Electrode assembly, electrochemical apparatus and electric device

Abstract

Provided in the present application are an electrode assembly, an electrochemical apparatus and an electric device. The electrode assembly comprises a first electrode sheet and a second electrode sheet having opposite polarities, wherein a first active material layer and a second active material layer of the first electrode sheet are respectively arranged on a first surface and a second surface of a first current collector that are opposite each other; the first active material layer is provided with a first groove and a second groove penetrating through a bottom wall of the first groove to the first surface; a first surface of a first single-sided bare foil area of the first current collector is exposed in the second groove, and a second surface thereof is covered by the second active material layer, such that the volume of the second active material layer is larger; a first tab is accommodated in the second groove and is welded to the first single-sided bare foil area to form a welded joint; and a first insulating adhesive layer is accommodated in the first groove and covers the welded joint, and the projection of the first insulating adhesive layer in the direction of thickness of the first current collector is located in the first groove, such that the overall thickness of the electrode assembly is smaller, making the energy density of the electrochemical apparatus higher.

Description

Electrode assembly, electrochemical device and electrical equipment CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Chinese patent application CN202311843081.7 entitled “Electrode Assembly, Electrochemical Device and Electrical Equipment” filed on December 28, 2023, the entire contents of which are incorporated herein by reference. Technical Field

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

[0003] With the rapid development of electronic information technology, various electronic devices are also developing towards intelligence and multi-functions, and the requirements for battery energy density are becoming higher and higher.

[0004] Currently, electrochemical devices include two electrode sheets, each typically consisting of a current collector, two active material layers, and tabs. A groove is provided on the surface of one of the active material layers of each electrode sheet where it connects to the tab. The two active material layers of each electrode sheet are each provided with two insulating adhesive layers corresponding to the tab of that electrode sheet and two insulating adhesive layers corresponding to the tab of the other electrode sheet. Therefore, after the two electrode sheets are wound together, each tab of one electrode sheet has four insulating adhesive layers, resulting in a thicker electrode assembly and a lower energy density for the electrochemical device. Summary of the Invention

[0005] The present application provides an electrode assembly, an electrochemical device, and electrical equipment, which can effectively improve the energy density of the electrochemical device.

[0006] In a first aspect, the present application provides an electrode assembly, comprising a first electrode piece and a second electrode piece with opposite polarities, the first electrode piece comprising: a first current collector having a first surface and a second surface arranged opposite to each other; a first active material layer arranged on the first surface, the first active material layer being provided with a first groove and a second groove extending from the bottom wall of the first groove to the first surface, the first current collector comprising a first single-sided empty foil area, the first surface of the first single-sided empty foil area being exposed to the second groove; a second active material layer arranged on the second surface, the second surface of the first single-sided empty foil area being covered by the second active material layer; a first electrode tab being accommodated in the second groove and welded to the first single-sided empty foil area to form a weld; and a first insulating adhesive layer being accommodated in the first groove and covering the weld between the first electrode tab and the first single-sided empty foil area, the projection of the first insulating adhesive layer along the thickness direction of the first current collector being located within the first groove.

[0007] In the above technical solution, the electrode assembly includes a first electrode piece and a second electrode piece with opposite polarities, so that metal ions can move between the first electrode piece and the second electrode piece, thereby realizing the charging and discharging of the electrode assembly; the first electrode piece includes a first current collector, a first active material layer and a second active material layer, the first active material layer is arranged on the first surface of the first current collector, and the second active material layer is arranged on the second surface of the first current collector, so that metal ions can be embedded or de-embedded in the first active material layer and the second active material layer to realize the movement of metal ions; by arranging a first groove and a second groove penetrating the bottom wall of the first groove to the first surface in the first active material layer, the first surface of the first single-sided empty foil area of ​​the first current collector is exposed to the second groove, and the second surface of the first single-sided empty foil area of ​​the first current collector is covered by the second active material layer, the first electrode ear of the electrode assembly is accommodated in the second groove and welded to the first single-sided empty foil area to form a weld, and the second groove can be formed only on the first active material layer of the first electrode piece to accommodate The first electrode tab is provided without providing a groove on the second active material layer, so that the volume of the second active material layer is larger, and the energy density of the electrochemical device provided with this electrode assembly is higher; by allowing the first insulating adhesive layer of the electrode assembly to be accommodated in the first groove and covering the welding point between the first electrode tab and the first single-sided hollow foil area, the first insulating adhesive layer can achieve the insulation effect between the first electrode tab and the second electrode sheet, reducing the possibility of short circuit between the first electrode sheet and the second electrode sheet; since there are burrs on the surface of the first electrode tab and burrs are also easily formed at the welding point with the first single-sided hollow foil area, the first insulating adhesive layer can also isolate the burrs, making it difficult for the burrs to contact the second electrode sheet to cause a short circuit or damage the second electrode sheet; and by allowing the projection of the first insulating adhesive layer along the thickness direction of the first current collector to be located in the first groove, the first insulating adhesive layer can be accommodated in the first groove along the length direction of the first current collector, thereby reducing the overall thickness of the electrode assembly, which can further increase the energy density of the electrochemical device provided with this electrode assembly.

[0008] In some embodiments of the first aspect, along the length direction of the first current collector, the width of the first groove is greater than or equal to the width of the first insulating adhesive layer; along the thickness direction of the first current collector, the depth of the first groove is greater than or equal to the thickness of the first insulating adhesive layer.

[0009] By ensuring that the width of the first groove along the length direction of the first current collector is greater than or equal to the width of the first insulating rubber layer; and the depth of the first groove along the thickness direction of the first current collector is greater than or equal to the thickness of the first insulating rubber layer, the first insulating rubber layer can be accommodated in the first groove, thereby further reducing the overall thickness of the electrode assembly and increasing the energy density of the electrochemical device provided with this electrode assembly.

[0010] In some embodiments of the first aspect, along the length direction of the first current collector, the width of the first groove is W11, the width of the first insulating adhesive layer is M1, and they satisfy 7mm≤W11≤17mm, 5mm≤M1≤15mm; along the thickness direction of the first current collector, the depth of the first groove is H11, the thickness of the first insulating adhesive layer is N1, and they satisfy 5μm≤H11≤55μm, 5μm≤N1≤20μm.

[0011] By ensuring that the width W11 of the first groove along the length direction of the first current collector satisfies 7mm≤W11≤17mm; and the depth H11 of the first groove along the thickness direction of the first current collector satisfies 5μm≤H11≤55μm, on the one hand, more of the first insulating rubber layer can be accommodated in the first groove, the overall thickness of the electrode assembly is smaller, and the energy density of the electrochemical device provided with this electrode assembly is higher; on the other hand, the volume loss of the first active material layer can be reduced, and the energy density of the electrochemical device provided with this electrode assembly is higher.

[0012] By ensuring that the width M1 of the first insulating adhesive layer along the length direction of the first current collector satisfies 5mm≤M1≤15mm and the thickness N1 of the first insulating adhesive layer along the thickness direction of the first current collector satisfies 5μm≤N1≤20μm, on the one hand, the insulating effect of the first insulating adhesive layer can be improved, and the first electrode tab is not easily short-circuited with the second electrode sheet; on the other hand, the shielding area of ​​the first active material layer is smaller, and the energy density of the electrochemical device provided with this electrode assembly is higher.

[0013] In some embodiments of the first aspect, along the length direction of the first current collector, the width of the second groove is W12, and the width of the first tab is P1, satisfying 5 mm ≤ W12 ≤ 15 mm, and 3 mm ≤ P1 ≤ 13 mm.

[0014] By ensuring that the width W12 of the second groove along the length direction of the first current collector satisfies 5mm≤W12≤15mm, on the one hand, the second groove can have sufficient space to accommodate the first electrode tab; on the other hand, the volume loss of the first active material layer can be reduced, and the energy density of the electrochemical device provided with this electrode assembly can be higher.

[0015] By ensuring that the width P1 of the first electrode tab satisfies 3mm≤P1≤13mm along the length direction of the first current collector, on the one hand, the connection surface with the first current collector can be made larger and the connection strength can be higher; on the other hand, the space occupied by the first electrode tab can be made smaller, thereby reducing the space required to be reserved for the second groove, resulting in less volume loss of the first active material layer and a higher energy density of the electrochemical device provided with this electrode assembly.

[0016] In some embodiments of the first aspect, the second pole piece includes:

[0017] a second current collector having a third surface and a fourth surface disposed opposite to each other, the third surface facing the first active material layer, and the fourth surface facing away from the first active material layer;

[0018] a third active material layer, disposed on the third surface;

[0019] a fourth active material layer, disposed on the fourth surface;

[0020] The second insulating adhesive layer is disposed on a side of the third active material layer away from the second current collector. When viewed along the thickness direction of the second current collector, the projection of the second insulating adhesive layer covers the first groove.

[0021] The second electrode sheet includes a second current collector, a third active material layer and a fourth active material layer. The third active material layer is arranged on the third surface of the second current collector, and the fourth active material layer is arranged on the fourth surface of the second current collector, so that metal ions can be embedded or de-embedded in the third active material layer and the fourth active material layer to realize the movement of metal ions; by setting a second insulating adhesive layer, and setting the second insulating adhesive layer on the side of the third active material layer away from the second current collector, so that when observed along the thickness direction of the second current collector, the projection of the second insulating adhesive layer covers the first groove, so that the second insulating adhesive layer can play an insulating role between the first electrode ear and the second electrode sheet, reducing the possibility of the burrs of the first electrode ear contacting the second current collector, thereby reducing the possibility of short circuit between the first electrode sheet and the second electrode sheet.

[0022] In some embodiments of the first aspect, the third active material layer is provided with a third groove, the second insulating adhesive layer is accommodated in the third groove, and a projection of the second insulating adhesive layer along the thickness direction of the second current collector is located in the third groove.

[0023] By providing a third groove in the third active material layer, the second insulating rubber layer is accommodated in the third groove, and the projection of the second insulating rubber layer along the thickness direction of the second current collector is located in the third groove, so that along the length direction of the second current collector, the second insulating rubber layer can be accommodated in the third groove, thereby making the overall thickness of the electrode assembly smaller, and further making the energy density of the electrochemical device provided with this electrode assembly higher.

[0024] In some embodiments of the first aspect, along the length direction of the second current collector, the width of the third groove is greater than or equal to the width of the second insulating adhesive layer; along the thickness direction of the second current collector, the depth of the third groove is greater than or equal to the thickness of the second insulating adhesive layer.

[0025] By ensuring that the width of the third groove along the length direction of the second current collector is greater than or equal to the width of the second insulating rubber layer; and the depth of the third groove along the thickness direction of the second current collector is greater than or equal to the thickness of the second insulating rubber layer, the second insulating rubber layer can be accommodated in the third groove, thereby further reducing the overall thickness of the electrode assembly and increasing the energy density of the electrochemical device provided with this electrode assembly.

[0026] In some embodiments of the first aspect, along the length direction of the second current collector, the width of the third groove is W21, and the width of the second insulating adhesive layer is M2, satisfying 17mm≤W21≤27mm, 15mm≤M2≤25mm; along the thickness direction of the second current collector, the depth of the third groove is H21, and the thickness of the second insulating adhesive layer is N2, satisfying 5μm≤H21≤55μm, 5μm≤N2≤20μm.

[0027] By ensuring that the width W21 of the third groove along the length direction of the second current collector satisfies 17mm≤W21≤27mm; and the depth H21 of the third groove along the thickness direction of the second current collector satisfies 5μm≤H21≤55μm, on the one hand, more of the second insulating rubber layer can be accommodated in the third groove, the overall thickness of the electrode assembly is smaller, and the energy density of the electrochemical device provided with this electrode assembly is higher; on the other hand, the volume loss of the third active material layer can be reduced, and the energy density of the electrochemical device provided with this electrode assembly is higher.

[0028] By ensuring that the width M2 of the second insulating adhesive layer along the length direction of the second current collector satisfies 15mm≤M2≤25mm; and the thickness N2 of the second insulating adhesive layer along the thickness direction of the second current collector satisfies 5μm≤N2≤20μm, on the one hand, the insulating effect of the second insulating adhesive layer can be improved, and the first electrode tab is not easily short-circuited with the second electrode sheet; on the other hand, the shielding area of ​​the third active material layer is smaller, and the energy density of the electrochemical device provided with this electrode assembly is higher.

[0029] In some embodiments of the first aspect, the third active material layer is further provided with a fourth groove extending from the bottom wall of the third groove to the third surface, and the projection of the first electrode tab along the thickness direction of the second current collector is located in the fourth groove.

[0030] By providing a fourth groove in the third active material layer that passes through the bottom wall of the third groove to the third surface, the projection of the first electrode tab along the thickness direction of the second current collector is located in the fourth groove, so that the fourth groove can be used to accommodate part of the first electrode tab, thereby making the overall thickness of the electrode assembly smaller and the energy density of the electrochemical device provided with this electrode assembly higher.

[0031] In some embodiments of the first aspect, along the length direction of the second current collector, the width of the fourth groove is W22, satisfying 4mm≤W22≤16mm; along the thickness direction of the second current collector, the depth of the fourth groove is H22, satisfying 10μm≤H22≤60μm.

[0032] By ensuring that the width W22 of the fourth groove along the length direction of the second current collector satisfies 4mm≤W22≤16mm and the depth H22 of the fourth groove along the thickness direction of the second current collector satisfies 10μm≤H22≤60μm, on the one hand, the fourth groove has sufficient space to accommodate the first electrode tab; on the other hand, the volume loss of the third active material layer can be reduced, and the energy density of the electrochemical device provided with this electrode assembly is higher.

[0033] In some embodiments of the first aspect, the third active material layer is provided with a fifth groove extending through the third active material layer to the third surface, the second current collector includes a second single-sided hollow foil area, the third surface of the second single-sided hollow foil area is exposed in the fifth groove, and the fourth surface of the second single-sided hollow foil area is covered by the fourth active material layer;

[0034] The second pole piece also includes:

[0035] The second electrode tab is accommodated in the fifth groove and welded to the second single-sided hollow foil area to form a welding point;

[0036] The third insulating adhesive layer covers the welding point between the second electrode tab and the second single-sided hollow foil area.

[0037] By providing a fifth groove in the third active material layer that extends through the third active material layer to the third surface, the third surface of the second single-sided hollow foil area of ​​the second current collector is exposed in the fifth groove, and the second single-sided hollow foil area of ​​the second current collector is covered by the fourth active material layer on the fourth surface. The second tab of the electrode assembly is accommodated in the fifth groove and welded to the second single-sided hollow foil area to form a weld. The fifth groove can be formed only in the third active material layer of the second electrode sheet to accommodate the second tab, without providing a groove in the fourth active material layer. This increases the volume of the fourth active material layer and increases the energy density of the electrochemical device provided with this electrode assembly. By providing the third insulating adhesive layer of the electrode assembly to cover the weld between the second tab and the second single-sided hollow foil area, the third insulating adhesive layer can insulate the second tab from the first electrode sheet, reducing the possibility of a short circuit between the first and second electrode sheets. Since burrs may be present on the surface of the second tab and burrs may also be formed at the weld between the second tab and the second single-sided hollow foil area, the third insulating adhesive layer can also isolate the burrs, making it less likely that the burrs will contact the first electrode sheet and cause a short circuit or damage the first electrode sheet.

[0038] In some embodiments of the first aspect, along the length direction of the second current collector, the width of the fifth groove is W23, the width of the second tab is P2, and 5 mm ≤ W23 ≤ 15 mm, and 3 mm ≤ P2 ≤ 13 mm are satisfied.

[0039] By ensuring that the width W23 of the fifth groove satisfies 5mm≤W23≤15mm along the length direction of the second current collector, on the one hand, the fifth groove can have sufficient space to accommodate the second electrode tab; on the other hand, the volume loss of the third active material layer can be reduced, and the energy density of the electrochemical device provided with this electrode assembly can be higher.

[0040] In some embodiments of the first aspect, along the length direction of the second current collector, the width of the third insulating adhesive layer is M3, satisfying 15mm≤M3≤25mm; along the thickness direction of the second current collector, the thickness of the third insulating adhesive layer is N3, satisfying 5μm≤N3≤20μm.

[0041] By ensuring that the width of the third insulating rubber layer along the length direction of the second current collector is M3, satisfying 15mm≤M3≤25mm; and the thickness of the third insulating rubber layer along the thickness direction of the second current collector is N3, 5μm≤N3≤20μm, on the one hand, the insulation effect of the third insulating rubber layer can be better, and the second electrode tab is not easily short-circuited with the first electrode sheet; on the other hand, the shielding area of ​​the third active material layer is smaller, and the energy density of the electrochemical device provided with this electrode assembly is higher.

[0042] In some embodiments of the first aspect, the first active material layer is further provided with a sixth groove, and when viewed along the thickness direction of the first current collector, the projection of the third insulating adhesive layer covers the sixth groove;

[0043] The first pole piece also includes:

[0044] The fourth insulating adhesive layer is accommodated in the sixth groove.

[0045] By providing a sixth groove in the first active material layer, the fourth insulating rubber layer of the first electrode piece is accommodated in the sixth groove, which can make the overall thickness of the electrode assembly smaller, and can further make the energy density of the electrochemical device provided with this electrode assembly higher; by making the projection of the third insulating rubber layer cover the sixth groove when observed along the thickness direction of the first current collector, the third insulating rubber layer can play an insulating role between the second electrode ear and the first electrode piece, reducing the possibility of the burrs of the second electrode ear contacting the first current collector, thereby reducing the possibility of short circuit between the first electrode piece and the second electrode piece.

[0046] In some embodiments of the first aspect, along the length direction of the first current collector, the width of the sixth groove is greater than or equal to the width of the fourth insulating adhesive layer; along the thickness direction of the first current collector, the depth of the sixth groove is greater than or equal to the thickness of the fourth insulating adhesive layer.

[0047] By ensuring that the width of the sixth groove along the length direction of the first current collector is greater than or equal to the width of the fourth insulating rubber layer; and the depth of the sixth groove along the thickness direction of the first current collector is greater than or equal to the thickness of the fourth insulating rubber layer, the fourth insulating rubber layer can be accommodated in the sixth groove, thereby further reducing the overall thickness of the electrode assembly and increasing the energy density of the electrochemical device provided with this electrode assembly.

[0048] In some embodiments of the first aspect, along the length direction of the first current collector, the width of the sixth groove is W13, and the width of the fourth insulating adhesive layer is M4, satisfying 7mm≤W13≤17mm, 5mm≤M4≤15mm; along the thickness direction of the first current collector, the depth of the sixth groove is H12, and the thickness of the fourth insulating adhesive layer is N4, satisfying 5μm≤H12≤55μm, 5μm≤N4≤20μm.

[0049] By ensuring that the width W13 of the sixth groove satisfies 7mm≤W13≤17mm along the length direction of the first current collector and the depth H12 of the sixth groove satisfies 5μm≤H12≤55μm along the thickness direction of the first current collector, on the one hand, more of the fourth insulating rubber layer can be accommodated in the sixth groove, the overall thickness of the electrode assembly is smaller, and the energy density of the electrochemical device provided with this electrode assembly is higher; on the other hand, the volume loss of the first active material layer can be reduced, and the energy density of the electrochemical device provided with this electrode assembly is higher.

[0050] By ensuring that the width M4 of the fourth insulating adhesive layer along the length direction of the first current collector satisfies 5mm≤M4≤15mm and the thickness N4 of the fourth insulating adhesive layer along the thickness direction of the first current collector satisfies 5μm≤N4≤20μm, on the one hand, the insulation effect of the fourth insulating adhesive layer can be improved, and the second electrode tab is not easily short-circuited with the first electrode sheet; on the other hand, the shielding area of ​​the first active material layer is smaller, and the energy density of the electrochemical device provided with this electrode assembly is higher.

[0051] In some embodiments of the first aspect, the first active material layer is further provided with a seventh groove extending from the bottom wall of the sixth groove to the first surface, and the projection of the second electrode tab along the thickness direction of the first current collector is located in the seventh groove.

[0052] By further providing a seventh groove in the first active material layer that passes through the bottom wall of the sixth groove to the first surface, the projection of the second electrode tab along the thickness direction of the first current collector is located within the seventh groove, so that the seventh groove can be used to accommodate part of the second electrode tab, thereby making the overall thickness of the electrode assembly smaller and the energy density of the electrochemical device provided with this electrode assembly higher.

[0053] In some embodiments of the first aspect, along the length direction of the first current collector, the width of the seventh groove is W14, satisfying 4mm≤W14≤16mm; along the thickness direction of the first current collector, the depth of the seventh groove is H13, satisfying 10μm≤H13≤60μm.

[0054] By ensuring that the width W14 of the seventh groove satisfies 4mm≤W14≤16mm along the length direction of the first current collector and the depth H13 of the seventh groove satisfies 10μm≤H13≤60μm along the thickness direction of the first current collector, on the one hand, the seventh groove has sufficient space to accommodate the second electrode tab; on the other hand, the volume loss of the first active material layer can be reduced, and the energy density of the electrochemical device provided with this electrode assembly is higher.

[0055] In some embodiments of the first aspect, the first electrode is a negative electrode, and the second electrode is a positive electrode.

[0056] In some embodiments of the first aspect, the first electrode tab is formed on the first current collector by laser welding, and the second electrode tab is formed on the second current collector by laser welding.

[0057] Compared with traditional ultrasonic welding, laser welding can form grooves only on the first active material layer, while no grooves are formed on the second active material layer. Therefore, only the first insulating rubber layer needs to be provided on the first active material layer corresponding to the first electrode tab, which is beneficial to reducing the thickness of the first electrode sheet and improving the energy density.

[0058] In some embodiments of the first aspect, the first pole tab is a negative pole tab, the second pole tab is a positive pole tab, the fifth groove includes a first sub-groove and a second sub-groove, the projection of the second sub-groove along the thickness direction of the second current collector is located within the first sub-groove, and along the width direction of the first pole tab, the distance between one side of the first pole tab and the corresponding groove wall of the first groove is a, and along the width direction of the second pole tab, the distance between one side of the second pole tab and the corresponding groove wall of the second sub-groove is b, and a and b satisfy: b<a.

[0059] Laser welding of the tabs generates heat during the welding process, which has a thermal impact on the active materials around the tabs, causing the active materials to fall off. Therefore, a gap needs to be set between the tabs and the corresponding slot walls. Since the current collectors and tab materials of the positive and negative electrodes are different, welding the negative tabs requires a higher temperature, so a larger gap is required, that is, b < a.

[0060] In some embodiments of the first aspect, a ≥ 0.2 mm, b ≥ 0.2 mm.

[0061] By limiting a≥0.2mm and b≥0.2mm, the influence of heat generated by the tab during laser welding on the surrounding active materials is controlled.

[0062] In a second aspect, the present application provides an electrochemical device comprising the electrode assembly as described above.

[0063] In a third aspect, the present application provides an electrical device, comprising the electrochemical device as described above, and the electrochemical device is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can also be obtained based on these drawings.

[0065] FIG1 is a schematic cross-sectional view of an electrode assembly according to some embodiments of the present application;

[0066] FIG2 is a schematic diagram of a partially enlarged structure of a portion A of the electrode assembly in FIG1 ;

[0067] FIG3 is a schematic cross-sectional view of an electrode assembly according to some other embodiments of the present application;

[0068] FIG4 is a schematic diagram of a partially enlarged structure of a portion B of the electrode assembly in FIG3 ;

[0069] FIG5 is a schematic diagram of a partially enlarged structure of a portion C of the electrode assembly in FIG3 ;

[0070] FIG6 is a schematic cross-sectional view of an electrode assembly according to some other embodiments of the present application;

[0071] FIG7 is a schematic cross-sectional structural diagram of an electrode assembly provided in some other embodiments of the present application.

[0072] Icon: 10-electrode assembly; 100-first pole piece; 110-first current collector; 111-first surface; 112-second surface; 113-first single-sided empty foil area; 120-first active material layer; 121-first groove; 122-second groove; 123-sixth groove; 124-seventh groove; 130-second active material layer; 140-first pole lug; 150-first insulating rubber layer; 160-fourth insulating rubber layer; 200-second pole piece; 210-second current collector; 211-third surface; 212-fourth surface; 213-second single-sided empty foil area; 220-third active material layer; 221-third groove; 222-fourth groove; 223-fifth groove; 2231-first sub-groove; 2232-second sub-groove; 230-fourth active material layer; 240-second insulating rubber layer; 250-second pole lug; 260-third insulating rubber layer. Specific embodiment

[0073] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0074] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0075] The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

[0076] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0077] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0078] An electrochemical device includes a housing, an electrode assembly, and an electrolyte. The housing is used to hold the electrode assembly and electrolyte. The electrode assembly consists of a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive electrode collector. The portion of the positive electrode collector not coated with the positive active material layer is provided with a positive electrode tab, which allows electrical energy to be input or output from the positive electrode sheet. For example, in lithium-ion batteries, the positive electrode current collector can be made of aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, a ternary material, or lithium manganese oxide. The negative electrode sheet includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative electrode collector. The portion of the negative electrode collector not coated with the negative active material layer is provided with a negative electrode tab, which allows electrical energy to be input or output from the negative electrode sheet. The negative electrode current collector can be made of copper, and the negative electrode active material can be made of carbon or silicon. The separator can be made of polypropylene (PP) or polyethylene (PE). Furthermore, the electrode assembly can be a wound or laminated structure, which is not limited in this embodiment.

[0079] With the development of the new energy industry, batteries are gradually developing in the direction of high energy density and high power density. However, the positive electrode sheet or negative electrode sheet in the current electrode assembly generally consists of a current collector, two active material layers arranged on opposite sides of the current collector, and a tab. Grooves need to be provided on the active material layer to accommodate the tabs so that the tabs are connected to the current collector. However, due to previous process limitations, such as forming grooves by ultrasonic welding, only two opposing grooves can be formed on two active material layers at the same time, and the tab is only accommodated in one of the grooves.

[0080] To insulate the positive and negative electrodes, two layers of insulating adhesive covering the two grooves are provided on the two active material layers. To reduce the lithium plating problem of the electrochemical device, the area of ​​the active material layer of the positive electrode needs to be smaller than that of the active material layer of the negative electrode. Therefore, two layers of insulating adhesive corresponding to the negative electrode tabs are provided on the two active material layers of the positive electrode, and these two insulating adhesive layers can further isolate the negative electrode tabs from the current collector of the positive electrode. To further isolate the positive electrode tabs from the negative electrode, two layers of insulating adhesive corresponding to the positive electrode tabs are provided on the two active material layers of the negative electrode.

[0081] After the electrode assembly is wound and formed, each electrode tab has four layers of insulating rubber layers, which makes the electrode assembly thicker and the energy density of the electrochemical device lower.

[0082] In order to improve the energy density of an electrochemical device, the present application provides an electrode assembly, the electrode assembly including a first electrode piece and a second electrode piece with opposite polarities, the first electrode piece including a first current collector, a first active material layer, a second active material layer, a first electrode ear and a first insulating adhesive layer, the first current collector having a first surface and a second surface arranged opposite to each other; the first active material layer is arranged on the first surface, the first active material layer is provided with a first groove and a second groove extending through the bottom wall of the first groove to the first surface, the first current collector includes a first single-sided empty foil area, the first surface of the first single-sided empty foil area is exposed to the second groove; the second active material layer is arranged on the second surface, the first single-sided empty foil area is covered by the second active material layer on the second surface; the first electrode ear is accommodated in the second groove and is welded to the first single-sided empty foil area to form a weld; the first insulating adhesive layer is accommodated in the first groove and covers the weld between the first electrode ear and the first single-sided empty foil area, and the projection of the first insulating adhesive layer along the thickness direction of the first current collector is located within the first groove.

[0083] In an electrode assembly of this structure, the electrode assembly includes a first electrode sheet and a second electrode sheet with opposite polarities, so that metal ions can move between the first electrode sheet and the second electrode sheet, thereby realizing charging and discharging of the electrode assembly; the first electrode sheet includes a first current collector, a first active material layer and a second active material layer, the first active material layer is arranged on the first surface of the first current collector, and the second active material layer is arranged on the second surface of the first current collector, so that metal ions can be embedded or de-embedded in the first active material layer and the second active material layer to realize the movement of metal ions; by arranging a first groove and a second groove penetrating the bottom wall of the first groove to the first surface in the first active material layer, the first surface of the first single-sided empty foil area of ​​the first current collector is exposed to the second groove, and the first single-sided empty foil area of ​​the first current collector is covered by the second active material layer on the second surface, the first pole ear of the electrode assembly is accommodated in the second groove and welded to the first single-sided empty foil area to form a weld, so that the second groove can be formed only on the first active material layer of the first electrode sheet to The first electrode tab is accommodated without providing a groove on the second active material layer, so that the volume of the second active material layer is larger, and the energy density of the electrochemical device provided with this electrode assembly is higher; by accommodating the first insulating adhesive layer of the electrode assembly in the first groove and covering the welding point between the first electrode tab and the first single-sided hollow foil area, the first insulating adhesive layer can achieve the insulation effect between the first electrode tab and the second electrode sheet, reducing the possibility of short circuit between the first electrode sheet and the second electrode sheet; because burrs exist on the surface of the first electrode tab and burrs are also easily formed at the welding point with the first single-sided hollow foil area, the first insulating adhesive layer can also isolate the burrs, making it less likely for the burrs to contact the second electrode sheet to cause a short circuit or damage the second electrode sheet; and by ensuring that the projection of the first insulating adhesive layer along the thickness direction of the first current collector is located within the first groove, the first insulating adhesive layer can be accommodated in the first groove along the length direction of the first current collector, thereby reducing the overall thickness of the electrode assembly, which can further increase the energy density of the electrochemical device provided with this electrode assembly.

[0084] The present invention provides an electrochemical device including an electrode assembly. The electrochemical device may be a secondary battery or a primary battery, such as a lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, although this embodiment is not limited thereto. The electrochemical device may be cylindrical, flat, rectangular, or have other shapes, although this embodiment is not limited thereto.

[0085] The embodiments of the present application provide an electrical device that uses an electrochemical device as a power source. The electrical device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, and the like.

[0086] 1 and 2 , FIG1 is a schematic cross-sectional structural diagram of an electrode assembly provided in some embodiments of the present application; FIG2 is a schematic enlarged structural diagram of a portion A of the electrode assembly in FIG1 .

[0087] The embodiment of the present application provides an electrode assembly 10, including a first electrode sheet 100 and a second electrode sheet 200 with opposite polarities, the first electrode sheet 100 including a first current collector 110, a first active material layer 120, a second active material layer 130, a first electrode tab 140 and a first insulating adhesive layer 150, the first current collector 110 having a first surface 111 and a second surface 112 arranged opposite to each other; the first active material layer 120 is arranged on the first surface 111, the first active material layer 120 is provided with a first groove 121 and a second groove 122 extending through the bottom wall of the first groove 121 to the first surface 111, the first current collector 110 includes A first single-sided hollow foil area 113, the first surface 111 of the first single-sided hollow foil area 113 is exposed in the second groove 122; the second active material layer 130 is provided on the second surface 112, and the second surface 112 of the first single-sided hollow foil area 113 is covered by the second active material layer 130; the first electrode tab 140 is accommodated in the second groove 122 and welded to the first single-sided hollow foil area 113 to form a weld; the first insulating adhesive layer 150 is accommodated in the first groove 121 and covers the weld between the first electrode tab 140 and the first single-sided hollow foil area 113, and the projection of the first insulating adhesive layer 150 along the thickness direction of the first current collector 110 is located within the first groove 121.

[0088] In some embodiments, the first single-sided empty foil area 113 is a section of the first current collector 110 and has a first surface 111 and a second surface 112 .

[0089] In some embodiments, the first electrode tab 140 is made of a metal material, such as copper, aluminum, etc. The first electrode tab 140 and the first current collector 110 are made of the same material, which facilitates welding of the first electrode tab 140 and the first current collector 110 .

[0090] In some embodiments, the first electrode tab 140 and the first current collector 110 may be welded by laser welding.

[0091] The electrode assembly 10 includes a first electrode sheet 100 and a second electrode sheet 200 of opposite polarity, allowing metal ions to move between the first electrode sheet 100 and the second electrode sheet 200, thereby achieving charging and discharging of the electrode assembly 10. The first electrode sheet 100 includes a first current collector 110, a first active material layer 120, and a second active material layer 130. The first active material layer 120 is disposed on a first surface 111 of the first current collector 110, and the second active material layer 130 is disposed on a second surface 112 of the first current collector 110. Metal ions can be embedded in or de-embedded in the first active material layer 120 and the second active material layer 130, thereby achieving metal ion movement. By providing a first groove 121 and a second groove 122 extending from the bottom wall of the first groove 121 to the first surface 111 in the first active material layer 120, the first surface 111 of the first single-sided empty foil area 113 of the first current collector 110 is exposed to the second groove 122, and the second surface 112 of the first single-sided empty foil area 113 of the first current collector 110 is covered by the second active material layer 130. The first electrode tab 140 of the electrode assembly 10 is accommodated in the second groove 122 and welded to the first single-sided empty foil area 113 to form a weld. The second groove 122 can be formed only on the first active material layer 120 of the first electrode sheet 100 to accommodate the first electrode tab 140, without providing a groove on the second active material layer 130. This increases the volume of the second active material layer 130 and increases the energy density of the electrochemical device provided with this electrode assembly 10. By positioning the first insulating layer 150 of the electrode assembly 10 within the first recess 121 and covering the weld between the first electrode tab 140 and the first single-sided hollow foil region 113, the first insulating layer 150 can insulate the first electrode tab 140 from the second electrode sheet 200, reducing the possibility of a short circuit between the first electrode sheet 100 and the second electrode sheet 200. Since burrs may be present on the surface of the first electrode tab 140 and are also likely to form at the weld between the first electrode tab 140 and the first single-sided hollow foil region 113, the first insulating layer 150 can also isolate the burrs, preventing them from contacting the second electrode sheet 200 and causing a short circuit or damage. Furthermore, by positioning the projection of the first insulating layer 150 along the thickness direction of the first current collector 110 within the first recess 121, the first insulating layer 150 can be positioned within the first recess 121 along the length of the first current collector 110, thereby reducing the overall thickness of the electrode assembly 10 and further increasing the energy density of the electrochemical device incorporating the electrode assembly 10.

[0092] In some embodiments, the first electrode tab 140 is formed on the first current collector 110 by laser welding, and the second electrode tab 250 is formed on the second current collector 210 by laser welding.

[0093] Compared with traditional ultrasonic welding, laser welding can form grooves only on the first active material layer 120, while no grooves are formed on the second active material layer 130. Therefore, corresponding to the first electrode tab 140, only the first insulating glue layer 150 needs to be set on the first active material layer 120, which is beneficial to reducing the thickness of the first electrode piece 100 and improving the energy density.

[0094] In some embodiments, along the length direction of the first current collector 110, the width of the first groove 121 is greater than or equal to the width of the first insulating layer 150, that is, M1 ≤ W11. Along the thickness direction of the first current collector 110, the depth of the first groove 121 is greater than or equal to the thickness of the first insulating layer 150, that is, N1 ≤ H11.

[0095] By ensuring that the width of the first groove 121 along the length direction of the first current collector 110 is greater than or equal to the width of the first insulating adhesive layer 150 and the depth of the first groove 121 along the thickness direction of the first current collector 110 is greater than or equal to the thickness of the first insulating adhesive layer 150, the first insulating adhesive layer 150 can be accommodated in the first groove 121, thereby further reducing the overall thickness of the electrode assembly 10 and increasing the energy density of the electrochemical device provided with the electrode assembly 10.

[0096] In other embodiments, along the thickness direction of the first current collector 110, the depth of the first groove 121 may also be less than the thickness of the first insulating adhesive layer 150, so that a portion of the first insulating adhesive layer 150 can be accommodated in the first groove 121. Compared with the electrode without the first groove 121, the overall thickness of the first electrode 100 in this embodiment is smaller, which can improve the energy density of the electrochemical device.

[0097] In some embodiments, along the length direction of the first current collector 110, the width W11 of the first groove 121 satisfies 7 mm ≤ W11 ≤ 17 mm. For example, W11 may be 7 mm, 12 mm, or 17 mm. Along the thickness direction of the first current collector 110, the depth H11 of the first groove 121 satisfies 5 μm ≤ H11 ≤ 55 μm. For example, H11 may be 5 μm, 30 μm, or 55 μm.

[0098] By ensuring that the width W11 of the first groove 121 along the length direction of the first current collector 110 satisfies 7mm≤W11≤17mm and the depth H11 of the first groove 121 along the thickness direction of the first current collector 110 satisfies 5μm≤H11≤55μm, on the one hand, more of the first insulating adhesive layer 150 can be accommodated in the first groove 121, the overall thickness of the electrode assembly 10 is smaller, and the energy density of the electrochemical device provided with this electrode assembly 10 is higher; on the other hand, the volume loss of the first active material layer 120 can be reduced, and the energy density of the electrochemical device provided with this electrode assembly 10 is higher.

[0099] In some embodiments, along the length direction of the first current collector 110, the width M1 of the first insulating adhesive layer 150 satisfies 5 mm ≤ M1 ≤ 15 mm. For example, M1 can be 5 mm, 10 mm, or 15 mm. Along the thickness direction of the first current collector 110, the thickness N1 of the first insulating adhesive layer 150 satisfies 5 μm ≤ N1 ≤ 20 μm. For example, N1 can be 5 μm, 12 μm, or 20 μm.

[0100] By ensuring that the width M1 of the first insulating adhesive layer 150 along the length direction of the first current collector 110 satisfies 5mm≤M1≤15mm and the thickness N1 of the first insulating adhesive layer 150 along the thickness direction of the first current collector 110 satisfies 5μm≤N1≤20μm, on the one hand, the insulation effect of the first insulating adhesive layer 150 can be improved, and the first electrode tab 140 is not easily short-circuited with the second electrode sheet 200; on the other hand, the shielding area of ​​the first active material layer 120 is small, and the energy density of the electrochemical device provided with this electrode assembly 10 is higher.

[0101] In some embodiments, along the length direction of the first current collector 110, the width of the second groove 122 is W12, and the width of the first tab 140 is P1, satisfying 5mm≤W12≤15mm, 3mm≤P1≤13mm. For example, W12 can be 5mm, 9mm or 15mm, and P1 can be 3mm, 8mm or 13mm, etc.

[0102] By ensuring that the width W12 of the second groove 122 along the length direction of the first current collector 110 satisfies 5mm≤W12≤15mm, on the one hand, the second groove 122 can have sufficient space to accommodate the first electrode tab 140; on the other hand, the volume loss of the first active material layer 120 can be reduced, and the energy density of the electrochemical device provided with this electrode assembly 10 can be higher.

[0103] By ensuring that the width P1 of the first electrode tab 140 along the length direction of the first current collector 110 satisfies 3mm≤P1≤13mm, on the one hand, the connection surface with the first current collector 110 can be made larger and the connection strength can be higher; on the other hand, the space occupied by the first electrode tab 140 can be made smaller, so that the space required to be reserved for the second groove 122 is smaller, the volume loss of the first active material layer 120 is reduced, and the energy density of the electrochemical device provided with this electrode assembly 10 is higher.

[0104] 3 and 4 , FIG3 is a schematic cross-sectional structural diagram of an electrode assembly provided in some other embodiments of the present application; FIG4 is a schematic enlarged structural diagram of a portion B of the electrode assembly in FIG3 .

[0105] The present embodiment provides an electrode assembly 10, comprising a first electrode sheet 100 and a second electrode sheet 200 of opposite polarity. The first electrode sheet 100 comprises a first current collector 110, a first active material layer 120, a second active material layer 130, a first electrode tab 140, and a first insulating adhesive layer 150. The first active material layer 120 and the second active material layer 130 are respectively disposed on the two surfaces of the first current collector 110. The first active material layer 120 is provided with a first groove 121 and a second groove 122. The first electrode tab 140 is accommodated in the second groove 122 and welded to the first single-sided hollow foil area 113. The first insulating adhesive layer 150 is accommodated in the first groove 121 and covers the weld between the first electrode tab 140 and the first single-sided hollow foil area 113. The structures of the first groove 121 and the second groove 122 are similar to those in the above-described electrode assembly embodiment and are not further described here.

[0106] In some embodiments, the second electrode 200 includes a second current collector 210, a third active material layer 220, a fourth active material layer 230 and a second insulating adhesive layer 240. The second current collector 210 has a third surface 211 and a fourth surface 212 that are relatively arranged, the third surface 211 faces the first active material layer 120, and the fourth surface 212 is back to the first active material layer 120; the third active material layer 220 is arranged on the third surface 211; the fourth active material layer 230 is arranged on the fourth surface 212; the second insulating adhesive layer 240 is arranged on the side of the third active material layer 220 away from the second current collector 210. When observed along the thickness direction of the second current collector 210, the projection of the second insulating adhesive layer 240 covers the first groove 121.

[0107] By setting the third active material layer 220 on the third surface 211 of the second current collector 210 and the fourth active material layer 230 on the fourth surface 212 of the second current collector 210, metal ions can be embedded or de-embedded in the third active material layer 220 and the fourth active material layer 230 to achieve the movement of metal ions; by setting the second insulating adhesive layer 240 and setting the second insulating adhesive layer 240 on the side of the third active material layer 220 away from the second current collector 210, when observed along the thickness direction of the second current collector 210, the projection of the second insulating adhesive layer 240 covers the first groove 121, so that the second insulating adhesive layer 240 can play an insulating role between the first electrode ear 140 and the second electrode sheet 200, reducing the possibility of the burrs of the first electrode ear 140 contacting the second current collector 210, thereby reducing the possibility of short circuit between the first electrode sheet 100 and the second electrode sheet 200.

[0108] In some embodiments, the third active material layer 220 is provided with a third groove 221 , the second insulating adhesive layer 240 is accommodated in the third groove 221 , and the projection of the second insulating adhesive layer 240 along the thickness direction of the second current collector 210 is located in the third groove 221 .

[0109] By setting a third groove 221 in the third active material layer 220, the second insulating rubber layer 240 is accommodated in the third groove 221, and the projection of the second insulating rubber layer 240 along the thickness direction of the second current collector 210 is located in the third groove 221, so that along the length direction of the second current collector 210, the second insulating rubber layer 240 can be accommodated in the third groove 221, thereby making the overall thickness of the electrode assembly 10 smaller, and further making the energy density of the electrochemical device provided with this electrode assembly 10 higher.

[0110] In some embodiments, the width of the third groove 221 along the length direction of the second current collector 210 is greater than or equal to the width of the second insulating adhesive layer 240, that is, M2 ≤ W21. Along the thickness direction of the second current collector 210, the depth of the third groove 221 is greater than or equal to the thickness of the second insulating adhesive layer 240, that is, N2 ≤ H21.

[0111] By ensuring that the width of the third groove 221 along the length direction of the second current collector 210 is greater than or equal to the width of the second insulating rubber layer 240; and the depth of the third groove 221 along the thickness direction of the second current collector 210 is greater than or equal to the thickness of the second insulating rubber layer 240, the second insulating rubber layer 240 can be accommodated in the third groove 221, thereby further reducing the overall thickness of the electrode assembly 10 and increasing the energy density of the electrochemical device provided with this electrode assembly 10.

[0112] In other embodiments, along the thickness direction of the second current collector 210, the depth of the third groove 221 may also be less than the thickness of the second insulating adhesive layer 240, so that a portion of the second insulating adhesive layer 240 can be accommodated in the third groove 221. Compared with the electrode without the third groove 221, the overall thickness of the first electrode 100 in this embodiment is smaller, which can improve the energy density of the electrochemical device.

[0113] In some embodiments, along the length direction of the second current collector 210, the width W21 of the third groove 221 satisfies 17 mm ≤ W21 ≤ 27 mm. For example, W21 may be 17 mm, 22 mm, or 27 mm. Along the thickness direction of the second current collector 210, the depth H21 of the third groove 221 satisfies 5 μm ≤ H21 ≤ 55 μm. For example, H21 may be 5 μm, 35 μm, or 55 μm.

[0114] By ensuring that the width W21 of the third groove 221 along the length direction of the second current collector 210 satisfies 17mm≤W21≤27mm; and the depth H21 of the third groove 221 along the thickness direction of the second current collector 210 satisfies 5μm≤H21≤55μm, on the one hand, more of the second insulating adhesive layer 240 can be accommodated in the third groove 221, the overall thickness of the electrode assembly 10 is smaller, and the energy density of the electrochemical device provided with this electrode assembly 10 is higher; on the other hand, the volume loss of the third active material layer 220 can be reduced, and the energy density of the electrochemical device provided with this electrode assembly 10 is higher.

[0115] In some embodiments, the width of the second insulating adhesive layer 240 along the length direction of the second current collector 210 is M2, satisfying 5 mm ≤ M2 ≤ 25 mm. For example, M2 can be 5 mm, 15 mm, or 25 mm. The thickness of the second insulating adhesive layer 240 along the thickness direction of the second current collector 210 is N2, satisfying 5 μm ≤ N2 ≤ 20 μm. For example, N2 can be 5 μm, 12 μm, or 20 μm.

[0116] By ensuring that the width M2 of the second insulating adhesive layer 240 along the length direction of the second current collector 210 satisfies 15mm≤M2≤25mm; and the thickness N2 of the second insulating adhesive layer 240 along the thickness direction of the second current collector 210 satisfies 5μm≤N2≤20μm, on the one hand, the insulation effect of the second insulating adhesive layer 240 can be improved, and the first electrode tab 140 is not easily short-circuited with the second electrode sheet 200; on the other hand, the shielding area of ​​the third active material layer 220 is smaller, and the energy density of the electrochemical device provided with this electrode assembly 10 is higher.

[0117] In some embodiments, the third active material layer 220 is further provided with a fourth groove 222 extending from the bottom wall of the third groove 221 to the third surface 211 , and the projection of the first electrode tab 140 along the thickness direction of the second current collector 210 is located in the fourth groove 222 .

[0118] By providing a fourth groove 222 in the third active material layer 220 that passes through the bottom wall of the third groove 221 to the third surface 211, the projection of the first electrode tab 140 along the thickness direction of the second current collector 210 is located in the fourth groove 222, so that the first electrode sheet 100 and the second electrode sheet 200 are stacked, and when the thickness of the first electrode tab 140 is greater than the thickness of the first active material layer 120, the fourth groove 222 can be used to accommodate part of the first electrode tab 140, thereby making the overall thickness of the electrode assembly 10 smaller and the energy density of the electrochemical device provided with this electrode assembly 10 higher.

[0119] In some embodiments, the width of the fourth groove 222 along the length direction of the second current collector 210 is W22, satisfying 4 mm ≤ W22 ≤ 16 mm. For example, W22 may be 4 mm, 12 mm, or 16 mm. The depth of the fourth groove 222 along the thickness direction of the second current collector 210 is H22, satisfying 10 μm ≤ H22 ≤ 60 μm. For example, H22 may be 10 μm, 35 μm, or 60 μm.

[0120] By ensuring that the width W22 of the fourth groove 222 along the length direction of the second current collector 210 satisfies 4mm≤W22≤16mm and the depth H22 of the fourth groove 222 along the thickness direction of the second current collector 210 satisfies 10μm≤H22≤60μm, on the one hand, the fourth groove 222 has sufficient space to accommodate the first electrode tab 140; on the other hand, the volume loss of the third active material layer 220 can be reduced, and the energy density of the electrochemical device provided with this electrode assembly 10 is higher.

[0121] In some embodiments, the third active material layer 220 is provided with a fifth groove 223 that passes through the third active material layer 220 to the third surface 211. The second current collector 210 includes a second single-sided hollow foil area 213. The third surface 211 of the second single-sided hollow foil area 213 is exposed in the fifth groove 223. The second single-sided hollow foil area 213 is covered by the fourth active material layer 230 on the fourth surface 212.

[0122] The second electrode piece 200 further includes a second electrode tab 250 and a third insulating adhesive layer 260 . The second electrode tab 250 is accommodated in the fifth groove 223 and is welded to the second single-sided hollow foil area 213 to form a welding point. The third insulating adhesive layer 260 covers the welding point between the second electrode tab 250 and the second single-sided hollow foil area 213 .

[0123] In some embodiments, the second electrode tab 250 is made of a metal material, such as copper, aluminum, etc. The second electrode tab 250 and the second current collector 210 are made of the same material, which facilitates welding of the second electrode tab 250 and the second current collector 210 .

[0124] In some embodiments, the first pole tab 250 is a negative pole tab, the second pole tab 250 is a positive pole tab, the fifth groove 223 includes a first sub-groove 2231 and a second sub-groove 2232, the projection of the second sub-groove 2232 along the thickness direction of the second current collector 210 is located within the first sub-groove 2231, along the width direction of the first pole tab 250, the distance between one side of the first pole tab 250 and the corresponding groove wall of the first groove 121 is a, along the width direction of the second pole tab 250, the distance between one side of the second pole tab 250 and the corresponding groove wall of the second sub-groove 2232 is b, and a and b satisfy: b<a.

[0125] Laser welding of the tabs generates heat during the welding process, which has a thermal impact on the active materials around the tabs, causing the active materials to fall off. Therefore, a gap needs to be set between the tabs and the corresponding slot walls. Since the current collectors and tab materials of the positive and negative electrodes are different, welding the negative tabs requires a higher temperature, so a larger gap is required, that is, b < a.

[0126] In some embodiments, a ≥ 0.2 mm, b ≥ 0.2 mm.

[0127] By limiting a≥0.2mm and b≥0.2mm, the influence of heat generated by the tab during laser welding on the surrounding active material layer is controlled. When a<0.2mm and b<0.2mm, the active material layer will be affected by the heat generated during laser welding, causing the active material layer to fall off, leading to lithium deposition and reduced energy density.

[0128] By providing a fifth groove 223 in the third active material layer 220 that passes through the third active material layer 220 to the third surface 211, the third surface 211 of the second single-sided empty foil area 213 of the second current collector 210 is exposed to the fifth groove 223, and the second single-sided empty foil area 213 of the second current collector 210 is covered by the fourth active material layer 230 on the fourth surface 212. The second electrode tab 250 of the electrode assembly 10 is accommodated in the fifth groove 223 and welded to the second single-sided empty foil area 213 to form a weld. The fifth groove 223 can be formed only on the third active material layer 220 of the second electrode sheet 200 to accommodate the second electrode tab 250, without providing a groove on the fourth active material layer 230. This makes the volume of the fourth active material layer 230 larger and the energy density of the electrochemical device provided with this electrode assembly 10 higher. By making the third insulating rubber layer 260 of the electrode assembly 10 cover the welding point between the second electrode tab 250 and the second single-sided hollow foil area 213, the third insulating rubber layer 260 can achieve the insulation effect between the second electrode tab 250 and the first electrode piece 100, thereby reducing the possibility of short circuit between the first electrode piece 100 and the second electrode piece 200; since there are burrs on the surface of the second electrode tab 250, and burrs are also easily formed at the welding point with the second single-sided hollow foil area 213, the third insulating rubber layer 260 can also isolate the burrs, making it difficult for the burrs to contact the first electrode piece 100 to cause a short circuit or damage the first electrode piece 100.

[0129] In some embodiments, along the length direction of the second current collector 210, the width of the fifth groove 223 is W23, and the width of the second tab 250 is P2, satisfying 5mm≤W23≤15mm, 3mm≤P2≤13mm. For example, W23 can be 5mm, 11mm or 15mm, and P2 can be 3mm, 9mm or 13mm, etc.

[0130] By ensuring that the width W23 of the fifth groove 223 along the length direction of the second current collector 210 satisfies 5mm≤W23≤15mm, on the one hand, the fifth groove 223 can have sufficient space to accommodate the second electrode tab 250; on the other hand, the volume loss of the third active material layer 220 can be reduced, and the energy density of the electrochemical device provided with this electrode assembly 10 can be higher.

[0131] In some embodiments, the width of the third insulating adhesive layer 260 along the length direction of the second current collector 210 is M3, satisfying 15 mm ≤ M3 ≤ 25 mm. For example, M3 can be 15 mm, 20 mm, or 25 mm. The thickness of the third insulating adhesive layer 260 along the thickness direction of the second current collector 210 is N3, satisfying 5 μm ≤ N3 ≤ 20 μm. For example, N3 can be 5 μm, 13 μm, or 20 μm.

[0132] By ensuring that the width of the third insulating adhesive layer 260 along the length direction of the second current collector 210 is M3, satisfying 15mm≤M3≤25mm; and the thickness of the third insulating adhesive layer 260 along the thickness direction of the second current collector 210 is N3, 5μm≤N3≤20μm, on the one hand, the insulation effect of the third insulating adhesive layer 260 can be better, and the second electrode tab 250 is not easily short-circuited with the first electrode sheet 100; on the other hand, the shielding area of ​​the third active material layer 220 is smaller, and the energy density of the electrochemical device provided with this electrode assembly 10 is higher.

[0133] 3 and 5 , FIG5 is a schematic diagram of a partially enlarged structure of a portion C of the electrode assembly in FIG3 .

[0134] In some embodiments, the first active material layer 120 further includes a sixth groove 123 . When viewed along the thickness direction of the first current collector 110 , the projection of the third insulating adhesive layer 260 covers the sixth groove 123 . The first pole piece 100 further includes a fourth insulating adhesive layer 160 , which is received in the sixth groove 123 .

[0135] By providing a sixth groove 123 in the first active material layer 120, the fourth insulating rubber layer 160 of the first electrode piece 100 is accommodated in the sixth groove 123, which can make the overall thickness of the electrode assembly 10 smaller, and can further make the energy density of the electrochemical device provided with this electrode assembly 10 higher; by making the projection of the third insulating rubber layer 260 cover the sixth groove 123 when observed along the thickness direction of the first current collector 110, the third insulating rubber layer 260 can play an insulating role between the second electrode tab 250 and the first electrode piece 100, reducing the possibility of burrs of the second electrode tab 250 contacting the first current collector 110, thereby reducing the possibility of short circuit between the first electrode piece 100 and the second electrode piece 200.

[0136] In some embodiments, along the length direction of the first current collector 110 , the width of the sixth groove 123 is greater than or equal to the width of the fourth insulating layer 160 . Along the thickness direction of the first current collector 110 , the depth of the sixth groove 123 is greater than or equal to the thickness of the fourth insulating layer 160 .

[0137] By ensuring that the width of the sixth groove 123 along the length direction of the first current collector 110 is greater than or equal to the width of the fourth insulating rubber layer 160; and the depth of the sixth groove 123 along the thickness direction of the first current collector 110 is greater than or equal to the thickness of the fourth insulating rubber layer 160, the fourth insulating rubber layer 160 can be accommodated in the sixth groove 123, thereby further reducing the overall thickness of the electrode assembly 10 and increasing the energy density of the electrochemical device provided with this electrode assembly 10.

[0138] In other embodiments, along the thickness direction of the first current collector 110, the depth of the sixth groove 123 may also be less than the thickness of the fourth insulating adhesive layer 160, so that a portion of the fourth insulating adhesive layer 160 can be accommodated in the sixth groove 123. Compared with the electrode without the sixth groove 123, the overall thickness of the first electrode 100 in this embodiment is smaller, which can improve the energy density of the electrochemical device.

[0139] In some embodiments, along the length direction of the first current collector 110, the width W13 of the sixth groove 123 satisfies 7 mm ≤ W13 ≤ 17 mm. For example, W13 may be 7 mm, 12 mm, or 17 mm. Along the thickness direction of the first current collector 110, the depth H12 of the sixth groove 123 satisfies 5 μm ≤ H12 ≤ 55 μm. For example, H12 may be 5 μm, 25 μm, or 55 μm.

[0140] By ensuring that the width W13 of the sixth groove 123 along the length direction of the first current collector 110 satisfies 7mm≤W13≤17mm; and the depth H12 of the sixth groove 123 along the thickness direction of the first current collector 110 satisfies 5μm≤H12≤55μm, on the one hand, more of the fourth insulating adhesive layer 160 can be accommodated in the sixth groove 123, the overall thickness of the electrode assembly 10 is smaller, and the energy density of the electrochemical device provided with this electrode assembly 10 is higher; on the other hand, the volume loss of the first active material layer 120 can be reduced, and the energy density of the electrochemical device provided with this electrode assembly 10 is higher.

[0141] In some embodiments, the width of the fourth insulating adhesive layer 160 along the length direction of the first current collector 110 is M4, satisfying 5 mm ≤ M4 ≤ 15 mm. For example, M4 can be 5 mm, 11 mm, or 15 mm. The thickness of the fourth insulating adhesive layer 160 along the thickness direction of the first current collector 110 is N4, satisfying 5 μm ≤ N4 ≤ 20 μm. For example, N4 can be 5 μm, 12 μm, or 20 μm.

[0142] By ensuring that the width M4 of the fourth insulating adhesive layer 160 along the length direction of the first current collector 110 satisfies 5mm≤M4≤15mm; and the thickness N4 of the fourth insulating adhesive layer 160 along the thickness direction of the first current collector 110 satisfies 5μm≤N4≤20μm, on the one hand, the insulation effect of the fourth insulating adhesive layer 160 can be improved, and the second electrode tab 250 is not easily short-circuited with the first electrode sheet 100; on the other hand, the shielding area of ​​the first active material layer 120 is smaller, and the energy density of the electrochemical device provided with this electrode assembly 10 is higher.

[0143] In some embodiments, the first active material layer 120 further includes a seventh groove 124 extending from the bottom wall of the sixth groove 123 to the first surface 111 , and the projection of the second electrode tab 250 along the thickness direction of the first current collector 110 is located in the seventh groove 124 .

[0144] By further providing a seventh groove 124 in the first active material layer 120 that passes through the bottom wall of the sixth groove 123 to the first surface 111, the projection of the second electrode tab 250 along the thickness direction of the first current collector 110 is located in the seventh groove 124, so that the first electrode sheet 100 and the second electrode sheet 200 are stacked, and when the thickness of the second electrode tab 250 is greater than the thickness of the third active material layer 220, the seventh groove 124 can be used to accommodate part of the second electrode tab 250, thereby making the overall thickness of the electrode assembly 10 smaller and the energy density of the electrochemical device provided with this electrode assembly 10 higher.

[0145] In some embodiments, the width of the seventh groove 124 along the length direction of the first current collector 110 is W14, satisfying 4 mm ≤ W14 ≤ 16 mm. For example, W14 can be 4 mm, 10 mm, or 16 mm. The depth of the seventh groove 124 along the thickness direction of the first current collector 110 is H13, satisfying 10 μm ≤ H13 ≤ 60 μm. For example, H13 can be 10 μm, 30 μm, or 60 μm.

[0146] By ensuring that the width W14 of the seventh groove 124 along the length direction of the first current collector 110 satisfies 4mm≤W14≤16mm and the depth H13 of the seventh groove 124 along the thickness direction of the first current collector 110 satisfies 10μm≤H13≤60μm, on the one hand, the seventh groove 124 has sufficient space to accommodate the second electrode tab 250; on the other hand, the volume loss of the first active material layer 120 can be reduced, and the energy density of the electrochemical device provided with this electrode assembly 10 is higher.

[0147] See FIG. 6 , which is a schematic cross-sectional view of an electrode assembly according to some other embodiments of the present application.

[0148] In other embodiments, the fifth groove 223 may include a first sub-groove 2231 and a second sub-groove 2232 extending from the bottom wall of the first sub-groove 2231 to the third surface 211. The third surface 211 of the second single-sided hollow foil region 213 is exposed in the second sub-groove 2232. The second electrode tab 250 is accommodated in the second sub-groove 2232, and the third insulating adhesive layer 260 is accommodated in the first sub-groove 2231. This can reduce the overall thickness of the second electrode sheet 200, thereby increasing the energy density of the electrochemical device provided with the electrode assembly 10.

[0149] In some embodiments, the first electrode 100 is a negative electrode, and the second electrode 200 is a positive electrode.

[0150] Since the first electrode 100 is a negative electrode and the second electrode 200 is a positive electrode, by ensuring that the projection of the second insulating adhesive layer 240 covers the first groove 121 when viewed along the thickness direction of the second current collector 210, and ensuring that the projection of the third insulating adhesive layer 260 covers the sixth groove 123 when viewed along the thickness direction of the first current collector 110, the area of ​​the blocked portion of the third active material layer 220 can be larger than the area of ​​the blocked portion of the first active material layer 120, thereby reducing the possibility of metal ion precipitation in the electrochemical device.

[0151] See FIG. 7 , which is a schematic cross-sectional view of an electrode assembly provided in some other embodiments of the present application.

[0152] The present embodiment provides an electrode assembly 10, comprising a first electrode sheet 100 and a second electrode sheet 200 of opposite polarity. The first electrode sheet 100 comprises a first current collector 110, a first active material layer 120, a second active material layer 130, a first electrode tab 140, a first insulating adhesive layer 150, and a fourth insulating adhesive layer 160. The first active material layer 120 and the second active material layer 130 are disposed on the two surfaces of the first current collector 110, respectively. The first active material layer 120 is provided with a first groove 121 and a second groove 122. The first electrode tab 140 is accommodated in the second groove 122 and welded to the first single-sided hollow foil area 113. The first insulating adhesive layer 150 is accommodated in the first groove 121 and covers the weld between the first electrode tab 140 and the first single-sided hollow foil area 113. The first active material layer 120 is also provided with a sixth groove 123 and a seventh groove 124. The fourth insulating adhesive layer 160 is accommodated in the sixth groove 123.

[0153] The second electrode sheet 200 includes a second current collector 210, a third active material layer 220, a fourth active material layer 230, a second electrode tab 250, a second insulating adhesive layer 240, and a third insulating adhesive layer 260. The third active material layer 220 and the fourth active material layer 230 are disposed on both surfaces of the second current collector 210, respectively. The third active material layer 220 is provided with a fifth groove 223. The second electrode tab 250 is accommodated in the fifth groove 223 and welded to the second single-sided hollow foil region 213. The third insulating adhesive layer 260 covers the weld between the second electrode tab 250 and the second single-sided hollow foil region 213. When viewed along the thickness direction of the second current collector 210, the projection of the second insulating adhesive layer 240 covers the first groove 121.

[0154] An embodiment of the present application provides an electrochemical device, comprising an electrode assembly 10 according to any of the above solutions.

[0155] An embodiment of the present application provides an electrical device, comprising an electrochemical device according to any of the above schemes, and the electrochemical device is used to provide electrical energy to the electrical device.

[0156] The electrical equipment may be any of the aforementioned equipment or systems using electrochemical devices.

[0157] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0158] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Persons skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. An electrode assembly, characterized in that, It includes a first pole piece and a second pole piece with opposite polarities. The first pole piece includes: A first current collector having a first surface and a second surface disposed opposite to each other; A first active material layer disposed on the first surface. The first active material layer is provided with a first groove and a second groove penetrating the bottom wall of the first groove to the first surface. The first current collector includes a first single-sided empty foil area, and the first surface of the first single-sided empty foil area is exposed in the second groove; A second active material layer disposed on the second surface, and the second surface of the first single-sided empty foil area is covered by the second active material layer; A first tab accommodated in the second groove and welded to the first single-sided empty foil area to form a welded joint; A first insulating adhesive layer accommodated in the first groove and covering the welded joint between the first tab and the first single-sided empty foil area. The projection of the first insulating adhesive layer in the thickness direction of the first current collector is located in the first groove.

2. The electrode assembly according to claim 1, characterized in that Along the length direction of the first current collector, the width of the first groove is W11, and the width of the first insulating adhesive layer is M1, satisfying M1≤W11, and 7mm≤W11≤17mm, 5mm≤M1≤15mm; along the thickness direction of the first current collector, the depth of the first groove is H11, and the thickness of the first insulating adhesive layer is N1, satisfying N1≤H11, and 5μm≤H11≤55μm, 5μm≤N1≤20μm.

3. The electrode assembly according to claim 1, characterized in that, Along the length direction of the first current collector, the width of the second groove is W12, and the width of the first tab is P1, satisfying 5mm≤W12≤15mm, 3mm≤P1≤13mm.

4. The electrode assembly according to claim 1, wherein, The second pole piece includes: A second current collector having a third surface and a fourth surface disposed opposite to each other. The third surface faces the first active material layer, and the fourth surface faces away from the first active material layer; A third active material layer disposed on the third surface; A fourth active material layer disposed on the fourth surface; A second insulating adhesive layer disposed on the side of the third active material layer away from the second current collector. When observed in the thickness direction of the second current collector, the projection of the second insulating adhesive layer covers the first groove.

5. The electrode assembly according to claim 4, wherein, The third active material layer is provided with a third groove, and the second insulating adhesive layer is accommodated in the third groove. The projection of the second insulating adhesive layer in the thickness direction of the second current collector is located in the third groove.

6. The electrode assembly according to claim 5, wherein, Along the length direction of the second current collector, the width of the third groove is W21, and the width of the second insulating adhesive layer is M2, satisfying M2≤W21, and 17mm≤W21≤27mm, 15mm≤M2≤25mm; along the thickness direction of the second current collector, the depth of the third groove is H21, and the thickness of the second insulating adhesive layer is N2, satisfying N2≤H21, and 5μm≤H21≤55μm, 5μm≤N2≤20μm.

7. The electrode assembly according to claim 5, characterized in that, The third active material layer is further provided with a fourth groove penetrating through the bottom wall of the third groove to the third surface, and the projection of the first tab along the thickness direction of the second current collector is located in the fourth groove. Along the length direction of the second current collector, the width of the fourth groove is W22, satisfying 4 mm ≤ W22 ≤ 16 mm; along the thickness direction of the second current collector, the depth of the fourth groove is H22, satisfying 10 μm ≤ H22 ≤ 60 μm.

8. The electrode assembly according to claim 4, wherein The third active material layer is provided with a fifth groove penetrating through the third active material layer to the third surface. The second current collector includes a second single-sided empty foil area, and the third surface of the second single-sided empty foil area is exposed in the fifth groove, and the second single-sided empty foil area is covered by the fourth active material layer on the fourth surface. The second electrode plate further includes: A second tab, accommodated in the fifth groove and welded to the second single-sided empty foil area to form a welded joint. A third insulating adhesive layer, covering the welded joint between the second tab and the second single-sided empty foil area.

9. The electrode assembly according to claim 8, wherein, Along the length direction of the second current collector, the width of the fifth groove is W23, and the width of the second tab is P2, satisfying 5 mm ≤ W23 ≤ 15 mm, 3 mm ≤ P2 ≤ 13 mm.

10. The electrode assembly according to claim 8, wherein, Along the length direction of the second current collector, the width of the third insulating adhesive layer is M3, satisfying 15 mm ≤ M3 ≤ 25 mm; along the thickness direction of the second current collector, the thickness of the third insulating adhesive layer is N3, 5 μm ≤ N3 ≤ 20 μm.

11. The electrode assembly according to claim 8, characterized in that, The first active material layer is further provided with a sixth groove. When observed along the thickness direction of the first current collector, the projection of the third insulating adhesive layer covers the sixth groove. The first electrode plate further includes: A fourth insulating adhesive layer, accommodated in the sixth groove.

12. The electrode assembly according to claim 11, characterized in that, Along the length direction of the first current collector, the width of the sixth groove is greater than or equal to the width of the fourth insulating adhesive layer; along the thickness direction of the first current collector, the depth of the sixth groove is greater than or equal to the thickness of the fourth insulating adhesive layer.

13. The electrode assembly according to claim 12, characterized in that, Along the length direction of the first current collector, the width of the sixth groove is W13, and the width of the fourth insulating adhesive layer is M4, satisfying 7 mm ≤ W13 ≤ 17 mm, 5 mm ≤ M4 ≤ 15 mm; along the thickness direction of the first current collector, the depth of the sixth groove is H12, and the thickness of the fourth insulating adhesive layer is N4, satisfying 5 μm ≤ H12 ≤ 55 μm, 5 μm ≤ N4 ≤ 20 μm.

14. The electrode assembly according to claim 12, wherein, The first active material layer is further provided with a seventh groove penetrating through the bottom wall of the sixth groove to the first surface, and the projection of the second tab along the thickness direction of the first current collector is located in the seventh groove. Along the length direction of the first current collector, the width of the seventh groove is W14, satisfying 4 mm ≤ W14 ≤ 16 mm; along the thickness direction of the first current collector, the depth of the seventh groove is H13, satisfying 10 μm ≤ H13 ≤ 60 μm.

15. The electrode assembly according to claim 1, characterized in that, The first electrode plate is a negative electrode plate, and the second electrode plate is a positive electrode plate.

16. The electrode assembly according to claim 1, characterized in that, The first tab is formed on the first current collector by laser welding, and the second tab is formed on the second current collector by laser welding.

17. The electrode assembly according to claim 16, wherein The first tab is a negative electrode tab, the second tab is a positive electrode tab, the fifth groove includes a first sub-groove and a second sub-groove, and the projection of the second sub-groove in the thickness direction of the second current collector is located within the first sub-groove. Along the width direction of the first tab, the distance between one side of the first tab and the corresponding groove wall of the first groove is a, and along the width direction of the second tab, the distance between one side of the second tab and the corresponding groove wall of the second sub-groove is b, where a and b satisfy: b < a.

18. The electrode assembly according to claim 17, wherein, a ≥ 0.2 mm, b ≥ 0.2 mm.

19. An electrochemical device, characterized in that, It includes the electrode assembly according to any one of claims 1 to 18.

20. An electrical device, characterized in that, It includes the electrochemical device according to claim 19, and the electrochemical device is used for providing electrical energy.

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