Sulfide solid electrolyte, and preparation method therefor and use thereof

Abstract

A sulfide solid electrolyte, and a preparation method therefor and the use thereof. The chemical composition of the sulfide solid electrolyte is LiaSbbPcSdOeClf, wherein 4.5≤a≤6.5, 0.02≤b≤0.9, 0.01≤e≤0.06, 0.9≤f≤1.6, b+c＝1, d+e＝5, and Sb-S bonding accounts for not less than 98% of total bonding formed by Sb. In an X-ray diffraction pattern of the sulfide solid electrolyte, the intensities of diffraction peaks with 2θ values of 29.8°±0.25°, 33.33°±0.25° and 31.45°±0.25° are Ia, Ib and Ic, respectively; and Ic / Ia is 18-26%, and Ic / Ib is 25-36%. The sulfide solid electrolyte has good ionic conductivity, and also has relatively good stability in air.

Description

A sulfide solid electrolyte and its preparation method and application

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on June 30, 2023, with application number 202310798194.3 and application name “A sulfide solid electrolyte, its preparation method and application”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of lithium-ion batteries, and in particular to a sulfide solid electrolyte and its preparation method and application. Background Art

[0003] Lithium-ion batteries, due to their high energy density, high operating voltage, and long lifespan, are widely used in various portable electronic products and new energy vehicles. However, the liquid electrolytes used in traditional lithium-ion batteries are extremely unstable and prone to combustion and explosion in the event of high temperatures, short circuits, or physical collisions, posing a significant safety hazard. In contrast, the solid electrolytes used in solid-state lithium-ion batteries fundamentally address the safety issues of liquid lithium-ion batteries and can also be used in extreme conditions such as high and low temperatures.

[0004] The solid electrolytes currently under extensive research include oxide solid electrolytes and sulfide solid electrolytes. Oxide solid electrolytes offer high oxidation potentials and good stability, but they generally suffer from low ionic conductivity, high rigidity, and poor ductility. Sulfide solid electrolytes, on the other hand, have high ionic conductivity and excellent mechanical properties due to the low electronegativity of sulfur ions, which bind cations more readily. Furthermore, their large radius facilitates lithium ion migration, facilitating the migration of lithium ions. However, sulfide solid electrolytes are unstable in air and readily undergo irreversible side reactions with moisture, oxygen, and carbon dioxide in the air, producing toxic hydrogen sulfide gas. This can cause the sulfide solid electrolyte structure to collapse, reduce ionic conductivity, and compromise the battery's long-cycle performance, severely limiting their application in all-solid-state lithium batteries. Therefore, there is a need to develop a sulfide solid electrolyte with excellent air stability.

[0005] Summary of the Invention

[0006] In view of the above-mentioned defects in the prior art, the present application provides a sulfide solid electrolyte with good ionic conductivity and good stability in air.

[0007] The present application provides a method for preparing a sulfide solid electrolyte. The preparation method is simple, has low operating costs, can promote the formation of Sb-S bonding and PO bonding, and improve its air stability and ionic conductivity.

[0008] The present application also provides an all-solid-state lithium-ion battery comprising the above-mentioned sulfide solid electrolyte. The all-solid-state lithium-ion battery has good cycle performance and rate performance.

[0009] The present application provides a sulfide solid electrolyte having a chemical composition of Formula 1, wherein the percentage of Sb-S bonds in the total bonds formed by Sb is not less than 98%,

[0010] Li a Sb b P c S d O e Cl f Formula 1

[0011] In formula 1, 4.5≤a≤6.5, 0.02≤b≤0.9, 0.01≤e≤0.06, 0.9≤f≤1.6, b+c=1, d+e=5;

[0012] In the X-ray diffraction pattern of the sulfide solid electrolyte, the intensities of the diffraction peaks at 2θ of 29.8±0.25°, 33.33±0.25°, and 31.45±0.25° are respectively I a , I b , I c , and I c / I a 18~26%, I c / I b It is 25-36%.

[0013] Furthermore, the room temperature ionic conductivity of the sulfide solid electrolyte is not less than 7.5 mS / cm.

[0014] Furthermore, the ionic conductivity retention rate of the sulfide solid electrolyte is not less than 70%.

[0015] Furthermore, the sulfide solid electrolyte is prepared according to a method comprising the following steps:

[0016] Sb2S5, a P source, and an O source are mixed and ground once, and then a Li source and a Cl source are added and ground twice to obtain an intermediate phase. The intermediate phase is sintered to obtain a sulfide solid electrolyte.

[0017] The present application also provides a method for preparing a sulfide solid electrolyte, comprising the following steps:

[0018] (1) Sb2S5, P source and O source are mixed and ground once, and then Li source and Cl source are added and ground again to obtain an intermediate phase;

[0019] (2) The intermediate phase is sintered to obtain a sulfide solid electrolyte.

[0020] Furthermore, in step (1), the P source includes at least one of P2O5 and P2S5, the O source includes at least one of P2O5 and Li2O, the Li source includes at least one of Li2O, Li2S and LiCl, and the Cl source includes LiCl.

[0021] Furthermore, in step (1), the primary grinding speed is 350-550 r / min, and the primary grinding time is 0.5-2 h.

[0022] Furthermore, in step (1), the secondary grinding speed is 350-550 r / min, and the secondary grinding time is 3-5 h.

[0023] Furthermore, in step (2), the sintering temperature is 530-580° C., and the sintering time is 4-6 hours.

[0024] The present application also provides an all-solid-state lithium-ion battery, comprising the sulfide solid electrolyte according to any one of the above claims.

[0025] The sulfide solid electrolyte of the present application has stable Sb-S bonding and PO bonding, wherein the percentage of Sb-S bonding in the total bonding formed by Sb is not less than 98%. Since there are a large number of stable Sb-S bonds in the sulfide solid electrolyte, when there is moisture in the air, the O in the water molecules is not easy to combine with the Sb in the Sb-S bonding to form an Sb-O bond, making it difficult for S to be lost, thereby improving air stability. At the same time, the sulfide solid electrolyte has good air stability and good ionic conductivity, which may also be because in the X-ray diffraction pattern of the sulfide solid electrolyte, the intensities of the diffraction peaks at 2θ of 29.8±0.25°, 33.33±0.25°, and 31.45±0.25° are respectively 1 a , I b , I c , I c / I a 18~26%, I c / I b The content of the sulfur element in the sulfide solid electrolyte is 25-36%, which makes the S element in the sulfide solid electrolyte more stable and not easily replaced by O in water molecules, thereby improving its stability in the air. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is an XPS graph of the sulfide solid electrolyte of Example 4 of the present application;

[0027] FIG2 is a Raman spectrum of the sulfide solid electrolytes of Example 4 and Comparative Example 6 of the present application;

[0028] FIG3 is an XRD diagram of the sulfide solid electrolytes of Comparative Example 3 and Example 4 of the present application;

[0029] FIG4 is a SEM photograph of the sulfide solid electrolyte of Example 1 of the present application;

[0030] FIG5 is a SEM photograph of the sulfide solid electrolyte of Example 4 of the present application;

[0031] FIG6 is a curve showing the change in H2S gas concentration after the sulfide solid electrolytes of Example 4 and Comparative Example 1 of the present application were exposed to a dew point of -50°C in a glove box for 1 hour. DETAILED DESCRIPTION

[0032] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0033] In a first aspect, the present application provides a sulfide solid electrolyte having a chemical composition of Formula 1, wherein the percentage of Sb-S bonds in the total bonds formed by Sb is not less than 98%,

[0034] Li a Sb b P c S d O e Cl f Formula 1

[0035] In formula 1, 4.5≤a≤6.5, 0.02≤b≤0.9, 0.01≤e≤0.06, 0.9≤f≤1.6, b+c=1, d+e=5;

[0036] In the X-ray diffraction pattern of the sulfide solid electrolyte, the intensities of the diffraction peaks at 2θ of 29.8±0.25°, 33.33±0.25°, and 31.45±0.25° are I a , I b , I c , and I c / I a 18~26%, I c / I b It is 25-36%.

[0037] The present application does not impose any particular limitation on the particle size of the sulfide solid electrolyte, and the sulfide solid electrolyte can be of any size.

[0038] The sulfide solid electrolyte of the present application is doped with Sb and O elements. According to the theory of hard and soft acids and bases, the soft acid Sb is more likely to combine with the soft base S to form a more stable Sb-S bond, and O is more inclined to combine with P to form a PO bond, wherein the percentage of Sb-S bond to the total bond formed by Sb is greater than 98%. When there is moisture in the air, since the sulfide solid electrolyte contains a large amount of stable Sb-S bonds, and the S in the Sb-S bond is not easily replaced by O in the moisture, the formation of Sb-O bonds and the byproduct H2S gas is effectively avoided, causing the collapse of the crystal structure, thereby improving the crystal structure stability of the sulfide solid electrolyte in the air environment. At the same time, the high air stability and high ionic conductivity of the sulfide electrolyte may also be due to the fact that in the X-ray diffraction pattern of the sulfide solid electrolyte, the intensities of the diffraction peaks at 2θ of 29.8±0.25°, 33.33±0.25°, and 31.45±0.25° are 1 a , I b , I c , I c / I a 18~26%, I c / I b The S element in the Sb-S bond is 25-36%, so that the S element in the Sb-S bond exists stably in the crystal lattice of the sulfide solid electrolyte and is not easily replaced by O in water, thereby effectively improving the stability of the crystal structure of the sulfide solid electrolyte, thereby improving its air stability and ionic conductivity.

[0039] In addition, due to the large atomic radius and low valence of the doping element Sb, the unit cell volume is expanded and the Li + Solubility, reducing Li + motion activation energy, and thus can also increase ionic conductivity.

[0040] In one specific embodiment, the room temperature ionic conductivity of the sulfide solid electrolyte is no less than 7.5 mS / cm. Room temperature ionic conductivity refers to ionic conductivity at 23-27°C. Specifically, by controlling the grinding time, grinding speed, sintering time, and sintering temperature, the stability of the sulfur element is further improved, so that the sulfide solid electrolyte has the above ionic conductivity, and thus the all-solid-state lithium-ion battery including the sulfide solid electrolyte has good charge and discharge rate performance.

[0041] In a specific embodiment, the ionic conductivity retention rate of the sulfide solid electrolyte is not less than 70%. The ionic conductivity retention rate of the sulfide solid electrolyte refers to the ionic conductivity retention rate at a temperature of 23 to 27°C and an air dew point of -48 to -52°C. Specifically, by controlling the doping molar amount of the Sb source and the O source, as well as the grinding time, grinding speed, sintering time, and sintering temperature, the stability of the S element is further improved, so that the sulfide solid electrolyte has the above-mentioned ionic conductivity retention rate, thereby making the all-solid-state lithium-ion battery including the sulfide solid electrolyte have good stability in an air environment, the ionic conductivity is maintained at a good level, and the impact on the battery cycle performance is reduced.

[0042] The present application does not limit the preparation method of the above-mentioned sulfide solid electrolyte. In a specific embodiment, the sulfide solid electrolyte is prepared by a method comprising the following process:

[0043] Sb2S5, P source and O source are mixed and ground once, and then Li source and Cl source are added and ground twice to obtain an intermediate phase, which is then sintered to obtain a sulfide solid electrolyte.

[0044] Specifically, under a protective atmosphere, Sb2S5, P source and O source are mixed and ground once, and then Li source and Cl source are added and ground again to obtain an intermediate phase; then, under a protective atmosphere, the intermediate phase is sintered to obtain a sulfide solid electrolyte.

[0045] The P source of the present application refers to the raw material providing the P element, the O source refers to the raw material providing the O element, the Li source refers to the raw material providing the Li element, and the Cl source refers to the raw material providing the Cl element. As long as it contains the target element (P, O, Li, Cl), it is within the scope of the present application, and a target element can be introduced into the reaction system by one or more raw materials. It should be noted that when the raw material includes two or more elements in the target element at the same time, the raw material can be understood as the element source of two target elements. For example, when the raw material is Li2O, it acts as a Li source and an O source at the same time.

[0046] The present application does not impose any specific restrictions on the molar ratio between Sb2S5, P source and O source, or Li source and Cl source, as long as the chemical formula of the prepared sulfide solid electrolyte satisfies Formula 1.

[0047] The above-mentioned preparation method selects Sb2S5 as the Sb source. Compared with other Sb sources, such as Sb2O5, this method not only helps to increase the percentage of Sb-S bonds and form a stable crystal structure, but also reduces the sintering temperature and ball milling speed during the preparation process, reducing energy waste. At the same time, the single grinding process can promote the formation of Sb-S bonds and PO bonds, thereby increasing the percentage of Sb-S bonds. When there is moisture in the air, due to the large number of Sb-S bonds in the prepared sulfide solid electrolyte, and the fact that the S in the Sb-S bonds is not easily replaced by O in the water, the crystal structure will not collapse due to the loss of S, and it will be more stable in the air environment, thereby improving its air stability.

[0048] A second aspect of the present application provides a method for preparing a sulfide solid electrolyte, comprising the following steps:

[0049] (1) Sb2S5, P source and O source are mixed and ground once, and then Li source and Cl source are added and ground again to obtain an intermediate phase;

[0050] (2) The intermediate phase is sintered to obtain a sulfide solid electrolyte.

[0051] Among them, the P source, O source, Li source, and Cl source are the same as those defined above and will not be repeated here.

[0052] Specifically, in step (1), Sb2S5, a P source, and an O source are mixed and ground once under a sealed and protective atmosphere, and then a Li source and a Cl source are added and ground again to obtain an intermediate phase. In this step, Sb2S5, the P source, the O source, the Li source, and the Cl source are fully mixed to promote the formation of Sb-S bonds and PO bonds.

[0053] The present application does not impose any particular limitation on the protective atmosphere. For example, argon is selected as the protective atmosphere.

[0054] In step (2), the intermediate phase is sintered under a protective atmosphere to obtain a sintered product, and the sintered product is ground and pulverized to obtain a sulfide solid electrolyte. In this step, since the intermediate phase undergoes two grinding processes and includes Sb2S5, the formation of Sb-S bonding and PO bonding is effectively promoted. Therefore, a relatively stable crystal structure can be formed during the sintering process, making the S element in the sintered product more stable. When there is moisture in the air, it is not easily replaced by O in water molecules, causing side reactions, thereby improving its air stability.

[0055] The present application does not impose any specific restrictions on the molar ratio between Sb2S5, P source and O source, or Li source and Cl source, as long as the chemical formula of the prepared sulfide solid electrolyte satisfies Formula 1.

[0056] The present application does not limit the specific sources of Sb2S5, P source, O source, Li source and Cl source, for example, they can be obtained through commercial or conventional preparation means.

[0057] The present application does not impose any particular limitation on the grinding method. For example, at least one of mechanical ball milling, high-energy ball milling, and roller milling can be used.

[0058] The present application does not impose any particular limitation on the crushing method. For example, the crushing can be performed by a crusher.

[0059] The present application does not impose any particular limitation on the protective atmosphere. For example, argon is selected as the protective atmosphere.

[0060] The preparation method of the sulfide solid electrolyte of the present application is simple, easy and has low operating costs. Moreover, through a single grinding process, the formation of Sb-S bonds is promoted and the percentage of Sb-S bonds is increased. As a result, in the prepared sulfide solid electrolyte, the S in the Sb-S bonds is not easily replaced by O in water in an air environment to generate H2S gas as a byproduct, thereby avoiding destruction of the crystal structure and making the prepared sulfide solid electrolyte have good air stability and ionic conductivity.

[0061] In a specific embodiment, the P source includes at least one of P2O5 and P2S5, the O source includes at least one of P2O5 and Li2O, the Li source includes at least one of Li2O, Li2S, and LiCl, and the Cl source includes LiCl.

[0062] In one embodiment, the primary grinding speed is 350-550 r / min and the primary grinding time is 0.5-2 h. When the primary grinding speed and the primary grinding time are within the above ranges, the formation of Sb-S bonds and PO bonds can be effectively promoted, thereby increasing the percentage of Sb-S bonds.

[0063] In one embodiment, the secondary grinding speed is 350-550 r / min and the secondary grinding time is 3-5 hours. When the secondary grinding speed and the secondary grinding time are within the above ranges, the raw materials can be mixed more evenly, which helps to fully react the mesophase during the sintering process.

[0064] In a specific embodiment, the sintering temperature is 530-580° C. and the sintering time is 4-6 hours. When the sintering temperature and sintering time are within the above ranges, a sulfide solid electrolyte with excellent electrical and mechanical properties can be obtained.

[0065] In a third aspect, the present application provides an all-solid-state lithium-ion battery comprising the sulfide solid electrolyte of the first aspect. The sulfide solid electrolyte included in the all-solid-state lithium-ion battery has good air stability and ionic conductivity, and can effectively improve battery performance.

[0066] The sulfide solid electrolyte of the present application is described in detail below through specific examples.

[0067] Example 1

[0068] The sulfide solid electrolyte of this embodiment is obtained by the following preparation method:

[0069] (1) P2S5, Sb2S5, and Li2O were mixed in a certain molar ratio, added to a sealed ball mill, and ground once at a speed of 410 r / min for 1 h. The ball mill was placed in a glove box, and the remaining molar amount of Li2S and LiCl was added for a second grinding at a speed of 410 r / min for 4 h to obtain an intermediate phase.

[0070] (2) sintering the intermediate phase at a temperature of 545° C. for 5.5 h to obtain a sintered product, which was then ground using a crusher to obtain the sulfide solid electrolyte of this embodiment;

[0071] After testing, the molecular formula of the solid electrolyte is Li6Sb 0.0444 P 0.9556 S 1.9722 O 0.0278 Cl, and the size was found to be 20 μm by SEM, as shown in FIG4 .

[0072] Example 2

[0073] The sulfide solid electrolyte of this embodiment is obtained by the following preparation method:

[0074] (1) Li2O, Sb2S5, Li2S and a portion of the molar amount of P2S5 were mixed in a certain molar ratio, added to a sealed ball mill, and ground once at a speed of 410 r / min for 1 h. The ball mill was placed in a glove box, and the remaining molar amount of P2S5 and LiCl were added and ground again at a speed of 410 r / min for 4 h to obtain an intermediate phase.

[0075] (2) sintering the intermediate phase at a temperature of 545° C. for 5.5 h to obtain a sintered product, which was then ground using a crusher to obtain the sulfide solid electrolyte of this embodiment;

[0076] After testing, the molecular formula of the solid electrolyte is Li6Sb 0.0444 P 0.9556 S 1.9722 O 0.0278 Cl.

[0077] Example 3

[0078] The sulfide solid electrolyte of this embodiment is obtained by the following preparation method:

[0079] (1) P2S5, Sb2S5, and Li2O were mixed in a certain molar ratio, added to a sealed ball mill, and ground once at a speed of 430 r / min for 1.5 h. The ball mill was placed in a glove box, and the remaining molar amount of Li2S and LiCl was added for a second grinding at a speed of 430 r / min for 4.5 h to obtain an intermediate phase.

[0080] (2) sintering the intermediate phase at a temperature of 550° C. for 5 h to obtain a sintered product, which was then ground using a crusher to obtain the sulfide solid electrolyte of this embodiment;

[0081] After testing, the molecular formula of the solid electrolyte is Li6Sb 0.0667 P 0.9333 S 4.9583 O 0.0417 Cl.

[0082] Example 4

[0083] The sulfide solid electrolyte of this embodiment is obtained by the following preparation method:

[0084] (1) Li2S, Sb2S5, Li2O and a portion of the molar amount of P2S5 were mixed in a certain molar ratio, added to a ball mill and sealed, and ground once at a speed of 410 r / min for 1 h. The ball mill was placed in a glove box, and the remaining molar amount of P2S5 and LiCl were added and ground again at a speed of 410 r / min for 4 h to obtain an intermediate phase.

[0085] (2) sintering the intermediate phase at a temperature of 545° C. for 5.5 h to obtain a sintered product, which was then ground using a crusher to obtain the sulfide solid electrolyte of this embodiment;

[0086] After testing, the molecular formula of the solid electrolyte is Li6Sb 0.0667 P 0.9333 S 4.9583 O 0.0417Cl, and the size was found to be 15 μm by SEM, as shown in Figure 5.

[0087] Example 5

[0088] (1) Li2S, Sb2S5, P2O5 and a partial molar amount of P2S5 were mixed in a certain molar ratio, added to a ball mill and sealed, and ground once at a speed of 375 r / min for 2 h. The ball mill was placed in a glove box, and the remaining molar amount of P2S5 and LiCl were added and ground again at a speed of 550 r / min for 3 h to obtain an intermediate phase.

[0089] (2) sintering the intermediate phase at a temperature of 530° C. for 6 h to obtain a sintered product, which was then ground using a crusher to obtain the sulfide solid electrolyte of this embodiment;

[0090] After testing, the molecular formula of the solid electrolyte is Li6Sb 0.0333 P 0.9671 S 4.9733 O 0.0278 Cl.

[0091] Example 6

[0092] (1) Li2S, Sb2S5, Li2O and a portion of the molar amount of P2S5 were mixed in a certain molar ratio, added to a ball mill and sealed, and ground once at a speed of 380 r / min for 2 h. The ball mill was placed in a glove box, and the remaining molar amount of P2S5, PCl3, and LiCl were added for a second grinding at a speed of 500 r / min for 3.5 h to obtain an intermediate phase.

[0093] (2) sintering the intermediate phase at a temperature of 560° C. for 5 h to obtain a sintered product, which was then ground using a crusher to obtain the sulfide solid electrolyte of this embodiment;

[0094] After testing, the molecular formula of the solid electrolyte is Li 5.5056 Sb 0.0333 P 0.9667 S 4.975 O 0.0278 Cl.

[0095] Example 7

[0096] The sulfide solid electrolyte of this embodiment is obtained by the following preparation method:

[0097] (1) P2S5, Sb2S5, and Li2O were mixed in a certain molar ratio, added to a sealed ball mill, and ground once at a speed of 550 r / min for 0.5 h. The ball mill was placed in a glove box, and the remaining molar amount of Li2S and LiCl was added for a second grinding at a speed of 400 r / min for 5 h to obtain an intermediate phase.

[0098] (2) sintering the intermediate phase at a temperature of 580° C. for 4 h to obtain a sintered product, which was then ground using a crusher to obtain the sulfide solid electrolyte of this embodiment;

[0099] After testing, the molecular formula of the solid electrolyte is Li6Sb 0.0444 P 0.9556 S 4.9722 O 0.0278 Cl.

[0100] Example 8

[0101] The sulfide solid electrolyte of this embodiment is obtained by the following preparation method:

[0102] (1) P2S5, Sb2S5, and Li2O were mixed in a certain molar ratio, added to a sealed ball mill, and ground once at a speed of 430 r / min for 1 h. The ball mill was placed in a glove box, and the remaining molar amount of Li2S and LiCl was added for a second grinding at a speed of 410 r / min for 5 h to obtain an intermediate phase.

[0103] (2) sintering the intermediate phase at a temperature of 520° C. for 5 h to obtain a sintered product, which was then ground using a crusher to obtain the sulfide solid electrolyte of this embodiment;

[0104] After testing, the molecular formula of the solid electrolyte is Li6Sb 0.0444 P 0.9556 S 4.9722 O 0.0278 Cl.

[0105] Example 9

[0106] The sulfide solid electrolyte of this embodiment is obtained by the following preparation method:

[0107] (1) Li2S, Sb2S5, Li2O and a partial molar amount of P2S5 were mixed in a certain molar ratio, added to a ball mill and sealed, and ground once at a speed of 430 r / min for 1 h. The ball mill was placed in a glove box, and the remaining molar amount of P2S5 and LiCl were added and ground again at a speed of 410 r / min for 5 h to obtain an intermediate phase.

[0108] (2) sintering the intermediate phase at a temperature of 520° C. for 5 h to obtain a sintered product, which was then ground using a crusher to obtain the sulfide solid electrolyte of this embodiment;

[0109] After testing, the molecular formula of the solid electrolyte is Li6Sb 0.0444 P 0.9556 S 4.9722 O 0.0278 Cl.

[0110] Comparative Example 1

[0111] The sulfide solid electrolyte of this comparative example is obtained by the following preparation method:

[0112] (1) Li2S, P2S5, LiCl, and Sb2O5 were mixed in a certain molar ratio, added to a sealed ball mill, and ground at a speed of 410 r / min for 4 h to obtain an intermediate phase;

[0113] (2) sintering the intermediate phase at a temperature of 560° C. for 5 h to obtain a sintered product, which was then ground using a crusher to obtain the sulfide solid electrolyte of this embodiment;

[0114] After testing, the molecular formula of the solid electrolyte is Li6Sb 0.05 P 0.95 S 4.875 O 0.125 Cl.

[0115] Comparative Example 2

[0116] The sulfide solid electrolyte of this comparative example is obtained by the following preparation method:

[0117] (1) Li2S, P2S5, P2O5, Sb2S5, and LiI were weighed in a certain molar ratio and poured into a ball mill at 600 rpm for 24 h to obtain the intermediate phase;

[0118] (2) The intermediate phase was sintered at 490°C for 4 h under vacuum to obtain the sulfide solid electrolyte of this comparative example. After testing, the molecular formula of the solid electrolyte was Li6Sb0.8 P 0.2 S 4.5 O 0.5 I.

[0119] Comparative Example 3

[0120] The preparation method of the sulfide solid electrolyte of this comparative example is basically the same as that of Example 4, except that Sb2S3 is used instead of Sb2S5 to obtain the sulfide solid electrolyte of this comparative example. After testing, the molecular formula of the solid electrolyte is Li6Sb 0.0667 P 0.933 S 4.9055 O 0.0278 Cl.

[0121] Comparative Example 4

[0122] The preparation method of the sulfide solid electrolyte of this comparative example is basically the same as that of Example 1, except that Sb2S5, P source, O source, Li source and Cl source are mixed and ground at a grinding speed of 410 r / min and a grinding time of 5 h to obtain the sulfide solid electrolyte of this comparative example. After testing, the molecular formula of the solid electrolyte is Li6Sb 0.0444 P 0.9556 S 1.9722 O 0.0278 Cl.

[0123] Comparative Example 5

[0124] The preparation method of the sulfide solid electrolyte of this comparative example is basically the same as that of Example 3, except that Sb2O5 is used to replace 10wt% of Sb2S5 in Example 3 to obtain the sulfide solid electrolyte of this comparative example;

[0125] After testing, the molecular formula of the solid electrolyte is Li6Sb 0.0667 P 0.9333 S 4.9583 O 0.0417 Cl.

[0126] Comparative Example 6

[0127] The preparation method of the sulfide solid electrolyte of this comparative example is basically the same as that of Example 3, except that the addition amounts of Sb and O are changed to obtain the sulfide solid electrolyte of this comparative example. After testing, the molecular composition of the solid electrolyte is Li6Sb 0.02 P 0.99 S 4.99 O 0.01 Cl.

[0128] Test example

[0129] 1. XPS and XRD tests were performed on the above examples and comparative examples, and Raman detection was performed on Example 4 and Comparative Example 6.

[0130] The percentage of Sb-S bonds in the total bonds formed by Sb can be obtained from the XPS graph. Specific data are shown in Table 1. FIG1 is an XPS graph of the sulfide solid electrolyte of Example 4.

[0131] From the Raman spectrum, it can be concluded that the Raman peak at 335.375 is caused by groups containing Sb and S elements, proving that the sulfide solid electrolyte was successfully synthesized, as shown in Figure 2.

[0132] From the XRD pattern, we can get the diffraction peak intensities I at 2θ of 29.8±0.25°, 31.45±0.25°, and 33.33±0.25°. a , I b , I c Specific data are shown in Table 1. FIG3 is the XRD diagram of the sulfide solid electrolytes of Comparative Example 3 and Example 4:

[0133] Table 1

[0134] As shown in Table 1, the percentage of Sb-S bonding in Examples 1-9 to the total bonding formed by Sb is greater than 98%, and I c / I a 18~26%, I c / I b It is 25-36%.

[0135] 2. The sulfide solid electrolytes prepared in the above examples and comparative examples were tested for ionic conductivity and air stability:

[0136] (1) Ionic conductivity

[0137] 0.23g of sulfide solid electrolyte material was weighed and poured into the battery compartment. The pressure was maintained at 3T for 10 minutes. The electrolyte layer thickness was measured, and blocking electrodes were placed on both sides of the electrolyte layer to complete the impedance test mold assembly. The assembled impedance mold was left at 25°C for 2 hours before the impedance test was performed. The ionic conductivity of the sulfide solid electrolyte before storage was obtained. Specific data are shown in Table 2.

[0138] A simple 110L glove box was left at a fixed dew point for 4 hours to remove any inherent moisture. The impedance mold, which had rested for 2 hours, was then placed in the glove box. A fan was used to displace the air inside the glove box for 0.5 hours, maintaining a dew point of -50°C. The glove box was then left standing for 1 hour with the side door closed. The ambient temperature was maintained at 25°C. Impedance testing was then performed to determine the ionic conductivity of the sulfide solid electrolyte after this period. Specific data are shown in Table 2.

[0139] (2) Air stability

[0140] 2-1: Air stability is characterized by the ionic conductivity retention of the sulfide solid electrolyte before and after storage. The ionic conductivity retention is calculated by formula 2:

[0141] Ionic conductivity retention rate = σ1 / σ2 Formula 2

[0142] In formula 2:

[0143] σ1 is the ionic conductivity of the sulfide solid electrolyte before storage;

[0144] σ2 is the ionic conductivity of the sulfide solid electrolyte after storage.

[0145] The test results are shown in Table 2.

[0146] 2-2: According to the following method, the sulfide solid electrolytes prepared in Example 4 and Comparative Example 1 were subjected to H2S gas testing.

[0147] A simple 110L glove box was set to a fixed dew point and left for 4 hours to remove any inherent moisture. The sulfide solid electrolyte and H2S gas analyzer were placed inside the glove box. A fan was used to perform gas displacement for a fixed 0.5-hour period, maintaining the dew point at -50°C. The glove box door was closed, and 2g of sample powder was spread evenly in a 4.5cm diameter container. The analyzer was then turned on and allowed to stand for 1 hour to determine the H2S gas concentration. The test results are shown in Figure 6.

[0148] As shown in FIG6 , the sulfide solid electrolyte of Comparative Example 1 generates H 2 S gas at about 1100 s, while the sulfide solid electrolyte of Example 4 generates H 2 S gas at about 1800 s. This shows that the sulfide solid electrolyte of the present application has good air stability.

[0149] Table 2

[0150] As can be seen from Table 2, through Examples 1-9 and Comparative Examples 1-6, the ionic conductivity retention rate of the sulfide solid electrolyte of the present application can reach 81.11%, and has good ionic conductivity, while the ionic conductivity retention rate of Comparative Examples 1-6 can only reach a maximum of 71.60%, and the ionic conductivity is relatively low.

[0151] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A sulfide solid electrolyte, wherein: Having a chemical composition of formula 1, the percentage of Sb-S bonding to the total bonding formed by Sb is not less than 98%, Li a Sb b P c S d O e Cl f Formula 1 In formula 1, 4.5≤a≤6.5, 0.02≤b≤0.9, 0.01≤e≤0.06, 0.9≤f≤1.6, b+c=1, d+e=5; In the X-ray diffraction pattern of the sulfide solid electrolyte, the intensities of the diffraction peaks at 2θ of 29.8±0.25°, 33.33±0.25°, and 31.45±0.25° are respectively I a , I b , I c , and I c / I a 18~26%, I c / I b It is 25 to 36%.

2. The sulfide solid electrolyte according to claim 1, wherein The room temperature ionic conductivity of the sulfide solid electrolyte is not less than 7.5 mS / cm.

3. The sulfide solid electrolyte according to claim 1, wherein The ionic conductivity retention rate of the sulfide solid electrolyte is not less than 70%.

4. The sulfide solid electrolyte according to any one of claims 1 to 3, wherein The sulfide solid electrolyte is prepared according to a method comprising the following steps: Sb2S5, a P source and an O source are mixed and ground once, and then a Li source and a Cl source are added and ground twice to obtain an intermediate phase, and the intermediate phase is sintered to obtain a sulfide solid electrolyte.

5. A method for preparing the sulfide solid electrolyte according to any one of claims 1 to 4, wherein: The steps include: (1) Sb2S5, P source and O source are mixed and ground once, and then Li source and Cl source are added and ground again to obtain an intermediate phase; (2) The intermediate phase is sintered to obtain a sulfide solid electrolyte.

6. The method for preparing a sulfide solid electrolyte according to claim 5, wherein: In step (1), the P source includes at least one of P2O5 and P2S5, the O source includes at least one of P2O5 and Li2O, the Li source includes at least one of Li2O, Li2S and LiCl, and the Cl source includes LiCl.

7. The method for preparing a sulfide solid electrolyte according to claim 5, wherein: In step (1), the primary grinding speed is 350-550 r / min, and the primary grinding time is 0.5-2 h.

8. The method for preparing a sulfide solid electrolyte according to claim 5, wherein: In step (1), the secondary grinding rotation speed is 350-550 r / min, and the secondary grinding time is 3-5 h.

9. The method for preparing a sulfide solid electrolyte according to claim 5, wherein: The sintering temperature is 530-580°C, and the sintering time is 4-6 hours.

10. An all-solid-state lithium-ion battery, wherein: Comprising the sulfide solid electrolyte according to any one of claims 1 to 4.

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