Fluorine ion solid electrolyte material and preparation method and application thereof

Abstract

The invention discloses a fluorine ion solid electrolyte material which is gamma-type NH4Sn2F5, and a preparation method of the fluorine ion solid electrolyte material comprises the following steps: S1, in an inert atmosphere, mixing SnF2 and NH4F, and grinding in a mortar to obtain a material before reaction; and S2, under the inert atmosphere condition, putting the pre-reaction material obtained in S1 and grinding balls into a ball mill, and carrying out ball milling to obtain the fluorine ion solid electrolyte material. The fluorine ion solid electrolyte provided by the invention has relatively high fluorine ion conductivity and can be used for an all-solid-state fluorine ion battery at room temperature. The preparation method has the advantages that the production cost is low, the production safety is high, the ionic conductivity can reach 10 <-3 > S.cm <-1 > at the room temperature, and an all-solid-state fluorine ion battery can be used at the room temperature.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluoride ion batteries, and in particular relates to a fluoride ion solid electrolyte material and a preparation method and application thereof. Background Art

[0002] With the development of electric vehicles and the energy storage industry, the energy density and safety requirements of batteries are becoming increasingly higher. The current energy density of lithium-ion batteries is gradually approaching its theoretical "ceiling", and the lithium resources on the earth are limited. Scientists have been trying to develop new and better battery technologies. Sodium-ion batteries, magnesium-ion batteries, zinc-ion batteries, etc. are all research hotspots in the energy field. In recent years, fluoride-ion batteries (FIBs), which are also "next-generation" electrochemical energy storage technologies, have become a hot topic due to their high energy density and high safety. The concept of fluoride-ion batteries was proposed as early as the 1970s. Due to the small molar mass of fluorine and the multi-electron transfer characteristics of polyvalent metal fluorides during the charge and discharge process, its theoretical volume energy density can reach 5000Wh L -1 , several times that of commercial lithium-ion batteries. In addition, fluorine ranks 13th in abundance in the earth's crust, which gives fluoride-ion batteries a clear advantage in terms of resource sustainability. In terms of safety, fluoride-ion batteries are fluoride ions (F) during the charging and discharging process. - ) replaces the shuttling of cations between the cathode and anode in traditional metal ion batteries, effectively preventing the formation of dendrites and the risk of short circuit caused by uneven deposition of metal ions when they shuttle between the anode and cathode. Therefore, fluoride ion batteries are known as "disruptive technology" internationally.

[0003] Most of the solid electrolytes used in current solid-state fluoride ion batteries can only work at high temperatures (150°C), which increases the complexity of the equipment, increases the cost, and reduces the safety and energy efficiency, which greatly limits the commercialization and promotion of this technology. How to achieve efficient conduction of fluoride ions at room temperature has become the primary problem in the development of fluoride ion batteries. Common fluorcerite-type solid electrolytes La 0.9 Ba 0.1 F 2.9 The highest ionic conductivity is 2.8×10 - 4 S cm -1 ; The typical fluorite-type solid electrolyte Ba 0.6 La 0.4 F 2.4 The ionic conductivity at the same temperature (160°C) is 1.9×10 -4 S cm -1A new solid-state fluoride electrolyte KSn2F5 shows higher ionic conductivity than traditional fluorcerite and fluorite fluorides, achieving 10 at 60 ° C. -4 S cm -1 However, the conductivity at room temperature still fails to meet the requirements of practical applications. Therefore, the development of fluoride ion solid electrolytes with high ionic conductivity at room temperature is of great significance for promoting the development of all-solid-state fluoride ion batteries and will greatly promote the further research and application of fluoride ion battery technology. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a fluoride ion solid electrolyte material and a preparation method thereof. The fluoride ion solid electrolyte material provided by the present invention has high ionic conductivity at room temperature and can be used in all-solid-state fluoride ion batteries at room temperature.

[0005] The present invention provides a fluoride ion solid electrolyte material, which is a γ-type NH4Sn2F5; the fluoride ion solid electrolyte material is a fluoride ion conductor.

[0006] The γ-type NH4Sn2F5 crystal belongs to the monoclinic system and the C2 / m space group;

[0007] Optionally, the unit cell parameters of the obtained γ-type NH4Sn2F5 crystal are: Z=6.

[0008] Optionally, the unit cell parameters of the obtained γ-type NH4Sn2F5 crystal are: Z=6.

[0009] Optionally, the lattice positions of each atom in the obtained NH4Sn2F5 crystal are: Sn1:8j, Sn2:4i, F1:4i, F2:8j, F3:8j, F4:4i, F5:8j, N1:4h, N2:2d.

[0010] A method for preparing the above-mentioned fluoride ion solid electrolyte material comprises the following steps:

[0011] S1. Under inert atmosphere, SnF2 and NH4F were mixed and ground in a mortar to obtain the reaction material;

[0012] S2. Under inert atmosphere, the pre-reaction material obtained in S1 and the grinding balls are placed in a ball mill for ball milling to obtain a fluoride ion solid electrolyte material.

[0013] Optionally, in the S1, the molar ratio of SnF2 to NH4F is in the range of 2.0:0.9 to 2.0:1.1.

[0014] Optionally, in S1, the grinding time is 2-10 minutes.

[0015] Optionally, in S2, the ratio of the pre-reaction material to the grinding balls is 10:1 to 30:1 by mass.

[0016] Optionally, in S2, the ball milling speed is 400-800 rpm;

[0017] Optionally, in S2, the ball milling time is 3-24 hours;

[0018] Optionally, in S2, the ball milling temperature is 20-60°C.

[0019] The present invention uses SnF2 and NH4F as raw materials and synthesizes high ionic conductivity fluoride ion solid electrolyte γ-type NH4Sn2F5 through mechanochemical method. 2+ The lone pair electron effect of NH4 + The larger radius weakens the F - The polarization of fluoride promotes the diffusion of fluoride ions, and the two work together to significantly improve the ionic conductivity. The room temperature ionic conductivity of the obtained γ-type NH4Sn2F5 crystal is 10 -4 -10 -2 S cm -1 .

[0020] The fluoride ion solid electrolyte of the present invention has high fluoride ion conductivity and can be used in an all-solid-state fluoride ion battery at room temperature.

[0021] In summary, the present invention has the following beneficial effects: 1. The preparation method of γ-type NH4Sn2F5 provided by the present invention has low production cost and high production safety. 2. The γ-type NH4Sn2F5 provided by the present invention can reach 10 -4 -10 -2 S cm -1 The ionic conductivity can be used in all-solid-state fluoride ion batteries at room temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The X-ray diffraction pattern of the γ-type NH4Sn2F5 powder obtained by the preparation method described in Example 1 of the present application;

[0023] Figure 2 The ionic conductivity test curve of γ-type NH4Sn2F5 obtained by the preparation method described in Example 1 of the present application;

[0024] Figure 3 The cycle performance test curve of the all-solid-state fluoride ion battery constructed by the preparation method described in Example 1 of the present application at room temperature;

[0025] Figure 4 The X-ray diffraction pattern of the γ-type NH4Sn2F5 powder obtained by the preparation method described in Example 2 of the present application;

[0026] Figure 5 The ionic conductivity test curve of γ-type NH4Sn2F5 obtained by the preparation method described in Example 2 of this application;

[0027] Figure 6 The X-ray diffraction pattern of the γ-type NH4Sn2F5 powder obtained by the preparation method described in Example 3 of the present application;

[0028] Figure 7 This is the ionic conductivity test curve of γ-type NH4Sn2F5 obtained by the preparation method described in Example 3 of the present application. DETAILED DESCRIPTION

[0029] The following is combined with Figure 1-7 The present invention will be further described in detail with the following embodiments:

[0030] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0031] The measurement method of ionic conductivity described in this application:

[0032] The electrolyte material was pressed into a disc with a diameter of 10 mm and a thickness of 1.5 mm under a pressure of 300 MPa. A layer of gold was sputtered on both sides of the disc as a blocking electrode using an ion sputtering instrument. The AC impedance was tested at room temperature to obtain the ionic conductivity of the electrolyte material.

[0033] The assembly method of the all-solid-state fluoride ion battery described in this application:

[0034] A mold battery was used to carry out constant current charge and discharge tests at room temperature to verify the feasibility of using the electrolyte for all-solid-state fluoride ion batteries at room temperature. The positive electrode was a mixture of BiF3, multi-walled carbon nanotubes and γ-type NH4Sn2F5, the intermediate electrolyte was γ-type NH4Sn2F5, the negative electrode was a mixture of Sn, multi-walled carbon nanotubes and γ-type NH4Sn2F5, and the assembly pressure was 300MPa.

[0035] Example 1

[0036] Weigh 10g of SnF2 and NH4F in a molar ratio of 2:1 and grind them thoroughly in an agate mortar for 5 minutes. Then weigh 100g of zirconia balls and place them in a zirconia ball mill. Then transfer the ground fluoride powder (10g) into the mill and seal the mill. All the above operations are carried out in an argon atmosphere glove box. Ball milling is carried out for 14 hours at a speed of 400rpm and a ball-to-material ratio of 10:1 to obtain the γ-type NH4Sn2F5 electrolyte powder material. Figure 1 , Figure 1 This is the X-ray diffraction pattern of the electrolyte powder prepared in Example 1 of the present invention.

[0037] After obtaining the electrolyte material, it was pressed into a disc with a diameter of 10 mm and a thickness of 1.5 mm under a pressure of 300 MPa. A layer of gold was sputtered on both sides of the disc as a blocking electrode using an ion sputtering instrument. The AC impedance was measured at room temperature to obtain the ionic conductivity of the electrolyte material. Figure 2 , Figure 2 This is the electrolyte ion conductivity test curve provided in Example 1 of the present invention. The calculation formula of conductivity (σ) is: Where: L is the thickness of the material (unit: cm), R b is the resistance value (unit: Ω), A is the cross-sectional area of the material (unit: cm 2 The results showed that at room temperature, the fluoride ion conductivity was 1.06×10 -3 S cm -1 The obtained electrolyte material was used to construct an all-solid-state fluoride ion battery, in which the positive electrode was a mixture of BiF3, multi-walled carbon nanotubes and γ-type NH4Sn2F5, the intermediate electrolyte was γ-type NH4Sn2F5, and the negative electrode was a mixture of Sn, multi-walled carbon nanotubes and γ-type NH4Sn2F5. A mold battery was used to conduct constant current charge and discharge tests at room temperature. Figure 3 , Figure 3 The cycle test curve of the all-solid-state fluoride ion battery constructed with the electrolyte provided in Example 1 of the present invention. The results show that at room temperature, the battery specific capacity can reach a maximum of 134.29 mAh g -1 , and the capacity retention rate was 63.8% after 200 cycles, indicating that the fluoride ion solid electrolyte provided in this embodiment can be used in all-solid-state fluoride ion batteries at room temperature.

[0038] Example 2

[0039] Weigh 10g of SnF2 and NH4F in a molar ratio of 2.0:0.9 and grind them thoroughly in an agate mortar for 2 minutes. Then weigh 200g of zirconia balls and place them in a zirconia ball mill. Then transfer the ground fluoride powder (10g) into the mill and seal the mill. All the above operations are carried out in an argon atmosphere glove box. Ball milling is carried out for 18 hours at a speed of 400 rpm and a ball-to-material ratio of 20:1 to obtain the γ-type NH4Sn2F5 electrolyte powder material. Figure 4 , Figure 4 This is the X-ray diffraction pattern of the electrolyte powder prepared in Example 2 of the present invention.

[0040] After obtaining the electrolyte material, it was pressed into a disc with a diameter of 10 mm and a thickness of 1.5 mm under a pressure of 300 MPa. A layer of gold was sputtered on both sides of the disc as a blocking electrode using an ion sputtering instrument. The AC impedance was measured at room temperature to obtain the ionic conductivity of the electrolyte material. Figure 5 , Figure 5 This is the electrolyte ion conductivity test curve provided in Example 2 of the present invention. The results show that at room temperature, its fluoride ion conductivity is 8.34×10 -4 S cm -1 This indicates that the fluoride ion solid electrolyte provided in this embodiment has good conductivity at room temperature.

[0041] Example 3

[0042] Weigh 10g of SnF2 and NH4F in a molar ratio of 2.0:1.1 and grind them thoroughly in an agate mortar for 10 minutes. Then weigh 300g of zirconia balls and place them in a zirconia ball mill. Then transfer the ground fluoride powder (10g) into the mill and seal the mill. All the above operations are carried out in an argon atmosphere glove box. Ball milling is carried out for 12 hours at a speed of 400 rpm and a ball-to-material ratio of 30:1 to obtain the γ-type NH4Sn2F5 electrolyte powder material. Figure 6 , Figure 6 This is the X-ray diffraction pattern of the electrolyte powder prepared in Example 1 of the present invention.

[0043] After obtaining the electrolyte material, it was pressed into a disc with a diameter of 10 mm and a thickness of 1.5 mm under a pressure of 300 MPa. A layer of gold was sputtered on both sides of the disc as a blocking electrode using an ion sputtering instrument. The AC impedance was measured at room temperature to obtain the ionic conductivity of the electrolyte material. Figure 7 , Figure 7 This is the electrolyte ion conductivity test curve provided in Example 1 of the present invention. The results show that at room temperature, its fluoride ion conductivity is 9.34×10 -4 S cm -1This indicates that the fluoride ion solid electrolyte provided in this embodiment has good conductivity at room temperature.

[0044] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as such modifications are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A fluoride ion solid electrolyte material, characterized in that: It is γ-type NH4Sn2F5; the fluoride ion solid electrolyte material is a fluoride ion conductor, and the γ-type NH4Sn2F5 crystal belongs to the monoclinic system and the C2 / m space group.

2. A fluoride ion solid electrolyte material according to claim 1, characterized in that: The unit cell parameters of the obtained γ-type NH4Sn2F5 crystal are: Z=6.

3. The fluoride ion solid electrolyte material according to claim 1, characterized in that: The unit cell parameters of the obtained γ-type NH4Sn2F5 crystal are: Z=6.

4. The fluoride ion solid electrolyte material according to claim 1, characterized in that: The lattice positions of each atom in the obtained NH4Sn2F5 crystal are: Sn1:8j, Sn2:4i, F1:4i, F2:8j, F3:8j, F4:4i, F5:8j, N1:4h, N2:2d.

5. A method for preparing the above-mentioned fluoride ion solid electrolyte material, characterized in that: The following steps are involved: S1. Under inert atmosphere, SnF2 and NH4F were mixed, the molar ratio of SnF2 and NH4F was in the range of 2.0:0.9-2.0:1.1, and ground in a mortar for 2-10 minutes to obtain the reaction material before; S2. Under inert atmosphere, the pre-reaction material obtained in S1 and the grinding balls are placed in a ball mill for ball milling to obtain a fluoride ion solid electrolyte material.

6. The method for preparing the fluoride ion solid electrolyte material according to claim 5, characterized in that: In S2, the ratio of the pre-reaction material to the grinding balls is 10:1 to 30:1 by mass.

7. The method for preparing the fluoride ion solid electrolyte material according to claim 5, characterized in that: In S2, the ball milling speed is 400-800 rpm, the ball milling time is 3-24 h, and the ball milling temperature is 20-60°C.

8. Use of the fluoride ion solid electrolyte material according to claims 1 to 4 in an all-solid-state fluoride ion battery.

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