Composite laminated structure for solid-state battery and preparation method therefor

Abstract

Disclosed in the present application are a composite laminated structure for a solid-state battery and a preparation method therefor. The composite laminated structure comprises a ceramic layer and a conductive layer which are arranged in a laminated manner, wherein the ceramic layer and the conductive layer form an integrated structure by means of a co-firing process; at least one of a film corresponding to the ceramic layer and a film corresponding to the conductive layer is formed by means of a tape casting technique; and the conductive layer comprises a negative electrode metal material and a phase material, the mass ratio of the phase material to the negative electrode metal material is (0-5):(95-100), and the melting point of the phase material is 300-1000°C.

Description

Composite Layer Structures for Solid-State Batteries and Their Preparation Methods

[0001] This application claims priority to Chinese Patent Application No. 202411500358.0, filed with the Chinese Patent Office on October 25, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of solid-state battery technology, specifically to a composite laminate structure for solid-state batteries and its preparation method. Background Technology

[0003] Solid-state batteries are a new type of battery technology that uses a solid electrolyte to replace the liquid electrolyte and separator in traditional lithium-ion batteries. Solid-state batteries offer higher safety, longer lifespan, and higher energy density. Because they do not contain flammable organic components, they have significant advantages in safety and stability compared to traditional liquid lithium-ion batteries. Technical issues

[0004] However, the stability of the solid electrolyte in contact with the negative electrode is poor, which can easily lead to uneven current distribution. This can cause abnormal lithium deposition during battery charging and discharging, resulting in lithium dendrites and short circuits, which greatly reduces the safety performance of solid-state batteries. Technical solutions

[0005] In a first aspect, this application provides a composite laminate structure for solid-state batteries. The composite laminate structure includes a stacked ceramic layer and a conductive layer, which are formed into a single structure by a co-firing process.

[0006] Among them, at least one of the thin film corresponding to the ceramic layer and the thin film corresponding to the conductive layer is formed by casting technology before the co-firing process;

[0007] The conductive layer includes a negative electrode metal material and a phase material, with a mass ratio of phase material to negative electrode metal material of (0-5):(95-100), and the melting point of the phase material is 300-1000℃.

[0008] Secondly, this application also provides a method for preparing a composite laminate structure for solid-state batteries, comprising the following steps:

[0009] S1. Provide ceramic electrolyte materials and negative electrode metal materials;

[0010] S2. Prepare the ceramic electrolyte material and the negative electrode metal material into a first slurry and a second slurry, respectively, and perform casting treatment on the first slurry and the second slurry to obtain a solid electrolyte membrane and a conductive membrane; wherein, the second slurry includes a negative electrode metal material and a phase material, the mass ratio of the phase material to the negative electrode metal material is (0~5):(95~100), and the melting point of the phase material is 300~1000℃;

[0011] S3. The solid electrolyte membrane and the conductive membrane are hot-pressed to obtain a composite film;

[0012] S4. The composite film is sintered to obtain a composite laminate structure for solid-state batteries. Beneficial effects

[0013] The composite laminate structure for solid-state batteries provided in this application is formed by co-firing a ceramic layer and a conductive layer into an integral structure. At least one of the thin films corresponding to the ceramic layer and the conductive layer can be formed by casting technology. In addition to adding a negative electrode metal material, a phase material is also added to the conductive layer, which can achieve a tight bond between the solid electrolyte and the negative electrode of the solid-state battery. This avoids the poor stability of the contact between the solid electrolyte and the negative electrode of the solid-state battery, and can effectively prevent the growth of lithium dendrites caused by abnormal lithium deposition between the solid electrolyte and the negative electrode of the solid-state battery. Attached Figure Description

[0014] Figure 1 is a schematic diagram of a composite laminate structure for solid-state batteries provided in an embodiment of this application;

[0015] Figure 2 is a first morphological view of the composite laminate structure for solid-state batteries provided in an embodiment of this application;

[0016] Figure 3 is a second morphological diagram of the composite laminate structure for solid-state batteries provided in an embodiment of this application.

[0017] Explanation of reference numerals in the attached figures:

[0018] 100. Ceramic layer; 200. Conductive layer. Embodiments of the present invention

[0019] In related technologies, the interfacial chemical stability between the solid electrolyte and the negative electrode of solid-state batteries is poor, and lithium dendrites are prone to grow on the metal surface. In order to solve the technical problem of poor interfacial chemical stability between the solid electrolyte and the metal negative electrode, this application provides a composite laminate structure and its preparation method, as well as a solid-state battery.

[0020] Please refer to Figure 1, which is a schematic diagram of a composite laminate structure for solid-state batteries provided in an embodiment of this application.

[0021] As shown in Figure 1, in one embodiment provided in this application, a composite laminate structure for solid-state batteries includes a ceramic layer 100 and a conductive layer 200 stacked together, wherein the ceramic layer 100 and the conductive layer 200 are formed into an integral structure by a co-firing process.

[0022] Among them, at least one of the thin film corresponding to the ceramic layer 100 and the thin film corresponding to the conductive layer 200 is formed by casting technology before the co-firing process;

[0023] The conductive layer 200 includes a negative electrode metal material and a phase material, with the mass ratio of the phase material to the negative electrode metal material being (0-5):(95-100), and the melting point of the phase material being 300-1000℃.

[0024] Specifically, the ceramic layer 100 and the conductive layer 200 can be integrally formed by hot pressing sintering, thereby achieving a tight bond between the solid electrolyte and the negative electrode metal. This avoids obvious cross-sectional pores between the ceramic layer 100 and the conductive layer 200, effectively preventing the growth of lithium dendrites caused by abnormal lithium deposition between the solid electrolyte and the negative electrode.

[0025] Casting technology is a molding process used to prepare thin films or sheets. Its basic principle is to form a thin film of a certain thickness on a substrate by passing a slurry through a doctor blade or die, and then produce the final product through steps such as drying and sintering.

[0026] This application employs a casting technique to generate a solid electrolyte film corresponding to the ceramic layer and a conductive film corresponding to the conductive layer. This technique considers the uniform distribution of the solid electrolyte in the solid electrolyte film and the uniform distribution of the metal material in the conductive film, while also taking into account the thickness and deformation of both the solid electrolyte film and the conductive film. If the casting technique is not used, the resulting solid electrolyte film and conductive film will be thicker and more prone to deformation, requiring further processing. This not only increases production costs but also makes processing more difficult. Furthermore, after the solid electrolyte film and conductive film are assembled and bonded, interfacial gaps can easily occur, affecting conductivity.

[0027] In some embodiments, this application further reduces the surface tension of the conductive layer 200 and improves its wettability by adding a phase material to the conductive layer 200. The melting point of the phase material can be set to 300-1000°C, and the mass ratio of the phase material to the negative electrode metal material is (0-5):(95-100). This ensures a tighter hot-press bonding between the conductive layer 200 and the ceramic layer 100, thereby further reducing the interfacial porosity between the solid electrolyte and the negative electrode. This avoids significant cross-sectional pores between the solid electrolyte and the negative electrode, effectively preventing lithium dendrite growth caused by abnormal lithium deposition between the solid electrolyte and the negative electrode.

[0028] In some embodiments, the interfacial porosity between the ceramic layer 100 and the conductive layer 200 can be between 0% and 5%.

[0029] In this embodiment, the interface porosity, also known as cavitation rate, porosity, or cross-sectional gas content, can be understood as the ratio of the area occupied by the cross-sectional pores at the bonding interface between the ceramic layer 100 and the conductive layer 200 to the area of ​​the bonding interface after the ceramic layer 100 and the conductive layer 200 are bonded together.

[0030] In one embodiment, the interfacial porosity can be between 0% and 1%.

[0031] Specifically, the interfacial porosity can be 1%, 0.5%, 0.2%, 0.1%, 0.05%, 0.025%, 0.015%, 0.005%, etc. The interfacial porosity between the ceramic layer 100 and the conductive layer 200 can be measured using methods such as direct measurement, image analysis, microscopy, and density measurement.

[0032] In some embodiments, the ceramic layer 100 includes a ceramic electrolyte.

[0033] Specifically, ceramic electrolytes are a class of solid materials with high ionic conductivity and excellent mechanical strength, and are widely used in solid-state batteries. The main advantage of ceramic electrolytes lies in their ability to effectively solve safety issues such as combustion and explosion that may occur during the use of traditional liquid electrolytes.

[0034] In this embodiment, the ceramic electrolyte can be garnet-type LLZTO (lithium lanthanum zirconium oxide, Li7La3Zr2O) 12 ), perovskite type (lithium lanthanum titanium oxide / lithium lanthanum titanate, Li 0.33 La 0.56 TiO3), NASICON (sodium superionic conductor, such as lithium titanium aluminum phosphate, Li 1.3 Al 0.3 Ti 1.7 (PO4)3) type, LISICON (lithium superionic conductor, such as Li 4-x Zn 2x GeO4, 0≦x≦1) type and layered LiN3, etc.

[0035] In one embodiment, the ceramic electrolyte may be a garnet-type ceramic electrolyte.

[0036] In some embodiments, the molecular formula of the garnet-type ceramic electrolyte includes: LixLa3ZryTa z O 12 , where 6<x≦7, 1<y≦2, 0≦z≦1.

[0037] In one embodiment, the molecular formula of the garnet-type ceramic electrolyte can be Li 6.4 La3Zr 1.4 Ta 0.6 O 12 .

[0038] Garnet-type ceramic electrolytes are widely used due to their high room-temperature ionic conductivity (10⁻³ S·cm⁻¹) and stability with lithium metal. However, garnet-type ceramic electrolytes readily react with water and carbon dioxide in the air, resulting in poor stability. This application addresses this issue by hot-pressing a garnet-type ceramic electrolyte to the negative electrode material in the form of a thin film. This ensures a tight bond between the garnet-type ceramic electrolyte and the negative electrode material, significantly reducing the interfacial porosity between the solid electrolyte and the negative electrode. This reduces the probability of the garnet-type ceramic electrolyte reacting with water and carbon dioxide in the air, and greatly improves the stability of the contact between the solid electrolyte and the negative electrode.

[0039] Furthermore, the garnet-type ceramic electrolyte provided in this application can also be composited with other polymers or ceramic materials to further improve the mechanical strength and ionic conductivity of the ceramic layer 100. For example, uniformly dispersing the nanoparticles of the garnet-type ceramic electrolyte in a PEO / LiTFSI polymer electrolyte can significantly improve the ionic conductivity and mechanical properties of the ceramic layer 100.

[0040] In some embodiments, the conductive layer 200 comprises nickel metal, graphite, or lithium metal.

[0041] In one embodiment, the conductive layer 200 contains nickel metal, which can improve the energy density and power capability of the solid-state battery, while also effectively reducing the growth of lithium dendrites caused by abnormal lithium deposition between the solid electrolyte and the negative electrode.

[0042] In some embodiments, the phase material includes at least one selected from silicon oxide, aluminum oxide, lithium oxide, zinc oxide, boron oxide, and titanium oxide.

[0043] In this embodiment, the phase material can be a low-melting-point glass phase material.

[0044] In one embodiment, the melting point of the glass phase material can be 600–800°C. The glass phase material can be composed of three or more of silicon oxide, aluminum oxide, lithium oxide, zinc oxide, boron oxide, and titanium oxide, which can ensure a tighter hot-press bonding between the conductive layer 200 and the ceramic layer 100, thereby further reducing the interfacial porosity between the solid electrolyte and the negative electrode. This avoids significant cross-sectional pores between the solid electrolyte and the negative electrode, effectively preventing lithium dendrite growth caused by abnormal lithium deposition between the solid electrolyte and the negative electrode.

[0045] Among them, silicon oxide, aluminum oxide, lithium oxide, zinc oxide, boron oxide, and titanium oxide can be silicon dioxide, aluminum oxide, lithium oxide, zinc oxide, boron oxide, and titanium dioxide, respectively.

[0046] In some embodiments, the negative electrode metal material can be nickel metal, and the phase material can be mixed with nickel metal in the form of doping, that is, the mass ratio between the phase material and nickel metal can be (0-5):(95-100).

[0047] In one embodiment, the mass ratio between the phase material and the nickel metal material can be (1-5):(95-99), or (1-4):(96-99), or (2-4):(96-98), etc.

[0048] Specifically, the phase material can be a glass phase material, and the mass ratio between the glass phase material and the nickel metal material can be 3:97, which can further improve the wettability of the conductive layer 200, thereby ensuring that the conductive layer 200 and the ceramic layer 100 can be more tightly bonded by hot pressing.

[0049] The composite laminate structure for solid-state batteries provided in this application includes a ceramic layer 100 and a conductive layer 200 stacked together. The ceramic layer 100 and the conductive layer 200 are formed into an integral structure through a co-firing process, thereby achieving a tight bond between the solid electrolyte and the negative electrode of the solid-state battery. This solves the problem of poor contact stability between the solid electrolyte and the negative electrode of the solid-state battery and can effectively avoid the growth of lithium dendrites caused by abnormal lithium deposition between the solid electrolyte and the negative electrode of the solid-state battery.

[0050] In some embodiments, this application also provides a method for preparing a composite laminate structure for solid-state batteries, comprising the following steps:

[0051] S1. Provide ceramic electrolyte materials and negative electrode metal materials;

[0052] S2. Prepare the ceramic electrolyte material and the negative electrode metal material into a first slurry and a second slurry, respectively, and perform casting treatment on the first slurry and the second slurry to obtain a solid electrolyte membrane and a conductive membrane; wherein, the second slurry includes a negative electrode metal material and a phase material, the mass ratio of the phase material to the negative electrode metal material is (0~5):(95~100), and the melting point of the phase material is 300~1000℃;

[0053] S3. The solid electrolyte membrane and the conductive membrane are hot-pressed to obtain a composite film;

[0054] S4. The composite film is sintered to obtain a composite laminate structure for solid-state batteries.

[0055] In this embodiment, the ceramic electrolyte material and the negative electrode metal material can be respectively made into a first slurry and a second slurry, that is, the ceramic electrolyte material is configured into a first slurry and the negative electrode metal material is configured into a second slurry. The first slurry and the second slurry can be subjected to casting process to form a solid electrolyte film and a conductive film.

[0056] Specifically, both the solid electrolyte membrane and the conductive membrane are cast films, which ensures that the solid electrolyte and negative electrode metal materials are uniformly distributed in the film. As a result, after the solid electrolyte membrane and the conductive membrane are hot-pressed together, the contact stability between the solid electrolyte membrane and the conductive membrane is high, which improves the stability of the contact between the solid electrolyte and the negative electrode in the solid battery.

[0057] Cast film, a type of non-stretched, non-oriented flat extruded film produced through a melt casting and rapid cooling process, is characterized by high performance, high transparency, good gloss, crystallinity, and hardness. It is widely used in packaging, medical, and electronics industries, such as in stretch film, barrier film, and food-grade packaging materials. The production process of cast film mainly includes melt extrusion, cooling and shaping, printing, and winding.

[0058] The production process of cast film differs from that of blown film. Cast film can be cooled and shaped on cooling rollers without longitudinal or transverse stretching, resulting in uniform thickness, good transparency, and excellent heat-sealing properties. Furthermore, cast film can be produced using two methods: single-layer casting and multi-layer co-extrusion casting. The production equipment for cast film includes an extruder, casting unit, cooling rollers, and cutting equipment.

[0059] Before casting the first and second slurries, they need to be ball-milled to improve their uniformity and viscosity during the casting process. Furthermore, after ball milling, vacuum degassing can be performed to remove air bubbles, thus preventing the formation of bubbles or pinholes during casting, which could lead to poor stability in the contact between the solid electrolyte membrane and the conductive membrane.

[0060] In addition, during the process of generating their respective cast films using casting technology, the first slurry and the second slurry mentioned in this application can use PET as a substrate, that is, a solid electrolyte film and a conductive film can be formed on the PET. After the solid electrolyte film and the conductive film are formed on the PET, they can be peeled off from the PET.

[0061] Meanwhile, the reason this application employs casting technology to generate the solid electrolyte membrane and conductive membrane is that it considers the uniform distribution of the solid electrolyte in the solid electrolyte membrane and the uniform distribution of the metal material in the conductive membrane, as well as the thickness and deformation issues of the solid electrolyte membrane and conductive membrane. If casting technology is not used, the resulting solid electrolyte membrane and conductive membrane will be thicker and more prone to deformation, requiring further processing. This not only increases production costs but also makes processing more difficult. Furthermore, after the solid electrolyte membrane and conductive membrane are assembled and bonded, interfacial gaps can easily occur, affecting conductivity.

[0062] In some embodiments, the first slurry includes a garnet-type ceramic electrolyte, an organic solvent, a dispersant, a binder, and a plasticizer, and the second slurry includes nickel metal, a glass phase material, an organic solvent, a dispersant, a binder, and a plasticizer.

[0063] In some embodiments, the first slurry comprises: 35-50 parts by weight of garnet-type ceramic electrolyte, 50-65 parts by weight of organic solvent, 0-1 parts by weight of dispersant, 1-10 parts by weight of binder, and 0-10 parts by weight of plasticizer; the second slurry comprises 34-49 parts by weight of nickel metal, 0-2 parts by weight of glass phase material, 50-65 parts by weight of organic solvent, 0-1 parts by weight of dispersant, 1-10 parts by weight of binder, and 0-10 parts by weight of plasticizer.

[0064] In some embodiments, the ceramic electrolyte has a particle size of 0.05–1 μm, and the nickel metal has a particle size of 0.5–5 μm.

[0065] Specifically, the first slurry and the second slurry are cast into a solid electrolyte membrane and a conductive membrane, respectively. After the solid electrolyte membrane and the conductive membrane are hot-pressed to form a composite film, the particle size of the ceramic electrolyte in the first slurry is set between 0.05 and 1 μm, while the negative electrode metal material, such as nickel metal, in the second slurry is set between 0.5 and 5 μm. This ensures that the solid electrolyte membrane and the conductive membrane are densified after sintering, thereby effectively preventing the growth of lithium dendrites caused by abnormal lithium deposition between the solid electrolyte and the negative electrode in the solid battery.

[0066] In some embodiments, the organic solvent includes at least one of ethanol, ethyl acetate, n-butanol, acetone, and toluene; the dispersant includes at least one of fish oil, triethanolamine, and trioleic acid glyceride; the binder includes polyvinyl butyral; and the plasticizer includes butyl phthalate.

[0067] In one embodiment, the organic solvent includes at least two of ethanol, ethyl acetate, and n-butanol, which can ensure the uniformity of the garnet-type ceramic electrolyte and nickel metal in their respective slurries.

[0068] In some embodiments, the thickness of the solid electrolyte membrane can be 0.01 to 1 mm. The thickness of the solid electrolyte membrane can be determined according to the specific process. For example, when the solid electrolyte membrane is formed using a casting technique, the thickness can be between 0.01 and 1 mm.

[0069] In one embodiment, the thickness of the solid electrolyte membrane is 0.03 to 0.1 mm.

[0070] In some embodiments, the thickness of the conductive film can be 0.005–0.1 mm. The thickness of the conductive film can be determined according to the specific process. For example, when the conductive film is formed using a casting technique, the thickness can be between 0.005 and 0.1 mm.

[0071] In one embodiment, the thickness of the conductive film can be 0.005 to 0.03 mm.

[0072] In some embodiments, the thickness of the composite laminate structure used for solid-state batteries can be 10–1080 μm.

[0073] In one embodiment, the thickness of the composite laminate structure used for solid-state batteries can be 15–120 μm.

[0074] In this embodiment, the thickness change that occurs after the solid electrolyte membrane and the conductive membrane are hot-pressed and sintered is at the micrometer level, that is, the thickness of the solid electrolyte membrane and the conductive membrane will be reduced by 5 to 20 μm after hot pressing and sintering.

[0075] In one embodiment, the thickness of the solid electrolyte membrane and the conductive membrane after hot pressing and sintering will be reduced by 10 to 15 μm.

[0076] In some embodiments, the hot pressing pressure is 1–10 MPa, the hot pressing temperature is 60–100°C, the hot pressing time is 1–3 min, the sintering temperature is 1000–1500°C, and the sintering time is 5–15 min.

[0077] In this embodiment, when the solid electrolyte membrane and the conductive membrane are hot-pressed together, the hot-pressing pressure can be controlled between 1 and 10 MPa, the hot-pressing temperature can be controlled between 60 and 100°C, and the hot-pressing time can be controlled between 1 and 3 minutes. This not only ensures that the solid electrolyte membrane and the conductive membrane are tightly bonded, but also avoids significant changes in the morphology of the solid electrolyte membrane and the conductive membrane.

[0078] In one embodiment, the hot pressing pressure can be 5 MPa, the hot pressing temperature can be 80°C, and the hot pressing time can be 2 min.

[0079] In addition, after the solid electrolyte membrane and the conductive membrane are hot-pressed together, the composite film after hot-pressing needs to be sintered to achieve densification between the solid electrolyte membrane and the conductive membrane, thereby completing the integral molding of the solid electrolyte membrane and the conductive membrane.

[0080] Specifically, the sintering temperature can be 1000-1500℃, and the sintering time can be 5-15 minutes, which can ensure that the solid electrolyte membrane and the conductive membrane can be physically bonded together to form a single unit, avoiding chemical reactions between the components of the solid electrolyte membrane and the conductive membrane.

[0081] In one embodiment, the sintering temperature can be 1300°C and the sintering time can be 10 minutes.

[0082] In addition, the composite film needs to be sintered in an argon atmosphere during the sintering process, and the sintering temperature rise rate should be as fast as possible. The sintering temperature rise rate can be controlled between 5 and 50℃ / min, such as 5℃ / min, 10℃ / min, 15℃ / min, 20℃ / min, 30℃ / min, 40℃ / min, 50℃ / min, etc. This ensures that the composite film can be densified after sintering, thereby effectively avoiding the growth of lithium dendrites caused by abnormal lithium deposition between the solid electrolyte and the negative electrode in the solid-state battery.

[0083] In some embodiments, this application also provides a solid-state battery, which includes the composite laminate structure for solid-state batteries provided in the above embodiments.

[0084] The beneficial effects of this application will be illustrated below with reference to specific embodiments.

[0085] Example 1

[0086] S1. A first slurry is prepared by mixing 40 parts by weight of LLZTO ceramic powder, 60 parts by weight of ethanol, 0.5 parts by weight of triethanolamine, 5 parts by weight of polyvinyl butyral, and 5 parts by weight of butyl phthalate. The first slurry is ball-milled and then used to prepare a solid electrolyte membrane by casting technology.

[0087] S2. A second slurry is prepared by mixing 40 parts by weight of high-purity nickel powder (purity > 99%), 60 parts by weight of ethanol, 0.5 parts by weight of triethanolamine, 5 parts by weight of polyvinyl butyral, and 5 parts by weight of butyl phthalate. The second slurry is ball-milled and then used to prepare a conductive film by casting technology.

[0088] S3. Cut the solid electrolyte membrane and the conductive membrane into the same size, such as 100*100mm. After stacking the solid electrolyte membrane and the conductive membrane, hot press them at 80℃ with a pressure of 5MPa. After holding the pressure for 2 minutes, release the pressure to obtain a composite film.

[0089] S4. Cut the composite film into the required size, such as 50*100mm, and place it on a ceramic support plate for degreasing and sintering. After sintering at 1300℃ and holding for 10 minutes, a composite laminate structure for solid-state batteries is obtained.

[0090] Example 2

[0091] S1. A first slurry is prepared by mixing 40 parts by weight of LLZTO ceramic powder, 60 parts by weight of ethanol, 0.5 parts by weight of triethanolamine, 5 parts by weight of polyvinyl butyral, and 5 parts by weight of butyl phthalate. The first slurry is ball-milled and then used to prepare a solid electrolyte membrane by casting technology.

[0092] S2. After uniformly mixing 38.8% by weight of high-purity nickel powder (purity > 99%) with 1.2% by weight of low-melting-point phase powder (silicon dioxide, aluminum oxide and lithium oxide), 60% by weight of ethanol, 0.5% by weight of triethanolamine, 5% by weight of polyvinyl butyral and 5% by weight of butyl phthalate are added to prepare a second slurry. After ball milling, the second slurry is used to prepare a conductive film using casting technology.

[0093] S3. Cut the solid electrolyte membrane and the conductive membrane into the same size, such as 100*100mm. After stacking the solid electrolyte membrane and the conductive membrane, hot press them at 80℃ with a pressure of 5MPa. After holding the pressure for 2 minutes, release the pressure to obtain a composite film.

[0094] S4. Cut the composite film into the required size, such as 50*100mm, and place it on a ceramic support plate for degreasing and sintering. After sintering at 1300℃ and holding for 10 minutes, a composite laminate structure for solid-state batteries is obtained.

[0095] Test Example 1

[0096] The bonding interface of the composite laminate structures for solid-state batteries prepared in Examples 1 and 2 was observed using scanning electron microscopy, and the morphology images shown in Figures 2 and 3 were obtained, respectively. Figure 2 shows the morphology of the composite laminate structure in Example 1 at 100 μm, with a ceramic layer on top and a conductive layer on the bottom; Figure 3 shows the morphology of the composite laminate structure in Example 2 at 50 μm, with a ceramic layer on top and a conductive layer on the bottom.

[0097] As can be clearly observed from Figures 2 and 3, the bonding interface of the composite laminate structure prepared by Examples 1 and 2 has no obvious cross-sectional pores. It can be determined that the solid electrolyte membrane and the conductive membrane in the composite laminate structure provided by this application are tightly bonded, which can solve the problem of poor stability of the contact between the solid electrolyte and the negative electrode, and thus effectively avoid the growth of lithium dendrites caused by abnormal lithium deposition between the solid electrolyte and the negative electrode.

[0098] Test Example 2

[0099] After measuring the thickness of the solid electrolyte membrane, conductive membrane, and composite laminate in Examples 1 and 2 using a micrometer, the thickness of the solid electrolyte membrane in Example 1 was 30–40 μm, the thickness of the conductive membrane was 8–12 μm, and the thickness of the composite laminate was 36–39 μm; the thickness of the solid electrolyte membrane in Example 2 was 30–40 μm, the thickness of the conductive membrane was 8–12 μm, and the thickness of the composite laminate was 38–40 μm.

[0100] Meanwhile, after measuring the diameter of the composite laminate structure in Example 1 and Example 2 with a micrometer, an Ag conductive layer was deposited on its ceramic surface and it was encapsulated with a button cell. Subsequently, an AC impedance test was performed using an electrochemical workstation, Metrohm Autolab, with an AC voltage of 10mV and a frequency of 10MHz to 1Hz.

[0101] After measuring the AC impedance of the composite laminate structure in Examples 1 and 2, the ionic conductivity was calculated. The calculation formula can be σ = L / RS, where L is the thickness of the composite laminate structure, R is the AC impedance of the composite laminate structure, and S is the single-sided area of ​​the composite laminate structure (calculated using the thickness and diameter of the composite laminate structure).

[0102] The thicknesses of the composite laminates in Example 1 were set to 36 μm and 39 μm, and the thicknesses of the composite laminates in Example 2 were set to 38 μm and 40 μm. Substituting these thicknesses into the formula for calculating ionic conductivity, the ionic conductivity of the composite laminates in Example 1 was found to be 0.961 mS / cm and 1.042 mS / cm, and the ionic conductivity of the composite laminates in Example 2 was found to be 1.207 mS / cm and 1.143 mS / cm, respectively.

[0103] It can be seen that the ionic conductivity of the composite film with the laminated structure provided in this application can be close to 1 mS / cm, or even reach more than 1 mS / cm, which effectively solves the problem of poor stability in the contact between the solid electrolyte film and the conductive film, and can effectively avoid the growth of lithium dendrites caused by abnormal lithium deposition between the solid electrolyte and the negative electrode.

Claims

1. A composite laminate structure for solid-state batteries, comprising a ceramic layer (100) and a conductive layer (200) stacked together, wherein the ceramic layer (100) and the conductive layer (200) are formed into an integral structure by a co-firing process; in, At least one of the thin film corresponding to the ceramic layer (100) and the thin film corresponding to the conductive layer (200) is formed by tape casting before the co-firing process; The conductive layer (200) includes a negative electrode metal material and a phase material, wherein the mass ratio of the phase material to the negative electrode metal material is (0-5):(95-100), and the melting point of the phase material is 300-1000℃.

2. The composite laminate structure for solid-state batteries according to claim 1, wherein, The ceramic layer (100) includes a garnet-type ceramic electrolyte.

3. The composite laminate structure for solid-state batteries according to claim 2, wherein, The molecular formula of the garnet-type ceramic electrolyte includes: LixLa3ZryTazO 12 , where 6<x≦7, 1<y≦2, 0≦z≦1.

4. The composite laminate structure for solid-state batteries according to claim 1, wherein, The negative electrode metal material includes nickel metal, and the phase material includes a glass phase material.

5. The composite laminate structure for solid-state batteries according to claim 4, wherein, The melting point of the glass phase material is 600–800°C.

6. The composite laminate structure for solid-state batteries according to claim 4, wherein, The glass phase material includes at least one of silicon oxide, aluminum oxide, lithium oxide, zinc oxide, boron oxide, and titanium oxide.

7. The composite laminate structure for solid-state batteries according to claim 4, wherein, The mass ratio of the glass phase material to the nickel metal is (2-4):(96-98).

8. The composite laminate structure for solid-state batteries according to any one of claims 1-7, wherein, The interfacial porosity between the ceramic layer (100) and the conductive layer (200) is 0 to 1%.

9. A method for preparing a composite laminate structure for solid-state batteries, comprising the following steps: S1. Provide ceramic electrolyte materials and negative electrode metal materials; S2. The ceramic electrolyte material and the negative electrode metal material are respectively prepared into a first slurry and a second slurry, and the first slurry and the second slurry are subjected to casting treatment to obtain a solid electrolyte film and a conductive film; wherein, The second slurry includes a negative electrode metal material and a phase material, wherein the mass ratio of the phase material to the negative electrode metal material is (0-5):(95-100), and the melting point of the phase material is 300-1000℃; S3. The solid electrolyte membrane and the conductive membrane are hot-pressed to obtain a composite film; S4. The composite film is sintered to obtain a composite laminate structure for solid-state batteries.

10. The method for preparing a composite laminate structure for solid-state batteries according to claim 9, wherein, The first slurry includes garnet-type ceramic electrolyte, organic solvent, dispersant, binder and plasticizer.

11. The method for preparing a composite laminate structure for solid-state batteries according to claim 9, wherein, The second slurry includes nickel metal, glass phase material, organic solvent, dispersant, binder and plasticizer.

12. The method for preparing a composite laminate structure for solid-state batteries according to claim 9, wherein, The ceramic electrolyte has a particle size of 0.05–1 μm.

13. The method for preparing a composite laminate structure for solid-state batteries according to claim 11, wherein, The nickel metal has a particle size of 0.5–5 μm.

14. The method for preparing a composite laminate structure for solid-state batteries according to claim 10, wherein, The first slurry comprises: 35-50 parts by weight of garnet-type ceramic electrolyte, 50-65 parts by weight of organic solvent, 0-1 parts by weight of dispersant, 1-10 parts by weight of binder and 0-10 parts by weight of plasticizer.

15. The method for preparing a composite laminate structure for solid-state batteries according to claim 11, wherein, The second slurry comprises 34 to 49 parts by weight of nickel metal, 0 to 2 parts by weight of glass phase material, 50 to 65 parts by weight of organic solvent, 0 to 1 part by weight of dispersant, 1 to 10 parts by weight of binder and 0 to 10 parts by weight of plasticizer.

16. The method for preparing a composite laminate structure for solid-state batteries according to claim 10 or 11, wherein, The dispersant includes at least one of fish oil, triethanolamine, and trioleic acid glyceride.

17. The method for preparing a composite laminate structure for a solid-state battery according to any one of claims 9-16, wherein, The pressure of the hot pressing is 3-12 MPa, and the temperature of the hot pressing is 50-80°C.

18. The method for preparing a composite laminate structure for a solid-state battery according to any one of claims 9-16, wherein, The hot pressing time is 1 to 5 minutes.

19. The method for preparing a composite laminate structure for a solid-state battery according to any one of claims 9-16, wherein, The sintering temperature is 1000–1500℃, and the sintering heating rate is 5–50℃ / min.

20. The method for preparing a composite laminate structure for a solid-state battery according to any one of claims 9-16, wherein, The sintering time is 5 to 15 minutes.

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