Electrode material additive and preparation method and application thereof

Abstract

The invention discloses an electrode material additive and a preparation method and application thereof. The preparation method comprises the following steps: dispersing a sulfide solid electrolyte in an ester solvent to form a first solution; taking raw materials LiA and MAn of halide electrolyte according to a stoichiometric ratio, and dispersing the raw materials in an alcohol solvent to form a second solution; wherein M is selected from In, Zr or Y, A is selected from Cl or F, and n is the valence state of M; and the first solution and the second solution are placed in a sanding device to be subjected to sanding, drying, sintering and dry ball milling depolymerization treatment, and the electrode material additive is prepared. When the electrode material additive is compounded with an electrode, direct contact between carbon and a sulfide solid electrolyte during charging and discharging is avoided, the structural stability of the sulfide solid electrolyte is ensured, and meanwhile, the nanoscale electrode material additive can effectively increase contact with an electrode material to form an effective ion transmission network.

Description

Technical Field

[0001] The present invention belongs to the technical field of sulfide solid-state batteries, and specifically relates to an electrode material additive and a preparation method and application thereof. Background Art

[0002] In sulfide all-solid-state batteries, a certain proportion of sulfide solid electrolyte is added to the electrode material. However, the sulfide solid electrolyte has a poor redox resistance and will decompose in the electrode. On the positive electrode side, the sulfide electrolyte undergoes oxidative decomposition to generate byproducts with low ionic conductivity, such as Li2S and P2S. x , elemental sulfur, etc. These decomposition products not only reduce the ionic conductivity of the electrolyte, but also form a high-resistance defect layer at the interface, hindering the transmission of lithium ions. In addition, these by-products may also undergo further chemical reactions with the positive electrode material to form reaction products such as sulfates and phosphates, further deteriorating the interface performance, and the carbon component in the electrode material will accelerate the decomposition of the sulfide solid electrolyte. On the negative electrode side, the sulfide solid electrolyte faces the same risks as the positive electrode side. This makes the adaptation of sulfide solid electrolytes to all-solid-state batteries have problems such as low reversible capacity and poor cycle performance.

[0003] Faced with the dilemma of sulfide solid electrolytes in the positive / negative electrode, most people choose to coat and modify the positive / negative electrode materials to enhance the interface stability of the sulfide solid electrolyte and the positive / negative electrode. For example, in the patent with publication number CN115395087A, halide solid electrolytes are used to coat the positive electrode material to stabilize the positive electrode interface in the sulfide solid-state battery. However, the halide has low electronic conductivity, which has a certain obstruction to the electron transport of the electrode material. In short, the various technologies for coating positive / negative electrode materials are essentially to maintain the interface problem between the positive electrode and the sulfide solid electrolyte, but ignore the decomposition of sulfide at high / low voltage, resulting in the deterioration of the ionic and electronic conductivity of the electrode material. In addition, there is also a technology that uses lithium salts to coat sulfide solid electrolytes (Surface Engineering Strategy Enables 4.5V Sulfide-Based All-Solid-State Batteries with High Cathode Loading and Long Cycle Life [J]. ACS Energy Letters, 2023, 8 (8): 3450-3459). This technology often uses ball milling for coating, which can lead to uneven coating and amorphization of the sulfide solid electrolyte, resulting in decreased ionic conductivity. Furthermore, this technology tends to address the interface between the cathode and the sulfide solid electrolyte. A more direct approach to ensuring the stability of the sulfide solid electrolyte in the electrode material is to dope the sulfide solid electrolyte to enhance its redox resistance (Park Y, Shim Y, Lee J, et al. Impacts of site-selective oxygen introduction on structural stabilization, moisture stability, and battery performance insulfide-based argyrodite [J]. Energy Storage Materials, 2025, 75. DOI: 10.1016 / j.ensm.2025.104078). However, this approach does not prevent the decomposition of the sulfide solid electrolyte. Overall, ensuring the stability of the sulfide solid electrolyte is crucial in composite electrode materials. However, these techniques do not address the issue of accelerated decomposition of the sulfide solid electrolyte due to direct contact with carbon. To address this problem, a core-shell structure of a halide solid electrolyte coated with a sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 and / or Li3PS4@Li 6-nMA6, protects the sulfide solid electrolyte in direct contact with carbon, and the particle size of this material is nanometer-scale, used as an electrode material additive. Summary of the Invention

[0004] The main purpose of the present invention is to provide an electrode material additive and a preparation method and application thereof, so as to overcome the deficiencies of the prior art.

[0005] To achieve the aforementioned object of the invention, the technical solutions adopted by the present invention include:

[0006] An embodiment of the present invention provides a method for preparing an electrode material additive, which comprises:

[0007] dispersing a sulfide solid electrolyte in an ester solvent to form a first solution;

[0008] Take the raw materials of halide electrolyte LiA and MA according to the stoichiometric ratio n dispersed in an alcohol solvent to form a second solution; wherein M is selected from In, Zr or Y, A is selected from Cl or F, and n is the valence state of M;

[0009] Furthermore, the first solution and the second solution are placed in a sand milling device for sand milling, drying, sintering, and dry ball milling depolymerization treatment to obtain an electrode material additive.

[0010] An embodiment of the present invention further provides an electrode material additive prepared by the aforementioned preparation method, wherein the electrode material additive comprises a sulfide solid electrolyte and a halide solid electrolyte coated on the surface of the sulfide solid electrolyte, and the electrode material additive has a core-shell structure.

[0011] The embodiments of the present invention also provide the use of the aforementioned electrode material additive in preparing sulfide all-solid-state battery electrodes.

[0012] An embodiment of the present invention further provides a positive electrode composite material, which includes a ternary positive electrode and the aforementioned electrode material additive.

[0013] An embodiment of the present invention further provides a negative electrode composite material, which includes a silicon-carbon negative electrode and the aforementioned electrode material additive.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) The halide solid electrolyte coated sulfide solid electrolyte in the present invention is used as an additive, and its particle size is nanometer-scale, which can effectively increase its contact area with the electrode material (ternary positive electrode / silicon carbon negative electrode) and form a stable ion and electron transmission network;

[0016] (2) The carbon component of the composite electrode material (including electrode material, carbon, and sulfide solid electrolyte) will accelerate the decomposition of the sulfide solid electrolyte. Due to the core-shell structure of the halide coating the sulfide, the outer halide protects the structural stability of the internal sulfide solid electrolyte, which can ensure the high ionic conductivity of the composite electrode material;

[0017] (3) The electrode material additives of the present invention have enhanced antioxidant and reduction capabilities, ensuring their structural stability under high / low voltages and enabling rapid ion transport;

[0018] (4) The fluorine ions and oxygen ions in the electrode material additives of the present invention form a stable interface layer with low interface impedance with the main electrode materials (ternary positive electrode, silicon-carbon negative electrode). BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 1-3 and 1-4 are ionic conductivity diagrams of Examples 1-3 of the present invention and Comparative Examples 1-4;

[0021] Figure 2a-2b is Li in Comparative Example 4 of the present invention 5.5 PS 4.5 Cl 1.5 , Li prepared in Example 1 5.5 PS 4.5 Cl 1.5 @2%Li3InCl 4.8 F 1.2 SEM images of

[0022] Figure 3a-3c is Li in Comparative Example 4 of the present invention 5.5 PS 4.5 Cl 1.5 , Comparative Example 1, Li prepared in Example 1 5.5 PS 4.5 Cl 1.5 @2%Li3InCl 4.8 F 1.2 Impedance diagrams of the solid-state battery at the first and 20th cycles. DETAILED DESCRIPTION

[0023] In view of the shortcomings of the prior art, the inventors of this case, after long-term research and extensive practice, have proposed the technical solution of the present invention. The technical solution of the present invention will be clearly and completely described below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making any creative effort shall fall within the scope of protection of the present invention.

[0024] Specifically, as one aspect of the technical solution of the present invention, a method for preparing an electrode material additive includes:

[0025] dispersing a sulfide solid electrolyte in an ester solvent to form a first solution;

[0026] Take the raw materials of halide electrolyte LiA and MA according to the stoichiometric ratio n dispersed in an alcohol solvent to form a second solution; wherein M is selected from In, Zr or Y, A is selected from Cl or F, and n is the valence state of M;

[0027] Furthermore, the first solution and the second solution are placed in a sand milling device for sand milling, drying, sintering, and dry ball milling depolymerization treatment to obtain an electrode material additive.

[0028] In some preferred embodiments, the particle size D50 of the sulfide solid electrolyte is ≥1 μm.

[0029] Furthermore, the particle size D50 of the sulfide solid electrolyte is 1-20 μm.

[0030] In some preferred embodiments, the ester solvent includes ethyl acetate and / or propylene carbonate, but is not limited thereto.

[0031] In some preferred embodiments, the sulfide solid electrolyte includes Li 5.5 PS 4.5 Cl 1.5 and / or Li3PS4, but not limited thereto.

[0032] In some preferred embodiments, the solid content of the first solution is 5-45 wt %.

[0033] Furthermore, the solid content of the first solution is 10-25 wt%, for example 25 wt%.

[0034] In some preferred embodiments, the preparation method specifically comprises: taking the raw materials LiA and MA of the halide electrolyte according to the stoichiometric ratio n The mixture is dispersed in an alcohol solvent and stirred at a rotation speed of 100-2000 rpm for 0.5-2 h to prepare a second solution.

[0035] Furthermore, the chemical formula of the halide electrolyte is Li 6-n MA6, wherein M is selected from In, Zr or Y, A is selected from Cl or F, and n is the valence state of M.

[0036] Furthermore, the alcohol solvent includes methanol and / or ethanol, but is not limited thereto.

[0037] Furthermore, the mass ratio of the raw material of the halide electrolyte to the alcohol solvent is 1:10-100.

[0038] In some preferred embodiments, the preparation method specifically comprises:

[0039] The first solution and the second solution are placed in a sand mill and sand milled at a rotation speed of 800-2000 rpm for 0.5-3 hours; wherein the diameter of the ball milling beads used is 0.1 mm-1 mm, and the particle size D50 of the sulfide solid electrolyte after sand milling is 300-800 nm;

[0040] Drying the solution obtained by sand milling at 80-400° C. for 6-48 hours to obtain a dry product;

[0041] Furthermore, the dried product is sintered at 150-500° C. for 0.5-10 hours, and then subjected to dry ball milling depolymerization treatment to obtain an electrode material additive of a halide solid electrolyte coated with a sulfide solid electrolyte.

[0042] Furthermore, the mass ratio of the raw material of the halide electrolyte to the sulfide solid electrolyte in the first solution is 0.5-5:100.

[0043] Furthermore, the sintering temperature is 150-300°C.

[0044] Furthermore, the dry ball milling deagglomeration treatment adopts a ball milling speed of 100-300 rpm, a ball milling bead diameter of 1 mm-15 mm, and a ball milling time of 0.1-1 h.

[0045] Furthermore, the particle size D50 of the electrode material additive is 650-850 nm.

[0046] In some more specific embodiments, the method for preparing the electrode material additive comprises the following steps:

[0047] (1) Weigh a sulfide solid electrolyte (Li 5.5 PS 4.5 Cl 1.5 ) is dispersed in ethyl acetate solution with a solid content of 10-45%, preferably a solid content of 25%.

[0048] (2) Halide electrolyte raw materials (LiA, MA n , M=In, Zr or Y, A=Cl or F, n is the valence of M) weigh the Li according to the stoichiometric ratio 6-n MA6 is dissolved in an alcohol solution. Alcohol solutions include methanol and ethanol. The total weight of the raw material to the weight of the ethanol is 1:10-100, preferably 1:30. The ethanol solution is then magnetically stirred at a speed of 100-2000 rpm, preferably 1500 rpm, for 0.5-2 hours, preferably 0.5 hours.

[0049] (3) The alcohol solution in (2) and the ethyl acetate solution in (1) are fed into a sand mill (model); the diameter of the ball milling beads is 0.1 mm to 1 mm, preferably 0.3 mm; the rotation speed is 800 to 2000 rpm, preferably 1500 rpm; the sand milling time is 0.5 to 3 h, preferably 1 h, wherein the target halide solid electrolyte Li in (2) 6-n MA6 is 0.5-5% of the mass of the sulfide solid electrolyte in (1), preferably 2%. The particle size of the sulfide solid electrolyte tested is D50 = 550 nm

[0050] (4) Collect the solution in (3) and transfer it to a vacuum oven for drying at a temperature of 80-400°C, preferably 80°C, and a drying time of 6-48 hours, preferably 12 hours.

[0051] (5) Sintering the dried product in (4) to obtain a halide solid electrolyte coated sulfide solid electrolyte (Li 5.5 PS 4.5 Cl 1.5 @Li 6-n MA6). The sintering temperature is 150-500°C, preferably 150°C, 200°C, or 300°C, and the drying time is 0.5-10 hours, preferably 1 hour.

[0052] (6) Due to the high sintering temperature, Li 5.5 PS 4.5 Cl 1.5 @Li 6-n The particle size of MA6 increases, and the material is subjected to dry ball milling deagglomeration. The ball mill speed is 100-300 rpm, preferably 120 rpm; the ball diameter is 1 mm-15 mm, preferably 8 mm; the ball milling time is 0-1 hour, preferably 0.25 hours. After deagglomeration, the particle size is measured, and the preferred particle size range is D50 = 650-850 nm.

[0053] Another aspect of an embodiment of the present invention further provides an electrode material additive prepared by the aforementioned preparation method, wherein the electrode material additive includes a sulfide solid electrolyte and a halide solid electrolyte coated on the surface of the sulfide solid electrolyte, and the electrode material additive has a core-shell structure.

[0054] The present invention uses a halide solid electrolyte with good stability with the positive electrode / negative electrode to coat the sulfide solid electrolyte, ensuring that the ionic conductivity of the composite electrolyte is high. At the same time, it avoids direct contact between carbon and the sulfide solid electrolyte during charging and discharging, ensuring the structural stability of the sulfide solid electrolyte. This composite solid electrolyte is reduced to nanometer size by sand milling, which can effectively increase the solid-solid contact between the positive electrode and the composite solid electrolyte, forming an effective ion transmission network. The halide selected is generally formulated as Li 6-n MA6, M=In, Zr or Y, A=Cl or F, n is the valence state of M. This type of halide solid electrolyte is coated on the surface of the sulfide solid electrolyte to form a core-shell structure.

[0055] The present invention selects halide solid electrolyte raw materials to be dissolved in methanol or ethanol, and sulfide solid electrolyte is dispersed in ethyl acetate. n ) are evenly coated in a sulfide solid electrolyte, and then sintered at low temperature to form a core-shell composite solid electrolyte material. This structure maintains the ionic conductivity of the electrolyte additive, improves the interfacial stability between the cathode material and the electrolyte, prevents the sulfide solid electrolyte from contacting carbon and enhances the sulfide solid electrolyte's redox resistance, thereby improving the battery's cycling stability.

[0056] The additive Li 5.5 PS 4.5 Cl 1.5 @Li 6-n MA6 mixed oxide cathode material is used in sulfide solid-state full battery: the additive Li 5.5 PS 4.5 Cl 1.5 @Li 6-n MA6 is mixed with conductive carbon, oxide positive electrode (such as NCM811, etc.) and silicon carbon negative electrode, and mixed with sulfide solid electrolyte (such as Li 5.5 PS 4.5 Cl 1.5 etc.), assembled into sulfide solid-state mold batteries.

[0057] Another aspect of the embodiments of the present invention further provides the use of the aforementioned electrode material additive in the preparation of sulfide all-solid-state battery electrodes.

[0058] Another aspect of the embodiments of the present invention further provides a positive electrode composite material, which includes a ternary positive electrode and the aforementioned electrode material additive.

[0059] Another aspect of an embodiment of the present invention further provides a negative electrode composite material, which includes a silicon-carbon negative electrode and the aforementioned electrode material additive.

[0060] The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments. This embodiment is implemented on the premise of the technical solution of the invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0061] Unless otherwise specified, the experimental materials used in the following examples can be purchased from conventional biochemical reagent companies.

[0062] All example steps were performed under an inert gas (argon or nitrogen) or vacuum environment.

[0063] Example 1

[0064] This example uses a liquid phase coating method to provide a halide solid electrolyte lithium indium chlorofluoride (Li3InCl 4.8 F 1.2 ) mass is sulfide solid electrolyte (Li 5.5 PS 4.5 Cl 1.5 ) mass of 2% coated sample (Li 5.5 PS 4.5 Cl 1.5 @2%Li3InCl 4.8 F 1.2 ).

[0065] The specific preparation process is as follows:

[0066] 1) Weigh 1 kg of sulfide solid electrolyte with a D50 of 20 μm and disperse it in 3 kg of ethyl acetate solution, and feed the mixture into a sand mill;

[0067] 2) Weigh 20 g of indium fluoride (4.183 g), indium chloride (8.0766 g), and lithium chloride (7.741 g) according to the stoichiometric ratio and dissolve them in 600 g of anhydrous ethanol. Magnetic stir the anhydrous ethanol solution at 1500 rpm for 0.5 h.

[0068] 3) feeding the ethanol solution into the sand mill prepared in step 1) and grinding the mixture for 1 h at a speed of 1500 rpm, using zirconia beads with a diameter of 0.3 mm;

[0069] 4) Testing the particle size of the sulfide solid electrolyte: Take the slurry in 3) and use a Malvern 3000 particle size analyzer to test the particle size; D50 = 532.9 nm;

[0070] 5) The slurry in 3) was dried at low temperature and dried in a vacuum oven at 80°C for 12 hours to obtain sulfide solid electrolyte and halide raw material powder: Li 5.5 PS 4.5 Cl 1.5 , LiCl, InCl3 and LiF.

[0071] 6) The powder in 5) is sintered at low temperature in a muffle furnace at 150 degrees Celsius for 1 hour to obtain a halide solid electrolyte coated sulfide solid electrolyte: Li 5.5 PS 4.5 Cl 1.5 @2%Li3InCl 4.8 F 1.2 ;

[0072] 7) Li 5.5 PS 4.5 Cl 1.5 @2%Li3InCl 4.8 F 1.2 Dry ball milling deagglomeration. The ball mill speed was 120 rpm; the ball diameter was 8 mm; the ball milling time was 0.15 h. After deagglomeration, the particle size was measured, and the particle size range was D50 = 582.3 nm.

[0073] 8) Test Li 5.5 PS 4.5 Cl 1.5 @2%Li3InCl 4.8 F 1.2 Ionic conductivity, test frequency is 10 -1 -10 6 Hz, the test results are as follows Figure 1 ; SEM pictures as Figure 2b shown.

[0074] 9) Li 5.5 PS 4.5 Cl 1.5 @2%Li3InCl 4.8 F 1.2 , conductive carbon black, and NCM811 positive electrode are mixed in the ratio of 2.5:0.5:7 as a composite positive electrode, and the electrolyte layer is Li 5.5 PS 4.5 Cl 1.5 , negative electrode side: SiC, Li 5.5 PS 4.5 Cl 1.5 @2%Li3InCl 4.8 F1.2 The first and 20th cycle impedance diagrams of solid-state batteries are shown in Figure 2. Figure 3c As shown in Table 1, the specific data of the impedance and capacity retention rate after the first effect and 20 cycles are shown.

[0075] Example 2

[0076] This example uses a liquid phase coating method to provide a halide solid electrolyte lithium yttrium chlorofluoride (Li3YCl 5.8 F 0.2 ) mass is sulfide solid electrolyte (Li 5.5 PS 4.5 Cl 1.5 ) mass of 1.5% coated sample (Li 5.5 PS 4.5 Cl 1.5 @1.5%Li3YCl 5.8 F 0.2 ).

[0077] The specific preparation process is as follows:

[0078] 1) Weigh 1 kg of sulfide solid electrolyte with a D50 of 20 μm and disperse it in 3 kg of ethyl acetate solution, and feed the mixture into a sand mill;

[0079] 2) Weigh 15 g of yttrium fluoride (0.4572 g), yttrium chloride (8.565 g), and lithium chloride (5.9773 g) in the stoichiometric ratio and dissolve in 600 g of anhydrous ethanol. Magnetic stir the anhydrous ethanol solution at 1500 rpm for 1 hour.

[0080] 3) feeding the ethanol solution into the sand mill prepared in step 1) and grinding the mixture for 1 h at a speed of 1500 rpm, using zirconia beads with a diameter of 0.3 mm;

[0081] 4) Testing the particle size of the sulfide solid electrolyte: Take the slurry in 3) and use a Malvern 3000 particle size analyzer to test the particle size; D50 = 532.9 nm;

[0082] 5) The slurry in 3) was dried at low temperature and dried in a vacuum oven at 80°C for 12 hours to obtain sulfide solid electrolyte and halide raw material powder: Li 5.5 PS 4.5 Cl 1.5 , LiCl and YCl3;

[0083] 6) Sinter the powder in 5) in a muffle furnace at 300 degrees Celsius for 1 hour to obtain a halide solid electrolyte coated sulfide solid electrolyte: Li 5.5 PS 4.5 Cl1.5 @2%Li3YCl 5.8 F 0.2 ;

[0084] 7) Li 5.5 PS 4.5 Cl 1.5 @1.5%Li3YCl 5.8 F 0.2 Dry ball milling deagglomeration. The ball mill speed was 120 rpm; the ball diameter was 8 mm; the ball milling time was 0.25 h. After deagglomeration, the particle size was measured, and the particle size range was D50 = 608.5 nm.

[0085] 8) Test Li 5.5 PS 4.5 Cl 1.5 @1.5%Li3YCl 5.8 F 0.2 Ionic conductivity, test frequency is 10 -1 -10 6 Hz, the test results are as follows Figure 1 ;

[0086] 9) Li 5.5 PS 4.5 Cl 1.5 @1.5%Li3YCl 5.8 F 0.2 , conductive carbon black, and NCM811 positive electrode are mixed in the ratio of 2.5:0.5:7 as a composite positive electrode, and the electrolyte layer is Li 5.5 PS 4.5 Cl 1.5 , negative electrode side: SiC, Li 5.5 PS 4.5 Cl 1.5 @1.5%Li3YCl 5.8 F 0.2 The composite negative electrode was prepared by mixing carbon nanotubes with a ratio of 7:2.5:0.5. The impedance and capacity retention after the first cycle and 20 cycles were tested. The specific data are shown in Table 1.

[0087] Example 3

[0088] This example adopts liquid phase coating method to provide a halide solid electrolyte lithium zirconium chloride (Li2ZrCl6) with a mass of sulfide solid electrolyte (Li 5.5 PS 4.5 Cl 1.5 ) mass of 2% coated sample (Li 5.5 PS 4.5 Cl 1.5 @2% Li2ZrCl6).

[0089] The specific preparation process is as follows:

[0090] 1) Weigh 1 kg of sulfide solid electrolyte with a D50 of 20 μm and disperse it in 3 kg of ethyl acetate solution, and feed the mixture into a sand mill;

[0091] 2) Weigh 20 g of zirconium chloride (14.664 g) and lithium chloride (5.336 g) according to the stoichiometric ratio and dissolve them in 600 g of anhydrous ethanol. Magnetic stir the anhydrous ethanol solution at 1500 rpm for 1 hour.

[0092] 3) feeding the ethanol solution into the sand mill prepared in step 1) and grinding the mixture for 1 h at a speed of 1500 rpm, using zirconia beads with a diameter of 0.3 mm;

[0093] 4) Testing the particle size of the sulfide solid electrolyte: Take the slurry in 3) and use a Malvern 3000 particle size analyzer to test the particle size; D50 = 532.9 nm;

[0094] 5) The slurry in 3) was dried at low temperature and dried in a vacuum oven at 80°C for 12 hours to obtain sulfide solid electrolyte and halide raw material powder: Li 5.5 PS 4.5 Cl 1.5 , LiCl and ZrCl4

[0095] 6) Sinter the powder in 5) in a muffle furnace at 200 degrees Celsius for 0.5 hours to obtain a halide solid electrolyte coated sulfide solid electrolyte: Li 5.5 PS 4.5 Cl 1.5 @2%Li2ZrCl6;

[0096] 7) Li 5.5 PS 4.5 Cl 1.5 2% Li₂ZrCl₂ was deagglomerated by dry ball milling. The ball mill speed was 120 rpm, the ball diameter was 8 mm, and the ball milling time was 0.25 h. After deagglomeration, the particle size was measured, and the particle size range was D50 = 590.2 nm.

[0097] 8) Test Li 5.5 PS 4.5 Cl 1.5 @2% Li2ZrCl6 ion conductivity, test frequency is 10 -1 -10 6 Hz, the test results are as follows Figure 1 ;

[0098] 9) Li 5.5 PS 4.5 Cl 1.5@2% Li2ZrCl6, conductive carbon black and NCM811 positive electrode are mixed in the ratio of 2.5:0.5:7 as a composite positive electrode, and the electrolyte layer is Li 5.5 PS 4.5 Cl 1.5 , negative electrode side: SiC, Li 5.5 PS 4.5 Cl 1.5 A composite negative electrode was prepared using a 7:2.5:0.5 ratio of 2% Li₂ZrCl₂ and carbon nanotubes. The impedance and capacity retention after initial efficiency and 20 cycles were tested. Specific data are shown in Table 1.

[0099] Comparative Example 1

[0100] This comparative example adopts dry ball milling coating method to provide halide solid electrolyte lithium indium chlorofluoride (Li3InCl 4.8 F 1.2 ) mass is sulfide solid electrolyte (Li 5.5 PS 4.5 Cl 1.5 ) mass of 2% coated sample (Li 5.5 PS 4.5 Cl 1.5 @2%Li3InCl 4.8 F 1.2 ).

[0101] 1) Weigh 1 kg of a sulfide solid electrolyte with a D50 of 532.9 nm;

[0102] 2) Weigh 20 g of the halide raw materials: indium fluoride (4.183 g), indium chloride (8.0766 g), and lithium chloride (7.741 g);

[0103] 3) 1) and 2) were added into a ball mill for ball milling at a speed of 300 rpm, a ball diameter of 8 mm, and an effective ball milling time of 1 h.

[0104] 4) The powder in 3) is sintered at low temperature in a muffle furnace at 150 degrees Celsius for 1 hour to obtain a halide solid electrolyte coated sulfide solid electrolyte - Li 5.5 PS 4.5 Cl 1.5 @2%Li3InCl 4.8 F 1.2 ;

[0105] 5) Li 5.5 PS 4.5 Cl 1.5 @2%Li3InCl 4.8 F 1.2Dry ball milling deagglomeration. The ball mill speed was 120 rpm; the ball diameter was 8 mm; the ball milling time was 0.25 h. After deagglomeration, the particle size was measured, and the particle size range was D50 = 1.07 μm.

[0106] 6) Test Li 5.5 PS 4.5 Cl 1.5 @2%Li3InCl 4.8 F 1.2 Ionic conductivity, test frequency is 10 -1 -10 6 Hz, the test results are as follows Figure 1 ;

[0107] 7) Li 5.5 PS 4.5 Cl 1.5 @2%Li3InCl 4.8 F 1.2 , conductive carbon black, NCM811 positive electrode are mixed in accordance with 2:0.5:7.5 to assemble the mold battery, the electrolyte layer is Li 5.5 PS 4.5 Cl 1.5 , the negative electrode layer is the negative electrode side: SiC, Li 5.5 PS 4.5 Cl 1.5 @2% Li2ZrCl6 and carbon nanotubes were mixed in a ratio of 7:2.5:0.5 as a composite negative electrode. The impedance and capacity retention rate of the first cycle and 20 cycles were tested. The impedance graphs of the solid-state battery at the first cycle and the 20th cycle are shown in the figure below. Figure 3b The specific data are shown in Table 1.

[0108] Comparative Example 2

[0109] This comparative example adopts dry ball milling coating method to provide halide solid electrolyte lithium yttrium chloride (Li3YCl 5.8 F 0.2 ) mass is sulfide solid electrolyte (Li 5.5 PS 4.5 Cl 1.5 ) mass of 1.5% coated sample (Li 5.5 PS 4.5 Cl 1.5 @Li3YCl 5.8 F 0.2 ).

[0110] 1) Weigh 1 kg of a sulfide solid electrolyte with a D50 of 532.9 nm;

[0111] 2) Weigh 15 g of the halide raw materials: yttrium fluoride (0.4572 g), yttrium chloride (8.565 g), and lithium chloride (5.9773 g);

[0112] 3) adding 1) and 2) into a ball mill and milling them at a speed of 300 rpm, a ball milling bead diameter of 8 mm, and an effective milling time of 1 h;

[0113] 4) Sinter the powder in 3) in a muffle furnace at 300 degrees Celsius for 1 hour to obtain a halide solid electrolyte coated sulfide solid electrolyte - Li 5.5 PS 4.5 Cl 1.5 @1.5%Li3YCl 5.8 F 0.2 ;

[0114] 5) Li 5.5 PS 4.5 Cl 1.5 @1.5%Li3YCl 5.8 F 0.2 Dry ball milling deagglomeration. The ball mill speed was 120 rpm; the ball diameter was 8 mm; the ball milling time was 0.25 h. After deagglomeration, the particle size was measured, and the particle size range was D50 = 1.37 μm.

[0115] 6) Test Li 5.5 PS 4.5 Cl 1.5 @1.5%Li3YCl 5.8 F 0.2 Ionic conductivity, the test frequency is 10-1-106Hz, the test results are as follows Figure 1 ;

[0116] 7) Li 5.5 PS 4.5 Cl 1.5 @1.5%Li3YCl 5.8 F 0.2 , conductive carbon black, NCM811 positive electrode are mixed in accordance with 2:0.5:7.5 to assemble the mold battery, the electrolyte layer is Li 5.5 PS 4.5 Cl 1.5 , negative electrode side: SiC, Li 5.5 PS 4.5 Cl 1.5 A composite negative electrode was prepared using a 7:2.5:0.5 ratio of 2% Li₂ZrCl₂ and carbon nanotubes. The impedance and capacity retention after initial efficiency and 20 cycles were tested. Specific data are shown in Table 1.

[0117] Comparative Example 3

[0118] This comparative example adopts dry ball milling coating method to provide a halide solid electrolyte lithium yttrium chloride (Li2ZrCl6) with a mass of sulfide solid electrolyte (Li 5.5PS 4.5 Cl 1.5 2% by mass of the coated sample (Li 5.5 PS 4.5 Cl 1.5 @2% Li2ZrCl6).

[0119] 1) Weigh 1 kg of a sulfide solid electrolyte with a D50 of 5392.9 nm;

[0120] 2) Weigh 20 g of the halide raw materials zirconium chloride (14.664 g) and lithium chloride (5.336 g);

[0121] 3) adding 1) and 2) into a ball mill and milling them at a speed of 300 rpm, a ball milling bead diameter of 8 mm, and an effective milling time of 1 h;

[0122] 4) Sinter the powder in 3) in a muffle furnace at 200 degrees Celsius for 0.5 hours to obtain a halide solid electrolyte coated sulfide solid electrolyte - Li 5.5 PS 4.5 Cl 1.5 @2%Li2ZrCl6;

[0123] 5) Li 5.5 PS 4.5 Cl 1.5 @1.5%Li3YCl 5.8 F 0.2 Dry ball milling deagglomeration. The ball mill speed was 120 rpm; the ball diameter was 8 mm; the ball milling time was 0.25 h. After deagglomeration, the particle size was measured, and the particle size range was D50 = 1.15 μm.

[0124] 6) Test Li 5.5 PS 4.5 Cl 1.5 @2% Li2ZrCl6 ion conductivity, test frequency is 10 -1 -10 6 Hz, the test results are as follows Figure 1 ;

[0125] 7) Li 5.5 PS 4.5 Cl 1.5 @2% Li2ZrCl6, conductive carbon black, NCM811 positive electrode are mixed in accordance with 2:0.5:7.5 to assemble the mold battery, the electrolyte layer is Li 5.5 PS 4.5 Cl 1.5 , negative electrode side: SiC, Li 5.5 PS 4.5 Cl 1.5A composite negative electrode was prepared using a 7:2.5:0.5 ratio of 2% Li₂ZrCl₂ and carbon nanotubes. The impedance and capacity retention after initial efficiency and 20 cycles were tested. Specific data are shown in Table 1.

[0126] Comparative Example 4

[0127] In this example, a sulfide solid electrolyte with a D50 of 532.9 nm was obtained by liquid phase sand milling.

[0128] The specific preparation process is as follows:

[0129] 1) Weigh 1 kg of sulfide solid electrolyte with a D50 of 20 μm and disperse it in 3 kg of ethyl acetate solution. Add the mixture into a sand mill and grind at a speed of 1500 rpm, using zirconia balls with a diameter of 0.3 mm, for 1 hour.

[0130] 2) Testing the particle size of the sulfide solid electrolyte: taking the slurry in 1), the particle size was measured using a Malvern 3000 particle size analyzer; the measured D50 was 532.9 nm;

[0131] 3) The slurry in 2) was dried at low temperature and dried in a vacuum oven at 80°C for 12 hours to obtain sulfide solid electrolyte and halide raw material powder: Li 5.5 PS 4.5 Cl 1.5 ;

[0132] 4) The powder in 3) is sintered at low temperature in a muffle furnace at 150 degrees Celsius for 1 hour to obtain a halide solid electrolyte coated sulfide solid electrolyte: Li 5.5 PS 4.5 Cl 1.5 ;

[0133] 5) Li 5.5 PS 4.5 Cl 1.5 Dry ball milling deagglomeration. The ball mill speed was 120 rpm; the ball diameter was 8 mm; the ball milling time was 0.25 h. After deagglomeration, the particle size was measured, and the particle size range was D50 = 568.2 nm.

[0134] 6) Test Li 5.5 PS 4.5 Cl 1.5 Ionic conductivity, test frequency is 10 -1 -10 6 Hz, the test results are as follows Figure 1 ; SEM pictures as Figure 2a shown.

[0135] Li with D50 = 568.2 nm 5.5 PS 4.5 Cl1.5 , conductive carbon black, NCM811 positive electrode are mixed in accordance with 2:0.5:7.5 to assemble the mold battery, the electrolyte layer is Li 5.5 PS 4.5 Cl 1.5 , negative electrode side: SiC, Li 5.5 PS 4.5 Cl 1.5 @2% Li2ZrCl6 and carbon nanotubes were mixed in a ratio of 7:2.5:0.5 as a composite negative electrode. The impedance and capacity retention rate of the first cycle and 20 cycles were tested. The impedance graphs of the solid-state battery at the first cycle and the 20th cycle are shown in the figure below. Figure 3a The specific data are shown in Table 1.

[0136] Comparative Example 5

[0137] The method was the same as in Example 1, except that the composite electrode material lacked a halide solid electrolyte. The impedance and capacity retention of the composite electrode were tested after the first cycle and 20 cycles. The specific data are shown in Table 1.

[0138] Comparative Example 6

[0139] The method was the same as in Example 1, except that the composite electrode material was mixed with a sulfide-free solid electrolyte. The impedance and capacity retention of the composite electrode were tested after the first cycle and 20 cycles. The specific data are shown in Table 1.

[0140] Comparative Example 7

[0141] A halide solid electrolyte and a sulfide solid electrolyte were directly mixed as additives. The capacity retention data after the first cycle and 20 cycles were tested and shown in Table 1.

[0142] Comparative Example 8

[0143] Li with D50 = 20 μm 5.5 PS 4.5 Cl 1.5 , conductive carbon black, NCM811 positive electrode are mixed in accordance with 2:0.5:7.5 to assemble the mold battery, the electrolyte layer is Li 5.5 PS 4.5 Cl 1.5 , negative electrode side: SiC, Li 5.5 PS 4.5 Cl 1.5 A composite negative electrode was prepared using a 7:2.5:0.5 ratio of 2% Li₂ZrCl₂ and carbon nanotubes. The impedance and capacity retention data for the initial cycle, 20 cycles, and 20 cycles are shown in Table 1.

[0144] Table 1 Characterization data of Examples 1-3 and Comparative Examples 1-7

[0145]

[0146] The examples all showed higher first-effect and first-cycle discharge specific capacities, indicating that the sulfide decomposed less in the electrode, maintaining the stability of the ion / electron transport network. The first effect of the comparative example was lower, indicating that the sulfide decomposed in contact with the positive electrode / carbon, hindering the migration of lithium ions and affecting its first effect and first-cycle discharge specific capacity. At the same time, the large-particle-sized sulfide solid electrolyte in comparative example 8 was used as a positive electrode additive, and the first-effect and first-cycle discharge specific capacities were poor, and the capacity retention rate was extremely low. This shows that large particle size cannot be used as an additive and affects solid-solid contact.

[0147] After 20 cycles, the capacity retention rates of the embodiments are all above 96%, while the capacity retention rate of the comparative examples decays by more than 15%. In comparative example 1, the ball-milled lithium salt-coated sulfide solid electrolyte has certain defects, and the interface impedance increases by 63Ω. In comparative example 4, the interface impedance value of the solid-state battery of the sulfide solid electrolyte without any coating increased by 90Ω. In Example 1, the sand milling method is used, and the sulfide solid electrolyte coated with the halide solid electrolyte decomposes less in the electrode, and its interface impedance value only increases by 15Ω, ensuring ion transmission.

[0148] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments using other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0149] It should be understood that the technical solution of the present invention is not limited to the above-mentioned specific implementation cases. Any technical variations made according to the technical solution of the present invention without departing from the scope of protection of the purpose of the present invention and the claims shall fall within the scope of protection of the present invention.

Claims

1. A method for preparing an electrode material additive, characterized in that: include: dispersing a sulfide solid electrolyte in an ester solvent to form a first solution; The raw materials of the halide electrolyte, LiA and MAn, are dispersed in an alcohol solvent according to a stoichiometric ratio to form a second solution; wherein M is selected from In, Zr or Y, A is selected from Cl or F, and n is the valence state of M; Furthermore, the first solution and the second solution are placed in a sand milling device for sand milling, drying, sintering, and dry ball milling depolymerization treatment to obtain an electrode material additive.

2. The preparation method according to claim 1, wherein: The particle size D50 of the sulfide solid electrolyte is ≥1 μm; and / or, the ester solvent includes ethyl acetate and / or propylene carbonate; And / or, the sulfide solid electrolyte includes Li 5.5 PS 4.5 Cl 1.5 and / or Li3PS4; And / or, the solid content of the first solution is 5-45 wt%.

3. The preparation method according to claim 1, characterized in that Specifically include: Take the raw materials of halide electrolyte LiA and MA according to the stoichiometric ratio n The mixture is dispersed in an alcohol solvent and stirred at a rotation speed of 100-2000 rpm for 0.5-2 h to prepare a second solution.

4. The preparation method according to claim 3, wherein: The general chemical formula of the halide electrolyte is Li 6- n MA6, wherein M is selected from In, Zr or Y, A is selected from Cl or F, and n is the valence state of M; and / or, the alcohol solvent includes methanol and / or ethanol; And / or, the mass ratio of the raw material of the halide electrolyte to the alcohol solvent is 1:10-100.

5. The preparation method according to claim 1, characterized in that Specifically include: The first solution and the second solution are placed in a sand mill and sand milled at a rotation speed of 800-2000 rpm for 0.5-3 hours; wherein the diameter of the ball milling beads used is 0.1 mm-1 mm, and the particle size D50 of the sulfide solid electrolyte after sand milling is 300-800 nm; Drying the solution obtained by sand milling at 80-400° C. for 6-48 hours to obtain a dry product; Furthermore, the dried product is sintered at 150-500° C. for 0.5-10 hours, and then subjected to dry ball milling depolymerization treatment to obtain an electrode material additive of a halide solid electrolyte coated with a sulfide solid electrolyte.

6. The preparation method according to claim 5, characterized in that: The mass ratio of the raw material of the halide electrolyte to the sulfide solid electrolyte in the first solution is 0.5-5:100; And / or, the sintering temperature is 150-300°C; And / or, the dry ball milling deagglomeration treatment adopts a ball milling speed of 100-300 rpm, a ball milling bead diameter of 1 mm-15 mm, and a ball milling time of 0.1-1 h; And / or, the particle size D50 of the electrode material additive is 500-850 nm.

7. The electrode material additive prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The electrode material additive includes a sulfide solid electrolyte and a halide solid electrolyte coated on the surface of the sulfide solid electrolyte, and the electrode material additive has a core-shell structure.

8. Use of the electrode material additive according to claim 7 in the preparation of sulfide all-solid-state battery electrodes.

9. A positive electrode composite material, characterized in that: It comprises a ternary positive electrode and the electrode material additive according to claim 7.

10. A negative electrode composite material, characterized in that: It comprises a silicon-carbon negative electrode and the electrode material additive according to claim 7.

Images