Novel sulfide solid electrolyte preparation method

Abstract

The invention discloses a preparation method of a novel sulfide solid electrolyte, relates to the technical field of sulfide solid electrolytes, and solves the problems that the lithium phosphorus sulfur chlorine structure, components and content of the existing high-chlorine sulfide solid electrolyte are basically determined; therefore, the problems of low ionic conductivity and unstable electrochemical performance of the high-chlorine sulfide solid electrolyte are solved. Comprising the following steps: S1, weighing and mixing a lithium source, a phosphorus source, a sulfur source and a metal halide dopant serving as raw materials to obtain a mixture; s2, putting the mixture into ball milling equipment for grinding and crushing to obtain a precursor mixture; s3, the precursor mixture is taken out and pressed into a sheet shape, and an electrolyte blank is obtained. According to the invention, through a high-temperature annealing process after high-speed ball milling, an element with a large ion radius is introduced from a raw material end in the synthesis process of the sulfide electrolyte for doping to replace a P-site element, and the novel sulfide solid electrolyte with high ionic conductivity and good electrochemical stability is prepared and obtained.

Description

Technical Field

[0001] This invention relates to the field of sulfide solid electrolyte technology, specifically a novel method for preparing sulfide solid electrolytes. Background Technology

[0002] Sulfide solid electrolytes are a core material in all-solid-state batteries. They are inorganic solid electrolyte materials with sulfur as the main component, used in all-solid-state batteries to replace traditional liquid electrolytes, thereby improving battery safety and energy density. The main material systems include sulfide-silver-germanium mineral type (such as Li6PS5Cl) and lithium-germanium-phosphorus-sulfur type (such as Li...). 10 GeP2S 12 Among them, the sulfide-silver-germanium ore type has received widespread attention due to its excellent comprehensive performance and is widely used in the production and preparation of solid-state batteries. The most widely used sulfide solid electrolyte in solid-state batteries is the high-chloride sulfide solid electrolyte.

[0003] The structure, composition, and content of lithium phosphorus sulfur chloride in existing high-chloride sulfide solid electrolytes are basically determined, resulting in low ionic conductivity and unstable electrochemical performance. Therefore, they do not meet the current requirements. To address this, we propose a novel method for preparing sulfide solid electrolytes. Summary of the Invention

[0004] The purpose of this invention is to provide a novel method for preparing sulfide solid electrolytes, in order to solve the problems mentioned in the background art, where the lithium-phosphorus-sulfur-chlorine structure, composition and content of existing high-chlorine sulfide solid electrolytes are basically determined, resulting in low ionic conductivity and unstable electrochemical performance of high-chlorine sulfide solid electrolytes.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a novel method for preparing a sulfide solid electrolyte, comprising the following steps: S1: A mixture is obtained by weighing and mixing lithium source, phosphorus source, sulfur source and metal halide dopant as raw materials; S2: The mixture is placed in a ball mill for grinding and pulverizing to obtain a precursor mixture; S3: The precursor mixture is removed and pressed into sheets to obtain electrolyte embryos; S4: The electrolyte preform is placed in a high-temperature furnace for annealing. S5: The annealed electrolyte preform is crushed to obtain sulfide solid electrolyte powder.

[0006] Preferably, the metal halide dopant is the doping replacement element, and the lithium source, phosphorus source, and sulfur source are the replaced elements. The lithium source includes, but is not limited to, LiCl and Li2S, the phosphorus source includes, but is not limited to, P2S5, the sulfur source includes, but is not limited to, Li2S and P2S5, and the metal halide dopant includes, but is not limited to, at least one of TaCl5, NbCl5, and LaCl3.

[0007] Preferably, the molar ratio of the doping substitution element to the replaced element is 0 to 30%.

[0008] Preferably, the molar ratio of the doping substitution element to the replaced element is 0 to 10%.

[0009] Preferably, the molar ratio of the doping substitution element to the replaced element is 0.5 to 6.5%.

[0010] Preferably, the annealing temperature in the high-temperature furnace is 305–600°C, and the annealing time is 1–8 hours.

[0011] Preferably, the annealing temperature in the high-temperature furnace is 400–550°C, and the annealing time is 2–6 hours.

[0012] Preferably, the annealing temperature in the high-temperature furnace is 420–500°C, and the annealing time is 3–5 hours.

[0013] Preferably, the ball milling equipment includes a turntable support and a grinding jar. The grinding jar is a sealed ball milling jar with an agate inner liner. The grinding jar contains agate grinding beads. The mass ratio of the mixture to the agate grinding beads is 1:10. The agate grinding beads include three different particle sizes: 3mm, 5mm, and 10mm. The mass ratio of the agate grinding beads from smallest to largest particle size is 1:3:6. The ball milling equipment operates at an initial speed of 200 rpm for 20 minutes, and then the speed is adjusted to 600 rpm. At 600 rpm, it operates for 30 minutes, then stops for 10 minutes, and then continues to rotate in the opposite direction at the same speed for 30 minutes, then stops for 10 minutes. This cycle is repeated 5 times in both directions at 600 rpm.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention adds one or more of metal halides MClx (M = Ta, Nb, La; x = 3~6) to the initial raw materials, and then processes them by ball milling, high-temperature annealing and other methods to obtain a novel sulfide solid electrolyte. The ionic conductivity of the sulfide solid electrolyte is higher than that of high-chloride lithium phosphorus sulfide chloride, which improves the low-rate capacity of solid batteries and significantly improves the cycle stability. 2. This invention changes the ionic conductivity of the prepared sulfide solid electrolyte by controlling the replacement ratio of lithium, phosphorus and sulfur sources of metal halide dopants, thereby optimizing the specific capacity of the battery and improving the cycle stability of the battery. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the preparation process of the sulfide solid electrolyte of the present invention. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0017] like Figure 1 As shown, the present invention provides the following embodiment: a novel method for preparing a sulfide solid electrolyte, comprising the following steps: S1: A mixture is obtained by weighing and mixing lithium source, phosphorus source, sulfur source and metal halide dopant as raw materials.

[0018] Metal halide dopants are the doping replacement elements, while lithium, phosphorus, and sulfur sources are the elements being replaced. The lithium source includes, but is not limited to, LiCl and Li2S; the phosphorus source includes, but is not limited to, P2S5; the sulfur source includes, but is not limited to, Li2S and P2S5; and the metal halide dopant includes, but is not limited to, at least one of TaCl5, NbCl5, and LaCl3.

[0019] The proportion of doping and substitution elements plays a crucial role in both the preparation conditions and electrochemical performance of the novel sulfide solid electrolyte. The examples demonstrate the preferred doping and substitution amounts, which can improve the ionic conductivity of the novel sulfide solid electrolyte, optimize the specific capacity of the battery, and improve the cycle stability of the battery. The molar ratio of the doping and substitution elements to the replaced elements is 0-30%; the preferred molar ratio is 0-10%; and the optimal molar ratio is 0.5-6.5%.

[0020] S2: The mixture is placed in a ball mill for grinding and pulverizing to obtain a precursor mixture.

[0021] The ball mill was run at an initial speed of 200 rpm for 20 minutes, then the speed was adjusted to 600 rpm. After running at 600 rpm for 30 minutes, it was stopped for 10 minutes, and then it was rotated in the opposite direction at the same speed for 30 minutes, and then stopped for 10 minutes. This cycle was repeated 5 times in both directions at 600 rpm.

[0022] As a preferred embodiment, the ball milling device includes a turntable support and a grinding jar. The grinding jar is a sealed ball milling jar with an agate inner liner. Agate grinding beads are provided inside the grinding jar, and the mass ratio of the mixture to the agate grinding beads is 1:10.

[0023] Agate grinding beads come in three different sizes: 3mm, 5mm, and 10mm. The mass ratio of agate grinding beads from smallest to largest size is 1:3:6.

[0024] After the first ball milling, the ball mill jar was transferred to the glove box, the sample was removed and crushed, and then put back into the ball mill jar. The ball milling operation was then repeated three times.

[0025] S3: The precursor mixture is removed and pressed into sheets to obtain electrolyte embryos.

[0026] Inside the glove box, the material after the fourth ball milling was pressed into an electrolyte embryo sample block with a diameter of φ=1cm and a thickness of about 1-2mm.

[0027] S4: The electrolyte preform is placed in a high-temperature furnace for annealing.

[0028] The control of annealing temperature and annealing time during the preparation process is the key to achieving the conductivity and electrochemical stability of kaolin. The annealing temperature in the high-temperature furnace is 305-600℃, preferably 400-550℃, and optimally 420-500℃; the annealing time is 1-8 hours, preferably 2-6 hours, and optimally 3-5 hours. The heating and cooling rates during the annealing process are both 2℃ / min.

[0029] S5: The annealed electrolyte preform is pulverized to obtain sulfide solid electrolyte powder.

[0030] The sulfide solid electrolyte powder has a D50 of 5 μm.

[0031] In the first embodiment, LiCl, P2S5, Li2S and TaCl5 were selected as initial raw materials, and weighed and mixed in a glove box with water and oxygen content strictly below 0.01 ppm according to a molar ratio of 1.5:0.495:2.025:0.01. The electrolyte preform sample block was sealed in a glass sample tube and transferred to a high-temperature furnace for annealing at 440℃ for 5 hours. The heating and cooling rates during the annealing process were both 2℃ / min.

[0032] The second embodiment differs from the first embodiment in that the doping ratio of TaCl5 is different; The molar ratio of LiCl, P2S5, Li2S and TaCl5 is 1.5:0.495:2.025:0.02.

[0033] The third embodiment differs from the first embodiment in that the doping ratio of TaCl5 is different. The molar ratio of LiCl, P2S5, Li2S and TaCl5 is 1.5:0.495:2.025:0.05.

[0034] The fourth embodiment differs from the first embodiment in that the annealing temperature is different; The annealing temperature in the high-temperature furnace was 440℃, the annealing time was 5h, and the heating and cooling rates were both 2℃ / min.

[0035] The fifth embodiment differs from the first embodiment in that the annealing temperature is different. The annealing temperature in the high-temperature furnace was 500℃, the annealing time was 5h, and the heating and cooling rates were both 2℃ / min.

[0036] The sixth embodiment differs from the first embodiment in that the annealing temperature is different; The annealing temperature in the high-temperature furnace was 440℃, the annealing time was 3h, and the heating and cooling rates were both 2℃ / min.

[0037] The seventh embodiment differs from the first embodiment in that the annealing temperature is different; The annealing temperature in the high-temperature furnace was 440℃, the annealing time was 10h, and the heating and cooling rates were both 2℃ / min.

[0038] Comparative Example 1: The difference from Example 1 is that LiCl, P2S5 and Li2S were selected as the initial raw materials and weighed and mixed in a molar ratio of 1.5:0.5:2; The annealing temperature in the high-temperature furnace was 450℃, the annealing time was 5h, and the heating and cooling rates were both 2℃ / min.

[0039] Comparative Example 2: The difference from the first embodiment is the annealing temperature; The annealing temperature in the high-temperature furnace was 480℃, the annealing time was 5h, and the heating and cooling rates were both 2℃ / min.

[0040] The electrolyte powders obtained from each embodiment and comparative example were pressed into tablets, and their ionic conductivity was tested by electrochemical impedance spectroscopy. The tablets were then assembled into solid-state simulated batteries for charge-discharge testing. The results are shown in Table 1. .

[0041] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A novel method for preparing a sulfide solid electrolyte, characterized in that: Includes the following steps: S1: A mixture is obtained by weighing and mixing lithium source, phosphorus source, sulfur source and metal halide dopant as raw materials; S2: The mixture is placed in a ball mill for grinding and pulverizing to obtain a precursor mixture; S3: The precursor mixture is removed and pressed into sheets to obtain electrolyte embryos; S4: The electrolyte preform is placed in a high-temperature furnace for annealing. S5: The annealed electrolyte preform is crushed to obtain sulfide solid electrolyte powder.

2. The method for preparing a novel sulfide solid electrolyte according to claim 1, characterized in that: The metal halide dopant is a doping substitution element, and the lithium source, phosphorus source, and sulfur source are the elements being replaced. The lithium source includes, but is not limited to, LiCl and Li2S, the phosphorus source includes, but is not limited to, P2S5, the sulfur source includes, but is not limited to, Li2S and P2S5, and the metal halide dopant includes, but is not limited to, at least one of TaCl5, NbCl5, and LaCl3.

3. The method for preparing a novel sulfide solid electrolyte according to claim 2, characterized in that: The ball milling equipment includes a turntable support and a ball milling jar. The ball milling jar is a sealed ball milling jar with an agate inner liner, and the inside of the ball milling jar is equipped with agate grinding beads. The mass ratio of the mixture to the agate grinding beads is 1:

10. The agate grinding beads include three different particle sizes: 3mm, 5mm, and 10mm. The mass ratio of the agate grinding beads from smallest to largest particle size is 1:3:

6. The ball milling equipment runs at an initial speed of 200 rpm for 20 minutes, then the speed is adjusted to 600 rpm. At 600 rpm, it runs for 30 minutes, then stops for 10 minutes, and then continues to rotate in the opposite direction at the same speed for 30 minutes, then stops for 10 minutes. This cycle is repeated 5 times in both directions at 600 rpm.

4. The method for preparing a novel sulfide solid electrolyte according to claim 3, characterized in that: The molar ratio of the doping substitution element to the replaced element is 0 to 30%.

5. The method for preparing a novel sulfide solid electrolyte according to claim 4, characterized in that: The molar ratio of the doping substitution element to the replaced element is 0 to 10%.

6. The method for preparing a novel sulfide solid electrolyte according to claim 5, characterized in that: The molar ratio of the doping substitution element to the replaced element is 0.5 to 6.5%.

7. A method for preparing a novel sulfide solid electrolyte according to any one of claims 4-6, characterized in that: The annealing temperature in the high-temperature furnace is 305–600℃, and the annealing time is 1–8 hours.

8. The method for preparing a novel sulfide solid electrolyte according to claim 7, characterized in that: The annealing temperature in the high-temperature furnace is 400–550°C, and the annealing time is 2–6 hours.

9. The method for preparing a novel sulfide solid electrolyte according to claim 8, characterized in that: The annealing temperature in the high-temperature furnace is 420–500°C, and the annealing time is 3–5 hours.

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