WO2022077900A1 - 一种集流体及具有集流体的电池 - Google Patents
一种集流体及具有集流体的电池 Download PDFInfo
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- WO2022077900A1 WO2022077900A1 PCT/CN2021/092596 CN2021092596W WO2022077900A1 WO 2022077900 A1 WO2022077900 A1 WO 2022077900A1 CN 2021092596 W CN2021092596 W CN 2021092596W WO 2022077900 A1 WO2022077900 A1 WO 2022077900A1
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- current collector
- support layer
- layer
- conductor layer
- conductor
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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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
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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
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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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/665—Composites
- H01M4/667—Composites in the form of layers, e.g. coatings
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- 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
- the present application relates to the technical field of lithium ion batteries, for example, to a current collector and a battery having a current collector.
- Lithium-ion batteries are formed by winding or superimposing a basic unit structure.
- the basic unit structure is positive electrode/separator/negative electrode.
- the structure is shown in Figure 1.
- the positive electrode and the negative electrode are the places where the electrochemical reaction occurs.
- the current generated by the electrochemical reaction is collected and exported through the current collectors in the positive electrode and the negative electrode. .
- Lithium-ion batteries may be accidentally bumped or squeezed during use. In this case, the pole pieces sometimes break, resulting in piercing the separator, and the positive and negative pole pieces contact to form an internal short circuit.
- Figure 2 The specific situation is shown in Figure 2.
- the current collector has an internal short circuit, the energy stored in the battery will be released in a short time, generating a lot of heat, causing the battery to burn and explode. Therefore, there is a need to continue to improve the situation that lithium-ion batteries are not safe under abusive conditions such as collision or crushing.
- the safety is mainly improved by improving the performance of the diaphragm. For example, improve the puncture strength of the diaphragm, reduce the possibility of the diaphragm being damaged; reduce the thermal shrinkage of the diaphragm at high temperature, and avoid the contact between the positive and negative electrodes caused by the contraction of the diaphragm at high temperature.
- improve the puncture strength of the diaphragm reduce the possibility of the diaphragm being damaged
- reduce the thermal shrinkage of the diaphragm at high temperature reduce the thermal shrinkage of the diaphragm at high temperature, and avoid the contact between the positive and negative electrodes caused by the contraction of the diaphragm at high temperature.
- the internal short circuit will still occur when the lithium-ion battery is abused.
- the present application provides a current collector to improve the unsafe condition of lithium-ion batteries in the related art under abusive conditions such as collision or extrusion.
- a current collector the elongation at break of the current collector is greater than 20%; when not stretched, the sheet resistance of the current collector is less than 100 milliohms/ ⁇ ; when stretched, the current collector has a The sheet resistance increases continuously until the current collector turns off.
- the embodiment of the present application also discloses a preparation method of the above current collector, which includes the following steps: after the conductor layer material is pressed into the conductor layer, the conductor layer and the support layer material are compounded.
- the embodiment of the present application also discloses a preparation method of the above current collector, which includes the following steps: forming a conductor layer by evaporation or sputtering on the surface of the support layer material.
- the embodiment of the present application also discloses a battery including a positive electrode piece, a negative electrode piece, a separator and an electrolyte, wherein the positive electrode piece and/or the negative electrode piece include the current collector as described above.
- FIG. 1 is a schematic structural diagram of the positive and negative pole pieces and the separator.
- FIG. 2 is a schematic diagram of the deformation of a battery in the related art after being subjected to an external force.
- FIG. 3 is a schematic diagram of the deformation of the battery in the present application after being subjected to an external force.
- FIG. 4 is a schematic diagram of the current paths in FIG. 3 .
- FIG. 5 is a schematic diagram showing the relationship between the elongation ratio and the conduction shutdown in Example 2.
- FIG. 6 is a schematic diagram showing the relationship between the elongation ratio and the conduction shutdown in Example 3.
- FIG. 6 is a schematic diagram showing the relationship between the elongation ratio and the conduction shutdown in Example 3.
- the terms “installed”, “connected” and “connected” should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication between two elements.
- installed should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication between two elements.
- FIG. 1 is a schematic structural diagram of the positive and negative pole pieces and the separator. As shown in FIG. 1 , both sides of the positive electrode current collector 1 are coated with positive electrode active materials, and both sides of the negative electrode current collector 3 are coated with negative electrode active materials. The positive electrode current collector 1 and the negative electrode current collector 3 are separated by a separator 2 .
- FIG. 2 is a schematic diagram of the deformation of a battery in the related art after being subjected to an external force.
- the pole piece will deform.
- the current collector will break, causing the pole piece to break and cut off the diaphragm 2.
- the positive pole piece and the negative pole piece are in direct contact, forming an internal short circuit and generating a lot of heat, thereby causing the lithium-ion battery to burn or even explode.
- FIG. 3 shows the deformation of the battery with the current collector after being subjected to external force.
- the current collector can be kept from breaking and tensile deformation occurs, thereby reducing the probability and area of piercing the separator 2 after the pole piece is directly broken.
- the initial sheet resistance of the current collector when it is not stretched, the initial sheet resistance of the current collector is less than 100 m ⁇ / ⁇ ; when it is stretched and deformed by an external force, the sheet resistance of the current collector increases continuously until the current collector turns off.
- Conductive turn-off means that the sheet resistance at the short circuit of the current collector increases rapidly, for example, to 2 times or more than the initial sheet resistance, which blocks the conduction of the internal current of the battery.
- the current paths in the battery are shown in Table 4, where R positive and R negative represent the internal resistance of the positive electrode and negative electrode active material, respectively, R copper represents the internal resistance of the negative electrode current collector, and R aluminum represents the internal resistance of the positive electrode current collector.
- the above current collector includes a support layer and a conductor layer, the support layer is made of insulating material, the conductor layer is made of conductive material, and the conductor layers are arranged on both sides of the support layer.
- the thickness of the support layer may be 2-20 ⁇ m, and the thickness of the single-sided conductor layer may be 0.8-5 ⁇ m.
- the support layer is made of polyethylene terephthalate (Polyethylene terephthalate, PET), polypropylene (Polypropylene, PP), polyethylene (Polyethylene, PE), polyimide (Polyimide, PI), polyarylsulfone One or more of them, or other insulating materials with light weight and high strength can be used instead.
- PET polyethylene terephthalate
- PP polypropylene
- PE polyethylene
- PE Polyimide
- PI polyarylsulfone One or more of them, or other insulating materials with light weight and high strength can be used instead.
- the conductor layer is made of aluminum, copper, nickel, silver, gold, carbon, stainless steel, aluminum alloy, copper alloy, nickel alloy, silver alloy, gold alloy, and carbon alloy.
- the conductor layer used as the positive electrode current collector is generally made of aluminum or aluminum alloy material
- the conductor layer used as the negative electrode current collector is generally made of copper or copper alloy material.
- the above-mentioned support layer and conductor layer can be combined together by means of gluing, and the conductor layer can be pressed before combining.
- the composite current collector can be thinned by chemical or electrochemical methods.
- the conductor layer can also be formed by vapor deposition or sputtering of the conductor layer material on the surface of the support layer.
- the aluminum material with a purity of 99.7% is rolled to obtain an aluminum foil with a thickness of 4 microns.
- a 4-micron-thick aluminum foil was compounded on both sides of a 10-micron-thick PET through an adhesive to form a positive current collector, and the current collector surface resistance value was 8 milliohms/ ⁇ .
- the molecular weight of PET is 192.17
- the adhesive is WB888 produced by Wuxi Yuke
- the compounding temperature is 95 degrees Celsius
- the compounding pressure is 0.5 MPa
- the standing time after compounding is 150 hours.
- Example 1 The difference between this example and Example 1 is that: PET with a thickness of 4.5 microns is used, and after the positive electrode current collector is compounded and allowed to stand, 20% NaOH solution is continuously used for chemical corrosion, the temperature is 45 degrees Celsius, and the corrosion time is 1 minute. Then use deionized water to rinse and dry, and the thickness of the single-side aluminum layer on the obtained current collector is 2 microns after chemical etching.
- Example 1 The difference between this example and Example 1 is that 12-micron-thick PET is used as the base material, and aluminum is evaporated on both sides under the vacuum condition of 3 ⁇ 10 -4 Pascals, and the speed of the PET base material is 8 m/min.
- the aluminum wire feeding speed is 1.3 m/min, and the evaporation source is a tungsten boat evaporation source of 15 kilowatts.
- the prepared composite current collector aluminum layer has a thickness of 1.2 microns on one side.
- Example 3 The difference between this example and Example 3 is that a 10-micron-thick PE material is used as the base material, and the single-side thickness of the prepared composite current collector aluminum layer is 0.8 micron.
- Example 3 The difference between this example and Example 3 is that a 15-micron-thick PI material is used as the base material, and the single-side thickness of the prepared composite current collector aluminum layer is 1 micron.
- a copper material with a purity of 99.7% was rolled to obtain a copper foil with a thickness of 5 microns.
- a 5-micron-thick copper foil was compounded on both sides of a 10-micron-thick PET through an adhesive to form a negative current collector, and the current collector surface resistance value was 4 milliohms/ ⁇ .
- the molecular weight of PET is 192.17
- the adhesive is WB888 produced by Wuxi Yuke
- the compounding temperature is 95 degrees Celsius
- the compounding pressure is 0.5 MPa
- the standing time after compounding is 150 hours.
- Example 6 The difference between this example and Example 6 is that a PP material with a thickness of 2 microns is used as the base material, and after the negative current collector is combined and allowed to stand, 20% NaOH solution is continuously used for chemical corrosion, the temperature is 45 degrees Celsius, and the corrosion time is 45 degrees Celsius. for 1 minute, and then rinsed and dried with deionized water, and the thickness of the single-sided copper layer on the obtained current collector was 2 microns after chemical etching.
- Example 6 The difference between this example and Example 6 is that 10-micron-thick PET is used as the base material, and copper is evaporated on both sides under the vacuum condition of 3 ⁇ 10 -4 Pascals, and the speed of the PET base material is 2 m/min.
- the aluminum wire feeding speed is 0.9 m/min, and the evaporation source is a 25-kilowatt tungsten boat evaporation source.
- the thickness of the copper layer on one side of the prepared composite current collector is 0.8 ⁇ m.
- Example 8 The difference between this example and Example 8 is that a 15-micron-thick polyarylsulfone material is used as the base material, and the single-sided copper layer of the prepared composite current collector has a thickness of 2.5 microns.
- Example 8 The difference between this example and Example 8 is that a 7-micron-thick PE material is used as the base material, and the single-sided copper layer of the prepared composite current collector has a thickness of 2 microns.
- Example 2 is taken as an example.
- the tensile samples were 40 mm long by 10 mm wide strips. Stretching uses a universal stretching machine to measure stress and strain. The stretching speed was 25 mm/min. After reaching the desired tensile elongation, the stretching was stopped, and a four-point surface resistance measuring instrument was used to measure the surface resistance.
- Region 1 is an elastic deformation region, corresponding to a stretching ratio of 0% to 3%, at this time, the current collector exhibits a high tensile modulus, and the current collector exhibits elastic deformation.
- Zone 2 is the stretching zone of the aluminum layer, corresponding to a stretching ratio of 3% to 20%. At this time, the tensile modulus of the current collector is small, and the sheet resistance increases but not much. In this case, the aluminum layer can still be continuous. , to achieve electrical connection.
- Zone 3 is the PET stretching zone, corresponding to elongation of 20% to 35.7% to break. At around 20% elongation, the tensile modulus changes and suddenly increases. And the sheet resistance suddenly rises, and a conduction shutdown occurs. This is because the aluminum layer reaches the elongation limit and there is an excess fracture that affects the electrical connection. In the PET stretching area, the sheet resistance is larger. The current collector has poor conductivity, and even if an internal short circuit occurs, the heat generation is small and the safety is high.
- Region 1 is an elastic deformation region, corresponding to a stretching ratio of 0% to 3%, at this time, the current collector exhibits a high tensile modulus, and the current collector exhibits elastic deformation.
- Region 2 is the tensile zone of the aluminum layer, corresponding to the elongation rate of 3% to 25%.
- the tensile modulus of the current collector is small or even negative, and the sheet resistance increases but not much.
- the aluminum layer It can still be continuous and realize electrical connection.
- the aluminum layer in this example is vapor-deposited, the density and strength of the aluminum layer are poor, so the tensile zone modulus of the aluminum layer is low.
- Zone 3 is a PET stretching zone, corresponding to an elongation of 25% to break. At around 25% elongation, the tensile modulus changes and suddenly increases. And the sheet resistance suddenly rises, and a conduction shutdown occurs. This is because the aluminum layer reaches the elongation limit and there is an excess fracture that affects the electrical connection. In the PET stretching area, the sheet resistance is larger. The current collector has poor conductivity, and even if an internal short circuit occurs, the heat generation is small and the safety is high.
- the current collectors prepared in the above Examples 1-10 and Comparative Examples 1-2 were made into batteries, and the battery safety performance test was carried out.
- the combination of the current collectors and the test results are shown in Table 2.
- the puncture test (Nail), the impact test (Impact), and the crush test (Crush) of the lithium ion battery (secondary battery) are all carried out in accordance with the UN38.3 lithium ion battery test standard.
- Example 6 60% 100% 60%
- Example 12 Example 2
- Example 6 60% 100% 80%
- Example 13 Example 3
- Example 7 100% 100% 100%
- Example 14 Example 4
- Example 8 100% 100% 100%
- Example 15 Example 5
- Example 9 100% 100%
- Example 16 Example 2
- Example 10 100% 100% Comparative Example 5
- Comparative Example 6 Example 3 Comparative Example 2 20% 20%
- Comparative Example 7 Comparative Example 1
- the puncture test pass rate, the impact test pass rate and the extrusion test pass rate of the battery made of the composite current collector in the related art are obviously lower than those of the battery using the present application.
- the batteries made of the composite current collectors described above illustrate that the composite current collectors described in this application can be used in secondary batteries and can greatly improve the safety performance and service life of secondary batteries.
- the elongation at break of the current collector is limited to be greater than 20%.
- the current collector is not easily broken after being stretched and deformed. The probability and area of piercing the diaphragm.
- the sheet resistance of the current collector continues to increase until the current collector turns off the conduction, which can reduce the probability of combustion and explosion and improve the safety of lithium-ion batteries.
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Abstract
本申请公开了一种集流体。其中,该集流体的断裂延伸率大于20%;在未拉伸时,集流体的面电阻小于100毫欧姆/□;在拉伸时,集流体的面电阻不断增大,直至集流体出现导电关断。
Description
本申请要求在2020年10月16日提交中国专利局、申请号为202011111137.6的中国专利申请的优先权,该申请的全部内容通过引用结合在本申请中。
本申请涉及锂离子电池技术领域,例如涉及到一种集流体及具有集流体的电池。
锂离子电池由基本单元结构卷绕或者叠加构成,基本单元结构为正极/隔膜/负极,结构如图1所示。其中正极和负极是发生电化学反应的地方,通过正极和负极中的集流体,将电化学反应生成的电流收集并导出;隔膜负责将正极和负极分隔开,避免正负极发生接触出现短路。
锂离子电池在使用过程中,会发生意外的碰撞或者挤压等情况。在这种情况下,有时会发生极片断裂,导致刺穿隔膜,发生正负极极片接触形成内短路,具体情况如图2所示。集流体发生内短路时,会导致电池内部储存的能量在短时间内释放出来,产生大量热,导致电池发生燃烧爆炸。因此,需要继续改善锂离子电池在碰撞或者挤压等滥用条件下不安全的情况。
相关技术中主要是通过提高隔膜性能来提升安全性。例如提高隔膜穿刺强度,降低隔膜被破坏的可能性;降低隔膜在高温下的热收缩量,避免高温时隔膜收缩导致正负极接触。然而仅仅提高隔膜性能,锂离子电池滥用时仍然会发生内短路。
发明内容
以下是对本文详细描述的主题的概述。本概述并非是为了限制权利要求的保护范围。
本申请提供一种集流体,改善相关技术中锂离子电池在碰撞或者挤压等滥用条件下不安全的情况。
本申请实施例采用以下技术方案:一种集流体,集流体的断裂延伸率大于 20%;在未拉伸时,集流体的面电阻小于100毫欧姆/□;在拉伸时,集流体的面电阻不断增大,直至集流体出现导电关断。
本申请实施例还公开了一种上述集流体的制备方法,包括以下步骤:将导体层材料压制成导体层后,将导体层与支撑体层材料复合。
本申请实施例还公开了一种上述集流体的制备方法,包括以下步骤,在支撑体层材料表面进行蒸镀或者溅射方法形成导体层。
本申请实施例还公开了一种电池,包括正极极片、负极极片、隔膜和电解质,其中,正极极片和/或负极极片包括如上所述的集流体。
在阅读并理解了附图和详细描述后,可以明白其他方面。
下面结合附图和实施例对本申请说明。
图1是正负极极片与隔膜的结构示意图。
图2是相关技术中电池受到外力后发生形变的示意图。
图3是本申请中电池受到外力后发生形变的示意图。
图4是图3中电流通路的示意图。
图5是实施例2的拉伸率与导电关断的关系示意图。
图6是实施例3的拉伸率与导电关断的关系示意图。
以下结合附图对本申请实施例进行详细说明。应当理解,此处所描述的示例实施例是本申请一部分实施例,而不是全部的实施例,仅仅用以解释本申请实施例,并不用于限定本申请实施例,本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例,都属于本申请保护的范围。
在本申请的描述中,需要说明的是,术语“中心”、“中”、“上”、“下”、“左”、“右”、“内”、“外”、“顶”、“底”、“侧”、“竖直”、“水平”等指示的方位或位置关系为基于附图所示的方位或位置关系,仅是为了便于描述本申请和简化描述,而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作,因此不能理解为对本申请的限制。此外,术语“一”、“第一”、“第二”、“第三”、“第四”、“第五”、“第六”仅用于描述目的,而不能理解为指示或暗示相对重要性。
在本申请的描述中,需要说明的是,除非另有明确的规定和限定,术语“安装”、“相连”、“连接”应做广义理解,例如,可以是固定连接,也可以是可拆卸连接,或一体地连接;可以是机械连接,也可以是电连接;可以是直接相连,也可以通过中间媒介间接相连,可以是两个元件内部的连通。对于本领域的普通技术人员而言,可以具体情况理解上述术语在本申请中的具体含义。
出于简明和说明的目的,实施例的原理主要通过参考例子来描述。在以下描述中,很多细节被提出用以提供对实施例的彻底理解。然而明显的是,对于本领域普通技术人员,这些实施例在实践中可以不限于这些细节。在一些实例中,没有详细地描述公知方法和结构,以避免无必要地使这些实施例变得难以理解。另外,所有实施例可以互相结合使用。
图1是正负极极片与隔膜的结构示意图。如图1所示,正极集流体1两侧涂覆有正极活性材料,负极集流体3两侧涂覆有负极活性材料,正极集流体1和负极集流体3之间通过隔膜2分隔开。
图2是相关技术中电池受到外力后发生形变的示意图。如图2所示,当电池受到针刺、撞击或者挤压时,极片会发生形变。当极片在剪切力作用下形变程度大于集流体的断裂延伸率(例如相关技术中的铜箔铝箔的断裂延伸率都小于5%)时,集流体会断裂,导致极片断裂并切断隔膜2,使得正极极片和负极极片直接接触,形成内短路,产生大量热量,从而引发锂离子电池燃烧甚至爆炸。
对此,本申请公开了一种集流体,其断裂延伸率大于20%,图3显示了具有该集流体的电池受到外力后发生形变的情况。如图3所示,当电池受到针刺、撞击或挤压时,能够保持集流体不断裂且产生拉伸形变,从而减少极片直接断裂后刺穿隔膜2的几率和面积。
对此,在未拉伸时,该集流体的初始面电阻小于100毫欧姆/□;在受到外力产生拉伸形变时,集流体的面电阻不断增大,直至集流体出现导电关断。导电关断,指的是集流体短路处的面电阻迅速增大,例如增大至初始面电阻的2倍或2倍以上,阻断电池内部电流的导通。在一实施例中,电池内的电流通路如表4所示,其中的R
正和R
负分别表示正极和负极活性物质内阻,R
铜表示负极集流体内阻,R
铝表示正极集流体内阻,R
短路表示正负极在短路处接触形成的短路电阻。由于锂离子电池电压是固定的U,锂离子电池的短路发热功率为P=U
2/R,其中R=R
正+R
负+R
铜+R
铝+R
短路。因此,通过提升R
短路来提升R,可以降低发热功率P,从而减少发生燃烧爆炸的几率,提升锂离子电池安全性。
此外,上述的集流体包括支撑体层和导体层,支撑体层采用绝缘材料制成,导体层采用导电材料制成,导体层设置在支撑体层的两侧。其中,为了保证集流体具备大于20%的断裂延伸率,支撑体层的厚度可以为2-20μm,单侧导体层的厚度为0.8-5μm。
支撑体层采用聚对苯二甲酸乙二醇酯(Polyethylene terephthalate,PET)、聚丙烯(Polypropylene,PP)、聚乙烯(Polyethylene,PE)、聚酰亚胺(Polyimide,PI)、聚芳砜中的一种或多种,或者也可以采用其他质量轻、强度大的绝缘材料作为替代。
导体层采用铝、铜、镍、银、金、碳、不锈钢、铝合金、铜合金、镍合金、银合金、金合金、碳合金制成。在一实施例中,用作正极集流体的导体层一般采用铝或铝合金材料制成,而作为负极集流体的导体层一般采用铜或铜合金材料制成。
对此,上述的支撑体层和导体层可以通过胶粘的方式复合在一起,导体层在复合之前可以进行压制。复合后的集流体可以通过化学或者电化学方法减薄。
此外,还可以通过在支撑体层表面蒸镀或者溅射导体层材料的方式形成导体层。
下面通过实施例来说明本申请的技术方案,但本申请并不限于这些实施例。
【实施例1】
将纯度99.7%的铝材进行轧制加工,获得4微米厚的铝箔。将4微米厚的铝箔通过胶黏剂分别复合在10微米厚的PET的两侧,形成正极集流体,集流体方阻面电阻值为8毫欧姆/□。其中PET分子量192.17,胶黏剂为无锡宇科生产的WB888胶,复合的温度为95摄氏度,复合压力0.5兆帕,复合后静置时间为150小时。
【实施例2】
本实施例与实施例1的不同之处在于:使用4.5微米厚的PET,在正极集流体复合静置后,继续采用20%NaOH溶液进行化学腐蚀,温度为45摄氏度,腐蚀时间为1分钟,然后使用去离子水冲洗烘干,获得的集流体上单侧铝层厚度经过化学腐蚀后为2微米。
【实施例3】
本实施例与实施例1的不同之处在于:采用12微米厚的PET作为基材,在3×10
-4帕斯卡的真空条件下进行双侧蒸镀铝,PET基材速度8米/分钟,铝材送 丝速度为1.3米/分钟,蒸发源为15千瓦的钨舟蒸发源。制备得到的复合集流体铝层单侧厚度1.2微米。
【实施例4】
本实施例与实施例3的不同之处在于:采用10微米厚的PE材料作为基材,制备得到的复合集流体铝层单侧厚度0.8微米。
【实施例5】
本实施例与实施例3的不同之处在于,采用15微米厚的PI材料作为基材,制备得到的复合集流体铝层单侧厚度1微米。
【实施例6】
将纯度99.7%的铜材进行轧制加工,获得5微米厚的铜箔。将5微米厚的铜箔通过胶黏剂分别复合在10微米厚的PET的两侧,形成负极集流体,集流体方阻面电阻值为4毫欧姆/□。其中PET分子量192.17,胶黏剂为无锡宇科生产的WB888胶,复合的温度为95摄氏度,复合压力0.5兆帕,复合后静置时间为150小时。
【实施例7】
本实施例与实施例6的不同之处在于:采用2微米厚的PP材料作为基材,在负极集流体复合静置后,继续采用20%NaOH溶液进行化学腐蚀,温度为45摄氏度,腐蚀时间为1分钟,然后使用去离子水冲洗烘干,获得的集流体上单侧铜层厚度经过化学腐蚀后为2微米。
【实施例8】
本实施例与实施例6的不同之处在于:采用10微米厚的PET作为基材,在3×10
-4帕斯卡的真空条件下进行双侧蒸镀铜,PET基材速度2米/分钟,铝材送丝速度为0.9米/分钟,蒸发源为25千瓦的钨舟蒸发源。制备得到的复合集流体单侧铜层厚度0.8微米。
【实施例9】
本实施例与实施例8的不同之处在于:采用15微米厚的聚芳砜材料作为基材,制备得到的复合集流体单侧铜层厚度2.5微米。
【实施例10】
本实施例与实施例8的不同之处在于:采用7微米厚的PE材料作为基材,制备得到的复合集流体单侧铜层厚度2微米。
为了说明本申请技术方案的技术效果,测试上述实施例制得的集流体的面电阻及断裂延伸率,并与相关技术中的铝箔(对比例1)、铜箔(对比例2)进行对比。其中,铝箔的厚度为9微米,铜箔的厚度为6微米。测试结果如表1所示。
表1
由表1可知,本申请中的集流体的断裂延伸率远大于相关技术中铝箔、铜箔的断裂延伸率。
基于此,以实施例2为例。拉伸样品为40毫米长,10毫米宽长条。拉伸采用万能拉伸机,测量应力和应变。拉伸速度为25毫米/分钟。达到需要的拉伸延伸率后,停止拉伸,并采用四探针面电阻测量仪进行面电阻测量。实施例2的拉伸率与导电关断的关系如图5所示,其中拉伸模量=拉伸力/拉伸率,拉伸力-拉伸率曲线的切线斜率即为拉伸模量,根据模量变化可以把拉伸过程分为三个区域:
区域1为弹性形变区,对应拉伸率0%~3%,此时集流体体现出很高的拉伸模量,集流体呈现弹性变形。
区域2为铝层拉伸区,对应拉伸率3%~20%,此时集流体的拉伸模量较小,同时面电阻增加但是增加不大,这种情况下铝层还是能够连续的,实现电连接。
区域3为PET拉伸区,对应延伸率20%~35.7%断裂。在延伸率20%左右,拉伸模量发生了变化,突然增大。并且面电阻突然升高,发生了导电关断。这是因为铝层达到延伸极限,出现多出断裂,导致电连接受影响。在PET拉伸区,面电阻均较大。集流体导电差,即使发生内短路,发热也较小,安全性较高。
同样地,实施例3的拉伸率与导电关断的关系如图6所示,根据模量变化可以把拉伸过程分为三个区域:
区域1为弹性形变区,对应拉伸率0%~3%,此时集流体体现出很高的拉伸模量,集流体呈现弹性变形。
区域2为铝层拉伸区,对应拉伸率3%~25%,此时集流体的拉伸模量较小甚至是负值,同时面电阻增加但是增加不大,这种情况下铝层还是能够连续的,实现电连接。与实施例2相比,由于本实施例中铝层为蒸镀,铝层的致密度和强度较差,因此铝层拉伸区模量较低。
区域3为PET拉伸区,对应延伸率25%~断裂。在延伸率25%左右,拉伸模量发生了变化,突然增大。并且面电阻突然升高,发生了导电关断。这是因为铝层达到延伸极限,出现多出断裂,导致电连接受影响。在PET拉伸区,面电阻均较大。集流体导电差,即使发生内短路,发热也较小,安全性较高。
下面,将上述实施例1-10及对比例1-2制得的集流体制成电池,并进行电池安全性能测试,集流体的组合以及测试结果如表2所示。其中,锂离子电池(二次电池)进行穿刺测试(Nail)、撞击测试(Impact)、挤压测试(Crush),均依照UN38.3锂离子电池测试标准进行。
表2
正极集流体 | 负极集流体 | 穿刺测试通过率 | 撞击测试通过率 | 挤压测试通过率 | |
实施例11 | 实施例1 | 实施例6 | 60% | 100% | 60% |
实施例12 | 实施例2 | 实施例6 | 60% | 100% | 80% |
实施例13 | 实施例3 | 实施例7 | 100% | 100% | 100% |
实施例14 | 实施例4 | 实施例8 | 100% | 100% | 100% |
实施例15 | 实施例5 | 实施例9 | 100% | 100% | 100% |
实施例16 | 实施例2 | 实施例10 | 100% | 100% | 100% |
对比例5 | 实施例2 | 对比例2 | 20% | 20% | 20% |
对比例6 | 实施例3 | 对比例2 | 20% | 20% | 20% |
对比例7 | 对比例1 | 实施例6 | 0% | 0% | 0% |
对比例8 | 对比例1 | 实施例8 | 0% | 0% | 0% |
由表2所示,采用了相关技术中的复合集流体制成的电池(对比例5-8)的 穿刺测试通过率、撞击测试通过率以及挤压测试通过率均明显低于采用本申请所述的复合集流体制成的电池(实施例11-16),说明本申请所述的复合集流体,应用于二次电池中,能够大大提高二次电池的安全性能和使用寿命。
尽管上面对本申请说明性的示例实施方式进行了描述,以便于本技术领域的技术人员能够理解本申请,但是本申请不仅限于示例实施方式的范围,对本技术领域的普通技术人员而言,只要各种变化只要在所附的权利要求限定和确定的本申请精神和范围内,一切利用本申请构思的申请创造均在保护之列。
与相关技术相比,本申请通过限定集流体的断裂延伸率大于20%,当电池受到针刺、撞击或者挤压时,集流体产生拉伸形变后不容易断裂,减少极片直接断裂后刺穿隔膜的几率和面积。同时,在受到外力产生拉伸形变时,集流体的面电阻不断增大,直至集流体出现导电关断,从而能够减少发生燃烧爆炸的几率,提升锂离子电池安全性。
Claims (11)
- 一种集流体,所述集流体的断裂延伸率大于20%;在未拉伸时,所述集流体的初始面电阻小于100毫欧姆/□;在拉伸过程中,所述集流体的面电阻不断增大;在所述集流体断裂前,所述集流体出现导电关断。
- 根据权利要求1所述的集流体,其中,所述集流体具有:支撑体层,所述支撑体层采用绝缘材料制成;导体层,所述支撑体层的第一侧和第二侧分别复合有所述导体层。
- 根据权利要求1所述的集流体,其中,所述支撑体层采用聚对苯二甲酸乙二醇酯PET、聚丙烯PP、聚乙烯PE、聚酰亚胺PI、聚芳砜中的一种或多种材料制成。
- 根据权利要求1所述的集流体,其中,所述支撑体层的厚度为2-20μm。
- 根据权利要求1所述的集流体,其中,所述导体层采用以下之一的材料制成:铝、铜、镍、银、金、碳、不锈钢、铝合金、铜合金、镍合金、银合金、金合金,以及碳合金。
- 根据权利要求5所述的集流体,其中,位于所述支撑体层的第一侧和第二侧的所述导体层的厚度分别为0.8-5μm。
- 根据权利要求1所述的集流体,其中,在所述集流体断裂前,所述集流体的面电阻增大至所述初始面电阻的2倍或2倍以上。
- 一种集流体的制备方法,用于制备如权利要求1所述的集流体,所述集流体包括导体层和支撑体层包括:将导体层材料压制成所述导体层后,将所述导体层与所述支撑体层复合。
- 根据权利要求8所述的方法,其中,所述导体层与所述支撑体层通过胶粘连接,所述导体层通过化学或者电化学方法减薄。
- 一种集流体的制备方法,用于制备如权利要求1所述的集流体,所述集流体包括导体层和支撑体层,包括:采用蒸镀或者溅射方法在所述支撑体层的表面形成所述导体层。
- 一种电池,包括正极极片、负极极片、隔膜和电解质,其中,所述正极极片和所述负极极片中的至少一种包括如权利要求1-10中任一项所述的集流体。
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CN114824160A (zh) * | 2022-04-25 | 2022-07-29 | 江阴纳力新材料科技有限公司 | 复合集流体及其制备方法、电极极片和二次电池 |
CN114843521A (zh) * | 2022-04-25 | 2022-08-02 | 江阴纳力新材料科技有限公司 | 复合集流体及其制备方法、电极极片和二次电池 |
CN114883574A (zh) * | 2022-04-25 | 2022-08-09 | 江阴纳力新材料科技有限公司 | 复合集流体及其制备方法、电极极片和二次电池 |
CN114843521B (zh) * | 2022-04-25 | 2023-10-24 | 江阴纳力新材料科技有限公司 | 复合集流体及其制备方法、电极极片和二次电池 |
CN114824160B (zh) * | 2022-04-25 | 2023-10-27 | 江阴纳力新材料科技有限公司 | 复合集流体及其制备方法、电极极片和二次电池 |
CN114883574B (zh) * | 2022-04-25 | 2023-11-03 | 江阴纳力新材料科技有限公司 | 复合集流体及其制备方法、电极极片和二次电池 |
CN115133231A (zh) * | 2022-06-28 | 2022-09-30 | 昆山卓微得焊接科技有限公司 | 基于镍补偿的多层复合集流体与极耳的连接结构及制备方法 |
WO2024131980A1 (zh) * | 2022-12-23 | 2024-06-27 | 安迈特科技(北京)有限公司 | 复合集流体及其制备方法和其在锂离子电池中的应用 |
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