Solid-state electrolyte and method for preparing the same
By manually mixing SbF3 and KF and controlling the heat treatment parameters, a β-KSbF4 solid electrolyte with high ionic conductivity was prepared, which solved the problem of insufficient conductivity in traditional methods and achieved higher ionic conductivity and safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIANGTAN UNIV
- Filing Date
- 2024-01-19
- Publication Date
- 2026-07-28
AI Technical Summary
Existing technologies struggle to efficiently and safely prepare β-KSbF4 solid electrolytes with high ionic conductivity. Traditional methods utilize highly corrosive hydrofluoric acid, and their conductivity needs improvement.
By manually mixing SbF3 and KF, and controlling the temperature and heating rate through heat treatment, some of the SbF3 is volatilized, forming crystal defects and improving electrical conductivity.
The prepared β-KSbF4 solid electrolyte has a room temperature ionic conductivity of 1.05×10-4S·cm-1, which is 4 times higher than that of the traditional method, and has excellent ion conduction performance.
Smart Images
Figure CN117855592B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fluoride-ion battery materials, and more particularly to a solid electrolyte and its preparation method. Background Technology
[0002] With the rapid development of electronic devices and electric vehicles, the requirements for electrochemical energy storage systems in batteries are becoming increasingly stringent. Compared to commercial lithium-ion batteries, all-solid-state fluorine-ion batteries (FIBs) exhibit greater application potential due to their ultra-high theoretical volumetric energy density, ideal safety, and resource advantages. However, the development of all-solid-state FIBs is limited by the development of solid electrolytes with high ionic conductivity and wide electrochemical windows. Typical SnF2-based electrolytes and BaSnF4 electrolytes exhibit conductivity higher than 10 at room temperature. -4 S·cm -1 While possessing high ionic conductivity, the narrow electrochemical window (~0.5V) limits the discharge plateau of assembled solid-state batteries to around 0.1V, severely restricting their further development. Air-stabilized β-KSbF4 is considered a promising fluoride-ion solid electrolyte, with room-temperature ionic conductivity reaching 10⁻⁶. - 4 S·cm -1 β-KSbF4 exhibits excellent air stability and has therefore attracted increasing attention. Currently, the main method for preparing β-KSbF4 involves synthesizing α-KSbF4 via a liquid-phase method, followed by a series of annealing processes. However, the liquid-phase method requires the use of large amounts of highly corrosive hydrofluoric acid, posing significant challenges to production equipment and the environment. Furthermore, the conductivity of β-KSbF4 prepared using traditional methods still needs further improvement compared to the increasingly demanding performance requirements of all-solid-state fluoride-ion batteries.
[0003] Therefore, how to efficiently and safely prepare solid electrolytes with higher ionic conductivity has become a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0004] The purpose of this invention is to provide a solid electrolyte and its preparation method. The solid electrolyte preparation method provided by this invention can efficiently and safely prepare β-KSbF4 solid electrolytes with higher ionic conductivity.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0006] This invention provides a method for preparing a solid electrolyte, comprising the following steps:
[0007] (1) Manually mix SbF3 and KF to obtain a mixture;
[0008] (2) The mixture obtained in step (1) is subjected to heat treatment to obtain a solid electrolyte;
[0009] The heat treatment temperature in step (2) is 200-300℃, and the heat treatment time is 10-14h;
[0010] The heating rate to the heat treatment temperature is 1–10 °C / min.
[0011] Preferably, the molar ratio of SbF3 to KF in step (1) is 1:(0.9 to 1.1).
[0012] Preferably, the manual mixing time in step (1) is 30 to 60 minutes.
[0013] Preferably, the manual mixing process in step (1) is carried out under inert conditions.
[0014] Preferably, the water content and oxygen content in the inert conditions are independently less than 0.1 ppm.
[0015] Preferably, the heat treatment temperature in step (2) is 220-280°C and the heat treatment time is 11-13 hours.
[0016] Preferably, the heating rate to the heat treatment temperature is 2–8 °C / min.
[0017] Preferably, the heat treatment is cooled to room temperature along with the furnace after the heat treatment and heat preservation are completed.
[0018] Preferably, the cooling rate of the furnace to room temperature is 1–6 °C / min.
[0019] The present invention provides a solid electrolyte prepared by the preparation method described above, wherein the solid electrolyte is β-KSbF4.
[0020] This invention provides a method for preparing a solid electrolyte, comprising the following steps: (1) manually mixing SbF3 and KF to obtain a mixture; (2) heat-treating the mixture obtained in step (1) to obtain a solid electrolyte; the heat treatment temperature in step (2) is 200–300 °C, the heat treatment time is 10–14 h, and the heating rate to the heat treatment temperature is 1–10 °C / min. This invention uses manual mixing of SbF3 and KF, followed by heat treatment of the mixture, with a limited heat treatment temperature and heating rate, to allow partial volatilization of SbF3 during the heat treatment process. This results in a solid electrolyte (β-KSbF4) with more crystal defects than β-KSbF4 prepared by conventional methods, thereby improving the ionic conductivity of the solid electrolyte. Example results show that the solid electrolyte prepared by the method provided by this invention has a maximum conductivity of 1.05 × 10⁻⁶. -4 S·cm -1 Its room temperature ionic conductivity is four times that of solid electrolytes prepared by traditional wet methods, demonstrating excellent ion conduction performance. Attached Figure Description
[0021] Figure 1 The X-ray diffraction pattern of the solid electrolyte (β-KSbF4) prepared in Example 1 of this invention;
[0022] Figure 2 The graph shows the ionic conductivity test curve of the solid electrolyte (β-KSbF4) prepared in Example 1 of the present invention.
[0023] Figure 3 The X-ray diffraction pattern of the solid electrolyte (β-KSbF4) prepared in Example 2 of this invention;
[0024] Figure 4 This is a graph showing the ionic conductivity test curve of the solid electrolyte (β-KSbF4) prepared in Example 2 of the present invention.
[0025] Figure 5 The X-ray diffraction pattern of the solid electrolyte (β-KSbF4) prepared in Example 3 of this invention;
[0026] Figure 6 The graph shows the ionic conductivity test curve of the solid electrolyte (β-KSbF4) prepared in Example 3 of the present invention.
[0027] Figure 7 The graph shows the ionic conductivity test curve of the solid electrolyte (β-KSbF4) prepared in Comparative Example 1 of this invention.
[0028] Figure 8This is a graph showing the ionic conductivity of the solid electrolyte (β-KSbF4) prepared in Comparative Example 2 of this invention. Detailed Implementation
[0029] This invention provides a method for preparing a solid electrolyte, comprising the following steps:
[0030] (1) Manually mix SbF3 and KF to obtain a mixture;
[0031] (2) The mixture obtained in step (1) is subjected to heat treatment to obtain a solid electrolyte.
[0032] In this invention, SbF3 and KF are manually mixed to obtain a mixture.
[0033] In this invention, the source of SbF3 and KF is not particularly limited, and commercially available SbF3 and KF can be used.
[0034] In this invention, the manual mixing is preferably manual grinding; the manual grinding is preferably carried out in a mortar. This invention does not have a particular limitation on the type of mortar; any mortar commonly used by those skilled in the art can be used for grinding.
[0035] In this invention, the manual mixing process is preferably carried out under inert conditions; the water content and oxygen content under these inert conditions are preferably independently less than 0.1 ppm. In a specific embodiment of this invention, the gas used for the inert conditions is preferably argon. Limiting the inert conditions to the above range ensures that oxidation of the raw materials and the introduction of impurities are avoided during the manual mixing process.
[0036] In this invention, the molar ratio of SbF3 to KF is preferably 1:(0.9 to 1.1), more preferably 1:(0.95 to 1.05), and even more preferably 1:1.0. Limiting the molar ratio of SbF3 to KF to the above range ensures that the resulting solid electrolyte is β-KSbF4.
[0037] In this invention, the manual mixing time is preferably 30-60 min, more preferably 35-55 min, and even more preferably 40-50 min. Setting the manual mixing time within the above range ensures thorough mixing of the ball materials.
[0038] After obtaining the mixture, the present invention performs heat treatment on the mixture to obtain a solid electrolyte.
[0039] In this invention, the heat treatment temperature is 200–300°C, preferably 220–280°C, more preferably 240–260°C, and even more preferably 250°C; the heat treatment time is 10–14 h, preferably 11–13 h, more preferably 11.5–12.5 h, and even more preferably 12 h. Limiting the heat treatment temperature and time to the above ranges ensures that the mixture undergoes a solid-phase reaction to obtain a solid electrolyte.
[0040] In this invention, the heating rate to the heat treatment temperature is 1–10 °C / min, preferably 2–8 °C / min, and more preferably 5 °C / min. By setting the heating rate to the heat treatment temperature within the above range, this invention avoids the formation of voids in the electrolyte due to an excessively rapid heating rate during heat treatment, thereby preventing a decrease in electrolyte density.
[0041] In this invention, the heat treatment is preferably carried out in a muffle furnace, a tube furnace, or a high-temperature oven.
[0042] In this invention, the furnace is preferably cooled to room temperature after the heat treatment and heat preservation are completed.
[0043] In this invention, the cooling rate for furnace cooling to room temperature is preferably 1–6 °C / min, more preferably 2–5 °C / min, and even more preferably 3 °C / min. Setting the cooling rate within the above range allows for the formation of crystals of suitable size, thereby ensuring the ionic conductivity of the electrolyte.
[0044] This invention employs manual mixing of SbF3 and KF, followed by heat treatment of the mixture with controlled temperature and heating rate. This process causes partial volatilization of SbF3, resulting in a solid electrolyte with more crystal defects compared to β-KSbF4 prepared by conventional methods, thereby improving the ionic conductivity of the solid electrolyte.
[0045] The present invention provides a solid electrolyte prepared by the preparation method described above, wherein the chemical composition of the solid electrolyte is β-KSbF4.
[0046] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0047] Example 1
[0048] A method for preparing a solid electrolyte comprises the following steps:
[0049] (1) Weigh 5g of KF and SbF3 in a molar ratio of 1:1 and grind them thoroughly in an agate mortar for 40 minutes to obtain a mixture;
[0050] (2) The mixture obtained in step (1) is heated to 250°C in a tube furnace at a heating rate of 5°C / min for 12 hours, and then cooled to room temperature with the furnace at a cooling rate of 5°C / min to obtain solid electrolyte (β-KSbF4).
[0051] The solid electrolyte (β-KSbF4) obtained in Example 1 was pressed into a disc under a pressure of 5t. The disc was polished flat, and a layer of gold was sputtered on both sides of the disc as a blocking electrode using an ion sputtering instrument. The ionic conductivity of the electrolyte material was obtained by testing the AC impedance at room temperature.
[0052] Figure 1 The X-ray diffraction pattern of the solid electrolyte (β-KSbF4) prepared in Example 1 is shown below. Figure 1 It can be seen that β-KSbF4 has good crystallinity, and each diffraction peak corresponds perfectly with the standard card.
[0053] Figure 2 The graph shows the ionic conductivity of the solid electrolyte (β-KSbF4) prepared in Example 1. Figure 2 It can be seen that, at room temperature (30℃), its ionic conductivity is 1.05 × 10⁻⁶. -4 S·cm -1 This indicates that the fluoride ion solid electrolyte provided in this embodiment has good ion conduction performance at room temperature.
[0054] Example 2
[0055] The only difference between Example 2 and Example 1 is that the heat treatment temperature is 270°C, otherwise it is the same as Example 1.
[0056] The solid electrolyte (β-KSbF4) obtained in Example 2 was pressed into a disc under a pressure of 5t. The disc was polished flat, and a layer of gold was sputtered on both sides of the disc as a blocking electrode using an ion sputtering instrument. The ionic conductivity of the electrolyte material was obtained by testing the AC impedance at room temperature.
[0057] Figure 3 The X-ray diffraction pattern of the solid electrolyte (β-KSbF4) prepared in Example 2 is shown below. Figure 3 It can be seen that β-KSbF4 has good crystallinity, and each diffraction peak corresponds perfectly with the standard card.
[0058] Figure 4The graph shows the ionic conductivity of the solid electrolyte (β-KSbF4) prepared in Example 2. Figure 4 It can be seen that, under room temperature conditions (30℃), its ionic conductivity is 8.3 × 10⁻⁶. -5 S·cm -1 This indicates that the fluoride ion solid electrolyte provided in this embodiment has good ion conduction performance at room temperature.
[0059] Example 3
[0060] The only difference between Example 3 and Example 1 is that the heat treatment temperature is 230°C, otherwise it is the same as Example 1.
[0061] The solid electrolyte (β-KSbF4) obtained in Example 3 was pressed into a disc under a pressure of 5t. The disc was polished flat, and a layer of gold was sputtered on both sides of the disc as a blocking electrode using an ion sputtering instrument. The ionic conductivity of the electrolyte material was obtained by testing the AC impedance at room temperature.
[0062] Figure 5 The X-ray diffraction pattern of the solid electrolyte (β-KSbF4) prepared in Example 3 is shown below. Figure 5 It can be seen that β-KSbF4 has good crystallinity, and each diffraction peak corresponds perfectly with the standard card.
[0063] Figure 6 The graph shows the ionic conductivity of the solid electrolyte (β-KSbF4) prepared in Example 3. Figure 6 It can be seen that, under room temperature conditions (30℃), its ionic conductivity is 7.6 × 10⁻⁶. -5 S·cm -1 This indicates that the fluoride ion solid electrolyte provided in this embodiment has good ion conduction performance at room temperature.
[0064] Comparative Example 1
[0065] K2CO3, Sb2O3 and HF were dissolved in ultrapure water in a molar ratio of 1:1:8 and magnetically stirred for 6 h. The aqueous solution was slowly evaporated at room temperature to obtain the precursor (α-KSbF4). The α-KSbF4 powder obtained after evaporation was placed in a crucible and calcined at 250 °C for 12 h to obtain the solid electrolyte (β-KSbF4).
[0066] The solid electrolyte (β-KSbF4) obtained in Comparative Example 1 was pressed into a disc under a pressure of 5t. The disc was polished flat, and a layer of gold was sputtered on both sides of the disc as a blocking electrode using an ion sputtering instrument. The ionic conductivity of the electrolyte material was obtained by measuring the AC impedance at room temperature.
[0067] Figure 7The graph shows the ionic conductivity of the solid electrolyte (β-KSbF4) prepared in Comparative Example 1. Figure 7 It can be seen that, at room temperature (30℃), its ionic conductivity is 1.61 × 10⁻⁶. -5 S·cm -1 This indicates that the solid electrolyte provided in Comparative Example 1 has ion conduction performance at room temperature that meets the level reported in general literature.
[0068] Comparative Example 2
[0069] A method for preparing a solid electrolyte comprises the following steps:
[0070] (1) Weigh 5g of KF and SbF3 in a molar ratio of 1:1 and ball mill them in a planetary ball mill at 550rpm for 12 hours to obtain the precursor.
[0071] (2) The precursor obtained in step (1) is heated to 250°C in a tube furnace at a heating rate of 5°C / min for 12 hours, and then cooled to room temperature in the furnace at a cooling rate of 5°C / min to obtain solid electrolyte (β-KSbF4).
[0072] The solid electrolyte (β-KSbF4) obtained in Comparative Example 2 was pressed into a disc under a pressure of 5t. The disc was polished flat, and a layer of gold was sputtered on both sides of the disc as a blocking electrode using an ion sputtering instrument. The ionic conductivity of the electrolyte material was obtained by measuring the AC impedance at room temperature.
[0073] Figure 8 The graph shows the ionic conductivity of the solid electrolyte (β-KSbF4) prepared in Comparative Example 2. Figure 8 It can be seen that, at room temperature (30℃), its ionic conductivity is 3.61 × 10⁻⁶. -5 S·cm -1 .
[0074] The solid electrolytes (β-KSbF4) synthesized in Examples 1-3 via a solid-state method combined with high-temperature annealing all maintained a high conductivity at room temperature. Compared to the solid electrolyte (β-KSbF4) prepared by the conventional wet method in Comparative Example 1, the β-KSbF4 prepared during sintering is defect-rich due to the volatilization of SbF3, which improves the room-temperature ionic conductivity of the solid electrolyte (β-KSbF4), with a maximum of 1.05 × 10⁻⁶. -4 S·cm -1 Its room temperature ionic conductivity is 4 times that of solid electrolytes (β-KSbF4) prepared by traditional wet methods.
[0075] Comparative Example 2 uses a mechanochemical synthesis (ball milling) precursor. Compared with Examples 1-3, ball milling in the mechanochemical synthesis process is a closed environment and does not create a large number of defects. The solid-state method is much simpler in terms of process than the previous ball milling + annealing. In addition, during solid-state sintering, because SbF3 has a very low melting point, it is easy to volatilize at the set temperature and heating rate, resulting in a large number of defects in the synthesized β-KSbF4. The ion migration in β-KSbF4 is a vacancy conduction mechanism, that is, vacancies are conducive to ion migration. Therefore, the obtained solid electrolyte (β-KSbF4) has a higher ionic conductivity.
[0076] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a solid electrolyte, comprising the following steps: (1) Manually mix SbF3 and KF to obtain a mixture; (2) The mixture obtained in step (1) is subjected to heat treatment to obtain a solid electrolyte; In step (1), the molar ratio of SbF3 to KF is 1:(0.9~1.1). The manual mixing time in step (1) is 30~60 minutes; The manual mixing process in step (1) is carried out under inert conditions; The heat treatment temperature in step (2) is 220~280℃, and the heat treatment time is 11~13h; The heating rate to the heat treatment temperature is 2~8℃ / min; The solid electrolyte is β-KSbF4.
2. The preparation method according to claim 1, characterized in that: Under the inert conditions, the water and oxygen contents are independently less than 0.1 ppm.
3. The preparation method according to claim 1, characterized in that: After the heat treatment and heat preservation are completed, the furnace is cooled to room temperature.
4. The preparation method according to claim 3, characterized in that: The cooling rate for furnace cooling to room temperature is 1~6℃ / min.