WO2023147701A1

WO2023147701A1 - Electrochemical device and electric device

Info

Publication number: WO2023147701A1
Application number: PCT/CN2022/075380
Authority: WO
Inventors: 曹维毅
Original assignee: 宁德新能源科技有限公司
Priority date: 2022-02-07
Filing date: 2022-02-07
Publication date: 2023-08-10
Also published as: CN116097496A

Abstract

An electrochemical device and an electric device. The electrochemical device comprises an electrode piece assembly and a heating assembly; the electrode piece assembly comprises a first electrode piece, the first electrode piece comprises a first current collector, a first surface of the first current collector is provided with a first active material layer, a second surface of the first current collector is provided with a second active material layer, and the first active material layer or the second active material layer is provided with a second groove; the heating assembly comprises a heating part and a first electrical connection part, the first electrical connection part is provided with a first connection area, the heating part is provided with a second connection area, and the first connection area is connected to the second connection area; and upon inspection along the thickness direction of the electrode piece assembly, the second groove covers the first connection area. In the present solution, a protrusion in the thickness direction of the first connection area where the first electrical connection part connects to the heating part is at least partially offset by the second groove, ultimately causing an improvement in the flatness of the electrochemical device, and an electrochemical reaction interface of positive and negative electrodes is improved.

Description

Electrochemical devices and electrical devices

technical field

The present application relates to the field of batteries, in particular to an electrochemical device and an electrical device.

Background technique

Lithium-ion batteries are widely used in daily life, providing great convenience and richness to people's life. However, the polarization of lithium-ion batteries is aggravated during charging and discharging under low temperature conditions, which reduces the service life of the batteries. At the same time, the high-power application scenarios in recent years have challenged the rate performance of lithium-ion batteries, especially at low temperatures. Existing methods to improve the low-temperature performance of lithium-ion batteries include heating the battery to room temperature and avoiding the use of the battery in low-temperature scenarios. This method does not need to change the chemical system, can improve battery kinetics, and can broaden the operating temperature of lithium-ion batteries Range, realize the use of lithium-ion batteries in low temperature environment, and can maintain the same charge and discharge rate as normal temperature. Therefore, improving the low-temperature performance of lithium-ion batteries by increasing the system kinetics through heating has attracted widespread attention.

At present, in the research of battery heating schemes, external heating methods and internal heating methods are often used. Generally speaking, external heating methods have low heating efficiency and risk of corrosion. Compared with external heating, the internal heating method is to place a heating sheet inside the battery to heat the battery. Compared with external heating, the heating rate of this method can be significantly improved, but the structural scheme for internal heating in the prior art It will cause the problem of uneven thickness inside the battery, thereby reducing the consistency of the electrochemical reaction interface of the positive and negative electrodes, increasing the risk of lithium precipitation, and reducing the cycle performance of the lithium-ion battery.

Contents of the invention

In view of the above problems, the present application provides an electrochemical device with high flatness and improved electrochemical reaction interface.

To achieve the above object, the application provides an electrochemical device, comprising:

case;

The first tab and the second tab;

The pole piece assembly, the pole piece assembly is accommodated in the housing, the pole piece assembly includes a first pole piece and a second pole piece, the first pole piece includes a first current collector, and the first current collector includes opposite first and second surfaces , the first surface is provided with a first active material layer, the second surface is provided with a second active material layer, the first active material layer is provided with a first groove, and the first surface includes a first uncoated layer located in the first groove. region, the first tab is arranged in the first groove and connected to the first uncoated region; the first active material layer or the second active material layer is provided with the second groove; and a heating assembly, the heating assembly includes a heating part , the first power connection part and the second power connection part, the heating part is accommodated in the casing, the first power connection part is provided with a first connection area, the heating part is provided with a second connection area, the first connection area and the second connection area Connection; viewed along the thickness direction of the pole piece assembly, the second groove covers the first connection area.

In the electrochemical device of the above scheme, the first groove and the second groove are respectively arranged on the active material layers on both sides of the first current collector, and then the first tab is arranged in the first groove, and the second groove covers The first connection area connecting the first electrical connection part and the heating part in the heating assembly, so that the protrusion in the thickness direction of the designed first connection area connecting the first electrical connection part and the heating part is at least partially covered by the second groove Offset, ultimately improving the flatness of the electrochemical device and improving the electrochemical reaction interface of the positive and negative electrodes.

Optionally, the second active material layer is provided with a second groove, the second surface includes a second uncoated area located in the second groove, along the thickness direction of the first current collector, the first uncoated area and the second Two uncoated areas face each other. At this time, the second active material layer on the back side of the first groove is removed to form a second groove, because the second active material layer on the back side may be damaged when the first tab is connected to the first uncoated region, the first tab is removed. The second active material layer on the back of the groove can improve the consistency of the electrochemical reaction interface of the second active material layer and at the same time use the space to reduce the influence caused by the protrusion of the first connection region.

Optionally, the second power connection part is connected to the heating part; viewed along the thickness direction of the pole piece assembly, the second power connection part and the second tab are separated from each other. Mutual separation means that along the thickness direction of the pole piece assembly, the projections of the second power connection part and the second pole lug do not overlap. By setting the second power connection part and the second pole lug apart from each other, the second The power connection part and the second tab do not interfere with each other in the thickness direction of the pole piece assembly, so that the second power connection part and the second tab are not easy to cause overheating of the heating component due to false contact, and then trigger the electrochemical device. thermal runaway.

Optionally, the second pole piece includes a second current collector, the second current collector includes an opposite third surface and a fourth surface, the third surface is provided with a third active material layer, and the fourth surface is provided with a fourth active material layer , the third active material layer is provided with a third groove, the third surface includes a third uncoated area located in the third groove, and the second tab is located in the third groove and connected to the third uncoated area ; The third active material layer or the fourth active material layer is provided with a fourth groove; the second connection part is provided with a third connection area, the heating part is provided with a fourth connection area, and the third connection area is connected to the fourth connection area ; Viewed along the thickness direction of the pole piece assembly, the fourth groove covers the third connection area. By setting the third groove and the fourth groove on the active material layers on both sides of the second current collector respectively, and then setting the second tab in the third groove, the fourth groove covers the second electrical connection in the heating assembly. part and the heating part, so that the protrusion in the thickness direction of the third connecting part connecting the designed second electrical connection part and the heating part is at least partially offset by the fourth groove, and finally the electrochemical device The flatness is improved, and the electrochemical reaction interface of the positive and negative electrodes is improved.

Optionally, the fourth active material layer is provided with a fourth groove, the fourth surface includes a fourth uncoated region located in the fourth groove, and along the thickness direction of the second current collector, the third uncoated region and the first Four uncoated regions face each other. At this time, the fourth active material layer on the back of the third groove is removed to form a fourth groove. Since the second tab is connected to the third uncoated region, the fourth active material layer on the back may be damaged, and the third active material layer is removed. The fourth active material layer on the back of the groove can improve the consistency of the electrochemical reaction interface of the fourth active material layer and at the same time use the space to reduce the influence caused by the protrusion of the third connection region.

Optionally, the first tab and the first uncoated area are connected by welding; the connection between the first tab and the first uncoated area can be made tighter by welding, so that it is not easy to fall off and extend The service life of the electrochemical device.

Optionally, the surface of the first active material layer is provided with a first insulating adhesive layer, and the first insulating adhesive layer covers the first groove; by providing the first insulating adhesive layer, it is possible to prevent the edge of the first tab and its contact with the first The burr at the welding part of the current collector pierces the separator to cause a short circuit, improving the safety of the electrochemical device.

Optionally, the first tab and the first power connection part respectively extend out of the casing and are connected outside the casing.

Optionally, the first groove is disposed between two ends of the first active material layer in the length direction. By arranging the first groove between the two ends in the length direction, the electron conduction paths of the active material layers on both sides of the first tab can be reduced to improve the rate performance of the electrochemical device.

Optionally, a second insulating adhesive layer is provided on the surface of the second active material layer, and the second insulating adhesive layer covers the second groove. Covering the second groove with the insulating adhesive layer can prevent the welding burr from piercing the diaphragm and cause a short circuit on the one hand, and play a protective role; on the other hand, it can at least partially fill the second groove to improve the flatness of the electrochemical device , to improve the interface of positive and negative electrochemical reactions.

Optionally, the first current collector is also provided with a fifth uncoated area, the fifth uncoated area is an area that does not cover the first active material layer or the second active material layer; area surface. Setting the heating part on the uncoated area on the current collector can make full use of the space in the pole piece where the first current collector is not coated with active material, thereby reducing the influence of the heating part on the thickness of the electrochemical device.

Optionally, the pole piece assembly is a winding structure, and the fifth uncoated region is located at the winding center of the winding structure. The pole piece assembly is a winding structure, and there is a certain gap at the center of the winding due to the rigidity of the inner pole piece. The fifth uncoated area is set at the winding center of the winding structure, so that the heating part can be set At the center of the winding, make full use of the gap, thereby reducing the influence of the heating part on the winding thickness of the pole piece assembly; at the same time, the heating part is set at the center of the winding, which can provide support for the inner pole piece during the hot pressing process , Inhibit the peeling of the active material layer due to excessive bending of the inner pole piece at the corner, thereby improving the electrochemical reaction interface of the positive and negative electrodes.

Optionally, the heating part includes a heating body and an insulating layer located on the surface of the heating body. By arranging an insulating layer on the surface of the heating body, adverse consequences such as battery damage due to short circuit between the heating body and pole pieces can be prevented.

Optionally, the material of the heating body includes at least one of metal material or carbon material; the material of the heating body only needs to be able to conduct electricity to generate heat, and it only needs to select a suitable dielectric and resistance value.

Optionally, the material of the insulating layer includes at least one of polymers or inorganic insulating materials. The insulating layer is designed as a polymer or an inorganic insulating material, which can achieve the insulating effect.

The present application also provides an electrical device, which includes the electrochemical device described in the above technical solutions.

In the present application, by designing the above-mentioned electrochemical device, the protrusion in the thickness direction of the first connecting region that can connect the designed first electrical connection part and the heating part is at least partially offset by the second groove, and finally makes the electrochemical device The flatness is improved, and the electrochemical reaction interface of the positive and negative electrodes is improved.

Description of drawings

The accompanying drawings are only used to illustrate the principles, implementations, applications, features and effects of specific embodiments of the present invention and other related content, and should not be considered as limiting the present application.

In the accompanying drawings of the manual:

FIG. 1 is a schematic diagram of an electrical device described in an embodiment of the present application;

Fig. 2 is the structural representation of the non-flat pole piece assembly described in the comparative example of the present application;

Fig. 3 is the schematic structural diagram of the electrochemical device described in the embodiment of the present application;

Fig. 4 is a schematic diagram of the pole piece assembly described in the embodiment of the present application;

Fig. 5 is a schematic diagram of the unfolded state of the first pole piece described in the embodiment of the present application;

Fig. 6 is a diagram of the unfolded state of the heating assembly and the first pole piece described in the embodiment of the present application;

Fig. 7 is a schematic diagram of the heating assembly described in the embodiment of the present application;

Fig. 8 is a schematic diagram of the fifth uncoated area of the first pole piece according to the embodiment of the present application.

The reference numerals involved in the above-mentioned drawings are explained as follows:

100. Electric device,

10. Shell,

110. Pole piece assembly

1. The first pole piece,

11. The first collection of fluids,

12. The first active material layer,

13. The first pole ear,

14. The first groove,

15. The second active material layer,

16. The second groove,

17. Fifth uncoated zone,

2. The second pole piece,

21. The second collector,

22. The fourth active material layer,

23. The second pole ear,

24. The third groove,

25. The third active material layer,

26, the fourth groove,

30. Heating components,

3. Heating part,

31. The first power connection department,

311. The first connection area,

312. The second connection area,

32. The second power connection part,

323. The third connecting area,

324. The fourth connection area.

Detailed ways

In order to describe in detail the possible application scenarios, technical principles, implementable specific solutions, achievable goals and effects, etc. of the present application, the following will be described in detail in conjunction with the listed specific embodiments and accompanying drawings. The embodiments described herein are only used to illustrate the technical solutions of the present application more clearly, so they are only examples, and cannot be used to limit the protection scope of the present application.

Reference herein to an "embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. In principle, in this application, as long as there is no technical contradiction or conflict, each technical feature mentioned in each embodiment can be combined in any way to form a corresponding implementable technical solution.

Unless otherwise defined, the meanings of the technical terms used herein are the same as those commonly understood by those skilled in the art to which the application belongs; the use of relevant terms herein is only to describe specific embodiments, and is not intended to limit the application .

In this application, terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is a relationship between these entities or operations. Any actual quantitative, primary or sequential relationship.

In the description of the embodiments of the present application, expressions related to space used, such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", " Left, right, vertical, horizontal, vertical, top, bottom, inner, outer, clockwise, counterclockwise, axial, radial, circumferential, etc. The indicated orientation or positional relationship is based on the specific embodiment or the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the specific embodiment of the application or for the reader’s understanding, rather than indicating or implying that the referred device or component must Having a specific position, a specific orientation, or being constructed or operated in a specific orientation should not be construed as limiting the embodiments of the present application.

Unless otherwise specified or limited, in the description of the embodiments of the present application, terms such as "installation", "connection", "connection", "fixation" and "setting" should be understood in a broad sense. For example, the "connection" can be a fixed connection, a detachable connection, or an integrated arrangement; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary; It may be a communication within two elements or an interaction relationship between two elements. Those skilled in the technical field to which the present application belongs can understand the specific meanings of the above terms in the embodiments of the present application according to specific situations.

Please refer to Fig. 1, an electrical device 100 provided for an embodiment, the electrical device 100 of the present application includes any device that can use an electrochemical device as a power source, including such as a mobile phone, a camera, a notebook computer, a wearable It also includes electric bicycles, electric cars, airplanes, EMUs, ships and other means of transportation, as well as electrical equipment installed on equipment, buildings and other facilities that use batteries. In the embodiment shown in FIG. 1 , the electric device 100 may be a mobile phone, and the battery is disposed in the mobile phone.

The internal heating method is to place a heating sheet inside the battery to heat the battery. The inventors of the present application found that when the heating sheet is added inside the battery, the protrusions at the connection between the heating electrode and the heating sheet will bring about extreme heat inside the battery. Due to the problem of uneven thickness of the sheet assembly, in the subsequent hot pressing formation process, there will be overpressure in the raised part, which will reduce the consistency of the electrochemical reaction interface of the positive and negative electrodes. In the comparative example shown in FIG. 2 , it shows that a heating part 3 is arranged inside the pole piece assembly 110, and the first electrical connection part 31 is connected to the surface of the heating part 3 to form a protrusion. The external extrusion occupies the position originally belonging to the positive and negative electrodes, and the layers are extruded outwards, which eventually leads to the problem of bulges and unevenness on the outermost part of the pole piece assembly 110, and causes overpressure on the bulges, reducing the positive and negative electrodes. The consistency of the electrode electrochemical reaction interface. The inventors of the present application discovered the above-mentioned problems, and invented the following electrochemical device for improvement.

Please refer to Fig. 3 and Fig. 4, in Fig. 3, the structural representation of the electrochemical device is shown, including: the housing 10; the electrochemical device also includes the first tab 13 and the second tab 23, the first tab 13 and The second tab 23 extends out of the housing 10 for providing electrical connection to the outside. The electrochemical device also includes a first electrical connection part 31 and a second electrical connection part 32 protruding from the casing 10 for connecting to a heating circuit for heating. Viewed along the thickness direction X of the pole piece assembly 110 , that is, the direction inward perpendicular to the plane of the paper, the first tab 13 covers the first power-connecting portion 31 . In some embodiments, the first tab 13 and the first power connection part 31 are connected outside the housing 10 .

The pole piece assembly 110 is accommodated in the casing 10, and the pole piece assembly 110 includes a first pole piece 1 and a second pole piece 2. Please continue to refer to FIG. The pole piece 1 includes a first current collector 11, the first current collector 11 includes an opposite first surface and a second surface, the first surface is provided with a first active material layer 12, and the second surface is provided with a second active material layer 15, The first active material layer 12 is provided with a first groove 14, the first surface includes a first uncoated area located in the first groove 14, the first tab 13 is arranged in the first groove 14, and is connected to the first uncoated area. The coating area is connected; the second active material layer 15 is provided with a second groove 16; and the heating assembly 30, please refer to FIG. The assembly 30 includes a heating part 3 , a first power connection part 31 and a second power connection part 32 , and the heating part 3 is accommodated in the casing 10 . The first connection part 31 is provided with a first connection area 311, and the heating part 3 is provided with a second connection area 312, and the first connection area 311 is connected to the second connection area 312; viewed along the thickness direction X of the pole piece assembly 110, the second The second groove 16 covers the first connection area 311 . By setting the first groove 14 and the second groove 16 on the active material layers on both sides of the first current collector 11, and then setting the first tab 13 in the first groove 14, the second groove 16 covers the first A first connection area 311 connecting the electric connection part 31 to the heating part 3, so that the protrusion of the first connection area 311 in the thickness direction is at least partially offset by the second groove 16, and finally the flatness of the pole piece assembly 110 is improved. Improve the electrochemical reaction interface of positive and negative electrodes.

Wherein, the housing 10 is the outer packaging of the electrochemical device, which plays the role of accommodating and protecting the pole piece assembly 110. It can be a soft shell, such as an aluminum-plastic film, or a hard shell, such as a steel shell or an aluminum shell. wait. The pole piece assembly 110 includes a first pole piece 1 and a second pole piece 2 , for example, the first pole piece 1 is a negative pole piece, and the second pole piece 2 is a positive pole piece.

The heating part 3 is a conversion device of electric energy and thermal energy, such as a resistance wire, and the electric connection part of the heating part 3 is used to receive electric current to form a heating circuit. Please continue to refer to FIG. 4 and FIG. 6. From the embodiment shown in FIG. 4, we can see that, viewed along the thickness direction X of the pole piece assembly 110, the second groove 16 covers the first connecting region 311, which is equivalent to the second The projection of the groove 16 along the thickness direction X of the pole piece assembly 110 can cover the first connection area 311 , that is, the position of the second groove 16 and the position of the first connection area 311 in the first electrical connection part 31 are at the center of the pole piece assembly 110 corresponding to the thickness direction. The second groove 16 may be adjacent to the first connection area 311 , or several layers of the first pole piece 1 , the diaphragm and the second pole piece 2 may be separated in the winding structure. It should be noted that the projections of the second groove 16 and the first groove 14 along the thickness direction of the pole piece assembly can cover one another, partially overlap or be separated from each other. The design of the above scheme can make the protrusion of the first connection area 311 of the first electrical connection part 31 in the thickness direction be at least partially offset by the second groove 16, and finally the flatness of the pole piece assembly 110 in the thickness direction is improved, improving The interface of positive and negative electrochemical reactions. In an actual application example, the first groove 14 and the first connection area 311 are arranged to overlap in the thickness direction of the pole piece assembly 110, which can also facilitate the connection of the first tab 13 and the first electrical connection part 31, thereby The heating part 3 is conveniently supplied with energy.

Optionally, please refer to FIG. 4 and FIG. 5, the second surface includes a second uncoated area located in the second groove 16, along the thickness direction of the first current collector 11, the first uncoated area and the second uncoated area Coated areas are opposite. At this time, the second active material layer on the back side of the first groove 14 is removed to form the second groove 16, because the second active material layer on the back side may be damaged when the first tab 13 is connected to the first uncoated region, Removing the second active material layer on the back of the first groove 14 can improve the consistency of the electrochemical reaction interface of the second active material layer, and at the same time use this space to reduce the impact caused by the protrusion of the first connection region 311 .

In some optional embodiments of this solution, please refer to FIG. 4 here, the second power connection part 32 is connected to the heating part 3; 23 separated from each other. Mutual separation means that along the thickness direction of the pole piece assembly 110, the projections of the second power connection part 32 and the second pole lug 23 do not overlap. The same side of the center plane of the thickness of the pole piece assembly 110 after winding may also be arranged on a different side of the center plane of the thickness of the pole piece assembly 110 after the winding with the second tab 23 . Through the separate arrangement of the second power connection part and the second pole ear, the second power connection part 32 and the second pole ear 23 can not interfere with each other in the thickness direction of the pole piece assembly 110, so that the second power connection The part 32 and the second tab 23 are not easy to cause overheating of the heating part 3 due to false contact, thereby causing thermal runaway of the electrochemical device.

In some embodiments of this solution, as shown in FIG. 4 , the second pole piece 2 can also be set in the same manner as the first pole piece 1, and the second pole piece 2 includes a second current collector 21, and the second current collector 21 includes an opposite The third surface and the fourth surface, the third surface is provided with a third active material layer 25, the fourth surface is provided with a fourth active material layer 22, the third active material layer 25 is provided with a third groove 24, the third surface Including the third uncoated area located in the third groove 24, the second tab 23 is arranged in the third groove 24 and connected with the third uncoated area; the fourth active material layer 22 is provided with a fourth groove 26 ; the second power connection portion 32 is provided with a third connection area 323 . Please continue to refer to FIG. 6, the heating part 3 is provided with a fourth connection area 324, and the third connection area 323 is connected to the fourth connection area 324; viewed along the thickness direction X of the pole piece assembly 110, the fourth groove 26 covers the third connection area. District 323. By setting the third groove 24 and the fourth groove 26 on the active material layers on both sides of the second current collector 21 respectively, and then disposing the second tab 23 in the third groove 24, the fourth groove 26 covers The third connection area 323, so that the protrusion of the third connection area designed in the thickness direction is at least partially offset by the fourth groove 26, which finally improves the flatness of the pole piece assembly and improves the electrochemical reaction interface of the positive and negative electrodes. .

Optionally, the fourth active material layer is provided with a fourth groove 26, the fourth surface includes a fourth uncoated area located in the fourth groove 26, along the thickness direction of the second current collector, the third uncoated area Opposite the fourth uncoated area. At this time, the fourth active material layer on the back side of the third groove 24 is removed to form a fourth groove 26. Since the second tab may damage the fourth active material layer on the back side when it is connected to the third uncoated region, the fourth active material layer on the back side is removed. The fourth active material layer on the back of the third groove 24 can use the space to reduce the influence caused by the protrusion of the third connection region 323 while improving the consistency of the electrochemical reaction interface of the fourth active material layer.

In some embodiments, the first tab 13 of the electrochemical device of this solution is connected to the first uncoated region by welding; the welding method can make the connection between the first tab 13 and the first uncoated region The connection between them is tighter, not easy to fall off, and prolongs the service life of the electrochemical device.

In some other embodiments, the surface of the first active material layer 12 is provided with a first insulating glue layer, and the first insulating glue layer covers the first groove 14; the first insulating glue layer covers the first groove 14, which can prevent the first The tab edge and welding burrs pierce the diaphragm to cause a short circuit, improving the safety of the electrochemical device.

In some other embodiments of this solution, the first tab 13 and the first power connection part 31 respectively extend out of the casing 10 and are connected outside the casing 10 .

In other embodiments of this solution, please refer to FIG. 5 and FIG. 6 , the first groove 14 is disposed between two ends of the first active material layer 12 in the length direction. Figure 6 shows the first pole piece 1 in the unfolded state, the horizontal direction is its length direction, the first tab 13 in Figure 6 is not arranged at both ends of the length direction, but is arranged in the middle of the length direction, When the pole piece assembly 110 is wound, by arranging the first groove 14 between the two ends in the length direction, the electron conduction paths of the active material layers on both sides of the first tab 13 can be reduced, and the performance of the electrochemical device can be improved. rate performance.

In other embodiments of this solution, a second insulating glue layer is provided on the surface of the second active material layer 15 , and the second insulating glue layer covers the second groove 16 . Cover the second groove 16 with an insulating adhesive layer. There may be burrs in the welding process in the second groove 16. On the one hand, the insulating adhesive layer can prevent the welding burrs from piercing the diaphragm and cause a short circuit, which plays a protective role. On the one hand, the second insulating adhesive layer can at least partially fill the second groove 16, improve the flatness of the pole piece assembly 110, and improve the interface of the positive and negative electrochemical reactions. When the first pole piece 1 is a negative pole piece, the second insulating adhesive layer can also inhibit the precipitation of lithium dendrites in the second groove 16 during charging, thereby improving the safety of the electrochemical device.

In some embodiments as shown in FIG. 7 , a schematic structural view of the heating assembly 30 is shown, and the heating part 3 can be a bent resistance wire. The embodiment in FIG. 6 shows the heating part 3 on the first current collector 11. position, the first current collector 11 is also provided with a fifth uncoated area 17, the fifth uncoated area 17 is an area not covered with the first active material layer 12; the heating part 3 is arranged on the fifth uncoated area 17 surface. It can be seen from FIG. 6 that the left end of the first pole piece 1 is provided with an empty foil area not covered with active material, that is, the fifth uncoated area 17 . Setting the heating part 3 on the empty foil area on the current collector can make full use of the space in the pole piece where the first current collector 11 is not coated with active material, thereby reducing the influence of the heating part 3 on the winding thickness of the pole piece assembly 110, At the same time, the heating part 3 can be better directly attached to the first collector 11 , and the heat can be directly and quickly transferred through the first collector 11 , thereby increasing the temperature rise rate of the pole piece assembly.

In some other embodiments of this solution, the pole piece assembly 110 is a winding structure, please refer to FIG. 6 and FIG. 8 here, and the fifth uncoated area 17 is located at the winding center of the winding structure. In some other embodiments, the heating part 3 can also be arranged in the empty foil area of the second pole piece 2, and the winding structure of the pole piece assembly 110 can be that the first pole piece 1, the diaphragm and the second pole piece 2 are sequentially stacked. Coil together. The figure shows the unfolded structure of the first pole piece 1 with an empty foil area. There is a certain gap in the winding center of the pole piece assembly 110. In this embodiment, the fifth uncoated area 17 is arranged on the coil. If the winding center part of the winding structure is used, the heating part 3 can be attached to the winding center part, or the heating part 3 can be directly inserted and arranged in the winding center of the pole piece assembly. By arranging the heating part 3 at the center of the winding, it can provide support for the pole piece of the inner layer during the thermocompression forming process, and prevent the active material layer from being peeled off due to excessive bending of the pole piece of the inner layer at the corner, thereby improving positive Negative electrode electrochemical reaction interface.

In some other embodiments, the heating part 3 includes a heating body and an insulating layer on the surface of the heating body. The insulating layer can isolate the heating body and the pole piece, and the material of the heating body is also a conductive material, so the heating body and the pole piece need to be insulated. By designing the insulating layer on the surface of the heating body, it is possible to prevent adverse consequences such as battery damage caused by short circuits between the heating body and pole pieces.

In some specific embodiments, the material of the heating body includes at least one of metal material or carbon material. Metal materials here include nickel, titanium, copper, silver, gold, platinum, iron, cobalt, chromium, tungsten, molybdenum, aluminum, magnesium, potassium, sodium, calcium, strontium, barium, silicon, germanium, tin, lead, indium At least one of , zinc or stainless steel; the carbon material described here includes at least one of carbon felt, carbon film, carbon black, acetylene black, fullerene, conductive graphite film or graphene film. In terms of specific material selection, it is only necessary that the material of the heating body be able to generate heat by electrification, and that a suitable dielectric and resistance value can be selected.

In some other specific embodiments, the material of the insulating layer includes at least one of polymers or inorganic insulating materials. Polymers here include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyimide, polyamide, polyethylene glycol , polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate , polypropylene carbonate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-co-chlorotrifluoroethylene), silicone, vinylon, polypropylene, anhydride modified polypropylene, polypropylene Ethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester, poly At least one of sulfone, amorphous α-olefin copolymer, and derivatives of the above substances. The inorganic insulating material here may also include hafnium dioxide, strontium titanate, tin oxide, cerium oxide, magnesium oxide, nickel oxide, calcium oxide, barium oxide, zinc oxide, zirconium dioxide, yttrium trioxide, aluminum oxide, titanium dioxide , silicon dioxide, boehmite, magnesium hydroxide or aluminum hydroxide at least one. The insulating layer is designed as a polymer or an inorganic insulating material, which can achieve the insulating effect. This embodiment does not limit this.

Finally, it should be noted that although the above-mentioned embodiments have been described in the specification text and drawings of the present application, the scope of protection of the patent of the present application cannot be limited thereby. Any technical solution based on the substantive concept of this application, using the equivalent structure or equivalent process replacement or modification of the content recorded in the text and drawings of this application, and directly or indirectly implementing the technical solutions of the above embodiments in Other relevant technical fields, etc., are all included in the patent protection scope of this application.

Claims

An electrochemical device, characterized in that, comprising:

case;

The first tab and the second tab;

A pole piece assembly, the pole piece assembly is accommodated in the housing, the pole piece assembly includes a first pole piece and a second pole piece, the first pole piece includes a first current collector, and the first current collector Including opposite first surface and second surface, the first surface is provided with a first active material layer, the second surface is provided with a second active material layer, and the first active material layer is provided with a first groove , the first surface includes a first uncoated area located in the first groove, the first tab is disposed in the first groove and connected to the first uncoated area; The first active material layer or the second active material layer is provided with a second groove; and

A heating assembly, the heating assembly includes a heating part, a first power connection part and a second power connection part, the heating part is accommodated in the housing, the first power connection part is provided with a first connection area, the The heating part is provided with a second connection area, the first connection area is connected to the second connection area; viewed along the thickness direction of the pole piece assembly, the second groove covers the first connection area.
The electrochemical device according to claim 1, wherein the second active material layer is provided with the second groove, and the second surface includes a second uncoated layer located in the second groove. region, along the thickness direction of the first current collector, the first uncoated region is opposite to the second uncoated region.
The electrochemical device according to claim 1, wherein the second pole piece comprises a second current collector, the second current collector comprises a third surface and a fourth surface opposite to each other, and the third surface is provided with a There is a third active material layer, the fourth surface is provided with a fourth active material layer, the third active material layer is provided with a third groove, and the third surface includes a third groove located in the third groove. In the uncoated area, the second tab is arranged in the third groove and connected to the third uncoated area; the third active material layer or the fourth active material layer is provided with a first four grooves;

The second power connection part is provided with a third connection area, the heating part is provided with a fourth connection area, and the third connection area is connected to the fourth connection area; viewed along the thickness direction of the pole piece assembly , the fourth groove covers the third connecting region.
The electrochemical device according to claim 1, wherein the electrochemical device satisfies at least one of the following characteristics:

(1) The first tab is connected to the first uncoated area by welding;

(2) A first insulating adhesive layer is provided on the surface of the first active material layer, and the first insulating adhesive layer covers the first groove;

(3) The first tab and the first power connection part respectively extend out of the housing and are connected outside the housing;

(4) The first groove is provided between both ends in the length direction of the first active material layer.
The electrochemical device according to claim 2, wherein a second insulating adhesive layer is provided on the surface of the second active material layer, and the second insulating adhesive layer covers the second groove.
The electrochemical device according to claim 1, wherein the first current collector is further provided with a fifth uncoated area, and the fifth uncoated area is not covered with the first active material layer or The region of the second active material layer; the heating part is disposed on the surface of the fifth uncoated region.
The electrochemical device according to claim 6, wherein the pole piece assembly is a wound structure, and the fifth uncoated region is located at a winding center of the wound structure.
The electrochemical device according to claim 1, wherein the heating part comprises a heating body and an insulating layer on a surface of the heating body.
The electrochemical device according to claim 8, wherein the electrochemical device satisfies at least one of the following characteristics:

(a) The material of the heating body includes at least one of metal material or carbon material;

(b) The material of the insulating layer includes at least one of a polymer or an inorganic insulating material.
An electric device, characterized in that the electric device comprises the electrochemical device according to any one of claims 1-9.