Dry electrolyte membrane, preparation method and application thereof

Abstract

The application provides a dry-method electrolyte film and a preparation method and application thereof, and the dry-method electrolyte film comprises a first electrolyte layer, a second electrolyte layer and a third electrolyte layer which are sequentially stacked, and each electrolyte layer comprises a solid-state electrolyte and a binder; the first electrolyte layer comprises a first binder, and the uniformity of the first binder in the first electrolyte layer is 96%-98%; the second electrolyte layer comprises a second binder, and the uniformity of the second binder in the second electrolyte layer is 98%-99%; and the third electrolyte layer comprises a third binder, and the uniformity of the third binder in the third electrolyte layer is 94%-96%. The dry-method electrolyte film, the preparation method and the application thereof have the advantages that the dry-method electrolyte film has both cohesion and high ionic conductivity, the electrolyte layer is less likely to be broken, and the safety performance of a battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power batteries, and in particular to a dry-process electrolyte membrane and a preparation method and application thereof. Background Art

[0002] With the rapid development of new energy, the development of technologies such as lithium-ion batteries is particularly important. All-solid-state batteries are considered one of the ultimate forms of commercial lithium-ion batteries. By replacing flammable liquid electrolytes with solid-state electrolyte layers, they can provide users with safer next-generation power batteries with higher energy density and better long-term cycle performance. The solid-state electrolyte layer is located between the positive and negative electrodes of the battery, primarily separating them and preventing short circuits.

[0003] The solid electrolyte layer is located between the positive and negative electrodes, and needs to solve problems such as physical contact, chemical compatibility, mechanical matching, and electrochemical kinetic matching with the positive and negative electrodes. Therefore, there is an urgent need to further improve the solid electrolyte layer to improve the performance of all-solid-state batteries. Summary of the Invention

[0004] The present invention proposes a dry electrolyte membrane, a preparation method and an application thereof. Through the dry electrolyte membrane, a preparation method and an application thereof provided by the present invention, the dry electrolyte membrane can simultaneously take into account both cohesion and high ionic conductivity, and at the same time prevent the periodic stress caused by electrode expansion and contraction from causing the electrolyte layer to rupture and lead to battery short circuit, thereby improving the safety performance of the battery.

[0005] To solve the above technical problems, the present invention provides a dry electrolyte membrane, comprising a first electrolyte layer, a second electrolyte layer and a third electrolyte layer stacked in sequence, each electrolyte layer comprising a solid electrolyte and a binder;

[0006] The first electrolyte layer includes a first binder, and the uniformity of the first binder in the first electrolyte layer is 96%-98%;

[0007] The second electrolyte layer includes a second binder, and the uniformity of the second binder in the second electrolyte layer is 98%-99%;

[0008] The third electrolyte layer includes a third binder, and a uniformity of the third binder in the third electrolyte layer is 94%-96%.

[0009] In one embodiment of the present invention, the binder exists in the electrolyte layer in the form of nanofibers, and the diameter of the nanofibers of the second electrolyte layer is smaller than that of the nanofibers of the first electrolyte layer and the third electrolyte layer.

[0010] In one embodiment of the present invention, in the first electrolyte layer, the diameter d of the nanofibers of the first binder is 50 4nm-10nm;

[0011] In the second electrolyte layer, the diameter d of the nanofibers of the second binder is 50 1nm-4nm;

[0012] In the third electrolyte layer, the diameter d of the nanofibers of the third binder is 50 10nm-20nm;

[0013] In each electrolyte layer, the nanofibers each satisfy d 90 / d 10 ≤1.5.

[0014] In one embodiment of the present invention, the first binder, the second binder and the third binder are each selected from one or more combinations of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, ethylene-vinyl acetate copolymer, polypropylene, polyethylene, ethylene-octene copolymer or polyimide;

[0015] And / or, the solid electrolyte is selected from at least one of an oxide solid electrolyte, a sulfide solid electrolyte and a halide solid electrolyte.

[0016] In one embodiment of the present invention, in each electrolyte layer, the content of the binder is 0.2 wt%-1 wt%, and the content ratio of the first binder, the second binder, and the third binder is 1:(0.8-1.2):(0.8-1.2).

[0017] In one embodiment of the present invention, the thickness of the dry electrolyte membrane is 10 μm-30 μm; and the thickness ratio of the first electrolyte layer, the second electrolyte layer and the third electrolyte layer is 1:(2-6):(1.2-1.4).

[0018] The present invention also provides a method for preparing a dry electrolyte membrane, comprising the following steps:

[0019] Sieving binder particles with a preset median particle size to obtain a first binder, a second binder, and a third binder;

[0020] mixing the solid electrolyte with the first binder, the second binder, and the third binder respectively to obtain a first mixed material, a second mixed material, and a third mixed material;

[0021] respectively subjecting the first mixed material, the second mixed material and the third mixed material to fiberization to obtain a first fibrillated material, a second fibrillated material and a third fibrillated material;

[0022] Cooling the first fibrillated material, the second fibrillated material, and the third fibrillated material to a target temperature at a preset rate while applying shear to obtain a first intermediate product, a second intermediate product, and a third intermediate product;

[0023] The first intermediate product, the second intermediate product and the third intermediate product are crushed and granulated to obtain a first electrolyte material, a second electrolyte material and a third electrolyte material respectively;

[0024] The first electrolyte material, the second electrolyte material and the third electrolyte material are respectively formed into films to a set thickness by multi-roll continuous rolling to obtain a first intermediate layer, a second intermediate layer and a third intermediate layer;

[0025] The first intermediate layer, the second intermediate layer and the third intermediate layer are stacked in sequence and rolled into a film by multi-roll continuous rolling to obtain a dry electrolyte membrane.

[0026] In one embodiment of the present invention, the preset median particle size of the first binder particles is 20 μm-50 μm, the preset median particle size of the second binder particles is 5 μm-20 μm, and the preset median particle size of the third binder particles is 50 μm-100 μm.

[0027] In one embodiment of the present invention, the binder particles are sieved at a preset temperature, wherein the preset temperature is 5° C.-20° C.;

[0028] The fibrillation includes a first stage, a second stage and a third stage. In the first stage, the treatment temperature is 20°C-40°C, the stirring linear speed is 20m / s-30m / s, and the stirring time is 10min-30min; in the second stage, the treatment temperature is 60°C-80°C, the stirring linear speed is 40m / s-60m / s, and the stirring time is 10min-30min; in the third stage, the treatment temperature is 90°C-120°C, the stirring linear speed is 60m / s-70m / s, and the stirring time is 60min-120min;

[0029] The preset rate is 10°C / min-15°C / min, and the target temperature is 25°C-40°C;

[0030] During the cooling process, pulse shearing is applied, wherein one pulse shearing comprises shearing at 8 m / s-10 m / s for 4 s-6 s and shearing at 3 m / s-5 m / s for 8 s-12 s.

[0031] The present invention also provides an all-solid-state lithium-ion battery, comprising:

[0032] Positive electrode;

[0033] A negative electrode plate, the negative electrode plate comprising a negative electrode active material, the negative electrode active material comprising a silicon material, the silicon material including but not limited to silicon, silicon carbon and silicon oxygen negative electrode materials;

[0034] The solid electrolyte layer is arranged between the positive electrode plate and the negative electrode plate, and is selected from the dry electrolyte membrane described above, or the dry electrolyte membrane obtained by the preparation method described above. The first electrolyte layer in the dry electrolyte membrane is arranged close to the positive electrode plate.

[0035] The present invention also provides an electronic device comprising the above-mentioned all-solid-state lithium-ion battery.

[0036] In summary, the present invention proposes a dry electrolyte membrane and its preparation method and application. By setting three electrolyte layers and controlling the uniformity of the binder in each of the three electrolyte layers, the second electrolyte layer connects the first electrolyte layer and the third electrolyte layer, and increases the ion path to improve the ionic conductivity of the dry electrolyte membrane, thereby improving the rate performance of the battery. At the same time, the dry electrolyte membrane takes into account both cohesion and high ionic conductivity. At the same time, it can prevent the periodic stress caused by electrode expansion and contraction from causing the electrolyte layer to rupture and lead to battery short circuit, thereby improving the safety performance of the battery. DETAILED DESCRIPTION

[0037] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0038] It should be understood that the present invention can be implemented in different forms and should not be interpreted as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided to make disclosure thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0039] The technical solutions of the present invention are further described in detail below with reference to the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] The present invention proposes a dry electrolyte membrane comprising a first electrolyte layer, a second electrolyte layer, and a third electrolyte layer stacked in sequence, each electrolyte layer comprising a solid electrolyte and a binder. The first electrolyte layer comprises a first binder, the uniformity of the first binder in the first electrolyte layer being 96%-98%, the second electrolyte layer comprises a second binder, the uniformity of the second binder in the second electrolyte layer being 98%-99%, and the third electrolyte layer comprises a third binder, the uniformity of the third binder in the third electrolyte layer being 94%-96%. Uniformity is defined as the degree of dispersion of the binder distribution within multiple detection regions of the electrolyte layer, and the degree of dispersion is negatively correlated with uniformity. By providing three electrolyte layers and controlling the uniformity of the binder within the three layers, the dry electrolyte membrane can achieve both cohesion and high ionic conductivity. It can also prevent periodic stress caused by electrode expansion and contraction from causing electrolyte layer rupture and battery short circuits, thereby improving battery safety.

[0041] In one embodiment of the present invention, the binder exists in the form of nanofibers in each electrolyte layer to form a three-dimensional nano-network structure to improve the cohesion of the electrolyte layer. The diameter of the nanofibers in the second electrolyte layer is smaller than that of the first and third electrolyte layers to connect the first and third electrolyte layers and improve the rate performance of the battery. In the first electrolyte layer, the diameter d of the nanofibers of the first binder is 50 For example, the diameter d of the nanofibers of the second binder in the second electrolyte layer is 4 nm to 10 nm. 50 For example, the diameter d of the nanofibers of the third binder in the third electrolyte layer is 1 nm to 4 nm. 50 For example, the nanofibers are 10 nm to 20 nm in each electrolyte layer, and each of the nanofibers satisfies d 90 / d 10 ≤1.5. Where, d 50 is the diameter of the nanofibers when the number of nanofibers increases from small to large and reaches 50%, d 10 is the diameter of the nanofibers when the number of nanofibers increases from small to large and reaches 10%, d 90 The diameter of the nanofibers when the number of nanofibers from small to large accumulates to 90%. When the preparation process is the same, the uniformity of the binder in the electrolyte layer is related to the diameter of the nanofibers, showing that: the smaller the nanofiber diameter, the higher the uniformity of the binder in the electrolyte layer, the higher the ionic conductivity, but the strength of the nanofibers decreases. Therefore, under the condition of controlling the uniformity, the diameter of the binder nanofibers is controlled so that each electrolyte layer has both cohesion and high ionic conductivity. When the diameter of the nanofiber d 90 / d 10When within the above range, the dispersion uniformity of the nanofibers in each electrolyte layer is high, which improves the uniformity and stability of the binder in each electrolyte layer. For example, it can avoid the obstruction of ion transmission caused by local fibers being too thick, and it can also avoid the local mechanical strength being insufficient due to local fibers being too thin. Local defects can cause performance deterioration.

[0042] In one embodiment of the present invention, when the dry electrolyte membrane is applied to a battery, the first electrolyte layer is placed facing the positive electrode sheet with a certain degree of expansion, and the diameter d of the nanofibers of the first binder is controlled. 50 The diameter of the nanofibers of the third binder is d, which is 4nm-10nm. The nanofibers of the third binder have a diameter of d, which is 10nm. The diameter of the nanofibers of the third binder is ... 50 The diameter of the nanofibers in the third electrolyte layer is 10nm-20nm, which increases the strength of the nanofibers and thus improves the mechanical strength of the dry electrolyte membrane. This can prevent the cyclic stress caused by electrode expansion and contraction from causing the third electrolyte layer to rupture and lead to battery short circuit, thereby improving the safety performance of the battery. The second electrolyte layer is located between the first and second electrolyte layers, not facing the electrodes, and controls the diameter of the nanofibers of the second binder. 50 At 1nm-4nm, the characteristics of the first electrolyte layer and the third electrolyte layer are coordinated to optimize the overall mechanical properties and ionic conductivity of the dry electrolyte membrane.

[0043] In one embodiment of the present invention, the first, second, and third binders are each selected from one or more of polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene (ETFE), ethylene-vinyl acetate (EVA), polypropylene (PP), polyethylene (PE), ethylene-octene copolymer, or polyimide (PI). The molecular weight of the binder is, for example, 6000 kg / mol to 8000 kg / mol. When the molecular weight of the binder is low, the bonding between the nanofibers formed by the binder is weak, resulting in insufficient strength of the formed three-dimensional nanonetwork. The binder content in each electrolyte layer is 0.2 wt% to 1 wt%, and the ratio of the first, second, and third binders is 1:(0.8-1.2):(0.8-1.2). That is, in the present application, the types of binders in the first electrolyte layer, the second electrolyte layer and the third electrolyte layer can be the same or different, and the content of the binder in each layer is set separately, so that while controlling the uniformity of the binder in each layer, the cohesion and the number of ion paths in each layer are balanced, thereby meeting the needs of different electrolyte layers and improving the quality of the dry electrolyte membrane.

[0044] In one embodiment of the present invention, the thickness of the dry-process electrolyte membrane is, for example, 10 μm to 30 μm, and the thickness ratio of the first, second, and third electrolyte layers is, for example, 1:(2-6):(1.2-1.4), meaning the second electrolyte layer is thicker than the third electrolyte layer, which in turn is thicker than the first electrolyte layer. By increasing the thickness ratio of the highly uniform second electrolyte layer, high ionic conductivity can be achieved. Controlling the thickness of the third electrolyte layer can reduce cracking in the dry-process electrolyte membrane. Controlling the thickness ratio of the three electrolyte layers can achieve a balance between high cohesion and high ionic conductivity for the dry-process electrolyte membrane.

[0045] In one embodiment of the present invention, the solid electrolyte is selected from at least one of an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte, and for example, is selected from Li7La3Zr2O 12 、Li 13 Al3Ti 17 (PO4)3、Li 10 GeP2S 12Li6PS5Cl, Li3InCl6, or Li3YCl6, etc. In different electrolyte layers, the solid-state electrolyte may or may not be the same.

[0046] Based on the dry electrolyte film described above, the present application further proposes a preparation method of the dry electrolyte film, at least comprising: screening binder particles of a preset median particle size to obtain a first binder, a second binder, and a third binder; mixing the solid-state electrolyte with the first binder, the second binder, and the third binder respectively to obtain a first mixture, a second mixture, and a third mixture; respectively performing fibrillation treatment on the first mixture, the second mixture, and the third mixture to obtain a first fibrillation material, a second fibrillation material, and a third fibrillation material; cooling the first fibrillation material, the second fibrillation material, and the third fibrillation material to a target temperature at a preset rate while applying shearing to obtain a first intermediate product, a second intermediate product, and a third intermediate product; and respectively rolling the first intermediate product, the second intermediate product, and the third intermediate product into a film through multi-roller continuous rolling to a set thickness to obtain a first intermediate layer, a second intermediate layer, and a third intermediate layer; and stacking the first intermediate layer, the second intermediate layer, and the third intermediate layer in sequence and rolling them into a film through multi-roller continuous rolling to obtain the dry electrolyte film.

[0047] In an embodiment of the present application, the binder is cooled to a brittle point of -40℃, and a closed-loop heat preservation crushing device is used for grinding to obtain a ground binder. The ground binder is screened through a screen with different pore sizes to obtain binder particles of a preset median particle size. The median particle size D50 refers to the particle size value corresponding to the cumulative volume distribution percentage of 50% in the volume distribution curve. In this embodiment, the screen pore size is, for example, 3μm-110μm, and the preset temperature is, for example, 5℃-20℃. Screening at the preset temperature can prevent agglomeration of the binder due to excessively high temperature and obtain solid binder particles. In this embodiment, the preset median particle size of the first binder particles is, for example, 20μm-50μm, the preset median particle size of the second binder particles is, for example, 5μm-20μm, and the preset median particle size of the third binder particles is, for example, 50μm-100μm.

[0048] When the median particle size of the binder particles is smaller, the diameter of the binder nanofibers in the solid electrolyte layer obtained is finer, and the uniformity of the binder in the solid electrolyte layer is better. When the median particle size of the binder particles is larger, the fiber network formed by the large-particle binder during the fiberization process is coarser, the fiber strength is greater, and the uniformity of the binder in the solid electrolyte layer deteriorates. Therefore, by controlling the particle size of the binder particles in each layer, the diameter and distribution of the nanofibers formed by the binder can be controlled, and the uniformity of each electrolyte layer can be regulated. By reducing the particle size of the binder in the second electrolyte layer, the distribution of the binder between the solid electrolytes can be made finer. The increased ion pathways can improve the ionic conductivity of the dry electrolyte membrane. By relatively increasing the binder particle size of the electrolyte layers on both sides, the periodic stress caused by electrode expansion and contraction can be prevented from causing the electrolyte layer to rupture and lead to battery short circuit, so that the dry electrolyte membrane has both internal cohesion and high ionic conductivity.

[0049] In one embodiment of the present invention, the solid electrolyte is mixed with the first binder, the second binder and the third binder respectively to obtain a first mixture, a second mixture and a third mixture. During the mixing, the components in the mixture are mixed more evenly by stirring. For example, the stirring line speed can be controlled to be, for example, 5m / s-20m / s, the stirring time can be, for example, 20min-60min, and the processing temperature can be, for example, 5°C-20°C. By controlling the processing temperature and line speed, problems such as agglomeration or local overheating of the binder particles caused by excessive temperature can be avoided, thereby avoiding uneven dispersion of the binder particles in the mixture. In this step, the content of the binder in each mixture is controlled to control the binder content in the formed electrolyte layer. At the same time, in this step, the solid electrolytes can be the same or different.

[0050] In one embodiment of the present invention, the first mixture, the second mixture and the third mixture are respectively subjected to fiberization treatment to obtain the first fibrillated material, the second fibrillated material and the third fibrillated material. In this embodiment, the fibrillation includes a first stage, a second stage and a third stage. In the first stage, the treatment temperature is, for example, 20°C-40°C, the stirring linear speed is, for example, 20m / s-30m / s, and the stirring time is, for example, 10min-30min; in the second stage, the treatment temperature is, for example, 60°C-80°C, the stirring linear speed is, for example, 40m / s-60m / s, and the stirring time is, for example, 10min-30min; in the third stage, the treatment temperature is, for example, 90°C-120°C, the stirring linear speed is, for example, 60m / s-70m / s, and the stirring time is, for example, 60min-120min. Through the three-stage fibrillation treatment, the synergistic effect of the step-by-step temperature increase and segmented speed-up shearing of the fibrillation is controlled to avoid excessive breakage or agglomeration of the binder. The high linear speed and time of the third stage are used to maximize the highest uniformity of the binder, thereby converting the binder particles into nanofibers. The nanofibers form a uniform and dense three-dimensional network structure, thereby improving the strength of the subsequent electrolyte membrane. In this embodiment, due to the limitations of the production process, the d of each layer of nanofibers obtained is 90 / d 10 ≥1.2.

[0051] In one embodiment of the present invention, after the fibrillation treatment step, the first fibrillated material, the second fibrillated material, and the third fibrillated material are cooled to a target temperature at a preset rate, for example, 10°C / min-15°C / min, and the target temperature is, for example, 25°C-40°C. During the cooling process, shearing is applied simultaneously to obtain a first intermediate product, a second intermediate product, and a third intermediate product. In this embodiment, the shearing is, for example, pulse shearing, and one pulse shearing includes shearing at 8m / s-10m / s for 4s-6s and shearing at 3m / s-5m / s for 8s-12s. Through rapid cooling and pulse shearing, the fiber structure can be locked to avoid fiber shrinkage caused by natural cooling, thereby stabilizing the size and distribution state of the nanofibers and obtaining a highly uniform binder distribution. At the same time, the d of the nanofibers formed by the binder can be reduced by step-by-step heating, segmented speed-up shearing, rapid cooling, and pulse shearing. 90 / d 10 , improving the uniformity of nanofiber diameter.

[0052] In one embodiment of the present invention, the first, second, and third intermediate products are crushed and granulated to produce a first electrolyte material, a second electrolyte material, and a third electrolyte material. The first, second, and third electrolyte materials are then rolled to a desired thickness using a multi-roller continuous rolling mill to produce a first intermediate layer, a second intermediate layer, and a third intermediate layer. The thickness ratio of the first, second, and third intermediate layers is, for example, 1:(2-6):(1.2-1.4), and the desired thickness of the first intermediate layer is, for example, 50 μm to 100 μm. The first, second, and third intermediate layers are then stacked and rolled using a multi-roller continuous rolling mill to produce a dry-process electrolyte membrane of a desired thickness. By manipulating the parameters used in the dry-process electrolyte membrane preparation process, the uniformity of the binder in each electrolyte layer can be maximized, resulting in a more uniform distribution of the nanofibers. This results in a dry-process electrolyte membrane with superior performance, thereby improving battery performance.

[0053] The present invention also provides an all-solid-state lithium-ion battery comprising a positive electrode sheet, a negative electrode sheet, and a solid electrolyte layer, wherein the solid electrolyte layer is disposed between the positive and negative electrode sheets and is selected from the dry-process electrolyte membrane described above. In the present invention, the all-solid-state battery is, for example, a primary battery or a secondary battery, and the secondary battery is, for example, a pouch cell, a prismatic cell, or a cylindrical cell. The present invention does not impose any specific restrictions on the type or type of the all-solid-state battery.

[0054] In one embodiment of the present invention, the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer coated on at least one surface of the positive electrode current collector. The positive electrode current collector is, for example, a surface-treated foil of nickel, titanium, aluminum, silver, stainless steel, or carbon. In addition to foil, the positive electrode current collector may also be in the form of a film, mesh, porous material, foam, or non-woven fabric, among other forms, or any combination thereof.

[0055] In one embodiment of the present invention, the positive electrode active layer includes a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder. The ratio of the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder can be selected based on actual needs. In this embodiment, the positive electrode active material includes, for example, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or a lithium-rich manganese-based oxide. The positive electrode conductive agent is, for example, selected from at least one of conductive carbon black, acetylene black, carbon nanotubes, or graphene. The positive electrode binder is, for example, selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyethylene oxide (PEO), polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyethylene ether, polymethyl methacrylate (PMMA), ethylene-propylene-diene terpolymer (EPDM), and polyhexafluoropropylene.

[0056] In one embodiment of the present invention, the positive electrode active layer further includes a solid electrolyte, which is selected from at least one of an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte, and is further selected from Li7La3Zr2O 12 、Li 13 Al3Ti 17 (PO4)3、Li 10 GeP2S 12 , Li6PS5Cl, Li3InCl6, or Li3YCl6. The mass ratio of the positive electrode active material, solid electrolyte, positive electrode conductive agent, and positive electrode binder is, for example, (64-93.9): (5-30): (1-5): (0.1-1). The positive electrode active layer can be prepared by a dry process or a wet process, which is not specifically limited in this application.

[0057] In one embodiment of the present invention, the negative electrode plate is, for example, an indium plate, a lithium plate, an aluminum plate, or an alloy plate composed of at least two of the above metals. In other embodiments of the present invention, the negative electrode plate further comprises, for example, a negative electrode current collector and a negative electrode active layer coated on at least one surface of the negative electrode current collector. The negative electrode current collector is, for example, a copper foil current collector, a composite copper foil current collector, a carbon current collector, a foam copper current collector, or a stainless steel current collector, and the negative electrode active layer comprises a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder. The proportions of the negative electrode active material, the negative electrode conductive agent, and the negative electrode binder can be selected according to actual needs. In this embodiment, the negative electrode active material is selected from a graphite material, a silicon material, or a composite material composed of a combination of the two. When it is a composite material, the mass percentage of the silicon material in the negative electrode active material is 0-100wt%. Among them, graphite materials include at least one of natural graphite or artificial graphite, natural graphite includes at least one of block graphite, flake graphite or earthy graphite, artificial graphite includes at least one of single crystal graphite, polycrystalline graphite, pyrolytic graphite or graphite fiber, silicon materials include but are not limited to silicon, silicon-carbon materials and silicon-oxygen negative electrode materials (SiO x , 0 <x<2),硅碳材料例如为多孔碳嵌入硅的结构。负极导电剂例如选自Super P、乙炔黑、科琴黑、碳纳米管或石墨烯等中的至少一种,负极粘结剂例如选自聚丙烯、聚四氟乙烯、聚丙烯酸酯、聚乙烯醚、聚甲基丙烯酸甲酯、聚六氟丙烯或丁苯橡胶等中的至少一种。负极活性层可以通过干法或湿法进行制备,本申请不作具体限制。

[0058] In one embodiment of the present invention, the negative electrode active layer further includes a solid electrolyte, which is selected from at least one of an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte, and is further selected from Li7La3Zr2O 12 、Li 13 Al3Ti 17 (PO4)3、Li 10 GeP2S 12 , Li6PS5Cl, Li3InCl6 or Li3YCl6, etc. When the negative electrode active layer includes a solid electrolyte, the mass ratio of the negative electrode active material, the solid electrolyte, the negative electrode conductive agent and the negative electrode binder is, for example, (55-93): (5.5-30): (1-5): (0.5-10).

[0059] In one embodiment of the present invention, the positive electrode sheet, dry-process electrolyte membrane, and negative electrode sheet are sequentially placed into a mold for assembly. After assembly, the mold is pressurized to 100 MPa and the nuts at the top of the columns are tightened to maintain a constant pressure, thereby producing an all-solid-state lithium-ion battery. The assembly process is performed under an argon atmosphere or vacuum.

[0060] Hereinafter, the present invention will be explained in more detail by citing examples, which should not be construed as limiting. Appropriate modifications may be made within the scope consistent with the gist of the present invention, all of which fall within the technical scope of the present invention.

[0061] Example 1

[0062] Screening of binder particles: Cool PTFE to its brittle point of -40°C and grind it in a closed-circuit, temperature-controlled pulverizing device. Control the post-grinding D50 to ≤100μm to obtain ground PTFE. Sieve the PTFE through sieves of varying apertures. For example, sieve the PTFE through a 40μm sieve, collecting the PTFE particles that pass through the sieve. Then, sieve the PTFE particles that pass through the sieve through a 30μm sieve, collecting the PTFE particles that do not pass through the sieve, and obtain a first binder having a median particle size of 36μm. The sieving temperature is 10°C. Similarly, sieve the PTFE through sieves with apertures of 12μm and 8μm to obtain a second binder, and sieve the PTFE through sieves with apertures of 80μm and 70μm to obtain a third binder. The median particle size of the second binder is 10μm, and the median particle size of the third binder is 75μm. The binder raw material was obtained from Daikin Fluorochemical (China) Co., Ltd., model F106C, with a molecular weight of 6000 kg / mol.

[0063] Preparation of dry electrolyte membrane: The first binder, the second binder, and the third binder are mixed with Li6PS5Cl to obtain a first mixture, a second mixture, and a third mixture, respectively, wherein the stirring linear velocity is 15 m / s, the stirring time is 30 min, and the treatment temperature is 10°C. The first mixture, the second mixture, and the third mixture are subjected to fiberization treatment to obtain a first fibrillated material, a second fibrillated material, and a third fibrillated material, respectively. The first stage treatment temperature is 25°C, the stirring linear velocity is 20 m / s, and the stirring time is 10 min; the second stage treatment temperature is 80°C, the stirring linear velocity is 50 m / s, and the stirring time is 10 min; the third stage treatment temperature is 120°C, the stirring linear velocity is 70 m / s, and the stirring time is 90 min. After fiberization, the resulting products were quenched to 25°C at a rate of 15°C / min while being pulsed sheared, with a pulse cycle of 10 m / s for 5 seconds and 5 m / s for 10 seconds, to obtain the first, second, and third intermediate products. The first, second, and third intermediate products were crushed and granulated to obtain the first, second, and third electrolyte materials, respectively. The first, second, and third electrolyte materials were then rolled into films using a multi-roll continuous rolling mill and thinned to 50 μm, 200 μm, and 70 μm, respectively, to obtain the first, second, and third intermediate layers. The first, second, and third intermediate layers were then stacked and rolled into films using a multi-roll continuous rolling mill and thinned to 20 μm, yielding a dry-process electrolyte membrane. The binder content in the first, second, and third electrolyte layers was 1:1:1, each containing 0.5 wt%. The thickness ratio of the first electrolyte layer, the second electrolyte layer and the third electrolyte layer is 1:4:1.4. The solid electrolyte is Li6PS5Cl, which is sourced from Shandong Xinjieneng Lithium Battery Co., Ltd. and the model is LPSCl.

[0064] Preparation of positive electrode: LiNi 0.8 Co 0.1 Mn 0.1 The mass ratio of O₂, Li₆PS₅Cl₃, conductive carbon black, and binder (PTFE) was 85:13:1:1. The membrane was prepared using a dry process, using the same mixing and preparation procedures and conditions as those used for dry-process electrolyte membranes. After forming, the membrane was laminated with aluminum foil. The binder (PTFE) was sourced from Daikin Fluorochemicals (China) Co., Ltd., model F106C, and was used directly without further treatment.

[0065] Preparation of the negative electrode sheet: The mass ratio of the negative electrode active material, solid electrolyte (Li6PS5Cl), conductive carbon black, and binder (PTFE) is 70:24:5:1. The negative electrode active material is a silicon-carbon material with a silicon content of 13%, sourced from Guangdong Candlelight New Energy Technology Co., Ltd., model number: Silicon-Carbon Material 650. The negative electrode sheet is prepared using a dry process. The mixing and preparation process and conditions are consistent with the dry process for preparing the electrolyte membrane. After film formation, it is composited with copper foil. The binder (PTFE) is sourced from Daikin Fluorochemical (China) Co., Ltd., model number: F106C, and is used directly without further treatment.

[0066] Battery Preparation: The positive electrode sheet, dry electrolyte membrane, and negative electrode sheet are sequentially placed into a mold for assembly. After assembly, the pressure is applied to 100 MPa and the nuts at the top of the columns are tightened to maintain a constant pressure to produce an all-solid-state lithium-ion battery. The assembly process is completed in an argon-filled glove box. The diameters of the positive electrode sheet, dry electrolyte membrane, and negative electrode sheet are all 10 mm.

[0067] Example 2

[0068] The binder screening process was adjusted to a median particle size of 20 μm for the first binder, 5 μm for the second binder, and 50 μm for the third binder. The remaining battery preparation steps (including the positive and negative electrode sheet preparation processes) were the same as in Example 1.

[0069] Example 3

[0070] The screening process of the binders was adjusted so that the median particle size of the first binder was 50 μm, the median particle size of the second binder was 20 μm, and the median particle size of the third binder was 100 μm. The other steps of preparing the battery were the same as those in Example 1.

[0071] Example 4

[0072] The screening process of the binder was adjusted, and the median particle size of the third binder was 100 μm. The other preparation steps of the battery were the same as those in Example 1.

[0073] Example 5

[0074] The screening process of the binder was adjusted, and the median particle size of the second binder was 20 μm. The other preparation steps of the battery were the same as those in Example 1.

[0075] Example 6

[0076] The ratio of the binder content in the first electrolyte layer, the second electrolyte layer, and the third electrolyte layer is 1:1:1, and the binder content is 0.2 wt % in each layer. The other steps of preparing the battery are the same as those in Example 1.

[0077] Example 7

[0078] The ratio of the binder content in the first electrolyte layer, the second electrolyte layer, and the third electrolyte layer was 1:1:1, all of which were 1 wt %. The other steps in preparing the battery were the same as those in Example 1.

[0079] Example 8

[0080] The total thickness of the dry electrolyte membrane is 30 μm, the thickness ratio of the first electrolyte layer, the second electrolyte layer and the third electrolyte layer is 1 / 2 / 1.2, and the preparation steps of the other batteries are the same as those in Example 1.

[0081] Example 9

[0082] The total thickness of the dry electrolyte membrane is 10 μm, the thickness ratio of the first electrolyte layer, the second electrolyte layer and the third electrolyte layer is 1 / 6 / 1.2, and the other preparation steps of the battery are the same as those in Example 1.

[0083] Example 10

[0084] The thickness ratio of the first electrolyte layer, the second electrolyte layer, and the third electrolyte layer is 1 / 1 / 1. The other preparation steps of the battery are the same as those in Example 1.

[0085] Example 11

[0086] The thickness ratio of the first electrolyte layer, the second electrolyte layer, and the third electrolyte layer is 1 / 7 / 1. The other preparation steps of the battery are the same as those in Example 1.

[0087] Example 12

[0088] The binder has a molecular weight of 8000 kg / mol and is sourced from Daikin Fluorochemical, model F121. The other steps in preparing the battery are the same as those in Example 1.

[0089] Comparative Example 1

[0090] The dry-process electrolyte membrane has a single-layer structure, the binder has a median particle size of 5 μm, and the other preparation steps of the battery are the same as those in Example 1.

[0091] Comparative Example 2

[0092] The dry-process electrolyte membrane has a single-layer structure, the binder has a median particle size of 50 μm, and the other preparation steps of the battery are the same as those in Example 1.

[0093] Comparative Example 3

[0094] The dry-process electrolyte membrane has a single-layer structure, the binder has a median particle size of 100 μm, and the other preparation steps of the battery are the same as those in Example 1.

[0095] Comparative Example 4

[0096] The dry-process electrolyte membrane has a single-layer structure, the binder has a median particle size of 400 μm, and the other preparation steps of the battery are the same as those in Example 1.

[0097] Comparative Example 5

[0098] The dry electrolyte membrane has a single-layer structure, the binder has a median particle size of 400 μm, and when obtaining the mixture, the stirring line speed is 15 m / s, the stirring time is 30 min, and the treatment temperature is 10 ° C to obtain the mixture. The mixture is subjected to a fiberization treatment to obtain a fibrillated material, the stirring line speed is 50 m / s, the stirring time is 20 min, and the treatment temperature is 100 ° C. After the fiberization is completed, it is naturally cooled to 25 ° C, and no shearing is performed during the cooling process. The preparation steps of the other batteries are the same as those in Example 1.

[0099] Comparative Example 6

[0100] The ratio of the binder content in the first electrolyte layer, the second electrolyte layer, and the third electrolyte layer is 1:1:1, and the binder content is 0.1 wt % in each layer. The other steps of preparing the battery are the same as those in Example 1.

[0101] Comparative Example 7

[0102] The ratio of the binder content in the first electrolyte layer, the second electrolyte layer, and the third electrolyte layer was 1:1:1, and all were 2 wt %. The other steps of preparing the battery were the same as those in Example 1.

[0103] Comparative Example 8

[0104] The second electrolyte layer was not provided, the thickness ratio of the first electrolyte layer to the third electrolyte layer was 1:1, and the other preparation steps of the battery were the same as those in Example 1.

[0105] Comparative Example 9

[0106] The screening process of the binder was adjusted, and the median particle size of the second binder was 250 μm. The other preparation steps of the battery were the same as those in Example 1.

[0107] Comparative Example 10

[0108] The screening process of the binder was adjusted, and the median particle size of the third binder was 400 μm. The other preparation steps of the battery were the same as those in Example 1.

[0109] Comparative Example 11

[0110] The screening process of the binder was adjusted, the median particle size of the second binder was 50 μm, and the median particle size of the third binder was 400 μm. The other preparation steps of the battery were the same as those in Example 1.

[0111] Comparative Example 12

[0112] The binder has a molecular weight of 2000 kg / mol and is sourced from Daikin Fluorochemical, model F104. The other steps in preparing the battery are the same as those in Example 1.

[0113] In the present invention, all unlabeled reagents and raw materials used in Examples 1-12 and Comparative Examples 1-12 are commercially available. Performance tests were conducted on the dry-process electrolyte membranes and all-solid-state lithium-ion batteries in Examples 1-12 and Comparative Examples 1-12, and the test results were recorded.

[0114] In one embodiment of the present invention, to determine the uniformity of the binder in a dry-process electrolyte membrane, Fourier transform infrared spectroscopy (FTIR) can be used to confirm the specific type of binder in the dry-process electrolyte membrane. In this application, for example, the electrolyte membrane is polished and thinned using focused ion beam (FIB) polishing technology to achieve delamination. Each delaminated electrolyte layer is used as a sample, and the binder type is determined by the position of characteristic functional group peaks. After determining the binder type, the characteristic chemical bonds of the binder are selected for characterization. The uniformity of the binder on the electrolyte layer surface is observed using energy dispersive X-ray spectroscopy (EDS). Specifically, the uniformity of the binder distribution can be best observed by increasing the magnification to 5000x. The specific process includes first selecting the middle area of ​​the electrolyte layer as the observation object, and randomly selecting 5 areas of 50μm×50μm. The 5 areas are arranged along the same line with a center point interval of 500μm. The proportion of different elements is obtained by EDS surface scanning, and the characteristic element of the binder is selected as the result of the area, such as PTFE as F element. The ratio of the standard deviation and the mean of the F element content in these 5 areas is obtained, and the ratio is subtracted from 1. The result is used as the uniformity of the binder in the electrolyte layer of a sample. Five dry electrolyte membranes obtained in the same embodiment or comparative example are selected and layered to obtain parallel samples of each electrolyte layer, and the uniformity data of the binder of the 5 parallel samples are obtained. The average value is recorded as the uniformity of the binder in the embodiment or comparative example.

[0115] In one embodiment of the present invention, the binder content is obtained by testing the characteristic element absorption peak of the binder by Fourier transform infrared spectroscopy. For example, PTFE has a unique infrared absorption peak (such as 1200 cm -1 -1300cm -1The content of PTFE can be quantitatively analyzed by FTIR. Operation steps: the electrolyte membrane is thinned by FIB ion beam polishing technology, layering is realized, and the powder is ground, mixed with KBr, and pressed into a tablet, or the ATR (attenuated total reflection) mode is directly used to test, collect the infrared spectrum of the sample, and quantitatively analyze the content of PTFE in each layer of the dry electrolyte membrane by standard curve or peak area integration.

[0116] In an embodiment of the present application, the existence form of the binder in the dry electrolyte membrane is nanofiber, and the diameter of the nanofiber is tested by scanning electron microscopy (SEM) or transmission electron microscopy (TEM). The electrolyte membrane is thinned by FIB ion beam polishing technology, layering is realized, and each electrolyte layer is placed in a testing device. Under a magnification of 50,000, fibers with a length greater than 5 μm are taken, and a point value width is taken every 200 nm along the fiber axis to obtain the average value of each point value width as the diameter of the fiber. Arbitrarily take 100 fibers, arrange the diameters from small to large, and obtain the diameters at the 10th, 50th, and 90th positions, denoted as d 10 , d 50 , d 90 .

[0117] Select five dry electrolyte membranes obtained in the same embodiment or comparative example as parallel samples. As above, obtain d 10 , d 50 , and d 90 of the nanofiber binder of each parallel sample of the electrolyte layer, and obtain the average values of d 50 , d 90 , and d 10 of the five parallel samples as d 50 , d 90 , and d 10 values of the embodiment or comparative example.

[0118] In an embodiment of the present application, the tensile strength is the meaning known in the art, and instruments and methods known in the art can be used for testing. An exemplary testing method is as follows: cut a dry electrolyte membrane sample with a total length ≥ 150 mm and a width (w) of 20 mm, and adjust the state in a 25 ± 2 °C / 50 ± 5% RH environment for ≥ 88 hours; accurately measure the thickness of the three-point distance section with a micrometer and take the average value h (μm); set the initial distance of the tensile testing machine clamp to 100 mm ± 5 mm, and select the tensile speed according to the pre-test breaking elongation; record the maximum load L (N) at break, and calculate the tensile strength (unit: MPa) according to the formula L / (w×h×10 -3 ).

[0119] In one embodiment of the present invention, the dry electrolyte membranes prepared in the examples and comparative examples were subjected to AC impedance spectroscopy testing at 25°C and normal pressure. Specifically, 150 mg of the dry electrolyte membrane was placed in a sleeve with a diameter of 10 mm, and stainless steel poles were placed at both ends to compact the membrane. The impedance of the blocked cell was measured using an electrochemical workstation at 300 MPa, using the formula: σ = L / SR b The ionic conductivity of the dry electrolyte membrane is calculated, where σ is the ionic conductivity of the dry electrolyte membrane, L is the thickness of the dry electrolyte membrane, S is the effective area of ​​the dry electrolyte membrane, and R b is the impedance of the dry electrolyte membrane at room temperature.

[0120] In one embodiment of the present invention, in order to obtain normal temperature cycle performance, the all-solid-state lithium-ion batteries obtained in Examples 1-12 and Comparative Examples 1-12 are subjected to long-cycle charge and discharge after constant capacity at 25°C, and the number of normal temperature cycle laps is measured. The test conditions are to perform a long-cycle charge and discharge test on the battery after constant capacity, and record the first-cycle discharge capacity during the process. When the battery capacity reaches 80% (80% State of Health, 80% SOH) of the first-cycle capacity, the test is terminated to obtain the normal temperature cycle number. The test voltage range is 2.5V-4.3V, and the constant capacity current is 0.6mA. The normal temperature cycle test rate is 0.3C. Under the condition of 2C, the discharge capacity is measured as the rate performance.

[0121] Table 1. Some parameters of dry-process electrolyte membranes and battery performance in Examples 1-9 and Comparative Examples 1-11

[0122]

[0123] As shown in Table 1, by comparing Examples 1-3 and Comparative Examples 1-3, it can be seen that by providing a three-layer dry-process electrolyte membrane and controlling the uniformity of the binder in the three electrolyte layers, the tensile strength and ionic conductivity of the dry-process electrolyte membrane can be balanced relative to a single-layer electrolyte layer. That is, both cohesion and high ionic conductivity are taken into account, resulting in better overall performance of the battery, such as the first-cycle discharge capacity, cycle performance, and rate performance. Comparative Examples 1-3 show that as the diameter of the binder nanofibers in each of the first, second, and third electrolyte layers increases, the uniformity of the binder improves. When the binder nanofiber diameter is small, the tensile strength of the dry-process electrolyte membrane decreases, but the ionic conductivity increases, the first-cycle discharge capacity and rate performance are improved, but the strength of the dry-process electrolyte membrane decreases, resulting in a decrease in cycle performance. By comparing comparative examples 1-3, it can be seen that when a single-layer electrolyte layer is set, as the binder particle D50 increases, the binder nanofiber diameter increases, the uniformity of the binder decreases, the tensile strength first increases and then decreases, the ionic conductivity decreases, and the comprehensive performance of the lithium-ion battery cannot be improved.

[0124] As shown in Table 1, a comparison of Examples 1, 4, and 5 shows that when only the binder nanofibers are added to the second or third electrolyte layer, the tensile strength of the dry-process electrolyte membrane increases, but the ionic conductivity decreases. This increased overall strength of the electrolyte membrane reduces electrolyte layer cracking caused by cyclical stress due to electrode expansion and contraction, thereby ensuring the battery's cycling performance.

[0125] As shown in Table 1, by comparing Examples 1, 6-7 and Comparative Examples 6-7, it can be seen that, through the preparation process provided by this application, when the D50 of the binder particles and the preparation process are the same, when the binder content is 0.1 wt%, the binder content is too low to form a film. As the binder content increases, the d50 of the binder nanofibers in the obtained electrolyte layer increases. 50 Increased binder content reduces the uniformity of the binder in the electrolyte layer, increasing the tensile strength of the dry electrolyte membrane, but decreasing the ionic conductivity and first-cycle discharge capacity. The cycling performance and rate performance first increase and then decrease. Therefore, by controlling the binder content and thus the binder uniformity within a set range, the dry electrolyte membrane can achieve both cohesion and high ionic conductivity, thereby improving the overall performance of the battery.

[0126] Please refer to Table 1. By comparing Examples 1, 8-11, it can be seen that as the thickness of the second electrolyte layer increases, the diameter d of the binder nanofibers in the second electrolyte layer increases. 50The dry electrolyte membrane has a smaller thickness and higher uniformity, and the tensile strength of the dry electrolyte membrane decreases, the ionic conductivity increases, the first-cycle discharge capacity increases, the cycle performance first decreases slowly and then rapidly, and the rate performance fluctuates within a small range. Therefore, by controlling the thickness ratio of the three electrolyte layers, the cohesion and high ionic conductivity are taken into account to improve the overall performance of the battery. Referring to Table 1, it can be seen from the comparison of Example 1 and Comparative Example 8 that when the second electrolyte layer is not provided, the tensile strength of the electrolyte layer increases and the ionic conductivity decreases, resulting in a decrease in the first-cycle discharge capacity, cycle performance, and rate performance of the battery. Therefore, the second electrolyte layer is provided to coordinate the characteristics of the first electrolyte layer and the third electrolyte layer, optimize the overall mechanical properties and ionic conductivity of the dry electrolyte membrane to improve the overall performance of the battery.

[0127] Comparing Example 1 and Comparative Example 4, it can be seen that when a single-layer electrolyte membrane is provided and under the preparation conditions of this application, when the D50 of the binder particles is large, the diameter of the resulting binder nanofibers is large and the uniformity is low, failing to meet the uniformity requirements for any layer. In this case, the ionic conductivity of the electrolyte membrane drops sharply, and the various battery performances deteriorate. Comparing Comparative Examples 4-5, it can be seen that when a single-layer electrolyte membrane is provided and the D50 of the binder particles is greater than the selection range of this application, under the preparation conditions of this application, the diameter of the binder nanofibers can be reduced, the uniformity is significantly improved, and the battery performance is slightly improved compared to preparation methods outside of this application.

[0128] As shown in Table 1, it can be seen from Comparative Example 1 and Comparative Example 9 that when the uniformity of the second electrolyte layer is less than the set value, the ion path is reduced, the tensile strength of the dry electrolyte membrane increases slightly, but the ionic conductivity decreases seriously, resulting in deterioration of the performance of the lithium-ion battery. Comparative Example 1 and Comparative Example 10 show that when the uniformity of the third electrolyte layer is less than the set value, the tensile strength and ionic conductivity of the dry electrolyte membrane decrease, resulting in deterioration of the performance of the lithium-ion battery. Comparative Example 1 and Comparative Example 11 show that when the uniformity of both the second and third electrolyte layers is less than the set value, the tensile strength of the dry electrolyte membrane increases, but the ionic conductivity decreases seriously, resulting in deterioration of the performance of the lithium-ion battery. Therefore, by controlling the uniformity of the binder in the three electrolyte layers, it is possible to take into account both cohesion and high ionic conductivity and improve the overall performance of the battery.

[0129] Table 2. Some parameters of dry-process electrolyte membranes and battery performance in Examples 1, 12 and Comparative Example 12

[0130]

[0131] As shown in Table 2, it can be seen from Examples 1, 12 and Comparative Example 12 that, under the same preparation process, when the D50 and content of the binder particles are the same, only the molecular weight of the binder is changed. As the molecular weight of the binder increases, the tensile strength of the obtained nanofibers increases, and the ionic conductivity increases, thereby improving the performance of the battery.

[0132] The present invention also provides an electronic device, which includes at least one of the above-mentioned all-solid-state lithium-ion batteries, and the all-solid-state lithium-ion battery is used to provide electrical energy. The electronic device may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, and an electric tool. In one embodiment of the present invention, the vehicle is, for example, a new energy vehicle, which may be a pure electric vehicle, a hybrid electric vehicle, or an extended-range vehicle. The spacecraft includes airplanes, rockets, space shuttles, and spacecrafts, and the electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys. The electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers. The electronic device includes the above-mentioned all-solid-state lithium-ion battery, and therefore includes the advantages of the above-mentioned all-solid-state lithium-ion battery, which will not be elaborated on here.

[0133] In summary, the present invention provides a dry-process electrolyte membrane, its preparation method, and its application. By providing three electrolyte layers and controlling the uniformity of the binder across the three layers, the dry-process electrolyte membrane achieves both cohesive strength and high ionic conductivity. This prevents cyclical stress caused by electrode expansion and contraction from causing electrolyte layer rupture and battery short circuits, thereby improving battery safety. Controlling the diameter of the binder nanofibers while maintaining uniformity prevents localized fiber thickness from hindering ion transport and localized mechanical strength from being insufficient due to cyclical stress caused by electrode expansion and contraction. This prevents cyclical stress from causing electrode expansion and contraction to cause rupture and battery short circuits, thereby improving battery safety. The nanofiber diameter of the second electrolyte layer is smaller than that of the first and third electrolyte layers, bridging the first and third electrolyte layers and increasing ion pathways to enhance the ionic conductivity of the dry-process electrolyte membrane, thereby improving the battery's rate capability. By controlling the thickness ratio of the three electrolyte layers and the nanofiber diameters in the first and second electrolyte layers, dry-process electrolyte membrane rupture can be reduced while achieving high ionic conductivity. By regulating the parameters in the preparation of dry electrolyte membranes, the uniformity of the binder in each electrolyte layer can be maximized, and the nanofibers can be distributed more evenly, thereby preparing a dry electrolyte membrane with better performance, thereby improving battery performance.

[0134] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept, such as the technical solutions formed by the mutual replacement of the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this application.

[0135] Except for the technical features described in the specification, the remaining technical features are known technologies to those skilled in the art. In order to highlight the innovative features of the present invention, the remaining technical features will not be described here in detail.

Claims

1. A dry electrolyte membrane, characterized in that: The invention comprises a first electrolyte layer, a second electrolyte layer and a third electrolyte layer stacked in sequence, wherein each electrolyte layer comprises a solid electrolyte and a binder; The first electrolyte layer includes a first binder, and the uniformity of the first binder in the first electrolyte layer is 96%-98%; the uniformity is the degree of dispersion of the binder in multiple detection areas of the electrolyte layer, and the dispersion degree is negatively correlated with the uniformity; The second electrolyte layer includes a second binder, and the uniformity of the second binder in the second electrolyte layer is 98%-99%; The third electrolyte layer includes a third binder, and the uniformity of the third binder in the third electrolyte layer is 94%-96%; The binder exists in the electrolyte layer in the form of nanofibers, and the diameter of the nanofibers of the second electrolyte layer is smaller than the diameter of the nanofibers of the first electrolyte layer and the third electrolyte layer; In the first electrolyte layer, the diameter d of the nanofibers of the first binder is 50 4nm-10nm; In the second electrolyte layer, the diameter d of the nanofibers of the second binder is 50 1nm-4nm; In the third electrolyte layer, the diameter d of the nanofibers of the third binder is 50 10nm-20nm; In each electrolyte layer, the nanofibers each satisfy d 90 / d 10 ≤1.5; The dry electrolyte membrane is obtained by the following preparation method: Sieving binder particles with a preset median particle size to obtain a first binder, a second binder, and a third binder; mixing the solid electrolyte with the first binder, the second binder, and the third binder respectively to obtain a first mixed material, a second mixed material, and a third mixed material; respectively subjecting the first mixed material, the second mixed material and the third mixed material to fiberization to obtain a first fibrillated material, a second fibrillated material and a third fibrillated material; Cooling the first fibrillated material, the second fibrillated material, and the third fibrillated material to a target temperature at a preset rate while applying shear to obtain a first intermediate product, a second intermediate product, and a third intermediate product; The first intermediate product, the second intermediate product and the third intermediate product are crushed and granulated to obtain a first electrolyte material, a second electrolyte material and a third electrolyte material respectively; The first electrolyte material, the second electrolyte material and the third electrolyte material are respectively formed into films to a set thickness by multi-roll continuous rolling to obtain a first intermediate layer, a second intermediate layer and a third intermediate layer; The first intermediate layer, the second intermediate layer and the third intermediate layer are stacked in sequence and rolled into a film by multi-roll continuous rolling to obtain a dry electrolyte membrane.

2. The dry-process electrolyte membrane according to claim 1, characterized in that The first binder, the second binder and the third binder are each selected from one or more combinations of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, ethylene-vinyl acetate copolymer, polypropylene, polyethylene, ethylene-octene copolymer or polyimide; And / or, the solid electrolyte is selected from at least one of an oxide solid electrolyte, a sulfide solid electrolyte and a halide solid electrolyte.

3. The dry-process electrolyte membrane according to claim 1, characterized in that In each electrolyte layer, the content of each binder is 0.2 wt % to 1 wt %, and the content ratio of the first binder, the second binder, and the third binder is 1:(0.8-1.2):(0.8-1.2).

4. The dry-process electrolyte membrane according to claim 1, characterized in that The thickness of the dry electrolyte membrane is 10 μm-30 μm; and the thickness ratio of the first electrolyte layer, the second electrolyte layer, and the third electrolyte layer is 1:(2-6):(1.2-1.4).

5. The dry-process electrolyte membrane according to claim 1, characterized in that The preset median particle size of the first binder particles is 20 μm-50 μm, the preset median particle size of the second binder particles is 5 μm-20 μm, and the preset median particle size of the third binder particles is 50 μm-100 μm.

6. The dry-process electrolyte membrane according to claim 1, characterized in that Sieving the binder particles at a preset temperature, wherein the preset temperature is 5° C.-20° C.; The fiberization treatment includes a first stage, a second stage, and a third stage. In the first stage, the treatment temperature is 20°C-40°C, the stirring linear speed is 20m / s-30m / s, and the stirring time is 10min-30min; in the second stage, the treatment temperature is 60°C-80°C, the stirring linear speed is 40m / s-60m / s, and the stirring time is 10min-30min; in the third stage, the treatment temperature is 90°C-120°C, the stirring linear speed is 60m / s-70m / s, and the stirring time is 60min-120min; The preset rate is 10°C / min-15°C / min, and the target temperature is 25°C-40°C; During the cooling process, pulse shearing is applied, wherein one pulse shearing comprises shearing at 8 m / s-10 m / s for 4 s-6 s and shearing at 3 m / s-5 m / s for 8 s-12 s.

7. An all-solid-state lithium-ion battery, characterized in that: include: Positive electrode; A negative electrode plate, the negative electrode plate comprising a negative electrode active material, the negative electrode active material comprising a silicon material, and the silicon material comprising silicon, silicon carbon and silicon oxygen negative electrode materials; The solid electrolyte layer is arranged between the positive electrode plate and the negative electrode plate, and is selected from the dry electrolyte membrane according to any one of claims 1 to 6, and the first electrolyte layer in the dry electrolyte membrane is arranged close to the positive electrode plate.

8. An electronic device, characterized in that: Including the all-solid-state lithium-ion battery according to claim 7.

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