaging bag 30 includes a main body 30a and a sealing part 30b. The electrode assembly and electrolyte are disposed within a receiving cavity 31 formed in the main body 30a. The sealing part 30b and the tabs 20 extend from one end of the main body 30a. The sealing part 30b seals the end of the main body 30a, thereby preventing electrolyte leakage from the end and preventing impurities such as water and oxygen from entering the packaging bag 30. It should be understood that the sealing part 30b also seals the protruding area of ​​the tabs 20. For example, tab adhesive 32 is provided at the junction of the packaging bag 30 and the tabs 20 to achieve a seal at the junction of the packaging bag 30 and the tabs 20. The tabs 20 protrude from the sealing area of ​​the sealing part 30b, which can be referred to as the top sealing area. Figure 5 In the scenario shown, the tab 20 extends from the upper end of the main body 30a, and the top sealing area is located at the upper end of the main body 30a.

[0071] The electrode assembly can be formed by winding several electrode sheets 10. In the scenario where the electrochemical device 1 includes positive and negative polarities, the electrode assembly includes a positive electrode sheet and a negative electrode sheet, as well as a separator disposed between the positive and negative electrode sheets. One end of the tab 20 extends into the packaging bag 30 and is electrically connected to the electrode sheet 10 of the corresponding polarity, while the other end of the tab 20 extends out from one side of the packaging bag 30.

[0072] The electrode 20 includes a first electrode and a second electrode, wherein the first electrode is a negative electrode and the second electrode is a positive electrode. The first electrode is electrically connected to the negative electrode and extends from inside the packaging bag 30 to outside the packaging bag 30, and the second electrode is electrically connected to the positive electrode and extends from inside the packaging bag 30 to outside the packaging bag 30. In other embodiments, the first electrode may be a positive electrode and the second electrode may be a negative electrode. Certain parts of this document describe the structure of the electrode 20 of this application using one type of electrode as an example. Additionally, certain parts of this document describe the structure of the electrode 10 of this application using one type of electrode as an example.

[0073] First Embodiment

[0074] Please refer to the following: Figures 1 to 6 As shown, the electrode 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 a third region Z3. The first region Z1 is provided with a first active material layer 12, and the second region Z2 is provided with a first insulating layer 13. 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 viewed 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 (e.g., at least one of the first insulating layer 13 or the second insulating layer 13a) can be coated onto the current collector 11 using gravure printing. This application can employ publicly known gravure printing techniques, and is not limited thereto.

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

[0077] In this embodiment, the term "end" can be understood as follows: taking a certain element as an example, the end is the edge portion of the element with one side, and along the direction from the side towards the center of the element, the ratio of the length of the edge portion to the length of the element is less than a predetermined threshold, for example, the predetermined threshold is d, satisfying: 10% ≤ d ≤ 30%. For further details, 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 along the first direction x, and the ratio of the length of the upper edge portion to the width of the current collector 11 (i.e. 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 Figure 4 The tab 20 is disposed on the first portion Z31 of the third region Z3. The orthographic projection of the first portion Z31 of the third region Z3 along the thickness direction of the current collector 11 surrounds the orthographic projection of the tab 20 along the thickness direction of the current collector 11. The tab 20 includes a first side 21, a second side 22, a third side 23, and a fourth side 24. The first side 21 and the second side 22 are disposed opposite each other along a first direction x. Along the first direction x, the distance between the second side 22 and the second side 112 of the current collector is less than the distance between the first side 21 and the second side 112 of the current collector, that is, the second side 22 is closer to the second side 112 of the current collector. The third side 23 and the fourth side 24 of the electrode are arranged opposite each other along the second direction y. Along the second direction y, the distance between the third side 23 of the electrode and the third side 113 of the current collector is less than the distance between the fourth side 24 of the electrode and the third side 113 of the current collector. That is, the third side 23 of the electrode is closer to the third side 113 of the current collector.

[0079] The first part Z31 of the third region Z3 includes a first side Z311, a second side Z312, a third side Z313, and a fourth side Z314. The first side Z311 and the second side Z312 are positioned opposite each other along a first direction x. Along the first direction x, the second side Z312 is adjacent to the second side 22 of the electrode tab, and the distance between them is L2. The third side Z313 and the fourth side Z314 are positioned opposite each other along a second direction y. Along the second direction y, the third side Z313 is adjacent to the third side 23 of the electrode tab, and the distance between them is L3. The fourth side Z314 is adjacent to the fourth side 24 of the electrode tab, and the distance between them is L4.

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

[0081] In scenarios where two adjacent sides are not parallel, that is, in other embodiments of this application, the shape of the first part Z31 of the third region Z3 and the tab 20 may not be... Figures 4 to 16 The rectangle shown can be a trapezoid or other irregular shape. The first part Z31 of the third region Z3 and the side of the tab 20 can be straight lines extending along the first direction x and / or along the second direction y, or oblique lines not extending along the first direction x and the second direction y, or even arcs, curves, etc. In this regard, the way to obtain the distance between two adjacent side edges includes, but is not limited to, one of the following:

[0082] First, 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 part and the second side 22 of the tab is the distance L2 between these two sides.

[0083] II. The distance can be the average distance between two adjacent sides. Taking the measurement of the distance L2 between the second side Z312 of the first part and the second side 22 of the electrode as an example, the second side Z312 of the first part and the second side 22 of the electrode are divided into multiple equally spaced segments along the second direction y. The more segments, the more accurate the measurement result. In each segment, two sampling points a1 and a2 are set along the first direction x. These two sampling points a1 and a2 are located on the second side Z312 of the first part and the second side 22 of the electrode, respectively. Sampling points a1 and a2 are two points located along the first direction x. The distance between each segment along the first direction x is the distance between the two sampling points a1 and a2. Using this as an example, the distance between the two sampling points a1 and a2 in all segments is measured, and the average value is calculated. This average value is used as the distance between two adjacent sides.

[0084] Each side of the tab 20 is spaced a certain distance from each side of the first portion Z31 of the third region Z3. By controlling this distance, for example, by reducing the distance between two adjacent sides, the exposed conductive area of ​​the electrode 10 can be further reduced. Furthermore, when the tab 20 is connected to the first portion Z31 of the third region, contact between the tab 20 and the first insulating layer 13 of the adjacent first portion Z31 of the third region Z3 is avoided, which helps improve the stability of the connection between the tab 20 and the first portion Z31 of the third region Z3. In some embodiments, at least one of the following conditions is satisfied: L2 ≤ 10 mm; L3 ≤ 10 mm; L4 ≤ 10 mm. The aforementioned distance between adjacent sides helps to improve the stability of the electrical connection between the tab 20 and the electrode 10 while minimizing the conductive area of ​​the electrode 10 not covered by the tab 20. Optionally, the ratio of the tab 20 to the first portion Z31 of the third region Z3 can be 0.3 to 1, resulting in a smaller exposed conductive area of ​​the electrode 10.

[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 during 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, thereby obtaining 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 for 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 manufacturing processes, 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 difference in the lengths of the two sides to the longest one of the first side Z311 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 in 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 insulating material. This first insulating layer 13 is disposed in the second region Z2 and serves to electrically insulate the second region Z2 from other conductive components (e.g., tabs 20, 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 portion Z31 of the third region Z3. The first portion Z31 of the third region Z3 can be the area where the electrode 10 and the tab 20 are electrically connected; this area is a conductive region. Here, along the first direction x, which is the width direction of the current collector 11, the length of the exposed conductive region of the electrode 10 is less than the length of the electrode 10. The exposed conductive region of the electrode 10 is smaller, and after the electrode 10 is connected to the tab 20, the area of ​​the electrode 10 not covered by the tab 20 is smaller, thereby reducing safety risks, such as reducing the risk of short circuits when puncturing the electrochemical device 1.

[0089] Optionally, the area where the tab 20 is electrically connected to the electrode 10 may be provided with a seal (not shown in the figure). This seal not only covers the connection area between the tab 20 and the electrode 10 to prevent welding burrs in the connection area from puncturing the packaging bag 30, but also covers the first portion Z31 of the entire third region Z3. In one embodiment, the seal includes, but is not limited to, insulating materials such as adhesive tape or sealant.

[0090] Second Embodiment

[0091] This application uses the same reference numerals to identify structural elements with the same name. Based on the description of the foregoing embodiments, but differing from them, please 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 portion of the orthographic projection of the first side 111 of the current collector along the thickness direction of the current collector 11 together 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 viewed along the thickness direction of the current collector 11, the first part, the first side Z311, coincides with the first side 111 of the current collector, and W1 = 0. Compared to the aforementioned... Figure 4 As shown, please refer to Figure 7 and Figure 9 As shown, the electrode blank 10a is cut along the dotted line O1 to obtain two electrodes 10 in this embodiment. The cutting process is precise, so that the exposed conductive area of ​​the electrode 10 (the first part Z31 of the third region Z3) conforms to the design.

[0092] Third Embodiment

[0093] When preparing the first portion 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 consequently adversely affecting the energy density of the electrochemical device 1, a stamping process can be used to remove the first insulating layer 13 between the third side Z313 of the first portion and the first side 111 of the current collector, leaving an arc-shaped notch. Please refer to... Figure 10 and Figure 11 In this embodiment, the third side Z313 and the fourth side Z314 of the first portion each independently include an arc-shaped portion. This arc-shaped portion is disposed at the first end of the current collector 11. Other embodiments may include arc-shaped portions. The following description uses an arc-shaped portion as an example.

[0094] In some embodiments, the extension length of the arc-shaped portion along the first direction x is no more than 10 mm. The smaller extension length results in a smaller area for the arc-shaped notch, ensuring that the notch does not affect the stability of the connection between the tab 20 and the first portion Z31 of the third region Z3. The extension length can be understood as the straight-line distance between the start and end points of the arc-shaped portion along the first direction x. Therefore, the extension length of the arc-shaped portion can be obtained by measuring the straight-line distance between its start and end points along the first direction x.

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

[0096] The endpoint of the arc-shaped portion refers to the rightmost point of the arc-shaped portion along the first direction x, that is, the point where the arc-shaped portion is furthest 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 can be greater than 5%. For example, in Figure 12 and 13 In the scenario shown, the upper end of the first part Z31 of the third region Z3 has an arc-shaped section, forming an arc-shaped notch. The length of the first side Z311 of the first part is less than the length of the second side Z312 of the first part. It should be understood that the length of the first side Z311 of the first part is the distance between the endpoint of the arc-shaped section of the third side Z313 of the first part and the endpoint of the arc-shaped section of the fourth side Z314 of the first part along the second direction y.

[0098] Fourth embodiment

[0099] Based on the description of the second embodiment described above, but differing from it, please refer to... Figures 12 to 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 disposed opposite to each other along the first direction x. The orthographic projection of the second region Z2 along the thickness direction of the current collector 11 and the orthographic projection of the second side 112 of the current collector along the thickness direction of the current collector 11 together surround the orthographic projection of the second part Z32 of the third region Z3 along the thickness direction of the current collector.

[0100] The second part Z32 of the third region Z3 includes a first side Z321 and a second side Z322 of the second part, 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 disposed opposite to each other 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 disposed opposite to each other 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 the same straight line.

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

[0106] Compared with the foregoing Figure 2 and Figure 3 shown, please refer to Figure 12 and Figure 13As shown, the electrode blank 10a is cut along the dotted line O3. The portion between two adjacent dotted lines O3 yields one electrode 10 in this embodiment. In the scenario where a single electrode 10 is obtained by cutting a whole electrode blank 10a, the existence of cutting process errors is allowed, reducing the cutting process accuracy. Based on this cutting process, the two sides in the aforementioned conditions (3) and (4) being on a straight line includes: the two sides being on a straight line, or approximately on a straight line. Approximately on a straight line can be understood as: along the second direction y, the maximum distance between the two sides is less than a preset threshold. This preset threshold can be set according to the production process error, for example, 2 mm.

[0107] In addition, for the first part Z31 and the second part Z32 of the third region Z3 with other shapes, the part between the two adjacent dashed lines O3 of the electrode blank 10a is of other shapes. The two sides in the aforementioned conditions (3) and (4) may not be able to be on a straight line at all. For example, before the electrode blank 10a is cut, the third side Z323 of the second part and the third side Z313 of the first part are on an arc. After the cutting, since these two sides are the same side of the same shape between the two adjacent dashed lines O3, 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 along the second direction y should be within a certain threshold range, for example, not greater than 5%.

[0108] It should be understood that the structural design of the electrode 10 in any of the foregoing embodiments is only an exemplary demonstration. Other embodiments may set the shape of the third region Z3 differently from the foregoing, as long as the following is achieved: the orthographic projection of the second region 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 region 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 electrode 10 is less than the length of the electrode 10. The conductive area exposed by the electrode 10 is smaller. After the electrode 10 is connected to the tab 20, the area of ​​the electrode 10 not covered by the tab 20 is smaller, thereby reducing safety risks, such as reducing the risk of short circuit when puncturing the electrochemical device 1.

[0109] Based on the description of any of the foregoing embodiments, please refer to the following: Figures 15 to 16 As shown, the electrode 10 further includes a second active material layer 12a and a second insulating layer 13a. 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 the second active material layer 12a, and the fifth region Z5 is provided with the second insulating layer 13a. 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 can be the same or different. The materials of the second insulating layer 13a and the first insulating layer 13 can be the same or different. The insulating materials and insulating properties of the second insulating layer 13a and the first insulating layer 13 can 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 alumina 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 may be greater than or equal to 1 Gohm, exhibiting good electrical insulation performance.

[0111] Therefore, 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 the welding between the tab 20 and the third region Z3.

[0112] In some embodiments, the sixth region Z6 and the third region 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 into 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 into 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... Figure 15 and Figure 16 As shown.

[0116] In addition, in some embodiments of this application, the third region Z3 includes a blank area exposed by the current collector 11, which directly exposes the surface of the current collector 11. That is, the current collector 11 is directly connected to the tab 20, which helps to reduce the overlap of the tab 20 at the third end of the current collector 11, reduce the thickness of the electrochemical device 1, and increase the energy density of the electrochemical device 1.

[0117] In some embodiments of this 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. This coating facilitates a stable connection between the tab 20 and the current collector 11, and promotes good electrical contact between them. The specific type of coating is not limited in this application. For example, the thermal conductivity of the coating can be greater than that of the current collector 11, which facilitates the conduction of heat generated inside the current collector 11 and the electrochemical device 1 to the tab 20 and then to the outside, thus improving the heat dissipation of the electrochemical device 1. Alternatively, the electrical conductivity of the coating can be greater than that of the current collector 11, which improves the electrical connection between the current collector 11 and the tab 20 and reduces the resistance of the electrical connection.

[0118] The electrode 10 in any of the foregoing embodiments can be a positive electrode, a negative electrode, or both the positive and negative electrodes can be designed using the electrode 10 in any of the foregoing embodiments.

[0119] Positive electrode sheet

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

[0121] There are no particular restrictions on the material of the positive electrode current collector (e.g., current collector 11), and it 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: metallic 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 can be one or more layers, with each layer in a multilayer positive electrode active material layer containing the same or different positive electrode active materials. The positive electrode active material is a substance capable of reversibly inserting and deintercalating metal ions such as lithium ions. Preferably, the rechargeable 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 depositing on the negative electrode during charging.

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

[0124] Substances with different compositions can adhere to the surface of the positive electrode active material. These adhered substances include, but are 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, etc.

[0125] Methods for attaching substances to the surface of the positive electrode active material layer include, but are not limited to: methods of dissolving or suspending the attaching substance in a solvent and then adding it into the positive electrode active material followed by drying; methods of dissolving or suspending the attaching substance in a solvent and then reacting it by heating or the like after adding it into the positive electrode active material; and methods of adding it to a positive electrode active material precursor while simultaneously calcining it. In the example of attached carbon, a method of mechanical attachment using carbon materials (such as activated carbon) can be used.

[0126] The presence of a substance adhering to 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 improving the lifespan of the electrochemical device 1. In the description herein, the positive electrode active material layer and the substance adhering to its surface 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 alumina, zirconium oxide, aluminum hydroxide, silicon oxide, boehmite, and titanium oxide, or a combination of multiple thereof. Optionally, it is mixed with a binder at a mass ratio of 3-15%.

[0128] Negative electrode sheet

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

[0130] In some implementations, the negative current collector (e.g., 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 can be one or more layers, and each layer in a multilayer negative electrode active material layer can contain the same or different negative electrode active materials. The negative electrode active material is any material capable of reversibly inserting and de-intercalating metal ions such as lithium ions.

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

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

[0134] isolation layer

[0135] An insulating layer, disposed between the positive and negative electrode plates, is used to isolate the positive and negative electrode plates and prevent electrons from freely passing through within the electrochemical device 1, while allowing ions in the electrolyte to pass through freely. The positive electrode plate, negative electrode plate, and insulating layer are wound together to form the electrode assembly of the electrochemical device 1.

[0136] In the scenarios shown in the aforementioned embodiments, the third region Z3 is disposed at the head of the electrode 10. In the electrode assembly formed by winding, the tab 20 electrically connected to the third region Z3 is located at the head of the electrode 10, that is, at the innermost ring of the electrode assembly.

[0137] In the wound electrode assembly, the third region Z3 can also be located 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 ring of the electrode assembly. Alternatively, in other embodiments, the third region Z3 can be located at the head or tail of the negative electrode sheet, which can also achieve the aforementioned beneficial effects.

[0138] Another embodiment of this application provides an electronic device including the electrochemical device 1 of any of the above embodiments.

[0139] Electronic devices can take many specific forms, such as drones, electric vehicles, electric cleaning tools, energy storage products, electric bicycles, and electric navigation tools. In practical applications, electronic devices specifically include, but are not limited to: laptops, pen-based computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and lithium-ion capacitors.

[0140] Those skilled in the art will understand that, apart from elements specifically designed for mobile purposes, the constructions according to embodiments of this application can also be applied to stationary electronic devices.

[0141] Since the electronic device has the electrochemical device 1 of any of the foregoing embodiments, the electronic device is able to produce the beneficial effects of the electrochemical device 1 of the corresponding embodiments.

[0142] Without further restrictions, an element defined by the phrase "comprising a..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, components, features, and elements with the same name in different embodiments may have the same meaning or may have different meanings, the specific meaning of which needs to be determined by its interpretation in that specific embodiment or by further consideration of the context of that specific embodiment.

[0143] Furthermore, although this document uses terms such as "first," "second," and "third" to describe various types of information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. The singular forms "a," "an," and "the" used herein are intended to also include the plural forms. The terms "or" and "and / or" are interpreted as inclusive, or meaning either one or any combination thereof. Exceptions to this definition only occur when combinations of elements, functions, steps, or operations are inherently mutually exclusive in some way.

[0144] The technical solution of this application is described by way of specific embodiments below:

[0145] Example 1

[0146] The positive electrode uses the above-mentioned Figure 9The structure shown is wound to form an electrode assembly, with L2 being 2mm, and L3 and L4 both being 2mm. The first insulating layer 13 is composed of 90% alumina and 10% binder by mass percentage.

[0147] Example 2:

[0148] The positive electrode uses the above-mentioned Figure 9 The structure shown is wound to form an electrode assembly, with L2 being 1.5 mm, and L3 and L4 both being 2 mm. The first insulating layer 13 is composed of 90% aluminum oxide and 10% binder by mass percentage.

[0149] Example 3:

[0150] The positive electrode uses the above-mentioned Figure 9 The structure shown is wound to form an electrode assembly, with L2 being 2 mm, and L3 and L4 both being 1.5 mm. The first insulating layer 13 is composed of 90% aluminum oxide and 10% binder by mass percentage.

[0151] Example 4:

[0152] The positive electrode uses the above-mentioned Figure 9 The structure shown is wound to form an electrode assembly, with L2 being 2mm, and L3 and L4 both being 2mm. The first insulating layer 13 is composed of 85% aluminum oxide and 15% binder by mass percentage.

[0153] Example 5:

[0154] The positive electrode uses the above-mentioned Figure 9 The structure shown is wound to form an electrode assembly, with L2 being 1.5 mm, and L3 and L4 both being 2 mm. The first insulating layer 13 is composed of 85% alumina and 15% binder by mass percentage.

[0155] Example 6:

[0156] The positive electrode uses the above-mentioned Figure 9 The structure shown is wound to form an electrode assembly, with L2 being 2 mm, and L3 and L4 both being 1.5 mm. The first insulating layer 13 is composed of 85% aluminum oxide and 15% binder by mass percentage.

[0157] Example 7:

[0158] The positive electrode uses the above-mentioned Figure 14 The structure shown is wound to form an electrode assembly. The first part Z31 of the third region Z3 is rectangular. The length of the first part Z31 of the third region Z3 is 2mm and the width is 8mm. The first insulating layer 13 is composed of 90% aluminum oxide and 10% binder by mass percentage.

[0159] Example 8:

[0160] The positive electrode uses the above-mentioned Figure 14 The structure shown is wound to form an electrode assembly. The first part Z31 of the third region Z3 is rectangular. The length of the first part Z31 of the third region 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 percentage.

[0161] Example 9:

[0162] The positive electrode uses the above-mentioned Figure 14 The structure shown is wound to form an electrode assembly. The first part Z31 of the third region Z3 is rectangular. The length of the first part Z31 of the third region Z3 is 3mm and the width is 8mm. The first insulating layer 13 is composed of 90% aluminum oxide and 10% binder by mass percentage.

[0163] Example 10:

[0164] The positive electrode uses the above-mentioned Figure 14 The structure shown is wound to form an electrode assembly. The first part Z31 of the third region Z3 is rectangular. The length of the first part Z31 of the third region Z3 is 2mm and the width is 10mm. The first insulating layer 13 is composed of 90% aluminum oxide and 10% binder by mass percentage.

[0165] Example 11:

[0166] The positive electrode uses the above-mentioned Figure 14 The structure shown is wound to form an electrode assembly. The first part Z31 of the third region Z3 is rectangular. The length of the first part Z31 of the third region Z3 is 2mm and the width is 12mm. The first insulating layer 13 is composed of 90% aluminum oxide and 10% binder by mass percentage.

[0167] Example 12:

[0168] The positive electrode uses the above-mentioned Figure 14 The structure shown is wound to form an electrode assembly. The first part Z31 of the third region Z3 is rectangular. The length of the first part Z31 of the third region Z3 is 2mm and the width is 14mm. The first insulating layer 13 is composed of 90% aluminum oxide and 10% binder by mass percentage.

[0169] Comparative example:

[0170] The positive electrode sheet is formed by winding using existing technology. 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] Needle prick test method

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

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

[0174] 3) Measure the temperature throughout the process and observe the phenomena;

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

[0176] The performance test results of Examples 1-12 and the comparative examples are shown in the table below. In the table, the nail penetration pass rate is the proportion of lithium-ion batteries that passed the nail 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 passed the nail 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 Example 11 10 / 10 Example 12 10 / 10 Comparative Example 4 / 10

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

[0179] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this specification and drawings are similarly included in the patent protection scope of this application.

Claims

1. An electrochemical device comprising an electrode and a tab, said electrode comprising: A current collector, the current collector comprising a first surface and a second surface disposed opposite to each other; First active material layer; and The 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; The electrode tab is disposed on the current collector, and the orthographic projection of the first part of the third region along the thickness direction of the current collector surrounds the orthographic projection of the electrode tab along the thickness direction of the current collector. Furthermore, there is a predetermined distance, which is not equal to zero, between each side of the electrode tab and each side corresponding to the first part of the third region.

2. The electrochemical device according to claim 1, wherein, The current collector includes: A first end and a second end are disposed along a first direction, wherein the first direction is the 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 provided along a second direction, which 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. Along the first direction, the first portion of the third region is disposed at the first end. Along the second direction, the first portion of the third region is disposed at the third end. The electrode includes: The first and second sides of the electrode tabs are arranged opposite each other along the first direction. Along the first direction, the distance between the second side of the electrode tab and the second side of the current collector is less than the distance between the first side of the electrode tab and the second side of the current collector. The third and fourth sides of the electrode tabs are arranged opposite each other along the second direction. Along the second direction, the distance between the third side of the electrode tab and the third side of the current collector is less than the distance between the fourth side of the electrode tab and the third side of the current collector. The first part of the third region includes: A first portion of a first side and a first portion of a second side are disposed opposite to each other along the first direction, wherein the first portion of the second side is adjacent to the second side of the electrode tab along the first direction; and The first portion of the third side and the first portion of the fourth side are arranged opposite 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 electrode tab, and the fourth side of the first part is adjacent to the fourth side of the electrode tab.

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

4. The electrochemical device according to claim 2, wherein, 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.

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, 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 no greater than 5%.

7. The electrochemical device according to claim 2, wherein, The orthographic projection of the second region along the thickness direction of the current collector and a portion of the orthographic projection of the first side of the current collector along the thickness direction together surround the orthographic projection of the 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 part and the length of the second side of the first part is greater than 5%.

9. The electrochemical device according to claim 8, wherein, The length of the first side of the first part is less than the length of the second side of the first part.

10. The electrochemical device according to claim 6, wherein, The third side of the first part and the fourth side of the first part each independently include an arc-shaped portion or a quasi-arc-shaped portion, and the arc-shaped portion or quasi-arc-shaped portion is disposed at the first end.

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, which is disposed at the second end along the first direction.

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 together surround the orthographic projection of the second part 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 region includes: A second portion of a first side and a second portion of a second side are arranged opposite to each other along the first direction. Along the first direction, the second portion of the first side is adjacent to the second side of the current collector, and the second portion of the second side coincides with the second side of the current collector. The second portion of the third region, with its third side edge and fourth side edge arranged opposite to each other along the second direction, 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 greater than 5%; c2) The third side of the second part and the third side of the first part are on the same straight line; d2) The fourth side of the second part and the fourth side of the first part are on the same straight line.

15. The electrochemical device according to claim 1, wherein, The electrode 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, and the fifth region is provided with the second insulating layer. 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 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.

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

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

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

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

21. The electrochemical device according to claim 1, wherein, The first active material layer includes an active material, which includes at least one of a combination of lithium transition metal composite oxides and lithium transition metal phosphate compounds.

22. An electronic device, wherein, It includes a load and an electrochemical device as described in any one of claims 1-21, wherein the electrochemical device supplies power to the electronic device.

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