Semi-solid lithium manganate battery, preparation method thereof and power utilization device

Abstract

According to the preparation method of the semi-solid lithium manganate battery and the semi-solid lithium manganate battery, the oxidation resistance of a liquid electrolyte is improved by introducing fluorinated cyclic ester, a dilution initiator is injected twice after the battery is formed, and the dilution initiator and the fluorinated cyclic ester form a polymer with a fluorine-based cross-linked structure, so that the semi-solid lithium manganate battery is prepared. And the hydrophobicity and the high bond energy of the fluorocarbon bond can obviously reduce the flammability of the electrolyte. Besides, the solid electrolyte membrane mixed with more than two oxide solid electrolytes is adopted to partially replace a liquid electrolyte to be thermally compounded on the surface of the positive electrode, so that an oxidation window can be widened, the side reaction of the electrolyte can be inhibited, and the swelling and liquid leakage risks of the battery are reduced. The flexibility of the fluorine-based cross-linked polymer can relieve the volume stress in the charging and discharging process, and the rigid structure of the oxide solid electrolyte inhibits the puncture of lithium dendrites to form a rigid-flexible composite structure, so that the structural integrity is maintained in the acupuncture test, the heat spreading is inhibited, and the safety performance of the battery is improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery manufacturing technology, and in particular to a semi-solid lithium manganese oxide battery, its manufacturing method, and an electrical device thereof. Background Technology

[0002] Lithium-ion semi-solid-state batteries have achieved large-scale application in various fields such as new energy vehicles, low-altitude economy, and aviation due to their advantages of high safety, high energy density, and compatibility with existing production lines. Lithium manganese oxide cathode materials have been extensively studied in semi-solid-state battery systems due to their low cost, high voltage platform, and environmental friendliness. They exhibit relatively stable structure, good low-temperature performance, excellent rate performance, and relatively simple fabrication processes. However, the core issue lies in the fact that manganese-based cathodes easily release oxygen at high temperatures, exacerbating the risk of thermal runaway; and the electrolyte is prone to reacting with the oxygen released from the cathode under high temperature and high voltage conditions, generating large amounts of gas that lead to battery swelling and leakage.

[0003] Therefore, the industry urgently needs a technical solution to address the above problems. Summary of the Invention

[0004] To address the issues of oxidation gas generation and low flash point of liquid electrolyte in semi-solid lithium manganese oxide batteries, this invention introduces fluorinated cyclic esters to improve the oxidation resistance of the liquid electrolyte. Furthermore, a dilution initiator is injected twice after battery formation, forming a fluorinated cross-linked polymer with the fluorinated cyclic ester. The hydrophobicity and high bond energy of the carbon-fluorine bonds significantly reduce the flammability of the electrolyte. Additionally, this invention uses a solid electrolyte membrane containing two or more oxide solid electrolytes to partially replace the liquid electrolyte, thermally composited onto the positive electrode surface. This broadens the oxidation window and suppresses electrolyte side reactions, reducing the risk of battery swelling and leakage. The flexibility of the fluorinated cross-linked polymer alleviates volumetric stress during charging and discharging, while the rigid structure of the oxide solid electrolyte inhibits lithium dendrite penetration, forming a "rigid-flexible" composite structure. This maintains structural integrity during nail penetration testing, suppresses heat propagation, and improves battery safety performance. The technical solution of this invention is as follows:

[0005] The first aspect of this invention discloses a method for preparing a semi-solid lithium manganese oxide battery, the method comprising the following steps:

[0006] S1. Provide a liquid electrolyte, wherein the liquid electrolyte comprises a fluorinated cyclic ester;

[0007] S2, Provides a solid electrolyte membrane;

[0008] S3. The solid electrolyte membrane is laminated onto the surface of the positive electrode to form a composite positive electrode. The composite positive electrode, the separator, and the negative electrode are then stacked in sequence. The liquid electrolyte is injected and the electrode is initially encapsulated (with a liquid injection port reserved).

[0009] S4. Inject a diluent initiator into the battery and perform a secondary encapsulation; the diluent initiator is used to initiate an in-situ reaction of the fluorinated cyclic ester.

[0010] Furthermore, the fluorinated cyclic ester includes at least one of the fluorinated compounds shown in Formula 1.

[0011]

[0012] R1 and R2 are each independently selected from H, F, and C1 to C3 fluoroalkyl groups.

[0013] Furthermore, the fluorinated compound is selected from at least one of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), and tetrafluoroethylene carbonate.

[0014] Furthermore, the thickness of the solid electrolyte membrane is 5 μm to 20 μm.

[0015] Furthermore, the diluting initiator includes an initiator, which includes one or more of aluminum trifluoromethanesulfonate, potassium fluoride, and azobisisobutyronitrile.

[0016] Furthermore, the diluting initiator is prepared by dissolving the initiator in a carbonate solvent, and mixing the initiator and the carbonate solvent at a mass ratio of 1:(1-9).

[0017] Furthermore, the mass ratio of the diluting initiator to the liquid electrolyte is (1-9):1.

[0018] Furthermore, the solid electrolyte membrane comprises an oxide solid electrolyte, which includes one or more of lithium lanthanum zirconium oxide electrolyte (LLZO), lithium titanium aluminum phosphate electrolyte (LATP), lithium lanthanum titanium oxide electrolyte (LLTO), lithium lanthanum zirconium tantalum oxide electrolyte (LLZTO), and lithium silicon zirconium phosphate (LZSP).

[0019] The second aspect of the present invention discloses a semi-solid lithium manganese oxide battery, which is prepared using the method disclosed in the first aspect of the present invention.

[0020] A third aspect of the present invention discloses an electrical device comprising a semi-solid lithium manganese oxide battery as disclosed in the second aspect.

[0021] The advantages of this invention are as follows:

[0022] This invention raises the oxidation decomposition potential of a single-injection liquid electrolyte to above 4.8V by introducing a high-flash-point, oxidation-resistant fluorinated cyclic ester into the solvent. Al3+, acting as a Lewis acid, interacts with the carbonyl oxygen (C=O) in the FEC (fluorinated ester) via a secondary injection dilution initiator (such as aluminum trifluoromethanesulfonate dissociating into Al3+ and trifluoromethanesulfonate ions in carbonates), weakening the CO bond polarity and promoting ring-opening of the cyclic ester. The trifluoromethanesulfonate ion nucleophilically attacks the carbonyl carbon, generating an alkoxy anion intermediate. This alkoxy anion attacks the carbonyl carbon of adjacent fluorinated cyclic esters, forming linear polymer chains. Fluorine atoms, through hydrophobic and steric effects, promote the formation of a cross-linked network between chains. Al3+ bridges the oxygen atoms of multiple polymer chains, forming a three-dimensional fluorinated cross-linked structure, significantly reducing the thermal propagation rate and the amount of thermal runaway gas produced.

[0023] By composite oxide solid electrolyte membranes on the cathode surface, the three-dimensional fluorine-based cross-linked structure generated by in-situ polymerization forms chemical bonds with the oxide electrolyte membrane surface, filling the interfacial pores between solid electrolyte particles and providing a dual-layer protection effect of stress buffering and mechanical reinforcement. The high thermal stability oxide solid electrolyte, combined with fluorine-based polymers, forms a gradient heat-resistant layer, which together reduces the flammability of the electrolyte, suppresses thermal runaway temperature rise and thermal runaway gas production, and does not ignite or explode during nail penetration safety testing. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used in the detailed description is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having” and any variations thereof in the specification and claims of this invention are intended to cover non-exclusive inclusion.

[0026] In the description of specific embodiments of the present invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, "multiple" means two or more, unless otherwise explicitly defined.

[0027] In this invention, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0028] In the description of the embodiments of this invention, the term "and / or" is merely a description of the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this invention, the character " / " generally indicates that the preceding and following associated objects have an "or" relationship.

[0029] It should be noted that, for ease of description, all identical technical features are labeled with the same symbols in the following embodiments.

[0030] Lithium manganese oxide batteries have attracted attention in the lithium-ion battery industry due to their cost and safety advantages. However, in semi-solid lithium manganese oxide batteries, the manganese-based cathode is prone to releasing oxygen at high temperatures, which exacerbates the risk of thermal runaway. Furthermore, the electrolyte is prone to reacting with the oxygen released from the cathode at high temperatures and voltages, generating a large amount of gas that causes the battery to swell and leak. This greatly limits the large-scale commercial application of semi-solid lithium manganese oxide batteries.

[0031] To address the above problems, this invention proposes a technical solution.

[0032] The first aspect of this invention discloses a method for preparing a semi-solid lithium manganese oxide battery, the method comprising the following steps:

[0033] S1. Provide liquid electrolyte, which includes fluorinated cyclic esters;

[0034] S2, Provides a solid electrolyte membrane;

[0035] S3. Composite a solid electrolyte membrane onto the surface of the positive electrode to form a composite positive electrode. Then, stack the composite positive electrode, the separator, and the negative electrode in sequence, inject liquid electrolyte, and perform initial encapsulation (with a pre-reserved injection port).

[0036] S4. Inject the diluted initiator into the battery and perform secondary encapsulation; the diluted initiator is used to initiate the in-situ reaction of fluorinated cyclic esters.

[0037] This invention raises the oxidation decomposition potential of a single-injection liquid electrolyte to above 4.8V by introducing a high-flash-point, oxidation-resistant fluorinated cyclic ester into the solvent. Al3+, acting as a Lewis acid, interacts with the carbonyl oxygen (C=O) in the FEC (fluorinated ester) via a secondary injection dilution initiator (such as aluminum trifluoromethanesulfonate dissociating into Al3+ and trifluoromethanesulfonate ions in carbonates), weakening the CO bond polarity and promoting ring-opening of the cyclic ester. The trifluoromethanesulfonate ion nucleophilically attacks the carbonyl carbon, generating an alkoxy anion intermediate. This alkoxy anion attacks the carbonyl carbon of adjacent fluorinated cyclic esters, forming linear polymer chains. Fluorine atoms, through hydrophobic and steric effects, promote the formation of a cross-linked network between chains. Al3+ bridges the oxygen atoms of multiple polymer chains, forming a three-dimensional fluorinated cross-linked structure, significantly reducing the thermal propagation rate and the amount of thermal runaway gas produced.

[0038] By composite oxide solid electrolyte membranes on the cathode surface, the three-dimensional fluorine-based cross-linked structure generated by in-situ polymerization forms chemical bonds with the oxide electrolyte membrane surface, filling the interfacial pores between solid electrolyte particles and providing a dual-layer protection effect of stress buffering and mechanical reinforcement. The high thermal stability oxide solid electrolyte, combined with fluorine-based polymers, forms a gradient heat-resistant layer, which together reduces the flammability of the electrolyte, suppresses thermal runaway temperature rise and thermal runaway gas production, and does not ignite or explode during nail penetration safety testing.

[0039] In some embodiments, the liquid electrolyte includes a non-aqueous organic solvent and an electrolyte salt; the non-aqueous organic solvent includes organic solvents, film-forming additives, and fluorinated cyclic esters, and the electrolyte salt includes at least one of fluorinated inorganic lithium salts and fluorinated organic lithium salts.

[0040] In some embodiments, the fluorocyclic ester includes at least one of the fluoro compounds shown in Formula 1.

[0041]

[0042] R1 and R2 are each independently selected from H, F, and C1 to C3 fluoroalkyl groups.

[0043] In some embodiments, the fluorinated compound is selected from at least one of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), and tetrafluoroethylene carbonate.

[0044] In some embodiments, the fluorinated inorganic lithium salt includes at least one of lithium hexafluorophosphate, lithium difluorophosphate, and lithium fluoroborate; the fluorinated organic lithium salt includes at least one of lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethanesulfonyl)imide.

[0045] In some embodiments, the organic solvent includes at least one of ethylene carbonate EC, ethyl methyl carbonate EMC, diethyl carbonate DEC, dimethyl carbonate DMC, and propylene carbonate PC.

[0046] In some specific embodiments, the organic solvent used in this application is ethyl methyl carbonate (EMC), the film-forming additive is vinylene carbonate (VC), and the fluorocyclic ester is fluoroethylene carbonate (FEC). This is merely an example and is not intended to be limiting.

[0047] In practical applications, the preparation process of liquid electrolytes is as follows:

[0048] An organic solvent, ethyl methyl carbonate (EMC), a film-forming additive, vinylene carbonate (VC), and a fluorocyclic ester, fluoroethylene carbonate (FEC), are mixed in a volume ratio of (1:1:1) to (1:1:8) and stirred for 30 to 60 minutes to obtain a mixed non-aqueous organic solvent. The fluorocyclic ester itself has the effect of reducing surface tension and improving wettability; for example, the volume ratio of the organic solvent, film-forming additive, and fluorocyclic ester can be selected as 1:1:1, 1:1:2, 1:1:3, 1:1:4, 1:1:5, 1:1:6, 1:1:7, 1:1:8, etc.; the stirring time can be selected as 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, etc.

[0049] Next, fluorinated inorganic lithium salt LiPF6 and fluorinated organic lithium salt LiFSI with a molar ratio of (1-99):1 are added to the mixed non-aqueous organic solvent. After stirring for 60-120 minutes, the mixture is left to stand at a low temperature of 0-10°C for 4-8 hours to obtain a liquid electrolyte. For example, the stirring time in this step can be selected as 60 min, 80 min, 100 min, 120 min, etc., the low temperature can be selected as 0°C, 2°C, 5°C, 8°C, 10°C, etc., and the standing time can be selected as 4 h, 5 h, 6 h, 7 h, 8 h, etc.

[0050] For example, the molar ratio of fluorinated inorganic lithium salt and fluorinated organic lithium salt can be selected as 1:1, 2:1, 5:1, 8:1, 10:1, 11:1, 12:1, 15:1, 18:1, 20:1, 31:1, 32:1, 35:1, 38:1, 40:1, 50:1, 55:1, 58:1, 60:1, 80:1, 85:1, 90:1, 99:1, etc.

[0051] In specific applications, the mass ratio of the mixed non-aqueous organic solvent and lithium salt is (3:2) to (20:1). For example, the mass ratio can be selected as 3:2, 2:1, 5:2, 5:1, 8:1, 10:1, 12:1, 15:1, 18:1, 20:1, etc. The above examples are only examples and are not limitations. Those skilled in the art can freely implement these methods without exceeding their understanding.

[0052] In some embodiments, the electrolyte salt concentration of the liquid electrolyte is 5% to 40%.

[0053] In specific applications, the electrolyte salt concentration of the liquid electrolyte can be selected as 5%, 8%, 10%, 12%, 14%, 15%, 18%, 20%, 22%, 24%, 25%, 28%, 30%, 32%, 34%, 35%, 38%, 40%, etc.; the above are just examples and are not limitations. Those skilled in the art can implement them freely without exceeding the scope of their understanding.

[0054] In some embodiments, the solid electrolyte membrane comprises an oxide solid electrolyte, which includes one or more of lithium lanthanum zirconium oxide electrolyte (LLZO), lithium titanium aluminum phosphate electrolyte (LATP), lithium lanthanum titanium oxide electrolyte (LLTO), lithium lanthanum zirconium tantalum oxide electrolyte (LLZTO), and lithium silicon zirconium phosphate (LZSP).

[0055] In practical applications, the preparation process of solid electrolyte membranes is as follows:

[0056] Mix two or more oxide solid electrolytes and stir for 30 to 60 minutes. Compared with a single oxide solid electrolyte, mixing two oxide solid electrolytes can achieve complementary improvement in ionic conductivity, optimize the synergistic effect of electrolyte membrane anti-brittleness and interface stability, and balance performance and cost.

[0057] In specific applications, LATP and LLZO can be selected. LATP particles can effectively fill the voids at the grain boundaries of LLZO, providing an additional fast migration channel for lithium ions and reducing grain boundary resistance. At the same time, the rigid framework of LLZO provides a stable support framework for LATP, suppressing its side reactions with the electrode. The dense interface formed by the combination of the two optimizes the overall transport path of lithium ions, thereby achieving ionic conductivity that surpasses that of a single component.

[0058] For example, the stirring time can be selected as 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, etc. The above examples are only examples and are not limitations. Those skilled in the art can freely implement them without exceeding their understanding.

[0059] The mixed oxide solid electrolyte and binder are mixed evenly at a mass ratio of (1:1) to (4:3), and then the solvent is added. The mixture is stirred for 60 min to 120 min to obtain a uniform solid electrolyte slurry. The slurry is then coated onto a glass plate using a casting coating machine and dried to obtain a solid electrolyte film.

[0060] For example, the mass ratio of the oxide solid electrolyte to the binder can be selected as 1:1, 5:4, 4:3, etc., and the stirring time can be selected as 60 min, 80 min, 100 min, 120 min, etc. The above examples are only examples and are not limitations. Those skilled in the art can freely implement these methods without exceeding their understanding.

[0061] In some embodiments, the solvent added after the mixed oxide solid electrolyte and binder are uniformly mixed is selected from at least one of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), acetone, tetrahydrofuran (THF), isopropanol (IPA), ethanol, n-butanol, and deionized water.

[0062] In this invention, "at least one" means that one element can be selected from the listed elements as the technical solution, or two or more elements can be selected from the listed elements as the technical solution. Since the listed elements have similar physicochemical properties and do not react chemically with each other, their individual physicochemical properties will not be affected. Those skilled in the art can select suitable single or mixed elements based on factors such as cost and the ease of obtaining raw materials; this invention is not limited thereto.

[0063] In some embodiments, the composite method in step S3 includes, but is not limited to, heated rolling, hot pressing, or isostatic pressing. This structural design aims to construct a stable positive electrode / solid electrolyte interface through close contact between the solid electrolyte membrane and the positive electrode active material, thereby synergistically suppressing the dissolution and migration of manganese ions during cycling from both physical and chemical perspectives.

[0064] In some embodiments, the thickness of the solid electrolyte membrane is 5 μm to 20 μm.

[0065] In specific applications, the thickness of the solid electrolyte membrane can be selected from 5μm, 6μm, 8μm, 10μm, 12μm, 14μm, 15μm, 16μm, 18μm, 20μm, etc.; the above are just examples and are not limitations. Those skilled in the art can implement them freely without exceeding the scope of their understanding.

[0066] In some embodiments, the diluent initiator includes an initiator, which includes one or more of aluminum trifluoromethanesulfonate, potassium fluoride, and azobisisobutyronitrile.

[0067] In some embodiments, the diluent initiator is prepared by dissolving the initiator in a carbonate solvent and mixing the initiator and the carbonate solvent at a mass ratio of 1:(1 to 9).

[0068] In the specific application of this application, ethyl methyl carbonate (EMC) is selected as the carbonate solvent. This is merely an example and is not intended to limit the application. It was chosen because it is consistent with the organic solvent of the liquid electrolyte, thus avoiding the introduction of new components, and its low viscosity facilitates rapid diffusion after injection.

[0069] In specific applications, the mass ratio of initiator to carbonate solvent can be selected as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, etc. The above examples are merely illustrations and not limitations. Those skilled in the art can freely implement these methods without exceeding their understanding.

[0070] In some embodiments, the mass ratio of the diluent initiator to the liquid electrolyte is (1-9):1.

[0071] In specific applications, the mass ratio of the diluent initiator to the liquid electrolyte can be selected as 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, etc. The above examples are merely illustrations and not limitations. Those skilled in the art can freely implement these methods without exceeding their understanding.

[0072] In some embodiments, the positive electrode is prepared as follows:

[0073] The positive electrode active material, positive electrode binder, and positive electrode conductive agent are mixed, and then the positive electrode slurry solvent is added and stirred evenly to obtain the positive electrode slurry. Then, the positive electrode slurry is coated onto the positive electrode current collector, dried, and pressed into a sheet to obtain the positive electrode.

[0074] In some embodiments, the negative electrode is prepared as follows:

[0075] The negative electrode active material, negative electrode binder, and negative electrode conductive agent are mixed, and a negative electrode slurry solvent is added and stirred evenly to obtain a negative electrode slurry. Then, the negative electrode slurry is coated onto a negative electrode current collector, dried, and pressed into a sheet to obtain the negative electrode.

[0076] In some embodiments, the diaphragm includes at least one of the following: polyolefin diaphragm, coated polyester membrane, cellulose membrane, polyimide and polyamide membrane, spandex or aramid membrane, nonwoven diaphragm, and inorganic nanocomposite membrane.

[0077] In this invention, the separator provides insulation protection for the positive and negative electrodes, preventing short circuits caused by contact between the positive and negative electrodes. The material and shape of the separator used in the lithium-ion battery of this invention are not particularly limited and can be any technology disclosed in the prior art.

[0078] In some embodiments, the positive electrode active material of the present invention is selected from lithium manganese oxide.

[0079] In some embodiments, the positive current collector may be aluminum (Al) foil, but is not limited thereto.

[0080] In some embodiments, non-limiting examples of positive electrode binders include polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0081] Positive electrode binders can improve the bonding between positive electrode active material particles and also improve the bonding between the positive electrode active layer and the positive electrode current collector.

[0082] In some embodiments, the positive electrode conductive agent imparts conductivity to the electrode. The positive electrode conductive agent may include any conductive material, as long as it does not cause a chemical change. Non-limiting examples of conductive materials include carbon-based materials (e.g., natural graphite, synthetic graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powder, metal fiber, etc., including, for example, copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives), and mixtures thereof.

[0083] In some embodiments, the positive electrode slurry solvent may be selected from polar organic solvents suitable for dissolving positive electrode binders, such as N-methylpyrrolidone (NMP) and N,N-dimethylformamide (DMF).

[0084] In some embodiments, the specific type of negative electrode active material is not specifically limited and can be selected according to requirements. Specifically, the negative electrode active material is selected from natural graphite, artificial graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, and spinel-structured lithiated TiO2-Li4Ti5O. 12 One or more of Li-Al alloys. Non-limiting examples of carbon materials include crystalline carbon, amorphous carbon, and mixtures thereof. Crystalline carbon can be amorphous or flake-shaped, small flake-shaped, spherical, or fibrous natural or artificial graphite. Amorphous carbon can be soft carbon, hard carbon, mesophase pitch carbides, calcined coke, etc.

[0085] In some embodiments, elemental metals and metal compounds may also be selected as negative electrode active materials, such as compounds containing metals or metalloids such as Li, Ag, Al, Bi, Cu, Ga, Ge, In, Ni, Pb, Sb, Si, Sn, Sr, and Zn.

[0086] In some embodiments, the negative electrode binder enhances the bonding between negative electrode active material particles and the bonding between the negative electrode active material and the current collector.

[0087] In some embodiments, non-limiting examples of negative electrode binders include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0088] In some embodiments, when an aqueous solvent is used as the liquid medium for forming the negative electrode slurry, a thickener is preferably used for slurry preparation, and the thickener is typically used to adjust the viscosity of the slurry.

[0089] In some embodiments, the aforementioned thickener may be one or more of the following: carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein and their salts, etc.

[0090] In some embodiments, the mass percentage of the thickener in the negative electrode slurry can be 0.1%-5%, for example, 0.1%, 0.2%, 0.5%, 0.6%, 1%, 2%, 3%, 4%, 5%, etc., preferably 0.5%-3%, and more preferably 0.6%-2%.

[0091] In some embodiments, the negative electrode conductive agent may include any conductive material, as long as it does not cause a chemical change. Non-limiting examples of negative electrode conductive materials include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powder, metal fiber, etc., such as copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives), and mixtures thereof.

[0092] In some embodiments, the negative current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with conductive metal, and combinations thereof.

[0093] In some embodiments, when an aqueous binder is used for the negative electrode slurry, the solvent may be deionized water; when an oil-based binder (such as PVDF) is used, the solvent may be N-methylpyrrolidone (NMP) or the like.

[0094] The second aspect of this invention discloses a semi-solid lithium manganese oxide battery, which is prepared by the method for preparing a semi-solid lithium manganese oxide battery disclosed in the first aspect.

[0095] The third aspect of the present invention discloses an electrical device, including the semi-solid lithium manganese oxide battery disclosed in the second aspect.

[0096] The present invention and its technical effects will be clearly and completely described below with reference to embodiments and comparative examples, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0097] Example 1: A semi-solid lithium manganese oxide battery, comprising a positive electrode, a separator, a negative electrode, a liquid electrolyte, and a solid electrolyte membrane. The preparation method of the semi-solid lithium manganese oxide battery is as follows:

[0098] 1. Preparation of liquid electrolytes

[0099] The organic solvent ethylene methyl carbonate (EMC), the film-forming additive vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were mixed in a volume ratio of 1:1:3 and stirred for 30 minutes to obtain a mixed organic solvent.

[0100] Add fluorinated inorganic lithium salt LiPF6 and fluorinated organic lithium salt LiFSI in a molar ratio of 1:1 (the molar ratio of mixed organic solvent to mixed lithium salt is 17:3) to the obtained mixed organic solvent. After stirring for 60 minutes, let it stand at 0℃ for 4 hours to obtain an electrolyte with a lithium salt mass concentration of 15%.

[0101] 2. Preparation of oxide solid electrolyte membranes

[0102] Mix the oxide solid electrolytes LATP and LLZO at a mass ratio of 7:3 and stir for 30 minutes until homogeneous.

[0103] The mixed oxide solid electrolyte and the binder polyvinylidene fluoride (PVDF) were mixed evenly at a mass ratio of 4:3, and then N-methylpyrrolidone (NMP) solvent was added. The mixture was stirred for 60 minutes to obtain a uniform slurry, which was then coated onto a glass plate using a casting coating machine. After drying, a solid electrolyte membrane with a thickness of 10 μm was obtained.

[0104] 3. Preparation of the positive electrode

[0105] The positive electrode active material LMO, binder polyvinylidene fluoride (PVDF), and conductive carbon SP were mixed at a mass ratio of 97:2:1. NMP solvent was added, and the mixture was stirred for 60 minutes to obtain a positive electrode slurry. The positive electrode slurry was then coated onto a positive electrode current collector aluminum foil, dried, and pressed into a sheet to obtain the positive electrode.

[0106] 4. Preparation of negative electrode

[0107] The negative electrode active material graphite, binder sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), and conductive agent conductive carbon SP were mixed in a mass ratio of 94:1.5:1.5:3. Deionized water was added and the mixture was stirred for 60 minutes to obtain a negative electrode slurry. Then, the negative electrode slurry was coated onto the negative electrode current collector copper foil, dried, and pressed into a sheet to obtain the negative electrode.

[0108] 5. Preparation of semi-solid lithium manganese oxide batteries

[0109] The prepared oxide solid electrolyte membrane and the prepared positive electrode are pressed together by heating and rolling to form a composite positive electrode sheet (heating and rolling temperature is 120℃, linear pressure is 2500N / mm, and rolling speed is 3m / min). Then, an aramid separator and a negative electrode are stacked on the surface of the oxide solid electrolyte membrane. Liquid electrolyte is injected once, and the formation and encapsulation are performed. A dilution initiator is injected a second time (the mass ratio of dilution initiator to liquid electrolyte is 4:1). The mixture is polymerized at 60℃ for 24 hours and encapsulated a second time to obtain a semi-solid lithium manganese oxide battery.

[0110] The preparation process of the diluted initiator is as follows: the initiator powder aluminum trifluoromethanesulfonate is dissolved in ethyl methyl carbonate (EMC), mixed at a mass ratio of 1:5, and stirred for 30 minutes to obtain the diluted initiator.

[0111] Example 2: A semi-solid lithium manganese oxide battery, comprising a positive electrode, a separator, a negative electrode, a liquid electrolyte, and a solid electrolyte membrane.

[0112] This embodiment is exactly the same as Example 1 in terms of structure, preparation process and raw materials. The only difference is that in this embodiment, the mass ratio of diluent initiator to liquid electrolyte is 7:3.

[0113] Example 3: A semi-solid lithium manganese oxide battery, comprising a positive electrode, a separator, a negative electrode, a liquid electrolyte, and a solid electrolyte membrane.

[0114] This embodiment is exactly the same as Example 1 in terms of structure, preparation process and raw materials. The only difference is that in this embodiment, the mass ratio of the diluent initiator to the liquid electrolyte is 9:1.

[0115] Example 4: A semi-solid lithium manganese oxide battery, comprising a positive electrode, a separator, a negative electrode, a liquid electrolyte, and a solid electrolyte membrane.

[0116] This embodiment is exactly the same as Example 1 in terms of structure, preparation process and raw materials. The only difference is that in this embodiment, the mass ratio of the diluent initiator to the liquid electrolyte is 1:1.

[0117] Example 5: A semi-solid lithium manganese oxide battery, comprising a positive electrode, a separator, a negative electrode, a liquid electrolyte, and a solid electrolyte membrane.

[0118] This embodiment is basically the same as Example 1 in terms of structure, preparation process and raw materials. The only difference is that in this embodiment, difluoroethylene carbonate replaces fluoroethylene carbonate in the mixed organic solvent. The volume ratio of the organic solvent ethylene carbonate (EMC), the film-forming additive vinylene carbonate (VC) and difluoroethylene carbonate (FEC) is 1:1:3.

[0119] Example 6: A semi-solid lithium manganese oxide battery, comprising a positive electrode, a separator, a negative electrode, a liquid electrolyte, and a solid electrolyte membrane.

[0120] This embodiment is basically the same as Example 1 in terms of structure, preparation process and raw materials. The only difference is that in this embodiment, the initiator powder in the diluted initiator is azobisisobutyronitrile.

[0121] Comparative Example 1: A semi-solid lithium manganese oxide battery, comprising a positive electrode, a separator, a negative electrode, a liquid electrolyte, and a solid electrolyte membrane.

[0122] The structure, preparation process and raw materials of this comparative example are exactly the same as those of Example 1. The only difference is that the mass ratio of the diluent initiator to the liquid electrolyte is 2:3 in this comparative example.

[0123] Comparative Example 2: A semi-solid lithium manganese oxide battery, comprising a positive electrode, a separator, a negative electrode, a liquid electrolyte, and a solid electrolyte membrane.

[0124] The structure, preparation process and raw materials of this comparative example are basically the same as those of Example 1. In the process of preparing the semi-solid lithium manganese oxide battery, the diluent initiator is not injected in this comparative example.

[0125] Comparative Example 3: A semi-solid lithium manganese oxide battery, comprising a positive electrode, a separator, a negative electrode, a liquid electrolyte, and a solid electrolyte membrane.

[0126] The structure, preparation process and raw materials of this comparative example are basically the same as those of Example 1. In the process of preparing the semi-solid lithium manganese oxide battery, this comparative example simultaneously injects a diluent initiator and a liquid electrolyte.

[0127] Comparative experiment:

[0128] Eight groups of samples were taken from Examples 1-6 and Comparative Examples 1-2, with 30 samples in each group, and the following tests were performed. It should be noted that, because the dilution initiator and liquid electrolyte will polymerize, the mixed gel-like substance is difficult to inject into the encapsulated battery. Therefore, Comparative Example 3 is not included in the comparative test.

[0129] Electrolyte flash point test:

[0130] Samples were heated in an open environment, and vapor flashover was detected by flame sweeping to simulate the fire risk in an open environment.

[0131] A fully automatic open-cup flash point tester was used.

[0132] Heating rate: 10-20℃ / min, start purging 20℃ before the preset flash point;

[0133] The temperature at which a blue flame first appears is the flash point.

[0134] Battery nail penetration test:

[0135] At room temperature, it is charged to 4.2V at a constant current and constant voltage of 0.33C, and the cutoff current is 0.05C.

[0136] Using a Φ5mm high-temperature resistant steel needle (with a cone angle of 45° at the needle tip, and a smooth surface free of rust, oxide layer, and oil), insert the needle at a speed of 25±5mm / s from a direction perpendicular to the battery cell plate. The insertion point should be close to the geometric center of the pierced surface, and the steel needle should remain inside the battery cell.

[0137] Observe for 1 hour and record video to confirm whether the battery is smoking, catching fire or exploding.

[0138] Battery thermal runaway testing (ARC):

[0139] Record the battery's initial appearance, weight, voltage, and internal resistance;

[0140] Charge at a constant current and constant voltage of 0.33C to the upper limit voltage of 4.2V, cut off current of 0.05C, and let stand for 60 minutes;

[0141] The battery with the thermocouple fixed to it is suspended on the cover of the insulation cavity, and the insulation cavity is sealed with bolts.

[0142] Use an internal resistance meter to monitor battery voltage and internal resistance, and use a data acquisition instrument to monitor temperature at a frequency of 1Hz.

[0143] After initial calibration, the initial temperature is 40±2℃. The adiabatic calibration time is confirmed to be ≥20min. The temperature rise of each segment is 5℃. The equipment stops the "step temperature rise" and instead follows the temperature of the battery and keeps it consistent, so that the battery continues to generate heat in the adiabatic environment until thermal runaway occurs or the temperature reaches 300℃.

[0144] During the adiabatic tracking phase, the gas production rate (pressure relief valve opening pressure) is recorded in real time.

[0145] Test results are imported into Table 1:

[0146] Table 1

[0147]

[0148]

[0149] According to Table 1, compared with Comparative Example 2 which did not have a secondary injection of diluent initiator, the lightning temperatures of Examples 1-6 were all above 85°C, and all passed the needle penetration test, while the gas generation rate of thermal runaway was below 0.5.

[0150] Furthermore, according to Comparative Example 1 and all examples, when the mass ratio of the diluent initiator to the liquid electrolyte is controlled within (1 to 9):1, the prepared semi-solid lithium manganese oxide battery can have both cell strength and heat resistance.

[0151] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein.

Claims

1. A method for preparing a semi-solid lithium manganese oxide battery, characterized in that, The method includes the following steps: S1. Provide a liquid electrolyte, wherein the liquid electrolyte comprises a fluorinated cyclic ester; S2, Provides a solid electrolyte membrane; S3. The solid electrolyte membrane is laminated onto the surface of the positive electrode to form a composite positive electrode. The composite positive electrode, the separator, and the negative electrode are then stacked in sequence. The liquid electrolyte is injected and the electrode is initially encapsulated, with an injection port reserved. S4. Inject a diluent initiator into the battery and perform a secondary encapsulation; the diluent initiator is used to initiate an in-situ reaction of the fluorinated cyclic ester.

2. The method according to claim 1, characterized in that, The fluorinated cyclic esters include at least one of the fluorinated compounds represented by Formula I; R1 and R2 are each independently selected from H, F, and C1 to C3 fluoroalkyl groups.

3. The method according to claim 2, characterized in that, The fluorinated compound is selected from at least one of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), and tetrafluoroethylene carbonate.

4. The method according to claim 1, characterized in that, The thickness of the solid electrolyte membrane is 5 μm to 20 μm.

5. The method according to claim 1, characterized in that, The diluting initiator includes an initiator, which includes one or more of aluminum trifluoromethanesulfonate, potassium fluoride, and azobisisobutyronitrile.

6. The method according to claim 1, characterized in that, The diluting initiator is prepared by dissolving the initiator in a carbonate solvent and mixing the initiator and the carbonate solvent at a mass ratio of 1:(1-9).

7. The method according to claim 6, characterized in that, The mass ratio of the diluting initiator to the liquid electrolyte is (1-9):

1.

8. The method according to claim 1, characterized in that, The solid electrolyte membrane includes an oxide solid electrolyte, which includes one or more of the following: lithium lanthanum zirconium oxide electrolyte (LLZO), lithium titanium aluminum phosphate electrolyte (LATP), lithium lanthanum titanium oxide electrolyte (LLTO), lithium lanthanum zirconium tantalum oxide electrolyte (LLZTO), and lithium silicon zirconium phosphate (LZSP).

9. A semi-solid lithium manganese oxide battery, characterized in that, The semi-solid lithium manganese oxide battery is prepared by any one of claims 1 to 8.

10. An electrical device, characterized in that, Including the semi-solid lithium manganese oxide battery as described in claim 9.

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