Polymer electrolyte and method of preparation, polysorbate and method of preparation and use

Abstract

The application discloses a polymer electrolyte and a preparation method thereof, a polysorbate and a preparation method and application thereof. The polymer electrolyte comprises a polymer base, a lithium salt and an additive; the additive comprises a polysorbate. The polymer electrolyte disclosed by the application has good ionic conductivity and good mechanical properties, and is thus beneficial to improving the cycle performance of a battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy, and in particular to a polymer electrolyte and a preparation method thereof, a polysorbate and a preparation method and application thereof. BACKGROUND

[0002] For the consumer electronics and electric vehicle markets with growing energy demand, it is urgent to develop sustainable high-energy density, high safety energy storage devices. Among all energy storage devices, lithium batteries are widely studied due to their excellent reversible capacity. However, the traditional lithium battery has serious side reactions between the liquid electrolyte and the electrode, resulting in low capacity, poor cycle stability, and the risk of liquid leakage and poor safety performance.

[0003] In the related art, when PVDF, PEO and other polymers are used as polymer solid electrolyte substrates, their crystallinity at room temperature is relatively high, resulting in low ionic conductivity. It is of great significance to reduce the crystallinity of polymers PVDF and PEO and improve their performance as polymer electrolyte substrates. SUMMARY

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a polymer electrolyte and a preparation method thereof, a polysorbate and a preparation method and application thereof. By adding the polysorbate, the crystallinity of the polymer is effectively reduced, thereby improving the ionic conductivity of the polymer electrolyte and the cycle stability of the battery. A method for preparing the polysorbate by radical polymerization is also provided, which is simple to operate.

[0005] In a first aspect, the present application provides a polymer electrolyte, comprising: a polymer substrate, a lithium salt and an additive.

[0006] The additive comprises a polysorbate.

[0007] As an optional solution, the polysorbate comprises at least one of alkali metal polysorbate; preferably, the alkali metal polysorbate comprises at least one of lithium polysorbate, sodium polysorbate, potassium polysorbate, calcium polysorbate or magnesium polysorbate; preferably, the alkali metal polysorbate comprises lithium polysorbate.

[0008] As an optional solution, the addition amount of the polysorbate is 5% to 12.5% of the mass of the polymer substrate.

[0009] As an optional solution, the molecular weight of the polysorbate is 1000 to 50000.

[0010] As an optional solution, the polymer substrate comprises at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-trifluorochloroethylene copolymer, polyethylene oxide, thermoplastic polyurethane, polypropylene oxide, polycarbonate, polyvinyl alcohol, polyacrylic acid, polyethyl methacrylate, polymethyl methacrylate, polyacrylonitrile, and polyvinyl chloride.

[0011] As an optional solution, the lithium salt comprises at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis-trifluoromethylsulfonylimide, lithium bisfluorosulfonylimide, lithium bis-oxalato-borate, lithium difluoro-oxalato-borate, and lithium trifluoromethanesulfonate.

[0012] As an optional solution, the lithium salt is added in an amount of 30%-60% of the mass of the polymer substrate, preferably, the lithium salt is added in an amount of 50%-60% of the mass of the polymer substrate.

[0013] In a second aspect, the present application provides a method for preparing the polymer electrolyte of the first aspect, comprising:

[0014] Mixing the polymer substrate, the lithium salt, the polysorbate, and the organic solvent to obtain a mixed solution, and solidifying the mixed solution to obtain the polymer electrolyte.

[0015] As an optional solution, the method for preparing the polysorbate comprises:

[0016] Mixing the sorbic acid solution and the metal base to obtain the polysorbate.

[0017] As an optional solution, in the method for preparing the polysorbate, the molar ratio of the sorbic acid monomer in the sorbic acid solution to the metal ion in the metal base is (1:1.2)-(1:1.6).

[0018] As an optional solution, in the process of mixing the sorbic acid solution and the metal base under the action of the initiator to obtain the polysorbate, the process comprises:

[0019] Mixing the sorbic acid and the initiator, and heating to react to obtain the sorbic acid solution;

[0020] Adding the metal base to the sorbic acid solution, continuing to react to a swollen state, and drying to obtain the polysorbate.

[0021] As an optional solution, in the process of mixing the sorbic acid and the initiator, and heating to react to obtain the sorbic acid solution, the reaction temperature is 60°C-70°C, and the reaction time is 2h-4h.

[0022] As an optional solution, the metal base comprises at least one of lithium hydroxide, sodium hydroxide, and potassium hydroxide.

[0023] As an option, the initiator includes azobisisobutyronitrile, azobisisoheptyl nitrile, dibenzoyl peroxide, diethylhexyl peroxydicarbonate, cumene hydroperoxide, t-butyl hydroperoxide, dilauryl peroxide, t-butyl peroxybenzoate, t-butyl peroxy pivalate, diisopropyl peroxydicarbonate, potassium persulfate, or ammonium persulfate.

[0024] As an option, in the preparation of the polymer electrolyte, the organic solvent includes at least one of diethyl ether, ethanol, acetonitrile, N,N dimethylformamide, N,N dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azelonitrile, and sebonitrile.

[0025] As an option, in the preparation of the polymer electrolyte, the solidification method is solution casting.

[0026] Preferably, drying is performed after solidification.

[0027] In a third aspect, the present application provides a method for preparing a polysorbate, comprising:

[0028] mixing a polysorbic acid solution and a metal base to obtain the polysorbate.

[0029] As an option, in the method for preparing the polysorbate, the molar ratio of sorbic acid monomers in the polysorbic acid solution to metal ions in the metal base is (1:1.2) to (1:1.6).

[0030] As an option, mixing the polysorbic acid solution and the metal base to obtain the polysorbate includes:

[0031] mixing sorbic acid and an initiator and heating to react to obtain the polysorbic acid solution;

[0032] adding the metal base to the polysorbic acid solution, continuing the reaction until a swollen state, and drying to obtain the polysorbate.

[0033] As an option, in the process of mixing the sorbic acid and the initiator and heating to react to obtain the polysorbic acid solution, the reaction temperature is 60°C to 70°C, and the reaction time is 2 hours to 4 hours.

[0034] As an option, the metal base includes at least one of lithium hydroxide, sodium hydroxide, and potassium hydroxide.

[0035] As an option, the initiator includes azobisisobutyronitrile, azobisisoheptyl nitrile, dibenzoyl peroxide, diethylhexyl peroxydicarbonate, cumene hydroperoxide, t-butyl hydroperoxide, dilauryl peroxide, t-butyl peroxybenzoate, t-butyl peroxy pivalate, diisopropyl peroxydicarbonate, potassium persulfate, or ammonium persulfate.

[0036] In a fourth aspect, the present application provides a polysorbate prepared according to the method of the second aspect.

[0037] As an optional solution, the polysorbate includes at least one of lithium polysorbate, sodium polysorbate, potassium polysorbate, calcium polysorbate or magnesium polysorbate, and preferably the alkali metal polysorbate includes lithium polysorbate.

[0038] In a fifth aspect, the present application provides a battery, characterized in that the battery includes the polymer electrolyte of the first aspect, or the polymer electrolyte prepared according to the preparation method of the second aspect, or the polysorbate prepared according to the preparation method of the third aspect, or the polysorbate of the fourth aspect.

[0039] In a sixth aspect, the present application provides an electrical equipment, including the battery of the fifth aspect, and the battery supplies power to the electrical equipment.

[0040] The polymer electrolyte provided by the present application is more conducive to reliably reducing the crystallinity of the polymer substrate and improving the ionic conductivity of the polymer electrolyte by adding the polysorbate additive, and the larger polyanion group in the polysorbate is mixed with the polymer substrate, and the carboxyl group in the sorbic acid as a polar group can provide more active sites for the transmission of lithium ions, which is further conducive to improving the ionic conductivity of the polymer electrolyte. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 The charge-discharge cycle curve of the battery of Example 1 of the present application at a current density of 0.5C. DETAILED DESCRIPTION

[0042] The present application will be further described in detail below with reference to examples. It can be understood that the specific examples described herein are only used to explain the related application, and not to limit the application.

[0043] It should be noted that the examples in the present application and the features in the examples can be combined with each other without conflict. The present application will be described in detail below with reference to examples.

[0044] In a first aspect, the embodiments of the present application provide a polymer electrolyte, including: a polymer substrate, a lithium salt and an additive.

[0045] The additive includes a polysorbate.

[0046] The polysorbate can be any kind of polysorbate metal salt, such as but not limited to lithium polysorbate, sodium polysorbate, potassium polysorbate, calcium polysorbate or magnesium polysorbate, etc.

[0047] It can be understood that the polyanion group in the polysorbate is conducive to reducing the crystallinity of the polymer substrate; the carboxyl group in the polysorbate can provide more active sites for the transmission of lithium ions.

[0048] The larger the molecular weight of the polysorbate is, the larger the polyanion group is, and the more effective the polysorbate mixed with the polymer substrate is in reducing the crystallinity of the polymer substrate.

[0049] The polymer electrolyte of the embodiments of the present application solves the problem of low ionic conductivity of the existing polymer electrolyte. By adding polysorbate, the larger polyanion group in the polysorbate is mixed with the polymer substrate, and within a reasonable range, the larger the molecular weight of the polysorbate is, the more conducive it is to reliably reduce the crystallinity of the polymer substrate, thereby improving its ionic conductivity; and the carboxyl group in the sorbic acid as a polar group can provide more active sites for the transmission of lithium ions, which is conducive to improving the ionic conductivity of the polymer electrolyte.

[0050] In some embodiments, the polysorbate includes at least one of an alkali metal polysorbate.

[0051] In preferred embodiments, the alkali metal polysorbate includes lithium polysorbate. The lithium polysorbate in the embodiments of the present application can provide lithium ions, which is conducive to reliably conducting active ions and improving the ionic conductivity of the polymer electrolyte.

[0052] As an implementable way, the addition amount of the polysorbate is 5%-12.5% of the mass of the polymer substrate.

[0053] The addition amount of the polysorbate in the present embodiment is conducive to reliably improving the ionic conductivity of the polymer electrolyte, and can be uniformly mixed with the polymer substrate to avoid the formation of large particles.

[0054] Specifically, the addition amount of the polysorbate can be, but is not limited to, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, or 12.5% of the mass of the polymer substrate. When the addition amount of the polysorbate is less than 5% of the mass of the polymer substrate, the content of the polysorbate is low, which cannot reliably improve the ionic conductivity of the polymer electrolyte; when the content of the polysorbate is higher than 12.5% of the mass of the polymer substrate, the content of the polysorbate is high, which not only cannot further improve the ionic conductivity, but also causes part of the polymer substrate to react and produce precipitated particles due to the alkalinity of the polysorbate, greatly affecting the uniformity of the polymer electrolyte.

[0055] As a realizable manner, the molecular weight of the polysorbate is 1000-50000. The molecular weight of the polysorbate in this embodiment is conducive to improving the ionic conductivity of the polymer electrolyte while ensuring that the polymer electrolyte has good mechanical properties.

[0056] Specifically, the molecular weight of the polysorbate can be, but is not limited to, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, 26000, 27000, 28000, 29000, 30000, 31000, 32000, 33000, 34000, 35000, 36000, 37000, 38000, 39000, 40000, 41000, 42000, 43000, 44000, 45000, 46000, 47000, 48000, 49000, or 50000, etc. When the molecular weight of the polysorbate is less than 1000, the molecular weight is too low, and after mixing with the polymer substrate, the crystallinity of the polymer substrate cannot be reliably reduced, resulting in that the ionic conductivity of the polymer electrolyte cannot be reliably improved; when the molecular weight of the polysorbate is higher than 50000, the molecular weight is too high, resulting in that the mechanical properties of the polymer electrolyte are decreased, and it is difficult to form a film or the formed film is easy to break.

[0057] In some embodiments, the polymer substrate comprises at least one of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyvinylidene fluoride-chlorotrifluoroethylene copolymer (PVDF-CTFE), polyethylene oxide (PEO), thermoplastic polyurethane (TPU), polypropylene oxide (PPO), polycarbonate (PPC), polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyethyl methacrylate (PEMA), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), and polyvinyl chloride (PVC). The polymer in this embodiment has excellent performance and the raw material is easy to obtain, so as to ensure that the prepared polymer electrolyte film has excellent electrochemical performance.

[0058] As a realizable manner, the lithium salt comprises at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium bis-trifluoromethylsulfonylimide (LiTFSI), lithium bis-fluorosulfonylimide (LiFSI), lithium bis-oxalate borate (LiBOB), lithium difluoro(oxalato)borate (LiODFB), and lithium trifluoromethanesulfonate (LiCF3SO3).

[0059] As a realizable manner, the adding amount of the lithium salt is 30%-60% of the mass of the polymer substrate.

[0060] The adding amount of the lithium salt in the embodiment is advantageous to ensure that the polymer electrolyte membrane has reliable active ion sources and the polymer electrolyte has good mechanical properties.

[0061] Specifically, the adding amount of the lithium salt can be, but is not limited to, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 53%, 55%, 58% or 60% of the mass of the polymer substrate. When the adding amount of the lithium salt is less than 30%, the adding amount of the lithium salt is too low, which can cause a serious reduction in the ion conductivity of the polymer electrolyte. When the adding amount of the lithium salt is higher than 60%, the adding amount of the lithium salt is too high, which can cause a reduction in the mechanical properties of the polymer electrolyte, and even the polymer electrolyte is difficult to form a film.

[0062] In a preferred embodiment, the adding amount of the lithium salt is 50%-60% of the mass of the polymer substrate.

[0063] In summary, the polymer electrolyte of the embodiment of the application can reliably improve the ion conductivity of the polymer electrolyte by adding the polysorbate, and ensure that the polymer electrolyte has good mechanical properties, so that the polymer electrolyte can be uniformly formed into a film.

[0064] In addition, the embodiment of the application can improve the ion conductivity of the polymer electrolyte while ensuring that the polymer electrolyte can be uniformly formed into a film and has good mechanical properties by adjusting the amount of the polysorbate.

[0065] In a second aspect, the embodiment of the application provides a preparation method of the polymer electrolyte of the first aspect, comprising:

[0066] The polymer substrate, the lithium salt, the polysorbate and the organic solvent are mixed to obtain a mixed solution, and the mixed solution is solidified to obtain the polymer electrolyte.

[0067] Specifically, the polymer substrate is dissolved in the organic solvent, and the lithium salt and the polysorbate are added. After uniform stirring, a mixed solution is obtained, and the mixed solution is solidified to obtain the polymer electrolyte.

[0068] It can be understood that the organic solvent is mainly used to disperse the polymer, the lithium salt and the polysorbate, so that the obtained polymer electrolyte is uniformly distributed.

[0069] The lithium salt is used as a source of active ions in the polymer electrolyte, and is used to ensure that the polymer electrolyte has good transmission ability of active ions. If the lithium salt is not added, the polymer electrolyte will lose the function of conducting active ions, and the whole battery cannot work normally.

[0070] It can also be understood that the stirring method can be magnetic stirring, shaking or ball milling, and the like, and the embodiments of the present application do not make specific limitations as long as uniform mixing is ensured.

[0071] In actual processing, the obtained mixed solution is coated on a polytetrafluoroethylene plate or a tempered glass plate to prepare a polymer electrolyte film by a solution coating method.

[0072] The preparation method of the polymer electrolyte of the embodiments of the present application is simple in operation, short in process time, and the obtained sulfide composite material has a uniform microstructure distribution, which can effectively improve the ionic conductivity of the polymer electrolyte.

[0073] As an implementable manner, the preparation method of the polysorbate includes:

[0074] The polysorbate is obtained by mixing the polysorbate solution and the metal base.

[0075] The polysorbate is obtained by mixing the polysorbate solution and the metal base.

[0076] In some embodiments, in the preparation method of the polysorbate, the molar ratio of the sorbic acid monomers in the polysorbate solution to the metal ions in the metal base is (1:1.2)-(1:1.6).

[0077] The sorbic acid monomers in the polysorbate solution refer to the repeating unit sorbic acid monomers in the polysorbate molecules.

[0078] The molar ratio of the polysorbate solution and the metal base disclosed in the embodiments is beneficial to the full reaction of the polysorbate solution and the metal base.

[0079] Specifically, the molar ratio of the sorbic acid monomers in the polysorbate solution to the metal ions in the metal base can be but is not limited to 1:1.2, 1:1.4, 1:1.6, etc. When the molar ratio of the sorbic acid monomers in the polysorbate solution to the metal ions in the metal base is lower than 1:1.2, the metal base is too little to fully react, and when the molar ratio of the sorbic acid monomers in the polysorbate solution to the metal ions in the metal base is higher than 1:1.6, the metal base is too much, resulting in too much alkali solution, causing waste and environmental pollution.

[0080] In a preferred embodiment, under the action of the initiator, the process of mixing the polysorbate solution and the metal base to obtain the polysorbate includes:

[0081] The polysorbate solution is obtained by mixing sorbic acid and an initiator and heating to react;

[0082] Specifically, sorbic acid and initiator are heated and dissolved in a solvent, and a poly-sorbate solution is obtained by heating reaction, wherein the solvent can be water, DMF, etc., and the embodiments of the present application do not specifically limit this.

[0083] In a preferred embodiment, water is selected as the solvent, which is simple and environmentally friendly, and the prepared poly-sorbate is applied to a polymer electrolyte, which has a better conductivity improvement effect on the polymer electrolyte.

[0084] Metal base is added to the poly-sorbate solution, and the reaction continues until the swelling state is reached, and the poly-sorbate metal salt is obtained after drying.

[0085] It should be noted that the role of the initiator is mainly to initiate the formation of sorbic acid radicals and promote the polymerization of sorbate to form poly-sorbate; the -COOH group in poly-sorbate is an acidic group, and the metal base is an alkaline substance, which can undergo acid-base neutralization reaction, and the H + in -COOH reacts with the OH - group of LiOH to form -COOM, which improves the electrochemical window.

[0086] In the present embodiment, under the action of sorbic acid initiator, the double bond is opened to form poly-sorbate, and the poly-sorbate reacts with the metal base to form the corresponding poly-sorbate salt.

[0087] As an implementable way, during the process of mixing sorbic acid and initiator and heating to obtain a poly-sorbate solution, the reaction temperature is 60-70°C, and the reaction time is 2-4h.

[0088] The heating method can be water bath heating, oil bath heating or oven heating, etc., and the embodiments of the present application do not specifically limit this.

[0089] Heating is conducive to the opening of the double bond in sorbic acid, and the initiator promotes its own polymerization to form poly-sorbate.

[0090] The reaction temperature and time in the present embodiment are mild and controllable, and are conducive to promoting the formation of poly-sorbate.

[0091] Specifically, the reaction temperature can be but is not limited to 60°C, 62°C, 65°C, 68°C or 70°C. When the reaction temperature is lower than 60°C, the temperature is too low, and the polymerization reaction is difficult to occur. When the reaction temperature is higher than 70°C, the temperature is too high, and the reaction degree is difficult to control, which affects the chain length and molecular weight of polysorbic acid. The reaction time can be but is not limited to 2h, 2.5h, 3h, 3.5h or 4h. When the reaction time is less than 2h, the time is too short, and the polymerization reaction degree is difficult to reach the expectation. When the reaction time is more than 4h, the time is too long, and the polymerization degree of polysorbic acid no longer has a significant effect, but it will cause energy waste.

[0092] In a preferred embodiment, the sorbic acid and the initiator are dissolved in deionized water, heated at 60°C for 2h to obtain a polysorbic acid solution.

[0093] As a realizable way, the metal base includes at least one of lithium hydroxide, sodium hydroxide and potassium hydroxide.

[0094] As a realizable way, the initiator includes azobisisobutyronitrile, azobisisoheptyl nitrile, dibenzoyl peroxide, diethylhexyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, dodecanoyl peroxide, tert-butyl benzene peroxide, tert-butyl tert-amyl peroxide, diisopropyl peroxide, potassium persulfate or ammonium persulfate. The initiator of the present embodiment is easy to obtain raw materials, and can reliably initiate the polymerization of sorbic acid.

[0095] As a realizable way, in the preparation process of the polymer electrolyte, the organic solvent includes at least one of diethyl ether, ethanol, acetonitrile, N,N dimethyl formamide, N,N dimethyl acetamide, N-methyl pyrrolidone, tetrahydrofuran, malononitrile, butanedinitrile, pentanedinitrile, hexanedinitrile, heptanedinitrile, octanedinitrile, nonanedinitrile and decanedinitrile. The organic solvent of the present embodiment is easy to obtain raw materials, has little pollution, is safe to use, can reliably dissolve and disperse the polymer base, lithium salt and polysorbate, ensure the uniform dispersion of the polymer electrolyte slurry, and is conducive to obtaining a polymer electrolyte film with excellent performance.

[0096] In a preferred embodiment, in the preparation process of the polymer electrolyte, the solidification method is solution casting; the solution casting method of the present embodiment is simple to operate, and can ensure uniform film formation of the polymer electrolyte.

[0097] In a preferred embodiment, drying is performed after solidification, wherein the drying atmosphere can be an air atmosphere or an inert atmosphere; the drying method can be air oven drying, vacuum drying box drying, or freeze drying, which is not limited in the present embodiment.

[0098] The present embodiment performs drying after solidification, which is conducive to better film formation of the polymer electrolyte film, so that the polymer electrolyte film has excellent performance.

[0099] In a third aspect, embodiments of the present application provide a method for preparing polysorbate, comprising:

[0100] In the method, the polysorbate is obtained by dissolving polysorbate in a metal base solution to perform an acid-base neutralization reaction.

[0101] In some embodiments, in the method for preparing polysorbate, the molar ratio of sorbic acid monomers in the polysorbate solution to metal ions in the metal base is (1:1.2)-(1:1.6).

[0102] In the method, the sorbic acid monomers in the polysorbate solution refer to the repeating unit sorbic acid monomers in the polysorbate molecules.

[0103] The molar ratio of the polysorbate solution to the metal base disclosed in the embodiments is beneficial to the full reaction of the polysorbate solution and the metal base.

[0104] Specifically, the molar ratio of the sorbic acid monomers in the polysorbate solution to the metal ions in the metal base can be, but is not limited to, 1:1.2, 1:1.4, or 1:1.6. When the molar ratio of the sorbic acid monomers in the polysorbate solution to the metal ions in the metal base is less than 1:1.2, the metal base is too little to fully react, and when the molar ratio of the sorbic acid monomers in the polysorbate solution to the metal ions in the metal base is higher than 1:2, the metal base is too much, resulting in too much base solution, causing waste and environmental pollution.

[0105] In preferred embodiments, under the action of the initiator, the polysorbate solution and the metal base are mixed to obtain the polysorbate.

[0106] The sorbic acid and the initiator are mixed and heated to obtain the polysorbate solution;

[0107] Specifically, the sorbic acid and the initiator are dissolved in a solvent and heated to obtain the polysorbate solution, wherein the solvent can be water, DMF, etc., and the embodiments of the present application do not make specific limitations thereon.

[0108] In preferred embodiments, the solvent is water, which is simple and environmentally friendly.

[0109] The metal base is added to the polysorbate solution, and the reaction is continued until the swelling state is reached, and then the polysorbate metal salt is obtained after drying.

[0110] It should be noted that the role of the initiator is mainly to initiate the formation of free radicals of sorbic acid, and to promote the polymerization of sorbic acid to form polysorbate; the -COOH group in the polysorbate is an acidic group, and the metal base is a basic substance, and the two can perform an acid-base neutralization reaction, and the H + OH of LiOH -In combination, -COO- is combined with a metal ion to form -COOM.

[0111] In this embodiment, under the action of sorbic acid initiator, the double bond is opened to form polysorbic acid, and the acid-base reaction occurs between polysorbic acid and metal base to generate the corresponding polysorbate.

[0112] As a realizable way, during the process of mixing sorbic acid and initiator and heating reaction to obtain polysorbic acid solution, the reaction temperature is 60-70°C, and the reaction time is 2-4h.

[0113] Among them, the heating method can be water bath heating, oil bath heating or oven heating, etc., and the embodiments of the present application do not make specific limitation.

[0114] The heating is conducive to the opening of the double bond in sorbic acid, and the self-polymerization occurs under the action of the initiator to generate polysorbic acid.

[0115] The reaction temperature and time in this embodiment are mild, the reaction is controllable, and it is conducive to promoting the generation of polysorbic acid.

[0116] Specifically, the reaction temperature can be but is not limited to 60°C, 62°C, 65°C, 68°C or 70°C. When the reaction temperature is lower than 60°C, the temperature is too low, and the polymerization reaction is difficult to occur. When the reaction temperature is higher than 70°C, the temperature is too high, and the reaction degree is difficult to control, which affects the chain length and molecular weight of polysorbic acid; the reaction time can be but is not limited to 2h, 2.5h, 3h or 3.5h. When the reaction time is less than 2h, the time is too short, and the polymerization reaction degree is difficult to reach the expectation. When the reaction time is more than 4h, the time is too long, and it has no significant effect on the polymerization degree of polysorbic acid, but it will cause energy waste.

[0117] In a preferred embodiment, sorbic acid and initiator are dissolved in deionized water together, heated at 60°C for 2h to obtain a polysorbic acid solution.

[0118] As a realizable way, the metal base includes at least one of lithium hydroxide, sodium hydroxide and potassium hydroxide.

[0119] As a realizable way, the initiator includes azobisisobutyronitrile, azobisisoheptyl nitrile, dibenzoyl peroxide, diethylhexyl peroxide, cumene peroxide, tert-butyl hydroperoxide, dodecanoyl peroxide, tert-butyl perbenzoate, tert-butyl peroxypivalate, diisopropyl peroxide, potassium persulfate or ammonium persulfate. The initiator of the present embodiment is easy to obtain, and can reliably initiate the polymerization of sorbic acid.

[0120] In a fourth aspect, embodiments of the present application provide a polysorbate prepared according to the method of the third aspect. Thus, the polysorbate has all the features and advantages of the method of preparing the polysorbate as described above, which will not be repeated here.

[0121] As an implementable manner, the polysorbate includes at least one of alkali metal polysorbate;

[0122] Preferably, the alkali metal polysorbate includes at least one of lithium polysorbate, sodium polysorbate, potassium polysorbate, calcium polysorbate or magnesium polysorbate, preferably the alkali metal polysorbate includes lithium polysorbate.

[0123] In a fifth aspect, embodiments of the present application provide a battery including the polymer electrolyte of the first aspect, or the polymer electrolyte prepared according to the method of the second aspect, or the polysorbate prepared according to the method of the third aspect, or the polysorbate of the fourth aspect. Thus, the battery has all the features and advantages of the polymer electrolyte, the method of preparing the polymer electrolyte, the polysorbate, the method of preparing the polysorbate as described above, which will not be repeated here. In general, the battery has good capacity performance and stability.

[0124] It can be understood that the battery can be a lithium ion battery, a lithium metal battery, a lithium-sulfur battery or a lithium ion solid-state battery, and embodiments of the present application do not make specific limitations thereto.

[0125] In a sixth aspect, embodiments of the present application provide an electrical equipment including the battery of the fifth aspect, and the battery supplies power to the electrical equipment. Thus, the electrical equipment has all the features and advantages of the battery as described above, which will not be repeated here.

[0126] Specifically, the electrical equipment can be an electric vehicle, a hybrid vehicle or a smart terminal device (such as but not limited to a mobile phone), etc.

[0127] The present application will be described below through specific embodiments. It should be noted that the specific embodiments below are only for illustrative purposes, and do not limit the scope of the present application in any way. In addition, unless otherwise specified, the methods without specific description of conditions or steps are conventional methods, and the reagents and materials used can be obtained from commercial channels.

[0128] Example 1

[0129] (1) Preparation of lithium polysorbate:

[0130] 8 g of sorbic acid and 0.04 g of AIBN were dissolved in 30 mL of deionized water, and after magnetic stirring until dissolution, heating was carried out in a water bath at 60°C for 2 h to obtain a polysorbic acid solution; 2.4 g of LiOH powder was added to the above polysorbic acid solution, and stirring was continued until it became a paste-like solid (swollen state), and after vacuum drying of the product at 60°C overnight, a lithium polysorbate product was obtained.

[0131] (2) Preparation of the polymer electrolyte:

[0132] 4 g of PVDF was dissolved in DMF, then lithium polysorbate equivalent to 12.5% of the mass of PVDF was added, and LiTFSI was added at 60 wt% of the mass of PVDF, and after magnetic stirring at 40°C for 24 h, a homogeneous mixture was formed;

[0133] The mixture was poured onto a clean glass plate, and after drying in a vacuum drying oven at 80°C for 8 h, a brown film was peeled off from the glass plate, and the obtained film was cut into a Φ16 mm circular electrolyte sheet;

[0134] Example 2

[0135] The difference between this example and Example 1 is that the amount of lithium polysorbate added in this example is 5%.

[0136] Example 3

[0137] The difference between this example and Example 1 is that the amount of lithium polysorbate added in this example is 7.5%.

[0138] Example 4

[0139] The difference between this example and Example 1 is that the amount of lithium polysorbate added in this example is 10%.

[0140] Example 5

[0141] The difference between this example and Example 1 is that the amount of lithium polysorbate added in this example is 14%.

[0142] Example 6

[0143] The difference between this example and Example 1 is that the amount of lithium polysorbate added in this example is 2.5%.

[0144] Example 7

[0145] The difference between this example and Example 1 is that the amount of lithium polysorbate added in this example is 16%.

[0146] Example 8

[0147] The difference between this example and Example 1 is that lithium polysorbate is replaced by potassium polysorbate in this example.

[0148] Example 9

[0149] Different from example 1, the polymer substrate in this example is PEO.

[0150] Example 10

[0151] Different from example 1, the amount of LiTFSI added in this example is 30% of PVDF.

[0152] Example 11

[0153] Different from example 1, the amount of LiTFSI added in this example is 40% of PVDF.

[0154] Example 12

[0155] Different from example 1, the amount of LiTFSI added in this example is 70% of PVDF.

[0156] Example 13

[0157] Different from example 1, the molar ratio of polysorbic acid and lithium hydroxide in this example is 1:1.6.

[0158] Example 14

[0159] Different from example 1, the molar ratio of polysorbic acid and lithium hydroxide in this example is 1:1.8.

[0160] Example 15

[0161] Different from example 1, the reaction temperature in the preparation of lithium polysorbate in this example is 70℃.

[0162] Example 16

[0163] Different from example 1, the reaction temperature in the preparation of lithium polysorbate in this example is 80℃.

[0164] Example 17

[0165] Different from example 1, the reaction temperature in the preparation of lithium polysorbate in this example is 50℃.

[0166] Example 18

[0167] Different from example 1, the reaction time in the preparation of lithium polysorbate in this example is 4h.

[0168] Example 19

[0169] Different from example 1, the reaction time in the preparation of lithium polysorbate in this example is 5h.

[0170] Example 20

[0171] The difference between this example and Example 1 is that the reaction time in the preparation of lithium sorbate is 1 h.

[0172] Comparative Example 1

[0173] The difference between this comparative example and Example 1 is that no lithium sorbate is added in the preparation of the polymer electrolyte.

[0174] The ion conductivity of the polymer electrolyte membrane and the lithium ion battery performance test process and test results are described below:

[0175] (1) Ion conductivity

[0176] The above prepared electrolyte sheet (CSEs) and two stainless steel electrodes (SS) are tested to form a SS / CSEs / SS simulated battery. The battery assembly process is carried out in a glove box with water and oxygen content of less than 0.1 ppm. The electrochemical impedance of the composite solid electrolyte is measured at room temperature by alternating current impedance spectroscopy (EIS) test in the frequency range of 0.01 Hz to 10 6 Hz. The impedance data obtained by EIS test is used to calculate the ion conductivity of the prepared composite solid electrolyte.

[0177] (2) Lithium ion battery performance test

[0178] The above prepared electrolyte sheet (CSEs) and lithium iron phosphate (LiFePO4) positive electrode and lithium metal negative electrode are combined to form a button cell. The battery is prepared in a glove box. The battery is tested for charge and discharge cycling at a rate of 0.5C, and the decay of its discharge capacity is detected.

[0179] The results of the polymer electrolyte membrane and lithium ion battery of Examples 1-20 and Comparative Example 1 tested according to the above process and method are shown in Table 1:

[0180] Table 1 Test results of Examples 1-20 and Comparative Example 1

[0181]

[0182]

[0183] As Figure 1 shown, the polymer electrolyte membrane prepared in Example 1 is assembled into a button cell and tested for charge and discharge cycling at a rate of 0.5C. The specific capacity of discharge and charge is high, and has good stability.

[0184] According to the results shown in Table 1:

[0185] The test results of Examples 1-6 compared to Comparative Example 1 show that the ionic conductivity of the polymer electrolyte of Examples 1-6 is higher than that of the polymer electrolyte of Comparative Example 1, and the discharge capacity of the polymer electrolyte assembled battery of Examples 1-6 is higher after 20 cycles, indicating that the addition of lithium polysorbate indeed effectively improves the ionic conductivity of the polymer solid-state electrolyte and improves the charge-discharge cycle stability of the solid-state battery; in Example 5, the addition amount of lithium polysorbate exceeds 12.5%, and the increase in ionic conductivity is no longer obvious compared to Example 1; in Example 6, the addition amount of lithium polysorbate is less, and the ionic conductivity and the discharge capacity of the battery decrease significantly; in Example 7, the addition amount of lithium polysorbate is 16%, although the ionic conductivity increases, but the prepared lithium polysorbate material has a certain basicity, which will react with PVDF to form particulate matter, affecting the uniformity of the electrolyte membrane, and thus the performance of the electrolyte membrane is reduced, resulting in a decrease in cycle performance; the polymer electrolyte film in Comparative Example 1 does not add lithium polysorbate, resulting in too low ionic conductivity of the polymer electrolyte film, and the cycle of the assembled button cell at room temperature is extremely poor, and the capacity is extremely low, and the battery cannot be charged and discharged for more than 30 times.

[0186] The test results of Examples 8 and 9 compared to Comparative Example 1 show that different polysorbate salts are beneficial to improve the ionic conductivity of the polymer electrolyte film and the cycle stability of the battery; and the polysorbate salt additive of the examples of the present application and the polymer electrolyte for different polymer substrates can improve the ionic conductivity thereof;

[0187] The test results of Examples 1 and Examples 10-12 show that the addition amount of lithium salt LiTFSI of the examples of the present application can effectively improve the ionic conductivity performance of the polymer electrolyte, and in Example 12, the addition amount of lithium salt is too high, although the ionic conductivity is slightly improved, but the cycle performance of the battery is decreased, indicating that too high addition amount of lithium salt can seriously reduce the mechanical properties of the film, thereby reducing the cycle performance of the battery;

[0188] Examples 1, Example 13 and Example 14 show that in the process of preparing lithium polysorbate by acid-base neutralization, too high content of LiOH added will make lithium polysorbate carry too strong basicity, thereby causing a decrease in the performance of the electrolyte;

[0189] The test results of Example 1 and Examples 15-20 show that the temperature and time range in the polymerization process of the polysorbic acid of the embodiments of the present application is beneficial to the polymerization of sorbic acid, so that the molecular weight of the obtained polysorbic acid is large, and in turn is beneficial to the improvement of the ionic conductivity of the polymer electrolyte; in Example 17, the temperature is too low to reach the decomposition temperature of the initiator, and the polymerization cannot be effectively carried out, resulting in a significant decrease in ionic conductivity; in Example 16, the temperature is too high, resulting in too fast polymerization rate, uneven polymerization, and even occurrence of side reactions, resulting in a decrease in ionic conductivity material; in Example 20, the heating time in the polymerization process is too short, the monomer is not completely polymerized, and the ionic conductivity is significantly decreased; in Example 19, the polymerization time is too long, and the influence on the polymerization degree / molecular weight is no longer significant, and the ionic conductivity does not change significantly.

[0190] The above description is merely the preferred embodiments of the present application and the explanation of the technical principles applied. It should be understood by those skilled in the art that the inventive scope involved in the present application is not limited to the technical solutions formed by the specific combinations of the above technical features, and should also cover other technical solutions formed by any combinations of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features can be replaced with the technical features disclosed in the present application (but not limited to) having similar functions to form technical solutions.

Claims

1. A polymer electrolyte, characterized in that, include: Polymer base, lithium salt and additives; The additive includes polysorbate, which is obtained by mixing a polysorbate solution with a metal alkali, wherein the molar ratio of sorbic acid monomer in the polysorbate solution to metal ions in the metal alkali is (1:1.2) to (1:1.6), and the metal alkali includes at least one of lithium hydroxide, sodium hydroxide, and potassium hydroxide; The amount of polysorbate added is 5%-12.5% ​​of the mass of the polymer matrix; The molecular weight of the polysorbate is 1000-50000.

2. The polymer electrolyte according to claim 1, characterized in that, The polysorbate includes at least one of alkali metal polysorbates.

3. The polymer electrolyte according to claim 2, characterized in that, The alkali metal polysorbate includes at least one of lithium polysorbate, sodium polysorbate, and potassium polysorbate.

4. The polymer electrolyte according to claim 3, characterized in that, The alkali metal polysorbate includes lithium polysorbate.

5. The polymer electrolyte according to claim 1, characterized in that, The polymer substrate includes at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-trifluorochloroethylene copolymer, polyethylene oxide, thermoplastic polyurethane, polypropylene oxide, polycarbonate, polyvinyl alcohol, polyacrylic acid, polyethyl methacrylate, polymethyl methacrylate, polyacrylonitrile, and polyvinyl chloride.

6. The polymer electrolyte according to claim 1, characterized in that, The lithium salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium di(oxalate)borate, lithium di(fluorooxalate)borate, and lithium trifluoromethanesulfonate.

7. The polymer electrolyte according to claim 1, characterized in that, The amount of lithium salt added is 30%-60% of the mass of the polymer substrate.

8. The polymer electrolyte according to claim 7, characterized in that, The amount of lithium salt added is 50%-60% of the mass of the polymer substrate.

9. The polymer electrolyte according to claim 1, characterized in that, The process of mixing the polysorbate solution and the metal alkali to obtain the polysorbate includes: Sorbic acid and an initiator were mixed and heated to obtain a polysorbate solution. The metal alkali is added to the polysorbate solution, and the reaction continues until it swells. After drying, the polysorbate is obtained.

10. The polymer electrolyte according to claim 9, characterized in that, In the process of mixing sorbic acid and an initiator and heating to obtain a polysorbic acid solution, the reaction temperature is 60℃-70℃ and the reaction time is 2h-4h.

11. The polymer electrolyte according to claim 9, characterized in that, The initiator includes azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, diethylhexyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, dodecyl peroxide, tert-butyl peroxide, tert-butyl peroxybenzoate, diisopropyl peroxide, potassium persulfate, or ammonium persulfate.

12. A method for preparing the polymer electrolyte according to any one of claims 1-11, characterized in that, include: A polymer substrate, lithium salt, polysorbate, and organic solvent are mixed to obtain a mixed solution, and the mixed solution is solidified to obtain the polymer electrolyte.

13. The method according to claim 12, characterized in that, In the preparation of the polymer electrolyte, the organic solvent includes at least one selected from diethyl ether, ethanol, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran, malononitrile, succinic anionyl nitrile, glutaronitrile, adiponitrile, heptacyanide, octanoic anionyl nitrile, azelaic anionyl nitrile, and sebacate.

14. The method according to claim 12, characterized in that, In the preparation process of the polymer electrolyte, the curing method is solution casting.

15. The method according to claim 14, characterized in that, After curing, the product is dried.

16. A battery, characterized in that, Includes the polymer electrolyte according to any one of claims 1-11.

17. An electrical appliance, characterized in that, Includes the battery of claim 16, wherein the battery supplies power to the electrical device.

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