Submicron sulfide solid electrolyte and preparation method thereof

Abstract

The invention provides a submicron sulfide solid electrolyte and a preparation method thereof, the preparation method comprises the following steps: weighing a proper amount of Li2S, P2S5 and LiX as raw materials, X being a halogen element; mechanically grinding the raw materials to obtain a sulfide solid electrolyte precursor; sintering the sulfide solid electrolyte precursor and cooling at room temperature to obtain a large-particle-size sulfide solid electrolyte; and mechanically grinding the large-particle-size sulfide solid electrolyte to obtain the submicron sulfide solid electrolyte. The submicron-level sulfide solid electrolyte is prepared by combining high-temperature solid-phase sintering and mechanical grinding, so that the loss of raw materials is effectively reduced, and the purity of the raw materials is improved.

Description

Technical Field

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

[0002] All-solid-state batteries have attracted much attention due to their higher safety and higher energy density. As a key material of all-solid-state batteries, solid electrolytes are directly related to the cycle performance of all-solid-state batteries due to their ionic conductivity, interface contact and electrochemical stability. Sulfide solid electrolytes have excellent ionic conductivity and good interface contact, making them a research hotspot in inorganic solid electrolytes.

[0003] At present, the main methods for preparing sulfide solid electrolytes are dry ball milling and wet ball milling. The sulfide solid electrolyte prepared by dry ball milling has a larger particle size and requires further processing. The electrolyte particles prepared by wet ball milling are smaller, but there are problems such as decreased ion conductivity and poor performance. Doping with halogen elements is beneficial to improving the electrochemical stability of the electrolyte, improving the stability of contact with the positive and negative electrodes, and improving the safety and stability of all-solid-state batteries. At present, the amount of sulfide electrolytes prepared in the laboratory is small, which affects mass production and use. Therefore, how to use new processes to prepare mass production of sulfide solid electrolytes is one of the difficulties. Summary of the invention

[0004] The purpose of the present invention is to propose a submicron sulfide solid electrolyte and a preparation method thereof, which can improve the safety and stability of the battery, improve the mass production capacity of the submicron sulfide electrolyte, and provide assistance for the industrialization of all-solid-state batteries.

[0005] The present invention is implemented as follows: a submicron sulfide solid electrolyte having a chemical formula of Li a P b S c X d It represents, wherein a, b, c, and d respectively represent the number of Li elements, the number of P elements, the number of S elements, and the number of X elements under the condition of one submicron sulfide solid electrolyte, a, b, c, and d make the submicron sulfide solid electrolyte satisfy electrical neutrality, X is a halogen element, and the particle size of the submicron sulfide solid electrolyte is between 100 nm and 1 μm.

[0006] For example, the halogen element is one or more of F, Cl, Br, and I.

[0007] Illustratively, a+5b=2c+d.

[0008] Illustratively, a=5-6, b=1, c=4-5, d=1-2.

[0009] For example, a=5.5, b=1, c=4.5, d=1.5; a=6, b=1, c=5, d=1; or a=5.7, b=1, c=4.7, d=1.3.

[0010] The present invention is implemented as follows: A method for preparing a submicron sulfide solid electrolyte comprises: weighing an appropriate amount of Li 2 S.P. 2 S 5 and LiX as a raw material, wherein X is a halogen element; mechanically grinding the raw material to obtain a sulfide solid electrolyte precursor; sintering the sulfide solid electrolyte precursor and cooling it at room temperature to obtain a sulfide solid electrolyte with a large particle size; and mechanically grinding the sulfide solid electrolyte with a large particle size to obtain a submicron sulfide solid electrolyte.

[0011] For example, the halogen element is one or more of F, Cl, Br, and I.

[0012] For example, the raw material further includes metal salts, and the metal salts include one or more of Fe, Zn, Ge, Zr, Ca, Mg, Ti, and Ag.

[0013] For example, the mechanical grinding of the raw materials is carried out in a high-speed mixer, a planetary ball mill, a horizontal ball mill, or a jet mill.

[0014] For example, when the raw materials are mechanically ground, the pressure in the ball mill is 800 Pa to 1000 Pa, the ball-to-material ratio is (20 to 60):1, the ball mill speed is 10 r / min to 50 r / min, and the ball mill time is 2 h to 4 h.

[0015] For example, the sintering temperature is 400° C. to 500° C., and the sintering time is 2 h to 4 h.

[0016] For example, when mechanically grinding the large-particle sulfide solid electrolyte, the ball-to-material ratio is (20 to 60):1, the liquid-to-material ratio is 1:(20 to 60), the ball milling speed is 100 r / min to 2800 r / min, and the ball milling time is 0.5 h to 4 h.

[0017] For example, mechanical grinding of the large-particle sulfide solid electrolyte is performed in a ball milling solvent, and the ball milling solvent includes one or more of cyclohexane, xylene, o-xylene, 2-xylene, n-heptane, dimethyl carbonate, and isobutyl isobutyrate.

[0018] For example, the raw material is mechanically ground by dry ball milling, and the large-particle sulfide solid electrolyte is mechanically ground by wet ball milling.

[0019] For example, the Li 2 S. P 2 S 5 And the molar ratio between the LiX is (2 to 6):1:(2 to 4).

[0020] In summary, the present invention proposes a sulfide solid electrolyte and a preparation method thereof in view of the properties of sulfide electrolytes. The preparation method combines high-temperature solid-phase sintering and mechanical grinding to prepare a submicron-level sulfide solid electrolyte, thereby effectively reducing the loss of raw materials and improving the purity of raw materials. Compared with the prior art, the technical solution of the present invention brings at least one or more of the following beneficial effects:

[0021] (1) High-temperature solid-phase sintering and mechanical grinding can produce high-purity submicron-level sulfide solid electrolytes that are stable at room temperature, with an ionic conductivity of 1.0x10 -3 S / cm to 1.0x10 -2 S / cm.

[0022] (2) Mechanical grinding can effectively reduce the particle size of sulfide solid electrolytes. Applying it to composite positive electrodes can improve the solid-solid contact in solid-state batteries, thereby improving the electrochemical performance of solid-state batteries.

[0023] (3) The ball milling process is optimized by controlling the rotation speed, ball-to-material ratio, and time so that the sulfide electrolyte is a pure phase after sintering, thereby improving the safety and stability of the battery made using it.

[0024] (4) The technical means of the present invention can expand production and achieve Li 5.5 PS 4.5 Cl 1.5 The large-scale mass production of sulfide solid electrolytes can achieve a daily output of 10kg of submicron sulfide solid electrolytes. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a scanning electron microscope (SEM) photograph of a large-particle sulfide solid electrolyte;

[0026] Figure 2 This is a scanning electron microscope (SEM) photograph of a submicron-scale sulfide solid electrolyte;

[0027] Figure 3 This is the X-ray diffractometer (XRD) analysis result of submicron-level sulfide solid electrolyte;

[0028] Figure 4 This is a graph showing the long cycle charge and discharge test results of the submicron-sized sulfide solid electrolyte of Example 1 and the large-particle-sized sulfide solid electrolyte of Comparative Example 1. DETAILED DESCRIPTION

[0029] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0030] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0031] The first embodiment of the present invention proposes a submicron sulfide solid electrolyte. The so-called "submicron" means that the particle size of the solid electrolyte is in the range of 100nm to 1μm, preferably 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 850nm, 900nm, 950nm, or 1μm.

[0032] Submicron-sized sulfide solid electrolytes are chemically Li a P b S c X d Indicates that a, b, c, and d represent the number of Li elements, the number of P elements, the number of S elements, and the number of X elements under the condition of one submicron sulfide solid electrolyte, respectively. a, b, c, and d make the submicron sulfide solid electrolyte meet the electrical neutrality, and X is a halogen element. The halogen element may include but is not limited to one or more of F, Cl, Br, and I, preferably F, Cl, or Br. Under the condition of meeting the electrical neutrality, a, b, c, and d may meet the following relationship: a+5b=2c+d, and may further meet a=5 to 6, b=1, c=4 to 5, and d=1 to 2, preferably a=5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, or 6, b=1, c=4, 4.1, 4.2, 4.3, 4.4 , 4.5, 4.6, 4.7, 4.8, 4.9, or 5, d=1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2, more preferably a=5.5, b=1, c=4.5, d=1.5; a=6, b=1, c=5, d=1; or a=5.7, b=1, c=4.7, d=1.3.

[0033] The second embodiment of the present invention provides a method for preparing a submicron sulfide solid electrolyte, where "submicron" means that the particle size of the solid electrolyte is in the range of 100nm to 1μm, preferably 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 850nm, 900nm, 950nm, or 1μm. The detailed steps of the preparation method of this embodiment are described in the following paragraphs.

[0034] First, weigh an appropriate amount of Li 2 S.P. 2 S 5 and LiX as a raw material, X is a halogen element. The halogen element may include but is not limited to one or more of F, Cl, Br, and I, preferably F, Cl, or Br. Li 2 S.P. 2 S 5 The amount of LiX weighed can be expressed in terms of mass or mole, and the calculation standard is the ratio of the number of different elements in the chemical formula of the obtained submicron-sized sulfide solid electrolyte. Specifically, the submicron-sized sulfide solid electrolyte can be expressed in terms of the chemical formula Li a P b S c X d The definitions of a, b, c, and d refer to the first embodiment and will not be described in detail here. 2 The sum of the moles of S plus 1 times the moles of LiX, 2 times the moles of P 2 S 5 Number of moles, 1 times Li 2 The number of moles of S plus 5 times the number of moles of P 2 S 5 The total molar number and the ratio between the molar number of LiX satisfy a:b:c:d. Further conversion can be obtained: Li 2 S.P. 2 S 5 and LiX have a molar ratio of (ad) / 2:b / 2:d. 2 S.P. 2 S 5and LiX may be, but is not limited to, (3 to 5):1:(2 to 4), preferably (3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5):1:(2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, to 4), preferably 4:1:3, 5:1:2, or 4.4:1:2.6.

[0035] In order to adjust the performance of the submicron sulfide solid electrolyte to meet actual needs, the raw materials may include but are not limited to metal salts, and the metal salts include one or more of Fe, Zn, Ge, Zr, Ca, Mg, Ti, and Ag. Under this condition, the submicron sulfide solid electrolyte can be chemically Li a-e P b S c M e X d , where ae, b, c, d, and e represent the number of Li elements, P elements, S elements, X elements, and M elements (metal elements in metal salts) under the condition of one submicron sulfide solid electrolyte, and a, b, c, d, and e make the submicron sulfide solid electrolyte meet the electrical neutrality. Based on this, 2 times the Li 2 The sum of the moles of S plus 1 times the moles of LiX, 2 times the moles of P 2 S 5 Number of moles, 1 times Li 2 The number of moles of S plus 5 times the number of moles of P 2 S 5 The sum of the moles, the moles of LiX, and the ratio between N times the metal salts satisfy (ae): b: c: d: e, where N is the number of metal elements under the condition of 1 metal salt. Further conversion can be obtained: Li 2 S.P. 2 S 5 The molar ratio between LiX and metal salts is (ade) / 2:b / 2:d:e / N.

[0036] Next, the raw materials are mechanically ground to obtain a sulfide solid electrolyte precursor. The mechanical grinding of the raw materials can be carried out by, but not limited to, dry ball milling; and the mechanical grinding of the raw materials can be carried out in, but not limited to, a high-speed mixer, a planetary ball mill, a horizontal ball mill, or a jet mill. When the raw materials are mechanically ground, the pressure in the ball mill can be but not limited to 800Pa to 1000Pa, preferably 800Pa, 810Pa, 820Pa, 830Pa, 840Pa, 850Pa, 860Pa, 870Pa, 880Pa, 890Pa, 900Pa, 910Pa, 920Pa, 930Pa, 940Pa, 950Pa, 960Pa, 970Pa, 980Pa, 990Pa, or 1000Pa; the ball to material ratio can be but not limited to (20 to 60):1, preferably 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, or 60:1; the ball milling speed may be, but not limited to, 10 r / min to 50 r / min, preferably 10 r / min, 15 r / min, 20 r / min, 25 r / min, 30 r / min, 35 r / min, 40 r / min, 45 r / min, or 50 r / min; the ball milling time may be, but not limited to, 2 h to 4 h, preferably 2 h, 2 h and 10 min, 2 h and 20 min, 2 h and 30 min, 2 h and 40 min, 2 h and 50 min, 3 h, 3 h and 10 min, 3 h and 20 min, 3 h and 30 min, 3 h and 40 min, 3 h and 50 min, or 4 h.

[0037] Then, the sulfide solid electrolyte precursor is sintered and cooled at room temperature to obtain a sulfide solid electrolyte with a large particle size. The sintering temperature may be, but is not limited to, 400°C to 500°C, preferably 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, or 500°C; the sintering time may be, but is not limited to, 2h to 4h, preferably 2h, 2h and 10min, 2h and 20min, 2h and 30min, 2h and 40min, 2h and 50min, 3h, 3h and 10min, 3h and 20min, 3h and 30min, 3h and 40min, 3h and 40min, or 4h. In addition, the particle size of the large-particle sulfide solid electrolyte may be but is not limited to 10 μm to 50 μm, preferably 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, or 50 μm, more preferably 10 μm or 15 μm.

[0038] Finally, mechanically grind the large-particle sulfide solid electrolyte to obtain a submicron-sized sulfide solid electrolyte. Mechanical grinding of large-particle sulfide solid electrolyte can be performed by, but not limited to, wet ball milling; mechanical grinding of large-particle sulfide solid electrolyte can be performed in, but not limited to, a ball milling solvent, and the ball milling solvent can include, but is not limited to, one or more of cyclohexane, xylene, o-xylene, q-xylene, n-heptane, dimethyl carbonate, and isobutyl isobutyrate. When mechanically grinding a large-particle sulfide solid electrolyte, the ball-to-material ratio may be, but not limited to, (20 to 60):1, preferably 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, or 60:1; the liquid-to-material ratio may be, but not limited to, 1:(20 to 60), preferably 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, or 1:60; the ball milling speed may be, but not limited to, 100 r / min to 2800 r / min, preferably 100 r / min, 200 r / min, 300 r / min, 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min in, 900r / min, 1000r / min, 1100r / min, 1200r / min, 1300r / min, 1400r / min, 1500r / min, 1600r / min, 1700r / min, 1800r / min, 1900r / min, 2000r / min, 2100r / min, 2200r / min, 2300r / min, 2400r / min, 2500r / min, 2600r / min, 2700r / min, or 2800r / min; the ball milling time may be, but is not limited to, 0.5h to 4h, preferably 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, or 4h.

[0039] The present invention is illustrated by the following examples:

[0040] Embodiment 1:

[0041] Weigh an appropriate amount of Li at a molar ratio of 4:1:3 2 S.P. 2 S 5 The raw materials were placed in a sealed ball mill with a ball-to-material ratio of 30:1. The mechanical ball milling method was used for preliminary ball milling, with a ball milling speed of 50r / min and a ball milling time of 3h. The ground sulfide solid electrolyte precursor was sintered in a muffle furnace at a sintering temperature of 500℃ and a sintering time of 4h. After cooling at room temperature, a large-particle sulfide solid electrolyte (such as Figure 1The obtained large-particle sulfide solid electrolyte was placed in a mechanical mill with a ball milling speed of 2800 r / min, a ball milling time of 0.5 h, a material-liquid ratio of 1:30, and a solvent of dimethyl carbonate to obtain a submicron-level sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 (like Figure 2 ), and its XRD analysis results are as follows Figure 3 .

[0042] Submicron-scale sulfide solid electrolyte powder is made into solid electrolyte sheets. 5.5 PS 4.5 Cl 1.5 The solid electrolyte grains are complete, without gaps, and the particles are small, all below 1μm.

[0043] Embodiment 2:

[0044] Weigh an appropriate amount of Li at a molar ratio of 4:1:3 2 S.P. 2 S 5 With LiBr raw materials, place the raw materials in a sealed ball mill with a ball-to-liquid ratio of 30:1; use mechanical ball milling for preliminary ball milling, the ball milling speed is 30r / min, and the ball milling time is 4h. The ground sulfide solid electrolyte precursor is screened and sintered in a muffle furnace with a sintering temperature of 500℃ and a sintering time of 4h. After cooling to room temperature, a large-particle sulfide solid electrolyte is obtained. The obtained large-particle sulfide solid electrolyte is placed in a mechanical mill with a ball milling speed of 2600r / min, a ball milling time of 0.7h, a material-liquid ratio of 1:30, and the solvent is isobutyl isobutyrate to obtain a submicron-level sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 .

[0045] Embodiment 3:

[0046] Weigh an appropriate amount of Li at a molar ratio of 4:1:3 2 S.P. 2 S 5With LiBr raw materials, place the raw materials in a sealed ball mill with a ball-to-liquid ratio of 20:1; use mechanical ball milling for preliminary ball milling, the ball milling speed is 40r / min, and the ball milling time is 3h. The ground sulfide solid electrolyte precursor is screened and sintered in a muffle furnace with a sintering temperature of 490°C and a sintering time of 4h. After cooling to room temperature, a large-particle sulfide solid electrolyte is obtained. The obtained large-particle sulfide solid electrolyte is placed in a mechanical mill with a ball milling speed of 2500r / min, a ball milling time of 0.6h, a material-liquid ratio of 1:25, and a solvent of dimethyl carbonate to obtain a submicron-level sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 .

[0047] Embodiment 4:

[0048] Weigh an appropriate amount of Li at a molar ratio of 4:1:3 2 S.P. 2 S 5 With LiF raw materials, place the raw materials in a sealed ball mill with a ball-to-liquid ratio of 20:1; use mechanical ball milling for preliminary ball milling, the ball milling speed is 40r / min, and the ball milling time is 3h. The ground sulfide solid electrolyte precursor is screened and sintered in a muffle furnace with a sintering temperature of 490℃ and a sintering time of 4h. After cooling to room temperature, a large-particle sulfide solid electrolyte is obtained. The obtained large-particle sulfide solid electrolyte is placed in a mechanical mill with a ball milling speed of 2600r / min, a ball milling time of 0.5h, a material-liquid ratio of 1:20, and a solvent of dimethyl carbonate to obtain a submicron-level sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 .

[0049] Embodiment 5:

[0050] Weigh an appropriate amount of Li at a molar ratio of 5:1:2 2 S.P. 2 S 5 With LiCl raw materials, place the raw materials in a sealed ball mill with a ball-to-liquid ratio of 20:1; use mechanical ball milling for preliminary ball milling, the ball milling speed is 40r / min, and the ball milling time is 3h. The ground sulfide solid electrolyte precursor is screened and sintered in a muffle furnace with a sintering temperature of 500℃ and a sintering time of 6h. After cooling to room temperature, a large-particle sulfide solid electrolyte is obtained. The obtained large-particle sulfide solid electrolyte is placed in a mechanical mill with a ball milling speed of 2800r / min, a ball milling time of 0.5h, a material-liquid ratio of 1:20, and a solvent of dimethyl carbonate to obtain a submicron-level sulfide solid electrolyte Li 6 PS5 Cl.

[0051] Embodiment 6:

[0052] Weigh an appropriate amount of Li at a molar ratio of 4.4:1:2.6 2 S.P. 2 S 5 With LiCl raw materials, place the raw materials in a sealed ball mill with a ball-to-liquid ratio of 20:1; use mechanical ball milling for preliminary ball milling, the ball milling speed is 40r / min, and the ball milling time is 3h. The ground sulfide solid electrolyte precursor is screened and sintered in a muffle furnace with a sintering temperature of 480℃ and a sintering time of 5h. After cooling to room temperature, a large-particle sulfide solid electrolyte is obtained. The obtained large-particle sulfide solid electrolyte is placed in a mechanical mill with a ball milling speed of 2200r / min, a ball milling time of 0.5h, a material-liquid ratio of 1:20, and a solvent of dimethyl carbonate to obtain a submicron-level sulfide solid electrolyte Li 5.7 PS 4.7 Cl 1.3 .

[0053] Comparative Example 1:

[0054] Weigh an appropriate amount of Li at a molar ratio of 4:1:3 2 S.P. 2 S 5 The raw materials were placed in a sealed ball mill with a ball-to-material ratio of 30:1. The mechanical ball milling method was used for preliminary ball milling, with a ball milling speed of 50r / min and a ball milling time of 2h. The ground sulfide solid electrolyte precursor was obtained by sieving, and was placed in a muffle furnace for sintering at a sintering temperature of 500℃ and a sintering time of 4h. After cooling at room temperature, a large-particle sulfide solid electrolyte was obtained. The large-particle sulfide solid electrolyte powder was made into a solid electrolyte sheet.

[0055] like Figure 4 As shown, the capacity retention rate of the submicron sulfide solid electrolyte of Example 1 after 500 cycles of 0.5C charge and discharge can reach 89.77%, compared with 80.35% of the large-particle sulfide solid electrolyte of Comparative Example 1. The first-cycle performance and long-cycle performance of the submicron sulfide solid electrolyte are significantly improved.

[0056] The above contents involving common knowledge are not described in detail, and those skilled in the art can understand them.

[0057] The above descriptions are only some specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. The technical scope of the present invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A submicron sulfide solid electrolyte, characterized in that: With chemical formula Li a P b S c X d It represents, wherein a, b, c, and d respectively represent the number of Li elements, the number of P elements, the number of S elements, and the number of X elements under the condition of one submicron sulfide solid electrolyte, a, b, c, and d make the submicron sulfide solid electrolyte satisfy electrical neutrality, X is a halogen element, and the particle size of the submicron sulfide solid electrolyte is between 100 nm and 1 μm.

2. The submicron sulfide solid electrolyte according to claim 1, characterized in that: The halogen element is one or more of F, Cl, Br and I.

3. The submicron sulfide solid electrolyte according to claim 1, characterized in that: a+5b=2c+d.

4. The submicron sulfide solid electrolyte according to claim 1, characterized in that: a=5 to 6, b=1, c=4 to 5, d=1 to 2.

5. The submicron sulfide solid electrolyte according to claim 1, characterized in that: a=5.5, b=1, c=4.5, d=1.5; a=6, b=1, c=5, d=1; or a=5.7, b=1, c=4.7, d=1.

3.

6. A method for preparing a submicron sulfide solid electrolyte, characterized in that: include: Weigh appropriate amounts of Li2S, P2S5 and LiX as raw materials, wherein X is a halogen element; Mechanically grinding the raw materials to obtain a sulfide solid electrolyte precursor; Sintering the sulfide solid electrolyte precursor and cooling it at room temperature to obtain a sulfide solid electrolyte with a large particle size; as well as The large-particle sulfide solid electrolyte is mechanically ground to obtain a submicron-sized sulfide solid electrolyte.

7. The method for preparing a submicron sulfide solid electrolyte according to claim 6, characterized in that: The halogen element is one or more of F, Cl, Br and I.

8. The method for preparing a submicron sulfide solid electrolyte according to claim 6, characterized in that: The raw materials further include metal salts, and the metal salts include one or more of Fe, Zn, Ge, Zr, Ca, Mg, Ti, and Ag.

9. The method for preparing a submicron sulfide solid electrolyte according to claim 6, characterized in that: Mechanical grinding of the raw materials is carried out in a high-speed mixer, a planetary ball mill, a horizontal ball mill, or a jet mill.

10. The method for preparing a submicron sulfide solid electrolyte according to claim 6, characterized in that: When the raw materials are mechanically ground, the pressure in the ball mill is 800 Pa to 1000 Pa, the ball-to-material ratio is (20 to 60):1, the ball mill speed is 10 r / min to 50 r / min, and the ball mill time is 2 h to 4 h.

11. The method for preparing a submicron sulfide solid electrolyte according to claim 6, characterized in that: The sintering temperature is 400°C to 500°C, and the sintering time is 2h to 4h.

12. The method for preparing a submicron sulfide solid electrolyte according to claim 6, characterized in that: When mechanically grinding the large-particle sulfide solid electrolyte, the ball-to-material ratio is (20 to 60):1, the liquid-to-material ratio is 1:(20 to 60), the ball milling speed is 100 r / min to 2800 r / min, and the ball milling time is 0.5 h to 4 h.

13. The method for preparing a submicron sulfide solid electrolyte according to claim 6, characterized in that: Mechanically grinding the large-particle sulfide solid electrolyte is performed in a ball milling solvent, wherein the ball milling solvent includes one or more of cyclohexane, xylene, o-xylene, 2-xylene, n-heptane, dimethyl carbonate, and isobutyl isobutyrate.

14. The method for preparing a submicron sulfide solid electrolyte according to claim 6, characterized in that: The raw material is mechanically ground by dry ball milling, and the large-particle sulfide solid electrolyte is mechanically ground by wet ball milling.

15. The method for preparing a submicron sulfide solid electrolyte according to claim 6, characterized in that: The molar ratio of the Li2S, the P2S5 and the LiX is (2 to 6):1:(2 to 4).

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