Method for preparing magnesium-based solid electrolytes

Abstract

The present invention relates to a magnesium-based solid electrolyte, a preparation method thereof, and a battery. The preparation method includes: mixing a magnesium compound, a titanium compound, and a phosphorus compound in a required theoretical mixing ratio to obtain a mixed precursor; pre-sintering the mixed precursor in an air atmosphere with a sintering temperature of 500°C to 700°C and a sintering time of 5 to 15 hours to obtain a sintered precursor; performing a pulverization treatment on the sintered precursor to obtain a powder material; sintering the powder material in an air atmosphere at 900°C to 1200°C for 5 to 10 hours and performing a crystallization treatment on the powder material to obtain a magnesium-based solid electrolyte.

Description

Technical Field

[0001] [Cross-reference] This application claims the priority of a Chinese patent application with the application number 202210891794.X, filed with the China National Intellectual Property Administration on July 27, 2022, and the invention title of "Magnesium-based Solid Electrolyte and Its Preparation Method and Battery".

[0002] The present invention relates to the technical field of new energy battery materials, and particularly to magnesium-based solid electrolytes, their preparation methods, and batteries.

Background Art

[0003] The deteriorating global environment and the continuous shortage of energy supply are the two most serious problems that humanity must face in the 21st century. The development and application of new energy and renewable clean energy have already brooked no delay. Since their emergence as a new type of green battery in 1990, lithium-ion secondary batteries have developed rather rapidly.

[0004] With the great success of lithium-ion batteries, magnesium, which is in a diagonal relationship with lithium in the periodic table, has similar ionic radius and chemical properties to lithium. In addition, as one of the light metal elements with the most abundant reserves on earth, magnesium is widely applied in various fields. As a result, the research on magnesium elements in the field of solid electrolytes has attracted the attention of many researchers. For example, Chinese Patent 202010803639.9 discloses a positive electrode material for a rechargeable magnesium battery and its manufacturing method. The pyrite-type compound contained in the positive electrode material of the rechargeable magnesium battery can simultaneously realize the valence change in the oxidation-reduction of cations and anions, and can increase the capacity and voltage of the positive electrode material.

[0005] Furthermore, magnesium is less reactive than lithium, easier to handle, non-polluting, and highly safe. Its price is also low, only 1 / 24th that of lithium. Therefore, advancing research on magnesium-based materials in solid electrolytes can alleviate the economic problems caused by the shortage of lithium raw materials, and developing research related to magnesium-based solid battery materials is of great significance for the sustainable development of energy in the future.

[0006] However, the reports currently available do not yet disclose methods for manufacturing magnesium titanium phosphate materials, particularly methods suitable for mass production. [Overview of the project] [Problems that the invention aims to solve]

[0007] The embodiments of the present invention provide a magnesium-based solid electrolyte, a method for preparing the same, and a battery. In this preparation method, pure-phase magnesium titanium phosphate powder is prepared by combining multi-stage solid-phase low-temperature sintering with multiple grinding cycles. The multiple grinding cycles increase the reaction activity between the powder particles, thereby enabling secondary sintering at low temperatures. This method is highly safe and advantageous for the mass production of magnesium titanium phosphate, a magnesium-based solid electrolyte. [Means for solving the problem]

[0008] In the first embodiment, the embodiment of the present invention is: The process involves mixing magnesium compounds, titanium compounds, and phosphorus compounds in the required theoretical mixing ratio to obtain a mixed precursor. The mixed precursor is pre-sintered in an air atmosphere, with a sintering temperature of 500°C to 700°C and a sintering time of 5 to 15 hours to obtain a sintered precursor. The aforementioned sintered precursor is subjected to a grinding process to obtain a powder material. The aforementioned powder material is sintered in an air atmosphere at 900°C to 1200°C for 5 to 10 hours, and the powder material is subjected to a crystallization treatment to obtain the magnesium-based solid electrolyte. including, This invention relates to a method for preparing magnesium-based solid electrolytes.

[0009] Preferably, the magnesium compound, titanium compound, and phosphorus compound are mixed in the required chemical measurement ratio, specifically as follows: Magnesium compounds, titanium compounds, and phosphorus compounds are mixed in a theoretical mixing ratio of Mg:Ti:P in a ratio of 1:5 to 9:7 to 15.

[0010] Preferably, the magnesium compound comprises one or more of magnesium oxide, magnesium carbonate, magnesium chloride, and magnesium hydroxide. The titanium compound comprises one or more of titanium oxide, titanium tetrachloride, and butyl titanate. The phosphorus compound comprises one or more of the following: solid phosphoric acid powder, diphosphorus pentoxide, ammonium dihydrogen phosphate, phosphorous acid, and hexametaphosphate.

[0011] Preferably, the grinding process is The sintered precursor is subjected to primary crushing in sequence using a jaw crusher and a roll crusher to obtain a first powder material with a particle size of 10 μm to 20 μm. The first powder material is subjected to a ball milling process, with a ball milling frequency of 200 Hz and a ball milling time of 2 hours, to obtain a second powder material with a particle size of 4 μm to 15 μm. The second powder material is subjected to jet milling to obtain a powder material with a particle size of 2 μm to 4 μm, Includes.

[0012] More preferably, after performing a crystallization treatment on the powder material, the method is performed The process further includes performing the grinding treatment on the product after the crystallization treatment to obtain the magnesium-based solid electrolyte.

[0013] In a second aspect, the embodiment of the present invention provides a magnesium-based solid electrolyte prepared by the magnesium-based solid electrolyte preparation method described in the first aspect.

[0014] Preferably, the magnesium-based solid electrolyte is a white powdery material with a particle size of 2 μm to 4 μm.

[0015] Preferably, the magnesium-based solid electrolyte is pure-phase magnesium titanium phosphate, and the chemical formula is Mg 0.5 Ti2(PO4)3.

[0016] Preferably, the XRD diffraction peaks of the magnesium-based solid electrolyte correspond one-to-one to those with a standard card number of PDF#82-0297.

[0017] In a third aspect, an embodiment of the present invention provides a battery including a magnesium-based solid electrolyte prepared by the method for preparing a magnesium-based solid electrolyte described in the first aspect.

Advantages of the Invention

[0018] In the method for preparing a magnesium-based solid electrolyte according to an embodiment of the present invention, by combining multi-stage solid-phase low-temperature sintering and multiple pulverizations, a pure-phase magnesium titanium phosphate powder is prepared. The reaction activity between powder particles is enhanced by multiple pulverizations, whereby secondary sintering can be performed at a low temperature, the safety of the preparation method is high, and it is advantageous for the mass production of magnesium titanium phosphate which is a magnesium-based solid electrolyte.

Brief Description of the Drawings

[0019] Hereinafter, with reference to the drawings and embodiments, the technical solutions of the embodiments of the present invention will be described in more detail.

[0020] [Figure 1] It is a flowchart of the method for preparing a magnesium-based solid electrolyte according to an embodiment of the present invention. [Figure 2] It is an X-ray diffraction (XRD) pattern of the sintering precursor after pulverization in Example 1 of the present invention. [Figure 3] It is an X-ray diffraction (XRD) pattern of magnesium titanium phosphate prepared in Example 1 of the present invention. [Modes for carrying out the invention]

[0021] The present invention will be further described below with reference to the drawings and specific embodiments, but these embodiments should be understood as being for illustrative purposes only and not as being intended to limit the present invention in any way, that is, not as limiting the scope of protection of the present invention.

[0022] This invention provides a method for preparing magnesium-based solid electrolytes that can be used industrially, filling a gap in the industrial preparation of magnesium titanium phosphate solid electrolyte materials within the industry.

[0023] The main preparation steps of the present invention include the following steps, as shown in Figure 1.

[0024] In step 110, the magnesium compound, titanium compound, and phosphorus compound are mixed in the required theoretical mixing ratio to obtain a mixed precursor.

[0025] The magnesium compound contains one or more of magnesium oxide, magnesium carbonate, magnesium chloride, and magnesium hydroxide; the titanium compound contains one or more of titanium oxide, titanium tetrachloride, and butyl titanate; and the phosphorus compound contains one or more of solid phosphoric acid powder, diphosphorus pentoxide, ammonium dihydrogen phosphate, phosphorous acid, and hexametaphosphate.

[0026] Magnesium compounds, titanium compounds, and phosphorus compounds are mixed from the selected compounds in a theoretical mixing ratio of Mg:Ti:P of 1:5 to 9:7 to 15.

[0027] In step 120, the mixed precursor is pre-sintered in an air atmosphere, with a sintering temperature of 500°C to 700°C and a sintering time of 5 to 15 hours to obtain a sintered precursor.

[0028] In step 130, the sintered precursor is subjected to a grinding process to obtain a powder material.

[0029] In the present invention, the grinding process employs a method of grinding multiple times and includes the following steps.

[0030] In step 131, the sintering precursor is subjected to primary crushing using a jaw crusher and a roll crusher in sequence to obtain a first powder material with a particle size of 10 μm to 20 μm.

[0031] In step 132, the first powder material is subjected to a ball milling process at a ball milling frequency of 200 Hz and a ball milling time of 2 hours to obtain a second powder material with a particle size of 4 μm to 15 μm.

[0032] In step 133, the second powder material is subjected to jet milling to obtain a powder material with a particle size of 2 μm to 4 μm.

[0033] In the present invention, a multi-step grinding process involves grinding a large-particle powder using a jaw crusher and a roll crusher. This powder is then further reduced in particle size by a ball mill, and finally, a jet mill is used to obtain a smaller, finer, and more uniformly sized powder. This multi-stage grinding process yields the finest and most uniform powder possible, increasing the reaction activity between the powder particles during secondary sintering.

[0034] In step 140, the powder material is sintered in an air atmosphere at 900°C to 1200°C for 5 to 10 hours to perform a crystallization treatment on the powder material and obtain a magnesium-based solid electrolyte.

[0035] Furthermore, after the crystallization treatment, preferably the product after the crystallization treatment is subjected to a grinding treatment, the same method as in step 130, and finally a powdered magnesium-based solid electrolyte is obtained.

[0036] The magnesium-based solid electrolyte prepared in this invention is pure phase magnesium titanium phosphate, and its chemical formula is Mg 0.5It is Ti2(PO4)3, a white powder with a particle size of 2μm-4μm. The XRD diffraction peaks of the magnesium-based solid electrolyte correspond one-to-one with the standard card number PDF#82-0297.

[0037] The magnesium-based solid electrolyte of the present invention can be applied as a positive electrode material to magnesium-ion batteries or solid-state batteries.

[0038] To better understand the technical proposals of the present invention, the specific processes and characteristics of preparing magnesium-based solid electrolytes by applying the methods described in the above-mentioned embodiments of the present invention will be explained below, with reference to several specific examples.

[0039] [Example 1] This example proposes the preparation of a pure-phase solid electrolyte of magnesium titanium phosphate.

[0040] In Step 1, 51g of magnesium oxide, 406g of titanium oxide, and 542g of phosphorus pentoxide are weighed out in a theoretical mixing ratio of Mg:Ti:P of 1:8:11, and poured into a mixer MG20 and mixed for 30 minutes to obtain a mixed precursor.

[0041] In step 2, the mixed precursor is pre-sintered. The sintering apparatus is a high-temperature box-type furnace RX3-50-14, the sintering temperature is set to 600°C, and the sintering time is set to 10 hours to obtain the sintered precursor.

[0042] In step 3, the sintered precursor obtained by sintering is subjected to a grinding process.

[0043] First, the sintered precursor is subjected to primary crushing using a jaw crusher DCI150X200 and a roll crusher DCJ230 in sequence to obtain a powder with a particle size Dv50 of 15.0 μm. Next, it is subjected to ball milling using a ball milling device XQM-20, with a ball milling frequency of 200 Hz and a ball milling time of 2 hours to obtain a powder with a particle size Dv50 of 8.2 μm. Finally, it is subjected to jet milling to obtain a uniform powder material with a particle size Dv50 of 3.2 μm.

[0044] XRD scanning tests were performed on the sintered precursor after grinding using an X-ray diffractometer DX-2700B. The results are shown in Figure 2. Approximately 90% of the diffraction peaks of the precursor material correspond to the standard peak of magnesium titanium phosphate, but crowded peaks are present. The presence of crowded peaks is due to the presence of other Mg / Ti / P / O elements in the product besides magnesium titanium phosphate. To obtain pure-phase magnesium titanium phosphate material, the material is further subjected to crystallization treatment, and secondary sintering is performed to remove non-crystallized products through sufficient reaction, thereby obtaining pure-phase magnesium titanium phosphate.

[0045] In step 4, the sintered precursor material after pulverization is sintered at 900°C for 5 hours in a high-temperature box-type furnace RX3-50-14 to crystallize the material, and then the temperature is lowered to obtain pure phase titanium magnesium phosphate, which is a white, hard, massive material.

[0046] Furthermore, the white, hard, lumpy material is further ground using the same method as in step 3 to obtain a white powder with a particle size Dv50 of approximately 2 μm. An XRD scanning test is performed on this powder. The XRD results obtained are shown in Figure 3, and each diffraction peak corresponds one-to-one with the standard card number PDF#82-0297. These results indicate that the preparation of a pure phase magnesium titanium phosphate material was successful through a multi-stage solid-phase sintering process.

[0047] [Example 2] This embodiment proposes the preparation of a pure-phase solid electrolyte of magnesium titanium phosphate. The apparatus used in each step is the same as in Example 1.

[0048] In Step 1, magnesium carbonate (a magnesium compound), butyl titanate (a titanium compound), and ammonium dihydrogen phosphate (a phosphorus compound) are weighed out in a theoretical mixing ratio of Mg:Ti:P of 1:8:11, poured into a mixer, and mixed for 30 minutes to obtain a mixed precursor.

[0049] In Step 2, the mixed precursor is pre-sintered at a sintering temperature of 700°C for a sintering time of 8 hours to obtain a sintered precursor.

[0050] In step 3, the sintered precursor obtained by sintering is subjected to a grinding process.

[0051] First, the sintered precursor is subjected to primary crushing using a jaw crusher and then a roll crusher in sequence to obtain a powder with a particle size Dv50 of 14.6 μm. Next, it is subjected to ball milling at a ball milling frequency of 200 Hz and a ball milling time of 2 hours to obtain a powder with a particle size Dv50 of 6.5 μm. Finally, it is subjected to jet milling to obtain a uniform powder material with a particle size Dv50 of 2.8 μm.

[0052] In step 4, the sintered precursor material after pulverization is sintered at 900°C for 5 hours to crystallize the material, and then the temperature is lowered to obtain pure phase magnesium titanium phosphate, which is a white, hard, massive material.

[0053] Furthermore, the white, hard, lumpy material was further ground using the same method as in step 3 to obtain a white powder with a particle size Dv50 of 2 μm. An XRD scanning test was performed on this powder, and the results indicated that the preparation of a pure phase magnesium titanium phosphate material was successful through a multi-stage solid-phase sintering process.

[0054] [Example 3] This embodiment proposes the preparation of a solid electrolyte containing magnesium titanium phosphate. The apparatus used in each step is the same as in Example 1.

[0055] In Step 1, magnesium chloride (a magnesium compound), titanium tetrachloride (a titanium compound), and phosphorous acid (a phosphorus compound) are measured out in a theoretical mixing ratio of Mg:Ti:P of 1:7:12, poured into a mixer, and mixed for 30 minutes to obtain a mixed precursor.

[0056] In Step 2, the mixed precursor is pre-sintered at a sintering temperature of 500°C for a sintering time of 10 hours to obtain a sintered precursor.

[0057] In step 3, the sintered precursor obtained by sintering is subjected to a grinding process.

[0058] First, the sintered precursor is subjected to primary crushing using a jaw crusher and then a roll crusher in sequence to obtain a powder with a particle size Dv50 of 16.1 μm. Next, a ball milling process is performed with a ball milling frequency of 200 Hz and a ball milling time of 2 hours to obtain a powder with a particle size Dv50 of 7.3 μm. Finally, a jet milling process is performed to obtain a uniform powder material with a particle size Dv50 of 2.5 μm.

[0059] In step 4, the sintered precursor material after pulverization is sintered at 900°C for 5 hours to crystallize the material, and then the temperature is lowered to obtain pure phase magnesium titanium phosphate, which is a white, hard, massive material.

[0060] Furthermore, the white, hard, lumpy material is further ground using the same method as in step 3 to obtain a white powder with a particle size Dv50 of approximately 2 μm.

[0061] In the method for preparing magnesium-based solid electrolytes according to the embodiments of the present invention, pure-phase magnesium titanium phosphate powder is prepared by combining multi-stage solid-phase low-temperature sintering with multiple grinding cycles. The multiple grinding cycles increase the reactive activity between powder particles, allowing secondary sintering to be performed at low temperatures. The preparation method is highly safe, the raw materials used are inexpensive, production costs are reduced, and it is advantageous for the mass production of magnesium titanium phosphate, a magnesium-based solid electrolyte. The present invention has significant importance for the sustainable development of future energy by increasing the application of magnesium-based materials to solid-state batteries, mitigating the problem of resource shortages caused by lithium raw materials.

[0062] The specific embodiments described above further illustrate the object, technical proposal and beneficial effects of the present invention. The above description is merely a description of specific embodiments of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are all included within the scope of protection of the present invention.

[0063] (Note) (Note 1) The process involves mixing magnesium compounds, titanium compounds, and phosphorus compounds in the required theoretical mixing ratio to obtain a mixed precursor. The mixed precursor is pre-sintered in an air atmosphere, with a sintering temperature of 500°C to 700°C and a sintering time of 5 to 15 hours to obtain a sintered precursor. The aforementioned sintered precursor is subjected to a grinding process to obtain a powder material. The aforementioned powder material is sintered in an air atmosphere at 900°C to 1200°C for 5 to 10 hours, and the powder material is subjected to a crystallization treatment to obtain a magnesium-based solid electrolyte. including, A method for preparing a magnesium-based solid electrolyte, characterized by the following features.

[0064] (Note 2) The mixing of the magnesium compound, titanium compound, and phosphorus compound in the required theoretical mixing ratio is specifically as follows: The magnesium compound, titanium compound, and phosphorus compound are mixed in a theoretical mixing ratio of Mg:Ti:P of 1:5 to 9:7 to 15. The preparation method described in Appendix 1, characterized by the features described herein.

[0065] (Note 3) The magnesium compound comprises one or more of magnesium oxide, magnesium carbonate, magnesium chloride, and magnesium hydroxide. The titanium compound comprises one or more of titanium oxide, titanium tetrachloride, and butyl titanate. The phosphorus compound comprises one or more of the following: solid phosphoric acid powder, diphosphorus pentoxide, ammonium dihydrogen phosphate, phosphorous acid, and hexametaphosphate. The preparation method described in Appendix 1, characterized by the features described herein.

[0066] (Note 4) The aforementioned grinding process is The sintered precursor is subjected to primary crushing in sequence using a jaw crusher and a roll crusher to obtain a first powder material with a particle size of 10 μm to 20 μm. The first powder material is subjected to a ball milling process, with a ball milling frequency of 200 Hz and a ball milling time of 2 hours, to obtain a second powder material with a particle size of 4 μm to 15 μm. The second powder material is subjected to jet milling to obtain a powder material with a particle size of 2 μm to 4 μm, including, The preparation method described in Appendix 1, characterized by the features described herein.

[0067] (Note 5) After performing a crystallization treatment on the aforementioned powder material, The method further includes performing the grinding treatment on the product after the crystallization treatment to obtain the magnesium-based solid electrolyte. The preparation method described in Appendix 4, characterized by the features described herein.

[0068] (Note 6) A magnesium-based solid electrolyte prepared by the method for preparing magnesium-based solid electrolytes described in any one of the above appendices 1 to 5.

[0069] (Note 7) The magnesium-based solid electrolyte described in Appendix 6 is characterized in that the magnesium-based solid electrolyte is a white powder material with a particle size of 2 μm to 4 μm.

[0070] (Note 8) The magnesium-based solid electrolyte is pure phase magnesium titanium phosphate, and its chemical formula is Mg 0.5 The magnesium-based solid electrolyte described in Appendix 6, characterized in that it is Ti2(PO4)3.

[0071] (Note 9) The magnesium-based solid electrolyte according to Appendix 6, characterized in that the XRD diffraction peak of the magnesium-based solid electrolyte corresponds one-to-one with the standard card number PDF#82-0297.

[0072] (Note 10) A battery characterized by containing a magnesium-based solid electrolyte prepared by the magnesium-based solid electrolyte preparation method described in any one of the above appendices 1 to 5.

Claims

1. A mixed precursor is obtained by mixing magnesium compounds, titanium compounds, and phosphorus compounds in a theoretical mixing ratio of Mg:Ti:P in a ratio of 1:5 to 9:7 to 15. The mixed precursor is pre-sintered in an air atmosphere, with a sintering temperature of 500°C to 700°C and a sintering time of 5 to 15 hours to obtain a sintered precursor. The aforementioned sintered precursor is subjected to a grinding process to obtain a powder material. The aforementioned powder material is sintered in an air atmosphere at 900°C to 1200°C for 5 to 10 hours, and the powder material is subjected to a crystallization treatment to obtain a magnesium-based solid electrolyte. Includes, The pulverization process includes: firstly pulverizing the sintered precursor using a jaw crusher and a roll crusher in sequence to obtain a first powder material with a particle size of 10 μm to 20 μm; ball milling the first powder material at a ball milling frequency of 200 Hz and a ball milling time of 2 hours to obtain a second powder material with a particle size of 4 μm to 15 μm; and jet milling the second powder material to obtain a powder material with a particle size of 2 μm to 4 μm. A method for preparing a magnesium-based solid electrolyte, characterized by the following features.

2. The magnesium compound comprises one or more of magnesium oxide, magnesium carbonate, magnesium chloride, and magnesium hydroxide. The titanium compound comprises one or more of titanium oxide, titanium tetrachloride, and butyl titanate. The phosphorus compound comprises one or more of the following: solid phosphoric acid powder, diphosphorus pentoxide, ammonium dihydrogen phosphate, phosphorous acid, and hexametaphosphate. The preparation method according to feature 1.

3. After performing a crystallization treatment on the aforementioned powder material, The method further includes performing the grinding treatment on the product after the crystallization treatment to obtain the magnesium-based solid electrolyte. The preparation method according to feature 1.

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