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, and further 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 range of lithium ion batteries becomes more and more widespread, lithium ion batteries are widely used in energy storage power systems such as hydroelectric power plants, thermal power plants, wind power plants and solar power plants, as well as in multiple fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. As lithium ion batteries have made great progress, higher requirements have been placed on 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 drawbacks such as easy flow, volatility, and poor thermal stability, which greatly limit the scope for improving the safety of lithium batteries. Meanwhile, the rapid development of modern society has raised 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 / H2) and low specific capacity (e.g., 3860 mAh / g vs. H2 / H2) are being developed. + Lithium metal anodes with a crystalline structure have once again attracted the attention of scientific researchers. However, the high reactivity of lithium and the short circuiting problem of lithium dendrites remain insurmountable obstacles to the development of lithium metal. The emergence of solid electrolytes has overcome these obstacles. The use of solid electrolytes instead of organic liquid electrolytes not only fundamentally solves the safety issues of batteries, but also opens up the possibility of further development of lithium metal batteries.

[0004] The use of aluminum-based polymers as solid polymer electrolyte membranes in lithium metal secondary batteries is currently an effective approach. However, the high-pressure resistance and safety performance of these solid polymer electrolyte membranes still need improvement. Therefore, there is still a need to provide a solid electrolyte membrane that has relatively high mechanical strength, good high-pressure resistance, and excellent flame retardancy. Summary of the Invention

[0005] The present application has been made in view of the above-mentioned problems, and its objective is to provide a polymer that has excellent flame retardancy, is resistant to oxidation under high pressure, and can improve ionic conductivity and lithium ion mobility when used as an electrolyte membrane material, and is suitable for high-voltage battery systems, as well as a method for producing the same. The present application also provides a solid electrolyte membrane including the polymer, which has good interfacial contact with electrodes, 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 formed by polymerizing Monomer 1, Monomer 2, and Monomer 3, 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 selected from hydrocarbon groups, R2 and R5 are each independently hydrogen, C 1-10a hydrocarbon group or a hydrocarbon group containing C=C or C≡C and having 10 or fewer carbon atoms and containing one or more elements of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus; Rf is selected from ethoxy segments containing 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 group units, and 0≦x≦20; A + is one selected from functional groups having nitrogen, sulfur, or phosphorus as the cation center, Q - is one, two or more anions selected from halogen ions, halogen borate salts, halogen oxalate borate salts, perhalogenates, halogen phosphate salts, halogen sulfonimide salts, and optionally Q - is one, two or more anions selected from chloride, tetrafluoroborate, difluorooxaloborate, perchlorate, hexafluorophosphate, and bis(fluorosulfonyl)imide salts; 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:

[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 in its molecular structure, 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). These functional groups each provide different functions to the polymer. For example, the presence of the ionic group and fluorine element (mainly derived from monomer 3) is currently 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 lithium ion migration, and the cationic centers in the ionic groups can interact with the anions in the lithium salt to increase the lithium ion migration rate. Due to the synergistic effect of the phosphate ester groups derived from Monomer 2 and the fluorine element (mainly derived from Monomer 3), electrolytes containing the polymer exhibit excellent flame retardancy, which can be used in lithium secondary batteries to improve battery safety. The amide derived from Monomer 1 imparts relatively strong hydrogen bonding forces between polymer molecules. The presence of these relatively strong hydrogen bonding forces and the construction of a crosslinked network centered on the phosphate ester (derived from Monomer 2) are advantageous for enhancing the mechanical performance of the polymer material.

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

[0009] In any embodiment, the substitution rate of fluorine atoms in the Rf group is greater than 29.0%, and the substitution rate of fluorine atoms is the ratio of the number of fluorine atoms to 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, possible phosphorus atoms, possible nitrogen atoms, and possible sulfur atoms present in this group. When the hydrogen atoms have already been substituted with other elements, for example, halogen atoms, the number of substitutable hydrogen atoms is calculated as the sum of the number of hydrogen atoms and the number of other substituted atoms.

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

[0012] In any embodiment, the polymer contains 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; Optionally, the molar ratio of monomer 1 to monomer 2 is in the range of 1:1 to 25:1; More preferably, 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 of the polymer is in the range of 0.06 to 0.35 W / m K, and the flame retardancy 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 following steps: dissolving the monomer 1, the monomer 2, the monomer 3, and an initiator in a solvent, reacting them under vacuum at 30 to 100°C for 0.2 to 24 hours, optionally for 6 to 24 hours, and then drying. The polymer is produced in the form of a block copolymer. Optionally, the drying is carried out under vacuum at 25 to 140°C for 1 to 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 to form an interpenetrating network, the second polymer being formed from Monomer 4, the general structure of which is: [ka]

[0018] wherein R7 is selected from hydrogen or hydrocarbon groups 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 term "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, and 2,3-dimethylbutyl; alkenyl groups having fewer than 7 carbon atoms, such as ethylene, propylene, butene, butadiene, pentene, pentadiene, hexene, and hexadiene; and alkynyl groups having fewer than 7 carbon atoms, such as acetylene, propyne, butyne, pentyne, and hexyne. The hydrocarbon groups having fewer 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 nThe second polymer may be referred to as a carbonate polymer. This oligomer is uniformly dispersed throughout the polymer network as a second polymer network. 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 of secondary batteries containing the electrolyte membrane. The second polymer in the interpenetrating network structure has a certain fluidity and can wet the electrode plates, thereby improving interfacial contact between the electrolyte membrane and the positive and negative electrodes. Therefore, in an interpenetrating network solid electrolyte membrane comprising a network formed by a polymer and a network formed by a second polymer, the introduction of the fluid second polymer network not only improves the wetting performance between the electrolyte membrane and the electrodes and improves interfacial contact between the electrolyte membrane and the positive and negative electrodes, but also ensures relatively high ionic conductivity of the electrolyte membrane because the segmental motion of the carbonate can drive lithium ion migration.

[0022] In some alternative embodiments, the electrolyte membranes containing the interpenetrating networks described herein are suitable for high voltage battery systems, such as 5V high voltage battery systems. electric The piezoelectric battery system is 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.

[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, and the lithium salt is 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 manufactured 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 it and the ether oxygen atoms and carbonyl groups in the polymer chain, and also affects the Li + and anions in the battery. Generally, PEO-based electrolytes + Multidentate chelation of the ether oxygen atom with TFSI and - Relatively weak solvent interaction with the anion results in a migration number less 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 of elemental fluorine 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.

[0028] In order to ensure the dual properties of high pressure resistance and flame retardancy of the electrolyte membrane manufactured using the polymer, the fluorine substitution in the Rf group of the polymer can be optimally maintained at a ratio of 29.0% or more. In the polymer electrolyte membrane manufactured using the polymer, the fluorine content ratio can be finally controlled within the above range, which is more advantageous in achieving 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, Monomer 4, Lithium salt, optional catalyst, and 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 for producing a polymer electrolyte membrane further comprises the step of anion-exchanging the resulting product 1 with a solution of a lithium salt to obtain product 2.

[0033] After anion exchange, the anions Q associated with the ionic groups in the formed polymer - , e.g., the corrosive Cl of aluminum foil - can be replaced with a target anion, optionally with the same type of anion as the anion in the lithium salt, in order to prevent some side reactions from occurring, and to adjust the binding ability between the anion, the polymer, and the lithium ion.

[0034] In any embodiment, the method for 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 any remaining 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 Monomer 1, Monomer 2, Monomer 3, and Monomer 4 to the lithium salt is within the 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 total weight 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 herein, 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 to a certain extent 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 produced using block copolymerization initiated by an initiator. The second polymer is produced using ionic polymerization catalyzed by a lithium salt and an optional catalyst. The monomers for the two polymers are mixed together, but are produced separately and do not interfere with each other. Furthermore, because the monomers, initiator, and optional catalyst are uniformly mixed in solution before the polymerization reaction, the resulting structure after complete polymerization is an interpenetrating network 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-described method for 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 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, and 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 a 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 electrode plate, but also, the movement of its segments provides channels for the transport of lithium ions inside the electrode plate, thereby enhancing 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 thickness of the polymer electrolyte membrane is 10 to 1000 μm.

[0049] A sixth aspect of the present application provides a battery module, which includes 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 explanation 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. [Figure 2]1 is a diagram showing charge-discharge curves 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. FIG. [Figure 3] 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 the embodiment of the present application. [Figure 5] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 6] 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 consumption device powered by a secondary battery according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0053] Hereinafter, 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 or repeated description of structures that are actually the same may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable 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, with the selected lower and upper limits defining the boundaries of the particular range. Such defined ranges may be inclusive or exclusive, and any combination is possible; i.e., any lower limit may be combined with any upper limit to form a single range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also possible. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all possible. In this application, unless otherwise specified, the numerical range "ab" represents a shorthand notation for any combination of real numbers from a to b, where a and b are both real numbers. For example, the numerical range "0 to 5" represents a list of all real numbers between "0 and 5" in this specification, and "0 to 5" is merely a shorthand representation of 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 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 specified, all steps in this application may be performed in order or randomly, and are preferably performed in order. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, when the method mentioned above may further include step (c), it means that step (c) may be added to the method in any order, and for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0058] Unless otherwise specified, the terms "comprise" and "comprises" used in this application may be open ended or closed ended. For example, the terms "comprise" and "comprises" may indicate that other components not listed may be further included or included, or that only the listed components may be included or included.

[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 when A is true (or exists) and B is false (or does not exist), when A is false (or does not exist) but B is true (or exists), or when both A and B are true (or exist).

[0060] Solid-state batteries can be divided into four types depending on the chemical system of the solid electrolyte: polymer, sulfide, oxide, and chloride. Polymer solid electrolytes, represented by polyoxyethylene (PEO)-based electrolytes, were first commercialized in the 1990s due to their advantages of good interfacial wetting, excellent processability, light weight, low density, and low cost. However, the voltage window of most such polymer electrolytes is relatively low (e.g., PEO∽3.9V), making them incompatible with high-voltage positive electrodes. This significantly limits improvements in battery energy density. At the same time, the flammable nature of polymers means they cannot 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 produced by homogeneously mixing the modified aluminum-based polymer, branched polymer, and electrolyte solution, adding a photoinitiator, and crosslinking under stirring conditions. Secondary batteries incorporating this electrolyte membrane have relatively high conductivity and can achieve stable cycling at 4.2 V. Furthermore, the crosslinked structure of this polymer provides the solid electrolyte membrane with relatively high mechanical strength and reduces dendrite formation, thereby improving the safety of lithium metal secondary batteries. However, this modified aluminum-based polymer membrane is primarily composed of polyester, which does not withstand high pressures by itself, limiting the improvement in high-pressure stability after aluminum-based modification. Second, this modified aluminum-based polymer membrane contains inorganic components and has a crosslinked structure, which improves mechanical performance but affects the interfacial contact between the resulting solid electrolyte membrane and the positive and negative electrodes. Furthermore, this solid electrolyte membrane is focused solely on its high-pressure resistance, not on the safety performance of the material itself, such as flame retardancy.

[0062] Surprisingly, the present application provides a new polymer that has good flame retardancy by itself and can form an interpenetrating network structure with other polymers. When a polymer having this structure is used as an electrolyte membrane, it can provide better mechanical strength. A secondary battery manufactured using this electrolyte membrane has better safety performance, better high-pressure stability, and better high-pressure cycling performance, and can achieve 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, 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 selected from hydrocarbon groups, R2 and R5 are each independently hydrogen, C 1-10 a hydrocarbon group or a hydrocarbon group containing C=C or C≡C and having 10 or fewer carbon atoms and containing one or more elements of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus; Rf is selected from ethoxy segments containing 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 group units, and 0≦x≦20; A + is one selected from functional groups having nitrogen, sulfur, or phosphorus as the cation center, Q -is one, two or more anions selected from halogen ions, halogen borates, halogen oxalates, perhalogenates, halogen phosphates, halogen sulfonimide salts, and optionally Q - is one, two or more anions selected from chloride, tetrafluoroborate, difluorooxaloborate, perchlorate, hexafluorophosphate, 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:

[0064] In this application, C 1-10 The alkyl group is a straight or branched chain alkyl group containing 1-10 carbon atoms, 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-methylpentyl, 2,4-dimethyl ... These include 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-tetramethylbutane, nonyl, and decyl.

[0065] In this application, C 1-10 The hydrocarbon group is the same as C 1-10 Alkyl group, C 6-10 Aromatic groups, linear or branched C 2-10 Alkenyl group, straight or branched chain C 2-10 It may contain an alkynyl group. 6-10 The aromatic group is, for example, a phenyl group, a naphthyl group, a C 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, or 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, the definition of the R4 group of Monomer 2 includes "C containing one or more elements of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus." 1-10 The "hydrocarbon group" may be straight-chain 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, but not limited to, as a group or a component part of the main structure of a structural formula, 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 the R2 and R5 groups of Monomer 2, "a hydrocarbon group containing C=C or C≡C and 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 group containing 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 straight 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 C 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. The phrase "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, but not limited to, as a group or a component 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 feasible. 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 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 also contain these elements in other forms, such as, but not limited to, as a group or a component 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 feasible. 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 preferentially it is selected from ammonium cation, imidazolium cation and pyridinium cation, most preferentially 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:

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

[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, and may be a mono-, di-, or poly-substituted halogenation. 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). It 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-pressure stability (especially high pressure 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 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. 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

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

[0076] In some embodiments, the substitution rate of fluorine atoms in the Rf group is greater than 29.0%, and the substitution rate of fluorine atoms is the ratio of the number of fluorine atoms to the number of substitutable 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, possible phosphorus atoms, possible nitrogen atoms, and possible sulfur atoms present in this group. When the hydrogen atoms have already been substituted with other elements, for example, halogen atoms, the number of substitutable hydrogen atoms is calculated as the sum of the number of hydrogen atoms and the number of other substituted atoms.

[0078] By ensuring that the fluorine substitution rate is 29.0% or more, the flame retardancy of the polymer is ensured, while the high-pressure stability and high-pressure 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 3.7 to 92.6 mol %, the molar ratio of Monomer 2 is 2.0 to 33.3 mol %, and the molar ratio of Monomer 3 is 3.7 to 92.6 mol %, all based on the total number of moles of Monomer 1, Monomer 2, and Monomer 3; Optionally, the molar ratio of monomer 1 to monomer 2 is in the range of 1:1 to 25:1; More preferably, 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 of the polymer is in the range of 0.06 to 0.35 W / m K and the flame retardancy 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 following steps: dissolving the monomer 1, the monomer 2, the monomer 3, and an initiator in a solvent, reacting them under vacuum at 30 to 100°C for 0.2 to 24 hours, optionally for 6 to 24 hours, and then drying. The polymer is produced in the form of a block copolymer. Optionally, the drying is carried out under vacuum at 25 to 140°C for 1 to 48 hours. The main purpose of 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 dispersed in the polymer to form an interpenetrating network, the second polymer being formed from Monomer 4, the general structure of which is: [ka]

[0087] wherein R7 is selected from hydrogen or hydrocarbon groups 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 fewer than 7 carbon atoms" include, but are 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, and 2,3-dimethylbutyl; alkenyl groups having fewer than 7 carbon atoms, such as ethylene, propylene, butene, butadiene, pentene, pentadiene, hexene, and hexadiene; and alkynyl groups having fewer than 7 carbon atoms, such as acetylene, propyne, butyne, pentyne, and hexyne. The hydrocarbon groups having fewer 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 herein can be interpenetrated with other polymers, optionally with flowable polymers, to form interpenetrating networks, resulting in polymers with higher mechanical strength. Optionally, the second polymer is uniformly dispersed in the polymer to form the interpenetrating network. A schematic diagram of the interpenetrating network of the polymer with the second polymer is shown in Figure 1.

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

[0092] In a 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 of the electrolyte membrane, and the electrolyte membrane exhibits a relatively wide electrochemical window, making it suitable for high-voltage battery systems, for example, it can exhibit good cycle stability in NCM811 / Li batteries. Furthermore, 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 migration of lithium ions, and the ionic groups with nitrogen, phosphorus, and sulfur as the cation centers can interact with the anions in the lithium salt to restrict their migration and further increase the number of lithium ions moving. The relatively strong hydrogen bonding forces between amide molecules in the polymer network and the construction of a crosslinked network centered on phosphate esters are advantageous for strengthening the mechanical performance of the material. At the same time, the triblock structure of the polymer can further combine contacts with the ethoxy side chain bases, reducing the crystallinity of the material and improving 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 The second polymer may be referred to as a carbonate polymer. This oligomer is uniformly dispersed throughout the polymer network as a second polymer network. In other words, 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 of secondary batteries containing the electrolyte membrane. The second polymer in the interpenetrating network structure has a certain fluidity and can wet the electrode plates, thereby improving interfacial contact between the electrolyte membrane and the positive and negative electrodes. Therefore, in an interpenetrating network solid electrolyte membrane comprising a network formed by a polymer and a network formed by a second polymer, the introduction of the fluid second polymer network not only improves the wetting performance between the electrolyte membrane and the electrodes and improves interfacial contact between the electrolyte membrane and the positive and negative electrodes, but also ensures relatively high ionic conductivity of the electrolyte membrane because the segmental motion of the carbonate can drive lithium ion migration.

[0095] In some alternative embodiments, the electrolyte membranes containing the interpenetrating networks described herein are suitable for high voltage battery systems, such as 5V high voltage battery systems. electric piezoelectric battery system 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, wherein the lithium salt is 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 manufactured 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 it and the ether oxygen atoms and carbonyl groups in the polymer chain, and also affects the Li + and anions in the battery. Generally, PEO-based electrolytes + Multidentate chelation of the ether oxygen atom with TFSI - Relatively weak solvent interaction with the anion results in a migration number less than 0.2.

[0099] In some embodiments, the mass fraction 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 manufactured using the polymer, the fluorine substitution in the Rf group of the polymer can be optimally maintained at a ratio of 29.0% or more. In the polymer electrolyte membrane manufactured using the polymer, the fluorine content ratio can be finally controlled within the above range, which is more advantageous in achieving 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 herein, Monomer 4, as described herein, a lithium salt, 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 coblock polymerization in the presence of the initiator to form the polymer, and Monomer 4 undergoes ionic copolymerization in the presence of the lithium salt and 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 and may be used to catalyze the ionic polymerization reaction of monomer 4 to form a mobile second polymer.

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

[0109] Alternatively, in a method for preparing a polymer electrolyte membrane, the monomer 1, the monomer 2, the monomer 3, the monomer 4, the lithium salt, the catalyst, and the initiator are dissolved in a solvent, and then 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 to 100°C, and reacted under vacuum for 0.2 to 24 hours; alternatively, the reaction is carried out in a vacuum oven.

[0111] In some embodiments, the method of producing a polymer electrolyte membrane further comprises 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, for example, they may cause corrosion, so anion exchange is necessary. After anion exchange, the anions Q associated with the ionic groups in the formed polymer are - , e.g., the corrosive Cl of aluminum foil - can be replaced with a target anion, optionally with the same type of anion as the anion in the lithium salt, in order to prevent some side reactions from occurring, and to adjust the binding ability between the anion, the polymer, and the lithium ion.

[0113] Generally, the concentration of anions in the lithium salt solution for anion exchange is determined by the Q - The concentration of Q - The determination of the concentration of may be carried out using conventional means 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, preferably the same. Optionally, the anion exchange is carried out for 1 to 20 hours, and this 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 herein further comprises drying the resulting product 2.

[0117] The purpose of drying is to remove any remaining 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 heat 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 herein, 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 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.

[0123] The initiator may be used to initiate the block copolymerization reaction of the polymer described herein, 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 to a certain extent 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, dimethyl sulfoxide, 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 produced using block copolymerization initiated by an initiator. The second polymer is produced using ionic polymerization catalyzed by a lithium salt and an optional catalyst. The monomers for the two polymers are mixed together, but are produced separately and do not interfere with each other. Furthermore, because the monomers, initiator, and optional catalyst are uniformly mixed in solution before the polymerization reaction, the resulting structure after complete polymerization is an interpenetrating network 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 production of electrolyte membranes also apply to the production methods 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 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 herein includes a positive electrode plate, a negative electrode plate, and a polymer electrolyte membrane described herein. During charging and discharging of the battery, active ions are absorbed and desorbed by shuttle between the positive electrode plate and the negative electrode plate. The polymer electrolyte membrane serves as ion conduction 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, and the positive electrode film layer includes 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 facing each other in the thickness direction thereof, and the positive electrode film layer is disposed on one or both of the two facing surfaces of the positive electrode current collector.

[0132] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum 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 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, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0133] In some embodiments, the positive electrode active material may be a battery positive electrode active material known in the art. For example, the positive electrode active material may include at least one of a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and a modified compound thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may also be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO), lithium nickel oxide (e.g., LiNiO), lithium manganese oxide (e.g., LiMnO, LiMnO), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and 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) and others.

[0135] In some embodiments, the positive electrode membrane layer optionally further includes an adhesive, which 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 a fluorine-containing acrylate resin.

[0136] In some embodiments, the positive electrode film layer optionally further includes a conductive agent, for example, 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 membrane layer may be the same as or different from the lithium salt in the electrolyte, and the above description of the lithium salt in the electrolyte membrane also applies to the lithium salt in the positive electrode membrane layer.

[0139] In some alternative embodiments, a positive electrode plate can be manufactured by the following method: dispersing the positive electrode active material, conductive agent (e.g., Super-p), monomer 4 for preparing the second polymer, and any other components in a solvent (e.g., N-methylpyrrolidone, abbreviated as NMP), then adding the lithium salt and optional catalyst, and mixing to form a uniform positive electrode slurry. The positive electrode slurry is then applied to a positive electrode current collector, and after drying and other processes, a positive electrode plate is obtained. Optionally, the drying may be performed in an oven at 30 to 100°C. Optionally, in this manufacturing process, 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, conductive agent, monomer 4, and any other components.

[0140] Optionally, 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 a 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 electrode plate, but also, the movement of its segments provides channels for the transport of lithium ions inside the electrode plate, thereby enhancing 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 surfaces that face each other in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two facing 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 base layer. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer base material (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[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 braided copper mesh, foamed copper, 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, and lithium boron alloy, but may be any other lithium alloy that can achieve the above-mentioned purpose.

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

[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 thickness of the polymer electrolyte membrane is 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 assemble into a battery.

[0153] [Exterior body] In some embodiments, the secondary battery may include an outer casing for packaging the positive electrode plate, the negative electrode plate, and the electrolyte. For example, the positive electrode plate, the solid polymer electrolyte membrane, and the negative electrode plate may be stacked to form a stacked battery core or may be wound into a wound battery core by a winding process, and the battery core is sealed in the outer casing. The number of battery cores in the secondary battery may be one or more and can 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 the electrode assembly by a stacking process or a winding process. The outer casing can be used to package the electrode assembly and the solid electrolyte membrane.

[0155] In some embodiments, the exterior of the secondary battery may be a pouch, for example, a bag-like pouch. The material of the pouch may be plastic, for example, may include one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), etc. In some embodiments, the exterior 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 manufacturing 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 it 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 to the bottom plate, and the bottom plate and side plate together form a surrounding accommodating cavity. The case 51 has an opening communicating with the accommodating cavity, and the cover plate 53 may cover the opening to seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the accommodating cavity. An electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and this can be selected by those skilled in the art 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 the secondary battery described in the fifth aspect of the present application, the battery module described in the sixth aspect of the present application, or the 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, and the specific number may be selected by those 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, a plurality of secondary batteries 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of 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 plurality of secondary batteries 5 are accommodated in this 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 those skilled in the art depending on the application and capacity of the battery pack.

[0167] 6 and 7 show an example of a battery pack 1. Referring to FIGS. 6 and 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 provided with a lid on 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 also provides a power consuming device, the power consuming device including at least one of a secondary battery, a battery module, or a 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 as an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc.

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

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

[0171] Other examples of the device may include a mobile phone, a tablet computer, a laptop computer, etc. These devices are generally required to be thin and lightweight, and may use a secondary battery as a power source.

[0172] 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 on the present application. Unless specific techniques or conditions are specified in the examples, they are carried out according to techniques or conditions described in literature in the field or according to product instructions. Unless the manufacturer is specified, reagents or equipment used are all commercially available 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, Inc., Monomer-Polymer & Dajac Labs, Suzhou CHEMWELLS Co., Ltd., and Aladdin Reagents, Inc., respectively.

[0174] I. Production of polymers, second polymers, electrolyte membranes, and secondary batteries I-1. Polymer production At 25°C under a nitrogen atmosphere, 1.103 g of N,N,N-trimethyl-3-(2-methylallylamino)-1-propylammonium chloride, 0.218 g of triallyl phosphate, 5.465 g of perfluoropolyether acrylate (PFPE-MAA-1000), and 0.063 g of azobisisobutyronitrile (AIBN) were added to 20 mL of acetonitrile, mixed uniformly by magnetic stirring, heated to 65°C, and reacted for 10 hours. After that, the mixture was placed in a vacuum oven at 45°C and dried 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] 1.4 g of fluoroethylene carbonate, 0.014 g of isooctanoic acid mono-tin ester, and 1.871 g of lithium bis(fluorosulfonyl)imide were mixed uniformly at 65°C and reacted for 10 hours to obtain a second polymer with fluidity. The number average molecular weight of the second polymer was 2000. The molecular weight test method was as follows:

[0177] The polymer is dissolved in N-methylpyrrolidone (NMP), and the dissolved molecules are separated by size using gel permeation chromatography (GPC) by passing them through a column containing a microporous packing. As the sample is separated and eluted from the column, it can be characterized by a series of detectors (common calibration and triple detection).

[0178] I-3. Production of polymer electrolyte membrane At 25°C, 1.103 g of N,N,N-trimethyl-3-(2-methylallylamino)-1-propylammonium chloride (monomer 1), 0.218 g of triallyl phosphate (monomer 2), 5.465 g of perfluoropolyether acrylate (PFPE-MAA-1000) (monomer 3), 0.063 g of azobisisobutyronitrile (AIBN) (initiator), 1.4 g of fluoroethylene carbonate (monomer 4), 0.014 g of stannous isooctanoate (catalyst), and 1.871 g of lithium bis(fluorosulfonyl)imide (lithium salt) were added to 20 mL of acetonitrile and mixed uniformly. The homogeneous solution was poured into a polytetrafluoroethylene mold with a fixed depth and kept in a vacuum oven at 65°C for 10 hours. The electrolyte membrane was then immersed in 50 mL of a 3 M LiFSI 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 produced electrolyte membrane: 100mm x 100mm x 15μm I-4. Battery manufacturing Step 1: Fabricating the positive electrode plate 4.5 g of lithium cobalt oxide (LiCoO), 0.05 g of the conductive agent Super-p, and 0.275 g of fluoroethylene carbonate were added to 2 ml of N-methylpyrrolidone (NMP) and mixed thoroughly. Subsequently, 1.2 ml of an NMP solution of lithium difluoro(oxalato)borate (LiDFOB) and stannous isooctanoate (mass concentrations of 12.5% ​​and 2.1%, respectively) was added to the slurry and mixed quickly and uniformly to obtain a positive electrode slurry. This slurry was then applied to a 13 μm aluminum foil and dried in a fan oven at 50-80°C to obtain a positive electrode plate.

[0180] Step 2: Fabricating 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: Full battery production 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 was fabricated into an electrolyte membrane by the following method.

[0184] 2 g of PEO powder and 0.3 g of lithium bis(fluorosulfonyl)imide (LiFSI) were dissolved in 35 g of acetonitrile and stirred until completely dissolved. 0.7 g of TiO powder (10-20 nm) was then added and stirred for 30 minutes. The mixture was then dispersed ultrasonically. The resulting slurry was poured into a self-made mold and placed in a vacuum oven at 60°C to dry for 12 hours. After drying, a PEO electrolyte membrane was 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 each cut into 30 mm x 30 mm square samples. Each set consisted of three parallel samples, and the mass of each sample was weighed. The samples were then immersed in a 1 M 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 gently blotted with filter paper to dry it, and then the mass of the swollen sample was measured. The swelling parameter was the percentage of the mass increase of the swollen sample compared to the original sample mass.

[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 can indicate to some extent that the electrolyte membrane is a blend of the polymer and the second polymer.

[0188] II-2.Flame retardancy The flame retardancy of polymers was examined using polyoxyethylene (PEO) as a comparison.

[0189] The thermal conductivity coefficients 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 were measured according to GB T 10294-2008.

[0190] The flame retardancy 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 is 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 according to the present application and electrolyte membranes produced using the polymers have superior flame retardant performance compared to the comparative PEO and comparative electrolyte membranes.

[0193] II-3. Effect 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, the high-pressure stability of the battery, and the high-pressure cycle performance were examined using Examples 1 to 9. The specific procedures were as follows.

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

[0195] Examples 2 to 9: The production was the same as in Example 1, except 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 the 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. Using a general-purpose testing machine, each of the above samples was stretched from a relaxed state to failure at a crosshead speed of 50 mm / min in accordance with the standard ASTM D882-10. The tensile strength and length L at which the maximum tensile stress of the sample broke were recorded, and the breaking elongation was calculated according to (L − L) / L × 100%.

[0198] (2) High voltage stability performance test of battery 5.0 mVs by linear scan voltammetry -1A linear potential scan was performed on each full battery in the range of 2 to 6 V at a scan 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. The stainless steel sheet served as the working electrode, and the metallic lithium sheet served as the reference electrode. A linear potential scan was performed on the full battery in the range of 2 to 6 V at a scan rate of 1.0 mV / s using an electrochemical workstation, with the voltage set to 6.0 V from the open circuit. The onset voltage of oxidative decomposition of the electrolyte film was recorded; 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 0.5 C to 0.5 C. 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 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 reduced. When the molar ratio of monomer 1 is too high, for example, in Example 5, the elongation of the resulting electrolyte membrane is significantly reduced, and the high-pressure cycle performance of the battery using such an electrolyte membrane is also significantly reduced. Therefore, the molar ratio of monomer 1 is preferably 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 battery.

[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 shown in the table below was used instead of N,N,N-trimethyl-3-(2-methylallylamido)-1-propylammonium chloride, and the lithium salt was LiBOB instead of LiFSI.

[0208] Example 11: 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 shown in the table below was used instead of N,N,N-trimethyl-3-(2-methylallylamido)-1-propylammonium chloride, and the lithium salt was LiBF4 instead of LiFSI.

[0209] Comparative Example 1: The preparation of the electrolyte membrane and 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 N,N,N-trimethyl-3-(2-methylallylamido)-1-propylammonium chloride, but the monomers in the following table were used.

[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 potentiostatic 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 cell system affect charge transport, and the current is at its maximum, recorded as I0 (initial current). As polarization progresses, a stable ion concentration gradient gradually forms inside the cell, suppressing the movement of anions, and the current in 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, the use of cation-containing Monomer 1 is advantageous in improving the lithium ion migration rate of the polymer solid electrolyte compared to Comparative Example 1, which does not contain a cation. Furthermore, the higher the charge density around the cation, the stronger the dissociation ability of the lithium salt and the larger the lithium ion migration rate.

[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 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 were 1.985 g, 0.218 g, and 1.094 g, respectively, and the molar ratios were 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 / electrolyte membrane / stainless steel sheet was assembled. After leaving it for 12 hours, an AC impedance spectroscopy (EIS) test was performed using an electrochemical workstation. 5 The frequency scan was performed in Hz, the voltage amplitude was 5 mV, the intersection of the graph and the horizontal axis was the impedance R of the polymer film, and the ionic conductivity σ could be calculated using 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 element content ratio test in electrolyte membrane: The content of elemental fluorine in the electrolyte membrane can be detected by X-ray photoelectron spectroscopy (XPS).

[0223] (3) Calculation of the substitution rate of fluorine atoms in the 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) Calculation of the molar ratio of monomer 3: Mass of monomer 3 / Molecular weight of monomer 3 is the number of moles of monomer 3, and number of moles of monomer 3 / (number of moles of monomer 1 + number of moles of monomer 2 + number of moles of monomer 3) is the molar ratio of monomer 3.

[0226] For the tests of the lithium ion mobility of the electrolyte membrane, the high-pressure stability of the battery, and the high-pressure cycle performance, see above. [Table 5] JPEG0007763971000017.jpg25292The results in the table above show the following:

[0227] Compared to Comparative Example 2, each of the Examples achieved better electrolyte membrane performance and battery performance. the molar ratio of monomer 3 in monomers 1 to 3 is in the range of 8 to 85%, and optionally in the 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, greater than 29.0%, which is advantageous for realizing better high-pressure stability of the battery; The higher the content 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 of elemental fluorine in the electrolyte membrane is too high, it may be detrimental to the lithium ion mobility of the electrolyte membrane and the high-pressure cycle performance of the battery. As shown in the table above, when the content 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 second polymer monomer and lithium salt on the electrolyte membrane and battery Examples 1, 20 to 27 The influence 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: The preparation was similar to that of 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 proportion of the lithium salt is calculated as mass of lithium salt / total mass of (monomers 1 to 4 + initiator + lithium salt + catalyst) × 100%.

[0233] For the tests of tensile strength, elongation, high pressure stability and high pressure cycling performance, see above, and for the test results, see 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 cycle performance.

[0234] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea and achieves the same effects within the scope of the technical solution of the present application is included within the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the embodiments and other methods that are constructed by combining some of the components of the embodiments are also included within the scope of the present application, as long as they do not deviate from the spirit 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 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, 【Chemistry 11】 where: R1 and R3 are each independently hydrogen or C １－１０ alkyl groups, R4 and R5 are allyl groups; R2 is hydrogen, C １－１０ selected from hydrocarbon groups or hydrocarbon groups containing C═C or C≡C groups having 10 or fewer carbon atoms and containing one or more elements of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus; Rf is selected from ethoxy segments containing fluorine and having 6 to 17 carbon atoms, and the substitution rate of fluorine atoms in the Rf group is greater than 29.0%, and the substitution rate of fluorine atoms is the ratio of the number of fluorine atoms to the number of substitutable hydrogen atoms in the Rf group; x is the number of repeating methylene group units, and 0≦x≦20; A ＋ is one selected from functional groups having nitrogen, sulfur, or phosphorus as the cation center, Q － is one, two or more anions selected from halogen ions, halogen borate salts, halogen oxalate borate salts, perhalogenates, halogen phosphate salts, halogen sulfonimide salts, E is selected from the structures (1) to (3), 【Chemistry 12】 where R6 is hydrogen or C １－１０ The polymer is selected from alkyl groups.

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

3. The polymer according to claim 1 or 2, wherein 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.

4. 3. The polymer according to claim 1, wherein the thermal conductivity of the polymer is in the range of 0.06 to 0.35 W / m K and the flame retardancy level is 94V-0 or 94V-1.

5. 3. A method for producing the polymer of claim 1 or 2, comprising the steps of dissolving the monomer 1, the monomer 2, the monomer 3 and an initiator in a solvent, maintaining the mixture at 30 to 100°C under vacuum for 0.2 to 24 hours, and then drying the mixture.

6. A polymer electrolyte membrane comprising the polymer of claim 1 or 2.

7. and further comprising a second polymer, said second polymer dispersed in said polymer to form an interpenetrating network, said second polymer being formed from Monomer 4, the general formula structure of which is: 【Chemistry 14】 7. The polymer electrolyte membrane of claim 6, wherein R7 is selected from hydrogen or a hydrocarbon group having fewer than 7 carbon atoms, unsubstituted or substituted with one or more of the elements fluorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus.

8. 7. The polymer electrolyte membrane of claim 6, further comprising a lithium salt, wherein the lithium salt is 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.

9. 9. The polymer electrolyte membrane according to claim 8, wherein the mass proportion of the lithium salt is in the range of 6.8 to 30.0% based on the total mass of the polymer electrolyte membrane.

10. 8. The polymer electrolyte membrane according to claim 7, 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.

11. 1. A method for producing a polymer electrolyte membrane, comprising: A method for producing a polymer electrolyte membrane, comprising reacting Monomer 1 according to claim 1 or 2, Monomer 2, Monomer 3, Monomer 4 according to claim 7, the lithium salt according to claim 8, an optional catalyst, and an initiator at 30 to 100°C for 0.2 to 24 hours to obtain Product 1.

12. 12. The method for producing a polymer electrolyte membrane according to claim 11, further comprising anion-exchanging the obtained product 1 with a solution of a lithium salt to obtain product 2.

13. 13. The method for producing a polymer electrolyte membrane according to claim 12, further comprising drying the obtained product 2.

14. 12. The method for producing a polymer electrolyte membrane according to claim 11, wherein the ratio of the total mass of the monomers 1, 2, and 3 to the mass of the monomer 4 is 20:1 to 2:

1.

15. 12. The method for producing a polymer electrolyte membrane according to claim 11, wherein the 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.

16. 12. The method for producing a polymer electrolyte membrane according to claim 11, wherein a weight ratio of the lithium salt to the initiator is 5:1 to 60:1, and when a catalyst is used, a ratio of the total weight of the lithium salt and the catalyst to the weight of the initiator is 7:1 to 80:

1.

17. A secondary battery comprising a positive electrode and a negative electrode, characterized in that it further comprises the polymer electrolyte membrane according to claim 6.

18. 18. The secondary battery according to claim 17, wherein the polymer electrolyte membrane has a thickness of 10 to 1000 μm.

19. 18. The secondary battery according to claim 17, wherein the negative electrode comprises a negative electrode current collector and a metal sheet formed of lithium metal and / or a lithium alloy.

20. 18. The secondary battery according to claim 17, wherein the positive electrode includes a positive electrode current collector and a positive electrode film layer, and the positive electrode film layer includes a positive electrode active material, the second polymer according to claim 7, and the lithium salt according to claim 8.

21. A battery module comprising the secondary battery according to claim 17.

22. A battery pack comprising the battery module according to claim 21.

23. 23. A power consuming device comprising a battery pack according to claim 22.

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