Magnesium-based solid-state electrolyte, method for preparing the same, and battery

Abstract

The application relates to a magnesium-based solid-state electrolyte and a preparation method and a battery thereof, the preparation method comprising the following steps: mixing a magnesium source compound, a titanium source compound and a phosphorus source compound according to a required stoichiometric ratio to obtain a mixed precursor; pre-sintering the mixed precursor in an air atmosphere, wherein the sintering temperature is 500 DEG C-700 DEG C, and the sintering time is 5-15 hours, to obtain a sintered precursor; crushing the sintered precursor to obtain a powder material; and sintering the powder material in an air atmosphere at 900 DEG C-1200 DEG C for 5-10 hours, and performing crystallization treatment on the powder material to obtain the magnesium-based solid-state electrolyte.

Description

Technical Field

[0001] This invention relates to the field of new energy battery materials technology, and in particular to a magnesium-based solid electrolyte, its preparation method, and the battery thereof. Background Technology

[0002] The continuous deterioration of the global environment and the persistent shortage of energy supply are the two most serious problems that mankind must face in the 21st century. The development and application of new energy sources and renewable clean energy are now imperative. As a new type of green battery, lithium-ion secondary batteries have developed quite rapidly since their introduction in 1990.

[0003] With the tremendous success of lithium-ion batteries, magnesium, located diagonally opposite lithium on the periodic table, shares similar ionic radii and chemical properties. Furthermore, as one of the most abundant light metal elements on Earth, magnesium is widely used in various fields. Therefore, research on magnesium in solid-state electrolytes has attracted increasing attention from researchers. For example, Chinese patent 202010803639.9 discloses a rechargeable magnesium battery cathode material and its preparation method. The pyrite-type compound included in the rechargeable magnesium battery cathode material can simultaneously achieve redox valence changes of both cations and anions, improving the capacity and voltage of the cathode material.

[0004] Furthermore, magnesium is less reactive than lithium, making it easier to handle; it is pollution-free and safe. It is also inexpensive, costing only 1 / 24th the price of lithium. Therefore, research on magnesium-based materials in solid-state electrolytes can alleviate the economic problems caused by the shortage of lithium raw materials; moreover, research on magnesium-based solid-state battery materials is of great significance for the sustainable development of future energy.

[0005] However, based on currently available public reports, there are no publicly available methods for preparing titanium magnesium phosphate materials, especially those suitable for industrial mass production. Summary of the Invention

[0006] This invention provides a magnesium-based solid electrolyte, its preparation method, and a battery. The preparation method combines multi-stage solid-phase low-temperature sintering with multiple crushing processes to prepare pure-phase magnesium titanium phosphate powder. The multiple crushing processes enhance the reactivity between powder particles, enabling secondary sintering to be carried out at low temperatures. The preparation method is highly safe and facilitates the mass production of magnesium titanium phosphate solid electrolyte.

[0007] In a first aspect, embodiments of the present invention provide a method for preparing a magnesium-based solid electrolyte, the method comprising:

[0008] Magnesium source compound, titanium source compound and phosphorus source compound are mixed in the required stoichiometric ratio to obtain a mixed precursor;

[0009] The mixed precursor was pre-fired in air at a sintering temperature of 500℃-700℃ for 5-15 hours to obtain a sintered precursor.

[0010] The sintering precursor is crushed to obtain a powder material.

[0011] The powder material is sintered in air at 900℃-1200℃ for 5-10 hours to crystallize the powder material and obtain the magnesium-based solid electrolyte.

[0012] Preferably, the mixing of the magnesium source compound, titanium source compound, and phosphorus source compound in the required stoichiometric ratio specifically involves:

[0013] Magnesium source compounds, titanium source compounds, and phosphorus source compounds are mixed in a stoichiometric ratio of Mg:Ti:P of 1:5-9:7-15.

[0014] Preferably, the magnesium source compound includes one or more of magnesium oxide, magnesium carbonate, magnesium chloride, and magnesium hydroxide;

[0015] The titanium source compound includes one or more of titanium oxide, titanium tetrachloride, and tetrabutyl titanate.

[0016] The phosphorus source compound includes one or more of the following: solid phosphoric acid powder, phosphorus pentoxide, ammonium dihydrogen phosphate, phosphorous acid, and hexametaphosphate.

[0017] Preferably, the crushing process includes:

[0018] The sintering precursor is subjected to primary crushing by a jaw crusher and a double roll crusher in sequence to obtain a first powder material with a particle size of 10μm-20μm.

[0019] The first powder material was ball-milled at a frequency of 200 Hz for 2 hours to obtain a second powder material with a particle size of 4 μm-15 μm.

[0020] The second powder material was subjected to air jet milling to obtain a powder material with a particle size of 2μm-4μm.

[0021] More preferably, after crystallizing the powder material, the method further includes:

[0022] The product after crystallization is subjected to the crushing process to obtain the magnesium-based solid electrolyte.

[0023] Secondly, embodiments of the present invention provide a magnesium-based solid electrolyte prepared by the method described in the first aspect.

[0024] Preferably, the magnesium-based solid electrolyte is a white powder with a particle size of 2μm-4μm.

[0025] Preferably, the magnesium-based solid electrolyte is pure-phase magnesium titanium phosphate, with the chemical formula Mg. 0.5 Ti2(PO4)3.

[0026] Preferably, the XRD diffraction peaks of the magnesium-based solid electrolyte correspond one-to-one with the standard card number PDF#82-0297.

[0027] Thirdly, embodiments of the present invention provide a battery comprising a magnesium-based solid electrolyte prepared by the method described in the first aspect.

[0028] The method for preparing magnesium-based solid electrolyte proposed in this invention combines multi-stage low-temperature solid-phase sintering with multiple crushing processes to prepare pure-phase magnesium titanium phosphate powder. The multiple crushing processes enhance the reactivity between powder particles, enabling secondary sintering to be carried out at low temperatures. The preparation method is highly safe and conducive to the mass production of magnesium-based solid electrolyte magnesium titanium phosphate. Attached Figure Description

[0029] The technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples.

[0030] Figure 1 This is a flowchart illustrating the preparation method of magnesium-based solid electrolyte according to an embodiment of the present invention;

[0031] Figure 2 This is the X-ray diffraction (XRD) pattern of the sintered precursor after crushing in Example 1 of the present invention;

[0032] Figure 3 This is the X-ray diffraction (XRD) pattern of the magnesium titanium phosphate prepared in Example 1 of this invention. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should be understood that these embodiments are only for more detailed description and should not be construed as limiting the present invention in any way, that is, not intended to limit the scope of protection of the present invention.

[0034] This invention proposes a method for preparing magnesium-based solid electrolytes that can be industrially applied, filling the gap in the industrial preparation of titanium magnesium phosphate solid electrolyte materials.

[0035] The main preparation steps of this invention are as follows: Figure 1 As shown, it includes:

[0036] Step 110: Mix the magnesium source compound, titanium source compound and phosphorus source compound in the required stoichiometric ratio to obtain a mixed precursor;

[0037] Magnesium source compounds include one or more of magnesium oxide, magnesium carbonate, magnesium chloride, and magnesium hydroxide; titanium source compounds include one or more of titanium oxide, titanium tetrachloride, and tetrabutyl titanate; phosphorus source compounds include one or more of solid phosphoric acid powder, phosphorus pentoxide, ammonium dihydrogen phosphate, phosphorous acid, and hexametaphosphate.

[0038] Magnesium source compounds, titanium source compounds, and phosphorus source compounds are mixed in a stoichiometric ratio of Mg:Ti:P of 1:5-9:7-15.

[0039] Step 120: The mixed precursor is pre-fired in air atmosphere at a sintering temperature of 500℃-700℃ for 5-15 hours to obtain the sintered precursor.

[0040] Step 130: The sintering precursor is crushed to obtain powder material;

[0041] In this invention, the crushing process employs a multi-stage crushing method, including:

[0042] Step 131: The sintering precursor is subjected to primary crushing by a jaw crusher and a double roll crusher in sequence to obtain the first powder material with a particle size of 10μm-20μm.

[0043] Step 132: The first powder material is ball-milled at a frequency of 200 Hz for 2 hours to obtain a second powder material with a particle size of 4 μm-15 μm.

[0044] Step 133: The second powder material is subjected to air jet milling to obtain powder material with a particle size of 2μm-4μm.

[0045] In the multi-stage crushing process of this invention, the large-sized powder obtained from jaw crusher and roller crusher is further reduced by ball milling; finally, even smaller, finer, and more uniform-sized powder is obtained by air jet milling. This multi-stage crushing process yields the finest and most uniform powder possible, thereby increasing the reactivity between particles in the secondary sintering powder.

[0046] Step 140: Sinter the powder material at 900℃-1200℃ in air for 5-10 hours to crystallize the powder material and obtain a magnesium-based solid electrolyte.

[0047] Furthermore, after crystallization, preferably, the crystallized product is further crushed, using the same method as step 130, to finally obtain a powdered magnesium-based solid electrolyte.

[0048] The magnesium-based solid electrolyte prepared by this invention is a pure phase of magnesium titanium phosphate, with the chemical formula Mg. 0.5 Ti2(PO4)3 is 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.

[0049] The magnesium-based solid electrolyte of the present invention can be used as a positive electrode material in magnesium-ion batteries or solid-state batteries.

[0050] To better understand the technical solutions provided by the present invention, the following specific examples illustrate the specific process and characteristics of preparing magnesium-based solid electrolytes using the methods provided in the above embodiments of the present invention.

[0051] Example 1

[0052] This embodiment proposes the preparation of a pure-phase magnesium titanium phosphate solid electrolyte.

[0053] Step 1: Weigh 51g of magnesium oxide, 406g of titanium oxide, and 542g of phosphorus pentoxide according to the stoichiometric ratio of Mg:Ti:P of 1:8:11. Pour them into a mixer and mix for 30 minutes to obtain a mixed precursor.

[0054] Step 2: Pre-sinter the mixed precursor at a sintering temperature of 600℃ for 10 hours to obtain the sintered precursor.

[0055] Step 3: Crush the sintered precursor obtained by sintering.

[0056] First, the sintering precursor is subjected to primary crushing by a jaw crusher and a double roll crusher to obtain powder with a particle size Dv50 of 15.0 μm. Then, it is ball-milled at a frequency of 200 Hz for 2 hours to obtain powder with a particle size Dv50 of 8.2 μm. Finally, it is subjected to air jet milling to obtain a uniform powder material with a particle size Dv50 of 3.2 μm.

[0057] The sintered precursor after crushing was subjected to XRD scanning tests, and the results are as follows: Figure 2 As shown, approximately 90% of the diffraction peaks of this precursor material correspond to the standard peaks of magnesium titanium phosphate, but impurity peaks still exist. The presence of these impurity peaks is due to the presence of other Mg / Ti / P / O elemental compositions besides magnesium titanium phosphate in the product. To obtain a pure-phase magnesium titanium phosphate material, the material is further crystallized, and amorphous products are eliminated through a secondary sintering process, resulting in a pure-phase magnesium titanium phosphate.

[0058] Step 4: Sinter the crushed sintering precursor material at 900℃ for 5 hours to crystallize the material. After cooling, a white, hard, blocky material is obtained, which is pure phase titanium magnesium phosphate.

[0059] Furthermore, the white, hard, lumpy material was crushed using the same method as in step 3 to obtain a white powder with a particle size Dv50 of approximately 2 μm. The powder was then subjected to XRD analysis. The XRD results are shown below. Figure 3 As shown, all diffraction peaks correspond one-to-one with the standard card PDF#82-0297. This result demonstrates that pure-phase magnesium titanium phosphate material was successfully prepared through multi-stage solid-state sintering.

[0060] Example 2

[0061] This embodiment proposes the preparation of a pure-phase magnesium titanium phosphate solid electrolyte.

[0062] Step 1: Weigh magnesium carbonate, tetrabutyl titanate, and ammonium dihydrogen phosphate according to the stoichiometric ratio of Mg:Ti:P of 1:8:11. Pour them into a mixer and mix for 30 minutes to obtain a mixed precursor.

[0063] Step 2: The mixed precursor is pre-sintered at a temperature of 700℃ for 8 hours to obtain the sintered precursor.

[0064] Step 3: Crush the sintered precursor obtained by sintering.

[0065] First, the sintering precursor is subjected to primary crushing by a jaw crusher and a double roll crusher to obtain powder with a particle size of 14.6 μm (Dv50). Then, it is ball-milled at a frequency of 200 Hz for 2 hours to obtain powder with a particle size of 6.5 μm (Dv50). Finally, it is subjected to air jet milling to obtain a uniform powder material with a particle size of 2.8 μm (Dv50).

[0066] Step 4: Sinter the crushed sintering precursor material at 900℃ for 5 hours to crystallize the material. After cooling, a white, hard, blocky material is obtained, which is pure phase titanium magnesium phosphate.

[0067] Furthermore, the white, hard, blocky material was crushed using the same method as in step 3 to obtain white powder with a particle size Dv50 of 2 μm. XRD analysis of this powder showed that pure-phase magnesium titanium phosphate material was successfully prepared through multi-stage solid-state sintering.

[0068] Example 3

[0069] This embodiment presents a method for preparing a magnesium titanium phosphate solid electrolyte.

[0070] Step 1: Weigh magnesium chloride, titanium tetrachloride, and phosphoric acid according to a stoichiometric ratio of Mg:Ti:P of 1:7:12. Pour them into a mixer and mix for 30 minutes to obtain a mixed precursor.

[0071] Step 2: Pre-sinter the mixed precursor at a sintering temperature of 500℃ for 10 hours to obtain the sintered precursor.

[0072] Step 3: Crush the sintered precursor obtained by sintering.

[0073] First, the sintering precursor is subjected to primary crushing by a jaw crusher and a double roll crusher to obtain powder with a particle size Dv50 of 16.1 μm. Then, it is ball-milled at a frequency of 200 Hz for 2 hours to obtain powder with a particle size Dv50 of 7.3 μm. Finally, it is subjected to air jet milling to obtain uniform powder material with a particle size Dv50 of 2.5 μm.

[0074] Step 4: Sinter the crushed sintering precursor material at 900℃ for 5 hours to crystallize the material. After cooling, a white, hard, blocky material is obtained, which is pure phase titanium magnesium phosphate.

[0075] Furthermore, the white, hard, lumpy material is crushed using the same method as in step 3 to obtain white powder with a particle size Dv50 of approximately 2 μm.

[0076] The method for preparing magnesium-based solid electrolytes proposed in this invention combines multi-stage low-temperature solid-phase sintering with multiple crushing processes to prepare pure-phase magnesium titanium phosphate powder. Multiple crushing processes enhance the reactivity between powder particles, enabling secondary sintering to be carried out at low temperatures. This method offers high safety, uses inexpensive raw materials, reduces production costs, and facilitates the mass production of magnesium titanium phosphate solid electrolytes. This invention improves the application of magnesium-based materials in solid-state batteries and alleviates the resource shortage problem caused by lithium raw materials, which is of great significance to the sustainable development of future energy.

[0077] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment 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 should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a magnesium-based solid electrolyte, characterized in that, The preparation method is a solid-state method, including: A magnesium source compound, a titanium source compound, and a phosphorus source compound are dry-mixed according to the required stoichiometric ratio to obtain a mixed precursor; the titanium source compound includes one or more of titanium oxide, titanium tetrachloride, and tetrabutyl titanate. The mixed precursor was pre-fired in air at a sintering temperature of 500℃-700℃ for 5-15 hours to obtain a sintered precursor. The sintering precursor is subjected to multi-stage crushing, which includes primary crushing, ball milling and air jet milling in sequence, to obtain a powder material with high reactivity and a particle size of 2μm-4μm. The powder material is sintered in air at 900℃-1200℃ for 5-10 hours to crystallize the powder material, so that the powder material activated by the multi-stage crushing treatment can fully react, thereby eliminating amorphous products and obtaining the pure phase magnesium-based solid electrolyte.

2. The preparation method according to claim 1, characterized in that, The specific steps of mixing the magnesium source compound, titanium source compound, and phosphorus source compound according to the required stoichiometric ratio are as follows: Magnesium source compounds, titanium source compounds, and phosphorus source compounds are mixed in a stoichiometric ratio of Mg:Ti:P of 1:5-9:7-15.

3. The preparation method according to claim 1, characterized in that, The magnesium source compound includes one or more of magnesium oxide, magnesium carbonate, magnesium chloride, and magnesium hydroxide. The phosphorus source compound includes one or more of the following: solid phosphoric acid powder, phosphorus pentoxide, ammonium dihydrogen phosphate, phosphorous acid, and hexametaphosphate.

4. The preparation method according to claim 1, characterized in that, The multi-stage crushing process includes: The sintering precursor is subjected to primary crushing by a jaw crusher and a double roll crusher in sequence to obtain a first powder material with a particle size of 10μm-20μm. The first powder material was ball-milled at a frequency of 200 Hz for 2 hours to obtain a second powder material with a particle size of 4 μm - 15 μm. The second powder material was subjected to air jet milling to obtain a powder material with a particle size of 2μm-4μm.

5. The preparation method according to claim 4, characterized in that, After crystallizing the powder material, the method further includes: The product after crystallization is subjected to the multi-stage crushing process to obtain the magnesium-based solid electrolyte.

6. A magnesium-based solid electrolyte prepared by a method according to any one of claims 1-5.

7. The magnesium-based solid electrolyte according to claim 6, characterized in that, The magnesium-based solid electrolyte is a white powder with a particle size of 2μm-4μm.

8. The magnesium-based solid electrolyte according to claim 6, characterized in that, The magnesium-based solid-state electrolyte is a pure-phase titanium magnesium phosphate with a chemical formula of Mg 0.5 Ti2(PO4)3.

9. The magnesium-based solid electrolyte according to claim 6, characterized in that, The XRD diffraction peaks of the magnesium-based solid electrolyte correspond one-to-one with the standard card number PDF#82-0297.

10. A battery, characterized in that, The battery comprises a magnesium-based solid electrolyte prepared by the method described in any one of claims 1-5.

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