Zirconium oxide precursor, NASICON type sodium ion solid electrolyte material and preparation method of zirconium oxide precursor and NASICON type sodium ion solid electrolyte material

Abstract

The invention discloses a zirconium oxide precursor, an NASICON type sodium ion solid electrolyte material and a preparation method of the NASICON type sodium ion solid electrolyte material, and relates to the technical field of battery materials. The chemical general formula of the zirconium oxide precursor material is Zr (2-x-y) / 2MIx / 2MIIy / 2O2, x and y are the mole numbers of MI and MII respectively, x is more than or equal to 0 and less than or equal to 0.5, y is more than or equal to 0 and less than or equal to 0.5, and x and y are not 0 at the same time. And M I and M II are one or more of Ca, Sr, Mg, Ba, Y, La, Al and In. And preparing the NASICON type sodium ion solid electrolyte by taking the precursor as a zirconium source. The chemical general formula of the solid electrolyte material is Na < 1 + 2x + y + z > Zr < 2-x-y > M < x > M < II > < y > Si < z > P < 3-z > O < 12 >, x, y and z are the mole numbers of M I, M II and Si respectively, x is larger than or equal to 0 and smaller than or equal to 0.5, y is larger than or equal to 0 and smaller than or equal to 0.5, and 0lt is larger than or equal to 0 and smaller than or equal to 0.5; zlt, zlt; x and y are not 0 at the same time. The zirconium oxide precursor material and the sodium ion solid electrolyte material are both prepared by adopting a solid phase method, and the method is simple, environment-friendly, relatively low in cost and easy for large-scale production. Meanwhile, the sodium ion solid electrolyte prepared by the method has the advantages of high room-temperature ionic conductivity, high density, high purity, low activation energy and low electronic conductivity.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and particularly relates to a zirconium oxide precursor, a NASICON-type sodium ion solid electrolyte material, and a preparation method thereof. Background Art

[0002] With the progress of technology and the rapid development of society, the energy crisis and global warming problems brought about by the consumption of traditional fossil fuels have become increasingly prominent. Developing and utilizing clean and renewable energy is an important way to solve the above problems. However, renewable energy sources such as solar energy, wind energy, and tidal energy have disadvantages such as uneven geographical distribution, low conversion rate, and intermittency, which limit their direct grid connection and utilization. In order to effectively store and utilize such green energy, it is crucial to design and prepare new energy storage devices that are safe, efficient, and stable.

[0003] Lithium-ion batteries are an excellent type of electrochemical energy storage device, with advantages such as high energy density, low self-discharge rate, high potential difference, and long cycle life. Therefore, they have been widely used in fields such as consumer electronics, new energy vehicles, smart grids, and industrial automation equipment. However, the global reserves of lithium resources are very limited and unevenly distributed. China's lithium resources are highly dependent on imports. Moreover, with the increasing demand for lithium-ion batteries in various industries, the shortage of lithium resources and their high costs will severely restrict the large-scale application of lithium-ion batteries. Therefore, it is necessary to develop suitable supplementary or alternative products.

[0004] Compared with lithium, sodium has extremely rich reserves and is evenly distributed. Moreover, both belong to the first main group and have similar physical and chemical properties and insertion mechanisms. Sodium-ion batteries can use the existing production technologies and equipment of lithium-ion batteries. Therefore, sodium-ion batteries have advantages such as rich resource reserves and low manufacturing costs, and have become a beneficial supplement and powerful alternative to lithium-ion batteries.

[0005] Traditional sodium-ion batteries, like traditional lithium-ion batteries, have serious safety hazards due to the use of flammable and leaky organic liquid electrolytes. Compared with organic liquid electrolytes, solid electrolytes have advantages such as high thermal stability, no leakage and volatility, and no risk of fire and explosion. The sodium-ion solid-state battery prepared by replacing the organic liquid electrolyte with a solid electrolyte has intrinsic safety. At the same time, the stable chemical properties of the solid electrolyte can effectively inhibit the interfacial side reactions between the electrode and the electrolyte, thereby inhibiting the attenuation of the battery capacity. The use of solid electrolytes can also simplify the battery structure and reduce the packaging cost. Therefore, solid-state sodium-ion batteries have the advantages of being safe, cheap, and having a long cycle life, and thus have broad development prospects in the application of large-scale energy storage devices.

[0006] NASICON-type solid electrolyte materials have the advantages of high room-temperature ionic conductivity, mechanical strength, good chemical and thermal stability, and inexpensive raw materials. They are an important class of sodium-ion oxide solid electrolytes. Among them, Na 1+x Zr2Si x P 3- x O 12 (0 < x < 3) has a unique three-dimensional open framework that can provide a fast transmission channel for Na + and enables it to have a high ionic conductivity even at room temperature, showing great potential in practical applications and thus becoming the focus of attention. Patent CN 105742698 B discloses a NASICON-type sodium-ion solid electrolyte material and its preparation method. By doping and substituting the Na site, Zr site, and Si site of the [Na 3+x-2y A y [Zr 2-x M][Si 2- x M'2]PO 12 material and using the sol-gel method for preparation, the ionic conductivity of the electrolyte material is improved. Patent CN 108695552 B provides a preparation method for a NASICON-structured sodium-ion solid electrolyte. By heat-treating the Na source, P source, ZrO2, SiO2, and metal oxide in a specific sintering atmosphere of nitrogen, argon, or oxygen, a material with a high room-temperature ionic conductivity is obtained. Patent CN 113113664 B provides a modified NASICON-type sodium-ion ceramic electrolyte, its preparation method, and application. The modified NASICON-type sodium-ion ceramic electrolyte is obtained by connecting low-melting-point boron oxides at the grain boundaries of the Na3Zr2Si2PO 12 ceramic, thereby reducing the densification sintering temperature of the electrolyte.

[0007] Solid-phase sintering method, sol-gel method, co-precipitation method, and hydrothermal-solvothermal method are common methods for preparing inorganic ceramic electrolytes. Among them, the solid-phase sintering method has a simple preparation process, low cost, mature process flow, and large product yield, making it suitable for mass production. However, the ionic conductivity of NASICON-type solid electrolytes prepared by the solid-phase sintering method is usually not high. Therefore, improving the room-temperature ionic conductivity of the products of the solid-phase sintering method is of profound significance for promoting the progress of the solid-state sodium-ion battery industry. Summary of the Invention

[0008] The present invention aims to solve the problem of low ionic conductivity of existing NASICON-type solid electrolytes, and provides a zirconium oxide precursor, a NASICON-type sodium ion solid electrolyte material and a preparation method thereof. The NASICON-type sodium ion solid electrolyte of the present invention has the advantages of high ionic conductivity, high density, high purity, low activation energy and low electronic conductivity. The preparation process of the present invention is simple, the raw materials are cheap and easy to obtain, the electrochemical performance of the product electrolyte material is good, it is easy to mass-produce, and has high practical value.

[0009] In a first aspect, the present invention provides a zirconium oxide precursor and a NASICON-type sodium ion solid electrolyte material. The zirconium source of the solid electrolyte material is a zirconium oxide precursor prepared by doping zirconia with a low-valent metal oxide. The low-valent element partially replaces the Zr site in the NASICON structure, and the low-valent element is one or more of Ca, Sr, Mg, Ba, Y, La, Al, and In.

[0010] Preferably, the chemical general formula of the zirconium oxide precursor material is: Zr (2-x-y) / 2 M Ⅰ x / 2 M Ⅱ y / 2 O2, where x and y are the molar numbers of the corresponding elements, respectively, where 0 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.5, and x and y are not both 0 at the same time.

[0011] Preferably, the chemical general formula of the solid electrolyte material is: Na 1+2x+y+z Zr 2-x-y M Ⅰ x M Ⅱ y Si z P 3-z O 12 , where x, y, and z are the molar numbers of the corresponding elements, respectively, where 0 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.5, 0 < z < 3, and x and y are not both 0 at the same time.

[0012] Preferably, the M Ⅰ is a divalent metal element that replaces the Zr site by doping, including one or more of Ca, Sr, Mg, and Ba. M Ⅱ is a trivalent metal element that replaces the Zr site by doping, including one or more of Y, La, Al, and In.

[0013] In a second aspect, the present invention provides a preparation method of a zirconium oxide precursor and a NASICON-type sodium ion solid electrolyte material. The preparation method is a solid-phase method, which specifically includes the following steps:

[0014] 1. Weigh zirconia with a stoichiometric ratio of 100% and metal oxides containing element M Ⅰ and M Ⅱ in a stoichiometric ratio of 2 - x - y:x:y, and then ball - mill and mix them. After drying and grinding, calcine them in an air atmosphere to obtain a pale - yellow massive zirconia precursor. Crush the massive precursor to obtain zirconia precursor powder;

[0015] 2. Thoroughly mix the zirconia precursor powder obtained in step 1 with a sodium source, a silicon source, and a phosphorus source, then place them in a ball mill for ball - milling. After drying and grinding, calcine them in an air atmosphere to obtain a white solid powder. Ball - mill, dry, grind, and sieve the white solid powder, and then press - mold it under a pressure of 10 - 100 Mpa to obtain a green body of the ceramic solid electrolyte;

[0016] 3. Calcine the green body of the ceramic solid electrolyte obtained in step 2 in an air atmosphere to obtain the NASICON - type sodium - ion solid electrolyte material.

[0017] Preferably, the rotation speed of the ball - milling in step 1 is 400 - 800 rpm, and the ball - milling time is 1 - 12 h;

[0018] Preferably, the calcination temperature in step 1 is 1200 - 1600 °C, the calcination duration is 2 - 10 h, and the heating rate of the calcination is 1 - 10 °C / min.

[0019] Preferably, the sodium source in step 2 is one or more of Na2CO3, NaHCO3, Na2C2O4, Na3PO4, Na2HPO4, NaH2PO4, and NaOH; the silicon source is one or more of SiO2, Si(OC2H5)4, and Si(OCH3)4; the phosphorus source is one or more of P2O5, NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, Na3PO4, Na2HPO4, and NaH2PO4.

[0020] Preferably, the calcination temperature in step 2 is 400 - 1000 °C, the calcination duration is 6 - 12 h, and the heating rate of the calcination is 1 - 10 °C / min.

[0021] Preferably, the calcination temperature in step 3 is 1000 - 1300 °C, the calcination duration is 5 - 14 h, and the heating rate of the calcination is 1 - 5 °C / min.

[0022] Advantages of the present invention:

[0023] The embodiments of the present invention provide a zirconium oxide precursor, a NASICON-type sodium ion solid electrolyte material and a preparation method thereof. The NASICON-type sodium ion solid electrolyte is obtained by a solid-phase method. A cubic zirconium oxide precursor is prepared by doping ZrO2 with one or several elements selected from Ca, Sr, Mg, Ba, Y, La, Al, and In, and the precursor is used as the Zr source for preparation. On the one hand, using the cubic zirconium oxide precursor as the Zr source can reduce the generation of m-ZrO2 impurities with poor conductivity in the product, improve the purity and increase the ionic conductivity of the NASICON-type sodium ion solid electrolyte material. On the other hand, due to doping, some low-valence elements partially replace the Zr site of the NASICON solid electrolyte material. To maintain charge balance, more mobile sodium ions will be introduced, making the proportion of mobile sodium ions and sodium ion vacancies appropriate, which is beneficial to improving the electrochemical performance. At the same time, by doping and modifying the matrix phase and grain boundaries, the bottleneck size for sodium ion migration is enlarged and the activation energy is reduced, thus significantly improving the ionic conductivity of the NASICON-type sodium ion solid electrolyte at room temperature.

[0024] The preparation process of the present invention is simple, the equipment requirements are low, and the raw materials are cheap and easy to obtain. It can be used for the large-scale production of sodium ion solid electrolytes. The prepared NASICON-type sodium ion solid electrolyte is an important part of all-solid-state sodium ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The technical solutions of the embodiments of the present invention will be further described in detail below with reference to the drawings and embodiments.

[0026] Figure 1 is the X-ray diffraction pattern (XRD) of the Na 3.32 Zr 1.82 Mg 0.14 Y 0.04 Si2PO 12 solid electrolyte sheet prepared in Example 1 of the present invention;

[0027] Figure 2 is the Na 3.32 Zr 1.82 Mg 0.14 Y 0.04 Si2PO 12 cross-sectional SEM image of the solid electrolyte sheet;

[0028] Figure 3 is the Na 3.32 Zr 1.82 Mg 0.14 Y 0.04 Si2PO 12 alternating current impedance spectrum (EIS) of the solid electrolyte sheet;

[0029] Figure 4 is the Na prepared in Example 1 of the present invention 3.32 Zr 1.82 Mg 0.14 Y 0.04 Si2PO 12 Arrhenius curve of the solid electrolyte sheet;

[0030] Figure 5 is the Na prepared in Example 2 of the present invention 3.32 Zr 1.8 Mg 0.12 Y 0.08 Si2PO 12 X-ray diffraction pattern (XRD) of the solid electrolyte sheet;

[0031] Figure 6 is the Na prepared in Example 2 of the present invention 3.32 Zr 1.8 Mg 0.12 Y 0.08 Si2PO 12 Cross-sectional SEM image of the solid electrolyte sheet;

[0032] Figure 7 is the Na prepared in Example 2 of the present invention 3.32 Zr 1.8 Mg 0.12 Y 0.08 Si2PO 12 Alternating current impedance spectrum (EIS) of the solid electrolyte sheet;

[0033] Figure 8 is the Na prepared in Example 3 of the present invention 3.44 Zr 1.76 Ca 0.2 Y 0.04 Si2PO 12 X-ray diffraction pattern (XRD) of the solid electrolyte sheet;

[0034] Figure 9 is the Na prepared in Example 3 of the present invention 3.44 Zr 1.76 Ca 0.2 Y 0.04 Si2PO 12 Cross-sectional SEM image of the solid electrolyte sheet;

[0035] Figure 10 is the Na prepared in Example 3 of the present invention 3.44 Zr 1.76 Ca 0.2 Y 0.04 Si2PO 12 Alternating current impedance spectrum (EIS) of the solid electrolyte sheet;

[0036] Figure 11 is the Na prepared in Example 4 of the present invention 3.34 Zr 1.86 Ca 0.1 Y 0.04 Si 2.1 P 0.9 O 12 X-ray diffraction pattern (XRD) of the solid electrolyte sheet;

[0037] Figure 12 is the Na prepared in Example 4 of the present invention 3.34 Zr 1.86 Ca 0.1 Y 0.04 Si 2.1 P 0.9 O 12 Cross-sectional SEM image of the solid electrolyte sheet;

[0038] Figure 13 is the Na prepared in Example 4 of the present invention 3.34 Zr 1.86 Ca 0.1 Y 0.04 Si 2.1 P 0.9 O 12 Alternating current impedance spectroscopy (EIS) of the solid electrolyte sheet;

[0039] Figure 14 is the Na prepared in Example 5 of the present invention 3.32 Zr 1.8 Mg 0.06 Sr 0.06 Al 0.08 Si2PO 12 X-ray diffraction pattern (XRD) of the solid electrolyte sheet;

[0040] Figure 15 is the Na prepared in Example 5 of the present invention 3.32 Zr 1.8 Mg 0.06 Sr 0.06 Al 0.08 Si2PO 12 Cross-sectional SEM image of the solid electrolyte sheet;

[0041] Figure 16 is the Na prepared in Example 5 of the present invention 3.32 Zr 1.8 Mg 0.06 Sr 0.06 Al 0.08 Si2PO 12 Alternating current impedance spectroscopy (EIS) of the solid electrolyte sheet;

[0042] Figure 17 is the Na prepared in Example 6 of the present invention 3.32 Zr 1.8 Mg 0.12 Y 0.04 La 0.04 Si2PO 12 X-ray diffraction pattern (XRD) of the solid electrolyte sheet;

[0043] Figure 18 is the Na prepared in Example 6 of the present invention 3.32 Zr 1.8 Mg 0.12 Y 0.04 La 0.04 Si2PO 12 Cross-sectional SEM image of the solid electrolyte sheet;

[0044] Figure 19 is the Na prepared in Example 6 of the present invention 3.32 Zr 1.8 Mg 0.12 Y 0.04 La 0.04 Si2PO 12 AC impedance spectroscopy (EIS) of the solid electrolyte sheet;

[0045] Figure 20 is the Na3Zr2Si2PO prepared in the comparative example of the present invention 12 X-ray diffraction pattern (XRD) of the solid electrolyte sheet;

[0046] Figure 21 is the Na3Zr2Si2PO prepared in the comparative example of the present invention 12 Cross-sectional SEM image of the solid electrolyte sheet;

[0047] Figure 22 is the Na3Zr2Si2PO prepared in the comparative example of the present invention 12 AC impedance spectroscopy (EIS) of the solid electrolyte sheet;

[0048] Figure 23 is the Na3Zr2Si2PO prepared in the comparative example of the present invention 12 Arrhenius curve of the solid electrolyte sheet; Detailed Description of the Invention

[0049] The following provides a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the protection scope of the present invention.

[0050] Specific implementation method 1: The embodiment of the present invention provides a zirconium oxide precursor and a NASICON type sodium ion solid electrolyte material, wherein the zirconium source of the solid electrolyte material is a zirconium oxide precursor prepared by doping zirconium oxide with low-valent metal oxides, and the low-valent elements partially replace the Zr position in the NASICON structure, wherein the low-valent elements are Mg and Y, and the low-valent metal oxides are magnesium oxide and yttrium oxide;

[0051] The general chemical formula of the solid electrolyte material is: Na 1+2x+y+z Zr 2-x-y M Ⅰ x M Ⅱ y Si z P 3-z O 12 , wherein x, y, and z are the molar numbers of the corresponding elements, wherein x=0.14, y=0.04, and z=1.

[0052] M Ⅰ is a divalent metal element doped to replace Zr, preferably Mg, M Ⅱ It is a trivalent metal element doped to replace the Zr position, preferably Y.

[0053] The embodiment of the present invention provides a method for preparing the above-mentioned zirconium oxide precursor and NASICON type sodium ion solid electrolyte material, which is a solid phase method and specifically comprises the following steps:

[0054] 1. Mix 100% of the required stoichiometric amount of zirconium oxide and 100% of the required stoichiometric amount of M-containing Ⅰ 、M Ⅱ The elemental metal oxides are weighed and ball-milled in a stoichiometric ratio of 1.82:0.14:0.04, dried and ground, and then calcined in an air atmosphere to obtain a light yellow blocky zirconium oxide precursor, and the blocky precursor is crushed to obtain a zirconium oxide precursor powder;

[0055] 2. The zirconium oxide precursor powder described in step 1 is fully mixed with a sodium source, a silicon source, and a phosphorus source, and then placed in a ball mill for ball milling. After drying and grinding, the mixture is calcined in an air atmosphere to obtain a white solid powder. The white solid powder is ball milled, dried, ground, sieved, and then pressed into a sheet under a pressure of 10 to 100 MPa to obtain a ceramic solid electrolyte green sheet;

[0056] 3. Calcine the ceramic solid electrolyte green sheet described in step 2 in an air atmosphere to obtain the NASICON type sodium ion solid electrolyte material.

[0057] Among them, the rotation speed of ball milling in Step 1 is 800 rpm, the ball milling time is 2 h, the calcination temperature is 1600 °C, the calcination duration is 5 h, and the heating rate of calcination is 5 °C / min.

[0058] The sodium source described in Step 2 is Na2CO3, the silicon source is SiO2, the phosphorus source is NH4H2PO4, the calcination temperature is 900 °C, the calcination duration is 6 h, and the heating rate of calcination is 5 °C / min.

[0059] The calcination temperature described in Step 3 is 1160 °C, the calcination duration is 6 h, and the heating rate of calcination is 3 °C / min.

[0060] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that: in Step 1, the stoichiometric ratio of zirconia, magnesia and yttria is 1.8:0.12:0.08, the sodium source is sodium hydroxide, and the other steps are the same as those in Specific Embodiment 1.

[0061] Specific Embodiment 3: The difference between this embodiment and Specific Embodiment 1 is that: the low-valence elements are Ca and Y, and the low-valence metal oxides are calcium oxide and yttrium oxide; in Step 1, the stoichiometric ratio of zirconia, calcium oxide and yttrium oxide is 1.76:0.2:0.04, the rotation speed of ball milling is 600 rpm, the ball milling time is 6 h, the calcination temperature is 1500 °C, and the calcination time is 3 h; in Step 2, the calcination temperature is 950 °C, the calcination duration is 8 h, and the heating rate of calcination is 10 °C / min; in Step 3, the calcination temperature is 1120 °C, the calcination duration is 8 h, and the heating rate of calcination is 1 °C / min, and the other steps are the same as those in Specific Embodiment 1.

[0062] Specific Embodiment 4: The difference between this embodiment and Specific Embodiment 1 is that: the low-valence elements are Ca and Y, and the low-valence metal oxides are calcium oxide and yttrium oxide; in Step 1, the stoichiometric ratio of zirconia, calcium oxide and yttrium oxide is 1.86:0.1:0.04, the rotation speed of ball milling is 600 rpm, the ball milling time is 6 h, the calcination temperature is 1500 °C, and the calcination time is 3 h; in Step 2, the calcination temperature is 950 °C, the calcination duration is 8 h, and the heating rate of calcination is 10 °C / min; in Step 3, the calcination temperature is 1120 °C, the calcination duration is 8 h, and the heating rate of calcination is 1 °C / min, and the other steps are the same as those in Specific Embodiment 1.

[0063] Specific Embodiment 5: The difference between this embodiment and Specific Embodiment 1 is that the low-valence elements are Mg, Sr, and Al, and the low-valence metal oxides are magnesium oxide, strontium oxide, and aluminum oxide; in Step 1, the stoichiometric ratio of zirconia to magnesium oxide, strontium oxide, and aluminum oxide is 1.8:0.06:0.06:0.08, the rotation speed of ball milling is 700 rpm, the ball milling time is 4 h, the calcination temperature is 1550 °C, and the calcination time is 6 h; in Step 2, the calcination temperature is 850 °C, the calcination duration is 12 h, and the heating rate of calcination is 2 °C / min; in Step 3, the calcination temperature is 1140 °C, the calcination duration is 10 h, and the heating rate of calcination is 2 °C / min. Other steps are the same as those in Specific Embodiment 1.

[0064] Specific Embodiment 6: The difference between this embodiment and Specific Embodiment 1 is that the low-valence elements are Mg, Y, and La, and the low-valence metal oxides are magnesium oxide, yttrium oxide, and lanthanum oxide; in Step 1, the stoichiometric ratio of zirconia to magnesium oxide, yttrium oxide, and lanthanum oxide is 1.8:0.12:0.04:0.04, the rotation speed of ball milling is 500 rpm, the ball milling time is 3 h, the calcination temperature is 1550 °C, and the calcination time is 6 h; in Step 2, the calcination temperature is 950 °C, the calcination duration is 10 h, and the heating rate of calcination is 3 °C / min; in Step 3, the calcination temperature is 1200 °C, the calcination duration is 12 h, and the heating rate of calcination is 5 °C / min. Other steps are the same as those in Specific Embodiment 1.

[0065] Specific Embodiment 7: The difference between this embodiment and Specific Embodiment 1 is that the sodium source described in Step 2 is one or more of NaHCO3, Na2C2O4, Na3PO4, Na2HPO4, NaH2PO4, and NaOH. Other steps are the same as those in Specific Embodiment 1.

[0066] Specific Embodiment 8: The difference between this embodiment and Specific Embodiment 1 is that the phosphorus source described in Step 2 is one or more of P2O5, (NH4)2HPO4, (NH4)3PO4, Na3PO4, Na2HPO4, and NaH2PO4. Other steps are the same as those in Specific Embodiment 1.

[0067] Specific Embodiment 9: The difference between this embodiment and Specific Embodiment 1 is that the silicon source described in Step 2 is one or more of SiO2, Si(OC2H5)4, and Si(OCH3)4. Other steps are the same as those in Specific Embodiment 1.

[0068] Comparative Example: This comparative example is unmodified Na3Zr2Si2PO 12, which is different from the specific implementation mode one: the zirconium source of the solid electrolyte material is zirconium oxide, and there is no need to prepare a zirconium oxide precursor prepared by doping zirconium oxide with a low-valent metal oxide, and the rest is the same as the specific implementation mode one.

[0069] In order to further illustrate the present invention, a zirconium oxide precursor and a NASICON type sodium ion solid electrolyte material and a preparation method thereof provided by the present invention are described in detail below in combination with specific embodiments.

[0070] Example 1

[0071] This embodiment provides a NASICON type sodium ion solid electrolyte material, the chemical formula is: Na 3.32 Zr 1.82 Mg 0.14 Y 0.04 Si2PO 12 , prepared by solid phase method, the specific steps are as follows:

[0072] 1. Weigh the required stoichiometric amount of 100% zirconium oxide and the required stoichiometric amount of 100% magnesium oxide and yttrium oxide in a stoichiometric ratio of 1.82:0.14:0.04, put them into a ball mill together, add anhydrous ethanol, and ball mill at a ball mill speed of 800rpm for 2h; after ball milling, dry them at 100°C for 24h, take them out and grind them, put them into a muffle furnace, and calcine them in an air atmosphere to obtain a light yellow blocky zirconium oxide precursor, the calcination temperature is 1600°C, the calcination time is 5h, the heating rate is 5°C / min, and the blocky precursor is crushed and ground to obtain a zirconium oxide precursor powder;

[0073] 2. Weigh zirconium oxide precursor powder, sodium carbonate, silicon dioxide, and ammonium dihydrogen phosphate according to a stoichiometric ratio of 2:1.66:2:1, wherein sodium carbonate is 10% in excess and ammonium dihydrogen phosphate is 5% in excess. After being fully mixed, place the mixture in a ball mill and add deionized water for ball milling at a speed of 600 rpm for 12 hours. After ball milling, dry the mixture at 100°C for 24 hours, take it out, grind it, and place it in a muffle furnace. Calcinate it in an air atmosphere to obtain a white solid powder. The temperature is 900°C, the calcination time is 6 hours, and the heating rate is 5°C / min; the white solid powder is crushed and ground and then placed in a ball mill, and anhydrous ethanol is added for secondary ball milling, the ball milling speed is 700rpm, and the ball milling time is 12 hours; after the ball milling is completed, it is dried at 100°C for 12 hours, taken out and ground for 20 minutes, sieved with a 200-mesh screen, and uniaxially pressed at a pressure of 20Mpa for 20 minutes to obtain a ceramic solid electrolyte green sheet with a diameter of 20mm and a thickness of 2.2mm;

[0074] 3. Place the ceramic solid electrolyte green sheet in a crucible, bury the powder up and down, and calcine in an air atmosphere, wherein the calcination temperature is 1160°C, the calcination time is 6 hours, and the heating rate is 3°C / min; after naturally cooling to room temperature, grind and polish to obtain a NASICON type sodium ion solid electrolyte.

[0075] Figure 1 For the preparation of Na 3.32 Zr 1.82 Mg 0.14 Y 0.04 Si2PO 12 X-ray diffraction (XRD) pattern of solid electrolyte sheet, Figure 1 It can be seen that Na 3.32 Zr 1.82 Mg 0.14 Y 0.04 Si2PO 12 The main characteristic peaks are consistent with the standard PDF card, and there is no m-ZrO2 diffraction peak, indicating that the use of zirconium oxide precursor as a zirconium source has a positive significance for reducing the m-ZrO2 impurity phase. 2+ Partially replace Zr 4+ , a NaMgPO4 secondary phase is formed at the grain boundary. NaMgPO4 is an excellent ion conductor. At the same time, the space charge layer effect will accelerate the transport of ions at the grain boundary.

[0076] Figure 2 For the preparation of Na 3.32 Zr 1.82 Mg 0.14 Y 0.04 Si2PO 12 Cross-sectional SEM image of solid electrolyte sheet. Figure 2 It can be seen that the grains are cubic in shape, the grains are in close contact, and there are few pores. 3.32 Zr 1.82 Mg 0.14 Y 0.04 Si2PO 12 The density of the solid electrolyte sheet was measured and found to be 97.3%, which is consistent with the low porosity reflected in the cross-sectional SEM image.

[0077] The Na 3.32 Zr 1.82 Mg 0.14 Y 0.04 Si2PO 12 A layer of gold electrode is evenly plated on both sides of the solid electrolyte sheet, and its ionic conductivity at room temperature is tested by an electrochemical workstation. Figure 3 As shown, after testing, Na 3.32 Zr 1.82 Mg0.14 Y 0.04 Si2PO 12 The ionic conductivity of the solid electrolyte sheet at room temperature is 1.68 mS / cm, indicating that the simultaneous doping of Mg and Y elements modifies the lattice and grain boundaries of the grains, which is beneficial to improving the ionic conductivity of the NASICON-type sodium ion solid electrolyte.

[0078] Figure 4 For the prepared Na 3.32 Zr 1.82 Mg 0.14 Y 0.04 Si2PO 12 Arrhenius curve of the solid electrolyte sheet. According to the slope of the fitting curve, the activation energy of Na 3.32 Zr 1.82 Mg 0.14 Y 0.04 Si2PO 12 The activation energy of the solid electrolyte sheet is 0.27 eV, indicating that by replacing part of Zr with Y 3+ is beneficial to expanding the bottleneck size of the Na 4+ transport channel, thereby reducing the activation energy and facilitating the migration of Na + + .

[0079] Example 2

[0080] This example provides a NASICON-type sodium ion solid electrolyte material with the chemical formula: Na 3.32 Zr 1.8 Mg 0.12 Y 0.08 Si2PO 12 , which is prepared by the solid-phase method. The specific steps are as follows:

[0081] I. Weigh zirconium oxide with a required stoichiometric ratio of 100%, magnesium oxide with a required stoichiometric ratio of 100%, and yttrium oxide according to the stoichiometric ratio of 1.8:0.12:0.08, put them into a ball mill together, add anhydrous ethanol, and ball mill for 2 h at a ball milling speed of 800 rpm; after the ball milling is completed, dry at 100 °C for 24 h, take out and grind, then put it into a muffle furnace and calcine in an air atmosphere to obtain a light yellow massive zirconium oxide precursor. The calcination temperature is 1600 °C, the calcination duration is 5 h, and the heating rate is 5 °C / min. After crushing and grinding the massive precursor, zirconium oxide precursor powder is obtained;

[0082] ​II. Weigh zirconium oxide precursor powder, sodium hydroxide, silicon dioxide, and ammonium dihydrogen phosphate according to the stoichiometric ratio of 2:3.32:2:1. Among them, sodium hydroxide is in an excess of 10%, and ammonium dihydrogen phosphate is in an excess of 5%. After fully mixing, place them into a ball mill, add deionized water for ball milling. The ball milling speed is 600 rpm, and the ball milling time is 12 h. After the ball milling is completed, dry at 100 °C for 24 h, take out and grind, then place it into a muffle furnace and calcine in an air atmosphere to obtain a white solid powder. Among them, the calcination temperature is 900 °C, the calcination duration is 6 h, and the heating rate is 5 °C / min. Crush and grind the white solid powder, then place it into a ball mill, add absolute ethanol for secondary ball milling. The ball milling speed is 700 rpm, and the ball milling time is 12 h. After the ball milling is completed, dry at 100 °C for 12 h, take out and grind for 20 min, sieve with a 200-mesh sieve, and then uniaxially press at a pressure of 20 Mpa for 20 min to obtain a green body of a ceramic solid electrolyte with a diameter of 20 mm and a thickness of 2.2 mm.

[0083] III. Place the green body of the ceramic solid electrolyte into a crucible, bury powder on the top and bottom, and calcine in an air atmosphere. Among them, the calcination temperature is 1160 °C, the calcination duration is 6 h, and the heating rate is 3 °C / min. After natural cooling to room temperature, polish it to obtain a NASICON-type sodium ion solid electrolyte.

[0084] Figure 5 For the prepared Na 3.32 Zr 1.8 Mg 0.12 Y 0.08 Si2PO 12 X-ray diffraction pattern (XRD) of the solid electrolyte sheet, the result is Figure 1 similar, the main characteristic peaks coincide with the standard PDF card, there is no appearance of the m-ZrO2 diffraction peak, and a NaMgPO4 ion conductor is formed at the grain boundary.

[0085] Figure 6 For the prepared Na 3.32 Zr 1.8 Mg 0.12 Y 0.08 Si2PO 12 Cross-sectional SEM image of the solid electrolyte sheet, the result is Figure 2 similar, the grains are in close contact and there are fewer pores. By measuring with the Archimedes drainage method, the density is obtained as 97.7%, which is consistent with the low porosity reflected by the cross-sectional SEM image.

[0086] Use an ion sputtering instrument to deposit Na 3.32 Zr 1.8 Mg 0.12 Y 0.08 Si2PO 12A layer of gold electrode is evenly plated on both sides of the solid electrolyte sheet, and its ionic conductivity at room temperature is tested by an electrochemical workstation as Figure 7 shown. After testing, Na 3.32 Zr 1.8 Mg 0.12 Y 0.08 Si2PO 12 The ionic conductivity of the solid electrolyte sheet at room temperature is 2.32 mS / cm, indicating that the simultaneous modification of the crystal lattice and grain boundaries of the grains by doping with Mg and Y elements is beneficial to improving the ionic conductivity of NASICON-type sodium ion solid electrolytes.

[0087] The Arrhenius plot of the NASICON-type sodium ion solid electrolyte prepared in this example is fitted and calculated, and the result is similar to Figure 4 that of undoped Na3Zr2Si2PO 12 with a lower activation energy, which is beneficial to the migration of sodium ions. The drawings are not repeated in this example.

[0088] Example 3

[0089] This example provides a NASICON-type sodium ion solid electrolyte material with the chemical formula: Na 3.44 Zr 1.76 Ca 0.2 Y 0.04 Si2PO 12 , which is prepared by the solid-phase method. The specific steps are as follows:

[0090] I. Weigh 100% of zirconium oxide, 100% of calcium oxide and yttrium oxide with the required stoichiometric numbers according to the stoichiometric ratio of 1.76:0.2:0.04, put them into a ball mill together, add absolute ethanol, and ball mill at a ball mill speed of 600 rpm for 6 h; after the ball milling is completed, dry at 100 °C for 24 h, take out and grind, then put it into a muffle furnace and calcine in an air atmosphere to obtain a light yellow blocky zirconium oxide precursor. The calcination temperature is 1500 °C, the calcination time is 3 h, and the heating rate is 5 °C / min. After crushing and grinding the blocky precursor, zirconium oxide precursor powder is obtained;

[0091] 2. Weigh zirconium oxide precursor powder, sodium bicarbonate, tetramethyl orthosilicate, and diammonium hydrogen phosphate in a stoichiometric ratio of 2:3.44:2:0.5, wherein sodium carbonate is 10% in excess and diammonium hydrogen phosphate is 5% in excess. Mix thoroughly until tetramethyl orthosilicate is completely hydrolyzed, place in a ball mill, add deionized water for ball milling, the ball milling speed is 600 rpm, and the ball milling time is 12 h. After ball milling, dry at 100 ° C for 24 h, take out and grind, place in a muffle furnace, and calcine in an air atmosphere to obtain a white solid. The powder is calcined at 950°C for 8 hours and at a heating rate of 10°C / min. The white solid powder is crushed and ground and then placed in a ball mill, and anhydrous ethanol is added for secondary ball milling at 700 rpm for 12 hours. After the ball milling is completed, the powder is dried at 100°C for 12 hours, taken out and ground for 20 minutes, sieved with a 200-mesh sieve, and uniaxially pressed at a pressure of 20 MPa for 20 minutes to obtain a ceramic solid electrolyte green sheet with a diameter of 20 mm and a thickness of 2.2 mm.

[0092] 3. Place the ceramic solid electrolyte green sheet in a crucible, bury the powder up and down, and calcine in an air atmosphere, wherein the calcination temperature is 1120°C, the calcination time is 8 hours, and the heating rate is 1°C / min; after naturally cooling to room temperature, grind and polish to obtain a NASICON type sodium ion solid electrolyte.

[0093] Figure 8 For the preparation of Na 3.44 Zr 1.76 Ca 0.2 Y 0.04 Si2PO 12 X-ray diffraction (XRD) pattern of solid electrolyte sheet, Figure 8 It can be seen that Na 3.44 Zr 1.76 Ca 0.2 Y 0.04 Si2PO 12 The main characteristic peaks are consistent with the standard PDF card, and no m-ZrO2 diffraction peak appears, thus obtaining a NASICON-type sodium ion solid electrolyte with higher purity.

[0094] Figure 9 For the preparation of Na 3.44 Zr 1.76 Ca 0.2 Y 0.04 Si2PO 12 The cross-sectional SEM image of the solid electrolyte sheet shows the same Figure 2 Similarly, the grains are in close contact and have fewer pores. The density is calculated by the Archimedean drainage method to be 95.1%, which is consistent with the low porosity reflected in the cross-sectional SEM image.

[0095] The Na3.44 Zr 1.76 Ca 0.2 Y 0.04 Si2PO 12 A gold electrode is evenly plated on both sides of the solid electrolyte sheet, and its ionic conductivity at room temperature is tested by an electrochemical workstation as Figure 10 shown. After testing, Na 3.44 Zr 1.76 Ca 0.2 Y 0.04 Si2PO 12 The ionic conductivity of the solid electrolyte sheet at room temperature is 1.10 mS / cm, indicating that the double-element doping of Ca and Y is beneficial to improving the ionic conductivity of the NASICON-type sodium ion solid electrolyte.

[0096] The Arrhenius plot of the NASICON-type sodium ion solid electrolyte prepared in this example is fitted and calculated, and the result is similar to Figure 4 that of the undoped Na3Zr2Si2PO 12 with a lower activation energy, which is beneficial to the migration of sodium ions. The drawings are not repeated in this example.

[0097] Example 4

[0098] This example provides a NASICON-type sodium ion solid electrolyte material with the chemical formula: Na 3.34 Zr 1.86 Ca 0. 1Y 0.04 Si 2.1 P 0.9 O 12 , which is prepared by the solid-phase method. The specific steps are as follows:

[0099] I. Weigh 100% of the required stoichiometric amount of zirconium oxide, 100% of the required stoichiometric amount of calcium oxide and yttrium oxide according to the stoichiometric ratio of 1.86:0.1:0.04, put them into a ball mill together, add absolute ethanol, and ball mill at a ball milling speed of 600 rpm for 6 h; after the ball milling is completed, dry at 100 °C for 24 h, take out and grind, then put it into a muffle furnace, and calcine in an air atmosphere to obtain a light yellow blocky zirconium oxide precursor. The calcination temperature is 1500 °C, the calcination duration is 3 h, and the heating rate is 5 °C / min. After crushing and grinding the blocky precursor, zirconium oxide precursor powder is obtained;

[0100] 2. Weigh zirconium oxide precursor powder, sodium bicarbonate, tetramethyl orthosilicate, and diammonium hydrogen phosphate in a stoichiometric ratio of 2:3.34:2.1:0.45, wherein sodium bicarbonate is 10% in excess and diammonium hydrogen phosphate is 5% in excess. Mix thoroughly until tetramethyl orthosilicate is completely hydrolyzed, place in a ball mill, add deionized water for ball milling, the ball milling speed is 600 rpm, and the ball milling time is 12 h. After ball milling, dry at 100 ° C for 24 h, take out and grind, place in a muffle furnace, and calcine in an air atmosphere to obtain a white Solid powder, wherein the calcination temperature is 950°C, the calcination time is 8 hours, and the heating rate is 10°C / min; the white solid powder is crushed and ground and then placed in a ball mill, anhydrous ethanol is added for secondary ball milling, the ball milling speed is 700rpm, and the ball milling time is 12 hours; after the ball milling is completed, it is dried at 100°C for 12 hours, taken out and ground for 20 minutes, sieved with a 200-mesh screen, and uniaxially pressed at a pressure of 20Mpa for 20 minutes to obtain a ceramic solid electrolyte green sheet with a diameter of 20 mm and a thickness of 2.2 mm;

[0101] 3. Place the ceramic solid electrolyte green sheet in a crucible, bury the powder up and down, and calcine in an air atmosphere, wherein the calcination temperature is 1120°C, the calcination time is 8 hours, and the heating rate is 1°C / min; after naturally cooling to room temperature, grind and polish to obtain a NASICON type sodium ion solid electrolyte.

[0102] Figure 11 For the preparation of Na 3.34 Zr 1.86 Ca 0.1 Y 0.04 Si 2.1 P 0.9 O 12 The X-ray diffraction pattern (XRD) of the solid electrolyte sheet is similar to Figure 8 Similar, Na 3.34 Zr 1.86 Ca 0.1 Y 0.04 Si 2.1 P 0.9 O 12 The main characteristic peaks are consistent with the standard PDF card, and no m-ZrO2 diffraction peak appears, thus obtaining a NASICON-type sodium ion solid electrolyte with higher purity.

[0103] Figure 12 For the preparation of Na 3.34 Zr 1.86 Ca 0.1 Y 0.04 Si 2.1 P 0.9 O 12 The cross-sectional SEM image of the solid electrolyte sheet shows the same Figure 2Similarly, the grains are in close contact, with fewer pores. Measured by the Archimedes drainage method, the density is 94.9%, which is consistent with the low porosity reflected in the cross-sectional SEM image.

[0104] Use an ion sputtering instrument to deposit a layer of gold electrodes evenly on both sides of the solid electrolyte sheet, and test its ionic conductivity at room temperature as 3.34 Zr 1.86 Ca 0.1 Y 0.04 Si 2.1 P 0.9 O 12 shown. After testing, the ionic conductivity of the Na Figure 13 Zr 3.34 Zr 1.86 Ca 0.1 Y 0.04 Si 2.1 P 0.9 O 12 solid electrolyte sheet at room temperature is 1.23 mS / cm, indicating that further adjusting the Si and P ratios on the basis of Ca and Y dual-element doping is beneficial to improving the ionic conductivity of NASICON-type sodium ion solid electrolytes.

[0105] Perform fitting calculations on the Arrhenius plot of the NASICON-type sodium ion solid electrolyte prepared in this example, and the results obtained are similar to Figure 4 those of undoped Na3Zr2Si2PO 12 with a lower activation energy, which is beneficial to the migration of sodium ions. The drawings are not repeated in this example.

[0106] Example 5

[0107] This example provides a NASICON-type sodium ion solid electrolyte material with the chemical formula: Na 3.32 Zr 1.8 Mg 0.06 Sr 0.06 Al 0.08 Si2PO 12 , which is prepared by the solid-phase method. The specific steps are as follows:

[0108] 1. Weigh the required stoichiometric amount of 100% zirconium oxide and the required stoichiometric amount of 100% magnesium oxide, strontium oxide and aluminum oxide in a stoichiometric ratio of 1.8:0.06:0.06:0.08, put them into a ball mill together, add anhydrous ethanol, and ball mill for 4 hours at a ball milling speed of 700 rpm; after ball milling, dry them at 100°C for 24 hours, take them out and grind them, and then put them into a muffle furnace, calcine them in an air atmosphere to obtain a light yellow blocky zirconium oxide precursor, the calcination temperature is 1550°C, the calcination time is 6 hours, the heating rate is 5°C / min, and the blocky precursor is crushed and ground to obtain a zirconium oxide precursor powder;

[0109] 2. Weigh zirconium oxide precursor powder, sodium carbonate, silicon dioxide, and ammonium dihydrogen phosphate according to the stoichiometric ratio of 2:1.66:2:1, wherein sodium carbonate is 10% in excess and ammonium dihydrogen phosphate is 5% in excess. After being fully mixed, place them in a ball mill and add deionized water for ball milling. The ball milling speed is 600 rpm and the ball milling time is 12 h. After the ball milling is completed, dry them at 100 ° C for 24 h, take them out and grind them, place them in a muffle furnace, and calcine them in an air atmosphere to obtain a white solid powder. The calcination temperature is 200 ° C. The temperature was 850°C, the calcination time was 12h, and the heating rate was 2°C / min; the white solid powder was crushed and ground and placed in a ball mill, and anhydrous ethanol was added for secondary ball milling, the ball milling speed was 700rpm, and the ball milling time was 12h; after the ball milling was completed, it was dried at 100°C for 12h, taken out and ground for 20min, sieved with a 200-mesh screen, and uniaxially pressed at a pressure of 20Mpa for 20min to obtain a ceramic solid electrolyte green sheet with a diameter of 20mm and a thickness of 2.2mm;

[0110] 3. Place the ceramic solid electrolyte green sheet in a crucible, bury the powder up and down, and calcine in an air atmosphere, wherein the calcination temperature is 1140°C, the calcination time is 10 hours, and the heating rate is 2°C / min; after naturally cooling to room temperature, grind and polish to obtain a NASICON type sodium ion solid electrolyte.

[0111] Figure 14 For the preparation of Na 3.32 Zr 1.8 Mg 0.06 Sr 0.06 Al 0.08 Si2PO 12 The X-ray diffraction pattern (XRD) of the solid electrolyte sheet is similar to Figure 8 Similar, Na 3.32 Zr 1.8 Mg 0.06 Sr 0.06 Al 0.08 Si2PO 12The main characteristic peaks are in agreement with the standard PDF cards. There is no appearance of the m-ZrO2 diffraction peak, and there is a small amount of Mg and Sr-doped Na3PO4 secondary phase with medium ionic conductivity, resulting in a NASICON-type sodium-ion solid electrolyte with relatively high purity.

[0112] Figure 15 For the prepared Na 3.32 Zr 1.8 Mg 0.06 Sr 0.06 Al 0.08 Si2PO 12 Cross-sectional SEM image of the solid electrolyte sheet. The results are Figure 2 similar. The grain size is smaller and the porosity is less compared to the undoped Na3Zr2Si2PO 12 . By measuring with the Archimedes drainage method, the density is obtained as 92.3%, which is consistent with the low porosity reflected by the cross-sectional SEM image.

[0113] Using an ion sputtering instrument, a gold electrode is evenly coated on both sides of the Na 3.32 Zr 1.8 Mg 0.06 Sr 0.06 Al 0.08 Si2PO 12 solid electrolyte sheet. Its ionic conductivity at room temperature is tested by an electrochemical workstation as Figure 16 shown. After testing, the ionic conductivity of the Na 3.32 Zr 1.8 Mg 0.06 Sr 0.06 Al 0.08 Si2PO 12 solid electrolyte sheet at room temperature is 1.12 mS / cm, indicating that doping with the three elements of Mg, Sr, and Al is beneficial to improving the ionic conductivity of the NASICON-type sodium-ion solid electrolyte.

[0114] The Arrhenius plot of the NASICON-type sodium-ion solid electrolyte prepared in this example is fitted and calculated. The obtained results are Figure 4 similar. Compared with the undoped Na3Zr2Si2PO 12 , it has a lower activation energy, which is beneficial to the migration of sodium ions. The attached drawings are not repeated in this example.

[0115] Example 6

[0116] This example provides a NASICON-type sodium-ion solid electrolyte material with the chemical formula: Na 3.32 Zr 1.8 Mg 0.1 2Y 0.04 La 0.04Si2PO 12 , it is prepared by a solid-phase method, and the specific steps are as follows:

[0117] I. Weigh zirconia, magnesia, yttria, and lanthanum oxide with stoichiometric ratios of 100% according to the stoichiometric ratio of 1.8:0.12:0.04:0.04, put them into a ball mill together, add absolute ethanol, and ball mill at a ball milling speed of 500 rpm for 3 h; after ball milling, dry at 100 °C for 24 h, take out and grind, then put it into a muffle furnace, and calcine in an air atmosphere to obtain a pale yellow massive zirconia precursor. The calcination temperature is 1550 °C, the calcination duration is 6 h, and the heating rate is 5 °C / min. After crushing and grinding the massive precursor, zirconia precursor powder is obtained;

[0118] II. Weigh zirconia precursor powder, sodium carbonate, silicon dioxide, and ammonium dihydrogen phosphate according to the stoichiometric ratio of 2:1.66:2:1, where sodium carbonate is in excess by 10% and ammonium dihydrogen phosphate is in excess by 5%. After fully mixing, put it into a ball mill, add deionized water for ball milling. The ball milling speed is 600 rpm, and the ball milling time is 12 h; after ball milling, dry at 100 °C for 24 h, take out and grind, then put it into a muffle furnace, and calcine in an air atmosphere to obtain a white solid powder. The calcination temperature is 950 °C, the calcination duration is 10 h, and the heating rate is 3 °C / min; after crushing and grinding the white solid powder, put it into a ball mill, add absolute ethanol for secondary ball milling. The ball milling speed is 700 rpm, and the ball milling time is 12 h; after ball milling, dry at 100 °C for 12 h, take out and grind for 20 min, sieve with a 200-mesh sieve, and uniaxially press for 20 min under a pressure of 20 Mpa to obtain a green ceramic solid electrolyte sheet with a diameter of 20 mm and a thickness of 2.2 mm;

[0119] III. Put the green ceramic solid electrolyte sheet into a crucible, bury the powder above and below, and calcine in an air atmosphere. The calcination temperature is 1200 °C, the calcination duration is 12 h, and the heating rate is 5 °C / min; after natural cooling to room temperature, polish to obtain a NASICON-type sodium ion solid electrolyte.

[0120] Figure 17 For the prepared Na 3.32 Zr 1.8 Mg 0.12 Y 0.04 La 0.04 Si2PO 12 X-ray diffraction pattern (XRD) of the solid electrolyte sheet, the result is similar to Figure 8 similar, Na 3.32 Zr 1.8 Mg 0.12 Y 0.04 La 0.04Si2PO 12 The main characteristic peaks are consistent with the standard PDF card. There is no appearance of the m-ZrO2 diffraction peak. There is a small amount of Mg and La-doped Na3PO4 secondary phase with medium ionic conductivity, and a NASICON-type sodium ion solid electrolyte with relatively high purity is obtained.

[0121] Figure 18 For the prepared Na 3.32 Zr 1.8 Mg 0.12 Y 0.04 La 0.04 Si2PO 12 The cross-sectional SEM image of the solid electrolyte sheet, and the result is similar to Figure 2 that of the undoped Na3Zr2Si2PO 12 The grain size is more uniform and there are fewer pores. Measured by the Archimedes drainage method, the density is 93.5%, which is consistent with the low porosity reflected by the cross-sectional SEM image.

[0122] Using an ion sputtering instrument, a layer of gold electrode is evenly coated on both sides of the Na 3.32 Zr 1.8 Mg 0.12 Y 0.04 La 0.04 Si2PO 12 solid electrolyte sheet. The ionic conductivity at room temperature is tested by an electrochemical workstation as shown in Figure 19 The measured ionic conductivity of the Na 3.32 Zr 1.8 Mg 0.12 Y 0.04 La 0.04 Si2PO 12 solid electrolyte sheet at room temperature is 1.20 mS / cm, indicating that doping with the three elements of Mg, Y, and La is beneficial to improving the ionic conductivity of the NASICON-type sodium ion solid electrolyte.

[0123] The Arrhenius plot of the NASICON-type sodium ion solid electrolyte prepared in this example is fitted and calculated, and the result is similar to Figure 4 that of the undoped Na3Zr2Si2PO 12 It has a lower activation energy, which is beneficial to the migration of sodium ions. The attached drawings are not repeated in this example.

[0124] Comparative example

[0125] This example provides a NASICON-type sodium ion solid electrolyte material with the chemical formula: Na3Zr2Si2PO 12 , which is prepared by the solid-phase method. The specific steps are as follows:

[0126] 1. Weigh zirconia, sodium carbonate, silica, and ammonium dihydrogen phosphate according to the stoichiometric ratio of 2:1.5:2:1. Among them, sodium carbonate is in excess by 10%, and ammonium dihydrogen phosphate is in excess by 5%. After thorough mixing, place them in a ball mill, add deionized water, and perform ball milling. The ball milling speed is 600 rpm / min, and the ball milling time is 12 h. After the ball milling is completed, dry at 100 °C for 24 h, take out and grind, then place it in a muffle furnace and calcine in an air atmosphere to obtain a white solid powder. Among them, the calcination temperature is 900 °C, the calcination duration is 6 h, and the heating rate is 5 °C / min. Crush and grind the white solid powder, then place it in a ball mill, add anhydrous ethanol for secondary ball milling. The ball milling speed is 700 rpm, and the ball milling time is 12 h. After the ball milling is completed, dry at 100 °C for 12 h, take out and grind for 20 min, sieve through a 200-mesh sieve, and then uniaxially press for 20 min under a pressure of 20 Mpa to obtain a green body sheet of ceramic solid electrolyte with a diameter of 20 mm and a thickness of 2.2 mm.

[0127] 2. Place the green body sheet of ceramic solid electrolyte in a crucible, bury the powder above and below, and calcine in an air atmosphere. Among them, the calcination temperature is 1160 °C, the calcination duration is 6 h, and the heating rate is 5 °C / min. After natural cooling to room temperature, polish to obtain a NASICON-type sodium ion solid electrolyte.

[0128] Figure 20 For the preparation of Na3Zr2Si2PO 12 X-ray diffraction pattern (XRD) of the solid electrolyte sheet, the results show that the main characteristic peaks of Na3Zr2Si2PO 12 match its standard PDF card. The appearance of m-ZrO2 diffraction peaks near 28° and 31° indicates the formation of m-ZrO2 impurities. The purity of the obtained NASICON-type sodium ion solid electrolyte is lower than that of Examples 1 - 6.

[0129] Figure 21 For the preparation of Na3Zr2Si2PO 12 Cross-sectional SEM image of the solid electrolyte sheet. The results show that compared with Examples 1 - 6, the grain size distribution of the comparative example is uneven and there are more pores. By measuring with the Archimedes drainage method, the density is obtained as 90.2%, which is lower than that of Examples 1 - 6, corresponding to the more pore phenomenon reflected in the cross-sectional SEM image.

[0130] Use an ion sputtering instrument to evenly coat a layer of gold electrodes on both sides of the Na3Zr2Si2PO 12 solid electrolyte sheet, and test its ionic conductivity at room temperature through an electrochemical workstation as Figure 22 shown. After testing, Na3Zr2Si2PO 12The ionic conductivity of the solid electrolyte sheet at room temperature is 0.43 mS / cm, indicating that the undoped Na3Zr2Si2PO 12 The ionic conductivity is low at room temperature. The presence of m-ZrO2 impurities and the large number of pores between grains are important factors leading to its low conductivity.

[0131] Figure 23 For the preparation of Na3Zr2Si2PO 12 Arrhenius curve of the solid electrolyte sheet. Na3Zr2Si2PO was calculated based on the slope of the fitting curve. 12 The activation energy of the solid electrolyte sheet is 0.36 eV.

[0132] The above is a detailed introduction to a zirconium oxide precursor and a NASICON-type sodium ion solid electrolyte and a preparation method provided by the present invention. This article uses specific examples to illustrate the principles and specific implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core technology; at the same time, for a general technician in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A zirconium oxide precursor and a NASICON type sodium ion solid electrolyte material and a preparation method thereof, characterized in that: The zirconium source of the solid electrolyte material is a zirconium oxide precursor prepared by doping zirconium oxide with low-valent metal oxides, and the low-valent element partially replaces the Zr position in the NASICON structure. The low-valent element is one or more of Ca, Sr, Mg, Ba, Y, La, Al, and In.

2. The zirconium oxide precursor material according to claim 1, characterized in that The general chemical formula of the zirconium oxide precursor material is: Zr (2-x-y) / 2 M Ⅰ x / 2 M Ⅱ y / 2 O2, the x and y are the molar numbers of the corresponding elements, wherein 0≤x≤0.5, 0≤y≤0.5, and x and y are not 0 at the same time.

3. A NASICON type sodium ion solid electrolyte material according to claim 1, characterized in that The zirconium source of the solid electrolyte material is a zirconium oxide precursor prepared by doping zirconia with a low-valent metal oxide. The chemical general formula of the solid electrolyte material is: Na 1+2x+y+z Zr 2-x-y M Ⅰ x M Ⅱ y Si z P 3-z O 12 , where x, y, and z are the molar amounts of the corresponding elements, respectively. Among them, 0 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.5, 0 < z < 3, and x and y are not both 0 at the same time.

4. A NASICON type sodium ion solid electrolyte material according to claim 1, characterized in that M described in claim 2 Ⅰ is a divalent metal element doped to replace Zr, including one or more of Ca, Sr, Mg, and Ba. Ⅱ It is a trivalent metal element doped to replace the Zr position, including one or more of Y, La, Al, and In.

5. The method for preparing a zirconium oxide precursor and a NASICON type sodium ion solid electrolyte material according to claim 1, characterized in that The preparation method is a solid phase method, which specifically includes the following steps:

1. Mix 100% of the required stoichiometric amount of zirconium oxide and 100% of the required stoichiometric amount of M-containing Ⅰ 、M Ⅱ The elemental metal oxides are weighed and mixed by ball milling according to a stoichiometric ratio of 2-xy:x:y, dried and ground, and then calcined in an air atmosphere to obtain a light yellow blocky zirconium oxide precursor, and the blocky precursor is crushed to obtain a zirconium oxide precursor powder; 2. The zirconium oxide precursor powder described in step 1 is fully mixed with a sodium source, a silicon source, and a phosphorus source, and then placed in a ball mill for ball milling. After drying and grinding, the mixture is calcined in an air atmosphere to obtain a white solid powder. The white solid powder is ball milled, dried, ground, sieved, and then pressed under a pressure of 10 to 100 MPa to obtain a ceramic solid electrolyte green sheet; 3. Calcine the ceramic solid electrolyte green sheet described in step 2 in an air atmosphere to obtain the NASICON type sodium ion solid electrolyte material.

6. The method for preparing a zirconium oxide precursor and a NASICON type sodium ion solid electrolyte material according to claim 1, characterized in that The ball milling speed in step 1 is 400-800 rpm, and the ball milling time is 1-12 h; The calcination temperature is 1200-1600° C., the calcination time is 2-10 hours, and the calcination heating rate is 1-10° C. / min.

7. The method for preparing a zirconium oxide precursor and a NASICON type sodium ion solid electrolyte material according to claim 1, characterized in that The sodium source described in step 2 is one or more of Na2CO3, NaHCO3, Na2C204, Na3PO4, Na2HPO4, NaH2PO4, and NaOH; the silicon source is one or more of SiO2, Si(OC2H5)4, and Si(OCH3)4; the phosphorus source is one or more of P2O5, NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, Na3PO4, Na2HPO4, and NaH2PO4.

8. The method for preparing a zirconium oxide precursor and a NASICON type sodium ion solid electrolyte material according to claim 1, characterized in that The calcination temperature in step 2 is 400-1000° C., the calcination time is 6-12 hours, and the calcination heating rate is 1-10° C. / min.

9. The method for preparing a zirconium oxide precursor and a NASICON type sodium ion solid electrolyte material according to claim 1, characterized in that The calcination temperature in step 3 is 1000-1300° C., the calcination time is 5-14 hours, and the calcination heating rate is 1-5° C. / min.

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