Solid electrolytes, their preparation methods, and batteries

Abstract

This invention provides a solid electrolyte, its preparation method, and a battery, specifically relating to the field of solid electrolyte technology. The solid electrolyte has the chemical formula (100-x)[Li] a P b S 4‑c O c ]·xLiBH4; where 2.5≤a≤3.5, b=1, 0

Description

Technical Field

[0001] The present invention relates to the technical field of solid electrolytes, and in particular to a solid electrolyte, a preparation method thereof, and a battery. Background Art

[0002] Sulfide solid electrolytes are regarded as key materials for next-generation all-solid-state lithium batteries due to their high ionic conductivity, wide electrochemical window, and good interfacial stability towards lithium metal. In recent years, to synergistically improve ion transport kinetics and structural stability, researchers have proposed introducing borohydrides (such as LiBH4) into sulfide matrices to form composite electrolyte systems (such as Li7P3S 11 –LiBH4, i.e., LPS-LBH). While maintaining relatively high lithium-ion conductivity, such composite materials exhibit improved interfacial wettability and low-temperature performance, and their feasibility has been verified in laboratory-scale solid-state battery prototypes.

[0003] However, the LPS-LBH system has an inherent safety flaw: its molecular structure contains both highly reactive P-S bonds and B-H bonds, which undergo uncontrollable and violent hydrolysis reactions even under the action of trace amounts of moisture. This reaction not only instantaneously releases a large amount of reaction heat but also simultaneously generates strongly reducing and flammable gases such as H2S and H2; heat accumulation and flammable gas enrichment in a sealed battery cavity are extremely likely to trigger a thermal runaway chain reaction, ultimately leading to fire or even explosion. This problem seriously restricts the practical engineering application of LPS-LBH materials.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a solid electrolyte, a preparation method thereof, and a battery, aiming to solve at least one of the above technical problems.

[0006] To achieve the above object of the present invention, the following technical solutions are specifically adopted: In the first aspect of the present invention, a solid electrolyte is provided, with the chemical formula (100 - x)[Li a P b S 4-c O c ·xLiBH4; wherein, 2.5 ≤ a ≤ 3.5, b = 1, 0 < c ≤ 0.5, and 50 ≤ x ≤ 80.

[0007] Further, in the above chemical formula, c satisfies 0.125 ≤ c ≤ 0.35.

[0008] Further, in the above chemical formula, x satisfies 60 ≤ x ≤ 70.

[0009] Furthermore, the solid electrolyte, when subjected to CuKα radiation, exhibits a peak A at 2θ = 15.35 ± 0.5° and a peak B at 2θ = 20.95 ± 0.5° in its X-ray diffraction pattern; wherein the peak area S of peak B is... B The peak area S of peak A A The ratio of S B / S A Satisfy 0 B / S A <0.80.

[0010] Furthermore, S B / S A Satisfy 0 B / S A <0.30.

[0011] Furthermore, the X-ray diffraction pattern of the solid electrolyte using CuKα radiation shows peak C at 2θ = 29.60 ± 0.5° and peak D at 2θ = 30.90 ± 0.5°; wherein, the peak height H of peak C is... C Peak height H of peak D D The ratio of H C / H D Satisfying 0.40≤H C / H D ≤0.80.

[0012] Furthermore, the X-ray diffraction pattern using CuKα radiation exhibits a peak E at 2θ = 27.20 ± 0.5°; where the peak intensity I of peak E is... E Peak intensity I of peak A A The ratio of I E / I A Satisfying 0≤I E / I A <0.33.

[0013] Furthermore, I E / I A Satisfy 0 E / I A ≤0.30.

[0014] The second aspect of the present invention provides a method for preparing the solid electrolyte, wherein a lithium source, a phosphorus source, a sulfur source and an oxygen source are mixed in an inert atmosphere at a molar ratio of Li:P:S:O=a:1:(4-c):c, an organic solvent and a grinding medium are added, and the mixture is ground to obtain a precursor suspension. The precursor suspension and LiBH4 were mixed and stirred to obtain a mixture; finally, the mixture was heat-treated to obtain the solid electrolyte.

[0015] ​​​A third aspect of the present invention provides a battery comprising the solid electrolyte described in the first aspect.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: The solid electrolyte provided by this invention can stabilize phosphorus and boron ions through oxygen substitution, thereby increasing the hydrolysis energy barrier, significantly suppressing the heat of reaction and the generation of H2S and H2, and preventing the material from igniting when exposed to water. At the same time, relying on the mixed anion effect, the diversification of electrostatic potential and the increase of configuration entropy under low concentration oxygen substitution offset the effect of lattice contraction, so that the electrolyte has both high ionic conductivity and excellent hydrolysis stability.

[0017] The preparation method provided by this invention, by introducing an oxygen source under an inert atmosphere and combining liquid-phase assisted ball milling with low-temperature heat treatment, achieves the controllable incorporation of oxygen atoms into the lithium thiophosphate framework Li3PS4, effectively suppressing the exposure of easily hydrolyzed PS bonds in the Li3PS4-LiBH4 system and significantly improving moisture stability. At the same time, the fast ion channels provided by LiBH4 and the lattice distortion and interface compatibility optimized by oxygen doping enable the solid electrolyte to maintain high ionic conductivity, and the process is compatible with existing solid electrolyte production lines, requiring no high-temperature sintering or complex equipment, and has good scalability and industrialization potential.

[0018] The battery provided by this invention, given that the solid electrolyte combines high safety and excellent electrochemical performance, improves the overall cycle life, rate performance and wide temperature range adaptability of the battery, making it particularly suitable for solid-state power batteries and energy storage systems with stringent requirements for safety and manufacturing economy. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 The graph shows the results of the water stability evaluation obtained from Test Example 1; Figure 2 The X-ray diffraction pattern obtained in test example 3. Detailed Implementation

[0021] The embodiments of the present invention will be described in detail below in conjunction with the embodiments and examples. However, those skilled in the art will understand that the following embodiments and examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present invention.

[0022] In the first aspect of the present invention, a solid electrolyte is provided, with the chemical formula (100 - x)[Li a P b S 4-c O c ·xLiBH4; wherein, 2.5 ≤ a ≤ 3.5, b = 1, 0 < c ≤ 0.5, and 50 ≤ x ≤ 80.

[0023] The solid electrolyte provided by the present invention can stabilize phosphorus ions and boron ions through oxygen substitution, improve the hydrolysis energy barrier, significantly inhibit the reaction heat and the generation of H2S and H2, and avoid the material catching fire when encountering water; at the same time, relying on the mixed anion effect, the diversification of the electrostatic potential and the increase of the configurational entropy under low-concentration oxygen substitution offset the influence of lattice contraction, making the electrolyte have both high ionic conductivity and excellent hydrolysis stability.

[0024] The inventors found that the P-S bond and B-H bond formed by coordination in LPS-LBH have high polarizability and reactivity, and are extremely prone to synergistic hydrolysis under the action of trace water, releasing H₂S, H₂ and accompanied by intense heat release. The present invention realizes the partial equivalent / quasi-equivalent substitution of S 2- by introducing an appropriate amount of oxygen source into the LPS skeleton, thereby constructing a more matching interaction in the local coordination environment, such as P-O and B-O. This structural modulation significantly enhances the charge localization and bond stability of the P center and B center, increases the activation energy barrier of the P-S bond breaking and B-H hydrolysis paths, suppresses the hydrolysis chain reaction kinetics from the source, greatly reduces the reaction heat output and the generation amount of H₂S and H₂, and fundamentally solves the safety bottleneck of the LPS-LBH system catching fire when wet.

[0025] The present invention realizes low-concentration mixed anion regulation by controlling the oxygen substitution amount to 0 < c ≤ 0.5: on the one hand, the coexistence of O 2- and S 2- results in a significant diversification of the spatial distribution of the electrostatic potential of the anion lattice, enhancing the local electric field gradient of the lithium ion migration channel; on the other hand, the disordered mixing of S / O greatly increases the configurational entropy, effectively alleviating the ion transport resistance caused by the rigid contraction of the lattice. The synergistic effect of the two not only offsets the negative effect of lattice densification, but instead optimizes the lithium ion transition energy barrier and carrier concentration, enabling the composite electrolyte to maintain high room temperature ionic conductivity while obtaining excellent hydrolysis stability.

[0026] Typical but non - restrictive, the solid - state electrolyte chemical formula is (100 - x)[Li a P b S 4-c O c ·xLiBH4, where the value of a can be, for example, 2.5, 2.7, 2.9, 3.0, 3.2, 3.4 or 3.5, or any value within the range of 2.5 ≤ a ≤ 3.5; the value of b is 1; the value of c can be, for example, 0.1, 0.2, 0.3, 0.4 or 0.5, or any value within the range of 0 < c ≤ 0.5; the value of x can be, for example, 50, 55, 60, 65, 70, 75 or 80, or any value within the range of 50 ≤ x ≤ 80.

[0027] Furthermore, in the above chemical formula, c satisfies 0.125 ≤ c ≤ 0.35. By enhancing the stability of the P / B central bond and raising the hydrolysis energy barrier, the hydrolysis stability is significantly improved; by optimizing the electrostatic potential gradient and configurational entropy with the moderate mixed - anion effect, the lattice contraction is offset, and an optimal balance between maintaining high ionic conductivity and stability is achieved.

[0028] Furthermore, in the above chemical formula, x satisfies 60 ≤ x ≤ 70. While ensuring that LiBH4 provides sufficient fast - ion channels and interface wettability, the structural integrity and continuity of the oxygen - doped lithium thiophosphate framework are maintained, thereby synergistically achieving high ionic conductivity and excellent hydrolysis stability.

[0029] Furthermore, the X - ray diffraction pattern of the described solid - state electrolyte using CuKα radiation has a peak A at 2θ = 15.35 ± 0.5° and a peak B at 2θ = 20.95 ± 0.5°; where the peak area S B of peak B and the peak area S A of peak A, the ratio S B / S A satisfies 0 < S B / S A < 0.80, which directly characterizes that oxygen has been successfully introduced and regulated the local order degree of the lithium thiophosphate framework and the dispersion state of LiBH4, thus verifying the structural basis for the synergistic achievement of improved hydrolysis stability and high ionic conductivity at the XRD - detectable level.

[0030] Furthermore, S B / S A satisfies 0 < S B / S A < 0.30.

[0031] Furthermore, the X - ray diffraction pattern of the described solid - state electrolyte using CuKα radiation has a peak C at 2θ = 29.60 ± 0.5° and a peak D at 2θ = 30.90 ± 0.5°; where the peak height HC Peak height H of peak D D The ratio of H C / H D Satisfying 0.40≤H C / H D ≤0.80, oxygen doping leads to a decrease in the lattice symmetry of the LPS matrix and the introduction of micro-strain, indicating that the PS framework undergoes controllable distortion rather than simple phase separation. This optimizes the non-uniform electric field and interface compatibility of the lithium-ion transport path while maintaining structural integrity, and is a key crystallographic criterion for the synergistic achievement of high conductivity and high hydrolysis stability.

[0032] Furthermore, the X-ray diffraction pattern using CuKα radiation exhibits a peak E at 2θ = 27.20 ± 0.5°; where the peak intensity I of peak E is... E Peak intensity I of peak A A The ratio of I E / I A Satisfying 0≤I E / I A <0.33 indicates that oxygen doping did not induce strong interfering impurities or disordered aggregation, confirming that low concentration of oxygen achieves selective local coordination regulation at the atomic scale rather than macroscopic structural destruction, ensuring that the material maintains the crystallinity of the lithium thiophosphate backbone and the integrity of the main ion transport channels while improving hydrolysis stability.

[0033] Furthermore, I E / I A Satisfy 0 E / I A ≤0.30.

[0034] The second aspect of the present invention provides a method for preparing the solid electrolyte, wherein a lithium source, a phosphorus source, a sulfur source and an oxygen source are mixed in an inert atmosphere at a molar ratio of Li:P:S:O=a:1:(4-c):c, an organic solvent and a grinding medium are added, and the mixture is ground to obtain a precursor suspension. The precursor suspension and LiBH4 were mixed and stirred to obtain a mixture; finally, the mixture was heat-treated to obtain the solid electrolyte.

[0035] The preparation method provided by this invention, by introducing an oxygen source under an inert atmosphere and combining liquid-phase assisted ball milling with low-temperature heat treatment, achieves the controllable incorporation of oxygen atoms into the lithium thiophosphate framework Li3PS4, effectively suppressing the exposure of easily hydrolyzed PS bonds in the Li3PS4-LiBH4 system and significantly improving moisture stability. At the same time, the fast ion channels provided by LiBH4 and the lattice distortion and interface compatibility optimized by oxygen doping enable the solid electrolyte to maintain high ionic conductivity, and the process is compatible with existing solid electrolyte production lines, requiring no high-temperature sintering or complex equipment, and has good scalability and industrialization potential.​

[0036] In embodiments of the present invention, the lithium source includes Li₂S and Li₂O; the phosphorus source includes P₂S₅; and the oxygen source includes Li₂O or P₂O₅. As long as the final feed, after metering and conversion, meets the elemental ratios in the target chemical formula, it is acceptable.

[0037] Preferably, the organic solvent comprises tetrahydrofuran.

[0038] Preferably, the grinding media comprises ceramic balls.

[0039] Preferably, the stirring reaction time is 24-72 hours.

[0040] Preferably, the heat treatment temperature is 140~180℃ and the time is 1~5h.

[0041] A third aspect of the present invention provides a battery comprising the solid electrolyte described in the first aspect.

[0042] The battery provided by this invention, given that the solid electrolyte combines high safety and excellent electrochemical performance, improves the overall cycle life, rate performance and wide temperature range adaptability of the battery, making it particularly suitable for solid-state power batteries and energy storage systems with stringent requirements for safety and manufacturing economy.

[0043] The present invention is further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for illustrative purposes and should not be construed as limiting the invention in any way. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of the present invention were carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0044] Example 1 Under an argon atmosphere, 1 g of Li₂S, Li₂O, and P₂S₅ (molar ratio Li:P:S:O = 3:1:3.875:0.125), 20 mL of tetrahydrofuran, and ceramic balls were added to a centrifuge tube and shaken to obtain a precursor suspension. Then, the obtained precursor suspension and LiBH₄ were added to a medium-volume flask to make a molar ratio of Li₃PS₅. 3.875 O 0.125 The ratio of LiBH4 to precursor powder was 33:66. After stirring the mixture for 48 hours, it was vacuum dried to obtain the precursor powder. Finally, the obtained precursor powder was heat-treated at 160°C for 3 hours in an argon atmosphere to obtain 33[Li3PS] from Example 1. 3.875 O 0.125 ]·66[LiBH4] solid electrolyte.

[0045] Example 2 Unlike Example 1, the Li:P:S:O ratio was 3:1:3.75:0.25, while the rest of the preparation method was the same as in Example 1, resulting in 33[Li3PS] of Example 2. 3.75 O 0.25 ]·66[LiBH4] solid electrolyte.

[0046] Example 3 Unlike Example 1, the Li:P:S:O ratio was 3:1:3.65:0.35, while the rest of the preparation method was the same as in Example 1, resulting in 33[Li3PS] of Example 3. 3.65 O 0.35 ]·66[LiBH4] solid electrolyte.

[0047] Example 4 Unlike Example 1, the Li:P:S:O ratio was 3:1:3.50:0.50, while the rest of the preparation method was the same as in Example 1, resulting in 33[Li3PS] of Example 4. 3.5 O 0.5 ]·66[LiBH4] solid electrolyte.

[0048] Example 5 Unlike Example 1, Li3PS 3.75 O 0.25 The molar ratio of LiBH4 was 50:50, and the rest of the preparation method was the same as in Example 1, resulting in 50[Li3PS] in Example 5. 3.75 O 0.25 50[LiBH4] solid electrolyte.

[0049] Example 6 Unlike Example 1, Li3PS 3.75 O 0.25 The molar ratio of LiBH4 was 20:80, and the rest of the preparation method was the same as in Example 1, resulting in 20[Li3PS] for Example 6. 3.75 O 0.25 ]·80[LiBH4] solid electrolyte.

[0050] Comparative Example 1 Under an argon atmosphere, 1 g of Li₂S and P₂S₅ (molar ratio Li:P:S = 3:1:4), 20 mL of tetrahydrofuran, and ceramic balls were added to a centrifuge tube and shaken to obtain a precursor suspension. Then, the obtained precursor suspension and LiBH₄ were added to a medium-volume flask to make a molar ratio of Li₃PS₄:LiBH₄ = 33:66. After stirring the mixture for 48 hours, it was vacuum dried to obtain precursor powder. Finally, the obtained precursor powder was heat-treated at 160°C for 3 hours under an argon atmosphere to obtain the 33[Li₃PS₄]·66[LiBH₄] solid electrolyte of Comparative Example 1.

[0051] Test Example 1: [Water Stability Evaluation] The water stability of the solid electrolytes in the examples and comparative examples was evaluated by taking 100 mg of solid electrolyte and placing it on Kimberly-Clark wiping paper, adding 60 μL of water, and observing for 1 min.

[0052] If the sample catches fire, it is rated "poor"; if the sample does not catch fire but partially burns, it is rated "medium"; if the sample neither catches fire nor burns, it is rated "excellent".

[0053] The results of the water stability evaluation are summarized in Table 1.

[0054] Test Example 2: [Ionic Conductivity Measurement] 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 sample, 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 the Cole-Cole curve. 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.

[0055] R = ρ(L / S); σ = 1 / ρ.

[0056] The ionic conductivity data are summarized in Table 1.

[0057] Test Example 3: [X-ray Diffraction Measurement] 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.

[0058] The testing setup was a Mini Flex600 manufactured by RIGAKU, with a tube voltage of 40 kV, a tube current of 15 mA, an X-ray wavelength of Cu-Ka (1.5418 Å), a Solar slit of 2.5°, a D / teX Ultra2 detector, a measurement range of 2θ = 10°~70°, a step size of 0.02°, a scanning speed of 2° / s, and a block-shaped, airtight sample holder.

[0059] X-ray diffraction patterns such as Figure 2 As shown, for Figure 2 Analysis: Peak area S and peak height H were calculated using IgorPro 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. Peak intensity I refers to the intensity data obtained directly from XRD measurements without background removal.

[0060] The data were statistically analyzed and presented in Table 1.

[0061] Table 1

[0062] As can be seen from Table 1, as the oxygen substitution amount c gradually increased from 0.125 in Example 1 to 0.50 in Example 4, the relative peak area ratio of XRD peak B to S... B / S A The increase from 0.119 to 0.476 indicates that the content of the phase corresponding to this peak increases with the introduction of oxygen; however, when c further increases to 0.50, S... B / S A It jumped to 0.476, while the peak E intensity I E / I A Approaching 0 suggests that high oxygen content may trigger local structural reconstruction or phase separation, weakening specific lattice vibration modes.

[0063] It is worth noting that in Example 3, c is 0.35 in S B / S A S E / I A and H C / H DAll indicators are in a relatively good balance range, and its water stability is "excellent" and its ionic conductivity reaches 3.14 mS / cm, which is the second highest value among all examples, slightly lower than 3.34 mS / cm in Example 2.

[0064] Comparing Examples 1, 5, and 6: x increases, i.e., LiBH4 increases, leading to S B / S A The increase, but excessive LiBH4 actually caused S to rise. B / S A The abnormal spike to 0.759, accompanied by a sharp drop in ionic conductivity to 1.02 mS / cm, while water stability remained "excellent," indicates that an excessively high LiBH4 ratio may induce aggregation or disrupt the continuity of the oxygen-doped framework, reducing the effective lithium transport channel density. Conversely, although Example 6 (x=80) had the highest LiBH4 content, S... B / S A With an efficiency of only 0.301 and an electrical conductivity of 1.26 mS / cm, it is evident that simply adding LiBH4 may not necessarily improve performance; it is necessary to coordinate with oxygen doping to optimize interface wetting and lattice matching.

[0065] All oxygen-doped examples exhibited significantly better water stability than the undoped Comparative Example 1, directly verifying the crucial role of oxygen substitution in suppressing the synergistic hydrolysis of PS / BH. In Comparative Example 1, S... B / S A =0、S E / I A =0、H C / H D =1.05379 (close to 1:1), reflecting that the peaks C and D in its XRD pattern are almost symmetrical, corresponding to the typical two-phase coexistence structure of the original LPS-LiBH4 system. It lacks oxygen-induced lattice distortion and electrostatic potential modulation, so it cannot block the hydrolysis chain reaction.

[0066] The highest conductivity of 3.34 mS / cm was observed in Example 2, followed by Example 3, both of which satisfied the S... B / S A <0.30, H C / H D ≈0.69–0.44, I E / I A The XRD fingerprint characteristics of <0.03 indicate that moderate oxygen doping, without significantly sacrificing crystallinity, achieves dual optimization of carrier concentration and migration rate through increased configuration entropy and enhanced electrostatic potential gradient, in conjunction with the fast ion channels provided by LiBH4. However, the conductivity in Example 4 dropped to 2.09 mS / cm, confirming that excessive oxygen leads to excessive lattice disorder or phase separation, which in turn hinders long-range ion transport.

[0067] Figure 1The graph shows the results of the water stability evaluation obtained from Test Example 1. Figure 1 It can be seen that none of the samples in Examples 1 to 6 showed any signs of ignition. Among them, Example 6 only had a very small amount of local charring marks, while the other sample samples remained in a white powder state without obvious signs of combustion or carbonization. However, the sample in Comparative Example 1 showed obvious carbonization and blackening and combustion marks, indicating a violent reaction.

[0068] According to the evaluation criteria, the samples of Examples 1 to 5 neither ignited nor burned, and their water stability was rated as excellent; the sample of Example 6 did not ignite but showed a small amount of localized charring, and its water stability was rated as moderate; the sample of Comparative Example 1 showed obvious combustion and carbonization, and its water stability was significantly worse than that of the other examples, with an overall poor performance. Overall, the water stability of the solid electrolytes in all examples was significantly better than that of Comparative Example 1, exhibiting better water resistance.

[0069] In summary, the low-concentration oxygen substitution of this invention is the structural key to breaking the dilemma of mutual repulsion between high conductivity and high stability in the LPS-LiBH4 system; its effect can be accurately characterized by the ratio of characteristic peaks in XRD, and a robust structure-activity relationship is formed with water stability and ionic conductivity.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A solid electrolyte, characterized in that, The chemical formula is (100-x)[Li a P b S 4-c O c ]·xLiBH4; Among them, 2.5 ≤ a ≤ 3.5, b = 1, 0 < c ≤ 0.5, and 50 ≤ x ≤ 80; The X-ray diffraction pattern using CuKα radiation shows peak A at 2θ = 15.35 ± 0.5° and peak B at 2θ = 20.95 ± 0.5°; the peak area S of peak B is... B The peak area S of peak A A The ratio of S B / S A Satisfy 0 B / S A <0.80;​ The X-ray diffraction pattern using CuKα radiation shows peak C at 2θ = 29.60 ± 0.5° and peak D at 2θ = 30.90 ± 0.5°; the peak height H of peak C is... C Peak height H of peak D D The ratio of H C / H D Satisfying 0.40≤H C / H D ≤0.80; The X-ray diffraction pattern using CuKα radiation has a peak E at 2θ = 27.20 ± 0.5°; the peak intensity I of peak E is... E Peak intensity I of peak A A The ratio of I E / I A Satisfying 0≤I E / I A <0.33; The preparation method of the solid electrolyte is that under an inert atmosphere, Li2S, Li2O, and P2S5 are mixed in a molar ratio of Li:P:S:O = a:1:(4 - c):c, and tetrahydrofuran and a grinding medium are added, and then ground to obtain a precursor suspension; the precursor suspension and LiBH4 are mixed and stirred to react to obtain a mixture; finally, the mixture is heat-treated at 140 - 180 °C for 1 - 5 h to obtain the solid electrolyte.

2. The solid electrolyte according to claim 1, characterized in that, c satisfies 0.125 ≤ c ≤ 0.

35.

3. The solid electrolyte according to claim 1, characterized in that, x satisfies 60 ≤ x ≤ 70.

4. The solid electrolyte according to claim 1, characterized in that, S B / S A Satisfy 0 B / S A <0.30.​ 5. The solid electrolyte according to claim 1, characterized in that, I E / I A full foot 0 E / I A ≤0.30.​ 6. A battery, characterized in that, It contains the solid electrolyte described in any one of claims 1 to 5.

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