Winding type electrode assembly, battery monomer, battery and electric device

Abstract

The utility model relates to a winding type electrode assembly, which is characterized in that a separator can increase the strength of a pole piece so as to play a role in preventing an inner-layer pole piece from being broken or falling powder to a certain extent. Moreover, the adhesion layer of the separator is only distributed in a local area on one side of the isolation layer, so that the contact area with the active material layer of the pole piece is small, and the pole piece is not easy to pollute and damage. Furthermore, the isolation layer can prevent the lithium ions from flowing between the anode pole piece and the cathode pole piece, so that the lithium ions flowing from the cathode pole piece to the anode pole piece are obviously reduced. Even if an active material layer on the anode pole piece falls off and lithium intercalation sites are reduced due to bending, the number of free lithium ions on one side of the anode pole piece can be effectively reduced. Therefore, the number of lithium ions capable of obtaining electrons and forming the lithium elementary substance is remarkably reduced, so that the lithium precipitation phenomenon can be effectively inhibited. In addition, the utility model also provides a battery monomer, a battery and an electric device.

Description

Technical Field

[0001] The utility model relates to the technical field of new energy, and in particular to a wound electrode assembly, a battery cell, a battery and an electrical device. Background Art

[0002] The winding process is a common method for manufacturing lithium-ion battery cells. By winding stacked anode and cathode sheets, along with a separator, a wound electrode assembly with a relatively large battery capacity is produced. Because the angle of the wound electrode assembly decreases as it moves toward the inner side, the coating on the inner electrode sheet may peel off or even break, leading to problems such as lithium deposition. Lithium deposition can adversely affect various parameters of lithium batteries, including charging efficiency and energy density. Severe lithium deposition can also puncture the separator, causing a short circuit within the battery and posing a serious safety hazard. Utility Model Content

[0003] Based on this, it is necessary to provide a wound electrode assembly that can effectively suppress lithium plating to address the above-mentioned problems.

[0004] A wound electrode assembly comprises a cathode electrode sheet, an anode electrode sheet and a diaphragm, wherein the cathode electrode sheet, the anode electrode sheet and the diaphragm are wound and pressed to form a flat structure, so that the wound electrode assembly has a straight area and bending areas located at both ends of the straight area. The wound electrode assembly also includes an isolating member, and the isolating member includes an isolating layer and an adhesion layer distributed in a local area on one side of the isolating layer. The front preset layer of the wound electrode assembly from the inside to the outside is covered with the isolating member on at least one side of the anode electrode sheet and / or the cathode electrode sheet to isolate the two adjacent layers of the anode electrode sheet and the cathode electrode sheet. The isolating member passes around the bending area and extends to the straight area, and is bonded and fixed by the adhesion layer.

[0005] In one embodiment, the adhesion layer is distributed at both ends of the isolation layer along the winding direction of the wound electrode assembly, and the adhesion layer is bonded to the cathode electrode sheet and / or the anode electrode sheet in the straight section of the straight area.

[0006] In one embodiment, the adhesive layer is in the shape of an elongated strip and extends along the axial direction of the wound electrode assembly; or, the adhesive layer includes a plurality of adhesive blocks, and the plurality of adhesive blocks are spaced apart along the axial direction of the wound electrode assembly.

[0007] In one embodiment, the insulating member is covered on both opposite sides of the cathode electrode sheet or the anode electrode sheet, and in the winding direction of the wound electrode assembly, the distance between the adhesion layer on the inner insulating member and the adhesion layer on the outer insulating member is a, and the distance between the adhesion layer on the inner insulating member and the bending area is b, and both a and b are greater than the thickness of the cathode electrode sheet or the anode electrode sheet.

[0008] In one embodiment, the adhesive layer is distributed at both ends of the isolation layer along the axial direction of the wound electrode assembly, and the adhesive layer is bonded to both side edges of the cathode electrode sheet and / or the anode electrode sheet in the width direction.

[0009] In one embodiment, an insulating layer is formed on at least one edge of the cathode electrode in the width direction, and the adhesive layer is bonded to the insulating layer.

[0010] In one embodiment, the adhesion layer is distributed at both ends of the isolation layer along the axial direction of the wound electrode assembly, and the adhesion layers at both ends of the isolation layer extend from both ends of the cathode electrode sheet and / or the anode electrode sheet in the width direction and are bonded to the diaphragm.

[0011] In one embodiment, the adhesion layer is distributed at both ends of the isolation layer along the axial direction of the wound electrode assembly, and the adhesion layers at both ends of the isolation layer extend from the two ends in the width direction of the cathode electrode sheet and / or the anode electrode sheet respectively. The isolation piece is provided on both sides of the cathode electrode sheet and / or the anode electrode sheet, and the adhesion layers of the isolation pieces on both sides are bonded to each other.

[0012] In one embodiment, the adhesive layer includes a plurality of gluing points, and the plurality of gluing points are evenly distributed on one side surface of the isolation layer;

[0013] Alternatively, the adhesive layer includes a plurality of adhesive blocks, and the plurality of adhesive blocks are evenly distributed on one side surface of the isolation layer;

[0014] Alternatively, the adhesive layer includes a plurality of adhesive blocks, the plurality of adhesive blocks are spaced apart along the axial direction of the wound electrode assembly, and each of the adhesive blocks extends along the winding direction of the wound electrode assembly;

[0015] Alternatively, the adhesive layer includes a plurality of adhesive blocks, the plurality of adhesive blocks are arranged at intervals along the winding direction of the wound electrode assembly, and each of the adhesive blocks extends along the axial direction of the wound electrode assembly.

[0016] In one embodiment, the ratio of the sum of the areas of the plurality of gluing points or the gluing blocks to the area of ​​the surface of one side of the isolation layer is greater than or equal to 5% and less than or equal to 60%.

[0017] In one embodiment, an embossed groove is formed on the surface of the cathode electrode, a plurality of convex structures are formed on one side of the isolation layer, the convex structures are embedded in the embossed groove, and the adhesive layer is attached to the surface of the convex structure.

[0018] In one embodiment, the separator is disposed on opposite sides of the first layer of the anode plate of the wound electrode assembly from the inside to the outside.

[0019] In one embodiment, a recessed area is formed on the surface of the cathode electrode piece and / or the anode electrode piece, and at least the portion of the separator where the adhesion layer is located is accommodated in the recessed area.

[0020] In one embodiment, the isolation member is entirely accommodated in the recessed area.

[0021] In the above-mentioned wound electrode assembly, the separator can increase the strength of the electrode sheet, thereby preventing the inner electrode sheet from breaking or falling off to a certain extent. Moreover, the adhesion layer of the separator is only distributed in a local area on one side of the separator, so the contact area with the active material layer of the electrode sheet is small, which is not easy to cause contamination and damage to the electrode sheet. Furthermore, since the separator can prevent lithium ions from flowing between the anode electrode sheet and the cathode electrode sheet, the lithium ions flowing from the cathode electrode sheet to the anode electrode sheet will be significantly reduced. Even if bending causes the active material layer on the anode electrode sheet to fall off and leads to a reduction in lithium insertion sites, the number of free lithium ions on one side of the anode electrode sheet can be effectively reduced. Therefore, the number of lithium ions that can obtain electrons and form lithium elements will be significantly reduced, thereby effectively suppressing the lithium precipitation phenomenon.

[0022] In addition, the utility model also provides a battery cell, a battery and an electrical device.

[0023] A battery cell comprises a shell, a top cover assembly and a wound electrode assembly as described in any one of the preferred embodiments above, wherein at least one end of the shell is provided with an opening, the wound electrode assembly is accommodated in the shell, and the top cover assembly is sealed at the opening.

[0024] A battery, characterized by comprising a plurality of battery cells as described in the above preferred embodiment.

[0025] An electrical device, characterized by comprising the battery cell as described in the above preferred embodiment or the battery as described in the above preferred embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 This is a schematic structural diagram of a battery cell in one embodiment of the present invention;

[0028] Figure 2 for Figure 1 A cross-sectional view of a wound electrode assembly in a battery cell;

[0029] Figure 3 for Figure 2 An enlarged schematic diagram of a local structure in the wound electrode assembly shown;

[0030] Figure 4 for Figure 3 A schematic diagram of the structure of the separator in the wound electrode assembly after unfolding;

[0031] Figure 5 is a schematic structural diagram of an expanded isolating member in another embodiment;

[0032] Figure 6 This is a schematic structural diagram of the second embodiment of the present invention after the isolation member is unfolded;

[0033] Figure 7 This is a schematic structural diagram of the fifth embodiment of the present invention after the isolation member is unfolded;

[0034] Figure 8 This is a schematic structural diagram of the sixth embodiment of the present invention after the isolation member is unfolded. DETAILED DESCRIPTION

[0035] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the present invention.

[0037] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this utility model, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0038] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0039] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0040] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0041] See also Figure 1 The present invention provides a battery cell 10. In addition, the present invention also provides a battery and an electrical device, wherein the electrical device includes the battery or the battery cell 10 and can be provided with electrical energy by the battery or the battery cell 10.

[0042] The aforementioned electrical devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, power tools, energy storage devices, amusement rides, elevators, lifting equipment, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, or electric airplane toys; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers; energy storage devices may include energy storage walls, base station energy storage, container energy storage, etc.; and amusement rides may include carousels, bungee jumping machines, etc.

[0043] The vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. For new energy vehicles, the above-mentioned battery can be used as a driving power source, thereby replacing fossil fuels to provide driving power.

[0044] The above-mentioned battery includes a plurality of battery cells 10, and the plurality of battery cells 10 can be connected in series, in parallel, or in series and in parallel. The above-mentioned battery can be a battery pack or a battery module. When the above-mentioned battery is a battery pack, the battery pack specifically includes a battery management system (BMS) and a plurality of the above-mentioned battery cells 10. The plurality of battery cells 10 can be electrically connected in series, in parallel, or in a mixture of series and parallel, and can be communicatively connected with the battery management system to form a battery pack. The above-mentioned battery management system controls and monitors the working status of each battery cell 10. In addition, the plurality of battery cells 10 can also be connected in series and / or in parallel first, and form a battery module with the module management system, and then the plurality of battery modules can be electrically connected in series, in parallel, or in a mixture of series and parallel, and together with the battery management system form a battery pack.

[0045] Specifically, the battery cell 10 in this embodiment is a prismatic battery, wherein the battery cell 10 includes a wound electrode assembly 100 , a housing 200 , and a top cover assembly 300 .

[0046] The housing 200 is a hollow structure with an interior space for accommodating the wound electrode assembly 100, electrolyte, and other components. At least one end of the housing 200 is provided with an opening through which the wound electrode assembly 100 can be inserted. The wound electrode assembly 100 is wound into a flat shape, and one housing 200 can accommodate one or more wound electrode assemblies 100 simultaneously.

[0047] Specifically, the outer contour of the housing 200 is a cuboid, with a rectangular opening. The top cover assembly 300 is mounted on the housing 200 and covers the opening, thereby forming a relatively closed environment within the housing 200, isolating the wound electrode assembly 100 from the external environment. Because the shape of the top cover assembly 300 must match the shape of the opening of the housing 200, it is generally rectangular.

[0048] See also Figure 2 and Figure 3 In one embodiment of the present invention, a wound electrode assembly 100 includes a cathode electrode sheet 110 , an anode electrode sheet 120 , a separator 130 and a spacer 140 .

[0049] The separator 130 is located between the adjacent cathode electrode sheet 110 and anode electrode sheet 120, and is used to separate the cathode electrode sheet 110 from the anode electrode sheet 120 to prevent short circuits. When preparing the wound electrode assembly 100, the cathode electrode sheet 110, the anode electrode sheet 120, and the separator 130 are first stacked and then rolled and pressed to form a flat structure. The relative positions of the cathode electrode sheet 110, the anode electrode sheet 120, and the separator 130 may vary for different models of wound electrode assemblies 100. For example, in this embodiment, there is one cathode electrode sheet 110 and one anode electrode sheet 120, and two separators 130, one of which is located at the bottom, with the cathode electrode sheet 110 stacked on it. Another separator 130 is set on the cathode electrode sheet 110, and the anode electrode sheet 120 is stacked on the second separator 130. Obviously, in other embodiments, the positions of the cathode electrode sheet 110 and the anode electrode sheet 120 can be reversed.

[0050] Furthermore, the wound electrode assembly 100 after press forming has a straight region 101 and a bending region 102 located at both ends of the straight region 101. The straight region 101 refers to the region with a parallel structure in the wound electrode assembly 100 with a flat structure, and the bending region 102 refers to the region with a bent structure in the wound electrode assembly 100 with a flat structure. In the straight region 101, the cathode electrode sheet 110, the anode electrode sheet 120 and the separator 130 are substantially parallel to each other and form straight sections respectively; in the bending region 102, the cathode electrode sheet 110, the anode electrode sheet 120 and the separator 130 are all bent to form bent sections, and the surfaces of the bent sections of each layer of the cathode electrode sheet 110, the anode electrode sheet 120 and the separator 130 are all curved.

[0051] The cathode electrode 110 is coated with a positive electrode active material layer formed by lithium manganese oxide, lithium cobalt oxide, lithium iron phosphate, etc., while the anode electrode 120 is coated with a negative electrode active material layer formed by graphite, silicon, etc. According to research, the cathode electrode 110 and the anode electrode 120 located in the bending area 102 are prone to cause their respective active materials to fall off during the bending process, which is called "powder loss". In particular, the shedding of the negative electrode active material on the anode electrode 120 will cause the number of lithium insertion sites of the negative electrode active material layer of the anode electrode 120 to be less than the number of lithium ions that can be provided by the positive electrode active material layer of its adjacent cathode electrode 110, thereby causing the lithium ions deintercalated from the positive electrode active material layer to be unable to be equally intercalated into the negative electrode active material layer. Therefore, after the lithium ions deintercalated from the cathode electrode 110 pass through the diaphragm 130 and reach the anode electrode 120, due to the lack of sufficient lithium insertion sites to combine with them, a large amount of free lithium ions will appear on one side of the anode electrode 120. During the charging process, the free lithium ions will combine with the electrons on the negative electrode side (the side of the anode electrode 120 ) to form single-element lithium, thereby causing lithium deposition in the bending area 102 .

[0052] Since the straight sections of the cathode electrode sheet 110 and anode electrode sheet 120 in the straight region 101 do not need to be bent during the forming process of the wound electrode assembly 100, there is almost no "powder loss". Therefore, the lithium insertion sites of the negative active material layer of the anode electrode sheet 120 in the straight region 101 can maintain a good match with the number of lithium ions that can be provided by the positive active material layer of the adjacent cathode electrode sheet 110. Therefore, lithium deposition generally does not occur in the straight region 101 of the wound electrode assembly 100.

[0053] To suppress lithium plating, the present application provides a separator 140 between the anode electrode 120 and the cathode electrode 110, which are located in a predetermined layer within the wound electrode assembly 100. Separator 140 comprises an isolation layer 141 and an adhesion layer 142. Isolation layer 141 is formed from an insulating material and can block lithium ions. Adhesion layer 142 can bond and secure separator 140, preventing it from shifting and losing its function during the cell winding process. Furthermore, adhesion layer 142 is distributed in a localized area on one side of isolation layer 141, meaning that adhesion layer 142 does not completely cover the entire surface of isolation layer 141.

[0054] Furthermore, the isolation member 140 is covered on at least one side of the front preset layer of anode electrode sheet 120 and / or cathode electrode sheet 110 from the inside to the outside of the wound electrode assembly 100 to isolate the two adjacent layers of anode electrode sheet 120 and cathode electrode sheet 110. The isolation member 140 passes through the bending area 102 and extends to the straight area 101, and is bonded and fixed by the adhesive layer 142. It can be seen that the isolation member 140 can completely cover the bending section of the anode electrode sheet 120 and / or cathode electrode sheet 110. Moreover, since the adhesive layer 142 of the isolation member 140 is only distributed in a local area on one side of the isolation layer 141, even if the adhesive layer 142 adheres to the active material layer of the electrode, due to the small contact area, it is not easy to cause significant damage and contamination to the active material layer.

[0055] The isolation member 140 can increase the strength of the electrode, thereby preventing the inner electrode from breaking to a certain extent. Moreover, since the isolation layer 141 can prevent the flow of lithium ions, the lithium ions flowing from the bent section of the cathode electrode 110 to the bent section of the anode electrode 120 will be significantly reduced. Even if the bending causes the active material layer of the bent section of the anode electrode 120 to fall off and leads to a reduction in lithium insertion sites, since the lithium ions supplied by the cathode electrode 110 are also reduced, the number of free lithium ions on one side of the anode electrode 120 can also be effectively reduced. Therefore, the number of lithium ions on one side of the anode electrode 120 that can obtain electrons and form lithium will be significantly reduced, thereby effectively suppressing the lithium precipitation phenomenon occurring in the bending area 102.

[0056] Typically, the separator 140 is only applied to the anode electrode sheets 120 or cathode electrode sheets 110 in the first three layers of the wound electrode assembly 100, from the inside out. This is because the first three layers of the electrode sheets in the wound electrode assembly 100 generally have the largest bending amplitude and are most susceptible to breakage or "chipping." Specifically, in this embodiment, the separator 140 is applied to opposite sides of the cathode electrode sheet 110 in the first three layers of the wound electrode assembly 100, from the inside out.

[0057] The separators 140 on both sides can separate the cathode electrode sheet 110 from the two adjacent anode electrode sheets 120. This reduces the amount of lithium ions flowing from the cathode electrode sheet 110 to the anode electrode sheets 120 on both sides, further improving the suppression of lithium deposition. Furthermore, since the separators 140 only need to be installed on fewer electrode sheets to achieve a better suppression of lithium deposition, a significant increase in the thickness of the wound electrode assembly 100 can be avoided.

[0058] Furthermore, in this embodiment, a recessed area (not shown) is formed on the surface of the cathode electrode piece 110 and / or the anode electrode piece 120 , and at least the portion of the separator 140 where the adhesive layer 142 is located is accommodated in the recessed area.

[0059] Specifically, for an electrode sheet covered with separator 140, a recessed area can be formed on the side where separator 140 is located by embossing or thinning. The adhesive layer 142 is bonded to the recessed area, allowing the separator 140 and the electrode sheet to at least partially overlap along the thickness direction. This reduces the height of the separator 140 protruding from the electrode sheet surface, thereby helping to avoid significantly increasing the thickness of the wound electrode assembly 100 due to the separator 140.

[0060] In the case where the separator 140 is covered on the cathode electrode 110, a recessed area is generally obtained by thinning the side of the cathode electrode 110 where the positive electrode active material layer is formed. Therefore, the content of positive electrode active material on the cathode electrode 110 will be reduced, and the number of lithium ions that can be released will also be reduced, thereby further suppressing lithium precipitation. In the case where the separator 140 is covered on the anode electrode 120, it is generally formed into the recessed area by embossing. In this way, the loss of negative electrode active material on the anode electrode 120 during the formation of the recessed area can be minimized, and the lithium insertion sites provided by the anode electrode 120 can be avoided from being further reduced.

[0061] Furthermore, in this embodiment, the separator 140 is entirely contained within the recessed area. This means that the recessed area is relatively large, and both the adhesive layer 142 and the isolation layer 141 of the separator 140 are located within it, further reducing the height of the separator 140 protruding from the electrode surface. Furthermore, the recessed area serves to position and limit the separator 140, facilitating its rapid positioning at the desired location on the electrode surface and preventing it from shifting during the cell winding process.

[0062] Please also refer to Figure 4 and Figure 5 In this embodiment, the adhesion layer 142 is distributed at both ends of the isolation layer 141 along the winding direction of the wound electrode assembly 100, and the adhesion layer 142 is bonded to the straight section of the cathode electrode sheet 110 and / or the anode electrode sheet 120 located in the straight area 101.

[0063] The isolation layer 141 is bonded to the electrode sheet at the straight section of the electrode sheet, and the adhesive layer 142 is not present in the area where the cathode electrode sheet 110 and / or the anode electrode sheet 120 are bent. This reduces the thickness of the bent area 102 and the distance between the cathode electrode sheet 110 and the anode electrode sheet 120 within the bent area 102.

[0064] The adhesive layer 142 may be a long strip of adhesive formed by continuous coating and extending along the axial direction of the wound electrode assembly 100 (see FIG. Figure 4 ), the bonding effect of the long strip is better. In addition, the adhesive layer 142 can also be formed by discontinuous adhesive blocks (see Figure 5 The adhesive layer 142 obtained by spot coating includes multiple adhesive blocks, namely adhesive blocks 1421, and the multiple adhesive blocks 1421 are spaced apart along the axial direction of the wound electrode assembly 100. Compared with the long strips of adhesive, the multiple adhesive blocks 1421 have a smaller bonding area and less damage to the electrode.

[0065] For further information, please refer to Figure 3 In this embodiment, the cathode electrode sheet 110 or the anode electrode sheet 120 are covered with an isolation member 140 on both sides, and in the winding direction of the wound electrode assembly 100, the distance between the adhesion layer 142 on the inner isolation member 140 and the adhesion layer 142 on the outer isolation member 140 is a, and the distance between the adhesion layer 142 on the inner isolation member 140 and the bending area is b, and both a and b are greater than the thickness of the cathode electrode sheet 110 or the anode electrode sheet 120.

[0066] As can be seen, the adhesive layers 142 on the separators 140 on either side of the electrode sheet do not overlap in the thickness direction of the wound electrode assembly 100. This prevents the inner and outer adhesive layers 142 from overlapping, which could result in locally excessive thickness in the wound electrode assembly 100. This also allows for space for the separators 140 on both sides to compress and deform the electrode sheet. Furthermore, because b is greater than the electrode sheet width c, excessive thickness in the bend region 102 is further prevented.

[0067] Obviously, there are many other possibilities for the distribution of the adhesive layer 142 on the spacer 140 and the way to fix it to the electrode, as long as it is ensured that the adhesive layer 142 does not completely cover the bending area 102. For example:

[0068] See also Figure 6 In the second embodiment, the adhesive layer 142 is distributed at both ends of the isolation layer 141 along the axial direction of the wound electrode assembly 100, and the adhesive layer 142 is bonded to the two side edges of the cathode electrode sheet 110 and / or the anode electrode sheet 120 in the width direction.

[0069] The width direction of the cathode electrode sheet 110 and the anode electrode sheet 120 is consistent with the axial direction of the wound electrode assembly 100. Therefore, when the separator 140 is provided, the adhesive layer 142 can be bonded only to the two side edges of the bending region 102 in the width direction. The overlapping area between the adhesive layer 142 and the bending region 102 is relatively small, and therefore the thickness of the bending region 102 is relatively small.

[0070] Furthermore, in this embodiment, an insulating layer (not shown) is formed on at least one edge of the cathode electrode 110 in the width direction, and the adhesive layer 142 is bonded to the insulating layer. The insulating layer is typically provided on the edge of the cathode electrode 110 where the tab is provided and extends along the length of the electrode. The insulating layer is typically a ceramic layer, and no active material is present in the area where it is provided.

[0071] Since there is no active material layer in the area where the insulating layer is located, the adhesive layer 142 will not adhere to the active material layer on the electrode, and thus it is not easy to damage the active material layer.

[0072] It should be noted that, in the second embodiment, the adhesive layer 142 may also be a long rubber strip formed by continuous coating, or a discontinuous rubber block formed by dot coating.

[0073] For another example, in the third embodiment, the adhesion layer 142 is distributed at both ends of the isolation layer 141 along the axial direction of the wound electrode assembly 100, and the adhesion layers 142 at both ends of the isolation layer 141 extend from both ends of the cathode electrode sheet 110 and / or the anode electrode sheet 120 in the width direction and are bonded to the diaphragm 130.

[0074] The structure of separator 140 in this embodiment is similar to that of separator 140 in the second embodiment, except that separator 140 in this embodiment is larger along the axial direction of wound electrode assembly 100, that is, in the width direction of separator 140. This allows adhesive layers 142 at both ends of separator 141 to extend from the width of the electrode. This allows separator 140 to be bonded to diaphragm 130 via adhesive layers 142, and adhesive layers 142 do not contact the electrode surface, minimizing damage to the active material layer on the electrode surface.

[0075] For example, in the fourth embodiment, the adhesion layer 142 is distributed at both ends of the isolation layer 141 along the axial direction of the wound electrode assembly 100, and the adhesion layers 142 at both ends of the isolation layer 141 extend from the two ends in the width direction of the cathode electrode sheet 110 and / or the anode electrode sheet 120 respectively. Isolators 140 are provided on both sides of the cathode electrode sheet 110 and / or the anode electrode sheet 120, and the adhesion layers 142 of the isolation members 140 on both sides are bonded to each other.

[0076] The structure of the isolating member 140 in this embodiment is the same as that of the isolating member 140 in the third embodiment, with the only difference being the method of fixing the electrode. When setting the isolating member 140, the isolating member 140 is set on both sides of the electrode, and the sides of the isolating member 140 provided with the adhesive layer 142 are arranged opposite each other. In this way, the adhesive layers 142 of the isolating members 140 on both sides can be bonded to each other to clamp the electrode between the isolating members 140 on both sides, thereby achieving the fixation of the isolating layer 140 and the electrode. Similarly, the adhesive layer 142 of the isolating member 140 does not contact the surface of the electrode, so the damage to the active material layer on the surface of the electrode is minimized.

[0077] See also Figure 7 In the fifth embodiment, the adhesive layer 142 includes a plurality of gluing points 1422 , and the plurality of gluing points 1422 are evenly distributed on one side surface of the isolation layer 141 .

[0078] Isolator 140 is secured to the electrode surface by the bonding force provided by multiple bonding points 1422. Multiple bonding points 1422 are evenly distributed on the surface of isolation layer 141, so the bonding force provided during bonding to the electrode is also more evenly distributed, reliably securing isolate 140 to the electrode. Furthermore, multiple bonding points 1422 occupy a relatively low proportion of the surface of one side of isolation layer 141, thereby minimizing adhesion to the active material layer on the electrode surface while maintaining bonding strength, thereby reducing damage to the electrode.

[0079] Furthermore, in other embodiments, the adhesive layer 142 may further include multiple adhesive blocks (not shown), which are evenly distributed on one side of the isolation layer 141. The adhesive blocks may be rectangular, circular, or other shapes. The area of ​​a single adhesive block is larger than the area of ​​a single adhesive point 1422, and the gap between two adjacent adhesive blocks may also be larger, making molding more convenient.

[0080] Furthermore, each adhesive block can be in the form of an elongated strip, extending along the winding direction or axial direction of the wound electrode assembly 100. When the adhesive blocks extend along the winding direction of the wound electrode assembly 100, the multiple adhesive blocks are spaced apart along the axial direction of the wound electrode assembly 100; and when the adhesive blocks extend along the axial direction of the wound electrode assembly 100, the multiple adhesive blocks are spaced apart along the winding direction of the wound electrode assembly 100. Furthermore, in one embodiment, the ratio of the sum of the areas of the multiple adhesive points 1422 or adhesive blocks to the area of ​​one side surface of the isolation layer 141 is greater than or equal to 5% and less than or equal to 60%. When this ratio is less than 5%, the adhesive layer 142 formed by the multiple adhesive points 1422 or adhesive blocks provides limited bonding force, failing to reliably secure the isolation member 140. When this ratio is greater than 60%, the adhesion area between the adhesive layer 142 and the active material layer on the electrode surface is large, causing significant damage to the electrode. Preferably, the above ratio is greater than or equal to 5% and less than or equal to 30%. When the above ratio is less than 30%, damage to the adhesive layer 142 and the electrode surface active material layer is relatively small.

[0081] See also Figure 8 In the sixth embodiment, an embossed groove (not shown) is formed on the surface of the cathode electrode 110, and a plurality of convex structures 1411 are formed on one side of the isolation layer 141. The convex structures 1411 are embedded in the embossed groove, and the adhesive layer 142 is attached to the surface of the convex structure 1411.

[0082] The isolating member 140 can be first laid on the surface of the cathode electrode 110, and then embossed together with the cathode electrode 110, thereby forming an embossed groove on one side of the cathode electrode 110, and at the same time forming a corresponding convex structure 1411 on the side of the isolating layer 141 facing the embossed groove. The convex structure 1411 and the embossed groove are nested with each other, so that the isolating member 140 and the cathode electrode 110 can be clamped and fixed. In addition, the connection strength between the isolating member 140 and the cathode electrode 110 can be increased by attaching the adhesive layer 142 to the surface of the convex structure 1411. The adhesive layer 142 is dot-shaped, and a glue point is formed on the surface of each convex structure 1411.

[0083] In the above-mentioned wound electrode assembly 100, the separator 140 can increase the strength of the electrode sheet, thereby preventing the inner electrode sheet from breaking or falling off to a certain extent. Moreover, the adhesion layer 142 of the separator 140 is only distributed in a local area on one side of the separator 141, so the contact area with the active material layer of the electrode sheet is small, which is not easy to cause electrode contamination and damage. Furthermore, since the separator 141 can prevent lithium ions from flowing between the anode electrode sheet 120 and the cathode electrode sheet 110, the lithium ions flowing from the cathode electrode sheet 110 to the anode electrode sheet 120 will be significantly reduced. Even if bending causes the active material layer on the anode electrode sheet 120 to fall off and leads to a reduction in lithium insertion sites, the number of free lithium ions on one side of the anode electrode sheet 120 can be effectively reduced. Therefore, the number of lithium ions that can obtain electrons and form lithium elements will be significantly reduced, thereby effectively suppressing the lithium precipitation phenomenon.

[0084] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present utility model patent shall be determined by the appended claims.

Claims

1. A wound electrode assembly comprising a cathode electrode sheet, an anode electrode sheet, and a separator, wherein the cathode electrode sheet, the anode electrode sheet, and the separator are wound and pressed to form a flat structure, so that the wound electrode assembly has a straight region and bent regions at both ends of the straight region, characterized in that: The wound electrode assembly also includes an isolation member, which includes an isolation layer and an adhesion layer distributed in a local area on one side of the isolation layer. The isolation member is covered on at least one side of the anode plate and / or the cathode plate of the front preset layer from the inside to the outside of the wound electrode assembly to isolate the two adjacent layers of the anode plate and the cathode plate. The isolation member passes around the bending area and extends to the straight area, and is bonded and fixed by the adhesion layer.

2. The wound electrode assembly according to claim 1, wherein: The adhesive layer is distributed at both ends of the isolation layer along the winding direction of the wound electrode assembly, and the adhesive layer is bonded to the cathode electrode sheet and / or the anode electrode sheet in the straight section of the straight area.

3. The wound electrode assembly according to claim 2, wherein: The adhesive layer is in a long strip shape and extends along the axial direction of the wound electrode assembly; or, the adhesive layer includes a plurality of adhesive blocks, and the plurality of adhesive blocks are arranged at intervals along the axial direction of the wound electrode assembly.

4. The wound electrode assembly according to claim 2, wherein: The insulating member is covered on both opposite sides of the cathode electrode sheet or the anode electrode sheet, and in the winding direction of the wound electrode assembly, the distance between the adhesion layer on the inner insulating member and the adhesion layer on the outer insulating member is a, and the distance between the adhesion layer on the inner insulating member and the bending area is b, and both a and b are greater than the thickness of the cathode electrode sheet or the anode electrode sheet.

5. The wound electrode assembly according to claim 1, wherein: The adhesive layer is distributed at both ends of the isolation layer along the axial direction of the wound electrode assembly, and the adhesive layer is adhered to both side edges of the cathode electrode sheet and / or the anode electrode sheet in the width direction.

6. The wound electrode assembly according to claim 5, characterized in that An insulating layer is formed on at least one edge of the cathode electrode in a width direction, and the adhesive layer is adhered to the insulating layer.

7. The wound electrode assembly according to claim 1, wherein: The adhesion layers are distributed at both ends of the isolation layer along the axial direction of the wound electrode assembly, and the adhesion layers at both ends of the isolation layer extend from both ends of the cathode electrode sheet and / or the anode electrode sheet in the width direction and are bonded to the diaphragm.

8. The wound electrode assembly according to claim 1, wherein: The adhesion layer is distributed at both ends of the isolation layer along the axial direction of the wound electrode assembly, and the adhesion layers at both ends of the isolation layer extend from the two ends of the width direction of the cathode electrode sheet and / or the anode electrode sheet respectively. The isolation piece is provided on both sides of the cathode electrode sheet and / or the anode electrode sheet, and the adhesion layers of the isolation pieces on both sides are bonded to each other.

9. The wound electrode assembly according to claim 1, wherein: The adhesive layer includes a plurality of gluing points, and the plurality of gluing points are evenly distributed on one side surface of the isolation layer; Alternatively, the adhesive layer includes a plurality of adhesive blocks, and the plurality of adhesive blocks are evenly distributed on one side surface of the isolation layer; Alternatively, the adhesive layer includes a plurality of adhesive blocks, the plurality of adhesive blocks are spaced apart along the axial direction of the wound electrode assembly, and each of the adhesive blocks extends along the winding direction of the wound electrode assembly; Alternatively, the adhesive layer includes a plurality of adhesive blocks, the plurality of adhesive blocks are arranged at intervals along the winding direction of the wound electrode assembly, and each of the adhesive blocks extends along the axial direction of the wound electrode assembly.

10. The wound electrode assembly according to claim 9, wherein: The ratio of the sum of the areas of the plurality of gluing points or the gluing blocks to the area of ​​the surface of one side of the isolation layer is greater than or equal to 5% and less than or equal to 60%.

11. The wound electrode assembly according to claim 1, wherein: An embossed groove is formed on the surface of the cathode electrode, a plurality of convex structures are formed on one side of the isolation layer, the convex structures are embedded in the embossed groove, and the adhesive layer is attached to the surface of the convex structure.

12. The wound electrode assembly according to claim 1, wherein: The separator is arranged on opposite sides of the cathode electrode in the first three layers of the wound electrode assembly from the inside to the outside.

13. The wound electrode assembly according to any one of claims 1 to 12, characterized in that: A recessed area is formed on the surface of the cathode electrode piece and / or the anode electrode piece, and at least the portion of the separator where the adhesion layer is located is accommodated in the recessed area.

14. The wound electrode assembly according to claim 13, wherein: The isolating member is entirely accommodated in the recessed area.

15. A battery cell, characterized in that: The invention comprises a shell, a top cover assembly and a wound electrode assembly as described in any one of claims 1 to 14, wherein at least one end of the shell is provided with an opening, the wound electrode assembly is accommodated in the shell, and the top cover assembly is sealed at the opening.

16. A battery, characterized in that: The battery comprises a plurality of battery cells as claimed in claim 15 .

17. An electrical device, characterized in that: The battery cell according to claim 15 or the battery according to claim 16 is included.

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