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JP-2026514198-A - Oxy halides, methods for producing the same, and all-solid-state lithium batteries

JP2026514198AJP 2026514198 AJP2026514198 AJP 2026514198AJP-2026514198-A

Abstract

This invention provides oxyhalides, a method for producing the same, and an all-solid-state lithium battery. The production method includes step 1, in which a mixture of lithium and boron sources weighed in stoichiometric ratios is polished, formed into a sheet, placed in a reaction tube, the reaction tube is vacuumed and sealed, and a first firing is performed at a temperature of 300 to 450°C for a duration of 4 to 20 hours; and step 2, after the first firing, the mixture is cooled to room temperature, the intermediate product in the reaction tube is removed, further polished, pressed into a sheet, placed in the reaction tube, the reaction tube is vacuumed and sealed, a second firing is performed, and then the mixture is cooled to room temperature. The production method of this invention is simple, has a high utilization rate of raw materials, and does not contain by-products, making it advantageous for industrial production. The oxyhalides produced have high ionic conductivity and stability, and good interfacial stability with metallic lithium. The all-solid-state lithium batteries produced have excellent electrochemical performance. [Selection Diagram] Figure 1

Inventors

  • 黄 富強
  • 曹 宇舸

Assignees

  • 上海交通大学

Dates

Publication Date
20260507
Application Date
20240705
Priority Date
20240407

Claims (10)

  1. A method for producing oxyhalides, The chemical formula of the oxyhalide is Li 3 B 7 O 12 ·(LiX) a , However, X is Cl and/or Br, and 0 < a ≤ 1, Step 1 involves polishing and sheet-pressing a mixture of lithium and boron sources weighed in stoichiometric ratios, placing it in a reaction tube, suctioning the reaction tube into a vacuum, sealing it, and then performing a first firing, with the temperature of the first firing being 300-450°C and the duration of the first firing being 4-20 hours. After the first firing, the reaction tube is cooled to room temperature, the intermediate product in the reaction tube is removed, further polished and sheet-pressed, then placed back into the reaction tube, the reaction tube is vacuumed and sealed, and a second firing is performed. After this, the tube is cooled to room temperature to obtain the oxyhalide. When the lithium source is lithium halide and lithium oxide, and the boron source is boron oxide, the temperature of the second firing is 810 to 860°C, and the duration of the second firing is 12 to 30 hours. In step 2, if the lithium source is lithium halide and lithium borate, and the boron source is boron oxide, the temperature of the second firing is 450 to 800°C, and the duration of the second firing is 12 to 30 hours. A method characterized by including the following.
  2. (1) In step 1 and/or step 2, the pressure of the sheet press is 5 to 15 MPa, (2) In step 1 and/or step 2, the condition is that the reaction tube is a quartz tube, (3) In step 1 and/or step 2, under the condition that after vacuum suction, the vacuum level of the reaction tube is 10⁻³ Pa or less, (4) The lithium borate is lithium metaborate, lithium tetraborate, or lithium pentaborate. (5) The lithium halide is lithium chloride or lithium bromide, (6) The chemical formula of the oxyhalide is such that 0.8 < a < 0.98, A method for producing oxyhalides according to claim 1, characterized by satisfying one or more of the following.
  3. In step 1, the temperature of the first firing is 350 to 450°C. and/or, the method for producing oxyhalides according to claim 1 or 2, characterized in that the time of the first firing in step 1 is 10 to 15 hours.
  4. In step 2, if the lithium source is lithium chloride and lithium oxide, and the boron source is boron oxide, the temperature of the second firing is 835 to 855°C. Furthermore/or, in step 2, if the lithium source is lithium chloride and lithium oxide, and the boron source is boron oxide, the time for the second calcination is 15 to 26 hours. Furthermore/or, in step 2, the lithium source is lithium chloride and lithium oxide, and the boron source is boron oxide, the molar ratio of lithium chloride, lithium oxide and boron oxide is (1.6 to 1.96):3:7, characterized in that the method for producing oxyhalides according to claim 1 or 2.
  5. In step 2, if the lithium source is lithium chloride and lithium borate, and the boron source is boron oxide, the temperature of the second firing is 480 to 610°C. Furthermore/or, in step 2, if the lithium source is lithium chloride and lithium borate, and the boron source is boron oxide, the time for the second calcination is 15 to 26 hours. Furthermore/or, in step 2, the lithium source is lithium chloride and lithium borate, the boron source is boron oxide, and the lithium borate is lithium metaborate, characterized in that the molar ratio of lithium chloride, lithium borate and boron oxide is (0.8 to 0.98):3:2, as described in claim 1 or 2.
  6. An oxyhalide produced by the method for producing an oxyhalide described in any one of claims 1 to 5, characterized in that its ionic conductivity at 25°C is 0.2 to 2 mS· cm⁻¹ .
  7. An all-solid-state lithium battery comprising, in order, a positive electrode, a solid electrolyte layer, a buffer layer, and a negative electrode, A battery characterized in that the positive electrode includes a positive electrode current collector and a positive electrode active material layer located on the surface of the positive electrode current collector, the positive electrode active material layer includes LiFePO4 and the oxyhalide described in claim 6, the solid electrolyte layer includes the oxyhalide described in claim 6, the buffer layer includes Li6PS5Cl , and the negative electrode includes a negative electrode current collector and a negative electrode active material layer located on the surface of the negative electrode current collector.
  8. (1) In the positive electrode active material layer, the mass ratio of LiFePO4 to the oxyhalide is (2 to 5):1. (2) The condition that the thickness of the positive electrode active material layer is 50 to 500 μm, (3) The condition that the thickness of the solid electrolyte layer is 100 to 1000 μm, (4) The condition that the thickness of the buffer layer is 100 to 1000 μm, (5) The condition that the thickness of the negative electrode active material layer is 50 to 500 μm, The all-solid-state lithium battery according to claim 7, characterized in that it satisfies one or more of the following conditions.
  9. A method for manufacturing an all-solid-state lithium battery according to claim 7 or 8, A step of performing a first press on the material of the solid electrolyte layer of the all-solid-state lithium battery to obtain the solid electrolyte layer, A step of adding the buffer layer material of the all-solid-state lithium battery to one side of the solid electrolyte layer and performing a second press to obtain the buffer layer, A step of adding the material for the positive electrode active layer of the all-solid-state lithium battery to the other side of the solid electrolyte layer and performing a third press to obtain the positive electrode active layer, A step to obtain the all-solid-state lithium battery by adding the material for the negative electrode active layer of the all-solid-state lithium battery to one side of the buffer layer and performing a fourth press, A method characterized by including the following.
  10. (1) Conditions including the process of performing a fifth press after the fourth press, by placing the positive electrode current collector on one side of the positive electrode active material layer and the negative electrode current collector on one side of the negative electrode active material layer, (2) Under the condition that the pressure of the first press is 300 to 500 MPa, (3) The condition that the pressure of the second press is 200 to 400 MPa, (4) The condition that the pressure of the third press is 200 to 400 MPa, (5) The condition that the pressure of the fourth press is 200 to 400 MPa, (6) Under the condition that the pressure of the fifth press is 60 to 180 MPa, A method for manufacturing an all-solid-state lithium battery according to claim 9, characterized in that it satisfies one or more of the following conditions.

Description

This invention relates to oxyhalides, a method for producing the same, and all-solid-state lithium batteries. All-solid-state lithium batteries are attracting attention due to their simple structure, high safety, and high energy density. Because they use a solid electrolyte instead of liquid electrolyte and separator, they are thinner and smaller in volume, improving energy density and safety. Therefore, research and development of all-solid-state lithium batteries as an alternative to conventional lithium-ion batteries is of great significance. However, all-solid-state lithium batteries have the following problems: (1) how to satisfy the transport problems between the positive and negative electrodes and electrolyte ions; (2) the positive and negative electrodes cannot maintain very good contact like liquids during the circulation process; and (3) metallic lithium is prone to dendritic crystal formation during the charge and discharge process. The existence of these problems results in inferior electrochemical performance of all-solid-state lithium batteries, which is detrimental to their practical application and development. The core of all-solid-state lithium batteries lies in the compound used as the solid electrolyte. Currently, both organic and inorganic compounds have been reported to be excellent electrolytes, and inorganic solid electrolytes have higher ionic conductivity and stability compared to organic solid electrolytes. To date, inorganic solid electrolyte materials have been divided into sulfides, oxides, and halides. Sulfide solid electrolytes have high ionic conductivity (> 10⁻³ S· cm⁻¹ ), but are affected by moisture in the surrounding atmosphere, leading to harmful hydrolysis reactions and a significant decrease in ionic conductivity. Furthermore, sulfides have poor oxidation stability, severely limiting their direct use as high-pressure cathode materials. Oxide solid electrolytes have high air and thermal stability, low manufacturing costs, and are easy to produce on a large scale, but their mechanical rigidity can lead to poor contact at the interface with the electrode material, requiring high-temperature processes or the inflow of liquid electrolyte for battery assembly. Halide solid electrolytes have high ionic conductivity (> 10⁻³ S· cm⁻¹ ) at room temperature, but still face problems with deliquescence and poor stability. In oxyhalide materials, the bonding of divalent oxygen ions and halogen ions maintains both the polarity of the halogen and the high bonding energy of oxygen, offering greater potential for the future exploration of new electrolyte materials. Furthermore, it has been reported that Li₄B₃O₁₂Cl exhibits high ionic conductivity at 300 ° C . However, previous reports indicate that a series of byproducts, such as Li₂B₄O₂Cl, can be produced during the synthesis process of Li₄B₃O₁₂Cl , which to some extent degrades the conductivity and electrochemical properties of Li₄B₃O₁₂Cl . Therefore, research and development of oxyhalide materials that are pure phases and possess excellent conductivity and electrochemical properties is of great significance to the field of batteries. This is an SEM image of the oxyhalide Li₄B₃O₁₂Clproducedin Example 1.These are the XRD spectra of the oxyhalides produced in Examples 1-2 and Comparative Examples 5-7.These are the XRD spectra of the oxyhalides produced in Examples 3-5 and Comparative Example 1.