WO2023206417A1 - 一种电极组件、纽扣电池及纽扣电池的制造方法 - Google Patents

一种电极组件、纽扣电池及纽扣电池的制造方法 Download PDF

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Publication number
WO2023206417A1
WO2023206417A1 PCT/CN2022/090457 CN2022090457W WO2023206417A1 WO 2023206417 A1 WO2023206417 A1 WO 2023206417A1 CN 2022090457 W CN2022090457 W CN 2022090457W WO 2023206417 A1 WO2023206417 A1 WO 2023206417A1
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Prior art keywords
pole piece
layer
axis
electrode assembly
winding
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PCT/CN2022/090457
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English (en)
French (fr)
Inventor
李勇
曾巧
Original Assignee
宁德新能源科技有限公司
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Application filed by 宁德新能源科技有限公司 filed Critical 宁德新能源科技有限公司
Priority to CN202280007390.8A priority Critical patent/CN116802882A/zh
Priority to PCT/CN2022/090457 priority patent/WO2023206417A1/zh
Publication of WO2023206417A1 publication Critical patent/WO2023206417A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/463—Separators, membranes or diaphragms characterised by their shape
    • H01M50/466—U-shaped, bag-shaped or folded
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present application relates to the field of battery technology, and in particular to an electrode assembly, a button battery, and a manufacturing method of a button battery.
  • button batteries made by winding usually include an upper case, a lower case, and an electrode assembly formed by stacking and winding cathode plates, separators, and anode plates.
  • the cathode plate and the anode plate may shift relative to each other under the action of external forces (such as vibration, etc.), causing local lithium deposition or loss of discharge capacity, resulting in a decrease in secondary battery performance; and the cathode electrode
  • the separator between the cathode and anode plates may also shrink and fold at high temperatures, resulting in a short circuit between the cathode and anode plates, which may reduce the performance of the secondary battery.
  • the purpose of this application is to provide an electrode assembly, a button battery and a manufacturing method of a button battery, so as to improve the performance of the button battery.
  • the specific technical solutions are as follows:
  • a first aspect of the present application provides an electrode assembly, which includes a first pole piece, a second pole piece and a separator.
  • the polarity of the second pole piece is opposite to that of the first pole piece, the diaphragm is disposed between the first pole piece and the second pole piece, the first pole piece, the diaphragm and the second pole piece are stacked and wound around the first axis;
  • the ends of the plurality of winding layers formed by winding the separator are bent toward the first axis to form a plurality of first bending edges; among the two adjacent winding layers, the end of the winding layer away from the first axis is A folded edge covers the first folded edge of the winding layer near the first axis.
  • the ends of multiple winding layers formed by winding the separator are bent toward the first axis to form multiple first bending edges; and in two adjacent winding layers , covering the first bending edge of the winding layer away from the first axis on the first bending edge of the winding layer close to the first axis, which can constrain the diaphragm and reduce the risk of inward shrinkage and folding of the diaphragm. It is beneficial to reduce the risk of short circuit between the first pole piece and the second pole piece; and the first bent edge can also limit the relative offset between the first pole piece and the second pole piece, improving local lithium deposition and discharge capacity loss. .
  • the electrode assembly further includes a first conductive part and a second conductive part, wherein the first conductive part is connected to the first pole piece, and the second conductive part is connected to the second pole piece; the first conductive part and/or the second conductive part covers at least one first bent edge.
  • the first bent edge of the separator can be constrained by the first conductive part and/or the second conductive part, which is beneficial to further improving the problems of separator folding and thermal shrinkage, thereby further improving the performance of the battery.
  • first conductive part and/or the second conductive part covering at least one first bent edge is also beneficial to reducing the interference of the first conductive part and/or the second conductive part in the extension direction of the first axis of the battery. Taking up space will help improve the space utilization within the battery, thereby increasing energy density.
  • the length of the bending of the end of the winding layer toward the first axis is a; among the two adjacent winding layers, the first bending edge of the winding layer away from the first axis
  • the overlap length with the first bent edge of the winding layer close to the first axis is b, 0.6a ⁇ b ⁇ 0.85a. The relationship between the two is within this range, which is conducive to further improving the safety and reliability of the battery.
  • the separator includes a base material layer and a ceramic layer.
  • the ceramic layer is disposed on a surface of the base material layer close to the first pole piece, and/or the ceramic layer is disposed on a surface of the base material layer close to the second pole piece. .
  • the separator includes a base material layer and a first adhesive layer.
  • the first adhesive layer is disposed on a surface of the base material layer close to the first pole piece, and/or the first adhesive layer is disposed on the base layer.
  • the material layer is close to the surface of the second pole piece.
  • the separator includes a base material layer and a second adhesive layer.
  • the second adhesive layer is disposed on a surface of the base material layer of the first bent edge away from the first pole piece or the second pole piece. , to fix the first bent edge. This arrangement is beneficial to maintaining the first bent edge in a bent state, thereby improving the safety and reliability of the battery.
  • the second adhesive layer is provided separately from the first conductive part and the second conductive part. In this way, the risk of the diaphragm being driven to move by the second adhesive layer when the first conductive part and the second conductive part vibrate can be reduced, thereby helping to improve the reliability of the diaphragm.
  • the first adhesive layer is connected to the second adhesive layer.
  • the entire separator is covered with an adhesive layer, which on the one hand facilitates the manufacturing process and on the other hand helps to improve the problem of separator shrinkage, thereby improving the safety and reliability of the battery.
  • the second adhesive layer is provided separately from the first pole piece and the second pole piece. This arrangement is beneficial to saving costs and reducing the impact of the second adhesive layer on the electrochemical reaction between the first pole piece and the second pole piece.
  • the second adhesive layer when viewed along the extension direction of the first axis, bonds the first bent edge of the winding layer away from the first axis and the first bending edge of the winding layer close to the first axis among the two adjacent winding layers.
  • the overlapping area of the first folded edges of the one-axis winding layer In this way, it is beneficial to make the stacking between two adjacent first bending edges more reliable.
  • the second adhesive layer when viewed along the extension direction of the first axis, completely covers the side surface of the first bent edge away from the first pole piece or the second pole piece. In this way, it is convenient to apply the second adhesive layer to the entire first bent edge.
  • the second adhesive layer adheres to the first conductive part and/or the second conductive part.
  • the first conductive part and/or the second conductive part are covered on at least one first bending edge through the second adhesive layer, which is beneficial to reducing the space occupied by the two conductive parts in the extension direction of the first axis, This further helps to improve the space utilization in the battery, and also helps to fix the first conductive part or the second conductive part and reduce the risk of the first conductive part or the second conductive part jumping.
  • the first pole piece is an anode pole piece
  • the second pole piece is a cathode pole piece
  • the difference in width between the separator and the first pole piece is 0.8mm ⁇ 2.0mm
  • the difference in width between the first pole piece and the second pole piece is 0mm ⁇ 1mm.
  • the separator includes a base material layer, and the base material layer is a single-layer film or a multi-layer composite film.
  • the material of the base material layer includes at least one of polypropylene or polyethylene.
  • the separator prepared from the above materials can isolate the first pole piece and the second pole piece, prevent electrons from passing through freely during the electrochemical reaction, and allow ions in the electrochemical reaction to freely pass between the first pole piece and the second pole piece. pass.
  • the substrate layer is a single-layer polypropylene film. Separators of different materials have different thermal shrinkages. Using separators of materials with smaller thermal shrinkage is beneficial to reducing the risk of dimensional shrinkage of the first bending edge, thereby further improving safety and reliability.
  • the electrode assembly is cylindrical. This facilitates the bending of the separator to form a plurality of first bending edges.
  • a second aspect of the present application provides a button battery, including the electrode assembly of the first aspect.
  • the electrode assembly in the button battery is formed by bending the ends of multiple rolled layers of the separator toward the first axis to form a plurality of first bent edges; and in the adjacent Among the two winding layers, the first bending edge of the winding layer away from the first axis is covered with the first bending edge of the winding layer close to the first axis, which can constrain the diaphragm and reduce the inward shrinkage and shrinkage of the diaphragm.
  • the risk of folding is conducive to reducing the probability of short circuit between the first pole piece and the second pole piece; and the first bent edge can also limit the relative offset between the first pole piece and the second pole piece, improving local analysis. Lithium and discharge capacity loss.
  • the application of the electrode assembly of the present application in button batteries is also beneficial to improving the performance of button batteries.
  • the bending of the separator can also reduce the width of the separator and reduce the space occupied by the separator in the extension direction of the first axis of the button battery, which is beneficial to improving the space utilization of the button battery.
  • a third aspect of the application provides a method for manufacturing a button battery, which includes: stacking a first pole piece, a separator and a second pole piece and winding them around a first axis; winding the separator into multiple winding layers The ends are bent toward the first axis to form a plurality of first bending edges; among the two adjacent winding layers, the first bending edge of the winding layer far away from the first axis covers the first bending edge close to the first axis. on the first bent edge of the winding layer of the first axis.
  • the electrode assembly in the button battery is bent toward the first axis by winding the separator into a plurality of winding layers to form a plurality of first bends. and in two adjacent winding layers, covering the first bending edge of the winding layer away from the first axis on the first bending edge of the winding layer close to the first axis, the separator can be constrained , reducing the risk of inward shrinkage and folding of the diaphragm, which is conducive to reducing the risk of short circuit between the first pole piece and the second pole piece; and the first bent edge can also limit the gap between the first pole piece and the second pole piece. Relative offset to improve local lithium deposition and discharge capacity loss. Therefore, the button battery according to the embodiment of the present application is beneficial to improving the performance of the button battery.
  • the bending of the separator can also reduce the width of the separator and reduce the space occupied by the separator in the extension direction of the first axis of the button battery, which is beneficial to improving the space utilization of the button battery.
  • the length of the bending of the end of the winding layer toward the first axis is a; among the two adjacent winding layers, the first bending edge of the winding layer away from the first axis
  • the overlap length with the first bent edge of the winding layer close to the first axis is b, 0.6a ⁇ b ⁇ 0.85a. The relationship between the two is within this range, which is conducive to further improving the safety and reliability of button batteries.
  • the method further includes heating the first bent edge.
  • the first bending edges of the two adjacent layers can be bonded together, which is beneficial to improving the shrinkage of the separator.
  • it is also beneficial to maintaining the bent state of the first bending edge and reducing the first bending of the separator. Risk of edge folding outwards.
  • Figure 1 is a schematic longitudinal cross-sectional view of a battery according to an embodiment of the present application.
  • Figure 2a is a partially enlarged schematic diagram of D in Figure 1 in an embodiment of the present application.
  • Figure 2b is a partially enlarged schematic diagram of D in Figure 1 in another embodiment of the present application.
  • Figure 2c is a partially enlarged schematic diagram of D in Figure 1 in yet another embodiment of the present application.
  • Figure 3a is an enlarged schematic diagram of E in Figure 1 in an embodiment of the present application.
  • Figure 3b is an enlarged schematic diagram of E in Figure 1 in another embodiment of the present application.
  • Figure 4 is a top view of a battery in some embodiments of the present application.
  • Figure 5 is a schematic diagram of the separator in an electrode assembly in some embodiments of the present application being bent and then subjected to planar hot pressing;
  • Figure 6 is a flow chart of an electrode assembly manufacturing method in some embodiments of the present application.
  • Figure 7 is a schematic structural diagram of the first pole piece or the second pole piece before winding according to the embodiment of the present application.
  • Figure 8 is a top view of the first pole piece or the second pole piece before winding according to the embodiment of the present application.
  • Figure 9 is a schematic diagram of the first pole piece, the second pole piece, and the separator according to the embodiment of the present application.
  • Battery-10 first housing-20; second housing-21; first wall-20a; second wall-20b; third wall-21a; fourth wall-21b; electrode assembly-100; first pole Piece-110; second pole piece-120; first layer of first pole piece-110a; first layer of second pole piece-120a; second layer of first pole piece-110b; diaphragm-130; first axis-C ;First bent edge-131;Second part-132;Connection part-133;Substrate layer-134;First layer of separator-130a;First layer of first bent edge-131a;Second part of the first layer -132a; the first layer connection part-133a; the second layer separator-130b; the second layer first bent edge-131b; the second part of the second layer-132b; the second layer connection part-133b; the third layer separator -130c; the first bent edge of the third layer-131c; the second part of the third layer-132c; the third layer connection part-133c; side surface-135; conductive part-
  • spatially relative terms such as “on,” etc., may be used herein for convenience to describe the relationship of one element or feature to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device or device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the diagram is turned over, features described as “above” or “on” other features or features would then be oriented “below” or “beneath” the other features or features. Thus, the exemplary term “upper” may include both upper and lower directions. It will be understood that, although the terms first, second, third, etc.
  • first direction may be any direction in the plane where the first surface is located.
  • a button battery made by a winding method usually includes an upper case, a lower case, and an electrode assembly formed by stacking and winding a cathode plate, a separator, and an anode plate.
  • the cathode plate and the anode plate may shift relative to each other under the action of external forces (such as vibration, etc.), causing local lithium precipitation and loss of discharge capacity, resulting in a decline in button battery performance; and the cathode plate
  • the separator between the anode and the cathode may also shrink and fold at high temperatures, which may cause a short circuit between the cathode and the anode, which may reduce the safety performance of the button battery.
  • embodiments of the present application provide an electrode assembly, a button battery, and a manufacturing method of button batteries.
  • the specific technical solutions are as follows:
  • Figure 1 is a cross-sectional view longitudinally cut along the dotted line F-F in Figure 4.
  • the first aspect of the present application provides an electrode assembly 100, including a first pole piece 110 and a second pole piece 120. And the diaphragm 130, the polarity of the second pole piece 120 and the first pole piece 110 is opposite; the diaphragm 130 is disposed between the first pole piece 110 and the second pole piece 120; the first pole piece 110, the diaphragm 130 and the second pole
  • the sheet 120 is wound around the first axis C; viewed from a longitudinal cross-section, the ends of the multiple winding layers formed by winding the separator 130 are bent toward the first axis C to form a plurality of first bends. Side 131.
  • the direction in which the first axis C extends is defined as the first direction Z
  • the two directions perpendicular to the first direction Z are defined as the second direction X and the third direction Y.
  • the second direction X and The third directions Y are perpendicular to each other.
  • the first axis C refers to the cross-section of the battery, and the circumscribed circle of the cross-sectional figure is obtained.
  • the center of the circumscribed circle is the point projected by the first axis C on the cross-section, and the extension direction of the center of the circle in the first direction Z That is the first axis C.
  • the battery 10 may be a button battery. Button batteries generally have a smaller volume relative to conventional square batteries, cylindrical batteries, and the like.
  • the electrode assembly 100 has a cylindrical shape, which is beneficial to the arrangement of the first bending edge 131 .
  • the electrode assembly 100 has a cylindrical shape, that is, a cross-section perpendicular to the first axis C of the electrode assembly 100 is circular.
  • the battery 10 includes a first housing 20 and a second housing 21 . The first housing 20 and the second housing 21 are connected to form an accommodation space, and the electrode assembly 100 is placed in the accommodation space. Inside.
  • the first housing 20 and the second housing 21 are used to protect the electrode assembly 100 and reduce the impact of external objects on the electrode assembly 100 .
  • the first housing 20 has a first wall 20a opposite to the electrode assembly 100 in the first direction Z and a second wall 20b extending in the first direction Z from the first wall 20a. Viewed from the first direction Z, the electrode assembly 100 may be surrounded by the second wall 20b.
  • the second housing 21 has a third wall 21 a opposite to the electrode assembly 100 in the first direction Z and a fourth wall 21 b extending in the first direction Z from the third wall 21 a. Viewed from the first direction Z, the electrode assembly 100 may be surrounded by the fourth wall 21b.
  • the diaphragm 130 refers to a device used to separate the first pole piece 110 and the second pole piece 120 to reduce the risk of internal short circuit of the first pole piece 110 and the second pole piece 120 and allow ions to pass freely to form an ion path. part. Viewed along the third direction Y, after being bent, the separator 130 can be divided into a first bent edge 131, a second part 132 used to separate the first pole piece 110 and the second pole piece 120, and a second part 132 used to connect the first bent edge. The connection 133 between the edge 131 and the second portion 132 . The diaphragm 130 is bent at the connecting portion 133 .
  • the second portion 132 in the second direction X, is located between the first pole piece 110 and the second pole piece 120 .
  • the first bending edge 131 extends from the connecting portion 133 toward the first axis C of the electrode assembly 100 in the second direction X. At the same time, the first bending edge 131 also extends from the connecting portion 133 toward the electrode assembly 100 in the first direction Z.
  • the first wall 20a of the first housing 20 extends.
  • the first pole piece 110 and the second pole piece 120 are pole pieces in the battery that can perform electrochemical reactions.
  • the first pole piece 110 may be an anode pole piece
  • the second pole piece 120 may be a cathode pole piece.
  • FIG. 7 and FIG. 8 it is a schematic structural diagram of the first pole piece 110 before winding.
  • the first pole piece 110 includes an active material layer 190 and a conductive metal layer 191; the conductive metal layer 191 includes a first region 200 and an empty foil region 210.
  • the fourth direction X' is the direction from the first area 200 to the empty foil area 210
  • the fifth direction Y' is the direction perpendicular to the first pole piece 110
  • the first direction Z is the direction of the aforementioned first axis C.
  • the first direction Z is perpendicular to the fourth direction X' and the fifth direction Y'.
  • the active material layer 190 is disposed on the outer surface of the first region 200 of the conductive metal layer 191, and the conductive portion 140 can be connected to the empty foil region 210 by welding or other methods.
  • Common anode active materials 190 include carbon-based anode materials, silicon-based anode materials, tin-based anode materials, and lithium-containing transition metal nitride anode materials.
  • the conductive metal layer 191 can be copper foil, gold foil, etc.
  • the second pole piece also includes an area containing an active material layer and an empty foil area that does not contain an active material layer.
  • the cathode conductive part can be connected to the empty foil area by welding or other methods.
  • Common cathode active material layers include Lithium cobalt oxide, lithium iron phosphate, lithium manganate, lithium nickel cobalt manganate and lithium nickel cobalt aluminate, etc.
  • the conductive metal layer can be aluminum foil, gold foil, etc.
  • Figure 1 is a cross-sectional view longitudinally cut along the F-F dotted line in Figure 4.
  • the first bending edge 131 of the winding layer far away from the first axis C covers the first bending edge 131 of the winding layer close to the first axis C.
  • the covering means at least partially overlapping in the extending direction of the first axis C.
  • the first bending edge 131 of the winding layer away from the first axis C covers at least part of the first bending edge 131 of the winding layer close to the first axis C.
  • the electrode assembly 100 provided by the embodiment of the present application helps improve the safety performance and reliability of the battery by improving the structure of the separator 130 .
  • multiple winding layers are formed.
  • the first pole piece 110 and the second pole piece 120 are divided into a first layer of first pole piece 110a, a first layer of second pole piece 120a, a second layer of first pole piece 110b, a second layer of second pole piece located on different layers. pole piece 120b, etc., and so on.
  • the first layer of membrane 130a includes the first layer of first bending edges 131a, the first layer of the second part 132a and the first layer of connecting portion 133a;
  • the second layer of membrane 130b includes the second layer of first bending edges 131b, the first layer of connecting parts 133a.
  • the third layer of membrane 130c includes the third layer of the first bending edge 131c, the third layer of the second part 132c and the third layer of connecting part 133c.
  • the first layer second portion 132a of the first layer separator 130a and the second layer There is a first layer of second pole pieces 120a between the second parts 132b. At least a part of the first layer of the first bending edge 131a of the first layer of separator 130a covers the first layer of second pole pieces 120a.
  • the first layer of separator 130a Another part of the first bending edge 131a of the first layer can cover the first bending edge 131b of the second layer separator 130b; the second bending edge 132b of the second separator 130b and the third There is a second layer of first pole pieces 110b between the third layer of second bending edges 132c of the second layer of separator 130c, and at least a part of the second layer of first bending edges 131b of the second layer of separator 130b covers the second layer of first poles.
  • the other part of the second layer of the first bending edge 131b of the second layer of membrane 130b can cover the third layer of the first layer of bending edge 131c of the third layer of membrane 130c, and so on.
  • the electrode assembly 100 of the embodiment of the present application is beneficial to improving the performance of the battery 10 .
  • the width of the separator 130 can also be reduced by bending the separator 130, thereby reducing the space occupied by the separator 130 in the first direction Z of the battery 10, which is beneficial to improving the space utilization of the battery 10.
  • the electrode assembly 100 further includes a conductive part 140.
  • the conductive part 140 includes a first conductive part 141 and a second conductive part 142.
  • the first conductive part 141 and the first pole piece 110 is connected to and extends out of the first pole piece 110
  • the second conductive portion 142 is connected to and extends out of the second pole piece 120 .
  • the first conductive part 141 and/or the second conductive part 142 may be provided on at least one first bent edge 131 in a covering manner. That is, the first conductive part 141 and/or the second conductive part 142 may be in contact with the first bending edge 131 and cover at least part of at least one first bending edge 131 .
  • the conductive part 140 refers to a metal conductor that leads out the electricity of the cathode and the anode from the electrode assembly 100. Charging and discharging the battery 10 can be completed by contacting the conductive parts of the positive and negative poles of the battery. As shown in FIGS. 1 and 4 , the first conductive part 141 is located on the upper surface of the electrode assembly 100 , and the second conductive part 142 is located on the other end of the electrode assembly 100 . The first conductive part 141 is also connected to the first wall 20 a of the first housing 20 , and the second conductive part 142 is also connected to the third wall 21 a of the second housing 21 .
  • the first conductive part 141 may be a cathode tab or an anode tab, and correspondingly, the second conductive part 142 may be an anode tab or a cathode tab.
  • the material of the tab may be aluminum (Al), aluminum alloy, nickel (Ni), etc.
  • the first conductive part 141 is an anode.
  • the material of the tab can be nickel (Ni), copper (Cu), nickel-plated copper (Ni-Cu), copper-nickel alloy, etc.
  • the first conductive part 141 and/or the second conductive part 142 are provided on at least one first bending edge 131 in a covering manner, so that the first bending edge 131 of the diaphragm 130 is also constrained by the tab 140, which is beneficial to further improvement.
  • the folding and thermal shrinkage of the separator 130 is conducive to further improving the performance of the battery 10 .
  • the length of the end of the winding layer bent toward the first axis C is a
  • the length of the two adjacent winding layers away from the first axis C is The overlapping length of the first bending edge 131 of the winding layer C and the first bending edge 131 of the winding layer close to the first axis C is b, 0.6a ⁇ b ⁇ 0.85a.
  • the length a refers to the length of the projection of the first bending edge 131 in the first direction Z in the second direction X
  • the overlap length b refers to the length in the second direction X.
  • the first bending edge 131a of the first layer of membrane 130a covers the second first bending edge 131b of the second layer of membrane 130b by the projection of the length in the first direction Z of the stacked length in the second direction X.
  • the dotted line in which the separator 130 is rolled represents the root of the separator 130 that is blocked by the first bent edge 131 of the separator 130 in the adjacent rolled layer. That is to say, in the top view of FIG.
  • the distance from the dotted line to the second separated solid line is the length a of the first bending edge 131
  • the distance from the dotted line to the separated first solid line is The distance is the length b of the stack. If the length relationship between the two is within this range, the first bent edge 131 can further constrain the separator 130 and reduce the risk of inward shrinkage and folding of the separator 130, which is beneficial to further improving the performance and reliability of the battery 10.
  • the separator 130 includes a base material layer 134 and a ceramic layer 150, and the ceramic layer 150 is disposed on the surface of the base material layer 134.
  • the ceramic layer 150 may be disposed on the surface of the base material layer 134 , which is close to the first pole piece 110 , and the ceramic layer 150 is in contact with the second pole piece 120 .
  • the ceramic layer 150 can be disposed on the surface of the base material layer 134 , which is close to the second pole piece 120 , and the ceramic layer 150 is in contact with the first pole piece 110 .
  • the ceramic layer 150 is simultaneously disposed on the surface of the base material layer 134 close to the first pole piece 110 and the surface of the base material layer 134 close to the second pole piece 120 .
  • the ceramic layer 150 is disposed on the surface of the base material layer 134 in contact with the cathode plate, which can reduce the oxidation effect of the high voltage of the cathode plate on the separator 130 .
  • the ceramic layer includes ceramic materials, and the ceramic materials include aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, At least one of boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate.
  • the separator 130 includes a base material layer 134 and a first adhesive layer 160.
  • the first adhesive layer 160 is disposed on a surface of the base material layer 134 close to the first pole piece 110.
  • the first adhesive layer 160 is disposed on the surface of the base material layer 134 close to the second pole piece 120 .
  • the material of the first adhesive layer 160 can be PVDF (polyvinylidene fluoride) or polyacrylate.
  • the first adhesive layer 160 can be disposed on the surface of the base material layer 134 close to the first pole piece 110.
  • the first adhesive layer 160 is in contact with the second pole piece 120 , or the first adhesive layer 160 can be simultaneously disposed on the surface of the base material layer 134 close to the first pole piece 110 and the surface of the base material layer 134 close to the second pole piece 120 .
  • a porous membrane made of polyethylene (PE) and/or polypropylene (PP) can be used as the base material layer of the separator.
  • the base material layer can also be directly used as the separator.
  • the separator 130 includes a base material layer 134, a ceramic layer 150 and a first adhesive layer 160.
  • the first adhesive layer 160 may be disposed on the base material layer 134 close to the second adhesive layer 160.
  • the ceramic layer 150 is in contact with the second pole piece 120.
  • the first bonding layer 160 may be located outside the ceramic layer 150 , that is, on the side away from the second pole piece 120 along the second direction X. In some embodiments, the ceramic layer 150 may be located outside the first bonding layer 160 .
  • the separator 130 includes a base material layer 134 and a second adhesive layer 170 , and the second adhesive layer 170 is disposed on the base material layer 134 of the first bending edge 131 .
  • the surface 135 facing away from the first pole piece 110 or the second pole piece 120 can be bonded between two adjacent layers of the first bent edge 131 to fix the first bent edge 131 .
  • the material of the second adhesive layer 170 may be PVDF, polyacrylic acid, polyacrylate, polyurethane or styrene-butadiene rubber.
  • the second adhesive layer 170 can be provided by applying glue. By providing the second adhesive layer 170 , it is helpful to fix the separator 130 , improve its folding and heat shrinkage conditions, and maintain the first bending edge 131 in a bent state, thereby improving the performance and reliability of the battery 10 .
  • the second adhesive layer 170 is provided separately from the first conductive part 141 and/or the second conductive part 142, that is, The second adhesive layer 170 is not adhered to the first conductive part 141 and/or the second conductive part 142 . In this way, when the first conductive part 141 and/or the second conductive part 142 vibrate, the risk of the diaphragm 130 being lifted up by the second adhesive layer 170 can be reduced, thereby improving the reliability of the diaphragm 130 .
  • the first adhesive layer 160 is connected to the second adhesive layer 170 .
  • one side surface of the entire separator 130 is covered with an adhesive layer, which on the one hand facilitates the manufacturing process, and on the other hand helps improve the shrinkage of the separator 130, thereby improving the performance and reliability of the battery 10. and improve the integrity of the electrode assembly 100.
  • the second adhesive layer 170 is provided separately from the first pole piece 110 and the second pole piece 120 , that is, the second adhesive layer 170 is not separated from the first pole piece 110 and the second pole piece 120 . 120 bonding.
  • Such arrangement can reduce the situation where the first pole piece 110 and the second pole piece 120 are adhered to the diaphragm 130 through the second adhesive layer 170 , thereby helping to reduce the risk of the first pole piece 110 and the second pole piece 120 damaging the diaphragm 130 risk.
  • the second adhesive layer 170 adheres to the first bent edge of the winding layer away from the first axis C of two adjacent winding layers. 131 and the overlapping area of the first bending edge 131 of the winding layer close to the first axis C. In this way, it is helpful to make the stacking between the plurality of first bending edges 131 more reliable.
  • the second adhesive layer 170 when viewed along the extending direction of the first axis C, completely covers the side surface of the first bent edge 131 away from the first pole piece 110 or the second pole piece 120 . In this way, it is convenient to coat the second adhesive layer 170 on the entire first bent edge 131 .
  • the second adhesive layer 170 when viewed along the extending direction of the first axis C, has an overlapping area with the first conductive part 141 and/or the second conductive part 142 . At this time, the first conductive part 141 and/or the second conductive part 142 are covered on at least one first bending edge 131 through the second adhesive layer 170, which is beneficial to reducing the number of the first conductive part 141 and/or the second conductive part. 142 occupies space in the height direction of the battery, thereby improving the space utilization within the battery 10 .
  • the first pole piece 110 is an anode pole piece
  • the second pole piece 120 is a cathode pole piece
  • the first pole piece 110, the second pole piece 120 and the separator 130 are unfolded, and on the first axis In the extending direction of C, with reference to Figure 9 , the width of the second pole piece 120 is L 1
  • the width of the first pole piece 110 is L 2
  • the width of the diaphragm 130 is L 3
  • the width of the diaphragm 130 and the first pole piece 110 is L 3 .
  • the separator 130 is beneficial to separate the cathode pole piece and the anode pole piece, which is conducive to reducing manufacturing difficulty and the risk of cathode and anode short circuit. It is also conducive to bending the separator 130 and enabling higher energy density.
  • the separator 130 includes a base material layer 134.
  • the base material layer is a single-layer film or a multi-layer composite film.
  • the material of the base material layer includes at least one of polypropylene (PP) or polyethylene (PE).
  • PP polypropylene
  • PE polyethylene
  • the separator can be PE separator, PP separator or PP/PE/PP composite separator (that is, three layers of PP, PE, and PP are stacked in sequence).
  • the separator 130 made of the above materials can isolate the cathode plate and the anode plate and prevent the electrons in the battery from freely passing through, allowing the ions of the battery 10 to freely pass between the cathode and the anode.
  • separators 130 of different materials Since the thermal shrinkage of separators 130 of different materials is different, using a separator 130 of a material with smaller thermal shrinkage (such as PP) will help reduce the risk of size shrinkage of the first bent edge 131 , thereby further improving the performance of the battery 10 Performance and reliability.
  • a material with smaller thermal shrinkage such as PP
  • a second aspect of the present application provides a button battery 10, including the electrode assembly 100 as described above.
  • the electrode assembly 100 in the process of stacking the first pole piece 110, the second pole piece 120 and the separator 130 and winding them around the first axis C, the electrode assembly 100 will form a multi-layer winding. layer, the ends of the separators 130 in the multiple winding layers are bent toward the first axis C to form a plurality of first bending edges 131, and in the two adjacent winding layers, the ends of the separators 130 in the multiple winding layers are bent away from the first axis C The first bending edge 131 of the winding layer covers the first bending edge 131 of the winding layer close to the first axis C.
  • the electrode assembly 100 of the embodiment of the present application is beneficial to improving the performance of the battery 10 .
  • the width of the separator 130 can also be reduced by bending the separator 130, thereby reducing the space occupied by the separator 130 in the extending direction of the first axis of the button battery 10, which is beneficial to improving the space utilization of the button battery 10.
  • the battery 10 further includes an insulating layer, which is obtained by injecting an insulating material into the accommodation space and curing.
  • the insulating layer at least partially covers the electrode assembly 100, and the insulating layer does not contact the first conductive portion 141 and/or the second conductive portion 142 in the electrode assembly 100.
  • the insulating layer is used to fix the electrode assembly 100.
  • insulating materials include but are not limited to insulating glue, insulating resin, etc.
  • the third aspect of this application provides a manufacturing method for button batteries, including:
  • the ends of the multiple winding layers formed by winding the separator 130 are all bent toward the first axis C to form a plurality of first bending edges 131; wherein, among the two adjacent winding layers, the end portions of the winding layers are further away from the first axis C.
  • the first bending edge 131 of the winding layer of an axis C covers the first bending edge 131 of the winding layer close to the first axis C.
  • the electrode assembly 100 is in the process of winding the first pole piece 110 , the second pole piece 120 and the separator 130 around the first axis C. Multiple winding layers will be formed, and the ends of the separators 130 in the multiple winding layers are bent toward the first axis C to form a plurality of first bending edges 131, and in two adjacent winding layers, The first bending edge 131 of the winding layer away from the first axis C is covered with the first bending edge 131 of the winding layer close to the first axis C.
  • the electrode assembly 100 of the embodiment of the present application is beneficial to improving the performance of the button battery 10 .
  • the width of the separator 130 can also be reduced by bending the separator 130, thereby reducing the space occupied by the separator 130 in the extending direction of the first axis C of the button battery 10, which is beneficial to improving the space utilization of the button battery 10.
  • the length of the end of the winding layer bent toward the first axis C is a; in the two adjacent winding layers, the length that is far away from the first axis C
  • the overlapping length of the winding layer C and the winding layer close to the first axis C is b; 0.6a ⁇ b ⁇ 0.85a.
  • the relationship between the two is within this range, and the first bent edge 131 can constrain the inward shrinkage and folding of the separator 130, which is beneficial to further improving the performance and reliability of the button battery 10.
  • the shaping mechanism 180 can be used to apply a temperature field, or pressure, or both a temperature field and pressure to the surface of the bent first bending edge 131 , that is, The hot pressing process is used to bond the first bending edges 131 of the diaphragm 130 between each compartment, which is beneficial to improving the shrinkage of the diaphragm 130 and reducing the risk of the first bending edge 131 of the diaphragm 130 folding outwards. , which is conducive to further improving the performance and reliability of the button battery 10 .
  • the shaping mechanism 180 of the present application is not particularly limited, and any shaping mechanism in the field can be used. This application has no special restrictions on the hot pressing process, and the hot pressing process in this field can be used.
  • the button battery of Comparative Example 1 was produced according to the following process:
  • the primer coating is formed by mixing SP, CMC and SBR according to the mass ratio of 60:5:35 and then coating it on the two surfaces of the current collector through the gravure coating method.
  • the base material layer of a single-layer film made of polyethylene (PE) is selected as the separator.
  • the thickness of the separator is 16 ⁇ m
  • the width of the separator is 6.1 mm
  • the difference in width between the separator and the anode plate is 1.6 mm.
  • the above-mentioned anode pole pieces, separators, and cathode pole pieces are stacked in order, so that the distance beyond the anode pole piece on both sides of the width direction of the separator is even and the distance beyond the cathode pole piece on both sides of the width direction of the anode pole is even, and then along the first axis
  • the electrode assembly is made by winding, and then goes through steps such as packaging, liquid injection, standing, formation and volume separation to obtain a button battery.
  • the difference from Comparative Example 1 is that the width of the separator is 5.3 mm, and the difference in width between the separator and the anode plate is 0.8 mm.
  • Comparative Example 1 The difference from Comparative Example 1 is that the width of the separator is 5.5 mm, and the difference in width between the separator and the anode plate is 1.0 mm.
  • the difference from Comparative Example 1 is that the width of the separator is 5.7 mm, and the difference in width between the separator and the anode plate is 1.2 mm.
  • Comparative Example 1 The difference from Comparative Example 1 is that the width of the separator is 5.9 mm, and the difference in width between the separator and the anode plate is 1.4 mm.
  • Comparative Example 1 The difference from Comparative Example 1 is that the width of the separator is 6.3 mm, and the difference in width between the separator and the anode plate is 1.8 mm.
  • the difference from Comparative Example 1 is that the width of the separator is 6.5 mm, and the difference in width between the separator and the anode plate is 2.0 mm.
  • the difference from Comparative Example 1 is that the width of the separator is 6.7 mm, and the difference in width between the separator and the anode plate is 2.2 mm.
  • the difference from Comparative Example 1 is that after the electrode assembly is made, a shaping mechanism is used to apply pressure to the electrode assembly in the extending direction of the first axis, so that the separator is bent toward the first axis to form a plurality of first bending edges. And among the two adjacent separator winding layers, the first bending edge of the winding layer far away from the first axis covers the first bending edge of the winding layer close to the first axis.
  • the diaphragm can be adjusted by The formation and size of the first bending edge are controlled by the width difference between the anode pole piece and the cathode pole piece, or the pressure exerted by the shaping mechanism.
  • the length a of the end of the winding layer bent toward the first axis is 800 ⁇ m.
  • Example 2 The difference from Example 1 is that a single-layer film made of polypropylene (PP) is used as the separator.
  • PP polypropylene
  • Example 1 The difference from Example 1 is that a three-layer film of PP/PE/PP materials laminated in sequence is selected as the separator.
  • Example 1 The difference from Example 1 is that the surface of one side of the base material layer is coated with a ceramic coating of three surface thicknesses (95% by weight of boehmite and 5% by weight of polyvinylidene fluoride).
  • Example 2 The difference from Example 1 is that a polyvinylidene fluoride coating with a thickness of 3 substrates is coated on the surface of the first bent edge of the substrate layer facing the first axis as an adhesive layer.
  • Voltage loss OCV 1 -OCV 2 , 10 batteries were measured for each example and comparative example, and the average value was calculated.
  • the voltage loss of the battery is less than 50mV, it means that the probability of short circuit inside the button battery is low and acceptable; when the voltage loss is less than 20mV, it means that there is no short circuit in the battery and there is no risk. The smaller the voltage loss, the better the performance of the battery.
  • Example 9 to Example 10 the material of the base material layer and whether there is a ceramic layer or an adhesive layer on the surface of the base material layer usually have an impact on the performance of the battery. It can be seen from Example 9 and Example 1 that this application can further reduce the voltage loss value of the battery and improve the performance and reliability of the battery by selecting a PP material with better heat shrinkage resistance as the separator. It can be seen from Example 10 and Example 1 that this application can further reduce the voltage loss value of the battery and improve the performance and reliability of the battery by selecting a separator made of PP/PE/PP multi-layer composite material.
  • Example 11 and Example 1 the present application can further reduce the voltage loss value of the battery and improve the performance and reliability of the battery by arranging a ceramic layer on the surface of the base material layer. It can be seen from Example 12 and Example 1 that the present application can further reduce the voltage loss value of the battery and improve the performance and reliability of the battery by providing an adhesive layer on the surface of the base material layer.

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Abstract

本申请提供了一种电极组件、纽扣电池及纽扣电池的制造方法，电极组件包括第一极片、第二极片及隔膜，第二极片与第一极片的极性相反；隔膜设置于第一极片与第二极片之间；第一极片、隔膜以及第二极片层叠并绕第一轴线进行卷绕；隔膜卷绕而形成的多个卷绕层的端部朝向第一轴线弯折以形成多个第一弯折边；相邻的两个卷绕层中远离第一轴线的卷绕层的第一弯折边覆盖在靠近第一轴线的卷绕层的第一弯折边上。本申请的电极组件的第一弯折边可以约束隔膜向内收缩以及翻折，降低出现阴极片与阳极片短路的风险，第一弯折边还可以限制第一极片和第二极片之间的相对偏移，改善局部析锂及放电容量损失。因此本申请实施例的电极组件有利于提高纽扣电池的性能。

Description

一种电极组件、纽扣电池及纽扣电池的制造方法 技术领域
本申请涉及电池技术领域，特别涉及一种电极组件、纽扣电池及纽扣电池的制造方法。
背景技术
二次电池如纽扣电池由于具有电池体积小，储电容量大、使用轻便等优点，在计算机、助听器、收音机、电子手表等各种精密和便携式设备中得到了广泛应用。
目前，采用卷绕方式制成的纽扣电池，通常包括上壳、下壳，以及将阴极极片、隔膜和阳极极片层叠并卷绕在一起形成的电极组件。
但是卷绕形成的电极组件中，阴极极片和阳极极片可能在外力作用下(如振动等)发生相对偏移，引起局部析锂或放电容量损失，导致二次电池性能下降；并且阴极极片和阳极极片之间的隔膜也可能在高温下发生收缩、翻折，从而发生阴极极片与阳极极片短路的情况，进而可能降低二次电池的性能。
发明内容
本申请的目的在于提供一种电极组件、纽扣电池及纽扣电池的制造方法，以提高纽扣电池的性能。具体技术方案如下：
本申请第一方面提供了一种电极组件，其包括第一极片、第二极片和隔膜。第二极片与第一极片的极性相反，隔膜设置于第一极片与第二极片之间，第一极片、隔膜以及第二极片层叠并绕第一轴线进行卷绕；隔膜卷绕而形成的多个卷绕层的端部朝向第一轴线弯折以形成多个第一弯折边；相邻的两个卷绕层中，远离第一轴线的卷绕层的第一弯折边覆盖在靠近第一轴线的卷绕层的第一弯折边上。
本申请提供的电极组件，通过将隔膜卷绕成的多个卷绕层的端部朝向第一轴线弯折，以形成多个第一弯折边；并且在相邻的两个卷绕层中，将远离第一轴线的卷绕层的第一弯折边覆盖在靠近第一轴线的卷绕层的第一弯折边上，可以约束隔膜，减小隔膜向内收缩以及翻折的风险，有利于降低第一极片和第二极片出现短路的风险；并且第一弯折边还可以限制第一极片和第二极片之间的相对偏移，改善局部析锂及放电容量损失。
在本申请的一些实施例中，电极组件还包括第一导电部和第二导电部，其中第一导电部与第一极片相连，第二导电部与第二极片相连；第一导电部和/或第二导电部覆盖在至少一个第一弯折边上。这样，隔膜的第一弯折边可以受到第一导电部和/或第二导电部的约束， 有利于进一步改善隔膜翻折及热收缩的问题，从而有利于进一步提高电池的性能。另外，第一导电部和/或第二导电部覆盖在至少一个第一弯折边上，还有利于减少第一导电部和/或第二导电部在电池的第一轴线的延伸方向上的占用空间，进而利于提高电池内的空间利用率，进而提升能量密度。
在本申请的一些实施例中，卷绕层的端部朝向第一轴线弯折的长度为a；相邻的两个卷绕层中，远离第一轴线的卷绕层的第一弯折边与靠近第一轴线的卷绕层的第一弯折边的重叠长度为b，0.6a≤b≤0.85a。二者之间的关系在这个范围内，有利于进一步提高电池的安全性和可靠性。
在本申请的一些实施例中，隔膜包括基材层和陶瓷层，陶瓷层设置在基材层靠近第一极片的表面，和/或陶瓷层设置在基材层靠近第二极片的表面。通过设置陶瓷层，有利于改善隔膜收缩的状况，进而有利于提高电池的安全性和可靠性。
在本申请的一些实施例中，隔膜包括基材层和第一粘接层，第一粘接层设置在基材层靠近第一极片的表面，和/或第一粘接层设置在基材层靠近第二极片的表面。通过设置第一粘结层，有利于改善隔膜收缩的状况，进而有利于提高电池的安全性和可靠性。
在本申请的一些实施例中，隔膜包括基材层以及第二粘接层，第二粘接层设置在第一弯折边的基材层的背离第一极片或第二极片的表面，以固定第一弯折边。这样设置，有利于使第一弯折边维持弯折状态，进而利于提高电池的安全性和可靠性。
在本申请的一些实施例中，第二粘接层与第一导电部和第二导电部相分离设置。这样，可以降低第一导电部和第二导电部振动时通过第二粘结层带动隔膜运动的风险，进而有利于提高隔膜的可靠性。
在本申请的一些实施例中，第一粘接层与第二粘接层连接。这样，整个隔膜上均覆盖有粘结层，一方面有利于方便工艺制造，另一方面，有利于改善隔膜收缩的问题，进而有利于提高电池的安全性和可靠性。
在本申请的一些实施例中，第二粘接层与第一极片及第二极片相分离设置。这样设置，有利于节省成本，以及降低第二粘接层对于第一极片和第二极片之间电化学反应的影响。
在本申请的一些实施例中，沿第一轴线的延伸方向观察，第二粘接层粘接相邻两个卷绕层中远离第一轴线的卷绕层的第一弯折边与靠近第一轴线的卷绕层的第一弯折边的重叠区域。这样，有利于使相邻的两个第一弯折边之间的层叠更为可靠。
在本申请的一些实施例中，沿第一轴线的延伸方向观察，第二粘接层完全覆盖第一弯 折边背离第一极片或第二极片的一侧表面。这样，有利于方便对整体的第一弯折边涂覆第二粘结层。
在本申请的一些实施例中，第二粘接层粘接第一导电部和/或第二导电部。此时，第一导电部和/或第二导电部通过第二粘结层覆盖在至少一个第一弯折边上，有利于减少两个导电部在第一轴线的延伸方向上的占用空间，进而利于提高电池内的空间利用率，也有利于固定第一导电部或第二导电部，降低第一导电部或第二导电部蹿动的风险。
在本申请的一些实施例中，第一极片为阳极极片，第二极片为阴极极片；在第一轴线的延伸方向上，隔膜与第一极片的宽度之差为0.8mm～2.0mm，第一极片与第二极片的宽度之差为0mm～1mm。这样，有利于使隔膜更好地分隔阴极极片与阳极极片，也有利于对隔膜进行折弯处理，有利于平衡安全性和能量密度。
在本申请的一些实施例中，隔膜包括基材层，基材层为单层膜或多层复合膜。基材层的材料包括聚丙烯或聚乙烯中的至少一种。由上述材料制备的隔膜可以隔离第一极片、第二极片，并使电化学反应中电子不能自由穿过，让电化学反应中的离子在第一极片和第二极片之间自由通过。在本申请的一些实施例中，基材层为单层聚丙烯膜。不同材料的隔膜的热收缩性具有差异，采用热收缩性较小的材料的隔膜有利于降低第一弯折边的尺寸收缩的风险，从而进一步提高安全性和可靠性。
在本申请的一些实施例中，电极组件为柱形。如此，有利于隔膜的弯折形成多个第一弯折边。
本申请第二方面提供了一种纽扣电池，包括上述第一方面的电极组件。
本申请实施例提供的纽扣电池，其内的电极组件通过将隔膜卷绕成的多个卷绕层的端部朝向第一轴线弯折以形成多个第一弯折边；并且在相邻的两个卷绕层中，将远离第一轴线的卷绕层的第一弯折边覆盖在靠近第一轴线的卷绕层的第一弯折边上，可以约束隔膜，降低隔膜向内收缩以及翻折的风险，有利于降低第一极片和第二极片出现短路的概率；并且第一弯折边还可以限制第一极片和第二极片之间的相对偏移，改善局部析锂及放电容量损失。
因此，本申请的电极组件应用于纽扣电池中还有利于提高纽扣电池的性能。此外，通过隔膜的弯折还可以降低隔膜的宽度，减小隔膜在纽扣电池第一轴线延伸方向上占用的空间，有利于提高纽扣电池的空间利用率。
本申请第三方面提供了一种纽扣电池的制造方法，包括：将第一极片、隔膜和第二极 片层叠并绕第一轴线进行卷绕；将隔膜卷绕成的多个卷绕层的端部均朝向第一轴线弯折，以形成多个第一弯折边；其中，相邻的两个卷绕层中，远离第一轴线的卷绕层的第一弯折边覆盖在靠近第一轴线的卷绕层的第一弯折边上。
通过本申请的纽扣电池的制造方法制造出的纽扣电池，其内的电极组件通过将隔膜卷绕成的多个卷绕层的端部朝向第一轴线弯折，以形成多个第一弯折边；并且在相邻的两个卷绕层中，将远离第一轴线的卷绕层的第一弯折边覆盖在靠近第一轴线的卷绕层的第一弯折边上，可以约束隔膜，降低隔膜向内收缩以及翻折的风险，有利于降低第一极片和第二极片出现短路的风险；并且第一弯折边还可以限制第一极片和第二极片之间的相对偏移，改善局部析锂及放电容量损失。因此，本申请实施例的纽扣电池有利于提高纽扣电池的性能。
此外，通过隔膜的弯折还可以降低隔膜的宽度，减小隔膜在纽扣电池第一轴线延伸方向上占用的空间，有利于提高纽扣电池的空间利用率。
在本申请的一些实施例中，卷绕层的端部朝向第一轴线弯折的长度为a；相邻的两个卷绕层中，远离第一轴线的卷绕层的第一弯折边与靠近第一轴线的卷绕层的第一弯折边的重叠长度为b，0.6a≤b≤0.85a。二者之间的关系在这个范围内，有利于进一步提高纽扣电池的安全性和可靠性。
在本申请的一些实施例中，所述方法还包括对第一弯折边的进行加热处理。这样，可以使相邻的两层第一弯折边粘结在一起，从而有利于改善隔膜收缩的情况，同时还有利于使第一弯折边维持弯折状态，降低隔膜的第一弯折边向外翻折的风险。
附图说明
为了更清楚地说明本申请的技术方案，下面对实施例中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，还可以根据这些附图获得其他的实施例。
图1是本申请实施例的电池的纵向剖面示意图；
图2a是本申请一种实施方式中图1中D处的局部放大示意图；
图2b是本申请另一种实施方式中图1中D处的局部放大示意图；
图2c是本申请再一种实施方式中图1中D处的局部放大示意图；
图3a是本申请一种实施方式中图1中E处的放大示意图；
图3b是本申请另一种实施方式中图1中E处的放大示意图；
图4是本申请一些实施例中的一种电池的俯视图；
图5是本申请一些实施例中的一种电极组件中隔膜弯折后进行平面热压的示意图；
图6是本申请一些实施例中的一种电极组件制作方法的流程图；
图7是本申请实施例的第一极片或第二极片卷绕前的结构示意图；
图8是本申请实施例的第一极片或第二极片卷绕前的俯视图；
图9是本申请实施例的第一极片、第二极片、隔膜的示意图。
附图标记：
电池-10；第一壳体-20；第二壳体-21；第一壁-20a；第二壁-20b；第三壁-21a；第四壁-21b；电极组件-100；第一极片-110；第二极片-120；第一层第一极片-110a；第一层第二极片-120a；第二层第一极片-110b；隔膜-130；第一轴线-C；第一弯折边-131；第二部分-132；连接部-133；基材层-134；第一层隔膜-130a；第一层第一弯折边-131a；第一层第二部分-132a；第一层连接部-133a；第二层隔膜-130b；第二层第一弯折边-131b；第二层第二部分-132b；第二层连接部-133b；第三层隔膜-130c；第三层第一弯折边-131c；第三层第二部分-132c；第三层连接部-133c；侧面-135；导电部-140；第一导电部-141；第二导电部-142；陶瓷层-150；第一粘结层160；第二粘接层-170；整形机构-180；活性物质层-190；导电金属层-191；第一区域-200；空箔区-210。
具体实施方式
下面对本申请实施例中的技术方案进行清楚、详细地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。除非另有定义，本文所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同。在本申请的说明书中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请。
下文，将详细地描述本申请的实施方式。但是，本申请可体现为许多不同的形式，并且不应解释为限于本文阐释的示例性实施方式。而是，提供这些示例性实施方式，从而使本申请透彻的和详细的向本领域技术人员传达。
另外，为了简洁和清楚，在附图中，各种组件、层的尺寸或厚度可被放大。遍及全文，相同的数值指相同的要素。如本文所使用，术语“及/或”、“以及/或者”包括一个或多个相关列举项目的任何和所有组合。另外，应当理解，当要素A被称为“连接”要素B时，要素A可直接连接至要素B，或可能存在中间要素C并且要素A和要素B可彼此间接连接。
进一步，当描述本申请的实施方式时使用“可”指“本申请的一个或多个实施方式”。
本文使用的专业术语是为了描述具体实施方式的目的并且不旨在限制本申请。如本文所使用，单数形式旨在也包括复数形式，除非上下文另外明确指出。应进一步理解，术语“包括”，当在本说明书中使用时，指存在叙述的特征、数值、步骤、操作、要素和/或组分，但是不排除存在或增加一个或多个其他特征、数值、步骤、操作、要素、组分和/或其组合。
空间相关术语，比如“上”等可在本文用于方便描述，以描述如图中阐释的一个要素或特征与另一要素(多个要素)或特征(多个特征)的关系。应理解，除了图中描述的方向之外，空间相关术语旨在包括设备或装置在使用或操作中的不同方向。例如，如果将图中的设备翻转，则描述为在其他要素或特征“上方”或“上”的要素将定向在其他要素或特征的“下方”或“下面”。因此，示例性术语“上”可包括上面和下面的方向。应理解，尽管术语第一、第二、第三等可在本文用于描述各种要素、组分、区域、层和/或部分，但是这些要素、组分、区域、层和/或部分不应受这些术语的限制。这些术语用于区分一个要素、组分、区域、层或部分与另一要素、组分、区域、层或部分。因此，下面讨论的第一要素、组分、区域、层或部分可称为第二要素、组分、区域、层或部分，而不背离示例性实施方式的教导。在本申请中，第一方向可为第一表面所在平面中的任意一方向。
需要说明的是，在本文中，诸如“第一”、“第二”、“第三”和“第四”等之类的关系术语仅仅用来将一个实体与另一个实体区分开来，而不一定要求或者暗示这些实体之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其它变体意在涵盖非排他性的包含，从而使得包括一系列要素的物品或者设备不仅包括那些要素，而且还包括没有明确列出的其它要素，或者是还包括为这种物品或者设备所固有的要素。
本说明书中的各个实施例均采用相关的方式描述，各个实施例之间相同相似的部分互相参见即可，每个实施例重点说明的都是与其它实施例的不同之处。
下面对本申请的一些实施方式作详细说明。在不冲突的情况下，下述的实施例及实施例中的特征可以相互组合。相关技术中，采用卷绕方式制成的纽扣电池，通常包括上壳、下壳，以及将阴极极片、隔膜和阳极极片层叠并卷绕在一起形成的电极组件。但是卷绕形成的电极组件中，阴极极片和阳极极片可能在外力作用下(如振动等)发生相对偏移，引起局部析锂及放电容量损失，导致纽扣电池性能下降；并且阴极极片和阳极极片之间的隔膜也可能在高温下发生收缩、翻折，从而可能发生阴极极片与阳极极片短路的情况，进而可能降低纽扣电池的安全性能。
为了改善纽扣电池的安全性能，本申请实施例提供了一种电极组件、纽扣电池及纽扣 电池的制造方法。具体技术方案如下：
如图1和图4所示，图1为图4中沿F-F虚线纵向剖开的剖面图，本申请第一方面提供了一种电极组件100，包括第一极片110、第二极片120以及隔膜130，第二极片120与第一极片110的极性相反；隔膜130设置于第一极片110与第二极片120之间；第一极片110、隔膜130以及第二极片120以第一轴线C为中心进行卷绕；从纵向剖面上观察，隔膜130卷绕而形成的多个卷绕层的端部朝向第一轴线C弯折，以形成多个第一弯折边131。在本申请实施例中，定义第一轴线C延伸的方向为第一方向Z，且将垂直于第一方向Z的两个方向定义为第二方向X和第三方向Y，第二方向X与第三方向Y相互垂直。本申请实施例中，第一轴线C是指获取电池的截面，得到截面图形的外接圆，外接圆圆心即为第一轴线C在截面上投影的点，圆心在第一方向Z上的延伸方向即为第一轴线C。
本申请还提供一种电池10。在本申请的一些实施例中，电池10可以为纽扣电池，纽扣电池通常具有相对于常规方形电池、圆柱电池等较小的体积。在本申请的一些实施例中，电极组件100具有柱形外形，有利于第一弯折边131的设置。在一些实施例中，电极组件100具有圆柱形外形，即电极组件100的垂直于第一轴线C的截面呈现圆形。在一些实施例中，如图1所示，电池10包括第一壳体20和第二壳体21，第一壳体20与第二壳体21连接形成容纳空间，电极组件100置于容纳空间内。第一壳体20及第二壳体21用于对电极组件100进行保护，降低外部物体对电极组件100的影响。第一壳体20在第一方向Z上具有与电极组件100相对的第一壁20a以及从第一壁20a向第一方向Z延伸的第二壁20b。从第一方向Z上观察，电极组件100可以被第二壁20b包围。第二壳体21在第一方向Z上具有与电极组件100相对的第三壁21a以及从第三壁21a向第一方向Z延伸的第四壁21b。从第一方向Z上观察，电极组件100可以被第四壁21b包围。
隔膜130是指一种用来分隔第一极片110和第二极片120，以降低第一极片110和第二极片120内部短路的风险，并使离子可以自由通过以形成离子通路的部件。沿第三方向Y观察，隔膜130经过折弯后可分为第一弯折边131、用于分隔第一极片110和第二极片120的第二部分132以及用于连接第一弯折边131和第二部分132的连接部133。隔膜130在连接部133处弯折。在一些实施例中，在第二方向X上，第二部分132位于第一极片110和第二极片120之间。第一弯折边131在第二方向X上从连接部133向电极组件100的第一轴线C延伸，同时，第一弯折边131在第一方向Z上还从连接部133向电极组件100的第一壳体20的第一壁20a延伸。
第一极片110和第二极片120即为电池内的可以进行电化学反应的极片。在一些实施例中，第一极片110可以是阳极极片，第二极片120可以是阴极极片。如图7和图8所示，为第一极片110卷绕前的结构示意图。第一极片110包括活性物质层190以及导电金属层191；导电金属层191包括第一区域200以及空箔区210。其中，第四方向X’为第一区域200至空箔区210的方向，第五方向Y’为垂直于第一极片110的方向，第一方向Z即为前述的第一轴线C的方向，且第一方向Z垂直于第四方向X‘与第五方向Y’。活性物质层190设置于导电金属层191的第一区域200的外表面，导电部140可以通过焊接等方式连接于空箔区210。常见的阳极活性物质190包括碳类阳极材料、硅基阳极材料、锡基阳极材料和含锂过渡金属氮化物阳极材料等。导电金属层191可以为铜箔、金箔等。
可以理解的是，第二极片也包括含有活性物质层的区域，以及不含有活性物质层的空箔区，阴极导电部可以通过焊接等方式连接于空箔区，常见的阴极活性物质层包括钴酸锂、磷酸铁锂、锰酸锂、镍钴锰酸锂和镍钴铝酸锂等。此时，导电金属层可以为铝箔、金箔等。
如图1所示，图1为图4中沿F-F虚线纵向剖开的剖面图。从第三方向Y上观察，相邻的两个卷绕层中，远离第一轴线C的卷绕层的第一弯折边131覆盖在靠近第一轴线C的卷绕层的第一弯折边131上。所述覆盖是指在第一轴线C的延伸方向上至少部分重叠。具体地，远离第一轴线C的卷绕层的第一弯折边131覆盖靠近第一轴线C的卷绕层的第一弯折边131的至少部分。
本申请实施例提供的电极组件100，通过改善隔膜130的结构以有利于提高电池的安全性能和可靠性。电极组件100在将第一极片110、第二极片120和隔膜130绕第一轴线C进行卷绕的过程中，会形成多层卷绕层。如图1所示，在第二方向X上，隔膜130被多个卷绕层依次分割出位于不同层的第一层隔膜130a、第二层隔膜130b、第三层隔膜130c等，以此类推。第一极片110和第二极片120被分割为位于不同层的第一层第一极片110a、第一层第二极片120a、第二层第一极片110b、第二层第二极片120b等，以此类推。因此，第一层隔膜130a包括第一层第一弯折边131a、第一层第二部分132a以及第一层连接部133a；第二层隔膜130b包括第二层第一弯折边131b、第二层第二部分132b以及第二层连接部133b；第三层隔膜130c包括第三层第一弯折边131c、第三层第二部分132c以及第三层连接部133c等。具体地，在相邻的两个卷绕层中，如图1所示，在第二方向X上，第一层隔膜130a的第一层第二部分132a与第二层隔膜130b的第二层第二部分132b之间具有第一层第二极片120a，第一层隔膜130a的至少一部分的第一层第一弯折边131a覆盖第 一层第二极片120a，第一层隔膜130a的第一层第一弯折边131a的另一部分可以覆盖在第二层隔膜130b的第二层第一弯折边131b上；第二层隔膜130b的第二层第二弯折边132b与第三层隔膜130c的第三层第二弯折边132c之间具有第二层第一极片110b，第二层隔膜130b的至少一部分的第二层第一弯折边131b覆盖第二层第一极片110b，第二层隔膜130b的第二层第一弯折边131b的另外一部分可以覆盖在第三层隔膜130c的第三层第一弯折边131c上，以此类推。这样，通过将不同卷绕层的隔膜130的第一弯折边131层叠的设置，可以约束隔膜130向内收缩以及翻折，有利于降低第一极片110和第二极片120出现短路的概率。并且第一弯折边131还可以限制第一极片110和第二极片120之间的相对偏移，还有利于改善局部析锂及放电容量损失。因此，本申请实施例的电极组件100有利于提高电池10的性能。
此外，通过隔膜130的弯折还可以降低隔膜130的宽度，减小隔膜130在电池10在第一方向Z上占用的空间，有利于提高电池10的空间利用率。
如图1所示，在本申请的一些实施例中，电极组件100还包括导电部140，导电部140包括第一导电部141和第二导电部142，第一导电部141与第一极片110相连并延伸出第一极片110，第二导电部142与第二极片120相连并延伸出第二极片120。第一导电部141和/或第二导电部142可以覆盖地设置在至少一个第一弯折边131上。即第一导电部141和/或第二导电部142可以与第一弯折边131接触并覆盖至少一个第一弯折边131的至少部分。导电部140是指从电极组件100中将阴极和阳极的电性引出来的金属导电体，通过接触电池上正负两极的导电部可以完成对电池10的充放电。如图1和图4所示，第一导电部141位于电极组件100的上表面，第二导电部142位于电极组件100的另一端。第一导电部141还与第一壳体20的第一壁20a连接，第二导电部142还与第二壳体21的第三壁21a连接。其中，第一导电部141可以为阴极极耳或阳极极耳，相应地，第二导电部142可以为阳极极耳或阴极极耳。在本实施例中，第二导电部142为阴极极耳时，极耳的材料可以为铝(Al)、铝合金、镍(Ni)等，在本实施例中，第一导电部141为阳极极耳时，极耳的材料可以为镍(Ni)、铜(Cu)、铜镀镍(Ni—Cu)、铜镍合金等。
将第一导电部141和/或第二导电部142覆盖地设置在至少一个第一弯折边131上，这样隔膜130的第一弯折边131还受到极耳140的约束，有利于进一步改善隔膜130翻折及热收缩的状况，从而有利于进一步提高电池10的性能。另外，还有利于减少极耳140在第一方向Z上的占用空间，进而利于提高电池10内的空间利用率。
如图3a和图3b所示，在本申请的一些实施例中，卷绕层的端部朝向第一轴线C弯折的长度为a，相邻的两个卷绕层中，远离第一轴线C的卷绕层的第一弯折边131与靠近第一轴线C的卷绕层的第一弯折边131的重叠长度为b，0.6a≤b≤0.85a。
本申请实施例中，如图1所示，长度a是指第一弯折边131的第一方向Z上的投影在第二方向X上的长度，重叠长度b是指在第二方向X上第一层隔膜130a的第一弯折边131a覆盖在第二层隔膜130b的第二第一弯折边131b上的层叠的长度的第一方向Z上的投影在第二方向X上的长度。在图4中，隔膜130卷绕的虚线表示被相邻卷绕层的隔膜130的第一弯折边131所遮挡的隔膜130的根部。也就是说，在图4的俯视图中，从第一方向Z观察，虚线至相隔的第二个实线的距离为第一弯折边131的长度a，虚线至相隔的第一个实线的距离为层叠的长度b。二者之间的长度关系在这个范围内，第一弯折边131能够进一步约束隔膜130，减小隔膜130向内收缩以及翻折的风险，有利于进一步提高电池10的性能及可靠性。
在本申请的一些实施例中，如图2a所示，隔膜130包括基材层134和陶瓷层150，陶瓷层150设置在基材层134的表面。通过设置陶瓷层150，有利于改善隔膜130收缩的状况，进而有利于提高电池10的性能及可靠性。其中，陶瓷层150可以设置在基材层134的表面，该基材层134靠近第一极片110，陶瓷层150与第二极片120接触连接。或者陶瓷层150可以设置在基材层134的表面，该基材层134靠近第二极片120，陶瓷层150与第一极片110接触连接。或者陶瓷层150同时设置在基材层134靠近第一极片110的表面以及基材层134靠近第二极片120的表面。陶瓷层150设置在基材层134与阴极极片接触的表面，可以降低阴极极片的高电压对隔膜130的氧化作用。陶瓷层包括陶瓷材料，陶瓷材料包括氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡中的至少一种。
在本申请的一些实施例中，如图2b所示，隔膜130包括基材层134和第一粘接层160，第一粘接层160设置在基材层134靠近第一极片110的表面，和/或第一粘接层160设置在基材层134靠近第二极片120的表面。通过设置第一粘结层160，可以增加隔膜130与极片之间的粘结力，也有利于改善隔膜130收缩的状况，进而有利于提高电池10的性能及可靠性。第一粘结层160的材料可以是PVDF(聚偏氟乙烯)或聚丙酸酯，第一粘接层160可以设置在基材层134的靠近第一极片110的表面，第一粘接层160与第二极片120接触 连接，或者第一粘接层160可以同时设置在基材层134靠近第一极片110的表面以及基材层134靠近第二极片120的表面。本申请实施例中，可以选用聚乙烯(PE)和/或聚丙烯(PP)材质的多孔膜作为隔膜的基材层，当然，也可以直接将该基材层作为隔膜使用。
在本申请的一些实施例中，如图2c所示，隔膜130包括基材层134、陶瓷层150和第一粘接层160，第一粘接层160可以设置在基材层134靠近第二极片120的表面，陶瓷层150与第二极片120接触连接。在一些实施例中，第一粘结层160可以位于陶瓷层150的外侧，即沿第二方向X背离第二极片120的一侧。在一些实施例中，陶瓷层150可以位于第一粘结层160的外侧。
在本申请的一些实施例中，如图1所示，隔膜130包括基材层134和第二粘接层170，第二粘接层170设置在第一弯折边131的基材层134的背离第一极片110或第二极片120的表面135，可以粘接于第一弯折边131相邻的两层之间，以固定第一弯折边131。第二粘接层170的材料可以是PVDF、聚丙烯酸、聚丙烯酸酯、聚氨酯或丁苯橡胶等。可以采用涂胶的方式设置第二粘结层170。通过设置第二粘接层170，有利于固定隔膜130，改善其翻折和热收缩的状况，使第一弯折边131维持弯折状态，进而利于提高电池10的性能及可靠性。
在本申请的一些实施例中，沿第一轴线C的延伸方向(即第一方向Z)，第二粘接层170与第一导电部141和/或第二导电部142相分离设置，即第二粘结层170不与第一导电部141和/或第二导电部142粘接。这样，当第一导电部141和/或第二导电部142振动时，可以降低通过第二粘结层170带起隔膜130的风险，进而有利于提高隔膜130的可靠性。
在本申请的一些实施例中，第一粘接层160与第二粘接层170连接。这样，整个隔膜130的一侧表面上均覆盖有粘结层，一方面有利于方便工艺制造，另一方面，有利于改善隔膜130收缩的状况，进而有利于提高电池10的性能和可靠性，以及提高电极组件100的整体性。
在本申请的一些实施例中，第二粘接层170与第一极片110及第二极片120相分离设置，即第二粘结层170不与第一极片110及第二极片120粘接。这样设置，可以减少第一极片110与第二极片120通过第二粘结层170粘在隔膜130上的情况，进而有利于降低第一极片110与第二极片120损坏隔膜130的风险。
在本申请的一些实施例中，沿第一轴线C的延伸方向观察，第二粘接层170粘接相邻两个卷绕层中远离第一轴线C的卷绕层的第一弯折边131与靠近第一轴线C的卷绕层的第 一弯折边131的重叠区域。这样，有利于使多个第一弯折边131之间的层叠更为可靠。
在本申请的一些实施例中，沿第一轴线C的延伸方向观察，第二粘接层170完全覆盖第一弯折边131背离第一极片110或第二极片120的一侧表面。这样，有利于方便对整体的第一弯折边131上涂覆第二粘结层170。
在本申请的一些实施例中，沿第一轴线C的延伸方向观察，第二粘接层170与第一导电部141和/或第二导电部142具有重叠区域。此时，第一导电部141和/或第二导电部142通过第二粘结层170覆盖在至少一个第一弯折边131上，有利于减少第一导电部141和/或第二导电部142在电池高度方向上的占用空间，进而利于提高电池10内的空间利用率。
在本申请的一些实施例中，第一极片110为阳极极片，第二极片120为阴极极片；将第一极片110、第二极片120和隔膜130展开，在第一轴线C的延伸方向上，参考图9，第二极片120的宽度为L 1，第一极片110的宽度为L 2，隔膜130的宽度为L 3，则隔膜130与第一极片110的宽度之差W 1＝L 3-L 2，W 1的范围为0.8mm～2.0mm；第一极片110与第二极片120的宽度之差W 2＝L 2-L 1，W 2的范围为0mm～1mm。这样，有利于使隔膜130分隔阴极极片与阳极极片，有利于降低制造难度以及阴阳极短路风险，也有利于对隔膜130进行折弯处理以及可以有较高的能量密度。
在本申请的一些实施例中，隔膜130包括基材层134，基材层为单层膜或多层复合膜，基材层的材料包括聚丙烯(PP)或聚乙烯(PE)中的至少一种。隔膜可以采用PE隔膜、PP隔膜或PP/PE/PP复合隔膜(即PP、PE、PP三层依次层叠)。由上述材料制备的隔膜130可以隔离阴极极片、阳极极片并使电池内的电子不能自由穿过，让电池10的离子在阴、阳极之间可以自由通过。由于不同材料的隔膜130的热收缩性具有差异，采用热收缩性更小的材料(如PP)的隔膜130有利于减小第一弯折边131的尺寸收缩的风险，从而进一步提高电池10的性能及可靠性。
本申请第二方面提供了一种纽扣电池10，包括如上述所述的电极组件100。
本申请实施例提供的电池10，其中的电极组件100在将第一极片110、第二极片120和隔膜130层叠并绕第一轴线C进行卷绕的过程中，会形成多层卷绕层，将多个卷绕层内的隔膜130的端部朝向第一轴线C弯折形成多个第一弯折边131，并且在相邻的两个卷绕层中，将远离第一轴线C的卷绕层的第一弯折边131覆盖在靠近第一轴线C的卷绕层的第一弯折边131上。这样，通过第一弯折边131层叠的设置，可以约束隔膜130向内收缩以及翻折，有利于降低第一极片110和第二极片120出现短路的概率。并且第一弯折边131 还可以限制第一极片110和第二极片120之间的相对偏移，还有利于改善局部析锂及放电容量损失。因此，本申请实施例的电极组件100有利于提高电池10的性能。
此外，通过隔膜130的弯折还可以降低隔膜130的宽度，减小隔膜130在纽扣电池10第一轴线延伸方向上占用的空间，有利于提高纽扣电池10的空间利用率。
在一些实施例中，电池10还包括绝缘层，绝缘层通过将绝缘材料注入容纳空间内并固化后得到。绝缘层至少部分覆盖电极组件100，且绝缘层不与电极组件100中的第一导电部141和/或第二导电部142接触。绝缘层用于固定电极组件100。其中，绝缘材料包括但不限于绝缘胶、绝缘树脂等。
如图6所示，本申请第三方面提供了一种纽扣电池的制造方法，包括：
S101、将第一极片110、隔膜130和第二极片120层叠并绕第一轴线C进行卷绕。
S102、将隔膜130卷绕成的多个卷绕层的端部均朝向第一轴线C弯折，形成多个第一弯折边131；其中，相邻的两个卷绕层中，远离第一轴线C的卷绕层的第一弯折边131覆盖在靠近第一轴线C的卷绕层的第一弯折边131上。
通过本申请实施例的纽扣电池的制造方法制造出的电池10，其中的电极组件100在将第一极片110、第二极片120和隔膜130绕第一轴线C进行卷绕的过程中，会形成多层卷绕层，将多个卷绕层内的隔膜130的端部朝向第一轴线C弯折形成多个第一弯折边131，并且在相邻的两个卷绕层中，将远离第一轴线C的卷绕层的第一弯折边131覆盖在靠近第一轴线C的卷绕层的第一弯折边131上。这样，通过第一弯折边131层叠的设置，可以约束隔膜130向内收缩以及翻折，有利于降低第一极片110和第二极片120出现短路的概率。并且第一弯折边131还可以限制第一极片110和第二极片120之间的相对偏移，还有利于改善局部析锂及放电容量损失。因此，本申请实施例的电极组件100有利于提高纽扣电池10的性能。
此外，通过隔膜130的弯折还可以降低隔膜130的宽度，减小隔膜130在纽扣电池10第一轴线C延伸方向上占用的空间，有利于提高纽扣电池10的空间利用率。
在本申请的一些实施例中，如图3a和图3b所示，卷绕层的端部朝向第一轴线C弯折的长度为a；相邻的两个卷绕层中，远离第一轴线C的卷绕层与靠近第一轴线C的卷绕层的重叠长度为b；0.6a≤b≤0.85a。二者之间的关系在这个范围内，第一弯折边131能够约束隔膜130向内收缩以及翻折，有利于进一步提高纽扣电池10的性能及可靠性。
在本申请的一些实施例中，如图5所示，可以通过整形机构180对弯折后的第一弯折 边131的表面施加温度场，或者施加压力，或者同时施加温度场和压力，即采用热压工艺使每个隔层间的隔膜130第一弯折边131粘结在一起，从而有利于改善隔膜130收缩的情况，减小隔膜130第一弯折边131向外翻折的风险，进而有利于进一步提高纽扣电池10的性能及可靠性。本申请的整形机构180没有特别限制，可以采用本领域的整形机构。本申请对热压工艺没有特别限制，可以采用本领域的热压工艺。
具体地，举出多个实施例及对比例来对上述申请的实施方式进行更具体地说明。
对比例1的扣式电池按照如下过程制作：
(1)阴极极片的制作
将钴酸锂、聚偏二氟乙烯、导电炭黑(SP)按照重量比97：1.5：1.5置于N-甲基吡咯烷酮(NMP)中充分搅拌混合，形成均匀的阴极浆料；然后将阴极浆料涂覆在阴极集流体(铝箔，厚度为16μm，宽度为4.0mm)正反两个表面形成均匀涂层，经烘干、冷压处理后，单侧涂层厚度为50μm，然后在阴极极片焊接极耳，得到阴极极片；
(2)阳极极片的制作
将石墨材料、丁苯橡胶(SBR)、羧甲基纤维素钠(CMC)按照重量比97.4∶1.2∶1.4置于去离子水中，充分搅拌混合，形成均匀的阳极浆料；将该阳极浆料涂覆于预先涂覆有底涂涂层的阳极集流体(铜箔，厚度为10μm，宽度为4.5mm)上，经烘干、冷压后，单侧涂层厚度为60μm，得到阳极极片；其中，底涂涂层是由SP、CMC、SBR按照质量比60∶5∶35混合后通过凹版涂布法涂敷于集流体两个表面形成。
(3)隔膜的制作
选用聚乙烯(PE)材质的单层膜的基材层作为隔膜，隔膜厚度为16μm，隔膜宽度为6.1mm，隔膜与阳极极片的宽度之差为1.6mm。
(3)扣式电池的制作
将上述阳极极片、隔膜、阴极极片按照顺序层叠设置，使隔膜宽度方向两侧超出阳极极片的距离均匀以及阳极极片宽度方向两侧超出阴极极片的距离均匀，然后沿第一轴线卷绕制成电极组件，再经封装、注液、静置、化成及分容等步骤，得到扣式电池。
对比例2
与对比例1的不同之处在于，隔膜宽度为5.3mm，隔膜与阳极极片的宽度之差为0.8mm。
对比例3
与对比例1的不同之处在于，隔膜宽度为5.5mm，隔膜与阳极极片的宽度之差为1.0mm。
对比例4
与对比例1的不同之处在于，隔膜宽度为5.7mm，隔膜与阳极极片的宽度之差为1.2mm。
对比例5
与对比例1的不同之处在于，隔膜宽度为5.9mm，隔膜与阳极极片的宽度之差为1.4mm。
对比例6
与对比例1的不同之处在于，隔膜宽度为6.3mm，隔膜与阳极极片的宽度之差为1.8mm。
对比例7
与对比例1的不同之处在于，隔膜宽度为6.5mm，隔膜与阳极极片的宽度之差为2.0mm。
对比例8
与对比例1的不同之处在于，隔膜宽度为6.7mm，隔膜与阳极极片的宽度之差为2.2mm。
实施例1
与对比例1的不同之处在于，在制成电极组件后，在第一轴线延伸方向上，利用整形机构对电极组件施加压力，使隔膜朝向第一轴线弯折形成多个第一弯折边，并使相邻的两个隔膜卷绕层中，远离第一轴线的卷绕层的第一弯折边覆盖在靠近第一轴线的卷绕层的第一弯折边上，可以通过调整隔膜与阳极极片的宽度差、阳极极片与阴极极片的宽度差或者整形机构施加的压力来控制第一弯折边的形成以及尺寸。其中卷绕层的端部朝向第一轴线弯折的长度a为800μm，相邻的两个卷绕层中，远离第一轴线的卷绕层与靠近第一轴线的卷绕层的重叠长度b为650μm，b＝0.81a。
实施例2
与对比例2的不同之处在于，对电极组件的隔膜进行实施例1中的整形工艺，a为400μm，b为250μm，b＝0.62a。
实施例3
与对比例3的不同之处在于，对电极组件的隔膜进行实施例1中的整形工艺，a为500μm，b为350μm，b＝0.70a。
实施例4
与对比例4的不同之处在于，对电极组件的隔膜进行实施例1中的整形工艺，a为600μm，b为450μm，b＝0.75a。
实施例5
与对比例5的不同之处在于，对电极组件的隔膜进行实施例1中的整形工艺，a为700 μm，b为550μm，b＝0.79a。
实施例6
与对比例6的不同之处在于，对电极组件的隔膜进行实施例1中的整形工艺，a为900μm，b为750μm，b＝0.83a。
实施例7
与对比例7的不同之处在于，对电极组件的隔膜进行实施例1中的整形工艺，a为1000μm，b为850μm，b＝0.85a。
实施例8
与对比例8的不同之处在于，对电极组件的隔膜进行实施例1中的整形工艺，a为1100μm，b为950μm，b＝0.86a。
实施例9
与实施例1的不同之处在于，选用聚丙烯(PP)材质的单层膜作为隔膜。
实施例10
与实施例1的不同之处在于，选用PP/PE/PP材质依次层叠的三层膜作为隔膜。
实施例11
与实施例1的不同之处在于，在基材层一侧表面涂覆3侧表厚的陶瓷涂层(95％重量占比的勃姆石配合5％重量占比的聚偏氟乙烯)。
实施例12
与实施例1的不同之处在于，在基材层的第一弯折边的朝向第一轴线的表面涂覆3基材厚度的聚偏氟乙烯涂层作为粘结层。
对以上对比例和实施例进行热箱(Hotbox)测试，测试流程如下，实验结果如表1和表2所示：
热箱(Hotbox)测试：
25±5℃环境中，将电池以0.2倍率(C)放电至3.0V，静置5min，1.5C恒流恒压充电至4.48V，电流≤0.05C；然后25±5℃下静置30min，记录电池OCV 1(开路电压)，检查外观并拍照；然后以5℃±2℃/min的速率升至130℃±2℃，并保持30min，记录电池OCV 2(开路电压)，检查外观并拍照。然后计算电压损失或统计通过率。
电压损失＝OCV 1-OCV 2，每个实施例和对比例测定10支电池，计算平均值。当电池的电压损失小于50mV时，说明扣式电池内部发生短路的概率较低，可接受；当电压损失小 于20mV时，表明电池内没有发生短路，无风险。电压损失越小，电池的性能越优异。
表1
Figure PCTCN2022090457-appb-000001
在表1中，通过实施例1与对比例1的可以看出，本申请实施例的电极组件通过在隔膜130设置第一弯折边131并且使第一弯折边131部分层叠的方式，使电池进行热箱(Hotbox)测试后电压损失值下降。由此，实施例1中的电池的安全可靠性更为优秀。因此，本申请实施例的电极组件有利于提高纽扣电池的性能及可靠性。
通过实施例1至实施例8可以看出，电池进行Hotbox测试的电压损失随着b/a的增加而减少。例如，当b/a＝0.86，电压损失低于20mV，但相应地会较大增加制造成本和难度。当b＝0.62a时，电池的电压损失相较于对比例仍然较低，表明也具有较好的改善效果。因此，本申请通过调控层叠长度b与第一弯折边131长度a满足0.6a≤b≤0.85a，能够提升电池性能及可靠性。
表2
Figure PCTCN2022090457-appb-000002
在表2中，通过实施例1、实施例9至实施例10可以看出，基材层的材质、基材层表面是否有无陶瓷层或粘结层通常也会对电池的性能产生影响。从实施例9和实施例1可以看出，本申请可以通过选择耐热收缩性更好的PP材质作为隔膜，能够进一步降低电池的电压损失值，提高电池的性能及可靠性。从实施例10和实施例1可以看出，本申请可以通过选择PP/PE/PP多层复合材质的隔膜，也能够进一步降低电池的电压损失值，提高电池的性能及可靠性。从实施例11和实施例1可以看出，本申请可以通过在基材层表面设置陶瓷层，也能够进一步降低电池的电压损失值，提高电池的性能及可靠性。从实施例12和实施例1可以看出，本申请可以通过在基材层表面设置粘结层，也能够进一步降低电池的电压损失值，提高电池的性能及可靠性。
以上所述仅为本申请的较佳实施例，并不用以限制本申请，凡在本申请的原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (19)

  1. 一种电极组件，包括：
    第一极片；
    第二极片，与所述第一极片的极性相反；以及
    隔膜，设置于所述第一极片与所述第二极片之间，所述第一极片、所述隔膜以及所述第二极片绕第一轴线进行卷绕；
    所述隔膜卷绕而形成的多个卷绕层的端部朝向所述第一轴线弯折以形成多个第一弯折边，相邻的两个所述卷绕层中，远离所述第一轴线的卷绕层的第一弯折边覆盖在靠近所述第一轴线的卷绕层的第一弯折边上。
  2. 根据权利要求1所述的电极组件，其中，还包括第一导电部和第二导电部，所述第一导电部与所述第一极片相连，所述第二导电部与所述第二极片相连；
    所述第一导电部和/或所述第二导电部覆盖在至少一个所述第一弯折边上。
  3. 根据权利要求1所述的电极组件，其中，所述卷绕层的端部朝向所述第一轴线弯折的长度为a；
    相邻的两个所述卷绕层中，远离所述第一轴线的卷绕层的第一弯折边与靠近所述第一轴线的卷绕层的第一弯折边的重叠长度为b，0.6a≤b≤0.85a。
  4. 根据权利要求2所述的电极组件，其中，所述隔膜包括：
    基材层；以及
    陶瓷层，设置在所述基材层靠近所述第一极片的表面和/或所述基材层靠近所述第二极片的表面。
  5. 根据权利要求2所述的电极组件，其中，所述隔膜包括：
    基材层；以及
    第一粘接层，设置在所述基材层靠近所述第一极片的表面和/或所述基材层靠近所述第二极片的表面。
  6. 根据权利要求1所述的电极组件，其中，所述隔膜包括：
    基材层；以及
    第二粘接层，所述第二粘接层设置在所述第一弯折边的基材层的背离所述第一极片或所述第二极片的表面。
  7. 根据权利要求6所述的电极组件，其中，所述第二粘接层与所述第一导电部和所述 第二导电部相分离设置。
  8. 根据权利要求6所述的电极组件，其中，所述隔膜还包括第一粘结层，所述第一粘接层设置在所述基材层靠近所述第一极片的表面和/或所述基材层靠近所述第二极片的表面，所述第一粘接层与所述第二粘接层连接。
  9. 根据权利要求6所述的电极组件，其中，所述第二粘接层与所述第一极片及所述第二极片相分离设置。
  10. 根据权利要求6所述的电极组件，其中，沿所述第一轴线的延伸方向观察，所述第二粘接层粘接相邻的两个所述卷绕层中远离所述第一轴线的卷绕层的第一弯折边与靠近所述第一轴线的卷绕层的第一弯折边的重叠区域。
  11. 根据权利要求6所述的电极组件，其中，沿所述第一轴线的延伸方向观察，所述第二粘接层完全覆盖所述第一弯折边背离所述第一极片或所述第二极片的表面。
  12. 根据权利要求6所述的电极组件，其中，所述第二粘接层粘接所述第一导电部和/或所述第二导电部。
  13. 根据权利要求1所述的电极组件，其中，所述第一极片为阳极极片，所述第二极片为阴极极片；
    在所述第一轴线的延伸方向上，所述隔膜与所述第一极片的宽度之差为0.8mm～2.0mm，所述第一极片与所述第二极片的宽度之差为0mm～1mm。
  14. 根据权利要求1所述的电极组件，其中，所述隔膜包括基材层，所述基材层为单层膜或多层复合膜，所述基材层的材料包括聚丙烯或聚乙烯中的至少一种。
  15. 根据权利要求1所述的电极组件，其中，所述电极组件为柱形。
  16. 一种纽扣电池，包括如权利要求1至15中任一项所述的电极组件。
  17. 一种纽扣电池的制造方法，包括：
    将第一极片、隔膜和第二极片层叠并绕第一轴线进行卷绕；
    将所述隔膜卷绕成的多个卷绕层的端部均朝向所述第一轴线弯折，形成多个第一弯折边；相邻的两个所述卷绕层中，远离所述第一轴线的卷绕层的第一弯折边覆盖在靠近所述第一轴线的卷绕层的第一弯折边上。
  18. 根据权利要求17所述的方法，其中，所述卷绕层的端部朝向所述第一轴线弯折的长度为a；
    相邻的两个所述卷绕层中，远离所述第一轴线的卷绕层的第一弯折边与靠近所述第一 轴线的卷绕层的第一弯折边的重叠长度为b，0.6a≤b≤0.85a。
  19. 根据权利要求18所述的方法，其中，所述方法还包括对所述第一弯折边进行热压处理。
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JPH01122574A (ja) * 1987-11-06 1989-05-15 Matsushita Electric Ind Co Ltd 円筒形リチウム二次電池
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