WO2020015362A1 - 一种卷绕式锂离子电池的极片和电芯及其制作方法 - Google Patents

一种卷绕式锂离子电池的极片和电芯及其制作方法 Download PDF

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Publication number
WO2020015362A1
WO2020015362A1 PCT/CN2019/076424 CN2019076424W WO2020015362A1 WO 2020015362 A1 WO2020015362 A1 WO 2020015362A1 CN 2019076424 W CN2019076424 W CN 2019076424W WO 2020015362 A1 WO2020015362 A1 WO 2020015362A1
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WO
WIPO (PCT)
Prior art keywords
pole
pole piece
ears
tabs
group
Prior art date
Application number
PCT/CN2019/076424
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English (en)
French (fr)
Inventor
曹辉
侯敏
刘婵
余招宇
刘思
刘微
姜森
Original Assignee
瑞浦能源有限公司
上海瑞浦青创新能源有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from CN201810806185.3A external-priority patent/CN108461811B/zh
Priority claimed from CN201821155582.0U external-priority patent/CN207765536U/zh
Application filed by 瑞浦能源有限公司, 上海瑞浦青创新能源有限公司 filed Critical 瑞浦能源有限公司
Priority to US16/649,622 priority Critical patent/US11322807B2/en
Priority to KR1020207011498A priority patent/KR20210031849A/ko
Priority to EP19837667.5A priority patent/EP3694043A4/en
Priority to JP2020543688A priority patent/JP7132672B2/ja
Publication of WO2020015362A1 publication Critical patent/WO2020015362A1/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
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • 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
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/528—Fixed electrical connections, i.e. not intended for disconnection
    • 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
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • 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
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/533—Electrode connections inside a battery casing characterised by the shape of the leads or tabs
    • 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
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/538—Connection of several leads or tabs of wound or folded electrode stacks
    • 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 invention belongs to the technical field of lithium ion batteries, and particularly relates to a pole piece and an electric core of a wound lithium ion battery and a manufacturing method thereof.
  • the winding type can obtain better battery performance and faster production cycle.
  • the battery pole piece structure of the wound multi-pole ear has higher energy density and production efficiency than the all-ear pole structure. Therefore, the industry tends to use a winding production method and a multi-pole battery pole piece structure.
  • the perimeter of each turn of the pole pieces gradually increases. In order to ensure the pole ears are aligned, the spacing between the pole pieces needs to increase with the number of turns.
  • the distance between the tabs is usually formed by die cutting of a metal die, and the distance formed by one die cutting is equal to the length of the metal die.
  • FIG. 1 is a schematic structural diagram of a pole piece 1 for a wound type lithium ion battery in the prior art.
  • the pole piece 1 is composed of a pole piece body 10 and a plurality of protruding pole ears 11 thereon.
  • a step 12 is formed at a portion where the pole ear 11 and the pole piece body 10 are connected.
  • the electrode body 10 is coated with an electrode material.
  • a layer of ceramic material 13 is coated on the part where the tab 11 and the tab body 10 are connected for insulation, thereby increasing the complexity of the process.
  • the technical problem to be solved by the present invention is to provide a pole piece and a battery cell of a wound type lithium ion battery and a manufacturing method thereof, which can avoid the problem that steps need to be performed in the die cutting area twice in the traditional method to produce a step, thereby greatly reducing the battery. Self-discharge rate.
  • the present invention provides a pole piece of a wound lithium-ion battery, comprising a pole piece body and at least two sets of pole ears arranged on the pole piece body, each set of pole ears including a plurality of poles Ears, the spacing between the plurality of tabs is equal, and the width of the plurality of tabs is increased by 2 ⁇ t in sequence, where ⁇ t is a positive electrode piece, a negative electrode piece, and a two-layer diaphragm of the lithium ion battery cell Of the thickness.
  • the interval between adjacent ones of the first group of ears in any of the at least two groups of the ears is equal to the distance between adjacent ones of the second group of ears.
  • the spacing between adjacent polar ears in the first group of any of the at least two sets of polar ears is not equal to the spacing between adjacent polar ears in the second group of polar ears.
  • the surface of the pole piece is completely coated with electrode material.
  • the number of polar ears in each of the at least two sets of polar ears is 3 to 36.
  • a distance between adjacent pole ears in each of the at least two groups of pole ears is 10 mm to 400 mm.
  • the width of the last tab of the at least two sets of tabs is the same as the width of the third-last tab.
  • the width of the last tab adjacent to the next set of tabs of each set of tabs is the same as the width of the penultimate tab of the set of tabs.
  • the technical solution adopted by the present invention to solve the above technical problem may also be a battery cell wound according to the above-mentioned pole piece, which is characterized by including a battery cell body and two electrodes, and the battery cell body The pole piece body is wound, and each of the electrodes is formed by sequentially superposing the at least two sets of pole ears of each pole piece.
  • the width of each tab of each set of tabs in each electrode is sequentially increased from the inner circle to the outer circle of the cell body.
  • the cell body includes the positive pole piece and the negative pole piece, and at least two sets of pole pieces of the positive pole piece and at least two pieces of the negative pole piece are provided.
  • the two sets of pole ears are respectively superposed to form an electrode.
  • it further includes two layers of separators sandwiched between the positive electrode sheet and the negative electrode sheet.
  • the technical solution adopted by the present invention to solve the above technical problem may also be a method for manufacturing a pole piece according to the above, which is characterized in that at least two knife dies are used to die cut the pole piece body to obtain The at least two sets of tabs are described, and the length of each die is equal to the distance between two adjacent tabs in the corresponding set of tabs.
  • the technical solution adopted by the present invention to solve the above technical problem may also be a pole piece of a wound lithium-ion battery, which comprises a pole piece body and at least one set of pole ears arranged on the pole piece body, each set of poles
  • the ear includes a plurality of pairs of tabs, and the two tabs of each pair of tabs have the same width, and the distance between the two tabs of each pair of tabs is equal.
  • the pitches are equal and the tab widths increase by ⁇ t, where ⁇ t is the sum of the thicknesses of the positive electrode sheet, the negative electrode sheet, and the two separators of the cell of the lithium ion battery.
  • a distance L1 between two polar ears in each pair of polar ears satisfies 5 mm ⁇ L1 ⁇ 280 mm.
  • a distance L2 between each pair of pole ears satisfies 5mm ⁇ L2 ⁇ 280mm.
  • the surface of the pole piece body is entirely coated with electrode material.
  • two of the last pair of tabs of the at least one set of tabs have different widths.
  • the width of the last pair of tabs in each set of tabs adjacent to the next set of tabs is not equal.
  • the technical solution adopted by the present invention to solve the above technical problem may also be a battery cell wound according to the above-mentioned pole piece, which is characterized by including a battery cell body and two electrodes, and the battery cell body It is formed by winding the pole piece body, and each of the electrodes is formed by sequentially superposing the at least one set of pole ears.
  • each of the electrodes includes two opposite half electrodes, each half electrode is formed by superposing one of the pair of ears, and the width of the ears in each of the half electrodes is determined by the battery core.
  • the inner and outer circles of the electrode increase in sequence, and each of the half-electrodes has a center symmetry.
  • two blade dies are used to die-cut the pole piece body for each group of pole lobes to obtain the plurality of pairs of pole lobes, wherein the length of one blade dies is equal to the plurality of pairs of pole lobes The distance between the two poles in the middle, and the length of the other die is equal to the distance between each pair of poles.
  • the technical solution adopted by the present invention to solve the above technical problems may also be a lithium ion battery including the above-mentioned battery cells.
  • the present invention has the following advantages: 1.
  • the present invention adopts the technical solution of fixing the pitch of the tabs and gradually changing the width of the tabs. Only one die cutting is required for the same tab and its pitch, which avoids Due to the secondary die cutting caused by the increasing distance between the tabs, the burr problem caused by the secondary die cutting is further avoided, and the possibility of battery self-discharge is reduced; 2.
  • the electrode material is coated, with high energy density and no sharp steps, which reduces the self-discharge rate and improves safety; by fine-tuning the width of the tabs in each set of tabs and the adjacent set, Continuity of the production line; when the thickness of the pole piece and the thickness of the diaphragm are changed, the existing die can continue to be used, reducing the equipment investment cost.
  • FIG. 1 is a schematic structural diagram of a pole piece for a wound lithium ion battery in the prior art
  • FIG. 2 is a schematic structural diagram of a pole piece for a wound lithium ion battery according to an embodiment of the present invention
  • FIG. 3 is one of the schematic diagrams of the relative positions of the pole piece and the die when the pole piece shown in FIG. 2 is manufactured;
  • FIG. 4 is a schematic diagram of the relative positions of the pole piece and the die when manufacturing the pole piece shown in FIG. 2;
  • FIG. 5 is a schematic structural diagram of a lithium ion battery cell formed by winding the pole pieces shown in FIG. 2;
  • FIG. 6A is a partially enlarged view of the area I in FIG. 5; FIG.
  • 6B is a partially enlarged view of a region II in FIG. 5;
  • FIG. 7 is a schematic structural diagram of a pole piece for a wound lithium ion battery according to another embodiment of the present invention.
  • FIG. 8 is a schematic structural diagram of a lithium ion battery cell formed by winding the pole pieces shown in FIG. 7;
  • FIG. 9 is a schematic structural diagram of a pole piece for a wound lithium ion battery according to another embodiment of the present invention.
  • FIG. 10 is a schematic structural diagram of a lithium ion battery cell formed by winding the pole pieces shown in FIG. 9;
  • FIG. 11 is a schematic diagram of a coating structure of a pole piece for a wound lithium ion battery according to an embodiment of the present invention.
  • spatial relation terms such as “below”, “below”, “below”, “below”, “above”, “up”, etc. may be used herein to describe an element shown in the drawings. Or the relationship of features to other elements or features. It will be understood that these spatially related words are intended to encompass directions other than those depicted in the figures of the device in use or operation. For example, if the device in the figures is turned over, elements described as “below” or “beneath” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary words “below” and “below” can encompass both up and down directions.
  • the device may also have other orientations (rotated 90 degrees or in other directions), so the spatial relationship descriptors used here should be interpreted accordingly.
  • orientations rotated 90 degrees or in other directions
  • the spatial relationship descriptors used here should be interpreted accordingly.
  • a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.
  • a structure in which the first feature is described as "on" the second feature may include embodiments in which the first and second features are formed in direct contact, and may also include additional features formed in the first and An embodiment between the second features so that the first and second features may not be in direct contact.
  • a component when a component is referred to as being “on another component”, “connected to another component”, “coupled to another component”, or “contacting another component”, it may be directly on the other component.
  • the other component is on, connected to or coupled to, or in contact with, or there may be an insertion component.
  • a component when a component is referred to as being “directly on,” “directly connected to,” “directly coupled to,” or “directly contacting” another component, there are no intervening components.
  • a first component when a first component is called “electrically contacted” or “electrically coupled to” a second component, there is an electrical path between the first component and the second component that allows current to flow.
  • the electrical path may include capacitors, coupled inductors, and / or other components that allow current to flow, even without direct contact between conductive components.
  • FIG. 2 is a schematic structural diagram of a pole piece for a wound lithium ion battery according to an embodiment of the present invention.
  • the present invention provides a pole piece for a wound lithium-ion battery.
  • the pole piece includes a pole piece body 110 and a plurality of pole ears 120.
  • the plurality of pole ears 120 are divided into at least two groups, each pole in each group.
  • the width of the ear 120 is increased by 2 ⁇ t in turn, and the widths of the adjacent two sets of polar ears 120 are different, and the spacing between the adjacent polar ears 120 in each group is equal.
  • the spacing between adjacent tabs 120 in the latter group is equal to or different from the spacing between adjacent tabs 120 in the previous group.
  • the number of pole ears 120 in each group is 3 to 36.
  • the distance between adjacent pole ears 120 in each group is 120 mm to 400 mm.
  • the pole piece body 110 has a long strip shape, and includes the pole piece body 110 and a plurality of pole ears 120. On one long side of the pole piece body 110, there is a rectangular pole lug 120 protruding upward at intervals.
  • the plurality of tabs 120 can be divided into at least two groups. Each group of tabs 120 includes a plurality of tabs 120. The intervals between the plurality of tabs 120 in each group are equal, and the widths of the plurality of tabs 120 are in order. Increase 2 ⁇ t. Among them, ⁇ t is the sum of the thicknesses of the two layers of the separator, the positive electrode sheet, and the negative electrode sheet.
  • the pole piece 100 of this embodiment when wound to make a lithium-ion battery cell, it can be formed by alternately stacking two layers of the pole piece 100 and two layers of the separator and winding them.
  • the formed battery includes Positive and negative pole pieces. Therefore, for each winding, the circumference of the battery cell will increase by 2 ⁇ t. Increasing the width of the lug 120 by 2 ⁇ t will align the lug 120 of each turn along its central axis, and the width of the lug will be outward from the inner circle of the cell. The circle increases in turn.
  • the separator is a selectively permeable membrane that allows lithium ions to pass, but does not allow electrons to pass.
  • the diaphragm will shrink, closing the lithium ion channel, preventing further reactions, and ensuring the safety of the lithium ion battery.
  • the interval between adjacent ones of the first group of the ears in any of the at least two groups of the ears 120 is equal to the interval between adjacent ones of the second group of the ears.
  • the distance between adjacent ones of the first group of ears in any of the at least two groups of the ears 120 is not equal to the distance between adjacent ones of the second group of ears.
  • the electrode material is completely coated on the surface of the electrode sheet 100, and an additional insulating material is not required to be applied to the connection portion between the electrode ear 120 and the electrode body 110.
  • the number of pole ears 120 in each group may be 3 to 36.
  • the distance between adjacent tabs 120 in each group is 10 mm to 400 mm.
  • the width of the last tab of each group of tabs 120 is specially set. That is, the width of the last tab in each group of tabs 120 is the same as the width of the penultimate tab in the group of tabs.
  • two sets of polar ears are provided on the pole piece body 110.
  • the first set of polar ears includes five polar ears
  • the second set of polar ears includes three polar ears.
  • the width of the first 4 ears in the first group of ears increases by 2 ⁇ t in turn, and the width of the fifth ear in the first group of ears is the same as the width of the third ear in the first group of ears.
  • the width of the fifth ear in the first group of ears does not rise compared to the width of the fourth ear and decreases.
  • the width of the first two ears in the second group of ears increases by 2 ⁇ t in order, and the width of the third ear in the second group of ears and the width of the first ear in the second group of ears the same.
  • the width of the third ear in the second group of ears does not rise compared to the width of the second ear and decreases. It can be understood that these embodiments emphasize the setting of the width of the last tab in each group, and the set of tabs 120 may have another set of tabs 120 adjacent to it.
  • the width of the plurality of tabs 120 is increased by 2 ⁇ t in sequence.
  • the last electrode in each group of tabs 120 adjacent to the next group of tabs 120 is Ear width is specially set. That is, the width of the last tab adjacent to the next set of tabs 120 in each set of tabs 120 is the same as the width of the penultimate tab in the set of tabs 120. It can be understood that, in these embodiments, the case of the polar ear group having the next adjacent group is emphasized.
  • the purpose of setting the width of the last tab in each group and / or the width of the last tab adjacent to the next group of tabs in each group is to ensure the production continuity of the pole piece 100. Specifically, the width of multiple tabs 120 in each group of tabs 120 is sequentially increased by 2 ⁇ t, and the width of the last tab in the group of tabs 120 is equal to the width of the penultimate tab in the group of tabs. The method will be explained later.
  • the first group of tabs has five and the second group of tabs has three.
  • the width of the first group of tabs increases from 14.00mm to 19.20mm, and the width of the second group of tabs from 17.47mm to 15.73mm Increase in order;
  • the first set of tabs is 160.09mm, which is equal to the length of the first die,
  • the second set of tabs is 167.03mm, which is the same as the length of the second set, and the pitch is only cut once forming.
  • B1 is the margin of the last ear in the previous pole piece
  • B2 is the margin of the first ear in the next pole piece.
  • B1 and B2 are cut by the same die.
  • B1 and B2 are both cut by the second die, so the sum of B1 and B2 is equal to the length of the second die.
  • a total of 8 pole tabs are provided on the pole piece body 110, and the 8 pole tabs 120 are divided into two groups.
  • the first group 121 includes 5 pole tabs (1211-1215).
  • the second group 122 includes three poles (1221-1223).
  • ⁇ t 0.276 mm.
  • the position of the knife die is fixed, and the knife piece is die-cut by the movement of the pole piece 100.
  • the moving direction of the pole piece 100 is shown as a first direction D1 in FIG. 2.
  • two different die dies correspond to two sets of pole ears respectively, and the length of the first die is equal to the distance S1 between the pole pieces in the first group 121.
  • the length of the second die is equal to the distance S2 between the poles in the second group 122.
  • FIG. 3 is a schematic diagram of the relative positions of the pole piece 100 and the die when the pole piece 100 shown in FIG. 2 is manufactured.
  • two knife molds are needed to make the pole piece 100 in the preferred embodiment shown in FIG. 2, which are a first knife mold K1 and a second knife mold K2.
  • the length of the knife mold K1 is equal to the distance S1 between the poles in the first group 121
  • the length of the second knife mold K2 is equal to the distance S2 between the poles in the second group 122.
  • the pole piece 100 is moved to an appropriate position according to the direction shown in the first direction D1, and then the first knife die K1 or the second knife die K2 is die-cut on the pole piece 100 to obtain the required The width of the ears and the distance between the ears.
  • FIG. 3 is a schematic diagram when the distance D is smaller than the width of the first tab 1211 in the first group 121.
  • FIG. 4 is a schematic diagram when the distance D is greater than the width of the first tab 1211 in the first group 121. The method for manufacturing the pole piece 100 shown in FIG. 2 will be described below with reference to FIGS. 3 and 4 respectively.
  • the distance D between the two die molds at this time is smaller than the width of the first tab 1211 in the first group 121.
  • the pole piece 100 shown in FIG. 3 is a pole piece 100 having two sets of pole ears formed after die-cutting. In practice, these pole ears have not been formed on the pole piece 100 before die-cutting.
  • the width of the j-th tab of the i-th group is set to W ij
  • the number of groups of the tabs is N.
  • the manufacturing method of the specific pole piece 100 includes the following steps:
  • B2 is the outer margin of the first ear on the pole piece 100. Since the pole piece 100 moves along the first direction D, the first ear piece 1211 in the first group 121 on the pole piece 100 is the first pole piece on the pole piece 100.
  • FIG. 3 shows a distance of B2 cut out at the rightmost end of the pole piece 100. In other embodiments, this distance may be cut out at the leftmost end of the pole piece 100 while the pole piece moves The direction of is opposite to the first direction D1.
  • S305 Die-cut the pole piece 100 by using the first die K1 to obtain the j-th j-th tab of the i-th group, and the width of the tab is W ij ;
  • S310 Die-cut the pole piece 100 by using the second knife die K2 to obtain the first group of fifth pole ears, and the width of the pole ears is W 15 ;
  • S313 Die-cut the pole piece 100 by using the second knife die K2 to obtain the j-th j-th tab of the i-th group, and the width of the tab is W ij ;
  • S315 Repeat steps S313-S315 until the left side of the last pole tab 1223 of the i-th group is excised. At this time, the left side distance of the last pole tab 1223 from the leftmost end of the pole piece 100 is B1;
  • B1 is the outer margin of the last tab in the pole piece 100.
  • the last given tab is the last tab 1223 in the second group 122.
  • the distance D between the two blade molds is larger than the width of the first tab 1211 in the first group 121 and smaller than the width S2 of the second blade mold K2 and the first blade 121 in the first group 121.
  • the manufacturing method of the specific pole piece 100 includes the following steps:
  • S404 Die-cut the pole piece 100 by using the first die K1 to obtain the j-th j-th tab of the i-th group, and the width of the tab is W ij ;
  • S409 Die-cut the pole piece 100 by using the second knife die K2 to obtain the first group of the fifth pole ears, and the width of the pole ears is W 15 ;
  • S412 Die-cut the pole piece 100 by using the second die K2 to obtain the j-th j-th ear of the i-th group, and the width of the ear is W ij ;
  • 3 and 4 are exemplary diagrams of the present invention.
  • the positions of two knife molds are changed, for example, the first knife mold K1 and the second knife mold
  • the positions of the die K2 are interchanged, or the distance D between the two die dies is changed.
  • the method of die cutting the pole piece 100 is similar.
  • each set of tabs corresponds to a knife mold.
  • the method of die cutting the pole pieces in these embodiments can be adjusted correspondingly with reference to the method described above.
  • the width of the last tab in each set of tabs 120 may be fine-tuned.
  • the distance S1 between two adjacent poles in the first group 121 is 160.09 mm
  • the distance between the last tab 1215 of the first group 121 and the first tab 1221 of the second group 122 can be equal to the length S2 of the second die K2, thereby realizing the transition from the first die K1 to the first die K1. Switching of two knife molds K2.
  • the distance S2 between two adjacent tabs in the second group 122 is 167.03 mm
  • the sum of the outer margin B1 of the last tab 1223 on the pole piece 100 and the outer margin B2 of the first tab 1211 on the next pole piece 100 to be die-cut in continuous production can be equal to the second
  • first knife die K1 can also be used for die cutting on the outer margin B1 and the outer margin B2.
  • the pole pieces after fine-tuning the pole pieces can ensure the accuracy of the connection between different knife molds in the process of manufacturing; on the other hand, when the pole pieces are wound to form a lithium ion battery cell,
  • the multiple tabs forming each electrode can be center aligned, and a certain safety distance is maintained between the two electrodes.
  • FIG. 5 is a schematic structural diagram of a lithium ion battery cell 200 formed by winding the pole piece 100 shown in FIG. 2.
  • the lithium ion battery cell formed by winding the electrode sheet shown in FIG. 2 includes a cell body 210 and two electrodes 220.
  • the cell body 210 is wound from the electrode sheet body 110, and the electrode 220 is formed by stacking multiple layers of tabs 120, and the width of several layers of tabs 120 decreases from the middle to the two sides in order.
  • the battery cell body 210 in FIG. 5 includes a positive pole piece and a negative pole piece, and the pole pieces are as shown in FIG. 2. After the positive electrode sheet and the negative electrode sheet are wound, two electrodes 220 are formed respectively.
  • FIGS. 6A and 6B are partial enlarged views of regions I and II in FIG. 5, respectively, showing the structures of two electrodes 220 of the battery cell 200, of which one is a positive electrode and one is a negative electrode.
  • each electrode 220 is formed by sequentially superposing at least two sets of pole ears 120 of each pole piece.
  • the width of each tab of each set of tabs 120 in each electrode 220 is sequentially increased from the inner circle to the outer circle of the cell body 210. Therefore, when the battery cell 200 is wound by using the pole piece 100 in the preferred embodiment shown in FIG.
  • the pole ears in the first group 121 are stacked in order first, and the width of the pole ears is from the inner circle of the battery body 210 to The outer ring increases in order.
  • the second group of tabs continues to be wound, because the width of the first tab 1211 in the second group 121 is smaller than the width of the last tab 1225 in the first group 122, Therefore, the width of the tabs of the battery cell 200 decreases first, and then increases toward the outer ring of the battery body 210 in order.
  • the purpose of this design is to ensure that the distance between the two electrodes 220 of the battery cell 200 is within a safe distance range.
  • the two electrodes 220 of the battery cell 200 wound by using the pole piece 100 correspond to each group of the pole ears 120 and the pole ears.
  • the width of the cell will be increased from the inner ring to the outer ring of the cell body 210 in order. After the winding of one set of tabs 120 is completed, the width of the next set of tabs 120 will be reduced first, and then increased from the outer ring of the cell body 210 in sequence, until all of the tabs 100 have been wound.
  • a positive electrode sheet can be obtained by coating a positive electrode active material on the surface of one electrode sheet 100
  • a negative electrode piece can be obtained by coating a negative electrode active material on the surface of another electrode sheet 100.
  • the positive electrode of the battery core 200 is formed by stacking at least two sets of tabs 120 of the positive electrode sheet
  • the negative electrode of the battery core 200 is formed by stacking at least two sets of tabs 120 of the negative electrode sheet.
  • the pole piece 100 obtained in the preferred embodiment shown in FIG. 2 the positive electrode of the battery core 200 is formed by superposing two sets of tabs 120 on the positive pole piece, and the negative pole of the battery core 200 is formed by two sets of tabs on the negative pole piece. 120 superimposed.
  • the filled areas in the present invention are all electrode materials, and the existing process requires a reserved area for coating ceramic insulating materials. Therefore, the present invention can increase energy density and reduce costs; the pole ears of the present invention The space between them is formed by die-cutting once.
  • the existing process requires die-cutting twice, which will produce a sharp step. The invention avoids this step, which can reduce the battery self-discharge rate and improve the yield rate.
  • the die is cut only once between adjacent poles, the die loss is reduced, and the self-discharge rate of the battery is reduced; the electrode sheet is completely coated with the electrode material, which reduces the process complexity and improves the battery.
  • Energy density, canceling ceramic coating reduces production cost; N group polar ear mode can reduce process error to 1 / N of the original between groups, improve manufacturing accuracy, reduce equipment requirements, and improve yield; pass Fine adjustment of the width of the pole ears achieves the continuity of the production line.
  • the existing die can continue to be used, which reduces the equipment investment cost.
  • FIG. 7 is a schematic structural diagram of a pole piece 300 for a wound lithium ion battery according to another embodiment of the present invention.
  • the pole piece 300 of this embodiment includes a pole piece body 310 and at least one set of pole ears 320 provided on the pole piece body 310.
  • Each set of tabs 320 includes multiple pairs of tabs. The width of the two tabs of each pair of tabs is equal. The distance L1 between the two tabs of each pair of tabs is equal. The interval L2 of each pair of tabs is equal. And the width of the tabs increases in order by ⁇ t, where ⁇ t is the sum of the thicknesses of the positive electrode sheet, the negative electrode sheet, and the two layers of the separator of the lithium ion battery cell.
  • the number of inner pole ears in each group is 5 to 80.
  • a special case is also included, that is, the last pair of poles in the at least one set of poles 320
  • the widths of the two poles in the ear may be unequal.
  • each set of tabs 320 is in phase with the next set of tabs
  • the width of the last pair of adjacent ears may be unequal.
  • the surface of the pole piece body 310 is entirely coated with electrode material.
  • the pole piece body 310 is provided with 12 pole ears 320, and the 12 pole ears 320 are divided into one group. There are 6 pairs of pole ears in this group, 2 in each pair. The widths of the two tabs are equal. The width of the tabs of two adjacent pairs of tabs increases by 0.867mm in turn. The distance between the two pairs of tabs is 34.956mm, and the distance between the two tabs of each pair is 8.522mm, in order to ensure the continuity of the production line, the width of the last lug is slightly narrower than the other lug in the pair.
  • a metal knife die cutting method may be adopted.
  • the position of the die is fixed, and the pole piece 300 moves in the first direction D1.
  • the pole piece 100 stops moving, and the pole piece 300 is die-cut using the knife die.
  • the method can be applied to the pole piece 300 having multiple sets of the pole pieces 320.
  • two blade dies are used to die-cut the pole piece body 310 for each group of pole lobes 320 to obtain multiple pairs of pole lobes.
  • the length of the first die is equal to the distance L1 between the two ears 320 of the multiple pairs of poles, and the length of the second die is equal to the distance L2 between the pairs of poles.
  • the method for manufacturing the pole piece 300 in the preferred embodiment shown in FIG. 7 is specifically described below.
  • the method includes the following steps:
  • the pole piece moves forward W + cnt ⁇ ⁇ t;
  • W is the width of the first tab
  • the process count is the working parameter of the cycle counter
  • L1 is the length of the first die
  • L2 is the length of the second die
  • the length of the first die is the distance L1 between the two poles of each pair of poles in the group.
  • L1 8.522 mm.
  • the distance L1 between two poles in each pair of poles satisfies 5mm ⁇ L1 ⁇ 280mm.
  • the length of the second die is the distance L2 between the pair of poles in the group.
  • L2 34.956 mm.
  • the distance L2 between each pair of pole ears satisfies 5mm ⁇ L2 ⁇ 280mm.
  • ⁇ t 0.276 mm, which is the same as the preferred embodiment shown in FIG. 2.
  • the die cutting method for each set of pole tabs is similar to the above method, except that the first knife mold and the second knife mold are different. Of different lengths.
  • the distance L1 between the two pole ears in each pair of pole ears in each group is equal to the length of the first blade die, and the distance L2 between the pole ears in each group is equal to the second blade die. length.
  • the first knife die and the second knife die corresponding to the group of pole ears are sequentially die-cut to obtain pole pieces having two or more pole ears.
  • FIG. 8 is a schematic structural diagram of a lithium ion battery cell 400 formed by winding the pole piece 300 shown in FIG. 7.
  • the battery cell 400 includes a battery cell body 410 and two electrodes 420.
  • Each electrode 420 is composed of two opposite half electrodes 421, and there is a space between the two half electrodes 421. Mirror-like.
  • Each electrode 420 is formed by sequentially superposing at least one set of pole tabs.
  • Each half-electrode 421 is formed by superposing one of the pair of tabs.
  • the cell body 410 is wound from a pole piece body 310, and the half electrode 421 is wound from a pole ear 320.
  • the width of the pole ears decreases in sequence from the outer ring to the inner ring of the battery core, and is symmetrical in the center.
  • the specific winding method is:
  • tolerance 0.867mm
  • tolerance ⁇ t
  • ⁇ t is the thickness of the positive pole piece + the thickness of the negative pole piece + the thickness of the two layers of the diaphragm
  • the change in the width of the pole tab of the negative pole piece is the same as that of the positive pole, and the pole ears within the same number of turns Same width, same tolerance and positive electrode.
  • the width of the positive and negative electrode initial ears can be designed according to the cell's overcurrent capability.
  • the positive pole piece, the negative pole piece and the two layers of separators are interspersed and superimposed to control the poles of all the pole pieces to face the same side. After winding twice, it should be shaped.
  • winding pay attention to: After determining the width of the pole ears, To ensure the integrity of the winding, you need a pair of tabs on each turn, and the distance between the two tabs on the first turn is the same as the distance between the two tabs on the second turn.
  • the length is 34.956mm, and so on;
  • the distance from the second pole of the first circle to the first pole of the second circle is the same as the distance from the second pole of the second circle to the first pole of the third circle.
  • the length is 8.522mm, and so on.
  • Each pitch can be formed by die cutting once, and if formed by hardware die cutting, two knife dies are required. Due to the need to ensure the continuity of the process, the pole pieces of the previous cell need to be continuous with the pole pieces of the next cell.
  • the positive and negative electrode pieces are wound into a battery cell by a circular winding pin with two layers of separators in the middle, and the wound tabs are located on the same side after winding.
  • the main structure of the battery core is shown in Figure 8.
  • the first layer of the separator, the negative electrode piece, the second layer of the separator, and the positive electrode piece are wound around the winding pin.
  • the positive electrode and the negative electrode each have two sets of tabs. There are multiple poles. After winding, the tabs are evenly distributed on the winding pins, and the final battery core is obtained after hot pressing. Because each circle of the battery has two poles with the same width, it is mirror-symmetric after winding, which is different from the current AB battery core. This can reduce the mechanism setting of the winding equipment and increase the simplicity of the process. .
  • FIG. 9 is a schematic structural diagram of a pole piece 500 for a wound lithium ion battery according to another embodiment of the present invention.
  • the pole piece 500 in this embodiment includes a pole piece body 510, and the pole piece body 510 is provided with 14 pole ears 520 divided into two groups.
  • the 10 poles in the first group G1 are divided into 5 pairs.
  • the width of the 2 poles in each pair is equal.
  • the width of the poles of two adjacent pairs of ears increases by 0.7mm.
  • the spacing is 29.2mm, and the spacing between the two poles in each pair is 5.6mm.
  • the width of the last pole in the first group G1 is narrower than the other pole in the pair; 4 poles in the second group G2 are divided into 2 pairs, 2 in each pair The widths of the tabs are equal.
  • the width of the tabs of two adjacent pairs of tabs is increased by 0.7mm.
  • the distance between the two pairs of tabs is 32.7mm, and the distance between the two tabs of each pair is 9mm.
  • the width of the last pole in the second group G2 is narrower than the other pole in the pair.
  • the pole piece 500 in this embodiment includes a pole piece body 510, and the pole piece body 510 is provided with 14 pole ears 520 divided into two groups. There are 10 poles in the first group G1 and 4 poles in the second group G2.
  • the first group G1 includes 5 pairs of 10 ears in total.
  • the width of 2 ears 520 in each pair is equal.
  • the distance G12 between two adjacent pairs of tabs is 29.2mm, and the distance G11 between the two tabs 520 in each pair is 5.6mm.
  • the width of the last tab 520a in the first group G1 is narrower than the other tab 520b in the pair.
  • the second group G2 includes a total of 2 pairs of 4 tabs, and the width of the 2 tabs 520 in each pair is equal.
  • the distance G22 between two pairs of adjacent ears is 32.7mm, and the distance G21 between the two electrodes 520 in each pair is 9mm.
  • the width of the last tab 520c in the second group G2 is narrower than the other tab 520d in the pair.
  • each set of knife molds includes two knife molds.
  • the lengths of the two knife molds in the first group of die molds respectively correspond to the distance G11 between the two tabs in the first group G1 and the distance G12 between the two pairs of adjacent tabs;
  • the lengths of the two knife molds correspond to the distance G21 between two tabs in the second group G2 and the distance G22 between two adjacent pairs of tabs, respectively.
  • FIG. 10 is a schematic structural diagram of a lithium ion battery cell 600 formed by winding a pole piece 500 shown in FIG. 9.
  • the battery cell 600 in this embodiment includes a battery body 610 and two electrodes 620.
  • Each electrode 620 is composed of two opposite half electrodes 621, and the two half electrodes 621 are spaced apart from each other and are mirror-symmetrical.
  • the cell body 610 is wound from a pole piece body 510, and the half electrode 621 is wound from a pole ear 520.
  • the width of the tabs in each group decreases from the outer ring to the inner ring in order, and is symmetrical in the center. After the group is wound, the width of the next set of repeated tabs is from the outer ring to the inner ring.
  • the inner circle decreases in order and has a symmetrical relationship.
  • the battery cell 600 in this embodiment includes a battery body 610 and two electrodes 620.
  • the cell body 610 is formed by winding a pole piece body 510.
  • the two electrodes 620 are a positive electrode and a negative electrode, respectively.
  • Each electrode 620 is composed of two opposite half electrodes 621.
  • Each half electrode 621 is wound by a tab 520.
  • the width of the tabs is sequentially increased from the inner circle to the outer circle of the battery core 600. After the winding of one set of tabs is completed, the next set of tabs is wound next to the first set of tabs. Since the width of the first tab in the next group is smaller than the width of the last tab in the previous group, the width of the tab is reduced first on the half electrode 621 After the increase.
  • the purpose of this design is to ensure that the distance between the two electrodes 620 of the battery cell 600 is within a safe distance range.
  • the pole piece 500 has more than two sets of the pole pieces 520
  • the two electrodes 620 of the battery cell 600 wound by using the pole piece 500 correspond to each set of the pole pieces 520
  • the pole pieces The width will increase from the inner ring to the outer ring of the cell body 610 in order. After the winding of one set of the tabs 520 is completed, the width of the next set of the tabs 520 will be reduced first, and then increased from the outer ring of the cell body 610 in turn until the winding of the tabs 500 is completed.
  • FIG. 11 is a schematic diagram of a coating structure of a pole piece for a wound lithium ion battery according to an embodiment of the present invention.
  • FIG. 11 uses the pole piece 300 shown in FIG. 7 as an example, showing that a fully-coated electrode material can be used in the pole piece body 310, which has a high energy density, does not have sharp steps, reduces the self-discharge rate, and improves safety.
  • the electrode material can be fully coated.

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Abstract

本发明提供一种卷绕式锂离子电池的极片、电芯及其制作方法。该极片包括极片本体和设置于极片本体上的至少两组极耳，每组极耳包括多个极耳，多个极耳之间的间距相等，多个极耳的宽度依次增加2πΔt，其中，Δt为所述锂离子电池的电芯的正极极片、负极极片和两层隔膜的厚度之和。本发明避免了现有技术中由于二次模切所带来的极片毛刺问题，降低了电池自放电的可能性；由于在极耳本体上全涂覆电极材料，能量密度高，提升了电池的安全性；通过对极耳宽度进行微调，实现了生产的连续性。

Description

一种卷绕式锂离子电池的极片和电芯及其制作方法 技术领域
本发明属于锂离子电池技术领域，具体涉及一种卷绕式锂离子电池的极片和电芯及其制作方法。
背景技术
在锂离子电池领域，现有技术下电芯的生成方式有叠片式和卷绕式两种。其中，采用卷绕式可以获得更优异的电池性能和更快的生产节拍。卷绕式多极耳的电池极片结构相对全极耳结构具有更高的能量密度和生产效率。因此，行业内都倾向于使用卷绕式的生产方式和多极耳的电池极片结构。然而，在对极片进行卷绕的过程中，极片每一圈的周长逐步增大，为了保证极耳对齐，各个极耳之间的间距需要随着卷绕的圈数而增大。极耳之间的间距通常是由五金刀模进行模切形成的，模切一次形成的间距等于五金刀模的长度。由于五金刀模的长度无法随着间距的增大而变更，一般采用两次模切的方式来形成极耳及其间距。这样虽然满足了极耳之间间距渐增的需要，但是带来了新的问题。其一，模切两次时由于刀模的抖动导致两次模切不能完全对齐，会在极片上产生台阶，形成尖锐毛刺，从而造成电池自放电增加甚至短路，存在安全隐患；其二，为了消除此影响一般会在模切的边缘涂覆一层陶瓷材料用于绝缘，这样造成了成本的增加，并且降低了电池的能量密度。
图1是现有技术中用于卷绕式锂离子电池的极片1的结构示意图。参考图1所示，极片1由极片本体10和其上若干个凸出的极耳11组成。由于二次模切在极耳11与极片本体10连接的部位形成了台阶12。在电极本体10上涂覆有电极材料。为了消除台阶12引起的电池自放电的影响，在极耳11与极片本体10连接的部位涂覆一层陶瓷材料13用于绝缘，从而增加了工艺的复杂性。
因此，有待提出一种既采用卷绕方式又能避免二次模切带来的问题的电池极片结构，以及采用这种极片结构形成的电芯和锂离子电池。
发明内容
本发明要解决的技术问题是提供一种卷绕式锂离子电池的极片和电芯及 其制作方法，可以避免传统方法中模切区域需要两次模切而产生台阶的问题，大幅降低电池自放电率。
为解决上述技术问题，本发明提出了一种卷绕式锂离子电池的极片，包括极片本体和设置于所述极片本体上的至少两组极耳，每组极耳包括多个极耳，所述多个极耳之间的间距相等，所述多个极耳的宽度依次增加2πΔt，其中，Δt为所述锂离子电池的电芯的正极极片、负极极片和两层隔膜的厚度之和。
可选地，所述至少两组极耳中的任意的第一组极耳内相邻极耳间的间距与第二组极耳内相邻极耳间的间距相等。
可选地，所述至少两组极耳中的任意的第一组极耳内相邻极耳间的间距与第二组极耳内相邻极耳间的间距不相等。
可选地，所述的极片表面全涂覆电极材料。
可选地，所述至少两组极耳中每组极耳数量为3～36个。
可选地，所述至少两组极耳中每组内相邻极耳之间的间距为10mm～400mm。
可选地，所述至少两组极耳的最后一个极耳的宽度与倒数第三个极耳的宽度相同。
可选地，每组极耳的与下一组极耳相邻的最后一个极耳的宽度与该组极耳的倒数第三个极耳的宽度相同。
本发明为解决上述技术问题而采用的技术方案还可以是一种根据以上所述的极片卷绕而成的电芯，其特征在于，包括电芯本体和两个电极，所述电芯本体由所述极片本体卷绕而成，每个所述电极由每个所述极片的所述至少两组极耳依次叠加而形成。
可选地，每个电极内每组极耳的各个极耳的宽度由所述电芯本体的内圈向外圈依次增大。
可选地，包括正极极片和负极极片，所述电芯本体包括所述正极极片和负极极片的极片本体，所述正极极片的至少两组极耳和负极极片的至少两组极耳分别叠加形成一个电极。
可选地，还包括夹于所述正极极片和负极极片之间的两层隔膜。
本发明为解决上述技术问题而采用的技术方案还可以是一种根据以上所述的极片的制作方法，其特征在于，采用至少两把刀模对所述极片本体进行模切，得到所述至少两组极耳，每把刀模的长度等于对应组极耳中两个相邻极耳之间的间距。
本发明为解决上述技术问题而采用的技术方案还可以是一种卷绕式锂离子电池的极片，包括极片本体和设置于所述极片本体上的至少一组极耳，每组极耳包括多对极耳，所述多对极耳中的每对极耳的两个极耳的宽度相等，各对极耳中两个极耳之间的间距相等，各对极耳之间的间距相等且极耳宽度依次增加πΔt，其中，Δt为所述锂离子电池的电芯的正极极片、负极极片和两层隔膜的厚度之和。
可选地，各对极耳中两个极耳之间的间距L1满足5mm≤L1≤280mm。
可选地，各对极耳之间的间距L2满足5mm≤L2≤280mm。
可选地，所述的极片本体表面全涂覆电极材料。
可选地，所述至少一组极耳的最后一对极耳中两个极耳的宽度不相等。
可选地，每组极耳中与下一组极耳相邻的最后一对极耳的宽度不相等。
本发明为解决上述技术问题而采用的技术方案还可以是一种根据以上所述的极片卷绕而成的电芯，其特征在于，包括电芯本体和两个电极，所述电芯本体由所述极片本体卷绕而成，每个所述电极由所述至少一组极耳依次叠加而形成。
可选地，每个所述电极包括相对设置的两个半电极，每个半电极由各对极耳的一者叠加而成，每个所述半电极中极耳的宽度由所述电芯的内圈向外圈依次增大，且每个所述半电极呈中心对称。
可选地，其特征在于，针对每组极耳采用两把刀模对所述极片本体进行模切，得到所述多对极耳，其中一把刀模的长度等于所述多对极耳中两个极耳之间的距离，另一把刀模的长度等于各对极耳之间的间距。
本发明为解决上述技术问题而采用的技术方案还可以是一种包括以上所述的电芯的锂离子电池。
与现有技术相比，本发明具有以下优点：1、本发明采用固定极耳间距，使极耳宽度渐变的技术方案，对于同一极耳及其间距来说只需要进行一次模切，避免了由于极耳之间间距渐增造成的二次模切，从而进一步避免了由于二次模切带来的极片毛刺问题，降低了电池自放电的可能性；2、由于在极耳本体上全涂覆电极材料，能量密度高，且不会产生尖锐台阶，在降低了自放电率的同时提升了安全性；通过对每组极耳中与相邻组衔接处的极耳宽度进行微调，实现生产线的连续性；在极片厚度和隔膜厚度产生变更时，现有的刀模可 以继续使用，降低了设备投入成本。
附图概述
本发明的特征、性能由以下的实施例及其附图进一步描述。
图1是现有技术中用于卷绕式锂离子电池的极片的结构示意图；
图2是根据本发明一实施例的用于卷绕式锂离子电池的极片的结构示意图；
图3是制作图2所示极片时极片和刀模的相对位置示意图之一；
图4是制作图2所示极片时极片和刀模的相对位置示意图之二；
图5是根据图2所示的极片所卷绕形成的锂离子电池电芯的结构示意图；
图6A是图5中I区域的局部放大图；
图6B是图5中II区域的局部放大图；
图7是根据本发明另一实施例的用于卷绕式锂离子电池的极片的结构示意图；
图8是根据图7所示的极片所卷绕形成的锂离子电池电芯的结构示意图；
图9是根据本发明又一实施例的用于卷绕式锂离子电池的极片的结构示意图；
图10是根据图9所示的极片所卷绕形成的锂离子电池电芯的结构示意图；
图11是根据本发明一实施例的用于卷绕式锂离子电池的极片的涂覆结构示意图。
本发明的较佳实施方式
为让本发明的上述目的、特征和优点能更明显易懂，以下结合附图对本发明的具体实施方式作详细说明。
在下面的描述中阐述了很多具体细节以便于充分理解本发明，但是本发明还可以采用其它不同于在此描述的其它方式来实施，因此本发明不受下面公开的具体实施例的限制。
如本申请和权利要求书中所示，除非上下文明确提示例外情形，“一”、“一个”、“一种”和/或“该”等词并非特指单数，也可包括复数。一般说来，术语“包括”与“包含”仅提示包括已明确标识的步骤和元素，而这些步骤和 元素不构成一个排它性的罗列，方法或者设备也可能包含其他的步骤或元素。
在详述本发明实施例时，为便于说明，表示器件结构的剖面图会不依一般比例作局部放大，而且所述示意图只是示例，其在此不应限制本发明保护的范围。此外，在实际制作中应包含长度、宽度及深度的三维空间尺寸。
为了方便描述，此处可能使用诸如“之下”、“下方”、“低于”、“下面”、“上方”、“上”等等的空间关系词语来描述附图中所示的一个元件或特征与其他元件或特征的关系。将理解到，这些空间关系词语意图包含使用中或操作中的器件的、除了附图中描绘的方向之外的其他方向。例如，如果翻转附图中的器件，则被描述为在其他元件或特征“下方”或“之下”或“下面”的元件的方向将改为在所述其他元件或特征的“上方”。因而，示例性的词语“下方”和“下面”能够包含上和下两个方向。器件也可能具有其他朝向(旋转90度或处于其他方向)，因此应相应地解释此处使用的空间关系描述词。此外，还将理解，当一层被称为在两层“之间”时，它可以是所述两层之间仅有的层，或者也可以存在一个或多个介于其间的层。
在本申请的上下文中，所描述的第一特征在第二特征之“上”的结构可以包括第一和第二特征形成为直接接触的实施例，也可以包括另外的特征形成在第一和第二特征之间的实施例，这样第一和第二特征可能不是直接接触。
应当理解，当一个部件被称为“在另一个部件上”、“连接到另一个部件”、“耦合于另一个部件”或“接触另一个部件”时，它可以直接在该另一个部件之上、连接于或耦合于、或接触该另一个部件，或者可以存在插入部件。相比之下，当一个部件被称为“直接在另一个部件上”、“直接连接于”、“直接耦合于”或“直接接触”另一个部件时，不存在插入部件。同样的，当第一个部件被称为“电接触”或“电耦合于”第二个部件，在该第一部件和该第二部件之间存在允许电流流动的电路径。该电路径可以包括电容器、耦合的电感器和/或允许电流流动的其它部件，甚至在导电部件之间没有直接接触。
图2是根据本发明一实施例的用于卷绕式锂离子电池的极片的结构示意图。参考图2所示，本发明提供一种用于卷绕式锂离子电池的极片，其包括极片本体110和若干极耳120，若干极耳120分为至少2组，每组内各个极耳120宽度依次增加2πΔt，相邻两组极耳120的宽度不同，每组内相邻极耳120之间的间距相等。
后一组内相邻极耳120的间距与前一组内相邻极耳120的间距相等或不 等。
每组内的极耳120数量为3～36个。
每组内相邻极耳120之间的间距为120mm～400mm。
在本实施例中，该极片本体110呈长条带状，包括极片本体110和若干极耳120。在极片本体110的一条长边上每隔一段距离具有一个向上凸出的矩形极耳120。该若干极耳120可以分为至少两组，每组极耳120中包括多个极耳120，每组中的多个极耳120之间的间距相等，且该多个极耳120的宽度依次增加2πΔt。其中，Δt为两层隔膜、正极极片、负极极片的厚度之和。这样设置的原因在于，当使用本实施例的极片100卷绕制成锂离子电池的电芯时可以由两层极片100和两层隔膜交替叠加后卷绕而成，形成的电芯包括正极极片和负极极片。因此每卷绕一圈，电芯的周长会增加2πΔt，将极耳120的宽度增加2πΔt即可以使每一圈的极耳120沿其中心轴对齐，并且极耳宽度由电芯的内圈向外圈依次增大。其中的隔膜是一种选择性透过膜，允许锂离子通过，但是不允许电子通过，放置于正负极片之间，防止正负极极片直接接触导致的短路。同时在外部短路或者高温情况下，隔膜会收缩，关闭锂离子通道，阻止进一步反应，保证锂离子电池的安全。
在一些实施例中，该至少两组极耳120中的任意的第一组极耳内相邻极耳间的间距与第二组极耳内相邻极耳间的间距相等。
在另一些实施例中，该至少两组极耳120中的任意的第一组极耳内相邻极耳间的间距与第二组极耳内相邻极耳间的间距不相等。
在一些实施例中，在极片100表面全涂覆电极材料，不需额外的在极耳120与极片本体110的连接部位涂覆绝缘材料。
在一些实施例中，每组内的极耳120数量可以为3～36个。
在一些实施例中，每组内相邻极耳120之间的间距为10mm～400mm。
在一些实施例中，每组极耳120中除了其包括的多个极耳120的宽度是依次增加2πΔt之外，每组极耳120的最后一个极耳的宽度是特殊设置的。即，每组极耳120中的最后一个极耳的宽度与该组极耳中的倒数第三个极耳的宽度相同。举例说明，假设极片本体110上设置有两组极耳，第一组极耳中包括5个极耳，第二组极耳中包括3个极耳。则第一组极耳中的前4个极耳的宽度依次增加2πΔt，第一组极耳中的第5个极耳的宽度与第一组极耳中的第3个极耳的宽度相同。也就是说，第一组极耳中的第5个极耳的宽度相比于第4个极耳的 宽度不升反降。同理，第二组极耳中的前2个极耳的宽度依次增加2πΔt，第二组极耳中的第3个极耳的宽度与第二组极耳中的第1个极耳的宽度相同。也就是说，第二组极耳中的第3个极耳的宽度相比于第2个极耳的宽度不升反降。可以理解的是，这些实施例强调了每组内最后一个极耳的宽度的设置，这些组极耳120可以在其之前或之后具有相邻的另一组极耳120。
在一些实施例中，每组极耳120中除了其包括的多个极耳120的宽度是依次增加2πΔt之外，每组极耳120中的与下一组极耳120相邻的最后一个极耳的宽度是特殊设置的。即，每组极耳120中的与下一组极耳120相邻的最后一个极耳的宽度与该组极耳120中的倒数第三个极耳的宽度相同。可以理解的是，在这些实施例中强调了具有下一组相邻组的极耳组的情况。
对每组内最后一个极耳的宽度和/或对每组内与下一组极耳相邻的最后一个极耳的宽度进行特殊设置的目的是为了保证极片100的生产连续性。具体的使每组极耳120中多个极耳120的宽度依次增加2πΔt，以及使该组极耳120中的最后一个极耳的宽度等于该组极耳中的倒数第三个极耳的宽度的方法将在后文中说明。
在优选的实施例中，该若干极耳120被分成了2组，即N＝2。
如图2所示，第一组极耳5个，第二组极耳3个，第一组极耳的宽度从14.00mm到19.20mm依次增加，第二组极耳宽度从17.47mm到15.73mm依次增加；第一组极耳间距为160.09mm，与第一把刀模长度相等，第二组极耳间距为167.03mm，与第二把刀模长度相等，间距都只用刀模模切一次成型。
如图2所示的极耳1215，由于是第一组121的最后一个极耳，本应该大于19.20mm，此处微调为了17.47mm，如此保证了第二把刀模能够准确衔接，并将累计误差归零；极耳1221是第二组122的第一个极耳，与第一组的第二个极耳1212相等，极耳的变化规律与第一组相同；极耳1223是第二组的最后一个极耳，尺寸本应该是19.20mm，现在微调为15.73mm，如此保证了B1+B2＝167.03mm。
其中，在对极片进行连续生产的过程中，B1是上一极片中最后一个极耳的外边距，B2是下一极片中第一个极耳的外边距。B1与B2是由同一把刀模模切出来的。在此实施例中，B1和B2都是由第二把刀模模切出来的，所以B1与B2之和等于第二把刀模的长度。
在图2所示的优选实施例中，极片本体110上共设置了8个极耳，将这8 个极耳120分成了两组，第一组121中包括5个极耳(1211～1215)，第二组122中包括3个极耳(1221～1223)。在此实施例中，Δt＝0.276mm。设定第i组第j个极耳的宽度为W ij，则第一组121中第一个极耳1211的宽度为W 11，第一组121中其余极耳的宽度依次增加2πΔt；第二组122中第一个极耳1221的宽度为W 21，第二组122中其余极耳的宽度依次增加2πΔt。
在对极片100进行模切时，刀模的位置是固定的，通过极片100的移动来使刀模对其进行模切。在此优选实施例中，极片100的移动方向如图2中的第一方向D1所示。在对该极片100进行模切的过程中，两把长度不同的刀模分别对应于两组极耳，其中第一把刀模的长度等于第一组121内各极耳之间的间距S1，第二把刀模的长度等于第二组122内各极耳之间的间距S2。
图3是在制作图2所示的极片100时极片100和刀模的相对位置示意图。参考图3所示，在制作图2所示的优选实施例中的极片100时需要用到两把刀模，分别是第一把刀模K1和第二把刀模K2，其中第一把刀模K1的长度等于第一组121内各极耳之间的间距S1，第二把刀模K2的长度等于第二组122内各极耳之间的间距S2。在对极片100进行模切时，第一把刀模K1和第二把刀模K2的位置是固定的，两把刀模之间的距离为D。模切的过程中，极片100按照第一方向D1所示的方向移动到合适的位置，再由第一把刀模K1或第二把刀模K2在极片100上进行模切以获得需要的极耳宽度以及极耳间距。
对极片100进行模切的方式与两把刀模之间的距离D有关。图3所示为当该距离D小于第一组121中第一个极耳1211的宽度时的示意图。图4所示为当该距离D大于第一组121中第一个极耳1211的宽度时的示意图。以下分别结合图3和图4对图2中所示极片100的制作方法进行说明。
参考图3所示，此时两把刀模之间的距离D小于第一组121中第一个极耳1211的宽度。可以理解的是，图3中所示的极片100为已经完成模切之后形成了两组极耳的极片100，实际中在进行模切之前极片100上还未形成这些极耳。其中，设定第i组第j个极耳的宽度为W ij，极耳的组数为N。在本实施例中，i≤2，j≤5，第1组中共有5个极耳，第2组中共有3个极耳，N＝2。具体的极片100的制作方法包括以下的步骤：
S301：用第一把刀模K1在极片100的一端切出长度为B2的间距；
这里的B2为该极片100上的第一个极耳的外边距。由于极片100是沿着第一方向D移动，因此极片100上第一组121中的第一个极耳1211即为该极 片100上的第一个极耳。
需要说明的是，图3所示为在极片100的最右端切出长度为B2的间距，在其他的实施例中也可以是在极片100的最左端切出此间距，同时极片移动的方向为与第一方向D1相反的方向。
S302：将第一组121中的第一个极耳1211的右侧与第二把刀模K2的左侧对齐；
S303：令i＝1，j＝1；
S304：极片100沿第一方向D1向前移动W ij-D之后停止；
S305：利用第一把刀模K1对极片100进行模切，得到第i组第j个极耳，该极耳的宽度为W ij；
S306：令j＝j+1；
S307：极片100沿第一方向D1向前移动W ij+S1之后停止；
S308：重复步骤S305-S307，直到将第i组的最后一个极耳右侧切除，此时第一组121的前四个极耳已经形成，j＝5；
S309：极片100沿第一方向D1向前移动S1+S2+D+W 15之后停止；
S310：利用第二把刀模K2对极片100进行模切，得到第1组第5个极耳，该极耳的宽度为W 15；
S311：令i＝i+1，j＝1；
S312：极片100沿第一方向D1向前移动W ij+S2之后停止；
S313：利用第二把刀模K2对极片100进行模切，得到第i组第j个极耳，该极耳的宽度为W ij；
S314：令j＝j+1；
S315：重复步骤S313-S315，直到将第i组的最后一个极耳1223左侧切除，此时，最后一个极耳1223的左侧距离该极片100的最左端距离为B1；
这里的B1是极片100中最后一个极耳的外边距，在此实施例中，该最后一给极耳即为第二组122中的最后一个极耳1223。
S316：分断极片100；
S317：回到步骤S301开始对下一个极片100进行模切。
参考图4所示，此时两把刀模之间的距离D大于第一组121中第一个极耳1211的宽度，且小于第二把刀模K2的宽度S2与第一组121中第一个极耳1211的宽度之和，即W 11≤D<W 11+S2。具体的极片100的制作方法包括以下的步骤：
S401：用第一把刀模K1在极片100的一端切出长度为B2的间距；
S402：令i＝1，j＝1；
S403：将极片100的最右端移动到距离第一把刀模K1右端B2+W ij的位置之后停止；
S404：利用第一把刀模K1对极片100进行模切，得到第i组第j个极耳，该极耳的宽度为W ij；
S405：令j＝j+1；
S406：极片100沿第一方向D1向前移动W ij+S1之后停止；
S407：重复步骤S404-S406，直到将第i组的最后一个极耳右侧切除，此时第一组121的前四个极耳已经形成，j＝5；
S408：极片100沿第一方向D1向前移动S1+S2+D+W ij之后停止；
S409：利用第二把刀模K2对极片100进行模切，得到第1组第5个极耳，该极耳的宽度为W 15；
S410：令i＝i+1，j＝1；
S411：极片100沿第一方向D1向前移动W ij+S2之后停止；
S412：利用第二把刀模K2对极片100进行模切，得到第i组第j个极耳，该极耳的宽度为W ij；
S413：令j＝j+1；
S414：重复步骤S412-S413，直到将第i组的最后一个极耳右侧切除；在本实施例中，本步骤执行完毕之后，第二组122的前两个极耳已经形成，j＝3；
S415：极片100沿第一方向D1向前移动W 11+W ij+S2-D；
S416：利用第一把刀模K1对极片100进行模切；
S417：极片100沿第一方向D1向前移动D-W 11之后停止；
S418：利用第二把刀模K2对极片100进行模切；
S419：分断极片100，使极片100沿第一方向D1向前移动S1+W 11+W 12-D；
S420：回到步骤S402开始对下一个极片进行模切。
当两把刀模之间的距离D更大时，按照类似上述步骤S415-418进行相应的调整，使极片100在制作过程中无需倒带的操作。
图3和图4所示为本发明的示例性示意图，对于图2所示的优选实施例来说，当两把刀模的位置发生变化时，例如第一把刀模K1和第二把刀模K2的位置互换，或两把刀模之间的距离D变化等，对极片100进行模切的方法类似。
在一些实施例中，当极片上具有多于两组极耳时，每一组极耳对应于一把刀模。对于这些实施例中的极片进行模切的方法可以在参考上文所述的方法进行相应的调整。
在图2所示的优选实施例中，为了保证生产的连续性，还可以对每组极耳120中的最后一个极耳的宽度进行微调。具体地，在图2所示的极片100中，第一组121中两个相邻极耳之间的间距S1＝160.09mm，第一组121中的第一个极耳1211的宽度为W 11＝14.00mm。第一组121中其余的极耳宽度依次增加2πΔt，Δt＝0.276mm，也就是W 12＝15.73mm，W 13＝17.47mm，W 14＝19.20mm，W 15＝20.93mm。为了保持生产的连续性，在模切至第一组121中的最后一个极耳1215时，使最后一个极耳1215的宽度等于第一组121中倒数第三个极耳的宽度，也就是W 15＝W 13＝17.47mm。这样，可以使第一组121最后一个极耳1215与第二组122第一个极耳1221之间的间距等于第二把刀模K2的长度S2，从而实现从第一把刀模K1到第二把刀模K2的切换。
类似的，第二组122中两个相邻极耳之间的间距S2＝167.03mm，第二组122中的第一个极耳1221的宽度为W 21＝15.73mm。第二组122中其余的极耳宽度依次增加2πΔt，也就是W 22＝17.47mm，W 23＝19.20mm。为了保持生产的连续性，在模切至第二组122中的最后一个极耳1223时，使最后一个极耳1223的宽度等于第二组122中倒数第三个极耳的宽度，也就是W 23＝W 21＝15.73mm。这样，可以使得极片100上的最后一个极耳1223的外边距B1与连续生产中所要进行模切的下一个极片100上的第一个极耳1211的外边距B2之和等于第二把刀模K2的长度S2，即B1+B2＝S2。此后，换作使用第一把刀模K1对下一个极片100上的第一组相邻极耳进行模切。依次类推。
可以理解的是，在对外边距B1和外边距B2进行模切使也可以采用第一把刀模K1，在这种实施例中，需要先由第二把刀模K2换为第一把刀模K1，再通过微调控制极片的走带方式，使B1+B2＝S1。
经过极耳宽度微调之后的极片一方面可以在加工制造的过程中保证不同刀模之间衔接的准确性；另一方面还使得在使用该极片卷绕形成锂离子电池的电芯时，形成每一个电极的多个极耳可以中心对齐，并且两个电极之间保持一定的安全距离。
图5是根据图2所示的极片100所卷绕形成的锂离子电池电芯200的结构示意图。参考图5所示，根据图2所示的极片所卷绕形成的锂离子电池电芯包 括电芯本体210和两个电极220，电芯本体210由极片本体110卷绕而成，电极220由多层极耳120叠加而成，若干层极耳120的宽度由中间向两侧依次减小。
可以理解的是，图5中的电芯本体210包括正极极片和负极极片，其极片均如图2所示。正极极片和负极极片卷绕后分别形成两个电极220。
图6A、6B分别是图5中区域I和区域II的局部放大图，分别示出了该电芯200的两个电极220的结构，其中，一个为正极电极，一个为负极电极。参考图6A和图6B所示，每个电极220由每个极片的至少两组极耳120依次叠加而形成。每个电极220内每组极耳120的各个极耳的宽度由该电芯本体210的内圈向外圈依次增大。因此，在使用图2所示的优选实施例中的极片100卷绕电芯200时，第一组121中的极耳先依次叠加，极耳的宽度从该电芯本体210的内圈向外圈依次增大。当第一组极耳卷绕完毕后，继续卷绕第二组极耳时，由于第二组121中第一个极耳1211的宽度小于第一组122中的最后一个极耳1225的宽度，因此该电芯200的极耳宽度先减小，再向电芯本体210的外圈依次增大。这样设计的目的在于，保证电芯200的两个电极220之间的间距处于安全距离的范围。
可以理解的是，当极片100具有大于两组的极耳120时，利用该极片100卷绕而成的电芯200的两个电极220中，对应于每一组极耳120，极耳的宽度将由电芯本体210的内圈向外圈依次增大。当一组极耳120卷绕完毕之后，下一组极耳120的宽度将先减小，再由向电芯本体210的外圈依次增大，直到极片100全部卷绕完毕。
在一些实施例中，可以通过在一片极片100的表面涂覆正极活性材料获得正极极片，通过在另一片极片100的表面涂覆负极活性材料获得负极极片。电芯200的正极是由正极极片的至少两组极耳120叠加形成，电芯200的负极是由负极极片的至少两组极耳120叠加形成。根据图2所示的优选实施例所获得的极片100，电芯200的正极是由正极极片上的两组极耳120叠加形成，电芯200的负极是由负极极片上的两组极耳120叠加形成。
与现有技术相比，本发明中的填充区域都是电极材料，而现有工艺需要预留区域，用于涂覆陶瓷绝缘材料，因此本发明可以提升能量密度，降低成本；本发明极耳之间的间距由刀模模切一次成型，现有工艺需要刀模模切两次，会产生一个尖锐的台阶，本发明避免了此台阶，可以降低电池自放电率，提升良 品率。
因此，采用本发明后，由于相邻极耳之间只用模切一次，降低刀模损耗，降低电池自放电率；极片由电极材料全涂覆既降低了工艺复杂性，又提升了电池能量密度，取消陶瓷涂覆降低了生产成本；N组极耳模式在组与组之间可以将工艺误差降低为原来的1/N，提升制造精度，降低对设备的要求，提升良品率；通过微调极耳宽度实现产线的连续性，同时极片厚度和隔膜厚度变更后，现有刀模可以继续使用，降低了设备投入成本。
图7是根据本发明另一实施例的用于卷绕式锂离子电池的极片300的结构示意图。参考图7所示，本实施例的极片300包括极片本体310和设置于极片本体310上的至少一组极耳320。每组极耳320包括多对极耳，每对极耳的两个极耳的宽度相等，各对极耳中两个极耳之间的间距L1相等，各对极耳之间的间距L2相等且极耳的宽度依次增加πΔt，其中，Δt为锂离子电池的电芯的正极极片、负极极片和两层隔膜的厚度之和。每组内极耳的数量为5～80个。
在一些实施例中，在该至少一组极耳320中的多对极耳的宽度是相等的情况之外，还包括一特殊情况，即，该至少一组极耳320中的最后一对极耳中的两个极耳的宽度可以是不相等的。
在一些实施例中，在该至少一组极耳320中的多对极耳的宽度是相等的情况之外，还包括一特殊情况，即，每组极耳320中与下一组极耳相邻的最后一对极耳的宽度可以是不相等的。
可以理解的是，这些实施例对一组极耳中的最后一对极耳的宽度进行特殊设置的目的是为了在连续生产极片的过程中，保证在进行下一组极耳的模切时，不同刀模之间可以顺利衔接。
在一些实施例中，极片本体310表面全涂覆电极材料。
参考图7所示，在优选的实施例中，极片本体310上设有12个极耳320，12个极耳320分为1组，该组中有6对极耳，每对中的2个极耳的宽度相等，相邻两对极耳的极耳宽度依次增加0.867mm，相邻两对极耳之间的间距分别为34.956mm，每对中的两个极耳之间的间距为8.522mm，为了保证生产线的连续性，最后一个极耳的宽度比该对中的另一个极耳略窄。
在制作图7所示的极片300时，可以采用五金刀模模切的方法。刀模的位置是固定的，极片300沿第一方向D1移动，当极片100移动的距离达到合适的距离时，极片100停止移动，使用刀模对极片300进行模切。
虽然图7所示的极片300仅包含一组极耳320，本方法可用于具有多组极耳320的极片300。在此方法中，针对每组极耳320采用两把刀模对极片本体310进行模切，得到多对极耳。其中第一把刀模的长度等于多对极耳中两个极耳320之间的距离L1，第二把把刀模的长度等于各对极耳之间的间距L2。
下面对图7所示优选实施例中的极片300的制作方法进行具体的说明，该方法包括以下步骤：
S701、调整两把刀模的间距D＝3mm，使其小于W＝4mm；
S702、将极片的一端与第一把刀模的前端对齐；
S703、设定过程计数cnt＝0；
S704、极片向前走带L1+L2+D＝8.522+34.956+3＝46.478mm；
S705、使用第二把刀模进行模切；
S706、极片向前走带W+cnt×Δt-D＝4+cnt×0.276-3；
S707、使用第一把刀模进行模切；
S708、极片向前走带W+cnt×Δt；
S709、设定过程计数为cnt＝cnt+1；
S710、重复S704～S709过程直到结束。
其中，W为第一个极耳的宽度，过程计数为循环计数器的工作参数，L1为第一把刀模长度，L2为第二把刀模长度，L1≠L2。
在上述方法中，第一把刀模的长度也就是该组中各对极耳中两个极耳之间的间距L1。在图7所示优选实施例中，L1＝8.522mm。在一些实施例中，各对极耳中两个极耳之间的间距L1满足5mm≤L1≤280mm。
在上述方法中，第二把刀模的长度也就是该组中各对极耳之间的间距L2。在图7所示优选实施例中，L2＝34.956mm。在一些实施例中，各对极耳之间的间距L2满足5mm≤L2≤280mm。
在图7所示优选实施例中，Δt＝0.276mm，与图2所示的优选实施例相同。
可以理解的是，在制作具有两组及以上极耳的极片300时，对于每一组极耳的模切方法与上述方法类似，不同之处在于第一把刀模和第二把刀模的长度不同。对于不同组极耳，每组内各对极耳中两个极耳之间的间距L1等于第一把刀模的长度，每组内各对极耳之间的间距L2等于第二把刀模的长度。对每组极耳使用该组极耳所对应的第一把刀模和第二把刀模依次进行模切，即可获得具有两组及以上极耳的极片。
图8是根据图7所示的极片300所卷绕形成的锂离子电池电芯400的结构示意图。如图8所示，该电芯400包括电芯本体410和两个电极420，每个电极420均由相对设置的两个半电极421组成，两个所述半电极421之间具有间隔，且呈镜面对称。每个电极420由至少一组极耳依次叠加而形成。每个半电极421由各对极耳的一者叠加而成。
电芯本体410由极片本体310卷绕而成，所述半电极421由极耳320卷绕而成。所述半电极421中，极耳的宽度由电芯的外圈向内圈依次减小，且呈中心对称。
具体卷绕方法为：
一、分别制作两种极片，并在两种极片的表面分别涂敷正极活性材料和负极活性材料后，五金模切得到多个极耳，极耳和间距可以根据电芯功率和工作情况来灵活设计，得到正极极片和负极极片，控制正极极片的极耳宽度随着圈数增加而依次增加，且同一圈的极耳宽度相同，不同圈的极耳宽度其差值为等差数列，公差为0.867mm，公差＝πΔt，其中Δt为正极极片厚度+负极极片厚度+两层隔膜厚度；负极极片的极耳宽度变化规律和正极相同，相同圈数内的极耳宽度相同，公差和正极亦相同。正负极初始极耳的宽度可以根据电芯过流能力来设计。
二、将正极极片、负极极片和两层隔膜穿插经过叠加，控制所有极片的极耳朝向同一侧，卷绕两圈后成型，卷绕时需注意：在确定好极耳宽度之后，保证卷绕的整体度，需要每一圈有一对极耳，且第一圈两个极耳之间的距离和第二圈两个极耳之间的距离相同，长度为34.956mm，依次类推；第一圈第二个极耳到第二圈第一个极耳的距离和第二圈第二个极耳到第三圈第一个极耳的距离相同，长度为8.522mm，依次类推，每个间距通过模切一次即可成形，且如果通过五金模切来成形，需要两幅刀模。由于需要保证工艺过程的连续性，前一个电芯的极片需要和后一个电芯的极片连续。
在得到不同极耳和间距的正负极极片之后，正负极极片通过圆形卷针，中间由两层隔膜隔开卷绕成为电芯，卷绕后极耳位于同一侧。电芯主要的结构如图8所示，第一层隔膜、负极极片、第二层隔膜和正极极片绕卷针卷绕形成的电芯，正负极各有两组极耳，每组有多个极耳。在卷绕之后，极耳均匀分布在卷针上，经过热压后得到最终的电芯。由于电池每一圈有两个宽度相同的极耳，在卷绕之后呈镜面对称，与目前方形电池AB芯的区分有一定的不同，这样可 以降低卷绕设备的机构设置，增加工艺的简便性。
图9是根据本发明又一实施例的用于卷绕式锂离子电池的极片500的结构示意图。参考图9所示，本实施例的极片500包括极片本体510，极片本体510上设有14个极耳520，分成2组。第一组G1中有10个极耳，第二组G2中有4个极耳。第一组G1中的10个极耳分为5对，每对中的2个极耳的宽度相等，相邻两对极耳的极耳宽度增加0.7mm，相邻两对极耳之间的间距分别为29.2mm，每对中的两个极耳之间的间距为5.6mm。为了保证生产线的连续性，第一组G1中最后一个极耳的宽度比该对中的另一个极耳窄；第二组G2中的4个极耳分为2对，每对中的2个极耳的宽度相等，相邻两对极耳的极耳宽度增加0.7mm，相邻两对极耳之间的间距分别为32.7mm，每对中的两个极耳之间的间距为9mm。为了保证生产线的连续性，第二组G2中最后一个极耳的宽度比该对中的另一个极耳窄。
参考图9所示，本实施例的极片500包括极片本体510，极片本体510上设有14个极耳520，分成2组。第一组G1中有10个极耳，第二组G2中有4个极耳。
第一组G1中包括5对共10个极耳，每对中的2个极耳520的宽度相等，相邻两对极耳的极耳宽度依次增加πΔt＝0.7mm，其中，Δt＝0.223mm。相邻两对极耳之间的间距G12为29.2mm，每对中的两个极耳520之间的间距G11为5.6mm。为了保证生产线的连续性，第一组G1中最后一个极耳520a的宽度比该对中的另一个极耳520b窄。
第二组G2中包括2对共4个极耳，每对中的2个极耳520的宽度相等，相邻两对极耳的极耳宽度依次增加πΔt＝0.7mm，其中，Δt＝0.223mm。相邻两对极耳之间的间距G22为32.7mm，每对中的两个极耳520之间的间距G21为9mm。为了保证生产线的连续性，第二组G2中最后一个极耳520c的宽度比该对中的另一个极耳520d窄。
在制作图9所示的极片500时，可参考图7所示优选实施例的制作方法。与图7所示优选实施例中的极片300不同的是，极片500中具有两组极耳。因此，在制作该极片500时，需要两组刀模，其中每组刀模中包括两把刀模。第一组刀模中的两把刀模的长度分别对应于第一组G1中的两个极耳之间的间距G11和相邻两对极耳之间的间距G12；第二组刀模中的两把刀模的长度分别对应于第二组G2中的两个极耳之间的间距G21和相邻两对极耳之间的间距G22。 在对极片进行模切以得到图9所示的极片500时，依次使用该两组刀模对极片进行模切。
图10是根据图9所示的极片500所卷绕形成的锂离子电池电芯600的结构示意图。参考图10所示，本实施例中的电芯600包括电芯本体610和两个电极620。每个电极620均由相对设置的两个半电极621组成，两个所述半电极621之间具有间隔，且呈镜面对称。电芯本体610由极片本体510卷绕而成，所述半电极621由极耳520卷绕而成。所述半电极621中，每一组中极耳的宽度由外圈向内圈依次减小，且呈中心对称，当该组卷绕完毕后，下一组重复极耳的宽度由外圈向内圈依次减小，且呈中心对称的关系。
参考图10所示，本实施例中的电芯600包括电芯本体610和两个电极620。电芯本体610由极片本体510卷绕而成。可以理解的是，该两个电极620分别为正极电极和负极电极。两个电极620之间具有一定的间隔距离，以保证该电芯600的正负极处于安全距离之外。每个电极620均由相对设置的两个半电极621组成。
每个半电极621由极耳520卷绕而成。经过一组极耳卷绕而成的半电极621中，极耳的宽度由电芯600的内圈向外圈依次增加。当一组极耳卷绕完毕之后，由下一组极耳紧挨着第一组极耳继续卷绕。由于下一组极耳中的第一个极耳的宽度相比前一组中的最后一个极耳的宽度有所减小，因此，在该半电极621上，极耳的宽度呈现先减小后增加的情况。这样设计的目的在于，保证电芯600的两个电极620之间的间距处于安全距离的范围。
可以理解的是，当极片500具有大于两组的极耳520时，利用该极片500卷绕而成的电芯600的两个电极620中，对应于每一组极耳520，极耳宽度将由电芯本体610的内圈向外圈依次增大。当一组极耳520卷绕完毕之后，下一组极耳520的宽度将先减小，再由向电芯本体610的外圈依次增大，直到极片500全部卷绕完毕。
图11是根据本发明一实施例的用于卷绕式锂离子电池的极片的涂覆结构示意图。
在图1所示的现有技术中，需要涂覆绝缘层13，并且会产生尖锐的台阶12。本发明在极片的涂覆方式方面采用全涂覆电极材料的方式。图11以图7所示的极片300为例，表示可以在极片本体310采用全涂覆电极材料，能量密度高，且不会有尖锐台阶，降低自放电率，提升安全性。相应地，对其他实施 例中的极片也可以采用全涂覆电极材料的方式。
本申请使用了特定词语来描述本申请的实施例。如“一个实施例”、“一实施例”、和/或“一些实施例”意指与本申请至少一个实施例相关的某一特征、结构或特点。因此，应强调并注意的是，本说明书中在不同位置两次或多次提及的“一实施例”或“一个实施例”或“一替代性实施例”并不一定是指同一实施例。此外，本申请的一个或多个实施例中的某些特征、结构或特点可以进行适当的组合。
虽然本发明已参照当前的具体实施例来描述，但是本技术领域中的普通技术人员应当认识到，以上的实施例仅是用来说明本发明，在没有脱离本发明精神的情况下还可作出各种等效的变化或替换，因此，只要在本发明的实质精神范围内对上述实施例的变化、变型都将落在本申请的权利要求书的范围内。

Claims (23)

  1. 一种卷绕式锂离子电池的极片，包括极片本体和设置于所述极片本体上的至少两组极耳，每组极耳包括多个极耳，所述多个极耳之间的间距相等，所述多个极耳的宽度依次增加2πΔt，其中，Δt为所述锂离子电池的电芯的正极极片、负极极片和两层隔膜的厚度之和。
  2. 根据权利要求1所述的极片，其特征在于，所述至少两组极耳中的任意的第一组极耳内相邻极耳间的间距与第二组极耳内相邻极耳间的间距相等。
  3. 根据权利要求1所述的极片，其特征在于，所述至少两组极耳中的任意的第一组极耳内相邻极耳间的间距与第二组极耳内相邻极耳间的间距不相等。
  4. 根据权利要求1所述的极片，其特征在于，所述的极片表面全涂覆电极材料。
  5. 根据权利要求1所述的极片，其特征在于，所述至少两组极耳中每组极耳数量为3～36个。
  6. 根据权利要求1所述的极片，其特征在于，所述至少两组极耳中每组内相邻极耳之间的间距为10mm～400mm。
  7. 根据权利要求1所述的极片，其特征在于，所述至少两组极耳的最后一个极耳的宽度与倒数第三个极耳的宽度相同。
  8. 根据权利要求1所述的极片，其特征在于，每组极耳的与下一组极耳相邻的最后一个极耳的宽度与该组极耳的倒数第三个极耳的宽度相同。
  9. 一种根据权利要求1-8任一项所述的极片卷绕而成的电芯，其特征在于，包括电芯本体和两个电极，所述电芯本体由所述极片本体卷绕而成，每个所述电极由每个所述极片的所述至少两组极耳依次叠加而形成。
  10. 根据权利要求9所述的电芯，其特征在于，每个电极内每组极耳的各个极耳的宽度由所述电芯本体的内圈向外圈依次增大。
  11. 根据权利要求9所述的电芯，其特征在于，包括正极极片和负极极片，所述电芯本体包括所述正极极片和负极极片的极片本体，所述正极极片的至少两组极耳和负极极片的至少两组极耳分别叠加形成一个电极。
  12. 根据权利要求11所述的电芯，其特征在于，还包括夹于所述正极极片和负极极片之间的两层隔膜。
  13. 一种根据权利要求1所述的极片的制作方法，其特征在于，采用至少两把刀模对所述极片本体进行模切，得到所述至少两组极耳，每把刀模的长度等于对 应组极耳中两个相邻极耳之间的间距。
  14. 一种卷绕式锂离子电池的极片，包括极片本体和设置于所述极片本体上的至少一组极耳，每组极耳包括多对极耳，所述多对极耳中的每对极耳的两个极耳的宽度相等，各对极耳中两个极耳之间的间距相等，各对极耳之间的间距相等且极耳宽度依次增加πΔt，其中，Δt为所述锂离子电池的电芯的正极极片、负极极片和两层隔膜的厚度之和。
  15. 根据权利要求14所述的极片，其特征在于，各对极耳中两个极耳之间的间距L1满足5mm≤L1≤280mm。
  16. 根据权利要求14所述的极片，其特征在于，各对极耳之间的间距L2满足5mm≤L2≤280mm。
  17. 根据权利要求14所述的极片，其特征在于，所述的极片本体表面全涂覆电极材料。
  18. 根据权利要求14所述的极片，其特征在于，所述至少一组极耳的最后一对极耳中两个极耳的宽度不相等。
  19. 根据权利要求14所述的极片，其特征在于，每组极耳中与下一组极耳相邻的最后一对极耳的宽度不相等。
  20. 一种根据权利要求14-19任一项所述的极片卷绕而成的电芯，其特征在于，包括电芯本体和两个电极，所述电芯本体由所述极片本体卷绕而成，每个所述电极由所述至少一组极耳依次叠加而形成。
  21. 根据权利要求20所述的电芯，其特征在于，每个所述电极包括相对设置的两个半电极，每个半电极由各对极耳的一者叠加而成，每个所述半电极中极耳的宽度由所述电芯的内圈向外圈依次增大，且每个所述半电极呈中心对称。
  22. 一种根据权利要求14所述的极片的制作方法，其特征在于，针对每组极耳采用两把刀模对所述极片本体进行模切，得到所述多对极耳，其中一把刀模的长度等于所述多对极耳中两个极耳之间的距离，另一把刀模的长度等于各对极耳之间的间距。
  23. 一种包括权利要求9或20所述的电芯的锂离子电池。
PCT/CN2019/076424 2018-07-20 2019-02-28 一种卷绕式锂离子电池的极片和电芯及其制作方法 WO2020015362A1 (zh)

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