Electrochemical device and electric device

Abstract

The application relates to the battery technical field and discloses an electrochemical device, a battery module and a power utilization device. The electrochemical device comprises an electrode assembly and an insulating piece. The electrode assembly comprises a first pole piece, a second pole piece and a separator. The first pole piece comprises a first current collector and a first active material layer. The first active material layer is provided with a first connecting edge. A first surface of the first pole piece is provided with a first empty foil area. The insulating piece covers part of the first active material layer and part of the first empty foil area. Through the above structure, the insulating piece completely and reliably covers part of the first connecting edge, reduces the coverage area of the base on the first active material layer, effectively increases the effective area of the first active material layer in the first pole piece, and thus improves the energy density of the electrochemical device.

Description

TECHNICAL FIELD

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

[0002] The electrochemical device is a device which converts external energy into electric energy and stores it inside, so as to supply power to external equipment (such as portable electronic equipment) at the required time. Generally, the electrochemical device includes a shell, an electrode assembly accommodated in the shell, an electrolyte, and a tab connected with the electrode assembly. The electrode assembly includes a first electrode sheet, a second electrode sheet, and a separator arranged between the first electrode sheet and the second electrode sheet.

[0003] At present, in order to ensure that the electrochemical device has high energy density, manufacturers generally set an active material layer on the inner surface of the outermost collector, and do not set an active material layer on the outer surface of the outermost collector to form an empty foil area, so as to avoid the waste of cost and the reduction of energy density caused by the active material on the outer surface not participating in the reaction. For the convenience of description, the electrode sheet at the end of the outermost electrode assembly is defined as the first electrode sheet, and the other electrode sheet is defined as the second electrode sheet.

[0004] For safety, an insulating film is generally arranged between the active material layer and the empty foil area to prevent the first electrode sheet and the second electrode sheet from being short-circuited due to contact between them, thereby affecting the safety of the electrochemical device. The insulating film covers part of the active material layer, thereby reducing the capacity and energy density of the electrochemical device. SUMMARY

[0005] The present application aims to provide an electrochemical device and a power utilization device, which can reduce the coverage area of the original insulating part on the first active material layer, effectively increase the effective area of the first active material layer in the first electrode sheet, and thereby improve the energy density of the electrochemical device.

[0006] In order to solve the technical problems, the present application adopts the following technical solutions:

[0007] An electrochemical device includes an electrode assembly and an insulating member, the electrode assembly is wound by a first electrode tab, a second electrode tab and a separator film arranged in layers, the separator film is arranged between the first electrode tab and the second electrode tab, the first electrode tab includes a first current collector and a first active material layer, a first surface of the first current collector includes a first coated area coated with the first active material layer and a first uncoated area without the first active material layer in a first direction, wherein the first surface is arranged away from a winding center of the electrode assembly, and the first direction is a direction in which a long side of the first electrode tab extends when the first electrode tab is unfolded; the first active material layer has a first side edge and a second side edge arranged oppositely in the first direction, and a third side edge and a fourth side edge arranged oppositely in a second direction, and the first side edge and the third side edge are connected by a first connecting edge, wherein the second direction is a direction in which a wide side of the first electrode tab extends when the first electrode tab is unfolded. The electrochemical device further includes an insulating member, the insulating member includes a base and a first extension, the base has a first end and a second end arranged oppositely in the first direction, the first end is arranged at the first uncoated area, the second end is arranged at the first active material layer, and the base covers the first side edge; the first extension extends from the second end in a direction away from the first end, and the first extension at least partially covers the first connecting edge, the insulating member completely covers the first connecting edge and the first side edge, and in the first direction, a maximum distance from a side of the first extension away from the second end to the first side edge is greater than a maximum distance from the second end to the first side edge.

[0008] In some embodiments, in the second direction (or in a direction in which the third side edge points to the fourth side edge), a distance from a side of the first extension away from the second end to the first side edge gradually decreases (or an outer contour of the first extension gradually shrinks).

[0009] In some embodiments, the first connecting edge has an arc shape, and a radius R1 of the first connecting edge satisfies: R1≥1mm.

[0010] In some embodiments, in the first direction, a distance D1 from a side of the first extension away from the first end to the first side edge satisfies: 1.2mm≤D1≤6mm.

[0011] In some embodiments, the insulating member is provided with a second connecting edge connecting the first extension and the base, and a minimum distance D2 between the second connecting edge and the first connecting edge satisfies: 0.2mm≤D2≤2mm.

[0012] In some embodiments, a minimum distance D3 between the second end and the first side edge satisfies: 0.2mm≤D3≤2mm.

[0013] In some embodiments, the first side edge and the fourth side edge are connected by a third connecting edge, the third connecting edge is arc-shaped, and a radius R2 of the third connecting edge satisfies R2≥1 mm.

[0014] In some embodiments, the insulating member further comprises a second extending portion and a fourth connecting edge, the second extending portion extends from the second end in a direction away from the first end, the fourth connecting edge connects the second extending portion and the base portion, the second extending portion at least partially covers the third connecting edge, the insulating member completely covers the first side edge and the third connecting edge, and in the first direction, a maximum distance from a side of the second extending portion away from the second end to the first side edge is greater than a maximum distance from the second end to the first side edge.

[0015] In some embodiments, in the second direction (or in a direction from the fourth side edge to the third side edge), a distance from a side of the second extending portion away from the second end to the first side edge gradually decreases (or an outer contour of the second extending portion gradually shrinks).

[0016] In some embodiments, in the first direction, a distance D4 from a side of the second extending portion away from the first end to the first side edge satisfies 1.2 mm≤D4≤6 mm, and a minimum distance D5 between the fourth connecting edge and the third connecting edge satisfies D5≥0.2 mm.

[0017] In some embodiments, the first pole piece is a cathode pole piece, and the second pole piece is an anode pole piece; a second tail end of the second pole piece is located between the second end and the first end of the base portion, the first pole piece provided with the first empty foil area is wound outside the second pole piece, and in the winding direction of the electrode assembly, the second tail end of the second pole piece protrudes from the first tail end of the first pole piece, wherein the first tail end and the second tail end are respectively the first pole piece and the second pole piece at the winding end of the electrode assembly.

[0018] The application also provides another embodiment of a power utilization device comprising the above-mentioned electrochemical device, and the electrochemical device is used to provide electric energy for the power utilization device.

[0019] Compared with the electrochemical devices on the market, the electrochemical device of the embodiments of the application has the beneficial effects that: through the above structure, the insulating member completely and reliably covers the first connecting edge while reducing the coverage area of the base portion on the first active material layer, effectively increasing the effective area of the first active material layer in the first pole piece, thereby improving the energy density of the electrochemical device. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained from the structures shown in the drawings without creative labor.

[0021] Figure 1 A perspective view of an electrochemical device according to an embodiment of the present application.

[0022] Figure 2 A perspective view of a first electrode sheet in an electrochemical device according to an embodiment of the present application.

[0023] Figure 3 A perspective view of a first surface of a first electrode sheet in an electrochemical device according to an embodiment of the present application.

[0024] Figure 4 A perspective view of another surface of a first electrode sheet in an electrochemical device according to an embodiment of the present application.

[0025] Figure 5 A perspective view of a second electrode sheet in an electrochemical device according to an embodiment of the present application.

[0026] Figure 6 A perspective view of another surface of a second electrode sheet in an electrochemical device according to an embodiment of the present application.

[0027] Figure 7 A perspective view of an insulating member in an electrochemical device according to an embodiment of the present application.

[0028] Figure 8 A partial enlarged view of a first electrode sheet in an electrochemical device according to an embodiment of the present application.

[0029] Figure 9 A perspective view of an insulating member in an electrochemical device according to another embodiment of the present application.

[0030] Figure 10 A perspective view of an insulating member in an electrochemical device according to still another embodiment of the present application.

[0031] Figure 11 A partial enlarged view of a first electrode sheet in an electrochemical device according to another embodiment of the present application.

[0032] Figure 12 A perspective view of an electrode assembly in an electrochemical device according to an embodiment of the present application.

[0033] Figure 13 A perspective view of an electrode assembly in an electrochemical device according to an embodiment of the present application. Figure 12 A partial enlarged view of part C. DETAILED DESCRIPTION

[0034] For the purpose of promoting the understanding of the present application, the present application will be described in further detail below in conjunction with the accompanying drawings and specific embodiments. It needs to be noted that when an element is described as "fixed", "disposed" or "connected" to another element, it can be directly on the other element or one or more intermediate elements can be present therebetween. When an element is described as "connected" to another element, it can be directly connected to the other element or one or more intermediate elements can be present therebetween. The terms "vertical", "horizontal", "left", "right", "inner", "outer" and similar expressions used in the present specification are for the purpose of illustration only.

[0035] In the present specification, the "mounting" includes welding, screwing, clamping, bonding and the like to fix or restrict an element or device to a specific position or place, and the element or device can be kept stationary or movable within a limited range in the specific position or place. The element or device fixed or restricted to the specific position or place can be disassembled or can not be disassembled, and the present application is not limited in the embodiments. In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0036] Please refer to Figure 1 , the electrochemical device 100 includes an electrode assembly 10, an insulating member 20, a case 30 and an electrolyte 40. The case 30 is provided with a receiving cavity, the electrolyte 40 is filled in the receiving cavity, the insulating member 20 is arranged inside the electrode assembly 10 and is received in the receiving cavity together with the electrode assembly 10, and the electrolyte 40 completely soaks the electrode assembly 10 and provides a liquid environment for the chemical reaction of the electrode assembly 10.

[0037] It is worth noting that the electrochemical device 100 can be a soft package battery, that is, the case 30 is made of a flexible material, for example, an aluminum plastic film or a steel plastic film, and the electrochemical device 100 can also be a hard shell battery, and the case 30 is made of a hard material, for example, an aluminum shell material, a steel shell material, a high-hardness plastic material or other metal materials.

[0038] The electrode assembly 10 comprises a first tab 11, a second tab 12 and a separator 13. The first tab 11 is provided with a first head end 11s and a first tail end 11w, and the second tab 12 is provided with a second head end 12s and a second tail end 12w. The first tab 11, the separator 13 and the second tab 12 are sequentially stacked and wound from the first head end 11s and the second head end 12s to form the electrode assembly 10. In the embodiment, the first tab 11 is a cathode tab, and the second tab 12 is an anode tab. After winding, the outermost tab is the first tab 11, and along the winding direction, the second head end 12s protrudes from the first head end 11s, and the second tail end 12w protrudes from the first tail end 11w. This ensures that the lithium cobaltate separated from the first tab 11 can be embedded in the second tab 12, preventing the lithium precipitation in the electrochemical device 100 and affecting the safety of the electrochemical device 100.

[0039] For the first tab 11 described above, refer to Figures 2 to 4 The direction in which the long side of the first tab 11 extends after being unfolded is defined as the first direction X, and the direction in which the short side of the first tab 11 extends after being unfolded is defined as the second direction Y. The first direction X and the second direction Y are perpendicular to each other. The first tab 11 comprises a first current collector 111, a first active material layer 112, a first insulating material layer 113 and a plurality of first tabs 114. The first active material layer 112 and the first insulating material layer 113 are coated on the surface of the first current collector 111. The first active material layer 112 chemically reacts with the second tab 12 through the electrolyte 40, and the first insulating material layer 113 separates the first tab 11 from the second tab 12 to reduce the risk of short circuit. The plurality of first tabs 114 are connected to the long side of the first tab 11, and the plurality of first tabs 114 are arranged at intervals along the first direction X, and each first tab 114 extends along the second direction Y.

[0040] The first current collector 111 is provided with a first surface 111a and a second surface 111b oppositely arranged, wherein the first surface 111a is away from the winding center of the electrode assembly 10, and the second surface 111b is close to the winding center of the electrode assembly 10. Along the first direction X, the first surface 111a of the first current collector 111 is sequentially and adjacently provided with a first coating area 1111 and a first empty foil area 1112, the first coating area 1111 is used for coating the first active material layer 112, and the first empty foil area 1112 is not processed. Along the second direction Y, the first surface 111a of the first current collector 111 is sequentially and adjacently provided with the first coating area 1111 and a second empty foil area 1113, and the second empty foil area 1113 is used for coating the first insulating material layer 113. Along the second direction Y, the second surface 111b of the first current collector 111 is sequentially and adjacently coated with the first active material layer 112 and the first insulating material layer 113. The first insulating material layer 113 can include some inorganic materials or insulating organic materials commonly used at present, and the inorganic materials can include aluminum oxide, magnesium oxide, zirconium oxide, etc. The first insulating material layer 113 can further include commonly used binders, such as polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride, polymethyl methacrylate, polyphenyl ether, polypropylene carbonate, polyethylene oxide and derivatives thereof, etc.

[0041] The first active material layer 112 coated on the first coating area 1111 is provided with a first side edge 1121, a second side edge 1122, a third side edge 1123, a fourth side edge 1124 and a first connecting edge 1125. The first side edge 1121 and the second side edge 1122 are oppositely arranged along the first direction X, the third side edge 1123 and the fourth side edge 1124 are oppositely arranged along the second direction Y, and the two ends of the first connecting edge 1125 are tangent to the first side edge 1121 and the third side edge 1123 respectively and are smoothly connected. The extension line of the first side edge 1121 intersects with the extension line of the third side edge 1123 at a point A, the shape of the first connecting edge 1125 is in the form of a circular arc, and the convex part of the circular arc tends to the point A, and the radius R1 of the first connecting edge 1125 satisfies: R1≥1mm. The extension line of the first side edge 1121, the extension line of the third side edge 1123 and the first connecting edge 1125 together enclose a first empty area 1114, and the first empty area 1114 is not coated with any coating.

[0042] In the embodiment, please refer to Figure 8 The measurement method of the radius R1 of the first connecting edge 1125 is that along the first direction X, there is an interface separation point P (i.e. the tangent point of the third side edge 1123 and the first connecting edge 1125) of the first insulating material layer 113 and the first active material layer 112, and the distance from the separation point P to the first side edge is the radius R1 of the first connecting edge 1125.

[0043] For the above-mentioned second tab 12, please refer to Figure 5 andFigure 6 The second tab sheet 12 includes a second current collector 121, a second active material layer 122, and a plurality of second tabs 123. The plurality of second tabs 123 are each connected to a long side of the second current collector 121, and are arranged at intervals in a direction in which the long side extends after being spread along the second tab sheet 12. The second current collector 121 is provided with a third surface 121a and a fourth surface 121b arranged opposite to each other, the third surface 121a being away from the winding center of the electrode assembly 10, and the fourth surface 121b being close to the winding center of the electrode assembly 10. The third surface 121a is coated with the second active material layer 122, and the fourth surface 121b is coated with the second active material layer 122, the fourth surface 121b being not coated with the second active material layer 122 close to the second first end 12s. The second active material layer 122 is configured to chemically react with the first active material layer 112.

[0044] When the first tab sheet 11, the second tab sheet 12, and the separator 13 are stacked and wound to form the electrode assembly 10, the plurality of first tabs 114 are sequentially stacked to form one electrode of the electrode assembly 10, and the plurality of second tabs 123 are sequentially stacked to form another electrode of the electrode assembly 10.

[0045] In some embodiments, the first tab sheet 11 is a cathode tab sheet, and the second tab sheet 12 is an anode tab sheet.

[0046] In some embodiments, the first current collector 111 is an aluminum foil, and the second current collector 121 is a copper foil.

[0047] In some embodiments, the first insulating material layer 113 can be an inorganic particle layer, such as a ceramic coating.

[0048] In some embodiments, the first tab 114 and the first current collector 111 are an integrally formed structure, i.e., the first tab 114 is formed by cutting the first current collector 111; and the second tab 123 and the second current collector 121 are an integrally formed structure, i.e., the second tab 123 is formed by cutting the second current collector 121. In other embodiments, the first tab 114 is welded or adhered to the first current collector 111; and the second tab 123 is welded or adhered to the second current collector 121.

[0049] For the above-mentioned insulating member 20, please refer to Figure 7The insulating piece 20 includes a base 21, a first extension 22, and a second connecting edge 24. In the first direction X, the base 21 is provided with a first end 211 and a second end 212, and the first end 211 is arranged at the first empty area 1112 and the second end 212 is arranged at the first active material layer 112, and the base 21 covers the first side edge 1121 of the first active material layer 112. The first extension 22 starts from the second end 212 and extends away from the first end 211, and the first extension 22 covers part of the first side edge 1121, part of the third side edge 1123, and the entire first connecting edge 1125 of the first active material layer 112. In an embodiment, the base 21 completely covers the first side edge 1121 of the first active material layer 112, and the first extension 22 at least partially covers the first connecting edge 1125. Generally, the thickness of the isolation film 13 is usually 4-5 microns, and the mechanical properties and density are relatively poor, while the thickness of the insulating piece 20 is 14-16 microns, and the mechanical properties and density are better. When the first extension 22 completely covers the first empty area 1114, it can prevent the aluminum-anode short-circuit reaction phenomenon of the first current collector 111 when the isolation film 13 between the first and second pole pieces 11 and 12 is damaged, thereby improving the safety performance of the electrochemical device 100. The second connecting edge 24 is used to smoothly connect the side of the first extension 22 away from the first end 211 to the second end 212, preventing the connection between the first extension 22 and the base 21 from having a sudden connection point, which can cause stress concentration at the sudden connection point, causing the insulating piece 20 to tear inward from the sudden connection point and damage the insulating piece 20, thereby affecting the safety performance of the electrochemical device 100. In the second direction Y (or in the direction of the third side edge 1123 of the first active material layer 112 pointing to the fourth side edge 1124), the distance from the side of the first extension 22 away from the second end 212 to the first side edge 1121 gradually decreases (or the outer contour of the first extension 22 gradually shrinks).

[0050] Please refer to Figure 8 In the first direction X, the distance D1 from the side of the first extension 22 of the insulating piece 20 away from the first end 211 to the first side edge 1121 of the first active material layer 112 satisfies: 1.2 mm≤D1≤6 mm. In the production process of the first pole piece 11, when the first active material layer 112 is coated on the first coating area 1111 of the first current collector 111, the radius R1 of the first connecting edge 1125 of the first active material layer 112 can only be controlled to be at least 1 mm due to the influence of the existing coating tool and coating process technology. In this embodiment, in order to ensure that the first extension 22 of the insulating piece 20 can completely and reliably cover the first empty area 1114, the distance D1 from the side of the first extension 22 of the insulating piece 20 away from the first end 211 to the first side edge 1121 of the first active material layer 112 is at least greater than or equal to 1.2 mm.

[0051] In the present embodiment, the distance D1 between the first extending portion 22 of the insulating member 20 away from the first end 211 to the first side edge 1121 of the first active material layer 112 is measured as follows: the first extending portion 22 of the insulating member 20 away from the first end 211 is extended along the second direction Y, the first side edge 1121 is extended along the second direction Y, and the distance between the two extended lines along the first direction X is the distance D1. The other distances in the present disclosure can also be measured in a similar manner, such as the distance D2.

[0052] The minimum distance D2 between the second connecting edge 24 of the insulating member 20 and the first connecting edge 1125 of the first active material layer 112 satisfies: 0.2 millimeter ≤ D2 ≤ 2 millimeter. In the process of arranging the insulating member 20 on the first pole piece 11, in order to ensure that the insulating member 20 can completely and reliably cover the first vacant area 1114, in combination with the existing process technical tolerance, when the minimum distance D2 between the second connecting edge 24 of the insulating member 20 and the first connecting edge 1125 of the first active material layer 112 is at least greater than or equal to 0.2 millimeter, the insulating member 20 can be reliably attached to the first active material layer 112.

[0053] Along the first direction X, the minimum distance D3 between the second end 212 of the insulating member 20 and the first side edge 1121 of the first active material layer 112 satisfies: 0.2 millimeter ≤ D3 ≤ 2 millimeter. In the process of arranging the insulating member 20 on the first pole piece 11, in order to ensure that the insulating member 20 can completely and reliably cover the first side edge 1121 of the first active material layer 112, in combination with the existing process technical tolerance, when the minimum distance D2 between the second end 212 of the insulating member 20 and the first side edge 1121 of the first active material layer 112 is at least greater than or equal to 0.2 millimeter, the insulating member 20 can be reliably attached to the first active material layer 112. At the same time, the minimum distance D2 between the second connecting edge 24 of the insulating member 20 and the first connecting edge 1125 of the first active material layer 112 and the minimum distance D3 between the second end 212 of the insulating member 20 and the first side edge 1121 of the first active material layer 112 also need to be controlled within a reasonable range. When the minimum distance D2 and the minimum distance D3 are too large, the area of the insulating member 20 covering the first active material layer 112 is too large, thereby affecting the effective reaction area between the first pole piece 11 and the second pole piece 12, and reducing the capacity and energy density of the electrochemical device 100.

[0054] In the embodiment, the second connecting edge 24 of the insulating piece 20 is in the shape of a circular arc, and the convex direction of the arc of the second connecting edge 24 is consistent with the convex direction of the arc of the first connecting edge 1125, that is, the center of the circle where the first connecting edge 1125 is located coincides with the center of the circle where the second connecting edge 24 is located, and the second connecting edge 24 and the first connecting edge 1125 form a ring structure. In the ring structure, the distance between the first connecting edge 1125 and the second connecting edge 24 is consistent, so that the insulating piece 20 can completely and reliably cover the first vacancy area 1114 while covering the smallest area of the first active material layer 112, which is beneficial to increase the capacity of the electrochemical device 100 and thus improve the energy density of the electrochemical device 100.

[0055] In other embodiments, referring to Figures 9 to 10 , the second connecting edge 24 of the insulating piece 20 can have other shapes, as long as the first extending portion 22 of the insulating piece 20 can completely and reliably cover the first vacancy area 1114, for example, a circular arc shape, in which the convex part of the arc is arranged opposite to the convex part of the arc of the first connecting edge 1125, or a straight line type, in which the straight line directly connects the first extending portion 22 and the second end 212.

[0056] In some embodiments, the first extending portion 22 of the insulating piece 20 covers part of the first connecting edge 1125, and the base 21 of the insulating piece 20 covers the remaining part of the first connecting edge 1125 and the entire first side edge 1121.

[0057] In some embodiments, referring to Figure 11 , the first active material layer 112 coated on the first coating area 1111 further includes a third connecting edge 1126, both ends of the third connecting edge 1126 are tangent to the first side edge 1121 and the fourth side edge 1124 respectively and are smoothly connected. The extension line of the first side edge 1121 intersects with the extension line of the fourth side edge 1124 at point B, the third connecting edge 1126 is in the shape of a circular arc, and the convex part of the circular arc tends to point B, and the radius R2 of the third connecting edge 1126 satisfies: R2≥1 millimeter. The extension line of the first side edge 1121, the extension line of the fourth side edge 1124 and the third connecting edge 1126 together enclose a second vacancy area 1115, and the second vacancy area 1115 is not coated with any coating.

[0058] The insulating piece 20 further comprises a second extending portion 23 and a fourth connecting edge 25. The second extending portion 23 starts from the second end 212 of the base portion 21 and extends away from the first end 211 of the base portion 21. The second extending portion 23 covers part of the first side edge 1121, part of the fourth side edge 1124 and the whole third connecting edge 1126 of the first active material layer 112, i.e. the second extending portion 23 completely covers the second vacancy area 1115. In this way, when the isolation film 13 between the first electrode tab 11 and the second electrode tab 12 is damaged, the first current collector 111 will not be subjected to anode reaction, thereby improving the safety performance of the electrochemical device 100. The second extending portion 23 can also partially cover the third connecting edge 1126. The base portion 21 completely covers the first side edge 1121 and part of the third connecting edge 1126, i.e. the base portion 21 and the second extending portion 23 jointly cover the second vacancy area 1115. The fourth connecting edge 25 is used to smoothly connect the side of the second extending portion 23 away from the first end 211 to the second end 212, so as to prevent the connection between the second extending portion 23 and the base portion 21 from having a sudden connection point. The insulating piece 20 is prone to stress concentration at the sudden connection point, and the insulating piece 20 is torn inward from the sudden connection point, which causes damage to the insulating piece 20 and affects the safety performance of the electrochemical device 100. Along the second direction Y (or, along the direction in which the fourth side edge 1124 of the first active material layer 112 points to the third side edge 1123), the distance from the side of the second extending portion 23 away from the second end 212 to the first side edge 1121 gradually decreases (or the outer contour of the second extending portion 23 gradually shrinks). Along the first direction X, the maximum distance from the side of the second extending portion 23 away from the second end 212 to the first side edge 1121 is greater than the maximum distance from the second end 212 to the first side edge 1121.

[0059] Along the first direction X, the distance D4 from the side of the second extending portion 23 of the insulating piece 20 away from the first end 211 to the first side edge 1121 of the first active material layer 112 satisfies: 1.2 mm≤D4≤6 mm.

[0060] The minimum distance D5 between the fourth connecting edge 25 of the insulating piece 20 and the third connecting edge 1126 of the first active material layer 112 satisfies: 0.2 mm≤D5≤2 mm.

[0061] It is worth mentioning that in some embodiments, the coverage of the first extension 22 and the base 21 on the first side edge 1121 and the first connecting edge 1125 can be adjusted according to actual needs, for example, the first extension 22 partially covers the first connecting edge 1125, and the base 21 covers the remaining first connecting edge 1125 and the first side edge 1121, or the base 21 covers part of the first side edge 1121, and the first extension 22 covers the remaining first side edge 1121 and the first connecting edge 1125, or the first extension 22 completely covers the first connecting edge 1125, and the base 21 completely covers the first side edge 1121, and the like, as long as the base 21 and the first extension 22 cooperate to completely cover the first vacancy 1114. Similarly, the second extension 23 and the base 21 also apply to the above coverage rules, as long as the base 21 and the second extension 23 cooperate to completely cover the second vacancy 1115.

[0062] In order to facilitate the reader to better understand the technical scheme of the present application, the first tab 11, the second tab 12 and the separator 13 (not shown in the figure) in the electrode assembly 10 are simplified, please refer to Figure 12 and Figure 13 In the present embodiment, the first active material layer 112 is lithium cobaltate, and the second active material layer 122 is graphite. When the first tab 11, the second tab 12 and the separator 13 are sequentially stacked and wound to form the electrode assembly 10, the second tail end 12w of the second tab 12 ends between the second end 212 and the first end 211 of the base 21 in the insulating piece 20. Preferably, the second tail end 12w of the second tab 12 ends between the second end 212 of the base 21 and the first side edge 1121 of the first active material layer 112, which can reduce the graphite coating in the second tab 12 that does not participate in the chemical reaction, reduce the manufacturing cost, improve the reaction rate between the lithium cobaltate in the first tab 11 and the graphite in the second tab 12, and ensure that the first tab 11 with the first vacancy 1112 continues to be wound outside the second tab 12, and the second tail end 12w of the second tab 12 protrudes from the first tail end 11w of the first tab 11 along the winding direction of the electrode assembly 10, so as to ensure that the second tab 12 has sufficient graphite coating for the lithium cobaltate in the first tab 11 to be embedded, reduce the probability of lithium precipitation phenomenon of the electrode assembly 10, and improve the safety of the electrochemical device 100.

[0063] The beneficial effect of the electrochemical device 100 in the embodiment of the present application is that the electrochemical device 100 comprises the electrode assembly 10 and the insulating piece 20, the electrode assembly 10 is wound by the first electrode tab 11, the second electrode tab 12 and the separator 13, the first electrode tab 11 comprises the first current collector 111 and the first active material layer 112, the first surface 111a of the first current collector 111 is provided with the first coating area 1111 and the first empty foil area 1112, the first active material layer 112 is arranged on the first coating area 1111, the first active material layer 112 has the first side edge 1121 and the second side edge 1122 arranged oppositely along the first direction X, and the third side edge 1123 and the fourth side edge 1124 arranged oppositely along the second direction Y, and the first side edge 1121 and the third side edge 1123 are connected by the first connecting edge 1125; the insulating piece 20 comprises the base 21 and the first extension 22, along the first direction X, the base 21 is provided with the first end 211 and the second end 212, the base 21 of the insulating piece 20 covers the first side edge 1121 of the first active material layer 112, the first extension 22 of the insulating piece 20 covers the first connecting edge 1125, along the direction of the third side edge 1123 pointing to the fourth side edge 1124, the outer contour of the first extension 22 gradually shrinks, wherein the first direction X is the direction of the long side extension of the first electrode tab 11 after being unfolded, and the second direction Y is the direction of the wide side extension of the first electrode tab 11 after being unfolded. Through the above structure, the insulating piece 20 completely and reliably covers the first connecting edge 1125 while reducing the coverage area of the base 21 on the first active material layer 112, effectively increasing the effective area of the first active material layer 112 in the first electrode tab 11, thereby improving the energy density of the electrochemical device 100.

[0064] Based on the same inventive concept, the embodiment of the present application also provides a power-using device comprising the electrochemical device 100, for the specific structure and function of the electrochemical device 100, please refer to the above embodiment, which will not be described here. The power-using device can be a mobile phone, a tablet computer, a computer, a drone or other power-using devices that need to be driven by electricity.

[0065] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above, which are not provided in detail for the sake of simplicity; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrochemical device comprising an electrode assembly, said electrode assembly being formed by winding together a first electrode, a second electrode, and a separator, wherein the separator is disposed between the first electrode and the second electrode, characterized in that, The first electrode includes a first current collector and a first active material layer. The first surface of the first current collector includes a first coating area coated with the first active material layer and a first empty foil area not coated with the first active material layer along a first direction. The first surface is disposed away from the winding center of the electrode assembly. The first direction is the direction in which the long side of the first electrode extends after it is unfolded. The first active material layer has a first side and a second side disposed opposite to each other along the first direction, and a third side and a fourth side disposed opposite to each other along the second direction. The first side and the third side are connected by a first connecting edge. The second direction is the direction in which the wide side of the first electrode extends after it is unfolded. The electrochemical device further includes an insulating component, which includes a base and a first extension. The base has a first end and a second end disposed opposite to each other along the first direction. The first end is disposed in the first empty foil region, and the second end is disposed in the first active material layer. The base covers the first side. The first extension extends from the second end in a direction away from the first end, and the first extension at least partially covers the first connecting edge. The insulating member covers the first side and the first connecting edge. Along the first direction, the maximum distance from the side of the first extension away from the second end to the first side is greater than the maximum distance from the second end to the first side.

2. The electrochemical device according to claim 1, characterized in that, Along the second direction, the distance from the side of the first extension away from the second end to the first side gradually decreases.

3. The electrochemical device according to claim 1, characterized in that, The first connecting edge is arc-shaped, and the radius R1 of the first connecting edge satisfies: R1≥1 mm.

4. The electrochemical device according to claim 1 or 2, characterized in that, Along the first direction, the distance D1 from the side of the first extension away from the first end to the first side edge satisfies: 1.2 mm ≤ D1 ≤ 6 mm.

5. The electrochemical device according to claim 1, characterized in that, The insulating component is provided with a second connecting edge, which connects the first extension to the base. The minimum distance D2 between the second connecting edge and the first connecting edge satisfies: 0.2 mm ≤ D2 ≤ 2 mm.

6. The electrochemical device according to claim 1, characterized in that, The minimum distance D3 between the second end and the first side satisfies: 0.2 mm ≤ D3 ≤ 2 mm.

7. The electrochemical device according to claim 1, characterized in that, The first side and the fourth side are connected by a third connecting edge, which is arc-shaped and has a radius R2 that satisfies: R2≥1 mm.

8. The electrochemical device according to claim 7, characterized in that, The insulating member further includes a second extension and a fourth connecting edge. The second extension extends from the second end in a direction away from the first end. The fourth connecting edge connects the second extension and the base. The second extension at least partially covers the third connecting edge. The insulating member completely covers the first side and the third connecting edge. Along the first direction, the maximum distance from the side of the second extension away from the second end to the first side is greater than the maximum distance from the second end to the first side.

9. The electrochemical device according to claim 8, characterized in that, Along the second direction, the distance from the side of the second extension away from the second end to the first side gradually decreases.

10. The electrochemical device according to claim 8, characterized in that, Along the first direction, the distance D4 from the side of the second extension away from the first end to the first side edge satisfies: 1.2 mm ≤ D4 ≤ 6 mm; The minimum distance D5 between the fourth connecting edge and the third connecting edge satisfies: 0.2 mm ≤ D5 ≤ 2 mm.

11. The electrochemical device according to claim 1, characterized in that, The first electrode is a cathode electrode, and the second electrode is an anode electrode; The second tail end of the second electrode is located between the second end and the first end of the base. The first electrode with the first empty foil area is wound around the outside of the second electrode and, along the winding direction of the electrode assembly, the second tail end of the second electrode protrudes from the first tail end of the first electrode. The first tail end and the second tail end are respectively the winding ends of the first electrode and the second electrode in the electrode assembly.

12. An electrical appliance, characterized in that, The device includes an electrochemical device as described in any one of claims 1 to 11, wherein the electrochemical device is used to provide electrical energy to the electrical device.

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