Solid-state secondary battery and preparation method thereof, energy storage system and electric equipment

Abstract

The invention relates to the field of batteries, and provides a solid-state secondary battery and a preparation method thereof, an energy storage system and electric equipment, and the preparation method comprises the following steps: preparing ceramic aerosol which comprises inorganic ceramic oxide particles and polyimide particles; providing a base material layer, and spraying the ceramic aerosol to at least one side of the base material layer; the base material layer is subjected to heat treatment, the polyimide particles are removed, the remaining inorganic ceramic oxide particles are converted into a plurality of branches, gaps are formed between the adjacent branches, and the branches are located on at least one side of the base material layer; coating one side of the base material layer with coating slurry, wherein the coating slurry also flows into the gap; drying treatment is carried out, the coating slurry is converted into an active layer, and the base material layer and the branches jointly form a solid electrolyte; at least one of the preparation steps of the positive plate and the negative plate comprises the following steps: providing a current collector, and positioning the active layer between the current collector and the base material layer; and packaging to obtain the solid-state secondary battery.

Description

[0001] This application is a divisional application of the patent application filed on June 17, 2025, application number: 202510813543.3, entitled "Solid-state secondary battery and its preparation method, energy storage system and electrical equipment". Technical Field

[0002] This application relates to the field of batteries, and in particular to a solid-state secondary battery and its preparation method, energy storage system and electrical equipment. Background Technology

[0003] Lithium-ion batteries are currently the main chemical power source system for various applications such as power and energy storage. They have obvious advantages in terms of specific energy, service life, and cost-effectiveness. However, the contradiction between specific energy and safety, as well as the constraints of lithium resources, have triggered a wave of research and development of various new types of rechargeable batteries. Among them, solid-state lithium batteries and sodium batteries have become the most powerful competitors of lithium-ion batteries.

[0004] Solid-state electrolytes can fundamentally improve the safety of rechargeable batteries and effectively enhance their energy density. Electrode materials, on the other hand, need to meet the requirements of multi-faceted matching with electrolyte materials in terms of chemical, mechanical, thermal, and electrochemical processes. Through modification of electrode active materials, electrolytes, and interfaces, battery performance can be improved and optimized. However, current solid-state rechargeable batteries also have some problems in application, such as poor solid-solid interface contact between the electrolyte and active materials, affecting characteristics such as battery internal resistance. Summary of the Invention

[0005] This application provides a solid-state secondary battery and its preparation method, energy storage system and electrical equipment, which at least helps to improve the problem of poor solid-solid interface contact between electrolyte and active material in solid-state secondary batteries.

[0006] According to some embodiments of this application, one aspect of this application provides a method for preparing a solid-state secondary battery, comprising: forming a solid electrolyte, including: obtaining a metal precursor, including: mixing a lithium metal compound, a lanthanum metal compound, and a zirconium metal compound to obtain a metal precursor; providing a substrate layer, depositing the metal precursor on the substrate layer; using argon as a carrier gas and oxygen as a reactant gas to obtain a prepolymer of surface-grown array pillars, wherein the array pillars have gaps between them; preparing a first coating slurry; coating the first coating slurry on one side of the substrate layer containing the prepolymer, and the coating slurry also flowing into the gaps between the array pillars; performing a drying treatment, wherein the first coating slurry is converted into an active layer, and the substrate layer and the array pillars together constitute the solid electrolyte; preparing a positive electrode and a negative electrode, wherein the preparation steps of at least one of the positive electrode and the negative electrode include: providing a current collector, wherein the active layer is located between the current collector and the substrate layer; sequentially stacking the negative electrode, the solid electrolyte, and the positive electrode, hot-pressing them to obtain a bare cell, placing the bare cell into a battery case, and then encapsulating it to obtain a solid-state secondary battery.

[0007] In some embodiments, the array columns have holes, and the coating slurry also flows into the holes.

[0008] In some embodiments, the molar ratio of the lithium metal compound, the lanthanum metal compound, and the zirconium metal compound is (10-11):(2.5-3.5):(1.5-2.5).

[0009] In some embodiments, the process step of depositing the metal precursor on the substrate layer includes: setting a baffle with an array of holes on the surface of the substrate layer, evaporating the premixed metal precursor using a laser, and depositing the metal precursor; wherein the deposition temperature is 700°C to 800°C, and the deposition chamber pressure is 1 kPa to 1.5 kPa.

[0010] In some embodiments, the process steps for forming the first coating slurry include: stirring the active material, nano-inorganic ceramic oxide particles, conductive agent, binder and dispersion solution evenly to obtain a second mixed solution; dispersing the second mixed solution at high speed under negative pressure for 4h to 6h to obtain the coating slurry, wherein the viscosity range of the coating slurry is 5000mPa·s to 20000mPa·s; wherein the ratio of the active material, nano-inorganic ceramic oxide particles, conductive agent and binder is (73wt% to 93wt%): (5wt% to 18wt%): (0.6wt% to 4.5wt%): (1.4wt% to 4.5wt%).

[0011] In some embodiments, the first coating slurry includes an active material, wherein the active material is graphite; after forming the solid electrolyte, the method further includes: stirring lithium bis(fluorosulfonyl)imide, poly(ethylene glycol) methacrylate, polyethylene glycol dimethacrylate, photoinitiator, graphite, and conductive carbon black evenly to obtain a curing liquid; immersing the solid electrolyte in the curing liquid to perform a curing treatment on the solid electrolyte having the curing liquid; wherein the mass ratio of lithium bis(fluorosulfonyl)imide: poly(ethylene glycol) methacrylate: polyethylene glycol dimethacrylate: photoinitiator: graphite: conductive carbon black is (35wt%~55wt%): (30wt%~50wt%): (1wt%~7.5wt%): (1.5wt%~4.5wt%): (2wt%~7wt%): (1wt%~3wt%).

[0012] In some embodiments, the current collector is a positive current collector, and the process steps for preparing the positive electrode sheet include: providing a positive current collector located on the surface of the active layer, performing hot pressing treatment on the solid electrolyte and the positive current collector, and the active layer and the positive current collector constituting the positive electrode sheet.

[0013] According to some embodiments of this application, another aspect of this application provides a solid-state secondary battery, comprising: a battery casing having a cavity; a bare cell located within the cavity; the bare cell comprising a stacked positive electrode, a solid electrolyte, and a negative electrode, wherein the solid electrolyte comprises: a substrate layer and a plurality of array pillars, with gaps between adjacent array pillars, the array pillars being located on at least one side of the substrate layer; an active layer located on the surface of the substrate layer and within the gaps; the active layer being located between the substrate layer and the positive current collector, and / or, the active layer being located between the substrate layer and the negative current collector.

[0014] In some embodiments, the array pillars have pores, and a portion of the active layer is embedded within the pores.

[0015] In some embodiments, the active layer comprises an active material coated with Ga-LLZO.

[0016] According to some embodiments of this application, another aspect of this application provides an energy storage system, including: a secondary battery prepared by the method for preparing a solid-state secondary battery as described in any of the above embodiments, or a solid-state secondary battery as described in the above embodiments.

[0017] According to some embodiments of this application, another aspect of this application provides an electrical device, including: a solid-state secondary battery prepared by the method for preparing a secondary battery as described in any of the above embodiments, a solid-state secondary battery as described in the above embodiments, or an energy storage system as described in the above embodiments.

[0018] The technical solution provided in this application has at least the following advantages:

[0019] The solid-state secondary battery provided in this application embodiment can form a solid dielectric layer containing array pillars, thereby combining vertical ion channels, three-dimensional electron networks and multi-level stress buffering mechanisms to achieve synergistic optimization of high energy density, low impedance and long cycle life.

[0020] This application embodiment creates a large three-dimensional space by forming array pillars with gaps between them. The first coating slurry (i.e., the electrode active material) can fully fill these gaps, thus effectively adding more active layers per unit area of ​​substrate, thereby increasing the volumetric energy density and gravimetric energy density, resulting in a longer lifespan, i.e., a longer cycle time. In energy storage products, it can provide long-term energy storage capabilities of 4 hours or even 8 hours. Secondly, the three-dimensional interlocking structure of LFP and LLZO has good stability and can remain stable during multiple cycles, exhibiting excellent cycle life and long-term energy storage. Attached Figure Description

[0021] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the drawings in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A flowchart corresponding to a method for preparing a solid-state secondary battery according to an embodiment of this application;

[0023] Figure 2 This is a schematic diagram of a first structure of a solid-state secondary battery provided in an embodiment of this application;

[0024] Figure 3 A top view of a solid electrolyte in a solid-state secondary battery provided in an embodiment of this application;

[0025] Figure 4This is a schematic diagram of a second structure of a solid-state secondary battery provided in an embodiment of this application;

[0026] Figure 5 This is a schematic diagram of a third structure of a solid-state secondary battery provided in one embodiment of this application;

[0027] Figure 6 This is a schematic diagram of a fourth structure of a solid-state secondary battery provided in one embodiment of this application;

[0028] Figure 7 This is a schematic diagram of a fifth structure of a solid-state secondary battery provided in an embodiment of this application;

[0029] Figure 8 This is a schematic diagram of a sixth structure of a solid-state secondary battery provided in an embodiment of this application;

[0030] Figure 9 This is a schematic diagram of a seventh structure of a solid-state secondary battery provided in an embodiment of this application;

[0031] Figure 10 This is a schematic diagram of an eighth structure of a solid-state secondary battery provided in an embodiment of this application;

[0032] Figure 11 This is a schematic diagram of a ninth structure of a solid-state secondary battery provided in an embodiment of this application;

[0033] Figure 12 This is a schematic diagram of the tenth structure of a solid-state secondary battery provided in an embodiment of this application;

[0034] Figure 13 This is a schematic diagram of the eleventh structure of a solid-state secondary battery provided in an embodiment of this application.

[0035] Explanation of reference numerals in the attached figures: 1. Positive electrode; 2. Negative electrode; 110. Branch; 100. Substrate layer; 101. Active layer; 102. Secondary spherical aggregate; 103. Ga-LLZO coated active material; 104. PEG-based polymer network; 105. Graphite / carbon black conductive path;

[0036] 210, Array pillars; 200, Substrate layer; 201, Active layer; 202, Secondary spherical aggregates; 203, Ga-LLZO coated active material; 204, PEG-based polymer network; 205, Graphite / carbon black conductive pathway;

[0037] 300, Substrate layer; 301, Active layer; 302, Secondary spherical aggregate; 303, Ga-LLZO coated active material; 304, PEG-based polymer network; 305, Graphite / carbon black conductive pathway. Detailed Implementation

[0038] As can be seen from the background technology, current solid-state secondary batteries suffer from problems such as poor solid-solid interface contact between the electrolyte and the active material, which affects the battery's internal resistance and other characteristics.

[0039] The solid-state secondary battery provided in this application involves preparing a solid electrolyte with multiple branches on its surface. These branches are located between the positive electrode and the substrate layer, and / or between the negative electrode and the substrate layer. This allows the positive active layer of the positive electrode to interlock with and be intercalated with the solid electrolyte, and the negative active layer of the negative electrode to interlock with and be intercalated with the solid electrolyte, thereby increasing the contact area and reducing the battery's internal resistance. Furthermore, an aerosol process is used to form the branches on the surface of the substrate layer, followed by the formation of the active layer within the gaps between the branches. The active layer serves not only as the positive / negative active layer but also as a contact enhancement layer, improving contact performance. In the subsequent rolling process, this ensures a tight interfacial contact between the solid electrolyte layer and the positive and negative electrodes.

[0040] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0041] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0042] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0043] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple groups" refers to two or more (including two groups), and "multiple pieces" refers to two or more (including two pieces).

[0044] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0045] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0046] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0047] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or it can have another component present in between. Moreover, when a component such as a layer, film, region, or plate is "directly located" on another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it indicates that no other components are located in between.

[0048] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "part" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0049] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0050] According to some embodiments of this application, one aspect of this application provides a method for preparing a solid-state secondary battery to improve problems such as poor solid-solid interface contact between the electrolyte and the active material, which affects the battery's internal resistance and other characteristics.

[0051] Figure 1 A flowchart corresponding to a method for preparing a solid-state secondary battery according to an embodiment of this application; Figure 2 This is a schematic diagram of a first structure of a solid-state secondary battery provided in an embodiment of this application; Figure 3 This is a top view of a solid electrolyte in a solid-state secondary battery provided in an embodiment of this application.

[0052] It should be noted that, Figure 2 Looking from the top cover towards the casing, one can see the sides of the positive electrode, negative electrode, and solid electrolyte, thus clearly seeing the relationship between the three. Figure 2 The diagram illustrates the case where the active layer is a positive electrode active layer and a negative electrode active layer. Those skilled in the art can, according to their needs, only set one side of the substrate layer to have branches and an active layer. Figure 3 The active layer in the image is a perspective view to show the arrangement of the branches and the substrate layer.

[0053] refer to Figures 1-3The preparation method includes: forming a solid electrolyte, which includes: preparing a ceramic aerosol, the ceramic aerosol comprising inorganic ceramic oxide particles and polyimide particles; providing a substrate layer 100 and spraying the ceramic aerosol onto at least one side of the substrate layer 100; heat-treating the substrate layer 100 to remove the polyimide particles, the remaining inorganic ceramic oxide particles being converted into a plurality of branches 110, with gaps between adjacent branches 110, the branches 110 being located on at least one side of the substrate layer 100; preparing a coating slurry; and applying the coating slurry... The coating is applied to one side of the substrate layer 100, and the coating slurry also flows into the gaps; after drying, the coating slurry is transformed into an active layer 101, and the substrate layer 100 and the branches 110 together constitute a solid electrolyte; a positive electrode 1 and a negative electrode 2 are prepared, and the preparation steps of at least one of the positive electrode 1 and the negative electrode 2 include: providing a current collector, with the active layer 101 located between the current collector and the substrate layer 100; stacking the negative electrode 2, the solid electrolyte and the positive electrode 1 in sequence and hot-pressing them to obtain a bare cell; placing the bare cell into a battery case and then encapsulating it to obtain a solid secondary battery.

[0054] The solid-state secondary battery provided in this application embodiment utilizes a solid electrolyte with multiple branches 110 on its surface. These branches 110 are located between the positive current collector and the substrate layer 100, and / or between the negative current collector and the substrate layer 100. This allows the positive active layer of the positive electrode 1 and the solid electrolyte to be interleaved and interlocked, and the negative active layer of the negative electrode 2 and the solid electrolyte to be interleaved and interlocked, thereby increasing the contact area and reducing the battery's internal resistance. Furthermore, the branches 110 are formed using an aerosol process, creating branches 110 on the surface of the substrate layer 100. Subsequently, an active layer 101 is formed, positioned within the gaps between the branches 110. The active layer 101 serves not only as the positive / negative active layer but also as a contact enhancement layer, improving contact performance and ensuring a tight interfacial contact between the solid electrolyte layer and the positive and negative electrodes 1 and 2 during the subsequent rolling process.

[0055] The preparation method described above will be explained in detail below.

[0056] According to their shape, the prepared solid-state secondary batteries can be classified into square cells, round cells, or pouch cells. According to their capacity, secondary batteries can be classified into models such as 50Ah, 100Ah, 150Ah, 200Ah, 280Ah, 306Ah, 314Ah, 500+Ah, 800+Ah, and 1000+Ah. According to the chemical composition and working principle of the bare cells, secondary batteries can be lithium-ion batteries, lead-acid batteries, sodium-ion batteries, or nickel-metal hydride batteries. This application uses a lithium-ion battery preparation method as an example. Those skilled in the art can replace the lithium ions in the positive electrode, negative electrode, and electrolyte with corresponding metal ions according to actual needs. For example, in a sodium-ion battery, the lithium transition metal oxide of the subsequent positive electrode active material can be replaced with any of the following: layered metal oxides (e.g., NaFeO2), polyanionic compounds (NaFePO4), and Prussian blue compound systems (e.g., NaMnFe(CN)6-zH2O).

[0057] Solid-state electrolytes (SSEs) are solid ionic conductors and electronic insulators, and are a key characteristic component of solid-state rechargeable batteries. Compared to liquid electrolytes, solid-state electrolytes are safer, do not have the problem of toxic organic solvent leakage, are non-flammable, non-volatile, have good mechanical and thermal stability, are easy to process, have low self-discharge, and can achieve higher power densities and cycle life. For example, because solid-state electrolyte membranes have the property of suppressing lithium dendrite formation, lithium metal anodes can be used in practical devices without the inherent limitations of liquid electrolytes. Using high-capacity anodes and low reduction potentials can lead to lighter, thinner, and cheaper rechargeable batteries.

[0058] Solid electrolytes include all-solid-state electrolytes and quasi-solid-state electrolytes (QSSE). All-solid-state electrolytes are further divided into inorganic solid electrolytes (ISE), solid polymer electrolytes (SPE), and composite polymer electrolytes (CPE). QSSE, also known as gel polymer electrolyte (GPE), is a self-contained membrane containing a certain amount of liquid component fixed within a solid matrix. The ion conduction mechanisms of SPE and GPE are quite different: SPE conducts ions through interactions with substituents in the polymer chains, while GPE mainly conducts ions in the solvent or plasticizer.

[0059] Solid electrolytes mainly consist of the following components: lithium salt, which serves as the ion source and is selected from lithium fluoride, lithium sulfide, or lithium phosphate; a matrix, which provides mechanical support and forms ion transport channels, and is a polymer matrix, which is a copolymer composed of one or more combinations of polyoxyethylene, polyvinylidene fluoride, polyacrylonitrile, and polyurethane; and inorganic fillers, which enhance the mechanical properties of the electrolyte and improve its ionic conductivity, and are selected from lithium oxide, lithium titanate, and phosphate. The electrolyte is a copolymer composed of one or more of lithium, alumina, and silicon oxide, with the inorganic filler being a nano-sized filler having a particle size of 1 nm to 100 nm; rare earth elements are used to improve the lithium-ion conductivity of the solid electrolyte, and the rare earth elements are copolymers composed of one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, erbium, lutetium, and yttrium; ceramic materials are used to enhance the toughness of the electrolyte, and the ceramic materials are one of zirconium oxide, silicon nitride, silicon dioxide, titanium disulfide, and lithium sulfide.

[0060] The preparation steps for the solid electrolyte include: mixing inorganic ceramic oxide particles with polyimide particles to obtain mixed particles. The inorganic ceramic oxide particles are a mixture of lithium salt, inorganic filler, rare earth elements, and ceramic materials. The polyimide particles form the interstitial structure in the subsequently formed branches 110. During high-temperature curing, the polyimide particles undergo an imidization reaction, releasing small molecules (such as water), leading to volume shrinkage. During the shrinkage process, the rigidity of the molecular chains hinders the uniform densification of the inorganic ceramic oxide particles. Local stress concentration causes wrinkles or protrusions at the edges of the pores formed by the sublimation of the polyimide particles, resulting in the formation of irregular array columns, i.e., branches 110.

[0061] In some embodiments, inorganic ceramic oxide particles may include LLTO (lithium lanthanum titanate / lithium lanthanum titanate, Li 0.33 La 0.56 TiO3), LLZTO (lithium lanthanum zirconium oxide / lithium lanthanum zirconate, Li7La3Zr2O) 12 Or LiTFSI (bis(trifluoromethanesulfonyl)imide, C2F6LiNO4S2), the representative material of NASICON (sodium superionic conductor) type solid electrolyte is LATP (lithium aluminum titanium phosphate, Li 1.3 Al 0.3 Ti 1.7 (PO4)3).

[0062] In some embodiments, in the step of preparing ceramic aerosol, the volume ratio of inorganic ceramic oxide particles to polyimide particles is 1:(1-10).

[0063] By preparing the mixed particles into ceramic aerosols, the sintering temperature for subsequent preparation of solid electrolytes can be reduced, thereby lowering the preparation cost; and the prepared solid electrolytes have uniform composition and smooth interfaces.

[0064] Specifically, nitrogen (or helium or oxygen, etc.) is used as the carrier gas, and the mixed particles are introduced into the aerosol chamber through a gas delivery device to disperse the mixed particles evenly in the aerosol chamber and form a ceramic aerosol.

[0065] A ceramic aerosol is sprayed onto a substrate layer 100 to form a prepolymer layer. Specifically, an LLZTO solid electrolyte sheet is used as the substrate layer 100. The deposition chamber pressure is set to 8 Pa to 12 Pa, the nozzle distance from the substrate layer surface is 9 mm to 11 mm, and the spray angle is 85° to 95°. The aerosol is sprayed onto the surface of the substrate layer 100 through the nozzle using a carrier gas with a flow rate of 20 L / min to 22 L / min and a deposition time of 1 h to 2 h. A solid electrolyte sheet with deposited mixed particles, i.e., the prepolymer layer, is obtained.

[0066] The mechanism of prepolymer layer formation via aerosol is as follows: The entire process can be divided into two stages. In the initial stage of deposition, the collision of the first batch of original micro / nanoparticles with the substrate rapidly forms an anchoring layer on the substrate surface. However, damage at the interface between the deposited film and the substrate increases the roughness of the contact surface. After the initial anchoring layer is formed, the growth of the deposited film slows down by reducing the carrier gas flow rate. Then, in the second stage, the particles deposited on the anchoring layer gradually smooth and densify the surface. Through countless repeated combinations of the original particles' continuous breakage, deformation, and collision, a dense deposited film (i.e., the prepolymer layer) is formed. This film formation phenomenon is also known as the room-temperature collision bonding principle.

[0067] It should be noted that LLZTO solid electrolyte sheet can be understood as a conventional solid electrolyte sheet, and the embodiments in this application are a further optimization of conventional solid electrolyte sheets.

[0068] The heat treatment step may include: placing the substrate layer 100 containing the prepolymer layer in a high-temperature reactor and calcining it at 900°C for 1 to 3 hours to remove the polyimide particles, while simultaneously fusing the inorganic ceramic oxide particles to form a substrate layer with branches 110.

[0069] The underlying mechanism is that inorganic ceramic oxide particles and polyimide (PI) particles differ significantly in density, particle size distribution, and surface energy. Polyimide particles typically exhibit thermal decomposition characteristics and act as sacrificial templates, while inorganic ceramic oxide particles demonstrate higher structural stability. When ceramic aerosol is deposited by high-speed spraying, the particles generate a "splashing effect" due to inertial impact on the substrate layer 100. Large particles are preferentially deposited, forming local accumulation. Small particles are filled by airflow disturbance, but are hindered by the elasticity of PI particles, forming a "micro-arch bridge" structure, resulting in an initial uneven morphology on the surface of the prepolymer layer. Furthermore, when PI particles are heat-treated at 300℃ to 500℃, they undergo stepwise decomposition (releasing gases such as carbon dioxide and formaldehyde). The decomposition kinetics compete with the sintering behavior of ceramic particles. The gases produced by PI decomposition escape along the gaps between ceramic particles, forming "dendritic channels" in the ceramic skeleton. Ceramic particles undergo surface sintering (neck growth) at high temperatures, while the volume of the PI decomposition area collapses. The difference in shrinkage rates between the two (ceramic shrinkage rate is about 3% to 5%, while the PI decomposition area is >20%) causes tensile stress concentration at the interface, forcing the edge of the pore wall to warp upwards, forming protrusions, i.e., branches 110.

[0070] In some embodiments, the process parameters for heat treatment include: a reaction temperature of 500℃ to 1000℃, a calcination time of 0.8h to 1.2h, and a purging gas purging rate of 0.5L / min to 3L / min.

[0071] The active material, conductive agent, binder and dispersion solution are stirred evenly to obtain a coating slurry; the coating slurry is applied to one side of the substrate layer 100, wherein the coating slurry flows into the gaps between some branches 110 and is dried, the coating slurry is transformed into an active layer 101, and the substrate layer 100 and the branches 110 together constitute a solid electrolyte.

[0072] In some embodiments, if the active layer is located between the positive electrode current collector and the substrate layer, the active material is a positive electrode active material; if the active layer is located between the negative electrode current collector and the substrate layer, the active material is a negative electrode active material. An example is given where the active layer is the positive electrode active material, and the positive electrode active material is LFP (lithium iron phosphate). Reference Figure 2 LFP, carbon black, and PVDF were mixed in a ratio of (92wt%–98wt%):(0.6wt%–4wt%):(1.4wt%–4wt%), and then NMP was added to bring the solid content of the slurry to 50%. The mixture was stirred under negative pressure for 3 hours to obtain the LFP slurry. Using a solid electrolyte layer as the substrate layer 100, the LFP slurry was coated with a doctor blade, and ultrasonicated for 5 minutes to promote the wetting of the slurry between the branches 110. The process of coating-ultrasonication-drying was repeated three times to obtain an irregularly protruding, interlocking structure, i.e., the substrate layer 100 with branches 110.

[0073] In some embodiments, the branch 110 has pores into which the coating slurry flows; and after drying, a portion of the active layer 101 is embedded within the pores. Thus, the coating slurry is located between the pores, which can improve the adhesion between the active layer 101 and the solid electrolyte, and the active layer 101 being located within the pores can also improve conductivity.

[0074] In some embodiments, the dispersion solution includes a wetting aid used to allow the coating slurry to flow into the pores. Thus, the wetting aid can improve the wettability of the coating slurry to the solid electrolyte, thereby increasing the contact area between the coating slurry and the solid electrolyte, and thus improving the interfacial contact performance between the solid electrolyte and the active layer 101.

[0075] In some embodiments, prior to the drying process, an ultrasonic treatment is further included, wherein the ultrasonic treatment is used to fill the pores of the coating slurry; the ultrasonic treatment time is 3 min to 15 min; and the ultrasonic frequency is 20 kHz to 5 MHz. This improves the contact performance between the active layer 101 and the solid electrolyte.

[0076] Figure 4 This is a schematic diagram of a second structure of a solid-state secondary battery provided in an embodiment of this application. Figure 4 This diagram only shows a portion of the solid electrolyte layer; the arrangement of the positive and negative electrodes can be referenced elsewhere. Figure 2 The following partial cross-sectional view can also be used as a reference. Figure 2 .

[0077] In some embodiments, reference Figure 4 The process steps for forming the coating slurry include: stirring the active material, nano-inorganic ceramic oxide particles, conductive agent, binder and dispersion solution evenly to obtain a second mixed solution; dispersing the second mixed solution at high speed under negative pressure for 4h to 6h to obtain the coating slurry, the viscosity range of the coating slurry being 5000mPa·s to 20000mPa·s; wherein, the mass ratio of the active material, nano-inorganic ceramic oxide particles, conductive agent and binder is (73wt% to 93wt%): (5wt% to 18wt%): (0.6wt% to 4.5wt%): (1.4wt% to 4.5wt%).

[0078] The average particle size of the second mixed solution composed of active materials, nano-inorganic ceramic oxide particles, conductive agents, and binders in the coating slurry is less than 20 μm.

[0079] Using LFP as the positive electrode active material as an example, LFP, nano-LLZO (lithium lanthanum zirconium oxide) particles, carbon black, and PVDF were mixed in a ratio of (73wt%–93wt%): (5wt%–18wt%): (0.6wt%–4.5wt%): (1.4wt%–4.5wt%). NMP was then added to achieve a solid content of 60% in the slurry. The mixture was then dispersed at high speed under negative pressure for 5 hours to obtain a mixed slurry with a viscosity range of 5000 mPa·s to 20000 mPa·s and a fineness of less than 20 μm. The mixed slurry was pumped into a buffer tank and then fed into a coating die via a conveyor pipe. The slurry was coated onto an LLZO solid electrolyte sheet at a coating speed of 5 m / min. The coated sheet was then transported via a conveyor belt into a multi-section drying oven with a temperature range of 80℃–130℃. After the slurry dries, due to the self-aggregation tendency of nano-LLZO particles in the slurry, the LLZO particles in the coating layer are transformed into secondary spherical aggregates 102.

[0080] The mechanism is as follows: High-speed dispersion under negative pressure for 5 hours breaks down the hard aggregates of LLZO nanoparticles through shear force, resulting in temporary uniform dispersion. During this time, the PVDF molecular chains fully extend in the NMP solvent, partially adsorbing onto the particle surface to form a steric hindrance layer, delaying re-agglomeration. The slurry's solid content reaches 60% or even higher, indicating high viscosity. This high-viscosity environment restricts the free movement of particles but also exacerbates the "crowding effect" between particles, causing LLZO particles to pre-agglomerate in localized areas due to physical compression. In the subsequent drying step, the LLZO nanoparticles, with their high surface energy, tend to reduce the total surface area and lower the system's free energy after solvent evaporation by agglomerating, thus forming secondary spherical aggregates 102.

[0081] Figure 5 This is a schematic diagram of a third structure of a solid-state secondary battery provided in an embodiment of this application.

[0082] refer to Figure 5 The coating slurry includes an active material, the surface of which is coated with Ga-LLZO. The process steps for forming the active material include: stirring Ga-LLZO particles, active particles and solution evenly to form a first mixed solution; drying the first mixed solution to form a first precursor; calcining the first precursor to form the Ga-LLZO-coated active material; wherein the mass ratio of Ga-LLZO particles to active particles is (0.5wt% to 2wt%): (8wt% to 9.5wt%).

[0083] It should be noted that if the active material is a positive electrode active material, the active material can be a lithium source material; if the active material is a negative electrode active material, the active material can be graphite.

[0084] Taking LFP as an example of active material, nano-Ga-LLZO particles and LFP were added to NMP solvent at a ratio of (0.5wt%–2wt%):(8wt%–9.5wt%), mixed evenly, dried to remove NMP, and then calcined at 700℃ for 30–60 min to form a Ga-LLZO-coated LFP structure. The Ga-LLZO-coated LFP structure, carbon black, and PVDF were mixed at a ratio of (92wt%–98wt%):(0.6wt%–4wt%):(1.4wt%–4wt%), and then NMP was added to achieve a solid content of 60%. The mixture was stirred under negative pressure for 3–5 h to obtain an LFP slurry. Using an LLZO solid electrolyte sheet as a substrate layer, the LFP slurry was extruded and coated, and after drying, a surface-coated interlocking structure was obtained. The surface-coated structure was Ga-LLZO-coated active material 103.

[0085] Figure 6 This is a schematic diagram of a fourth structure of a solid-state secondary battery provided in an embodiment of this application.

[0086] In some embodiments, reference Figure 6 The coating slurry includes an active material, which is graphite. After forming the solid electrolyte, the slurry further includes: stirring lithium bis(fluorosulfonyl)imide, poly(ethylene glycol) methacrylate, polyethylene glycol dimethacrylate, a photoinitiator, graphite, and conductive carbon black evenly to obtain a curing solution; immersing the solid electrolyte in the curing solution to cure the solid electrolyte containing the curing solution; wherein the mass ratio of lithium bis(fluorosulfonyl)imide: poly(ethylene glycol) methacrylate: polyethylene glycol dimethacrylate: photoinitiator: graphite: conductive carbon black is (35wt%~55wt%): (30wt%~50wt%): (1wt%~7.5wt%): (1.5wt%~4.5wt%): (2wt%~7wt%): (1wt%~3wt%).

[0087] In pure water, graphite, carbon black, CMC, and SBR are mixed in a ratio of (92wt%–96wt%):(1wt%–3wt%):(0.5wt%–2.5wt%):(1.5wt%–3.5wt%) to achieve a solid content of 50%. The mixture is stirred under negative pressure for 3 hours to obtain a graphite slurry. Using an LLZO solid electrolyte sheet as the substrate layer, the graphite slurry is extruded and coated, and after drying, a graphite-coated solid electrolyte sheet is obtained. The solid electrolyte sheet is then immersed in a curing solution and allowed to stand for 30–60 minutes. In the curing solution, the mass ratio of lithium bis(fluorosulfonyl)imide salt: poly(ethylene glycol) methacrylate: polyethylene glycol dimethacrylate: photoinitiator: graphite: conductive carbon black is (35wt%–55wt%): (30wt%–50wt%): (1wt%–7.5wt%): (1.5wt%–4.5wt%): (2wt%–7wt%): (1wt%–3wt%). After standing, the solid electrolyte sheet is removed and cured under UV light for 3–6 minutes to obtain a cross-network interlocking structure.

[0088] The mechanism is as follows: the PEG-based polymer network 104 (i.e., a polymer composed of poly(ethylene glycol) methacrylate and polyethylene glycol dimethacrylate) interpenetrates with the graphite / carbon black conductive pathway 105, forming a bicontinuous phase structure. The polymer network conducts ions, and the carbon black network conducts electrons (carbon black self-aggregates, and long-range conductive segments construct the conductive network), improving the ionic / electronic conductivity of the active material layer. After curing, a polymer film also forms on the surface of the active material layer, enhancing the strength of the solid electrolyte. The addition of conductive materials can improve the electronic conductivity of the current collector.

[0089] In some embodiments, the active layer can serve as the active layer of the positive electrode. The current collector is then the positive electrode current collector, and the process steps for forming the positive electrode include: providing the positive electrode current collector, the positive electrode current collector being located on the surface of the active layer 101, performing hot pressing treatment on the solid electrolyte and the positive electrode current collector, and the active layer 101 and the positive electrode current collector constituting the positive electrode 1.

[0090] In some embodiments, the active layer can serve as part of the active layer of the positive electrode sheet, which also has a positive electrode active layer. The current collector is a positive electrode current collector. The process steps for forming the positive electrode sheet include: preparing a positive electrode active layer located on the surface of the active layer 101; providing a positive electrode current collector located on the surface of the positive electrode active layer; and performing hot pressing treatment on the solid electrolyte and the positive electrode current collector. The positive electrode active layer, the active layer 101, and the positive electrode current collector constitute the positive electrode sheet 1. The active layer 101 not only serves as the positive electrode active layer but can also serve as a contact enhancement layer, thereby improving contact performance and forming a tight interfacial contact between the solid electrolyte layer and the positive electrode sheet during the hot pressing step.

[0091] Similarly, the active layer can serve as the active layer of the negative electrode. The current collector is then the negative electrode current collector, and the process steps for forming the negative electrode include: providing the negative electrode current collector, which is located on the surface of the active layer 101; performing hot pressing treatment on the solid electrolyte and the negative electrode current collector; and the active layer 101 and the negative electrode current collector together constitute the negative electrode 2.

[0092] In some embodiments, the active layer can serve as part of the active layer of the negative electrode sheet, which also has a negative electrode active layer. The current collector is a negative electrode current collector. The process steps for forming the negative electrode sheet include: preparing a negative electrode active layer located on the surface of the active layer 101; providing a negative electrode current collector located on the surface of the negative electrode active layer; and performing hot pressing treatment on the solid electrolyte and the negative electrode current collector. The negative electrode active layer, the active layer 101, and the negative electrode current collector constitute the negative electrode sheet 2. The active layer 101 not only serves as the negative electrode active layer but can also serve as a contact enhancement layer, thereby improving contact performance and forming a tight interfacial contact between the solid electrolyte layer and the negative electrode sheet during the hot pressing step.

[0093] The preparation method also includes: welding tabs to the adapter plate, connecting the other end of the adapter plate to the terminal post; and snapping the top cover into the battery casing. The adapter plate is located within the cavity, and the terminal post passes through the top cover.

[0094] The adapter includes at least a first adapter and a second adapter, and the terminal includes a positive terminal and a negative terminal. The first adapter is electrically connected to the positive electrode tab and the positive terminal of the positive electrode, and the second adapter is electrically connected to the negative electrode tab and the negative terminal of the negative electrode.

[0095] The solid-state secondary battery fabrication method provided in this application involves preparing a solid electrolyte with multiple branches 110 on its surface. These branches 110 are located between the positive current collector and the substrate layer 100, and / or between the negative current collector and the substrate layer 100. This allows the positive active layer of the positive electrode 1 and the negative active layer of the negative electrode 2 to be interleaved and interlocked with the solid electrolyte, thereby increasing the contact area and reducing the battery's internal resistance. Next, the branches 110 are formed using an aerosol process, creating branches 110 on the surface of the substrate layer 100. Subsequently, an active layer 101 is formed, located within the gaps between the branches 110. The active layer 101 can serve not only as a positive / negative active layer but also as a contact enhancement layer, improving contact performance and ensuring a tight interfacial contact between the solid electrolyte layer and the positive and negative electrodes 1 and 2 during the subsequent rolling process.

[0096] According to some embodiments of this application, another aspect of this application provides a solid-state secondary battery, including: a battery casing having a cavity inside; a bare cell located within the cavity; the bare cell includes a stacked positive electrode 1, a solid electrolyte, and a negative electrode 2, wherein the solid electrolyte includes: a substrate layer 100 and a plurality of branches 110, with gaps between adjacent branches 110, and the branches 110 located on at least one side of the substrate layer 100; an active layer 101 located on the surface of the substrate layer 100 and within the gaps; the active layer is located between the substrate layer 100 and the positive current collector, and / or, the active layer is located between the substrate layer 100 and the negative current collector. The active layer located between the substrate layer 100 and the positive current collector is part of the positive active layer and together with the positive current collector constitutes the positive electrode 1; the active layer located between the substrate layer 100 and the negative current collector is part of the negative active layer and together with the negative current collector constitutes the negative electrode 2.

[0097] In some embodiments, the branch 110 has holes, and a portion of the active layer 101 is embedded in the holes.

[0098] In some embodiments, the active layer 101 comprises an active material coated with Ga-LLZO.

[0099] The beneficial effects of the embodiments of this application will be further illustrated below with reference to examples and comparative examples.

[0100] Example 1:

[0101] LLZTO particles and PI particles were mixed uniformly at a volume ratio of 1:2 to obtain mixed particles. Nitrogen was used as the carrier gas and introduced into the aerosol chamber through a gas delivery device to ensure uniform dispersion of the mixed particles in the aerosol chamber. LLZTO solid electrolyte sheets were used as the substrate layer. The deposition chamber pressure was set to 10 Pa, the nozzle distance from the substrate layer surface was 10 mm, and the spray angle was 90°. The aerosol was sprayed onto the substrate layer surface through the nozzle using the carrier gas at a flow rate of 20 L / min, and the deposition time was 1 h. A prepolymer layer of deposited mixed particles was obtained. The prepolymer layer was placed in a high-temperature reactor and calcined at 900°C for 1 h to remove PI particles and simultaneously fuse LLZTO particles to form a precursor with branches. LFP, carbon black, and PVDF were mixed in a ratio of 94 wt%: 3 wt%: 3 wt%, and then NMP was added to achieve a slurry solid content of 50%. The mixture was stirred under negative pressure for 3 h to obtain an LFP slurry. Using a solid electrolyte layer as the substrate layer, LFP slurry was coated with a doctor blade, ultrasonicated for 5 minutes to promote the wetting of the slurry between the array columns, and then dried. The doctor blade-ultrasonication-drying steps were repeated 3 times to obtain a solid electrolyte with branches.

[0102] A positive electrode and a negative electrode are provided, and the active layer is the positive active layer of the positive electrode. The negative electrode, solid electrolyte and positive electrode are stacked in sequence and hot-pressed to obtain a bare cell. The bare cell is placed in a battery case and then packaged to obtain a solid secondary battery.

[0103] Example 2: The difference from Example 1 is that the volume ratio of LLZTO particles to PI particles is 1:1.

[0104] Example 3: The difference from Example 1 is that the volume ratio of LLZTO particles to PI particles is 1:10.

[0105] Example 4: The difference from Example 1 is that the active layer is the positive active layer of the positive electrode sheet and the negative active layer of the negative electrode sheet.

[0106] Example 5: The difference from Example 1 is that the prepolymer layer is placed in a high-temperature reactor and calcined at 500°C for 1 hour to remove PI particles, while LLZTO particles are fused to form a substrate layer with branches.

[0107] Example 6: The difference from Example 1 is that the prepolymer layer is placed in a high-temperature reactor and calcined at 1000°C for 1 hour to remove PI particles, while LLZTO particles are fused to form a substrate layer with branches.

[0108] Example 7:

[0109] The difference from Example 1 is that the preparation steps of the active layer 101 are as follows: LFP, nano-LLZO particles, carbon black, and PVDF are mixed in a ratio of 80wt%:14wt%:3wt%:3wt%, followed by the addition of NMP to achieve a solid content of 60%. The mixture is then dispersed at high speed under negative pressure for 5 hours to obtain a mixed slurry with a viscosity range of 10000 mPa·s and a fineness of less than 20 μm. Coating: The mixed slurry is pumped into a buffer tank and then fed through a conveyor pipe into a coating die head, where it is coated onto an LLZO solid electrolyte sheet at a coating speed of 5 m / min. The coated sheet is then transported via a conveyor belt into a multi-section drying oven with a temperature range of 80℃ to 130℃. After drying, the self-aggregation tendency of the nano-LLZO particles in the slurry exhibits the following characteristics: Figure 4 The structure.

[0110] Example 8: The difference from Example 7 is that the mass ratio of LFP, nano LLZO particles, carbon black, and PVDF is 76wt%:18wt%:3wt%:3wt%.

[0111] Example 9: The difference from Example 7 is that the mass ratio of LFP, nano LLZO particles, carbon black, and PVDF is 89wt%: 5wt%: 3wt%: 3wt%.

[0112] Example 10:

[0113] Nano-Ga-LLZO particles and LFP were added to NMP solvent at a ratio of 1 wt%:9 wt%, mixed evenly, dried to remove NMP, and then calcined at 700℃ for 30 min to form a Ga-LLZO-coated LFP structure. The Ga-LLZO-coated LFP structure, carbon black, and PVDF were mixed at a ratio of 94 wt%:3 wt%:3 wt%, and then NMP was added to achieve a solid content of 60%. The mixture was stirred under negative pressure for 3 h to obtain the LFP slurry. Using an LLZO solid electrolyte sheet as the substrate layer, the LFP slurry was extruded and coated. After drying, a surface-coated interlocking structure was obtained. Figure 5 structure.

[0114] Example 11: The difference from Example 10 is that the mass ratio of nano-Ga-LLZO particles to LFP is 2wt%:8wt%.

[0115] Example 12: The difference from Example 10 is that the mass ratio of nano-Ga-LLZO particles to LFP is 0.5wt%:9.5wt%.

[0116] Example 13: The difference from Example 10 is that the mass ratio of Ga-LLZO-coated LFP structure, carbon black, and PVDF is 98wt%:0.6wt%:1.4wt%.

[0117] Example 14: The difference from Example 10 is that the mass ratio of Ga-LLZO-coated LFP structure, carbon black, and PVDF is 92wt%:4wt%:4wt%.

[0118] Example 15:

[0119] In pure water, graphite, carbon black, CMC, and SBR were mixed in a ratio of 94wt%:2wt%:1.5wt%:2.5wt% to achieve a solid content of 50%. The mixture was stirred under negative pressure for 3 hours to obtain a graphite slurry. Using an LLZO solid electrolyte sheet as the substrate layer, the graphite slurry was extruded and coated, and after drying, a graphite-coated solid electrolyte sheet was obtained. The solid electrolyte sheet was then immersed in a curing solution and allowed to stand for 30 minutes. In the curing solution, the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP was 45wt%:40wt%:5wt%:3wt%:5wt%:2wt%. After standing, the solid electrolyte sheet was removed and cured under UV light for 3 minutes to obtain a cross-network interlocking structure, i.e. Figure 6 structure.

[0120] Example 16: The difference from Example 15 is that the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP is 35wt%:50wt%:5wt%:3wt%:5wt%:2wt%.

[0121] Example 17: The difference from Example 15 is that the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP is 55wt%:30wt%:5wt%:3wt%:5wt%:2wt%.

[0122] Comparative Example 1: The solid electrolyte is LLZTO solid electrolyte sheet.

[0123] Comparative Example 2: The difference from Example 1 is that LLZTO particles and PI particles are mixed in a volume ratio of 1:0.1.

[0124] Comparative Example 3: The difference from Example 1 is that LLZTO particles and PI particles are mixed in a volume ratio of 1:20.

[0125] Comparative Example 4: The difference from Example 1 is that the temperature of the reactor is 300°C.

[0126] Comparative Example 5: The difference from Example 1 is that the temperature of the reactor is 1500°C.

[0127] Comparative Example 6: The difference from Example 7 is that the mass ratio of LFP, nano LLZO particles, carbon black, and PVDF is 64wt%:30wt%:3wt%:3wt%.

[0128] Comparative Example 7: The difference from Example 7 is that the mass ratio of LFP, nano LLZO particles, carbon black, and PVDF is 93wt%:1wt%:3wt%:3wt%.

[0129] Comparative Example 8: The difference from Example 10 is that the mass ratio of nano-Ga-LLZO particles to LFP is 3wt%:7wt%.

[0130] Comparative Example 9: The difference from Example 10 is that the mass ratio of nano-Ga-LLZO particles to LFP is 0.2wt%:9.8wt%.

[0131] Comparative Example 10: The difference from Example 10 is that the mass ratio of Ga-LLZO-coated LFP structure, carbon black, and PVDF is 90wt%:5wt%:5wt%.

[0132] Comparative Example 11: The difference from Example 10 is that the mass ratio of Ga-LLZO-coated LFP structure, carbon black, and PVDF is 99wt%:0.5wt%:0.5wt%.

[0133] Comparative Example 12: The difference from Example 15 is that the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP is 25wt%:60wt%:5wt%:3wt%:5wt%:2wt%.

[0134] Comparative Example 13: The difference from Example 15 is that the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP is 65wt%:20wt%:5wt%:3wt%:5wt%:2wt%.

[0135] The solid-state secondary batteries prepared in the above examples and comparative examples were subjected to electrochemical performance tests in sequence, and the test results were summarized and recorded in Table 1.

[0136] Electrochemical performance testing: The test temperature was 25±2℃. The battery was charged at a constant current of 0.5C to 3.65V; allowed to rest for 10 minutes; then discharged at a constant current of 0.5C until the cutoff voltage reached 2.5V. This capacity was recorded as the initial capacity for the rate test. The battery was then charged at a constant current of 1C to 3.65V; allowed to rest for 10 minutes; and then discharged at a constant current of 1C until the cutoff voltage reached 2.5V. This capacity was recorded as the 1C rate capacity. Here, C-rate (C for short) is a value relative to the battery's rated capacity. For example, if a battery's rated capacity is 200Ah, then 1C is equivalent to a charging or discharging rate of 200A. According to this definition, 0.5C means the battery can be fully charged in 2 hours, while 1C means the battery can be fully charged in 1 hour.

[0137] Table 1

[0138]

[0139]

[0140] Referring to the experimental data in Table 1, it can be seen that, based on the electrochemical performance tests of Examples 1 to 6 and Comparative Examples 1 to 5, the solid electrolyte provided in this application can improve the rate capacity compared to ordinary solid electrolytes. Based on the electrochemical performance tests of Examples 7 to 17 and Comparative Examples 6 to 13, the solid electrolyte with a branched structure provided in this application can optimize both the rate capacity and the initial capacity.

[0141] Accordingly, another embodiment of this application provides a method for preparing a solid electrolyte, which differs from the above embodiment in that some process steps are changed, and the structure of the obtained solid electrolyte layer is different. The same or corresponding technical features as the above embodiment will not be described in detail here.

[0142] refer to Figure 7 The preparation method includes: mixing lithium metal compound, lanthanum metal compound, and zirconium metal compound in a molar ratio of (10-11):(2.5-3.5):(1.5-2.5) in an argon-protected glove box to obtain a metal precursor, with oxygen and water contents below 1 ppm; using an LLZO solid electrolyte surface as the substrate layer 200, with a baffle having arrayed holes on the surface, and evaporating the premixed metal precursor using a laser for deposition. The deposition temperature is set to 700℃-800℃, the deposition chamber pressure to 1 kPa-1.5 kPa; argon is used as the carrier gas at a flow rate of 3 standard liters / min-3.5 standard liters / min; oxygen is used as the reactant gas at a flow rate of 2 standard liters / min-2.5 standard liters / min; the reaction time is 30 min-60 min. After the reaction stops, the temperature is maintained for 15 min-25 min, and then cooled at a rate of 1℃ / s-1.5℃ / s to obtain a prepolymer with surface-grown array pillars 210.

[0143] The active material, conductive agent, binder and dispersion solution are stirred evenly to obtain a first coating slurry; the first coating slurry is applied to the prepolymer, wherein the first coating slurry flows into the gaps between some of the array columns 210, and after drying, it forms a solid electrolyte, and the coating slurry is transformed into an active layer 201.

[0144] In some embodiments, if the active layer is located between the positive current collector and the substrate layer, the active material is a positive active material; if the active layer is located between the negative current collector and the substrate layer, the active material is a negative active material.

[0145] In some embodiments, LFP, carbon black, and PVDF are mixed in a ratio of (92wt%–96wt%):(2wt%–4wt%):(2wt%–4wt%), followed by the addition of NMP to achieve a slurry solid content of 50%. The mixture is stirred under negative pressure for 3 hours to obtain an LFP slurry. Using a solid electrolyte layer as the substrate layer, the LFP slurry is coated with a doctor blade, ultrasonicated for 5 minutes to promote wetting of the slurry between the array columns, and then dried. This doctor blade-ultrasonic-drying process is repeated three times to obtain an interlocking structure in the form of array columns.

[0146] In some embodiments, the lithium metal compound may be LiC 11 H 19 O2; the lanthanum metal compound can be La(C5H7O2)3·4H2O, and the zirconium metal compound can be Zr(C5H7O2)4.

[0147] The mechanism is as follows: LLZO array pillars are grown by laser deposition template. The laser (such as a carbon dioxide laser, wavelength 8μm~12μm) is focused on the precursor target, and the instantaneous high temperature (>2000℃) vaporizes the organometallic compound. The gaseous precursor is transported to the LLZO substrate layer by the carrier gas (Ar). The micropores on the baffle (diameter ≈50μm, spacing ≈100μm) restrict the deposition area. After the gaseous precursor passes through the micropores, the diffusion is restricted, forming a local concentration gradient on the surface of the substrate layer, driving the columnar growth. The gaseous precursor reacts with O2 to generate Li-La-Zr-O aerosol, which undergoes heterogeneous nucleation on the LLZO surface (activation energy ≈150kJ / mol). The columnar growth preferentially grows along the (110) crystal plane (anisotropic surface energy difference), eventually forming a single-crystal LLZO array pillar. By combining multi-step ultrasound-assisted coating and PVDF binder phase modulation, a three-dimensional interlocking structure of LFP and LLZO was successfully constructed. This structure achieves synergistic optimization of high energy density, low impedance, and long cycle life through vertical ion channels, a three-dimensional electron network, and a multi-level stress buffering mechanism.

[0148] The preparation steps of positive electrode 1 and negative electrode 2 include: providing a current collector, with an active layer 101 located between the current collector and the substrate layer 100; stacking the negative electrode, solid electrolyte and positive electrode in sequence and hot-pressing them to obtain a bare cell; placing the bare cell into a battery case and then encapsulating it to obtain a solid secondary battery.

[0149] This application embodiment creates a large three-dimensional space by forming array pillars with gaps between them. The first coating slurry (i.e., the electrode active material) can fully fill these gaps, thus effectively adding more active layers per unit area of ​​substrate, thereby increasing the volumetric energy density and gravimetric energy density, resulting in a longer lifespan, i.e., a longer cycle time. In energy storage products, it can provide long-term energy storage capabilities of 4 hours or even 8 hours. Secondly, the three-dimensional interlocking structure of LFP and LLZO has good stability and can remain stable during multiple cycles, exhibiting excellent cycle life and long-term energy storage.

[0150] Figure 8 This is a sixth structural schematic diagram of a solid-state secondary battery provided in an embodiment of this application.

[0151] In some embodiments, reference Figure 8The process steps for forming the first coating slurry include: stirring the active material, nano-inorganic ceramic oxide particles, conductive agent, binder and dispersion solution evenly to obtain a second mixed solution; dispersing the second mixed solution at high speed under negative pressure for 4h to 6h to obtain the coating slurry, the viscosity range of the coating slurry is 5000mPa·s to 20000mPa·s, and the particle size is less than 20μm; wherein, the mass ratio of the active material, nano-inorganic ceramic oxide particles, conductive agent and binder is (73wt% to 93wt%): (5wt% to 18wt%): (0.6wt% to 4.5wt%): (1.4wt% to 4.5wt%).

[0152] LFP, nano-LLZO particles, carbon black, and PVDF were mixed in the following proportions: (73wt%–93wt%): (5wt%–18wt%): (0.6wt%–4.5wt%): (1.4wt%–4.5wt%). NMP was then added to achieve a solid content of 60%. The mixture was dispersed at high speed under negative pressure for 5 hours to obtain a mixed slurry with a viscosity range of 5000 mPa·s to 20000 mPa·s and a fineness of less than 20 μm. The mixed slurry was pumped into a buffer tank and then fed into a coating die via a conveyor pipe. The slurry was coated onto an LLZO solid electrolyte sheet at a coating speed of 5 m / min. The coated sheet was then transported via a conveyor belt into a multi-section drying oven with a temperature range of 80℃–130℃. After drying, due to the self-aggregation tendency of the nano-LLZO particles in the slurry, the LLZO particles in the coating layer transformed into secondary spherical aggregates 202.

[0153] Figure 9 This is a schematic diagram of a seventh structure of a solid-state secondary battery provided in an embodiment of this application.

[0154] refer to Figure 9 The active material is a Ga-LLZO coated active material. The process steps for forming the active material layer include: stirring Ga-LLZO particles, active particles, and a first dispersion solution evenly to form a first mixed solution; drying the first mixed solution to form a first precursor; calcining the first precursor to form the Ga-LLZO coated active material; wherein the mass ratio of Ga-LLZO particles to active particles is (0.5wt%~2wt%):(8wt%~9.5wt%). If the active material is a positive electrode active material, it can be a lithium source material; if the active material is a negative electrode active material, it can be graphite.

[0155] Nano-Ga-LLZO particles and LFP were added to NMP solvent at a ratio of (0.5wt%–2wt%):(8wt%–9.5wt%), mixed evenly, dried to remove NMP, and then calcined at 700℃ for 30–60 min to form a Ga-LLZO-coated LFP structure. The Ga-LLZO-coated LFP structure, carbon black, and PVDF were mixed at a ratio of (92wt%–98wt%):(0.6wt%–4wt%):(1.4wt%–4wt%), and then NMP was added to achieve a solid content of 60%. The mixture was stirred under negative pressure for 3–5 h to obtain an LFP slurry. Using an LLZO solid electrolyte sheet as a substrate layer, the LFP slurry was extruded and coated, and after drying, a surface-coated interlocking structure was obtained. The surface-coated interlocking structure is Ga-LLZO-coated active material 203.

[0156] Figure 10 This is a schematic diagram of an eighth structure of a solid-state secondary battery provided in an embodiment of this application.

[0157] In some embodiments, reference Figure 10 The active material is graphite; after forming the solid electrolyte, the process further includes: stirring lithium bis(fluorosulfonyl)imide, poly(ethylene glycol) methacrylate, polyethylene glycol dimethacrylate, photoinitiator, graphite, and conductive carbon black evenly to obtain a curing solution; immersing the solid electrolyte in the curing solution to cure the solid electrolyte containing the curing solution; wherein, the mass ratio of lithium bis(fluorosulfonyl)imide: poly(ethylene glycol) methacrylate: polyethylene glycol dimethacrylate: photoinitiator: graphite: conductive carbon black is (35wt%~55wt%): (30wt%~50wt%): (1wt%~7.5wt%): (1.5wt%~4.5wt%): (2wt%~7wt%): (1wt%~3wt%).

[0158] In pure water, graphite, carbon black, CMC, and SBR are mixed in a ratio of (92wt%–96wt%):(1wt%–3wt%):(0.5wt%–2.5wt%):(1.5wt%–3.5wt%) to achieve a solid content of 50%. The mixture is stirred under negative pressure for 3 hours to obtain a graphite slurry. Using an LLZO solid electrolyte sheet as the substrate layer, the graphite slurry is extruded and coated, and after drying, a graphite-coated solid electrolyte sheet is obtained. The solid electrolyte sheet is then immersed in a curing solution and allowed to stand for 30–60 minutes. In the curing solution, the mass ratio of lithium bis(fluorosulfonyl)imide salt: polyethylene glycol (PEG) methacrylate: PEG dimethacrylate: photoinitiator: graphite: conductive carbon black is (35wt%–55wt%): (30wt%–50wt%): (1wt%–7.5wt%): (1.5wt%–4.5wt%): (2wt%–7wt%): (1wt%–3wt%). After standing, the solid electrolyte sheet is removed and cured under UV light for 3–6 minutes to obtain a cross-network interlocking structure. The cross-network form refers to the cross-network formed by the PEG-based polymer network 204 (i.e., the polymer composed of PEG: PEG dimethacrylate) and the graphite / carbon black conductive pathway 205.

[0159] According to some embodiments of this application, another aspect of this application provides a solid-state secondary battery, including: a battery casing having a cavity inside; a bare cell located within the cavity; the bare cell includes a stacked positive electrode, a solid electrolyte, and a negative electrode, wherein the solid electrolyte includes: a substrate layer 200 and array pillars 210, the array pillars 210 being located on the surface of the substrate layer 200, gaps being present between the array pillars 210, and an active layer 201 being present on the surface of the array pillars 210; the active layer 201 being located on the surface of the substrate layer 200 and within the gaps; the active layer 201 being located between the substrate layer 200 and the positive current collector, and / or, the active layer being located between the substrate layer 200 and the negative current collector. The active layer located between the substrate layer 200 and the positive current collector is part of the positive active layer, and together with the positive current collector, constitutes the positive electrode 1; the active layer located between the substrate layer 200 and the negative current collector is part of the negative active layer, and together with the negative current collector, constitutes the negative electrode 2.

[0160] In some embodiments, the array pillar 210 has holes, and a portion of the active layer is embedded in the holes.

[0161] In some embodiments, the active layer is made of Ga-LLZO coated active material.

[0162] The beneficial effects of the embodiments of this application will be further illustrated below with reference to examples and comparative examples.

[0163] Example 18: In an argon-protected glove box, LiC was... 11 H 19 O2, La(C5H7O2)3·4H2O, and Zr(C5H7O2)4 were mixed in a molar ratio of 10.5:3:2, with oxygen and water contents both below 1 ppm. Using an LLZO solid electrolyte surface as the substrate layer, a baffle with arrayed perforations was placed on the surface. The premixed precursor was evaporated using a laser for deposition. The deposition temperature was set at 700℃, the deposition chamber pressure at 1 kPa, argon as the carrier gas at a flow rate of 3 standard liters / min, and oxygen as the reactant gas at a flow rate of 2 standard liters / min. The reaction time was 30 min. After the reaction was stopped, the temperature was maintained for 15 min, followed by cooling at a rate of 1℃ / s. A prepolymer with surface-grown array columns was obtained.

[0164] LFP, carbon black, and PVDF were mixed in a ratio of 94wt%:3wt%:3wt%, and then NMP was added to achieve a solid content of 50%. The mixture was stirred under negative pressure for 3 hours to obtain an LFP slurry. Using a solid electrolyte layer as the substrate, the LFP slurry was coated with a doctor blade, and sonicated for 5 minutes to promote wetting of the slurry between the array columns. The process was then dried. This doctor blade-scraping-sonicating-drying step was repeated three times to obtain an interlocking structure in the form of array columns.

[0165] A positive electrode and a negative electrode are provided. The active layer is part of the positive active layer of the positive electrode and the negative active layer of the negative electrode is located in the gap between the array columns. The negative electrode, solid electrolyte and positive electrode are stacked in sequence and hot-pressed to obtain a bare cell. The bare cell is placed in a battery case and then packaged to obtain a solid secondary battery.

[0166] Example 19: The difference from Example 18 is that: LiC 11 H 19 The molar ratio of O2, La(C5H7O2)3·4H2O and Zr(C5H7O2)4 is 11:2.5:2.

[0167] Example 20: The difference from Example 18 is that: LiC 11 H 19 The molar ratio of O2, La(C5H7O2)3·4H2O and Zr(C5H7O2)4 is 10.5:3:2.5.

[0168] Example 21: The difference from Example 18 is that the positive active layer of the positive electrode is located in the gap between the array pillars and the negative active layer of the negative electrode is located in the gap between the array pillars.

[0169] Example 22: The difference from Example 18 is that the preparation steps of the active layer 101 are as follows: LFP, nano-LLZO particles, carbon black, and PVDF are mixed in a ratio of 80wt%:14wt%:3wt%:3wt%, followed by the addition of NMP to achieve a solid content of 60%. The mixture is then dispersed at high speed under negative pressure for 5 hours to obtain a mixed slurry with a viscosity range of 10000 mPa·s and a fineness of less than 20 μm. Coating: The mixed slurry is pumped into a buffer tank and then fed into a coating die via a conveyor pipe. It is coated onto an LLZO solid electrolyte sheet at a coating speed of 5 m / min. The coated sheet is then transported via a conveyor belt into a multi-section drying oven with a temperature range of 80℃ to 130℃. After drying, the self-aggregation tendency of the nano-LLZO particles in the slurry exhibits the following characteristics: Figure 8 The structure.

[0170] Example 23: The difference from Example 22 is that the mass ratio of LFP, nano LLZO particles, carbon black, and PVDF is 76wt%:18wt%:3wt%:3wt%.

[0171] Example 24: The difference from Example 22 is that the mass ratio of LFP, nano LLZO particles, carbon black, and PVDF is 89wt%: 5wt%: 3wt%: 3wt%.

[0172] Example 25: Nano-Ga-LLZO particles and LFP were added to NMP solvent at a ratio of 1 wt%:9 wt%, mixed evenly, dried to remove NMP, and calcined at 700℃ for 30 min to form a Ga-LLZO-coated LFP structure. The Ga-LLZO-coated LFP structure, carbon black, and PVDF were mixed at a ratio of 94 wt%:3 wt%:3 wt%, and then NMP was added to bring the slurry solid content to 60%. The mixture was stirred under negative pressure for 3 h to obtain an LFP slurry. Using an LLZO solid electrolyte sheet as the substrate layer, the LFP slurry was extruded and coated. After drying, an interlocking structure with a surface coating was obtained. Figure 9 structure.

[0173] Example 26: The difference from Example 25 is that the mass ratio of nano-Ga-LLZO particles to LFP is 2wt%:8wt%.

[0174] Example 27: The difference from Example 25 is that the mass ratio of nano-Ga-LLZO particles to LFP is 0.5wt%:9.5wt%.

[0175] Example 28: The difference from Example 25 is that the mass ratio of Ga-LLZO-coated LFP structure, carbon black, and PVDF is 98wt%:0.6wt%:1.4wt%.

[0176] Example 29: The difference from Example 25 is that the mass ratio of Ga-LLZO-coated LFP structure, carbon black, and PVDF is 92wt%:4wt%:4wt%.

[0177] Example 30: In pure water, graphite, carbon black, CMC, and SBR were mixed in a ratio of 94wt%:2wt%:1.5wt%:2.5wt% to achieve a solid content of 50%. The mixture was stirred under negative pressure for 3 hours to obtain a graphite slurry. Using an LLZO solid electrolyte sheet as the substrate layer, the graphite slurry was extruded and coated, and after drying, a graphite-coated solid electrolyte sheet was obtained. The solid electrolyte sheet was immersed in a curing solution and allowed to stand for 30 minutes. In the curing solution, the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP was 45wt%:40wt%:5wt%:3wt%:5wt%:2wt%. After standing, the solid electrolyte sheet was removed and cured under UV light for 3 minutes to obtain a cross-network interlocking structure, i.e. Figure 10 structure.

[0178] Example 31: The difference from Example 30 is that the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP is 35wt%:50wt%:5wt%:3wt%:5wt%:2wt%.

[0179] Example 32: The difference from Example 30 is that the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP is 55wt%:30wt%:5wt%:3wt%:5wt%:2wt%.

[0180] Comparative Example 14: The difference from Example 18 is that LiC 11 H 19 The molar ratio of O2, La(C5H7O2)3·4H2O and Zr(C5H7O2)4 is 8:2.5:2.

[0181] Comparative Example 15: The difference from Example 18 is that LiC 11 H 19 The molar ratio of O2, La(C5H7O2)3·4H2O and Zr(C5H7O2)4 is 15:2.5:2.

[0182] Comparative Example 16: The difference from Example 22 is that the mass ratio of LFP, nano LLZO particles, carbon black, and PVDF is 70wt%: 24wt%: 3wt%: 3wt%.

[0183] Comparative Example 17: The difference from Example 22 is that the mass ratio of LFP, nano LLZO particles, carbon black, and PVDF is 90wt%:4wt%:3wt%:3wt%.

[0184] Comparative Example 18: The difference from Example 25 is that the mass ratio of nano-Ga-LLZO particles to LFP is 3wt%:7wt%.

[0185] Comparative Example 19: The difference from Example 25 is that the mass ratio of nano-Ga-LLZO particles to LFP is 0.2wt%:9.8wt%.

[0186] Comparative Example 20: The difference from Example 25 is that the mass ratio of Ga-LLZO-coated LFP structure, carbon black, and PVDF is 90wt%:5wt%:5wt%.

[0187] Comparative Example 21: The difference from Example 25 is that the mass ratio of Ga-LLZO-coated LFP structure, carbon black, and PVDF is 99wt%:0.5wt%:0.5wt%.

[0188] Comparative Example 22: The difference from Example 30 is that the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP is 25wt%:60wt%:5wt%:3wt%:5wt%:2wt%.

[0189] Comparative Example 23: The difference from Example 30 is that the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP is 65wt%:20wt%:5wt%:3wt%:5wt%:2wt%.

[0190] The solid-state secondary batteries prepared in the above embodiments and comparative examples were subjected to electrochemical performance tests in sequence, and the test results were summarized and recorded in Table 2.

[0191] Table 2

[0192]

[0193]

[0194] Referring to the experimental data in Table 2, it can be seen that, based on the electrochemical performance tests of Examples 18 to 32 and Comparative Examples 14 to 23, the solid electrolyte provided in this application can optimize the rate capacity and initial capacity.

[0195] Accordingly, another embodiment of this application provides a method for preparing a solid electrolyte, which differs from the above embodiment in that it does not form array pillars and branches, and the structure of the obtained solid electrolyte layer is different. The same or corresponding technical features as the above embodiment will not be described in detail here.

[0196] Figure 11 This is a ninth structural schematic diagram of a solid-state secondary battery provided in an embodiment of this application.

[0197] refer to Figure 11 The preparation method includes: providing a substrate layer 300; the process steps for forming a second coating slurry include: stirring the active material, nano-inorganic ceramic oxide particles, conductive agent, binder and dispersion solution evenly to obtain a second mixed solution; dispersing the second mixed solution at high speed under negative pressure for 4h to 6h to obtain a coating slurry, the viscosity range of the coating slurry is 5000mPa·s to 20000mPa·s, and the particle size is less than 20μm; wherein, the mass ratio of the active material, nano-inorganic ceramic oxide particles, conductive agent and binder is (73wt% to 93wt%): (5wt% to 18wt%): (0.6wt% to 4.5wt%): (1.4wt% to 4.5wt%).

[0198] LFP, nano-LLZO particles, carbon black, and PVDF were mixed in the following proportions: (73wt%–93wt%): (5wt%–18wt%): (0.6wt%–4.5wt%): (1.4wt%–4.5wt%). NMP was then added to achieve a solid content of 60%. The mixture was dispersed at high speed under negative pressure for 5 hours to obtain a mixed slurry with a viscosity range of 5000 mPa·s to 20000 mPa·s and a fineness of less than 20 μm. The mixed slurry was pumped into a buffer tank and then fed into a coating die via a conveyor pipe. It was coated onto an LLZO solid electrolyte sheet (i.e., substrate layer 300) at a coating speed of 5 m / min. The coated sheet was then transported via a conveyor belt into a multi-section drying oven with a temperature range of 80℃–130℃. After drying, due to the self-aggregation tendency of the nano-LLZO particles in the slurry, the LLZO particles in the coating layer exhibited the form of secondary spherical aggregates 302. The coating layer formed the active layer 301.

[0199] A positive electrode and a negative electrode are provided, with the active layer being a part of the positive active layer of the positive electrode and / or the active layer being a part of the negative active layer of the negative electrode; the negative electrode, solid electrolyte and positive electrode are stacked in sequence and hot-pressed to obtain a bare cell; the bare cell is placed in a battery case and then packaged to obtain a solid-state secondary battery.

[0200] Figure 12 This is a schematic diagram of the tenth structure of a solid-state secondary battery provided in an embodiment of this application.

[0201] refer to Figure 12 The preparation method includes: providing a substrate layer 300; the active material is a Ga-LLZO coated active material; the process steps for forming the active material layer include: stirring Ga-LLZO particles, active particles, and a first dispersion solution evenly to form a first mixed solution; drying the first mixed solution to form a first precursor; calcining the first precursor to form the Ga-LLZO coated active material; wherein the mass ratio of Ga-LLZO particles to active particles is (0.5wt%~2wt%):(8wt%~9.5wt%). If the active material is a positive electrode active material, the active material can be a lithium source material; if the active material is a negative electrode active material, the active material can be graphite.

[0202] Nano-Ga-LLZO particles and LFP were added to NMP solvent at a ratio of (0.5wt%–2wt%):(8wt%–9.5wt%), mixed evenly, dried to remove NMP, and then calcined at 700℃ for 30–60 min to form a Ga-LLZO-coated LFP structure. The Ga-LLZO-coated LFP structure, carbon black, and PVDF were mixed at a ratio of (92wt%–98wt%):(0.6wt%–4wt%):(1.4wt%–4wt%), and then NMP was added to achieve a solid content of 60%. The mixture was stirred under negative pressure for 3–5 h to obtain an LFP slurry. Using an LLZO solid electrolyte sheet as the substrate layer, the LFP slurry was extruded and coated, and after drying, a surface-coated interlocking structure was obtained. The surface-coated structure consisted of Ga-LLZO-coated active material 303.

[0203] A positive electrode and a negative electrode are provided, with the active layer being a part of the positive active layer of the positive electrode and / or the active layer being a part of the negative active layer of the negative electrode; the negative electrode, solid electrolyte and positive electrode are stacked in sequence and hot-pressed to obtain a bare cell; the bare cell is placed in a battery case and then packaged to obtain a solid-state secondary battery.

[0204] Figure 13 This is a schematic diagram of the eleventh structure of a solid-state secondary battery provided in an embodiment of this application.

[0205] refer to Figure 13The preparation method includes: providing a substrate layer 100; the active material is graphite; after forming the solid electrolyte, it further includes: stirring lithium bis(fluorosulfonyl)imide, poly(ethylene glycol) methacrylate, polyethylene glycol dimethacrylate, photoinitiator, graphite and conductive carbon black evenly to obtain a curing liquid; immersing the solid electrolyte in the curing liquid to cure the solid electrolyte with the curing liquid; wherein, the mass ratio of lithium bis(fluorosulfonyl)imide: poly(ethylene glycol) methacrylate: polyethylene glycol dimethacrylate: photoinitiator: graphite: conductive carbon black is (35wt%~55wt%): (30wt%~50wt%): (1wt%~7.5wt%): (1.5wt%~4.5wt%): (2wt%~7wt%): (1wt%~3wt%).

[0206] In pure water, graphite, carbon black, CMC, and SBR are mixed in a ratio of (92wt%–96wt%):(1wt%–3wt%):(0.5wt%–2.5wt%):(1.5wt%–3.5wt%) to achieve a solid content of 50%. The mixture is stirred under negative pressure for 3 hours to obtain a graphite slurry. Using an LLZO solid electrolyte sheet as the substrate layer 300, the graphite slurry is extruded and coated onto the sheet. After drying, a graphite-coated solid electrolyte sheet is obtained. The solid electrolyte sheet is then immersed in a curing solution and allowed to stand for 30–60 minutes. In the curing solution, the mass ratio of lithium bis(fluorosulfonyl)imide salt: polyethylene glycol methacrylate: polyethylene glycol dimethacrylate: photoinitiator: graphite: conductive carbon black is (35wt%–55wt%): (30wt%–50wt%): (1wt%–7.5wt%): (1.5wt%–4.5wt%): (2wt%–7wt%): (1wt%–3wt%). After standing, the solid electrolyte sheet is removed and cured under UV for 3–6 minutes to obtain a cross-network interlocking structure. The cross-network refers to the interpenetration of the PEG-based polymer network 304 (i.e., the polymer composed of polyethylene glycol methacrylate and polyethylene glycol dimethacrylate) and the graphite / carbon black conductive pathway 305, forming a cross-network.

[0207] A positive electrode and a negative electrode are provided, and the active layer is the positive active layer of the positive electrode. The negative electrode, solid electrolyte and positive electrode are stacked in sequence and hot-pressed to obtain a bare cell. The bare cell is placed in a battery case and then packaged to obtain a solid secondary battery.

[0208] Example 33: The preparation steps of active layer 101 are as follows: LFP, nano-LLZO particles, carbon black, and PVDF are mixed in a ratio of 80wt%:14wt%:3wt%:3wt%, followed by the addition of NMP to achieve a solid content of 60%. The mixture is then dispersed at high speed under negative pressure for 5 hours to obtain a mixed slurry with a viscosity range of 10000 mPa·s and a fineness of less than 20 μm. Coating: The mixed slurry is pumped into a buffer tank and then fed into a coating die via a conveyor pipe. It is coated onto an LLZO solid electrolyte sheet at a coating speed of 5 m / min. The coated sheet is then transported via a conveyor belt into a multi-section drying oven with a temperature range of 80℃ to 130℃. After drying, the self-aggregation tendency of the nano-LLZO particles in the slurry exhibits the following characteristics: Figure 10 The structure.

[0209] A positive electrode and a negative electrode are provided, with the active layer being a part of the positive active layer of the positive electrode and / or the active layer being a part of the negative active layer of the negative electrode; the negative electrode, solid electrolyte and positive electrode are stacked in sequence and hot-pressed to obtain a bare cell; the bare cell is placed in a battery case and then packaged to obtain a solid-state secondary battery.

[0210] Example 34: The difference from Example 33 is that the mass ratio of LFP, nano LLZO particles, carbon black, and PVDF is 76wt%:18wt%:3wt%:3wt%.

[0211] Example 35: The difference from Example 33 is that the mass ratio of LFP, nano LLZO particles, carbon black, and PVDF is 89wt%: 5wt%: 3wt%: 3wt%.

[0212] Example 36: Nano-Ga-LLZO particles and LFP were added to NMP solvent at a ratio of 1 wt%:9 wt%, mixed evenly, dried to remove NMP, and then calcined at 700℃ for 30 min to form a Ga-LLZO-coated LFP structure. The Ga-LLZO-coated LFP structure, carbon black, and PVDF were mixed at a ratio of 94 wt%:3 wt%:3 wt%, and then NMP was added to bring the solid content of the slurry to 60%. The mixture was stirred under negative pressure for 3 h to obtain an LFP slurry. Using an LLZO solid electrolyte sheet as the substrate layer, the LFP slurry was extruded and coated. After drying, an interlocking structure with a surface coating was obtained. Figure 11 structure.

[0213] A positive electrode and a negative electrode are provided, and the active layer is the positive active layer of the positive electrode. The negative electrode, solid electrolyte and positive electrode are stacked in sequence and hot-pressed to obtain a bare cell. The bare cell is placed in a battery case and then packaged to obtain a solid secondary battery.

[0214] Example 37: The difference from Example 36 is that the mass ratio of nano-Ga-LLZO particles to LFP is 2wt%:8wt%.

[0215] Example 38: The difference from Example 36 is that the mass ratio of nano-Ga-LLZO particles to LFP is 0.5wt%:9.5wt%.

[0216] Example 39: The difference from Example 36 is that the mass ratio of Ga-LLZO-coated LFP structure, carbon black, and PVDF is 98wt%:0.6wt%:1.4wt%.

[0217] Example 40: The difference from Example 36 is that the mass ratio of Ga-LLZO-coated LFP structure, carbon black, and PVDF is 92wt%:4wt%:4wt%.

[0218] Example 41:

[0219] In pure water, graphite, carbon black, CMC, and SBR were mixed in a ratio of 94wt%:2wt%:1.5wt%:2.5wt% to achieve a solid content of 50%. The mixture was stirred under negative pressure for 3 hours to obtain a graphite slurry. Using an LLZO solid electrolyte sheet as the substrate layer, the graphite slurry was extruded and coated, and after drying, a graphite-coated solid electrolyte sheet was obtained. The solid electrolyte sheet was then immersed in a curing solution and allowed to stand for 30 minutes. In the curing solution, the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP was 45wt%:40wt%:5wt%:3wt%:5wt%:2wt%. After standing, the solid electrolyte sheet was removed and cured under UV light for 3 minutes to obtain a cross-network interlocking structure, i.e. Figure 9 structure.

[0220] A positive electrode and a negative electrode are provided, and the active layer is the positive active layer of the positive electrode. The negative electrode, solid electrolyte and positive electrode are stacked in sequence and hot-pressed to obtain a bare cell. The bare cell is placed in a battery case and then packaged to obtain a solid secondary battery.

[0221] Example 42: The difference from Example 41 is that the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP is 35wt%:50wt%:5wt%:3wt%:5wt%:2wt%.

[0222] Example 43: The difference from Example 41 is that the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP is 55wt%:30wt%:5wt%:3wt%:5wt%:2wt%.

[0223] Comparative Example 24: The difference from Example 33 is that the mass ratio of LFP, nano LLZO particles, carbon black, and PVDF is 70wt%:24wt%:3wt%:3wt%.

[0224] Comparative Example 25: The difference from Example 33 is that the mass ratio of LFP, nano LLZO particles, carbon black, and PVDF is 90wt%:4wt%:3wt%:3wt%.

[0225] Comparative Example 26: The difference from Example 36 is that the mass ratio of nano-Ga-LLZO particles to LFP is 3wt%:7wt%.

[0226] Comparative Example 27: The difference from Example 36 is that the mass ratio of nano-Ga-LLZO particles to LFP is 0.2wt%:9.8wt%.

[0227] Comparative Example 28: The difference from Example 36 is that the mass ratio of Ga-LLZO-coated LFP structure, carbon black, and PVDF is 90wt%:5wt%:5wt%.

[0228] Comparative Example 29: The difference from Example 36 is that the mass ratio of Ga-LLZO-coated LFP structure, carbon black, and PVDF is 99wt%:0.5wt%:0.5wt%.

[0229] Comparative Example 30: The difference from Example 41 is that the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP is 25wt%:60wt%:5wt%:3wt%:5wt%:2wt%.

[0230] Comparative Example 31: The difference from Example 41 is that the mass ratio of LiFSI:PEGMA:PEGDMA:D1173:graphite:SP is 65wt%:20wt%:5wt%:3wt%:5wt%:2wt%.

[0231] The solid-state secondary batteries prepared in the above embodiments and comparative examples were subjected to electrochemical performance tests in sequence, and the test results were summarized and recorded in Table 3.

[0232] Table 3

[0233] project Initial capacity / Ah Ratio Capacity / Ah project Initial capacity / Ah Ratio Capacity / Ah Example 33 2.57 2.48 Example 43 3.00 2.84 Example 34 2.44 2.36 Comparative Example 24 2.04 1.98 Example 35 2.83 2.67 Comparative Example 25 3.00 2.82 Example 36 2.69 2.62 Comparative Example 26 2.11 2.08 Example 37 2.42 2.38 Comparative Example 27 2.95 2.76 Example 38 2.88 2.73 Comparative Example 28 2.59 2.54 Example 39 2.76 2.65 Comparative Example 29 2.61 2.33 Example 40 2.65 2.56 Comparative Example 30 3.03 2.61 Example 41 2.98 2.79 Comparative Example 31 3.00 2.78 Example 42 2.97 2.75

[0234] Referring to the experimental data in Table 3, it can be seen that, based on the electrochemical performance tests of Examples 33 to 43 and Comparative Examples 24 to 31, the solid electrolyte provided in the embodiments of this application can optimize the rate capacity and initial capacity.

[0235] According to some embodiments of this application, another aspect of this application provides an energy storage system, including: a secondary battery prepared by the method for preparing a solid-state secondary battery as described in any of the above embodiments, or a solid-state secondary battery as described in the above embodiments.

[0236] According to some embodiments of this application, another aspect of this application provides an electrical device, including: a solid-state secondary battery prepared by the method for preparing a secondary battery as described in any of the above embodiments, a solid-state secondary battery as described in the above embodiments, or an energy storage system as described in the above embodiments.

[0237] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A method for producing a solid-state secondary battery, characterized by, include: Solid electrolytes are formed, including: Obtaining a metal precursor includes: mixing a lithium metal compound, a lanthanum metal compound, and a zirconium metal compound to obtain a metal precursor; A substrate layer is provided, and the metal precursor is deposited on the substrate layer; Using argon as the carrier gas and oxygen as the reactant gas, a prepolymer of surface-grown array columns is obtained, wherein there are gaps between the array columns; Preparation of the first coating slurry; The first coating slurry is applied to one side of the substrate layer containing the prepolymer, and the coating slurry also flows into the gaps between the array columns; The first coating slurry is dried to transform into an active layer, and the substrate layer and the array pillars together constitute the solid electrolyte. A positive electrode and a negative electrode are prepared, and the preparation steps of at least one of the positive electrode and the negative electrode include: providing a current collector, with the active layer located between the current collector and the substrate layer. The negative electrode, the solid electrolyte, and the positive electrode are stacked in sequence and hot-pressed to obtain a bare cell. The bare cell is then placed into a battery case and packaged to obtain a solid-state secondary battery.

2. The method for preparing a solid-state secondary battery according to claim 1, characterized in that, The array column has holes, and the coating slurry also flows into the holes.

3. The method for preparing a solid-state secondary battery according to claim 2, characterized in that, The molar ratio of the lithium metal compound, the lanthanum metal compound, and the zirconium metal compound is (10-11):(2.5-3.5):(1.5-2.5).

4. The method of claim 3, wherein the solid-state secondary battery is prepared by a method comprising: The process steps for depositing the metal precursor on the substrate layer include: setting a baffle with an array of holes on the surface of the substrate layer, evaporating the premixed metal precursor using a laser, and depositing the metal precursor; wherein the deposition temperature is 700℃~800℃ and the deposition chamber pressure is 1kPa~1.5kPa.

5. The method for preparing a solid-state secondary battery according to claim 1, characterized in that, The process steps for forming the first coating slurry include: The active material, nano-inorganic ceramic oxide particles, conductive agent, binder and dispersion solution are stirred evenly to obtain a second mixed solution; The second mixed solution is dispersed at high speed under negative pressure for 4h to 6h to obtain the coating slurry, the viscosity range of the coating slurry is 5000mPa·s to 20000mPa·s; The mass ratio of active material, nano-inorganic ceramic oxide particles, conductive agent and binder is (73wt%~93wt%): (5wt%~18wt%): (0.6wt%~4.5wt%): (1.4wt%~4.5wt%).

6. The method for preparing a solid-state secondary battery according to claim 1, characterized in that, The first coating slurry includes an active material, wherein the active material is graphite; after forming the solid electrolyte, it further includes: Lithium bis(fluorosulfonyl)imide salt, poly(ethylene glycol) methacrylate, polyethylene glycol dimethacrylate, photoinitiator, graphite, and conductive carbon black were stirred evenly to obtain a curing solution. The solid electrolyte is immersed in the curing solution to cure it; wherein the mass ratio of lithium bis(fluorosulfonyl)imide:poly(ethylene glycol) methacrylate:polyethylene glycol dimethacrylate:photoinitiator:graphite:conductive carbon black is (35wt%~55wt%):(30wt%~50wt%):(1wt%~7.5wt%). (1.5wt%~4.5wt%):(2wt%~7wt%):(1wt%~3wt%)。 7. The method for preparing a solid-state secondary battery according to claim 1, characterized in that, The current collector is a positive electrode current collector, and the process steps for preparing the positive electrode sheet include: providing a positive electrode current collector, the positive electrode current collector is located on the surface of the active layer, and the solid-state electrolyte and the positive electrode current collector are subjected to hot pressing treatment, and the active layer and the positive electrode current collector constitute the positive electrode sheet.

8. A solid-state secondary battery characterized by comprising: Comprising: A battery shell having a cavity inside; A bare cell located in the cavity; the bare cell comprises a laminated positive electrode sheet, a solid-state electrolyte and a negative electrode sheet, wherein the solid-state electrolyte comprises: a substrate layer and a plurality of array columns, adjacent array columns have gaps between them, and the array columns are located on at least one side of the substrate layer; an active layer located on the surface of the substrate layer and in the gap; the active layer is located between the substrate layer and the positive electrode current collector, and / or the active layer is located between the substrate layer and the negative electrode current collector.

9. The secondary battery according to claim 8, characterized by The array column has a hole, and part of the active layer is embedded in the hole.

10. The secondary battery according to claim 8, characterized by The active layer comprises Ga-LLZO-coated active material.

11. An energy storage system characterized by, Comprising: The solid-state secondary battery prepared by the preparation method of the solid-state secondary battery according to any one of claims 1-7 or the solid-state secondary battery according to claims 8-10.

12. An electrical device, characterized by Comprising: The solid-state secondary battery prepared by the preparation method of the solid-state secondary battery according to any one of claims 1-7, the solid-state secondary battery according to claims 8-10, or the energy storage system according to claim 11.

Images