Electrochemical device and electric device

Abstract

An electrochemical device and an electric device, the electrochemical device comprising: a pole piece assembly and a heating assembly; the pole piece assembly comprising a first pole piece, the first pole piece comprising a first current collector, a first surface of the first current collector being provided with a first active material layer, a second surface of the first current collector being provided with a second active material layer, the first active material layer or the second active material layer being provided with a second groove; the heating assembly comprising a heating part and a first power connection part, the first power connection part being provided with a first connection area, the heating part being provided with a second connection area, the first connection area being connected with the second connection area; in the thickness direction of the pole piece assembly, the second groove covers the first connection area. The first connection area connecting the first power connection part with the heating part is at least partially offset in the thickness direction by the second groove, finally improving the flatness of the electrochemical device and improving the electrochemical reaction interface of the positive and negative poles.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of batteries, in particular to an electrochemical device and a power utilization device. BACKGROUND

[0002] Lithium ion batteries are widely used in daily life, providing great convenience and richness to people's life. However, under low temperature conditions, the polarization during the charging and discharging process of lithium ion batteries is intensified, which reduces the service life of the battery. At the same time, in recent years, the application of high power has put forward challenges to the rate performance of lithium ion batteries, especially under low temperature conditions. The existing methods to improve the low temperature performance of lithium ion batteries include heating the battery to room temperature to avoid the use of the battery in low temperature scenarios. This method does not need to change the chemical system, can improve the dynamics of the battery, can widen the temperature range of the lithium ion battery, and can realize the use of the lithium ion battery in low temperature environment, and can maintain the same charging and discharging rate as room temperature. Therefore, the improvement of the low temperature performance of lithium ion batteries by heating to improve the dynamics of the system has attracted widespread attention.

[0003] In the current research on the heating scheme of the battery, external heating method and internal heating method are commonly used. Overall, the external heating method has low heating efficiency and corrosion risk. Compared with external heating, internal heating method is to place a heating sheet inside the battery to heat the battery. This method can significantly improve the heating rate compared with external heating, but the existing structure scheme for realizing internal heating will cause the problem of uneven thickness inside the battery, thereby reducing the consistency of the positive and negative electrochemical reaction interfaces, increasing the risk of lithium precipitation, and reducing the cycle performance of the lithium ion battery. SUMMARY

[0004] In view of the above problems, the present application provides an electrochemical device with high flatness and improved electrochemical reaction interface.

[0005] To achieve the above-mentioned purpose, the present application provides an electrochemical device, comprising:

[0006] a shell;

[0007] a first tab and a second tab;

[0008] The pole piece assembly is accommodated in the shell, and 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, and 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 area located in the first groove. The first tab is arranged in the first groove and connected with the first uncoated area. The first active material layer or the second active material layer is provided with a second groove. 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 shell. The first power connection part is provided with a first connecting area, and the heating part is provided with a second connecting area. The first connecting area is connected with the second connecting area. In the thickness direction of the pole piece assembly, the second groove covers the first connecting area.

[0009] The electrochemical device provided in the above scheme can improve the flatness of the electrochemical device and improve the electrochemical reaction interface of the positive and negative electrodes by arranging the first groove and the second groove on the active material layers on the two surfaces of the first current collector, arranging the first tab in the first groove, and covering the first connecting area where the first power connection part of the heating assembly is connected with the heating part by the second groove.

[0010] Optionally, the second active material layer is provided with a second groove, and the second surface includes a second uncoated area located in the second groove. In the thickness direction of the first current collector, the first uncoated area is opposite to the second uncoated area. At this time, the second active material layer on the back of the first groove is removed to form the second groove. Since the first tab may damage the second active material layer on the back when it is connected with the first uncoated area, removing the second active material layer on the back of the first groove can improve the consistency of the electrochemical reaction interface of the second active material layer while reducing the impact of the protrusion of the first connecting area.

[0011] Optionally, the second power connection part is connected with the heating part, and in the thickness direction of the pole piece assembly, the second power connection part and the second tab are separated from each other. Separated from each other means that in the thickness direction of the pole piece assembly, the projection of the second power connection part and the projection of the second tab do not overlap. By arranging the second power connection part and the second tab to be separated from each other, the second power connection part and the second tab can 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 the heating assembly to be overheated due to miscontacting, and thus the thermal runaway of the electrochemical device is caused.

[0012] Optionally, the second pole piece comprises a second current collector, the second current collector comprises opposite third and fourth surfaces, the third surface is provided with 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, the third surface comprises a third uncoated area at the third groove, and the second tab is arranged in the third groove and connected with the third uncoated area; the third active material layer or the fourth active material layer is provided with a fourth groove; the second electrical connection part is provided with a third connecting area, and the heating part is provided with a fourth connecting area, the third connecting area is connected with the fourth connecting area; in the thickness direction of the pole piece assembly, the fourth groove covers the third connecting area. By arranging the third groove and the fourth groove on the active material layers on the two surfaces of the second current collector respectively, and arranging the second tab in the third groove, the fourth groove covers the third connecting area where the second electrical connection part and the heating part of the heating assembly are connected, so that the protrusion of the third connecting area designed to connect the second electrical connection part and the heating part in the thickness direction is at least partially offset by the fourth groove, and finally the flatness of the electrochemical device is improved, and the electrochemical reaction interface of the positive and negative electrodes is improved.

[0013] Optionally, the fourth active material layer is provided with a fourth groove, the fourth surface comprises a fourth uncoated area at the fourth groove, and the third uncoated area and the fourth uncoated area are opposite in the thickness direction of the second current collector. At this time, the fourth active material layer on the back of the third groove is removed to form the fourth groove. Since the second tab may damage the fourth active material layer on the back when connected with the third uncoated area, removing the fourth active material layer on the back of the third groove can improve the consistency of the electrochemical reaction interface of the fourth active material layer while reducing the impact of the protrusion of the third connecting area.

[0014] Optionally, the first tab and the first uncoated area are connected by welding. By welding, the connection between the first tab and the first uncoated area is more secure and less likely to fall off, prolonging the service life of the electrochemical device.

[0015] 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 arranging the first insulating adhesive layer, the burr at the edge of the first tab and the welding position between the first tab and the first current collector can be prevented from piercing the separator and causing short circuit, thereby improving the safety of the electrochemical device.

[0016] Optionally, the first tab and the first electrical connection part extend out of the shell and are connected outside the shell.

[0017] Optionally, the first groove is arranged between the two ends in the length direction of the first active material layer. By arranging the first groove between the two ends in the length direction, the electronic conduction path of the active material layer on both sides of the first tab can be reduced to improve the rate performance of the electrochemical device.

[0018] Optionally, the surface of the second active material layer is provided with a second insulating adhesive layer, and the second insulating adhesive layer covers the second groove. Covering the insulating adhesive layer on the second groove can prevent the welding burr from piercing the diaphragm to cause short circuit, thereby playing a protective role. In addition, the second groove can be at least partially filled, thereby improving the flatness of the electrochemical device and improving the interface of the positive and negative electrochemical reactions.

[0019] Optionally, the first current collector is further provided with a fifth non-coated area, and the fifth non-coated area is an area not covered by the first active material layer or the second active material layer; and the heating part is arranged on the surface of the fifth non-coated area. Arranging the heating part on the non-coated area of the current collector can make full use of the space of the first current collector not coated with the active material in the pole piece, thereby reducing the influence of the heating part on the thickness of the electrochemical device.

[0020] Optionally, the pole piece assembly is in a wound structure, and the fifth non-coated area is located at the winding center part of the wound structure. When the pole piece assembly is in a wound structure, there is a certain gap at the winding center due to the stiffness of the inner layer pole piece. Arranging the fifth non-coated area at the winding center part of the wound structure can allow the heating part to be arranged at the winding center part, thereby making full use of the gap and reducing the influence of the heating part on the winding thickness of the pole piece assembly. At the same time, arranging the heating part at the winding center part can provide support for the inner layer pole piece during the hot-pressing formation process, thereby inhibiting the active material layer from peeling off at the corner due to excessive bending of the inner layer pole piece, and further improving the interface of the positive and negative electrochemical reactions.

[0021] Optionally, the heating part comprises a heating body and an insulating layer arranged on the surface of the heating body. Arranging the insulating layer on the surface of the heating body can prevent the heating body from being short-circuited with other components such as the pole piece, thereby preventing the battery from being damaged and other adverse consequences.

[0022] Optionally, the material of the heating body comprises at least one of a metal material or a carbon material. The material of the heating body can generate heat by electrification, and a suitable dielectric and resistance value can be selected.

[0023] Optionally, the material of the insulating layer comprises at least one of a polymer or an inorganic insulating material. The insulating layer designed as a polymer or an inorganic insulating material can achieve the effect of insulation.

[0024] The application also provides a power utilization device comprising the electrochemical device as described in any of the above technical solutions.

[0025] The application can at least partially offset the protrusion of the first connecting area connecting the first power connection part and the heating part in the thickness direction by the second groove, thereby improving the flatness of the electrochemical device and improving the interface of the positive and negative electrochemical reactions. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings are only used to illustrate the principles, implementation manners, applications, characteristics and effects of specific embodiments of the present application and cannot be considered as limitations to the present application.

[0027] In the drawings:

[0028] Figure 1 A schematic diagram of an electric device according to an embodiment of the present application;

[0029] Figure 2 A schematic diagram of a non-flat pole piece assembly structure according to a comparative example of the present application;

[0030] Figure 3 A schematic diagram of an electrochemical device structure according to an embodiment of the present application;

[0031] Figure 4 A schematic diagram of a pole piece assembly according to an embodiment of the present application;

[0032] Figure 5 A schematic diagram of a first pole piece in an unfolded state according to an embodiment of the present application;

[0033] Figure 6 A schematic diagram of a heating assembly and a first pole piece in an unfolded state according to an embodiment of the present application;

[0034] Figure 7 A schematic diagram of a heating assembly according to an embodiment of the present application;

[0035] Figure 8 A schematic diagram of a fifth uncoated area of a first pole piece according to an embodiment of the present application.

[0036] The reference signs involved in the above-mentioned drawings are explained as follows:

[0037] 100, electric device,

[0038] 10, housing,

[0039] 110, pole piece assembly

[0040] 1, first pole piece,

[0041] 11, first current collector,

[0042] 12, first active material layer,

[0043] 13, first tab,

[0044] 14, first groove,

[0045] 15, second active material layer,

[0046] 16, second groove,

[0047] 17, fifth uncoated area,

[0048] 2、the second tab,

[0049] 21、the second current collector,

[0050] 22、the fourth active material layer,

[0051] 23、the second tab,

[0052] 24、the third groove,

[0053] 25、the third active material layer,

[0054] 26、the fourth groove,

[0055] 30、the heating assembly,

[0056] 3、the heating portion,

[0057] 31、the first power connection portion,

[0058] 311、the first connection region,

[0059] 312、the second connection region,

[0060] 32、the second power connection portion,

[0061] 323、the third connection region,

[0062] 324、the fourth connection region. DETAILED DESCRIPTION

[0063] To explain possible application scenarios, technical principles, specific implementable schemes, achievable purposes and effects of the present application in detail, the following will be described in detail in combination with specific embodiments listed and with the aid of the accompanying drawings. The embodiments described herein are only used to more clearly explain the technical schemes of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0064] In this article, the mention of "embodiments" means that the specific features, structures or characteristics described in combination with the embodiments can be included in at least one embodiment of the present application. In principle, in the present 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 scheme.

[0065] 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 present application belongs; the use of related terms in this article is only for the purpose of describing specific embodiments, and is not intended to limit the present application.

[0066] In the present application, terms such as "first" and "second" are merely used to distinguish one entity or operation from another, and do not necessarily require or imply any actual quantity, primary or secondary, or order relationship between the entities or operations.

[0067] In the description of the embodiments of the present application, the spatial-related expressions such as "center", "longitudinal", "transverse", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are indicated by the orientation or position relationship shown in the specific embodiments or the drawings, and are only for the convenience of describing the specific embodiments of the present application or for the reader to understand, and do not indicate or imply that the indicated device or component must have a specific position, a specific orientation, or be constructed or operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0068] Unless otherwise explicitly specified or limited, in the description of the embodiments of the present application, the terms "mount", "connect", "connect", "fix", "set", etc. should be broadly understood. For example, the "connection" can be a fixed connection, or a detachable connection, or an integral setting; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art to which the present application belongs, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0069] Please refer to Figure 1 A power consuming device 100 is provided in the embodiments, the power consuming device 100 of the present application includes any device that can use an electrochemical device as a power source, including various consumer electronic products such as mobile phones, cameras, notebook computers, wearable devices, etc.; also including electric bicycles, electric vehicles, airplanes, motor trains, ships and other transportation tools, and also including electrical equipment that uses batteries on devices, buildings and other facilities. Figure 1 The power consuming device 100 in the illustrated embodiment can be a mobile phone, and the battery is arranged in the mobile phone.

[0070] The internal heating method is to place a heating sheet inside the battery to heat the battery. The present inventors have found that when a heating sheet is added inside the battery, the protrusions of the heating electrode connection part with the heating sheet will cause the thickness of the electrode assembly inside the battery to be uneven. In the subsequent hot-pressing formation process, the protruding part will be over-pressed, thereby reducing the consistency of the positive and negative electrochemical reaction interfaces. For example, as shown in Figure 2In the comparative example shown, the heating part 3 is arranged inside the pole piece assembly 110. The first current collecting part 31 is connected to the surface of the heating part 3 to form a protrusion. During the hot-pressing process, the protrusion will extrude outwardly to occupy the position originally belonging to the positive or negative pole piece, and the extrusion is transmitted layer by layer outwardly, finally resulting in the protrusion and unevenness of the outermost part of the pole piece assembly 110, and causing overpressure at the protrusion, which reduces the consistency of the positive and negative electrochemical reaction interfaces. The inventors of the present application found the above problems and invented the following electrochemical device for improvement.

[0071] Please refer to Figure 3 and Figure 4 The structure of the electrochemical device is shown in Figure 3 , which includes a shell 10. The electrochemical device further includes a first tab 13 and a second tab 23, which protrude out of the shell 10 to provide external electrical connection. The electrochemical device further includes a first current collecting part 31 and a second current collecting part 32, which protrude out of the shell 10 to connect the heating circuit for heating. In the thickness direction X of the pole piece assembly 110, i.e. the direction perpendicular to the paper, the first tab 13 covers the first current collecting part 31. In some embodiments, the first tab 13 and the first current collecting part 31 are connected outside the shell 10.

[0072] The pole piece assembly 110 is accommodated in the shell 10, and the pole piece assembly 110 includes a first pole piece 1 and a second pole piece 2. Please continue to refer to Figure 4 , which is a cross-sectional view along the XY plane of the first pole piece 1. The first pole piece 1 includes a first current collector 11, which includes opposite first and second surfaces. 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 recess 14, and the first surface includes a first non-coated area located in the first recess 14. The first tab 13 is arranged in the first recess 14 and connected to the first non-coated area. The second active material layer 15 is provided with a second recess 16. Please also refer to Figure 6This is a schematic diagram of the heating assembly 30 and the first electrode 1 in their unfolded state. The heating assembly 30 includes a heating part 3, a first contact part 31, and a second contact part 32, with the heating part 3 housed in the housing 10. The first contact part 31 has a first connection area 311, and the heating part 3 has a second connection area 312, which are connected. Viewed along the thickness direction X of the electrode assembly 110, 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 placing the first electrode tab 13 in the first groove 14, the second groove 16 covers the first connection area 311 where the first contact part 31 and the heating part 3 are connected, thereby at least partially offsetting the protrusion of the first connection area 311 in the thickness direction by the second groove 16. Ultimately, this improves the flatness of the electrode assembly 110 and the electrochemical reaction interface between the positive and negative electrodes.

[0073] The housing 10 serves as the outer packaging of the electrochemical device, containing and protecting the electrode assembly 110. It can be a soft housing, such as an aluminum-plastic film, or a rigid housing, such as a steel or aluminum housing. The electrode assembly 110 includes a first electrode 1 and a second electrode 2, such as the first electrode 1 being the negative electrode and the second electrode 2 being the positive electrode.

[0074] Heating unit 3 is a device for converting electrical energy into thermal energy, such as a resistance wire. The energizing part of heating unit 3 is used to connect current to form a heating circuit. Please continue to refer to [reference needed]. Figure 4 and Figure 6 ,from Figure 4 In the illustrated embodiment, when viewed along the thickness direction X of the electrode assembly 110, the second groove 16 covers the first connection area 311. This means the projection of the second groove 16 along the thickness direction X of the electrode assembly 110 covers the first connection area 311. In other words, the position of the second groove 16 corresponds to the position of the first connection area 311 in the first contact portion 31 along the thickness direction of the electrode assembly 110. The second groove 16 can be adjacent to the first connection area 311, or it can be spaced several layers of the first electrode 1, the separator, and the second electrode 2 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 electrode assembly can overlap, partially overlap, or be separate. This design allows the protrusion of the first connection area 311 in the thickness direction of the first contact portion 31 to be at least partially offset by the second groove 16, ultimately improving the flatness of the electrode assembly 110 along the thickness direction and enhancing the interface between the positive and negative electrodes in the electrochemical reaction. In practical applications, the first groove 14 and the first connection area 311 are arranged to overlap in the thickness direction of the electrode assembly 110, which also makes it easy to connect the first electrode tab 13 to the first power connection part 31, thereby facilitating the power supply to the heating part 3.

[0075] Alternatively, please refer toFigure 4 and Figure 5 The second surface includes a second uncoated area at the second groove 16, and the first uncoated area is opposite to the second uncoated area along the thickness direction of the first current collector 11. At this time, the second active material layer on the back of the first groove 14 is removed to form the second groove 16. Since the first tab 13 may damage the second active material layer on the back when connected to the first uncoated area, 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 while using the space to reduce the impact of the protrusion of the first connecting area 311.

[0076] In some optional embodiments of the present solution, please refer to Figure 4 The second current collecting part 32 is connected to the heating part 3, and the second current collecting part 32 and the second tab 23 are separated from each other along the thickness direction of the tab assembly. Separated from each other means that the projections of the second current collecting part 32 and the second tab 23 do not overlap along the thickness direction of the tab assembly 110. The second current collecting part 32 can be arranged on the same side of the thickness center plane of the tab assembly 110 after winding as the second tab 23, or can be arranged on different sides of the thickness center plane of the tab assembly 110 after winding as the second tab 23. By arranging the second current collecting part and the second tab separately, the second current collecting part 32 and the second tab 23 do not interfere with each other along the thickness direction of the tab assembly 110, so that the second current collecting part 32 and the second tab 23 are not easy to cause the heating part 3 to overheat due to miscontacting, thereby causing thermal runaway of the electrochemical device.

[0077] In some embodiments of the present solution, as shown in Figure 4 The second tab 2 can also be arranged in the same manner as the first tab 1. The second tab 2 includes a second current collector 21, and the second current collector 21 includes opposite third and fourth surfaces. The third surface is provided with a third active material layer 25, and 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, and the third surface includes a third uncoated area at the third groove 24. The second tab 23 is arranged at the third groove 24 and connected to the third uncoated area. The fourth active material layer 22 is provided with a fourth groove 26, and the second current collecting part 32 is provided with a third connecting area 323. Please continue to refer to Figure 6The heating part 3 is provided with a fourth connecting area 324, and the third connecting area 323 is connected with the fourth connecting area 324. In the thickness direction X of the pole piece assembly 110, the fourth recess 26 covers the third connecting area 323. By arranging the third recess 24 and the fourth recess 26 on the active material layers on the two sides of the second current collector 21 respectively, and arranging the second tab 23 in the third recess 24, and covering the third connecting area 323 with the fourth recess 26, the protrusion of the designed third connecting area in the thickness direction is at least partially offset by the fourth recess 26, so that the flatness of the pole piece assembly is improved, and the electrochemical reaction interface of the positive and negative poles is improved.

[0078] Optionally, the fourth active material layer is provided with a fourth recess 26, and the fourth surface includes a fourth uncoated area in the fourth recess 26. In the thickness direction of the second current collector, the third uncoated area is opposite to the fourth uncoated area. At this time, the fourth active material layer on the back of the third recess 24 is removed to form the fourth recess 26. Since the second tab may damage the fourth active material layer on the back when connected with the third uncoated area, removing the fourth active material layer on the back of the third recess 24 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 impact of the protrusion of the third connecting area 323.

[0079] In some embodiments, the first tab 13 of the electrochemical device is connected with the first uncoated area by welding. The welding can make the connection between the first tab 13 and the first uncoated area more secure, and is not easy to fall off, thereby prolonging the service life of the electrochemical device.

[0080] In other embodiments, the surface of the first active material layer 12 is provided with a first insulating adhesive layer, and the first insulating adhesive layer covers the first recess 14. The first insulating adhesive layer covering the first recess 14 can prevent the first tab edge and the welding burr from piercing the separator to cause short circuit, thereby improving the safety of the electrochemical device.

[0081] In other embodiments of the present scheme, the first tab 13 and the first current collecting part 31 extend out of the shell 10 and are connected outside the shell 10.

[0082] In other embodiments of the present scheme, please refer to Figure 5 and Figure 6 The first recess 14 is arranged between the two ends of the length direction of the first active material layer 12. Figure 6 The first pole piece 1 in the unfolded state is shown in Figure 6The first tab 13 in the first electrode tab 1 is not arranged at the two ends of the length direction, but arranged at the middle of the length direction. When the electrode tab assembly 110 is wound, by arranging the first groove 14 between the two ends of the length direction, the electronic conduction path of the active material layer on both sides of the first tab 13 can be reduced, and the rate performance of the electrochemical device can be improved.

[0083] In some other embodiments of the present scheme, the surface of the second active material layer 15 is provided with a second insulating adhesive layer, and the second insulating adhesive layer covers the second groove 16. By covering the insulating adhesive layer on the second groove 16, burrs that may exist in the second groove 16 during the welding process can be prevented from piercing the diaphragm and causing short circuit, thereby playing a protective role. On the other hand, the second insulating adhesive layer can at least partially fill the second groove 16, improve the flatness of the electrode tab assembly 110, and improve the interface of the positive and negative electrochemical reactions. When the first electrode tab 1 is a negative electrode tab, the second insulating adhesive layer can also inhibit the precipitation of lithium dendrites at the second groove 16 during the charging process, thereby improving the safety of the electrochemical device.

[0084] In some embodiments as shown in Figure 7 , a structural schematic diagram of the heating assembly 30 is shown. The heating part 3 can be a bent resistance wire, Figure 6 Embodiments of the present scheme show the position of the heating part 3 on the first current collector 11. The first current collector 11 is also provided with a fifth uncoated area 17, which is an area not covered by the first active material layer 12; and the heating part 3 is arranged on the surface of the fifth uncoated area 17. From Figure 6 , it can be seen that the left end of the first electrode tab 1 is provided with an uncoated active material foil area, i.e., the fifth uncoated area 17. By arranging the heating part 3 on the uncoated foil area of the current collector, the space of the first current collector 11 not coated with active material in the electrode tab can be fully utilized, thereby reducing the impact of the heating part 3 on the winding thickness of the electrode tab assembly 110. At the same time, the heating part 3 can be better directly attached to the first current collector 11, and the heat can be quickly transferred through the first current collector 11, thereby improving the heating rate of the electrode tab assembly.

[0085] In some other embodiments of the present scheme, the electrode tab assembly 110 is in a wound structure. Please refer to Figure 6 and Figure 8The fifth uncoated region 17 is located at the winding center of the winding structure. In some other embodiments, the heating part 3 can also be arranged at the empty foil region of the second pole piece 2. The winding structure of the pole piece assembly 110 can be wound by stacking the first pole piece 1, the separator and the second pole piece 2 in sequence. The structure of the first pole piece 1 with the empty foil region is shown in the figure. There is a certain gap at the winding center of the pole piece assembly 110. In this embodiment, the fifth uncoated region 17 is arranged at the winding center of the winding structure, so that the heating part 3 can be arranged at the winding center or directly inserted into the winding center of the pole piece assembly. By arranging the heating part 3 at the winding center, the inner pole piece can be supported during the hot-pressing formation process, so as to prevent the active material layer from peeling off due to excessive bending at the corner of the inner pole piece, and thus improve the positive and negative electrode electrochemical reaction interface.

[0086] In some other embodiments, the heating part 3 comprises a heating body and an insulating layer arranged on the surface of the heating body. The insulating layer can isolate the heating body and the pole piece. The material of the heating body is also a conductive material, so that the heating body and the pole piece need to be insulated. By designing the insulating layer on the surface of the heating body, the short circuit between the heating body and the pole piece and other components can be prevented, so as to avoid the damage of the battery and other adverse consequences.

[0087] In some specific embodiments, the material of the heating body comprises at least one of a metal material or a carbon material. The metal material herein comprises at least one of nickel, titanium, copper, silver, gold, platinum, iron, cobalt, chromium, tungsten, molybdenum, aluminum, magnesium, potassium, sodium, calcium, strontium, barium, silicon, germanium, tin, lead, indium, zinc or stainless steel; and the carbon material herein comprises at least one of carbon felt, carbon film, carbon black, acetylene black, fullerene, conductive graphite film or graphene film. In the selection of specific materials, only the material of the heating body can generate heat by electrification, and the appropriate dielectric and resistance value can be selected.

[0088] In some other embodiments, the insulating layer comprises at least one of a polymer or an inorganic insulating material. The polymer can include at least one of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyimide, polyamide, polyethylene glycol, polyamide-imide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, poly methylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-co-chlorotrifluoroethylene), silicone, vinylon, polypropylene, anhydride-modified polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester, polysulfone, amorphous α-olefin copolymer, and derivatives thereof. The inorganic insulating material can further include at least one of hafnium dioxide, strontium titanate, tin oxide, cerium oxide, magnesium oxide, nickel oxide, calcium oxide, barium oxide, zinc oxide, zirconium dioxide, yttrium oxide, aluminum oxide, titanium dioxide, silicon dioxide, boehmite, magnesium hydroxide, or aluminum hydroxide. The insulating layer can be designed to achieve the insulating effect by using either a polymer or an inorganic insulating material. The embodiments are not limited in this regard.

[0089] Finally, it should be noted that the above-described embodiments are described in the specification and drawings of the present application for illustrative purposes, and the patent protection scope of the present application should not be limited thereto. Any technical solutions obtained by replacing or modifying the equivalent structures or equivalent processes based on the essential concept of the present application, using the content described in the specification and drawings of the present application, and directly or indirectly applying the technical solutions of the above embodiments to other related technical fields, are included in the patent protection scope of the present application.

Claims

1. An electrochemical device, characterized by, The electrochemical device comprises: a shell; a first tab and a second tab; a tab assembly accommodated in the shell, the tab assembly comprising a first tab and a second tab, the first tab comprising a first current collector, the first current collector comprising opposite first and second surfaces, the first surface being provided with a first active material layer, the second surface being provided with a second active material layer, the first active material layer being provided with a first groove, the first surface comprising a first uncoated area at the first groove, the first tab being provided in the first groove and connected with the first uncoated area; the second active material layer being provided with a second groove, and a heating assembly comprising a heating part, a first power connection part and a second power connection part, the heating part being accommodated in the shell, the first power connection part being provided with a first connection area, the heating part being provided with a second connection area, the first connection area being connected with the second connection area; as viewed in the thickness direction of the tab assembly, the second groove covers the first connection area; the second surface comprising a second uncoated area at the second groove, the first uncoated area and the second uncoated area being opposite in the thickness direction of the first current collector; the first current collector further comprising a fifth uncoated area, the fifth uncoated area being an area not covered by the first active material layer; the heating part being provided on the surface of the fifth uncoated area; the tab assembly being in a wound structure, and the fifth uncoated area being located at the winding center of the wound structure.

2. The electrochemical device of claim 1, wherein the second tab comprising a second current collector, the second current collector comprising opposite third and fourth surfaces, the third surface being provided with a third active material layer, the fourth surface being provided with a fourth active material layer, the third active material layer being provided with a third groove, the third surface comprising a third uncoated area at the third groove, the second tab being provided in the third groove and connected with the third uncoated area; the third active material layer or the fourth active material layer being provided with a fourth groove; the second power connection part being provided with a third connection area, the heating part being provided with a fourth connection area, the third connection area being connected with the fourth connection area; as viewed in the thickness direction of the tab assembly, the fourth groove covers the third connection area.

3. The electrochemical device of claim 1, wherein The electrochemical device satisfies at least one of the following characteristics: (1) the first tab and the first uncoated area are connected by welding; (2) the surface of the first active material layer is provided with a first insulating adhesive layer, the first insulating adhesive layer covering the first groove; (3) the first tab and the first power connection part extend out of the shell respectively and are connected outside the shell; (4) the first groove is provided between the two ends of the length direction of the first active material layer.

4. The electrochemical device of claim 1, wherein The surface of the second active material layer is provided with a second insulating adhesive layer, the second insulating adhesive layer covering the second groove.

5. The electrochemical device of claim 1, wherein The heating part comprises a heating body and an insulating layer on the surface of the heating body.

6. The electrochemical device of claim 5, wherein, The electrochemical device satisfies at least one of the following characteristics: (a) the material of the heating body comprises at least one of a metal material or a carbon material; (b) the material of the insulating layer comprises at least one of a polymeric or inorganic insulating material.

7. An electrical device, characterized by The power consuming device comprises an electrochemical device as claimed in any of claims 1-6.

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