Sulfide-type electrolyte precursor, method for producing same, sulfide-type electrolyte, secondary battery, and electric device

Abstract

The application discloses a sulfide electrolyte precursor and a preparation method thereof, a sulfide electrolyte, a secondary battery and an electric device. The preparation method of the sulfide electrolyte precursor comprises the following steps: placing raw materials in a first tank in an inert atmosphere according to a stoichiometric ratio, performing first mixing treatment through a tank mill to obtain a mixed material; transferring the mixed material to a second tank in an inert atmosphere, performing second mixing treatment through a three-dimensional mixer to obtain the sulfide electrolyte precursor; and supplementing sulfur to the mixed material in the process of the second mixing treatment. The preparation method of the sulfide electrolyte precursor provided by the application greatly reduces the energy consumption of equipment and the production cost, and can realize large-scale production of the sulfide electrolyte.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte technology, and in particular to a sulfide-type electrolyte precursor and its preparation method, a sulfide-type electrolyte, a secondary battery, and electrical equipment. Background Technology

[0002] Sulfide electrolytes are a class of solid electrolyte materials that have recently attracted attention. They typically have high ionic conductivity and good ductility, and can form relatively dense physical contacts with positive and negative electrode materials. Solid-state batteries made from sulfide electrolytes have high initial efficiency and rate performance. Therefore, all-solid-state batteries using sulfide electrolytes are the technology most likely to realize a battery revolution, and the preparation technology of sulfide electrolytes is of paramount importance.

[0003] Currently, common methods for preparing sulfide electrolytes can be divided into two types: liquid-phase reaction and solid-phase reaction. Liquid-phase reaction has a simpler process and is easier to scale up, but the resulting electrolyte has lower purity and performance, and residual solvents and other impurities cause significant side reactions in the battery, severely impacting battery performance. In contrast, solid-phase reaction produces electrolytes with higher purity and superior performance, resulting in better-performing assembled batteries. However, its preparation process is complex, requires high energy consumption, and is difficult to scale up, thus becoming a significant factor restricting the rapid development of the entire industry chain. Summary of the Invention

[0004] This invention provides a method for preparing a sulfide-type electrolyte precursor, which greatly reduces equipment energy consumption and production costs, and enables large-scale production of sulfide electrolytes.

[0005] In a first aspect, the present invention provides a method for preparing a sulfide-type electrolyte precursor, comprising the following steps:

[0006] The raw materials, in stoichiometric proportions, are placed in the first tank under an inert atmosphere and subjected to the first mixing process through a tank mill to obtain a mixture.

[0007] The mixture is transferred to a second tank under an inert atmosphere and subjected to a second mixing process using a three-dimensional mixer to obtain the sulfide-type electrolyte precursor.

[0008] In the second mixing process, sulfur is added to the mixture.

[0009] Furthermore, during the first mixing process:

[0010] The raw materials include Li₂S, P₂S₅, and LiM, wherein M is selected from Cl. - I - F - ,Br- One or more of the following; and / or,

[0011] The ball-to-material ratio in the first hopper is (10-30):1; and / or,

[0012] The roller speed of the mill is 50–100 rpm, and the first mixing treatment time is 4–8 hours; and / or,

[0013] The particle size of the mixture is no greater than 50 μm.

[0014] Furthermore, during the second mixing process:

[0015] The spindle speed of the three-dimensional mixer is 2–13 rpm; and / or,

[0016] Prior to the sulfur replenishment, the mixing time of the three-dimensional mixer is 2–6 hours; and / or,

[0017] After the sulfur replenishment, the three-dimensional mixer continues mixing for 2–6 hours; and / or,

[0018] The sulfur source for the sulfur replenishment includes one or more of Li₂S, S, and P₂S₅; and / or,

[0019] The amount of sulfur source added is 0.8 wt% to 5 wt% of the mixture.

[0020] Furthermore, the amount of sulfur source added is 3 wt% to 3.5 wt% of the mixture.

[0021] Furthermore, the amount of sulfur source added is 3.15 wt% to 3.35 wt% of the mixture.

[0022] Secondly, the present invention provides a sulfide-type electrolyte precursor prepared by the aforementioned preparation method.

[0023] Thirdly, the present invention provides a sulfide-type electrolyte, which is obtained by heat treatment of the aforementioned sulfide-type electrolyte precursor under an inert atmosphere.

[0024] Furthermore, the chemical formula of the sulfide-type electrolyte is Li. 7-x PS 6-x M x Where M is selected from Cl - I - F - ,Br - One or more of the following, where 0.1 ≤ x ≤ 5.9.

[0025] Furthermore, the heat treatment temperature is 450℃~550℃, the heat treatment holding time is 6~12h, and the heat treatment heating rate is 1~5℃ / min.

[0026] Furthermore, after the heat treatment, the process also includes grinding and sieving the sulfide-type electrolyte.

[0027] Furthermore, after the grinding and sieving, the particle size of the sulfide-type electrolyte is no greater than 50 μm.

[0028] Fourthly, the present invention provides a secondary battery comprising a positive electrode layer, an electrolyte layer, and a negative electrode layer, wherein at least one of the positive electrode layer, the electrolyte layer, and the negative electrode layer comprises the aforementioned sulfide-type electrolyte;

[0029] The secondary battery includes a semi-solid lithium secondary battery and an all-solid lithium secondary battery.

[0030] Fifthly, the present invention provides an electrical device including the aforementioned secondary battery.

[0031] Through one or more embodiments of the above embodiments of the present invention, at least the following technical effects can be achieved:

[0032] 1. The novel solid-phase preparation process for sulfide-type electrolyte precursors provided by this invention employs a low-speed mixing and dispersion method. Compared with the conventional high-energy ball milling process, this not only significantly reduces equipment energy consumption and thus lowers costs during the preparation process, but also avoids the need for continuous manual scraping during the preparation process, simplifying the preparation flow and enabling continuous preparation.

[0033] 2. The low-energy-consumption preparation method provided by this invention is beneficial for equipment scale-up and process control, enabling large-scale production of sulfide electrolytes, thereby promoting the rapid development and commercial application of the entire solid-state battery industry.

[0034] 3. The sulfide-type electrolyte prepared by this invention has performance that is basically equivalent to that of products prepared by conventional high-energy ball milling. Attached Figure Description

[0035] The technical solution and other beneficial effects of the present invention will become apparent from the following detailed description of specific embodiments of the invention, in conjunction with the accompanying drawings.

[0036] Figure 1 XRD diffraction patterns of the sulfide electrolytes prepared in Examples 1-4;

[0037] Figure 2 XRD diffraction patterns of the sulfide-type electrolytes prepared in Examples 5-8;

[0038] Figure 3 XRD diffraction patterns of the sulfide-type electrolytes prepared in Examples 9-10;

[0039] Figure 4 The XRD diffraction patterns are for the sulfide-type electrolytes prepared in Comparative Examples 1-3. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0041] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the term "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, the character " / " in this document, unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship.

[0042] As mentioned in the background section, for sulfide-type electrolytes, electrolytes prepared by solid-state reaction methods have higher purity and better performance. However, current solid-state reaction methods generally employ a process of high-energy ball milling followed by sintering. High-energy ball milling not only consumes a lot of energy and involves a cumbersome preparation process, but it is also difficult to achieve large-scale production, thus hindering the rapid development of sulfide-type electrolytes.

[0043] To address this technical problem, the inventors have developed a solid-phase reaction preparation method suitable for sulfide electrolytes. This method is not only energy-efficient but also easy to produce in large quantities, thus overcoming the various shortcomings of traditional solid-phase reaction methods. The preparation method of this invention is described in detail below.

[0044] The sulfide-type electrolyte described in this invention may have the chemical formula Li. 7-x PS 6-x M x Where M is a halogen element, which can be selected from Cl. - I - F - ,Br - One or more of the following, where 0.1 ≤ x ≤ 5.9. Depending on the values ​​of x and M, the sulfide-type electrolyte has different chemical formulas. For example, in some embodiments of the invention, when M is selected as Cl... - When x = 1.6, the chemical formula of the electrolyte is Li.5.4 PS 4.4 Cl 1.6 .

[0045] The above-mentioned sulfide-type electrolyte Li 7-x PS 6-x M x It is obtained by partially substituting the sulfur element in Li7PS6 with halogens such as F, Cl, Br, and I, and this substitution process does not change the crystal form of Li7PS6, thus endowing Li with... 7-x PS 6-x M x Good thermal stability and electrochemical performance. Li 7-x PS 6-x M x When used as an electrolyte material, the requirements for its performance are high purity and good conductivity.

[0046] The following section uses sulfide-type electrolyte Li 7-x PS 6-x M x The present invention will be described in detail using Li as an example. Those skilled in the art should understand that the preparation method described in this invention is not limited to Li 7-x PS 6-x M x This is a sulfide-type electrolyte.

[0047] First, this invention provides a method for preparing a sulfide-type electrolyte precursor, specifically including the following steps:

[0048] S1. Li2S, P2S5, and LiM are placed in a first material tank under an inert atmosphere and mixed using a tank mill to obtain a mixture.

[0049] S2. The mixture is transferred to a second tank under an inert atmosphere and subjected to a second mixing process using a three-dimensional mixer to obtain a sulfide-type electrolyte precursor.

[0050] In step S1 above, Li 7-x PS 6-x M x For example, the raw materials for preparing sulfide-type electrolyte precursors can be Li₂S, P₂S₅, LiM (LiF, LiCl, LiBr, LiI, etc.). When preparing the raw materials, Li₂S, P₂S₅, and LiM need to be proportioned according to the Li… 7-x PS 6-x M x The ingredients are prepared according to the stoichiometric ratio of the elements.

[0051] Because raw materials readily react with moisture in the air, introducing impurities and reducing product purity, subsequent steps must be performed under a protective atmosphere to eliminate the influence of moisture. The protective atmosphere can be one of inert gases such as nitrogen or argon, or a mixture of at least two gases. In one embodiment of the invention, some operations involving the raw materials can be performed in a glove box.

[0052] Unlike existing high-energy ball milling methods, this invention first performs canning on the raw materials. Canning is carried out using a canning mill, with the GMS5-2 model being a suitable option. The canning mill uses rubber rollers to rotate the grinding jar optimally, causing the grinding balls within the jar to disperse the material in a cascading motion, achieving the best grinding effect and quickly grinding the material to the micron level. The purpose of canning in this invention is twofold: firstly, to refine the particle size of various electrolyte raw materials, normalizing the particle size and ensuring closer contact between particles; and secondly, to serve as a preliminary mixing process.

[0053] The specific operation process of the can mill is as follows: First, under an inert atmosphere, the weighed raw materials are placed in the first material container (which can be a ball mill container), the container is covered and sealed, and then placed on the roller of the can mill. The can mill is started, and the movement of the roller drives the first material container to rotate. The first material container contains grinding balls, which move regularly within the first material container to achieve grinding, refining, and preliminary mixing of the raw materials.

[0054] In this invention, the ball-to-material ratio in the first material tank can be set to (10-30):1, for example, it can be any value or a range of any two values ​​from 10:1, 12:1, 15:1, 16:1, 18:1, 20:1, 22:1, 24:1, 25:1, 28:1, 30:1.

[0055] In this invention, the roller speed of the mill can be set to 50-100 rpm, for example, any value or a range of any two values ​​among 50 rpm, 55 rpm, 60 rpm, 65 rpm, 70 rpm, 75 rpm, 80 rpm, 85 rpm, 90 rpm, 95 rpm, and 100 rpm.

[0056] It should be noted that, compared with the high rotation speed of ordinary high-energy ball mills (generally above 300 rpm), the can milling process in this invention uses a lower roller speed. The low-speed mixing not only greatly reduces the energy consumption of the equipment, but also avoids phenomena such as sticking to the wall and sedimentation. There is no need for manual scraping during the mixing process, which is conducive to the continuity of the preparation process.

[0057] In this invention, the ball milling time of the ball mill can be controlled within 4 to 8 hours, for example, it can be any value among 4 hours, 5 hours, 6 hours, 7 hours, and 8 hours, or a range consisting of any two of these values.

[0058] After the above-mentioned grinding process, the raw materials are initially mixed, and the particle size of the raw materials is refined, with the overall particle size controllable within the range of 50μm.

[0059] In step S2 above, the mixture obtained after the can milling process is further subjected to three-dimensional low-speed dispersion mixing. Similarly, to avoid the raw materials reacting with moisture in the air, this step also needs to be carried out under the protection of an inert atmosphere.

[0060] The mixing equipment used in this step is a three-dimensional mixer, with the S-5L model being a selectable option. The mixing principle of the three-dimensional mixer is as follows: the mixer drives the dispersion tank mounted on it to perform unique, irregular movements such as translation, rotation, and rocking in three-dimensional space. This causes the material within the dispersion tank to be in a complex motion state of "rotational flow-translation-inverted fall," where each particle constantly changes its position during frequent movement and diffusion, accelerating flow and diffusion, resulting in a satisfactory mixing effect. Compared to ordinary mixing equipment, the three-dimensional mixer has more mixing points within the dispersion tank, resulting in a significantly improved mixing effect and higher uniformity than conventional mixers.

[0061] In this invention, a second mixing process is carried out by a three-dimensional mixer. Since all parts of the three-dimensional mixer have rounded transitions without dead corners, and the dispersion tank moves in multiple directions, the material is basically free from centrifugal force, and there is no segregation, stratification, or agglomeration. This ensures that all kinds of raw materials are dispersed and mixed evenly.

[0062] In this invention, the specific operation process of the three-dimensional mixer is as follows: under the protection of an inert atmosphere, the mixture in the first material tank is transferred to the second material tank (which can be a dispersion tank), the tank lid is covered and sealed, and then placed on the three-dimensional mixer. The three-dimensional mixer is then started to disperse and mix the mixture.

[0063] In this invention, the spindle speed of the three-dimensional mixer is 2 to 13 rpm, for example, it can be any value or a range of any two values ​​among 2 rpm, 3 rpm, 4 rpm, 5 rpm, 6 rpm, 7 rpm, 8 rpm, 9 rpm, 10 rpm, 11 rpm, 12 rpm, and 13 rpm.

[0064] Similarly, the three-dimensional mixer in this invention uses a low rotation speed, which greatly reduces the energy consumption of the equipment. On the other hand, the three-dimensional low-speed mixing method without dead angles eliminates the need for manual scraping and mixing, enabling uninterrupted and continuous electrolyte preparation and improving preparation efficiency.

[0065] It is important to note that when using traditional high-energy ball milling for mixing, the raw materials are in a high surface energy state during the grinding and mixing process, leading to mutual reactions between the materials and the formation of a stable electrolyte precursor. Thus, during subsequent high-temperature heat treatment, the sulfur element in the electrolyte precursor will not be lost due to sublimation, resulting in a stable sulfide-type electrolyte, Li. 7-x PS 6-x M x It is a pure phase.

[0066] However, when using a can mill and a three-dimensional mixer for low-speed mixing, only uniform mixing of the raw materials can be ensured, but the materials cannot react completely to form a stable state. Therefore, during subsequent high-temperature heat treatment, the sulfur (S) in the mixture is easily sublimated, resulting in S loss. This S loss further leads to the formation of a sulfide-type electrolyte, Li. 7- x PS 6-x M x The low electrical conductivity and impure phase severely affect the battery's performance.

[0067] To address this problem, the inventors discovered that adding a certain amount of sulfur during the mixing process of a three-dimensional mixer (i.e., sulfur supplementation) can compensate for the sulfur loss during high-temperature heat treatment of low-speed mixing materials, thus solving the problem of sulfur-type electrolytes Li 7-x PS 6-x M x Problems include low electrical conductivity and impure phases.

[0068] In this invention, the timing of sulfur replenishment is not arbitrary. For example, performing sulfur replenishment during the grinding process will not achieve the desired effect. Sulfur replenishment needs to be added during the dispersion and mixing process in a three-dimensional mixer. This ensures thorough mixing of the added sulfur with the raw materials, which is beneficial for improving the purity and conductivity of the finished product. Preferably, sulfur replenishment is performed 2–6 hours after dispersion and mixing in the three-dimensional mixer. For example, any value from 2 hours, 3 hours, 4 hours, 5 hours, and 6 hours, or any range of any two values, can be used for initial dispersion and mixing.

[0069] It should be noted that the sulfur replenishment process also needs to be carried out under the protection of an inert atmosphere. The specific operation procedure is as follows: take out the second material tank from the three-dimensional mixer, open the tank cover under an inert atmosphere, add the predetermined amount of sulfur source, then close the tank cover and seal it, and reinstall it on the three-dimensional mixer.

[0070] In this invention, the sulfur source for sulfur supplementation includes, but is not limited to, one or more of Li₂S, S, and P₂S₅. The amount of sulfur added needs to be determined based on the amount of mixture in the second tank. The amount of sulfur added should not be too low or too high, as both will lead to an imbalance in the elemental ratio in the mixture, which in turn will result in an impure phase in the synthesized electrolyte product. Generally, the amount of sulfur source added can be 0.8wt% to 5wt% of the mixture, for example, any value or a range of any two values ​​from 0.8wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, and 5wt%.

[0071] Furthermore, the amount of sulfur source added can be 3 wt% to 3.5 wt% of the mixture, for example, any value or a range of any two of 3 wt%, 3.1 wt%, 3.2 wt%, 3.3 wt%, 3.4 wt%, and 3.5 wt%.

[0072] Furthermore, the amount of sulfur source added can be 3.15 wt% to 3.35 wt% of the mixture, for example, any value or a range of any two of 3.15 wt%, 3.2 wt%, 3.25 wt%, 3.3 wt%, and 3.35 wt%. When the amount of sulfur added is within this range, the resulting electrolyte product is essentially pure phase with high conductivity and excellent performance.

[0073] After the sulfur replenishment treatment, the three-dimensional mixer is started to continue low-speed three-dimensional mixing to ensure that the added sulfur source is thoroughly and evenly mixed with the raw materials. The mixing time can be 2 to 6 hours, for example, any value from 2 hours, 3 hours, 4 hours, 5 hours, and 6 hours, or any combination of any two of these values.

[0074] Secondly, this invention provides a sulfide-type electrolyte, obtained by calcining the aforementioned sulfide-type electrolyte precursor under an inert atmosphere. The specific preparation process involves transferring the sulfide-type electrolyte precursor to a sintering furnace (e.g., a muffle furnace) and subjecting it to high-temperature heat treatment under an inert atmosphere. During this high-temperature heat treatment, the raw materials undergo a chemical reaction to generate the sulfide-type electrolyte Li. 7-x PS 6-x M x .

[0075] Compared with the traditional high-energy ball milling method, the heat treatment process in this invention sets a slightly higher temperature to ensure sufficient reaction between the raw materials. Generally, the heat treatment temperature can be set to 450℃~550℃, for example, any value or a range of any two of the following: 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃, and 550℃.

[0076] In this invention, the heating rate of the heat treatment is not limited and can generally be set to 1 to 5℃ / min, for example, any value or a range of any two of 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, and 5℃ / min.

[0077] In this invention, the heat treatment holding time can be set to 6–12 hours to ensure sufficient reaction between the raw materials. In some embodiments, the holding time can be any value from 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, and 12 hours, or a range consisting of any two of these values.

[0078] After the above high-temperature heat treatment, the product is cooled to obtain a crude electrolyte product. Further, the crude electrolyte product is ground and sieved to obtain a finished electrolyte product with an overall particle size ≤50μm.

[0079] The sulfide-type electrolyte material prepared by this invention can have a crystal phase that is either a glass-ceramic phase or a crystalline phase. Preferably, the conductivity of this sulfide-type electrolyte material is ≥6 mS / cm.

[0080] The present invention also provides a secondary battery, comprising a positive electrode layer, an electrolyte layer, and a negative electrode layer, wherein one or more of the positive electrode layer, electrolyte layer, and negative electrode layer comprise the aforementioned sulfide-type electrolyte material. The aforementioned secondary battery includes, but is not limited to, semi-solid-state lithium secondary batteries and all-solid-state lithium secondary batteries.

[0081] The present invention also provides an electrical device comprising the aforementioned secondary battery, and using the secondary battery as the power supply for the electrical device. In some embodiments, the electrical device of the present invention includes, but is not limited to: a backup power supply, a motor, an electric vehicle, an electric motorcycle, a power-assisted bicycle, a bicycle, power tools, and a large household storage battery.

[0082] The present application will be further described below with reference to embodiments and comparative examples. These embodiments and comparative examples should not be construed as limiting the technical solutions of the present application.

[0083] Example 1

[0084] (1) Under the protection of argon atmosphere, 1.9 mol Li2S, 0.5 mol P2S5 and 1.6 mol LiCl were weighed in molar ratio, placed in a ball mill jar, sealed well and then refined by jar milling with a roller speed of 80 rpm for 4 h to obtain precursor 1#.

[0085] (2) Precursor 1# was transferred to a dispersion tank under an argon atmosphere, sealed, and then subjected to three-dimensional low-speed dispersion and mixing. The spindle speed was 6 rpm and the mixing time was 8 h to obtain precursor 2#.

[0086] (3) Precursor 2# was subjected to 0.5% Li2S sulfur replenishment under argon atmosphere. After sulfur replenishment, three-dimensional low-speed dispersion was continued. The spindle speed was 6 rpm and the mixing time was 4 h to obtain precursor 3#.

[0087] (4) Precursor 3# was subjected to high-temperature heat treatment in an argon atmosphere using a muffle furnace at a temperature of 500℃, a temperature rise rate of 2℃ / min, and a holding time of 10h. After natural cooling, a crude electrolyte product was obtained. The crude product was then ground and sieved to obtain an electrolyte product Li with a sulfur content of 0.8%. 5.4 PS 4.4 Cl 1.6 .

[0088] Examples 2 to 10

[0089] The difference between Examples 2-10 and Example 1 is that the amount of sulfur added is different. For the specific amount of sulfur added, the corresponding conductivity and phase information for each example, please refer to Table 1.

[0090] Comparative Example 1

[0091] The difference between Comparative Example 1 and Example 1 is that no sulfur supplementation was performed.

[0092] Comparative Example 2

[0093] The difference between Comparative Example 2 and Example 7 is that the sulfur replenishment time was changed; sulfur replenishment was performed during the ingredient preparation process. The specific process is as follows:

[0094] (1) Under the protection of argon atmosphere, 1.9 mol Li2S, 0.5 mol P2S5 and 1.6 mol LiCl were weighed in molar ratio, and 3.25% Li2S sulfur supplement was added together and placed in a ball mill jar. After sealing well, the jar mill was used for jar milling and refining. The roller speed was 80 rpm and the time was 4 h to obtain precursor 1#.

[0095] (2) Precursor 1# was transferred to a dispersion tank under an argon atmosphere, sealed, and then subjected to three-dimensional low-speed dispersion and mixing. The spindle speed was 6 rpm and the mixing time was 8 h to obtain precursor 2#.

[0096] (3) Precursor 2# was subjected to high-temperature heat treatment in an argon atmosphere using a muffle furnace at a temperature of 500℃, a temperature rise rate of 2℃ / min, and a holding time of 10h. After natural cooling, a crude electrolyte product was obtained. The crude product was then ground and sieved to obtain an electrolyte product Li with a sulfur content of 3.25%. 5.4 PS 4.4 Cl 1.6 .

[0097] Comparative Example 3

[0098] The difference between Comparative Example 3 and Examples 1-10 is that Li was prepared using a conventional high-energy ball milling process. 5.4 PS 4.4 Cl 1.6 No sulfur supplementation is required, as detailed below:

[0099] Under an argon atmosphere, 1.9 mol Li₂S, 0.5 mol P₂S₅, and 1.6 mol LiCl were weighed in a molar ratio and placed in a ball mill jar. After sealing, the jar was ball-milled at a ball-to-material ratio of 20:1 for 25 hours at a milling speed of 660 rpm. The resulting electrolyte precursor was then subjected to high-temperature heat treatment in a muffle furnace under an argon atmosphere at 500℃, a temperature rise rate of 2℃ / min, and a holding time of 10 hours. After natural cooling, a crude electrolyte product was obtained. This crude product was then ground and sieved to obtain the final electrolyte product, LiCl. 5.4 PS 4.4 Cl 1.6 .

[0100] Performance testing

[0101] 1. Conductivity test

[0102] 100 mg of electrolyte powder was weighed and placed in an insulating sleeve with an inner diameter of 10 mm. It was then pressurized at 300 MPa and shaped. An AC impedance spectroscopy test was performed to measure the impedance value of the electrolyte material. The thickness of the pressurized sheet electrolyte was then measured. Based on the sheet impedance value, thickness, and area, the ionic conductivity of the electrolyte material was calculated using the formula σ = d / (R*S). Where: σ is the ionic conductivity (s / cm); d is the sheet thickness (cm); R is the impedance value (Ω); and S is the sheet area (cm²). 2 The results are shown in Table 1.

[0103] 2. Battery Testing

[0104] Inside an argon glove box, Li3InCl6 electrolyte and positive electrode active material Li(Ni) are... 0.8 Co 0.1 Mn 0.1O2 (NCM811) was weighed at a weight ratio of 20:80. The mixture was ground uniformly using an agate mortar, thus preparing the composite cathode material. In an insulating outer cylinder with a diameter of 10 mm, 14 mg of the above composite cathode material and 70 mg of Li were mixed... 5.4 PS 4.4 Cl 1.6 The electrolyte is stacked. It is then pressurized at 360 MPa to form the positive electrode and solid electrolyte layer. Next, an aluminum foil is stacked on the positive electrode side, forming a current collector. Then, on the opposite side of the solid electrolyte layer that contacts the positive electrode, an indium sheet with a thickness of 200 μm and a diameter of 10 mm is placed as the negative electrode material. It is then pressurized at 80 MPa to produce a stack consisting of a positive electrode, a solid electrolyte layer, and a negative electrode. Stainless steel current collectors are then placed on the top and bottom of the stack, and current collector leads are attached to the current collectors. The assembled solid-state battery is subjected to cycle performance testing under the following conditions: current density of 1C and voltage range of 2.7–4.3 V (Li). + The results are shown in Table 2.

[0105] 3. XRD Testing

[0106] The prepared sulfide-type solid electrolyte was subjected to XRD analysis. The sample preparation method for XRD analysis was as follows:

[0107] Prepare a glass slide with square grooves (10 mm in length and 0.2–0.5 mm in depth). Place an appropriate amount of electrolyte powder into the grooves, flatten it with a powder-pressing slide, and scrape off any excess powder, ensuring the powder surface is flush with the main surface of the slide. Then, seal the slide with 20 μm or 30 μm thick polyimide tape, ensuring the tape surface is smooth and wrinkle-free during sealing to minimize the impact of the sealing tape on the test results. Perform XRD testing on the prepared samples using the following parameters: test angle (10–80)° and scanning speed 1° / min. The results are as follows: Figures 1-4 As shown in Table 1.

[0108] Table 1. Conductivity and phase information of sulfide-type electrolytes prepared in the examples and comparative examples.

[0109] Group Sulfur supplementation amount - electrolyte components electrical conductivity XRD Example 1 <![CDATA[0.8%-Li 5.4 PS 4.4 Cl 1.6 ]]> 3.4ms / cm Obvious heterogeneous phase Example 2 <![CDATA[1%-Li 5.4 PS 4.4 Cl 1.6 ]]> 1.5ms / cm Obvious heterogeneous phase Example 3 <![CDATA[2%-Li 5.4 PS 4.4 Cl 1.6 ]]> 5.2ms / cm Obvious heterogeneous phase Example 4 <![CDATA[2.5%-Li 5.4 PS 4.4 Cl 1.6 ]]> 4.9ms / cm Obvious heterogeneous phase Example 5 <![CDATA[2.75%-Li 5.4 PS 4.4 Cl 1.6 ]]> 5.1ms / cm Obvious heterogeneous phase Example 6 <![CDATA[3%-Li 5.4 PS 4.4 Cl 1.6 ]]> 6.7ms / cm Slight heterogeneous phase Example 7 <![CDATA[3.25%-Li 5.4 PS 4.4 Cl 1.6 ]]> 8.9ms / cm Pure phase Example 8 <![CDATA[3.5%-Li 5.4 PS 4.4 Cl 1.6 ]]> 6.0ms / cm Slight heterogeneous phase Example 9 <![CDATA[4%-Li 5.4 PS 4.4 Cl 1.6 ]]> 4.7ms / cm Obvious heterogeneous phase Example 10 <![CDATA[5%-Li 5.4 PS 4.4 Cl 1.6 ]]> 4.8ms / cm Obvious heterogeneous phase Comparative Example 1 <![CDATA[0%-Li 5.4 PS 4.4 Cl 1.6 ]]> 1.5ms / cm Obvious heterogeneous phases and strong peaks Comparative Example 2 <![CDATA[3.25%-Li 5.4 PS 4.4 Cl 1.6 ]]> 6.2ms / cm Slight heterogeneous phase Comparative Example 3 <![CDATA[Li 5.4 PS 4.4 Cl 1.6 ]]> 9ms / cm Pure phase

[0110] Please refer to Table 1 and Figure 1-4 Comparative Example 1 used the preparation process of this invention, but without sulfur supplementation. The results showed that the prepared Li... 5.4 PS 4.4 Cl 1.6The presence of a distinct impurity phase and strong peaks in the electrolyte indicates low product purity and low conductivity, only 1.5 ms / cm. This underscores the necessity of sulfur supplementation when using the preparation process of this invention.

[0111] Comparative examples 1-10 show that when the sulfur supplementation amount is less than 3.25 wt%, as the sulfur supplementation amount increases, Li 5.4 PS 4.4 Cl 1.6 The impurity phase in the electrolyte gradually decreases, and the overall conductivity shows a gradual increasing trend. However, when the sulfur addition exceeds 3.25 wt%, the Li... 5.4 PS 4.4 Cl 1.6 The impurity phase in the electrolyte gradually increases, while the overall conductivity shows a gradual decreasing trend. Specifically, when the sulfur addition is 3.25 wt%, the prepared Li... 5.4 PS 4.4 Cl 1.6 The electrolyte is a pure phase and has a conductivity of 8.9 ms / cm, which is the optimal embodiment.

[0112] Comparing Example 7 and Comparative Example 2, it can be seen that the timing of sulfur supplementation has a significant impact on the performance of the electrolyte. In Comparative Example 2, sulfur supplementation was performed first, followed by low-speed can milling and low-speed three-dimensional mixing to prepare Li 5.4 PS 4.4 Cl 1.6 The electrolyte exhibited a slight impurity phase and had a conductivity of 6.2 mS / cm, both lower than those in Example 7. Therefore, this invention determines that sulfur replenishment should be performed during the low-speed three-dimensional mixing process.

[0113] Please refer to Example 7 and Comparative Example 3. Using the preparation process of the present invention, when the sulfur supplementation amount is 3.25 wt%, the prepared Li 5.4 PS 4.4 Cl 1.6 The electrolyte is comparable to that of the existing process in terms of both purity and conductivity, and can replace the existing process to prepare sulfide-type electrolytes.

[0114] Table 2. Electrochemical performance test results of the electrolytes in Example 7 and Comparative Example 3.

[0115]

[0116] Please refer to Table 2. The battery assembled using the electrolyte prepared in Example 7 achieved a 1C first-cycle discharge capacity of 205 mAh / g, a 1C first-cycle coulombic efficiency of 92.3%, and a 1C cycle count@capacity retention of 792 cycles@80%. These performance indicators are basically no different from those of the electrolyte in Comparative Example 3, proving the feasibility of the new sulfide-type electrolyte preparation process provided by this invention.

[0117] In summary, although the present invention has been disclosed above with reference to preferred embodiments, the above preferred embodiments are not intended to limit the present invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims.

Claims

1. A method for producing a sulfide-type electrolyte precursor, characterized by, The method comprises the following steps: putting raw materials in a stoichiometric ratio into a first tank under an inert atmosphere, performing a first mixing treatment through a tank mill to obtain a mixed material; transferring the mixed material into a second tank under an inert atmosphere, performing a second mixing treatment through a three-dimensional mixer to obtain the sulfide electrolyte precursor; wherein, during the second mixing treatment, sulfur is supplemented to the mixed material, and the addition amount of the sulfur source for the supplementation is 0.8wt%-5wt% of the mixed material.

2. The method for preparing a sulfide-type electrolyte precursor as described in claim 1, characterized in that, when the first mixing treatment is performed: The starting materials include Li2S, P2S5, and LiM, where M is selected from one or more of Cl - - - - and / or,​​​ the ball-to-material ratio in the first tank is (10-30):1; and / or, the roller shaft speed of the tank mill is 50-100 rpm, and the time for the first mixing treatment is 4-8 h; and / or, the particle size of the mixed material is not greater than 50 μm.

3. The method for preparing a sulfide-type electrolyte precursor as described in claim 1, characterized in that, when the second mixing treatment is performed: the spindle speed of the three-dimensional mixer is 2-13 rpm; and / or, before the supplementation of sulfur, the mixing time of the three-dimensional mixer is 2-6 h; and / or, after the supplementation of sulfur, the three-dimensional mixer is allowed to continue mixing for 2-6 h; and / or, the sulfur source comprises one or more of Li2S, S, and P2S5.

4. The method for preparing a sulfide-type electrolyte precursor as described in claim 3, characterized in that, the addition amount of the sulfur source is 3wt%-3.5wt% of the mixed material.

5. The method for preparing a sulfide-type electrolyte precursor as described in claim 4, characterized in that, the addition amount of the sulfur source is 3.15wt%-3.35wt% of the mixed material.

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