WO2018054332A1 - 一种卷绕式电芯 - Google Patents

一种卷绕式电芯 Download PDF

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Publication number
WO2018054332A1
WO2018054332A1 PCT/CN2017/102754 CN2017102754W WO2018054332A1 WO 2018054332 A1 WO2018054332 A1 WO 2018054332A1 CN 2017102754 W CN2017102754 W CN 2017102754W WO 2018054332 A1 WO2018054332 A1 WO 2018054332A1
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WO
WIPO (PCT)
Prior art keywords
pole piece
diaphragm
region
cell
tab
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Application number
PCT/CN2017/102754
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English (en)
French (fr)
Inventor
肖良针
曾巧
王可飞
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 EP17852400.5A priority Critical patent/EP3518315B1/en
Publication of WO2018054332A1 publication Critical patent/WO2018054332A1/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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/04—Construction or manufacture in general
    • H01M10/0431—Cells with wound or folded electrodes
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/0459—Cells or batteries with folded separator between plate-like electrodes
    • 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
    • H01M10/06—Lead-acid accumulators
    • H01M10/12—Construction or manufacture
    • H01M10/125—Cells or batteries with wound or folded electrodes
    • 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
    • H01M10/06—Lead-acid accumulators
    • H01M10/12—Construction or manufacture
    • H01M10/14—Assembling a group of electrodes or 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
    • H01M10/24—Alkaline accumulators
    • H01M10/28—Construction or manufacture
    • H01M10/286—Cells or batteries with wound or folded electrodes
    • 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 secondary batteries, and in particular to a wound cell.
  • the object of the present invention is to propose a wound cell.
  • the present application relates to a wound cell that includes a flat cell wound from a starting end of a first diaphragm, a first pole piece, a second diaphragm, and a second pole piece, a first tab is connected to the first pole piece, and a second tab is connected to the second pole piece;
  • the first pole piece includes a first current collector and a first surface coated on opposite surfaces of the first current collector
  • An active material the second pole piece includes a second current collector and a second active material coated on opposite surfaces of the second current collector, and the outermost circle of the second pole piece includes a second single-sided coated area a surface of the second single-sided coating region facing the center of the wound cell is a second empty current collector region not coated with the second active material, the first pole piece and the second surface
  • the opposite portion of the empty current collector region includes a first one-sided coated region, the face of the first one-sided coated region facing away from the center of the wound cell is uncoated the first live The first empty current collector region of the substance;
  • a finishing end of the first pole piece includes a first empty foil area, and a portion of the second pole piece opposite to the first empty foil area comprises a second empty foil area;
  • the starting end of the first empty foil region and the starting end of the second single-sided coating region are located on opposite sides of the flat cell relative to the thickness direction of the flat cell.
  • the second one-sided coated area coincides with the first tab and/or the second tab in a projection in the thickness direction of the flat cell.
  • the first empty foil region coincides with the first tab and/or the second tab.
  • the length of the first empty foil zone is greater than the length of the second empty foil zone.
  • the length of the first empty foil region is less than or equal to the length of the first single-sided coated region, and/or the length of the second empty foil region is less than or equal to the second single-sided coated region. length.
  • the length of the first diaphragm and/or the second diaphragm is greater than the length of the first empty foil region.
  • the distance from the starting end of the first diaphragm to the first tab is a first diaphragm head, and the distance from the starting end of the second diaphragm to the first tab is Two diaphragm head;
  • the first diaphragm head and the second diaphragm head are disposed in parallel along the width direction of the flat cell, or the first diaphragm head is folded back inside the flat cell to form a diaphragm retracting section, or The first diaphragm head and the second diaphragm head are folded back inside the flat cell to form a diaphragm retracting section; in the projection of the flat cell thickness direction, the diaphragm retracting section is neither Coinciding with the first tab and the second tab.
  • the distance from the beginning end of the second pole piece to the second pole piece is a second pole piece head, and the second pole piece head is folded back inside the flat cell to form a second pole piece back
  • the distance from the beginning end of the first pole piece to the first pole piece is a first pole piece head, and the first pole piece head is folded back inside the flat cell to form a first a pole piece retracting section; in the projection in the thickness direction of the flat cell, the first pole piece folding back segment and/or the second pole piece back folding section are not associated with the first tab and the The second pole coincides.
  • the starting end of the first membrane is connected to the starting end of the second membrane.
  • the first pole piece is a positive pole piece, and the second pole piece is a negative pole piece; or the first pole piece is a negative pole piece, and the second pole piece is a positive pole piece.
  • the present application adopts a single-sided anion and anode finishing technique, thereby forming a vest by a single-side coated empty cathode anode current collector on one side along the thickness direction of the battery core, along the battery core.
  • the other side in the width direction is formed by a double-sided empty cathode anode current collector, and the present invention forms a vest on both planes of the flat battery core, thereby improving the safety of the battery core.
  • the thickness of the battery core can be further reduced, thereby increasing the energy density of the battery.
  • the present application forms vests on both planes of the flat cell, so that the flatness of the cell is better, and the cell deformation can be improved.
  • 1 is a schematic view showing the structure of a conventional secondary battery
  • FIG. 2 is a schematic structural view of a wound type electric core in a specific embodiment of the present application.
  • FIG. 3 is a schematic structural view of a wound type electric core in a specific embodiment of the present application.
  • FIG. 4 is a schematic structural view of a wound type electric core in a specific embodiment of the present application.
  • FIG. 5 is a schematic structural view of a wound type electric core in a specific embodiment of the present application.
  • FIG. 6 is a schematic structural view of a wound type electric core in a specific embodiment of the present application.
  • FIG. 7 is a schematic structural view of a wound type electric core in a specific embodiment of the present application.
  • FIG. 8 is a schematic structural view of a wound type electric core in a specific embodiment of the present application.
  • FIG. 9 is a schematic structural view of a wound type electric core in a specific embodiment of the present application.
  • FIG. 10 is a schematic structural view of a wound type electric core in a specific embodiment of the present application.
  • FIG. 11 is a schematic structural view of a wound type electric core in a specific embodiment of the present application.
  • FIG. 12 is a schematic structural view of a wound type electric core in a specific embodiment of the present application.
  • Embodiments of the present application relate to a wound cell including a flat cell 1 wound from a starting end of a first diaphragm 30, a first pole piece 10, a second diaphragm 40, and a second pole piece 20, a first pole 50 is connected to the first pole piece 10, and a second pole 60 is connected to the second pole piece 20;
  • the first pole piece 10 includes a first current collector and a first current collector and opposite surfaces of the first current collector.
  • the second pole piece 20 includes a second current collector and a second active material coated on opposite surfaces of the second current collector;
  • the outermost circumference of the second pole piece 20 includes a second single-sided coating area 22, and the surface of the second single-sided coating area 22 toward the center of the wound cell is uncoated with the second activity.
  • the surface of the core center is The first empty current collector region 13 not coated with the first active material; that is, the tail portions of the first pole piece 10 and the second pole piece 20 in the present application are each provided with a single-sided coating area, and the single-sided coated area hollow set
  • the fluid side forms an opposite vest area; the vest area allows the battery core to protect the battery core in the event of abuse such as acupuncture or impact, thereby improving the safety performance of the battery core.
  • the closing end of the first pole piece 10 includes a first empty foil area 11, and the portion of the second pole piece 20 opposite to the first empty foil area 11 includes a second empty foil area 21, the first empty A vest area opposite to the empty current collector is formed between the foil region 11 and the second empty foil region 21, and the empty foil region is a double-sided uncoated region. Also, the vest area can improve the safety of the battery.
  • the length of the first empty foil region 11 is less than or equal to the length of the first single-sided coated region 12, and/or the length of the second empty foil region 21 is less than or equal to the second single-sided coated region.
  • the start end of the first empty foil region 11 and the start end of the second single-sided coating region are located on opposite sides of the flat cell 1, thereby being in a flat cell
  • the opposite sides of the 1 form a vest area, no matter which side of the battery is subjected to abuse or impact, the vest area on both sides can protect the battery, thereby greatly improving the safety performance of the battery.
  • the vest area on one side of the present application is formed by a single-sided coating area of two pole pieces, and is a vest formed by a single-sided coating area and a pole piece being an empty foil area. The energy density of the cells is also improved.
  • the first tab 50 and the second tab 60 are both located at the head of the battery pole piece, as shown in FIG. 2; the first tab 50 is away from the bending point of the first pole piece 10.
  • the distance is greater than the distance of the second tab 60 from the bending point of the second pole piece 20, that is, when the battery is wound counterclockwise, the first tab 50 is located on the left side of the second tab 60, in the thickness of the flat cell 1 Within the projection in the direction, the second one-sided coated area 22 coincides with the second tab 60, and the first empty foil area 11 coincides with the first tab 50.
  • the two vest areas each avoid the thickest position of one of the tabs, thereby further reducing the thickness of the cell and increasing the energy density of the cell; and, in the cell In the middle, the symmetry of the battery core is very good, so that the flatness of the battery core is better, and the deformation of the battery core can be improved.
  • the first tab 50 is also located on the left side of the second tab 60.
  • the second single-sided coated region 22 Coincident with both the first tab 50 and the second tab 60, the first empty foil region 11 and the first tab 50 and the second tab 60 are all coincident.
  • the area of the vest area is increased relative to FIG. 2, and the safety performance of the battery core is further improved; since both vest areas (shown by dashed lines) avoid the thickest positions of all the tabs, The thickness of the cell is further reduced, and the energy density of the cell is further increased; and, in the cell, the symmetry of the cell is good, and the cell deformation can be improved.
  • the length of the first empty foil region 11 is larger than that of the second empty foil region 21, and the tail end of the first empty foil region 11 is separated from the first pole piece 10 surrounding the outermost circumference of the battery by the tail glue. Fixed to complete the winding of the battery core.
  • the starting end of the first empty foil region 11 and the finishing end of the first empty foil region 11 are located in the flat cell 1 with respect to the thickness direction of the flat cell 1. The same side. This arrangement further reduces cell thickness and saves raw materials.
  • the starting end of the first empty foil region 11 and the finishing end of the first empty foil region 11 are located in the flat cell 1 with respect to the thickness direction of the flat cell 1. Relative sides.
  • the arrangement rewinds the first empty foil region 11 by a half circle of the battery core, thereby further improving the safety performance of the battery and facilitating the preparation of the battery core.
  • the length of the first diaphragm 30 and the second diaphragm 40 is greater than the length of the first empty foil region 11, which can increase the friction between the battery core and the packaged aluminum foil, and reduce the core body.
  • the impact force received during the drop process improves the drop resistance of the battery.
  • the center line of the flat cell 1 in the width direction is the cell center line L; the first tab 50 and the second tab 60 are respectively located on both sides of the cell center line L, as shown in FIG. 2 ⁇ Figure 4; the first tab 50 and the second tab 60 can also be located on the same side of the cell centerline L, as shown in Figures 5 and 6.
  • the diaphragm is disposed in a conventional manner, and the first diaphragm 30 and the second diaphragm 40 are wound inside the battery core along the width direction of the flat battery core 1. In one turn, a four-layer separator is formed.
  • the thickness of the battery core may be further reduced by other means.
  • the distance from the starting end of the first diaphragm 30 to the first tab 50 is the head of the first diaphragm 30, and the second diaphragm 40
  • the distance from the starting end to the first tab 50 is the head of the second diaphragm 40; the head of the first diaphragm 30 is disposed parallel to the head of the second diaphragm 40 in the longitudinal direction of the flat cell 1.
  • the first The starting end of the diaphragm 30 can also be connected to the starting end of the second diaphragm 40, that is, the entire diaphragm is used for winding, as shown in FIGS. 7 to 9.
  • the entire diaphragm winding can further simplify the winding method and simplify the cell preparation process.
  • the head of the first diaphragm 30 can be folded back inside the flat cell 1 to form a diaphragm retracting section; the head of the first diaphragm 30 and the head of the second diaphragm 40 can also be inside the flat cell 1 at the same time.
  • the first diaphragm retracting section 301 and the second diaphragm retracting section 401 are formed by folding back. As shown in FIG. 10, in the projection in the thickness direction of the flat cell 1, neither the first diaphragm retracting section 301 nor the second diaphragm retracting section 401 is formed. It coincides with the first tab 50 and the second tab 60. Thereby, the effect of reducing the thickness of the battery core can be achieved to further increase the energy density.
  • the head of the pole piece can also be bent.
  • the distance from the starting end of the second pole piece 20 to the second pole 60 is the head of the second pole piece 20, and the head of the second pole piece 20
  • the portion is folded back inside the flat cell 1 to form a second pole piece folded back portion 24, and as shown in FIG. 11, the second pole piece folded back portion 24 does not coincide with the first tab 50 and the second tab 60.
  • the first diaphragm 30 and the second diaphragm 40 may also be bent together with the head of the second pole piece 20, and the formed folded back portions are not coincident with the first tab 50 and the second tab 60. .
  • the wound cell of the present application may be a multi-pole structure, for example, the tab may be soldered at the empty cathode anode current collector of the outermost ring to increase its charge and discharge rate performance.
  • the winding direction of the battery cell is counterclockwise or clockwise, depending on the core winding device.
  • the second pole piece 20 when the first pole piece 10 is a positive pole piece, the second pole piece 20 is a negative pole piece; or when the first pole piece 10 is a negative pole piece, the second pole piece 20 is a positive pole Polar film.

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  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Secondary Cells (AREA)
  • Connection Of Batteries Or Terminals (AREA)

Abstract

一种卷绕式电芯（1），由第一隔膜（30）、第一极片（10）、第二隔膜（40）和第二极片（20）的起始端卷绕而成，第二极片（20）的最外圈包括第二单面涂覆区域（22），第二单面涂覆区域（22）朝向卷绕式电芯中心的面为未涂覆活性物质的第二空集流体区（23），第一极片（10）上与第二空集流体区（23）相对的部分包括第一单面涂覆区域（12），第一单面涂覆区域（12）背离卷绕式电芯中心的面为未涂覆活性物质的第一空集流体区（13）；第一极片的收尾端包含第一空箔区（11），第二极片（20）上与所述第一空箔区（11）相对的部分包含第二空箔区（21）；第一空箔区（11）的起始端与第二单面涂覆区（22）的起始端位于电芯的厚度方向的相对两侧。在电芯的两平面都形成马甲，从而提高了电芯的安全性。

Description

一种卷绕式电芯 技术领域
本申请涉及二次电池领域，具体讲，涉及一种卷绕式电芯。
背景技术
目前聚合物锂离子电池在不断追求高能量密度，随之而来的安全问题同样是巨大的挑战，许多高能量密度的电芯面临难以通过某些安全测试的风险，比如针刺和撞击安全测试。而常用的改善针刺撞击的方法是通过双面未涂覆的阴阳极集流体形成的外马甲区，且目前此方法仅能在电芯的一面形成马甲区，如图1所示；从而使得当未形成马甲的区域遭受外力撞击时易于引发安全问题，同时也会造成较大的能量密度损失，同时对材料造成浪费。
鉴于此，特提出本申请。
发明内容
本申请的发明目的在于提出一种卷绕式电芯。
为了完成本申请的目的，采用的技术方案为：
本申请涉及一种卷绕式电芯，所述卷绕式电芯包括由第一隔膜、第一极片、第二隔膜和第二极片的起始端卷绕而成的扁平状电芯，所述第一极片上连接有第一极耳，所述第二极片上连接有第二极耳；所述第一极片包括第一集流体和涂覆于第一集流体相对两表面的第一活性物质，所述第二极片包括第二集流体和涂覆于第二集流体相对两表面的第二活性物质，所述第二极片的最外圈包括第二单面涂覆区域，所述第二单面涂覆区域朝向所述卷绕式电芯中心的面为未涂覆所述第二活性物质的第二空集流体区，所述第一极片上与所述第二空集流体区相对的部分包括第一单面涂覆区域，所述第一单面涂覆区域背离所述卷绕式电芯中心的面为未涂覆所述第一活 性物质的第一空集流体区；
所述第一极片的收尾端包含第一空箔区，所述第二极片上与所述第一空箔区相对的部分包含第二空箔区；
相对于所述扁平状电芯的厚度方向，所述第一空箔区的起始端与所述第二单面涂覆区的起始端位于所述扁平状电芯的相对两侧。
优选的，在所述扁平状电芯厚度方向上的投影内，所述第二单面涂覆区域与所述第一极耳和/或所述第二极耳重合。
优选的，在所述扁平状电芯厚度方向上的投影内，所述第一空箔区与所述第一极耳和/或第二极耳重合。
优选的，所述第一空箔区的长度大于所述第二空箔区的长度。
优选的，所述第一空箔区的长度小于等于所述第一单面涂覆区域的长度，和/或所述第二空箔区的长度小于等于所述第二单面涂覆区域的长度。
优选的，所述第一隔膜和/或第二隔膜的长度大于所述第一空箔区的长度。
优选的，所述第一隔膜的起始端到所述第一极耳之间的距离为第一隔膜头部，所述第二隔膜的起始端到所述第一极耳之间的距离为第二隔膜头部；
所述第一隔膜头部与所述第二隔膜头部沿所述扁平状电芯宽度方向平行设置，或所述第一隔膜头部在所述扁平状电芯内部回折形成隔膜回折段，或所述第一隔膜头部和所述第二隔膜头部在所述扁平状电芯内部回折形成隔膜回折段；在所述扁平状电芯厚度方向上的投影内，所述隔膜回折段均不与所述第一极耳和所述第二极耳重合。
优选的，所述第二极片的起始端到第二极耳的距离为第二极片头部，所述第二极片头部在所述扁平状电芯内部回折形成第二极片回折段；和/或，所述第一极片的起始端到第一极耳的距离为第一极片头部，所述第一极片头部在所述扁平状电芯内部回折形成第一极片回折段；在所述扁平状电芯厚度方向上的投影内，所述第一极片回折段和/或所述第二极片回折段均不与所述第一极耳和所述第二极耳重合。
优选的，所述第一隔膜的起始端与所述第二隔膜的起始端相连接。
优选的，所述第一极片为正极极片，所述第二极片为负极极片；或，所述第一极片为负极极片，所述第二极片为正极极片。
本申请的技术方案至少具有以下有益的效果：
本申请通过改善极片设计和卷绕结构，采用单面阴、阳极收尾的技术方案，从而在沿电芯厚度方向的一侧由单面涂覆的空阴阳极集流体形成马甲，沿电芯宽度方向的另一侧则由双面空阴阳极集流体形成马甲，本申请在扁平状电芯的两平面都形成马甲，从而提高了电芯的安全性。
同时，由于本申请通过单面涂覆的极片结尾，可进一步减小电芯的厚度，从而提高电池的能量密度。
并且，由于本申请在扁平状电芯的两平面都形成马甲，平衡了电芯两侧卷曲部分的厚度，从而使电芯的平整度更好，可改善电芯变形。
附图说明
图1为现有二次电芯结构示意图；
图2为本申请某一具体实施方式中的卷绕式电芯结构示意图；
图3为本申请某一具体实施方式中的卷绕式电芯结构示意图；
图4为本申请某一具体实施方式中的卷绕式电芯结构示意图；
图5为本申请某一具体实施方式中的卷绕式电芯结构示意图；
图6为本申请某一具体实施方式中的卷绕式电芯结构示意图；
图7为本申请某一具体实施方式中的卷绕式电芯结构示意图；
图8为本申请某一具体实施方式中的卷绕式电芯结构示意图；
图9为本申请某一具体实施方式中的卷绕式电芯结构示意图；
图10为本申请某一具体实施方式中的卷绕式电芯结构示意图；
图11为本申请某一具体实施方式中的卷绕式电芯结构示意图；
图12为本申请某一具体实施方式中的卷绕式电芯结构示意图；
其中：
1-扁平状电芯；
10-第一极片；
11-第一空箔区；
12-第一单面涂覆区域；
13-第一空集流体区；
20-第二极片；
21-第二空箔区；
22-第二单面涂覆区域；
23-第二空集流体区；
24-第二极片回折段；
30-第一隔膜；
301-第一隔膜回折段；
40-第二隔膜；
401-第二隔膜回折段；
50-第一极耳；
60-第二极耳；
L-电芯中线。
具体实施方式
下面结合具体实施例，进一步阐述本申请。应理解，这些实施例仅用于说明本申请而不用于限制本申请的范围。文中所述“左”、“右”均以附图中的二次电池电芯的放置状态为参照。
本申请实施例涉及一种卷绕式电芯，包括由第一隔膜30、第一极片10、第二隔膜40和第二极片20的起始端卷绕而成的扁平状电芯1，第一极片10上连接有第一极耳50，第二极片20上连接有第二极耳60；第一极片10包括第一集流体和涂覆于第一集流体相对两表面的第一活性物质，第二极片20包括第二集流体和涂覆于第二集流体相对两表面的第二活性物质；
在本申请实施例中，第二极片20的最外圈包括第二单面涂覆区域22，第二单面涂覆区域22朝向卷绕式电芯中心的面为未涂覆第二活性物质的第二空集流体区23，第一极片10上与第二空集流体区23相对的部分包括第一单面涂覆区域12，第一单面涂覆区域12背离卷绕式电芯中心的面为 未涂覆第一活性物质的第一空集流体区13；即本申请中第一极片10和第二极片20的尾部均设置有单面涂覆区域，以单面涂覆区域中空集流体侧形成相对的马甲区；该马甲区使电芯在面临针刺或者撞击等滥用状况时，形成对电芯的保护，提高了电芯的安全性能。
在本申请实施例中，第一极片10的收尾端包含第一空箔区11，第二极片20上与第一空箔区11相对的部分包含第二空箔区21，第一空箔区11与第二空箔区21之间形成了空集流体相对的马甲区，空箔区为双面未涂覆区域。同样，该马甲区可提高电池的安全性能。
在本申请实施例中，第一空箔区11的长度小于等于第一单面涂覆区域12的长度，和/或所述第二空箔区21的长度小于等于第二单面涂覆区域22的长度。
并且，相对于扁平状电芯1的厚度方向，第一空箔区11的起始端与第二单面涂覆区的起始端位于扁平状电芯1的相对两侧，从而在扁平状电芯1的相对两侧均形成马甲区，无论电池的哪个面受到针刺或者撞击等滥用状况，两侧的马甲区均能对电池形成保护，从而大大提高电池的安全性能。并且，本申请通过一侧的马甲区是由两个极片的单面涂覆区形成，相对于一个极片为单面涂覆区、一个极片为空箔区所形成的马甲来讲，电芯的能量密度也得到提升。
在本申请实施例中，当第一极耳50和第二极耳60均位于电池极片的头部时，如图2所示；第一极耳50距离第一极片10弯折点的距离大于第二极耳60距离第二极片20弯折点的距离，即当电池逆时针卷绕时，第一极耳50位于第二极耳60的左侧，在扁平状电芯1厚度方向上的投影内，第二单面涂覆区域22与第二极耳60重合，第一空箔区11与第一极耳50重合。在该实施例中，两个马甲区(如虚线所示)各避开一个极耳的最厚位置，从而可进一步减小电芯的厚度，提高电芯的能量密度；并且，在该电芯中，电芯的对称性很好，使电芯的平整度更好，可改善电芯变形。
在本申请实施例中，如图3所示，第一极耳50也位于第二极耳60的左侧，在扁平状电芯1厚度方向上的投影内，第二单面涂覆区域22与第一极耳50和第二极耳60均重合，第一空箔区11与第一极耳50和第二极耳 60均重合。在该实施例中，相对于图2来讲，马甲区的面积增加，电芯的安全性能得到进一步改善；由于两个马甲区(如虚线所示)均避开所有极耳的最厚位置，电芯的厚度进一步减小，电芯的能量密度进一步提高；并且，在该电芯中，电芯的对称性很好，也可改善电芯变形。
在本申请实施例中，第一空箔区11的长度大于第二空箔区21，通过尾部胶将第一空箔区11的尾端与围绕电芯最外圈的第一极片10相固定，完成电芯的卷绕。
在本申请实施例中，如图2所示，相对于扁平状电芯1的厚度方向，第一空箔区11的起始端与第一空箔区11的收尾端均位于扁平状电芯1的同侧。该设置方式可进一步减少电芯厚度，并节约原料。
在本申请实施例中，如图3所示，相对于扁平状电芯1的厚度方向，第一空箔区11的起始端与第一空箔区11的收尾端位于扁平状电芯1的相对两侧。该设置方式将第一空箔区11再卷绕电芯半圈，从而可进一步提高电池的安全性能并方便电芯的制备。
在本申请实施例中，如图4所示，第一隔膜30和第二隔膜40的长度大于第一空箔区11的长度，可增加电芯与包装铝箔间的摩擦力，减少电芯主体在跌落过程中受到的冲击力，提高电芯的抗跌落性能。
在本申请实施例中，扁平状电芯1在宽度方向上的中心线为电芯中线L；第一极耳50和第二极耳60可分别位于电芯中线L的两侧，如图2～图4所示；第一极耳50和第二极耳60也可位于电芯中线L的同侧，如图5和图6所示。
在本申请实施例中，如图2～图6所示，隔膜的设置方式可采用常规方式，将第一隔膜30和第二隔膜40沿扁平状电芯1的宽度方向在电芯内部卷绕一圈，形成4层隔离膜。
在本申请实施例中，也可采用其他方式进一步降低电芯的厚度，例如，第一隔膜30的起始端到第一极耳50之间的距离为第一隔膜30头部，第二隔膜40的起始端到第一极耳50之间的距离为第二隔膜40头部；第一隔膜30头部与第二隔膜40头部沿扁平状电芯1长度方向平行设置。当第一隔膜30头部与第二隔膜40头部沿扁平状电芯1长度方向平行设置时，第一 隔膜30的起始端与第二隔膜40的起始端还可相连接，即采用整条隔膜进行卷绕，如图7～图9所示。采用整条隔膜卷绕可进一步简化卷绕方法，简化电芯制备工艺。
在本申请实施例中，第一隔膜30头部可在扁平状电芯1内部回折形成隔膜回折段；第一隔膜30头部和第二隔膜40头部在扁平状电芯1内部也可同时回折形成第一隔膜回折段301和第二隔膜回折段401，如图10所示，在扁平状电芯1厚度方向上的投影内，第一隔膜回折段301和第二隔膜回折段401均不与第一极耳50和第二极耳60重合。从而可达到不同程度降低电芯厚度的效果，进一步提高能量密度。
为了方便电池的卷绕，还可将极片的头部进行弯折，第二极片20的起始端到第二极耳60的距离为第二极片20头部，第二极片20头部在扁平状电芯1内部回折形成第二极片回折段24，如图11所示，第二极片回折段24均不与第一极耳50和第二极耳60重合。
如图12所示，第一隔膜30和第二隔膜40还可与第二极片20的头部一起弯折，所形成的回折段均不与第一极耳50和第二极耳60重合。
在本申请实施例中，本申请的卷绕式电芯可为多极耳结构，例如可在在最外圈的空阴阳极集流体处焊接极耳，增加其充放电倍率性能。
在本申请实施例中，电芯的卷绕方向为逆时针或顺时针，根据电芯卷绕设备而定。
在本申请实施例中，当第一极片10为正极极片时，第二极片20为负极极片；或，当第一极片10为负极极片时，第二极片20为正极极片。
本申请虽然以较佳实施例公开如上，但并不是用来限定权利要求，任何本领域技术人员在不脱离本申请构思的前提下，都可以做出若干可能的变动和修改，因此本申请的保护范围应当以本申请权利要求所界定的范围为准。

Claims (10)

  1. 一种卷绕式电芯，所述卷绕式电芯包括由第一隔膜、第一极片、第二隔膜和第二极片的起始端卷绕而成的扁平状电芯，所述第一极片上连接有第一极耳，所述第二极片上连接有第二极耳；所述第一极片包括第一集流体和涂覆于第一集流体相对两表面的第一活性物质，所述第二极片包括第二集流体和涂覆于第二集流体相对两表面的第二活性物质，其特征在于，
    所述第二极片的最外圈包括第二单面涂覆区域，所述第二单面涂覆区域朝向所述卷绕式电芯中心的面为未涂覆所述第二活性物质的第二空集流体区，所述第一极片上与所述第二空集流体区相对的部分包括第一单面涂覆区域，所述第一单面涂覆区域背离所述卷绕式电芯中心的面为未涂覆所述第一活性物质的第一空集流体区；
    所述第一极片的收尾端包含第一空箔区，所述第二极片上与所述第一空箔区相对的部分包含第二空箔区；
    相对于所述扁平状电芯的厚度方向，所述第一空箔区的起始端与所述第二单面涂覆区的起始端位于所述扁平状电芯的相对两侧。
  2. 根据权利要求1所述的卷绕式电芯，其特征在于，在所述扁平状电芯厚度方向上的投影内，所述第二单面涂覆区域与所述第一极耳和/或所述第二极耳重合。
  3. 根据权利要求1或2所述的卷绕式电芯，其特征在于，在所述扁平状电芯厚度方向上的投影内，所述第一空箔区与所述第一极耳和/或第二极耳重合。
  4. 根据权利要求1所述的卷绕式电芯，其特征在于，所述第一空箔区的长度大于所述第二空箔区的长度。
  5. 根据权利要求1所述的卷绕式电芯，其特征在于，所述第一空箔区的长度小于等于所述第一单面涂覆区域的长度，和/或所述第二空箔区的长度小于等于所述第二单面涂覆区域的长度。
  6. 根据权利要求1所述的卷绕式电芯，其特征在于，所述第一隔膜和/或第二隔膜的长度大于所述第一空箔区的长度。
  7. 根据权利要求1所述的卷绕式电芯，其特征在于，所述第一隔膜的起始端到所述第一极耳之间的距离为第一隔膜头部，所述第二隔膜的起始端到所述第一极耳之间的距离为第二隔膜头部；
    所述第一隔膜头部与所述第二隔膜头部沿所述扁平状电芯宽度方向平行设置，或所述第一隔膜头部在所述扁平状电芯内部回折形成隔膜回折段，或所述第一隔膜头部和所述第二隔膜头部在所述扁平状电芯内部回折形成隔膜回折段；在所述扁平状电芯厚度方向上的投影内，所述隔膜回折段均不与所述第一极耳和所述第二极耳重合。
  8. 根据权利要求1所述的卷绕式电芯，其特征在于，所述第二极片的起始端到第二极耳的距离为第二极片头部，所述第二极片头部在所述扁平状电芯内部回折形成第二极片回折段；和/或，所述第一极片的起始端到第一极耳的距离为第一极片头部，所述第一极片头部在所述扁平状电芯内部回折形成第一极片回折段；在所述扁平状电芯厚度方向上的投影内，所述第一极片回折段和/或所述第二极片回折段均不与所述第一极耳和所述第二极耳重合。
  9. 根据权利要求1所述的卷绕式电芯，其特征在于，所述第一隔膜的起始端与所述第二隔膜的起始端相连接。
  10. 根据权利要求1～9任一权利要求所述的卷绕式电芯，其特征在于，所述第一极片为正极极片，所述第二极片为负极极片；或，所述第一极片为负极极片，所述第二极片为正极极片。
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