WO2021000781A1 - 二次电池 - Google Patents

二次电池 Download PDF

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Publication number
WO2021000781A1
WO2021000781A1 PCT/CN2020/098122 CN2020098122W WO2021000781A1 WO 2021000781 A1 WO2021000781 A1 WO 2021000781A1 CN 2020098122 W CN2020098122 W CN 2020098122W WO 2021000781 A1 WO2021000781 A1 WO 2021000781A1
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WO
WIPO (PCT)
Prior art keywords
secondary battery
tab
unit
connecting plate
heat absorption
Prior art date
Application number
PCT/CN2020/098122
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English (en)
French (fr)
Inventor
耿天凤
张小文
杨建东
李星
金义矿
刘强
Original Assignee
宁德时代新能源科技股份有限公司
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Publication of WO2021000781A1 publication Critical patent/WO2021000781A1/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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/61—Types of temperature control
    • H01M10/613—Cooling or keeping cold
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/64—Heating or cooling; Temperature control characterised by the shape of the cells
    • H01M10/647—Prismatic or flat cells, e.g. pouch cells
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/654—Means for temperature control structurally associated with the cells located inside the innermost case of the cells, e.g. mandrels, electrodes or electrolytes
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/655—Solid structures for heat exchange or heat conduction
    • H01M10/6551—Surfaces specially adapted for heat dissipation or radiation, e.g. fins or coatings
    • 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

Definitions

  • This application relates to the field of battery technology, and in particular to a secondary battery.
  • the secondary battery generally includes a case, an electrode assembly housed in the case, and a top cover assembly fixed to the case, and the tab unit of the electrode assembly is electrically connected to the electrode terminal of the top cover assembly via a connecting member.
  • the tab unit is directly welded to the connecting part first, and then the tab unit is bent to reduce the space occupied by the tab unit.
  • the embodiment of the present application provides a secondary battery to alleviate the technical problem of damage to the pole piece due to the increase in temperature at the tab in the prior art.
  • the secondary batteries provided by this application include:
  • a housing the housing having an opening and an inner cavity
  • a top cover assembly covering the opening
  • the electrode assembly is located in the inner cavity, and the electrode assembly includes an electrode unit and a tab unit.
  • the electrode unit has two opposite sides, and the number of tab units is two, two The two tab units are respectively arranged on two sides, and each tab unit extends from the side where it is located; and
  • the tab unit is provided with a first heat absorption layer.
  • the secondary battery provided in the present application includes an electrode assembly.
  • the electrode assembly includes an electrode unit and a tab unit.
  • the tab unit is provided with a first heat absorption layer.
  • the first heat absorption layer can absorb heat on the tab unit to make the tab unit.
  • the temperature is reduced, thereby reducing the excessive temperature rise at the connecting parts due to the effect of overcurrent during charging and discharging, and the temperature is transferred from the tab unit to the inside of the secondary battery, thereby reducing the damage of the positive and negative pole pieces and the separator to the secondary battery
  • the possibility of internal short circuit reduces the risk of failure of the secondary battery and improves the safety of the secondary battery.
  • FIG. 1 is a top view of a secondary battery provided by this application in a specific embodiment
  • Figure 2 is an exploded view of Figure 1;
  • FIG. 3 is a schematic diagram of the structure of the electrode assembly in FIG. 2;
  • Figure 4 is a schematic diagram of the structure of the connecting component
  • Fig. 5 is a first structural schematic diagram of the A-A cross-sectional view of Fig. 1;
  • Figure 6 is an enlarged view at a in Figure 5;
  • FIG. 7 is a schematic diagram of the second structure of the A-A cross-sectional view of FIG. 1;
  • Fig. 8 is an enlarged view at b in Fig. 7.
  • Fig. 1 is a top view of the secondary battery provided by this application in a specific embodiment
  • Fig. 2 is an exploded view of Fig. 1
  • Fig. 3 is a schematic structural diagram of the electrode assembly 1 in Fig. 2
  • Fig. 4 is a structure of the connecting member 2 Schematic diagram
  • Figure 5 is the first structural schematic diagram of the AA cross-sectional view of Figure 1
  • Figure 6 is the enlarged view at a in Figure 5
  • Figure 7 is the second structural schematic diagram of the AA cross-sectional view of Figure 1
  • Figure 8 is a diagram The enlarged view at b in 7.
  • the length direction X is defined as the direction with the longest dimension of the casing
  • the height direction Z is defined as perpendicular to the length direction X and is the direction opposite to the opening of the casing and the bottom of the casing.
  • the secondary battery provided by the embodiment of the present application includes a case 4, an electrode assembly 1, a top cover assembly 3 and a connecting member 2.
  • the housing 4 may have a hexahedral shape or other shapes.
  • the housing 4 forms an inner cavity for accommodating the electrode assembly 1 and the electrolyte.
  • One end of the housing 4 forms an opening so that the electrode assembly 1 can be placed in the housing through the opening. 4 inner cavity.
  • the housing 4 may be made of metal materials, such as conductive metal materials such as aluminum or aluminum alloy, or may be made of plastic insulating materials.
  • the electrode assembly 1 includes an electrode unit 11 and a tab unit 12. Along the length direction X, the electrode unit 11 has two opposite sides, the number of tab units 12 is two, and the two tab units are respectively arranged in two On the side, and each tab unit 12 extends from the side where it is located, the tab unit 12 includes a plurality of tabs stacked in a thickness direction, and the thickness direction is the thickness direction of the tab itself.
  • the electrode unit 11 includes an anode pole piece, a cathode pole piece, and an isolation membrane, wherein the isolation membrane is located between adjacent anode pole pieces and cathode pole pieces for separating the anode pole piece and the cathode pole piece.
  • the electrode assembly 1 may be formed by stacking or winding an anode electrode piece, a cathode electrode piece, and a separator between the anode electrode piece and the cathode electrode piece.
  • the anode electrode piece includes an anode current collector (such as copper foil) and an anode active material layer (such as graphite, carbon or silicon) coated on the surface of the anode current collector, and the cathode electrode piece includes a cathode current collector (such as aluminum foil) and coating
  • the cathode active material layer for example, ternary material, lithium iron phosphate, or lithium cobalt oxide
  • the tab unit 12 is connected to the anode pole piece and extends from the electrode unit 11, and the tab unit 12 can be directly cut from the anode current collector; at the cathode of the electrode assembly 1, The tab unit 12 is connected to the cathode pole piece and extends from the electrode unit 11, and the tab unit 12 can be directly formed by cutting the cathode current collector.
  • the connecting component 2 is used to connect the tab unit 12 and the top cover assembly 3.
  • the top cover assembly 3 is arranged to cover the opening and includes a top cover plate 31 and a pole 32.
  • the top cover plate 31 is fixed to the opening of the housing 4, and the top cover plate 31 is provided with a liquid injection hole through which the electrolyte can be injected To the inside of the battery.
  • the top cover plate 31 also includes a sealing element, and the sealing element is in sealing cooperation with the liquid injection hole for sealing the liquid injection hole.
  • the pole 32 is arranged on the top cover plate 31 and includes an anode pole and a cathode pole. The two poles 32 and the corresponding tabs are connected by connecting parts. 2 Electrical connection, the top cover 31 is provided with an explosion-proof opening 311.
  • the tab unit 12 is located on both sides of the secondary battery, the tab unit 12 and the pole 32 need to be connected by the connecting part 2. It is usually necessary to weld the tab unit 12 and the connection part 2. Because the cross-sectional area of the welding part is small, During the charging and discharging process, the temperature of the connecting part 2 is too high due to the influence of overcurrent, and the temperature will be transferred from the tab unit 12 to the inside of the secondary battery, which will damage the positive and negative pole pieces and the separator, resulting in the inside of the secondary battery. Short circuit, causing safety risks.
  • the tab unit 12 is provided with a first heat absorption layer 122b.
  • the first heat absorption layer 122b can absorb the heat on the tab unit 12.
  • the temperature of the tab unit 12 is reduced, thereby reducing the influence of overcurrent during charging and discharging.
  • the temperature rise at the connecting part 2 is too high, and the temperature may be transferred from the tab unit 12 to the inside of the secondary battery, thereby reducing the risk of internal short circuit of the secondary battery due to damage to the positive and negative pole pieces and the separator, and improving the secondary battery’s safety.
  • the first heat absorption layer 122b can absorb the heat on the tab unit 12
  • the local temperature rise of the tab unit 12 can be reduced, thereby reducing the damage to the pole piece or the edge of the isolation film close to the tab unit 12.
  • the resulting partial short circuit of the secondary battery leads to the risk of failure.
  • the first heat absorption layer 122b can be disposed on the tab unit 12 by spraying, bonding, deposition, or the like.
  • the thickness of the first heat absorption layer 122b is less than 0.1 mm, preferably, the thickness of the first heat absorption layer 122b is 0.01-0.1 mm to ensure a better heat absorption effect without losing the energy density of the secondary battery .
  • the first heat absorption layer 122b may be made of a material that can absorb heat.
  • the specific heat capacity of the heat absorption material of the heat absorption layer should be greater than 1 kJ kg-1 K-1.
  • the temperature of the first heat absorption layer 122b itself can be increased to absorb the heat of the tab unit 12 in contact with it, thereby reducing the risk of the heat of the second connecting plate 22 being transferred to the electrode unit 11.
  • the first heat absorption layer 122b is selected from polyethylene, polypropylene, polyvinylidene fluoride, polyvinyl alcohol, polyvinyl chloride, polystyrene, cellulose acetate, ethyl cellulose, polyethylene
  • pyrrolidone and glass fiber materials because these materials have good heat absorption properties, they can absorb the heat of the tab unit 12 in contact with it, thereby reducing the temperature of the tab unit 12 and reducing the second connecting plate There is a risk that the heat of 22 will be transferred to the electrode unit 11.
  • the specific heat capacity of the first heat absorption layer 122 b is greater than the specific heat capacity of the tab unit 12, that is, the specific heat capacity of the material of the first heat absorption layer 122 b is greater than the specific heat capacity of the material of the tab unit 12. Since the specific heat capacity of the first heat absorption layer 122b is greater than the specific heat capacity of the tab unit 12, the first heat absorption layer 122b can be used as a heat absorption medium to take away the heat in the tab unit 12 through the first heat absorption layer 122b.
  • the specific heat capacity of the first heat absorption layer 122b is large, the temperature of the tab unit 12 will not increase significantly, thereby reducing the possibility of temperature transfer from the tab unit 12 to the inside of the secondary battery, thereby reducing the positive and negative pole pieces
  • the safety of the secondary battery is improved due to the risk of internal short circuit due to damage to the isolation film.
  • the tab unit 12 includes a plurality of tabs stacked in the thickness direction; the tab includes a body portion 121 and an extension portion 122.
  • the body portion 121 extends from the side portion, and the extension portion 122 is opposite to the body.
  • the extension 122 includes a first end surface 122a away from the electrode unit 11, and the first heat absorption layer 122b is disposed on the first end surface 122a; and/or, the outer surface of the main body 121 is provided with a A heat absorption layer 122b.
  • the first end surface 122a of the extension 122 away from the electrode unit 11 is provided with a first heat absorption layer 122b, the first heat absorption layer 122b serves as a heat absorption medium, and the tab unit 12 is inserted into the tab unit 12 through the first heat absorption layer 122b.
  • the heat taken away can be transferred to the shell 4 or to the gas inside the shell, so as to prevent the temperature rise at the tab unit 12 from excessively high due to the influence of overcurrent during the charging and discharging process.
  • the ear unit 12 is transmitted to the inside of the secondary battery, thereby preventing damage to the positive and negative pole pieces and the separator, preventing the internal short circuit of the secondary battery, and improving the safety of the secondary battery.
  • the first heat absorption layer 122b may be provided on each layer of tabs.
  • the first heat-absorbing layer 122b can be used as a heat-absorbing medium through the first heat-absorbing layer 122b to take away the heat in each layer of tabs, thereby preventing the tab unit 12 from being affected by overcurrent during charging and discharging.
  • the temperature rises too high, the temperature is transferred from the tabs to the inside of the secondary battery, thereby preventing damage to the positive and negative pole pieces and the separator, preventing the internal short circuit of the secondary battery, and improving the safety of the secondary battery.
  • the first end surface 122a of the extension 122 away from the electrode unit 11 is provided with a first heat absorption layer 122b.
  • the outer surface of each layer of tabs is also provided with a first heat absorption layer 122b.
  • the thermal layer 122b takes away the heat in the tab unit 12 or each layer of tabs, and prevents excessive temperature rise at the tab unit 12 due to overcurrent during the charging and discharging process, and the temperature from the tab unit 12 to the secondary battery Passed internally.
  • the connecting member 2 includes a first connecting plate 21, a second connecting plate 22, and a third connecting plate 23; the first connecting plate 21 and the second connecting plate 22 pass through the first bending The portion 24 is connected, and the second connecting plate 22 and the third connecting plate 23 are connected by the second bending portion 25.
  • the first connecting plate 21 is connected to the top cover assembly 3, and the third connecting plate 23 is connected to the tab unit 12.
  • the second connecting plate 22 includes a second end surface 221, the second end surface 221 is set back to the electrode unit 11; the second end surface 221 is provided with a thermally conductive layer 221a, the thermally conductive layer 221a can produce on the second connecting plate 22 The heat is transferred to the housing 4 or the gas in the housing 4, thereby reducing the temperature of the second connecting plate 22.
  • the second connecting plate 22 and the third connecting plate 23 are connected by the second bending portion 25, and the third connecting plate 23 is connected with the tab unit 12.
  • the temperature rises due to the small flow area.
  • the heat can be transferred through the heat conducting layer 221a
  • the gas into the casing 4 or the casing 4 thereby reducing the possibility of heat transfer from the tab unit 12 to the inside of the secondary battery due to the high temperature at the welding place of the tab unit 12 and the third connecting plate 23, thereby reducing the positive and negative
  • the pole piece and the isolation membrane may be damaged and the internal short circuit of the secondary battery may occur, which improves the safety of the secondary battery.
  • the thermally conductive layer 221a can be disposed on the second connecting plate 22 by spraying, bonding, deposition or the like.
  • the thermal conductive layer 221a may be made of a material with good thermal conductivity.
  • the thermally conductive layer 221a is selected from one or more of graphene, silicone sheet, carbon fiber and boron nitride materials. Because these materials have good thermal conductivity, the second connecting plate that is in contact with it can be The heat of 22 is transferred out, thereby reducing the possibility of heat transfer from the tab unit 12 to the inside of the secondary battery due to the high temperature at the welding place of the tab unit 12 and the third connecting plate 23, thereby reducing the positive and negative pole pieces and the separator The possibility of an internal short circuit in the secondary battery improves the safety of the secondary battery.
  • the thermal conductivity of the thermal conductive layer 221a is greater than the thermal conductivity of the connecting member 2.
  • the thermal conductivity of the material of the thermal conductive layer 221a is greater than the thermal conductivity of the material of the connecting member 2. Since the thermal conductivity of the thermal conductive layer 221a is greater than the thermal conductivity of the connecting component 2, the thermal conductivity of the thermal conductive layer 221a is better than the thermal conductivity of the connecting component 2.
  • the heat of the second connecting plate 22 in contact with it can be transferred out, so that The temperature of the third connecting plate 23 is reduced, thereby reducing the possibility of heat transfer from the tab unit 12 to the inside of the secondary battery due to the high temperature at the welding place of the tab unit 12 and the third connecting plate 23, thereby reducing the positive and negative pole pieces
  • the possibility of internal short-circuit with the isolation membrane of the secondary battery improves the safety of the secondary battery.
  • the thermally conductive layer 221 a is disposed in an area where the second end surface 221 is higher than the top of the second bending portion 25.
  • the thermally conductive layer 221a along the height direction Z, the height area from the top of the second bending portion 25 upward is covered with the thermally conductive layer 221a, so that the coverage of the thermally conductive layer 221a is higher than the entire area of the top of the second bending portion 25, increasing The thermal conductivity of the thermal conductive layer 221a.
  • the thickness of the thermal conductive layer 221a is less than 0.1 mm, preferably, the thickness of the thermal conductive layer 221a is 0.01 to 0.1 mm. In order to ensure better thermal conductivity without losing the energy density of the secondary battery.
  • the second connecting plate 22 includes a third end surface 222 facing the electrode unit 11, and the third end surface 222 is provided with a second heat absorption layer 222a.
  • the second heat absorption layer 222a can absorb the heat on the second connection plate 22, it can absorb the heat of the second connection plate 22 in contact with the second heat absorption layer 222a, and further make the third connection plate 23
  • the temperature of the lug unit 12 is reduced, thereby reducing the heat transfer from the lug unit 12 to the inside of the secondary battery due to the excessively high temperature at the welding place of the lug unit 12 and the third connecting plate 23, which can reduce the local temperature rise of the lug unit 12, and then
  • the risk of partial short-circuit of the secondary battery caused by damage to the pole piece or the edge of the isolation film close to the tab unit 12 is reduced.
  • the second heat absorption layer 222a can be disposed on the third end surface 222 by spraying, bonding, deposition or the like.
  • the thickness of the second heat absorption layer 222a is less than 0.1 mm, preferably, the thickness of the second heat absorption layer 222a is 0.01 to 0.1 mm. To ensure a better heat absorption effect without losing the energy density of the secondary battery.
  • the second heat absorption layer 222a may be made of a material that can absorb heat.
  • the specific heat capacity of the heat absorption material of the heat absorption layer should be greater than 1kJ kg-1 K-1.
  • the temperature of the second heat absorption layer 222a itself can be increased to absorb the heat of the second connecting plate 22 in contact with it, thereby reducing the risk of the heat of the second connecting plate 22 being transferred to the tab unit 12.
  • the second heat absorption layer 222a is selected from polyethylene, polypropylene, polyvinylidene fluoride, polyvinyl alcohol, polyvinyl chloride, polystyrene, cellulose acetate, ethyl cellulose, polyethylene
  • pyrrolidone and glass fiber materials because these materials have good heat absorption properties, they can absorb the heat of the second connecting plate 22 contacting it, thereby reducing the temperature of the second connecting plate 22.
  • the second heat absorption layer 222 a is disposed in an area where the third end surface 222 is lower than the top of the second bending portion 25.
  • the height area from the top of the second bending part 25 downwards covers the second heat absorption layer 222a, so that the coverage of the second heat absorption layer 222a is lower than the top of the second bending part 25 Therefore, the risk of heat transfer from the second connecting plate 22 to the tab unit 12 is reduced.
  • the upper end of the second heat absorption layer 222a and the lower end of the heat-conducting layer 221a can be aligned, and the heat absorbed by the second heat-absorbing layer 222a can be transferred from the heat-conducting layer 221a, which improves the heat dissipation effect.

Abstract

本申请提供了一种二次电池，涉及电池技术领域，所述的二次电池包括：壳体，所述壳体具有开口和内腔；顶盖组件，覆盖于所述开口；电极组件，位于所述内腔，且所述电极组件包括电极单元和极耳单元，沿长度方向X，所述电极单元具有相对设置的两侧部，所述极耳单元从所述侧部延伸出；和连接部件，用于连接所述极耳单元与所述顶盖组件；其中，所述极耳单元设置有第一吸热层，以缓解现有技术中存在的由于极耳处温度升高损伤极片的技术问题。

Description

二次电池
本申请要求于2019年07月01日提交中国专利局、申请号为201921010763.9、申请名称为“二次电池”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电池技术领域，尤其涉及一种二次电池。
背景技术
二次电池通常包括壳体、收容于壳体的电极组件以及固定于壳体的顶盖组件，而电极组件的极耳单元经由连接部件与顶盖组件的电极端子电连接。在装配电极组件和连接部件时，通常先将极耳单元直接焊接于连接部件，然后再将极耳单元弯折，以减少极耳单元占用的空间。
目前针对极耳单元位于两侧的二次电池，由于极耳单元与连接部件的焊接部过流面积较小，焊接部温度升高，温度向二次电池内部蔓延，损伤极片和隔离膜等，导致二次电池内部短路，增加二次电池失效风险。
发明内容
有鉴于此，本申请实施例提供了一种二次电池，以缓解现有技术中存在的由于极耳处温度升高损伤极片的技术问题。
本申请提供的二次电池包括：
壳体，所述壳体具有开口和内腔；
顶盖组件，覆盖于所述开口；
电极组件，位于所述内腔，且所述电极组件包括电极单元和极耳单元，沿长度方向X，所述电极单元具有相对设置的两个侧部，极耳单元的数量为两个，两个极耳单元分别设置在两个侧部上，且每个极耳单元从所在的侧部延伸出；和
连接部件，用于连接所述极耳单元与所述顶盖组件；
其中，所述极耳单元设置有第一吸热层。
本申请提供的技术方案可以达到以下有益效果：
本申请提供的二次电池包括电极组件，电极组件包括电极单元和极耳单元，极耳单元设置有第一吸热层，第一吸热层能吸收极耳单元上的热量，使极耳单元的温度降低，从而减少由于充放电过程中过流影响，连接部件处温升过高，温度从极耳单元向二次电池内部传递，进而降低正负极极片与隔离膜损伤使二次电池内部短路的可能，降低了二次电池失效的风险，提高了二次电池的安全性。
附图说明
图1为本申请所提供二次电池在一种具体实施例中的俯视图；
图2为图1的爆炸图；
图3为图2中电极组件的结构示意图；
图4为连接部件的结构示意图；
图5为图1的A-A向剖视图的第一种结构示意图；
图6为图5中a处的放大图；
图7为图1的A-A向剖视图的第二种结构示意图；
图8为图7中b处的放大图。
具体实施方式
为了更好的理解本申请的技术方案，下面结合附图对本申请实施例进行详细描述。
应当明确，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其它实施例，都属于本申请保护的范围。
在本申请实施例中使用的术语是仅仅出于描述特定实施例的目的，而非旨在限制本申请。在本申请实施例和所附权利要求书中所使用的单数形式的“一种”、“所述”和“该”也旨在包括多数形式，除非上下文清楚地表示其他含义。
应当理解，本文中使用的术语“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
需要注意的是，本申请实施例所描述的“上”、“下”、“左”、“右”等方位词是以附图所示的角度来进行描述的，不应理解为对本申请实施例的限定。此外，在上下文中，还需要理解的是，当提到一个元件连接在另一个元件“上”或者“下”时，其不仅能够直接连接在另一个元件“上”或者“下”，也可以通过中间元件间接连接在另一个元件“上”或者“下”。
图1为本申请所提供二次电池在一种具体实施例中的俯视图；图2为图1的爆炸图；图3为图2中电极组件1的结构示意图；图4为连接部件2的结构示意图；图5为图1的A-A向剖视图的第一种结构示意图；图6为图5中a处的放大图；图7为图1的A-A向剖视图的第二种结构示意图；图8为图7中b处的放大图。
本申请中，定义长度方向X为，壳体的尺寸最长的方向，定义高度方向Z为，与长度方向X垂直，且为壳体的开口和壳体的底部相对的方向。
如图1和图2所示，本申请实施例提供的二次电池包括壳体4、电极组件1、顶盖组件3以及连接部件2。
壳体4可具有六面体形状或者其他形状，该壳体4内部形成内腔，用于容纳电极组件1和电解液，壳体4的一端形成开口，使得电极组件1可通过该开口放置于壳体4的内腔。其中，壳体4可包括金属材料，例如铝或铝合金等导电金属材料制成，也可由塑胶绝缘材料制成。
电极组件1包括电极单元11和极耳单元12，沿长度方向X，电极单元11具有相对设置的两个侧部，极耳单元12的数量为两个，两个极耳单元分别设置在两个侧部上，且每个极耳单元12从所在的侧部延伸出，极耳单元12包括多个沿厚度方向层叠设置的极耳，厚度方向是极耳自身的厚度方向。电极单元11包括阳极极片、阴极极片和隔离膜，其中，隔离膜位于相邻阳极极片与阴极极片之间，用于隔开阳极极片与阴极极片。电极组件1可通过阳极极片、阴极极片和以及位于阳极极片和阴极极片之间的隔离膜一同堆叠或卷绕形成。
其中，阳极极片包括阳极集流体(例如铜箔)和涂覆在阳极集流体表面 的阳极活性物质层(例如石墨、碳或硅)，阴极极片包括阴极集流体(例如铝箔)和涂覆在阴极集流体表面的阴极活性物质层(例如三元材料、磷酸铁锂或钴酸锂)。在电极组件1的阳极，极耳单元12与阳极极片相连，并从电极单元11中伸出，且该极耳单元12可直接由阳极集流体裁切而成；在电极组件1的阴极，极耳单元12与阴极极片相连，并从电极单元11中伸出，且该极耳单元12可直接由阴极集流体裁切形成。
连接部件2用于连接极耳单元12与顶盖组件3。顶盖组件3覆盖开口设置，包括顶盖板31和极柱32，顶盖板31固定于壳体4的开口，顶盖板31上开设有注液孔，电解液可以通过注液孔被注入到电池的内部。顶盖板31还包括密封件，密封件与注液孔密封配合，用于密封注液孔。从而将电极组件1和电解液封闭于壳体4的内腔，极柱32设置于顶盖板31，并包括阳极极柱和阴极极柱，两极柱32与对应的极耳之间通过连接部件2电连接，顶盖板31设置有防爆口311。
极耳单元12位于两侧的二次电池，需使用连接部件2将极耳单元12与极柱32相连，通常需要将极耳单元12与连接部件2焊接，由于焊接部截面积较小，在充放电过程中由于过流影响，连接部件2处温升过高，温度将会从极耳单元12向二次电池内部传递，进而会损伤正负极极片与隔离膜，造成二次电池内部短路，引发安全风险。
为了解决上述技术问题，如图2和图3所示，极耳单元12设置有第一吸热层122b。第一吸热层122b能吸收极耳单元12上的热量，通过将极耳单元12设置有第一吸热层122b，使极耳单元12的温度降低，从而减少充放电过程中由于过流影响，连接部件2处温升过高，温度从极耳单元12向二次电池内部传递的可能，进而减少正负极极片与隔离膜损伤使二次电池内部短路风险，提高了二次电池的安全性。
当电流经过时，由于第一吸热层122b能吸收极耳单元12上的热量，能够降低极耳单元12的局部温升，进而降低由于损伤与极耳单元12相近的极片或隔离膜边缘导致的二次电池局部短路引发失效的风险。
其中，第一吸热层122b可采用喷涂、粘接、沉积等方式设置在极耳单元12上。
第一吸热层122b的厚度小于0.1毫米，较佳的，第一吸热层122b的厚度为0.01～0.1毫米，以保证在不损失二次电池能量密度的基础上保证较 佳的吸热效果。
第一吸热层122b可以由能吸热的材料制成。较佳的，吸热层吸热材料的比热容应大于1kJ kg-1 K-1。在使用时，第一吸热层122b本身的温度能够升高，吸收与它接触的极耳单元12的热量，从而降低第二连接板22的热量传递到电极单元11上的风险。
在一种具体实施方式中，第一吸热层122b选自聚乙烯、聚丙烯、聚偏氟乙烯、聚乙烯醇、聚氯乙烯、聚苯乙烯、醋酸纤维素、乙基纤维素、聚乙烯吡咯烷酮和玻璃纤维材料中的一种或几种，由于这些材料吸热性能好，可以吸收与它接触的极耳单元12的热量，从而使极耳单元12的温度降低，减小第二连接板22的热量传递到电极单元11上的风险。
在一种具体实施方式中，第一吸热层122b的比热容大于极耳单元12的比热容，即第一吸热层122b的材料的比热容大于极耳单元12材料的比热容。由于第一吸热层122b的比热容大于极耳单元12的比热容，因此，第一吸热层122b可以作为吸热介质，通过第一吸热层122b将极耳单元12中的热量带走。由于第一吸热层122b的比热容较大，因此，极耳单元12的温度不会明显升高，从而减少温度从极耳单元12向二次电池内部传递的可能，进而降低正负极极片与隔离膜损伤使二次电池内部短路的风险，提高了二次电池的安全性。
在一种具体实施方式中，极耳单元12包括多个沿厚度方向层叠设置的极耳；极耳包括本体部121和延伸部122，本体部121从侧部延伸出，延伸部122相对于本体部121弯折；沿长度方向X，延伸部122包括远离电极单元11的第一端面122a，第一吸热层122b设置于第一端面122a；和/或，本体部121的外表面设置有第一吸热层122b。
可选的，延伸部122远离电极单元11的第一端面122a上设有第一吸热层122b，第一吸热层122b作为吸热介质，通过第一吸热层122b将极耳单元12中的热量带走，带走的热量可以向壳体4传递，也可以向壳体内部的气体传递，从而防止充放电过程中由于过流影响，极耳单元12处温升过高，温度从极耳单元12向二次电池内部传递，进而防止损伤正负极极片与隔离膜，防止二次电池内部短路，提高了二次电池的安全性。
可选的，由于极耳单元12包括多个沿厚度方向层叠设置的极耳，每一层极耳均包括本体部121和弯折部，第一吸热层122b可以设置在每一层极 耳的外表面，第一吸热层122b可以作为吸热介质，通过第一吸热层122b将每一层极耳中的热量带走，从而防止充放电过程中由于过流影响，极耳单元12处温升过高，温度从极耳向二次电池内部传递，进而防止损伤正负极极片与隔离膜，防止二次电池内部短路，提高了二次电池的安全性。
可选的，延伸部122远离电极单元11的第一端面122a上设有第一吸热层122b，同时，每一层极耳的外表面也均设置第一吸热层122b，通过第一吸热层122b将极耳单元12或者每一层极耳中的热量带走，防止充放电过程中由于过流影响，极耳单元12处温升过高，温度从极耳单元12向二次电池内部传递。
如图4、图5和图6所示，连接部件2包括第一连接板21、第二连接板22和第三连接板23；第一连接板21和第二连接板22通过第一弯折部24连接，第二连接板22和第三连接板23通过第二弯折部25连接。其中第一连接板21与顶盖组件3连接，第三连接板23与极耳单元12连接。沿长度方向X，第二连接板22包括第二端面221，第二端面221背向电极单元11设置；第二端面221上设有导热层221a，导热层221a可以将第二连接板22上产生的热量传递到壳体4或者壳体4内的气体，从而降低第二连接板22的温度。
其中，第二连接板22和第三连接板23通过第二弯折部25连接，第三连接板23与极耳单元12连接。当极耳单元12与第三连接板23焊接处，由于过流面积小，引起温度升高时，热量从第三连接板23传递至第二连接板22后，可以经导热层221a将热量传递到壳体4或者壳体4内的气体，从而减少极耳单元12与第三连接板23焊接处由于温度过高，热量从极耳单元12向二次电池内部传递的可能，进而降低正负极极片与隔离膜损伤发生二次电池内部短路的可能，提高了二次电池的安全性。
导热层221a可采用喷涂、粘接、沉积等方式设置在第二连接板22上。
导热层221a可以由导热性能良好的材料制成。
在一种具体实施方式中，导热层221a选自石墨烯、硅胶片、碳纤维和氮化硼材料中的一种或几种，由于这些材料导热性能好，可以将与它接触的第二连接板22的热量传递出去，从而减少极耳单元12与第三连接板23焊接处由于温度过高，热量从极耳单元12向二次电池内部传递的可能，进而降低正负极极片与隔离膜发生二次电池内部短路的可能，提高了二次电 池的安全性。
在一种具体实施方式中，导热层221a的导热系数大于连接部件2的导热系数。导热层221a的材料的导热系数大于连接部件2材料的导热系数。由于导热层221a的导热系数大于连接部件2的导热系数，从而导热层221a的导热性能要比连接部件2的导热性能好，因此可以将与它接触的第二连接板22的热量传递出去，使第三连接板23的温度降低，从而减少极耳单元12与第三连接板23焊接处由于温度过高，热量从极耳单元12向二次电池内部传递的可能，进而降低正负极极片与隔离膜发生二次电池内部短路的可能，提高了二次电池的安全性。
在一种具体实施方式中，导热层221a设置在第二端面221高于第二弯折部25的顶部的区域。换句话说，沿高度方向Z，从第二弯折部25的顶部向上的高度区域覆盖有导热层221a，使导热层221a的覆盖高于第二弯折部25的顶部的整个区域，提高了导热层221a的导热效果。
导热层221a的厚度小于0.1毫米，较佳的，导热层221a的厚度为0.01～0.1毫米。以在不损失二次电池能量密度的基础上保证较佳的导热效果。
在一种具体实施方式中，沿长度方向X，第二连接板22包括面向电极单元11的第三端面222，第三端面222设置有第二吸热层222a。当电流经过时，由于第二吸热层222a能吸收第二连接板22上的热量，可以将与第二吸热层222a接触的第二连接板22的热量吸收，进一步使第三连接板23的温度降低，从而减少由于极耳单元12与第三连接板23焊接处温度过高，热量从极耳单元12向二次电池内部传递的情况，能够降低极耳单元12的局部温升，进而减少由于损伤与极耳单元12相近的极片或隔离膜边缘导致的二次电池局部短路引发失效的风险。
其中，第二吸热层222a可采用喷涂、粘接、沉积等方式设置在第三端面222上。
第二吸热层222a的厚度小于0.1毫米，较佳的，第二吸热层222a的厚度为0.01～0.1毫米。以保证在不损失二次电池能量密度的基础上保证较佳的吸热效果。
第二吸热层222a可以由能吸热的材料制成。较佳的，吸热层吸热材料比热容应大于1kJ kg-1 K-1。在使用时，第二吸热层222a本身的温度能够升高，吸收与它接触的第二连接板22的热量，从而降低第二连接板22的 热量传递到极耳单元12上的风险。
在一种具体实施方式中，第二吸热层222a选自聚乙烯、聚丙烯、聚偏氟乙烯、聚乙烯醇、聚氯乙烯、聚苯乙烯、醋酸纤维素、乙基纤维素、聚乙烯吡咯烷酮和玻璃纤维材料中的一种或几种，由于这些材料吸热性能好，可以吸收与它接触的第二连接板22的热量，从而使第二连接板22的温度降低。
在一种具体实施方式中，第二吸热层222a设置在第三端面222低于第二弯折部25的顶部的区域。换句话说，沿高度方向Z，从第二弯折部25的顶部向下的高度区域覆盖第二吸热层222a，使第二吸热层222a的覆盖低于第二弯折部25的顶部的区域，从而降低第二连接板22的热量传递到极耳单元12的风险。
如图7和图8所示，第二吸热层222a的上端与导热层221a的下端可以对齐设置，第二吸热层222a吸收的热量可以从导热层221a传递出去，提高了散热效果。
以上仅为本申请的较佳实施例而已，并不用以限制本申请，凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (10)

  1. 一种二次电池，其特征在于，包括：
    壳体，所述壳体具有开口和内腔；
    顶盖组件，覆盖于所述开口；
    电极组件，位于所述内腔，且所述电极组件包括电极单元和极耳单元，沿长度方向(X)，所述电极单元具有相对设置的两个侧部，所述极耳单元的数量为两个，两个所述极耳单元分别设置在两个所述侧部上，且每个所述极耳单元从所在的所述侧部延伸出；和
    连接部件，用于连接所述极耳单元与所述顶盖组件；
    其中，所述极耳单元设置有第一吸热层。
  2. 根据权利要求1所述的二次电池，其特征在于，所述第一吸热层的比热容大于所述极耳单元的比热容。
  3. 根据权利要求1或2所述的二次电池，其特征在于，
    所述极耳单元包括多个沿厚度方向层叠设置的极耳；
    所述极耳包括本体部和延伸部，所述本体部从所述侧部延伸出，所述延伸部相对于所述本体部弯折；
    沿长度方向(X)，所述延伸部包括远离所述电极单元的第一端面，所述第一吸热层设置于所述第一端面；和/或，所述本体部的外表面设置有所述第一吸热层。
  4. 根据权利要求1-3任一项所述的二次电池，其特征在于，
    所述连接部件包括第一连接板、第二连接板和第三连接板；
    所述第一连接板和所述第二连接板通过第一弯折部连接，所述第二连接板和所述第三连接板通过第二弯折部连接；
    沿长度方向(X)，所述第二连接板包括第二端面，所述第二端面背向所述电极单元设置；
    所述第二端面上设有导热层。
  5. 根据权利要求4所述的二次电池，其特征在于，所述导热层的导热系数大于所述连接部件的导热系数。
  6. 根据权利要求4或5所述的二次电池，其特征在于，所述导热层设置在所述第二端面高于所述第二弯折部的顶部的区域。
  7. 根据权利要求4-6任一项所述的二次电池，其特征在于，沿长度方向(X)，所述第二连接板包括面向所述电极单元的第三端面，所述第三端面设置有第二吸热层。
  8. 根据权利要求7所述的二次电池，其特征在于，
    所述第二吸热层设置在所述第三端面低于所述第二弯折部的顶部的区域。
  9. 根据权利要求1-8任一项所述的二次电池，其特征在于，所述第一吸热层选自聚乙烯、聚丙烯、聚偏氟乙烯、聚乙烯醇、聚氯乙烯、聚苯乙烯、醋酸纤维素、乙基纤维素、聚乙烯吡咯烷酮和玻璃纤维材料中的一种或几种。
  10. 根据权利要求4-8任一项所述的二次电池，其特征在于，所述导热层选自石墨烯、硅胶片、碳纤维和氮化硼材料中的一种或几种。
PCT/CN2020/098122 2019-07-01 2020-06-24 二次电池 WO2021000781A1 (zh)

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CN209786061U (zh) * 2019-07-01 2019-12-13 宁德时代新能源科技股份有限公司 二次电池
WO2021248488A1 (zh) * 2020-06-12 2021-12-16 宁德新能源科技有限公司 电池和用电装置

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