Preparation method for solid-state electrolyte containing oxygen vacancies and solid-state battery

Abstract

A preparation method for a solid-state electrolyte containing oxygen vacancies, and a solid-state battery. The preparation method for a solid-state electrolyte containing oxygen vacancies comprises: mixing a carbon material and an oxide solid-state electrolyte to obtain a mixed material, and performing heat treatment on the mixed material to prepare a solid-state electrolyte containing oxygen vacancies. The carbon material and the oxide solid-state electrolyte are subjected to heat treatment to prepare the solid-state electrolyte containing oxygen vacancies. In the solvent-free preparation method for obtaining the solid-state electrolyte containing oxygen vacancies, the carbon material is converted into carbon dioxide in the heat treatment process, such that the solid-state electrolyte can give full play to the advantages of oxygen vacancies so as to improve the ionic conductivity of the solid-state electrolyte and minimize the negative effect of the heat treatment process on the performance of the solid-state electrolyte.

Description

Preparation method of solid electrolyte containing oxygen vacancies and solid-state battery

[0001] Cross-references

[0002] This application refers to Chinese patent application No. 202410365294.1, filed on March 28, 2024, entitled “Preparation method of solid electrolyte containing oxygen vacancies and solid-state battery”, which is incorporated into this application in its entirety by reference. Technical Field

[0003] The present application relates to the technical field of secondary batteries, and in particular to a method for preparing a solid electrolyte containing oxygen vacancies, a solid electrolyte containing oxygen vacancies, a solid-state battery, and an electrical device. Background Art

[0004] Driven by the need for energy conservation and emission reduction, batteries are increasingly being used. They are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in aerospace and other fields.

[0005] Solid-state batteries use solid electrolytes. The use of solid electrolytes significantly improves battery safety and energy density. The performance of solid electrolytes has a critical impact on the electrochemical performance of solid-state batteries. Further improving the performance of solid electrolytes is a pressing technical challenge facing those skilled in the art.

[0006] The approaches described in this section are not necessarily approaches that have been previously conceived or employed. Unless otherwise indicated, it should not be assumed that any approach described in this section is prior art simply by virtue of its inclusion in this section. Similarly, unless otherwise indicated, the issues raised in this section should not be considered as having been recognized in any prior art.

[0007] Summary of the Invention

[0008] The present application is made in view of the above-mentioned demands, and its purpose is to provide a method for preparing a solid electrolyte containing oxygen vacancies, a solid electrolyte containing oxygen vacancies, a solid-state battery, and an electrical device.

[0009] A first aspect of the present application provides a method for preparing a solid electrolyte containing oxygen vacancies, comprising: mixing a carbon material and an oxide solid electrolyte to obtain a mixed material, and heat-treating the mixed material to prepare a solid electrolyte containing oxygen vacancies.

[0010] The second aspect of the present application provides a solid electrolyte containing oxygen vacancies, wherein the solid electrolyte containing oxygen vacancies is prepared by the preparation method described in the first aspect of the present application.

[0011] The third aspect of the present application provides a solid-state battery, comprising a solid electrolyte containing oxygen vacancies prepared by the preparation method of the first aspect or a solid electrolyte containing oxygen vacancies prepared by the preparation method of the second aspect.

[0012] The fourth aspect of the present application provides an electrical device comprising the solid-state battery of the third aspect of the present application.

[0013] This application uses carbon materials and oxide solid electrolytes for heat treatment to prepare a solid electrolyte containing oxygen vacancies. The solid electrolyte containing oxygen vacancies is obtained through a solvent-free preparation method. The carbon material is converted into carbon dioxide during the heat treatment process, so that the solid electrolyte can fully utilize the advantages of oxygen vacancies to improve the ionic conductivity of the solid electrolyte while minimizing the negative impact of the heat treatment process on the performance of the solid electrolyte. DETAILED DESCRIPTION

[0014] The following embodiments of the technical solution of the present application are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only used as examples and are not intended to limit the scope of protection of the present application.

[0015] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description and claims of this application are intended to cover non-exclusive inclusions.

[0016] In the description of the embodiments of this application, the technical terms "first," "second," etc. are used only to distinguish different objects and should not be understood to indicate or imply relative importance or to implicitly indicate the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise specifically defined.

[0017] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0018] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0019] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0020] It should be understood that in this specification, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships or dimensions are schematic orientations or positional relationships or dimensions, and these terms are used only for the convenience of description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of this application.

[0021] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0022] A first aspect of the present application provides a method for preparing a solid electrolyte containing oxygen vacancies, comprising: mixing a carbon material and an oxide solid electrolyte to obtain a mixed material, and heat-treating the mixed material to prepare a solid electrolyte containing oxygen vacancies.

[0023] Oxygen vacancies refer to vacancies formed when oxygen atoms (oxygen ions) in the crystal lattice of metal oxides or other oxygen-containing compounds are separated, resulting in the loss of oxygen. Simply put, oxygen vacancies refer to defects left behind by the escape of oxygen ions from their crystal lattice. Oxygen vacancies are one of the most common defects in metal oxides. Solid electrolytes mainly include sulfide solid electrolytes, oxide solid electrolytes and polymer solid electrolytes. For oxide solid electrolytes, ion transport usually depends on the concentration and distribution of defects. The ion diffusion mechanisms based on Schottky defects and Frenkel point defects include simple vacancy mechanisms and relatively complex diffusion mechanisms, such as divacancy mechanisms, interstitial mechanisms, interstitial substitution exchange mechanisms and collective mechanisms. The presence of oxygen vacancies facilitates the conduction of lithium ions and can improve the ionic conductivity of solid electrolytes.

[0024] However, the common method of introducing oxygen vacancies is usually liquid-phase reduction, which inevitably requires the introduction of solvents, and the solvent treatment history has a negative impact on the performance of solid electrolytes. This application creatively uses carbon materials and oxide solid electrolytes for heat treatment to prepare solid electrolytes containing oxygen vacancies. A solid electrolyte containing oxygen vacancies is obtained through a solvent-free and residue-free preparation method. The carbon material is converted into carbon dioxide during the heat treatment process, so that the solid electrolyte can give full play to the advantages of oxygen vacancies and improve the ionic conductivity of the solid electrolyte while minimizing the negative impact of the heat treatment process on other properties of the solid electrolyte.

[0025] In some embodiments, the mass ratio of the carbon material to the solid electrolyte is 0.1:100-2:100.

[0026] In some embodiments, the mass ratio of carbon material to solid electrolyte may be 0.1:100, 0.2:100, 0.3:100, 0.4:100, 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, 1:100, 1.1:100, 1.2:100, 1.3:100, 1.4:100, 1.5:100, 1.6:100, 1.7:100, 1.8:100, 1.9:100, 2.0:100 or any range therebetween.

[0027] The mass ratio of carbon material to oxide solid electrolyte within the above range can not only increase the oxygen vacancy content of the solid electrolyte and improve the ionic conductivity of the solid electrolyte, but also reduce the negative impact of incomplete reaction of the carbon material on the ionic conductivity of the solid electrolyte.

[0028] In some embodiments, the carbon material includes one or more of conductive carbon black, graphite, graphene, and carbon nanotubes.

[0029] In some embodiments, the solid electrolyte includes one or more of lithium lanthanum zirconium oxide (LLZO), lithium aluminum titanium phosphate (LATP), lithium lanthanum titanate (LLTO), and modified materials thereof.

[0030] The modified materials include materials prepared by any modification method, including but not limited to doped modified materials and coated modified materials.

[0031] In some embodiments, the oxide solid state electrolyte comprises a tantalum-doped lithium lanthanum zirconium oxide electrolyte (LLZTO).

[0032] Lithium lanthanum zirconium oxide electrolytes are garnet-type electrolytes and are very sensitive to solvents. The preparation method provided in the embodiments of this application is particularly suitable for preparing oxygen vacancies in garnet-type electrolytes. Tantalum-doped lithium lanthanum zirconium oxide electrolytes have high ionic conductivity, and the preparation method provided in the embodiments of this application can further improve the ionic conductivity of the electrolyte.

[0033] In some embodiments, the temperature of the heat treatment is 1100°C to 1400°C.

[0034] In some embodiments, the temperature of the heat treatment may be 1100° C., 1200° C., 1300° C., 1400° C., or any range therebetween.

[0035] In some embodiments, the heat treatment time is from 1 / 6 hour to 12 hours.

[0036] In some embodiments, the heat treatment time can be selected as 1 / 6 hour, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours or any range therebetween.

[0037] In some embodiments, the heating rate of the heat treatment is 1° C. / min-20° C. / min.

[0038] In some embodiments, the heating rate of the heat treatment can be selected as 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, 11°C / min, 12°C / min, 13°C / min, 14°C / min, 15°C / min, 16°C / min, 17°C / min, 18°C / min, 19°C / min, 20°C / min or any numerical range therebetween.

[0039] In some embodiments, the heat treatment environment is an inert atmosphere.

[0040] In some embodiments, the inert atmosphere includes one or more of nitrogen, helium, neon, and argon.

[0041] In some embodiments, the solid electrolyte containing oxygen vacancies has a lithium ion conductivity of 0.8 mS / cm to 1.6 mS / cm.

[0042] In some embodiments, the lithium ion conductivity of the solid electrolyte containing oxygen vacancies can be selected from 0.8 mS / cm, 0.9 mS / cm, 1.0 mS / cm, 1.1 mS / cm, 1.2 mS / cm, 1.3 mS / cm, 1.4 mS / cm, 1.5 mS / cm, 1.6 mS / cm, or any range therebetween.

[0043] The second aspect of the present application provides a solid electrolyte containing oxygen vacancies, wherein the solid electrolyte containing oxygen vacancies is prepared by the preparation method of the first aspect of the present application.

[0044] The third aspect of the present application provides a solid-state battery, comprising a solid electrolyte containing oxygen vacancies prepared by the preparation method of the first aspect of the present application or provided by the second aspect of the present application.

[0045] In some embodiments, the solid-state battery also includes a positive electrode plate, which includes a positive electrode active material. The positive electrode active material can be selected from one or more of lithium cobalt oxide, lithium manganese oxide, nickel manganese material, lithium iron phosphate, nickel cobalt manganese, nickel cobalt aluminum ternary material and sulfur-containing material.

[0046] In some embodiments, the solid-state battery further includes a negative electrode plate, which includes a negative electrode active material. The negative electrode active material can be one or more of lithium metal, hard carbon, soft carbon, silicon material and tin material.

[0047] The fourth aspect of the present application provides an electrical device, comprising the solid-state battery provided in the third aspect of the present application.

[0048] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present application. Therefore, the description is considered to be illustrative and non-restrictive in nature.

[0049] Example

[0050] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0051] 1. Preparation method

[0052] Example 1

[0053] 1) Preparation of solid electrolytes containing oxygen vacancies

[0054] LiOH, La2O3, ZrO2 and Ta2O5 were weighed according to the stoichiometric ratio of 7.0:1.5:1.4:0.6 to prepare Li 6.4 La3Zr 1.4 Ta 0.6 O 12 , where the lithium source content needs to be added in excess of 10% compared to the theoretical content. After fully mixing the configured raw materials, place them in a ball mill, add an appropriate amount of isopropanol, and ball mill at a speed of 350rpm for 12 hours. After drying, place the mixed sample raw materials in a tube furnace for high-temperature sintering. The high-temperature sintering conditions are 1150℃ for 10 hours and a heating rate of 5℃ / min. After the reaction is completed, place the sample in a tube furnace and cool it naturally to take out the product. Place the product in a zirconia ball mill, add an appropriate amount of isopropanol, and ball mill at a speed of 350rpm for 12 hours to refine the powder. After the powder is dried, it is screened to obtain LLZTO (Li 6.4 La3Zr 1.4 Ta 0.6 O 12 )powder.

[0055] LLZTO powder and graphene (carbon material) were placed in a tube furnace at a mass ratio of 100:0.25 and heat-treated at 1150°C in an argon atmosphere for 12 hours at a heating rate of 10°C / min. The sample was then allowed to cool naturally in the tube furnace. Argon was maintained throughout the cooling process to prevent oxidation of the sample at high temperatures. After cooling, the LLZTO powder, which had surface oxygen vacancies, was ultrasonically dispersed to prevent agglomeration.

[0056] The LLZTO powder with surface oxygen vacancies was placed in a mold for uniaxial tableting. The obtained solid electrolyte ceramic sheet was sintered at high temperature under argon. The reaction conditions were 1150 °C, the sintering time was 10 hours, and the heating rate was 4 °C min -1 The cooled solid electrolyte ceramic sheet was polished to make its surface smooth, and then the prepared solid electrolyte ceramic sheet was used for impedance testing.

[0057] Example 2

[0058] The preparation method of the battery of Example 2 is basically the same as that of Example 1, except that in Example 2, the mass ratio of tantalum-doped lithium lanthanum zirconium oxide electrolyte (LLZTO) powder to graphene carbon material is 100:0.5.

[0059] Example 3

[0060] The preparation method of the battery of Example 3 is basically the same as that of Example 1, except that in Example 3, the mass ratio of tantalum-doped lithium lanthanum zirconium oxide electrolyte (LLZTO) powder to graphene carbon material is 100:1.

[0061] Example 4

[0062] The preparation method of the battery of Example 4 is basically the same as that of Example 1, except that in Example 4, the mass ratio of tantalum-doped lithium lanthanum zirconium oxide electrolyte (LLZTO) powder to graphene carbon material is 100:1.5.

[0063] Example 5

[0064] The preparation method of the battery of Example 5 is basically the same as that of Example 1, except that in Example 5, the mass ratio of tantalum-doped lithium lanthanum zirconium oxide electrolyte (LLZTO) powder to graphene carbon material is 100:2.

[0065] Example 6

[0066] The preparation method of the battery of Example 6 is basically the same as that of Example 1, except that the type of solid electrolyte is different. The solid electrolyte in Example 6 is lithium aluminum titanium phosphate (LATP).

[0067] LATP powder and graphene (carbon material) were placed in a tube furnace at a mass ratio of 100:0.25 and heat-treated at 1150°C in an argon atmosphere for 12 hours at a heating rate of 10°C / min. The sample was then allowed to cool naturally in the tube furnace. Argon was maintained throughout the cooling process to prevent oxidation of the sample at high temperatures. After cooling, the LATP powder, which contained surface oxygen vacancies, was ultrasonically dispersed to prevent agglomeration.

[0068] The LATP powder with surface oxygen vacancies was placed in a mold for uniaxial pressing. The obtained solid electrolyte ceramic sheet was sintered at high temperature under argon. The reaction conditions were 1150 ° C, sintering time was 10 hours, and the heating rate was 4 ° C min -1 After cooling, the solid electrolyte membrane is polished to make its surface smooth.

[0069] Example 7

[0070] The preparation method of the battery of Example 7 is basically the same as that of Example 1, except that the type of carbon material is different. The carbon material in Example 7 is carbon nanotubes.

[0071] Example 8

[0072] The preparation method of the battery of Example 8 is basically the same as that of Example 1, except that the temperature of the heat treatment is different. In Example 8, the LLZTO powder and the carbon material graphene are heat treated at 1350° C. in an argon environment for 10 minutes.

[0073] Comparative Example 1

[0074] The preparation method of the battery of Comparative Example 1 is substantially the same as that of Example 1, except that the LLZTO powder is not blended with the carbon material for heat treatment.

[0075] Comparative Example 2

[0076] The preparation method of the battery of Comparative Example 2 is basically the same as that of Example 6, except that the LATP powder is not blended with the carbon material for heat treatment.

[0077] 2. Performance Testing

[0078] 1) Solid electrolyte ion conductivity test

[0079] The sintered solid electrolyte ceramic sheet was polished to a smooth surface, then soaked in dilute hydrochloric acid for 30 seconds to remove surface impurities such as Li₂CO₃ and LiOH, and then placed in a glove box for later use. A layer of Ag was deposited on both sides of the solid electrolyte membrane using a thermal evaporation coater to form an Ag / LLZTO / Ag blocking system. Lithium sheets were used as electrodes, and a coin cell battery was used for packaging.

[0080] An electrochemical workstation was used to apply a small-amplitude sinusoidal wave to the button cell, with an AC amplitude of 0.01V. The test temperature was room temperature. The frequency of the applied small-amplitude sinusoidal wave was varied within the test frequency range of 1Hz to 1MHz, obtaining a series of impedances at different frequencies. The Nyquist plot was obtained, with the real part of the impedance as the horizontal axis and the imaginary part as the vertical axis, with each point representing a different frequency. The left side of the plot, known as the high-frequency region, has a semicircular shape, while the right side, known as the low-frequency region, has a linear shape. According to equivalent circuit analysis, the intersection of the semicircle with the real axis at low frequencies corresponds to the ionic resistance R of the solid electrolyte ceramic sheet. The conductivity was calculated using the following formula.

[0081] Wherein, σ represents conductivity, with the unit of S / m; ρ represents resistivity, which is the reciprocal of resistivity, with the unit of Ω·m; L represents the length of the solid electrolyte ceramic sheet, with the unit of m; A represents the cross-sectional area of ​​the solid electrolyte ceramic sheet, with the unit of m 2 ; R represents the ionic resistance of the solid electrolyte ceramic sheet.

[0082] 3. Analysis of test results of various embodiments and comparative examples

[0083] Batteries of various examples and comparative examples were prepared according to the above methods, and various performance parameters were measured. The results are shown in Table 1.

[0084] Table 1

[0085] As can be seen from the comparison of the examples and the comparative examples, the solid electrolyte containing oxygen vacancies prepared by the method of the present application has higher ionic conductivity, which helps to further improve the electrochemical performance of solid-state batteries. As can be seen from the comparison of Example 1 and Example 6, the prepared tantalum-doped lithium lanthanum zirconium oxide electrolyte (LLZTO) has higher ionic conductivity. As can be seen from the comparison of Example 1 and Example 7, the selection of graphene as the carbon material can further improve the improvement effect of the ionic conductivity of the solid electrolyte.

[0086] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing a solid electrolyte containing oxygen vacancies, characterized in that: include: Mixing carbon materials and oxide solid electrolytes to obtain hybrid materials, The mixed material is heat-treated to prepare a solid electrolyte containing oxygen vacancies.

2. The preparation method according to claim 1, characterized in that The mass ratio of the carbon material to the oxide solid electrolyte is 0.1:100-2:

100.

3. The preparation method according to claim 1, characterized in that The carbon material includes one or more of conductive carbon black, graphite, graphene, and carbon nanotubes.

4. The preparation method according to claim 1, characterized in that The oxide solid electrolyte includes one or more of lithium lanthanum zirconium oxide electrolyte (LLZO), lithium aluminum titanium phosphate (LATP), lithium lanthanum titanate (LLTO) and modified materials thereof.

5. The preparation method according to claim 1, characterized in that The oxide solid electrolyte includes a tantalum-doped lithium lanthanum zirconium oxide (LLZTO) electrolyte.

6. The preparation method according to claim 1, characterized in that The temperature of the heat treatment is 1100°C-1400°C.

7. The preparation method according to claim 1, characterized in that The heat treatment time is 1 / 6 hour to 12 hours.

8. The preparation method according to claim 1, characterized in that The heating rate of the heat treatment is 1°C / min-20°C / min.

9. The preparation method according to claim 1, characterized in that The heat treatment environment is an inert atmosphere.

10. The preparation method according to claim 1, characterized in that The lithium ion conductivity of the solid electrolyte containing oxygen vacancies is 0.8 mS / cm-1.6 mS / cm. 11 . A solid electrolyte containing oxygen vacancies, wherein the solid electrolyte containing oxygen vacancies is prepared by the preparation method according to any one of claims 1 to 10.

12. A solid-state battery, characterized in that: The solid electrolyte containing oxygen vacancies is prepared by the preparation method according to any one of claims 1 to 10, or the solid electrolyte containing oxygen vacancies according to claim 11.

13. An electrical device, characterized in that: Including the solid-state battery according to claim 12.

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