Recycling method of sulfide solid electrolyte

Abstract

The invention provides a recycling method of sulfide solid electrolyte. The recycling method comprises the following steps: (1) determining required components in invalid sulfide solid electrolyte; and (2) processing the invalid sulfide solid electrolyte based on the measured required components to obtain the sulfide solid electrolyte with conductivity meeting application conditions. According to the method, the state of the sulfide electrolyte is confirmed by measuring the direct relation between specific elements in the sulfide solid electrolyte and the conductivity, and the conductivity of the sulfide solid electrolyte is recovered to 10ms / cm through secondary processing of the sulfide electrolyte, so that the sulfide solid electrolyte can be recycled, waste is reduced, and the cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries and relates to a method for recycling sulfide solid electrolytes. Background Art

[0002] Sulfide solid electrolytes are attracting increasing attention due to their ultra-high electrical conductivity and high morphability. The mass production of sulfide solid electrolytes has become a symbol of the strength of solid-state battery companies. At present, most sulfide electrolyte systems with high ionic conductivity contain the element P. According to the theory of hard and soft acids and bases, sulfide electrolytes containing the element P have poor air stability and easily react with moisture and oxygen in the air, accompanied by the production of toxic hydrogen sulfide gas, which destroys the structure of the electrolyte itself and changes its chemical composition, leading to a sharp deterioration in its ionic conductivity and other properties. However, current research rarely focuses on the failure of sulfide electrolytes during preparation and storage, resulting in the abandonment and waste of sulfide electrolytes due to failure for various reasons.

[0003] At present, the failure of sulfide electrolytes mainly includes two reasons. On the one hand, due to problems with the large-scale preparation process during the preparation of sulfide solid electrolytes, there is volatilization loss of some materials, resulting in its conductivity being lower than its theoretical conductivity; on the other hand, since there is still some time before the commercial application of solid-state batteries, some batched sulfide electrolytes are difficult to digest and are stored for a long time. Due to storage environment problems and exposure to water and moisture during transportation, the conductivity of sulfide electrolytes decreases.

[0004] In this regard, how to confirm whether the sulfide electrolyte has failed during the preparation or storage process, and how to effectively recycle and reuse the failed sulfide electrolyte are issues that need to be urgently addressed. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention provides a method for recycling sulfide solid electrolytes. This method measures the direct relationship between specific elements in the sulfide solid electrolyte and its conductivity to confirm the state of the sulfide electrolyte. Secondary processing of the sulfide solid electrolyte restores its conductivity, allowing it to be recycled, reducing waste and lowering costs.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for recycling sulfide solid electrolytes, the recycling method comprising:

[0008] (1) Determination of required components in spent sulfide solid electrolytes;

[0009] (2) Based on the determined required components, the failed sulfide solid electrolyte is processed to obtain a sulfide solid electrolyte whose conductivity meets the application conditions.

[0010] As a preferred embodiment of the present invention, before step (1) determining the required components in the failed sulfide solid electrolyte, the method further includes the step of confirming whether the sulfide solid electrolyte is in a failed state, comprising: detecting the change in the S element content and the electrical conductivity in the sulfide solid electrolyte, and confirming that the sulfide solid electrolyte is in a failed state.

[0011] As a preferred embodiment of the present invention, detecting the change in the S element content and the electrical conductivity in the sulfide solid electrolyte includes: when the change in the S element in the sulfide solid electrolyte is ≥10wt% and the electrical conductivity is ≤0.5mS / cm, the sulfide solid electrolyte is in a failed state.

[0012] As a preferred embodiment of the present invention, detecting the change in the S element content and the electrical conductivity in the sulfide solid electrolyte includes: when the change in the S element in the sulfide solid electrolyte is ≥20wt% and the electrical conductivity is ≤1mS / cm, the sulfide solid electrolyte is in a failed state.

[0013] As a preferred embodiment of the present invention, determining the required components in the failed sulfide solid electrolyte in step (1) includes determining the lost components in the failed sulfide solid electrolyte, or the missing components after comparison with the target sulfide solid electrolyte.

[0014] As a preferred embodiment of the present invention, in step (1), the required components in the failed sulfide solid electrolyte are determined by XRD determination and / or calcination method.

[0015] As a preferred embodiment of the present invention, the calcination method in step (1) comprises: placing the failed sulfide solid electrolyte in an inert atmosphere for calcination, and judging whether the P2S5 reaction is complete based on whether yellow droplets appear.

[0016] As a preferred embodiment of the present invention, the moisture content in the inert atmosphere is ≤1 ppm, and the oxygen content is ≤1 ppm.

[0017] As a preferred embodiment of the present invention, the inert atmosphere includes any one of helium atmosphere, argon atmosphere or nitrogen atmosphere, or a combination of at least two of them.

[0018] As a preferred embodiment of the present invention, the calcination temperature is 150°C to 600°C.

[0019] As a preferred embodiment of the present invention, the roasting time is 5 minutes to 20 hours.

[0020] As a preferred embodiment of the present invention, the processing of the sulfide solid electrolyte in step (2) includes: adding the determined missing components to the failed sulfide solid electrolyte, mechanically crushing it, and calcining it to obtain a sulfide solid electrolyte whose electrical conductivity meets the application conditions.

[0021] As a preferred embodiment of the present invention, the mechanical crushing includes ball milling.

[0022] As a preferred embodiment of the present invention, the rotation speed of the ball mill is 350 rpm to 600 rpm, preferably 500 rpm.

[0023] As a preferred embodiment of the present invention, the ball milling time is 15 hours to 40 hours, preferably 20 hours.

[0024] As a preferred embodiment of the present invention, the ball-to-material mass ratio of the ball mill is (3-10):1, preferably 5:1.

[0025] As a preferred embodiment of the present invention, the calcination temperature is 150°C to 600°C.

[0026] As a preferred embodiment of the present invention, the calcination time is 5 minutes to 20 hours.

[0027] As a preferred embodiment of the present invention, step (2) of processing the failed sulfide solid electrolyte is carried out under an inert atmosphere.

[0028] As a preferred embodiment of the present invention, the moisture content in the inert atmosphere is ≤1 ppm, and the oxygen content is ≤1 ppm.

[0029] As a preferred embodiment of the present invention, the inert atmosphere includes any one of helium atmosphere, argon atmosphere or nitrogen atmosphere, or a combination of at least two of them.

[0030] As a preferred embodiment of the present invention, the conductivity of the sulfide solid electrolyte meeting the application conditions is ≥10 ms / cm.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention determines the direct relationship between specific elements and electrical conductivity in a sulfide solid electrolyte to confirm the state of the sulfide electrolyte. The sulfide electrolyte is then subjected to secondary processing to restore its electrical conductivity to 10ms / cm, allowing it to be recycled and reused, thereby reducing waste and lowering costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The sulfide electrolyte Li stored for a long time in Example 1 of the present invention 5.5 S 4.5 PCl1.5 XRD test pattern;

[0034] Figure 2 The sulfide solid electrolyte Li recovered in Example 1 of the present invention 5.5 S 4.5 PCl 1.5 Impedance conductivity;

[0035] Figure 3 The sulfide electrolyte Li for long-term storage in Example 2 of the present invention 5.5 S 4.5 PCl 1.5 XRD test pattern. DETAILED DESCRIPTION

[0036] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, the present invention is further described in detail below. However, the following embodiments are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0037] The specific embodiment of the present invention provides a method for recycling sulfide solid electrolyte, which comprises:

[0038] (1) Determination of required components in spent sulfide solid electrolytes;

[0039] (2) Based on the determined required components, the failed sulfide solid electrolyte is processed to obtain a sulfide solid electrolyte whose conductivity meets the application conditions.

[0040] The sulfide solid electrolyte recycling method of the present invention is mainly aimed at sulfide solid electrolytes that have failed due to problems in the preparation process or storage.

[0041] As a preferred embodiment of the present invention, before step (1) determining the required components in the failed sulfide solid electrolyte, the method further includes the step of confirming whether the sulfide solid electrolyte is in a failed state, comprising: detecting the change in the S element content and the electrical conductivity in the sulfide solid electrolyte, and confirming that the sulfide solid electrolyte is in a failed state.

[0042] Sulfide solid electrolytes (SEs) contain air / water sensitive S 2-Ions and oxygen-loving P atoms are sensitive to air and water, leading to S loss during the preparation and storage processes, which in turn causes changes in ionic conductivity. The present invention has discovered that when the change in the S element in a sulfide solid electrolyte and the conductivity meet a certain relationship, the sulfide solid electrolyte is in a failed state. Sulfide SEs in this failed state can be recycled using the method described in the present invention, thereby reducing waste of sulfide SEs and lowering production costs.

[0043] As a preferred embodiment of the present invention, detecting the change in the S element content and the electrical conductivity in the sulfide solid electrolyte includes: when the change in the S element in the sulfide solid electrolyte is ≥10wt% and the electrical conductivity is ≤0.5mS / cm, the sulfide solid electrolyte is in a failed state.

[0044] As a preferred embodiment of the present invention, detecting the change in the S element content and the electrical conductivity in the sulfide solid electrolyte includes: when the change in the S element in the sulfide solid electrolyte is ≥20wt%, such as 20wt%, 30wt%, 40wt%, 50wt% or 60wt%, etc., but not limited to the listed values, other values not listed within the numerical range are also applicable; when the electrical conductivity is ≤1mS / cm, such as 1mS / cm, 0.8mS / cm, 0.6mS / cm, 0.4mS / cm or 0.2mS / cm, etc., but not limited to the listed values, other values not listed within the numerical range are also applicable, the sulfide solid electrolyte is in a failed state.

[0045] As a preferred embodiment of the present invention, determining the required components in the failed sulfide solid electrolyte in step (1) includes determining the lost components in the failed sulfide solid electrolyte, or the missing components after comparison with the target sulfide solid electrolyte.

[0046] In the present invention, the lost component refers to the effective component lost due to the reaction of the sulfide solid electrolyte due to problems in the preparation process or storage; the missing component after comparison with the target sulfide solid electrolyte refers to the missing component when the failed sulfide solid electrolyte is used to prepare another sulfide solid electrolyte, for example, when the failed Li 5.5 S 4.5 PCl 1.5 Preparation of Li 5.3 PS 4.3 ClBr 0.7 When additional components are required.

[0047] As a preferred embodiment of the present invention, in step (1), the required components in the failed sulfide solid electrolyte are determined by XRD determination and / or calcination method.

[0048] Specifically, by comparing the XRD patterns of the sulfide solid electrolyte before and after failure, the changes in the material content of the sulfide solid electrolyte before and after failure are judged, and the exact components are determined.

[0049] As a preferred embodiment of the present invention, the calcination method used in step (1) includes: placing the failed sulfide solid electrolyte in an inert atmosphere for calcination, and judging whether the P2S5 reaction is complete based on whether yellow droplets appear.

[0050] As a preferred embodiment of the present invention, the moisture content in the inert atmosphere is ≤1 ppm, and the oxygen content is ≤1 ppm.

[0051] As a preferred embodiment of the present invention, the inert atmosphere includes any one of helium atmosphere, argon atmosphere or nitrogen atmosphere, or a combination of at least two of them.

[0052] As a preferred embodiment of the present invention, the calcination temperature is 150°C to 600°C, for example, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C or 600°C, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0053] As a preferred embodiment of the present invention, the calcination time is 5 min to 20 h, for example, 5 min, 1 h, 3 h, 5 h, 7 h, 10 h, 13 h, 15 h, 17 h or 20 h, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0054] As a preferred embodiment of the present invention, the processing of the sulfide solid electrolyte in step (2) includes: adding the determined missing components to the failed sulfide solid electrolyte, mechanically crushing it, and calcining it to obtain a sulfide solid electrolyte whose electrical conductivity meets the application conditions.

[0055] As a preferred embodiment of the present invention, the mechanical crushing includes ball milling.

[0056] As a preferred embodiment of the present invention, the rotation speed of the ball mill is 350rpm to 600rpm, for example, 350rpm, 400rpm, 450rpm, 500rpm, 550rpm or 600rpm, but is not limited to the listed values. Other unlisted values within the numerical range are also applicable, preferably 500rpm.

[0057] As a preferred embodiment of the present invention, the ball milling time is 15h to 40h, for example, 15h, 20h, 25h, 30h, 35h or 40h, but is not limited to the listed values. Other unlisted values within the numerical range are also applicable, preferably 20h.

[0058] As a preferred embodiment of the present invention, the ball-to-material mass ratio of the ball mill is (3-10):1, for example, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc., but is not limited to the listed values. Other unlisted values within this numerical range are also applicable, preferably 5:1.

[0059] As a preferred embodiment of the present invention, the calcination temperature is 150°C to 600°C, for example, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C or 600°C, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0060] As a preferred embodiment of the present invention, the calcination time is 5 min to 20 h, for example, 5 min, 1 h, 3 h, 5 h, 7 h, 10 h, 13 h, 15 h, 17 h or 20 h, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.

[0061] As a preferred embodiment of the present invention, step (2) of processing the failed sulfide solid electrolyte is carried out under an inert atmosphere.

[0062] As a preferred embodiment of the present invention, the moisture content in the inert atmosphere is ≤1 ppm, and the oxygen content is ≤1 ppm.

[0063] As a preferred embodiment of the present invention, the inert atmosphere includes any one of helium atmosphere, argon atmosphere or nitrogen atmosphere, or a combination of at least two of them.

[0064] As a preferred embodiment of the present invention, the conductivity of the sulfide solid electrolyte meeting the application conditions is ≥10 ms / cm.

[0065] The following are typical but non-limiting examples of the present invention:

[0066] Example 1:

[0067] This embodiment provides a sulfide electrolyte Li for long-term storage. 5.5 S 4.5 PCl 1.5 A recycling method comprising the following steps:

[0068] (1) For long-term storage of sulfide electrolyte Li 5.5 S 4.5 PCl 1.5 Testing revealed a change in the S element of 25 wt% and a conductivity of 1 mS / cm, confirming that the long-stored sulfide solid electrolyte was in a failed state.

[0069] (2) Determination of missing components in failed sulfide solid electrolytes: In an argon dry atmosphere (water content less than 1 ppm, oxygen content less than 1 pmm), take a small amount of the spent electrolyte, press the mixed dry powder into a block material, put it into a quartz ceramic container, and then put it into a rapid heating electric furnace, bake it at 400 ° C for 6 hours, observe the interface of the quartz container, if there are yellow gas droplets on the inner surface of the quartz device, it is judged that P2S5 has not reacted completely, and cool it to room temperature; at the same time, the sulfide electrolyte Li stored for a long time is 5.5 S 4.5 PCl 1.5 Perform XRD test, such as Figure 1 As shown;

[0070] (3) Based on the missing components determined, the failed sulfide solid electrolyte was processed: in an argon dry atmosphere (water content less than 1 ppm, oxygen content less than 1 pmm), more than 200 g of electrolyte Li 5.5 S 4.5 PCl 1.5 2g of Li2S with a purity of more than 99wt% was mixed with Li 5.5 S 4.5 PCl 1.5 The powder was then placed in a ball mill with a ball-to-material weight ratio of 5:1 and subjected to high-energy ball milling at 500 rpm for 20 h. The powder was then pressed into a block and calcined at 550 ° C for 6 h in an argon dry atmosphere (moisture content less than 1 ppm, oxygen content less than 1 pmm) until no yellow material appeared, thereby obtaining a sulfide solid electrolyte Li 5.5 S 4.5 PCl 1.5 , its impedance conductivity is measured as Figure 2 As shown, the conductivity value at 25°C is calculated to be >10ms / cm.

[0071] Example 2:

[0072] This embodiment provides a sulfide electrolyte Li for long-term storage. 5.5 S 4.5 PCl 1.5 Recycling and preparation of Li 5.3 PS 4.3 ClBr 0.7 The method comprises the following steps:

[0073] (1) For long-term storage of sulfide electrolyte Li 5.5 S 4.5 PCl 1.5Testing revealed a 30 wt% change in the S element and a conductivity of 1 mS / cm, confirming that the long-stored sulfide solid electrolyte was in a failed state.

[0074] (2) Determination of missing components in failed sulfide solid electrolytes: Li 5.5 S 4.5 PCl 1.5 Perform XRD test, such as Figure 3 As shown;

[0075] (3) Based on the missing components determined, the failed sulfide solid electrolyte is processed: Based on the measurement results, the ingredients are prepared: Li 5.5 S 4.5 PCl 1.5 150g, Li2S 31.828g, P2S550.224g, LiCl 7.109g, LiBr61.464g, the ingredients were mixed and placed in a ball mill with a ball-to-material weight ratio of 5:1. The high-energy ball milling was carried out at 500rpm for 20h. The powder was then pressed into blocks and calcined at 400℃ for 10h in an argon dry atmosphere (moisture content less than 1ppm, oxygen content less than 1pm). After sintering, a trace amount of yellow material was still observed on the inner surface of the quartz container, indicating that P2S5 had not reacted completely. The mixture was cooled to room temperature and tested for 2 The conductivity value at 5°C is >6ms / cm; further, more than 200g of P2S5 electrolyte that has not reacted completely is taken, 2g of Li2S with a purity of more than 99wt% is added, and then placed in a ball mill with a ball-to-material weight ratio of 5:1, and high-energy ball milling is performed at a speed of 500rpm for 20h. The powder is then pressed into a block and calcined at 460°C for 10h in an argon dry atmosphere (moisture content less than 1ppm, oxygen content less than 1pmm) to obtain a sulfide solid electrolyte Li 5.3 PS 4.3 ClBr 0.7 , calculated that its conductivity value at 25℃ is >10ms / cm.

[0076] The applicant declares that the present invention uses the above-described embodiments to illustrate the detailed process equipment and process flow of the present invention. However, the present invention is not limited to the above-described detailed process equipment and process flow, and does not necessarily rely on the above-described detailed process equipment and process flow in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for the raw materials of the present invention's products, additions of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for recycling sulfide solid electrolyte, characterized in that: The recycling method comprises: (1) Determination of required components in spent sulfide solid electrolytes; (2) Based on the determined required components, the failed sulfide solid electrolyte is processed to obtain a sulfide solid electrolyte whose conductivity meets the application conditions.

2. The recycling method according to claim 1, characterized in that: Before step (1) of determining the required components in the failed sulfide solid electrolyte, the method further includes the step of confirming whether the sulfide solid electrolyte is in a failed state, comprising: detecting the change in the S element content and the electrical conductivity in the sulfide solid electrolyte, and confirming that the sulfide solid electrolyte is in a failed state; Preferably, detecting the change in the S element content and the electrical conductivity in the sulfide solid electrolyte includes: when the change in the S element in the sulfide solid electrolyte is ≥10wt% and the electrical conductivity is ≤0.5mS / cm, the sulfide solid electrolyte is in a failed state; Preferably, detecting the change in the S element content and the electrical conductivity in the sulfide solid electrolyte includes: when the change in the S element in the sulfide solid electrolyte is ≥20wt% and the electrical conductivity is ≤1mS / cm, the sulfide solid electrolyte is in a failed state.

3. The recycling method according to claim 1, characterized in that: Determining the desired components in the failed sulfide solid electrolyte in step (1) includes determining the lost components in the failed sulfide solid electrolyte, or the missing components after comparison with the target sulfide solid electrolyte; Preferably, the required components in the failed sulfide solid electrolyte are determined in step (1) by XRD determination and / or calcination method.

4. The recycling method according to claim 3, characterized in that: The roasting method includes: placing the failed sulfide solid electrolyte in an inert atmosphere for roasting, and judging whether the P2S5 reaction is complete based on whether yellow droplets appear.

5. The recycling method according to claim 4, characterized in that: The moisture content in the inert atmosphere is ≤1ppm, and the oxygen content is ≤1ppm; Preferably, the inert atmosphere comprises any one of helium atmosphere, argon atmosphere or nitrogen atmosphere, or a combination of at least two thereof; Preferably, the calcination temperature is 150°C to 600°C; Preferably, the calcination time is 5 minutes to 20 hours.

6. The recycling method according to claim 1, characterized in that: The processing of the sulfide solid electrolyte in step (2) includes: adding the determined missing components to the failed sulfide solid electrolyte, mechanically crushing it, and calcining it to obtain a sulfide solid electrolyte whose conductivity meets the application conditions.

7. The recycling method according to claim 6, characterized in that: The mechanical crushing includes ball milling; Preferably, the ball milling speed is 350 rpm to 600 rpm, preferably 500 rpm; Preferably, the ball milling time is 15h to 40h, preferably 20h; Preferably, the ball-to-material mass ratio of the ball mill is (3-10):1, preferably 5:

1.

8. The recycling method according to claim 6, characterized in that: The calcination temperature is 150°C to 600°C; Preferably, the calcination time is 5 minutes to 20 hours.

9. The recycling method according to claim 1, characterized in that: Step (2) processing the failed sulfide solid electrolyte is carried out under an inert atmosphere; Preferably, the moisture content in the inert atmosphere is ≤1 ppm, and the oxygen content is ≤1 ppm; Preferably, the inert atmosphere includes any one of helium atmosphere, argon atmosphere or nitrogen atmosphere, or a combination of at least two of them.

10. The recycling method according to claim 1, characterized in that: The conductivity of the sulfide solid electrolyte that meets the application conditions is ≥10ms / cm.

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