Polymer, separator, related secondary battery, and power consumption device

Abstract

This application provides a polymer, a separator, and related secondary batteries and power consumption devices. The polymer includes a first structural unit, a second structural unit, and a third structural unit. The first structural unit includes a structural unit represented by formula (I). In formula (I), R1 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group. R2 includes one or more of a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, and a substituted or unsubstituted C1-C20 hydroxyalkyl group. The second structural unit includes a structural unit represented by formula (II). In formula (II), R3 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group. The third structural unit includes a structural unit represented by formula (III). Among the three types of structural units in the polymer, they act synergistically with each other, and can jointly improve the adhesiveness, stability, swelling resistance, and thermal stability of the polymer. JPEG2025523973000032.jpg51170

Description

Technical Field

[0001] This application relates to the field of batteries, and specifically to polymers, separators, and related secondary batteries and power consumption devices.

Background Art

[0002] Secondary batteries have characteristics such as high capacity and long life, and are therefore widely applied to electronic devices such as mobile phones, notebook computers, battery vehicles, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and electric tools.

[0003] As the application range of batteries becomes increasingly wide, the requirements for the safety performance of secondary batteries are also becoming increasingly strict. How to continuously improve the safety performance of secondary batteries remains an urgent problem to be solved by those skilled in the art.

Summary of the Invention

[0004] This application is made in view of the above problems, and aims to provide a polymer, a separator, and related secondary batteries and power consumption devices.

[0005] The first aspect of this application provides a polymer, and the polymer includes a first structural unit, a second structural unit, and a third structural unit. The first structural unit includes a structural unit represented by formula (I). In formula (I) of JPEG2025523973000002.jpg5089, R1 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group. Optionally, R1 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C3 alkyl group. R2 includes one or more of a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, and a substituted or unsubstituted C1-C20 hydroxyalkyl group. Optionally, R2 includes one or more of a C1-C12 alkyl group, a C3-C12 cycloalkyl group, and a C1-C12 hydroxyalkyl group. The second structural unit includes the structural unit represented by formula (II), In formula (II), R3 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group. Optionally, R3 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C3 alkyl group, The third structural unit includes the structural unit represented by formula (III), In formula (III), R4 to R 11 each independently include a substituted or unsubstituted C1-C10 alkyl group, one or more of the structural units represented by formula (III-1), and at least one of R4 to R 11 includes the structural unit represented by formula (III-1), In formula (III-1), R 12 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group. Optionally, R 12 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C3 alkyl group. R 13 includes a substituted or unsubstituted C1-C10 alkyl group. Optionally, R 13 includes a substituted or unsubstituted C3-C10 alkyl group.

[0006] Accordingly, in the present application, the first structural unit contributes to exerting a good adhesion effect because the flexible monomer chain segment in the molecular chain segment can adjust the glass transition temperature of the polymer and improve the toughness and peel strength of the polymer. The second structural unit can generate excellent swelling resistance and high adhesiveness, and contributes to improving the ion conductivity of the secondary battery. When the polymer is applied to the separator, the polymer is in contact with the electrolyte, and the polymer is difficult to swell, which has relatively good swelling resistance. The third structural unit can endow the polymer with advantages in terms of heat resistance and mechanical properties, and can guarantee the safety performance of the secondary battery by ensuring the stability of the polymer and effectively blocking the positive and negative electrode plates during long-term cycle charge and discharge of the secondary battery. The cooperation between the first structural unit and the third structural unit exerts a synergistic effect and can improve the adhesion performance and heat resistance performance of the polymer. The cooperation between the first structural unit and the second structural unit can exert a synergistic effect and can improve the stability and swelling resistance of the polymer. Among the three types of structural units in the polymer, they act synergistically with each other and can jointly improve the adhesiveness, stability, swelling resistance and thermal stability of the polymer.

[0007] In some embodiments, R1 includes a hydrogen atom or a methyl group, and / or R2 includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-octyl group, an isooctyl group, a 2-ethylhexyl group, a dodecyl group or an isobornyl group.

[0008] In some embodiments, R3 includes a hydrogen atom or a methyl group.

[0009] In some embodiments, R4~R 11 each independently includes the structural unit represented by the formula (III-1). Optionally, R 12 includes a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group or an n-pentyl group, and / or R 13It contains an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-octyl group, an isooctyl group or a 2-ethylhexyl group.

[0010] In some embodiments, one of R4 to R 11 contains the structural unit represented by the formula (III-1), and optionally, R 12 is a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group or an n-pentyl group, and / or R 13 contains an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-octyl group, an isooctyl group or a 2-ethylhexyl group.

[0011] In some embodiments, based on the total molar amount of the first structural unit, the second structural unit and the third structural unit, the molar content of the first structural unit is A%, and 60 ≦ A < 100, and optionally, 60 ≦ A ≦ 80. When the molar content of the first structural unit is within the above range, its proportion in the polymer is relatively large, and by improving the flexibility of the polymer, the adhesiveness of the polymer can be significantly improved. When the polymer is applied to the separator, the bonding force between the polymer and the substrate of the separator can be improved.

[0012] In some embodiments, based on the total molar amount of the first structural unit, the second structural unit and the third structural unit, the molar content of the second structural unit is B%, and 0 < B ≦ 20, and optionally, 5 ≦ B ≦ 20. When the molar content of the second structural unit is within the above range, the stability of the polymer can be significantly improved.

[0013] In some embodiments, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the third structural unit is C%, where 0 < C ≤ 20, and optionally, 5 ≤ C ≤ 20. When the molar content of the third structural unit is within the above range, the heat resistance of the polymer can be guaranteed, and its proportion is relatively small, which is beneficial to improving the proportions of the first structural unit and the second structural unit and enhancing the performance of the polymer as a whole, such as adhesiveness, stability, and swelling resistance.

[0014] In some embodiments, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the first structural unit is A%, the molar content of the second structural unit is B%, and the molar content of the third structural unit is C%. The polymer satisfies one or more of the following conditions: (1) 3 ≤ A / B ≤ 16, (2) 3 ≤ A / C ≤ 16, and (3) A:B:C is (12 - 16):(1 - 4):(1 - 4). When the molar contents of the first structural unit, the second structural unit, and the third structural unit satisfy the above ratios, the three types of structural units act synergistically with each other, further improving the adhesiveness, stability, swelling resistance, and thermal stability of the polymer.

[0015] In some embodiments, the number average molecular weight of the polymer is from 20,000 to 80,000, and optionally from 30,000 to 50,000. When the number average molecular weight of the polymer is within the above range, it is advantageous for the formation of polymer particles with relatively small particle sizes. When applied to a separator, a thin coating of the coating on the separator can be realized, and the overall thickness of the separator can be reduced, thereby easily increasing the energy density of the secondary battery. At the same time, the particle size of the polymer particles formed by the polymer is not too small, and the risk that the polymer particles block the base material in the separator can be reduced, and the performance such as the air permeability of the entire separator can be improved. In some embodiments, the polymer is in particulate form, and the polymer further satisfies one or more of the following conditions: (I) the topography of the polymer includes spherical and / or quasi-spherical shapes; (II) the volume distribution particle size Dv50 of the polymer satisfies 0.1 μm ≤ Dv50 ≤ 2.0 μm, and optionally 0.5 μm ≤ Dv50 ≤ 1.2 μm; (III) taking the specific surface area of the polymer as S, the unit is m 2 / g, and 5.0 ≤ S ≤ 12.0, and optionally 6.0 ≤ S ≤ 10.0. When the polymer is in particulate form and satisfies at least one of the above conditions, the adhesiveness, stability, swelling resistance and heat resistance of the polymer can be further improved.

[0016] The second aspect of the present application provides a method for manufacturing a polymer. The method is used for manufacturing the polymer according to any one of the embodiments of the first aspect of the present application. The method includes providing a first monomer, a second monomer and a third monomer, and mixing the first monomer, the second monomer and the third monomer to generate a polymerization reaction under the action of an initiator to generate a polymer. Here, the first monomer includes a compound represented by formula (IV). In Formula (IV) of JPEG2025523973000006.jpg5284, R1 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group. Optionally, R1 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C3 alkyl group. R2 includes one or more of a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, and a substituted or unsubstituted C1-C20 hydroxyalkyl group. Optionally, R2 includes one or more of a C1-C12 alkyl group, a C3-C12 cycloalkyl group, and a C1-C12 hydroxyalkyl group. The second monomer includes a compound represented by Formula (V). In Formula (V) of JPEG2025523973000007.jpg5452, R3 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group. Optionally, R3 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C3 alkyl group. The third monomer includes a compound represented by Formula (VI). In Formula (VI) of JPEG2025523973000008.jpg83136, R 30 ~R 37 each independently includes a substituted or unsubstituted C1-C10 alkyl group and one or more of the structural units represented by Formula (VI-1), and at least one of R 30 ~R 37 includes the structural unit represented by Formula (VI-1). In Formula (VI-1) of JPEG2025523973000009.jpg50115, R 12 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group. Optionally, R 12 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C3 alkyl group. R 13 includes a substituted or unsubstituted C1-C10 alkyl group. Optionally, R 13 includes a substituted or unsubstituted C3-C10 alkyl group.

[0017] In some embodiments, the step of mixing the first monomer, the second monomer, and the third monomer and generating a polymerization reaction under the action of an initiator to produce a polymer includes the step of adding the first monomer, the second monomer, and the third monomer to a solvent and an emulsifier, mixing them to form a mixed system, and adding the initiator to the mixed system to generate a polymerization reaction under the action of the initiator to produce the polymer.

[0018] In some embodiments, the first monomer includes one or more of methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-pentyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.

[0019] In some embodiments, the second monomer includes acrylonitrile and / or methacrylonitrile.

[0020] In some embodiments, the third monomer includes one or more of methacryloxypropyl cage-type polysilsesquioxane, methacryloxypropyl heptaisobutyl polysilsesquioxane, acryloxypropyl cage-type polysilsesquioxane, acryloxypropyl heptaisobutyl polysilsesquioxane, and methacryloxypropyl heptaoctyl polysilsesquioxane.

[0021] A third aspect of this application further provides a separator, which includes a substrate and a coating disposed on at least one surface of the substrate, and the coating includes the polymer described in any one of the embodiments of the first aspect of this application or the polymer obtained by manufacturing according to the method described in any one of the embodiments of the second aspect of this application.

[0022] In some embodiments, based on the mass of the coating, the mass percentage content of the polymer is m%, where m ≥ 70, and optionally, 80 ≤ m ≤ 95. When the mass percentage content of the polymer is within the above range, the adhesiveness, stability, swelling resistance, and heat resistance of the entire separator can be further improved.

[0023] In some embodiments, the separator (A) the longitudinal thermal shrinkage rate of the separator at 150°C for 1 h is η1 ≤ 5.0%, and optionally 0.5% ≤ η1 ≤ 3%; (B) the transverse thermal shrinkage rate of the separator at 150°C for 1 h is η2 ≤ 5.0%, and optionally 0.5% ≤ η2 ≤ 2%; (C) the longitudinal tensile strength of the separator is R m1 ≥ 3000 kg / cm 2 and optionally 3500 kg / cm 2 ≤ R m1 ≤ 4500 kg / cm 2 ; (D) the transverse tensile strength of the separator is R m2 ≥ 3000 kg / cm 2 and optionally 3500 kg / cm 2 ≤ R m2 ≤ 4500 kg / cm 2 ; (E) the air permeability of the separator is MAP ≤ 250 s / 100 mL, and optionally 120 s / 100 mL ≤ MAP ≤ 180 s / 100 mL; (F) the wetting length of the separator is L ≥ 30 mm, and optionally 30 mm ≤ L ≤ 80 mm. (G) The wetting rate of the separator satisfies one or more of the conditions that u ≥ 3 mm / s, and optionally, 3 mm / s ≤ u ≤ 10 mm / s.

[0024] A fourth aspect of the present application further provides a secondary battery, which includes a separator according to any one of the embodiments of the third aspect of the present application.

[0025] A fifth aspect of the present application further provides a power consumption device, which includes the secondary battery described in the fourth aspect of the present application.

Brief Description of the Drawings

[0026] To more clearly explain the technical solutions of the embodiments of the present application, the following briefly introduces the drawings that need to be used in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. On the premise that no creative effort is required for those skilled in the art, other drawings can also be obtained based on the drawings. The drawings are not necessarily drawn to actual scale.

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Embodiments for Carrying Out the Invention

[0027] Hereinafter, embodiments specifically disclosing the polymer, separator, related secondary battery, and power consumption device of the present application will be described in detail. However, detailed descriptions that are not necessary may be omitted. For example, detailed descriptions of well-known matters and duplicate descriptions of actually identical structures may be omitted. This is to avoid the following description from becoming unnecessarily long and to enable those skilled in the art to easily understand. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and do not limit the theme described in the claims.

[0028] The "range" disclosed in the present application is limited in the form of a lower limit and an upper limit. The given range is limited by selecting one lower limit and one upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The range thus limited may or may not include the end values, and any combination is possible, that is, any lower limit can be combined with any upper limit to form a range. For example, when ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, ranges of 60 to 110 and 80 to 120 can also be assumed to be understood. Note that if 1 and 2 are listed as the minimum range values and 3, 4, and 5 are listed as the maximum range values, ranges of 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 can all be assumed. In the present application, unless otherwise specified, the numerical range of "a to b" represents a shortened expression of any real number combination of a to b, where both a and b are real numbers. For example, the numerical range of "0 to 5" represents that all real numbers between "0 to 5" have been listed in this specification, and "0 to 5" is only a shortened expression of the combination of these numerical values. Also, when a certain parameter is expressed as an integer ≧ 2, it corresponds to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0029] Unless otherwise specified, all embodiments and alternative embodiments of this application can be combined with each other to form a new technical solution. Unless otherwise specified, all technical features and alternative technical features of this application can be combined with each other to form a new technical solution.

[0030] Unless otherwise specified, all steps of this application may be performed in order or randomly, and preferably, they are performed in order. For example, if a method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, if the mentioned method may further include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), etc.

[0031] Unless otherwise specified, the terms "include" and "comprise" mentioned in this application represent an open type and may also be a closed type. For example, "include" and "comprise" may further include or comprise other components not listed, or may include or comprise only the listed components.

[0032] Unless otherwise specified, the term "or" in this application is inclusive. For example, the phrase "A or B" represents "A, B, or both A and B". More specifically, any of the conditions where A is true (or exists) and B is false (or does not exist), where A is false (or does not exist) but B is true (or exists), and where both A and B are true (or exist) satisfy "A or B".

[0033] In this application, terms such as "a plurality of" and "various" refer to two or more.

[0034] Unless otherwise specified, the terms used in this application have the meanings known to those skilled in the art and generally understood.

[0035] Unless otherwise specified, the numerical values of each parameter mentioned in this application can be measured by various test methods commonly used in the art, for example, they can be measured according to the test methods shown in the examples of this application.

[0036] The term "alkyl group" includes straight-chain and branched-chain alkyl groups. For example, the alkyl group may be a C1-C50 alkyl group, a C1-C40 alkyl group, a C1-C30 alkyl group, a C1-C20 alkyl group, a C1-C12 alkyl group, a C1-C10 alkyl group, a C1-C6 alkyl group, a C1-C5 alkyl group, or a C1-C3 alkyl group. In some embodiments, the alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, etc. Also, the alkyl group may be optionally substituted.

[0037] The term "cycloalkyl group" refers to a cyclic structure composed of three or more carbon atoms. For example, the cycloalkyl group may be a C3-C50 cycloalkyl group, a C3-C40 cycloalkyl group, a C3-C30 cycloalkyl group, a C3-C20 cycloalkyl group, a C3-C12 cycloalkyl group, a C3-C10 cycloalkyl group, a C3-C6 cycloalkyl group, or a C3-C4 cycloalkyl group. In some embodiments, the cycloalkyl group includes a cyclopropyl group, a cycloisopropyl group, a cyclobutyl group, a cycloisobutyl group, a cyclotert-butyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, etc. Also, the cycloalkyl group may be optionally substituted.

[0038] The term "hydroxyalkyl group" refers to a group in which one hydrogen atom in an alkyl group is replaced by a hydroxyl group. For example, the hydroxyalkyl group may be a C1-C50 hydroxyalkyl group, a C1-C40 hydroxyalkyl group, a C1-C30 hydroxyalkyl group, a C1-C20 hydroxyalkyl group, a C1-C12 hydroxyalkyl group, a C1-C10 hydroxyalkyl group, a C1-C6 hydroxyalkyl group, a C1-C5 hydroxyalkyl group, or a C1-C3 hydroxyalkyl group. In some embodiments, the alkyl group includes a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, a hydroxyisopropyl group, a hydroxybutyl group, a hydroxyisobutyl group, a hydroxytert-butyl group, a hydroxypentyl group, a hydroxyhexyl group, a hydroxyheptyl group, a hydroxyoctyl group, etc. Further, the alkyl group may be optionally substituted.

[0039] The term "hydrogen" refers to 1H (protium, H), 2H (deuterium, D), or 3H (tritium, T). In each embodiment, "hydrogen" may be 1H (protium, H).

[0040] Throughout this specification, substituents of a compound are disclosed in groups or ranges. Such a description is clearly contemplated to include each individual sub-combination of members of these groups and ranges. For example, the term "C1-C8 alkyl group" alone clearly contemplates disclosure of C1, C2, C3, C4, C5, C6, C7, C8, C1-C8, C1-C7, C1-C6, C1-C5, C1-C4, C1-C3, C1-C2, C2-C8, C2-C7, C2-C6, C2-C5, C2-C4, C2-C3, C3-C8, C3-C7, C3-C6, C3-C5, C3-C4, C4-C8, C4-C7, C4-C6, C4-C5, C5-C8, C5-C7, C5-C6, C6-C8, C6-C7, and C7-C8 alkyl groups.

[0041] As another example, it is clearly anticipated that integers in the range of 5 to 40 alone disclose 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 and 40, and it is clearly anticipated that integers in the range of 1 to 20 alone disclose 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 and 20. Therefore, other groups or ranges can be clearly anticipated.

[0042] When the above group is substituted, the substituent may be a halogen atom or a heteroatom.

[0043] The term "halogen atom" refers to a fluorine atom, a chlorine atom, a bromine atom, etc.

[0044] The term "heteroatom" refers to a nitrogen atom, a sulfur atom, a phosphorus atom, etc.

[0045] Generally, a secondary battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. The separator is disposed between the positive electrode plate and the negative electrode plate, and mainly plays a role in preventing a short circuit between the positive electrode plate and the negative electrode plate, and can allow active ions to pass freely to form a circuit.

[0046] With the application and popularization of secondary batteries, people's requirements for the performance of secondary batteries (such as safety performance) are becoming increasingly high. The separator is an important component of the secondary battery, and the safety performance of the secondary battery can be improved by improving the performance of the separator.

[0047] According to the inventors' discovery, the adhesion of the separator in the related art is relatively poor, and the adhesion effect between the separator and the positive and negative electrode plates is bad. Generally, in order to enhance its adhesion, a coating containing a polymer is coated on the substrate. However, the polymer coating still has the problem of shrinking at high temperatures. Specifically, during long-term cyclic charge and discharge of a secondary battery, heat is released, and the temperature inside the secondary battery rises due to the heat. On the other hand, the separator has relatively poor heat resistance performance and a relatively high shrinkage rate at high temperatures. Therefore, the entire separator cannot play a good role in blocking the positive and negative electrode plates, thereby deteriorating the safety performance of the secondary battery. In addition, the separator also needs to satisfy the requirement of having good swelling resistance under the infiltration of the electrolyte solution. This is because if the separator is prone to swelling and the volume of the separator becomes relatively large, the positive and negative electrode plates may be compressed, which may have an adverse effect on the positive and negative electrode plates. As can be seen therefrom, it is difficult for the separator in the related art to balance adhesion, heat resistance performance, and swelling resistance.

[0048] To solve the above problems, from the perspective of improving the coating performance of the separator, the inventors improved the performance of the separator by forming the polymer by polymerizing monomers containing a polymer and having various functions, and then the technical solution of the present application will be described in detail.

[0049] Polymer According to a first aspect, the present application proposes a polymer, and the polymer includes a first structural unit, a second structural unit, and a third structural unit.

[0050] The first structural unit includes a structural unit represented by formula (I). In formula (I) of JPEG2025523973000010.jpg5494, R1 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group. Optionally, R1 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C3 alkyl group. R2 includes one or more of a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, and a substituted or unsubstituted C1-C20 hydroxyalkyl group. Optionally, R2 includes one or more of a C1-C12 alkyl group, a C3-C12 cycloalkyl group, and a C1-C12 hydroxyalkyl group.

[0051] The second structural unit includes the structural unit represented by formula (II). In formula (II), R3 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group. Optionally, R3 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C3 alkyl group.

[0052] The third structural unit includes the structural unit represented by formula (III). In formula (III), R4 to R 11 each independently includes one or more of a substituted or unsubstituted C1-C10 alkyl group and the structural units represented by formula (III-1), and at least one of R4 to R 11 includes the structural unit represented by formula (III-1). In formula (III-1), R 12 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group. Optionally, R 12 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C3 alkyl group. R 13 includes a substituted or unsubstituted C1-C10 alkyl group. Optionally, R 13 includes a substituted or unsubstituted C3-C10 alkyl group.

[0053] The polymer of the present application includes a first structural unit, a second structural unit, and a third structural unit, and it has good adhesiveness, stability, swelling resistance, heat resistance, etc.

[0054] Although the mechanism is not yet fully clear, the inventors of the present application speculate that the possible causes are as follows.

[0055] The first structural unit may be formed by the opening of a carbon-carbon double bond during the polymerization of an acrylate monomer. The flexible monomer chain segment in the molecular chain segment can adjust the glass transition temperature of the polymer and improve the toughness and peel strength of the polymer, thus contributing to the exertion of good adhesion.

[0056] The second structural unit may be formed by the opening of a carbon-carbon double bond during the polymerization of an acrylonitrile monomer. The second structural unit can generate excellent swelling resistance and high adhesiveness, and contribute to the improvement of the ion conductivity of the secondary battery. When the polymer is applied to the separator, the polymer is in contact with the electrolyte, and the polymer is difficult to swell, which has relatively good swelling resistance.

[0057] The third structural unit is formed by the polyhedral silsesquioxane containing a substituted or unsubstituted acryloxyalkyl group opening the carbon-carbon double bond of the substituted or unsubstituted acryloxy group during polymerization. The polyhedral silsesquioxane may be considered as a material including an organic-inorganic hybrid core-shell structure, with its internal inorganic framework as the core, that is, a skeletal structure composed of Si-O-Si or Si-O bonds. Its housing is composed of organic substituents (C1-C5 alkyl groups), and the organic substituents wrap around the outside of the skeletal structure and are connected to the Si element of the skeletal structure. The core structure of the polyhedral silsesquioxane can endow the polymer with advantages in terms of heat resistance and mechanical properties. Its shrinkage is relatively poor. During the long-term cycle charge and discharge of the secondary battery, it can guarantee the stability of the polymer and effectively block the positive and negative electrode plates, thereby guaranteeing the safety performance of the secondary battery. At the same time, the particle size of the polyhedral silsesquioxane is relatively small and the specific surface area is relatively large. On the physical scale, since it is close to many polymer chain segments, the atoms on the surface of the polyhedral silsesquioxane have relatively high reactivity. The polymer modified with the polyhedral silsesquioxane has properties such as relatively good heat resistance, flame retardancy, and oxidation resistance.

[0058] The above analysis is carried out based on each structural unit, but the synergistic effect between each structural unit cannot be ignored. Specifically, the cooperation between the first structural unit and the third structural unit can exert a synergistic effect and improve the adhesion performance and heat resistance of the polymer. The cooperation between the first structural unit and the second structural unit can exert a synergistic effect and improve the stability and swelling resistance of the polymer.

[0059] In some embodiments, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the first structural unit is A%, and 60 ≦ A < 100. When the molar content of the first structural unit is within the above range, its proportion in the polymer is relatively large. By improving the flexibility of the polymer, the adhesiveness of the polymer can be significantly improved. When the polymer is applied to a separator, the bonding strength between the polymer and the base material of the separator can be improved. Optionally, 60 ≦ A ≦ 80. Exemplarily, the molar content of the first structural unit may be 60%, 65%, 70%, 75%, 80%, or a range consisting of any two of the above numerical values.

[0060] In some embodiments, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the second structural unit is B%, and 0 < B ≦ 20. When the molar content of the second structural unit is within the above range, the stability of the polymer can be significantly improved. Optionally, 5 ≦ B ≦ 20. Exemplarily, the molar content of the second structural unit may be 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, or a range consisting of any two of the above numerical values.

[0061] In some embodiments, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the third structural unit is C%, and 0 < C ≦ 20. When the molar content of the third structural unit is within the above range, the heat resistance of the polymer can be guaranteed, and its proportion is relatively small, which is beneficial to improving the proportions of the first structural unit and the second structural unit and enhancing the performance of the polymer as a whole, such as adhesiveness, stability, and swelling resistance. Optionally, 5 ≦ C ≦ 20. Exemplarily, the molar content of the third structural unit may be 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, or a range consisting of any two of the above numerical values.

[0062] The polymer contains a first structural unit. The first structural unit imparts good adhesion and flexibility to the polymer. However, when the polymer is applied to the separator, it inevitably comes into contact with the electrolyte. Therefore, while the swelling effect of the electrolyte reduces the adhesion of the polymer to some extent, the polymer further contains a second structural unit. The cyano groups in the second structural unit exhibit a synergistic effect with the first structural unit, and can jointly improve the swelling resistance and adhesion performance of the polymer. In particular, when the present application further satisfies 3 ≤ A / B ≤ 16, the first structural unit can more fully exhibit the synergistic effect with the second structural unit, and can improve the adhesion, stability and swelling resistance of the polymer. Exemplarily, A / B may be 3, 4, 5, 8, 10, 12, 15, 16, or a range consisting of any two of the above numerical values.

[0063] The polymer contains a first structural unit. The first structural unit imparts good adhesion to the polymer, but its own heat resistance performance is relatively poor. When the polymer is applied to the separator, as the charge and discharge time of the secondary battery becomes longer, the temperature inside the secondary battery rises, which may lead to the destruction of the first structural unit. On the other hand, the polymer further contains a third structural unit. The inorganic structure of polysilsesquioxane in the third structural unit synergistically acts with the first structural unit, and can improve the heat resistance and adhesion performance of the whole polymer. In particular, when the present application further satisfies 3 ≤ A / C ≤ 16, the first structural unit can more fully exhibit the synergistic effect with the third structural unit, and can improve the adhesion performance and heat resistance performance of the polymer. Exemplarily, A / C may be 3, 4, 5, 8, 10, 12, 15, 16, or a range consisting of any two of the above numerical values.

[0064] In some embodiments, A:B:C is (12 to 16):(1 to 4):(1 to 4). When the molar contents of the first structural unit, the second structural unit, and the third structural unit satisfy the above ratio, the three types of structural units in the polymer act synergistically with each other, jointly improving the adhesiveness, stability, swelling resistance, and thermal stability of the polymer. Exemplarily, A:B:C may be 12:4:4, 13:4:3, 14:4:2, 15:4:1, 16:3:1, 13:3:4, or 15:1:4. The first structural unit includes various chemical structures, and the specific chemical structures of the first structural unit will be described next.

[0065] In some embodiments, R1 includes a hydrogen atom or a methyl group.

[0066] In some embodiments, R2 includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-octyl group, an isooctyl group, a 2-ethylhexyl group, a dodecyl group, or an isobornyl group.

[0067] Exemplarily, the first structural unit includes one or more of the structures shown by formula (I-1) to formula (I-8) such as JPEG2025523973000014.jpg121161.

[0068] The second structural unit includes various chemical structures, and the specific chemical structures of the second structural unit will be described next.

[0069] In some embodiments, R3 includes a hydrogen atom or a methyl group.

[0070] Exemplarily, the second structural unit includes one or more of the structures shown by formula (II-1) to formula (II-4) such as JPEG2025523973000015.jpg85170.

[0071] The third structural unit includes various chemical structures, and the specific chemical structures of the third structural unit will be described next.

[0072] In some embodiments, R4 to R 11 each independently includes the structural unit represented by formula (III-1), and optionally, R 12 is a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group or an n-pentyl group, and / or R 13 is an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-octyl group, an isooctyl group or a 2-ethylhexyl group.

[0073] In some embodiments, one of R4 to R 11 includes the structural unit represented by formula (III-1), and optionally, R 12 is a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group or an n-pentyl group, and / or R 13 is an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-octyl group, an isooctyl group or a 2-ethylhexyl group.

[0074] The types of groups in the polymer can be measured using infrared spectroscopy. For example, the types of modified groups can be determined by testing the infrared spectrum of the material and determining the characteristic peaks contained therein. Specifically, infrared spectroscopic analysis can be performed on the material using instruments and methods known in the art. For example, infrared spectroscopy (e.g., the IS10 type Fourier transform infrared spectrometer of Nicolet, USA) can be used to test according to the general rules of infrared spectroscopic analysis method GB / T6040-2019.

[0075] In some examples, in the infrared spectrum of the polymer, 1750 cm -1 ~1735 cm-1 has characteristic peaks that represent the presence of ester groups.

[0076] In some embodiments, in the infrared spectrum of the polymer, 2260 cm -1 ~2220 cm -1 has characteristic peaks that represent the presence of cyano groups.

[0077] In some embodiments, in the infrared spectrum of the polymer, 1100 cm -1 ~1120 cm -1 has characteristic peaks that represent the presence of the Si-O-Si backbone of silsesquioxane.

[0078] The inventors further discovered in their research that when specific parameters of the polymer are within a specific range, the adhesiveness and stability of the polymer can be significantly improved.

[0079] In some embodiments, the number average molecular weight of the polymer is from 20,000 to 80,000, and optionally from 30,000 to 50,000. Exemplarily, the number average molecular weight of the polymer may be 20,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000 or a range consisting of any two of the above numerical values. When the number average molecular weight of the polymer is within the above range, it is advantageous for the formation of polymer particles with relatively small particle sizes. When applied to a separator, a thin coating of the coating on the separator can be realized, and the overall thickness of the separator can be reduced, thereby easily increasing the energy density of the secondary battery. At the same time, the particle size of the polymer particles formed by the polymer is not too small, and the risk that the polymer particles block the substrate in the separator can be reduced, and the performance such as the air permeability of the entire separator can be improved.

[0080] The number average molecular weight of the polymer can be tested by gel permeation chromatography (GPC). Specifically, the test is carried out using a GPC1515 instrument from Waters, USA. The sample is dissolved in tetrahydrofuran with a dissolution time of 12 h or more, the sample concentration is 4 mg / ml, and the sample is prepared by filtration. The test is performed at a test temperature of 25°C and a test flow rate of 1 ml / min.

[0081] In further research, the inventors discovered that when the polymer is in particulate form and satisfies at least one of the following conditions, the adhesiveness, stability, swelling resistance, and heat resistance of the polymer can be further improved.

[0082] In some embodiments, the topography of the polymer includes spherical and / or quasi-spherical shapes. When the polymer is applied to the separator, the polymer exhibits a particulate form, and the spherical and / or quasi-spherical particulate shapes can ensure good wrapping between particles, and there are voids between the particles, which is advantageous for constructing a stable spatial network structure, thereby enhancing the ion transmission characteristics of the separator and the compressive resistance ability under external force. And the voids between the spherical and / or quasi-spherical particles are relatively large, which can mitigate the influence of the coating on the air permeability of the substrate, further improve the air permeability and ion conductivity of the entire separator, and enhance the kinetic performance of the secondary battery. Furthermore, the relatively large porosity between the spherical and / or quasi-spherical particles is advantageous for enhancing the wettability of the separator to the electrolyte and the liquid retention rate and liquid holding rate of the separator, further enhancing the kinetic performance of the secondary battery, and the relatively large porosity can achieve a weight reduction effect, which is advantageous for enhancing the energy density per unit weight of the secondary battery and can reduce the dosage of the polymer in the coating, which is advantageous for reducing the cost of the secondary battery.

[0083] The topography of the polymer can be observed by a scanning electron microscope (SEM). For example, using a JSM-5610LV type scanning electron microscope from FEI, USA, after vacuum gold spraying on the sample, the topography structure is observed.

[0084] In some embodiments, the volume - average particle size Dv50 of the polymer satisfies 0.1 μm ≤ Dv50 ≤ 2.0 μm, and optionally, 0.5 μm ≤ Dv50 ≤ 1.2 μm. When the particle size of the polymer is relatively small, it is advantageous for the uniform dispersion of the polymer when applying the polymer to the separator, and thus the performance of the membrane layer formed thereby is more uniform. Exemplarily, the volume - average particle size Dv50 of the polymer may be 0.1 μm, 0.2 μm, 0.5 μm, 0.8 μm, 1.0 μm, 1.2 μm, 1.5 μm, 2.0 μm, or a range consisting of any two of the above numerical values.

[0085] The volume - average particle size Dv50 of the polymer has the meaning known in the art and can be measured using instruments and methods known in the art. For example, referring to GB / T 19077 - 2016 Laser Diffraction Method for Particle Size Distribution, it can be tested using a laser particle size analyzer (such as Master Size 3000).

[0086] In some embodiments, let the specific surface area of the polymer be S, and its unit is m 2 / g, and 5.0 ≤ S ≤ 12.0, and optionally, 6.0 ≤ S ≤ 10.0. When the specific surface area of the polymer is within the above range, the specific surface area of the polymer is relatively large, which is advantageous for good wrapping between particles, makes it easier to form the pore structure between polymer particles, and is advantageous for the migration of active ions. Exemplarily, the specific surface area of the polymer may be 5.0 m 2 / g, 5.5 m 2 / g, 6.0 m 2 / g, 7.0 m 2 / g, 8.0 m 2 / g, 9.0 m 2 / g, 10.0 m 2 / g, 11.0 m 2 / g, 12.0 m 2 / g, or a range consisting of any two of the above numerical values.

[0087] The specific surface area of the polymer is a meaning known in the art and can be measured using instruments and methods known in the art. For example, referring to GB / T 19587-2017, it can be tested using the nitrogen gas adsorption specific surface area analysis test method and calculated by the BET (Brunauer Emmett Teller) method. Optionally, the nitrogen gas adsorption specific surface area analysis test may be performed using a Tri-Star 3020 specific surface area pore size analyzer from Micromeritics, USA.

[0088] Method for manufacturing a polymer According to a second aspect, the present application provides a method for manufacturing a polymer. The method can be used to manufacture the polymer of any one of the examples of the first aspect of the present application.

[0089] The method includes the following steps: Step S100: Provide a first monomer, a second monomer, and a third monomer. Step S200: Mix the first monomer, the second monomer, and the third monomer, and generate a polymerization reaction under the action of an initiator to produce a polymer.

[0090] In the present application, after mixing the first monomer, the second monomer, and the third monomer, copolymerization is carried out, and the formed polymer is a copolymer of the three types of monomers.

[0091] The first monomer includes a compound represented by formula (IV). JPEG2025523973000016.jpg5990In formula (IV), R1 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group. Optionally, R1 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C3 alkyl group. R2 contains one or more of a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, and a substituted or unsubstituted C1-C20 hydroxyalkyl group. Optionally, R2 contains one or more of a C1-C12 alkyl group, a C3-C12 cycloalkyl group, and a C1-C12 hydroxyalkyl group.

[0092] The first monomer is an acrylate compound, and when it is polymerized, the carbon-carbon double bond is opened to form a first structural unit.

[0093] Exemplarily, the first monomer contains one or more of methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-pentyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.

[0094] The second monomer contains a compound represented by formula (V). In formula (V), R3 contains one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group. Optionally, R3 contains one or more of a hydrogen atom and a substituted or unsubstituted C1-C3 alkyl group.

[0095] The second monomer is an acrylonitrile compound, and when it is polymerized, the carbon-carbon double bond is opened to form a second structural unit.

[0096] Exemplarily, the second monomer includes acrylonitrile and / or methacrylonitrile.

[0097] The third monomer includes a compound represented by formula (VI). JPEG2025523973000018.jpg88146In formula (VI), R 30 ~R 37 are each independently a substituted or unsubstituted C1-C10 alkyl group, include one or more of the structural units represented by formula (VI-1), and R 30 ~R 37 at least one of which is a structural unit represented by formula (VI-1). JPEG2025523973000019.jpg51117In formula (VI-1), R 12 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group, and optionally, R 12 includes one or more of a hydrogen atom and a substituted or unsubstituted C1-C3 alkyl group. R 13 includes a substituted or unsubstituted C1-C10 alkyl group, and optionally, R 13 includes a substituted or unsubstituted C3-C10 alkyl group.

[0098] Exemplarily, the third monomer includes one or more of methacryloxypropyl cage-type polysilsesquioxane, methacryloxypropyl heptaisobutyl polysilsesquioxane, acryloxypropyl cage-type polysilsesquioxane, acryloxypropyl heptaisobutyl polysilsesquioxane, and methacryloxypropyl heptaoctyl polysilsesquioxane.

[0099] In some embodiments, step S200 specifically includes the following steps. Step S210: Add the first monomer, the second monomer, and the third monomer to a solvent and an emulsifier, and mix them to form a mixed system. Step S220: Add an initiator to the mixed system, and cause a polymerization reaction to occur under the action of the initiator to generate a polymer.

[0100] This application can copolymerize various monomers by means of emulsion polymerization, and the polymerization method is more convenient. Of course, this application can also adopt other polymerization means, such as solution polymerization, suspension polymerization, etc., and the process parameters adopted in the polymerization process can be selected from the parameters commonly used in the art, and will not be described further here.

[0101] In some embodiments, the emulsifier includes one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, alkyldiphenyloxide disulfonate, and ethoxylated alkylphenol ammonium sulfate.

[0102] In some embodiments, based on the total mass of the mixed system, the ratio of the mass percentage content of the emulsifier to the mass percentage contents of the first monomer, the second monomer, and the third monomer is from 0.1% to 5%, that is, the dosage of the emulsifier is from 0.1% to 5% of the total mass of the three kinds of monomers. When the mass percentage content of the emulsifier is within the above range, the first monomer, the second monomer, and the third monomer can be emulsified and dispersed in the solvent to form a relatively uniform system.

[0103] In some embodiments, the initiator includes potassium persulfate and / or ammonium persulfate.

[0104] In some embodiments, based on the total mass of the mixed system, the ratio of the mass percentage content of the initiator to the mass percentage contents of the first monomer, the second monomer, and the third monomer is from 0.15% to 1%, that is, the dosage of the initiator is from 0.1% to 5% of the total mass of the three kinds of monomers. When the mass percentage content of the initiator is within the above range, sufficient polymerization can be guaranteed.

[0105] In some embodiments, the solvent may include water, such as deionized water.

[0106] As a specific embodiment, the method includes the following, Manufacture of prepolymer: Deionized water, an emulsifier, a first polymerization monomer, a second polymerization monomer, and a third polymerization monomer are blended and stirred uniformly to obtain a prepolymer. Manufacture of polymer: An emulsifier and deionized water are added to a container and stirred for 30 min to 60 min for emulsification to obtain a uniform and stable emulsion. Then, the prepolymer produced in the previous step and an initiator solution (dissolving potassium persulfate and / or ammonium persulfate as the initiator in deionized water to form a solution) are slowly dropped respectively. After the dropping is completed, the temperature is raised to 90°C to 110°C, and a heat preservation reaction is carried out for 0.5 h. After cooling to 40°C and adjusting the pH to 7 - 8 with ammonia water, filtration and discharging are carried out, and a polymer is prepared through a drying process.

[0107] Separator According to a third aspect, the present application proposes a separator.

[0108] The separator includes a base material and a coating disposed on at least one surface of the base material. The coating includes the polymer described in any one of the examples of the first aspect of the present application or the polymer obtained by manufacturing according to the method described in any one of the examples of the second aspect of the present application. Since the polymer has excellent adhesiveness, stability, swelling resistance, heat resistance, etc., when it is applied to the coating of the separator, the adhesiveness, stability, swelling resistance, heat resistance, etc. of the whole separator can be significantly improved.

[0109] In some examples, based on the mass of the coating, the mass percentage content of the polymer is m%, where m ≥ 70, and optionally, 80 ≤ m ≤ 95. When the mass percentage content of the polymer is within the above range, the adhesiveness, stability, swelling resistance, heat resistance, etc. of the whole separator can be further improved. The mass percentage content m% of the polymer may be 70%, 80%, 85%, 86%, 88%, 90%, 92%, 95%, 98%, 99% or a range consisting of any two of the above numerical values.

[0110] This application is not particularly limited with respect to the material of the substrate, and a substrate having any known good chemical stability and mechanical stability, such as at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride, may be selected. The substrate may be a single-layer film or a multi-layer composite film. When the substrate is a multi-layer composite film, the materials of each layer may be the same or different.

[0111] In some embodiments, the coating may further include a filler. Further, the filler may include at least one of inorganic particles and organic particles.

[0112] In some embodiments, the decomposition temperature of the filler may be 200 °C or higher, whereby the filler can have good thermal stability and be difficult to decompose, and further can further enhance the heat resistance of the separator.

[0113] Inorganic particles have high thermal stability and are difficult to decompose. In some embodiments, optionally, the inorganic particles include at least one of inorganic particles having a dielectric constant of 5 or more, inorganic particles having ion conductivity but not storing ions, and inorganic particles capable of generating an electrochemical reaction.

[0114] Optionally, the inorganic particles having a dielectric constant of 5 or more include boehmite, aluminum oxide, zinc oxide, silicon oxide, titanium oxide, zirconium oxide, barium oxide, calcium oxide, magnesium oxide, nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hectorite, zirconium titanate, barium titanate, Pb(Zr,Ti)O3 (abbreviated as PZT), Pb 1-m La m ZR1-n Ti n O3 (abbreviated as PLZT, 0 < m < 1, 0 < n < 1), Pb(Mg3Nb 2 / 3 )O3 - PbTiO3 (abbreviated as PMN - PT), and includes at least one of each modified inorganic particle. Optionally, the modification method of each inorganic particle may be chemical modification and / or physical modification. The chemical modification method includes coupling agent modification (for example, using silane coupling agent, titanate coupling agent, etc.), surfactant modification, polymer graft modification, etc. The physical modification method may be mechanical force dispersion, ultrasonic dispersion, high - energy treatment, etc. The modification treatment can reduce the aggregation of inorganic particles, thereby constructing a more stable and uniform spatial network structure with nanocellulose. Additionally, by selecting a coupling agent, surfactant or polymer - modified inorganic particle with specific functional groups, it also contributes to enhancing the wetting property of the coating with respect to the electrolyte and increasing the adhesion strength between the coating and the substrate.

[0115] Optionally, the inorganic particles that have ion conductivity but do not store ions are Li3PO4, lithium titanium phosphate Li x1 Ti y1 (PO4)3, lithium aluminum titanium phosphate Li x2 Al y2 Ti z1 (PO4)3, (LiAlTiP) x3 O y3 - type glass, lithium lanthanum titanate Li x4 La y4 TiO3, lithium germanium thiophosphate Li x5 Ge y5 P z2 S w , lithium nitride Li x6 N y6 , SiS2 - type glass Li x7 Si y7 S z3 and P2S5 - type glass Li x8 P y8 S z4including at least one of them, where 0 < x1 < 2, 0 < y1 < 3, 0 < x2 < 2, 0 < y2 < 1, 0 < z1 < 3, 0 < x3 < 4, 0 < y3 < 13, 0 < x4 < 2, 0 < y4 < 3, 0 < x5 < 4, 0 < y5 < 1, 0 < z2 < 1, 0 < w < 5, 0 < x6 < 4, 0 < y6 < 2, 0 < x7 < 3, 0 < y7 < 2, 0 < z3 < 4, 0 < x8 < 3, 0 < y8 < 3, 0 < z4 < 7. Thereby, the ion transmission characteristics of the separator can be further enhanced.

[0116] Optionally, the inorganic particles capable of generating the electrochemical reaction include at least one of lithium-containing transition metal oxides, lithium-containing phosphates, carbon-based materials, silicone-based materials, tin-based materials, and lithium titanium compounds.

[0117] The organic particles have good thermal stability and are difficult to decompose, thereby enhancing the heat resistance of the separator. When the internal temperature of the secondary battery reaches the melting point of the organic particles due to overcharge abuse, thermal abuse, etc., the organic particles melt and are sucked into the fine holes of the base material by capillary action, and can also play a role in blocking the holes, thereby being advantageous for ensuring that the secondary battery has high safety performance.

[0118] In some embodiments, the organic particles include, but are not limited to, at least one of polyethylene particles, polypropylene particles, polystyrene particles, melamine resin particles, phenol resin particles, polyester particles (such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate), polyimide particles, polyamideimide particles, polyaramid particles, polyphenylene sulfide particles, polysulfone particles, polyether sulfone particles, polyether ether ketone particles, polyaryl ether ketone particles, and copolymers of butyl acrylate and ethyl methacrylate (such as cross-linked polymers of butyl acrylate and ethyl methacrylate).

[0119] In some embodiments, optionally, the glass transition temperature of the organic particles may be 130° C. or higher. Thereby, when the internal temperature of the secondary battery reaches 130° C., the organic particles do not transition from the glassy state to the viscous flow state, thereby ensuring that the separator does not shrink rapidly. Further optionally, the organic particles include, but are not limited to, at least one of melamine formaldehyde resin particles, phenol resin particles, polyester particles, polyimide particles, polyamideimide particles, polyaramide particles, polyphenylene sulfide particles, polysulfone particles, polyether sulfone particles, polyether ether ketone particles, and polyaryl ether ketone particles.

[0120] In some embodiments, the coating further includes an adhesive. The present application is not particularly limited with respect to the type of adhesive, and any known material having good adhesiveness may be selected. By way of example, the adhesive includes at least one of an aqueous acrylic resin (e.g., a copolymer of acrylic acid, methacrylic acid, sodium acrylate monomer homopolymer, or other copolymer monomers), polyvinyl alcohol, an isobutylene-maleic anhydride copolymer, and polyacrylamide.

[0121] Optionally, the content of the adhesive in the coating is <30% based on the mass of the coating.

[0122] In some embodiments, the separator may further include an adhesive layer, the adhesive layer is disposed on at least a part of the surface of the coating, and the adhesive layer includes an adhesive. The adhesive layer can not only prevent the coating from peeling off and improve the safety performance of the secondary battery, but also improve the interface between the separator and the electrode and enhance the cycle performance of the secondary battery.

[0123] Optionally, the adhesive contains at least one of an acrylate monomer homopolymer or copolymer, an acrylic acid monomer homopolymer or copolymer, and a fluorine-containing olefin monomer homopolymer or copolymer. The copolymer monomer includes, but is not limited to, at least one of an acrylate monomer, an acrylic acid monomer, an olefin monomer, a halogen-containing olefin monomer, and a fluoroether monomer.

[0124] Optionally, the adhesive contains a vinylidene fluoride polymer, such as a homopolymer of vinylidene fluoride monomer (VDF) and / or a copolymer of vinylidene fluoride monomer and other copolymer monomers. The other copolymer monomers may include at least one of an olefin monomer, a fluorine-containing olefin monomer, a chlorine-containing olefin monomer, an acrylate monomer, an acrylic acid monomer, and a fluoroether monomer. Optionally, the other copolymer monomers may include at least one of trifluoroethylene (VF3), trifluorochloroethylene (CTFE), 1,2-difluoroethylene, tetrafluoroethylene (TFE), hexafluoropropylene (HFP), perfluoro(alkyl vinyl) ether (such as perfluoro(methyl vinyl) ether PMVE, perfluoro(ethyl vinyl) ether PEVE, perfluoro(propyl vinyl) ether PPVE), perfluoro(1,3-dioxole), and perfluoro(2,2-dimethyl-1,3-dioxole) (PDD).

[0125] In some embodiments, the longitudinal thermal shrinkage rate of the separator at 150 °C for 1 h is η1 ≤ 5.0%, and optionally, 0.5% ≤ η1 ≤ 3%.

[0126] In some embodiments, the transverse thermal shrinkage rate of the separator at 150 °C for 1 h is η2 ≤ 5.0%, and optionally, 0.5% ≤ η2 ≤ 2%.

[0127] The separator of the present application can further improve the safety performance of the secondary battery by having a low thermal shrinkage rate in both the horizontal and vertical directions under a high temperature of 150°C.

[0128] In some embodiments, the tensile strength of the separator in the vertical direction is R m1 ≥ 3000 kg / cm 2 and, optionally, 3500 kg / cm 2 ≤ R m1 ≤ 4500 kg / cm 2 is.

[0129] In some embodiments, the tensile strength of the separator in the horizontal direction is R m2 ≥ 3000 kg / cm 2 and, optionally, 3500 kg / cm 2 ≤ R m2 ≤ 4500 kg / cm 2 is.

[0130] The separator of the present application has a high tensile strength in both the horizontal and vertical directions, so that when the secondary battery expands, the probability of damage to the separator is relatively small, thereby further improving the safety performance of the secondary battery.

[0131] In some embodiments, the air permeability of the separator is MAP ≤ 250 s / 100 mL, and, optionally, 120 s / 100 mL ≤ MAP ≤ 180 s / 100 mL. The separator of the present application can improve the ion transmission characteristics by having good air permeability.

[0132] In some embodiments, the wetting length of the separator is L ≥ 30 mm, and, optionally, 30 mm ≤ L ≤ 80 mm.

[0133] In some embodiments, the wetting rate of the separator is u ≥ 3 mm / s, and, optionally, 3 mm / s ≤ u ≤ 10 mm / s.

[0134] The separator of the present application has good electrolyte infiltration characteristics, thereby enhancing ion transmission characteristics and the capacity performance of the secondary battery.

[0135] The thermal shrinkage rate, tensile strength, and air permeability of the separator all have meanings known in the art and can be measured using methods known in the art. For example, they can all be tested with reference to the standard GB / T 36363-2018.

[0136] The wetting length and wetting speed of the separator both have meanings known in the art and can be measured using methods known in the art. An exemplary test method is as follows: that is, the separator is cut into samples with a width of 5 mm and a length of 100 mm. After fixing both ends of the sample and placing it horizontally, 0.5 mg of electrolyte is taken and dropped onto the center of the sample. After reaching a predetermined time (1 min in the present application), a photo is taken to measure the diffusion length of the electrolyte, thereby obtaining the wetting length and wetting speed of the separator. To ensure the accuracy of the test results, multiple (for example, 5 to 10) samples can be taken for testing, and the test results can be obtained by calculating the average value. The electrolyte may be prepared according to the following method: that is, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a mass ratio of 30:50:20 to obtain an organic solvent, and sufficiently dried LiPF6 is dissolved in the above organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0137] It should be noted that the coating parameters (such as surface density, thickness, etc.) of the above separator are all the coating parameters on one side of the substrate. When the coating is installed on both sides of the substrate, if the coating parameters on either one side meet the requirements of the present application, it is considered to fall within the protection scope of the present application.

[0138] Method for manufacturing a separator According to a fourth aspect, the present application further provides a method for manufacturing a separator. The method may be used to manufacture the separator of any one of the embodiments of the third aspect of the present application.

[0139] The method includes the following steps: Step S10: Provide a substrate. Step S20: Manufacture a coating slurry: Mix a polymer in a predetermined mass with a solvent to prepare the coating slurry. Step S30: Coating: Apply the coating slurry onto at least one surface of the substrate, form a coating and dry it to obtain a separator, where the separator includes a substrate and a coating disposed on at least one surface of the substrate.

[0140] The polymer in step S20 may employ the polymer of any one of the embodiments of the first aspect of the present application, or the polymer obtained by manufacturing according to the method described in any one of the embodiments of the second aspect of the present application.

[0141] In some embodiments, in step S20, the solvent may be water, for example, deionized water.

[0142] In some embodiments, in step S20, the coating slurry may further include other components, for example, it may further include a dispersant, a wetting agent, an adhesive, etc.

[0143] In some embodiments, in step S20, the solid content of the coating slurry may be controlled between 28% and 45%, for example, between 30% and 38%. When the solid content of the coating slurry is within the above range, the film surface problem of the coating can be effectively reduced, and the probability of coating non-uniformity can be reduced, thereby further improving the energy density and safety performance of the secondary battery.

[0144] In some embodiments, in step S30, the coating is performed using a coater. The present application does not impose any special restrictions on the model number of the coater. For example, a commercially available coater may be used. The coater includes a gravure roll, and the gravure roll is used to transfer the coating slurry onto the substrate.

[0145] In some embodiments, in step S30, the coating method may employ transfer roll coating, rotary spraying, dip coating, etc.

[0146] In some embodiments, the method further includes the following steps.

[0147] Step S40, secondary coating: A slurry containing an adhesive is applied onto at least a part of the surface of the coating, and after drying, an adhesive layer is formed. Optionally, the coating method employs rotary spraying.

[0148] The method for manufacturing the separator of the present application simplifies the production process flow of the separator significantly by preparing the coating through primary coating.

[0149] For parameters such as some of the raw materials used in the method for manufacturing the separator of the present application and their contents, reference may be made to the separator in the first aspect of the embodiments of the present application, and no further explanation will be given here.

[0150] Unless otherwise specified, each of the raw materials used in the method for manufacturing the separator of the present application can be obtained commercially.

[0151] Secondary battery According to a fifth aspect, the present application further provides a secondary battery.

[0152] A secondary battery, also called a rechargeable battery or a storage battery, is a battery that can continue to be used by activating the active material in a charging manner after discharging. Generally, a secondary battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. The separator is installed between the positive electrode plate and the negative electrode plate, mainly serving to prevent short circuit between the positive electrode and the negative electrode and allowing active ions to pass through.

[0153] This application is not particularly limited to the type of secondary battery. For example, the secondary battery may be a lithium-ion battery, a sodium-ion battery, etc. In particular, the secondary battery may be a lithium-ion secondary battery.

[0154] The secondary battery described in this application includes a separator of the third aspect of this application or a separator manufactured by the method of the fourth aspect of the embodiment of this application. The separator is separated between the positive electrode plate and the negative electrode plate. Optionally, at least the side of the separator close to the negative electrode plate has the coating of this application. Further, the side of the separator close to the positive electrode plate has the coating of this application, and the side of the separator close to the negative electrode plate also has the coating of this application, whereby the safety performance of the secondary battery of this application can be improved.

[0155] [Positive electrode plate] In some embodiments, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer installed on at least one surface of the positive electrode current collector and containing a positive electrode active material. For example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode film layer is installed on either one or both of the two opposing surfaces of the positive electrode current collector.

[0156] When the secondary battery of the present application is a lithium ion battery, the positive electrode active material may include, but is not limited to, at least one of lithium-containing transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of the lithium-containing transition metal oxides may include, but are not limited to, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds. Examples of the lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, and their respective modified compounds.

[0157] In some embodiments, in order to further improve the energy density of the secondary battery, the positive electrode active material used in the lithium ion battery may include at least one of lithium transition metal oxides represented by the general formula Li a Ni b Co c M d O e A f and their modified compounds. 0.8 ≦ a ≦ 1.2, 0.5 ≦ b < 1, 0 < c < 1, 0 < d < 1, 1 ≦ e ≦ 2, 0 ≦ f ≦ 1, M includes at least one of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A includes at least one of N, F, S, and Cl.

[0158] For example, the positive electrode active material used in the lithium ion battery may be LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523), LiNi0.6 Co 0.2 Mn 0.2 O2 (NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), LiNi 0.85 Co 0.15 Al 0.05 It may contain at least one of O2, LiFePO4, and LiMnPO4.

[0159] When the secondary battery of this application is a sodium-ion battery, the positive electrode active material may contain, but is not limited to, at least one of sodium transition metal oxides, polyanion materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue-based materials.

[0160] As an example, the positive electrode active materials used in sodium-ion batteries include NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue-based materials, materials with the general formula X p M’ q (PO4) r O x Y 3-x It may contain at least one of the materials represented by the formula. In the general formula X p M’ q (PO4) r O x Y 3-x , 0 < p ≤ 4, 0 < q ≤ 2, 1 ≤ r ≤ 3, 0 ≤ x ≤ 2, and X is H + , Li + , Na + , K + and NH4 +including at least one of them, M’ is a transition metal cation, selectively at least one of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, Y is a halogen anion, selectively at least one of F, Cl and Br.

[0161] In this application, the modified compound of each of the above positive electrode active materials may be obtained by doping and / or surface coating modification of the positive electrode active material.

[0162] In some embodiments, the positive electrode film layer further selectively includes a positive electrode conductive agent. This application is not particularly limited to the type of the positive electrode conductive agent. For example, the positive electrode conductive agent includes at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene and carbon nanofiber. In some embodiments, based on the total mass of the positive electrode film layer, the mass percentage content of the positive electrode conductive agent is ≤5%.

[0163] In some embodiments, the positive electrode film layer further selectively includes a positive electrode adhesive. This application is not particularly limited to the type of the positive electrode adhesive. For example, the positive electrode adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin. In some embodiments, based on the total mass of the positive electrode film layer, the mass percentage content of the positive electrode adhesive is ≤5%.

[0164] In some embodiments, the positive current collector may employ a metal foil sheet or a composite current collector. As an example of the metal foil sheet, an aluminum foil may be employed. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0165] The positive electrode film layer is generally obtained by applying a positive electrode slurry to a positive current collector, followed by drying and cold pressing. The positive electrode slurry is generally formed by dispersing a positive electrode active material, a selective conductive agent, a selective adhesive, and any other components in a solvent and uniformly stirring them. The solvent may be N-methylpyrrolidone (NMP), but is not limited thereto.

[0166] [Negative electrode plate] In some embodiments, the negative electrode plate includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector and containing a negative electrode active material. For example, the negative current collector has two opposing surfaces in its thickness direction, and the negative electrode film layer is disposed on either one or both of the two opposing surfaces of the negative current collector.

[0167] The negative electrode active material may employ a negative electrode active material for a secondary battery known in the art. By way of example, the negative electrode active material may include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate. The silicon-based material may include at least one of silicon alone, silicon oxide, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy material. The tin-based material may include at least one of tin alone, tin oxide, and a tin alloy material.

[0168] In some embodiments, the negative electrode film layer further selectively includes a negative electrode conductive agent. The present application is not particularly limited with respect to the type of the negative electrode conductive agent. By way of example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, based on the total mass of the negative electrode film layer, the mass percentage content of the negative electrode conductive agent is ≤5%.

[0169] In some embodiments, the negative electrode film layer further selectively includes a negative electrode adhesive. The present application is not particularly limited with respect to the type of the negative electrode adhesive. By way of example, the negative electrode adhesive may include at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, aqueous acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, based on the total mass of the negative electrode film layer, the mass percentage content of the negative electrode adhesive is ≤5%.

[0170] In some embodiments, the negative electrode film layer further selectively contains other auxiliary agents. By way of example, the other auxiliary agents may include thickeners such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, and the like. In some embodiments, based on the total mass of the negative electrode film layer, the mass percentage content of the other auxiliary agents is ≤ 2%.

[0171] In some embodiments, the negative electrode current collector may employ a metal foil sheet or a composite current collector. By way of example, a copper foil may be employed as the metal foil sheet. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. By way of example, the metal material may include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. By way of example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0172] The negative electrode film layer is generally obtained by applying a negative electrode slurry to a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is generally formed by dispersing a negative electrode active material, a selective conductive agent, a selective adhesive, and a selective other auxiliary agent in a solvent and uniformly stirring them. The solvent may be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.

[0173] The negative electrode plate does not exclude other additional functional layers other than the negative electrode film layer. For example, in some embodiments, the negative electrode plate described in the present application further includes a conductive undercoating (for example, composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. Also, in some embodiments, the negative electrode plate described in the present application further includes a protective layer covering the surface of the negative electrode film layer.

[0174] [Electrolyte solution] During the charge and discharge of the secondary battery, active ions are reversibly occluded and released between the positive electrode plate and the negative electrode plate, and the electrolyte plays a role of conducting active ions between the positive electrode plate and the negative electrode plate. The present application is not particularly limited to the type of electrolyte and can be selected according to actual needs.

[0175] The electrolyte contains an electrolyte salt and a solvent. The types of the electrolyte salt and the solvent are not specifically limited and can be selected according to actual needs.

[0176] When the secondary battery of the present application is a lithium-ion battery, for example, the electrolyte salt may include at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP), but is not limited thereto.

[0177] When the secondary battery of the present application is a sodium-ion battery, for example, the electrolyte salt may include, but is not limited to, at least one of sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluoro(oxalato)borate (NaDFOB), sodium bis(oxalato)borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluoro bis(oxalato)phosphate (NaDFOP), and sodium tetrafluoro(oxalato)phosphate (NaTFOP).

[0178] For example, the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0179] In some embodiments, the electrolytic solution further selectively contains additives. For example, the additives may include negative electrode film-forming additives, may include positive electrode film-forming additives, and may further include additives that can improve some performances of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature performance of the battery, additives that improve the low-temperature power performance of the battery, and the like.

[0180] In some embodiments, the positive electrode plate, the separator and the negative electrode plate may be used to fabricate an electrode assembly by a winding process and / or a stacking process.

[0181] In some embodiments, the secondary battery may include an outer package. This outer package may be used to package the above electrode assembly and electrolytic solution.

[0182] In some embodiments, the outer package of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, or the like. The outer package of the secondary battery may be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0183] This application is not particularly limited to the shape of the secondary battery, and it may be cylindrical, square, or any other arbitrary shape. FIG. 1 shows a secondary battery 5 with a square structure as an example.

[0184] In some embodiments, as shown in FIG. 2, the exterior body may include a case 51 and a cover plate 53. The case 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose and form an accommodation cavity. The case 51 has an opening communicating with the accommodation cavity, and the cover plate 53 is used to cover the opening to seal the accommodation cavity. The positive electrode plate, the negative electrode plate and the separator may form an electrode assembly 52 through a winding process and / or a lamination process. The electrode assembly 52 is packaged in the accommodation cavity. The electrolyte is infiltrated into the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and may be adjusted according to demand.

[0185] The method for manufacturing the secondary battery of the present application is known. In some embodiments, a secondary battery can be formed by assembling a positive electrode plate, a separator, a negative electrode plate and an electrolyte. As an example, a positive electrode plate, a separator, and a negative electrode plate are formed into an electrode assembly through a winding process and / or a lamination process, the electrode assembly is placed in an exterior body, dried, and then an electrolyte is injected, and through processes such as vacuum packaging, standing, formation, and shaping, a secondary battery can be obtained.

[0186] In some embodiments of the present application, the secondary battery according to the present application may be assembled into a battery module, and the number of secondary batteries included in the battery module may be plural, and the specific number may be adjusted according to the application and capacity of the battery module.

[0187] FIG. 3 is a schematic diagram of a battery module 4 as an example. As shown in FIG. 3, in the battery module 4, a plurality of secondary batteries 5 may be arranged in sequence along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other arbitrary manner. Further, these plurality of secondary batteries 5 may be fixed by fastening members.

[0188] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of secondary batteries 5 are accommodated in this accommodation space.

[0189] In some embodiments, the battery module may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0190] FIG. 4 and FIG. 5 are schematic diagrams of a battery pack 1 as an example. As shown in FIGS. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3. The upper housing 2 covers the lower housing 3 and is used to form a sealed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0191] Power consumption device The sixth aspect of the embodiment of the present application provides a power consumption device, and the power consumption device includes at least one of the secondary battery, battery module or battery pack of the present application. The secondary battery, battery module or battery pack may be used as a power source of the power consumption device, and may also be used as an energy storage unit of the power consumption device. The power consumption device may be a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0192] The power consumption device can select a secondary battery, a battery module or a battery pack according to its usage requirements.

[0193] FIG. 6 is a schematic diagram of a power consumption device as an example. This power consumption device is, for example, a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the demand for high power and high energy density of this power consumption device, a battery pack or a battery module can be adopted.

[0194] Another example of a power consumption device may be a mobile phone, a tablet computer, a notebook computer, etc. This power consumption device generally requires thinning and can adopt a secondary battery as a power source.

[0195] Example The following examples describe more specifically the content disclosed by this application. Since various modifications and changes within the scope of the content disclosed by this application will be obvious to those skilled in the art, these examples are only descriptive explanations. Unless otherwise specified, all parts, percentages, and ratios reported in the following examples are all based on mass, and all reagents used in the examples can be obtained commercially or synthesized by ordinary methods and can be used directly without further treatment, and all instruments used in the examples can be obtained commercially.

[0196] Manufacture of Polymer Example A Prepolymer production 1400 g of deionized water and 7 g of sodium dodecyl sulfate were added to a 5 L three-necked flask, stirred at a rotation speed of 1500 r / min for 30 min to emulsify and obtain a uniform and stable emulsion. Then, 645.68 g of methyl acrylate, 79.59 g of acrylonitrile, and 663.50 g of methacryloxypropyl cage-type polysilsesquioxane (the molar content ratio of methyl acrylate, acrylonitrile, and methacryloxypropyl cage-type polysilsesquioxane is 15:3:2) were added in sequence, and stirring was continued at a rotation speed of 1500 r / min for 30 min to obtain a uniform prepolymer.

[0197] Polymer production Add 3 g of emulsifier and 1000 g of deionized water to a dried three-necked flask, stir at high speed for 30 min for emulsification to obtain a uniform and stable emulsion, and then use a peristaltic pump to slowly dropwise add the prepolymer and initiator solution produced in the previous step (dissolve 3 g of potassium persulfate as the initiator in 30 g of deionized water to form a solution) respectively. After the dropping is completed, raise the temperature to 90 °C and keep it warm for 0.5 h for reaction, cool to 40 °C, adjust the pH to 7 - 8 with ammonia water, then filter, discharge, and produce the polymer through a drying process.

[0198] Examples B - E The polymer was produced using a method similar to that of Example A, and the difference from Example A was that at least one of the raw material components and their contents was adjusted.

[0199] The relevant parameters for polymer production are as shown in Table 1 and Table 2.

[0200] Example 1 Manufacture of separator Provision of PE substrate: The thickness is 7 μm, the porosity is 40%, and the ion conductivity is 1.20 mS / cm.

[0201] Preparation of coating slurry: The polymer produced in Example A above and aqueous solution type polyacrylic acid as the adhesive were uniformly mixed in an appropriate amount of deionized water as the solvent at a mass ratio of 90:10 to obtain a coating slurry.

[0202] Coating: The prepared coating slurry was coated on two surfaces of the PE substrate with a coater, and after drying and slitting processes, a separator was obtained. The areal density of the coating located on one side of the PE substrate is 0.9 g / m 2 and the thickness is 0.45 μm.

[0203] Manufacture of positive electrode plate Cathode active material LiNi 0.8 Co 0.1 Mn 0.1O2 (NCM811), carbon black (Super P) as the conductive agent, and polyvinylidene fluoride (PVDF) as the binder were uniformly mixed in a proper amount of solvent N-methylpyrrolidone (NMP) at a mass ratio of 96.2:2.7:1.1 to obtain a positive electrode slurry. The positive electrode slurry was coated on a positive electrode current collector aluminum foil, and after processes such as drying, cold pressing, stripping, and cutting, a positive electrode plate was obtained. The surface density of the positive electrode plate was 0.207 mg / mm 2 and the tap density was 3.5 g / cm 3 as follows.

[0204] Manufacture of negative electrode plate Artificial graphite as the negative electrode active material, carbon black (Super P) as the conductive agent, and styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC) as the binder were uniformly mixed in a proper amount of solvent deionized water at a mass ratio of 96.4:0.7:1.8:1.1 to obtain a negative electrode slurry. The negative electrode slurry was coated on a negative electrode current collector copper foil, and after processes such as drying, cold pressing, stripping, and cutting, a negative electrode plate was obtained. The surface density of the negative electrode plate was 0.126 mg / mm 2 and the tap density was 1.7 g / cm 3 as follows.

[0205] Manufacture of electrolyte Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 30:70 to obtain an organic solvent. Thoroughly dried LiPF6 was dissolved in the above organic solvent to prepare an electrolyte solution with a concentration of 1 mol / L.

[0206] Manufacture of secondary battery The positive electrode plate, separator, and negative electrode plate were stacked and wound in sequence to obtain an electrode assembly. The electrode assembly was placed in an outer package, and after drying, the electrolyte solution was injected. After processes such as vacuum packaging, standing, formation, and shaping, a secondary battery was obtained.

[0207] Comparative Example, Examples 2 to 15 The secondary battery was manufactured using a method similar to that of Example 1, with the difference being that the manufacturing parameters of the separator were different. The details of the specific parameters are as shown in Table 3.

[0208] Example 16 The secondary battery was manufactured using a method similar to that of Example 1, with the difference being the manufacturing method of the coating slurry. Specifically, the polymer manufactured in Example A above, aluminum oxide filler (average particle size Dv50 is 300 nm), and aqueous solution type polyacrylic acid as the adhesive were uniformly mixed in a mass ratio of 80:15:5 in an appropriate amount of solvent deionized water to obtain a coating slurry with a solid content of 35 wt%.

[0209] Test section 1. Adhesion test between separator and positive electrode plate The battery positive electrode plate and the separator were overlapped and placed in a hot press machine. As the parameters of the hot press machine, the temperature was set to 25 °C, the pressure was set to 10 t, and the time was set to 30 s. The separator / positive electrode plate sample was made by applying pressure for adhesion, and the separator / electrode plate sample was cut into a rectangular spline of 150×20 mm. One side of the positive electrode plate of the above rectangular spline was attached to the steel plate through a double-sided adhesive, and at one end of the rectangular spline, the separator was separated from the positive electrode plate by a length of 2 cm along the longitudinal direction to make a test sample.

[0210] The steel plate was held horizontally and fixed with the lower jig of a universal testing machine (manufactured by Xieqiang Instrument Manufacturing (Shanghai) Co., Ltd., model number CTM2100). The peeled end of the separator described above was fixed with the upper jig of the universal testing machine, and a tensile machine was connected. As the test conditions, the tensile rate was set to 20 mm / min and the horizontal tension was set to 10 cm. After the tensile force was stabilized, the tensile force value was recorded, and the adhesion force between the separator and the electrode plate was obtained from the ratio of the tensile force value to the sample width.

[0211] 2. Thermal shrinkage rate test of separator Sample production: The separator manufactured above was punched into samples with a width of 50 mm and a length of 100 mm using a press, five parallel samples were taken and placed on A4 paper, and the A4 paper with the samples was further placed on cardboard with a thickness of 1 mm to 5 mm.

[0212] Sample test: The temperature of the forced-air oven was set to 150 °C. After the temperature reached the set temperature and stabilized for 30 min, the A4 paper placed on the cardboard was put into the forced-air oven, timing was started. After reaching the set time (1 h in this application), the length and width of the separator were measured, and the numerical values were denoted as a and b respectively.

[0213] Calculation of thermal shrinkage rate: The thermal shrinkage rate in the longitudinal direction (MD) = [(100 - a) / 100] × 100%, and the thermal shrinkage rate in the transverse direction (TD) = [(50 - b) / 50] × 100%. The average value of the five parallel samples was taken as the test result.

[0214] 3. Heat box test of secondary battery At 25 °C, the secondary battery was charged at a constant current of 1 C until 4.2 V, and then charged at a constant voltage until the current ≤ 0.05 C. After standing for 5 min, each secondary battery was tested with a jig in a DHG-9070A DHG series high-temperature oven. The temperature was raised from room temperature to 80 ± 2 °C at a rate of 5 °C / min and held for 30 min, and then the temperature was raised at a rate of 5 °C / min. Every time the temperature was raised by 5 °C, it was kept warm for 30 min until the secondary battery failed. During the temperature rise, the surface temperature change of the secondary battery was monitored. The corresponding oven temperature when the rapid temperature rise started was the heat box failure temperature of the secondary battery. The higher the heat box failure temperature of the secondary battery, the better the thermal safety performance of the secondary battery was shown.

[0215]

Table 1

[0216]

Table 2

[0217]

Table 3

[0218] As can be seen from Tables 1 to 3, the polymer of Comparative Example 1 includes a first structural unit and a second structural unit. When the separator adopted the polymer, its adhesion performance was relatively good, but the heat box failure temperature of the secondary battery was relatively low, and thermal runaway was likely to occur. The polymer of Comparative Example 2 includes a first structural unit and a third structural unit. When the separator adopted the polymer, its heat resistance performance was improved to a certain extent, but the adhesion performance of the separator was relatively poor.

[0219] On the other hand, the polymers of Examples 1 to 16 include a first structural unit, a second structural unit, and a third structural unit, and it was possible to achieve both improvement in the heat resistance performance, adhesion performance, and swelling resistance performance of the polymer. By adjusting the molar content of the three structural units, the performance of the polymer can be adjusted and controlled to a certain extent. In particular, when 3≤A / B≤16, 3≤A / C≤16 and / or A:B:C is (12 - 16):(1 - 4):(1 - 4), the performance of the polymer can be further enhanced. In Examples 15 to 17, the polymer had good heat resistance performance, and when its content was relatively high, the heat resistance performance of the separator was relatively good. Inorganic particles, such as aluminum oxide, can also further enhance the heat resistance performance of the separator as a heat resistance auxiliary material.

[0220] The present application has been described with reference to the preferred embodiments, but it can be variously improved without departing from the scope of the present application, and members thereof can be replaced with equivalents. In particular, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any manner. The present application is not limited to the specific embodiments disclosed in this specification, but includes all technical solutions within the scope of the claims.

Description of Reference Numerals

[0221] The description of the symbols is as follows. 1. Battery pack, 2. Upper housing, 3. Lower housing, 4. Battery module, 5. Secondary battery, 51. Case, 52. Electrode assembly, 53. Cover plate, 6. Power consumption device.

Claims

1. A polymer comprising a first structural unit, a second structural unit, and a third structural unit, wherein the first structural unit comprises a structural unit shown in formula (I): In formula (I), R １ contains one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group; R ２ comprises one or more of a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, and a substituted or unsubstituted C1 to C20 hydroxyalkyl group; The second structural unit comprises a structural unit represented by formula (II): In formula (II), R ３ contains one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group; The third structural unit includes a structural unit represented by formula (III): In formula (III), R ４ ~R １１ each independently comprises one or more of a substituted or unsubstituted C1 to C10 alkyl group, a structural unit represented by formula (III-1), and R ４ ~R １１ At least one of the above contains a structural unit represented by formula (III-1): In formula (III-1), R １２ contains one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group; R １３ comprises a substituted or unsubstituted C1-C10 alkyl group; A polymer having a volume distribution particle size Dv50 that satisfies 0.1 μm≦Dv50≦2.0 μm.

2. R １ contains a hydrogen atom or a methyl group, and / or R ２ 2. The polymer of claim 1, wherein comprises a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-octyl group, an isooctyl group, a 2-ethylhexyl group, a dodecyl group, or an isobornyl group.

3. R ３ The polymer of claim 1 , wherein comprises a hydrogen atom or a methyl group.

4. The R ４ ~R １１ each independently contains a structural unit represented by formula (III-1), and R １２ contains a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, or an n-pentyl group, and / or R １３ contains an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-octyl group, an isooctyl group or a 2-ethylhexyl group, or The R ４ ~R １１ One of the structural units represented by formula (III-1) is R １２ contains a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, or an n-pentyl group, and / or R １３ The polymer of claim 1, wherein comprises an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-octyl group, an isooctyl group, or a 2-ethylhexyl group.

5. The molar content of the first structural unit is A%, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, and is 60≦A<100; and / or The molar content of the second structural unit is B%, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, and is 0<B≦20; and / or The polymer according to claim 1, wherein the molar content of the third structural unit is C%, based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, and C% is 0<C≦20.

6. Based on the total molar amount of the first structural unit, the second structural unit, and the third structural unit, the molar content of the first structural unit is A%, the molar content of the second structural unit is B%, and the molar content of the third structural unit is C%, and the polymer is (1) 3≦A / B≦16; (2) 3≦A / C≦16; (3) A:B:C is (12-16):(1-4):(1-4).

7. 2. The polymer of claim 1, wherein the number average molecular weight of the polymer is from 20,000 to 80,000.

8. The polymer is in particulate form, and the polymer comprises: (I) the topography of the polymer comprises spherical and / or near-spherical shapes; (II) The specific surface area of ​​the polymer is S, and its unit is m ２ / g and 5.0≦S≦12.

0.

9. 1. A method for producing a polymer, comprising: providing a first monomer, a second monomer, and a third monomer; mixing the first monomer, the second monomer, and the third monomer and causing a polymerization reaction under the action of an initiator to produce a polymer; wherein the first monomer comprises a compound represented by formula (IV): In formula (IV), R １ contains one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group; R ２ comprises one or more of a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, and a substituted or unsubstituted C1 to C20 hydroxyalkyl group; The second monomer comprises a compound represented by formula (V): In formula (V), R ３ contains one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group; The third monomer comprises a compound represented by formula (VI): In formula (VI), R ３０ ~R ３７ each independently comprises one or more of a substituted or unsubstituted C1 to C10 alkyl group, a structural unit represented by formula (VI-1), and R ３０ ~R ３７ At least one of the above contains a structural unit represented by formula (VI-1): In formula (VI-1), R １２ contains one or more of a hydrogen atom and a substituted or unsubstituted C1-C5 alkyl group; R １３ A method for producing a polymer comprising a substituted or unsubstituted C1 to C10 alkyl group, wherein the polymer has a volume distribution particle size Dv50 that satisfies 0.1 μm≦Dv50≦2.0 μm.

10. The step of mixing the first monomer, the second monomer and the third monomer and causing a polymerization reaction under the action of an initiator to produce a polymer includes: adding the first monomer, the second monomer and the third monomer to a solvent and an emulsifier and mixing to form a mixed system; and adding the initiator to the mixed system and causing a polymerization reaction under the action of the initiator to produce the polymer.

11. the first monomer comprises one or more of methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-pentyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate; the second monomer comprises acrylonitrile and / or methacrylonitrile; and / or 10. The method of claim 9, wherein the third monomer comprises one or more of methacryloxypropyl polysilsesquioxane, methacryloxypropyl heptaisobutyl polysilsesquioxane, acryloxypropyl polysilsesquioxane, acryloxypropyl heptaisobutyl polysilsesquioxane, and methacryloxypropyl heptaoctyl polysilsesquioxane.

12. A separator comprising a substrate and a coating disposed on at least one surface of the substrate, the coating comprising the polymer of claim 1.

13. 13. The separator according to claim 12, wherein the mass percentage content of the polymer is m%, based on the mass of the coating, and m≧70.

14. The separator is (A) The thermal shrinkage rate of the separator in the longitudinal direction at 150°C for 1 hour is η １ ≦5.0%; (B) The thermal shrinkage rate of the separator in the transverse direction at 150°C for 1 hour is η ２ ≦5.0%; (C) The separator has a longitudinal tensile strength of R ｍ１ ≧3000kg / cm ２ That is, (D) The tensile strength in the lateral direction of the separator is R ｍ２ ≧3000kg / cm ２ That is, (E) the separator has an air permeability of MAP≦250 s / 100 mL; (F) the wetted length of the separator is L≧30 mm; (G) The separator according to claim 12, wherein the separator satisfies one or more of the following conditions: (i) a wetting speed of the separator is u≧3 mm / s.

15. A secondary battery comprising the separator according to claim 12.

16. A power consuming device comprising the secondary battery of claim 15.

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