WO2024092708A1 - 二次电池的壳体、二次电池和电子装置 - Google Patents

二次电池的壳体、二次电池和电子装置 Download PDF

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Publication number
WO2024092708A1
WO2024092708A1 PCT/CN2022/129827 CN2022129827W WO2024092708A1 WO 2024092708 A1 WO2024092708 A1 WO 2024092708A1 CN 2022129827 W CN2022129827 W CN 2022129827W WO 2024092708 A1 WO2024092708 A1 WO 2024092708A1
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Prior art keywords
adhesive layer
secondary battery
electrode assembly
recess
present application
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PCT/CN2022/129827
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English (en)
French (fr)
Inventor
王鑫
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宁德新能源科技有限公司
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Priority to PCT/CN2022/129827 priority Critical patent/WO2024092708A1/zh
Publication of WO2024092708A1 publication Critical patent/WO2024092708A1/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
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/102—Primary casings; Jackets or wrappings characterised by their shape or physical structure
    • H01M50/105—Pouches or flexible bags
    • 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
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/14—Primary casings; Jackets or wrappings for protecting against damage caused by external factors

Definitions

  • the present application relates to the field of electrochemical technology, and in particular to a secondary battery shell, a secondary battery and an electronic device.
  • Secondary batteries such as lithium-ion batteries or sodium-ion batteries, etc.
  • Secondary batteries are widely used in mobile communication tools, electronic digital products, smart wearable products, etc.
  • Existing lithium-ion batteries often have their aluminum-plastic film shells damaged by impact after falling, resulting in lithium-ion battery failure.
  • the current improvement method is usually to increase the thickness of the aluminum-plastic film shell to improve the impact resistance of the aluminum-plastic film shell and thus improve the drop failure of lithium-ion batteries.
  • Experimental and simulation results show that increasing the thickness of the aluminum-plastic film shell can improve the drop failure to a certain extent, but the improvement effect is limited. In addition, increasing the thickness of the aluminum-plastic film shell will also affect the manufacturing quality rate of lithium-ion batteries.
  • the purpose of the present application is to provide a secondary battery housing, a secondary battery and an electronic device to improve the drop performance of the secondary battery.
  • lithium-ion batteries are used as an example of secondary batteries to explain this application, but this is not intended to limit the types of secondary batteries.
  • the specific technical solutions of this application are as follows:
  • the first aspect of the present application provides a shell of a secondary battery, which includes a substrate and an adhesive layer, a first recess for accommodating an electrode assembly is formed on the substrate, and the adhesive layer is arranged on at least part of the inner surface of the first recess; the adhesive layer has a thiol functional group.
  • the adhesive layer is arranged adjacent to at least part of the inner surface of the first recess, and after the electrode assembly is placed in the first recess, when the adhesive layer is connected to the negative electrode collector or the positive electrode collector of the outermost layer of the electrode assembly, the adhesive layer has good adhesion on the negative electrode collector or the positive electrode collector, so that the adhesive layer and the electrode assembly can be bonded.
  • the electrode assembly and the shell of the secondary battery form an integrated structure, which can reduce the risk of the electrode assembly hitting the inner side of the shell of the secondary battery during the fall process; at the same time, after the first recess is formed by punching, the substrate thickness of each corner of the first recess will be much smaller than the substrate thickness before the punching, and after the first recess is formed, by setting the adhesive layer on the inner surface of the first recess, the risk of rupture of each corner of the first recess can be reduced. As a result, the drop performance of the secondary battery is improved.
  • the adhesive force of the adhesive layer is 40N/m to 100N/m, preferably 60N/m to 100N/m.
  • the adhesive force of the adhesive layer is within the above range, and the electrode assembly placed in the first recess and the shell of the secondary battery can be bonded together, so that the electrode assembly and the shell of the secondary battery form a tight integrated structure, and the integrated structure can reduce the risk of the electrode assembly hitting the inner side of the shell of the secondary battery during the fall process; at the same time, after the first recess is formed by punching, the substrate thickness of each corner of the first recess will be much smaller than the substrate thickness before the punching, and after the first recess is formed, the adhesive layer is arranged on the inner surface of the first recess, which can effectively reduce the risk of rupture of each corner of the first recess, thereby improving the drop performance of the secondary battery.
  • the adhesive layer includes a polymer having a thiol functional group.
  • the adhesive layer includes a polymer having a thiol functional group, so that the adhesive layer has good flexibility, solvent resistance, stress relaxation and other properties. And the adhesive layer has adhesion. In this way, after the electrode assembly is placed in the first recess, the electrode assembly and the shell of the secondary battery are bonded together, so that the electrode assembly and the shell of the secondary battery form a tight integrated structure, thereby improving the drop performance of the secondary battery.
  • the weight average molecular weight of the polymer is 1000 to 30000, preferably 15000 to 25000. Regulating the weight average molecular weight of the polymer within the above range is more conducive to the uniform arrangement of the adhesive layer, and is also more conducive to regulating the adhesive force of the adhesive layer within an appropriate range. In this way, the electrode assembly placed in the first recess and the adhesive layer can be more conducive to bonding to form an integrated structure, thereby improving the drop performance of the secondary battery.
  • the adhesive layer includes an adhesive layer emulsion, which includes an acrylic compound, an emulsifier, an initiator, a pH stabilizer and a solvent; based on the mass of the adhesive layer emulsion, the mass percentage of the acrylic compound is 13% to 29%, preferably 24% to 29%, the mass percentage of the emulsifier is 1% to 6%, preferably 5.4% to 6%, the mass percentage of the initiator is 0.1% to 1.6%, preferably 1% to 1.6%, the mass percentage of the pH stabilizer is 0.1% to 2%, preferably 1% to 2%, and the mass percentage of the solvent is 30% to 80%, preferably 60% to 70%.
  • the mass percentage of the acrylic compound is 13% to 29%, preferably 24% to 29%
  • the mass percentage of the emulsifier is 1% to 6%, preferably 5.4% to 6%
  • the mass percentage of the initiator is 0.1% to 1.6%, preferably 1% to 1.6%
  • the mass percentage of the pH stabilizer is 0.1% to 2%,
  • the adhesive layer emulsion is uniformly arranged on the inner surface of the first recess, and an unactivated adhesive layer is formed after drying and curing.
  • the unactivated adhesive layer is transformed from an unactivated state to an activated state after hot pressing treatment, so that the adhesive layer has good adhesion, and the electrode assembly placed in the first recess is bonded to the shell of the secondary battery into an integrated structure.
  • the integrated structure can reduce the risk of the electrode assembly colliding with the inner side of the shell of the secondary battery during falling, thereby improving the drop performance of the secondary battery.
  • the acrylic compound includes polysulfide thermoplastic acrylic acid (C 3 H 4 O 2 S) n , and 10 ⁇ n ⁇ 300;
  • the emulsifier includes N-dodecyldimethylamine;
  • the initiator includes ammonium persulfate and sodium persulfate;
  • the pH stabilizer includes sodium bicarbonate; and
  • the solvent includes deionized water.
  • the selection of polysulfide thermoplastic acrylic acid introduces sulfur-based functional groups into the adhesive layer, so that the adhesive layer has good flexibility, solvent resistance and stress relaxation properties. After the electrode assembly is placed in the first recess, the adhesive layer has good adhesion on the negative electrode collector or the positive electrode collector, so that the adhesive layer can be bonded to the electrode assembly. Thereby, the drop performance of the secondary battery is improved.
  • the acrylic compound further comprises at least one of methacrylic acid, chloroacrylic acid, fluoroacrylic acid or acrylic acid. Further selecting the above-mentioned acrylic compounds in the adhesive layer is more conducive to the bonding of the adhesive layer and the electrode assembly to form an integrated structure, thereby improving the drop performance of the secondary battery.
  • the thickness of the substrate is 70 ⁇ m to 200 ⁇ m, preferably 150 ⁇ m to 200 ⁇ m; the thickness of the adhesive layer is 3 ⁇ m to 40 ⁇ m, preferably 5 ⁇ m to 15 ⁇ m.
  • the second aspect of the present application provides a secondary battery, which includes an electrode assembly and a housing of the secondary battery provided in the first aspect of the present application, wherein the electrode assembly is received in a first recess, and the adhesive layer adheres the electrode assembly. Therefore, the secondary battery of the present application has good drop performance, thermal shock performance, and a high impact test pass rate.
  • the structure of the electrode assembly is a laminate structure.
  • a third aspect of the present application provides an electronic device, which includes the secondary battery provided by the second aspect of the present application.
  • the present application provides a secondary battery shell, a secondary battery and an electronic device, wherein the secondary battery shell includes a substrate and an adhesive layer, a first recess for accommodating an electrode assembly is formed on the substrate, and the adhesive layer is arranged on at least part of the inner surface of the first recess; the adhesive layer has a thiol functional group.
  • first recess for accommodating an electrode assembly on the substrate, and adjacently arranging an adhesive layer on at least part of the inner surface of the first recess, after the electrode assembly is placed in the first recess, when the adhesive layer is connected to the negative electrode current collector or the positive electrode current collector of the outermost layer of the electrode assembly, the adhesive layer has good adhesion on the negative electrode current collector or the positive electrode current collector, so that the adhesive layer and the electrode assembly can be bonded.
  • the electrode assembly and the secondary battery shell form an integrated structure, which can reduce the risk of the electrode assembly impacting the inner side of the secondary battery shell during the falling process; at the same time, after the first recess is formed by punching, the substrate thickness of each corner of the first recess will be much smaller than the substrate thickness before punching, and after the first recess is formed, by arranging the adhesive layer on the inner surface of the first recess, the risk of cracking of each corner of the first recess can be reduced. Thereby, the drop resistance of the secondary battery is improved.
  • FIG1 is a schematic diagram of a cross-sectional structure of a shell of a secondary battery along its thickness direction according to some embodiments of the present application;
  • FIG2 is a schematic diagram of the cross-sectional structure of the shell of the secondary battery in FIG1 along the A-A direction.
  • lithium-ion batteries are used as an example of secondary batteries to explain the present application, but this does not limit the type of secondary batteries.
  • the specific technical solution is as follows:
  • a secondary battery housing which includes a substrate and an adhesive layer, a first recess for accommodating an electrode assembly is formed on the substrate, and the adhesive layer is disposed on at least part of the inner surface of the first recess; the adhesive layer has a thiol functional group, and the adhesive layer containing the thiol functional group has good flexibility, solvent resistance, stress relaxation and other properties.
  • the adhesive layer By forming a first recess for accommodating an electrode assembly on the substrate, and adjacently arranging the adhesive layer on at least part of the inner surface of the first recess, after the electrode assembly is placed in the first recess, when the adhesive layer is connected to the outermost negative electrode current collector or positive electrode current collector of the electrode assembly, the adhesive layer has good adhesion on the negative electrode current collector or positive electrode current collector, so that the adhesive layer and the electrode assembly can be bonded.
  • the electrode assembly and the shell of the secondary battery form an integrated structure, and the integrated structure can reduce the risk of the electrode assembly hitting the inner side of the shell of the secondary battery during the falling process; at the same time, after the first recess is formed by the punching, the substrate thickness of each corner of the first recess will be much smaller than the substrate thickness before the punching, and after the first recess is formed, by setting an adhesive layer on the inner surface of the first recess, the risk of rupture of each corner of the first recess can be reduced.
  • the drop performance of the secondary battery is improved.
  • the integrated structure of the electrode assembly and the first recess can be broken at the same time during the impact, reducing the impact time, making the shell of the secondary battery and the electrode assembly separate faster, reducing the contact time of the fracture, so as to reduce the risk of short circuit, thereby improving the impact test pass rate of the secondary battery.
  • the diaphragm in the electrode assembly is bonded to the adhesive layer, which can inhibit the shrinkage of the diaphragm during the thermal shock test and improve the thermal shock performance of the secondary battery.
  • the prior art also often attaches a film such as styrene-isoprene-styrene block copolymer (SIS) on the surface of the electrode assembly to fix the electrode assembly and the aluminum-plastic film shell, thereby suppressing the impact of the electrode assembly on the aluminum-plastic film shell during the falling process and improving the drop performance of the secondary battery.
  • SIS styrene-isoprene-styrene block copolymer
  • this method requires adding a hot press activation process for the film, and the use of the film makes the secondary battery prone to poor appearance problems such as bubbles and folding.
  • the setting of the shell of the secondary battery of the present application by setting an adhesive layer on the inner surface of the first recess, and forming an integrated structure after the electrode assembly and the shell of the secondary battery are bonded, can well solve the problem of the shell of the secondary battery being torn when the SIS film is introduced into the secondary battery, and the poor appearance problems such as bubbles and folding in the hot press activation process on the basis of improving the drop performance of the secondary battery.
  • the present application does not impose any particular restrictions on the characterization method of "thiol functional group", as long as the purpose of the present application can be achieved.
  • the thiol functional group can be characterized by infrared spectroscopy, specifically, in the infrared spectrum, there is an absorption peak that characterizes the thiol functional group in the wave number range of 2550 cm -1 to 2590 cm -1 .
  • the adhesive layer is disposed on at least part of the inner surface of the first recess
  • the adhesive layer is disposed on part of the inner surface of the first recess.
  • the adhesive layer is disposed on the entire surface of the first recess.
  • the adhesive layer is disposed on the entire surface of the first recess, which is more conducive to industrial production, and the bonding effect between the electrode assembly and the adhesive layer is better, which is more conducive to improving the drop performance of the secondary battery.
  • the substrate is an aluminum-plastic film
  • the aluminum-plastic film includes a protective layer, a heat-sealing layer, and an intermediate layer between the protective layer and the heat-sealing layer.
  • a first recess is formed on the substrate, the outer surface of the first recess is the protective layer, the inner surface of the first recess is the heat-sealing layer, and the adhesive layer is arranged on the inner surface of the first recess, which can also be understood as the adhesive layer and the heat-sealing layer being arranged adjacent to each other.
  • the present application does not particularly limit the materials of the protective layer, the heat-sealing layer, and the intermediate layer, as long as the purpose of the present application can be achieved.
  • the material of the protective layer is a polyester or nylon material with a high melting point (melting point of 160°C to 260°C), and the material of the protective layer has strong mechanical properties, which can prevent damage to the lithium-ion battery by external forces and protect the lithium-ion battery.
  • the material of the heat-sealing layer is polyethylene or polypropylene, which can encapsulate the lithium-ion battery.
  • the material of the middle layer is any one of aluminum foil, steel foil or titanium foil, which can prevent the infiltration of water vapor outside the lithium-ion battery and prevent the leakage of internal electrolyte.
  • the adhesive force of the adhesive layer is 40N/m to 100N/m, preferably 60N/m to 100N/m.
  • the adhesive force can be 40N/m, 50N/m, 60N/m, 70N/m, 80N/m, 90N/m, 100N/m or any value between any two of the above numerical ranges.
  • the adhesive force of the adhesive layer is within the above range, and the electrode assembly placed in the first recess and the shell of the secondary battery can be bonded together, so that the electrode assembly and the shell of the secondary battery form a tight integrated structure, and the integrated structure can reduce the risk of the electrode assembly hitting the inner side of the shell of the secondary battery during the fall process; at the same time, after the first recess is formed by the punching pit, the substrate thickness of each corner of the first recess will be much smaller than the substrate thickness before the punching pit, and after the first recess is formed, the adhesive layer is arranged on the inner surface of the first recess, which can reduce the risk of rupture of each corner of the first recess, thereby improving the drop performance of the secondary battery.
  • the adhesive force of the adhesive layer is within the above-mentioned preferred range, which is more conducive to further improving the drop performance of the secondary battery.
  • the adhesive layer includes a polymer, and the polymer has a thiol functional group.
  • the adhesive layer includes a polymer having a thiol functional group, so that the adhesive layer has good flexibility, solvent resistance and stress relaxation properties. And the adhesive layer has adhesive force.
  • the electrode assembly and the shell of the secondary battery are bonded together, so that the electrode assembly and the shell of the secondary battery form a tight integrated structure, and the integrated structure can reduce the risk of the electrode assembly hitting the inner side of the shell of the secondary battery during the fall process;
  • the substrate thickness of each corner of the first recess will be much smaller than the substrate thickness before punching, and after the first recess is formed, the adhesive layer is arranged on the inner surface of the first recess, which can reduce the risk of rupture of each corner of the first recess, thereby improving the drop performance of the secondary battery.
  • the weight average molecular weight of the polymer is 1000 to 30000, preferably 15000 to 25000.
  • the weight average molecular weight can be 1000, 5000, 10000, 15000, 20000, 25000, 30000 or any value between any two of the above numerical ranges.
  • Regulating the weight average molecular weight of the polymer within the above range is more conducive to the uniform arrangement of the adhesive layer, and is also more conducive to regulating the adhesion of the adhesive layer within an appropriate range. In this way, the electrode assembly placed in the first recess can be bonded to the adhesive layer to form an integrated structure, thereby improving the drop performance of the secondary battery.
  • Regulating the weight average molecular weight of the polymer within the above preferred range is more conducive to further improving the drop performance of the secondary battery.
  • the present application does not particularly limit the method for regulating the weight average molecular weight of the polymer, and those skilled in the art may select a method known in the art to regulate the weight average molecular weight of the polymer, as long as the purpose of the present application can be achieved.
  • the weight average molecular weight of the polymer may be regulated by adjusting the value of n in the polysulfide thermoplastic acrylic acid (C 3 H 4 O 2 S) n , or by adjusting the ratio of the acrylic compound, emulsifier, initiator, or the polymerization temperature.
  • the adhesive layer includes an adhesive layer emulsion, which includes an acrylic compound, an emulsifier, an initiator, a pH stabilizer and a solvent; based on the mass of the adhesive layer emulsion, the mass percentage of the acrylic compound is 13% to 29%, preferably 24% to 29%, the mass percentage of the emulsifier is 1% to 6%, preferably 5.4% to 6%, the mass percentage of the initiator is 0.1% to 1.6%, preferably 1% to 1.6%, the mass percentage of the pH stabilizer is 0.1% to 2%, preferably 1% to 2%, and the mass percentage of the solvent is 30% to 80%, preferably 60% to 70%.
  • the mass percentage of the acrylic compound is 13% to 29%, preferably 24% to 29%
  • the mass percentage of the emulsifier is 1% to 6%, preferably 5.4% to 6%
  • the mass percentage of the initiator is 0.1% to 1.6%, preferably 1% to 1.6%
  • the mass percentage of the pH stabilizer is 0.1% to 2%,
  • the mass percentage of the acrylic compound is 13%, 15%, 17%, 19%, 21%, 24%, 25%, 27%, 29% or any value between any two of the above numerical ranges
  • the mass percentage of the emulsifier is 1%, 2%, 3%, 4%, 5%, 5.4%, 6% or any value between any two of the above numerical ranges
  • the mass percentage of the initiator is 0.1%, 0.4%, 0.7%, 1.0%, 1.3%, 1.6% or any value between any two of the above numerical ranges
  • the mass percentage of the pH stabilizer is 0.1%, 0.4%, 0.7%, 1.0%, 1.3%, 1.6%, 2% or any value between any two of the above numerical ranges
  • the mass percentage of the solvent is 30%, 40%, 50%, 60%, 62%, 67%, 70%, 80% or any value between any two of the above numerical ranges.
  • the acrylic compound, emulsifier, initiator, pH stabilizer and solvent in the above mass percentage range it is easier to prepare an adhesive layer emulsion with uniform distribution of each component, and the adhesive layer emulsion is evenly arranged on the inner surface of the first concave portion, and after drying and curing, an adhesive layer in an unactivated state is formed, and the unactivated adhesive layer is transformed from an unactivated state to an activated state after hot pressing, so that the adhesive layer has good adhesion, and the electrode assembly placed in the first concave portion is bonded to the shell of the secondary battery into an integrated structure, and the integrated structure can reduce the risk of the electrode assembly hitting the inner side of the shell of the secondary battery during the falling process, thereby improving the drop performance of the secondary battery.
  • Selecting the acrylic compound, emulsifier, initiator, pH stabilizer and solvent in the above preferred mass percentage range is more conducive to improving the drop performance of the secondary battery.
  • the adhesive layer emulsion is uniformly arranged on the inner surface of the first recess, and an adhesive layer in an unactivated state is formed after drying and curing.
  • the adhesive layer in the unactivated state is transformed from an unactivated state to an activated state after being subjected to a hot pressing treatment.
  • the adhesive layer in the unactivated state has no adhesive force
  • the adhesive layer in the activated state has an adhesive force.
  • the adhesive layer refers to an adhesive layer that is in an activated state and has an adhesive force after being subjected to a hot pressing treatment.
  • the temperature of the above-mentioned "hot pressing treatment” is 70°C to 80°C, and the pressure is 1.0MPa to 1.2MPa.
  • the present application does not particularly limit the process conditions of the above-mentioned “drying", as long as the purpose of the present application can be achieved.
  • the acrylic compound includes polysulfide thermoplastic acrylic acid (C 3 H 4 O 2 S) n , and 10 ⁇ n ⁇ 300;
  • the emulsifier includes N-dodecyldimethylamine;
  • the initiator includes ammonium persulfate or sodium persulfate, etc.;
  • the pH stabilizer includes sodium bicarbonate or potassium bicarbonate; and
  • the solvent includes deionized water.
  • the selection of polysulfide thermoplastic acrylic acid introduces sulfur-based functional groups into the adhesive layer, so that the adhesive layer has good flexibility, solvent resistance and stress relaxation properties.
  • the adhesive layer After the electrode assembly is placed in the first recess, when the adhesive layer is connected to the outermost negative electrode current collector or positive electrode current collector of the electrode assembly, the adhesive layer has good adhesion on the negative electrode current collector or the positive electrode current collector, so that the adhesive layer and the electrode assembly can be bonded.
  • the electrode assembly and the shell of the secondary battery form an integrated structure, which can reduce the risk of the electrode assembly hitting the inner side of the shell of the secondary battery during the falling process, thereby improving the drop performance of the secondary battery.
  • 50 ⁇ n ⁇ 250 In another embodiment of the present application, 100 ⁇ n ⁇ 200.
  • the acrylic compound further includes at least one of methacrylic acid, chloroacrylic acid, fluoroacrylic acid or acrylic acid (molecular formula: C 3 H 4 O 2 ). Further selecting the above-mentioned acrylic compounds in the adhesive layer is more conducive to the bonding of the adhesive layer and the electrode assembly to form an integrated structure, so that the risk of the electrode assembly impacting the inner side of the secondary battery shell during the falling process is reduced, thereby improving the falling performance of the secondary battery.
  • the adhesive layer emulsion can be prepared by the following preparation method: acrylic compound, emulsifier, initiator, pH stabilizer and solvent are uniformly mixed according to the mass percentage of the present application to prepare the adhesive layer emulsion.
  • the thickness of the substrate is 70 ⁇ m to 200 ⁇ m, preferably 150 ⁇ m to 200 ⁇ m; the thickness of the adhesive layer is 3 ⁇ m to 40 ⁇ m, preferably 5 ⁇ m to 15 ⁇ m.
  • the thickness of the substrate is 70 ⁇ m, 80 ⁇ m, 90 ⁇ m, 100 ⁇ m, 110 ⁇ m, 120 ⁇ m, 130 ⁇ m, 140 ⁇ m, 150 ⁇ m, 200 ⁇ m or any value between any two of the above numerical ranges
  • the thickness of the adhesive layer is 3 ⁇ m, 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m or any value between any two of the above numerical ranges.
  • the shell of the secondary battery has a thickness that reduces the impact pass rate, so that the secondary battery has a smaller volume, thereby making the secondary battery have a higher energy density, and improving the drop performance of the secondary battery. Controlling the thickness of the substrate and the thickness of the adhesive layer within the above preferred range is more conducive to further improving the drop performance of the secondary battery.
  • the present application has no particular limitation on the type of the secondary battery shell, as long as the purpose of the present application can be achieved.
  • the secondary battery shell is an integrated structure, or the secondary battery shell is a separate structure including a first packaging shell and a second packaging shell.
  • the shell of the secondary battery is an integrated structure, and its preparation method includes the following steps: on the substrate 10 as shown in (a) in Figure 1 and (a) in Figure 2, a first recess 11 and an air bag 12 as shown in (b) in Figure 1 and (b) in Figure 2 are formed; on the inner surface of the first recess 11, an unactivated adhesive layer 13 as shown in (c) in Figure 1 and (c) in Figure 2 is adjacently arranged.
  • the first recess 11 is used to accommodate the electrode assembly, and the electrode assembly is subsequently placed in the first recess 11. After hot pressing, the unactivated adhesive layer 13 is transformed from an unactivated state to an activated state, so that the adhesive layer 13 and the electrode assembly are bonded into an integrated structure.
  • the present application has no particular restrictions on the process of setting the adhesive layer adjacent to the inner surface of the first concave portion, as long as the purpose of the present application can be achieved.
  • the process of setting the adhesive layer adjacent to the inner surface of the first concave portion is selected from any one of gravure printing, wire rod coating, blade coating and curtain coating.
  • the second aspect of the present application provides a secondary battery, which includes an electrode assembly and a shell of the secondary battery provided in the first aspect of the present application, the shell of the secondary battery includes a first recess and a sealing portion connected to the first recess, the electrode assembly is accommodated in the first recess, and the adhesive layer is arranged on at least part of the inner surface of the first recess.
  • the electrode assembly and the shell of the secondary battery form an integrated structure, and the integrated structure can reduce the risk of the electrode assembly hitting the inner side of the shell of the secondary battery during the falling process; at the same time, after the first recess is formed by punching, the substrate thickness of each corner of the first recess will be much smaller than the substrate thickness before the punching, and after the first recess is formed, the adhesive layer is arranged on the inner surface of the first recess, which can reduce the risk of rupture of each corner of the first recess, thereby improving the drop performance of the secondary battery.
  • the integrated structure of the electrode assembly and the first recess can be broken at the same time during the impact, which reduces the impact time, separates the shell of the secondary battery and the electrode assembly more quickly, and reduces the contact time of the fracture to reduce the risk of short circuit, thereby improving the impact test pass rate of the secondary battery.
  • the diaphragm in the electrode assembly is bonded to the adhesive layer, which can inhibit the shrinkage of the diaphragm during the thermal shock test and improve the thermal shock performance of the secondary battery.
  • the present application has no particular limitation on the structure of the electrode assembly, as long as the purpose of the present application can be achieved.
  • the structure of the electrode assembly is a winding structure or a laminated structure.
  • the structure of the electrode assembly is a laminated structure.
  • the structure of the electrode assembly of the laminated structure is more conducive to bonding with various parts of the adhesive layer on the inner surface of the first recess, and is more conducive to improving the bonding force between the electrode assembly and the adhesive layer, so that the electrode assembly and the housing of the secondary battery form a more compact integrated structure, thereby being more conducive to improving the drop performance of the secondary battery.
  • the electrode assembly of the present application includes a positive electrode sheet, a separator and a negative electrode sheet.
  • the separator is located between the positive electrode sheet and the negative electrode sheet, separating the positive electrode sheet and the negative electrode sheet to prevent internal short circuit of the secondary battery.
  • the separator allows electrolyte ions to pass freely to complete the electrochemical charge and discharge process.
  • the number of separators, positive electrode sheets and negative electrode sheets in the electrode assembly is not particularly limited, as long as the purpose of the present application can be achieved.
  • the present application does not particularly limit the types of positive electrode sheets, separators, and negative electrode sheets. Those skilled in the art can choose according to actual needs, as long as the purpose of the present application can be achieved.
  • the positive electrode sheet includes a positive electrode active material layer and a positive electrode current collector, the positive electrode active material layer is arranged on one surface or two surfaces of the positive electrode current collector along its own thickness direction, and the positive electrode active material layer includes a positive electrode active material.
  • the negative electrode sheet includes a negative electrode active material layer and a negative electrode current collector, the negative electrode active material is arranged on one surface or two surfaces of the negative electrode current collector along its own thickness direction, and the negative electrode active material layer includes a negative electrode active material.
  • the present application does not particularly limit the positive electrode active material, the positive electrode current collector, the negative electrode active material, and the negative electrode current collector. Those skilled in the art can choose according to actual needs, as long as the purpose of the present application can be achieved.
  • the secondary battery of the present application also includes an electrolyte.
  • the present application has no special restrictions on the electrolyte, and those skilled in the art can select it according to actual needs as long as the purpose of the present application can be achieved.
  • the secondary battery of the present application is not particularly limited, and may include a device that generates an electrochemical reaction.
  • the secondary battery may include, but is not limited to: a lithium metal secondary battery, a lithium ion secondary battery (lithium ion battery), a sodium ion secondary battery, a lithium polymer secondary battery, and a lithium ion polymer secondary battery.
  • the present application does not particularly limit the preparation method of the secondary battery, and a preparation method known in the art can be selected as long as the purpose of the present application can be achieved.
  • the shell of the secondary battery is an integrated structure, and the preparation method of the secondary battery includes the following steps: on the substrate 10 as shown in (a) in FIG. 1 and (a) in FIG. 2, a first recess 11 and an air bag 12 as shown in (b) in FIG. 1 and (b) in FIG. 2 are formed; an adhesive layer 13 in an unactivated state as shown in (c) in FIG. 1 and (c) in FIG.
  • the electrode assembly is placed in the first recess 11 as shown in (c) in FIG. 1, so that the outer surface of the electrode assembly is adjacent to the adhesive layer 13, and the shell of the secondary battery as shown in (c) in FIG. 1 is folded in half and then packaged to form a receiving portion and a sealing portion; then the packaged secondary battery is subjected to a hot pressing treatment to bond the electrode assembly to the shell of the secondary battery to form an integrated structure; thereafter, an electrolyte is injected and formed to obtain a secondary battery.
  • the present application has no particular restrictions on the preparation method of the electrode assembly, as long as the purpose of the present application can be achieved.
  • the positive electrode sheet, the separator and the negative electrode sheet are stacked in sequence, and they are wound, folded, etc. as needed to obtain an electrode assembly with a wound structure.
  • the positive electrode sheet, the separator and the negative electrode sheet are stacked in sequence, and the four corners of the entire stacked structure are fixed with tape to obtain an electrode assembly with a stacked structure.
  • the third aspect of the present application provides an electronic device, which includes the secondary battery provided by the second aspect of the present application. Therefore, the beneficial effects of the secondary battery provided by the second aspect can be obtained.
  • the electronic device of the present application is not particularly limited, and it can be an electronic device known in the prior art.
  • the electronic device can include, but is not limited to: a laptop computer, a pen-input computer, a mobile computer, an electronic book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large household battery, and a lithium-ion capacitor.
  • the housing is fixed on one side of the tensile machine, and the electrode assembly is fixed on the other side;
  • Lithium-ion battery 1.0-meter drop pass rate test (1) Lithium-ion battery 1.0-meter drop pass rate test:
  • Lithium-ion battery failure judgment criteria :
  • the lithium-ion battery can pass the functional inspection (such as measuring voltage and internal resistance);
  • Test In a test environment of 20 ⁇ 5°C, place the lithium-ion battery to be tested as a sample on the test table, and place a round bar with a diameter of ⁇ 15.8 ⁇ 0.1mm and a length of at least 6cm at the center of the wide surface of the sample.
  • the longitudinal axis of the sample is parallel to the surface of the test table and perpendicular to the longitudinal axis of the round bar.
  • Use a 9.1 ⁇ 0.1kg weight to drop vertically from a height of 610 ⁇ 25mm and fall on the intersection of the round bar and the sample.
  • Judgment criteria Pass if there is no fire, explosion or smoke.
  • the temperature sensing wire is attached to the head and tail area of the lithium-ion battery and one surface of its own thickness, and the insulating yellow glue is attached to the bottom plate, and the other surface of the lithium-ion battery's own thickness is attached to the bottom plate, and the head and tail of the lithium-ion battery are semi-fixed with the insulating yellow glue;
  • Test Place the lithium-ion battery to be tested as a sample horizontally in a high and low temperature box and heat it to 132 ⁇ 2°C at a rate of 5 ⁇ 2°C and keep it for 60 minutes;
  • Judgment standard Pass if there is no fire or explosion.
  • dioxolane and dimethyl ether were mixed at a mass ratio of 1:1 to obtain an organic solvent, and then lithium salt lithium bistrifluoromethanesulfonyl imide was added to the organic solvent to dissolve and mix evenly to obtain an electrolyte with a lithium salt concentration of 1.0 mol/L.
  • the negative electrode active material graphite, the negative electrode conductive agent graphite, the negative electrode conductive agent carbon black and the negative electrode binder sodium carboxymethyl carbonate acid are mixed in a mass ratio of 95:1:2:2, and the obtained mixture is evenly dispersed in distilled water, and stirred evenly under the action of a vacuum mixer to obtain a negative electrode slurry, wherein the solid content of the negative electrode slurry is 75wt%.
  • the negative electrode slurry is evenly coated on one surface of a negative electrode current collector copper foil with a thickness of 12 ⁇ m, and the copper foil is dried at 85°C to obtain a negative electrode sheet with a coating thickness of 75 ⁇ m and a single-sided coating of a negative electrode active material layer.
  • the positive electrode active material lithium iron phosphate, the positive electrode conductive agent conductive carbon black, and the positive electrode binder polyvinylidene fluoride are mixed in a mass ratio of 97.5:1.0:1.5, N-methylpyrrolidone is added, and the mixture is stirred evenly under the action of a vacuum mixer to obtain a positive electrode slurry, wherein the solid content of the positive electrode slurry is 75wt%.
  • the positive electrode slurry is evenly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 10 ⁇ m, and the aluminum foil is dried at 90°C to obtain a positive electrode sheet coated with a positive electrode active material layer on one side.
  • a polyethylene film with a thickness of 11 ⁇ m (provided by Celgard) was used.
  • a separator is placed between the positive electrode sheet and the negative electrode sheet prepared as above, and the four corners are fixed after stacking to form an electrode assembly with a laminated structure, wherein the number of layers of the positive electrode sheet and the negative electrode sheet are 16 and 17 respectively, and the number of layers of the separator is 32.
  • a base aluminum-plastic film with a thickness of 90 ⁇ m was punched to form a first concave portion as shown in FIG. 1 (b), and an adhesive layer emulsion was evenly disposed on the inner surface of the first concave portion by a gravure printing process, and dried and solidified for 2 seconds to form an unactivated adhesive layer with a thickness of 10 ⁇ m.
  • the adhesive layer emulsion includes polyacrylic acid compounds: polysulfide thermoplastic acrylic acid (C 3 H 4 O 2 S) n (48 ⁇ n ⁇ 241), methacrylic acid, fluoroacrylic acid and acrylic acid, an emulsifier N-dodecyldimethylamine, an initiator sodium persulfate, a pH stabilizer sodium bicarbonate, and a solvent deionized water.
  • polyacrylic acid compounds polysulfide thermoplastic acrylic acid (C 3 H 4 O 2 S) n (48 ⁇ n ⁇ 241), methacrylic acid, fluoroacrylic acid and acrylic acid, an emulsifier N-dodecyldimethylamine, an initiator sodium persulfate, a pH stabilizer sodium bicarbonate, and a solvent deionized water.
  • the mass percentage of (C 3 H 4 O 2 S) n is 10%
  • the mass percentage of methacrylic acid is 8%
  • the mass percentage of fluoroacrylic acid is 4%
  • the mass percentage of acrylic acid is 2%
  • the mass percentage of N-dodecyldimethylamine is 5.4%
  • the mass percentage of sodium persulfate is 1.6%
  • the mass percentage of sodium bicarbonate is 2%
  • the mass percentage of deionized water is 67%.
  • the electrode assembly is placed in the first concave portion, and the shell of the secondary battery shown in (c) of FIG1 is folded in half and packaged to obtain a secondary battery.
  • the packaged secondary battery is subjected to a hot pressing treatment at 70°C and 1MPa, and the inactivated adhesive layer is transformed into an activated state, and the various substances in the adhesive layer are polymerized to form a polymer with a weight average molecular weight of 20,000. After that, an electrolyte is injected and formed to obtain a final secondary battery.
  • Example 1-1 Except for adjusting the relevant preparation parameters according to Table 1, the rest is the same as Example 1-1.
  • Example 1-1 Except for adjusting the specifications of the negative electrode sheet in ⁇ Preparation of Negative Electrode Sheet> to 41mm ⁇ 440mm, adjusting the specifications of the positive electrode sheet in ⁇ Preparation of Positive Electrode Sheet> to 38mm ⁇ 430mm, and adjusting the structure of the electrode assembly in ⁇ Preparation of Lithium-ion Battery> to a winding structure, the rest is the same as Example 1-1.
  • the preparation method of the electrode assembly with a wound structure is as follows: stack the positive electrode sheet, negative electrode sheet and separator prepared above in order, place the separator between the positive electrode sheet and the negative electrode sheet to play an isolating role, and wind to obtain the electrode assembly.
  • Example 1-1 Except for adjusting the relevant preparation parameters according to Table 2, the rest is the same as Example 1-1.
  • Example 1-1 Except for adjusting the relevant preparation parameters according to Table 3, the rest is the same as Example 1-1.
  • Example 1-1 Except that no adhesive layer was provided in ⁇ Preparation of lithium-ion battery>, the rest was the same as Example 1-1.
  • the component of the adhesive layer is methacrylic acid-fluoroacrylic acid-acrylic acid copolymer (weight average molecular weight 20,000, mass ratio of methacrylic acid, fluoroacrylic acid and acrylic acid is 1:1:1), the rest is the same as Example 1-1.
  • Examples 1-1 to 1-9 use a lithium-ion battery in which an adhesive layer is provided on the inner surface of the first recess formed on the substrate, and the adhesive layer has a thiol functional group, and has better drop performance, better thermal shock performance, and a higher impact pass rate; lithium-ion batteries in which the weight average molecular weight of the polymer in the adhesive layer is within the scope of the present application have further drop performance, better thermal shock performance, and a higher impact pass rate.
  • a lithium-ion battery in which the adhesive layer of the present application is not provided on the inner surface of the first recess is used, and its drop performance, thermal shock performance, and impact pass rate are not improved.
  • Comparative Example 2 a lithium-ion battery in which the adhesive layer does not have a thiol functional group is used, and its drop performance, thermal shock performance, and impact pass rate are not improved.
  • the structure of the electrode assembly usually also affects the drop performance of the lithium-ion battery. It can be seen from Examples 1-1 and 1-10 that the lithium-ion battery using the electrode assembly structure within the scope of the present application has good drop performance, good thermal shock performance and a high impact pass rate.
  • the thickness of the adhesive layer usually also affects the drop performance, impact pass rate and thermal shock performance of the lithium-ion battery. It can be seen from Examples 1-1, 2-1 to 2-8 that the lithium-ion battery with the thickness of the adhesive layer within the range of the present application has good drop performance, good thermal shock performance and a high impact pass rate.
  • the thickness of the substrate usually also affects the drop performance, impact pass rate and thermal shock performance of the lithium-ion battery. It can be seen from Examples 1-1, 2-9 to 2-11 that the lithium-ion battery with a substrate thickness within the range of the present application has good drop performance, good thermal shock performance and a high impact pass rate.
  • the mass percentage of acrylic compound, emulsifier, initiator, pH stabilizer and solvent in the adhesive layer emulsion usually also affects the drop performance, impact pass rate and thermal shock performance of the lithium ion battery. It can be seen from Example 1-1, Example 3-1 and Example 3-3 that the lithium ion battery with the mass percentage of acrylic compound, emulsifier, initiator, pH stabilizer and solvent in the adhesive layer emulsion within the range of the present application has good drop performance, good thermal shock performance and high impact pass rate.
  • the type of acrylic compound in the adhesive layer emulsion usually also affects the drop performance, impact pass rate and thermal shock performance of the lithium ion battery. It can be seen from Examples 1-1, 3-4 and 3-5 that the lithium ion battery with the type of acrylic compound in the adhesive layer emulsion within the scope of the present application has good drop performance, good thermal shock performance and a high impact pass rate.

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Abstract

本申请提供了一种二次电池的壳体、二次电池和电子装置，该壳体包括基体及粘接层，在基体上形成用以收容电极组件的第一凹部，粘接层设置于第一凹部的至少部分内表面上；粘接层具有巯基官能团。通过在基体上形成用以收容电极组件的第一凹部，在第一凹部的至少部分内表面上邻接设置粘接层，使电极组件置于第一凹部后，粘接层经热压处理处于激活状态，粘接层的粘性被激活，粘接力得到显著提高，粘接层与电极组件的外周粘接，使电极组件与壳体形成一体化结构。电极组件与壳体的一体化结构，能够降低电极组件在跌落过程中对壳体内侧产生撞击的风险，从而提高二次电池的跌落性能。

Description

二次电池的壳体、二次电池和电子装置 技术领域
本申请涉及电化学技术领域，特别是涉及一种二次电池的壳体、二次电池和电子装置。
背景技术
二次电池(例如锂离子电池或钠离子电池等)广泛应用于移动通信工具、电子数码产品、智能穿戴产品等领域。现有的锂离子电池常常在跌落后会出现铝塑膜壳体各边因撞击破损，从而导致锂离子电池失效的现象。
目前的改进方式通常是增加铝塑膜壳体的厚度来提升铝塑膜壳体的抗撞击能力从而改善锂离子电池的跌落失效。实验及仿真结果显示，铝塑膜壳体厚度的提升能在一定程度上改善跌落失效，但改善效果有限。并且，铝塑膜壳体厚度的提升，还将影响锂离子电池的制成优率。
因此，寻找一种新的提高锂离子电池跌落性能的技术，成为本领域技术人员亟待解决的问题。
发明内容
本申请的目的在于提供一种二次电池的壳体、二次电池和电子装置，以提高二次电池的跌落性能。
需要说明的是，本申请的发明内容中，以锂离子电池作为二次电池的例子来解释本申请，但并不作为对二次电池种类的限定。本申请的具体技术方案如下：
本申请第一方面提供了一种二次电池的壳体，其包括基体及粘接层，在基体上形成用以收容电极组件的第一凹部，粘接层设置于第一凹部的至少部分内表面上；粘接层具有巯基官能团。通过在基体上形成用以收容电极组件的第一凹部，在第一凹部的至少部分内表面上邻接设置粘接层，将电极组件置入第一凹部后，粘接层与电极组件最外层的负极集流体或正极集流体连接时，粘接层在负极集流体或正极集流体上具有良好的附着力，使得粘接层与电极组件能够粘接。这样，电极组件与二次电池的壳体形成一体化结构，能够降低电极组件在跌落过程中对二次电池的壳体内侧产生撞击的风险；同时，冲坑形成第一凹部后，第一凹部各角位的基体厚度会远小于冲坑前的基体厚度，而形成第一凹部后，通过在第一凹部的内表面设置粘接层，能够降低第一凹部各角位破裂的风险。由此，二次电池的跌落性能得以提高。
在本申请的一种实施方案中，粘接层的粘接力为40N/m至100N/m，优选为60N/m至100N/m。粘接层的粘接力处于上述范围内，能够将置于第一凹部内的电极组件和二次电池的壳体粘接在一起，使电极组件与二次电池的壳体形成紧密的一体化结构，一体化结构能够降低电极组件在跌落过程中对二次电池的壳体内侧产生撞击的风险；同时，冲坑形成第一凹部后，第一凹部各角位的基体厚度会远小于冲坑前的基体厚度，而形成第一凹部后，在第一凹部的内表面设置粘接层，能够有效降低第一凹部各角位破裂的风险，从而提高二次电池的跌落性能。
在本申请的一种实施方案中，粘接层包括聚合物，聚合物具有巯基官能团。粘接层包括具有巯基官能团的聚合物，使粘接层具有良好的柔韧性、耐溶剂性及应力松弛等性能。且粘接层具有粘接力。这样，将电极组件置入第一凹部后，电极组件和二次电池的壳体粘接在一起，使电极组件与二次电池的壳体形成紧密的一体化结构，从而提高二次电池的跌落性能。
在本申请的一种实施方案中，聚合物的重均分子量为1000至30000，优选为15000至25000。将聚合物的重均分子量调控在上述范围内，更利于粘接层的均匀设置，也更利于使粘接层的粘接力调控在适当范围内。这样，置于第一凹部的电极组件与粘接层之间能够更利于粘接形成一体化结构，从而提高二次电池的跌落性能。
在本申请的一种实施方案中，粘接层包括粘接层乳液，粘接层乳液包括丙烯酸类化合物、乳化剂、引发剂、pH值稳定剂和溶剂；基于粘接层乳液的质量，丙烯酸类化合物的质量百分含量为13％至29％，优选为24％至29％，乳化剂的质量百分含量为1％至6％，优选为5.4％至6％，引发剂的质量百分含量为0.1％至1.6％，优选为1％至1.6％，pH值稳定剂的质量百分含量为0.1％至2％，优选为1％至2％，溶剂的质量百分含量为30％至80％，优选为60％至70％。选用上述质量百分含量范围的丙烯酸类化合物、乳化剂、引发剂、pH值稳定剂和溶剂，更容易制备得到各组分均匀分布的粘接层乳液，粘接层乳液均匀设置于第一凹部的内表面上，经烘干固化后形成未激活状态的粘接层，未激活状态的粘接层经热压处理后从未激活状态转变成激活状态，使粘接层具有良好的粘接力，将置入第一凹部的电极组件与二次电池的壳体粘接成一体化结构，一体化结构能够降低电极组件在跌落过程中对二次电池的壳体内侧产生撞击的风险，从而提高二次电池的跌落性能。
在本申请的一种实施方案中，丙烯酸类化合物包括聚硫化热塑性丙烯酸(C 3H 4O 2S) n，且10≤n≤300；乳化剂包括N-十二烷基二甲胺；引发剂包括过硫酸铵、过硫酸钠；pH值 稳定剂包括碳酸氢钠；溶剂包括去离子水。上述种类的聚丙烯酸类化合物、乳化剂、引发剂、pH值稳定剂和溶剂的选择，更容易制备得到均匀的粘接层乳液，形成均匀各组分均匀分布的粘接层。聚硫化热塑性丙烯酸的选用，使粘接层中引入硫基官能团，从而使粘接层具有良好的柔韧性、耐溶剂性及应力松弛等性能。将电极组件置入第一凹部后，粘接层在负极集流体或正极集流体上具有良好的附着力，使得粘接层与电极组件能够粘接。从而提高二次电池的跌落性能。
在本申请的一种实施方案中，丙烯酸类化合物还包括甲基丙烯酸、氯代丙烯酸、氟代丙烯酸或丙烯酸中的至少一种。在粘接层中进一步选用上述种类的丙烯酸类化合物，更利于粘接层与电极组件粘接形成一体化结构，从而提高二次电池的跌落性能。
在本申请的一种实施方案中，基体的厚度为70μm至200μm，优选为150μm至200μm；粘接层的厚度为3μm至40μm，优选为5μm至15μm。将基体的厚度和粘接层的厚度调控在上述范围内，能够使二次电池具有较高的能量密度的情况下，提高二次电池的跌落性能。
本申请第二方面提供了一种二次电池，其包括电极组件和本申请第一方面提供的二次电池的壳体，电极组件收容于第一凹部，粘接层粘接电极组件。因此，本申请的二次电池具有良好的跌落性能、热冲击性能和较高的撞击测试通过率。
在本申请的一种实施方案中，电极组件的结构为叠片结构。
本申请第三方面提供了一种电子装置，其包括本申请第二方面提供的二次电池。
本申请提供了一种二次电池的壳体、二次电池和电子装置，其中，二次电池的壳体包括基体及粘接层，在基体上形成用以收容电极组件的第一凹部，粘接层设置于第一凹部的至少部分内表面上；粘接层具有巯基官能团。通过在基体上形成用以收容电极组件的第一凹部，在第一凹部的至少部分内表面上邻接设置粘接层，将电极组件置入第一凹部后，粘接层与电极组件最外层的负极集流体或正极集流体连接时，粘接层在负极集流体或正极集流体上具有良好的附着力，使得粘接层与电极组件能够粘接。这样，电极组件与二次电池的壳体形成一体化结构，能够降低电极组件在跌落过程中对二次电池的壳体内侧产生撞击的风险；同时，冲坑形成第一凹部后，第一凹部各角位的基体厚度会远小于冲坑前的基体厚度，而形成第一凹部后，通过在第一凹部的内表面设置粘接层，能够降低第一凹部各角位破裂的风险。由此，二次电池的跌落性能得以提高。
附图说明
为了更清楚地说明本申请实施例和现有技术的技术方案，下面对实施例和现有技术中 所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，还可以根据这些附图获得其他的附图。
图1为本申请一些实施例的二次电池的壳体沿自身厚度方向的剖面结构示意图；
图2为图1的二次电池的壳体沿A-A方向的剖面结构示意图。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照附图并举实施例，对本申请进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员所获得的所有其他实施例，都属于本申请保护的范围。
需要说明的是，本申请的具体实施方式中，以锂离子电池作为二次电池的例子来解释本申请，但并不作为对二次电池种类的限定。具体技术方案如下：
本申请第一方面提供了一种二次电池的壳体，其包括基体及粘接层，在基体上形成用以收容电极组件的第一凹部，粘接层设置于第一凹部的至少部分内表面上；粘接层具有巯基官能团，含有巯基官能团的粘接层具有良好的柔韧性、耐溶剂性及应力松弛等性能。通过在基体上形成用以收容电极组件的第一凹部，在第一凹部的至少部分内表面上邻接设置粘接层，将电极组件置入第一凹部后，粘接层与电极组件最外层的负极集流体或正极集流体连接时，粘接层在负极集流体或正极集流体上具有良好的附着力，使得粘接层与电极组件能够粘接。由此，电极组件与二次电池的壳体形成一体化结构，一体化结构能够降低电极组件在跌落过程中对二次电池的壳体内侧产生撞击的风险；同时，冲坑形成第一凹部后，第一凹部各角位的基体厚度会远小于冲坑前的基体厚度，而形成第一凹部后，通过在第一凹部的内表面设置粘接层，能够降低第一凹部各角位破裂的风险。由此，二次电池的跌落性能得以提高。并且，通过在第一凹部中设置粘接层将电极组件与二次电池的壳体粘接，当二次电池受到外力撞击时，可以在撞击的过程中使电极组件和第一凹部的一体化结构同时断裂，减小了撞击时间，使二次电池的壳体与电极组件更快的分开，减少断口接触时间，以降低短路风险，从而提升二次电池的撞击测试通过率。电极组件中的隔膜和粘接层粘接，可以抑制热冲击测试过程中的隔膜内缩，提升二次电池的热冲击性能。
此外，现有技术还常常在电极组件表面贴苯乙烯-异戊二烯-苯乙烯嵌段共聚物(SIS)等胶膜来固定电极组件和铝塑膜壳体，从而抑制电极组件在跌落过程中对铝塑膜壳体的撞击进而提高二次电池的跌落性能。但是，该方法需要增加胶膜热压激活工序，且胶膜的采 用使二次电池易出现气泡、翻折等外观不良问题。本申请的二次电池的壳体的设置，通过在第一凹部的内表面设置粘接层，电极组件和二次电池的壳体粘接后一体化结构的形成，可以在提高二次电池的跌落性能的基础上，很好地解决SIS胶膜导入二次电池时二次电池的壳体撕裂的问题，以及热压激活工序中的气泡、翻折等外观不良问题。
本申请对“巯基官能团”的表征方式不做特别限制，只要能够实现本申请目的即可。例如，可以通过红外光谱来表征巯基官能团，具体地，红外光谱中，在波数为2550cm -1至2590cm -1范围内具有表征巯基官能团的吸收峰。
在本申请中，“粘接层设置于第一凹部的至少部分内表面上”可以理解，在本申请的一些实施例中，粘接层设置于第一凹部的部分内表面上。在本申请的另一些实施例中，粘接层设置于第一凹部的全部表面上。优选地，粘接层设置于第一凹部的全部表面上，更利于工业生产，且电极组件与粘接层的粘接效果更好，更利于提高二次电池的跌落性能。
本申请对基体的种类没有特别限制，本领域技术人员可以根据实际需要进行选择，只要能够实现本申请目的即可。示例性地，在本申请的一些实施例中，基体为铝塑膜，铝塑膜包括保护层、热封层以及位于保护层和热封层之间的中间层，在基体上形成第一凹部，第一凹部的外表面为保护层，第一凹部的内表面为热封层，粘接层设置于第一凹部的内表面上，也可以理解为粘接层与热封层邻接设置。本申请对保护层、热封层和中间层的材料没有特别限制，只要能够实现本申请目的即可。例如，保护层的材料为高熔点(熔点为160℃至260℃)的聚酯或尼龙材料，保护层的材料具有较强的机械性能，能够防止外力对锂离子电池的损伤，起保护锂离子电池的作用。热封层的材料为聚乙烯或聚丙烯，能够将锂离子电池进行封装。中间层的材料为铝箔、钢箔或钛箔中的任一种，能够防止锂离子电池外部水汽的渗入，同时防止内部电解液的渗出。
在本申请的一种实施方案中，粘接层的粘接力为40N/m至100N/m，优选为60N/m至100N/m。例如，粘接力可以为40N/m、50N/m、60N/m、70N/m、80N/m、90N/m、100N/m或上述任两个数值范围间的任一数值。粘接层的粘接力处于上述范围内，能够将置于第一凹部内的电极组件和二次电池的壳体粘接在一起，使电极组件与二次电池的壳体形成紧密的一体化结构，一体化结构能够降低电极组件在跌落过程中对二次电池的壳体内侧产生撞击的风险；同时，冲坑形成第一凹部后，第一凹部各角位的基体厚度会远小于冲坑前的基体厚度，而形成第一凹部后，在第一凹部的内表面设置粘接层，能够降低第一凹部各角位破裂的风险，从而提高二次电池的跌落性能。粘接层的粘接力处于上述优选范围内，更利 于进一步提高二次电池的跌落性能。在本申请的一种实施方案中，粘接层包括聚合物，聚合物具有巯基官能团。粘接层包括具有巯基官能团的聚合物，使粘接层具有良好的柔韧性、耐溶剂性及应力松弛等性能。且粘接层具有粘接力。这样，将电极组件置入第一凹部后，电极组件和二次电池的壳体粘接在一起，使电极组件与二次电池的壳体形成紧密的一体化结构，一体化结构能够降低电极组件在跌落过程中对二次电池的壳体内侧产生撞击的风险；同时，冲坑形成第一凹部后，第一凹部各角位的基体厚度会远小于冲坑前的基体厚度，而形成第一凹部后，在第一凹部的内表面设置粘接层，能够降低第一凹部各角位破裂的风险，从而提高二次电池的跌落性能。
在本申请的一种实施方案中，聚合物的重均分子量为1000至30000，优选为15000至25000。例如，重均分子量可以为1000、5000、10000、15000、20000、25000、30000或上述任两个数值范围间的任一数值。将聚合物的重均分子量调控在上述范围内，更利于粘接层的均匀设置，也更利于使粘接层的粘接力调控在适当范围内。这样，置于第一凹部的电极组件与粘接层之间能够粘接形成一体化结构，从而提高二次电池的跌落性能。将聚合物的重均分子量调控在上述优选范围内，更利于进一步提高二次电池的跌落性能。
本申请对聚合物的重均分子量大小的调控方式没有特别限制，本领域技术人员可以选择本领域公知的方式进行调控，只要能够实现本申请目的即可。例如，可以通过调整聚硫化热塑性丙烯酸(C 3H 4O 2S) n中的n值的大小，或者调整丙烯酸类化合物、乳化剂、引发剂的配比，或者聚合的温度等来调控聚合物的重均分子量。
在本申请的一种实施方案中，粘接层包括粘接层乳液，粘接层乳液包括丙烯酸类化合物、乳化剂、引发剂、pH值稳定剂和溶剂；基于粘接层乳液的质量，丙烯酸类化合物的质量百分含量为13％至29％，优选为24％至29％，乳化剂的质量百分含量为1％至6％，优选为5.4％至6％，引发剂的质量百分含量为0.1％至1.6％，优选为1％至1.6％，pH值稳定剂的质量百分含量为0.1％至2％，优选为1％至2％，溶剂的质量百分含量为30％至80％，优选为60％至70％。例如，基于粘接层乳液的质量，丙烯酸类化合物的质量百分含量为13％、15％、17％、19％、21％、24％、25％、27％、29％或上述任两个数值范围间的任一数值，乳化剂的质量百分含量为1％、2％、3％、4％、5％、5.4％、6％或上述任两个数值范围间的任一数值，引发剂的质量百分含量为0.1％、0.4％、0.7％、1.0％、1.3％、1.6％或上述任两个数值范围间的任一数值，pH值稳定剂的质量百分含量为0.1％、0.4％、0.7％、1.0％、1.3％、1.6％、2％或上述任两个数值范围间的任一数值，溶剂的质量百分含量为30％、40％、50％、 60％、62％、67％、70％、80％或上述任两个数值范围间的任一数值。选用上述质量百分含量范围的丙烯酸类化合物、乳化剂、引发剂、pH值稳定剂和溶剂，更容易制备得到各组分均匀分布的粘接层乳液，粘接层乳液均匀设置于第一凹部的内表面上，经烘干固化后形成未激活状态的粘接层，未激活状态的粘接层经热压处理后从未激活状态转变成激活状态，使粘接层具有良好的粘接力，将置入第一凹部的电极组件与二次电池的壳体粘接成一体化结构，一体化结构能够降低电极组件在跌落过程中对二次电池的壳体内侧产生撞击的风险，从而提高二次电池的跌落性能。选用上述优选质量百分含量范围的丙烯酸类化合物、乳化剂、引发剂、pH值稳定剂和溶剂，更利于提高二次电池的跌落性能。
在本申请中，粘接层乳液均匀设置于第一凹部的内表面上，经烘干固化后形成未激活状态的粘接层，未激活状态的粘接层经过热压处理后从未激活状态转变成激活状态。其中，未激活状态的粘接层不具有粘接力，激活状态的粘接层具有粘接力。在本申请中，如无特别说明，粘接层是指经过热压处理后，处于激活状态、具有粘接力的粘接层。上述“热压处理”的温度为70℃至80℃、压力为1.0MPa至1.2MPa。本申请对上述“烘干”的工艺条件没有特别限制，只要能够实现本申请目的即可。
在本申请的一种实施方案中，丙烯酸类化合物包括聚硫化热塑性丙烯酸(C 3H 4O 2S) n，且10≤n≤300；乳化剂包括N-十二烷基二甲胺；引发剂包括过硫酸铵或过硫酸钠等；pH值稳定剂包括碳酸氢钠或碳酸氢钾；溶剂包括去离子水。上述种类的聚丙烯酸类化合物、乳化剂、引发剂、pH值稳定剂和溶剂的选择，更容易制备得到均匀的粘接层乳液，形成均匀各组分均匀分布的粘接层。聚硫化热塑性丙烯酸的选用，使粘接层中引入硫基官能团，从而使粘接层具有良好的柔韧性、耐溶剂性及应力松弛等性能。将电极组件置入第一凹部后，粘接层与电极组件最外层的负极集流体或正极集流体连接时，粘接层在负极集流体或正极集流体上具有良好的附着力，使得粘接层与电极组件能够粘接。由此，电极组件与二次电池的壳体形成一体化结构，一体化结构能够降低电极组件在跌落过程中对二次电池的壳体内侧产生撞击的风险，从而提高二次电池的跌落性能。在本申请的一种实施方案中，50≤n≤250。在本申请的另一种实施方案中，100≤n≤200。
在本申请的一种实施方案中，丙烯酸类化合物还包括甲基丙烯酸、氯代丙烯酸、氟代丙烯酸或丙烯酸(分子式：C 3H 4O 2)中的至少一种。在粘接层中进一步选用上述种类的丙烯酸类化合物，更利于粘接层与电极组件粘接形成一体化结构，使得电极组件在跌落过程中对二次电池的壳体内侧产生撞击的风险得以降低，从而提高二次电池的跌落性能。
本申请对粘接层乳液的制备方法没有特别限制，只要能够实现本申请目的即可。例如，可以采用以下制备方法制备粘接层乳液：将丙烯酸类化合物、乳化剂、引发剂、pH值稳定剂和溶剂按照本申请的质量百分含量均匀混合制得粘接层乳液。
在本申请的一种实施方案中，基体的厚度为70μm至200μm，优选为150μm至200μm；粘接层的厚度为3μm至40μm，优选为5μm至15μm。例如，基体的厚度为70μm、80μm、90μm、100μm、110μm、120μm、130μm、140μm、150μm、200um或上述任两个数值范围间的任一数值，粘接层的厚度为3μm、5μm、10μm、15μm、20μm、25μm、30μm、35μm、40μm或上述任两个数值范围间的任一数值。将基体的厚度和粘接层的厚度调控在上述范围内，二次电池的壳体具有降低撞击通过率的厚度的情况下，使二次电池具有较小的体积，从而使二次电池具有较高的能量密度的情况下，提高二次电池的跌落性能。将基体的厚度和粘接层的厚度调控在上述优选范围内，更利于进一步提高二次电池的跌落性能。
本申请对二次电池的壳体的种类没有特别限制，只要能够实现本申请目的即可。例如，二次电池的壳体为一体式结构，或者，二次电池的壳体为包含有第一包装壳和第二包装壳的分离式结构。
本申请对二次电池的壳体的制备方法没有特别限制，只要能够实现本申请目的即可。示例性地，如图1和图2所示，在本申请的一些实施例中，二次电池的壳体为一体式结构，其制备方法包括如下步骤：在如图1中的(a)和图2中的(a)所示的基体10上，形成如图1中的(b)和图2中的(b)所示的第一凹部11和气袋12；在第一凹部11的内表面上邻接设置如图1中的(c)和图2中的(c)所示的未激活状态的粘接层13。第一凹部11用以容纳电极组件，后续将电极组件置入第一凹部11中，经热压处理后，未激活状态的粘接层13由未激活状态转变成激活状态，使粘接层13与电极组件粘接成一体式结构。
本申请对在第一凹部内表面上邻接设置粘接层的工艺没有特别限制，只要能够实现本申请目的即可。优选地，在第一凹部内表面上邻接设置粘接层的工艺选自凹版印刷、绕线棒涂布、刮刀涂布和落帘涂布中的任一种。
本申请第二方面提供了一种二次电池，其包括电极组件和本申请第一方面提供的二次电池的壳体，二次电池的壳体包括第一凹部及与第一凹部连接的密封部，电极组件收容于第一凹部，粘接层设置于第一凹部的至少部分内表面上。通过在第一凹部的内表面上设置粘接层，粘接层与电极组件最外层的负极集流体或正极集流体连接时，粘接层在负极集流体或正极集流体上具有良好的附着力，使得粘接层与电极组件能够粘接。由此，电极组件 与二次电池的壳体形成一体化结构，一体化结构能够降低电极组件在跌落过程中对二次电池的壳体内侧产生撞击的风险；同时，冲坑形成第一凹部后，第一凹部各角位的基体厚度会远小于冲坑前的基体厚度，而形成第一凹部后，在第一凹部的内表面设置粘接层，能够降低第一凹部各角位破裂的风险，从而提高二次电池的跌落性能。并且，通过在第一凹部中设置粘接层将电极组件与二次电池的壳体粘接，当二次电池受到外力撞击时，可以在撞击的过程中使电极组件和第一凹部的一体化结构同时断裂，减小了撞击时间，使二次电池的壳体和电极组件更快的分开，减少断口接触时间，以降低短路风险，从而提升二次电池的撞击测试通过率。电极组件中的隔膜和粘接层粘接，可以抑制热冲击测试过程中的隔膜内缩，提升二次电池的热冲击性能。
本申请对电极组件的结构没有特别限制，只要能够实现本申请目的即可。例如，电极组件的结构为卷绕结构或叠片结构。
优选地，在本申请的一种实施方案中，电极组件的结构为叠片结构。叠片结构的电极组件相较于卷绕结构，其自身结构更利于与第一凹部内表面上粘接层的各部位粘接，更利于提升电极组件与粘接层之间的粘接力，使得电极组件与二次电池的壳体形成更加紧密的一体化结构，从而更利于提高二次电池的跌落性能。
本申请的电极组件包括正极极片、隔膜和负极极片，隔膜位于正极极片和负极极片之间，将正极极片和负极极片分隔开，以防止二次电池内部短路，隔膜允许电解质离子自由通过，完成电化学充放电过程的作用。在本申请中，对电极组件中的隔膜、正极极片和负极极片的数量不做特别限定，只要能实现本申请目的即可。
本申请对正极极片、隔膜和负极极片的种类均没有特别限制，本领域技术人员可以根据实际需要选择，只要能够实现本申请目的即可。示例性地，在本申请的一些实施例中，正极极片包括正极活性材料层和正极集流体，正极活性材料层设置于正极集流体沿自身厚度方向的一个表面或两个表面上，正极活性材料层包括正极活性材料。负极极片包括负极活性材料层和负极集流体，负极活性材料设置于负极集流体沿自身厚度方向的一个表面或两个表面上，负极活性材料层包括负极活性材料。本申请对正极活性材料、正极集流体、负极活性材料和负极集流体没有特别限制，本领域技术人员可以根据实际需要选择，只要能够实现本申请目的即可。
本申请的二次电池还包括电解液，本申请对电解液没有特别限制，本领域技术人员可以根据实际需要选择，只要能够实现本申请目的即可。
本申请的二次电池没有特别限制，其可以包括发生电化学反应的装置。例如，二次电池可以包括但不限于：锂金属二次电池、锂离子二次电池(锂离子电池)、钠离子二次电池、锂聚合物二次电池、锂离子聚合物二次电池。
本申请对二次电池的制备方法没有特别限制，可以选用本领域公知的制备方法，只要能够实现本申请目的即可。示例性地，在本申请的一些实施例中，二次电池的壳体为一体式结构，二次电池的制备方法包括如下步骤：在如图1中的(a)和图2中的(a)所示的基体10上，形成如图1中的(b)和图2中的(b)所示的第一凹部11和气袋12；在第一凹部11的内表面上邻接设置如图1中的(c)和图2中的(c)所示的未激活状态的粘接层13；将电极组件放入如图1中的(c)所示的第一凹部11内，使电极组件外表面与粘接层13相邻，将如图1中的(c)所示的二次电池的壳体对折后封装成型，形成容纳部和密封部；接着将封装成型后的二次电池进行热压处理，使电极组件与二次电池的壳体粘接而形成一体化结构；之后，注入电解液、化成，得到二次电池。
其中，本申请对电极组件的制备方法没有特别限制，只要能够实现本申请目的即可。例如，将正极极片、隔膜和负极极片按顺序堆叠，并根据需要将其卷绕、折叠等操作得到卷绕结构的电极组件。或者，将正极极片、隔膜和负极极片按顺序堆叠，然后用胶带将整个叠片结构的四个角固定好得到叠片结构的电极组件。
本申请第三方面提供了一种电子装置，其包括本申请第二方面提供的二次电池。因此，能够获得上述第二方面提供的二次电池的有益效果。
本申请的电子装置没有特别限定，其可以是用于现有技术中已知的电子装置。例如，电子装置可以包括但不限于：笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池、锂离子电容器。
实施例
以下举出实施例及对比例来对本申请的实施方式进行更具体地说明。各实施例和对比例的制备及各性能参数的测试按照下述的方法进行。
测试方法和设备：
粘接层的粘接力的测试：
1)取各实施例和对比例的锂离子电池放电至SOC(荷电状态)＝0％；
2)拆解锂离子电池，沿锂离子电池四周将多余壳体裁切去除；
3)采用拉力机对电极组件和粘接层进行粘接力测试；
4)拉力机的一侧固定壳体，一侧固定电极组件；
5)记录拉力机原始F-X(拉力-位移)数据并进行分析，最终测得平稳区域的拉力平均值记为粘接力。
跌落通过率的测试：
(1)锂离子电池1.0米跌落通过率的测试：
1)将各实施例和对比例的锂离子电池在常温下进行表面清洁并装入跌落夹具；
2)对装入跌落夹具的锂离子电池进行电压调试至SOC＝50％；
3)采用自动跌落设备进行1.0米跌落，跌落要求：6面、8棱边、4顶点跌落，共计跌落18次；
4)锂离子电池跌落完毕后进行外观、气体检查，按如下要求判定锂离子电池是否失效，不失效即为通过。
锂离子电池失效判定标准：
不漏液：检查所测试锂离子电池的接缝、角、表面、边缘无漏液，漏液较少外观不易看出时，可以进行气体检查，如是否有异味；
不燃烧：锂离子电池没有燃烧或出现热失控；
不变形：目测无异常变形；
极耳不断裂：锂离子电池能通过功能检查(如测电压和内阻)；
无隔膜翻折：拆解隔膜不能有翻折或者收缩，导致正极极片和/或负极极片极片外露；
没有封装失效：密封部必须完整，无分层或张开。
每个实施例或对比例各测试10个锂离子电池，跌落通过率(％)＝通过个数/10×100％。
(2)锂离子电池1.5米跌落通过率的测试：
除了将3)中的1.0米跌落调整为1.5米跌落以外，其余与上述(1)锂离子电池1.0米跌落通过率的测试相同。
撞击通过率的测试：
1)预处理：将各实施例和对比例的锂离子电池在常温下满充至SOC＝100％；
2)测试前检查外观并拍照；
3)将感温线贴在锂离子电池的头尾区和其自身厚度的一个表面，在底板上贴绝缘黄胶，将锂离子电池自身厚度的另一个表面和底板粘贴，将锂离子电池头尾用绝缘黄胶半固定；
4)测试：在20±5℃测试环境，将待测试锂离子电池作为样品放置于测试台面，将直径为φ15.8±0.1mm、长度至少6cm的圆棒放置于样品宽面的中心位置。待样品纵轴平行测试台面表面且与圆棒纵轴垂直。使用9.1±0.1kg的重锤，从610±25mm高度垂直自由状态落下，跌落于圆棒与样品交叉处。
5)测试后检查外观并拍照；
6)判定标准：不起火、不爆炸、不冒烟即为通过。
每个实施例或对比例各测试10个锂离子电池，撞击通过率(％)＝通过个数/10×100％。
热冲击性能的测试：
1)预处理：将各实施例和对比例的锂离子电池在25℃预处理温度下满充至SOC＝100％；
2)测试前检查外观并拍照；
3)感温线贴在锂离子电池的头尾区和其自身厚度的一个表面，在底板上贴绝缘黄胶，将锂离子电池自身厚度的另一个表面和底板粘贴，将锂离子电池头尾用绝缘黄胶半固定；
4)测试：将待测试锂离子电池作为样品水平放置于高低温箱的箱体中按照5±2℃升温速度升温至132±2℃并保持60min；
5)测试后检查外观并拍照；
6)判定标准：不起火、不爆炸即为通过。
每个实施例或对比例各测试10个锂离子电池，热冲击性能测试通过率(％)＝通过个数/10×100％。
实施例1-1
<电解液的制备>
在干燥的氩气气氛中，将二氧环戊烷和二甲醚按照质量比＝1:1混合得到有机溶剂，然后向有机溶剂中加入锂盐双三氟甲烷磺酰亚胺锂溶解并混合均匀，得到锂盐浓度为1.0mol/L的电解液。
<负极极片的制备>
将负极活性材料石墨、负极导电剂石墨、负极导电剂炭黑和负极粘结剂羧甲基碳酸素钠酸按照质量比为95:1:2:2进行混合，将得到的混合物均匀分散在蒸馏水中，在真空搅拌机作用下搅拌均匀，获得负极浆料，其中负极浆料的固含量为75wt％。将负极浆料均匀涂覆于厚度为12μm的负极集流体铜箔的一个表面上，将铜箔在85℃下烘干，得到涂层厚度为75μm的单面涂覆有负极活性材料层的负极极片。在铜箔的另一个表面上重复以上步骤，即得到双面涂布负极活性材料层的负极极片。然后经过干燥、冷压、裁片、分切后得到规格为41mm×61mm的负极极片。
<正极极片的制备>
将正极活性材料磷酸铁锂、正极导电剂导电炭黑、正极粘结剂聚偏氟乙烯按照质量比为97.5:1.0:1.5进行混合，加入N-甲基吡咯烷酮，在真空搅拌机作用下搅拌均匀，获得正极浆料，其中正极浆料的固含量为75wt％。将正极浆料均匀涂覆于厚度为10μm的正极集流体铝箔的一个表面上，将铝箔在90℃下烘干，得到单面涂覆有正极活性材料层的正极极片。在铝箔的另一个表面上重复以上步骤，即得到双面涂布正极活性材料层的正极极片。然后经过干燥、冷压、裁片、分切后得到规格为38mm×58mm的正极极片。
<隔膜的制备>
采用厚度为11μm的聚乙烯薄膜(Celgard公司提供)。
<锂离子电池的制备>
在上述制备所得的正极极片和负极极片中间放置隔膜，层叠后将四个角固定，形成叠片结构的电极组件，其中正极极片和负极极片的层数分别为16、17，隔膜的层数为32。
对厚度为90μm的基体铝塑膜冲坑成型，形成如图1中的(b)所示的第一凹部，在第一凹部的内表面上采用凹版印刷工艺均匀设置粘结层乳液，经2s烘干固化，形成厚度为10μm的未激活状态的粘接层。其中，粘接层乳液包括聚丙烯酸类化合物：聚硫化热塑性丙烯酸(C 3H 4O 2S) n(48≤n≤241)、甲基丙烯酸、氟代丙烯酸和丙烯酸，乳化剂N-十二烷基二甲胺，引发剂过硫酸钠，PH值稳定剂碳酸氢钠，溶剂去离子水。基于粘接层乳液的质量，(C 3H 4O 2S) n的质量百分含量为10％、甲基丙烯酸的质量百分含量为8％、氟代丙烯酸的质量百分含量为4％、丙烯酸的质量百分含量为2％、N-十二烷基二甲胺的质量百分含量为5.4％、过硫酸钠的质量百分含量1.6％、碳酸氢钠的质量百分含量为2％、去离子水的质量百分含量为67％。
将电极组件放入第一凹部内，将如图1中的(c)所示的二次电池的壳体对折后封装成 型得到二次电池。将封装成型后的二次电池在70℃和1MPa条件下进行热压处理，未激活状态的粘接层转变成激活状态，粘接层中各物质聚合形成聚合物，聚合物的重均分子量为20000，之后，注入电解液、化成，得到最终的二次电池。
实施例1-2至实施例1-9
除了按照表1调整相关制备参数以外，其余与实施例1-1相同。
实施例1-10
除了将<负极极片的制备>中负极极片的规格调整41mm×440mm、将<正极极片的制备>中正极极片的规格调整为38mm×430mm、将<锂离子电池的制备>中电极组件的结构调整为卷绕结构以外，其余与实施例1-1相同。
其中，卷绕结构的电极组件的制备方法如下：将上述制备得到的正极极片、负极极片、隔膜按顺序叠好，使隔膜处于正极极片和负极极片中间起到隔离的作用，卷绕得到电极组件。
实施例2-1至实施例2-11
除了按照表2调整相关制备参数以外，其余与实施例1-1相同。
实施例3-1至实施例3-5
除了按照表3调整相关制备参数以外，其余与实施例1-1相同。
对比例1
除了在<锂离子电池的制备>中不设置粘接层以外，其余与实施例1-1相同。
对比例2
除了在<锂离子电池的制备>中，粘接层的组分为甲基丙烯酸-氟代丙烯酸-丙烯酸共聚物(重均分子量20000，甲基丙烯酸、氟代丙烯酸、丙烯酸的质量比为1:1:1)外，其余与实施例1-1相同。
各实施例和对比例的制备参数如表1至表3所示。
表1
Figure PCTCN2022129827-appb-000001
注：表1中的“\”表示无对应制备参数，实施例1-10中的电极组件结构为卷绕结构。
从实施例1-1至实施例1-9、对比例1和对比例2中可以看出，实施例1-1至实施例1-9选用在基体上形成的第一凹部的内表面上设置粘接层，粘接层具有巯基官能团的锂离子电池，具有更好的跌落性能、更好的热冲击性能和更高的撞击通过率；粘接层中聚合物的重均分子量在本申请范围内的锂离子电池，具有进一步的跌落性能、更好的热冲击性能和更高的撞击通过率。而对比例1中，选用第一凹部的内表面未设置本申请的粘接层的锂离子电池，其跌落性能、热冲击性能和撞击通过率均未能得到提高。对比例2中，选用粘接层不具有巯基官能团的锂离子电池，其跌落性能、热冲击性能和撞击通过率均未能得到提高。
电极组件的结构通常也会影响锂离子电池的跌落性能。从实施例1-1和实施例1-10中可以看出，选用电极组件的结构在本申请范围内的锂离子电池，具有良好的跌落性能、良好的热冲击性能和较高的撞击通过率。
表2
Figure PCTCN2022129827-appb-000002
Figure PCTCN2022129827-appb-000003
粘接层的厚度通常也会影响锂离子电池的跌落性能、撞击通过率和热冲击性能。从实施例1-1、实施例2-1至实施例2-8可以看出，选用粘接层的厚度在本申请范围内的锂离子电池，具有良好的跌落性能、良好的热冲击性能和较高的撞击通过率。
基体的厚度通常也会影响锂离子电池的跌落性能、撞击通过率和热冲击性能。从实施例1-1、实施例2-9至实施例2-11可以看出，选用基体的厚度在本申请范围内的锂离子电池，具有良好的跌落性能、良好的热冲击性能和较高的撞击通过率。
Figure PCTCN2022129827-appb-000004
Figure PCTCN2022129827-appb-000005
粘接层乳液中丙烯酸类化合物、乳化剂、引发剂、pH值稳定剂和溶剂的质量百分含量通常也会影响锂离子电池的跌落性能、撞击通过率和热冲击性能。从实施例1-1、实施例3-1和实施例3-3可以看出，选用粘接层乳液中丙烯酸类化合物、乳化剂、引发剂、pH值稳定剂和溶剂的质量百分含量在本申请范围内的锂离子电池，具有良好的跌落性能、良好的热冲击性能和较高的撞击通过率。
粘接层乳液中丙烯酸类化合物的种类通常也会影响锂离子电池的跌落性能、撞击通过率和热冲击性能。从实施例1-1、实施例3-4和实施例3-5可以看出，选用粘接层乳液中丙烯酸类化合物的种类在本申请范围内的锂离子电池，具有良好的跌落性能、良好的热冲击性能和较高的撞击通过率。
以上所述仅为本申请的较佳实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (15)

  1. 一种二次电池的壳体，其特征在于，包括基体及粘接层，在所述基体上形成用以收容电极组件的第一凹部，所述粘接层设置于所述第一凹部的至少部分内表面上；
    所述粘接层具有巯基官能团。
  2. 根据权利要求1所述的壳体，其特征在于，所述粘接层的粘接力为40N/m至100N/m。
  3. 根据权利要求2所述的壳体，其特征在于，所述粘接层的粘接力为60N/m至100N/m。
  4. 根据权利要求1所述的壳体，其特征在于，所述粘接层包括聚合物，所述聚合物具有巯基官能团。
  5. 根据权利要求4所述的壳体，其特征在于，所述聚合物的重均分子量为1000至30000。
  6. 根据权利要求5所述的壳体，其特征在于，所述聚合物的重均分子量为15000至25000。
  7. 根据权利要求4所述的壳体，其特征在于，所述粘接层包括粘接层乳液，所述粘接层乳液包括丙烯酸类化合物、乳化剂、引发剂、pH值稳定剂和溶剂；
    基于所述粘接层乳液的质量，所述丙烯酸类化合物的质量百分含量为13％至29％，所述乳化剂的质量百分含量为1％至6％，所述引发剂的质量百分含量为0.1％至1.6％，所述pH值稳定剂的质量百分含量为0.1％至2％，所述溶剂的质量百分含量为30％至80％。
  8. 根据权利要求7所述的壳体，其特征在于，基于所述粘接层乳液的质量，所述丙烯酸类化合物的质量百分含量为24％至29％，所述乳化剂的质量百分含量为5.4％至6％，所述引发剂的质量百分含量为1％至1.6％，所述pH值稳定剂的质量百分含量为1％至2％，所述溶剂的质量百分含量为60％至70％。
  9. 根据权利要求7所述的壳体，其特征在于，所述丙烯酸类化合物包括聚硫化热塑性丙烯酸(C 3H 4O 2S) n，且10≤n≤300；
    所述乳化剂包括N-十二烷基二甲胺；
    所述引发剂包括过硫酸铵或过硫酸钠；
    所述pH值稳定剂包括碳酸氢钠或碳酸氢钾；
    所述溶剂包括去离子水。
  10. 根据权利要求9所述的壳体，其特征在于，所述丙烯酸类化合物还包括甲基丙烯酸、氯代丙烯酸、氟代丙烯酸或丙烯酸中的至少一种。
  11. 根据权利要求1所述的壳体，其特征在于，所述基体的厚度为70μm至200μm，所述粘接层的厚度为3μm至40μm。
  12. 根据权利要求11所述的壳体，其特征在于，所述基体的厚度为150μm至200μm，所述粘接层的厚度为5μm至15μm。
  13. 一种二次电池，其特征在于，包括电极组件和权利要求1至12中任一项所述的二次电池的壳体，所述电极组件收容于所述第一凹部，所述粘接层粘接所述电极组件。
  14. 根据权利要求13所述的二次电池，其特征在于，所述电极组件的结构为叠片结构。
  15. 一种电子装置，其特征在于，包括权利要求13或14所述的二次电池。
PCT/CN2022/129827 2022-11-04 2022-11-04 二次电池的壳体、二次电池和电子装置 WO2024092708A1 (zh)

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