Polymers and their production, Electrolyte membranes and their production

Abstract

The present application provides a polymer obtained by polymerizing Monomer 1, Monomer 2, and Monomer 3. Monomer 1 has a structure of Formula 1, Monomer 2 has a structure of Formula 2, and Monomer 3 has a structure of Formula 3. R1, R2, R3, R4, R5, Rf, x, A + , Q - , E is as defined in the specification. The present application further provides a polymer electrolyte membrane comprising an interpenetrating network formed of a polymer and a carbonate polymer. The polymer electrolyte membrane according to the present application has excellent mechanical strength, improved ionic conductivity and ionic mobility, and a battery produced therefrom has excellent high-pressure resistance and high-pressure cycle performance. [C15] JPEG2025515203000024.jpg58134

Description

[Technical field]

[0001] The present application relates to a polymer. The present application further relates to an electrolyte membrane including the polymer, a secondary battery including the electrolyte membrane, a battery pack including the secondary battery, a battery module, and a power consuming device. [Background technology]

[0002] In recent years, as the application scope of lithium ion batteries becomes more and more extensive, lithium ion batteries are widely used in energy storage power systems such as hydroelectric power stations, thermal power stations, wind power stations and solar power stations, as well as in multiple fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. Lithium ion batteries have made great progress, which has put forward higher requirements for their electrolytes.

[0003] Most current commercially available lithium batteries use organic liquid electrolytes, which have high ionic conductivity (10 -3 S / cm) and high wettability of the electrode surface. However, organic liquid electrolytes have disadvantages such as easy flow, easy volatility, and low thermal stability, which greatly limits the room for improving the safety of lithium batteries. Meanwhile, the rapid development of modern society has put forward higher requirements for the energy density and cycle life of batteries. Therefore, high specific capacity (e.g., 3860 mAh / g), extremely low potential (e.g., -3.04 V vs. H2 / H + Lithium metal anodes with a ionic conductivity type (CuO) have been attracting the attention of scientific researchers again. However, the high reactivity of lithium and the short circuit problem of lithium dendrites are insurmountable obstacles to the development of lithium metal. The emergence of solid electrolytes has broken this obstacle. The use of solid electrolytes instead of organic liquid electrolytes not only fundamentally solves the safety problems of batteries, but also brings the possibility of further development of lithium metal batteries.

[0004] The use of aluminum-based polymer as a solid polymer electrolyte membrane in a lithium metal secondary battery is currently an efficient means. However, the high-pressure resistance and safety performance of this solid polymer electrolyte membrane still have room for improvement. Therefore, there is still a need to provide a solid electrolyte membrane that has relatively high mechanical strength, good high-pressure resistance properties, and excellent flame retardant performance. Summary of the Invention

[0005] The present application has been made in view of the above problems, and an object of the present application is to provide a polymer that has excellent flame retardancy, is resistant to oxidation under high pressure, can improve ionic conductivity and lithium ion mobility when used as an electrolyte membrane material, and is suitable for a high-voltage battery system, and a method for producing the same. The present application also provides a solid electrolyte membrane including the polymer, which has good interfacial contact with an electrode, relatively high ionic conductivity, excellent high-temperature stability, and excellent mechanical performance, and a method for producing the same. The present application also provides a secondary battery including the electrolyte membrane.

[0006] Accordingly, a first aspect of the present application provides a polymer, the polymer being comprised of monomer 1, monomer 2, and monomer 3 polymerized, wherein monomer 1 has a structure of formula 1, monomer 2 has a structure of formula 2, and monomer 3 has a structure of formula 3, [ka] Where: R1 and R3 are each independently hydrogen or C 1-10 alkyl groups, R4 is C 1-10 C containing one or more of the following elements: hydrocarbon group, fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus 1-10 is selected from a hydrocarbon group; R2 and R5 are each independently hydrogen or C 1-10a hydrocarbon group or a C=C or C≡C-containing hydrocarbon group having 10 or less carbon atoms and containing one or more of the elements fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus; Rf is selected from an ethoxy segment having up to 16 carbon atoms of hydrogen or one or more of the elements fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus; x is the number of repeating methylene units, and 0≦x≦20; A + is one selected from functional groups having nitrogen, sulfur, or phosphorus as a cation center, Q - is one, two or more anions selected from halogen ions, halogen borates, halogen oxaloborates, perhalogenates, halogen phosphates, and halogen sulfonimide salts; and optionally Q - is one, two or more anions selected from chloride, tetrafluoroborate, difluorooxaloborate, perchlorate, hexafluorophosphate, and bis(fluorosulfonyl)imide salt; E is selected from the structures (1) to (3), [ka] where R6 is hydrogen or C 1-10 The alkyl group is selected from the group consisting of aryl, ... and alkyl groups.

[0007] The polymer according to the present application is formed by polymerizing three types of monomers (monomer 1, monomer 2, and monomer 3), has an ethyl group as the main chain, and contains functional groups such as an ionic group (derived from monomer 1), an amide (derived from monomer 1), a phosphate ester (derived from monomer 2), and a fluorinated ethoxy group (derived from monomer 3) in its molecular structure. Each of these functional groups provides a different function to the polymer. At present, for example, the presence of the ionic group and fluorine element (mainly derived from monomer 3) is believed to be advantageous in improving the oxidation resistance or high pressure stability (especially at high pressures above 5 V) of the material. When the polymer is used as an electrolyte membrane material in a secondary battery, the flexible ethoxy side chains in the polymer can drive the migration of lithium ions, and the cationic center in the ionic group can interact with the anion in the lithium salt to increase the number of lithium ions moving. Due to the synergistic effect of the phosphate ester group derived from monomer 2 and the fluorine element (mainly derived from monomer 3), the electrolyte containing the polymer exhibits excellent flame retardant properties, which can be applied to lithium secondary batteries to improve the safety of the batteries. The amide derived from monomer 1 provides a relatively strong hydrogen bonding force between polymer molecules, and the presence of the relatively strong hydrogen bonding force and the construction of a crosslinked network centered on the phosphate ester (derived from monomer 2) are advantageous in enhancing the mechanical performance of the polymer material.

[0008] Optionally, the polymer has a triblock structure, which can block the contact between the ethoxy side chains and reduce the crystallinity of the polymer material, which can be used in the electrolyte membrane to improve the ionic conductivity.

[0009] In any embodiment, the substitution rate of elemental fluorine in the Rf group is greater than 29.0%, and the substitution rate of elemental fluorine is the ratio of the number of fluorine atoms based on the number of substitutable hydrogen atoms in the Rf group.

[0010] The "number of substitutable hydrogen atoms" should be understood as the number of substitutable sites in the Rf group, i.e., the maximum number of hydrogen atoms bonded to carbon atoms, phosphorus atoms, nitrogen atoms, and sulfur atoms present in this group. When the hydrogen atoms have already been substituted with other elements, such as halogen atoms, the number of substitutable hydrogen atoms is calculated as the sum of the number of hydrogen atoms and the number of other atoms substituted therewith.

[0011] By ensuring that the fluorine substitution rate is 29.0% or more, the flame retardant performance of the polymer can be ensured, while the high-voltage stability and high-voltage cycle performance of a battery obtained by using the polymer can be improved.

[0012] In any embodiment, the polymer comprises a cation A + is one selected from the structural formulas (4) to (6). [ka]

[0013] In any embodiment, in the polymer, the molar ratio of Monomer 1 is in the range of 3.7 to 92.6 mol %, the molar ratio of Monomer 2 is in the range of 2.0 to 33.3 mol %, and the molar ratio of Monomer 3 is in the range of 3.7 to 92.6 mol %, based on the total number of moles of Monomer 1, Monomer 2, and Monomer 3; Alternatively, the molar ratio of monomer 1 to monomer 2 is in the range of 1:1 to 25:1; More preferentially, the molar ratio of monomer 3 to monomer 2 is in the range of 1:1 to 25:1.

[0014] In either embodiment, the thermal conductivity coefficient of the polymer is in the range of 0.06 to 0.35 W / mK, and the flame retardant level is 94V-0 or 94V-1.

[0015] A second aspect of the present application provides a method for producing the polymer according to the first aspect of the present application, comprising the steps of: dissolving the monomer 1, the monomer 2, the monomer 3 and an initiator in a solvent, reacting them under vacuum at 30-100°C for 0.2-24 hours, optionally for 6-24 hours, and then drying. The polymer is in the form of a block copolymer. Optionally, the drying is carried out under vacuum at 25-140°C for 1-48 hours. The main purpose of drying is to remove the solvent remaining after the reaction.

[0016] A third aspect of the present application provides a polymer electrolyte membrane, comprising a polymer according to the first aspect of the present application or a polymer produced by the method according to the second aspect of the present application.

[0017] In either embodiment, the polymer electrolyte membrane further comprises a second polymer, the second polymer being dispersed in the polymer and forming an interpenetrating network, the second polymer being formed from Monomer 4, the general formula structure of which is: [ka]

[0018] wherein R7 is selected from hydrogen or a hydrocarbon group having less than 7 carbon atoms, unsubstituted or substituted with one or more of the elements fluorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus.

[0019] As described above, the "hydrocarbon group having fewer than 7 carbon atoms" includes, but is not limited to, alkyl groups having fewer than 7 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, isopropyl, isobutyl, tert-butyl, isopentyl, tert-pentyl, neopentyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, alkenyl groups having fewer than 7 carbon atoms, such as ethylene, propylene, butene, butadiene, pentene, pentadiene, hexene, hexadiene, and alkynyl groups having fewer than 7 carbon atoms, such as acetylene, propyne, butyne, pentyne, hexyne, and the like. The hydrocarbon groups having less than 7 carbon atoms may be unsubstituted, mono- or polysubstituted with one or more of the elements fluorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron and phosphorus.

[0020] In this application, the second polymer is intended to be in contrast to and distinct from the aforementioned polymer.

[0021] The second polymer described in this application is an oligomer, which has a carbonate backbone and a number average molecular weight M n<2000 Da, viscosity less than 3000 cP, and has a certain fluidity. The second polymer may be called a carbonate polymer. The oligomer is uniformly dispersed in the network of the polymer as a second polymer network, and the presence of the carbonate backbone in the second polymer network ensures the high pressure stability of the formed electrolyte membrane and contributes to the excellent high pressure resistance performance of the secondary battery containing the electrolyte membrane. The second polymer in the interpenetrating network structure has a certain fluidity and can act to wet the electrode plate, thereby improving the interfacial contact between the electrolyte membrane and the positive and negative electrodes. Therefore, in the interpenetrating network solid electrolyte membrane including the network formed by the polymer and the network formed by the second polymer, the introduction of the second polymer network having fluidity not only improves the wetting performance between the electrolyte membrane and the electrodes and improves the interfacial contact between the electrolyte membrane and the positive and negative electrodes, but also ensures the relatively high ionic conductivity of the electrolyte membrane because the segment motion of the carbonate can drive the movement of lithium ions.

[0022] In some alternative embodiments, the electrolyte membrane containing the interpenetrating network described herein is suitable for a high voltage battery system, such as a 5V high voltage battery system. 0.8 Co 0.1 Mn 0.1 O2, LiCoO2, LiMn2O4, LiNiCoAlO2, LiNi 0.5 Mn 1.5 This includes, but is not limited to, battery systems such as O4.

[0023] Optionally, in the interpenetrating network, the weight ratio of the polymer to the second polymer is from 20:1 to 2:1.

[0024] In any embodiment, the polymer electrolyte membrane further comprises a lithium salt, the lithium salt being one or more selected from lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium difluoro(oxalato)borate (LiDFOB), lithium perchlorate (LiClO), and lithium bis(oxalato)borate (LiBOB).

[0025] The type of lithium salt affects the number of lithium ion transfers in the polymer electrolyte membrane. Different lithium salts have different structures, so there are differences in the degree of dissociation between anions and cations. Lithium salts with a high degree of dissociation can provide more carriers, and Li + The concentration of affects the "coordination-dissociation" process between the ether oxygen atoms and carbonyl groups in the polymer chain, and also affects the Li + In general, PEO-based electrolytes affect the mobility of Li and anions in the battery. + Polydentate chelation of the ether oxygen atom with TFSI - Relatively weak solvent interactions with the anion result in migration numbers smaller than 0.2.

[0026] In any embodiment, the mass proportion of the lithium salt in the polymer electrolyte membrane is in the range of 6.8 to 30.0% based on the total mass of the polymer electrolyte membrane.

[0027] In any of the embodiments, the content ratio of elemental fluorine in the polymer electrolyte membrane is within a range of 12.5 to 46.0% based on the total weight of the polymer electrolyte membrane.

[0028] In order to ensure the dual properties of high pressure resistance and flame retardancy of the electrolyte membrane prepared using the polymer, the substitution of fluorine element in the Rf group of the polymer can optimally maintain a ratio of 29.0% or more. In the polymer electrolyte membrane prepared using the polymer, the content ratio of fluorine element is finally controlled within the above range, which is more favorable to realize the high pressure resistance and flame retardancy of the electrolyte membrane.

[0029] A third aspect of the present application provides a method for producing a polymer electrolyte membrane, comprising the steps of:

[0030] Monomer 1, monomer 2, monomer 3, and monomer 4 described above in the present application, the lithium salt described above in the present application, an optional catalyst, and an initiator are reacted at 30 to 100° C. for 0.2 to 24 hours to obtain product 1.

[0031] It is currently believed that in this step, Monomer 1, Monomer 2, and Monomer 3 undergo a coblock polymerization reaction in the presence of an initiator to form the polymer, and Monomer 4 undergoes an ionic copolymerization reaction in the presence of a lithium salt and an optional catalyst to form a flowable second polymer.

[0032] In either embodiment, the method of producing the polymer electrolyte membrane further comprises the step of anion-exchanging the obtained product 1 with a solution of a lithium salt to obtain product 2.

[0033] After anion exchange, the anion Q associated with the ionic group in the formed polymer - , e.g., the corroding Cl of aluminum foil - can be replaced by a target anion, optionally with the same type of anion as that in the lithium salt, in this way, on the one hand, it is possible to prevent some side reactions from occurring, and on the other hand, it is also possible to adjust the binding ability between the anion and the polymer, the lithium ion.

[0034] In any embodiment, the method of producing a polymer electrolyte membrane described in the present application further comprises drying the resulting product 2.

[0035] The purpose of drying is to remove residual solvent. Drying may be performed by any means conventionally used in the art, as long as the purpose of removing the solvent is achieved and the electrolyte membrane is not decomposed. Drying may be performed using a vacuum oven.

[0036] In any embodiment, in the method for producing a polymer electrolyte membrane described in the present application, the ratio of the total mass of Monomer 1, Monomer 2, and Monomer 3 to the mass of Monomer 4 is 20:1 to 2:1.

[0037] In any embodiment, in the method for producing a polymer electrolyte membrane described in the present application, the mass ratio of the total mass of the monomer 1, monomer 2, monomer 3, and monomer 4 to the lithium salt is within a range of 2.3 to 13.6.

[0038] In any embodiment, in the method for producing a polymer electrolyte membrane described herein, the weight ratio of the lithium salt to the initiator is 5:1 to 60:1, and when a catalyst is used, the ratio of the sum of the weights of the lithium salt and catalyst to the weight of the initiator is 7:1 to 80:1.

[0039] The initiator may be used to initiate the block copolymerization reaction of the polymer described in this application, and the lithium salt and catalyst may be used to initiate the ionic polymerization reaction of the second polymer, and the ratio of the two may reflect in a certain sense the distribution of the two polymers produced and the structural composition of the interpenetrating network.

[0040] It is currently believed that the polymer described in this application is prepared by block copolymerization and initiated by an initiator. The second polymer is prepared by ionic polymerization catalyzed by a lithium salt and an optional catalyst. The monomers of the two polymers are mixed together, but each is prepared separately and does not interfere with each other. And because each monomer, initiator, and optional catalyst are uniformly mixed in solution before carrying out the polymerization reaction, the result after complete polymerization is an interpenetrating network structure in which the polymer network and the second polymer network are uniformly interpenetrated, and the lithium salt is uniformly dispersed therein.

[0041] Optionally, in any embodiment, the present application provides a solid electrolyte membrane produced by the above method of producing a solid polymer electrolyte membrane.

[0042] A fifth aspect of the present application provides a secondary battery, comprising a positive electrode, a negative electrode, and further comprising a polymer electrolyte membrane according to the third aspect of the present application or a polymer electrolyte membrane produced by the method according to the fourth aspect of the present application. The secondary battery, battery module, battery pack, and power consumption device of the present application are described below.

[0043] In any embodiment, the positive electrode includes a positive electrode current collector and a positive electrode film layer, the positive electrode film layer includes a positive electrode active material, the second polymer, and the lithium salt. Optionally, the mass ratio of the second polymer in the positive electrode film layer is 2 to 15%, and optionally, the mass ratio of the lithium salt in the positive electrode film layer is 0.5 to 10%.

[0044] The use of the second polymer in the positive electrode membrane has the following advantages: the voids inside the positive electrode membrane are filled with the fluid second polymer and lithium salt, and the fluid second polymer not only acts to wet the inside of the plate, but at the same time, the movement of its segments further provides channels for the lithium ions to transport inside the plate, thereby enhancing the ion transport inside the positive electrode membrane.

[0045] In any of the embodiments, in the secondary battery, the negative electrode includes a negative electrode current collector and a metal sheet formed of lithium metal or a lithium alloy.

[0046] The polymer electrolyte membrane described in this application has a high specific capacity (3860 mAh / g), an extremely low potential (-3.04 V vs. H2 / H + ) in combination with a lithium metal anode, a lithium alloy anode, or no anode. Optionally, the thickness of the anode plate is 9 to 50 μm.

[0047] The lithium alloy includes, but is not limited to, a lithium aluminum alloy, a lithium magnesium alloy, a lithium boron alloy, and the like.

[0048] In any of the embodiments, in the secondary battery, the polymer electrolyte membrane has a thickness of 10 to 1000 μm.

[0049] A sixth aspect of the present application provides a battery module, the battery module including the secondary battery according to the fifth aspect of the present application.

[0050] A seventh aspect of the present application provides a battery pack, the battery pack including the battery module according to the sixth aspect of the present application.

[0051] An eighth aspect of the present application provides a power consumption device, the power consumption device including at least one selected from the secondary battery according to the fifth aspect of the present application, the battery module according to the sixth aspect of the present application, or the battery pack according to the seventh aspect of the present application. [Brief description of the drawings]

[0052] [Figure 1] 1 is a schematic diagram of an interpenetrating network of a polymer described in the present application and a second polymer, where the dots represent lithium salts and two distinct random lines represent the polymer and the second polymer, respectively. [Diagram 2]FIG. 2 is a charge / discharge curve diagram of a battery core (i.e., a battery obtained after matching positive and negative electrodes) when a high-voltage cycle performance test is performed on the solid electrolyte membrane produced in Example 1. [Diagram 3] FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application. [Figure 4] FIG. 4 is an exploded view of the secondary battery shown in FIG. 3 according to an embodiment of the present application. [Diagram 5] FIG. 1 is a schematic diagram of a battery module according to an embodiment of the present application. [Figure 6] FIG. 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Figure 7] FIG. 7 is an exploded view of the battery pack shown in FIG. 6 according to an embodiment of the present application. [Figure 8] 1 is a schematic diagram of a power consuming device powered by a secondary battery according to an embodiment of the present application; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] Hereinafter, the embodiments specifically disclosing the polymer, polymer electrolyte membrane, lithium battery, and manufacturing method thereof of the present application will be described in detail with appropriate reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters and repeated description of structures that are actually the same may be omitted. This is to avoid the following description becoming unnecessarily redundant and to allow those skilled in the art to easily understand. Note that the drawings and the following description are provided to allow those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0054] The "ranges" disclosed in this application are defined in the form of lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive, and may be arbitrarily combined, i.e., any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also envisaged. It is noted that if 1 and 2 are listed as minimum range values, and 3, 4 and 5 are listed as maximum range values, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 are all envisaged. In this application, unless otherwise specified, the numerical range "ab" represents a shorthand representation of any combination of real numbers a to b, where a and b are both real numbers. For example, the numerical range "0-5" represents a listing of all real numbers between "0-5" in this specification, and "0-5" is only a shorthand for combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. In this specification, when expressing a range, "~" and "-" have the same meaning.

[0055] Unless otherwise stated, all the embodiments and optional embodiments in the present application can be combined with each other to form a new technical solution.

[0056] Unless otherwise stated, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0057] Unless otherwise stated, all steps in this application may be performed in sequence or randomly, and preferably in sequence. For example, the method includes steps (a) and (b) to mean that the method may include steps (a) and (b) performed in sequence, or may include steps (b) and (a) performed in sequence. For example, the method mentioned above may further include step (c) to mean that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), etc.

[0058] Unless otherwise stated, the terms "comprise" and "comprises" referred to in this application may be open ended or closed ended. For example, the terms "comprise" and "comprises" may further include or include other ingredients not listed, or may include or include only the listed ingredients.

[0059] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, "A or B" is satisfied in any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) but B is true (or exists); and A and B are both true (or exist).

[0060] Solid-state batteries can be divided into four types according to the chemical system of the solid electrolyte: polymer, sulfide, oxide, and chloride. Polymer solid electrolytes, represented by polyoxyethylene (PEO), were commercialized in the 1990s due to their advantages of good interfacial infiltration, excellent processing performance, light weight and low density, and low cost. However, the voltage window of most such polymer electrolytes is relatively low (e.g., PEO ∽ 3.9 V), and they are difficult to match with high-voltage positive electrodes, which greatly limits the improvement of the energy density of batteries, and at the same time, the flammable properties of polymers make it impossible to meet the high safety requirements of next-generation batteries.

[0061] One example of a current high-pressure-resistant solid electrolyte membrane is manufactured using a modified aluminum-based polymer. This electrolyte membrane is manufactured by homogeneously mixing a modified aluminum-based polymer, a branched polymer, and an electrolyte solution, adding a photoinitiator, and crosslinking under stirring conditions. A secondary battery having this electrolyte membrane has a relatively high conductivity and can achieve a stable cycle at 4.2V. In addition, since this polymer has a crosslinked structure, it can provide a relatively high mechanical strength to the solid electrolyte membrane and reduce the occurrence of dendrites, thereby improving the safety of lithium metal secondary batteries. However, this modified aluminum-based polymer membrane has a polyester-based structure, which does not withstand high pressure, and there is a limit to improving the high-pressure stability after aluminum-based formation. Secondly, this modified aluminum-based polymer membrane contains an inorganic component and has a crosslinked structure, which improves mechanical performance, but affects the interface contact between the solid electrolyte membrane manufactured thereby and the positive and negative electrodes. In addition, this solid electrolyte membrane is focused only on its high-pressure resistance characteristics, and is not involved in the safety performance of the material itself, such as flame retardancy.

[0062] Surprisingly, the present application provides a new polymer, which has good flame retardant performance by itself, and can form an interpenetrating network structure with other polymers, and when a polymer having this structure is used as an electrolyte membrane, it can provide better mechanical strength, and a secondary battery manufactured using this electrolyte membrane can have better safety performance, better high-pressure stability and better high-pressure cycle performance, and can realize better interfacial contact between the electrolyte membrane and the positive and negative electrodes.

[0063] Accordingly, a first aspect of the present application provides a polymer, the polymer being formed by polymerizing Monomer 1, Monomer 2, and Monomer 3, where Monomer 1 has a structure of Formula 1, Monomer 2 has a structure of Formula 2, and Monomer 3 has a structure of Formula 3, [ka] Here, R1 and R3 are each independently hydrogen or C 1-10 alkyl groups, R4 is C 1-10 C containing one or more of the following elements: hydrocarbon group, fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus 1-10 is selected from a hydrocarbon group; R2 and R5 are each independently hydrogen or C 1-10 a hydrocarbon group or a C=C or C≡C-containing hydrocarbon group having 10 or less carbon atoms and containing one or more of the elements fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus; Rf is selected from an ethoxy segment having up to 16 carbon atoms of hydrogen or one or more of the elements fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus; x is the number of repeating methylene units, and 0≦x≦20; A + is one selected from functional groups having nitrogen, sulfur, or phosphorus as a cation center, Q -is one, two or more anions selected from halogen ions, halogen borates, halogen oxaloborates, perhalogenates, halogen phosphates, and halogen sulfonimide salts; and optionally Q - is one, two or more anions selected from chloride, tetrafluoroborate, difluorooxaloborate, perchlorate, hexafluorophosphate, and bis(fluorosulfonyl)imide salt; E is selected from the structures (1) to (3), [ka] where R6 is hydrogen or C 1-10 The alkyl group is selected from the group consisting of aryl, ... and alkyl groups.

[0064] In this application, 1-10 The alkyl group is a straight or branched chain alkyl group containing 1-10 carbons, including, but not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, isopropyl, isobutyl, tert-butyl, isopentyl, tert-pentyl, neopentyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 2-methylhexyl, 3-methylhexyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3-ethylpentyl, 2,2,3-trimethylbutyl, 2-methylhexyl, 3-ethylpentyl, 2,2,3-trimethylbutyl, 2-methylhexyl, 3-ethylhexyl, 2,2,3-trimethylbutyl, 2-methylhexyl, 3-ethylhexyl, 2,2,3-trimethylpentyl, 2,4-dimethylpentyl, 3-ethylpentyl, 2,2,3-trimethylbutyl, 2-methylhexyl, 3-ethylhex ... These include dimethylheptyl, 3-methylheptyl, 4-methylheptyl, 2,2-dimethylhexane, 3,3-dimethylhexane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane, 3,4-dimethylhexane, 3-ethylhexane, 2,2,3-trimethylpentyl, 2,2,4-trimethylpentyl, 2,3,3-trimethylpentyl, 2,3,4-trimethylpentyl, 2-methyl-3-ethylpentyl, 3-methyl-3-ethylpentyl, 2,2,3,3-tetramethylbutene, nonyl, and decyl.

[0065] In this application, 1-10 The hydrocarbon group is as described above in 1-10 Alkyl group, C 6-10 Aromatic groups, linear or branched C 2-10 Alkenyl group, linear or branched C 2-10 It may contain an alkynyl group. 6-10 The aromatic group is, for example, a phenyl group, a naphthyl group, 1-4 It may be an alkyl-substituted phenyl group. 2-10 The alkenyl group may be, for example, a vinyl group, a propenyl group, an allyl group, a butenyl group, a butadienyl group, a pentenyl group, a pentadienyl group, a hexenyl group, and the like. 2-10 The alkynyl group may be, for example, an ethynyl group, a propynyl group, a butynyl group, a butadialkynyl group, a pentynyl group, a pentadialkynyl group, a hexynyl group, and the like.

[0066] In the present application, in the definition of the R4 group of the monomer 2, "C containing one or more elements of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus" is defined as 1-10 The "hydrocarbon group" may be linear or branched, mono- or poly-substituted, saturated or unsaturated. "Containing one or more elements of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus" means that these elements are contained in a substituted form, such as, but not limited to, fluorine, chlorine, bromine, and iodine, and may also contain these elements in other forms, such as, for example, these elements are made into a group or a structural body structure, such as, but not limited to, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus, as long as it is chemically feasible. For example, the R4 group may be a phenyl group, a vinyl group, a propenyl group, an allyl group, a pyridyl group, a pyrimidyl group, etc.

[0067] In the present application, in the definition of R2 and R5 groups of Monomer 2, "a C=C or C≡C-containing hydrocarbon group having 10 or less carbon atoms and containing one or more elements selected from the group consisting of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus" means a C=C or C≡C-containing hydrocarbon group having one or more elements selected from the group consisting of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus. 2-10 Alkenyl group or C 2-10 Alkynyl groups may be represented as alkynyl groups, which may be linear or branched, mono- or poly-substituted. 2-10 The alkenyl group may be, for example, a vinyl group, a propenyl group, a butenyl group, a butadienyl group, a pentenyl group, a pentadienyl group, a hexenyl group, etc., and 2-10 The alkynyl group may be, for example, an ethynyl group, a propynyl group, a butynyl group, a butadialkynyl group, a pentynyl group, a pentadialkynyl group, a hexynyl group, etc. "Containing one or more elements of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus" means that these elements are contained in the form of substitution, such as, but not limited to, fluorine, chlorine, bromine, and iodine, and may also contain these elements in other forms, such as, for example, these elements are made into a group or a structural formula body structure, such as, but not limited to, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus, as long as it is chemically realizable. For example, R2 and R5 may be hydrogen, a vinyl group, a propenyl group, an allyl group, etc.

[0068] In the present application, in the definition of the Rf group of the monomer 3, "an ethoxy segment having 16 or less carbon atoms and containing one or more elements selected from the group consisting of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus" refers to a segment having 1 to 8 ethoxy groups, and containing one or more elements selected from the group consisting of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus. "Containing one or more elements selected from the group consisting of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus" refers to the presence of these elements in the form of substitution, such as, but not limited to, fluorine, chlorine, bromine, and iodine, and may contain these elements in other forms, such as, but not limited to, these elements as a group or a component part of the main structure of the structural formula, such as, but not limited to, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus, as long as it is chemically realizable. The segment of 1 to 8 ethoxy groups may be a branched or linear C 1-10 It may be substituted with an alkyl group or a haloalkyl group. For example, an ethoxy segment having 16 or less carbon atoms and containing one or more elements of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus may be an ethoxy segment connected to a cyclotriphosphazene, or may be an ethoxy segment substituted with one or more elements of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus.

[0069] In this application, A + In the definition of A, "a functional group having nitrogen, sulfur, or phosphorus as a cationic center" means that the functional group contains nitrogen, sulfur, or phosphorus, and the nitrogen, sulfur, or phosphorus is the cationic center. + is a functional group of a nitrogen-containing cation, more preferably selected from an ammonium cation, an imidazolium cation and a pyridinium cation, and most preferably A + is -N(R')2 + - and [ka] where R' is independently hydrogen or C 1-10The alkyl group is selected from the group consisting of aryl, ... and alkyl groups.

[0070] In this application, Q - is defined as one, two or more anions selected from halogen ions, halogen borates, halogen oxaloborates, perhalogenates, halogen phosphates, and halogen sulfonimide salts, and the number of anions is A + It depends on the number of cations in, e.g., A + If the group has two positive charges, Q - A may be an anion having two single charges. + , Q - The number of ions in is not specifically limited, and may be any number that is chemically feasible.

[0071] In the present application, the halogen ion may be a fluorine ion, a chloride ion, a bromide ion, or an iodide ion. The halogenation may be a fluorine ion, a chloride ion, a bromide ion, or an iodide ion, or may be selectively a fluoride ion, and the halogenation may be mono-, di-, or poly-substituted. The perhalogenate may be a perfluorate, a perchlorate, a perbromate, or a periodate.

[0072] The polymer according to this application is formed by polymerizing three types of monomers (monomer 1, monomer 2, monomer 3), which has an ethyl group as the main chain and contains functional groups such as an ionic group (derived from monomer 1), an amide (derived from monomer 1), a phosphate ester (derived from monomer 2), and a fluoroethoxy group (derived from monomer 3) in its molecular structure. These functional groups provide different effects to the polymer respectively. Currently, for example, the presence of the ionic group and fluorine element (mainly derived from monomer 3) is considered to be advantageous for improving the oxidation resistance or high-voltage stability (especially high voltage exceeding 5V) of the material. When the polymer is used as an electrolyte membrane material in a secondary battery, the flexible ethoxy side chain in the polymer can drive the movement of lithium ions, and the cation center in the ionic group can act with the anion in the lithium salt to improve the lithium ion transference number. Due to the synergistic effect of the phosphate ester group derived from monomer 2 and the fluorine element (mainly derived from monomer 3), the electrolyte containing the polymer exhibits excellent flame retardant properties, which can be applied to lithium secondary batteries and improve the safety of the battery. The amide derived from monomer 1 gives relatively strong hydrogen bonding forces between polymer molecules, and the presence of the relatively strong hydrogen bonding forces and the construction of a cross-linked network centered on the phosphate ester (derived from monomer 2) are advantageous for strengthening the mechanical properties of the polymer material.

[0073] The polymer described in this application may be a random triblock polymer. In some embodiments, the polymer described in this application has the following structural formula.

[0074] [Chemical formula] Here, R1, R2, R3, R4, Rf, E, A + , Q - , x are as defined above, and n, m, p are the number of repeating units, where 0 < n ≤ 5000, 0 < m ≤ 1000, 0 < p ≤ 5000, and The ratio of n to m, n:m, is within the range of 1:1 to 25:1, and the ratio of p to m, p:m, is within the range of 1:1 to 25:1, The tilde represents a crosslinking site between one polymer molecule of Formula 4 and another polymer molecule of Formula 4.

[0075] Optionally, the polymer has a triblock structure, which can block the contact between the ethoxy side chains and reduce the crystallinity of the polymer material, which can be used in the electrolyte membrane to improve the ionic conductivity.

[0076] In some embodiments, the substitution rate of the fluorine element in the Rf group is greater than 29.0%, and the substitution rate of the fluorine element is the ratio of the number of fluorine atoms based on the number of replaceable hydrogen atoms in the Rf group.

[0077] The "number of substitutable hydrogen atoms" should be understood as the number of substitutable sites in the Rf group, i.e., the maximum number of hydrogen atoms bonded to carbon atoms, phosphorus atoms, nitrogen atoms, and sulfur atoms present in this group. When the hydrogen atoms have already been substituted with other elements, such as halogen atoms, the number of substitutable hydrogen atoms is calculated as the sum of the number of hydrogen atoms and the number of other atoms substituted therewith.

[0078] By ensuring that the fluorine substitution rate is 29.0% or more, the flame retardant performance of the polymer can be ensured, while the high-voltage stability and high-voltage cycle performance of a battery obtained by using the polymer can be improved.

[0079] In some embodiments, the polymer comprises a cation A + is one selected from the structural formulas (4) to (6). [ka]

[0080] In some embodiments, in the polymer, the molar ratio of Monomer 1 is in the range of 3.7 to 92.6 mol %, the molar ratio of Monomer 2 is in the range of 2.0 to 33.3 mol %, and the molar ratio of Monomer 3 is in the range of 3.7 to 92.6 mol %, all based on the total number of moles of Monomer 1, Monomer 2, and Monomer 3; Alternatively, the molar ratio of monomer 1 to monomer 2 is in the range of 1:1 to 25:1; More preferentially, the molar ratio of monomer 3 to monomer 2 is in the range of 1:1 to 25:1.

[0081] In some embodiments, the thermal conductivity coefficient of the polymer is in the range of 0.06 to 0.35 W / m K and the flame retardant level is 94V-0 or 94V-1.

[0082] The thermal conductivity coefficients of the polymer and electrolyte membranes may be measured according to GB T 10294-2008.

[0083] The flame retardancy level of the polymer and electrolyte membrane may be determined according to the UL94 vertical flame test of ASTM D3801.

[0084] A second aspect of the present application provides a method for producing the polymer according to the first aspect of the present application, comprising the steps of: dissolving the monomer 1, the monomer 2, the monomer 3 and an initiator in a solvent, reacting them under vacuum at 30-100°C for 0.2-24 hours, optionally 6-24 hours, and then drying. The polymer is in the form of a block copolymer. Optionally, the drying is carried out under vacuum at 25-140°C for 1-48 hours. The main purpose of the drying is to remove the solvent remaining after the reaction.

[0085] A third aspect of the present application provides a polymer electrolyte membrane, comprising a polymer according to the first aspect of the present application or a polymer produced by the method according to the second aspect of the present application.

[0086] In some embodiments, the polymer electrolyte membrane further comprises a second polymer, the second polymer being dispersed in the polymer and forming an interpenetrating network, the second polymer being formed with Monomer 4, the general formula structure of which is: [ka]

[0087] wherein R7 is selected from hydrogen or a hydrocarbon group having less than 7 carbon atoms, unsubstituted or substituted with one or more of the elements fluorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus.

[0088] As described above, "hydrocarbon groups having less than 7 carbon atoms" include, but are not limited to, alkyl groups having less than 7 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, isopropyl, isobutyl, tert-butyl, isopentyl, tert-pentyl, neopentyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, alkenyl groups having less than 7 carbon atoms, such as ethylene, propylene, butene, butadiene, pentene, pentadiene, hexene, hexadiene, and alkynyl groups having less than 7 carbon atoms, such as acetylene, propyne, butyne, pentyne, hexyne, and the like. The hydrocarbon groups having less than 7 carbon atoms may be unsubstituted, mono- or polysubstituted with one or more of the elements fluorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron and phosphorus.

[0089] In this application, the second polymer is intended to be in contrast to and distinct from the aforementioned polymer.

[0090] The polymers described in this application can form interpenetrating networks with other polymers, optionally with flowable polymers, to obtain polymers with higher mechanical strength. Optionally, the second polymer is uniformly dispersed in the polymer to form an interpenetrating network. A schematic diagram of the interpenetrating network of the polymer with the second polymer is shown in FIG. 1.

[0091] The interpenetrating network structure is a special blend, and is also called an interpenetrating polymer network (abbreviated as IPN).

[0092] In the solid electrolyte membrane comprising an interpenetrating network structure formed by a polymer network and a second polymer network, the presence of ionic groups and fluorine elements in the polymer network can effectively improve the high pressure stability system of the electrolyte membrane, and the electrolyte membrane can exhibit a relatively wide electrochemical window, and thus is suitable for high voltage battery systems, for example, it can exhibit good cycle stability in NCM811 / Li batteries. In addition, due to the synergistic effect of the phosphate ester groups and fluorine elements in the polymer network, the polymer electrolyte membrane exhibits excellent flame retardant properties, improving the safety of lithium metal batteries. In addition, the presence of ionic groups and fluorine elements in the polymer network can effectively improve the high pressure stability system of the electrolyte membrane, and the electrolyte membrane can exhibit a relatively wide electrochemical window, and thus is suitable for high voltage battery systems, for example, it can exhibit good cycle stability in NCM811 / Li batteries. In addition, due to the synergistic effect of the phosphate ester groups and fluorine elements in the polymer network, the polymer electrolyte membrane exhibits excellent flame retardant properties, improving the safety of lithium metal batteries. The flexible ethoxy segments in the polymer can drive the movement of lithium ions, and the ionic groups with nitrogen, phosphorus, and sulfur as the cation centers can act with the anions in the lithium salt to restrict the movement and further improve the lithium ion movement rate. The relatively strong hydrogen bonding force between the amide molecules in the polymer network and the construction of a crosslinked network centered on phosphate ester are favorable for enhancing the mechanical performance of the material. At the same time, the triblock structure of the polymer can further combine the contact of the ethoxy side chain base, which reduces the crystallinity of the material and improves the ionic conductivity of the electrolyte membrane.

[0093] It should be understood that the above statements regarding polymers also apply to polymers in interpenetrating networks or electrolyte membranes.

[0094] The second polymer described in this application is an oligomer, which has a carbonate backbone and a number average molecular weight M n <2000 Da, viscosity less than 3000 cP, and has a certain fluidity. The second polymer may be called a carbonate polymer. The oligomer is uniformly dispersed in the polymer network as a second polymer network, i.e., in the random triblock polymer, the presence of the carbonate backbone in the second polymer network ensures the high pressure stability of the formed electrolyte membrane and contributes to the excellent high pressure resistance performance of the secondary battery containing the electrolyte membrane. The second polymer in the interpenetrating network structure has a certain fluidity and can act to wet the electrode plate, thereby improving the interfacial contact between the electrolyte membrane and the positive and negative electrodes. Therefore, in the interpenetrating network solid electrolyte membrane including the network formed by the polymer and the network formed by the second polymer, the introduction of the second polymer network having fluidity not only improves the wetting performance between the electrolyte membrane and the electrodes and improves the interfacial contact between the electrolyte membrane and the positive and negative electrodes, but also ensures the relatively high ionic conductivity of the electrolyte membrane, since the segment motion of the carbonate can drive the movement of lithium ions.

[0095] In some alternative embodiments, the electrolyte membrane containing the interpenetrating network structure described in the present application is suitable for high voltage battery systems, such as a 5V high voltage battery system. The high voltage battery series includes LiNi 0.8 Co 0.1 Mn 0.1 O2, LiCoO2, LiMn2O4, LiNiCoAlO2, LiNi 0.5 Mn 1.5 This includes, but is not limited to, battery systems such as O4.

[0096] Optionally, in the interpenetrating network, the weight ratio of the polymer to the second polymer is from 20:1 to 2:1.

[0097] In some embodiments, the polymer electrolyte membrane further comprises a lithium salt, the lithium salt being one or more selected from lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium difluoro(oxalato)borate (LiDFOB), lithium perchlorate (LiClO), and lithium bis(oxalato)borate (LiBOB).

[0098] The type of lithium salt affects the number of lithium ion transfers in the polymer electrolyte membrane. Different lithium salts have different structures, so there are differences in the degree of dissociation between anions and cations. Lithium salts with a high degree of dissociation can provide more carriers, and Li + The concentration of affects the "coordination-dissociation" process between the ether oxygen atoms and carbonyl groups in the polymer chain, and also affects the Li + In general, PEO-based electrolytes affect the mobility of Li and anions in the battery. + Polydentate chelation of the ether oxygen atom with TFSI - Relatively weak solvent interactions with the anion result in migration numbers smaller than 0.2.

[0099] In some embodiments, the mass percentage of the lithium salt in the polymer electrolyte membrane is in the range of 6.8 to 30.0%, based on the total mass of the polymer electrolyte membrane.

[0100] Alternatively, in the polymer electrolyte membrane, the mass ratio of the interpenetrating network structure to the lithium salt may be expressed as the mass ratio of the sum of the masses of the polymer and the second polymer to the lithium salt or the mass ratio of the sum of the masses of the monomers 1 to 4 to the lithium salt, i.e., 2.3 to 13.6.

[0101] In some embodiments, the fluorine content in the polymer electrolyte membrane is in the range of 12.5 to 46.0% based on the total weight of the polymer electrolyte membrane.

[0102] In order to ensure the dual properties of high pressure resistance and flame retardancy of the electrolyte membrane prepared using the polymer, the substitution of fluorine element in the Rf group of the polymer can optimally maintain a ratio of 29.0% or more. In the polymer electrolyte membrane prepared using the polymer, the content ratio of fluorine element is finally controlled within the above range, which is more favorable to realize the high pressure resistance and flame retardancy of the electrolyte membrane.

[0103] A third aspect of the present application provides a method for producing a polymer electrolyte membrane, comprising the steps of:

[0104] Monomer 1, monomer 2, monomer 3 as described hereinabove, and monomer 4 as described hereinabove, a lithium salt as described hereinabove, an optional catalyst, and an initiator are reacted at 30-100° C. for 0.2-24 hours to obtain product 1. It is currently believed that in this step, monomer 1, monomer 2, and monomer 3 undergo a coblock polymerization reaction in the presence of the initiator to form the polymer, and monomer 4 undergoes an ionic copolymerization reaction in the presence of a lithium salt and an optional catalyst to form a flowable second polymer.

[0105] Initiators are used to initiate the block copolymerization reaction between Monomer 1, Monomer 2, and Monomer 3 to form the polymers described herein. The initiators include, but are not limited to, azo- or peroxy-based molecules such as 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(isobutylnitrile), 2,2'-azobis(methylbutyronitrile), 1,1'-azobis(cyanocyclohexane), dibenzoyl peroxide, dodecanoyl peroxide, di-tert-butyl peroxide, diisopropyl peroxydicarbonate, and dicyclohexyl peroxydicarbonate.

[0106] Optionally, the weight of the initiator is 5% or less of the total weight of the two polymer monomers and the lithium salt (ie, the sum of the weights of monomer 1, monomer 2, monomer 3, monomer 4 and the lithium salt).

[0107] The lithium salt is as described above. The lithium salt may be used to catalyze the ionic polymerization reaction of monomer 4 to form a mobile second polymer.

[0108] In some cases, using only lithium salt to catalyze the ionic polymerization reaction of monomer 4 is insufficient, and a catalyst is also required. Usable catalysts include, but are not limited to, stannous isooctanoate, aluminum trifluoromethanesulfonate, aluminum trichloride, trimethylsilyl trifluoromethanesulfonate, boron trifluoride ethyl ether, triethylamine, and 1,8-diazabicyclo[5.4.0]undec-7-ene. The catalyst catalyzes the polymerization of the second polymer. In the present application, the second polymer is obtained by a form of ionic polymerization.

[0109] Optionally, in the method for preparing a polymer electrolyte membrane, the monomer 1, the monomer 2, the monomer 3 and the monomer 4, the lithium salt, the catalyst and the initiator are dissolved in a solvent, and stirred or otherwise mixed to obtain a homogeneous solution.

[0110] Alternatively, the homogeneous solution is poured into an apparatus commonly used in the art (e.g., a polytetrafluoroethylene mold), heated to 30-100°C, and reacted under vacuum for 0.2-24 hours, and optionally, the reaction is carried out in a vacuum oven.

[0111] In some embodiments, the method of producing a polymer electrolyte membrane further comprises the step of anion-exchanging the obtained product 1 with a solution of a lithium salt to obtain product 2.

[0112] As mentioned above, monomer 1 contains Q -Anions are present, and some anions (e.g., chloride ions) may be detrimental to the battery core system, e.g., may cause corrosive effects, so anion exchange is necessary. After anion exchange, the anion Q associated with the ionic group in the formed polymer is - , e.g., the corroding Cl of aluminum foil - can be replaced by a target anion, optionally with the same type of anion as that in the lithium salt, in this way, on the one hand, it is possible to prevent some side reactions from occurring, and on the other hand, it is also possible to adjust the binding ability between the anion and the polymer, the lithium ion.

[0113] In general, the concentration of anions in the lithium salt solution for anion exchange is determined by the Q - The concentration of Q must be much higher than that of - The concentration of may be determined by conventional techniques in the art, for example, by measuring Cl - In this case, titration with silver nitrate may be performed in a neutral solution using potassium chromate as an indicator, and the chloride ion concentration can be calculated from the volume of silver nitrate solution consumed.

[0114] The lithium salt solution is a separately prepared solution, and the lithium salt in the lithium salt solution is the same or different from the lithium salt in the electrolyte membrane, and more preferably the same.Optionally, the anion exchange is carried out for 1-20 hours, and the time is not limited and can be adjusted according to the actual situation.

[0115] In the anion exchange, the solvent in the lithium salt solution used may be, for example, but is not limited to, acetone, acetonitrile, ethylene glycol dimethyl ether, dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate.

[0116] In some embodiments, the method for producing a polymer electrolyte membrane described in the present application further comprises drying the resulting product 2.

[0117] The purpose of drying is to remove residual solvent. Drying may be performed by any means conventionally used in the art, as long as the purpose of removing the solvent is achieved and the electrolyte membrane is not decomposed. Drying may be performed using a vacuum oven.

[0118] Optionally, the drying temperature does not exceed 140° C. and the drying time at 140° C. does not exceed 1 hour.

[0119] Optionally, the thermal shrinkage temperature of the electrolyte membrane is about 140 to 160°C.

[0120] In some embodiments, in the method for producing a polymer electrolyte membrane described in the present application, the ratio of the total mass of Monomer 1, Monomer 2, and Monomer 3 to the mass of Monomer 4 is 20:1 to 2:1.

[0121] In some embodiments, in the method for producing a polymer electrolyte membrane described herein, the mass ratio of the total mass of Monomer 1, Monomer 2, Monomer 3, and Monomer 4 to the lithium salt is in the range of 2.3 to 13.6.

[0122] In some embodiments, in the method of producing a polymer electrolyte membrane described herein, the weight ratio of the lithium salt to the initiator is from 5:1 to 60:1, and when a catalyst is used, the ratio of the sum of the weights of the lithium salt and catalyst to the weight of the initiator is from 7:1 to 80:1.

[0123] The initiator may be used to initiate the block copolymerization reaction of the polymer described in this application, and the lithium salt and catalyst may be used to initiate the ionic polymerization reaction of the second polymer, and the ratio of the two may reflect in a certain sense the distribution of the two polymers produced and the structural composition of the interpenetrating network.

[0124] According to the present application, in the preparation of the polymer and electrolyte membrane of the present application, the solvent used may be acetonitrile or other solvents commonly used in the field, such as acetone, 1,4-dioxane, N-methylpyrrolidone, dimethylsulfoxide, ethyl methyl carbonate, dimethyl carbonate, ethylene carbonate, ethylene glycol dimethyl ether, etc.

[0125] It is currently believed that the polymer described in this application is prepared by block copolymerization and initiated by an initiator. The second polymer is prepared by ionic polymerization catalyzed by a lithium salt and an optional catalyst. The monomers of the two polymers are mixed together, but each is prepared separately and does not interfere with each other. And because each monomer, initiator, and optional catalyst are uniformly mixed in solution before carrying out the polymerization reaction, the result after complete polymerization is an interpenetrating network structure in which the polymer network and the second polymer network are uniformly interpenetrated, and the lithium salt is uniformly dispersed therein.

[0126] It should be understood that the statements herein regarding process parameter conditions such as solvents, initiators, etc. in the preparation of electrolyte membranes also apply to the preparation of the aforementioned polymers.

[0127] Optionally, in some embodiments, the present application provides a solid electrolyte membrane produced by the above-described method of producing a solid polymer electrolyte membrane.

[0128] A fifth aspect of the present application provides a secondary battery, comprising a positive electrode, a negative electrode, and further comprising a polymer electrolyte membrane according to the third aspect of the present application or a polymer electrolyte membrane produced by the method according to the fourth aspect of the present application. The secondary battery, battery module, battery pack, and power consumption device of the present application are described below.

[0129] secondary battery The secondary battery described in the present application includes a positive electrode plate, a negative electrode plate, and a polymer electrolyte membrane described in the present application. During charging and discharging of the battery, active ions shuttle between the positive electrode plate and the negative electrode plate to be absorbed and desorbed. The polymer electrolyte membrane serves as an ion conductor between the positive electrode plate and the negative electrode plate.

[0130] [Positive electrode plate] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer including the positive electrode active material of the first aspect of the present application.

[0131] As an example, the positive electrode current collector has two surfaces opposing each other in the thickness direction of the positive electrode current collector, and the positive electrode film layer is disposed on either one or both of the two opposing surfaces of the positive electrode current collector.

[0132] In some embodiments, the positive electrode current collector may use a metal foil sheet or a composite current collector. For example, aluminum foil may be adopted as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0133] In some embodiments, the positive electrode active material may be a positive electrode active material for a battery known in the art. For example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphate with an olivine structure, lithium transition metal oxide, and each modified compound. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive electrode active material for a battery may be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of the lithium transition metal oxide include lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (may be abbreviated as LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (may be abbreviated as LiNi 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (may be abbreviated as LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (may be abbreviated as LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM 811 Lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05Examples of the lithium-containing phosphate having an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0134] Alternatively, the positive electrode active material may be lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMnO 2、 LiMn2O4, etc.), lithium nickel cobalt manganese oxide (LiNi 0.8 Co 0.1 Mn 0.1 O2 or LiNi 0.6 Co 0.2 Mn 0.2 O2) etc.

[0135] In some embodiments, the positive electrode membrane layer further optionally includes an adhesive. For example, the 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.

[0136] In some embodiments, the positive electrode membrane layer optionally further comprises a conductive agent, for example, the conductive agent may comprise at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0137] In some embodiments, the positive electrode includes a positive electrode current collector and a positive electrode film layer, the positive electrode film layer including a positive electrode active material, the second polymer, and the lithium salt. Optionally, the mass percentage of the second polymer in the positive electrode film layer is 2 to 15%, and optionally, the mass percentage of the lithium salt in the positive electrode film layer is 0.5 to 10%.

[0138] The lithium salt in the positive electrode layer may be the same as or different from the lithium salt in the electrolyte. The above description of the lithium salt in the electrolyte layer also applies to the lithium salt in the positive electrode layer.

[0139] In some alternative embodiments, a positive electrode plate can be manufactured by the following method, in which the positive electrode active material, the conductive agent (e.g., Super-p), the monomer 4 for manufacturing the second polymer, and any other components are dispersed in a solvent (e.g., N-methylpyrrolidone, abbreviated as NMP), and then the lithium salt and optional catalyst are added and mixed to form a uniform positive electrode slurry, and the positive electrode slurry is applied to a positive electrode current collector, and after a process such as drying, a positive electrode plate is obtained. Optionally, the drying may be performed in an oven at 30 to 100°C. Optionally, in this manufacture, the proportion of the positive electrode active material is 80% to 95%, the proportion of the conductive agent is 1 to 5%, the proportion of the monomer 4 is 2 to 15%, and the proportion of the lithium salt is 0.5 to 10%, all based on the total weight of the positive electrode active material, the conductive agent, the monomer 4, and any other components.

[0140] Alternatively, the lithium salt in the positive electrode membrane, the lithium salt in the electrolyte membrane and the lithium salt in the optional anion exchange operation are the same type of lithium salt.

[0141] The use of the second polymer in the positive electrode membrane has the following advantages: the voids inside the positive electrode membrane are filled with the fluid second polymer and lithium salt, and the fluid second polymer not only acts to wet the inside of the plate, but at the same time, the movement of its segments further provides channels for the lithium ions to transport inside the plate, thereby enhancing the ion transport inside the positive electrode membrane.

[0142] [Negative electrode plate] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0143] For example, the negative electrode current collector has two opposing surfaces in the thickness direction of the negative electrode current collector, and the negative electrode film layer is disposed on either one or both of the two opposing surfaces of the negative electrode current collector.

[0144] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, a copper foil may be used as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0145] In some embodiments, in the secondary battery, the negative electrode includes a negative electrode current collector and a metal sheet formed of lithium metal or a lithium alloy.

[0146] The negative electrode current collector may be a copper foil, but is not limited to a continuous copper foil, and may be a copper wire braided copper mesh, copper foam, or three-dimensional nanoporous copper.

[0147] The polymer electrolyte membrane described in this application has a high specific capacity (3860 mAh / g), an extremely low potential (-3.04 V vs. H2 / H + ) in combination with a lithium metal anode, a lithium alloy anode, or no anode. Optionally, the thickness of the anode plate is 9 to 50 μm.

[0148] The lithium alloy includes, but is not limited to, lithium aluminum alloy, lithium magnesium alloy, lithium boron alloy, etc. It should be understood that the lithium alloy described in this application is not limited to the three lithium aluminum alloy, lithium magnesium alloy, or lithium boron alloy, but may be other lithium alloys that can achieve the above-mentioned purposes.

[0149] In some embodiments, the negative electrodes may be commercially purchased or obtained by coating lithium metal and / or lithium alloys directly onto a current collector by cold pressing.

[0150] [Polymer electrolyte membrane] The electrolyte serves to conduct ions between the positive and negative electrodes. In particular, the secondary battery uses the solid polymer electrolyte membrane described in the present application, which can conduct lithium ions well and has high safety performance.

[0151] In some embodiments, in the secondary battery, the polymer electrolyte membrane has a thickness of 10 to 1000 μm.

[0152] The positive electrode plate, the solid polymer electrolyte membrane, and the negative electrode plate are stacked in this order to form a battery.

[0153] [Exterior body] In some embodiments, the secondary battery may include an exterior body for packaging the positive electrode plate, the negative electrode plate and the electrolyte. As an example, the positive electrode plate, the solid polymer electrolyte membrane and the negative electrode plate may be stacked to form a stacked structure battery core or may be wound structure battery core by a winding process, and the battery core is sealed in the exterior body. The number of battery cores in the secondary battery may be one or more, and may be adjusted according to demand.

[0154] In one embodiment, the present application provides an electrode assembly. In some embodiments, a positive electrode plate, a solid electrolyte membrane, and a negative electrode plate can be manufactured into an electrode assembly by a stacking process or a winding process. The exterior body can be used to package the electrode assembly and the solid electrolyte membrane.

[0155] In some embodiments, the exterior body of the secondary battery may be a pouch, for example, a bag-shaped pouch. The material of the pouch may be plastic, for example, including one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), etc. In some embodiments, the exterior body of the secondary battery may be a hard case, for example, a hard plastic case, an aluminum case, a steel case, etc.

[0156] Secondary battery manufacturing method In one embodiment, the present application provides a method for producing a secondary battery, which uses a polymer electrolyte membrane described herein or produced by a method described herein.

[0157] The manufacture of the secondary battery may further include assembling the negative electrode plate, the positive electrode plate, and the electrolyte of the present application to form a secondary battery. In some embodiments, the positive electrode plate, the polymer electrolyte membrane, and the negative electrode plate may be stacked in order and cold pressed to assemble into a full battery.

[0158] The present application does not particularly limit the shape of the secondary battery, and the secondary battery may be cylindrical, rectangular, or any other shape. For example, FIG. 3 shows a secondary battery 5 having a rectangular structure as an example.

[0159] In some embodiments, referring to FIG. 4, the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and a side plate connected on the bottom plate, and the bottom plate and the side plate surround and form a receiving cavity. The case 51 has an opening communicating with the receiving cavity, and the cover plate 53 can cover the opening to seal the receiving cavity. The positive electrode plate, the negative electrode plate and the separator may form an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving 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 those skilled in the art may select according to specific actual needs.

[0160] A sixth aspect of the present application provides a battery module, wherein the battery module includes the secondary battery according to the fifth aspect of the present application.

[0161] A seventh aspect of the present application provides a battery pack, wherein the battery pack includes the battery module according to the sixth aspect of the present application.

[0162] An eighth aspect of the present application provides a power consumption device, wherein the power consumption device includes at least one selected from a secondary battery described in the fifth aspect of the present application, a battery module described in the sixth aspect of the present application, or a battery pack described in the seventh aspect of the present application.

[0163] In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, with the specific number being selectable by one skilled in the art according to the application and capacity of the battery module.

[0164] Fig. 5 shows an example of a battery module 4. Referring to Fig. 5, in the battery module 4, the multiple 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 manner. Furthermore, the multiple secondary batteries 5 may be fixed by fasteners.

[0165] Optionally, the battery module 4 may further include a housing having an accommodating space, and the multiple secondary batteries 5 are accommodated in the accommodating space.

[0166] In some embodiments, the battery modules may be assembled into a battery pack, and the battery pack may include one or more battery modules, the specific number of which may be selected by one skilled in the art according to the application and capacity of the battery pack.

[0167] 6 and 7 show an example of a battery pack 1. Referring to FIG. 6 and FIG. 7, 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, and the upper housing 2 may be covered by the lower housing 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0168] The present application further provides a power consuming device, the power consuming device including at least one of the secondary battery, the battery module, or the battery pack according to the present application. The secondary battery, the battery module, or the battery pack may be used as a power source for the power consuming device, or may be used as an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, a mobile device (e.g., a mobile phone, a laptop, etc.), an electric vehicle (e.g., 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, a satellite, an energy storage system, etc.

[0169] The power consumption device can be a secondary battery, a battery module, or a battery pack depending on its usage demand.

[0170] 8 shows an example of a power consumption device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. A battery pack or a battery module can be employed to meet the demand for high power output and high energy density of the secondary battery of the power consumption device.

[0171] Another example of the device may be a mobile phone, a tablet computer, a notebook computer, etc. These devices are generally required to be thin and lightweight, and may employ a secondary battery as a power source.

[0172] Working Example The following are examples to illustrate the present application. The examples described below are illustrative and are used only to interpret the present application, and should not be understood as limitations to the present application. If no specific techniques or conditions are specified in the examples, they are performed according to techniques or conditions described in the literature in the field or according to the product instructions. If no manufacturer is specified, the reagents or equipment used are all commercially available ordinary products.

[0173] In the following examples, N,N,N-trimethyl-3-(2-methylallylamino)-1-propylammonium chloride, triallyl phosphate, perfluoropolyether acrylate (PFPE-MAA-1000), and fluoroethylene carbonate were purchased from Aladdin Reagents, Monomer-Polymer & Dajac Labs, Suzhou CHEMWELLS, and Aladdin Reagents, respectively.

[0174] I. Preparation of polymer, second polymer, electrolyte membrane, and secondary battery I-1. Polymer production At 25°C under a nitrogen atmosphere, 1.103g of N,N,N-trimethyl-3-(2-methylallylamino)-1-propylammonium chloride, 0.218g of triallyl phosphate, 5.465g of perfluoropolyether acrylate (PFPE-MAA-1000) and 0.063g of azobisisobutyronitrile (AIBN) are added to 20mL of acetonitrile, mixed uniformly by magnetic stirring, heated to 65°C, reacted for 10 hours, and then further dried in a vacuum oven at 45°C for 6 hours to produce a polymer.

[0175] I-2. Preparation of the second polymer The second polymer is ionically polymerized using fluoroethylene carbonate, the process being as follows.

[0176] At a temperature of 65°C, 1.4g of fluoroethylene carbonate, 0.014g of isooctanoic acid primary tin ester and 1.871g of lithium bis(fluorosulfonyl)imide are mixed uniformly and reacted for 10 hours, after which a second polymer having fluidity can be obtained. The number average molecular weight of the second polymer is 2000. The molecular weight test method is as follows:

[0177] The polymers are dissolved in N-methylpyrrolidone (NMP) and the dissolved molecules are separated according to size by gel permeation chromatography (GPC) through a column containing a microporous packing. As the samples are separated and eluted from the column, they can be characterized by a series of detectors (common calibration and triple detection).

[0178] I-3. Production of polymer electrolyte membrane At 25°C, 1.103g of N,N,N-trimethyl-3-(2-methylallylamino)-1-propylammonium chloride (monomer 1), 0.218g of triallyl phosphate (monomer 2), 5.465g of perfluoropolyether acrylate (PFPE-MAA-1000) (monomer 3), 0.063g of azobisisobutyronitrile (AIBN) (initiator), 1.4g of fluoroethylene carbonate (monomer 4), 0.014g of stannous isooctanoate (catalyst) and 1.871g of lithium bis(fluorosulfonyl)imide (lithium salt) were added to 20mL of acetonitrile and mixed uniformly. The homogeneous solution is poured into a polytetrafluoroethylene mold with a fixed depth and kept in a vacuum oven at 65 °C for 10 hours, and then the electrolyte membrane is immersed in 50 mL of 3 M LiFSI in acetone solution for anion exchange for 12 hours, and then dried in a vacuum oven at 45 °C for 6 hours to obtain a polymer solid electrolyte membrane with a thickness of 15 μm.

[0179] Size of the electrolyte membrane produced: 100mm x 100mm x 15μm I-4. Battery manufacturing Step 1: Manufacturing the positive electrode plate 4.5 g of lithium cobalt oxide (LiCoO2), 0.05 g of conductive agent Super-p, and 0.275 g of fluoroethylene carbonate are added to 2 ml of N-methylpyrrolidone (NMP) and mixed thoroughly, then 1.2 ml of lithium difluoro(oxalato)borate (LiDFOB) and NMP solution of stannous isooctanoate (mass concentrations are 12.5% ​​and 2.1%, respectively) are added to the above slurry and mixed quickly and uniformly to obtain a positive electrode slurry, which is applied to a 13 μm aluminum foil and dried in a blast oven at 50-80° C. to obtain a positive electrode plate.

[0180] Step 2: Manufacturing the negative electrode plate Negative electrode plate: Lithium metal (purchased from Shenzhen Kejing Zhida Technology Co., Ltd., with a thickness of 30 μm) was cold-pressed onto copper foil to form a coating, thereby obtaining a negative electrode plate.

[0181] Step 3: Fabrication of the polymer electrolyte membrane For the production of the electrolyte membrane, see I-3.

[0182] Step 4: Build a full battery The positive electrode plate containing the second polymer, the polymer solid electrolyte membrane, and the lithium metal or lithium alloy negative electrode plate were stacked in order and cold pressed to form a full battery, which was then subjected to charge / discharge and cycle tests.

[0183] I-5. Comparative polymer and comparative solid electrolyte membrane PEO with an average molecular weight Mv of 1,000,000 purchased from Aladdin Reagents was used as a comparison material and made into an electrolyte membrane by the following method.

[0184] 2g of PEO powder and 0.3g of lithium bis(fluorosulfonyl)imide (LiFSI) are dissolved in 35g of acetonitrile and stirred until completely dissolved. Then 0.7g of TiO2 powder (10-20nm) is added, stirred for 30min, and dispersed by ultrasonic. The dispersed slurry is poured into a self-made mold and dried in a vacuum oven at 60℃ for 12h. After drying, a PEO electrolyte membrane can be obtained.

[0185] Electrolyte membrane size: 100mm x 100mm x 15μm II. Performance considerations of polymers, electrolyte membranes, and batteries II-1. Swelling parameters The swelling parameters of the polymer prepared in I-1, the second polymer prepared in I-2, and the polymer electrolyte membrane prepared in I-3 were tested using the following method.

[0186] The polymer prepared in I-1, the second polymer prepared in I-2, and the electrolyte membrane prepared in I-3 were cut into square samples of 30 mm x 30 mm, each group was divided into three parallel samples, and the mass of each sample was weighed. The samples were then immersed in a 1M LiFSI solution in ethyl methyl carbonate (EMC) for 12 hours to swell. After swelling, the excess solvent on the surface of the swollen sample was first lightly blotted with filter paper to dry it, and then the mass of the sample after swelling was measured. The swelling parameter is the percentage of the mass increase of the sample after swelling to the mass of the original sample.

[0187] [Table 1] As can be seen from the results in the above table, the swelling parameters of the electrolyte membrane are between those of the polymer and the second polymer, which may indicate to some extent that the electrolyte membrane is a blend of the polymer and the second polymer.

[0188] II-2.Flame retardant performance The flame retardant performance of the polymer was examined in comparison with polyoxyethylene (PEO).

[0189] The thermal conductivity coefficients of the polymer prepared in I-1, the electrolyte membrane prepared in I-3, the comparative polymer PEO in I-5, and the comparative electrolyte membrane prepared using PEO were measured according to GB T 10294-2008.

[0190] The flame retardant performance of the polymer produced in I-1, the electrolyte membrane produced in I-3, the comparative polymer PEO in I-5, and the comparative electrolyte membrane produced using PEO are determined by the UL94 vertical flame test of ASTM D3801.

[0191] The performance test results are shown in the table below.

[0192] [Table 2] As can be seen from the results in the above table, the polymers and electrolyte membranes produced using the polymers according to the present application have superior flame retardant performance compared to the comparative PEO and comparative electrolyte membranes.

[0193] II-3. Effects of Monomer 1 and Monomer 2 on electrolyte membrane and battery performance Examples 1 to 9 The effects of Monomer 1 and Monomer 2 on the mechanical performance of the electrolyte membrane, and the high-pressure stability and high-pressure cycle performance of the battery were considered using Examples 1 to 9. The specific operations were as follows.

[0194] Example 1: A full battery was fabricated according to I-3 and I-4.

[0195] Examples 2 to 9: The preparation was the same as in Example 1, with the only difference being that the molar ratio of monomers 1 to 3 (based on the total molar amount of monomers 1 to 3) was changed. For the specific amounts and molar ratios of monomers used, see the table below.

[0196] The performance of the electrolyte membranes and full batteries produced in Examples 1 to 9 was tested, and the test methods were as follows.

[0197] (1) Electrolyte membrane tensile strength and elongation test The electrolyte membranes in Examples 1 to 9 were cut into rectangular electrolyte membrane samples with a size of 150 mm×20 mm and a thickness of 15 μm, and the above samples were stretched from the relaxed state to failure at a crosshead speed of 50 mm / min using a general-purpose testing machine with reference to standard ASTM D882-10, and the tensile strength and length L at the time when the maximum tensile stress of the sample broke were recorded, and the breaking elongation was calculated according to (L-L0) / L0×100%.

[0198] (2) High voltage stability performance test of batteries 5.0 mVs by linear scan voltammetry -1A linear potential scan was performed on each full battery in the range of 2-6 V at a scanning rate of 1.0 mV / s, and the change in current was recorded. The electrolyte film was sandwiched between a stainless steel sheet and a metallic lithium sheet and assembled into a coin-type battery, in which the stainless steel sheet was used as the working electrode and the metallic lithium sheet was used as the reference electrode, and a linear potential scan was performed on it in the range of 2-6 V at a scanning rate of 1.0 mV / s by an electrochemical workstation, with the voltage set to 6.0 V from the open circuit. The onset voltage when the electrolyte film was oxidatively decomposed was recorded, and the higher this voltage, the better the stability.

[0199] The curves obtained by testing the battery of Example 1 are shown in FIG.

[0200] (3) High-voltage cycle performance test of batteries A constant current charge / discharge test was performed on the full batteries in the examples within a voltage range of 2.8 to 4.3 V at a charge / discharge rate of 0.5C to 0.5C, and the number of cycles (cls) at which the remaining capacity was 80% during the high voltage upper limit charging process of each full battery was tested, and the numerical value of this number of cycles was recorded. The higher the number of cycles, the higher the stability of the high voltage cycle.

[0201] The test results are shown in the table below. [Table 3] The results in the table above show:

[0202] The high pressure stability of Examples 1 to 9 is relatively high, When the molar ratio of monomer 1 is low, for example in Examples 4 and 2, the tensile strength of the resulting electrolyte membrane is relatively low and the elongation is high, when the molar ratio of monomer 1 is too low, for example in Example 4, the high-pressure cycle performance of the corresponding battery is significantly decreased, and when the molar ratio of monomer 1 is too high, for example in Example 5, the elongation of the resulting electrolyte membrane is significantly decreased, and the high-pressure cycle performance of the battery obtained using such an electrolyte membrane is also significantly decreased. Therefore, it is preferable that the molar ratio of monomer 1 is 10 to 85%.

[0203] When the molar ratio of monomer 2 is low, for example in Examples 8 and 6, the tensile strength of the resulting electrolyte membrane is significantly low, and when the molar ratio of monomer 2 is too low, for example in Example 8, the high-pressure cycle performance is significantly reduced. When the molar ratio of monomer 2 is high, for example in Examples 7 and 9, the elongation of the resulting electrolyte is relatively low, and when the molar ratio of monomer 2 is too high, for example in Example 9, the high-pressure stability of the battery produced using the electrolyte membrane is poor and the high-pressure cycle performance is significantly reduced. Therefore, the molar ratio of monomer 2 is preferably 2.0 to 33.3%, more preferably 5% to 25%.

[0204] As can be seen from the above, the molar ratios of monomer 1 and monomer 2 have a relatively large effect on the mechanical strength (tensile strength and elongation) of the corresponding electrolyte membrane, and also have a significant effect on the high-pressure stability and high-pressure cycle performance of the corresponding batteries.

[0205] II-4. Effect of cations and lithium salts in monomer 1 on the number of lithium ions moving through the electrolyte membrane Examples 1, 10 to 11 In Examples 1, 10 and 11, the influence of the cation species and lithium salt species in Monomer 1 on the number of lithium ion transfers was considered.

[0206] Example 1: Full batteries were fabricated according to I-3 and I-4 as described above.

[0207] Example 10: The preparation of an electrolyte membrane and a full battery was the same as in Example 1, except that in the preparation of the electrolyte membrane in I-3, the monomer 1 was replaced with the monomers in the table below instead of N,N,N-trimethyl-3-(2-methylallylamide)-1-propylammonium chloride, and the lithium salt was replaced with LiBOB instead of LiFSI.

[0208] Example 11: The preparation of the electrolyte membrane and the full battery was the same as in Example 1, except that in the preparation of the electrolyte membrane in I-3, the monomer 1 was replaced with the monomers in the table below instead of N,N,N-trimethyl-3-(2-methylallylamide)-1-propylammonium chloride, and the lithium salt was replaced with LiBF4 instead of LiFSI.

[0209] Comparative Example 1: The electrolyte membrane and full battery were manufactured in the same manner as in Example 1, except that in the manufacture of the electrolyte membrane in I-3, the monomer 1 was replaced with the monomer in the following table instead of N,N,N-trimethyl-3-(2-methylallylamido)-1-propylammonium chloride.

[0210] The lithium ion migration rate of the electrolyte membranes produced in each of the Examples and Comparative Examples was tested, and the test method was as follows.

[0211] The number of lithium ions moving in the polymer solid electrolyte was measured by the constant potential polarization method. + The test method is as follows.

[0212] A Li / polymer solid electrolyte / Li symmetric cell was assembled, and a small constant potential difference ΔV (approximately 10 mV) was applied to the symmetric cell under test, while the change in current over time was recorded. In the initial state, all mobile ions in the battery system affect charge transport, and the current is at its maximum at this time, which is recorded as I0 (initial current). As polarization progresses, a gradually stable ion concentration gradient is formed inside the battery, the movement of anions is suppressed, and the current of the battery system is contributed by cations (i.e., lithium ions), and the current at this time is I s (steady-state current) is recorded. The lithium ion transfer rate t is calculated using Equation 1. + can be calculated.

number

[0213] [Table 4] As can be seen from the results in the above table, compared with Comparative Example 1 that does not contain a cation, the use of cation-containing monomer 1 is advantageous in improving the lithium ion mobility of the polymer solid electrolyte, and the higher the charge density around the cation, the stronger the dissociation ability of the lithium salt and the larger the lithium ion mobility.

[0214] II-5. Effect of Monomer 3 on electrolyte membrane and battery performance Examples 12 to 23 The effects of the type of Rf in monomer 3, the substitution rate of the fluorine element, the type of E group, and the amount of monomer 3 used on the electrolyte membrane and battery performance were considered.

[0215] Examples 12 to 15: The electrolyte membrane and full battery were manufactured in the same manner as in Example 1, except that the molar ratio of monomer 3 was not changed (the amounts of monomers 1 and 2 were changed according to the molar ratio in Example 1 and the mass of monomer 3 in Table 3), and only the Rf group and E group in monomer 3 were changed. See Table 5 below for details.

[0216] Example 16: The amounts of Monomer 1, Monomer 2, and Monomer 3 used were 0.221 g, 0.218 g, and 9.836 g, respectively, and the molar ratios were 9.10%, 9.10%, and 81.80%, respectively.

[0217] Example 17: The amounts of Monomer 1, Monomer 2, and Monomer 3 are 1.985 g, 0.218 g, and 1.094 g, respectively, and the molar ratios are 81.80%, 9.10%, and 9.10%, respectively.

[0218] Example 18: The amounts of Monomer 1, Monomer 2, and Monomer 3 were 0.049 g, 0.218 g, and 10.690 g, respectively, and the molar ratios were 2.0%, 9.10%, and 88.90%, respectively.

[0219] Example 19: The amounts of Monomer 1, Monomer 2, and Monomer 3 were 2.087 g, 0.218 g, and 0.589 g, respectively, and the molar ratios were 86.0%, 9.10%, and 4.90%, respectively.

[0220] The electrolyte membrane and full battery produced in each Example were subjected to the following tests.

[0221] (1) Ionic conductivity test: The electrolyte membrane was cut into a circular sheet with a diameter of 19 mm, and an R2032 button battery consisting of stainless steel sheet I electrolyte membrane I stainless steel sheet was assembled. After standing for 12 hours, an AC impedance spectrum (EIS) test was performed on an electrochemical workstation to obtain a 0.1-10 5 The frequency scan was performed in Hz, the voltage amplitude was 5 mV, the intersection point of the graph with the horizontal axis was the impedance R of the polymer film, and the ionic conductivity σ was calculated according to the following formula: σ=d / RA In the formula, d is the thickness of the electrolyte membrane, R is the resistance value, and A is the area of ​​the electrolyte membrane.

[0222] (2) Fluorine content ratio test in electrolyte membrane: The content of elemental fluorine in the electrolyte membrane is obtained by detection using X-ray photoelectron spectroscopy (XPS).

[0223] (3) Calculation of the substitution rate of fluorine element in Rf group:

[0224] The substitution rate of fluorine elements is based on the number of substitutable hydrogen atoms in the Rf group, that is, the number of fluorine atoms / (total number of halogen atoms+number of hydrogen atoms).

[0225] (4) Molar ratio calculation of monomer 3: mass of monomer 3 / molecular weight of monomer 3 is the number of moles of monomer 3, and moles of monomer 3 / (moles of monomer 1+moles of monomer 2+moles of monomer 3) is the molar ratio of monomer 3.

[0226] For the tests of the lithium ion mobility in the electrolyte membrane, the high-pressure stability of the battery, and the high-pressure cycleability, see above. [Table 5] JPEG2025515203000018.jpg25292The results in the table above show:

[0227] Compared to Comparative Example 2, each of the Examples achieved better electrolyte membrane performance and battery performance. The molar ratio of the monomer 3 in the monomers 1 to 3 is within a range of 8 to 85%, and optionally within a range of 8 to 80%, so that better electrolyte membrane and battery performance can be achieved; The substitution rate of fluorine element in Rf group is high, that is, greater than 29.0%, which is favorable for realizing better high-pressure stability of the battery; The higher the content ratio of elemental fluorine in the electrolyte membrane, the better the ionic conductivity of the electrolyte membrane and the better the high-pressure stability of the battery. However, if the content ratio of elemental fluorine in the electrolyte membrane is too high, it may be disadvantageous to the lithium ion migration rate of the electrolyte membrane and the high-pressure cycle performance of the battery. As shown in the above table, if the content ratio of elemental fluorine in the electrolyte membrane is within the range of 12.5 to 46%, better electrolyte membrane performance and battery performance can be achieved.

[0228] II-6. Effect of the amount of monomer and lithium salt of the second polymer on the electrolyte membrane and battery Examples 1, 20 to 27 The effect of the monomer 4 used to produce the second polymer on the performance of the electrolyte membrane and the battery was considered.

[0229] Example 1: As described above.

[0230] Examples 24-27: The preparation was similar to that of Example 1, except that the amounts of Monomers 1-3 and the amount of lithium salt added were kept constant, and only the amount of Monomer 4 was changed.

[0231] Examples 28-31: Similar to the preparation in Example 1, except that the amounts of Monomers 1-4 were kept constant and only the amount of lithium salt added was varied.

[0232] In the table, the mass percentage of the lithium salt is calculated as mass of lithium salt / total mass of (monomers 1 to 4 + initiator + lithium salt + catalyst) × 100%.

[0233] The tests for tensile strength, elongation, high pressure stability and high pressure cycle performance are shown above, and the test results are shown in the table below. [Table 6] As can be seen from the results in the above table, when the mass ratio of the sum of the masses of the monomers 1 to 3 to the monomer 4 is 2 to 20, the mass ratio of the monomers 1 to 4 to the lithium salt is 2.3 to 13.6, and the mass proportion of the lithium salt in the electrolyte membrane is within the range of 6.8 to 30.0%, the electrolyte membrane achieves better tensile strength and elongation, and the battery achieves better high-pressure stability and high-pressure cycleability.

[0234] It should be noted that the present application is not limited to the above embodiment. The above embodiment is merely an example, and any embodiment that has substantially the same configuration as the technical idea and achieves the same effect within the scope of the technical proposal of the present application is included in the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the embodiment and other methods that are configured by combining some of the components in the embodiment are also included in the scope of the present application, within the scope of the purpose of the present application. [Explanation of symbols]

[0235] 1: battery pack, 2: upper housing, 3: lower housing, 4: battery module, 5: secondary battery, 51: case, 52: electrode assembly, 53: top cover assembly

Claims

1. A polymer comprising monomer 1, monomer 2, and monomer 3 polymerized therein; The monomer 1 has a structure of formula 1, the monomer 2 has a structure of formula 2, and the monomer 3 has a structure of formula 3, 【Chemistry 11】 Where: R1 and R3 are each independently hydrogen or C １－１０ alkyl groups, R4 is C １－１０ C containing one or more elements of a hydrocarbon group, fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus １－１０ is selected from a hydrocarbon group; R2 and R5 are each independently hydrogen or C １－１０ selected from hydrocarbon groups or C=C or C≡C containing hydrocarbon groups having 10 or less carbon atoms and containing one or more of the elements fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus; Rf is selected from an ethoxy segment having up to 16 carbon atoms containing hydrogen or one or more of the elements fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus; x is the number of repeating methylene units, 0≦x≦20; A ＋ is one selected from functional groups having nitrogen, sulfur, or phosphorus as a cation center, Q － is one, two or more anions selected from halogen ions, halogen borates, halogen oxaloborates, perhalogenates, halogen phosphates, and halogen sulfonimide salts; and optionally Q － is one, two or more anions selected from chloride, tetrafluoroborate, difluorooxaloborate, perchlorate, hexafluorophosphate, and bis(fluorosulfonyl)imide salt; E is selected from the structures (1) to (3), 【Chemistry 12】 where R6 is hydrogen or C １－１０ The polymer is selected from the group consisting of alkyl groups.

2. 2. The polymer according to claim 1, wherein the substitution rate of the fluorine element in the Rf group is greater than 29.0%, and the substitution rate of the fluorine element is a ratio of the number of fluorine atoms based on the number of replaceable hydrogen atoms in the Rf group.

3. Cation A ＋ is one selected from the structural formulas (4) to (6). 【Chemistry 13】

4. Based on the total number of moles of monomer 1, monomer 2, and monomer 3, the molar ratio of monomer 1 is in the range of 3.7 to 92.6 mol %, the molar ratio of monomer 2 is in the range of 2.0 to 33.3 mol %, and the molar ratio of monomer 3 is in the range of 3.7 to 92.6 mol %. Optionally, the molar ratio of monomer 1 to monomer 2 is in the range of 1:1 to 25:1; More preferentially, the molar ratio of monomer 3 to monomer 2 is in the range of 1:1 to 25:

1.

5. 5. The polymer according to any one of claims 1 to 4, characterized in that the thermal conductivity coefficient of the polymer is in the range of 0.06 to 0.35 W / mK and the flame retardant level is 94V-0 or 94V-1.

6. 6. A method for producing the polymer of any one of claims 1 to 5, comprising dissolving said monomer 1, said monomer 2, said monomer 3 and an initiator in a solvent and keeping at 30-100°C under vacuum for 0.2-24 hours and then drying.

7. 7. A polymer electrolyte membrane comprising a polymer according to any one of claims 1 to 5 or a polymer produced by the method according to claim 6.

8. and further comprising a second polymer, said second polymer being dispersed in said polymer and forming an interpenetrating network, said second polymer being formed from Monomer 4, the general formula structure of which is: 【Chemistry 14】 8. The polymer electrolyte membrane of claim 7, wherein R7 is selected from hydrogen or a hydrocarbon group having less than 7 carbon atoms, unsubstituted or substituted with one or more of the following elements: fluorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, phosphorus.

9. 9. The polymer electrolyte membrane according to claim 7 or 8, further comprising a lithium salt, the lithium salt being one or more selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluoro(oxalato)borate, lithium perchlorate, and lithium bis(oxalato)borate.

10. 10. The polymer electrolyte membrane according to claim 7, wherein the mass percentage of the lithium salt is in the range of 6.8 to 30.0% based on the total mass of the polymer electrolyte membrane.

11. 11. The polymer electrolyte membrane according to claim 8, wherein the content of elemental fluorine is in the range of 12.5 to 46.0% based on the total weight of the polymer electrolyte membrane.

12. 1. A method for producing a polymer electrolyte membrane, comprising: A method for producing a polymer electrolyte membrane, comprising reacting monomer 1 according to any one of claims 1 to 11, monomer 2, monomer 3, monomer 4 according to any one of claims 8 to 11, a lithium salt according to any one of claims 9 to 11, an optional catalyst, and an initiator at 30 to 100°C for 0.2 to 24 hours to obtain product 1.

13. 13. The method for producing a polymer electrolyte membrane according to claim 12, further comprising anion-exchanging the obtained product 1 with a solution of a lithium salt to obtain product 2.

14. 14. The method for producing a polymer electrolyte membrane according to claim 13, further comprising drying the product 2 obtained.

15. The method for producing a polymer electrolyte membrane according to any one of claims 12 to 14, wherein a ratio of the total mass of the monomers 1, 2, and 3 to the mass of the monomer 4 is from 20:1 to 2:

1.

16. The method for producing a polymer electrolyte membrane according to any one of claims 12 to 15, wherein a mass ratio of the total mass of the monomer 1, the monomer 2, the monomer 3, and the monomer 4 to the lithium salt is within a range of 2.3 to 13.

6.

17. 17. The method for producing a polymer electrolyte membrane according to claim 12, wherein the weight ratio of the lithium salt to the initiator is from 5:1 to 60:1, and when a catalyst is used, the ratio of the sum of the weights of the lithium salt and the catalyst to the weight of the initiator is from 7:1 to 80:

1.

18. A secondary battery comprising a positive electrode and a negative electrode, characterized in that it further comprises the polymer electrolyte membrane according to claims 7 to 11 or the polymer electrolyte membrane produced by the method according to claims 12 to 17.

19. 19. The secondary battery according to claim 18, wherein the polymer electrolyte membrane has a thickness of 10 to 1000 μm.

20. 20. The secondary battery according to claim 18, wherein the negative electrode comprises a negative electrode current collector and a metal sheet formed of lithium metal and / or a lithium alloy.

21. 21. The secondary battery according to claim 18, wherein the positive electrode comprises a positive electrode current collector and a positive electrode film layer, and the positive electrode film layer comprises a positive electrode active material, the second polymer according to claim 8, and the lithium salt according to claim 9.

22. A battery module comprising the secondary battery according to any one of claims 18 to 21.

23. A battery pack comprising the battery module according to claim 22.

24. 24. A power consuming device comprising at least one selected from the group consisting of the secondary battery according to claim 18, the battery module according to claim 22, and the battery pack according to claim 23.

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