Polymer and application thereof

Abstract

The invention discloses a polymer and application thereof. The polymer at least comprises a structural formula as shown in a formula 1; in the formula 1, R1 is selected from a substituted or unsubstituted alkyl group of C1 to C30 and a substituted or unsubstituted aryl group of C6 to C60; r < 2 > is selected from a substituted or unsubstituted polyether group, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, and *-b < 1 >-S-S-b < 2 >-*; b1 and b2 are respectively and independently selected from a substituted or unsubstituted C2-C15 chain alkyl group and a substituted or unsubstituted C6-C60 aryl group; r3 is an ionic liquid group; n > = 1 and is an integer. Due to the special molecular structure of the polymer, the polymer has excellent room-temperature ionic conductivity when being applied to a polymer electrolyte.

Description

A polymer and its application Technical Field

[0001] The embodiments of the present application relate to a polymer and its application, belonging to the field of energy technology. Background Art

[0002] In the 1990s, Sony successfully industrialized lithium-ion batteries. Over decades of development, lithium-ion batteries have been widely used in various industries, including consumer electronics, electric vehicles, energy storage, and aerospace. Currently, lithium-ion batteries use organic electrolytes such as ethers and carbonates as a medium for lithium ion transmission. However, organic electrolytes present safety issues such as volatility, leakage, and flammability and explosiveness. Furthermore, during the cycling of lithium-ion batteries, uneven lithium deposition at the negative electrode interface can trigger the formation and growth of lithium dendrites. These dendrites can pierce the battery separator, causing a short circuit and leading to safety issues such as thermal runaway or fire.

[0003] Inorganic solid electrolytes are widely used to address safety issues in lithium-ion batteries due to their excellent electrochemical stability, thermal stability, and mechanical strength. However, inorganic solid electrolytes have the performance defect of being brittle and prone to cracking during use, which can increase the internal resistance of the battery and even cause failure. In addition, the poor solid-solid contact interface between the inorganic solid electrolyte and the positive and negative electrodes of the battery can also increase the internal resistance of the lithium-ion battery, resulting in a rapid decrease in the capacity and performance of the lithium-ion battery. To overcome the defects of inorganic solid electrolytes, polymer electrolytes have emerged. Polymer electrolytes have good processability, flexibility, and mechanical strength, which can effectively compensate for the performance defects of inorganic solid electrolytes. However, they generally have low room temperature ionic conductivity.

[0004] Summary of the Invention

[0005] The present application provides a polymer whose special molecular structure enables it to have excellent room-temperature ionic conductivity when applied to polymer electrolytes.

[0006] The present application provides a polymer electrolyte having excellent room temperature ionic conductivity, which can be widely used in batteries to improve the electrochemical performance of the batteries.

[0007] The present application provides a separator comprising the above-mentioned polymer or polymer electrolyte, so when applied to a battery, the electrochemical performance of the battery can be improved.

[0008] The battery of the present application has excellent electrochemical performance because it includes any one of the above-mentioned polymer, polymer electrolyte, and separator.

[0009] The present application provides a polymer, wherein the polymer comprises at least the structural formula shown in Formula 1;

[0010] In Formula 1, R1 is selected from substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C6-C60 aryl;

[0011] R2 is selected from substituted or unsubstituted polyether groups, substituted or unsubstituted C1-C30 alkyl groups, substituted or unsubstituted C1-C30 alkoxy groups, and *-b1-SS-b2-*; b1 and b2 are each independently selected from substituted or unsubstituted C2-C15 chain alkyl groups and substituted or unsubstituted C6-C60 aryl groups; R3 is an ionic liquid group;

[0012] n≥1 and is an integer.

[0013] The polymer as described above, wherein

[0014] When the polymer includes a plurality of the structural formula 1, the R3 is selected from the same ionic liquid group.

[0015] The polymer as described above, wherein when the polymer includes a plurality of the structural formula 1, at least one of the following is satisfied:

[0016] a) the R1 in the multiple structural formulas of Formula 1 is selected from the same group;

[0017] b) The R2 in the multiple structural formulas of Formula 1 is selected from the same group.

[0018] In the polymer as described above, R3 is selected from one of an imidazole ionic liquid group, a pyridine ionic liquid group, a quaternary ammonium ionic liquid group or a quaternary phosphonium ionic liquid group.

[0019] The polymer as described above, wherein the R3 is selected from any one of the following groups;

[0020] Wherein, R4 is selected from substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C1-C30 alkoxy; R5 is selected from substituted or unsubstituted C1-C10 alkyl; A is selected from BF4 - PF6 - TFSI - 、OTf - 、DCA - or TOS - .

[0021] The polymer as described above, wherein the R2 is selected from any one of the following groups;

[0022] Wherein, n is a positive integer.

[0023] The polymer as described above, wherein at least one of the following is satisfied:

[0024] a) R1 is a cyclic structure;

[0025] b) R2 is a chain structure.

[0026] The polymer as described above, wherein

[0027] The polymer is obtained by reacting an imine-based ionic liquid with a diisocyanate compound.

[0028] The present application provides a polymer electrolyte, wherein the polymer electrolyte includes a lithium salt and the polymer as described above.

[0029] The polymer electrolyte as described above, wherein the mass percentage of the lithium salt in the polymer electrolyte is 5-30%, and the mass percentage of the polymer is 70-95%.

[0030] The present application provides a separator, which includes a porous matrix, and the polymer or polymer electrolyte described above disposed on at least a portion of the surface of the porous matrix and / or in at least a portion of the pores of the porous matrix.

[0031] The present application provides a battery, comprising the polymer as described above;

[0032] or, comprising a polymer electrolyte as described above;

[0033] Or, comprising a membrane as described above.

[0034] The polymer of the present application includes the structural formula shown in Formula 1. The ionic liquid groups and anionic groups in the polymer can interact well with each other, thereby fixing the anions, allowing lithium ions to dissociate rapidly, increasing the concentration of freely migrating lithium ions in the electrolyte, and facilitating the improvement of the ionic conductivity and ion migration number of the polymer electrolyte. At the same time, the structure of the polymer is relatively neat, and the ionic liquid can be dispersed relatively evenly in the polymer, which is beneficial to improving the rapid conduction of lithium ions in the electrolyte, reducing the transmission resistance of lithium ions, and improving the electrochemical performance of the polymer electrolyte.

[0035] The polymer electrolyte of the present application includes the above-mentioned polymer. The polymer electrolyte has excellent room temperature ionic conductivity and mechanical strength and can be widely used in batteries to improve the electrochemical performance of the batteries.

[0036] The separator of the present application includes the above-mentioned polymer or polymer electrolyte, and therefore, when applied to a battery, can improve the electrochemical performance of the battery.

[0037] The battery of the present application has excellent electrochemical performance because it includes any one of the above-mentioned polymer, polymer electrolyte, and separator. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG1 is an infrared spectrum of the polymer in Example 1 of the present application. DETAILED DESCRIPTION

[0039] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0040] The first aspect of the present application provides a polymer, the polymer at least comprising the structural formula shown in Formula 1;

[0041] In Formula 1, R1 is selected from a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C6-C60 aryl group; R2 is selected from a substituted or unsubstituted polyether group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C1-C30 alkyl group, *-b1-SS-b2-*; b1 and b2 are each independently selected from a substituted or unsubstituted C2-C15 chain alkyl group, a substituted or unsubstituted aryl group; R3 is an ionic liquid group;

[0042] n≥1 and is a positive integer.

[0043] Specifically, R1 is selected from substituted or unsubstituted C1~C30 alkyl (for example, it can be a straight chain alkyl, a branched alkyl, a cycloalkyl, a substituted straight chain alkyl, a substituted branched alkyl, or a substituted cycloalkyl), and substituted or unsubstituted C6-C60 aryl (for example, it can be a substituted phenyl, an unsubstituted phenyl, a substituted biphenyl, or an unsubstituted biphenyl).

[0044] R2 is selected from substituted or unsubstituted polyether groups (for example, substituted chain polyether groups or unsubstituted chain polyether groups), substituted or unsubstituted C1-C30 alkyl groups (for example, linear alkyl groups, branched alkyl groups, cycloalkyl groups, substituted linear alkyl groups, substituted branched alkyl groups, or substituted cycloalkyl groups), substituted or unsubstituted C1-C30 alkoxy groups (for example, substituted branched alkoxy groups, substituted linear alkoxy groups, substituted cyclic alkoxy groups, unsubstituted linear alkoxy groups, unsubstituted branched alkoxy groups, or unsubstituted cyclic alkoxy groups), *-b1-SS-b2-* (b1 and b2 are each independently selected from substituted or unsubstituted C2-C15 chain alkyl groups, which may be linear alkyl groups or branched alkyl groups; substituted or unsubstituted C6-C60 aryl groups, which may be unsubstituted phenyl groups, substituted phenyl groups, substituted biphenyl groups, or unsubstituted biphenyl groups; * is the position connected to the main chain in Formula 1).

[0045] The present application does not particularly limit the substituents in R1 and R2, and the substituents may be substituents commonly used in the art. For example, the substituents may be selected from substituted or unsubstituted C1-C30 alkyl groups, substituted or unsubstituted C2-C30 alkenyl groups, substituted or unsubstituted C3-30 alkynyl groups, ester groups, substituted or unsubstituted C1-C30 alkoxy groups, substituted or unsubstituted C6-C60 aryl groups, or halogen groups.

[0046] The ionic liquid group in R3 refers to an organic group containing a cation and an anion.

[0047] n is the degree of polymerization, which is a positive integer; further, 50≤n≤800.

[0048] The polymer of the present application includes the structural formula shown in Formula 1. The ionic liquid groups in the polymer can interact well with the anionic groups, thereby fixing the anions, allowing lithium ions to dissociate rapidly, increasing the concentration of freely migrating lithium ions in the electrolyte, and facilitating the improvement of the ionic conductivity and ion migration number of the polymer electrolyte. At the same time, the structure of the polymer is relatively neat, and the ionic liquid can be dispersed relatively evenly in the polymer, which is conducive to improving the rapid conduction of lithium ions in the electrolyte, reducing the transmission resistance of lithium ions, and improving the electrochemical performance of the polymer electrolyte. It is worth mentioning that the ionic liquid groups can also improve the flame retardant properties of the polymer, so that the polymer electrolyte including the polymer has excellent flame retardant properties, thereby improving the safety performance of the battery.

[0049] It can be understood that in the polymer of the present application, R1, R2, and R3 in the structure shown in Formula 1 can be selected from the same group or different groups, that is, when the polymer includes multiple structures of Formula 1 (when n≥2), R1 in multiple structures of Formula 1 can be the same or different, R2 in multiple structures of Formula 1 can be the same or different, and R3 in multiple structures of Formula 1 can be the same or different.

[0050] In some embodiments of the present application, when a polymer includes multiple structures of Formula 1, R3 in the multiple structures of Formula 1 is selected from the same ionic liquid group. The same ionic liquid group is beneficial to improving the uniformity of ion conduction, thereby further improving the ionic conductivity of the polymer.

[0051] In some embodiments of the present application, when a polymer includes multiple structures of Formula 1, R1 in the multiple structures of Formula 1 is selected from the same group and R2 in the multiple structures of Formula 1 is selected from the same group. The same group is beneficial to improving the structural uniformity of the polymer and further improving the mechanical properties and ionic conductivity of the polymer.

[0052] In some embodiments of the present application, R3 is selected from one of an imidazole ionic liquid group, a pyridine ionic liquid group, a quaternary ammonium ionic liquid group or a quaternary phosphonium ionic liquid group.

[0053] In the present application, the polymer including the above-mentioned ionic liquid group can have more excellent room temperature ionic conductivity and flame retardant properties when used in polymer electrolytes, and the ionic liquid used to form the above-mentioned ionic liquid group is easy to obtain and relatively low in price, which helps to save production costs.

[0054] Further, R3 is selected from any one of the following groups;

[0055] Wherein, R4 is selected from substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C1-C30 alkoxy; R5 is selected from substituted or unsubstituted C1-C10 alkyl; A is selected from BF4 - PF6 - TFSI - ,OTf - 、DCA - or TOS - .

[0056] Specifically, * in the above structural formula refers to the position connected to the main chain shown in Formula 1.

[0057] R4 is selected from substituted or unsubstituted C1-C30 alkyl (for example, it can be substituted straight-chain alkyl, substituted branched-chain alkyl, substituted cycloalkyl, unsubstituted branched-chain alkyl, unsubstituted straight-chain alkyl or unsubstituted cycloalkyl), substituted or unsubstituted C1-C30 alkoxy (for example, it can be substituted straight-chain alkoxy, substituted cycloalkoxy, substituted branched-chain alkoxy, unsubstituted cycloalkoxy, unsubstituted straight-chain alkoxy, unsubstituted branched-chain alkoxy); R5 is selected from substituted or unsubstituted C1-C10 alkyl (for example, it can be substituted straight-chain alkyl, substituted branched-chain alkyl, substituted cycloalkyl, unsubstituted branched-chain alkyl, unsubstituted straight-chain alkyl or unsubstituted cycloalkyl).

[0058] Among them, the formation of anionic groups can be obtained by dissociation of corresponding salts. For example, tetrafluoroborate ions are obtained by dissociation of lithium tetrafluoroborate, and hexafluorophosphate ions are obtained by dissociation of lithium hexafluorophosphate. The structures of the anionic groups of the present application are shown below:

[0059] The present application does not particularly limit the substituents in R4 and R5, and the substituents may be substituents commonly used in the art. For example, the substituents may be selected from at least one of a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, a substituted or unsubstituted C3-30 alkynyl group, an ester group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C6-C60 aryl group, and a halogen.

[0060] When R3 is selected from the above structural formula, the production cost can be reduced while further improving the electrochemical performance and flame retardant performance of the battery.

[0061] In some embodiments of the present application, R2 is selected from any one of the following groups, but is not limited to the following structures:

[0062] n in R2 is the degree of polymerization, which can be a positive integer between 1 and 30. The degree of polymerization in each structural formula in this application can be the same or different; * refers to the position connected to the main chain shown in Formula 1.

[0063] When R2 is selected from the above structural formula, the electrochemical performance of the battery can be further improved.

[0064] In some embodiments of the present application, R1 is a cyclic structure, that is, R1 is selected from substituted or unsubstituted C1-C30 cycloalkyl groups (for example, substituted cycloalkyl groups or unsubstituted cycloalkyl groups).

[0065] When R1 is a ring structure, it helps to improve the rigidity and thermal properties of the polymer, thereby improving the mechanical properties and heat resistance of the polymer electrolyte and extending the service life of the battery.

[0066] Furthermore, R2 is a chain structure. That is, R2 is selected from a substituted or unsubstituted chain polyether group (for example, a substituted linear polyether group, a substituted branched polyether group, an unsubstituted linear polyether group, or an unsubstituted branched polyether group), a substituted or unsubstituted C1-C30 chain alkoxy group (for example, a substituted branched alkoxy group or a substituted linear alkoxy group), and *-b1-SS-b2-* (b1 and b2 are each independently selected from a C2-C15 chain alkyl group, which is a linear alkyl group or a branched alkyl group).

[0067] In the present application, when R2 is a chain structure, the transport performance of lithium ions between ionic liquid structures can be regulated, thereby improving the lithium ion transport efficiency of the polymer electrolyte.

[0068] In particular, when R1 in the polymer is a ring structure and R2 is a chain structure, the structure of the polymer is both rigid and flexible, which can enable the polymer electrolyte to have both excellent mechanical properties and lithium ion transmission properties, thereby improving the electrochemical performance of the battery and extending the battery life.

[0069] The present application does not impose any particular restrictions on the raw materials and production methods for the polymers. As long as the polymers meet the above-mentioned characteristics, the raw materials and production methods can be freely selected according to the purpose.

[0070] In some embodiments of the present application, the polymer is obtained by reacting an imine-based ionic liquid with a diisocyanate compound.

[0071] The present application does not particularly limit the imine-based ionic liquid, which may be an ionic liquid containing an imine group commonly used in the art. The imine-based ionic liquid may be purchased commercially or prepared in a laboratory.

[0072] The present application does not particularly limit the diisocyanate compound. The diisocyanate compound can be a compound containing two isocyanate groups commonly used in the art. For example, the diisocyanate compound can be selected from at least one of isophorone diisocyanate, diphenylmethane-4,4′-diisocyanate, p-phenylene diisocyanate, 1,3-diisophenylcyanate, 2,6-toluene diisocyanate, m-phenylenediisocyanate, toluene-2,4-diisocyanate and 4,4′-dicyclohexylmethane diisocyanate.

[0073] In the present application, the imine-based ionic liquid reacts with the diisocyanate compound, the imine-based ionic liquid is used to form the R2 and R3 groups, and the diisocyanate compound is used to form the R1 group.

[0074] The present application prepares the polymer through the above process, which not only can obtain a polymer with excellent comprehensive properties, but also has a simple preparation method and is suitable for wide promotion and application.

[0075] The present application does not impose any particular restrictions on the specific reaction conditions of the imine ionic liquid and the diisocyanate compound. Generally, the amount of the diisocyanate compound used should be no less than the amount of the imine ionic liquid used. The main purpose is to allow the imine groups in the imine ionic liquid to undergo a complete chemical reaction. Furthermore, a moderate excess of isocyanate groups can form potential chemical reaction sites in the resulting polyurea polymer electrolyte, undergoing chemical cross-linking reactions with other components in the polymer electrolyte, thereby increasing the cross-linking density of the polyurea polymer electrolyte. For example, the remaining isocyanate groups can continue to react with amino- or hydroxyl-containing compounds to increase the cross-linking density of the polymer electrolyte; and a moderate excess of isocyanate groups can react with water, which can appropriately eliminate the adverse effects of moisture on the performance of the polyurea polymer electrolyte. In some embodiments, the molar ratio of the imine groups in the imine ionic liquid to the isocyanate groups in the diisocyanate compound can be 1:(1.0 to 1.2).

[0076] In some embodiments, when the reaction of the imino ionic liquid and the diisocyanate compound is conducted at a temperature of 40°C to 80°C and for a time of 30 minutes to 24 hours, a polymer with superior properties can be obtained. Furthermore, a catalyst can be added during the reaction of the imino ionic liquid and the diisocyanate compound. The catalyst can be an organotin catalyst or an alcoholamine catalyst, and the amount of the catalyst can be 0.2 to 3 mol% of the total amount of monomers (the sum of the imino ionic liquid and the diisocyanate compound).

[0077] In some embodiments, as shown in Formula 2, an imine ionic liquid can be prepared by an addition reaction between an amine ionic liquid and a diene compound;

[0078] The amine-based ionic liquid can be an amine-containing ionic liquid commonly used in the art, and the amine-based ionic liquid can be purchased commercially or prepared in a laboratory.

[0079] The diene compound may be a compound containing two alkenyl groups commonly used in the art. For example, the diene compound may be selected from at least one of poly(ethylene glycol) diacrylate, poly(ethylene glycol) dimethacrylate, polyethylene glycol-block-polypropylene glycol-block-polyethylene glycol diacrylate, ethylene glycol diacrylate, triethylene glycol diacrylate, tetra(ethylene glycol) diacrylate, ethylene glycol dimethacrylate, poly(propylene glycol) dimethacrylate, bis(2-methylpropylene) ethoxy disulfide, and diallyl disulfide. The structural formula of some of the diene compounds is as follows:

[0080] In the above structure, n represents the degree of polymerization, which is a positive integer.

[0081] As shown in Formula 2, when the amine-based ionic liquid reacts with the diene compound, the diene compound is used to form R2, and the amine-based ionic liquid is used to form R3, thereby obtaining an imine-based ionic liquid including R3 and R2.

[0082] Specifically, the A1 compound forms an a1 group, the A2 compound can form an a2 group, the A3 compound can form an a3 group, the A4 compound can form an a4 group, the A5 compound can form an a5 group, and the A6 compound can form an a6 group.

[0083] The present application does not impose any particular restrictions on the specific reaction conditions of the amine-based ionic liquid and the dienyl compound. A moderate excess of the amine-based ionic liquid is primarily intended to ensure a complete chemical reaction between the dienyl compound and the amine groups. Furthermore, the molar ratio of the amine groups in the amine-based ionic liquid to the alkenyl groups in the dienyl compound can be (1.0-1.2):1. In some embodiments, a temperature of 40°C-90°C and a reaction time of 8-24 hours during the reaction of the amine-based ionic liquid and the dienyl compound contribute to the production of a polymer with excellent overall properties.

[0084] A second aspect of the present application provides a polymer electrolyte, which includes a lithium salt and the polymer of the first aspect of the present application.

[0085] Among them, lithium salt is used to transmit lithium ions, the polymer is the skeleton of the polymer electrolyte, and the lithium salt is embedded in the polymer skeleton.

[0086] The present application does not particularly limit the lithium salt and can be selected from lithium salts commonly used in the art. For example, the lithium salt can be selected from at least one of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium bis(trifluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), and lithium hexafluorophosphate (LiPF6). Because the polymer electrolyte of the present application includes the polymer of the first aspect, when used in a battery, it can improve the electrochemical performance of the battery and extend the battery life.

[0087] It can be understood that the addition of lithium salt in the present application can be done by directly adding the corresponding lithium salt during the preparation of the polymer electrolyte, or by adding the corresponding lithium salt in the form of an electrolyte during the preparation of the battery.

[0088] In some embodiments, the polymer of the first aspect may be uniformly mixed with a lithium salt and a solvent, and then the solvent may be removed to form a polymer electrolyte comprising the polymer of the first aspect and the lithium salt.

[0089] In other embodiments, the polymer electrolyte is obtained by reacting a raw material system including a lithium salt, an imine-based ionic liquid, and a diisocyanate compound.

[0090] Specifically, a solvent, a lithium salt, an imine ionic liquid and a diisocyanate compound can be mixed to obtain a raw material system, and the raw material system is reacted. The imine ionic liquid and the diisocyanate compound will react to form a polymer including the structure of Formula 1, and the electrolyte formed by the lithium salt and the solvent will be embedded in the polymer. After drying and removing the solvent, a polymer electrolyte including the lithium salt and the polymer of the first aspect is obtained.

[0091] The present application does not particularly limit the preparation method of the polymer electrolyte, and those skilled in the art can freely select a manufacturing method corresponding to the purpose.

[0092] In some embodiments, the polymer electrolyte can be obtained by self-supporting film formation, such as by applying the raw material system of the polymer electrolyte to a carrier (such as a release film, an electrode, or a battery casing) to initiate polymerization of the raw material system to obtain a polymer electrolyte. The polymer system can also be cast on a release film and cured to form a film and then peeled off to obtain the polymer electrolyte. The polymer electrolyte can also be obtained by extruding the polymer system into a film.

[0093] In some embodiments, the polymer electrolyte may be prepared by a method comprising the following steps:

[0094] A polymer is added to a first solvent to obtain a first mixed solution; a lithium salt is added to the first solution and stirred evenly to obtain a polymer system; the polymer system is cast on the surface of a release film, and then the first solvent is removed and the polymer system is separated from the release film to obtain a composite electrolyte.

[0095] The present application does not impose any particular limitation on the first solvent, which can be selected from commonly used solvents, such as N-methylpyrrolidone (NMP), acetone, methanol, ethanol, and the like.

[0096] The present application does not impose any specific restrictions on the thickness of the porous matrix, for example, it can be preferably 5-50 μm. The present application also does not impose any specific restrictions on the pore size and porosity in the porous matrix, for example, they can be preferably 0.2-100 μm and 10-99%, and further preferably 0.5-50 μm and 30-70%, respectively.

[0097] In some embodiments of the present application, when the mass percentage of lithium salt in the polymer electrolyte is 5%-30% and the mass percentage of polymer is 70%-95%, the polymer electrolyte has more excellent room temperature ionic conductivity and mechanical properties. When applied to batteries, it can further improve the electrochemical performance of the battery and extend the service life of the battery.

[0098] A third aspect of the present application provides a separator comprising a porous substrate, and the polymer of the first aspect or the polymer electrolyte of the second aspect disposed on at least a portion of the surface of the porous substrate and / or in at least a portion of the pores of the porous substrate.

[0099] It can be understood that in the membrane of the present application, the polymer can be arranged on part of the surface or the entire surface of the porous matrix, or in part of the pores or the entire pores of the porous matrix; or the polymer electrolyte can be arranged on part of the surface or the entire surface of the porous matrix, or in part of the pores or the entire pores of the porous matrix.

[0100] The present application does not limit the specific arrangement method. The arrangement method commonly used in the art can be used to arrange the polymer or polymer electrolyte on at least part of the surface of the porous matrix and / or in at least part of the pores of the porous matrix to form a diaphragm.

[0101] In some embodiments, the separator can be obtained by coating a polymer electrolyte raw material system on the separator, initiating polymerization of the raw material system, and curing the separator. Alternatively, the separator can be obtained by hot pressing or roll-combining a self-forming polymer electrolyte with a porous substrate. Alternatively, the separator can be obtained by coating the polymer system on the separator and curing the polymer system. The separator has a porous substrate, which can be any conventional porous substrate used for battery separators. For example, the porous matrix can be a membrane or fabric matrix formed by any one of the following polymers, and the polymer can be selected from at least one of polyethylene terephthalate, polybutylene terephthalate, polymethyl methacrylate, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene ether, polyphenylene sulfide, polyethylene naphthalene, polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, tetrafluoropropylene copolymer, and hexafluoropropylene copolymer; it can also be selected from at least one of copolymers, homopolymers, and derivatives of propylene, 1-butene, pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 1-decene.

[0102] In some embodiments, the membrane can be prepared by a method comprising the following steps: adding a polymer to a first solvent to obtain a first mixed solution; adding a lithium salt to the first solution and stirring uniformly to obtain a polymer system; casting the polymer system on at least a portion of the surface of the porous matrix, and then removing the first solvent to obtain a membrane.

[0103] The present application does not impose any particular limitation on the first solvent, which can be selected from commonly used solvents, such as N-methylpyrrolidone (NMP), acetone, methanol, ethanol, and the like.

[0104] In some embodiments, the method for preparing the separator may further include the following steps: the separator obtained after drying is subjected to a roller pressing process to make the polymer electrolyte more tightly bonded to the porous matrix.

[0105] The diaphragm of the present application, since it includes the above-mentioned polymer or polymer electrolyte, can improve the electrochemical performance of the battery and broaden the application scenarios of the battery when applied to the battery.

[0106] A fourth aspect of the present application is a battery, comprising the polymer of the first aspect;

[0107] or, comprising the polymer electrolyte of the second aspect;

[0108] Alternatively, the separator of the third aspect may be included. It is understood that the battery of the present application may further include a positive electrode sheet, a negative electrode sheet, and an outer packaging.

[0109] In some embodiments, a polymer and an electrolyte can be combined to form a gel electrolyte for use in a battery. That is, a positive electrode sheet, a polymer (or a separator), and a negative electrode sheet are stacked to form an electrode assembly, which is then placed in an outer package, injected with electrolyte, and sealed to form a battery.

[0110] In other embodiments, the positive electrode sheet, the polymer electrolyte (or the separator containing the polymer electrolyte), and the negative electrode sheet may be stacked to obtain an electrode assembly, and the electrode assembly may be placed in an outer package and sealed to obtain a battery.

[0111] Since the battery of the present application includes the above-mentioned polymer electrolyte, it has excellent electrochemical performance and excellent user experience, and is suitable for wide promotion and application.

[0112] The technical solution of this application is described in detail below through specific embodiments.

[0113] The sources of some components in the Examples and Comparative Examples are as follows. Components for which specific experimental steps or conditions are not specified in the Examples or Comparative Examples can be obtained by following the conventional experimental steps or conditions described in the prior art.

[0114] (1) Amine-based ionic liquids:

[0115] (1) 1-Aminoethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (CAS: 1384979-21-8) and 1-aminopropyl-3-methylimidazolium tetrafluoroborate (CAS: 914770-49-3) were purchased from Qingdao Oriko New Materials Technology Co., Ltd.

[0116] (2) (6-aminohexyl) triphenylphosphonium bromide bis(trifluoromethanesulfonyl)imide salt: prepared in the laboratory, the preparation process is as follows:

[0117] (6-aminohexyl)triphenylphosphonium bromide hydrobromide (purchased from Sigma-Aldrich) was dissolved in anhydrous ethanol (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and stirred until fully dissolved. Then, silver bis(trifluoromethanesulfonyl)imide (purchased from Sigma-Aldrich) was gradually added. Stirring was continued until silver bromide (AgBr) precipitated. The precipitate was removed by filtration, and the anhydrous ethanol was removed by vacuum rotary evaporation. After heating and drying, (6-aminohexyl)triphenylphosphonium bromide bis(trifluoromethanesulfonyl)imide salt was obtained.

[0118] (2) Triethylene glycol diacrylate: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0119] (III) 4,4'-Dicyclohexylmethane diisocyanate: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0120] (iv) Dibutyltin dilaurate: purchased from Sigma-Aldrich.

[0121] (5) Hexamethylene diisocyanate: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0122] (6) 1,4-Cyclohexanedimethanol divinyl ether: purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0123] (7) m-Xylylenediisocyanate: purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0124] (8) Polyethylene glycol diacrylate (Mn=575): purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0125] (IX) p-Phenylene diisocyanate: purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0126] (10) Diallyl disulfide: purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0127] Example 1

[0128] The battery of this embodiment is prepared by a method comprising the following steps:

[0129] 1) Preparation of polymer

[0130] allowing the amine-based ionic liquid to undergo a first reaction with a diene-based compound to obtain an imine-based ionic liquid;

[0131] allowing the imine-based ionic liquid to undergo a second reaction with the diisocyanate compound to obtain a polymer;

[0132] Wherein, the amine-based ionic liquid is 1-aminoethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, the diene compound is triethylene glycol diacrylate, and the diisocyanate compound is 4,4'-diphenylmethane diisocyanate;

[0133] In the first reaction, the ratio of the molar content of the amine group in the amine-based ionic liquid to the molar content of the alkenyl group in the diene compound was 1:1, the temperature was 60° C., and the reaction time was 12 h;

[0134] In the second reaction, the ratio of the molar content of the imine group in the imine ionic liquid to the molar content of the isocyanate group in the diisocyanate compound is 1:1, the temperature is 60° C., the time is 12 h, the catalyst is dibutyltin dilaurate, and the amount of the catalyst is 0.2 mol% of the sum of the amounts of the imine ionic liquid and the diisocyanate compound.

[0135] 2) Preparation of polymer electrolyte

[0136] Mixing the solvent, lithium salt and the polymer from step 1) and drying to obtain a polymer electrolyte;

[0137] Wherein, the lithium salt is lithium hexafluorophosphate and the solvent is NMP;

[0138] In the polymer electrolyte, the mass percentage of lithium salt is 10%, and the mass percentage of polymer is 90%.

[0139] 3) Battery preparation

[0140] The positive electrode sheet, polymer electrolyte and negative electrode sheet are stacked to obtain an electrolytic assembly, and the electrode assembly is placed in an aluminum-plastic film and sealed to obtain a battery;

[0141] The positive electrode sheet includes an aluminum foil and a positive electrode active layer disposed on the surface of the aluminum foil. The positive electrode active layer includes lithium cobalt oxide, a conductive agent Super P, and a binder PVDF. The mass ratio of lithium cobalt oxide, the conductive agent, and the binder is 96:2:2.

[0142] The negative electrode sheet includes a copper foil and a negative electrode active layer arranged on the surface of the copper foil. The negative electrode active layer includes silicon-doped graphite, a conductive agent Super P, and a binder PAA. The mass ratio of the silicon-doped graphite, the conductive agent, and the binder is 95:2:3.

[0143] Example 2

[0144] The preparation method of the battery of this embodiment is basically the same as that of embodiment 1, except that:

[0145] 1) Preparation of polymer

[0146] The diisocyanate compound is hexamethylene diisocyanate.

[0147] Example 3

[0148] The preparation method of the battery of this embodiment is basically the same as that of embodiment 1, except that:

[0149] 1) Preparation of polymer

[0150] The amine-based ionic liquid is 1-aminopropyl-3-methylimidazolium tetrafluoroborate, the diene compound is 1,4-cyclohexanedimethanol divinyl ether, and the diisocyanate compound is m-xylylenediisocyanate.

[0151] Example 4

[0152] The preparation method of the battery of this embodiment is basically the same as that of embodiment 1, except that:

[0153] 1) Preparation of polymer

[0154] The amino-based ionic liquid is 1-aminopropyl-3-methylimidazolium tetrafluoroborate, the diene compound is polyethylene glycol diacrylate (Mn=575), and the diisocyanate compound is p-phenylene diisocyanate.

[0155] Example 5

[0156] The preparation method of the battery of this embodiment is basically the same as that of embodiment 1, except that:

[0157] 1) Preparation of polymer

[0158] The amine-based ionic liquid is 1-aminopropyl-3-methylimidazolium tetrafluoroborate, the diene compound is diallyl disulfide, and the diisocyanate compound is p-phenylene diisocyanate.

[0159] Example 6

[0160] The preparation method of the battery of this embodiment is basically the same as that of embodiment 1, except that:

[0161] 1) Preparation of polymer

[0162] The amino ionic liquid is (6-aminohexyl) triphenylphosphonium bromide bistrifluoromethanesulfonyl imide salt, the diene compound is polyethylene glycol diacrylate (Mn=575), and the diisocyanate compound is p-phenylene diisocyanate.

[0163] In the first reaction, the ratio of the molar content of the amine groups in the amine-based ionic liquid to the molar content of the alkenyl groups in the diene compound is 1.2:1;

[0164] In the second reaction, the ratio of the molar content of the imine group in the imine ionic liquid to the molar content of the isocyanate group in the diisocyanate compound is 1:1.2.

[0165] Example 7

[0166] The preparation method of the battery of this embodiment is basically the same as that of Example 1, except that:

[0167] The polymer electrolyte is prepared by a method comprising the following steps:

[0168] allowing the amine-based ionic liquid to undergo a first reaction with a diene-based compound to obtain an imine-based ionic liquid;

[0169] allowing the imine-based ionic liquid, the diisocyanate compound, the lithium salt and the solvent to undergo a second reaction, followed by drying to obtain a polymer electrolyte;

[0170] The amine-based ionic liquid is 1-aminoethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, the diene compound is triethylene glycol diacrylate, and the diisocyanate compound is 4,4'-diisocyanate dicyclohexylmethane;

[0171] In the first reaction, the ratio of the molar content of the amine group in the amine-based ionic liquid to the molar content of the alkenyl group in the diene compound was 1:1, the temperature was 60° C., and the reaction time was 12 h;

[0172] In the second reaction, the ratio of the molar content of the imine group in the imine ionic liquid to the molar content of the isocyanate group in the diisocyanate compound is 1:1, the temperature is 60° C., the time is 12 h, the catalyst is dibutyltin dilaurate, and the amount of the catalyst is 0.2 mol% of the sum of the amounts of the imine ionic liquid and the diisocyanate compound;

[0173] The lithium salt is lithium hexafluorophosphate and the solvent is NMP;

[0174] In the polymer electrolyte, the mass percentage of lithium salt is 10%, and the mass percentage of polymer is 90%.

[0175] Example 8

[0176] The preparation method of the battery of this embodiment is basically the same as that of Example 1, except that:

[0177] 2) Preparation of polymer electrolyte

[0178] In the polymer electrolyte, the mass percentage of lithium salt is 40%, and the mass percentage of polymer is 60%.

[0179] Example 9

[0180] The preparation method of the battery of this embodiment is basically the same as that of Example 1, except that:

[0181] 2) Preparation of polymer

[0182] The amine-based ionic liquid includes 1-aminoethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-aminopropyl-3-methylimidazolium tetrafluoroborate and (6-aminohexyl)triphenylphosphonium bromide bis(trifluoromethanesulfonyl)imide, wherein the molar ratio of 1-aminoethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-aminopropyl-3-methylimidazolium tetrafluoroborate and (6-aminohexyl)triphenylphosphonium bromide bis(trifluoromethanesulfonyl)imide is 1:1:1.

[0183] Example 10

[0184] The preparation method of the battery of this embodiment is basically the same as that of Example 1, except that:

[0185] 2) Preparation of polymer

[0186] The diene compound includes triethylene glycol diacrylate, 1,4-cyclohexanedimethanol divinyl ether and polyethylene glycol diacrylate (Mn=575), wherein the molar ratio of triethylene glycol diacrylate, 1,4-cyclohexanedimethanol divinyl ether and polyethylene glycol diacrylate is 1:1:1.

[0187] Example 11

[0188] The preparation method of the battery of this embodiment is basically the same as that of Example 1, except that:

[0189] 2) Preparation of polymer

[0190] The diisocyanate compound comprises p-phenylene diisocyanate and m-phenylene diisocyanate, wherein the molar ratio of p-phenylene diisocyanate to m-phenylene diisocyanate is 1:1.

[0191] Comparative Example 1

[0192] The preparation method of the battery of this comparative example is basically the same as that of Example 1, except that:

[0193] The polymer electrolyte is prepared by a method comprising the following steps:

[0194] Polyetheramine D230, hexamethylene diisocyanate, lithium salt and solvent were mixed, reacted at 60° C. for 12 h, and then dried to remove the solvent to obtain a polymer electrolyte.

[0195] In the above reaction, the ratio of the molar content of the amino groups of the polyetheramine D230 to the molar content of the isocyanate groups of the hexamethylene diisocyanate is 1.1:1.

[0196] Comparative Example 2

[0197] The preparation method of the battery of this comparative example is basically the same as that of Example 1, except that:

[0198] The polymer electrolyte is prepared by a method comprising the following steps:

[0199] 1-aminoethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 4,4'-diisocyanate dicyclohexylmethane, lithium salt and solvent were mixed, reacted at 60°C for 12 hours, and then dried to remove the solvent to obtain a polymer electrolyte;

[0200] In the above reaction, the ratio of the molar content of the amino group of 1-aminoethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt to the molar content of the isocyanate group of hexamethylene diisocyanate is 1:2, the catalyst is dibutyltin dilaurate, and the amount of the catalyst used is 0.2 mol% of the sum of the amounts of the imine ionic liquid and the diisocyanate compound used.

[0201] Comparative Example 3

[0202] The preparation method of the battery of this comparative example is basically the same as that of Example 1, except that:

[0203] The polymer electrolyte is prepared by a method comprising the following steps:

[0204] 1-aminoethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, triethylene glycol diacrylate, lithium salt and solvent were mixed, reacted at 60° C. for 12 hours, and then dried to remove the solvent to obtain a polymer electrolyte;

[0205] In the above reaction, the ratio of the molar content of the amino group of 1-aminoethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt to the molar content of the vinyl group of triethylene glycol diacrylate is 1:2, the catalyst is dibutyltin dilaurate, and the amount of the catalyst used is 0.2 mol% of the sum of the amounts of the imine-based ionic liquid and the diisocyanate compound used.

[0206] Comparative Example 4

[0207] The preparation method of the battery of this comparative example is basically the same as that of Example 1, except that:

[0208] 1) Preparation of polymer

[0209] Adding an amine ionic liquid, a diene compound, and a diisocyanate compound into a reaction vessel to carry out a first reaction (the amine ionic liquid and the diisocyanate compound preferentially react to form a urea intermediate compound);

[0210] After adding a catalyst, the alkenyl group of the diene compound and the imine group of the urea intermediate compound undergo a second reaction to obtain a polymer;

[0211] In the first reaction, the ratio of the molar content of the amino group in the amino ionic liquid, the molar content of the alkenyl group in the diene compound, and the molar content of the isocyanate group in the diisocyanate compound is 1:1:1, the temperature is 60° C., and the reaction time is 2 h;

[0212] In the second reaction, the catalyst is dibutyltin dilaurate, the amount of the catalyst is 0.2 mol% of the sum of the amounts of the amino ionic liquid, the diene compound and the diisocyanate compound, the temperature is 60° C., and the time is 12 h.

[0213] Performance Testing

[0214] The following performance tests were performed on the polymers, polymer electrolytes or batteries in the examples and comparative examples, and the test results are shown in Table 1.

[0215] 1. Infrared test

[0216] The polymer in Example 1 was subjected to infrared testing. As shown in FIG1 , in the infrared spectrum of the polymer in Example 1, 3308 cm -1 and 1642cm -1 The absorption peaks at 1228 cm-1 come from the vibration absorption of NH and C=O bonds in the urea group; -1 The absorption peak at 1373 cm is the stretching vibration absorption peak of the CN bond. -1 The absorption peak at 1453 cm comes from the vibration absorption of tertiary amine, indicating the presence of tertiary amine groups in the polymer structure; -1 、1506cm -1 and 1594cm -1 The absorption peak at 1537cm comes from the stretching vibration absorption of the benzene ring; -1 The absorption peak at 1178 cm is the absorption peak of the imidazole ring skeleton vibration. -1 The absorption peak at 2860~2930cm comes from the stretching vibration absorption of the imidazole ring; -1 1102cm is the stretching vibration absorption peak of methyl and methylene; -1 The absorption peak at comes from the stretching vibration absorption of the ether bond in the polymer structure. This proves that Example 1 of the present application successfully prepared a polymer having the structure shown in Formula 1.

[0217] 2. Room temperature ionic conductivity

[0218] The test is carried out using the method specified in the "Test Method for Ionic Conductivity of Power Battery Membranes" (industry standard NB / T 10827-2021).

[0219] 3. Battery cycle performance

[0220] The test is carried out in accordance with the methods specified in the national standard GB / T31486-2015 "Electrical Performance Requirements and Test Methods for Power Batteries for Electric Vehicles".

[0221] 4. Limiting oxygen index

[0222] The test is carried out in accordance with the methods specified in GB / T2406.1-2008 "Plastics - Determination of Combustion Behavior by Oxygen Index Method - Part 1: Guidelines" and GB / T2406.2-2009 "Plastics - Determination of Combustion Behavior by Oxygen Index Method - Part 2: Room Temperature Test".

[0223] 5. Tensile strength test

[0224] The tensile strength of polymer electrolytes is measured according to the standard test method of ASTM D638-14 "Standard Test Method for Tensile Properties of Plastics".

[0225] Table 1

[0226] As can be seen from Table 1, the product of the embodiment of the present application has excellent room temperature ionic conductivity, battery capacity retention rate and limiting oxygen index, has excellent performance, and can be widely used.

[0227] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A polymer, wherein, The polymer comprises at least the structural formula shown in Formula 1; In Formula 1, R1 is selected from substituted or unsubstituted C1-C30 alkyl groups, and substituted or unsubstituted C6-C60 aryl groups; R2 is selected from substituted or unsubstituted polyether groups, substituted or unsubstituted C1-C30 alkyl groups, substituted or unsubstituted C1-C30 alkoxy groups, *-b1-S-S-b2-*; b1 and b2 are each independently selected from substituted or unsubstituted C2-C15 linear alkyl groups, and substituted or unsubstituted C6-C60 aryl groups; R3 is an ionic liquid group; n≥1 and is an integer.

2. The polymer according to claim 1, wherein, When the polymer includes multiple Formula 1 structural formulas, R3 is selected from the same ionic liquid group.

3. The polymer according to claim 1, wherein, When the polymer includes multiple Formula 1 structural formulas, at least one of the following is satisfied: a) The R1 in multiple Formula 1 structural formulas is selected from the same group; b) The R2 in multiple Formula 1 structural formulas is selected from the same group.

4. The polymer according to claim 1, wherein R3 is selected from one of imidazole-based ionic liquid groups, pyridine-based ionic liquid groups, quaternary ammonium-based ionic liquid groups, or quaternary phosphonium-based ionic liquid groups.

5. The polymer according to claim 4, wherein, The R3 is selected from any one of the following groups; Wherein, R4 is selected from substituted or unsubstituted C1-C30 alkyl groups, substituted or unsubstituted C1-C30 an alkoxy group; R5 is selected from substituted or unsubstituted C1-C10 alkyl groups; A is selected from BF4 - , PF6 - , TFSI - , OTf - , DCA - or TOS - .

6. The polymer according to any one of claims 1-5, wherein, The R2 is selected from any one of the following groups; Wherein, n is a positive integer.

7. The polymer according to any one of claims 1-6, wherein, At least one of the following is satisfied: a) R1 is a cyclic structure; b) R2 is a chain structure.

8. The polymer according to any one of claims 1-7, wherein, The polymer is obtained by reacting an imino ionic liquid with a diisocyanate compound.

9. A polymer electrolyte, wherein, The polymer electrolyte includes a lithium salt and the polymer according to any one of claims 1-8.

10. The polymer electrolyte according to claim 9, wherein, In the polymer electrolyte, the mass percentage content of the lithium salt is 5-30%, and the mass percentage content of the polymer is 70-95%.

11. A separator, wherein, It includes a porous matrix, and the polymer according to any one of claims 1-8 or the polymer electrolyte according to any one of claims 9-10 provided on at least part of the surface of the porous matrix and / or in at least part of the pores of the porous matrix.

12. A battery, wherein, It includes the polymer according to any one of claims 1-8; Or, it includes the polymer electrolyte according to any one of claims 9-10; Or, it includes the separator according to claim 11.

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