A binder, a solid electrolyte membrane, a method for manufacturing the same, and a battery

Abstract

The present application provides a kind of binder, solid electrolyte membrane and its preparation method and battery, the binder includes multiple copolymer and auxiliary agent, multiple copolymer includes the copolymer of acrylate structural unit, hydroxyl ester structural unit and functional structural unit, the functional structural unit includes acrylic structural unit and / or amide structural unit;The auxiliary agent includes phosphate and / or silane coupling agent class.The binder of the present application has good bonding performance, etc., is suitable for preparing solid electrolyte membrane, can improve the forming capacity of solid electrolyte and other materials for forming solid electrolyte membrane, and the structural stability and ionic conductivity of solid electrolyte membrane, etc.Performance is improved, and the cost of solid electrolyte membrane is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid electrolyte membrane, and particularly relates to a binder, a solid electrolyte membrane, a preparation method of the solid electrolyte membrane and a battery. BACKGROUND

[0002] The solid electrolyte has advantages such as high electrical conductivity and can be applied to a solid electrolyte membrane of a battery. However, due to factors such as high rigidity of the solid electrolyte, in the preparation of the solid electrolyte membrane using the solid electrolyte, there are generally problems such as poor processability, poor structural stability of the solid electrolyte membrane and low ionic conductivity. For example, the oxide solid electrolyte (such as lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanate (LLTO) and lithium aluminum titanium phosphate (LATP) electrolyte) has advantages such as high electrical conductivity (the electrical conductivity is generally 10 -4 S / cm-10 -3 S / cm), good chemical / electrochemical stability, wide electrochemical window, low cost and strong compatibility with lithium metal negative electrode, and is widely applied. However, due to factors such as high rigidity and substantially no flexibility of the oxide solid electrolyte, in the preparation of the solid electrolyte membrane using the oxide solid electrolyte, there are problems such as poor processability, poor structural stability of the solid electrolyte membrane and low ionic conductivity.

[0003] Specifically, due to factors such as high rigidity and substantially no flexibility of the solid electrolyte, in the preparation of the solid electrolyte membrane using the solid electrolyte and the like, it is generally necessary to use high stamping pressure (generally greater than 10 MPa) to stamp form the solid electrolyte and the like to form the solid electrolyte membrane. For example, the preparation process of the common solid electrolyte and the solid electrolyte membrane (such as the oxide solid electrolyte and the solid electrolyte membrane formed by using the oxide solid electrolyte) mainly includes the following steps: precursor mixing, precursor grinding, precursor pre-sintering, secondary grinding of the pre-sintered precursor, isostatic pressing and stamping forming, high-temperature sintering and the like, to obtain the solid electrolyte membrane.

[0004] In the preparation process of the above-mentioned solid electrolyte membrane, the internal stress formed in the electrolyte powder during stamping forming is difficult to effectively bind the solid electrolyte particles, which leads to the problem that the solid electrolyte particles are prone to breakage during stamping forming, especially when preparing a relatively thin solid electrolyte membrane, which is more prone to breakage during stamping forming, thereby affecting the structural stability and ionic conductivity of the formed solid electrolyte membrane. For example, for high-energy-density batteries, there is an increasingly high requirement for the thickness of the solid electrolyte. For example, for a 500 Wh / kg battery using a lithium metal negative electrode, the thickness of the solid electrolyte is generally required to be within 10 μm, which poses a greater challenge to the preparation of the solid electrolyte membrane.

[0005] Furthermore, the stamping equipment used in the preparation of solid electrolyte membranes needs to withstand high stamping pressure (typically >10MPa). Especially when preparing solid electrolyte membranes for use in large-capacity batteries, as the battery capacity increases (for example, when the battery capacity increases from 1Ah to 10Ah or even 100Ah), the area of ​​the solid electrolyte membrane required also increases, requiring a larger solid electrolyte forming area. The increase in the solid electrolyte forming area will place higher demands on the stamping pressure of the stamping equipment, which will increase the manufacturing cost of solid electrolyte membranes, as well as individual cells and batteries.

[0006] Therefore, improving the molding capability of solid electrolyte membranes, reducing their manufacturing cost, and simultaneously improving their structural stability and ionic conductivity remain pressing technical challenges in this field. While mixing solid electrolytes and other materials with binders can bond these materials together, limitations in the poor adhesion of existing binders cannot effectively improve the molding capability of the solid electrolytes used to form the membrane, nor the structural stability and ionic conductivity of the solid electrolyte membrane itself. Summary of the Invention

[0007] This invention provides an adhesive, a solid electrolyte membrane, a method for preparing the same, and a battery. The adhesive has good adhesion and other properties, is suitable for preparing solid electrolyte membranes, can improve the molding ability of solid electrolytes and other materials used to form solid electrolyte membranes, and can improve the structural stability and ionic conductivity of solid electrolyte membranes while reducing the cost of solid electrolyte membranes, effectively overcoming the defects of existing technologies.

[0008] The present invention provides an adhesive comprising a multi-component copolymer and an additive, wherein the multi-component copolymer comprises a copolymer of acrylate structural units, hydroxy ester structural units and functional structural units, wherein the functional structural units comprise acrylate structural units and / or amide structural units; and the additive comprises phosphate esters and / or silane coupling agents.

[0009] According to one embodiment of the present invention, the mass ratio of the multi-component copolymer to the additive is 100:(5-0.05).

[0010] According to one embodiment of the present invention, the phosphate esters include monophosphate esters and / or diphosphate esters; and / or, the silane coupling agents include one or more of α-methacryloyloxy-methyl-triethoxysilane, γ-methacryloyloxy-propyl-triethoxysilane, vinyltriethoxysilane, and cyclohexylmethyldimethoxysilane.

[0011] According to one embodiment of the present invention, the acrylate structural unit includes a methacrylate structural unit and / or an acrylate structural unit.

[0012] According to one embodiment of the present invention, the hydroxy ester structural unit includes one or more of the following: methyl hydroxymethyl acrylate structural unit, hydroxyethyl acrylate structural unit, hydroxypropyl acrylate structural unit, hydroxybutyl acrylate structural unit, 5-hydroxypentyl acrylate structural unit, and 6-hydroxyhexyl acrylate structural unit.

[0013] According to one embodiment of the present invention, the acrylic structural unit includes one or more of the following: acrylic acid structural unit, methacrylic acid structural unit, maleic acid structural unit, itaconic acid structural unit, cinnamic acid structural unit, itaconic acid ester structural unit, itaconic acid monomethyl ester structural unit, itaconic acid monoethyl ester structural unit, itaconic acid monopropyl ester structural unit, and itaconic acid monobutyl ester structural unit.

[0014] According to one embodiment of the present invention, the amide structural unit includes one or more of acrylamide structural units, dimethylacrylamide structural units, methacrylamide structural units, and caprolactam structural units.

[0015] According to one embodiment of the present invention, the mass ratio of the acrylate structural unit, the hydroxy ester structural unit and the functional structural unit is (4.3-7):(0.5-2):(0.2-1).

[0016] According to one embodiment of the present invention, the weight-average molecular weight of the multi-component copolymer is 10,000 Da to 600,000 Da; and / or, the molecular weight distribution index (PDI) of the multi-component copolymer is 1.5 to 5; and / or, the 100% thermal weight loss temperature of the multi-component copolymer is 200°C to 400°C.

[0017] According to one embodiment of the present invention, the pH of the adhesive is 6-8.

[0018] According to one embodiment of the present invention, the adhesive further includes a solvent, which includes one or more of alcohol solvents, sulfone solvents, and amide solvents.

[0019] In another aspect, the present invention provides a solid electrolyte membrane comprising a solid electrolyte and the binder described above.

[0020] According to one embodiment of the present invention, the solid electrolyte comprises an oxide solid electrolyte; and / or, the average particle size of the solid electrolyte is 0.4 μm-1.0 μm.

[0021] According to one embodiment of the present invention, based on the total mass of the solid electrolyte and the binder, the mass percentage of the solid electrolyte is 95%-99.5%, and the mass percentage of the binder is 0.5%-5%.

[0022] In another aspect, the present invention provides a battery comprising the above-described solid electrolyte membrane.

[0023] According to one embodiment of the present invention, the battery further includes a positive electrode and a negative electrode, and the solid electrolyte membrane is located between the positive electrode and the negative electrode; the negative electrode includes a lithium metal negative electrode.

[0024] The implementation of this invention has at least the following beneficial effects:

[0025] (1) The adhesive provided by the present invention has good adhesion and other properties, which can improve the molding ability of solid electrolytes and other materials. It is suitable for preparing solid electrolyte membranes by coating and film formation without the need for stamping. On the one hand, it can avoid the problems of solid electrolytes and other materials breaking due to high-pressure stamping process and poor structural stability of the solid electrolyte membrane formed. In particular, it can solve the problems of solid electrolytes and other materials breaking due to high stamping pressure and poor structural stability of the solid electrolyte membrane formed when preparing thinner solid electrolyte membranes. Therefore, it is suitable for preparing thinner solid electrolyte membranes. For example, it can be used for the large-scale manufacturing of ultra-thin solid electrolyte membranes with a thickness of no more than 16 μm or even no more than 10 μm. On the other hand, it can save the use of ultra-high pressure isostatic pressing equipment. At the same time, the solid electrolyte membrane preparation process can be better compatible with the commonly used battery (such as lithium battery) manufacturing process, reducing the preparation cost of solid electrolyte membranes and batteries. Therefore, the binder of the present invention is more conducive to the preparation of solid electrolyte membranes, especially to the reduction of the thickness of solid electrolyte membranes, and can be used to prepare thin solid electrolyte membranes, providing a more economical technical path for improving the energy density and cycle stability of solid batteries.

[0026] (2) The binder provided by the present invention has a low thermal decomposition temperature. When it is applied to prepare solid electrolyte membrane by coating, after the solid electrolyte and other materials are shaped by the binder, it is beneficial to remove the binder in the shaped membrane by sintering. This avoids the problem of residual inactive impurities in the solid electrolyte membrane and thus avoids the problem of residual inactive impurities blocking the ion transport channels of the solid electrolyte membrane, thereby improving the electrochemical performance such as ionic conductivity of the solid electrolyte membrane. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. The specific embodiments listed below are merely descriptions of the principles and features of this invention, and the examples given are only for explaining this invention and are not intended to limit the scope of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0028] This invention provides an adhesive comprising a multi-component copolymer and an additive. The multi-component copolymer comprises a copolymer of acrylate structural units, hydroxy ester structural units, and functional structural units, wherein the functional structural units include acrylic structural units and / or amide structural units; and the additives include phosphate esters and / or silane coupling agents.

[0029] According to the inventors' research, in the composition system of the above-mentioned adhesive, the synergistic effect of the multi-component copolymer and the additives can improve the adhesive properties, specifically, the strength and peel strength of the adhesive film formed by the adhesive are improved. This adhesive is suitable for preparing solid electrolyte membranes, which can enhance the bonding force between solid electrolytes and other materials, improve the molding ability of solid electrolytes and other materials used to form solid electrolyte membranes, and is especially suitable for preparing solid electrolyte membranes by coating film formation. It avoids the problems of high-pressure stamping molding process and the resulting breakage of solid electrolytes and other materials, poor structural stability and low ionic conductivity of the solid electrolyte membrane, thereby improving the structural stability and ionic conductivity of the solid electrolyte membrane. At the same time, it is beneficial to reduce the thickness of the solid electrolyte membrane, and is suitable for preparing thinner solid electrolyte membranes, such as ultrathin solid electrolyte membranes with a thickness of no more than 16 μm or even no more than 10 μm, and can reduce the preparation cost of solid electrolyte membranes. In addition, the above-mentioned binder has a low thermal decomposition temperature. After the solid electrolyte and other materials are formed by the binder, the binder in the formed film can be easily removed by sintering, avoiding the introduction of impurities into the formed solid electrolyte film, thereby improving the electrochemical performance of the solid electrolyte film such as ionic conductivity.

[0030] In some embodiments, the mass ratio of the aforementioned multi-component copolymer to the aforementioned additive (i.e., the ratio of the total mass of acrylate structural units, hydroxy ester structural units, and functional structural units in the multi-component copolymer to the mass of the additive) can be 100:(5-0.05), for example, a range consisting of 100:0.05, 100:1, 100:2, 100:3, 100:4, 100:5, or any two of these. By controlling the mass ratio of the multi-component copolymer to the additive within the aforementioned range, the additive can be fully and uniformly dispersed in the multi-component copolymer, thereby further improving the adhesive performance of the binder. When the mass ratio is too high, it will increase the complete thermal decomposition temperature of the binder, which will not only affect the solid electrolyte membrane during the sintering process but also increase energy consumption. When the mass ratio is too low, the adhesive performance of the binder cannot be sufficiently improved.

[0031] In some embodiments, the phosphate ester additives mentioned above include monophosphates and / or diphosphates. These adhesives enhance the bonding performance of the adhesives while being made from low-cost and readily available raw materials, which is beneficial for large-scale production applications.

[0032] In some embodiments, the above-mentioned silane coupling agent additives include one or more of α-methacryloyloxy-methyl-triethoxysilane, γ-methacryloyloxy-propyl-triethoxysilane, vinyltriethoxysilane, and cyclohexylmethyldimethoxysilane, which are beneficial for further improving the adhesion and other properties of the adhesive.

[0033] In this embodiment of the invention, the multi-component copolymer includes a copolymer of acrylate structural units, hydroxy ester structural units, and functional structural units; the acrylate structural units are formed by polymerization of acrylate monomers, the hydroxy ester structural units are formed by polymerization of hydroxy ester monomers, and the functional structural units are formed by polymerization of functional monomers. That is, the copolymer contains acrylate structural units formed by polymerization of acrylate monomers, hydroxy ester structural units formed by polymerization of hydroxy ester monomers, and functional structural units formed by polymerization of functional monomers (i.e., acrylic structural units formed by polymerization of acrylic monomers and / or amide structural units formed by polymerization of amide monomers).

[0034] In some embodiments, the acrylate structural units described above include methacrylate structural units and / or acrylate structural units. These acrylate structural units are formed by polymerization of acrylate monomers; the acrylate monomers include methacrylates and / or acrylates, that is, the acrylate structural units in the multi-component copolymer include methacrylate structural units formed by polymerization of methacrylates and / or acrylate structural units formed by polymerization of acrylates. These acrylate structural units are beneficial for improving the flexibility of the electrolyte membrane in the solid state, while simultaneously reducing the complete thermal decomposition temperature of the multi-component copolymer.

[0035] In some embodiments, the hydroxy ester structural units include one or more of the following: methyl hydroxymethacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, 5-hydroxypentyl acrylate, and 6-hydroxyhexyl acrylate. The hydroxy ester structural units are formed by polymerization of hydroxy ester monomers; the hydroxy ester monomers (including hydroxyl monomers) include one or more of the following: methyl hydroxymethacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, 5-hydroxypentyl acrylate, and 6-hydroxyhexyl acrylate. That is, the hydroxy ester structural units in the multi-component copolymer include one or more of the following: methyl hydroxymethyl acrylate structural units formed by polymerization of methyl hydroxymethyl acrylate, hydroxyethyl acrylate structural units formed by polymerization of hydroxyethyl acrylate, hydroxypropyl acrylate structural units formed by polymerization of hydroxypropyl acrylate, hydroxybutyl acrylate structural units formed by polymerization of hydroxybutyl acrylate, 5-hydroxypentyl acrylate structural units formed by polymerization of 5-hydroxypentyl acrylate, and 6-hydroxyhexyl acrylate structural units formed by polymerization of 6-hydroxyhexyl acrylate. The above-mentioned hydroxy ester structural units help to further improve the adhesion of the adhesive.

[0036] In some embodiments, the functional structural units include acrylic structural units and / or amide structural units.

[0037] In some embodiments, the acrylic structural unit comprises one or more of the following: acrylic acid structural unit, methacrylic acid structural unit, maleic acid structural unit, itaconic acid structural unit, cinnamic acid structural unit, itaconic acid ester structural unit, itaconic acid monomethyl ester structural unit, itaconic acid monoethyl ester structural unit, itaconic acid monopropyl ester structural unit, and itaconic acid monobutyl ester structural unit. The acrylic structural unit is formed by polymerization of acrylic acid monomers; the acrylic acid monomers include one or more of the following: acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, itaconic acid ester, itaconic acid monomethyl ester, itaconic acid monoethyl ester, itaconic acid monopropyl ester, and itaconic acid monobutyl ester. That is, the acrylic structural units in the multi-component copolymer include one or more of the following: acrylic structural units formed by the polymerization of acrylic acid, methacrylic acid structural units formed by the polymerization of methacrylic acid, maleic acid structural units formed by the polymerization of maleic acid, itaconic acid structural units formed by the polymerization of itaconic acid, cinnamic acid structural units formed by the polymerization of cinnamic acid, itaconic acid ester structural units formed by the polymerization of itaconic acid ester, itaconic acid monomethyl ester structural units formed by the polymerization of itaconic acid monoethyl ester, itaconic acid monopropyl ester structural units formed by the polymerization of itaconic acid monopropyl ester, and itaconic acid monobutyl ester structural units formed by the polymerization of itaconic acid monobutyl ester. The above-mentioned functional structural units help to improve the dispersion performance of the binder on the slurry, thereby preventing agglomeration and making the slurry have excellent uniformity and stability during the coating process.

[0038] In some embodiments, the amide structural units include one or more of acrylamide, dimethacrylamide, methacrylamide, and caprolactam structural units. These amide structural units are formed by the polymerization of amide monomers; the amide monomers include one or more of acrylamide, dimethacrylamide, methacrylamide, and caprolactam. That is, the amide structural units in the multi-component copolymer include one or more of acrylamide structural units formed by the polymerization of acrylamide, dimethacrylamide structural units formed by the polymerization of dimethacrylamide, methacrylamide structural units formed by the polymerization of methacrylamide, and caprolactam structural units formed by the polymerization of caprolactam. These functional structural units help improve the dispersion performance of the binder on the slurry, thereby preventing agglomeration and resulting in excellent uniformity and stability of the slurry during coating.

[0039] In some embodiments, the adhesive further includes a solvent, which includes an organic solvent (oil-based solvent). The organic solvent may include one or more of alcohol solvents, sulfone solvents, and amide solvents. The alcohol solvent may include ethanol, the sulfone solvent may include dimethyl sulfoxide (DMSO), and the amide solvent may include one or more of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), and 1,3-dimethyl-2-imidazolinone (DMI).

[0040] In some embodiments, the solvent in the adhesive may include one or more of ethanol, dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, and 1,3-dimethyl-2-imidazolinone.

[0041] In some embodiments, the pH of the adhesive can be 6-8, for example, a range of 6, 6.5, 7, 7.5, 8 or any two of them. Controlling the pH of the adhesive within the above range is beneficial for maintaining the viscosity of the adhesive and can avoid the problem of poor flowability caused by excessive entanglement and twisting of the adhesive molecular chains under excessively acidic or alkaline conditions.

[0042] Specifically, the adhesive can be prepared by a process including the following steps: polymerizing monomer raw materials including acrylate monomers, hydroxy ester monomers and functional monomers; after the polymerization reaction is completed, adjusting the pH of the resulting reaction solution to 6-8 using a neutralizing agent to obtain an adhesive containing the above-mentioned multi-component copolymer.

[0043] Specifically, the polymerization reaction described above can be carried out in a solvent. The solvent in the binder comes from the solvent used in the preparation process of the binder. As mentioned above, the solvent used may include organic solvents (oil-based solvents), that is, the monomer raw materials described above can be copolymerized in an oil-based solution. Among them, the organic solvent may include one or more of alcohol solvents, sulfone solvents, and amide solvents. Alcohol solvents may include ethanol, sulfone solvents may include dimethyl sulfoxide (DMSO), and amide solvents may include one or more of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), and 1,3-dimethyl-2-imidazolinone (DMI).

[0044] In practice, monomer raw materials, including acrylate monomers, hydroxy ester monomers, and functional monomers, can be mixed in a solvent to obtain a mixture. An initiator is added to the mixture, and under the action of the initiator, these monomers undergo a polymerization reaction, specifically a free radical polymerization reaction. After the polymerization reaction is completed, a neutralizing agent is used to adjust the pH of the resulting reaction solution to 6-8 to obtain a polymer solution containing multi-component copolymers. The multi-component copolymers are then mixed with additives to obtain a binder.

[0045] Generally, the binder may include the aforementioned solvent. That is, after mixing the multi-component copolymer with the additives, there is no need to separate the solvent. The resulting binder is a liquid binder containing the aforementioned solvent. Subsequently, this binder can be directly mixed with components such as solid electrolytes to prepare a solid electrolyte membrane. In some embodiments, the viscosity of the polymer solution containing the multi-component copolymer at room temperature (25℃±5℃) is within the range of 500 mPa·s, 732 mPa·s, 1000 mPa·s, 1543 mPa·s, 2000 mPa·s, 3000 mPa·s, 4000 mPa·s, 5000 mPa·s, or any combination thereof.

[0046] In some embodiments, the monomer concentration is 20%-45% (i.e., the mass of the monomer raw material can be 20%-45% of the total mass of the mixture), for example, a range of 20%, 27%, 30%, 40%, 45% or any two of these.

[0047] In some embodiments, the neutralizing agent comprises an organic amine and / or an inorganic base, wherein the organic amine comprises one or more of ethylamine, diethylamine, triethylamine, propylamine, ethanolamine, n-propanolamine, and n-butanolamine, and the inorganic base comprises one or more of lithium hydroxide, sodium hydroxide, and potassium hydroxide.

[0048] In some embodiments, the initiator includes one or more of benzoyl peroxide, azobisisobutyronitrile, azobisisoheptanenitrile, azobisisobutylamidine hydrochloride, azobisisobutyramidoline hydrochloride, azobisisopropylimidazoline, and azobiscyanopentanoic acid. Such initiators facilitate free radical polymerization between the monomers and promote the formation of the multi-component copolymer.

[0049] In some embodiments, the reaction temperature of the polymerization reaction can be 50℃-70℃, for example, a range of 50℃, 60℃, 65℃, 70℃, or any two of these; the reaction time of the polymerization reaction can be 3h-7h, for example, a range of 3h, 4.5h, 5h, 6.5h, 7h, or any two of these. Controlling the reaction temperature and time of the polymerization reaction within the above ranges can, on the one hand, ensure an appropriate reaction rate and conversion efficiency, and avoid the risk of side reactions caused by high temperatures; on the other hand, it can also effectively control energy consumption and take into account the economic efficiency of the production process.

[0050] Specifically, the mass (amount added) of the aforementioned initiator can be 0.5%-2.5% of the total mass of the monomer raw materials, for example, 0.5%, 0.8%, 1%, 1.3%, 2%, 2.5% or any combination thereof.

[0051] Specifically, the aforementioned acrylate monomers include methacrylates and / or acrylates.

[0052] Specifically, the carbon chain length of the acrylate monomer (i.e., the total number of carbon atoms in the acrylate) can be 5-15, for example, a range of 5, 8, 10, 12, 15 or any two of these.

[0053] In some embodiments, the methacrylates mentioned above include one or more of ethyl methacrylate, methyl methacrylate, and n-butyl methacrylate. That is, in the multi-component copolymer, the methacrylate structural unit may include one or more of the following: ethyl methacrylate structural unit formed by polymerization of ethyl methacrylate, methyl methacrylate structural unit formed by polymerization of methyl methacrylate, and n-butyl methacrylate structural unit formed by polymerization of n-butyl methacrylate.

[0054] In some embodiments, the acrylates mentioned above include one or more of isooctyl acrylate, n-octyl acrylate, and n-butyl acrylate. That is, in the multi-component copolymer, the acrylate structural unit may include one or more of isooctyl acrylate structural units formed by polymerization of isooctyl acrylate, n-octyl acrylate structural units formed by polymerization of n-octyl acrylate, and n-butyl acrylate structural units formed by polymerization of n-butyl acrylate.

[0055] Specifically, the aforementioned hydroxy ester monomers (including hydroxy monomers) include one or more of methyl hydroxymethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, 5-hydroxypentyl acrylate, and 6-hydroxyhexyl acrylate.

[0056] Specifically, the aforementioned acrylic monomers include one or more of the following: acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, itaconic acid ester, monomethyl itaconic acid, monoethyl itaconic acid, monopropyl itaconic acid, and monobutyl itaconic acid.

[0057] Specifically, the aforementioned amide monomers include one or more of acrylamide, dimethacrylamide, methacrylamide, and caprolactam.

[0058] In some embodiments, the mass ratio of the acrylate structural unit, the hydroxy ester structural unit, and the functional structural unit is (4.3-7):(0.5-2):(0.2-1), that is, the mass ratio of the acrylate monomer, the hydroxy ester monomer, and the functional monomer can be (4.3-7):(0.5-2):(0.2-1), for example, 4.3:0.5:0.2, 4.3:2:0.2, 4.5:0.7:0.2, 5:1:0.6, 5:0.5:0.2, 7:2:0.5, 7:2:1, 7:0.5:1, or any combination thereof.

[0059] In some embodiments, the weight-average molecular weight of the aforementioned multi-component copolymer is between 10,000 Da and 600,000 Da, for example, a range consisting of 10,000 Da, 50,000 Da, 100,000 Da, 150,000 Da, 200,000 Da, 300,000 Da, 400,000 Da, 500,000 Da, 600,000 Da, or any two of these. A weight-average molecular weight of not less than 10,000 Da allows for better intermolecular interactions between the copolymer's molecular chains, thus promoting the adhesive's bonding properties; a weight-average molecular weight of not more than 600,000 Da helps avoid excessively high polymer solution viscosity due to excessively high molecular weight.

[0060] In some embodiments, the molecular weight distribution index (PDI) of the aforementioned multi-component copolymer (i.e., polydispersity index, defined as the ratio of weight-average molecular weight to number-average molecular weight: PDI = Mw / Mn) can be 1.5-5, for example, a range of 1.5, 2, 2.38, 3, 4, 4.83, 5, or any combination thereof. Controlling the molecular weight distribution index (PDI) of the multi-component copolymer within the above range is beneficial for further improving the adhesive properties such as adhesion.

[0061] In this embodiment of the invention, the multi-component copolymer has a low decomposition temperature, specifically its complete thermal decomposition temperature (i.e., 100% thermogravimetric temperature) can be less than or equal to 400°C. This results in a low decomposition temperature for the binder, which facilitates the removal of the binder from the formed membrane after bonding solid electrolytes and other materials with the binder. This avoids introducing impurities into the solid electrolyte membrane, thereby improving the ionic conductivity and other properties of the solid electrolyte membrane. At the same time, the low thermal decomposition temperature of the binder facilitates the removal of the binder from the formed membrane at a lower sintering temperature to obtain a solid electrolyte membrane. This not only reduces the impact of the sintering process on the solid electrolyte membrane but also saves energy and is more conducive to industrial applications.

[0062] In some embodiments, the 100% thermal weight loss temperature of the above-mentioned multi-component copolymer can be 200-400°C, for example, a range consisting of 200°C, 250°C, 294°C, 300°C, 350°C, 373°C, 400°C, or any two of these.

[0063] Specifically, after the binder is mixed with the solid electrolyte and coated into a film, when the binder in the resulting molded film (solid electrolyte membrane precursor) is removed by sintering, the sintering temperature can generally be less than or equal to 1000℃, specifically 800℃-1000℃. That is, the binder in the molded film can be basically completely removed by a high-temperature sintering process of no more than 1000℃, for example, 800℃-1000℃, thus avoiding the introduction of inactive impurities into the solid electrolyte membrane and the resulting impact on the ionic conductivity and other properties of the solid electrolyte membrane.

[0064] The present invention also provides a method for preparing the above-mentioned adhesive, comprising the following steps: mixing (blending) the above-mentioned multi-component copolymer with the above-mentioned additives to obtain the above-mentioned adhesive.

[0065] In addition, the preparation method of the above-mentioned adhesive may also include the preparation process of a multi-component copolymer. As mentioned above, the multi-component copolymer is copolymerized from monomer raw materials including acrylate monomers, hydroxy ester monomers and functional monomers. The specific preparation process is described above and will not be repeated here.

[0066] Specifically, the method for preparing a solid electrolyte membrane includes the following steps: coating an electrolyte slurry containing a solid electrolyte and a binder material into a film to obtain a solid electrolyte membrane precursor; wherein the binder material includes the binder or a binder prepared according to the binder preparation method; and sintering the solid electrolyte membrane precursor to remove the binder material to obtain the solid electrolyte membrane.

[0067] In the above preparation process, the binder is used to prepare the solid electrolyte membrane by coating, eliminating the need for stamping. This avoids problems such as breakage of solid electrolyte materials and poor structural stability of the resulting solid electrolyte membrane caused by high-pressure stamping. In particular, it solves the problems of breakage of solid electrolyte materials and poor structural stability of the resulting solid electrolyte membrane caused by high stamping pressure when preparing thinner solid electrolyte membranes. Therefore, it is suitable for preparing thinner solid electrolyte membranes, such as for the large-scale manufacturing of ultra-thin solid electrolyte membranes with a thickness of no more than 16 μm or even no more than 10 μm. On the other hand, it eliminates the need for ultra-high pressure isostatic pressing equipment, and the preparation process of the solid electrolyte membrane is more compatible with commonly used battery (such as lithium battery) manufacturing processes, reducing the preparation cost of solid electrolyte membranes and batteries. Therefore, the above preparation method is more conducive to the preparation of solid electrolyte membranes and improves the structural stability and ionic conductivity of the prepared solid electrolyte membranes. In particular, it can prepare thin solid electrolyte membranes, such as ultrathin solid electrolyte membranes with a thickness of no more than 10 μm, providing a more economical technical path for improving the energy density and cycle stability of solid-state batteries.

[0068] Specifically, the aforementioned solid electrolyte includes one or more of lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, lithium aluminum titanium phosphate, and lithium aluminum germanium phosphate.

[0069] In some embodiments, the process of coating an electrolyte slurry containing a solid electrolyte and a binder into a film includes: coating the electrolyte slurry into a wet film; drying the wet film to obtain a dry film; and rolling the dry film to obtain a solid electrolyte membrane precursor (a self-supporting electrolyte membrane).

[0070] Specifically, the electrolyte slurry can be coated onto a substrate, dried, and then rolled into shape. The resulting solid electrolyte membrane precursor is then peeled off from the substrate, cut into a preset shape, and then the binder is removed by sintering to obtain the solid electrolyte membrane.

[0071] As mentioned above, in the prior art, after the solid electrolyte precursor is ground twice, it needs to be formed by isostatic pressing and then sintered at high temperature to obtain a solid electrolyte membrane. Due to factors such as the weak interaction force between precursor particles, it is difficult to prepare a solid electrolyte membrane by isostatic pressing, especially to prepare an ultrathin solid electrolyte membrane. However, the embodiments of the present invention introduce a binder into the precursor particles to enhance the adhesion between the precursor particles. The self-supporting solid electrolyte membrane precursor can be obtained by coating, baking, rolling and substrate peeling. In particular, it is possible to obtain a self-supporting ultrathin solid electrolyte membrane precursor with a thickness of no more than 16 μm or even no more than 10 μm, and then obtain a solid electrolyte membrane. At the same time, it can improve the structural stability and ionic conductivity of the fixed electrolyte membrane.

[0072] In practice, the binder and solid electrolyte, materials used to form a solid electrolyte membrane, can be mixed with a solvent to prepare an electrolyte slurry. The electrolyte slurry is then coated onto a substrate to form a wet film. The wet film on the substrate is then dried by baking or other methods to form a dry film. The substrate with the dry film is then rolled to form a solid electrolyte membrane precursor (self-supporting membrane). The solid electrolyte membrane precursor (i.e., the rolled dry film) is then peeled off from the substrate to obtain an independent solid electrolyte membrane precursor. The solid electrolyte membrane precursor is then sintered in an oxygen-filled sintering furnace to remove the binder, resulting in the solid electrolyte membrane.

[0073] In the above preparation process, the substrate may include a polymer film and / or a metal foil.

[0074] In some embodiments, the polymer film includes one or more of polyethylene terephthalate film (PET film), polyimide film (PI film), and polyamide film (PA film).

[0075] In some embodiments, the metal foil includes one or more of copper foil, aluminum foil, stainless steel foil, nickel foil, and titanium foil.

[0076] In general, during the preparation of the above-mentioned solid electrolyte membrane, the electrolyte slurry can be coated by conventional coating methods in the art, such as microgravure roller coating, wire rod coating, narrow slit extrusion coating, etc., to coat the electrolyte slurry onto the substrate, and there are no particular limitations on this.

[0077] In this embodiment of the invention, rolling can be performed using conventional rolling methods, with the rolling pressure generally between 0.5 MPa and 2 MPa.

[0078] In some embodiments, the average particle size of the solid electrolyte can be 0.4 μm to 1.0 μm, for example, a range of 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 1.0 μm, or any combination thereof. Controlling the average particle size of the solid electrolyte within this range is beneficial for optimizing the rheological properties of the electrolyte slurry, giving it good dispersion stability, facilitating the coating and film-forming process of the electrolyte slurry, avoiding morphological abnormalities such as particles during the coating process, and further optimizing the performance of the prepared solid electrolyte membrane.

[0079] In this embodiment of the invention, the average particle size of the solid electrolyte can be controlled by conventional methods such as grinding, and there are no particular limitations on this.

[0080] In this embodiment of the invention, the average particle size of the solid electrolyte can be obtained by testing and statistical analysis using conventional methods.

[0081] In some embodiments, based on the total mass of the solid electrolyte and the binder, the mass percentage of the solid electrolyte (i.e., the mass percentage of the solid electrolyte to the sum of the masses of the solid electrolyte and the binder) can be 95%-99.5%, for example, a range of 95%, 96%, 97%, 98%, 99%, 99.5% or any two of these.

[0082] In some embodiments, based on the total mass of the solid electrolyte and the binder, the mass percentage of the binder (i.e., the mass percentage of the binder to the sum of the masses of the solid electrolyte and the binder) can be 0.5%-5%, for example, a range of 0.5%, 1%, 2%, 3%, 4%, 5% or any two of these.

[0083] In some embodiments, the solid content of the electrolyte slurry can be 40-70%, for example, a range of 40%, 50%, 60%, 63%, 70%, or any two of these.

[0084] Specifically, the solid content of an electrolyte slurry refers to the ratio of the mass of components other than the solvent in the electrolyte slurry to the total mass of the electrolyte slurry.

[0085] In some embodiments, the viscosity of the electrolyte slurry can be between 1500 mPa·s and 8000 mPa·s, for example, a range of 1500 mPa·s, 2000 mPa·s, 2138 mPa·s, 2500 mPa·s, 3000 mPa·s, 4000 mPa·s, 5000 mPa·s, 6000 mPa·s, 7000 mPa·s, 8000 mPa·s, or any combination thereof.

[0086] In some embodiments, when the electrolyte slurry is coated into a film, the coating thickness (i.e., the thickness of the wet film formed by coating) can be 10-25 μm, for example, a range of 10 μm, 15 μm, 20 μm, 25 μm or any two of these.

[0087] In some embodiments, during the preparation of the solid electrolyte membrane described above, after the electrolyte slurry is coated into a wet film, the wet film is dried to form a dry film. The drying temperature can be 60°C-120°C, for example, a range of 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C or any two of these. The drying time can be 30s-90s, for example, a range of 30s, 60s, 90s or any two of these.

[0088] In some embodiments, during the preparation of the solid electrolyte membrane described above, the dry membrane is rolled to control its thickness to be between 8 μm and 16 μm, for example, 8 μm, 10 μm, 12 μm, 14 μm, 15 μm, 16 μm, or any combination thereof. Controlling the thickness of the dry membrane within this range is beneficial for preparing ultra-thin and highly dense solid electrolyte membranes, meeting the requirements of high-energy-density batteries.

[0089] Specifically, the thickness of the solid electrolyte membrane is lower than the thickness of the dry membrane.

[0090] In some embodiments, the sintering process described above is carried out in an oxygen atmosphere. During the sintering process, the oxygen flow rate can be 0.1 cc / min to 10 cc / min, for example, a range of 0.1 cc / min, 0.5 cc / min, 1 cc / min, 5 cc / min, 10 cc / min, or any combination thereof. Controlling the oxygen flow rate within the above range is beneficial for impurity removal while avoiding excessive gas flow that could affect the integrity of the solid electrolyte membrane.

[0091] In some embodiments, the sintering temperature can be 700℃-1000℃, for example, a range of 700℃, 800℃, 850℃, 900℃, 980℃, 1000℃, or any combination thereof. Controlling the sintering temperature within the above range is beneficial for the solid electrolyte membrane precursor to complete sufficient grain growth and densification processes, while also promoting the decomposition of impurities.

[0092] In some embodiments, the sintering time can be 1h-10h, for example, a range of 1h, 3h, 5h, 7h, 9h, 10h or any two of these.

[0093] In practice, the solid electrolyte membrane precursor can be placed in a sintering furnace with an oxygen atmosphere. After the sintering furnace is purged with gas, oxygen is introduced into the sintering furnace to provide an oxygen atmosphere, and the temperature is increased at a rate of 20°C / min-70°C / min to reach the above-mentioned sintering temperature, so that the solid electrolyte membrane precursor is sintered in an oxygen atmosphere.

[0094] This invention also provides a solid electrolyte membrane prepared by the above-described method for preparing a solid electrolyte membrane.

[0095] In this embodiment of the invention, the solid electrolyte membrane is prepared by the above-described preparation method. The solid electrolyte membrane includes a solid electrolyte, which is basically free of binders and inactive impurities introduced due to factors such as incomplete sintering of binders. It has both good ionic conductivity and structural stability, and has a low cost, which is conducive to industrial application.

[0096] As mentioned above, the solid electrolyte membrane in this embodiment of the invention can also have a relatively thin thickness, which can be less than or equal to 16 μm, or even less than or equal to 10 μm.

[0097] In some embodiments, the thickness of the solid electrolyte membrane can be 8μm-16μm, which is beneficial for further improving the ionic conductivity and structural stability of the solid electrolyte membrane.

[0098] In some embodiments, the solid electrolyte in the solid electrolyte membrane may include an oxide solid electrolyte, which may include one or more of lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanate (LLTO), and lithium titanium aluminum phosphate (LATP) electrolytes.

[0099] This invention also provides a battery comprising the aforementioned solid electrolyte membrane. This battery has advantages corresponding to the aforementioned solid electrolyte membrane.

[0100] In this embodiment of the invention, the battery can be a solid-state battery, specifically an all-solid-state battery.

[0101] Generally, a battery consists of a positive electrode and a negative electrode, with a solid electrolyte membrane located between the positive and negative electrodes.

[0102] Specifically, a battery includes a cell and a casing that encapsulates the cell. The cell includes a positive electrode, a solid electrolyte membrane, and a negative electrode. The solid electrolyte membrane is located between the positive and negative electrodes to separate them and prevent short circuits. At the same time, the solid electrolyte membrane also allows active ions such as lithium ions to pass through, so that active ions such as lithium ions can be inserted and extracted between the positive and negative electrodes, thus realizing the charging and discharging process of the battery.

[0103] In this embodiment of the invention, the battery cell can be packaged using conventional housing materials in the art, such as flexible packaging materials like aluminum-plastic film, but is not limited thereto.

[0104] Generally, a positive electrode sheet includes a positive current collector and a positive electrode coating located on at least one side surface of the positive current collector. Specifically, the positive electrode coating can be provided on one side surface of the positive current collector, or the positive electrode coating can be provided on the opposite two sides of the positive current collector in the thickness direction (i.e., the positive and negative surfaces of the positive current collector).

[0105] Specifically, the positive electrode coating includes materials such as positive electrode active material, conductive agent, and binder, all of which can be conventional materials in the art. For example, the battery described above is a lithium-ion battery, and the positive electrode active material may include lithium-containing positive electrode active material, specifically including one or more of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and ternary positive electrode materials. The ternary positive electrode material may include nickel-cobalt-manganese ternary materials and / or nickel-cobalt-aluminum ternary materials.

[0106] In addition, the conductive agent in the positive electrode coating may include one or more of the following: conductive carbon black (Super. P), conductive graphite, carbon nanotubes (CNT), acetylene black, graphene, Ketjen black, and carbon fiber.

[0107] In addition, the binder in the positive electrode coating may be one or more of the following: polyvinylidene fluoride (PVDF), polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, polyvinyl chloride, carboxylated polyvinyl chloride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, etc.

[0108] In this embodiment of the invention, conventional positive current collectors in the art can be used, for example, the positive current collector includes aluminum foil.

[0109] In this embodiment of the invention, the positive electrode sheet can be prepared by conventional methods in the art, such as by coating. Specifically, the positive electrode active material, conductive agent, binder, and other components used to form the positive electrode active material layer can be dispersed in a positive electrode solvent, such as N-methylpyrrolidone (NMP), to prepare a positive electrode slurry. This slurry is then coated onto the surface of the positive electrode current collector, and after drying, rolling, and other processes, the positive electrode sheet is obtained. The coating, drying, and rolling processes involved are conventional operations for preparing positive electrode sheets using the coating method, and are not particularly limited thereto.

[0110] In addition, the negative electrode sheet may include a metal negative electrode sheet, specifically a lithium metal negative electrode sheet (i.e., the negative electrode sheet is a lithium metal negative electrode), but is not limited thereto. In other embodiments, the negative electrode sheet may also include a negative current collector and a negative electrode coating located on at least one side surface of the negative current collector. Specifically, the negative electrode coating may be provided on one side surface of the negative current collector, or the negative electrode coating may be provided on both sides of the negative current collector in the thickness direction.

[0111] In comparison, solid electrolytes (such as oxide solid electrolytes) have stronger compatibility with metal anodes (such as lithium metal anodes). Therefore, when the anode is a metal anode, it can be better adapted to the solid electrolyte membrane, further improving the battery's cycle stability and other performance characteristics.

[0112] Specifically, the aforementioned negative electrode coating (negative electrode active material layer) may include materials such as negative electrode active material, conductive agent, and binder. These materials can be conventional materials in the field. For example, the negative electrode active material may include one or more of silicon-based materials, siloxy-based materials, silicon-carbon-based materials, graphite, lithium metal, and lithium-indium alloy materials. Graphite may include artificial graphite and / or natural graphite. The conductive agent may include one or more of conductive carbon black, carbon nanotubes (CNT), acetylene black, graphene, Ketjen black, and carbon fiber. The binder may include one or more of sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate.

[0113] The embodiments of the present invention may employ conventional negative electrode current collectors in the art, for example, negative electrode current collectors include copper foil.

[0114] In this embodiment of the invention, the negative electrode sheet can be prepared by conventional methods in the art, such as by coating. Specifically, the components used to form the negative electrode coating, such as the negative electrode active material, conductive agent, and binder, can be dispersed in a fourth solvent, such as water (specifically deionized water), to prepare a negative electrode slurry. Then, the slurry is coated on the surface of the negative electrode current collector, and after drying, rolling and other processes, the negative electrode sheet is obtained.

[0115] In this embodiment of the invention, solid-state batteries can be prepared by conventional methods in the art. The preparation process may include: assembling a positive electrode, a solid electrolyte membrane, and a negative electrode layer into a cell, and then encapsulating it with a casing to obtain a solid-state battery. All the processes involved are conventional preparation processes for solid-state batteries and are not particularly limited thereto.

[0116] The present invention will be further described below through specific embodiments.

[0117] Example 1

[0118] 1. Preparation of multi-component copolymers

[0119] In this embodiment, a multi-component copolymer of ethyl methacrylate, hydroxypropyl acrylate, and acrylic acid is obtained through free radical polymerization. The specific preparation process is as follows:

[0120] Ethyl methacrylate, hydroxypropyl acrylate, and acrylic acid were mixed in ethanol at a mass ratio of 7:2:0.5, and benzoyl peroxide, an initiator, was added. The polymerization reaction was then carried out at 65°C for 6.5 hours. The amount of initiator added was 0.8%, calculated as the mass of initiator divided by the total mass of ethyl methacrylate, hydroxypropyl acrylate, and acrylic acid. The monomer concentration was 40%, calculated as A / B, where A = the sum of the masses of ethyl methacrylate, hydroxypropyl acrylate, and acrylic acid, and B = A + the mass of ethanol.

[0121] After the polymerization reaction is complete, lithium hydroxide is added to the resulting reaction solution to neutralize the pH of the reaction solution to 6.1, thus obtaining a polymer solution containing the multi-component copolymer.

[0122] The polymer solution viscosity was 1543 mPa∙s, the molecular weight of the obtained multi-component copolymer was 30w, the molecular weight distribution index (PDI) was 4.83, and the 100% thermal weight loss temperature of the multi-component copolymer was 373℃.

[0123] 2. Preparation of adhesive

[0124] A polymer solution containing a multi-component copolymer is blended with a monophosphate ester at a mass ratio of 100:5 to obtain an adhesive.

[0125] 3. Preparation of solid electrolyte membranes

[0126] S1. Preparation of solid electrolyte membrane precursor

[0127] Lithium lanthanum zirconium oxide (solid electrolyte) and binder were mixed at a mass ratio of 99:1 to prepare an electrolyte slurry; wherein the particle size of lithium lanthanum zirconium oxide was 0.5 μm, the solid content of the electrolyte slurry was 63%, and the viscosity of the electrolyte slurry was 2138 mPa∙s.

[0128] Electrolyte slurry is coated onto PET film using a micro-gravure roller coating method to form a wet film on the PET film;

[0129] Then the wet film on the PET film is baked at a temperature of 70°C for 30 seconds to form a dry film.

[0130] Then, the PET film with the above-mentioned dry film is rolled, and the thickness of the rolled dry film is controlled at 15 μm, so as to form a solid electrolyte membrane precursor with a thickness of less than 15 μm on the PET film.

[0131] Then, the dry film after rolling is peeled off from the PET film. The dry film peeled off from the PET film is the solid electrolyte membrane precursor (self-supporting membrane).

[0132] S2. Preparation of solid electrolyte membrane

[0133] The solid electrolyte membrane precursor was placed in a sintering furnace. After the furnace was purged with oxygen, oxygen was introduced into it at a flow rate of 0.5 cc / min. Under the oxygen atmosphere, the temperature was increased to 980℃ (the sintering temperature) at a rate of 50℃ / min. The membrane was then sintered at 980℃ for 3 hours to remove the binder from the solid electrolyte membrane precursor, thus obtaining the solid electrolyte membrane.

[0134] Example 2

[0135] 1. Preparation of multi-component copolymers

[0136] In this embodiment, a multi-component copolymer of isooctyl acrylate, 5-hydroxypentyl acrylate, and acrylamide is obtained by free radical polymerization. The specific preparation process is as follows:

[0137] Isooctyl acrylate, 5-hydroxypentyl acrylate, and acrylamide were mixed in dimethyl sulfoxide at a mass ratio of 4.5:0.7:0.2, and azobisisobutyronitrile (AIB) was added as an initiator. The polymerization reaction was then carried out at 70°C for 4.5 hours. The amount of initiator added was 1.3%, calculated as the mass of the initiator divided by the total mass of isooctyl acrylate, 5-hydroxypentyl acrylate, and acrylamide. The monomer concentration was 27%, calculated as A / B, where A is the sum of the masses of isooctyl acrylate, 5-hydroxypentyl acrylate, and acrylamide, and B is the mass of A plus the mass of dimethyl sulfoxide.

[0138] After the polymerization reaction is completed, n-butanolamine is added to the resulting reaction solution to neutralize the pH of the reaction solution to 6.1, thereby obtaining a polymer solution containing a multi-component copolymer.

[0139] The polymer solution had a viscosity of 732 mPa∙s, the resulting multi-component copolymer had a molecular weight of 15w, a molecular weight distribution index (PDI) of 2.38, and a 100% thermal weight loss temperature of 294℃.

[0140] 2. Preparation of adhesive

[0141] A polymer solution containing a multi-component copolymer is blended with vinyltriethoxysilane at a mass ratio of 100:5 to obtain an adhesive.

[0142] 3. Preparation of solid electrolyte membranes

[0143] S1. Preparation of solid electrolyte membrane precursor

[0144] Lithium lanthanum zirconium oxide (solid electrolyte) and binder were mixed at a mass ratio of 98:2 to prepare an electrolyte slurry; wherein the particle size of lithium lanthanum zirconium oxide was 0.7 μm, the solid content of the electrolyte slurry was 70%, and the viscosity of the electrolyte slurry was 1657 mPa∙s.

[0145] Electrolyte slurry is coated onto copper foil using a micro-gravure roller coating process to form a wet film on the copper foil.

[0146] Then the wet film on the copper foil is baked at a temperature of 120°C for 90 seconds to form a dry film.

[0147] Then, the copper foil with the above-mentioned dry film is rolled, and the thickness of the rolled dry film is controlled at 12 μm, so as to form a solid electrolyte membrane precursor with a thickness of less than 12 μm on the PET film.

[0148] Then, the dry film after rolling is peeled off from the copper foil. The dry film peeled off from the copper foil is the solid electrolyte membrane precursor (self-supporting membrane).

[0149] S2. Preparation of solid electrolyte membrane

[0150] The solid electrolyte membrane precursor was placed in a sintering furnace. After the furnace was purged with gas, oxygen was introduced into it at a flow rate of 1 cc / min. Under the oxygen atmosphere, the temperature was increased to 850°C (the sintering temperature) at a rate of 50°C / min. The membrane was sintered at 850°C for 9 hours to remove the binder from the solid electrolyte membrane precursor, thus obtaining the solid electrolyte membrane.

[0151] Example 3: The difference from Example 1 is that the mass ratio of the multi-component copolymer to the additive, the average particle size of the solid electrolyte, the mass ratio of the solid electrolyte to the binder, and the dry film thickness after rolling are different, as detailed in Tables 1, 2, and 3.

[0152] Examples 4 to 6: The difference from Example 3 is that the mass ratio of the multi-component copolymer to the additive is different, as shown in Tables 1, 2 and 3.

[0153] Examples 7-8 and Comparative Examples 1-3 differ from Example 3 in that the mass ratio of the monomers used to prepare the multi-component copolymers is different, as detailed in Tables 1, 2, and 3.

[0154] Examples 9-10: The difference from Example 3 is that the mass ratio of solid electrolyte to binder is different, as shown in Tables 1, 2 and 3.

[0155] Example 11: The difference from Example 3 is that the thickness of the dry film after rolling is different, as shown in Tables 1, 2 and 3.

[0156] Comparative Example 1: The difference from Example 3 is that no additives were added, as detailed in Tables 1, 2, and 3.

[0157] Comparative Example 2: The difference from Example 3 is that no functional monomers were added, as detailed in Tables 1, 2, and 3.

[0158] Comparative Example 3: The difference from Example 3 is that no hydroxy ester monomers were added, as detailed in Tables 1, 2, and 3.

[0159] Comparative Example 4: The difference from the examples lies in the preparation process of the solid electrolyte membrane. The specific preparation process of the solid electrolyte membrane in Comparative Example 4 is as follows:

[0160] S1. Preparation of solid electrolyte membrane precursor

[0161] Lithium lanthanum zirconium oxide powder was filled into an isostatic pressing mold; it was subjected to cold isostatic pressing at a pressing pressure of 20 MPa for 1 h; after pressing, it was demolded to obtain a solid electrolyte membrane precursor with a thickness of 150 μm.

[0162] S2. Preparation of solid electrolyte membrane

[0163] The solid electrolyte membrane precursor was placed in a sintering furnace. After the sintering furnace was purged with gas, oxygen was introduced into it at a flow rate of 1 cc / min. Under the oxygen atmosphere, the temperature was increased to 1800℃ (i.e., the sintering temperature) at a heating rate of 50 ℃ / min. The solid electrolyte membrane was then sintered at 1800℃ for 10 h to obtain the solid electrolyte membrane.

[0164] The properties of the binder and solid electrolyte membrane of each embodiment and comparative example were tested through the following process, and the test results are shown in Table 2.

[0165] 1. Weight-average molecular weight and molecular weight distribution index (PDI) test of multi-component copolymers: Gel permeation chromatography (GPC) was used for testing. Specifically, the polymer solution containing the multi-component copolymer was diluted with deionized water before injection and analysis to obtain the weight-average molecular weight and PDI of the multi-component copolymer.

[0166] 2. 100% Thermogravimetric Temperature (TGA) Test of Multi-component Copolymers: The 100% thermogravimetric temperature of the multi-component copolymers was determined using thermogravimetric analysis (TGA). The test atmosphere of the TGA was set to oxygen, and the temperature program was set to a constant heating rate of 10℃ / min from 25℃ to 800℃. The polymer solution containing the multi-component copolymer was dried to completely evaporate the solvent and moisture, obtaining a solid sample of the multi-component copolymer. The solid sample of the multi-component copolymer was placed in a crucible, and thermogravimetric analysis was performed under the set oxygen atmosphere and temperature program to obtain the thermogravimetric curve of the multi-component copolymer mass as a function of temperature. The 100% thermogravimetric temperature was defined as the initial temperature at which the mass signal of the multi-component copolymer reached and stabilized at the complete weightlessness plateau after the derivative peak of the thermogravimetric curve ended.

[0167] 3. Adhesive film strength test:

[0168] Spread the adhesive evenly in a mold measuring 8cm x 1.5cm x 0.5cm (length x width x depth), place it in a cool, dry place at room temperature for 2-3 days, then transfer it to a 60℃ forced-air oven to dry for 5-10 minutes, until no bubbles remain. Test the dried adhesive film using a CMT6104 universal tensile testing machine.

[0169] Test conditions: test speed 200 mm / min, gauge length 25.00 mm, test temperature 25°C, test humidity 45-55%. The test results are shown in Table 4.

[0170] 4. Adhesive film peel strength test:

[0171] Referring to the aforementioned method S1 for preparing a solid electrolyte membrane, an electrolyte slurry is coated onto a copper foil, a wet film is formed on the copper foil, and then baked to prepare a dry film. Subsequently, the dry film is compacted to achieve a compaction density of 2.4 g / cm³. 3 Cut copper foil with dry film into 20 cm × 3 cm (length × width) samples. With the dry film side facing down, fix the sample to the steel plate tape of the tensile testing machine stand, and use a 2.5 kg pressure roller, one back-and-forth motion as one cycle, for a total of 3 cycles. Use a tensile testing machine with a range of 20 N, with the upper plate clamping the copper foil end, and stretch at a rate of 50 mm / min at a peel angle of 180° to tear the dry film and copper foil. Continue until the dry film separates from the copper foil. Record the average value of the plateau segment in the tensile curve as the peel strength of the film, in Newtons per meter (N / m). The test results are shown in Table 4.

[0172] 5. Ionic conductivity test of solid electrolyte membranes:

[0173] The ionic conductivity of the solid electrolyte membrane at room temperature (25℃) was tested using an electrochemical workstation. A stainless steel electrode was used as the working electrode, and another stainless steel electrode served as the counter and reference electrode. The test frequency was 1Hz–1MHz, and the amplitude was 10mV. The resistance of the adhesive film was determined based on the obtained AC impedance spectroscopy. The formula for calculating the ionic conductivity is as follows, and the measurement results are shown in Table 4.

[0174]

[0175] In the formula,

[0176] σ: Ionic conductivity of the solid electrolyte membrane sample, in units of (S / cm).

[0177] L: Thickness of the solid electrolyte membrane sample, in cm.

[0178] R: Ohmic impedance of the solid electrolyte membrane sample, in Ω.

[0179] S: Cross-sectional area of ​​the solid electrolyte membrane sample, in cm² 2 ).

[0180] Table 1 summarizes the following conditions in each embodiment and comparative example: the types and mass ratios of monomers used to synthesize the multi-component copolymers, the molecular weight of the multi-component copolymers, the molecular weight distribution index (PDI) of the multi-component copolymers, and the 100% thermogravimetric temperature of the multi-component copolymers. Table 2 summarizes the following conditions in each example and comparative example: the types of additives, the mass ratio of the multi-component copolymers to the additives, the polymerization reaction temperature during the preparation of the multi-component copolymers, the polymerization reaction time, the pH of the reaction solution after neutralization with a neutralizing agent after the polymerization reaction, and the viscosity of the polymer solution at room temperature. Table 2 summarizes the following conditions in the preparation of the solid electrolyte membrane: the types of solid electrolytes used, the average particle size of the solid electrolytes, the mass ratio of the solid electrolytes to the binders, the oxygen flow rate, the sintering temperature, the sintering time, and the thickness of the obtained solid electrolyte membrane.

[0181] Table 1

[0182]

[0183] Table 2

[0184]

[0185] Table 3

[0186]

[0187] Continued from Table 3

[0188]

[0189] Table 4

[0190]

[0191] Continued from Table 4

[0192]

[0193] As shown in Table 4, the adhesive film peel strength of the binders in Examples 1-11 is above 12 N / m. This indicates that a strong bond is formed between the binder and the copper foil, as well as with the precursor particles, ensuring that a complete, defect-free solid electrolyte membrane precursor can be peeled off completely after baking and rolling. The extremely low peel strength (4.6 N / m) of Comparative Example 3 directly led to its molding difficulties. This shows that the strength and peel strength of the adhesive film formed by the binder are improved through the synergistic effect of the multi-component copolymer and additives.

[0194] The ionic conductivity of the solid electrolyte membranes in Examples 1-11 was maintained at 4.1 × 10⁻⁻⁻⁻⁶. 4 S / cm up to 6.4×10⁻ 4The S / cm ratio is significantly higher than that of the comparative example. This indicates that the binder provided by the present invention can be completely decomposed and removed after high-temperature sintering, avoiding the problem of residual inactive impurities in the formed solid electrolyte membrane, and thus avoiding the problem of residual inactive impurities blocking the ion transport channels of the solid electrolyte membrane, thereby improving the electrochemical performance of the solid electrolyte membrane such as ionic conductivity.

[0195] Compared to Comparative Examples 1-4, Examples 1-11 exhibit an excellent combination of high Young's modulus and high elongation at break. This indicates that the adhesive provided by the present invention possesses sufficient rigidity to resist deformation and maintain dimensional stability during rolling and peeling processes, making it less prone to breakage or cracking; it also exhibits good flexibility, allowing it to deform under processing stress rather than fracture brittlely, effectively avoiding breakage problems caused by traditional processes, thereby increasing the structural stability of the solid electrolyte membrane formed. In Example 7, the excessive addition of acrylate monomers (ethyl methacrylate) resulted in a softening of the adhesive film, a significant decrease in strength, and a significant increase in elongation at break, thus demonstrating that this type of monomer is beneficial for improving the flexibility of the solid electrolyte membrane.

[0196] In summary, the binder provided by this invention has good adhesion properties, is suitable for preparing solid electrolyte membranes, can improve the molding ability of solid electrolytes and other materials used to form solid electrolyte membranes, and can also improve the structural stability and ionic conductivity of solid electrolyte membranes.

[0197] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A solid-state electrolyte membrane, characterized by, The solid-state electrolyte film is prepared by a preparation process comprising the following steps: coating an electrolyte slurry containing a solid-state electrolyte and a binder into a film to obtain a solid-state electrolyte film precursor; and sintering the solid-state electrolyte film precursor to remove the binder to obtain the solid-state electrolyte film. The binder comprises a multi-component copolymer and an auxiliary agent, the multi-component copolymer comprises a copolymer of acrylic ester structural units, hydroxyl ester structural units and functional structural units, the functional structural units comprise acrylic structural units and / or amide structural units; the auxiliary agent comprises phosphate ester and / or silane coupling agent; the phosphate ester comprises monophosphate ester; the mass ratio of the acrylic ester structural units, the hydroxyl ester structural units and the functional structural units is (4.3-7):(0.5-2):(0.2-1).

2. The solid-state electrolyte film of claim 1, wherein, The mass ratio of the multi-component copolymer to the auxiliary agent is 100:(0.05-5).

3. The solid-state electrolyte film according to claim 1 or 2, characterized in that, The silane coupling agent comprises one or more of alpha-methyl acryloyloxy-methyl-triethoxysilane, gamma-methyl acryloyloxy-propyl-triethoxysilane, vinyl triethoxysilane, cyclohexyl methyl dimethoxysilane.

4. The solid-state electrolyte film according to claim 1 or 2, characterized in that, The acrylic ester structural units comprise methyl acrylate structural units and / or acrylate structural units; And / or, the hydroxyl ester structural units comprise one or more of hydroxyethyl acrylate structural units, hydroxypropyl acrylate structural units, hydroxybutyl acrylate structural units, 5-hydroxy-pentyl-acrylate structural units, 6-hydroxy-hexyl-acrylate structural units; And / or, the acrylic structural units comprise one or more of acrylic acid structural units, methacrylic acid structural units, maleic acid structural units, itaconic acid structural units, cinnamic acid structural units, itaconic acid monomethyl ester structural units, itaconic acid monoethyl ester structural units, itaconic acid monopropyl ester structural units, itaconic acid monobutyl ester structural units; And / or, the amide structural units comprise one or more of acrylamide structural units, dimethyl acrylamide structural units, methacrylamide structural units.

5. The solid-state electrolyte film according to claim 1, characterized in that, The weight average molecular weight of the multi-component copolymer is 10,000 Da-6,000,000 Da; And / or, the molecular weight distribution index PDI of the multi-component copolymer is 1.5-5; And / or, the 100% thermal weight loss temperature of the multi-component copolymer is 200℃-400℃.

6. The solid-state electrolyte film according to claim 1, characterized in that, The pH of the binder is 6-8; And / or, the binder further comprises a solvent, the solvent comprises one or more of alcohol solvents, sulfone solvents, amide solvents.

7. The solid-state electrolyte film according to claim 1, characterized in that, The solid-state electrolyte comprises an oxide solid-state electrolyte; And / or, the average particle size of the solid-state electrolyte is 0.4 μm-1.0 μm; And / or, based on the total mass of the solid-state electrolyte and the binder, the mass proportion of the solid-state electrolyte is 95%-99.5%, and the mass proportion of the binder is 0.5%-5%.

8. A battery, characterized by The solid-state electrolyte film as claimed in any one of claims 1-7.

9. The battery of claim 8, wherein, The battery further comprises a positive electrode sheet and a negative electrode sheet, and the solid-state electrolyte film is located between the positive electrode sheet and the negative electrode sheet; the negative electrode sheet comprises a lithium metal negative electrode sheet.

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