A halide solid-state electrolyte, a preparation method thereof, and a preparation method of a full solid-state battery

Abstract

The present application provides a kind of halide solid electrolyte and preparation method and preparation method of full solid battery thereof.The solid electrolyte includes Li 2+a M 1‑a N a F b Cl 6‑b Wherein, M includes any one of Zr, Y, In, Sc, Er or Ga, N includes any one of Fe, Al, Ti, Mn or Zn, 0

Description

Technical Field

[0001] This invention relates to the field of lithium-ion batteries, and more particularly to a halide solid electrolyte, a halide solid electrolyte and its preparation method, and a method for preparing an all-solid-state battery. Background Technology

[0002] Solid-state lithium-ion batteries offer enhanced safety and a wider operating temperature range due to the use of solid electrolytes instead of traditional separators and electrolytes. Furthermore, the electrolyte does not dry out during long-term cycling, resulting in longer cycle life and overall battery life. The key to the development and application of solid-state lithium-ion batteries lies in constructing a high-performance solid electrolyte.

[0003] CN114400368A discloses a sulfide solid electrolyte layer, its preparation method, and a lithium-ion battery. An electrode is provided, on which a sulfide solid electrolyte coating is formed on a portion of the electrode surface. The mixed powder includes sulfide solid electrolyte powder, lithium salt powder, and thermosensitive polymer powder. However, sulfide electrolytes have high synthesis costs, and the limited yield and high price of the raw material Li2S restrict its large-scale production. Furthermore, the reaction products include H2S, posing challenges to the environment and health.

[0004] CN113363567A discloses a halide solid electrolyte, its preparation method, and its application. Its chemical formula is Li3MX6, where M is at least one rare earth element and X is at least one of F, Cl, Br, and I; the structural micro-stress of the halide solid electrolyte is 0.001–0.01. However, halide solid electrolytes often suffer from drawbacks such as a low electrochemical stability window, oxidation by the positive electrode material under high voltage, low ionic conductivity, and instability with lithium metal anodes. Furthermore, common halide solid electrolytes include Li3InCl6, Li3ScCl6, and Li3YCl. 6、 Li2ZrCl6 and similar materials use a large amount of rare earth elements, resulting in high synthesis costs and limiting their application in all-solid-state batteries and composite cathodes.

[0005] Common methods to improve the above problems mainly involve modifying the electrode interface, using artificial coatings or SEI to enhance its high-voltage stability and stability to the lithium metal anode. However, these methods are often complex to operate and difficult to apply in engineering. Therefore, how to prepare a high-performance lithium-ion battery is an important research direction in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a halide solid electrolyte and its preparation method, as well as a method for preparing an all-solid-state battery, and to develop a halide solid electrolyte and its synthesis method that have both high ionic conductivity and a wide electrochemical stability window, as well as excellent cost advantages.

[0007] To achieve the object of the present invention, the present invention adopts the following technical solution:

[0008] One of the objects of the present invention is to provide a halide solid electrolyte, wherein the halide solid electrolyte comprises Li 2+a M 1-a N a F b Cl 6-b , wherein M comprises any one of Zr, Y, In, Sc, Er or Ga, N comprises any one of Fe, Al, Ti, Mn or Zn, 0<a≤0.5, 0<b≤2, the value of a can be 0.1, 0.2, 0.3, 0.4 or 0.5, etc., the value of b can be 0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 1.9 or 2, etc., but is not limited to the listed values, other unlisted values within the above numerical ranges are also applicable.

[0009] In the metal element and halogen element doped solid electrolyte provided by the present invention, through structural design of the halide solid electrolyte, doping metal elements such as Fe into the halide solid electrolyte can significantly reduce production costs while improving the ionic conductivity of the halide solid electrolyte. Meanwhile, doping part of F element can increase the electrochemical stability window to above 6V, and can in-situ generate a fluoride-rich interface layer on the electrode surface during cycling, thereby realizing inhibition of reduction and improving the stability to lithium negative electrodes.

[0010] The second object of the present invention is to provide a preparation method of the halide solid electrolyte described in the first object, wherein the preparation method comprises:

[0011] After drying LiCl, LiF, MCl x and NCl y are sequentially subjected to first ball milling and calcination treatment to obtain the halide solid electrolyte, wherein x is 3 or 4, 2≤y≤4, and the value of y can be 2, 3 or 4, etc.

[0012] The method for preparing the halide solid electrolyte of the present invention is simple and efficient, facilitates continuous large-scale production and industrialization, is applicable to a variety of different halide solid electrolytes, and has good versatility.

[0013] As a preferred technical solution of the present invention, the LiCl, LiF, MCl x and NCl yThe molar ratio is (0.5~3):(0.1~2):(0.1~1):(0.1~1), wherein the molar ratio can be 0.5:0.1:0.1:0.1, 1:0.5:0.5:0.5, 1.5:1:1:1, 2:2:1:1, 2.5:0.1:0.1:1 or 3:1:1:1, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0014] As a preferred technical solution of the present invention, the drying temperature is 120-180℃, wherein the temperature can be 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃ or 180℃, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0015] Preferably, the drying time is 6 to 10 hours, wherein the time can be 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0016] Preferably, the first grinding is performed before the first ball milling.

[0017] As a preferred technical solution of the present invention, the atmosphere of the first ball mill includes an argon atmosphere.

[0018] Preferably, the ball-to-material ratio of the first ball mill is (5-40):1, wherein the ball-to-material ratio can be 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1 or 40:1, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0019] Preferably, the first ball mill includes low-speed ball milling and high-speed ball milling.

[0020] Preferably, the low-speed ball milling speed is 200-400 rpm, wherein the speed can be 200 rpm, 220 rpm, 240 rpm, 260 rpm, 280 rpm, 300 rpm, 320 rpm, 340 rpm, 360 rpm, 380 rpm or 400 rpm, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0021] Preferably, the low-speed ball milling time is 1.5 to 2.5 hours, wherein the time can be 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, or 2.5 hours, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] Preferably, the speed of the high-speed ball mill is 400 to 800 rpm, wherein the speed can be 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm or 800 rpm, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0023] Preferably, the high-speed ball milling time is 24 to 40 hours, wherein the time can be 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, 36 hours, 38 hours or 40 hours, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] Preferably, the calcination temperature is 250–400°C, wherein the temperature can be 250°C, 280°C, 300°C, 320°C, 340°C, 360°C, 380°C, or 400°C, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0025] Preferably, the atmosphere for the calcination treatment includes an argon atmosphere.

[0026] Preferably, the calcination treatment time is 3 to 10 hours, wherein the time can be 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] A third objective of this invention is to provide a method for preparing an all-solid-state battery, the all-solid-state battery comprising the halide solid electrolyte as described in one objective, the preparation method comprising:

[0028] (1) The first halide solid electrolyte, the positive electrode material and the conductive agent are sequentially subjected to a second grinding and a second ball milling to obtain composite positive electrode powder;

[0029] (2) Add the second halide solid electrolyte to the model battery, perform the first cold pressing treatment, add the composite positive electrode powder described in step (1) to one side of the model battery, perform the second cold pressing treatment, attach the negative electrode metal sheet to the other side of the model battery, and perform the third cold pressing treatment to obtain an all-solid-state battery.

[0030] As a preferred technical solution of the present invention, the positive electrode material in step (1) includes any one or a combination of at least two of NCM622, NCN712, NCM811, N90, lithium iron phosphate, lithium manganese oxide, or lithium cobalt oxide. Typical but non-limiting examples of the combination include: the combination of NCM622 and NCN712, the combination of NCN712 and NCM811, the combination of NCM811 and N90, the combination of N90 and lithium iron phosphate, the combination of lithium iron phosphate and lithium manganese oxide, or the combination of lithium manganese oxide and lithium cobalt oxide, etc.

[0031] Preferably, the conductive agent in step (1) includes any one or a combination of at least two of conductive carbon black, graphene, carbon nanotubes, carbon nanofibers or Ketjen black, wherein typical but non-limiting examples of the combination are: a combination of conductive carbon black and graphene, a combination of graphene and carbon nanotubes, a combination of carbon nanotubes and carbon nanofibers or a combination of carbon nanofibers and Ketjen black.

[0032] Preferably, based on the mass of the composite positive electrode powder as 100%, the first halide solid electrolyte in step (1) accounts for 15 to 40 wt% of the composite positive electrode powder. The mass fraction can be 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] Preferably, based on the mass of the composite positive electrode powder as 100%, the positive electrode main material in step (1) accounts for 55 to 80 wt% of the mass of the composite positive electrode powder. The mass fraction can be 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, or 80 wt%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] Preferably, based on the mass of the composite positive electrode powder as 100%, the conductive agent in step (1) accounts for 2 to 10 wt% of the composite positive electrode powder. The mass fraction can be 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] As a preferred technical solution of the present invention, the second ball milling time in step (1) is 4 to 8 hours, wherein the time can be 4 hours, 5 hours, 6 hours, 7 hours or 8 hours, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] Preferably, the speed of the second ball mill in step (1) is 200 to 400 rpm, wherein the speed can be 200 rpm, 220 rpm, 240 rpm, 260 rpm, 280 rpm, 300 rpm, 320 rpm, 340 rpm, 360 rpm, 380 rpm or 400 rpm, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] As a preferred technical solution of the present invention, the mass of the second halide solid electrolyte in step (2) is 80 to 120 mg, wherein the mass can be 80 mg, 85 mg, 90 mg, 95 mg, 100 mg, 105 mg, 110 mg, 115 mg or 120 mg, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] Preferably, the mass of the composite positive electrode powder in step (2) is 10 to 30 mg, wherein the mass can be 10 mg, 14 mg, 18 mg, 22 mg, 26 mg or 30 mg, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0039] Preferably, the negative electrode metal sheet in step (2) includes any one of Li-Fe alloy, Li-In alloy, Li-Mg alloy, Li-Zn alloy, Li-Al alloy, indium sheet or lithium sheet.

[0040] Preferably, the thickness of the negative electrode metal sheet in step (2) is 0.1 to 0.2 mm, wherein the thickness can be 0.1 mm, 0.12 mm, 0.14 mm, 0.16 mm, 0.18 mm or 0.2 mm, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0041] As a preferred technical solution of the present invention, the pressure of the first cold pressing process in step (2) is 300-500 MPa, wherein the pressure can be 300 MPa, 320 MPa, 340 MPa, 360 MPa, 380 MPa, 400 MPa, 420 MPa, 460 MPa, 480 MPa or 500 MPa, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] Preferably, the time for the first cold pressing process in step (2) is ≥5 min, wherein the time can be 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] Preferably, the pressure of the second cold pressing process in step (2) is 300-400 MPa, wherein the pressure can be 300 MPa, 310 MPa, 320 MPa, 330 MPa, 340 MPa, 350 MPa, 360 MPa, 370 MPa, 380 MPa, 390 MPa or 400 MPa, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Preferably, the time for the second cold pressing process in step (2) is ≥5 min, wherein the time can be 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] Preferably, the pressure of the third cold pressing process in step (2) is 50 to 150 MPa, wherein the pressure can be 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, 110 MPa, 120 MPa, 130 MPa, 140 MPa or 150 MPa, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0046] Preferably, the time for the third cold pressing process in step (2) is ≥5 min, wherein the time can be 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The halide solid electrolyte prepared by this invention possesses both high ionic conductivity and a wide electrochemical stability window, exhibiting excellent cycle stability in all-solid-state batteries and demonstrating great application potential. The ionic conductivity is significantly improved, reaching a maximum of 8.4 x 10⁻⁶. -4 With an S / cm above, the electrochemical window is stable above 5V, significantly improving cycle stability, and the capacity retention rate increases by more than 15.18% after 100 cycles. Attached Figure Description

[0049] Figure 1 These are charge-discharge curves of all-solid-state batteries in Embodiment 1, Comparative Example 3, and Comparative Example 4 of the present invention.

[0050] Figure 2 These are cycle test diagrams of all-solid-state batteries in Embodiment 1, Comparative Example 3, and Comparative Example 4 of the present invention. Detailed Implementation

[0051] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0052] Example 1

[0053] This embodiment provides a method for preparing an all-solid-state battery:

[0054] Preparation method of solid electrolyte (Li 2.15 Zr 0.85 Fe 0.15 F 0.5 Cl 5.5 The raw materials LiCl (>99%), ZrCl4 (>99%), LiF (>99%), and FeCl3 (>99%) were vacuum dried in an oven at 150℃ for 8 hours to remove moisture. LiCl, LiF, ZrCl4, and FeCl3 were weighed according to stoichiometric ratio (molar ratio of LiCl, LiF, ZrCl4, and FeCl3 was 1.65:0.5:0.85:0.15), ground and premixed, and then added to a ball mill jar. Zirconia grinding beads (ball-to-material ratio 20:1) were added, argon gas was introduced, and the jar was sealed. The mixture was then ball-milled at 300 rpm for 2 hours, followed by high-speed ball milling at 500 rpm for 36 hours. After ball milling, the LiCl4, ZrCl4, and FeCl3 were removed. 2.15 Zr 0.85 Fe 0.15 F 0.5 Cl 5.5 The electrolyte was ground uniformly and placed in a tube furnace for calcination at 400℃ under argon gas for 10 hours to obtain Li. 2.15 Zr 0.85 Fe 0.15 F 0.5 Cl 5.5 Solid electrolyte.

[0055] Preparation method of all-solid-state battery: NCM811 cathode material and Super-P, Li 2.15 Zr 0.85 Fe 0.15 F 0.5 Cl 5.5 The electrolytes were ground uniformly in a 6:1:3 ratio and then ball-milled at 300 rpm for 6 hours in a zirconium oxide ball mill jar to prepare composite cathode powder; 100 mg of Li was taken 2.15 Zr 0.85 Fe 0.15 F 0.5 Cl 5.5 Electrolyte was added to the model battery, and the powder was cold-pressed at 350 MPa for at least 5 minutes using a tablet press; 15 mg of composite cathode powder was added to one side of the model battery, and cold-pressed at 350 MPa for at least 5 minutes using a tablet press; a thickness of 0.15 mm was then added... An indium sheet is attached to the other side of the model battery, and the sheet is cold-pressed at 100MPa for more than 5 minutes using a tablet press to assemble the all-solid-state battery.

[0056] Example 2

[0057] This embodiment provides a method for preparing an all-solid-state battery:

[0058] Preparation method of solid electrolyte (Li 2.15 Zr 0.85 Fe 0.15 F1Cl5): Raw materials LiCl (>99%), ZrCl4 (>99%), LiF (>99%), and FeCl3 (>99%) were placed in an oven at 120℃ and vacuum dried for 10 hours to remove moisture. LiCl, LiF, ZrCl4, and FeCl3 were weighed according to the stoichiometric ratio (molar ratio of LiCl, LiF, ZrCl4, and FeCl3 was 1.15:1:0.85:0.15), ground and premixed, and then added to a ball mill jar. Zirconia grinding beads (ball-to-material ratio 5:1) were added, argon gas was introduced, and the jar was sealed. The jar was then ball-milled at a low speed of 400 rpm for 1.5 hours, followed by ball-milling at a high speed of 400 rpm for 40 hours. After ball milling, LiCl4 was removed. 2.15 Zr 0.85 Fe 0.15 F1Cl5 electrolyte was ground evenly and calcined in a tube furnace at 400℃ under argon gas for 10 hours to obtain Li. 2.15 Zr 0.85 Fe 0.15 F1Cl5 solid electrolyte.

[0059] Preparation method of all-solid-state battery: NCM811 cathode material and Super-P, Li 2.15 Zr 0.85 Fe 0.15 F1Cl5 electrolyte was ground uniformly in a 6:1:3 ratio and then ball-milled at 300 rpm for 6 hours in a zirconium oxide ball mill jar to prepare composite cathode powder; 100 mg of Li was then taken... 2.15 Zr 0.85 Fe 0.15 F1Cl5 electrolyte was added to the model battery, and the powder was cold-pressed at 350 MPa for at least 5 minutes using a tablet press; 15 mg of composite cathode powder was added to one side of the model battery, and cold-pressed at 350 MPa for at least 5 minutes using a tablet press; a thickness of 0.15 mm was then added... An indium sheet is attached to the other side of the model battery, and the sheet is cold-pressed at 100MPa for more than 5 minutes using a tablet press to assemble the all-solid-state battery.

[0060] Example 3

[0061] This embodiment provides a method for preparing an all-solid-state battery:

[0062] Preparation method of solid electrolyte (Li 2.15 Zr 0.85 Fe 0.15 F 1.5 Cl 4.5 The raw materials LiCl (>99%), ZrCl4 (>99%), LiF (>99%), and FeCl3 (>99%) were vacuum dried in an oven at 180℃ for 6 hours to remove moisture. LiCl, LiF, ZrCl4, and FeCl3 were weighed according to stoichiometric ratio (molar ratio of LiCl, LiF, ZrCl4, and FeCl3 was 0.65:1.5:0.85:0.15), ground and premixed, and then added to a ball mill jar. Zirconia grinding beads (ball-to-material ratio 40:1) were added, argon gas was introduced, and the jar was sealed. The mixture was then ball-milled at a low speed of 200 rpm for 2.5 hours, followed by high-speed ball milling at 400 rpm for 24 hours. After ball milling, the LiCl4, ZrCl4, and FeCl3 were removed. 2.15 Zr 0.85 Fe 0.15 F 1.5 Cl 4.5 The electrolyte was ground uniformly and placed in a tube furnace for calcination at 280°C under argon gas for 4 hours to obtain Li. 2.15 Zr 0.85 Fe 0.15 F 1.5 Cl 4.5 Solid electrolyte.

[0063] Preparation method of all-solid-state battery: NCM811 cathode material and Super-P, Li 2.15 Zr 0.85 Fe 0.15 F 1.5 Cl 4.5 The electrolytes were ground uniformly in a 6:1:3 ratio and then ball-milled at 300 rpm for 6 hours in a zirconium oxide ball mill jar to prepare composite cathode powder; 100 mg of Li was taken 2.15 Zr 0.85 Fe 0.15 F 1.5 Cl 4.5 Electrolyte was added to the model battery, and the powder was cold-pressed at 350 MPa for at least 5 minutes using a tablet press; 15 mg of composite cathode powder was added to one side of the model battery, and cold-pressed at 350 MPa for at least 5 minutes using a tablet press; a thickness of 0.15 mm was then added... An indium sheet is attached to the other side of the model battery, and the sheet is cold-pressed at 100MPa for more than 5 minutes using a tablet press to assemble the all-solid-state battery.

[0064] Example 4

[0065] In this embodiment, the only difference is that the process of preparing the solid electrolyte is changed from low-speed ball milling at 300 rpm for 2 hours followed by high-speed ball milling at 500 rpm for 36 hours to low-speed ball milling at 300 rpm for 38 hours. All other conditions are the same as in Example 1.

[0066] Example 5

[0067] In this embodiment, the only difference is that the low-speed ball milling at 300 rpm for 2 hours followed by high-speed ball milling at 500 rpm for 36 hours in the solid electrolyte preparation method is replaced with high-speed ball milling at 500 rpm for 38 hours. All other conditions are the same as in Example 1.

[0068] Example 6

[0069] In this embodiment, the conditions are the same as in Example 1, except that the calcination at 400°C with argon gas for 10 hours in a tubular furnace is replaced with calcination at 200°C with argon gas for 5 hours in a tubular furnace.

[0070] Example 7

[0071] In this embodiment, the conditions are the same as in Example 1, except that the calcination at 400°C with argon gas for 10 hours is replaced with calcination at 600°C with argon gas for 10 hours.

[0072] Comparative Example 1

[0073] This comparative example provides a method for preparing an all-solid-state battery:

[0074] Preparation method of solid electrolyte (Li 2.5 Zr 0.5 Fe 0.5 Cl6): Raw materials LiCl (>99%), ZrCl4 (>99%), and FeCl3 (>99%) were vacuum dried in an oven at 150℃ for 8 hours to remove moisture. LiCl, ZrCl4, and FeCl3 were weighed according to stoichiometric ratio (molar ratio of LiCl, ZrCl4, and FeCl3 was 2.5:0.5:0.5), ground and premixed, and then added to a ball mill jar. Zirconia grinding beads were added (ball-to-material ratio 20:1). Argon gas was introduced and the jar was sealed. The mixture was ball-milled at a low speed of 300 rpm for 2 hours, followed by ball-milling at a high speed of 500 rpm for 36 hours. After ball milling, LiCl was removed. 2.5 Zr 0.5 Fe 0.5 Cl6 electrolyte was ground evenly and placed in a tube furnace for calcination at 350℃ under argon gas for 10 hours to obtain Li. 2.5 Zr 0.5 Fe 0.5 Cl6 solid electrolyte.

[0075] The preparation method of the all-solid-state battery is the same as that in Example 1.

[0076] Comparative Example 2

[0077] This comparative example provides a method for preparing an all-solid-state battery:

[0078] Preparation method of solid electrolyte (Li 2.25 Zr 0.75 Fe 0.25 Cl6: Raw materials LiCl (>99%), ZrCl4 (>99%), and FeCl3 (>99%) were vacuum dried in an oven at 150℃ for 8 hours to remove moisture. LiCl, ZrCl4, and FeCl3 were weighed according to stoichiometric ratio (molar ratio of LiCl, ZrCl4, and FeCl3 was 2.25:0.75:0.25), ground and premixed, and then added to a ball mill jar. Zirconia grinding beads were added (ball-to-material ratio 20:1). Argon gas was introduced and the jar was sealed. The mixture was ball-milled at a low speed of 300 rpm for 2 hours, followed by ball-milling at a high speed of 500 rpm for 36 hours. After ball milling, LiCl was removed. 2.25 Zr 0.75 Fe 0.25 Cl6 electrolyte was ground evenly and placed in a tube furnace for calcination at 350°C under argon gas for 10 hours to obtain Li. 2.25 Zr 0.75 Fe 0.25 Cl6 solid electrolyte.

[0079] The preparation method of the all-solid-state battery is the same as that in Example 1.

[0080] Comparative Example 3

[0081] This comparative example provides a method for preparing an all-solid-state battery:

[0082] Preparation method of solid electrolyte (Li 2.15 Zr 0.85 Fe 0.15 Cl6: Raw materials LiCl (>99%), ZrCl4 (>99%), and FeCl3 (>99%) were vacuum dried in an oven at 150℃ for 8 hours to remove moisture. LiCl, ZrCl4, and FeCl3 were weighed according to stoichiometric ratio (molar ratio of LiCl, ZrCl4, and FeCl3 was 2.15:0.85:0.15), ground and premixed, and then added to a ball mill jar. Zirconia grinding beads were added (ball-to-material ratio 20:1). Argon gas was introduced and the jar was sealed. The mixture was ball-milled at a low speed of 300 rpm for 2 hours, followed by ball-milling at a high speed of 500 rpm for 36 hours. After ball milling, LiCl was removed. 2.15 Zr 0.85 Fe 0.15 Cl6 electrolyte was ground evenly and placed in a tube furnace for calcination at 350°C under argon gas for 10 hours to obtain Li. 2.15 Zr 0.85 Fe 0.15 Cl6 solid electrolyte.

[0083] The preparation method of the all-solid-state battery is the same as that in Example 1.

[0084] Comparative Example 4

[0085] This comparative example provides a method for preparing an all-solid-state battery:

[0086] Preparation method of solid electrolyte (Li2ZrCl6: raw materials LiCl (>99%), ZrCl4 (>99%), placed in an oven at 150℃ and vacuum dried for 8h to remove water, LiCl and ZrCl4 were weighed according to stoichiometric ratio (LiCl:ZrCl4 molar ratio of 2:1), ground and premixed and added to a ball mill jar, zirconia ball milling beads were added (ball-to-material ratio of 20:1), argon gas was introduced and sealed, and ball milling was carried out at a low speed of 300rpm for 2h, followed by high speed ball milling at 500rpm for 36h; after ball milling, the Li2ZrCl6 electrolyte was taken out, ground evenly and placed in a tube furnace at 350℃ and calcined with argon gas for 10h to obtain Li2ZrCl6 solid electrolyte.

[0087] The preparation method of the all-solid-state battery is the same as that in Example 1.

[0088] The charge-discharge curves and cycle test graphs of the all-solid-state batteries corresponding to Embodiment 1, Comparative Example 3, and Comparative Example 4 of this invention are shown below. Figure 1 As shown.

[0089] The internal resistance, thickness, ionic conductivity and electrochemical stability window of the all-solid-state batteries prepared in Examples 1-7 and Comparative Examples 1-4 were tested, and the test results are shown in Table 1.

[0090] The method for testing ionic conductivity is as follows: 80-120 mg of the solid electrolyte from Examples 1-7 and Comparative Examples 1-4 after calcination is added to the model battery, the powder is cold-pressed at 350 MPa for more than 5 minutes using a tablet press, a stainless steel battery is assembled, and the ionic conductivity is tested using an electrochemical workstation at a frequency of 4 MHz to 0.1 Hz.

[0091] The method for testing the electrochemical stability window is as follows: Take 80-120 mg of the solid electrolyte from Examples 1-7 and Comparative Examples 1-4 and add it to the model battery (inner diameter). In the process, the powder was cold-pressed at 350MPa for more than 5 minutes using a tablet press; Super-P and electrolyte were ground and mixed evenly at a ratio of 1:2, and 20mg of the mixture was placed into one side of the model battery and cold-pressed at 350MPa for more than 5 minutes using a tablet press; In-Li alloy was assembled at a ratio of In:Li = 40:1 and attached to the other side of the model battery and cold-pressed at 100MPa for more than 5 minutes using a tablet press; LSV testing was performed using an electrochemical workstation, with a scan range from open circuit voltage to 7V and a scan rate of 0.0005V / s.

[0092] Table 1

[0093]

[0094] As shown in the table above, this invention significantly increases the ionic conductivity of the material by introducing Fe (a metallic element) while reducing costs. Furthermore, the addition of fluorine greatly enhances the electrochemical stability window, giving the material both high electrochemical stability and good ionic conductivity. This combined effect results in higher charge / discharge capacity and cycle stability for the all-solid-state battery. Appropriate ball milling speed and time ensure uniform synthesis of the electrolyte with high purity. Suitable calcination temperature and time result in a better crystal structure and orientation for the electrolyte.

[0095] As can be seen from the comparison of Examples 1-3, doping with Fe (a metallic element) can reduce costs while maximizing the ionic conductivity of the material. Doping with F can improve the interfacial stability of the battery and increase the electrochemical window. While increasing the doping amount of F improves the electrochemical window and interfacial stability, doping with F will cause a significant decrease in ionic conductivity. Therefore, it is necessary to balance the doping amounts of Fe and F to coordinate ionic conductivity and electrochemical stability window. The goal is to significantly increase the electrochemical stability window to enhance cycle stability while maintaining high ionic conductivity and good lithium-ion transport capability.

[0096] A comparison of Examples 1 and 4-7 shows that replacing the two-stage ball milling with a single stage of excessively high-speed ball milling, or ball milling at excessively high speed, worsens the uniformity of the electrolyte, leading to decreased battery purity, increased internal resistance, and decreased ionic conductivity. Excessively high or low calcination temperatures result in unstable electrolyte lattice structure and orientation, increasing battery internal resistance and decreasing ionic conductivity.

[0097] A comparison of Example 1 and Comparative Examples 1-3 shows that without increasing the amount of F, the electrochemical stability window of the battery narrows. With increasing Fe (metal) content, the ionic conductivity of the battery increases. However, excessive doping alters the electrolyte's crystal structure, leading to decreased electrolyte performance.

[0098] A comparison of Example 1 and Comparative Example 1 shows that without increasing the amount of F and metal elements, the internal resistance of the battery increases, the ionic conductivity decreases, and the electrochemical stability window narrows.

[0099] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A halide solid electrolyte, characterized in that, The halide solid electrolyte includes Li 2+a M 1-a N a F b Cl 6-b Where M is Zr, N is Fe, and 0 <a≤0.15,0<b≤2; The halide solid electrolyte is prepared by the following method, which includes the following steps: Dry LiCl, LiF, MCl x and NCl y The halide solid electrolyte is obtained by sequentially performing a first ball milling and calcination treatment, wherein x is 3 or 4, and 2≤y≤4; The first ball mill includes a low-speed ball mill and a high-speed ball mill; the speed of the low-speed ball mill is 200~400 rpm; the speed of the high-speed ball mill is 400~800 rpm. The calcination temperature is 280~400℃.

2. A method for preparing a halide solid electrolyte as described in claim 1, characterized in that, The preparation method includes: Dry LiCl, LiF, MCl x and NCl y The halide solid electrolyte is obtained by sequentially performing a first ball milling and calcination treatment, wherein x is 3 or 4, and 2≤y≤4; The first ball mill includes a low-speed ball mill and a high-speed ball mill; the speed of the low-speed ball mill is 200~400 rpm; the speed of the high-speed ball mill is 400~800 rpm. The calcination temperature is 280~400℃.

3. The preparation method according to claim 2, characterized in that, The LiCl, LiF, MCl x and NCl y The molar ratio is (0.5~3):(0.1~2):(0.1~1):(0.1~1).

4. The preparation method according to claim 2, characterized in that, The drying temperature is 120~180℃.

5. The preparation method according to claim 2, characterized in that, The drying time is 6-10 hours.

6. The preparation method according to claim 2, characterized in that, A first grinding process is performed before the first ball milling.

7. The preparation method according to claim 2, characterized in that, The atmosphere in the first ball mill includes an argon atmosphere.

8. The preparation method according to claim 2, characterized in that, The ball-to-material ratio of the first ball mill is (5~40):

1.

9. The preparation method according to claim 2, characterized in that, The low-speed ball milling time is 1.5~2.5h.

10. The preparation method according to claim 2, characterized in that, The high-speed ball milling time is 24~40h.

11. The preparation method according to claim 2, characterized in that, The atmosphere for the calcination treatment includes an argon atmosphere.

12. The preparation method according to claim 2, characterized in that, The calcination treatment time is 3 to 10 hours.

13. A method for preparing an all-solid-state battery, characterized in that, The all-solid-state battery includes the halide solid electrolyte as described in claim 1, and the preparation method includes: (1) The first halide solid electrolyte, the positive electrode material and the conductive agent are sequentially subjected to a second grinding and a second ball milling to obtain composite positive electrode powder; (2) Add the second halide solid electrolyte to the model battery, perform the first cold pressing treatment, add the composite positive electrode powder described in step (1) to one side of the model battery, perform the second cold pressing treatment, attach the negative electrode metal sheet to the other side of the model battery, and perform the third cold pressing treatment to obtain an all-solid-state battery.

14. The preparation method according to claim 13, characterized in that, The positive electrode material in step (1) includes any one or a combination of at least two of NCM622, NCN712, NCM811, lithium iron phosphate, lithium manganese oxide, or lithium cobalt oxide.

15. The preparation method according to claim 13, characterized in that, The conductive agent in step (1) includes any one or a combination of at least two of conductive carbon black, graphene, carbon nanotubes or carbon nanofibers.

16. The preparation method according to claim 13, characterized in that, Based on the mass of the composite cathode powder being 100%, the first halide solid electrolyte in step (1) accounts for 15~40wt% of the mass fraction of the composite cathode powder.

17. The preparation method according to claim 13, characterized in that, Based on the mass of the composite cathode powder being 100%, the cathode material in step (1) accounts for 55~80 wt% of the mass of the composite cathode powder.

18. The preparation method according to claim 13, characterized in that, Based on the mass of the composite positive electrode powder being 100%, the conductive agent in step (1) accounts for 2~10 wt% of the mass of the composite positive electrode powder.

19. The preparation method according to claim 13, characterized in that, Step (1) The second ball milling time is 4~8 hours.

20. The preparation method according to claim 13, characterized in that, Step (1) The speed of the second ball mill is 200~400 rpm.

21. The preparation method according to claim 13, characterized in that, In step (2), the mass of the second halide solid electrolyte is 80~120 mg.

22. The preparation method according to claim 13, characterized in that, The mass of the composite cathode powder in step (2) is 10~30mg.

23. The preparation method according to claim 13, characterized in that, The negative electrode metal sheet in step (2) includes any one of Li-Fe alloy, Li-In alloy, Li-Mg alloy, Li-Zn alloy, Li-Al alloy, indium sheet or lithium sheet.

24. The preparation method according to claim 13, characterized in that, The thickness of the negative electrode metal sheet in step (2) is 0.1~0.2mm.

25. The preparation method according to claim 13, characterized in that, In step (2), the pressure of the first cold pressing process is 300~500 MPa.

26. The preparation method according to claim 13, characterized in that, Step (2) The time for the first cold pressing treatment is ≥5 min.

27. The preparation method according to claim 13, characterized in that, In step (2), the pressure of the second cold pressing process is 300~400 MPa.

28. The preparation method according to claim 13, characterized in that, Step (2) The second cold pressing process takes ≥5 minutes.

29. The preparation method according to claim 13, characterized in that, The pressure of the third cold pressing process in step (2) is 50~150 MPa.

30. The preparation method according to claim 13, characterized in that, The time for the third cold pressing process in step (2) is ≥5 min.

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