Preparation method and application of silicon-based potassium ion solid electrolyte material and optimized modification thereof

Abstract

The application discloses a novel silicon-based potassium ion solid electrolyte material and a preparation method and application of optimized modification thereof, and belongs to the technical field of potassium ion solid electrolyte materials. 3‑ x LnSi (3‑x) P x O9 (x=0~0.3), wherein Ln is Y or Gd. The solid electrolyte material is prepared by a solid phase method, has the advantages of simple preparation method and strong ion conductive capacity, has good practical value, and can be applied to a potassium ion solid-state battery.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of potassium ion batteries, in particular to a silicon-based potassium ion solid electrolyte material and optimization modification thereof, and especially to a novel silicon-based potassium ion solid electrolyte material and a preparation method and application of optimization modification thereof. BACKGROUND

[0002] Large-scale energy storage systems can store unevenly distributed and intermittent wind and solar energy and output stable, flexible and controllable energy, which is conducive to solving energy problems and promoting sustainable economic development. In the field of large-scale energy storage systems, traditional liquid lithium ion batteries have certain limitations, including relatively high prices and difficult to fully guarantee safety. Mainly, the content of lithium resources on the earth is low and the distribution is seriously uneven, making it difficult to control and predict the cost. Secondly, liquid batteries need to use a large amount of organic solvents, which leads to safety hazards such as flammability, volatility and leakage. In the face of these problems, it is completely necessary and must be implemented to find an effective substitute for lithium ion batteries.

[0003] It is worth noting that the content of potassium in the earth's crust is high and there is no regional restriction. With the in-depth research of potassium ion batteries, potassium ion batteries are concerned due to their low cost, ecological friendliness and high energy density. Since the safety hazards of organic solvents exist in liquid lithium ion batteries, they are also reproduced in liquid potassium ion battery systems. And large-scale energy storage systems will amplify this problem, so it is particularly important to develop potassium ion solid-state batteries with higher safety and higher energy density, which have strong competitiveness in low cost, high safety and energy density, and also show great application value and business prospects.

[0004] As the most important component of potassium solid-state batteries, developing high-performance and high-quality potassium ion solid electrolytes is the common pursuit of relevant researchers. At present, some research work has achieved great success, but due to the large ionic radius and high mass of potassium ions, the transmission of potassium ions in electrolytes has certain difficulties. The reported potassium ion solid electrolytes are very limited in type and quantity, and the ionic conductivity is generally low, and only a few solid-state potassium batteries have successfully undergone electrochemical performance tests. The research on potassium ion solid electrolyte conductors is still in the early stage, and exploring potential potassium ion conductors with high ionic conductivity and physical / electrochemical stability is a necessary and challenging task. SUMMARY

[0005] In view of the limitations of the existing solid electrolyte types, the application provides a new type of silicon-based potassium ion solid electrolyte material and an optimized modification preparation method and application thereof. The purpose is to develop and prepare a new type of solid electrolyte material suitable for potassium ion conduction; to expand the application system of potassium ion solid electrolyte material; and to provide a universal research idea for optimizing and modifying ion (such as potassium ion) transmission.

[0006] The application provides a new type of silicon-based potassium ion solid electrolyte material, characterized in that the chemical formula of the new type of silicon-based potassium ion solid electrolyte material is K (3-x) LnP x Si (3-x) O9, x = 0-0.3, Ln is Y or Gd, each pair of silicon oxygen tetrahedron in the crystal framework shares a vertex, forming a silicate framework with [Si3O9] helical chain as a complex group, and anion [LnSi3O9] n 3n- The framework is a three-dimensional channel system, the main channels are parallel to

[100] and

[010] directions, and three crystallographically different K atom positions are distributed in the channels, and the solid electrolyte material is a three-dimensional network structure.

[0007] The application also provides a preparation method of the new type of silicon-based potassium ion solid electrolyte material, characterized by comprising the following steps:

[0008] Potassium salt, trivalent metal oxide, silicon dioxide and phosphate are taken as precursors, and a solvent is added in a proportion of 1 g / mL according to the mass of the precursors, and then sufficient ball milling is performed to obtain a uniform precursor mixture; the solvent is removed by drying, and the precursor is calcined in a muffle furnace at 500-900 DEG C to promote the decomposition of the precursor and the synthesis of the intermediate phase; the intermediate phase is pressed by a unidirectional cold press machine at 200-400 MPa for 10-60 seconds to obtain a complete wafer; the wafer is calcined in a muffle furnace at 1100-1300 DEG C to obtain the solid electrolyte material K (3-x) LnP x Si (3-x) O9.

[0009] Preferably, according to one or more embodiments of the application, the potassium salt in the preparation method of the new type of silicon-based potassium ion solid electrolyte material is any one of potassium carbonate, potassium acetate and potassium nitrate.

[0010] Preferably, according to one or more embodiments of the application, the trivalent metal oxide in the preparation method of the new type of silicon-based potassium ion solid electrolyte material is any one of yttrium oxide or gadolinium oxide.

[0011] Preferably, according to one or more embodiments of the present application, the phosphate in the preparation method of the new silicon-based potassium ion solid electrolyte material is any one of di-ammonium hydrogen phosphate, ammonium dihydrogen phosphate, potassium hypophosphite, and tripotassium phosphate.

[0012] Preferably, according to one or more embodiments of the present application, the solvent in the preparation method of the new silicon-based potassium ion solid electrolyte material is any one of isopropyl alcohol and acetone, the drying temperature is 60-120℃, and the drying time is 6-36h.

[0013] Preferably, according to one or more embodiments of the present application, the time for the 500-900℃ calcination in the preparation method of the new silicon-based potassium ion solid electrolyte material is 3-12h.

[0014] Preferably, according to one or more embodiments of the present application, the time for the 1100-1300℃ calcination in the preparation method of the new silicon-based potassium ion solid electrolyte material is 1-24h.

[0015] Preferably, according to one or more embodiments of the present application, the content of the heterovalent element P in the preparation method of the new silicon-based potassium ion solid electrolyte material needs to be maintained within the performance improvement range, and the content is between 0 and 0.3.

[0016] The present application also provides the application of the above-mentioned new silicon-based potassium ion solid electrolyte material as a solid electrolyte.

[0017] The technical scheme of the present application has the following advantages:

[0018] The present application provides a material system suitable for potassium ion solid electrolyte. The material system is a three-dimensional network structure, and there is a large ion migration bottleneck in the crystal structure, and the distance between potassium ions is close, which provides favorable conditions for the rapid migration of ions. The AC impedance test and ion conductivity calculation of the potassium ion solid electrolyte of the system show that the ion conductivity of K3YSi3O9 at 60℃ is 7.92×10 -3 mS / cm, and the ion conductivity of K3GdSi3O9 at 60℃ is 1.02×10 -2 mS / cm. Further, the heterovalent element P is introduced into the system for optimization and modification, and the purpose is to adjust the crystal structure of the material and to create potassium ion vacancies or increase new potassium ion sites, thereby improving the performance. The ion conductivity of K 2.8 GdP 0.2 Si 2.8 O9 at 60℃ is 8.82×10 -2 mS / cm, which has a high ion conductivity. Based on K (3-x) LnP x Si(3-x) The application also shows that the potassium ion solid electrolyte material has good application prospect in the potassium ion solid-state battery as the conductive ability of O9(x=0~0.3), and provides a new idea for the development and optimization of the potassium ion solid electrolyte material. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the drawings needed in the description of the specific embodiments or prior art will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0020] Figure 1 The XRD pattern of the potassium ion solid electrolyte K3YSi3O9 obtained in the present application examples 1-3 is shown in the following figure:

[0021] Figure 2 The ion conductivity pattern of the potassium ion solid electrolyte K3YSi3O9 obtained in the present application examples 1-3 is shown in the following figure:

[0022] Figure 3 The scanning electron microscope pattern of the potassium ion solid electrolyte K3YSi3O9 obtained in the present application example 3 is shown in the following figure:

[0023] Figure 4 The crystal structure pattern of the potassium ion solid electrolyte K3YSi3O9 obtained in the present application example 3 is shown in the following figure:

[0024] Figure 5 The XRD pattern of the potassium ion solid electrolyte K3GdSi3O9 obtained in the present application examples 4-6 is shown in the following figure:

[0025] Figure 6 The ion conductivity pattern of the potassium ion solid electrolyte K3GdSi3O9 obtained in the present application examples 4-6 is shown in the following figure:

[0026] Figure 7 The scanning electron microscope pattern of the potassium ion solid electrolyte K3GdSi3O9 obtained in the present application example 6 is shown in the following figure:

[0027] Figure 8 The crystal structure pattern of the potassium ion solid electrolyte K3GdSi3O9 obtained in the present application example 6 is shown in the following figure:

[0028] Figure 9 The XRD pattern of the potassium ion solid electrolyte K (3-x) GdP x Si (3-x) O9(x=0~0.3) obtained in the present application examples 6-9 is shown in the following figure:

[0029] Figure 10 Potassium ion solid electrolyte K (3-x) GdP x Si (3-x) Ionic conductivity graph of K3YSi3O9(x = 0 ~ 0.3);

[0030] Figure 11 Potassium ion solid electrolyte K 2.8 GdP 0.2 Si 2.8 Scanning electron microscope graph of K3YSi3O9;

[0031] Figure 12 Potassium ion solid electrolyte K 2.8 GdP 0.2 Si 2.8 Voltage window test CV graph of K3YSi3O9.

[0032] Figure 13 Potassium ion solid electrolyte K 2.8 GdP 0.2 Si 2.8 Cycle performance graph of K3YSi3O9 matching Prussian blue positive electrode and potassium carbon composite negative electrode.

[0033] Figure 14 Potassium ion solid electrolyte K 2.8 GdP 0.2 Si 2.8 Cycle performance graph of K3YSi3O9 matching high-voltage vanadium potassium phosphate positive electrode and potassium carbon composite negative electrode. DETAILED DESCRIPTION

[0034] The application will be further described below in connection with specific embodiments. It should be understood that these embodiments are only used to illustrate the application and not used to limit the protection scope of the application. Furthermore, it should be understood that after reading the disclosure of the application, those skilled in the art can make various modifications or changes to the application, and these equivalent forms also fall within the protection scope of the application.

[0035] The experimental methods used in the following examples are conventional methods unless otherwise specified; the reagents, materials, instruments, etc. used in the following examples can be obtained from commercial channels unless otherwise specified.

[0036] Example 1

[0037] A potassium ion solid electrolyte material K3YSi3O9, the preparation method of which is as follows:

[0038] Experimental method of the precursor mixture: the potassium salt is anhydrous potassium carbonate, the rare earth metal oxide is yttrium oxide, and the silicon dioxide, wherein the mass of each component is weighed according to the molar mass ratio of potassium element: yttrium element: silicon element = 3: 1: 3. The precursor solvent is isopropyl alcohol. The prepared precursor substances and solvent are sealed in a ball milling tank and ball milled in a planetary ball mill at a speed of 250 rpm for 6 hours. Then the mixed slurry is transferred to a 120°C air drying oven and dried for 12 hours to remove the solvent isopropyl alcohol.

[0039] Experimental method of pretreatment: the obtained precursor mixture is first ground in a mortar, and then the powder is transferred to an alumina crucible and pretreated in a muffle furnace, wherein the calcination temperature is 600°C and the holding time is 5 hours to obtain sample A1.

[0040] Experimental method of sintering: the sample A1 obtained by the above pretreatment is again ground in a mortar, and then an appropriate amount of sample A1 is weighed in a tablet press mold to obtain a dense sample B1 by keeping the unidirectional pressure at 400 MPa for 60 s. Then the sample B1 is calcined in an alumina crucible, wherein the sintering temperature is 1200°C and the holding time is 5 hours to obtain sample C1.

[0041] Example 2

[0042] A potassium ion solid electrolyte material K3YSi3O9, a preparation method thereof is:

[0043] Experimental method of the precursor mixture: the potassium salt is anhydrous potassium carbonate, the rare earth metal oxide is yttrium oxide, and the silicon dioxide, wherein the mass of each component is weighed according to the molar mass ratio of potassium element: yttrium element: silicon element = 3: 1: 3. The precursor solvent is isopropyl alcohol. The prepared precursor substances and solvent are sealed in a ball milling tank and ball milled in a planetary ball mill at a speed of 250 rpm for 6 hours. Then the mixed slurry is transferred to a 120°C air drying oven and dried for 12 hours to remove the solvent isopropyl alcohol.

[0044] Experimental method of pretreatment: the obtained precursor mixture is first ground in a mortar, and then the powder is transferred to an alumina crucible and pretreated in a muffle furnace, wherein the calcination temperature is 600°C and the holding time is 5 hours to obtain sample A2.

[0045] Experimental method of sintering: the sample A2 obtained by the above pretreatment is again ground in a mortar, and then an appropriate amount of sample A2 is weighed in a tablet press mold to obtain a dense sample B2 by keeping the unidirectional pressure at 400 MPa for 60 s. Then the sample B2 is calcined in an alumina crucible, wherein the sintering temperature is 1250°C and the holding time is 5 hours to obtain sample C2.

[0046] Example 3

[0047] A potassium ion solid electrolyte material K3YSi3O9, a preparation method thereof is:

[0048] Experimental method of precursor mixture: the potassium salt is anhydrous potassium carbonate, the rare earth metal oxide is yttrium oxide, and the silicon dioxide, wherein the mass of each component is weighed according to the molar mass ratio of potassium element: yttrium element: silicon element = 3: 1: 3. The precursor solvent is isopropyl alcohol. The prepared precursor substances and solvents are sealed in a ball milling tank and ball milled in a planetary ball mill at a speed of 250 rpm for 6 hours. Then the mixed slurry is transferred to a 120°C air drying oven and dried for 12 hours to remove the isopropyl alcohol solvent.

[0049] Experimental method of pretreatment: the above obtained precursor mixture is first ground in a mortar, and then the powder is transferred to an alumina crucible and pretreated in a muffle furnace, wherein the calcination temperature is 600°C and the holding time is 5 hours to obtain sample A3.

[0050] Experimental method of sintering: the sample A3 obtained by the above pretreatment is again ground in a mortar, and then an appropriate amount of sample A3 is weighed in a tablet press mold to obtain a dense sample B3 by maintaining a unidirectional pressure of 400 MPa for 60 s. Then the sample B3 is calcined in an alumina crucible, wherein the sintering temperature is 1300°C and the holding time is 5 hours to obtain sample C3.

[0051] XRD characterization of the potassium ion solid electrolyte obtained in the above examples 1-3: the sample C1-C3 is ground into powder in a mortar, wherein the XRD characterization test 2θ angle is 10-80°.

[0052] Figure 1 is the XRD pattern obtained by testing the sample C1-C3.

[0053] The potassium ion solid electrolyte obtained in the above examples is subjected to alternating current impedance test to calculate the ionic conductivity: the two sides of the sample C1-C3 are respectively smeared with silver paste, and dried in a 70°C air drying oven to obtain a sandwich type (Ag / K3YSi3O9 / Ag) symmetrical battery. The ionic conductivity is calculated by alternating current impedance characterization, wherein the test frequency range is 10 6 -0.1 Hz, the impedance of the electrolyte sheet is obtained by fitting, and the formula σ = L / (RS) is brought in, wherein σ is the ionic conductivity, L is the thickness of the electrolyte sheet, R is the impedance obtained by fitting, and S is the opposite area of the electrolyte sheet.

[0054] Figure 2 is the comparison of the ionic conductivity of the electrolyte K3YSi3O9 at different calcination temperatures, wherein the sample calcined at 1300 degrees is the best, and at 60 degrees it is 7.92 x 10-3 mS / cm, which indicates that this solid electrolyte has excellent ionic conductive ability.

[0055] Figure 3 is a scanning electron microscope image of K3YSi3O9 calcined at 1300 degrees.

[0056] Figure 4 is a crystal structure diagram of K3YSi3O9.

[0057] Example 4

[0058] A potassium ion solid electrolyte material K3GdSi3O9, the preparation method of which is:

[0059] The experimental method of the precursor mixture is as follows: the potassium salt is anhydrous potassium carbonate, the rare earth metal oxide is gadolinium oxide, and the silicon dioxide, wherein the mass of each component is weighed according to the molar mass ratio of potassium element: gadolinium element: silicon element = 3: 1: 3. The precursor solvent is acetone. The prepared precursor substances and solvent are sealed in a ball mill tank and ball milled in a planetary ball mill at a speed of 250 rpm for 6 hours. Then the mixed slurry is transferred to a 80°C air drying oven and dried for 3 hours to remove the solvent acetone.

[0060] The experimental method of the pretreatment is as follows: the above obtained precursor mixture is first ground in a mortar, and then the powder is transferred to an alumina crucible and pretreated in a muffle furnace, wherein the calcination temperature is 600°C and the holding time is 5 hours, to obtain sample A4.

[0061] The experimental method of the sintering is as follows: the sample A4 obtained by the above pretreatment is again ground in a mortar, and then an appropriate amount of sample A4 is weighed in a tablet press mold to obtain a dense sample B4 by keeping the unidirectional pressure at 400 MPa for 60 s. Then the sample B4 is sintered in an alumina crucible, wherein the sintering temperature is 1200°C and the holding time is 12 hours, to obtain sample C4.

[0062] Example 5

[0063] A potassium ion solid electrolyte material K3GdSi3O9, the preparation method of which is:

[0064] The experimental method of the precursor mixture is as follows: the potassium salt is anhydrous potassium carbonate, the rare earth metal oxide is gadolinium oxide, and the silicon dioxide, wherein the mass of each component is weighed according to the molar mass ratio of potassium element: gadolinium element: silicon element = 3: 1: 3. The precursor solvent is acetone. The prepared precursor substances and solvent are sealed in a ball mill tank and ball milled in a planetary ball mill at a speed of 250 rpm for 6 hours. Then the mixed slurry is transferred to a 80°C air drying oven and dried for 3 hours to remove the solvent acetone.

[0065] Pre-treatment experimental method: the precursor mixture obtained above was first ground thoroughly in a mortar, and then the powder was transferred to an alumina crucible and pre-treated in a muffle furnace, with a calcination temperature of 600°C and a holding time of 5 hours, to obtain sample A5.

[0066] Sintering experimental method: the sample A5 obtained after the above pre-treatment was again ground thoroughly in a mortar, and then an appropriate amount of sample A5 was weighed and pressed into a dense sample B5 in a tablet press mold at a unidirectional pressure of 400 MPa for 60 s. Then, the sample B5 was subjected to mother powder sintering in an alumina crucible, with a sintering temperature of 1250°C and a holding time of 12 hours, to obtain sample C5.

[0067] Example 6

[0068] A potassium ion solid electrolyte material K3GdSi3O9, a preparation method thereof is:

[0069] Preparation method of the precursor mixture: the potassium salt is anhydrous potassium carbonate, the rare earth metal oxide is gadolinium oxide, and the silicon dioxide, wherein the mass of each component is weighed according to the molar mass ratio of potassium element: gadolinium element: silicon element = 3:1:3. The precursor solvent is acetone. The prepared precursor substances and solvent are sealed in a ball milling tank and ball milled in a planetary ball mill at a speed of 250 rpm for 6 hours. Then, the mixed slurry is transferred to a 80°C air drying oven and dried for 3 hours to remove the solvent acetone.

[0070] Pre-treatment experimental method: the precursor mixture obtained above was first ground thoroughly in a mortar, and then the powder was transferred to an alumina crucible and pre-treated in a muffle furnace, with a calcination temperature of 600°C and a holding time of 5 hours, to obtain sample A6.

[0071] Sintering experimental method: the sample A6 obtained after the above pre-treatment was again ground thoroughly in a mortar, and then an appropriate amount of sample A6 was weighed and pressed into a dense sample B6 in a tablet press mold at a unidirectional pressure of 400 MPa for 60 s. Then, the sample B6 was subjected to mother powder sintering in an alumina crucible, with a sintering temperature of 1300°C and a holding time of 12 hours, to obtain sample C6.

[0072] XRD characterization of the potassium ion solid electrolyte obtained in the above examples 4-6: the samples C4-C6 were ground into powder in a mortar, and the XRD characterization was tested at a 2θ angle of 10-80°.

[0073] Figure 5 The XRD patterns obtained by testing samples C4-C6 are shown in the following table.

[0074] Figure 6The ionic conductivity of electrolyte K3GdSi3O9 at different calcination temperatures is compared. The sample calcined at 1300 degrees is the best, and at 60 degrees is 1.02×10 -2 mS / cm, indicating that this solid electrolyte has excellent ionic conductivity.

[0075] Figure 7 This is a scanning electron microscope image of K3GdSi3O9 calcined at 1300 degrees.

[0076] Figure 8 This is the crystal structure diagram of K3GdSi3O9.

[0077] Example 7

[0078] A potassium ion solid electrolyte material K 2.9 GDP 0.1 Si 2.9 O9, the preparation method thereof is as follows:

[0079] The precursor mixture experimental method: The potassium salt is anhydrous potassium carbonate, the rare earth metal oxide is gadolinium oxide, the phosphate is ammonium dihydrogen phosphate, and the silicon dioxide is weighed according to the molar mass ratio of potassium: gadolinium: phosphorus: silicon = 2.9:1:0.1:2.9. The precursor solvent is acetone. The prepared precursor materials and solvent are sealed in a ball mill jar and milled in a planetary ball mill at 250 rpm for 6 hours. The mixed slurry is then transferred to an 80°C forced air drying oven and dried for 3 hours to remove the acetone solvent.

[0080] Experimental method for pretreatment: The precursor mixture obtained above was first fully ground in a mortar, and then the powder was transferred to an alumina crucible and pretreated in a muffle furnace, wherein the calcination temperature was 600°C and the holding time was 5 hours to obtain sample A7.

[0081] Sintering Experimental Method: Sample A7, obtained after the above pretreatment, was thoroughly ground again in a mortar. An appropriate amount of Sample A7 was then pressed into a tableting mold at a uniaxial pressure of 400 MPa for 60 seconds to obtain a dense sample B7. Sample B7 was then sintered in an alumina crucible at a temperature of 1300°C for 12 hours to obtain Sample C7.

[0082] Example 8

[0083] A potassium ion solid electrolyte material K 2.8 GDP 0.2 Si 2.8 O9, the preparation method thereof is as follows:

[0084] Experimental method of the precursor mixture: the potassium salt is anhydrous potassium carbonate, the rare earth metal oxide is gadolinium oxide, the phosphate salt is ammonium dihydrogen phosphate, and the silicon dioxide, wherein the mass of each component is weighed according to the molar mass ratio of potassium element: gadolinium element: phosphorus element: silicon element = 2.8: 1: 0.2: 2.8. The precursor solvent is acetone. The prepared precursor substances and solvent are sealed in a ball milling tank and ball milled in a planetary ball mill at a speed of 250 rpm for 6 hours. Then the mixed slurry is transferred to a 80℃ air drying oven and dried for 3 hours to remove the solvent acetone.

[0085] Experimental method of pretreatment: the above obtained precursor mixture is first ground in a mortar, and then the powder is transferred to an alumina crucible and pretreated in a muffle furnace, wherein the calcination temperature is 600℃ and the holding time is 5 hours, to obtain sample A8.

[0086] Experimental method of sintering: the sample A8 obtained by the above pretreatment is again ground in a mortar, and then an appropriate amount of sample A8 is weighed in a tablet press mold to obtain a dense sample B8 by keeping the unidirectional pressure at 400 MPa for 60 s. Then the sample B8 is sintered in an alumina crucible, wherein the sintering temperature is 1300℃ and the holding time is 12 hours, to obtain sample C8.

[0087] Example 9

[0088] A potassium ion solid electrolyte material K 2.7 GdP 0.3 Si 2.7 O9, a preparation method thereof is:

[0089] Experimental method of the precursor mixture: the potassium salt is anhydrous potassium carbonate, the rare earth metal oxide is gadolinium oxide, the phosphate salt is ammonium dihydrogen phosphate, and the silicon dioxide, wherein the mass of each component is weighed according to the molar mass ratio of potassium element: gadolinium element: phosphorus element: silicon element = 2.7: 1: 0.3: 2.7. The precursor solvent is acetone. The prepared precursor substances and solvent are sealed in a ball milling tank and ball milled in a planetary ball mill at a speed of 250 rpm for 6 hours. Then the mixed slurry is transferred to a 80℃ air drying oven and dried for 3 hours to remove the solvent acetone.

[0090] Experimental method of pretreatment: the above obtained precursor mixture is first ground in a mortar, and then the powder is transferred to an alumina crucible and pretreated in a muffle furnace, wherein the calcination temperature is 600℃ and the holding time is 5 hours, to obtain sample A9.

[0091] The experimental method of sintering: the sample A9 obtained by the above pretreatment is ground again in a mortar, and then an appropriate amount of sample A9 is weighed in a tablet press mold to obtain a dense sample B9 by maintaining a unidirectional pressure of 400 MPa for 60 s. Then, the sample B9 is subjected to mother powder sintering in an alumina crucible, wherein the sintering temperature is 1300°C, and the holding time is 12 hours, to obtain sample C9.

[0092] The potassium ion solid electrolyte obtained in the above examples 7-9 is subjected to XRD characterization: the sample C7-C9 is ground into powder in a mortar, and the XRD characterization is tested at a 2θ angle of 10-80°.

[0093] Figure 9 is the XRD pattern obtained by testing sample C6-C9.

[0094] Figure 10 is the electrolyte K (3-x) GdP x Si (3-x) O9(x=0~0.3) is compared, wherein K 2.8 GdP 0.2 Si 2.8 O9 is the best sample, which is 8.82×10 -2 mS / cm at 60 degrees, indicating that this solid electrolyte has high ion conductivity.

[0095] Figure 11 is the scanning electron microscope image of K 2.8 GdP 0.2 Si 2.8 O9.

[0096] Figure 12 is the CV test graph of the voltage window of K 2.8 GdP 0.2 Si 2.8 O9.

[0097] Figure 13 is the cycle performance graph of the Prussian blue positive electrode and the potassium carbon composite negative electrode matched with the solid electrolyte K 2.8 GdP 0.2 Si 2.8 O9.

[0098] Figure 14 is the cycle performance graph of the high-voltage vanadium potassium phosphate positive electrode and the potassium carbon composite negative electrode matched with the solid electrolyte K 2.8 GdP 0.2 Si 2.8 O9.

[0099] Obviously, the above embodiments are only examples and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments are not required to be exhaustive. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A silicon-based potassium ion solid electrolyte material, characterized by, The silicon-based potassium ion solid electrolyte material has a chemical formula of K (3-x) LnP x Si (3-x) O 9， x=0~0.3, Ln is Y or Gd, each pair of silicon oxygen tetrahedron in the crystal framework shares a vertex, forming a silicate framework with [Si3O9] spiral chain as a complex group, and anion [LnSi3O9] n 3n- The framework is a three-dimensional channel system, the main channels are parallel to [100] and [010] directions, and three crystallographically different K atom positions are distributed in the main channels, and the solid electrolyte material is a three-dimensional network structure.

2. The method for preparing a silicon-based potassium ion solid electrolyte material according to claim 1, wherein The method comprises the following steps: Potassium salt, trivalent metal oxide, silicon dioxide, phosphate as precursor, and according to the precursor quality, the solvent is added in the proportion of 1 g / mL, and then the uniform precursor mixture is obtained by ball milling; dry to remove the solvent, put it in the muffle furnace to promote the decomposition of the precursor and the synthesis of the intermediate phase at 500-900°C; the intermediate phase is pressed by the unidirectional cold isostatic press at 200-400MPa for 10-60 seconds to obtain a complete wafer; the wafer is calcined at 1100-1300°C in the muffle furnace to obtain a solid electrolyte material K (3-x) LnP x Si (3-x) O9.

3. The method for preparing a silicon-based potassium ion solid electrolyte material according to claim 2, wherein: The potassium salt is any one of potassium carbonate, potassium acetate, potassium nitrate.

4. The method for preparing a silicon-based potassium ion solid electrolyte material according to claim 2, wherein: The trivalent metal oxide is any one of yttrium oxide or gadolinium oxide.

5. The method of claim 2, wherein the silicon-based potassium ion solid electrolyte material is prepared by a process comprising: mixing a silicon-based compound and a potassium compound; and sintering the mixture. The phosphate is any one of diammonium hydrogen phosphate, ammonium dihydrogen phosphate, potassium hypophosphite, or tripotassium phosphate.

6. The method of claim 2, wherein the silicon-based potassium ion solid electrolyte material is prepared by a process comprising: mixing a silicon-based compound and a potassium compound to prepare a mixture; and heating the mixture at a temperature of 600 to 1,000°C for 1 to 10 hours in an inert gas atmosphere. The solvent is any one of isopropyl alcohol or acetone, the drying temperature is 60-120℃, and the drying time is 6-36h.

7. The method of claim 2, wherein the silicon-based potassium ion solid electrolyte material is prepared by a process comprising: mixing a silicon-based compound and a potassium compound to prepare a mixture; and heating the mixture at a temperature of 500 to 1,000 °C for 1 to 10 hours in an inert gas atmosphere. The calcination at 500-900℃ is performed for 3-12h.

8. The method of claim 2, wherein the silicon-based potassium ion solid electrolyte material is prepared by a process comprising: mixing a silicon-based compound and a potassium compound to prepare a mixture; and heating the mixture at a temperature of 500 to 1,000 °C for 1 to 10 hours in an inert gas atmosphere. The calcination at 1100-1300℃ is performed for 1-24h.

9. Application of the silicon-based potassium ion solid electrolyte material of claim 1 or the silicon-based potassium ion solid electrolyte material prepared by the method of any one of claims 2-8 as a solid electrolyte.

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