Transition metal regulated sulfide solid electrolyte, preparation method thereof and all-solid-state lithium-sulfur battery

Abstract

The invention relates to the technical field of solid-state batteries, in particular to a transition metal regulated sulfide solid-state electrolyte, a preparation method thereof and an all-solid-state lithium-sulfur battery. The general formula of the transition metal regulated sulfide solid electrolyte is Li < 6 + x > P < 1-x > M < x > S5X, and x is more than or equal to 0.01 and less than or equal to 1; m comprises at least one of V, Ti, Mo and W; and X comprises at least one of F, Cl, Br, I, BH4, CN and SCN. The transition metal regulated sulfide solid electrolyte provided by the invention has high ionic conductivity and high stability. The all-solid-state lithium-sulfur battery assembled based on the sulfide solid electrolyte regulated and controlled by the transition metal provided by the invention has excellent cycle performance and rate capability.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state batteries, and in particular to a transition metal-regulated sulfide solid electrolyte, a preparation method thereof, and an all-solid-state lithium-sulfur battery. Background Art

[0002] All-solid-state lithium batteries are considered to be one of the most promising candidates for the next generation of energy storage and are expected to address limitations in thermal safety, energy density, and possibly power density. Among various electrochemical systems, all-solid-state lithium-sulfur batteries show great potential due to their use of sulfur as the cathode, which has the characteristics of high energy density, low cost, and environmental friendliness. Traditional liquid lithium-sulfur batteries have serious capacity decay problems due to the shuttling effect of polysulfides. The use of inorganic solid electrolytes instead of liquid electrolytes has two significant advantages: eliminating the stubborn problem of polysulfide dissolution and shuttling, and being able to realize a solid-solid reaction mechanism, which is theoretically decoupled from the volume of the electrolyte, and is expected to provide high energy. Among different solid electrolytes, sulfide electrolytes: Li3PS4, Li7P3S 11 ,Li6PS5Cl, etc., have attracted widespread attention due to their high ionic conductivity and good mechanical ductility.

[0003] However, when used as S cathode solid electrolytes, they face serious electrochemical stability issues, mainly manifested in the low stability at 1.7-2.0 V vs Li + / Li 0 Although sulfide solid electrolytes are used as solid electrolytes for layered metal oxide cathodes, they are usually more than 3.5V vs Li + / Li 0 However, due to the poor electronic and ionic conductivity of sulfur active materials, a large amount of carbon conductive additives and solid cathode electrolytes are inevitably required in the S cathode, which may lead to severe decomposition of sulfide electrolytes. Crucially, these decomposition reactions are persistent, causing the decomposition products to accumulate at the interface between the electrolyte and the active material, forming an interfacial layer that hinders electron / ion transport, thereby reducing the charge transfer efficiency. Therefore, improving the stability of the S cathode solid electrolyte is crucial to achieving stable and high-rate all-solid-state lithium-sulfur batteries.

[0004] Precise control of the operating voltage window has been shown to be effective in mitigating the reduction decomposition reaction of the positive electrode solid electrolyte, for example by increasing the lower voltage limit of the battery. However, the oxidative decomposition problem remains unsolved because the S active material reaction (S 2- →S 0) overlaps with the oxidation potential of the sulfide solid electrolyte, leading to inevitable oxidative degradation. Another approach is to reduce the electrical contact between the solid cathode electrolyte and the carbon additive to prevent the decomposition of the solid cathode electrolyte, such as by coating the carbon / sulfur with lithium phosphate oxide or using a non-conductive sulfur carrier. However, these measures will seriously affect the positive electrode solid electrolyte and the ion / electron transport channels between the carbon and the active material, thereby affecting the capacity of the S active material. Although the strategies through electrode structure design have certain improvement effects, they do not solve the intrinsic interfacial redox behavior of the positive electrode solid electrolyte of the all-solid-state lithium-sulfur battery, and solving this problem is crucial to building an all-solid-state lithium-sulfur battery with excellent electrochemical performance.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The first object of the present invention is to provide a transition metal-regulated sulfide solid electrolyte having a specific chemical composition, high ionic conductivity and excellent electrochemical reversibility.

[0007] The second object of the present invention is to provide a method for preparing a transition metal-regulated sulfide solid electrolyte.

[0008] A third object of the present invention is to provide a structural component.

[0009] A fourth object of the present invention is to provide an all-solid-state lithium-sulfur battery.

[0010] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0011] The present invention first provides a transition metal-regulated sulfide solid electrolyte, wherein the general formula of the sulfide solid electrolyte is Li 6+x P 1-x M x S5X, wherein 0.01≤x≤1; M includes at least one of V, Ti, Mo and W; and X includes at least one of F, Cl, Br, I, BH4, CN and SCN.

[0012] Furthermore, the phase state of the transition metal-regulated sulfide solid electrolyte is a glass phase, a glass-ceramic phase or a ceramic phase.

[0013] Furthermore, the ionic conductivity of the transition metal-regulated sulfide solid electrolyte at 25° C. is ≥0.2 mS / cm.

[0014] The present invention further provides a method for preparing the transition metal-regulated sulfide solid electrolyte, comprising the following steps:

[0015] (1) mixing a lithium source, a phosphorus source, an M source, a sulfur source and an X source in a mortar; wherein M comprises at least one of V, Ti, Mo and W; optionally, an X source is added during the mixing process, wherein X comprises at least one of F, Cl, Br, I, BH4, CN and SCN.

[0016] (2) ball-milling the mixed raw material obtained in step 1 to obtain the transition metal-regulated sulfide solid electrolyte.

[0017] Furthermore, the lithium source includes at least one of Li2S, LiF, LiBr, LiI, LiBH4, LiCN and LiSCN.

[0018] Furthermore, the phosphorus source includes P2S5.

[0019] Furthermore, the M source includes at least one of VS2, TiS2, MoS2 and WS2.

[0020] Furthermore, the sulfur source includes at least one of P2S5 and Li2S.

[0021] Furthermore, the X source includes a X-containing lithium salt.

[0022] Furthermore, the mixing method includes grinding, and the grinding time is 10 to 30 minutes.

[0023] Furthermore, the ball milling specifically includes: ball milling for 15 to 30 hours at a rotation speed of 500 to 600 rpm.

[0024] Furthermore, the ball milling is performed under vacuum conditions or inert atmosphere.

[0025] The present invention further provides a structural component, comprising a positive electrode sheet, a negative electrode sheet and a solid electrolyte layer, wherein the positive electrode sheet contains the transition metal-regulated sulfide solid electrolyte.

[0026] Furthermore, the positive electrode sheet is mainly composed of a positive electrode material and the transition metal-regulated sulfide solid electrolyte.

[0027] Furthermore, the negative electrode sheet includes at least one of Li, Li-Si alloy, Li-In alloy, and Li-C material.

[0028] Furthermore, the solid electrolyte layer is mainly composed of at least one electrolyte selected from the group consisting of a sulfide electrolyte, a halide electrolyte, an oxide electrolyte, a polymer electrolyte, a sulfide-polymer composite electrolyte, a halide-polymer composite electrolyte and an oxide-polymer composite electrolyte.

[0029] The present invention also provides an all-solid-state lithium-sulfur battery, comprising the transition metal-regulated sulfide solid electrolyte, or the structural component.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The transition metal sulfide solid electrolyte provided by the present invention regulates the reversibility of the decomposition reaction of the sulfide electrolyte by controlling the doping ratio of the transition metal M, preserves the migration path of lithium ions, alleviates the accumulation of decomposition products, improves the interface stability between the S active material and the solid electrolyte, and reduces the interface impedance.

[0032] (2) The preparation method of the transition metal-regulated sulfide solid electrolyte provided by the present invention has a simple process, easy-to-control process conditions, and is suitable for large-scale production.

[0033] (3) The transition metal-regulated sulfide electrolyte prepared by the present invention can be used as a sulfur positive electrode electrolyte to comprehensively improve the electrochemical performance of the sulfur positive electrode. At the same time, it can be used with other sulfide electrolytes as the electrolyte layer and lithium metal / alloy as the negative electrode to construct an all-solid-state lithium-sulfur battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 The X-ray powder diffraction patterns of the transition metal-regulated sulfide solid electrolytes prepared in Examples 1 to 5 provided by the present invention;

[0036] Figure 2 A mapping diagram of the transition metal-regulated sulfide solid electrolyte prepared in Example 2 provided by the present invention;

[0037] Figure 3 This is a SEM image of the transition metal-regulated sulfide solid electrolyte prepared in Example 2 provided by the present invention;

[0038] Figure 4 This is a SEM image of the transition metal-regulated sulfide solid electrolyte prepared in Example 3 provided by the present invention;

[0039] Figure 5 The sulfide solid electrolyte regulated by the transition metal prepared in Example 2 provided by the present invention 7 Li solid-state NMR spectrum;

[0040] Figure 6 The cycle performance diagram of the full battery assembled in Example 2 provided by the present invention;

[0041] Figure 7 A Nyquist curve diagram of the Ti|solid electrolyte|Ti battery assembled in Example 1 provided by the present invention at 25° C.;

[0042] Figure 8 A Nyquist plot of the Ti|solid electrolyte|Ti battery assembled in Example 2 provided by the present invention at 25° C.;

[0043] Fig. 9 A Nyquist curve diagram at 25° C. of the Ti|solid electrolyte|Ti battery assembled in Example 3 provided by the present invention;

[0044] Fig.10 A Nyquist curve diagram at 25° C. of the Ti|solid electrolyte|Ti battery assembled in Example 4 provided by the present invention;

[0045] Fig.11 A Nyquist curve diagram of the Ti|solid electrolyte|Ti battery assembled in Example 5 provided by the present invention at 25° C.;

[0046] Fig.12 The embodiment 2 provided by the present invention is a sulfur positive electrode electrolyte, Li 5.5 PS 4.5 Cl 1.5 The charge and discharge curves and cycle performance diagrams of all-solid-state lithium-sulfur batteries assembled with electrolyte separator layers;

[0047] Fig.13 The embodiment 2 provided by the present invention is a cycle performance diagram of an all-solid-state lithium-sulfur battery assembled with a sulfur positive electrode electrolyte and Li6PS5I as an electrolyte separator layer;

[0048] Fig.14 Example 4 provided by the present invention is a cycle performance diagram of an all-solid-state lithium-sulfur battery assembled with a sulfur positive electrode electrolyte and Li6PS5Cl as an electrolyte separator layer;

[0049] Fig.15 Comparative Example 1: Li6PS5I as sulfur cathode electrolyte, Li 5.5 PS 4.5 Cl 1.5 The charge and discharge curve and cycle performance diagram of the all-solid-state lithium-sulfur battery assembled with the electrolyte separator layer. DETAILED DESCRIPTION

[0050] The present invention will be further described below in conjunction with embodiments.

[0051] Example 1

[0052] The method for preparing the transition metal-regulated sulfide solid electrolyte provided in this embodiment comprises the following steps:

[0053] (1) Li2S, P2S5, WS2, and LiI were weighed in a molar ratio of 51:9:2:20, and the weighed raw materials were placed in an agate mortar and ground to ensure that the raw materials were evenly mixed. The grinding time was 20 min to obtain a precursor. All operations were carried out in a glove box filled with argon atmosphere.

[0054] (2) The precursor obtained in step (1) is placed in a ball mill, and zirconium dioxide ball milling beads are added at the same time, wherein the ball-to-material ratio is 40:1, and the ball mill is sealed.

[0055] (3) Place the ball milling jar from step (2) into a ball mill for ball milling. Set the speed to 500 rpm and the time to 15 h. To prevent powder agglomeration and the generation of a large amount of heat that affects the product during the ball milling process, each ball milling is performed for 30 min and then stopped for 5 min.

[0056] (4) The powder prepared by ball milling in step (3) is transferred from the ball mill to a mortar for further grinding to finally obtain the target sulfide solid electrolyte: Li 6.1 P 0.9 W 0.1 S5I. That is, x = 0.1, M = WS2, X = LiI.

[0057] Example 2

[0058] The preparation method of the transition metal-regulated sulfide solid electrolyte provided in this embodiment is basically the same as that in Example 1, except that: in step (1), Li2S, P2S5, WS2, and LiI are weighed according to a molar ratio of 13:2:1:5.

[0059] The transition metal-regulated sulfide solid electrolyte prepared in this embodiment is: Li 62 P 08 W 02 S5I, that is, x=0.2, M=WS2, X=LiI.

[0060] Example 3

[0061] The preparation method of the transition metal-regulated sulfide solid electrolyte provided in this embodiment is basically the same as that in Example 1, except that: in step (1), Li2S, P2S5, MoS2, and LiI are weighed according to a molar ratio of 51:9:2:20.

[0062] The transition metal-regulated sulfide solid electrolyte prepared in this embodiment is: Li 6.1P 0.9 Mo 0.1 S5I, that is, x=0.1, M=MoS2, X=LiI.

[0063] Example 4

[0064] The preparation method of the transition metal-regulated sulfide solid electrolyte provided in this embodiment is basically the same as that in Example 1, except that: in step (1), Li2S, P2S5, MoS2, and LiCl are weighed according to a molar ratio of 13:2:1:5.

[0065] The transition metal-regulated sulfide solid electrolyte prepared in this embodiment is: Li 6.2 P 0.8 Mo 0.2 S5I, that is, x=0.2, M=MoS2, X=LiI.

[0066] Example 5

[0067] The preparation method of the transition metal-regulated sulfide solid electrolyte provided in this embodiment is basically the same as that in Example 1, except that: in step (1), Li2S, P2S5, WS2, and LiCl are weighed according to a molar ratio of 13:2:1:5.

[0068] The transition metal-regulated sulfide solid electrolyte prepared in this embodiment is: Li 6.2 P 0.8 W 0.2 S5Cl, that is, x=0.2, M=WS2, X=LiCl.

[0069] Structural analysis:

[0070] The transition metal-regulated sulfide solid electrolytes prepared in Examples 1 to 5 were subjected to X-ray diffraction tests: the samples were sealed with a Kapton film to prevent exposure to air and decomposition of the samples, and data were collected using a Rigaku MiniFlex600 X-ray diffractometer (Cu K α radiation, ), the scanning range is 10°~70°, and the scanning step is 0.01°. The obtained X-ray diffraction spectrum is as follows Figure 1 As shown. Figure 1 It can be seen that, except for the crystalline phases LiI and Li2S, the main phases in Examples 1 to 4 are amorphous phases, indicating that Examples 1 to 4 are glass-ceramic phases. The main crystalline phase in Example 5 is argyrodite phase.

[0071] The transition metal-regulated sulfide solid electrolyte prepared in Example 2 was subjected to SEM-Mapping test: Hitachi Regulus 8220 device was used for SEM test, and the obtained Mapping map and SEM map were as follows: Figure 2 and Figure 3 As shown. Figure 2 It can be seen that the W element is evenly distributed inside the electrolyte particles, proving that the W element is successfully doped into the electrolyte bulk phase. Figure 3 It can be seen that the sulfide solid electrolyte material prepared in Example 2 is irregular particles with a size of about 3-5 microns. Figure 4 This is the SEM of Example 3, which is also irregular particles with a size of about 3-5 microns.

[0072] Electrochemical property analysis:

[0073] The solid electrolytes of each embodiment and the comparison group were tested for ionic conductivity: the solid electrolyte powder was placed in a PEEK sleeve with a diameter of 10 mm by cold pressing, and then two titanium rods (Ti) were placed at both ends of the PEEK sleeve, and a dense electrolyte sheet was formed by cold pressing at 370 MPa for 3 minutes. The obtained Ti|solid electrolyte|Ti battery assembly was placed in a customized stainless steel housing, and a constant pressure of about 100 MPa was applied. The electrochemical impedance spectroscopy (EIS) test was performed using a Bio-Logic SP-200 electrochemical workstation, where the Nyquist spectra of Examples 1-5 are shown as follows: Figure 7-Figure 11 The corresponding impedance value is read, and the ionic conductivity is calculated according to the formula σ=L / (R×S) (L is the thickness of the electrolyte sheet, S is the area of ​​the electrolyte sheet), and the specific results are shown in Table 1.

[0074] Table 1 Ionic conductivity results of each group (25℃)

[0075] Group Electrolyte general formula Ionic conductivity (mS / cm) Example 1 <![CDATA[Li 6.1 P 0.9 W 0.1 S5I]]> 0.76 Example 2 <![CDATA[Li 6.2 P 0.8 W 0.2 S5I]]> 1.3 Example 3 <![CDATA[Li 6.1 P 0.9 You 0.1 S5I]]> 0.38 Example 4 <![CDATA[Li 6.2 P 0.8 You 0.2 S5I]]> 0.44 Example 5 <![CDATA[Li 6.2 P 0.8 W 0.2 S5Cl]]> 0.94

[0076] As can be seen from Table 1, the doping of transition metals has no effect on the electrolyte ion conductivity. This is because the electrolyte matrix is ​​a glass phase, and the introduction of transition metals into the glass network will not hinder the ion transmission path, so the ion conductivity of the electrolyte matrix is ​​basically maintained. Figure 5 As shown, in addition to the characteristic peaks of Li2S and LiI, the 7 The Li spectrum also shows a major peak at 0.28 ppm, which is consistent with the reported amorphous Li6PS5I. After the addition of WS2, this major peak shifted to a lower chemical shift (0.15 ppm), which can be attributed to the mobile Li +The electroactive interactions between ions and the anionic framework are weakened, which helps to increase the ion transport efficiency and thus ensure ionic conductivity.

[0077] For convenience, the Li6PS5Cl electrolyte in the present invention is referred to as LPSC. 5.5 PS 4.5 Cl 1.5 , the electrolyte is referred to as LPSC 1.5 , Li6PS5I is referred to as LPSI, Li 6.2 P 0.8 W 0.2 S5I is referred to as LPW 0.2 SI, Li 6.2 P 0.8 Mo 0.2 S5I is referred to as LPM 0.2 SI.

[0078] The electrochemical stability test of Example 2 was conducted: the solid electrolyte powder was used as the active material and was mixed with the conductive carbon Super P in a mass ratio of 7:3 by ball milling to obtain the positive electrode material. The Li6PS5Cl electrolyte material was placed in a PEEK cylinder with a diameter of 10 mm, and two Ti columns were placed on both sides of the PEEK cylinder. The electrolyte sheet was pre-pressed at 150 MPa for 1 minute. Then the prepared Li 6.2 P 0.8 W 0.2 The S5I / SP positive electrode (without S active material) was cold pressed at 370 MPa for 3 minutes. Finally, indium foil and lithium foil were placed on the other side in turn, and cold pressed at 150 MPa for 1 minute to obtain the battery LiIn|LPSC|Li 6.2 P 0.8 W 0.2 S5I / SP. The test process is at 25℃, 100mAg -1 The constant current charge and discharge test was carried out at a current density of 1.5 %. The cycle performance was as follows: Figure 6 As shown. Figure 6 It can be seen that the transition metal-regulated sulfide solid electrolyte Li prepared in Example 2 6.2 P 0.8 W 0.2 S5I at 100mAg -1 It can produce 247mAh g -1 (Here Li 6.2 P 0.8 W 0.2 The first cycle specific capacity (calculated by mass of S5I). As the cycle progresses, the specific capacity increases to 317 mA h g -1 (Here Li 6.2 P0.8 W 0.2 The capacity of S5I was calculated by mass calculation, indicating that the electrolyte was completely decomposed. Then the capacity remained stable until 400 cycles, indicating that Li 6.2 P 0.8 W 0.2 S5I has good electrochemical reaction reversibility.

[0079] Fig.12 The embodiment 2 provided by the present invention is a sulfur positive electrode electrolyte, LPSC 1.5 The charge and discharge curve and cycle performance diagram of the all-solid-state lithium-sulfur battery assembled with the electrolyte separator layer and LiIn alloy as the negative electrode; Fig.13 Example 2 provided by the present invention is a cycle performance diagram of an all-solid-state lithium-sulfur battery assembled with sulfur positive electrode electrolyte, LPSI as electrolyte separator layer, and LiIn alloy as negative electrode; Fig.14 The embodiment 4 provided by the present invention is a sulfur positive electrode electrolyte, LPSC 1.5 This is the cycling performance diagram of an all-solid-state lithium-sulfur battery assembled with an electrolyte separator layer and LiIn alloy as the negative electrode. Fig.15 LPSC uses LPSI as the cathode electrolyte. 1.5 The charge and discharge curve and cycle performance diagram of an all-solid-state lithium-sulfur battery assembled with an electrolyte separator layer and LiIn alloy as the negative electrode (this is comparative example 1).

[0080] The specific preparation method of the sulfur positive electrode containing the transition metal-regulated sulfide solid electrolyte is as follows: First, prepare S / KB: weigh the sulfur element and the conductive carbon KB at a mass ratio of 70:30, grind them and place them in a quartz tube for vacuum sealing, then place them in a muffle furnace, heat them to 155°C at a heating rate of 1°C / min, and keep them warm for 5 hours. The above-mentioned S / KB powder, the transition metal-regulated sulfide solid electrolyte powder and the conductive carbon black Super P are weighed at a mass ratio of 5:4:1 and placed in a zirconia ball mill, and the mass ratio of zirconia beads to the ball-milled material is 40:1. The ball mill is packaged in an inert atmosphere, and the ball mill is placed in a planetary ball mill. The positive electrode materials are mixed evenly at a speed of 500rpm and a rotation time of 4h to obtain a sulfur positive electrode of a transition metal-regulated solid electrolyte.

[0081] The preparation method of all-solid-state lithium-sulfur battery comprises the following steps: first, in an inert atmosphere, 80 mg of solid electrolyte powder (LPSC 1.5, LPSC or LPSI) is placed in a PEEK cylinder, and the two ends are pressed at a pressure of 150MPa for 1 minute with a customized Ti rod to form a solid electrolyte diaphragm layer. Then, a sulfur positive electrode material with a certain sulfur loading is evenly spread on top of the solid electrolyte diaphragm layer and pressed at a pressure of 300MPa for 3 minutes. On the other side of the electrolyte diaphragm layer, a thin layer of indium foil (9 mm in diameter, 99.99%, 0.2 mm in thickness) and a thin lithium foil (7 mm in diameter, 0.1 mm in thickness) are attached and pressed at 100MPa for 1 minute to obtain the final batteries, which are represented as: LiIn|LPSC 1.5 |LPW 0.2 SI / SKB, LiIn|LPSI|LPW 0.2 SI / SKB and LiIn|LPSC|LPM 0.2 SI / SKB. Afterwards, the molded battery was placed in a customized stainless steel housing and tested with a pressure of 30MPa.

[0082] In Comparative Example 1, the preparation method of the sulfur cathode and the all-solid-state battery using LPSI as the electrolyte in the sulfur cathode is basically the same as the above conditions, except that the sulfide solid electrolyte powder containing transition metal regulation in the sulfur cathode is replaced by LPSI, and the material of the electrolyte diaphragm layer is LPSC 1.5 The battery is named LiIn|LPSC 1.5 |LPSI / SKB.

[0083] Battery performance test of all-solid-state lithium-sulfur battery: The above-mentioned battery was placed in an oven at 25°C and subjected to constant current charge and discharge test on a NEWARE battery testing system.

[0084] like Fig.12 The sulfur loading of the cell shown is 1.2 mg cm -2 , the battery LiIn|LPSC 1.5 |LPW 0.2 SI / SKB has a first cycle discharge capacity of 877 mA hg at 1C rate -1 (Here the mass of elemental sulfur is used for calculation). The capacity then showed a trend of decreasing first and then increasing, which was related to the decomposition reaction of the positive electrode electrolyte. Finally, the capacity stabilized at 852 mA hg -1 (Here the mass of elemental sulfur is used for calculation). Fig.15 As shown, the battery LiIn|LPSC of Comparative Example 1 1.5 |The sulfur loading of LPSI / SKB is 0.98 mg cm -2 The first cycle discharge capacity of the battery is 959mA hg -1 (Here the mass of elemental sulfur is used for calculation), but after 100 cycles the capacity is only 550 mA hg-1 By comparing the two, we can see that LPW 0.2 All-solid-state lithium-sulfur batteries with SI as the cathode electrolyte exhibit excellent cycling stability.

[0085] like Fig.13 The sulfur loading of the cell shown is 1.1 mg cm -2 , the battery LiIn|LPSI|LPW 0.2 SI / SKB shows 608mAh g at 1C rate in the first cycle -1 (Here calculated based on the mass of elemental sulfur), relative to LiIn|LPSI|LPW 0.2 The SI / SKB battery has a lower capacity because the ionic conductivity of LPSI as the electrolyte layer is lower than that of LPSC. 1.5 The low capacity will cause some polarization. However, after 100 cycles, the capacity is still 557 mAh g -1 (here calculated by the mass of elemental sulfur), also showed excellent stability. The above results show that LPW 0.2 SI as a positive electrode electrolyte can comprehensively improve the stability of all-solid-state lithium-sulfur batteries.

[0086] like Fig.14 The sulfur loading of the cell shown is 0.88 mg cm -2 , Figure 14 shows the LiIn|LPSC|LPM 0.2 The cycling performance of SI / SKB battery at C / 5 rate. It can be seen that the first cycle capacity is 1529mAh g -1 (Here, the mass of elemental sulfur is used for calculation). This capacity is mainly provided by the S active material, and the electrolyte also provides some additional capacity. After 100 cycles, the capacity remains at 1434 mAh g -1 (here calculated by the mass of elemental sulfur), also showed excellent stability. This result shows that the sulfide electrolyte regulated by transition metals is used as the sulfur cathode electrolyte.

[0087] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A transition metal-regulated sulfide solid electrolyte, characterized in that: The chemical formula is Li 6+x P 1-x M x S5X, wherein 0.01≤x≤1; M includes at least one of V, Ti, Mo and W; and X includes at least one of F, Cl, Br, I, BH4, CN and SCN.

2. The transition metal-regulated sulfide solid electrolyte according to claim 1, characterized in that: The sulfide solid electrolyte is in a glass phase, a glass-ceramic phase or a ceramic phase.

3. The transition metal-regulated sulfide solid electrolyte according to claim 1, characterized in that: The ionic conductivity at 25°C is ≥ 0.2 mS / cm.

4. The method for preparing the transition metal-regulated sulfide solid electrolyte according to any one of claims 1 to 3, characterized in that: The steps include: (1) mixing the lithium source, phosphorus source, M source, sulfur source and X source in a mortar; (2) placing the mixed raw materials in the first step in a vacuum ball mill, and obtaining the transition metal-regulated sulfide solid electrolyte through ball milling.

5. The method for preparing the transition metal-regulated sulfide solid electrolyte according to claim 4, characterized in that: At least one of the following conditions is met: (1) The lithium source includes at least one of Li2S and LiX; (2) The phosphorus source includes P2S5; (3) The M source includes at least one of TiS2, VS2, MoS2 and WS2; (4) The sulfur source includes at least one of Li2S, MS2 and P2S5; (5) The X source includes a X-containing lithium salt.

6. The method for preparing the transition metal-regulated sulfide solid electrolyte according to claim 4, characterized in that: In step (2), the mass ratio of the ball milling beads to the sum of the lithium source, the phosphorus source, the M source, the sulfur source and the X source is 30-60:

1.

7. The method for preparing the transition metal-regulated sulfide solid electrolyte according to claim 4, characterized in that: In step (2), the rotation speed of the ball mill is 500-600 rpm, and the ball milling time is 15-30 hours; and the ball milling is stopped for 5-15 minutes after each 25-30 minutes of ball milling.

8. A structural component, characterized in that: The invention comprises a positive electrode sheet, a negative electrode sheet and a solid electrolyte layer, wherein the positive electrode sheet contains the transition metal-regulated sulfide solid electrolyte as claimed in any one of claims 1 to 3.

9. The structural assembly according to claim 8, characterized in that: At least one of the following conditions is met: (1) The positive electrode sheet is mainly composed of a positive electrode material and the transition metal-regulated sulfide solid electrolyte; (2) The negative electrode sheet includes at least one of Li, Li-Si alloy, Li-In alloy, and Li-C material; (3) The solid electrolyte layer is mainly composed of at least one electrolyte selected from the group consisting of a sulfide electrolyte, a halide electrolyte, an oxide electrolyte, a polymer electrolyte, a sulfide-polymer composite electrolyte, a halide-polymer composite electrolyte and an oxide-polymer composite electrolyte.

10. An all-solid-state lithium-sulfur battery, characterized in that: It comprises the transition metal-regulated sulfide solid electrolyte as described in any one of claims 1 to 3, or the structural component as described in claim 8.

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