WO2019228200A1 - 锂离子二次电池组件及其制备方法和锂离子二次电池 - Google Patents

锂离子二次电池组件及其制备方法和锂离子二次电池 Download PDF

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Publication number
WO2019228200A1
WO2019228200A1 PCT/CN2019/087467 CN2019087467W WO2019228200A1 WO 2019228200 A1 WO2019228200 A1 WO 2019228200A1 CN 2019087467 W CN2019087467 W CN 2019087467W WO 2019228200 A1 WO2019228200 A1 WO 2019228200A1
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WO
WIPO (PCT)
Prior art keywords
welding
connection portion
protective layer
polymer protective
pole
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Application number
PCT/CN2019/087467
Other languages
English (en)
French (fr)
Inventor
袁万颂
潘仪
梁桂海
唐富兰
Original Assignee
比亚迪股份有限公司
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
Application filed by 比亚迪股份有限公司 filed Critical 比亚迪股份有限公司
Priority to KR1020207037736A priority Critical patent/KR20210016425A/ko
Priority to US17/059,459 priority patent/US20210210823A1/en
Priority to JP2020566606A priority patent/JP2021525943A/ja
Priority to EP19811732.7A priority patent/EP3806195A4/en
Publication of WO2019228200A1 publication Critical patent/WO2019228200A1/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
    • 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
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/586—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries inside the batteries, e.g. incorrect connections of 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
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • 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
    • H01M50/534—Electrode connections inside a battery casing characterised by the material 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
    • H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
    • 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
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/59—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries characterised by the protection means
    • 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 disclosure relates to the field of lithium ion secondary batteries, and relates to a lithium ion secondary battery component, a method for preparing the same, and a lithium ion secondary battery.
  • the electrode core current collector foil needs to be welded to the connector that provides the external connection of the battery.
  • This process is more complicated in power batteries, and there will be multiple welding processes, such as the current collector foil ears.
  • these processes mostly adopt ultrasonic welding or laser welding, etc.
  • some welding slags, burrs and other defects that cause hidden dangers to battery safety are generated.
  • an insulation tape or a high-temperature-resistant insulation tape is affixed to these high-risk areas after dust removal to solve the above problems.
  • the adhesive tape has poor resistance to electrolyte soaking, because the presence of welds causes unevenness on the metal surface, the adhesive tape cannot adhere closely to the metal surface, and the electrolyte easily penetrates into the inside of the tape, destroying the tape and the metal surface. Adhesion caused the tape to fall off; when high-risk areas such as welded joints are exposed, the above-mentioned structures such as welding slag and burrs will endanger the safety performance of the battery.
  • the second is that some larger or sharper welding slag or burr structures can pierce the tape, causing the protective measures of the tape to fail.
  • An object of the present disclosure is to provide a lithium-ion secondary battery assembly that can prevent defects such as welding slag and burrs from being exposed and ensure battery safety.
  • a first aspect of the present disclosure provides a lithium ion secondary battery assembly including a pole piece and a pole post, and a pole ear protruding from the pole piece; between the pole ear and the pole pole It has a welded connection formed by welding; the welded connection has convex welding defects; the surface of the welded connection is covered with a polymer protective layer, and the thickness of the polymer protective layer is greater than or equal to the protrusion Thickness of the welding defect, the raised welding defect is embedded in the polymer protective layer.
  • the raised welding defect is in full contact with the polymer protective layer.
  • the polymer protective layer is a polymer protective layer formed by dispensing or applying glue on the surface of the soldered connection portion.
  • the welding connection portion includes a first welding connection portion; a first welding connection portion formed by welding the pole post to the pole ear, or a lead-out piece protruding from the pole post and the pole ear
  • the assembly further includes a connection piece, and the welding connection portion includes a second welding connection portion and a third welding connection portion; one end of the connection piece is welded to the tab to form the second welding connection portion. ; The other end of the connecting piece is welded to the pole to form the third welding connection portion, or the other end of the connecting piece is welded to the lead piece protruding from the pole to form a third welding connection portion;
  • the third welding connection portion includes a connection piece side of the third welding connection portion; the polymer protective layer covers at least both sides of the second welding connection portion and the connection piece side of the third welding connection portion. on the surface.
  • the ratio of the thickness of the raised welding defect to the thickness of the polymer protective layer is (0.1-0.9): 1.
  • the welded connection portion further has a welded seam
  • the polymer protective layer has a filling protrusion extending into the welded seam
  • the assembly further includes an insulating layer covering the polymer protective layer.
  • the insulating layer is at least one of a polypropylene insulating layer, a polyethylene insulating layer, and a polyvinyl chloride insulating layer.
  • the molding shrinkage of the polymer in the polymer protective layer is 1 to 4%.
  • the polymer protective layer is at least one of a hot-melt adhesive polymer protective layer, a photo-curable adhesive polymer protective layer, and a pressure-sensitive adhesive polymer protective layer.
  • the hot melt adhesive is selected from the group consisting of random polypropylene hot melt adhesives, copolymers of ethylene and / or propylene and oxygen-containing olefins, polystyrene, copolymers of styrene and butadiene, isoprene At least one of an olefin and butadiene copolymer, an epoxy-modified styrene-butadiene-styrene copolymer, and a dimer acid polyamide hot-melt adhesive;
  • the photo-curing adhesive is an ultraviolet-curing adhesive
  • the UV curing adhesive is selected from the group consisting of acrylic UV curing adhesive, alicyclic epoxy curing UV adhesive, aliphatic epoxy curing UV adhesive, and aromatic epoxy curing UV.
  • Glue bisphenol A epoxy-modified acrylate ultraviolet curing adhesive, and phenolic epoxy-modified acrylate ultraviolet curing adhesive; at least one selected from the group consisting of cross-linked acrylate pressure-sensitive adhesives At least one of a sensitive adhesive, a silicone-based pressure-sensitive adhesive, a polyurethane-based pressure-sensitive adhesive, and a rubber-based pressure-sensitive adhesive.
  • a second aspect of the present disclosure provides a method for preparing a lithium-ion secondary battery assembly, the assembly including a pole piece and a pole post, the pole piece protruding with a pole ear, and the pole pole protruding with a lead-out piece, the method comprises the following steps: S1, welding the pole ear to the pole post to form a welding connection portion, the welding connection portion has a convex welding defect S2, and applying a polymer to the surface of the welding connection portion to form Forming a polymer protective layer and embedding the convex welding defect in the polymer protective layer, the application amount of the polymer is such that the thickness of the polymer protective layer is greater than or equal to that of the convex welding The thickness of the defect.
  • the method of forming the polymer protective layer is dispensing or gluing.
  • the welding connection portion includes a first welding connection portion; a method of forming the first welding connection portion includes: welding the pole tab to the pole post to form the first welding connection portion, Or welding the pole lug to the lead piece protruding from the pole post to form the first welding connection part; the first welding connection part includes a pole lug side of the first welding connection part, and the first welding A polymer is applied on the tab-side surface of the connection portion to form the polymer protective layer.
  • the assembly further includes a connection piece, the welding connection portion includes a second welding connection portion and a third welding connection portion; a method of forming the second welding connection portion and the third welding connection portion includes: Welding one end of the connection piece to the pole tab to form the second welding connection portion; welding the other end of the connection piece to the pole post to form the third welding connection portion, or The other end of the connecting piece is welded to the lead piece protruding from the pole to form the third welding connecting portion; the third welding connecting portion includes a connecting piece side of the third welding connecting portion; and the second welding Polymer is applied to both surfaces of the connection portion and to the connection piece side surface of the third soldered connection portion to form the polymer protective layer, respectively.
  • step S2 includes at least one of the following methods: method a: apply a hot-melt adhesive to be cured on the surface of the welding connection portion, and cure to form the polymer protective layer; method b : Coating a surface of the soldered connection portion with a light-curing adhesive to be cured, and curing under a light condition to form the polymer protective layer; and mode c: making the pressure-sensitive adhesive cover the welding under a pressure state The surface of the connection part is then removed from the pressure to form the polymer protective layer.
  • method a apply a hot-melt adhesive to be cured on the surface of the welding connection portion, and cure to form the polymer protective layer
  • method b Coating a surface of the soldered connection portion with a light-curing adhesive to be cured, and curing under a light condition to form the polymer protective layer
  • mode c making the pressure-sensitive adhesive cover the welding under a pressure state The surface of the connection part is then removed from the pressure to form the polymer protective layer.
  • the temperature of the hot-melt adhesive in the molten state is 100-180 ° C
  • the viscosity is 1000-10000CP
  • the curing temperature is 20-25 ° C
  • the curing time is 0-30s
  • the viscosity is 1000-5000CP
  • the light exposure time is 5-20s
  • the pressure is 0.2-0.8MPa.
  • the method further includes: covering the polymer protective layer with an insulating material and forming an insulating layer.
  • a third aspect of the present disclosure provides a lithium ion secondary battery including a cover plate and the lithium ion secondary battery component of the first aspect of the present disclosure or a lithium ion secondary battery obtained by using the method described in the second aspect of the present disclosure. Components.
  • the lithium ion secondary battery assembly of the present disclosure can embed a polymer protective layer on the surface of the welding connection portion between the tab and the lead-out piece, so that the welding connection portion having convex welding defects can be embedded and can be embedded in the polymerization.
  • the welding defects are fixed and the surface of the welding connection is flat without protrusions, which effectively solves the problem that the protruding of the welding defects punctures the separator and reduces the safety performance of the battery; at the same time, the polymer protective layer is resistant to electrolyte soaking, The resistance to electrochemical oxidation-reduction improves the durability and stability of components and batteries.
  • FIG. 1 is a schematic cross-sectional view of a welding connection portion of a lithium ion secondary battery according to a specific embodiment of the present disclosure.
  • FIG. 2 is a schematic structural diagram of a specific embodiment of a lithium ion secondary battery of the present disclosure.
  • FIG. 3 is a side view (ie, a left side view of FIG. 2) of a specific embodiment of the lithium ion secondary battery of the present disclosure.
  • FIG. 4 is a schematic structural diagram of another embodiment of a lithium ion secondary battery of the present disclosure.
  • FIG. 5 is a side view (ie, a left side view of FIG. 4) of another embodiment of the lithium ion secondary battery of the present disclosure.
  • FIG. 6 is a cross-sectional photograph of an embodiment of a lithium ion secondary battery module according to the present disclosure before the electrolyte is soaked.
  • FIG. 7 is a cross-sectional photograph of an embodiment of the lithium ion secondary battery module of the present disclosure after the electrolyte is soaked.
  • FIG. 8 is a cross-sectional photograph before the electrolyte is soaked in another embodiment of the lithium ion secondary battery module of the present disclosure.
  • FIG. 9 is a cross-sectional photograph of a lithium ion secondary battery module according to another embodiment of the present disclosure after being soaked in an electrolytic solution.
  • a first aspect of the present disclosure provides a lithium ion secondary battery assembly.
  • the assembly includes a pole piece 7 and a pole post 3.
  • the pole piece 7 has a tab 6 protruding therefrom;
  • the lithium ion secondary battery assembly of the present disclosure can embed a polymer protection layer on the surface of the welding connection portion between the tab and the lead-out piece, so that the welding connection portion can have embedded welding defects and be embedded in the polymer protection layer. Therefore, the welding defects are fixed and the surface of the welding connection part is flat without protrusions, which effectively solves the problem that the protruding of the welding defects punctures the separator and reduces the safety performance of the battery; at the same time, the polymer protective layer is resistant to electrolyte immersion and electrochemical oxidation- Reduced characteristics, improve the durability and stability of components and batteries.
  • the polymer protective layer may partially or completely cover the soldered connection portion, preferably covering the entire surface of the soldered connection portion to improve the stability of the soldered portion.
  • the welded connection portion may include a first welded connection portion, and the first welded connection portion may be a first formed by welding the pole 3 and the pole ear 6.
  • the surface on the tab side of the first welding connection portion refers to the main surface on the side of the first welding connection portion that is relatively close to the tab.
  • the assembly may further include a connection piece 5, and the welding connection portion may include a second welding connection portion and a third welding connection portion;
  • the connecting piece 5 may be welded to the pole 6 to form a second welding connection portion;
  • the other end of the connecting piece 5 may be welded to the pole 3 to form a third welding connection portion, or the other end of the connecting piece 5 may be connected to the pole
  • the lead-out piece 4 protruding from the column is welded to form a third welding connection portion;
  • the third welding connection portion may include the connection piece side of the third welding connection portion, and the polymer protective layer may cover at least the two surfaces of the second welding connection portion And the third solder connection portion on the surface of the connection piece side.
  • the surface on the connection piece side of the third welding connection portion refers to the main surface on the side of the third welding connection portion that is relatively close to the connection piece.
  • the ratio of the thickness of the raised welding defect to the thickness of the polymer protective layer may be (0.1 to 0.9): 1, for example, 0.1: 1, 0.2: 1, 0.3: 1, 0.4: 1, 0.5: 1, 0.6: 1, 0.7: 1, 0.8: 1, 0.9: 1, and preferably (0.3 to 0.6): 1.
  • the thickness of the polymer protective layer refers to the maximum thickness of the surface of the polymer protective layer relative to the contact surface between the polymer protective layer and the welding connection portion, and the thickness of the raised welding defect means that the raised welding defect is in the polymer.
  • the maximum height in the thickness direction of the protective layer can further ensure that all protruding welding defects of the welding connection portion during the use of the module do not puncture the polymer protective layer, which is effective for the pole piece assembly
  • the protective effect reduces the risk of short circuit caused by welding slag and burr piercing the separator, improves the safety of the battery, and can quickly form a protective layer to prevent the protective layer from being too thick and affecting the assembly and performance of the pole piece assembly.
  • the meaning of the raised welding defect is well known to those skilled in the art, for example, the raised welding defect may include burrs and / or slag protruding from the surface of the tab and the lead piece before welding.
  • the maximum height of the burr and the welding slag can be 50-800 ⁇ m, for example, 50 ⁇ m, 75 ⁇ m, 100 ⁇ m, 125 ⁇ m, 150 ⁇ m, 175 ⁇ m, 200 ⁇ m, 225 ⁇ m, 250 ⁇ m, 275 ⁇ m, 300 ⁇ m, 325 ⁇ m, 350 ⁇ m, 375 ⁇ m, 400 ⁇ m, 425 ⁇ m, 450 ⁇ m , 475 ⁇ m, 500 ⁇ m, 525 ⁇ m, 550 ⁇ m, 575 ⁇ m, 600 ⁇ m, 625 ⁇ m, 650 ⁇ m, 675 ⁇ m, 700 ⁇ m, 725 ⁇ m, 750 ⁇ m, 775 ⁇
  • the welded connection portion may further have a welded seam
  • the polymer protective layer may have a filling protrusion extending into the welded seam to further fully conform the polymer protective layer to the welded connection portion and improve the protection layer and the welded connection portion. Cohesion of the surface.
  • the meaning of the welding seam is well known to those skilled in the art, that is, at least one of depressions and grooves and gaps formed after welding and lower than the original surface of the welding connection portion.
  • the depth of the weld can be 0-500 microns, for example, 0 microns, 30 microns, 50 microns, 75 microns, 100 microns, 130 microns, 150 microns, 175 microns, 200 microns, 230 microns, 250 microns, 275 micrometers, 300 micrometers, 330 micrometers, 350 micrometers, 375 micrometers, 400 micrometers, 430 micrometers, 450 micrometers, 475 micrometers, and 500 micrometers, more preferably 30-300 micrometers, and even more preferably 30-150 micrometers.
  • the polymer protective layer may also cover at least one of at least part of the tabs and at least part of the lead-out piece; or, polymerize
  • the physical protection layer may also cover at least one of at least part of the tabs, at least part of the lead-out sheet, and at least part of the connecting sheet.
  • the polymer protection The layer may be a polymer protective layer formed by dispensing or gluing on the surface of the welded connection portion.
  • the dispensing method and the coating method can ensure that the polymer material fully contacts and adheres to the surface of the welded connection portion and the surface of the convex welding defect when the polymer material has a certain fluidity, and maintains the adhered
  • the polymer protective layer is formed in a state of being formed, and the polymer protective layer thus obtained can fully contact the surface of the welding connection portion, achieve maximum contact, and adhere to the surface of the raised welding defect, thereby improving the polymer protective layer to the welding connection. Protection effect.
  • the raised welding defect Full contact with the polymer protective layer where full contact means that the raised welding defects of the welded connection are embedded in the polymer protective layer and observed under a metallographic microscope.
  • all surfaces of the raised welding defects are completely Laminated with polymer, there is no gap between the surface of the welding defect and the polymer; it should be noted that under certain unavoidable process conditions, the surface of the raised welding defect may also be protected by the polymer
  • the molding shrinkage of the polymer of the polymer protective layer may be 1 to 4%, such as 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9% , 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, more preferably 1 to 3% to avoid excessive polymer after molding Shrinkage causes an excessive gap between the polymer protective layer and the surface of the welded joint.
  • molding shrinkage is well known to those skilled in the art, that is, the size of the material before molding (for example, when the hot-melt adhesive is in a heated state and when the light-curing adhesive is not exposed to light) and after the molding (for example, the hot-melt adhesive is curing) After curing at temperature, the photocurable glue is cured after light curing) to form the percentage of the difference in the dimensions of the article.
  • the test method of molding shrinkage can be performed with reference to the standard GB / T15585-1995 thermoplastic injection molding shrinkage measurement.
  • the polymer of the polymer protective layer may be conventional in the art, and is preferably a polymer material capable of resisting electrolytic solution soaking and resisting electrochemical oxidation-reduction. Further, in order to improve the adhesion of the polymer protective layer to the surface of the welding connection portion, the polymer of the polymer protective layer may preferably be a polymer material that can have fluidity in a certain state and can be cured after removal of conditions.
  • the polymer protective layer may be a hot melt adhesive polymer
  • At least one of the protective layer, the photo-curable adhesive polymer protective layer, and the pressure-sensitive adhesive polymer protective layer may be a pressure-sensitive adhesive polymer protective layer that is convenient to apply.
  • the assembly of the present disclosure further includes a connecting sheet, two ends of the connecting sheet are respectively provided with a polymer protective layer, and the polymers of the two polymer protective layers may be the same or different, and preferably the same.
  • hot-melt adhesives are well known to those skilled in the art, that is, materials whose physical state, such as fluidity, changes and changes with temperature within a certain temperature range, and the types of hot-melt adhesives can be conventional in the art.
  • Preferred is selected from the group consisting of randomly copolymerized polypropylene hot melt adhesives, copolymers of ethylene and / or propylene and oxygen-containing olefins, polystyrene, copolymers of styrene and butadiene, copolymers of isoprene and butadiene 2.
  • At least one of epoxy-modified styrene-butadiene-styrene copolymer and dimer acid polyamide hot melt adhesive At least one of epoxy-modified styrene-butadiene-styrene copolymer and dimer acid polyamide hot melt adhesive.
  • the above-mentioned preferred types of hot-melt adhesives have suitable melting temperatures and viscosities, and the melting temperature will not affect the performance of the pole pieces; good curing performance and resistance to electrolyte immersion, which can fully contact the surface of the bonded welding connection under appropriate fluidity conditions,
  • the formed protective layer has good adhesion to the surface of the soldered connection portion and is convenient for coating operation.
  • the application method of the hot melt adhesive may be conventional in the art, such as dispensing or gluing.
  • the meaning of light-curing glue is well known to those skilled in the art, that is, materials that can be cured under light conditions, and the light-curing glue can adopt conventional types in the art, such as ultraviolet light-curing glue and / or visible light-curing glue.
  • the photo-curing adhesive is an ultraviolet-curing adhesive to increase the curing speed.
  • the ultraviolet curing adhesive may be selected from conventional types in the art, and the preferred ultraviolet curing adhesive of the present disclosure may be selected from the group consisting of acrylic ultraviolet curing adhesive, alicyclic epoxy curing ultraviolet adhesive, and aliphatic epoxy resin.
  • At least one of a UV-based curing adhesive At least one of a UV-based curing adhesive, an aromatic epoxy-based UV curing adhesive, a bisphenol A epoxy-modified acrylate UV-curing adhesive, and a phenolic epoxy-modified acrylate UV-curing adhesive.
  • the above-mentioned preferred types of UV-curable adhesives have fast curing speed, good electrolyte resistance, and suitable viscosity and fluidity in a molten state, which is conducive to bonding the surface of the welding connection portion and improving the adhesion of the protective layer.
  • pressure-sensitive adhesives can be well known to those skilled in the art, that is, pressure-sensitive adhesives.
  • pressure-sensitive adhesives have a certain fluidity under pressure, for example, they can be selected from rubbers.
  • the pressure-sensitive adhesive may be selected from the group consisting of cross-linked acrylic pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, polyurethane-based pressure-sensitive adhesives, and rubber-based pressure-sensitive adhesives. At least one.
  • the above-mentioned preferred types of pressure-sensitive adhesives have strong adhesion, are easy to use, and have good resistance to electrolytes and electrochemical properties.
  • the component may further include an insulating layer, which may cover the polymer protective layer and in some embodiments, the tabs, lead-out pieces, and connecting pieces. At least one of.
  • the insulation layer may contain conventional insulation materials in the art.
  • the insulation layer may be at least one of a polypropylene insulation layer, a polyethylene insulation layer, and a polyvinyl chloride insulation layer.
  • the thickness of the insulation layer may be 30 to 300 ⁇ m, for example 30 ⁇ m, 40 ⁇ m, 50 ⁇ m, 60 ⁇ m, 70 ⁇ m, 80 ⁇ m, 90 ⁇ m, 100 ⁇ m, 110 ⁇ m, 120 ⁇ m, 130 ⁇ m, 140 ⁇ m, 150 ⁇ m, 160 ⁇ m, 170 ⁇ m, 180 ⁇ m, 190 ⁇ m, 200 ⁇ m, 210 ⁇ m, 220 ⁇ m, 230 ⁇ m, 240 ⁇ m, 250 ⁇ m, 260 ⁇ m, 270 ⁇ m 280 ⁇ m, 290 ⁇ m, and 300 ⁇ m, and preferably 30 to 100 ⁇ m.
  • the method of applying the insulating layer to the polymer protective layer may also be conventional in the art, for example, by a method of bonding or sheathing.
  • the assembly of the present disclosure further includes a connecting piece
  • the two soldered connection portions at both ends of the connecting piece are preferably provided with an insulating layer respectively to further strengthen the protection of high-risk areas and better prevent raised welding defects. Bring inferior quality problems, improve battery safety performance.
  • a second aspect of the present disclosure provides a method for preparing the above-mentioned lithium ion secondary battery assembly.
  • the assembly includes a pole piece and a pole post, with pole ears protruding from the pole piece, and lead-out pieces protruding from the pole pole.
  • the method includes the following steps. :
  • the method of the present disclosure by providing a polymer protective layer on the surface of the welding connection portion between the tab and the lead-out piece, it is possible to embed the welding defect having the convex portion in the welding portion and embed it in the polymer protective layer, thereby fixing the welding defect.
  • the position does not cause displacement, and the surface of the welded part is flat without protrusions, which effectively solves the problem that the safety performance of the battery is reduced due to the protruding of the welding defect and piercing the separator; at the same time, the polymer protective layer is resistant to electrolyte immersion and electrochemical oxidation- Reduced characteristics, improve the durability and stability of components and batteries.
  • the method may include partially or completely covering the welding connection portion with the polymer protective layer, and preferably covering the entire surface of the welding connection portion with the polymer protective layer to improve the stability of the welding portion.
  • a polymer is formed.
  • the method of protecting the layer may be by dispensing or gluing the surface of the soldered connection portion.
  • the dispensing method and the coating method can ensure that the polymer material fully contacts and adheres to the surface of the welding connection portion and the surface of the convex welding defect when the polymer material has a certain fluidity, and maintains the adhered
  • the polymer protective layer is formed in a state of being formed, and the polymer protective layer thus obtained can fully contact the surface of the welding connection portion, achieve maximum contact, and adhere to the surface of the raised welding defect, thereby improving the polymer protective layer to the welding connection. Protection effect.
  • the welded connection portion may include a first welded connection portion, and a method of forming the first welded connection portion may include: welding a pole ear to a pole post to form the first welding connection portion, or The tabs are welded to form a first welding connection portion on the lead-out piece protruding from the pole; the first welding connection portion may include a tab side of the first welding connection portion, and a polymer is applied on a surface of the tab side of the first welding connection portion A polymer protective layer is formed by molding.
  • the assembly may further include a connecting piece, and the pole and the tab may be welded together through the connecting piece.
  • the welding connection portion may include a second welding connection portion and a third welding connection portion.
  • the method of forming the second welding connection portion and the third welding connection portion may include: welding one end of the connection piece to the pole tab to form a second welding connection portion; and welding the other end of the connection piece to the pole post to form The third welding connection portion, or the other end of the connection piece is welded to the lead piece protruding from the pole to form a third welding connection portion; the third welding connection portion includes the connection piece side of the third welding connection portion; and the second welding connection Polymers are applied on both the side surfaces of the parts and on the side surfaces of the tabs of the third soldered connection part to form polymer protective layers, respectively.
  • the ratio of the thickness of the raised welding defect to the thickness of the polymer protective layer may be (0.1 to 0.9): 1, for example, 0.1: 1, 0.2: 1, 0.3: 1, 0.4: 1, 0.5: 1, 0.6: 1, 0.7: 1, 0.8: 1, 0.9: 1, and preferably (0.3 to 0.6): 1.
  • the thickness of the polymer protective layer refers to the maximum thickness of the surface of the polymer protective layer relative to the original surface of the welded connection portion. Within a preferred thickness range, all protrusions of the welded connection portion during the use of the component can be further guaranteed.
  • the welding defect does not pierce the polymer protective layer, which effectively protects the pole piece assembly, reduces the risk of short circuit caused by welding slag and burrs piercing the separator, improves the safety of the battery, and can quickly form a protective layer to avoid Excessive protective layer affects the assembly and performance of the pole piece assembly.
  • raised welding defects may include burrs and / or welding slag protruding from the original surfaces of the tabs and the tabs, where the tabs And the original surface of the lead-out sheet refers to the surface before both are welded.
  • the welded connection portion may further have a welded seam
  • the applied polymer may be allowed to enter the welded seam to form a filling protrusion to further make the polymer protective layer fully fit the welded connection portion and improve the protective layer.
  • the meaning of the welding seam is well known to those skilled in the art, that is, at least one of depressions, grooves and gaps formed after welding and lower than the original surface of the welding connection.
  • the surface of the soldered connection portion may be treated before applying a polymer to improve the binding force of the polymer protective layer.
  • the method of performing the surface treatment may include conventional methods in the art, for example, the surface treatment may include a surface etching treatment. Among them, the surface etching treatment may be preferably one or more of electrochemical etching, acid-base etching or oxidizing agent etching, so as to improve the binding force between the metal and the organic polymer.
  • the present invention may further include pretreatment of the surface of the welded connection. The pretreatment is various treatments known to those skilled in the art, and generally includes grinding and cleaning the surface.
  • the molding shrinkage of the polymer of the polymer protective layer may be 1 to 4%, for example, 1%, 1.1%, 1.2 %, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, more preferably 1 to 3% to avoid polymerization after molding Excessive shrinkage of the material causes an excessive gap between the polymer protective layer and the surface of the welded connection.
  • the meaning and test method of molding shrinkage are as above.
  • the polymer of the polymer protective layer may be conventional in the art, and is preferably a polymer material capable of resisting electrolytic solution soaking and resisting electrochemical oxidation-reduction.
  • the polymer of the polymer protective layer may preferably be a material that can have fluidity in a certain state and can be cured after removal of conditions, so as to make The protective layer is sufficiently filled or fitted with welding defects, and is sufficiently in contact with the surface of the soldered connection portion to improve the adhesion.
  • the polymer protective layer may be a hot-melt adhesive polymer protective layer, photocuring At least one of the adhesive polymer protective layer and the pressure-sensitive adhesive polymer protective layer is further preferably a pressure-sensitive adhesive polymer protective layer which is convenient to apply.
  • the assembly of the present disclosure further includes a connecting sheet, two ends of the connecting sheet are respectively provided with a polymer protective layer, and the two polymer protective layers may be the same or different, and preferably the same.
  • hot melt adhesive is well known to those skilled in the art, that is, a material whose physical state, such as fluidity, changes and changes with temperature in a certain temperature range
  • the coating method of the hot melt adhesive may be conventional in the art.
  • Such as injection molding, hot pressing, spraying or coating Such as injection molding, hot pressing, spraying or coating.
  • the meaning of light-curing glue is well known to those skilled in the art, that is, materials that can be cured under light conditions, and the coating method of light-curing glue can be conventional in the art, such as injection molding, hot pressing, spraying or coating.
  • the meaning and type of pressure-sensitive adhesive can be well known to those skilled in the art, that is, pressure-sensitive adhesives, usually pressure-sensitive adhesives have a certain fluidity under pressure.
  • step S2 may include at least one of the following methods:
  • Method a apply the hot-melt adhesive to be cured on the surface of the welding connection portion, and cure to form a polymer protective layer;
  • Method b coating the surface of the welding connection portion with a light-curing adhesive to be cured, and curing under a light condition to form a polymer protective layer;
  • Method c The pressure-sensitive adhesive is applied to cover the surface of the welding connection part under a pressure state, and then the pressure is removed to form a polymer protective layer.
  • the conditions for applying the hot-melt adhesive in a molten state can be changed within a wide range.
  • the temperature of the hot-melt adhesive in a molten state can be 100 to 180 ° C, such as 100 ° C, 110 ° C, 120 ° C, 130 ° C, 140 ° C, 150 ° C, 160 ° C, 170 ° C, 180 ° C, preferably 110-150 ° C
  • the viscosity can be 1000-10000CP, such as 1000CP, 1500CP, 2000CP, 2500CP, 3000CP, 3500CP, 4000CP, 4500CP, 5000CP, 5500CP, 6000CP, 6500CP, 7000CP, 7500CP, 8000CP, 8500CP, 9000CP, 9500CP, and 10000CP, preferably 1500 to 5000CP.
  • the curing temperature can be 20 to 25 ° C, such as 20 ° C, 21 ° C, 22 ° C, At 23 ° C, 24 ° C, and 25 ° C, the curing time can be 0-30s, such as 1s, 5s, 10s, 15s, 17s, 20s, 22s, 25s, 30s, and preferably 15-25s.
  • the type of hot-melt adhesive may be conventional in the art. Further, in order to satisfy the above-mentioned conditions for melt coating, the hot-melt adhesive may be preferably selected from random polypropylene hot-melt adhesives, ethylene and / or propylene and Copolymers of oxyolefins, polystyrene, copolymers of styrene and butadiene, copolymers of isoprene and butadiene, epoxy-modified styrene-butadiene-styrene copolymers, and dimerization At least one of acid type polyamide hot melt adhesives.
  • the above-mentioned preferred types of hot-melt adhesives have suitable melting temperatures and viscosities, and the melting temperature will not affect the performance of the pole pieces; good curing performance and resistance to electrolyte immersion, which can fully contact the surface of the bonded welding connection under appropriate fluidity conditions,
  • the formed protective layer has good adhesion to the surface of the soldered connection portion and is convenient for coating operation.
  • the wavelength and intensity of the light can be selected according to the type of the light-curing glue, which is well known to those skilled in the art, and is not repeated here.
  • the viscosity of the light-curing glue can be 1000-5000CP, such as 1000CP, 1500CP , 2000CP, 2500CP, 3000CP, 3500CP, 4000CP, 4500CP, 5000CP, preferably 1000-3000CP;
  • the time of light can be 5-20s, such as 5s, 10s, 11s, 12s, 13s, 14s , 15s, 17s, 20s, preferably 10-15s.
  • the light-curing adhesive may be of a conventional type in the art, such as an ultraviolet-curing adhesive and / or a visible-light curing adhesive.
  • the light-curing adhesive is preferably an ultraviolet-curing adhesive to improve Curing speed.
  • the ultraviolet curing adhesive may be selected from conventional types in the art, and the preferred ultraviolet curing adhesive of the present disclosure may be selected from the group consisting of acrylic ultraviolet curing adhesive, alicyclic epoxy curing ultraviolet adhesive, and aliphatic epoxy resin.
  • At least one of a UV-based curing adhesive At least one of a UV-based curing adhesive, an aromatic epoxy-based UV curing adhesive, a bisphenol A epoxy-modified acrylate UV-curing adhesive, and a phenolic epoxy-modified acrylate UV-curing adhesive.
  • the above-mentioned preferred types of UV-curable adhesives have fast curing speed, good electrolyte resistance, and suitable viscosity and fluidity in a molten state, which is conducive to bonding the surface of the welding connection portion and improving the adhesion of the protective layer.
  • the applied pressure may be 0.2 to 0.8 MPa, for example, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, preferably 0.4 to 0.6MPa.
  • the pressure-sensitive adhesive due to the pressure during the use of the pressure-sensitive adhesive, it can generate a certain pressure on the larger or higher welding slag, reduce its height, and effectively avoid the occurrence of extremely large welding slag; meanwhile, the pressure-sensitive adhesive is compacted and After the pressure is removed, the polymer protective layer takes effect immediately. No heating device or light source is required during the process, which is more conducive to improving production efficiency.
  • the pressure-sensitive adhesive may be selected from a rubber-based pressure-sensitive adhesive and a resin-based pressure-sensitive adhesive.
  • the pressure-sensitive adhesive may be selected from a cross-linked acrylate pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, and a polyurethane. At least one of a pressure-sensitive adhesive based on rubber and a pressure-sensitive adhesive based on rubber.
  • the above-mentioned preferred types of pressure-sensitive adhesives are strong, easy to use, and have good resistance to electrolytes and electrochemical properties.
  • the pressure-sensitive adhesive may be rubber Pressure-sensitive adhesive, wherein the rubber-based pressure-sensitive adhesive is preferably a modified nitrile rubber; further, the weight content of the acrylonitrile structural unit in the modified nitrile rubber may be 25% to 50%, such as 25%, 27%, 30%, 32%, 35%, 37%, 40%, 43%, 45%, 47%, 50%, molecular weight can be 100,000 to 300,000 (weight average molecular weight), such as 100,000, 120,000, 140,000, 160,000, 180,000, 200,000, 220,000, 240,000, 260,000, 280,000, 300,000, to improve the strength and adhesion of pressure-sensitive adhesives.
  • the method may include: covering the polymer protective layer with an insulating material and forming an insulating layer.
  • the insulating material may be conventional in the art, preferably at least one of insulating polypropylene, polyethylene, and polyvinyl chloride; the method of applying the insulating layer to the polymer protective layer may also be conventional in the art, such as by bonding Or set method.
  • the method may include providing two insulating connection layers at both ends of the connecting piece, respectively, to increase the protection of high-risk areas and further improve the safety performance of the battery.
  • a third aspect of the present disclosure provides a lithium ion secondary battery including the lithium ion secondary battery component of the first aspect of the present disclosure or a lithium ion secondary battery component obtained by the method of the second aspect of the present disclosure, and a cover plate.
  • the lithium ion secondary battery of the present disclosure effectively protects the high-risk areas of structures such as welding slag and burrs existing at the welding connection site, which can reduce the risk of battery short circuit caused by welding slag and burrs piercing the separator, and improve battery safety. Sex.
  • an electrode post in a component of a lithium ion secondary battery may be provided on a cover plate for connection with an external circuit, and the lead-out sheet may be connected to the electrode post and extend to the inside of the cover plate so as to be connected with the electrode ear or the electrode.
  • the lugs of the ear connection are soldered.
  • a lithium ion secondary battery may include a positive electrode component and a negative electrode component, preferably the positive electrode component and the negative electrode component are components of the present disclosure, respectively, to further improve the safety and stability of the battery.
  • the disclosure is further described below through examples, but the disclosure is not limited in any way.
  • the shear strength is tested using the GB / T 7124-2008 adhesive tensile shear strength measurement method, and the cross-sectional morphology of the polymer protective layer is tested using a metallographic microscope.
  • the polymer protection The thickness of the layer was also measured using a metallographic microscope.
  • This embodiment is used to describe the lithium ion secondary battery assembly and the method for manufacturing the same.
  • the assembly includes pole pieces 7, pole posts 3, and connecting pieces 5 which are electrically connected.
  • the pole pieces 7 have protruding ears 6, and the pole pieces 3 have lead-out pieces 4.
  • the connecting pieces The two ends of 5 are respectively welded with the tab 6 and the lead-out piece 4 to form two welded joints, and a high molecular weight butyl rubber pressure-sensitive adhesive (purchased from ITW company, product number is sm5190) is covered by welding under a pressure of 0.6 MPa. After the pressure is removed from the surface of the connection part, a polymer protective layer 1 is formed.
  • the ratio of the maximum height of the raised welding defect 2 to the thickness of the polymer protective layer 1 is 0.5: 1.
  • the component was sealed after being immersed in the electrolyte at a high temperature (80 ° C) for 180 days, and the cross-sectional morphology of the welded connection and the polymer protective layer before and after the immersion were observed.
  • the results are shown in Figures 6 and 7, respectively.
  • the shear strength is shown in Table 1.
  • This embodiment is used to describe the lithium ion secondary battery assembly and the method for manufacturing the same.
  • Example 1 The method of Example 1 is adopted, except that the insulating polypropylene layer is adhered to the polymer protective layer 1 to form the insulating layer 9.
  • the component was sealed after being immersed in the electrolyte at a high temperature (80 ° C) for 180 days, and the cross-sectional morphology of the welded connection and the polymer protective layer before and after the immersion were observed.
  • the results are shown in Figs. 8 and 9, respectively.
  • the shear strength is shown in Table 1.
  • This embodiment is used to describe the lithium ion secondary battery assembly and the method for manufacturing the same.
  • the component includes an electrically connected pole piece, a pole post, and a connecting piece.
  • the pole piece protrudes from a pole ear, and the pole post has a lead-out piece. Both ends of the connecting piece are respectively welded with the pole ear and the lead-out piece to form two welded connections.
  • the hot-melt adhesive (purchased from Australia-China Company, product number B03) is melted (melt viscosity is 2500CP) at 160 ° C, and then coated on the surface of the welded joint. After curing at room temperature for 15s, a polymer protective layer is formed. The thickness is 300 ⁇ m.
  • the assembly was sealed and immersed in an electrolyte at a high temperature (80 ° C.) for 180 days, and the shear strength of the polymer protective layer before and after immersion was tested.
  • the results are shown in Table 1.
  • This embodiment is used to describe the lithium ion secondary battery assembly and the method for manufacturing the same.
  • the component includes an electrically connected pole piece, a pole post, and a connecting piece.
  • the pole piece protrudes from a pole ear
  • the pole post has a lead-out piece. Both ends of the connecting piece are respectively welded with the pole ear and the lead-out piece to form two welded connections.
  • UV-curable adhesive purchased from Debon Company, product number 703, viscosity 2000CP
  • a polymer protective layer was formed with a thickness of 250 ⁇ m.
  • the assembly was sealed and immersed in an electrolyte at a high temperature (80 ° C.) for 180 days, and the shear strength of the polymer protective layer before and after immersion was tested.
  • the results are shown in Table 1.
  • This embodiment is used to explain the lithium ion secondary battery pole piece assembly and the manufacturing method thereof.
  • Example 4 The method of Example 4 is adopted, except that an insulating polypropylene is adhered to the polymer protective layer to form an insulating layer.
  • Example 1 The method and material of Example 1 were used, except that the ratio of the maximum height of the welding defect to the thickness of the pressure-sensitive adhesive layer was 0.3: 1.
  • the pole piece assembly was sealed and immersed in an electrolyte at a high temperature (80 ° C.) for 180 days, and the shear strength of the polymer protective layer before and after immersion was tested. The results are shown in Table 1.
  • Embodiment 1 As shown in FIG. 4 and FIG. 5, the method and material of Embodiment 1 are adopted. The difference is that the component does not include a connecting piece, a pole piece 6 extends from the pole piece 7, and a lead-out piece 4 extends from the pole post 3. , The tab 6 and the lead-out piece 4 are welded to form a welded connection portion.
  • the assembly was sealed and immersed in an electrolyte at a high temperature (80 ° C.) for 180 days, and the shear strength of the polymer protective layer 1 before and after immersion was tested. The results are shown in Table 1.
  • Embodiment 3 The method and material of Embodiment 3 are adopted, except that the pole piece assembly does not include a connecting piece, the pole piece protrudes from the pole piece, the pole piece has a lead-out piece, and the pole ear and the lead-out piece are welded to form a welding connection portion. .
  • the pole piece assembly was sealed and immersed in an electrolyte at a high temperature (80 ° C.) for 180 days, and the shear strength of the polymer protective layer before and after immersion was tested. The results are shown in Table 1.
  • Example 8 The method of Example 8 is adopted, except that an insulating polypropylene is adhered to the polymer protective layer to form an insulating layer.
  • Example 4 The method and material of Example 4 are adopted, except that the pole piece assembly does not include a connecting piece, the pole piece protrudes from the pole piece, the pole piece has a lead-out piece, and the pole ear and the lead-out piece are welded to form a welding connection portion. .
  • the pole piece assembly was sealed and immersed in an electrolyte at a high temperature (80 ° C.) for 180 days, and the shear strength of the polymer protective layer before and after immersion was tested. The results are shown in Table 1.
  • Example 8 The method and material of Example 8 were adopted, except that the ratio of the maximum height of the welding defect to the thickness of the hot-melt adhesive layer was 0.3: 1.
  • the pole piece assembly was sealed and immersed in an electrolyte at a high temperature (80 ° C.) for 180 days, and the shear strength of the polymer protective layer before and after immersion was tested. The results are shown in Table 1.
  • Example 1 The method and material of Example 1 were used, except that ordinary insulating tape (commercial number: 471 purchased from 3M Company) was affixed to the surface of the welding connection portion.
  • ordinary insulating tape commercial number: 471 purchased from 3M Company
  • the assembly was sealed and immersed in an electrolyte at a high temperature (80 ° C.) for 180 days, and the shear strength of the polymer protective layer before and after immersion was tested.
  • the results are shown in Table 1.
  • Example 2 0.85 0.77
  • Example 3 1.40 1.25
  • Example 4 1.35 1.22
  • Example 5 1.45 1.35
  • Example 6 0.95 0.87
  • Example 7 1.00 0.90
  • Example 8 1.55 1.38
  • Example 9 1.54 1.36
  • Example 10 1.73 1.60
  • Example 11 1.58 1.40 Comparative Example 1 0.75 0.05
  • the polymer protective layer of the lithium ion secondary battery module of the present application has higher shear strength before and after immersion compared with the module (comparative example 1) with ordinary insulating tape, especially the After the electrolyte is soaked at a high temperature, the shear strength of the polymer protective layer of the present application does not decrease significantly, and it can still maintain effective protection of the welded connection portion and improve the safety of battery use.

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Abstract

公开了一种锂离子二次电池组件及其制备方法和锂离子二次电池，该组件包括极片和极柱，所述极片上伸出有极耳；所述极耳与所述极柱之间具有焊接形成的焊接连接部；所述焊接连接部具有凸起的焊接缺陷；所述焊接连接部的表面上覆盖有聚合物保护层，所述聚合物保护层的厚度大于或等于所述凸起的焊接缺陷的厚度，所述凸起的焊接缺陷嵌入在所述聚合物保护层中。

Description

锂离子二次电池组件及其制备方法和锂离子二次电池
优先权信息
本公开请求于2018年05月31日向中国国家知识产权局提交的、专利申请号为201810556198.X、申请名称为“锂离子二次电池组件及其制备方法和锂离子二次电池”的中国专利申请的优先权，并且其全部内容通过引用结合在本公开中。
技术领域
本公开涉及锂离子二次电池领域，涉及一种锂离子二次电池组件及其制备方法和锂离子二次电池。
背景技术
锂离子二次电池在制作过程中电极芯集流体箔材需要与提供电池外部连接的接头焊接起来，这个过程在动力电池中较为复杂，会存在多个焊接工序，例如集流体箔材极耳的预焊、箔材极耳与软连接片焊接到一起，软连接片与电池盖板的焊接等等。目前这些工序多采用超声焊接或激光焊接等方式，在焊接过程中会产生一些焊渣、毛刺等对电池安全性造成隐患的缺陷。目前电池中为提升安全性一般是采取除尘后在这些高风险区域贴绝缘胶布或耐高温绝缘胶布的方式，以解决上述问题。
这类产品存在以下缺点：一是胶布耐电解液浸泡性能较差，因为焊缝的存在导致金属表面凹凸不平，胶布与金属表面无法紧密贴合，电解液容易浸入胶带内部，破坏胶带与金属表面的粘结，导致胶带脱落；当焊接的接头这类高风险区暴露出来之后，上述的焊渣、毛刺等结构会危害电池的安全性能。二是某些较大或较尖锐的焊渣或毛刺结构会刺破胶布，从而导致贴胶布的保护措施失效。
公开内容
本公开的目的是提供一种锂离子二次电池组件，该组件能够防止焊渣、毛刺等缺陷暴露，保证电池安全性。
为了实现上述目的，本公开第一方面提供一种锂离子二次电池组件，该组件包括极片和极柱，所述极片上伸出有极耳；所述极耳与所述极柱之间具有焊接形成的焊接连接部；所述焊接连接部具有凸起的焊接缺陷；所述焊接连接部的表面上覆盖有聚合物保护层，所述聚合物保护层的厚度大于或等于所述凸起的焊接缺陷的厚度，所述凸起的焊接缺陷嵌入在所述聚合物保护层中。
一些实施例中，所述凸起的焊接缺陷与所述聚合物保护层完全接触。
一些实施例中，所述聚合物保护层为通过在焊接连接部表面点胶或涂胶形成的聚合物保护层。
一些实施例中，所述焊接连接部包括第一焊接连接部；所述极柱与所述极耳焊接形成的第一焊接连接部，或所述极柱伸出的引出片与所述极耳焊接形成的第一焊接连接部；所述第一焊接连接部包括第一焊接连接部的极耳侧；所述聚合物保护层覆盖在所述第一焊接连接部的极耳侧的表面上。
一些实施例中，该组件还包括连接片，所述焊接连接部包括第二焊接连接部和第三焊接连接部；所述连接片的一端与所述极耳焊接形成所述第二焊接连接部；所述连接片的另一端与所述极柱焊接形成所述第三焊接连接部，或所述连接片的另一端与所述极柱伸出的引出片焊接形成第三焊接连接部；所述第三焊接连接部包括第三焊接连接部的连接片侧；所述聚合物保护层至少覆盖在所述第二焊接连接部的双侧表面上和所述第三焊接连接部的连接片侧的表面上。
一些实施例中，所述凸起的焊接缺陷的厚度与所述聚合物保护层的厚度的比例为(0.1～0.9)：1。
一些实施例中，所述焊接连接部还具有焊缝，所述聚合物保护层具有向所述焊缝中延伸的填充突出部。
一些实施例中，该组件还包括绝缘层，所述绝缘层覆盖所述聚合物保护层。
一些实施例中，所述绝缘层为聚丙烯绝缘层、聚乙烯绝缘层和聚氯乙烯绝缘层中的至少一种。
一些实施例中，所述聚合物保护层中的聚合物的成型收缩率为1～4％。
一些实施例中，所述聚合物保护层为热熔胶聚合物保护层、光固化胶聚合物保护层和压敏胶聚合物保护层中的至少一种。
一些实施例中，所述热熔胶为选自无规聚丙烯热熔胶、乙烯和\或丙烯与含氧烯烃的共聚物、聚苯乙烯、苯乙烯与丁二烯共聚物、异戊二烯与丁二烯共聚物、环氧改性的苯乙烯-丁二烯-苯乙烯共聚物和二聚酸型聚酰胺热熔胶中的至少一种；所述光固化胶为紫外光固化胶，所述紫外光固化胶为选自丙烯酸酯类紫外光固化胶、脂环族环氧树脂类紫外光固化胶、脂肪族环氧树脂类紫外光固化胶、芳香族环氧树脂类紫外光固化胶、双酚A环氧改性丙烯酸酯类紫外光固化胶和酚醛环氧改性丙烯酸酯类紫外光固化胶中的至少一种；所述压敏胶 为选自交联型丙烯酸酯类压敏胶、有机硅类压敏胶、聚氨酯类压敏胶和橡胶类压敏胶中的至少一种。
本公开第二方面提供一种制备锂离子二次电池组件的方法，该组件包括极片和极柱，所述极片上伸出有极耳，所述极柱上伸出有引出片，该方法包括如下步骤：S1，将所述极耳焊接在所述极柱上并形成焊接连接部，所述焊接连接部具有凸起的焊接缺陷S2，在所述焊接连接部的表面施用聚合物以成型形成聚合物保护层并使所述凸起的焊接缺陷嵌入在所述聚合物保护层中，所述聚合物的施用量为使得所述聚合物保护层的厚度大于或等于所述凸起的焊接缺陷的厚度。
一些实施例中，形成所述聚合物保护层的方法为点胶或涂胶。
一些实施例中，所述焊接连接部包括第一焊接连接部；形成所述第一焊接连接部的方法包括：将所述极耳焊接在所述极柱上形成所述第一焊接连接部，或将所述极耳焊接在所述极柱伸出的引出片上形成所述第一焊接连接部；所述第一焊接连接部包括第一焊接连接部的极耳侧，在所述第一焊接连接部的极耳侧表面上施用聚合物以成型形成所述聚合物保护层。
一些实施例中，该组件还包括连接片，所述焊接连接部包括第二焊接连接部和第三焊接连接部；形成所述第二焊接连接部和所述第三焊接连接部的方法包括：将所述连接片的一端焊接在所述极耳上形成所述第二焊接连接部；将所述连接片的另一端焊接在所述极柱上形成所述第三焊接连接部，或将所述连接片的另一端焊接在所述极柱伸出的引出片上形成所述第三焊接连接部；所述第三焊接连接部包括第三焊接连接部的连接片侧；在所述第二焊接连接部的双侧表面上和所述第三焊接连接部的连接片侧表面上施用聚合物以分别成型形成所述聚合物保护层。
一些实施例中，步骤S2的操作包括如下方式中的至少一种：方式a：在所述焊接连接部的表面涂布待固化的热熔胶，并固化形成所述聚合物保护层；方式b：在所述焊接连接部的表面涂布待固化的光固化胶，并在光照条件下固化形成所述聚合物保护层；及方式c：使压敏胶在施加压力的状态下覆盖所述焊接连接部的表面，然后去除所述压力，形成所述聚合物保护层。
一些实施例中，所述熔融状态的热熔胶的温度为100～180℃，粘度为1000～10000CP，所述固化的温度为20～25℃，固化时间为0～30s；所述光固化胶的粘度为1000～5000CP，所述光照的时间为5～20s；所述压力为0.2～0.8MPa。
一些实施例中，该方法还包括：在所述聚合物保护层上覆盖绝缘材料并形成绝缘层。
本公开第三方面提供一种锂离子二次电池，该电池包括盖板以及本公开第一方面的锂离子二次电池组件或采用本公开第二方面所述的方法得到的锂离子二次电池组件。
通过上述技术方案，本公开的锂离子二次电池组件通过在极耳与引出片的焊接连接部表面设置聚合物保护层，能够包埋焊接连接部中具有凸起的焊接缺陷并使其嵌入聚合物保护层中，从而固定了上述焊接缺陷并使焊接连接部表面平整无突出物，有效解决了焊接缺陷突出刺破隔膜引起电池安全性能降低的问题；同时聚合物保护层具有耐电解液浸泡、耐电化学氧化-还原的特性，提高了组件和电池的耐用性和稳定性。
本公开的附加方面和优点将在下面的描述中部分给出，部分将从下面的描述中变得明显，或通过本公开的实践了解到。
附图说明
附图是用来提供对本公开的进一步理解，并且构成说明书的一部分，与下面的具体实施方式一起用于解释本公开，但并不构成对本公开的限制。在附图中：
图1是本公开的锂离子二次电池的一种具体实施方式的焊接连接部截面示意图。
图2是本公开的锂离子二次电池的一种具体实施方式的结构示意图。
图3是本公开的锂离子二次电池的一种具体实施方式的侧视图(即图2的左视图)。
图4是本公开的锂离子二次电池的另一种具体实施方式的结构示意图。
图5是本公开的锂离子二次电池的另一种具体实施方式的侧视图(即图4的左视图)。
图6是本公开的锂离子二次电池组件的一种具体实施方式的电解液浸泡前的截面照片。
图7是本公开的锂离子二次电池组件的一种具体实施方式的电解液浸泡后的截面照片。
图8是本公开的锂离子二次电池组件的另一种具体实施方式的电解液浸泡前的截面照片。
图9是本公开的锂离子二次电池组件的另一种具体实施方式的电解液浸泡后的截面照片。
附图标记说明
1聚合物保护层   2凸起的焊接缺陷
3极柱           4引出片
5连接片         6极耳
7极片           8电池盖板
9绝缘层         10焊接连接部
公开详细描述
下面详细描述本公开的实施例，所述实施例的示例在附图中示出，自始至终相同或类似的标号表示相同或类似的元件或具有相同或类似功能的元件。下面通过参考附图描述的实施例是示例性的，旨在用于解释本公开，而不能理解为对本公开的限制。
在本文中所披露的范围的端点和任何值都不限于该精确的范围或值，这些范围或值应当理解为包含接近这些范围或值的值。对于数值范围来说，各个范围的端点值之间、各个范围的端点值和单独的点值之间，以及单独的点值之间可以彼此组合而得到一个或多个新的数值范围，这些数值范围应被视为在本文中具体公开。
在本公开中，在未作相反说明的情况下，使用的方位词如“上、下”通常是指装置在正常使用状态下的上和下。“内、外”是针对装置本身的轮廓而言的。
如图1-图5所示，本公开第一方面提供一种锂离子二次电池组件，该组件包括极片7和极柱3，极片7上伸出有极耳6；极耳6与极柱3之间具有焊接形成的焊接连接部10；焊接连接部10具有凸起的焊接缺陷2；焊接连接部10的表面上覆盖有聚合物保护层1，聚合物保护层1的厚度大于或等于凸起的焊接缺陷2的厚度，凸起的焊接缺陷2嵌入在聚合物保护层1中。
本公开的锂离子二次电池组件通过在极耳与引出片的焊接连接部表面设置聚合物保护层，能够包埋焊接连接部中具有凸起的焊接缺陷并使其嵌入聚合物保护层中，从而固定了上述焊接缺陷并使焊接连接部表面平整无突出物，有效解决了焊接缺陷突出刺破隔膜引起电池安全性能降低的问题；同时聚合物保护层具有耐电解液浸泡、耐电化学氧化-还原的特性，提高了组件和电池的耐用性和稳定性。
根据本公开，聚合物保护层可以部分或全部覆盖焊接连接部，优选覆盖焊接连接部的整个表面，以提高焊接部分的稳定性。
如图4-图5所示，在本公开的一种具体实施方式中，焊接连接部可以包括第一焊接连接部，第一焊接连接部可以为极柱3与极耳6焊接形成的第一焊接连接部，或者为极柱伸出的引出片4与极耳6焊接形成的第一焊接连接部；第一焊接连接部可以包括第一焊接连接部的极耳侧，聚合物保护层1可以覆盖在第一焊接连接部的极耳侧的表面上。其中，第一焊接连接部的极耳侧的表面是指第一焊接连接部的两个主表面中，相对靠近极耳一侧的主表面。
如图2-图3所示，在本公开的另一种具体实施方式中，该组件还可以包括连接片5，焊接连接部可以包括第二焊接连接部和第三焊接连接部；在这种情况中，连接片5的一端可以与极耳6焊接形成第二焊接连接部；连接片5的另一端可以与极柱3焊接形成第三焊接连接部，或连接片5的另一端可以与极柱伸出的引出片4焊接形成第三焊接连接部；第三焊接连接部可以包括第三焊接连接部的连接片侧，聚合物保护层可以至少覆盖在第二焊接 连接部的双侧表面上和第三焊接连接部的连接片侧的表面上。其中，第三焊接连接部的连接片侧的表面是指第三焊接连接部的两个主表面中，相对靠近连接片一侧的主表面。
根据本公开，为了完全包埋住凸起的焊接缺陷，凸起的焊接缺陷的厚度与聚合物保护层的厚度的比例可以为(0.1～0.9)：1，例如0.1:1、0.2:1、0.3:1、0.4:1、0.5:1、0.6:1、0.7:1、0.8:1、0.9:1，优选为(0.3～0.6)：1。其中，聚合物保护层的厚度是指聚合物保护层的表面相对于聚合物保护层与焊接连接部的接触面的最大厚度，凸起的焊接缺陷的厚度是指凸起的焊接缺陷在聚合物保护层厚度方向上的最大高度，在优选的厚度范围内，能够进一步保证组件使用过程中焊接连接部的所有凸起的焊接缺陷不刺破该聚合物保护层，对极片组件起到有效的保护作用，降低焊渣、毛刺刺穿隔膜导致电池短路的风险，提升电池的安全性，又能够快速成型保护层、避免保护层过厚影响极片组件的组装和性能。
根据本公开，凸起的焊接缺陷的含义为本领域技术人员所熟知的，例如凸起的焊接缺陷可以包括凸出于极耳和引出片的焊接前的表面的毛刺和/或焊渣。优选地，毛刺和焊渣的最大高度可以为50-800μm，例如50μm、75μm、100μm、125μm、150μm、175μm、200μm、225μm、250μm、275μm、300μm、325μm、350μm、375μm、400μm、425μm、450μm、475μm、500μm、525μm、550μm、575μm、600μm、625μm、650μm、675μm、700μm、725μm、750μm、775μm、800μm，进一步优选为50～500μm。
根据本公开，焊接连接部还可以具有焊缝，聚合物保护层可以具有向焊缝中延伸的填充突出部，以进一步使聚合物保护层充分贴合焊接连接部，提高保护层与焊接连接部表面的结合力。其中焊缝的含义为本领域技术人员所熟知的，即焊接后形成的低于焊接连接部原始表面的凹陷和、沟槽和缝隙中的至少一种。优选地，所述焊缝的深度可以为0～500微米，例如0微米、30微米、50微米、75微米、100微米、130微米、150微米、175微米、200微米、230微米、250微米、275微米、300微米、330微米、350微米、375微米、400微米、430微米、450微米、475微米、500微米，更优选为30-300μm，进一步优选为30～150μm。
进一步地，为了充分保护焊接连接部，防止缺陷暴露，在本公开的一种具体实施方式中，聚合物保护层还可以覆盖至少部分极耳和至少部分引出片中的至少一者；或者，聚合物保护层还可以覆盖至少部分极耳、至少部分引出片和至少部分连接片中的至少一者。
根据本公开，为了使聚合物保护层充分包裹和贴合凸起的焊接缺陷以使该凸起的焊接缺陷完全嵌入聚合物保护层中，在本公开的一种具体实施方式中，聚合物保护层可以为通过在焊接连接部表面点胶或涂胶形成的聚合物保护层。在这一实施方式中，点胶法及涂胶法能够保证聚合物材料在具有一定流动性时充分接触并贴合焊接连接部的表面及凸起的焊接缺陷的表面，并在保持贴合的状态下成型形成聚合物保护层，由此得到的聚合物保护层能够充分接触焊接连接部表面、达到最大程度的接触并贴合凸起的焊接缺陷的表面，从而 提高聚合物保护层对焊接连接部的保护效果。
为了进一步提高保护层与凸起的焊接缺陷的粘结力、防止凸起的焊接缺陷在使用中产生位移，提高组件的耐用性，在本公开的一种具体实施方式中，凸起的焊接缺陷可以与聚合物保护层完全接触，其中完全接触是指焊接连接部的凸起的焊接缺陷嵌入聚合物保护层且在金相显微镜下观察，在误差范围内，凸起的焊接缺陷的所有表面完全与聚合物贴合，焊接缺陷的表面与聚合物之间无缝隙；其中需要说明的是，在某些不可避免的工艺条件限制的情况下，凸起的焊接缺陷的表面也可能与聚合物保护层之间具有一定空隙，例如微气泡，在此类空隙面积占凸起的焊接缺陷的表面与聚合物保护层接触面面积的10％以内的情况下，依然属于本申请的保护范围。
根据本公开，为了进一步提高保护层与焊接连接部表面的粘结力，优选地，聚合物保护层的聚合物的成型收缩率可以为1～4％，例如1％、1.1％、1.2％、1.3％、1.4％、1.5％、1.6％、1.7％、1.8％、1.9％、2％、2.1％、2.2％、2.3％、2.4％、2.5％、2.6％、2.7％、2.8％、2.9％、3％、3.1％、3.2％、3.3％、3.4％、3.5％、3.6％、3.7％、3.8％、3.9％、4％，更优选为1～3％，以避免成型后的聚合物过分收缩，造成聚合物保护层与焊接连接部表面产生过大间隙。成型收缩率的含义为本领域技术人员所熟知的，即材料在成型前(例如热熔胶在升温状态下、光固化胶在未经光照时)的尺寸与成型后(例如热熔胶在固化温度下固化后、光固化胶在光照固化后)形成制件的尺寸之差的百分比。成型收缩率的测试方法可以参考标准GB/T15585-1995热塑性塑料注射成型收缩率的测定来进行。
根据本公开，聚合物保护层的聚合物可以为本领域常规的，优选能够耐电解液浸泡、耐电化学氧化-还原的聚合物材料。进一步地，为了提高聚合物保护层对焊接连接部表面的粘结力，聚合物保护层的聚合物可以优选为在一定状态下能够具有流动性、并能在条件去除后固化的聚合物材料，以便于使聚合物保护层充分填充或嵌合焊接缺陷，与焊接连接部表面充分接触从而提高粘结力，例如，在本公开优选的实施方式中，聚合物保护层可以为热熔胶聚合物保护层、光固化胶聚合物保护层和压敏胶聚合物保护层中的至少一种，可选为施用便捷的压敏胶聚合物保护层。其中在本公开的组件还包括连接片的实施方式中，连接片两端分别设有聚合物保护层，两个聚合物保护层的聚合物可以相同或不同，优选相同。
根据本公开，热熔胶的含义为本领域技术人员所熟知的，即在一定温度范围内其流动性等物理状态随温度变化和改变的材料，热熔胶的种类可以为本领域常规的，优选为选自无规共聚的聚丙烯热熔胶、乙烯和/或丙烯与含氧烯烃的共聚物、聚苯乙烯、苯乙烯与丁二烯共聚物、异戊二烯与丁二烯共聚物、环氧改性的苯乙烯-丁二烯-苯乙烯共聚物和二聚酸型聚酰胺热熔胶中的至少一种。上述优选种类的热熔胶熔融温度和粘度适宜，熔融温度不会对极片性能产生影响；固化性能好且耐电解液浸泡，能够在适宜的流动性条件下充分接触 贴合焊接连接部表面，形成的保护层与焊接连接部表面粘结性好且便于涂覆操作。热熔胶的涂覆方式可以为本领域常规的，例如点胶或涂胶。
根据本公开，光固化胶的含义为本领域技术人员所熟知的，即在光照条件下可固化的材料，光固化胶可以采用本领域常规的种类，例如紫外光固化胶和/或可见光固化胶，在本公开的一种具体实施方式中，优选光固化胶为紫外光固化胶，以提高固化速度。紫外光固化胶可以选自本领域的常规种类，本公开优选的紫外光固化胶可以为选自丙烯酸酯类紫外光固化胶、脂环族环氧树脂类紫外光固化胶、脂肪族环氧树脂类紫外光固化胶、芳香族环氧树脂类紫外光固化胶、双酚A环氧改性丙烯酸酯类紫外光固化胶和酚醛环氧改性丙烯酸酯类紫外光固化胶中的至少一种。上述优选种类的紫外光固化胶固化速度快、耐电解液性能好且在熔融状态下具有适宜的粘度和流动性，有利于贴合焊接连接部表面，提高保护层粘结力。
根据本公开，压敏胶的含义和种类可以为本领域技术人员所熟知的，即对压力有敏感性的胶粘剂，通常压敏胶在受压力状态下具有一定流动性，例如可以选自橡胶类压敏胶和树脂类压敏胶，优选地，压敏胶可以为选自交联型丙烯酸酯类压敏胶、有机硅类压敏胶、聚氨酯类压敏胶和橡胶类压敏胶中的至少一种。上述优选种类的压敏胶粘结力强、使用方便，并且具有良好的耐电解液和耐电化学性能，此外，压敏胶使用过程中由于压力的存在，可对较大或较高的焊渣产生一定的压力，降低其高度，有效避免极端较大焊渣的出现，确保保护层表面平整；同时，压敏胶压实、撤销压力后，保护层立即生效，工艺过程中不需要加热装置或光源，更有利于提高生产效率。
为了进一步提升组件的安全性能，在本公开的一种具体实施方式中，该组件还可以包括绝缘层，绝缘层可以覆盖聚合物保护层并一些实施例中还覆盖极耳、引出片和连接片中的至少一种。绝缘层可以含有本领域常规的绝缘材料，优选地，绝缘层可以为聚丙烯绝缘层、聚乙烯绝缘层和聚氯乙烯绝缘层中的至少一种，绝缘层的厚度可以为30～300μm，例如30μm、40μm、50μm、60μm、70μm、80μm、90μm、100μm、110μm、120μm、130μm、140μm、150μm、160μm、170μm、180μm、190μm、200μm、210μm、220μm、230μm、240μm、250μm、260μm、270μm、280μm、290μm、300μm，优选为30～100μm。将绝缘层施加到聚合物保护层的方法也可以为本领域常规的，例如通过粘接或套设的方法。在本公开的组件还包括连接片的实施方式中，连接片两端的两个焊接连接部优选分别设有绝缘层，以进一步，加强对高风险区域的保护，更好地防止凸起的焊接缺陷带来的劣质问题，提升电池的安全性能。
本公开第二方面提供一种制备上述锂离子二次电池组件的方法，该组件包括极片和极柱，极片上伸出有极耳，极柱上伸出有引出片，该方法包括如下步骤：
S1，将极耳焊接在极柱上并形成焊接连接部，焊接连接部具有凸起的焊接缺陷；
S2，在焊接连接部的表面施用聚合物以成型形成聚合物保护层并使凸起的焊接缺陷嵌入在聚合物保护层中，聚合物的施用量为使得聚合物保护层的厚度大于或等于凸起的焊接缺陷的厚度。
本公开的方法通过在极耳与引出片的焊接连接部表面设置聚合物保护层，能够包埋焊接部中具有凸起的焊接缺陷并使其嵌入聚合物保护层中，从而固定上述焊接缺陷的位置不使其产生位移，并使焊接部表面平整无突出物，有效解决了焊接缺陷突出刺破隔膜引起电池安全性能降低的问题；同时聚合物保护层具有耐电解液浸泡、耐电化学氧化-还原的特性，提高了组件和电池的耐用性和稳定性。
根据本公开，该方法可以包括使聚合物保护层部分或全部覆盖焊接连接部，优选使聚合物保护层覆盖焊接连接部的整个表面，以提高焊接部分的稳定性。
根据本公开，为了使聚合物保护层充分包裹和贴合凸起的焊接缺陷以使该凸起的焊接缺陷完全嵌入聚合物保护层中，在本公开的一种具体实施方式中，形成聚合物保护层的方法可以为通过在焊接连接部表面点胶或涂胶。在这一实施方式中，点胶法和涂胶法能够保证聚合物材料在具有一定流动性时充分接触并贴合焊接连接部的表面及凸起的焊接缺陷的表面，并在保持贴合的状态下成型形成聚合物保护层，由此得到的聚合物保护层能够充分接触焊接连接部表面、达到最大程度的接触并贴合凸起的焊接缺陷的表面，从而提高聚合物保护层对焊接连接部的保护效果。
在本公开的一种具体实施方式中，焊接连接部可以包括第一焊接连接部，形成第一焊接连接部的方法可以包括：将极耳焊接在极柱上形成第一焊接连接部，或将极耳焊接在极柱伸出的引出片上形成第一焊接连接部；第一焊接连接部可以包括第一焊接连接部的极耳侧，在第一焊接连接部的极耳侧表面上施用聚合物以成型形成聚合物保护层。
在另一种具体实施方式中，该组件还可以包括连接片，可以通过连接片将极柱与极耳焊接在一起，焊接连接部可以包括第二焊接连接部和第三焊接连接部，在这种情况下，形成第二焊接连接部和第三焊接连接部的方法可以包括：将连接片的一端焊接在极耳上形成第二焊接连接部；将连接片的另一端焊接在极柱上形成第三焊接连接部，或将连接片的另一端焊接在极柱伸出的引出片上形成第三焊接连接部；第三焊接连接部包括第三焊接连接部的连接片侧；在第二焊接连接部的双侧表面上和第三焊接连接部的连接片侧表面上施用聚合物以分别成型形成聚合物保护层。
根据本公开，为了完全包埋住凸起的焊接缺陷，凸起的焊接缺陷的厚度与聚合物保护层的厚度的比例可以为(0.1～0.9)：1，例如0.1:1、0.2:1、0.3:1、0.4:1、0.5:1、0.6:1、0.7:1、0.8:1、0.9:1，优选为(0.3～0.6)：1。其中，聚合物保护层的厚度是指聚合物保护层的表面相对于焊接连接部的原始表面的最大厚度，在优选的厚度范围内，能够进一步保证组件使 用过程中焊接连接部的所有凸起的焊接缺陷不刺破该聚合物保护层，对极片组件起到有效的保护作用，降低焊渣、毛刺刺穿隔膜导致电池短路的风险，提升电池的安全性，又能够快速成型保护层、避免保护层过厚影响极片组件的组装和性能。
根据本公开，凸起的焊接缺陷的含义为本领域技术人员所熟知的，例如凸起的焊接缺陷可以包括凸出于极耳和引出片的原始表面的毛刺和/或焊渣，其中极耳和引出片的原始表面是指二者未经焊接之前的表面。
根据本公开，焊接连接部还可以具有焊缝，并且，可以使所施用的聚合物进入至焊缝中以形成填充突出部，以进一步使聚合物保护层充分贴合焊接连接部，提高保护层与焊接连接部表面的结合力。其中焊缝的含义为本领域技术人员所熟知的，即焊接后形成的低于焊接连接部的原始表面的凹陷和、沟槽和缝隙中的至少一种。
进一步地，可以对焊接连接部的表面进行处理后再施用聚合物，以提高聚合物保护层的结合力，进行表面处理的方法可以包括本领域常规的，例如表面处理可包括表面刻蚀处理。其中，表面刻蚀处理可优选电化学刻蚀、酸碱刻蚀或氧化剂刻蚀中的一种或几种，提高金属与有机聚合物的结合力。本发明在表面处理前还可以包括对焊接连接部表面进行预处理，预处理为本领域技术人员公知的各种处理，一般包括对表面进行打磨、清洁等。
根据本公开，为了进一步提高聚合物保护层与焊接连接部表面的粘结力，优选地，聚合物保护层的聚合物的成型收缩率可以为1～4％，例如1％、1.1％、1.2％、1.3％、1.4％、1.5％、1.6％、1.7％、1.8％、1.9％、2％、2.1％、2.2％、2.3％、2.4％、2.5％、2.6％、2.7％、2.8％、2.9％、3％、3.1％、3.2％、3.3％、3.4％、3.5％、3.6％、3.7％、3.8％、3.9％、4％，更优选为1～3％，以避免成型后的聚合物材料过分收缩，造成聚合物保护层与焊接连接部表面产生过大间隙。成型收缩率的含义和测试方法如上文。
根据本公开，聚合物保护层的聚合物可以为本领域常规的，优选能够耐电解液浸泡、耐电化学氧化-还原的聚合物材料。进一步地，为了提高聚合物保护层对焊接连接部的粘结力，聚合物保护层的聚合物可以优选为在一定状态下能够具有流动性、并能在条件去除后固化的材料，以便于使保护层充分填充或嵌合焊接缺陷，与焊接连接部表面充分接触从而提高粘结力，例如，在本公开优选的实施方式中，聚合物保护层可以为热熔胶聚合物保护层、光固化胶聚合物保护层和压敏胶聚合物保护层中的至少一种，进一步优选为施用便捷的压敏胶聚合物保护层。其中在本公开的组件还包括连接片的实施方式中，连接片两端分别设有聚合物保护层，两个聚合物保护层的可以相同或不同，优选相同。
根据本公开，热熔胶的含义为本领域技术人员所熟知的，即在一定温度范围内其流动性等物理状态随温度变化和改变的材料，热熔胶的涂覆方式可以为本领域常规的，例如注塑、热压、喷涂或涂布。光固化胶的含义为本领域技术人员所熟知的，即在光照条件下可 固化的材料，光固化胶的涂覆方式可以为本领域常规的，例如注塑、热压、喷涂或涂布。压敏胶的含义和种类可以为本领域技术人员所熟知的，即对压力有敏感性的胶粘剂，通常压敏胶在受压力状态下具有一定流动性。
为了保证粘接效果和便于操作，步骤S2的操作可以包括如下方式中的至少一种：
方式a：在焊接连接部的表面涂布待固化的热熔胶，并固化形成聚合物保护层；
方式b：在焊接连接部的表面涂布待固化的光固化胶，并在光照条件下固化形成聚合物保护层；及
方式c：使压敏胶在施加压力的状态下覆盖焊接连接部的表面，然后去除压力，形成聚合物保护层。
其中，在方式a中，涂布熔融状态的热熔胶的条件可以在较大范围内变化，优选地，熔融状态的热熔胶的温度可以为100～180℃，例如100℃、110℃、120℃、130℃、140℃、150℃、160℃、170℃、180℃，优选为110-150℃，粘度可以为1000～10000CP，例如1000CP、1500CP、2000CP、2500CP、3000CP、3500CP、4000CP、4500CP、5000CP、5500CP、6000CP、6500CP、7000CP、7500CP、8000CP、8500CP、9000CP、9500CP、10000CP，优选为1500～5000CP，固化的温度可以为20～25℃，例如20℃、21℃、22℃、23℃、24℃、25℃，固化时间可以为0～30s，例如1s、5s、10s、15s、17s、20s、22s、25s、30s，优选为15～25s。
根据本公开，热熔胶的种类可以为本领域常规的，进一步地，为了满足上述熔融涂布的条件，热熔胶可以优选为选自无规聚丙烯热熔胶、乙烯和\或丙烯与含氧烯烃的共聚物、聚苯乙烯、苯乙烯与丁二烯共聚物、异戊二烯与丁二烯共聚物、环氧改性的苯乙烯-丁二烯-苯乙烯共聚物和二聚酸型聚酰胺热熔胶中的至少一种。上述优选种类的热熔胶熔融温度和粘度适宜，熔融温度不会对极片性能产生影响；固化性能好且耐电解液浸泡，能够在适宜的流动性条件下充分接触贴合焊接连接部表面，形成的保护层与焊接连接部表面粘结性好且便于涂覆操作。
其中，在方式b中，光照的波长和强度可以根据光固化胶的种类进行选择，此为本领域技术人员所熟知的，此处不再赘述。
进一步地，为了保证光固化胶在固化前具有适宜的流动性以使其能够充分贴合、浸润或填充上述的焊接缺陷，优选地，光固化胶的粘度可以为1000～5000CP，例如1000CP、1500CP、2000CP、2500CP、3000CP、3500CP、4000CP、4500CP、5000CP，优选为1000-3000CP；进一步地，为了保证生产效率，光照的时间可以为5～20s，例如5s、10s、11s、12s、13s、14s、15s、17s、20s，优选为10-15s。
根据本公开，光固化胶可以采用本领域常规的种类，例如紫外光固化胶和/或可见光固化胶，在本公开的一种具体实施方式中，优选光固化胶为紫外光固化胶，以提高固化速度。 紫外光固化胶可以选自本领域的常规种类，本公开优选的紫外光固化胶可以为选自丙烯酸酯类紫外光固化胶、脂环族环氧树脂类紫外光固化胶、脂肪族环氧树脂类紫外光固化胶、芳香族环氧树脂类紫外光固化胶、双酚A环氧改性丙烯酸酯类紫外光固化胶和酚醛环氧改性丙烯酸酯类紫外光固化胶中的至少一种。上述优选种类的紫外光固化胶固化速度快、耐电解液性能好且在熔融状态下具有适宜的粘度和流动性，有利于贴合焊接连接部表面，提高保护层粘结力。
其中，在方式c中，为了保证粘结效果，其中施加的压力可以为0.2～0.8MPa，例如0.2MPa、0.3MPa、0.4MPa、0.5MPa、0.6MPa、0.7MPa、0.8MPa，优选为0.4～0.6MPa。该方法中压敏胶使用过程中由于存在压力，可对较大或较高的焊渣产生一定的压力，降低其高度，有效避免极端较大焊渣的出现；同时，压敏胶压实并去除压力后，聚合物保护层立即生效，工艺过程中不需要加热装置或光源，更有利于提高生产效率。
根据本公开，压敏胶可以选自橡胶类压敏胶和树脂类压敏胶，优选地，压敏胶可以为选自交联型丙烯酸酯类压敏胶、有机硅类压敏胶、聚氨酯类压敏胶和橡胶类压敏胶中的至少一种。上述优选种类的压敏胶粘性强、使用方便，并且具有良好的耐电解液和耐电化学性能。
进一步地，为了提高压敏胶的粘性和对被粘材料良好的湿润性，从而提高保护层与焊接连接部表面的粘结力，在本公开的一种实施方式中，压敏胶可以为橡胶类压敏胶，其中橡胶类压敏胶优选为改性丁腈橡胶；进一步地，改性丁腈橡胶中丙烯腈结构单元的重量含量可以为25％～50％，例如25％、27％、30％、32％、35％、37％、40％、43％、45％、47％、50％，分子量可以为10～30万(重均分子量)，例如10万、12万、14万、16万、18万、20万、22万、24万、26万、28万、30万，以提高压敏胶的强度和粘结力。
为了进一步提升电极组件的安全性能，在本公开的一种具体实施方式中，该方法可以包括：在聚合物保护层上覆盖绝缘材料并形成绝缘层。绝缘材料可以为本领域常规的，优选为绝缘聚丙烯、聚乙烯和聚氯乙烯中的至少一种；将绝缘层施加到聚合物保护层的方法也可以为本领域常规的，例如通过粘接或套设的方法。在本公开的组件还包括连接片的实施方式中，该方法可以包括在连接片两端的两个焊接连接部优选分别设置绝缘层，以增加对高风险区域的保护，进一步提升电池的安全性能。
本公开第三方面提供一种锂离子二次电池，该电池包括本公开第一方面的锂离子二次电池组件或采用本公开第二方面的方法得到的锂离子二次电池组件以及盖板。
本公开的锂离子二次电池的对焊接连接部位存在的焊渣、毛刺等结构的高风险区域进行了有效保护，可以降低焊渣、毛刺刺穿隔膜导致电池短路的风险，提升了电池的安全性。
根据本公开，锂离子二次电池的组件中的极柱可以设置在盖板上，以用于与外电路连 接，引出片可以连接极柱并延伸至盖板内侧，以便与极耳或与极耳连接的连接片焊接。
根据本公开，锂离子二次电池中可以包括正极组件和负极组件，优选地正极组件和负极组件分别为本公开的组件，以进一步提高电池的安全性和稳定性。
下面通过实施例进一步描述本公开，但是本公开并不因此而受到任何限制。在本公开的下述实施例和对比例中，剪切强度采用GB/T 7124-2008胶粘剂拉伸剪切强度测定方法进行测试，聚合物保护层的截面形态采用金相显微镜测试，聚合物保护层的厚度也采用金相显微镜测量。
下面参考具体实施例，对本公开进行描述，需要说明的是，这些实施例仅仅是描述性的，而不以任何方式限制本公开。
实施例1
本实施例用于说明本公开的锂离子二次电池组件及其制备方法。
如图2和图3所示，组件包括电连接的极片7、极柱3和连接片5，极片7上伸出有极耳6，极柱3上伸出有引出片4，连接片5的两端分别与极耳6和引出片4焊接以形成两个焊接连接部，将高分子量丁基橡胶压敏胶(购自ITW公司，商品号为sm5190)在0.6MPa压力下覆盖在焊接连接部表面，去除压力后形成聚合物保护层1，凸起的焊接缺陷2的最大高度与聚合物保护层1的厚度的比例为0.5：1。
将该组件密封在电解液高温(80℃)浸泡180天后，观察浸泡前后焊接连接部和聚合物保护层的截面形态，结果分别如图6和图7所示；测试该聚合物保护层浸泡前后的剪切强度，结果列于表1中。
实施例2
本实施例用于说明本公开的锂离子二次电池组件及其制备方法。
采用实施例1的方法，所不同的是，聚合物保护层1上粘有绝缘聚丙烯形成绝缘层9。
将该组件密封在电解液高温(80℃)浸泡180天后，观察浸泡前后焊接连接部和聚合物保护层的截面形态，结果分别如图8和图9所示；测试该聚合物保护层浸泡前后的剪切强度，结果列于表1中。
实施例3
本实施例用于说明本公开的锂离子二次电池组件及其制备方法。
组件包括电连接的极片、极柱和连接片，极片上伸出有极耳，极柱上伸出有引出片，连接片的两端分别与极耳和引出片焊接以形成两个焊接连接部，使热熔胶(购自澳中公司， 商品号为B03)在160℃下熔融(熔融粘度为2500CP)后涂覆于焊接连接部表面，常温固化15s后形成聚合物保护层，厚度为300μm。
将该组件密封在电解液高温(80℃)浸泡180天，测试该聚合物保护层浸泡前后的剪切强度，结果列于表1中。
实施例4
本实施例用于说明本公开的锂离子二次电池组件及其制备方法。
组件包括电连接的极片、极柱和连接片，极片上伸出有极耳，极柱上伸出有引出片，连接片的两端分别与极耳和引出片焊接以形成两个焊接连接部，将紫外光固化胶(购自德邦公司，商品号为703，粘度为2000CP)涂覆于焊接连接部表面，在紫外光照下固化10s后形成聚合物保护层，厚度为250μm。
将该组件密封在电解液高温(80℃)浸泡180天，测试该聚合物保护层浸泡前后的剪切强度，结果列于表1中。
实施例5
本实施例用于说明本公开的锂离子二次电池极片组件及其制备方法。
采用实施例4的方法，所不同的是，聚合物保护层上粘有绝缘聚丙烯形成绝缘层。
将该极片组件密封在电解液高温(80℃)浸泡180天后，测试该聚合物保护层浸泡前后的剪切强度，结果列于表1中。
实施例6
采用实施例1的方法和材质，所不同的是，焊接缺陷的最大高度与压敏胶层的厚度的比例为0.3：1。
将该极片组件密封在电解液高温(80℃)浸泡180天，测试该聚合物保护层浸泡前后的剪切强度，结果列于表1中。
实施例7
如图4和图5所示，采用实施例1的方法和材质，所不同的是，组件不包括连接片，极片7上伸出有极耳6，极柱3上伸出有引出片4，极耳6和引出片4焊接以形成焊接连接部。
将该组件密封在电解液高温(80℃)浸泡180天，测试该聚合物保护层1浸泡前后的剪切强度，结果列于表1中。
实施例8
采用实施例3的方法和材质，所不同的是，极片组件不包括连接片，极片上伸出有极耳，极柱上伸出有引出片，极耳和引出片焊接以形成焊接连接部。
将该极片组件密封在电解液高温(80℃)浸泡180天，测试该聚合物保护层浸泡前后的剪切强度，结果列于表1中。
实施例9
采用实施例8的方法，所不同的是，聚合物保护层上粘有绝缘聚丙烯形成绝缘层。
将该极片组件密封在电解液高温(80℃)浸泡180天后，测试该聚合物保护层浸泡前后的剪切强度，结果列于表1中
实施例10
采用实施例4的方法和材质，所不同的是，极片组件不包括连接片，极片上伸出有极耳，极柱上伸出有引出片，极耳和引出片焊接以形成焊接连接部。
将该极片组件密封在电解液高温(80℃)浸泡180天，测试该聚合物保护层浸泡前后的剪切强度，结果列于表1中。
实施例11
采用实施例8的方法和材质，所不同的是，焊接缺陷的最大高度与热熔胶层的厚度的比例为0.3：1。
将该极片组件密封在电解液高温(80℃)浸泡180天，测试该聚合物保护层浸泡前后的剪切强度，结果列于表1中。
对比例1
采用实施例1的方法和材质，所不同的是，将普通绝缘胶带(购自3M公司商品号为471)贴在焊接连接部表面。
将该组件密封在电解液高温(80℃)浸泡180天，测试该聚合物保护层浸泡前后的剪切强度，结果列于表1中。
表1
  剪切强度(浸泡前，MPa) 剪切强度(浸泡后，Mpa)
实施例1 0.90 0.86
实施例2 0.85 0.77
实施例3 1.40 1.25
实施例4 1.35 1.22
实施例5 1.45 1.35
实施例6 0.95 0.87
实施例7 1.00 0.90
实施例8 1.55 1.38
实施例9 1.54 1.36
实施例10 1.73 1.60
实施例11 1.58 1.40
对比例1 0.75 0.05
由表1数据可知，与贴普通绝缘胶带的组件(对比例1)相比，本申请的锂离子二次电池组件的聚合物保护层在浸泡前后都具有更高的剪切强度，尤其是经电解液高温浸泡后，本申请的聚合物保护层的剪切强度没有明显下降，仍能够保持对焊接连接部的有效保护，提高了电池使用安全性。
以上详细描述了本公开的优选实施方式，但是，本公开并不限于上述实施方式中的具体细节，在本公开的技术构思范围内，可以对本公开的技术方案进行多种简单变型，这些简单变型均属于本公开的保护范围。
另外需要说明的是，在上述具体实施方式中所描述的各个具体技术特征，在不矛盾的情况下，可以通过任何合适的方式进行组合，为了避免不必要的重复，本公开对各种可能的组合方式不再另行说明。
此外，本公开的各种不同的实施方式之间也可以进行任意组合，只要其不违背本公开的思想，其同样应当视为本公开所公开的内容。
在本说明书的描述中，参考术语“一个实施例”、“一些实施例”、“示例”、“具体示例”、或“一些示例”等的描述意指结合该实施例或示例描述的具体特征、结构、材料或者特点包含于本公开的至少一个实施例或示例中。在本说明书中，对上述术语的示意性表述不必须针对的是相同的实施例或示例。而且，描述的具体特征、结构、材料或者特点可以在任一个或多个实施例或示例中以合适的方式结合。此外，在不相互矛盾的情况下，本领域的技术人员可以将本说明书中描述的不同实施例或示例以及不同实施例或示例的特征进行结合和组合。
尽管上面已经示出和描述了本公开的实施例，可以理解的是，上述实施例是示例性的， 不能理解为对本公开的限制，本领域的普通技术人员在本公开的范围内可以对上述实施例进行变化、修改、替换和变型。

Claims (20)

  1. 一种锂离子二次电池组件，其中，所述组件包括极片和极柱，所述极片上伸出有极耳；所述极耳与所述极柱之间具有焊接形成的焊接连接部；所述焊接连接部具有凸起的焊接缺陷；所述焊接连接部的表面上覆盖有聚合物保护层，所述聚合物保护层的厚度大于或等于所述凸起的焊接缺陷的厚度，所述凸起的焊接缺陷嵌入在所述聚合物保护层中。
  2. 根据权利要求1所述的组件，其中，所述凸起的焊接缺陷与所述聚合物保护层完全接触。
  3. 根据权利要求1或2所述的组件，其中，所述聚合物保护层为通过在焊接连接部表面点胶或涂胶形成的聚合物保护层。
  4. 根据权利要求1-3中任一项所述的组件，其中，所述焊接连接部包括第一焊接连接部；
    所述极柱与所述极耳焊接形成的所述第一焊接连接部，或所述极柱伸出的引出片与所述极耳焊接形成的所述第一焊接连接部；
    所述第一焊接连接部包括第一焊接连接部的极耳侧；所述聚合物保护层覆盖在所述第一焊接连接部的极耳侧的表面上。
  5. 根据权利要求1-4中任一项所述的组件，其中，所述组件还包括连接片，所述焊接连接部包括第二焊接连接部和第三焊接连接部；所述连接片的一端与所述极耳焊接形成所述第二焊接连接部；
    所述连接片的另一端与所述极柱焊接形成所述第三焊接连接部，或所述连接片的另一端与所述极柱伸出的引出片焊接形成所述第三焊接连接部；
    所述第三焊接连接部包括第三焊接连接部的连接片侧；
    所述聚合物保护层至少覆盖在所述第二焊接连接部的双侧表面上和所述第三焊接连接部的连接片侧的表面上。
  6. 根据权利要求1-5中任一项所述的组件，其中，所述凸起的焊接缺陷的厚度与所述聚合物保护层的厚度的比例为(0.1～0.9)：1。
  7. 根据权利要求1-6中任一项所述的组件，其中，所述焊接连接部还具有焊缝，所述聚合物保护层具有向所述焊缝中延伸的填充突出部。
  8. 根据权利要求1-7中任一项所述的组件，其中，所述组件还包括绝缘层，所述绝缘层覆盖所述聚合物保护层。
  9. 根据权利要求1-8中任一项所述的组件，其中，所述绝缘层为聚丙烯绝缘层、聚乙烯绝缘层和聚氯乙烯绝缘层中的至少一种。
  10. 根据权利要求1-9中任一项所述的组件，其中，所述聚合物保护层中的聚合物的成型收缩率为1～4％。
  11. 根据权利要求1-10中任一项所述的组件，其中，所述聚合物保护层为热熔胶聚合物保护层、光固化胶聚合物保护层和压敏胶聚合物保护层中的至少一种。
  12. 根据权利要求1-11中任一项所述的组件，其中，所述热熔胶为选自无规聚丙烯热熔胶、乙烯和/或丙烯与含氧烯烃的共聚物、聚苯乙烯、苯乙烯与丁二烯共聚物、异戊二烯与丁二烯共聚物、环氧改性的苯乙烯-丁二烯-苯乙烯共聚物和二聚酸型聚酰胺热熔胶中的至少一种；
    所述光固化胶为紫外光固化胶，所述紫外光固化胶为选自丙烯酸酯类紫外光固化胶、脂环族环氧树脂类紫外光固化胶、脂肪族环氧树脂类紫外光固化胶、芳香族环氧树脂类紫外光固化胶、双酚A环氧改性丙烯酸酯类紫外光固化胶和酚醛环氧改性丙烯酸酯类紫外光固化胶中的至少一种；
    所述压敏胶为选自交联型丙烯酸酯类压敏胶、有机硅类压敏胶、聚氨酯类压敏胶和橡胶类压敏胶中的至少一种。
  13. 一种制备权利要求1-12中任一项所述的锂离子二次电池组件的方法，所述组件包括极片和极柱，所述极片上伸出有极耳，其中，所述方法包括如下步骤：
    S1，将所述极耳焊接在所述极柱上并形成焊接连接部，所述焊接连接部具有凸起的焊接缺陷；
    S2，在所述焊接连接部的表面施用聚合物以成型形成聚合物保护层并使所述凸起的焊 接缺陷嵌入在所述聚合物保护层中，所述聚合物的施用量为使得所述聚合物保护层的厚度大于或等于所述凸起的焊接缺陷的厚度。
  14. 根据权利要求13所述的方法，其中，形成所述聚合物保护层的方法为点胶或涂胶。
  15. 根据权利要求13或14所述的方法，其中，所述焊接连接部包括第一焊接连接部；形成所述第一焊接连接部的方法包括：
    将所述极耳焊接在所述极柱上形成所述第一焊接连接部，或将所述极耳焊接在所述极柱伸出的引出片上形成所述第一焊接连接部；
    所述第一焊接连接部包括第一焊接连接部的极耳侧，在所述第一焊接连接部的极耳侧表面上施用聚合物以成型形成所述聚合物保护层。
  16. 根据权利要求13-15中任一项所述的方法，其中，所述组件还包括连接片，所述焊接连接部包括第二焊接连接部和第三焊接连接部；形成所述第二焊接连接部和所述第三焊接连接部的方法包括：
    将所述连接片的一端焊接在所述极耳上形成所述第二焊接连接部；
    将所述连接片的另一端焊接在所述极柱上形成所述第三焊接连接部，或将所述连接片的另一端焊接在所述极柱伸出的引出片上形成所述第三焊接连接部；
    所述第三焊接连接部包括第三焊接连接部的连接片侧；
    在所述第二焊接连接部的双侧表面上和所述第三焊接连接部的连接片侧表面上施用聚合物以分别成型形成所述聚合物保护层。
  17. 根据权利要求13-16中任一项所述的方法，其中，步骤S2的操作包括如下方式中的至少一种：
    方式a：在所述焊接连接部的表面涂布待固化的热熔胶，并固化形成所述聚合物保护层；
    方式b：在所述焊接连接部的表面涂布待固化的光固化胶，并在光照条件下固化形成所述聚合物保护层；及
    方式c：使压敏胶在施加压力的状态下覆盖所述焊接连接部的表面，然后去除所述压力，形成所述聚合物保护层。
  18. 根据权利要求13-17中任一项所述的方法，其中，所述熔融状态的热熔胶的温度为100～180℃，粘度为1000～10000CP，所述固化的温度为20～25℃，固化时间为0～30s；
    所述光固化胶的粘度为1000～5000CP，所述光照的时间为5～20s；
    所述压力为0.2～0.8MPa。
  19. 根据权利要求13-18中任一项所述的方法，其中，所述方法还包括：在所述聚合物保护层上覆盖绝缘材料并形成绝缘层。
  20. 一种锂离子二次电池，其特征在于，所述电池包括盖板以及权利要求1～12中任一项所述的锂离子二次电池组件或采用权利要求13-19中任一项所述的方法制备得到的锂离子二次电池组件。
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