Oxide solid-state electrolyte, solid-state electrolyte membrane, and preparation method, preparation device, and solid-state battery

Abstract

This invention relates to the field of battery technology, and in particular to an oxide solid electrolyte, a solid electrolyte membrane, a preparation method, a preparation apparatus, and a solid-state battery. The preparation method includes the following steps: S1: high-temperature sintering of the oxide solid electrolyte raw material; S2: secondary annealing of the product of step S1. The technical solution of this application can utilize existing float glass preparation equipment (melting furnace section and annealing furnace section) to prepare the solid electrolyte. The melting furnace section provides a closed high-temperature environment, which can efficiently realize the melting, blending, and reaction of the solid electrolyte. Further annealing yields a crystalline solid electrolyte, and the uniform deposition and performance enhancement of the electrolyte film are achieved through roll forming technology.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to an oxide solid electrolyte, a solid electrolyte membrane, a preparation method, a preparation apparatus, and a solid battery. Background Technology

[0002] In recent years, new energy vehicles have experienced rapid development due to their advantages such as low carbon emissions, environmental friendliness, and high energy efficiency. By 2024, the global market penetration rate of new energy vehicles had exceeded 45%, and the installed capacity of lithium-ion batteries, their core power source, had subsequently climbed to the thousands of GWh level. However, the energy density and safety bottlenecks of current lithium-ion batteries are becoming increasingly prominent, and solid-state batteries, due to their high energy density (>400 Wh / kg) and inherent safety, are considered a key breakthrough direction for next-generation battery technology.

[0003] Oxide solid-state electrolytes, as one of the core material systems of solid-state batteries, mainly include garnet-type electrolytes (such as LLZO, i.e., Li7La3Zr2O). 12 ), NASICON type (such as LATP, i.e., Li 1.3 Al 0.3 Ti 1.7 (PO4)3) and perovskite types, etc. These materials possess excellent chemical stability and high ionic conductivity (some reaching 10). -3 Solid-state electrolytes (SO4) offer advantages such as high density (on the order of S / cm) and a wide electrochemical window. However, their industrial application still faces two major challenges: first, their intrinsic brittleness leads to poor solid-solid interface contact and high interfacial impedance between the electrolyte and electrode; second, traditional preparation processes (such as high-temperature sintering) struggle to achieve both high densification and low energy consumption, and large-area, continuous thin-film preparation is difficult to achieve, thus limiting production efficiency and cost control. Therefore, developing a new method and device for the continuous and efficient preparation of high-performance oxide solid-state electrolytes is crucial for promoting the commercialization of solid-state battery technology. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings and defects of the prior art and to provide an oxide solid electrolyte, a solid electrolyte membrane, a preparation method, a preparation apparatus, and a solid battery.

[0005] To achieve the above objectives, this application adopts the following solution: A method for preparing an oxide solid electrolyte includes the following steps: S1: high-temperature sintering of the oxide solid electrolyte raw material; S2: secondary annealing of the product of step S1.

[0006] The oxide solid electrolyte is a garnet-type solid electrolyte; preferably LLZO or metal-doped LLZO; preferably, the doping element of the metal-doped LLZO is Al; Preferably, step S1 is as follows: Li2CO3, La2O3 and ZrO2 are mixed in a certain proportion and sintered at 1300–1500℃ to form cubic garnet structure LLZO or metal-doped LLZO; preferably, the molar ratio of Li2CO3, La2O3 and ZrO2 is 3.5:1.5:2. Preferably, step S2 involves annealing in a Li2O atmosphere at 1100–1200°C.

[0007] In step S1, the oxide solid electrolyte is a NASICON-type solid electrolyte; preferably LATP. Preferably, step S1 involves mixing Li₂CO₃, Al₂O₃, TiO₂, and NH₄H₂PO₄ in a specific ratio, pre-firing at 600-800℃, preferably 700℃, followed by high-temperature sintering at 850-1050℃, preferably 900-1000℃, and more preferably 950℃ to form a NASICON structure Li. 1.3 Al 0.3 Ti 1.7 (PO4)3); preferably, the molar ratio of Li2CO3, Al2O3, TiO2, and NH4H2PO4 is 0.65:0.15:1.70:3.00; Preferably, step S2 specifically involves low-temperature annealing at 500-600℃ to eliminate residual stress.

[0008] When preparing the oxide solid electrolyte as a NASICON-type solid electrolyte, the process also includes step S3: waste treatment stage, which includes: 1. Treating the NH3 and H3PO4 vapors during the pre-calcination and high-temperature sintering processes with a two-stage spray tower. Preferably, the first stage sprays acidic solution, preferably a 5% H2SO4 solution to absorb NH3; the second stage sprays alkaline solution, preferably a 10% NaOH solution to neutralize the phosphoric acid vapors; 2. Extracting lithium from the sintering residue during high-temperature sintering by acid leaching and calcining the recovered residue to generate TiO2-Al2O3 multiphase material.

[0009] The present invention also includes an oxide solid electrolyte obtained by the preparation method described above.

[0010] The present invention also includes an apparatus for preparing the oxide solid electrolyte, comprising a raw material processing section, a calcination section, an annealing section, and a post-processing section; preferably, the calcination section and the annealing section are the melting furnace section and the annealing furnace section of a float glass preparation apparatus.

[0011] The present invention also includes a method for preparing an oxide solid electrolyte membrane, comprising the following steps: rolling the oxide solid electrolyte into a membrane, and then winding and cutting it.

[0012] The specific steps for roll forming are as follows: film formation by casting or hot pressing; the conditions for hot pressing are 200-300℃ and 100MPa; preferably, diamond wire cutting or ultraviolet laser cutting can be used during the winding process.

[0013] The present invention also includes an oxide solid electrolyte membrane obtained by the preparation method described above.

[0014] The present invention also includes a solid-state battery, comprising the oxide solid-state electrolyte or the oxide solid-state electrolyte membrane.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The technical solution of this application can use existing float glass preparation equipment (melting furnace section and annealing furnace section) to prepare solid electrolytes. The melting furnace section provides a closed high-temperature environment, which can efficiently realize the melting, blending and reaction of solid electrolytes. Crystalline solid electrolytes are obtained through further annealing, and uniform deposition and performance enhancement of electrolyte films are achieved through roll forming film technology. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating Embodiment 2 of the present invention. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0018] Example 1: 1. A method for preparing LLZO oxide electrolyte, comprising the following steps: S1: High-temperature sintering of oxide solid electrolyte raw materials. Li2CO3:La2O3:ZrO2 is mixed according to a precise stoichiometric ratio (Li2CO3:La2O3:ZrO2 = 3.5:1.5:2, with a 10% excess lithium source to compensate for volatilization). After mixing in a mixer, the mixture is fed into the melting furnace section of the float glass preparation apparatus for high-temperature sintering and melting reaction. Sintering is carried out in a closed high-temperature environment at 1300-1500℃, specifically 1400℃ in this embodiment, to allow the raw materials to fully react and melt, directly forming the LLZO crystal phase with a cubic garnet structure.

[0019]

[0020] This step can be used to perform Al doping to improve ionic conductivity and obtain metal-doped LLZO. The reaction formula is as follows:

[0021] S2: The product from step S1 undergoes a second annealing (corresponding to the annealing furnace section of float glass).

[0022] The sintered LLZO material is continuously fed into the annealing furnace section. Secondary annealing is performed in a Li₂O atmosphere at a temperature of 1100-1200℃, specifically 1150℃ in this embodiment. The purpose of this process is to eliminate the internal stress generated by high-temperature sintering, improve the mechanical strength of the material, promote further grain growth and densification, optimize the grain boundary structure, thereby improving ionic conductivity, and stabilize the cubic phase structure to prevent transformation to the poorly conductive tetragonal phase.

[0023] 2. Preparation of oxide solid electrolyte membranes: LLZO oxide electrolyte solid oxide roll forming: LLZO electrolyte strips that have undergone sufficient annealing and have a stable structure are rolled using a precisely controlled roll press. Depending on the requirements, a uniform thickness (e.g., 20-50 μm) and dense flexible or rigid electrolyte film can be produced using either a casting method (with a small amount of binder added) or a hot pressing method (200-300℃, 100 MPa).

[0024] Winding and Precision Cutting (Post-processing Section): The electrolyte membrane after film formation enters the post-processing section. Winding is performed in a constant temperature and humidity environment, with a tension control system maintaining membrane surface flatness during the winding process. Diamond wire cutting or ultraviolet laser cutting technology is used to cut the continuous film strip into specific dimensions that meet battery assembly requirements.

[0025] 3. Waste Treatment and Resource Utilization (Green Manufacturing): Trace amounts of alkaline gases that may be generated during sintering can be purified through the alkaline neutralization system in the post-treatment section. Solid waste such as scraps generated during cutting can be collected, crushed, and reused as raw materials in the first batching process, achieving resource recycling.

[0026] The present invention also includes an apparatus for preparing an oxide solid electrolyte that is a garnet-type solid electrolyte, comprising a raw material processing section, a calcination section (corresponding to the melting furnace section of a float glass preparation apparatus), an annealing section (corresponding to the melting furnace section of a float glass preparation apparatus), and a post-treatment section (including a waste liquid treatment unit, specifically an alkali neutralization system).

[0027] Example 2: 1. A method for preparing LATP oxide electrolyte, comprising the following steps ( Figure 1 (As shown): S1, high-temperature sintering of oxide solid electrolyte raw materials; including pretreatment, mixing Li2CO3, Al2O3, TiO2, and NH4H2PO4 in stoichiometric ratios (0.65:0.15:1.70:3.00), with precise control of the Al / Ti ratio (0.3:1.7). The mixture is then mixed in a mixer to reduce the particle size and improve sintering activity. Pre-firing (600-800℃, 700℃ for 3 hours in this example) decomposes NH4H2PO4 into PO4. 3- This avoids the volatilization of phosphates at high temperatures and simultaneously forms titanium aluminum oxide precursors.

[0028]

[0029]

[0030] After sintering in the melting furnace section (950℃, air atmosphere), a NASICON-type structure (LATP) is formed, Al 3+ Occupying Ti sites, the ionic conductivity reaches 1×10 -3 S / cm, the overall reaction equation is:

[0031]

[0032] S2, the product from step S1 is subjected to a second annealing.

[0033] It is directly fed into the annealing furnace section because it can directly form a stable crystalline phase after sintering. Low-temperature annealing (500–600℃, 550℃ in this example) eliminates residual stress and improves mechanical strength (flexural strength > 100 MPa).

[0034] Comparative Example 1 (sintering temperature 850℃) The only difference from Example 2 is that the high-temperature sintering temperature is 850℃; all other steps and parameters are the same. The resulting product has insufficient crystallization, obvious impurity phases, low density, and an ionic conductivity of ≈2×10⁻⁶. -4 S / cm, flexural strength <60MPa.

[0035] Comparative Example 2 (sintering temperature 900℃) The only difference from Example 2 is that the high-temperature sintering temperature is 900℃, while all other steps and parameters are the same. The resulting product is essentially a pure phase, still containing a small amount of residual precursor, with moderate density and an ionic conductivity of ≈6×10⁻⁶. -4 S / cm, flexural strength ≈ 80 MPa.

[0036] Comparative Example 3 (sintering temperature 1000℃) The only difference from Example 2 is that the high-temperature sintering temperature is 1000℃; all other steps and parameters are the same. The resulting product is a pure phase, but slight lithium and phosphate volatilization occurs, the grains are relatively large, and the ionic conductivity is approximately 9 × 10⁻⁶. -4 S / cm, flexural strength ≈90 MPa.

[0037] Comparative Example 4 (sintering temperature 1050℃) The only difference from Example 2 is that the high-temperature sintering temperature is 1050℃; all other steps and parameters are the same. The product suffered severe lithium loss, exhibited impurity phases, had an inhomogeneous structure, and had an ionic conductivity ≈ 3 × 10⁻⁶. -4 With a strength of S / cm and a flexural strength of <50 MPa, it cannot meet the requirements for film formation and use.

[0038] The performance of the electrolytes obtained in Example 2 and Comparative Examples 1–4 was tested, and the results are shown in Table 1. It should be noted that the comparative examples in this application are also part of the examples.

[0039] Table 1

[0040] Therefore, the LATP electrolyte obtained by sintering at 950℃ in this invention has a pure crystal phase, high density, and optimal ionic conductivity and mechanical properties; if the temperature is too low, crystallization will be insufficient and the performance will be low; if the temperature is too high, lithium and phosphate will volatilize, and the performance will be significantly degraded.

[0041] 2. Preparation of oxide solid electrolyte membranes: LATP oxide electrolyte is rolled into a film after passing through an annealing section: casting or rolling process, combined with polymer binder (such as PVDF, added at 5-10 wt%) to form a flexible composite film (thickness 20-50 μm).

[0042] Winding and Cutting. The flexible composite film, after roll forming, enters a constant temperature and humidity winding system (temperature 25±2℃, humidity <30%), driven by a servo motor for precise tension control (2-5N) to prevent wrinkles or stretching deformation of the film layer. Before winding, the film surface is simultaneously scanned by an online optical inspection system (CCD resolution 10μm) to remove defective sections containing air bubbles or uneven thickness. Cutting is performed using ultraviolet laser combined with nitrogen blowing to achieve burr-free slitting, obtaining film rolls with a width of 100-300mm and a length of 500-1000m, with an edge flatness <Ra 1.2μm. Cutting waste (approximately 2-3%) is crushed and mixed with raw materials at a 1:9 ratio, and then processed through a hot-pressing regeneration process to produce secondary film materials for low-end battery encapsulation.

[0043] 3. Disposal of waste.

[0044] (1) Acid gas purification: NH3 and H3PO4 vapors generated in the pre-calcination and sintering sections are treated by a two-stage spray tower: the first stage spray (5% H2SO4 solution) absorbs NH3:

[0045] Secondary spraying (10% NaOH solution) to neutralize phosphoric acid vapor:

[0046] (2) Dust recovery: Titanium-aluminum dust from the cutting and crushing section is collected by bag filter (filtration accuracy 0.1μm) and used as ceramic filler in building material production.

[0047] (3) Phosphate-containing waste residue: sintering residue (containing Li) 1.3 Al 0.3 Ti 1.7 (PO4)3) Lithium was extracted by acid leaching (2 mol / L HCl, 80℃):

[0048] The lithium extraction rate is >85%, and the residue is calcined (800℃) to generate TiO2-Al2O3 multiphase material, which is used as a catalyst support.

[0049] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. In summary, the technical solution of this application can prepare solid electrolytes using existing float glass preparation equipment (calcination section and annealing section). The calcination section provides a closed high-temperature environment, which can efficiently realize the melting, blending and reaction of solid electrolytes. Crystalline solid electrolytes are obtained through further annealing, and uniform deposition and performance enhancement of electrolyte films are achieved through roll forming technology.

[0050] Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of the equivalents of the claims be included within the invention.

[0051] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing an oxide solid electrolyte, characterized in that, The process includes the following steps: S1: High-temperature sintering of oxide solid electrolyte raw materials; S2: Secondary annealing of the product from step S1.

2. The method for preparing the oxide solid electrolyte according to claim 1, characterized in that, The oxide solid electrolyte is a garnet-type solid electrolyte; preferably LLZO or metal-doped LLZO; preferably, the doping element of the metal-doped LLZO is Al; Preferably, step S1 is as follows: Li2CO3, La2O3 and ZrO2 are mixed in a certain proportion and sintered at 1300–1500℃ to form cubic garnet structure LLZO or metal-doped LLZO; preferably, the molar ratio of Li2CO3, La2O3 and ZrO2 is 3.5:1.5:

2. Preferably, step S2 involves annealing in a Li2O atmosphere at 1100–1200°C.

3. The method for preparing the oxide solid electrolyte according to claim 1, characterized in that, In step S1, the oxide solid electrolyte is a NASICON-type solid electrolyte; preferably LATP. Preferably, step S1 involves mixing Li₂CO₃, Al₂O₃, TiO₂, and NH₄H₂PO₄ in a specific ratio, pre-firing at 600-800℃, preferably 700℃, followed by high-temperature sintering at 850-1050℃, preferably 900-1000℃, and more preferably 950℃ to form a NASICON structure Li. 1.3 Al 0.3 Ti 1.7 (PO4)3; preferably, the molar ratio of Li2CO3, Al2O3, TiO2, and NH4H2PO4 is 0.65:0.15:1.70:3.00; Preferably, step S2 specifically involves low-temperature annealing at 500-600℃ to eliminate residual stress.

4. The method for preparing the oxide solid electrolyte according to claim 3, characterized in that, It also includes step S3: waste treatment stage, including 1. treating NH3 and H3PO4 vapors in the pre-calcination and high-temperature sintering process with a two-stage spray tower. Preferably, the first stage sprays acidic solution, preferably 5% H2SO4 solution to absorb NH3; the second stage sprays alkaline solution, preferably 10% NaOH solution to neutralize phosphoric acid vapor; 2. extracting lithium from the sintering residue in the high-temperature sintering process by acid leaching and recovering the residue by calcining to generate TiO2-Al2O3 multiphase material.

5. An oxide solid electrolyte obtained by the preparation method according to any one of claims 1-4.

6. An apparatus for preparing an oxide solid electrolyte as described in claim 5, characterized in that, It includes a raw material processing section, a calcination section, an annealing section, and a post-processing section; preferably, the calcination section and the annealing section are the melting furnace section and the annealing furnace section of the float glass preparation apparatus.

7. A method for preparing an oxide solid electrolyte membrane, characterized in that, The process includes the following steps: rolling the oxide solid electrolyte of claim 5 into a film, and then winding and cutting it.

8. The method for preparing an oxide solid electrolyte membrane according to claim 7, characterized in that, The specific steps for roll forming are as follows: film formation by casting or hot pressing; the conditions for hot pressing are 200-300℃ and 100 MPa; preferably, diamond wire cutting or ultraviolet laser cutting can be used during the winding process.

9. An oxide solid electrolyte membrane obtained by the preparation method according to claim 7 or 8.

10. A solid-state battery, characterized in that, It includes the oxide solid electrolyte as described in claim 5 or the oxide solid electrolyte membrane as described in claim 9.

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