Solid electrolyte Li4SnS4 and preparation method thereof

Abstract

The invention relates to solid electrolyte Li4SnS4 and a preparation method thereof. An XRD (X-Ray Diffraction) spectrogram of the solid electrolyte Li4SnS4 comprises a first characteristic peak and a second characteristic peak; the first characteristic peak is located at 2theta = 17 + / -0.5 degrees, the peak height is I1, and the peak area is S1; the second characteristic peak is located at 2theta = 25.9 + / -0.5 degrees, the peak height is I2, and the peak area is S2; in addition, the result is 0.64 lt; i1 / I2lt; 0.86, S1 / S2gt; 0.7, 0.7; the ionic conductivity of the solid electrolyte Li4SnS4 is more than 6.5 * 10 <-5 > S / cm. According to the preparation method provided by the invention, the ionic conductivity of Li4SnS4 can be remarkably improved while the synthesis efficiency is ensured.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolyte technology and relates to a solid electrolyte Li4SnS4 and its preparation method. Background Technology

[0002] Solid electrolytes are core components of next-generation high-safety lithium-sulfur batteries, among which Li4SnS4 has become a research hotspot due to its excellent ion conduction potential and chemical stability. Currently, the mainstream methods for preparing Li4SnS4 solid electrolytes in existing technologies mostly use lithium sulfide (Li2S) and tin disulfide (SnS2) as raw materials to synthesize the target product through specific reaction pathways.

[0003] However, existing preparation methods using Li₂S and SnS₂ as raw materials have limitations in balancing reaction efficiency and product performance. Although some methods can synthesize Li₄SnS₄, the ionic conductivity of the resulting solid electrolyte is often insufficient to meet the practical application requirements of high-performance batteries due to limitations in the reactivity of the raw materials and reaction conditions, thus hindering its industrialization process.

[0004] Meanwhile, existing technologies tend to control reaction temperatures primarily in the medium to low temperature range, failing to fully utilize the role of high temperatures in enhancing the sufficiency of the reactant reaction. How to significantly improve the ionic conductivity of Li4SnS4 while ensuring synthesis efficiency through optimizing the combination of reactants and reaction temperature has become a pressing issue in the preparation of Li4SnS4 solid electrolytes. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a solid electrolyte Li4SnS4 and its preparation method. The preparation method provided by this invention can significantly improve the ionic conductivity of Li4SnS4 while ensuring the synthesis efficiency.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a solid electrolyte Li4SnS4, wherein the XRD spectrum of the solid electrolyte Li4SnS4 includes a first characteristic peak and a second characteristic peak;

[0008] The first characteristic peak is located at 2θ = 17° ± 0.5°, with a peak height of I1 and a peak area of ​​S1;

[0009] The second characteristic peak is located at 2θ = 25.9° ± 0.5°, with a peak height of I2 and a peak area of ​​S2;

[0010] Furthermore, 0.64 <I1 / I2<0.86,S1 / S2> 0.7;

[0011] The ionic conductivity of the solid electrolyte Li4SnS4 is 6.5 × 10⁻⁶. -5 S / cm or higher.

[0012] The first and second characteristic peaks of the solid electrolyte Li4SnS4 provided by this invention exhibit significantly better parameter ratios (such as peak height, full width at half maximum, and peak area) than conventional diffraction peaks, indicating that the solid electrolyte possesses optimized crystal orientation and high crystallinity. Compared to the insufficient crystallinity and disordered crystal plane orientation that may exist in existing technologies, the characteristic peak characteristics of this invention indicate that the crystal planes of the solid electrolyte are regularly arranged, reducing lattice defects and grain boundary impedance, and ensuring the high crystallinity of Li4SnS4. + The continuity and smoothness of the transport channel reduce mass transfer resistance, enabling the ionic conductivity of the solid electrolyte Li4SnS4 to reach 6.5 × 10⁻⁶. -5 S / cm or higher.

[0013] In some embodiments, the full width at half maximum (FWHM1) of the first characteristic peak is greater than 0.6.

[0014] In some embodiments, the space group of the solid electrolyte Li4SnS4 includes Pnma and / or P63 / mmc.

[0015] In some embodiments, S1 > 0.144.

[0016] Secondly, the present invention provides a method for preparing a solid electrolyte Li4SnS4, the method comprising the following steps:

[0017] Li2S, Sn and S are mixed to obtain a raw material powder; the raw material powder is mixed with a solvent and subjected to a heated reaction under sealed conditions; after the reaction is completed, it is vacuum dried to obtain a precursor powder; the precursor powder is calcined in a protective atmosphere to obtain the solid electrolyte Li4SnS4 described in the first aspect.

[0018] The solid electrolyte Li4SnS4 prepared by this invention has an ionic conductivity of 6.5 × 10⁻⁶. -5 For reactions with a S / cm or higher, existing technologies use Li₂S and SnS₂ as raw materials. In SnS₂, Sn is in the +4 valence state, and the valence transformation path during the reaction with Li₂S is fixed. Furthermore, the reactivity of the raw material interface is limited, and lattice defects are easily formed due to incomplete reaction, hindering the reaction of Li₂S. +Transport. This invention uses Li₂S, elemental Sn, and S as raw materials. The elemental components have higher reactivity. Under high-pressure hydrothermal conditions, water molecules act as a mass transfer medium to accelerate ion diffusion, allowing Sn and S to first generate a more reactive low-valence Sn-S intermediate in situ, which then reacts efficiently with Li₂S to form a uniform precursor. Vacuum drying removes moisture from the precursor powder and maintains morphological stability. Subsequent calcination further promotes crystal regularization, significantly reducing lattice defects and grain boundary impedance. Therefore, the solid electrolyte Li₄SnS₄ prepared by the method of this invention can provide Li₂SnS₄ with high reactivity. + By constructing a smoother transport channel, the ionic conductivity of the product Li4SnS4 is ultimately superior to that of existing technologies.

[0019] In some embodiments, the temperature of the heating reaction is 100°C to 200°C, for example, 100°C, 120°C, 150°C, 160°C, 180°C or 200°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] In some embodiments, the heating reaction time is 1h to 5h, for example, it can be 1h, 2h, 3h, 4h or 5h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] In some embodiments, the solvent includes water.

[0022] In some embodiments, the mass-volume ratio of the raw material powder to the solvent is 1g / 20mL to 1g / 30mL, for example, it can be 1g / 20mL, 1g / 21mL, 1g / 24mL, 1g / 25mL, 1g / 27mL, 1g / 28mL or 1g / 30mL, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0023] In some embodiments, the vacuum drying temperature is 140°C to 160°C, for example, it can be 140°C, 145°C, 150°C, 155°C or 160°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] In some embodiments, the vacuum drying time is 1h to 5h, for example, it can be 1h, 2h, 3h, 4h or 5h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] In some embodiments, the calcination temperature is 240°C to 280°C, for example, 240°C, 250°C, 260°C, 270°C or 280°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] In some embodiments, the calcination time is 0.5h to 1.5h, for example, it can be 0.5h, 0.6h, 0.8h, 1h, 1.2h or 1.5h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] As a preferred embodiment of the preparation method provided in the second aspect, the preparation method includes the following steps:

[0028] (1) Mix Li2S, Sn and S to obtain raw material powder;

[0029] (2) Mix the raw material powder and solvent, and carry out the reaction at 100℃~200℃ for 1h~5h under sealed environment. After the reaction is completed, vacuum dry at 140℃~160℃ for 1h~5h to obtain the precursor powder.

[0030] The solvent includes water, and the mass-to-volume ratio of the raw material powder to the solvent is 1g / 20mL to 1g / 30mL.

[0031] (3) The precursor powder is calcined at 240~280℃ for 0.5h~1.5h in an argon atmosphere to obtain the solid electrolyte Li4SnS4.

[0032] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The first and second characteristic peaks of the solid electrolyte Li4SnS4 provided by this invention have parameter ratios (such as peak height, half-width at half-maximum, and peak area) that are significantly better than those of conventional diffraction peaks, indicating that the solid electrolyte has optimized crystal orientation and high crystallinity. Compared with the insufficient crystallinity and disordered crystal plane orientation that may exist in the prior art, the characteristic peak characteristics of this invention indicate that the crystal planes of the solid electrolyte are regularly arranged, reducing lattice defects and grain boundary impedance, and ensuring the high crystallinity of Li4SnS4. + The continuity and smoothness of the transport channel reduce mass transfer resistance, enabling the ionic conductivity of the solid electrolyte Li4SnS4 to reach 6.5 × 10⁻⁶. -5 S / cm or higher;

[0035] (2) The ionic conductivity of the solid electrolyte Li4SnS4 prepared in this invention is 6.5 × 10⁻⁶. -5For reactions with a S / cm or higher, existing technologies use Li₂S and SnS₂ as raw materials. In SnS₂, Sn is in the +4 valence state, and the valence transformation path during the reaction with Li₂S is fixed. Furthermore, the reactivity of the raw material interface is limited, and lattice defects are easily formed due to incomplete reaction, hindering the reaction of Li₂S. + Transport. This invention uses Li₂S, elemental Sn, and S as raw materials. The elemental components have higher reactivity. Under high-pressure hydrothermal conditions, water molecules act as a mass transfer medium to accelerate ion diffusion, allowing Sn and S to first generate a more reactive low-valence Sn-S intermediate in situ, which then reacts efficiently with Li₂S to form a uniform precursor. Vacuum drying removes moisture from the precursor powder and maintains morphological stability. Subsequent calcination further promotes crystal regularization, significantly reducing lattice defects and grain boundary impedance. Therefore, the solid electrolyte Li₄SnS₄ prepared by the method of this invention can provide Li₂SnS₄ with high reactivity. + By constructing a smoother transport channel, the ionic conductivity of the product Li4SnS4 is ultimately superior to that of existing technologies. Attached Figure Description

[0036] Figure 1 These are the XRD patterns of the solid electrolyte Li4SnS4 obtained in Examples 1 to 4 and Comparative Examples 1 to 3. Detailed Implementation

[0037] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0038] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0039] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0040] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0041] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0042] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0043] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0044] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0045] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0046] Example 1

[0047] This embodiment provides a method for preparing the solid electrolyte Li4SnS4, including the following steps:

[0048] (1) Mix Li2S, Sn and S in a molar ratio of 2:1:2 to obtain raw material powder;

[0049] (2) Mix the raw material powder and solvent in a high pressure vessel, seal the high pressure vessel, and carry out a reaction at 150°C for 3 hours. After the reaction is completed, filter to remove the residue, and then vacuum dry at 150°C for 3 hours to obtain the precursor powder.

[0050] The solvent is water, and the mass-to-volume ratio of the raw material powder to the solvent is 1g / 25mL;

[0051] (3) The precursor powder is calcined at 250°C for 1 hour in an argon atmosphere to obtain the solid electrolyte Li4SnS4.

[0052] Example 2

[0053] This embodiment provides a method for preparing the solid electrolyte Li4SnS4, including the following steps:

[0054] (1) Mix Li2S, Sn and S in a molar ratio of 2:1:2 to obtain raw material powder;

[0055] (2) Mix the raw material powder and solvent in a high pressure vessel, seal the high pressure vessel, and carry out a reaction at 150°C for 5 hours. After the reaction is completed, filter to remove the residue, and then vacuum dry at 150°C for 3 hours to obtain the precursor powder.

[0056] The solvent is water, and the mass-to-volume ratio of the raw material powder to the solvent is 1g / 25mL;

[0057] (3) The precursor powder is calcined at 250°C for 1 hour in an argon atmosphere to obtain the solid electrolyte Li4SnS4.

[0058] Example 3

[0059] This embodiment provides a method for preparing the solid electrolyte Li4SnS4, including the following steps:

[0060] (1) Mix Li2S, Sn and S in a molar ratio of 2:1:2 to obtain raw material powder;

[0061] (2) Mix the raw material powder and solvent in a high pressure vessel, seal the high pressure vessel, and carry out a reaction at 100°C for 3 hours. After the reaction is completed, filter to remove the residue, and then vacuum dry at 150°C for 3 hours to obtain the precursor powder.

[0062] The solvent is water, and the mass-to-volume ratio of the raw material powder to the solvent is 1g / 25mL;

[0063] (3) The precursor powder is calcined at 250°C for 1 hour in an argon atmosphere to obtain the solid electrolyte Li4SnS4.

[0064] Example 4

[0065] This embodiment provides a method for preparing the solid electrolyte Li4SnS4, including the following steps:

[0066] (1) Mix Li2S, Sn and S in a molar ratio of 2:1:2 to obtain raw material powder;

[0067] (2) Mix the raw material powder and solvent in a high pressure vessel, seal the high pressure vessel, and carry out a reaction at 200°C for 1 hour. After the reaction is completed, filter to remove the residue, and then vacuum dry at 150°C for 3 hours to obtain the precursor powder.

[0068] The solvent is water, and the mass-to-volume ratio of the raw material powder to the solvent is 1g / 25mL;

[0069] (3) The precursor powder is calcined at 250°C for 1 hour in an argon atmosphere to obtain the solid electrolyte Li4SnS4.

[0070] Comparative Example 1

[0071] This comparative example provides a method for preparing the solid electrolyte Li4SnS4, including the following steps:

[0072] (1) Mix Li2S, Sn and S in a molar ratio of 2:1:2 to obtain raw material powder;

[0073] (2) Mix the raw material powder and solvent in a glass bottle, cover the bottle, and carry out the reaction at 80°C for 24 hours. After the reaction is completed, filter to remove the residue, and then vacuum dry at 150°C for 3 hours to obtain the precursor powder.

[0074] The solvent is water, and the mass-to-volume ratio of the raw material powder to the solvent is 1g / 25mL;

[0075] (3) The precursor powder is calcined at 250°C for 1 hour in an argon atmosphere to obtain the solid electrolyte Li4SnS4.

[0076] Comparative Example 2

[0077] This comparative example provides a method for preparing the solid electrolyte Li4SnS4, including the following steps:

[0078] Weigh Li2S and SnS2 at a molar ratio of 2:1, and place them together with zirconia balls into a ball mill jar. Stir at 510 rpm for 60 min, pause for 10 min, and repeat 10 times to obtain precursor powder. Heat the precursor powder to 390℃ in an argon atmosphere for 3 h, and keep it at 390℃ for 2 h to obtain the solid electrolyte Li4SnS4.

[0079] Comparative Example 3

[0080] This comparative example provides a method for preparing the solid electrolyte Li4SnS4, including the following steps:

[0081] Li₂S, Sn, and S were weighed according to a molar ratio of 2:1:2 and placed together with zirconia balls into a ball mill jar. The mixture was stirred at 510 rpm for 60 min using a planetary ball mill (Fritsch, P-6), paused for 10 min, and repeated 10 times to obtain the precursor powder. The precursor powder was heated to 390 °C in an argon atmosphere for 3 h and held at 390 °C for 2 h to obtain the solid electrolyte Li₄SnS₄.

[0082] Performance Characterization

[0083] X-ray diffraction measurement

[0084] The solid electrolytes obtained in the examples and comparative examples were filled into grooves with a diameter of 20 mm and a depth of 0.2 mm, and flattened with a glass plate to serve as samples. The samples were sealed with an X-ray diffraction film and measured without contact with air. Peak height extraction was performed against the background of the X-ray diffraction pattern.

[0085] The testing setup was a MiniFlex600 manufactured by RIGAKU, with a tube voltage of 40kV, a tube current of 15mA, an X-ray wavelength of Cu-Ka (1.5418Å), a Solar slit of 2.5°, a D / teX Ultra2 detector, a measurement range of 2θ = 10deg~70deg, a step size of 0.02deg, a scanning speed of 2deg / s, and a block-shaped, airtight sample holder.

[0086] The XRD diffraction patterns of the solid electrolytes provided in Examples 1-4 and Comparative Examples 1-3 are as follows: Figure 1 As shown, by Figure 1 It is known that the solid electrolyte obtained by the preparation method provided by the present invention has a first characteristic peak at 2θ=17°±0.5° and a second characteristic peak at 2θ=25.9°±0.5°.

[0087] Analysis of the X-ray diffraction pattern: The full width at half maximum (FWHM) and peak area were calculated using Igor Pro via "Multi-peak Fitting". During peak fitting, "Auto-locate Peaks Now" and "Find More in Residuals" were applied. To avoid fitting errors, "Voigt" was selected in "Set Type for All Peaks". The fitted pattern is not shown. Peak height extraction was performed with the X-ray diffraction pattern background present.

[0088] [Ionic Conductivity Measurement]

[0089] The solid electrolytes obtained in the examples and comparative examples were used to prepare circular pellets with a diameter of 10 mm (resulting in a cross-sectional area S) and a height (L) of 5 cm as samples. Electrode terminals were connected to both sides of the samples, and AC impedance spectroscopy was performed at 25°C and a pressure of 690 MPa (frequency 0.1 Hz to 1 MHz, amplitude 10 mV) to obtain Cole-Cole curves. The real part Z'(Ω) near the right end of the arc observed in the high-frequency region, where -Z''(Ω) is the minimum point, was taken as the bulk resistance R(Ω) of the electrolyte, and the ionic conductivity σ(S / cm) was calculated according to the following formula. The results are shown in Table 1.

[0090] Table 1

[0091]

[0092] In summary, the first and second characteristic peaks of the solid electrolyte Li4SnS4 provided by this invention exhibit significantly better parameter ratios (such as peak height, full width at half maximum, and peak area) than conventional diffraction peaks, indicating that the solid electrolyte possesses optimized crystal orientation and high crystallinity. Compared to the insufficient crystallinity and disordered crystal plane orientation that may exist in existing technologies, the characteristic peak characteristics of this invention indicate that the crystal planes of the solid electrolyte are regularly arranged, reducing lattice defects and grain boundary impedance, and ensuring the high crystallinity of Li4SnS4. + The continuity and smoothness of the transport channel reduce mass transfer resistance, enabling the ionic conductivity of the solid electrolyte Li4SnS4 to reach 6.5 × 10⁻⁶. -5 The ionic conductivity of the solid electrolyte Li4SnS4 prepared by this invention is above S / cm; the ionic conductivity is 6.5 × 10⁻⁶. -5 For reactions with a S / cm or higher, existing technologies use Li₂S and SnS₂ as raw materials. In SnS₂, Sn is in the +4 valence state, and the valence transformation path during the reaction with Li₂S is fixed. Furthermore, the reactivity of the raw material interface is limited, and lattice defects are easily formed due to incomplete reaction, hindering the reaction of Li₂S. +Transport. This invention uses Li₂S, elemental Sn, and S as raw materials. The elemental components have higher reactivity. Under high-pressure hydrothermal conditions, water molecules act as a mass transfer medium to accelerate ion diffusion, allowing Sn and S to first generate a more reactive low-valence Sn-S intermediate in situ, which then reacts efficiently with Li₂S to form a uniform precursor. Vacuum drying removes moisture from the precursor powder and maintains morphological stability. Subsequent calcination further promotes crystal regularization, significantly reducing lattice defects and grain boundary impedance. Therefore, the solid electrolyte Li₄SnS₄ prepared by the method of this invention can provide Li₂SnS₄ with high reactivity. + By constructing a smoother transport channel, the ionic conductivity of the product Li4SnS4 is ultimately superior to that of existing technologies.

[0093] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A solid electrolyte Li4SnS4, characterized in that, The XRD pattern of the solid electrolyte Li4SnS4 includes a first characteristic peak and a second characteristic peak; The first characteristic peak is located at 2θ = 17° ± 0.5°, with a peak height of I1 and a peak area of ​​S1; The second characteristic peak is located at 2θ = 25.9° ± 0.5°, with a peak height of I2 and a peak area of ​​S2; Furthermore, 0.64 <I1 / I2<0.86,S1 / S2> 0.7; The ionic conductivity of the solid electrolyte Li4SnS4 is 6.5 × 10⁻⁶. -5 S / cm or higher.

2. The solid electrolyte Li4SnS4 according to claim 1, characterized in that, The full width at half maximum (FWHM) of the first characteristic peak is greater than 0.

6.

3. The solid electrolyte Li4SnS4 according to claim 1, characterized in that, The space group of the solid electrolyte Li4SnS4 includes Pnma and / or P63 / mmc; And / or, S1>0.

144.

4. A method for preparing a solid electrolyte Li4SnS4, characterized in that, The preparation method includes the following steps: Li2S, Sn and S are mixed to obtain a raw material powder; the raw material powder is mixed with a solvent and subjected to a heated reaction under sealed conditions; after the reaction is completed, it is vacuum dried to obtain a precursor powder; the precursor powder is calcined in a protective atmosphere to obtain the solid electrolyte Li4SnS4 as described in any one of claims 1 to 3.

5. The preparation method according to claim 4, characterized in that, The temperature of the heating reaction is 100℃~200℃.

6. The preparation method according to claim 4 or 5, characterized in that, The heating reaction takes 1 to 5 hours.

7. The preparation method according to any one of claims 4 to 6, characterized in that, The solvent includes water; And / or, the mass-to-volume ratio of the raw material powder to the solvent is 1g / 20mL to 1g / 30mL.

8. The preparation method according to any one of claims 4 to 7, characterized in that, The vacuum drying temperature is 140℃~160℃; And / or, the vacuum drying time is 1h to 5h.

9. The preparation method according to any one of claims 4 to 8, characterized in that, The calcination temperature is 240℃~280℃; And / or, the calcination time is 0.5h to 1.5h.

10. The preparation method according to claim 4, characterized in that, The preparation method includes the following steps: (1) Mix Li2S, Sn and S to obtain raw material powder; (2) Mix the raw material powder and solvent, and carry out the reaction at 100℃~200℃ for 1h~5h under sealed environment. After the reaction is completed, vacuum dry at 140℃~160℃ for 1h~5h to obtain the precursor powder. The solvent includes water, and the mass-to-volume ratio of the raw material powder to the solvent is 1g / 20mL to 1g / 30mL. (3) The precursor powder is calcined at 240~280℃ for 0.5h~1.5h in an argon atmosphere to obtain the solid electrolyte Li4SnS4.

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