Multi-element co-doped garnet solid electrolyte as well as preparation method and application thereof

Abstract

The invention relates to the technical field of lithium ion batteries, and discloses a multi-element co-doped garnet solid electrolyte and a preparation method and application thereof.The solid electrolyte is a compound with the following chemical formula structure: (Li < 1 + alpha > A < 1m + t >) (La < 3 + 3-uD < 2 + u >) (Zr < 4 + x > Hf < 4 + y > Y < 3 + z > Ta < 5 + v > Mr + w) (O < 2-12-oEs-o), chemical valence balance is met, alpha is smaller than or equal to 6.8, y is smaller than or equal to 0.07, y is smaller than or equal to 0.07, and y is smaller than or equal to 0.07. V + w + x + y + z = 2, and the range among v, w, x and y does not exceed 50% of the maximum value. According to the multi-element co-doped garnet solid electrolyte provided by the invention, the ionic conductivity can be remarkably improved, the activation energy can be reduced, the air stability can be greatly improved, and the applicability is wide.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a multi-component co-doped garnet solid electrolyte, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries have been widely used in portable electronic devices and new energy electric vehicles due to their high energy density and environmental friendliness. However, most commercially available lithium-ion batteries currently use flammable organic liquid electrolytes, posing safety hazards.

[0003] All-solid-state batteries, assembled by replacing electrolytes with inorganic solid-state electrolytes, can fundamentally improve battery safety performance. Among them, garnet solid-state electrolytes such as Li7La3Zr2O... 12 Due to its good electrochemical stability, LLZO is widely considered a promising candidate material for solid-state batteries. However, its room-temperature ionic conductivity is relatively low compared to sulfide electrolytes, typically around 1 mS / cm, which hinders its application in all-solid-state batteries. It is usually used in conjunction with electrolytes for in-situ solidification assembly of semi-solid-state batteries.

[0004] Multi-element co-doping can significantly enhance ionic conductivity and lower activation energy in materials substituted with multiple elements, and has been well applied in fields such as sulfide electrolytes. However, the ionic conductivity of garnet solid electrolyte LLZO has not yet been effectively improved by employing a multi-element co-doping strategy. For example, the literature (Feng, Yitian, et al. “Rational Design of High-Entropy Garnet Electrolytes via Computational Screening for Stable Lithium Interfaces in All-Solid-State Batteries.” Advanced Materials 37(41) (2022): e0938) discloses a multi-element co-doped Li 6.6 La3Zr 0.4 Sn 0.4 Hf 0. 4Sc 0.2 Ta 0.6 O 12 Garnet solid electrolytes are available, but their ionic conductivity is only 0.4 mS / cm, which limits their industrial application. In addition, current garnet solid electrolytes usually have problems such as poor air stability. Summary of the Invention

[0005] The main objective of this invention is to provide a multi-component co-doped garnet solid electrolyte with higher room temperature ionic conductivity, lower activation energy, and good air stability.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a multi-component co-doped garnet solid electrolyte having a compound with the chemical structure shown in formula (I). (Li 1+ α A1 m+ t (La) 3+ 3-u D 2+ u (Zr) 4+ x Hf 4+ y Y 3+ z Ta 5+ v M r+ w (O) 2- 12-o E s- o (1); Wherein, α satisfies the valence equilibrium requirement, and α≤6.8; A1 is selected from at least one of Na, Li, and Mg; m is 1 or 2, and t is selected from any value from 0 to 0.75; D is selected from at least one of Ca, Sr, and Ba; u is selected from any value from 0 to 1; M is selected from one or more of Nb, Mo, and W; r takes any integer value from 4 to 6, and w takes a value from 0.01 to 0.52; E is selected from at least one of F, S, and N; s is any integer from 1 to 3, and o takes the value from 0 to 2; x ranges from 0.38 to 0.52; y ranges from 0.38 to 0.52; z ranges from 0.38 to 0.52; v ranges from 0.38 to 0.52; w ranges from 0.01 to 0.52. Furthermore, v+w+x+y+z=2, and the range between v, x, y and z does not exceed 50% of the maximum value.

[0007] A second aspect of the present invention provides a method for preparing the above-mentioned multi-component co-doped garnet solid electrolyte, comprising the following steps: (1) The precursor materials are mixed to obtain mixture I; The precursor material is selected from at least one of the oxides, fluorides, sulfides, nitrides of the metal source corresponding to formula (1) and metal compounds that can form the corresponding metal source oxide after calcination. The metal sources include Li source, Al source, La source, D source, Zr source, Hf source, Y source, Ta source, M source, and E source; (2) The mixture I is subjected to multi-stage heat treatment to obtain a multi-element co-doped garnet solid electrolyte.

[0008] A third aspect of the present invention provides a solid electrolyte membrane containing a solid electrolyte and a binder; the content of the solid electrolyte is ≥80 wt% based on the total mass of the solid electrolyte membrane; the solid electrolyte includes the multi-component co-doped garnet solid electrolyte described in the first aspect above.

[0009] A fourth aspect of the present invention provides a cathode material comprising an intermediate layer and a solid electrolyte coating at least a portion of the surface of the intermediate layer; wherein the solid electrolyte is the multi-component co-doped garnet solid electrolyte described in the first aspect above.

[0010] A fifth aspect of the present invention provides a lithium-ion battery comprising a positive electrode, a negative electrode, and an electrolyte; wherein the positive electrode active material in the positive electrode and / or the electrolyte contains the multi-component co-doped garnet solid electrolyte described in the first aspect above.

[0011] This invention promotes the increase of solid electrolyte configuration entropy and lithium vacancy concentration by co-doping with multiple elements (simultaneously doping with multiple metal elements and non-metal elements), which can form ion percolation and thus effectively reduce the activation energy barrier for lithium ion migration. Combined with a multi-stage heat treatment process based on temperature control, cooling control and calcination atmosphere regulation, it promotes the development of garnet-type solid electrolytes with high room temperature ionic conductivity, low activation energy and high air stability.

[0012] Compared with the prior art, the effective effects of the present invention include: 1) The multi-component co-doped garnet solid electrolyte provided by this invention can significantly improve ionic conductivity (by several times) and significantly reduce activation energy compared with currently commercialized garnet electrolytes, while also taking into account excellent air stability.

[0013] 2) The composite electrolyte membrane prepared based on the solid electrolyte of the present invention not only has good mechanical properties, but also significantly improved room temperature ionic conductivity, which can promote the preparation of thinner composite electrolyte membranes.

[0014] 3) The cathode material prepared based on the solid electrolyte of the present invention can exhibit good interfacial electrochemical stability when matched with sulfide or halide electrolytes. Attached Figure Description

[0015] Figure 1 The XRD patterns are of the multi-component co-doped garnet solid electrolytes prepared in Examples 1-2 and Comparative Examples 6-8. Figure 2 XRD patterns of the multi-component co-doped garnet solid electrolytes prepared in Examples 4-5; Figure 3 XRD patterns of the multi-component co-doped garnet solid electrolytes prepared in Comparative Examples 1-4; Figure 4 The XRD patterns are of the multi-component co-doped garnet solid electrolytes prepared in Comparative Examples 11-12. Figure 5 Impedance spectra of the multi-component co-doped garnet solid electrolytes prepared in Examples 1-2 and Comparative Examples 6-7; Figure 6 The multi-component co-doped garnet solid electrolytes prepared in Examples 4-5 of Impedance spectrum; Figure 7 Impedance spectra of the multi-component co-doped garnet solid electrolytes prepared in Comparative Examples 11-12; Figure 8 Comparison of ionic conductivity of the multi-component co-doped garnet solid electrolytes prepared in Examples 1-5 and Comparative Examples 7, 11, and 12 after being placed in air for 0 h, two weeks, and two months, respectively. Figure 9 Impedance spectra of the multi-component co-doped garnet solid electrolyte prepared in Example 1 after being placed in air for 0 h, two weeks and two months, respectively. Figure 10 Impedance spectra of the multi-component co-doped garnet solid electrolyte prepared in Example 2 after being placed in air for 0 h, two weeks and two months; Figure 11 Impedance spectra of the multi-component co-doped garnet solid electrolyte prepared in Example 3 after being placed in air for 0 h, two weeks and two months; Figure 12 Impedance spectra of the multi-component co-doped garnet solid electrolyte prepared in Example 4 after being placed in air for 0 h, two weeks, and two months; Figure 13 Impedance spectra of the multi-component co-doped garnet solid electrolyte prepared in Example 5 after being placed in air for 0 h, two weeks and two months; Figure 14 Impedance spectra of the multi-component co-doped garnet solid electrolyte prepared for Comparative Example 7 after being placed in air for 0 h, two weeks and two months; Figure 15 Impedance spectra of the multi-component co-doped garnet solid electrolyte prepared for Comparative Example 11 after being placed in air for 0 h, two weeks and two months. Figure 16 Impedance spectra of the multi-component co-doped garnet solid electrolyte prepared for Comparative Example 12 after being placed in air for 0 h, two weeks and two months. Figure 17 SEM image of the multi-component co-doped garnet solid electrolyte prepared in Example 1; Figure 18 This is a photograph of the solid electrolyte membrane used in Application Example 1; Figure 19 The graph shows the charge-discharge cycle results of the all-solid-state lithium-ion batteries in Application Example 1 and Application Comparative Example 1 under room temperature conditions. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] The room temperature ionic conductivity mentioned in this invention refers to the ionic conductivity at 23~27℃.

[0018] As previously stated, a first aspect of the present invention provides a multi-component co-doped garnet solid electrolyte having a compound of the chemical formula shown in formula (1). (Li 1+ α A1 m+ t ) (La 3+ 3-u D 2+ u (Zr) 4+ x Hf 4+ y Y 3+ z Ta 5+ v M r+ w (O) 2- 12-o E s- o (1); Wherein, α satisfies the valence equilibrium requirement, and α≤6.8; A1 is selected from at least one of Na, Li, and Mg; m is 1 or 2, and t takes the value 0 to 0.75; For example, t can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, or 0.75, with a preferred value of 0 to 0.5. D is selected from at least one of Ca, Sr, and Ba; u takes values ​​from 0 to 1, for example, u can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0; M is selected from one or more of Nb, Mo, and W; w takes a value of 0.01 to 0.52; E is selected from at least one of F, S, and N; s is any integer from 1 to 3; o takes the value from 0 to 2, for example, o can be 0, 0.5, 1.0, 1.5, 2.0, preferably o is any value from 0 to 1; x takes values ​​from 0.38 to 0.52; y takes values ​​from 0.38 to 0.52; z takes values ​​from 0.38 to 0.52; v takes values ​​from 0.38 to 0.52; and w takes values ​​from 0.01 to 0.52. Furthermore, v+w+x+y+z=2; the range between v, z, x and y does not exceed 50% of the maximum value, preferably not more than 20% of the maximum value, and more preferably the range between v, z, x and y is 0.

[0019] The solid electrolyte provided by this invention employs specific types of multi-metal elements for co-doping (simultaneous doping with multiple metal elements and non-metal elements), and strictly limits the content of the doped metal elements to meet the specific requirements of this invention. This can increase the configurational entropy of the solid electrolyte, achieve ion percolation, and thus reduce the activation energy barrier for lithium ion migration. Furthermore, by combining a multi-stage heat treatment process based on temperature control, cooling control, and calcination atmosphere regulation, it can promote the improvement of high room temperature ionic conductivity and low activation energy of the solid electrolyte, while also improving the air stability of the resulting electrolyte to a certain extent.

[0020] In some embodiments of the present invention, when M is Nb or Mo, r = 5; when M is W, r = 6.

[0021] In some embodiments of the present invention, when E is S, s=2; when E is N, s=3.

[0022] According to a preferred embodiment, in formula (I), A1 is selected from at least one of Li, Na, and Mg; m is 1 or 2, and t is selected from any value from 0 to 0.5; D is selected from at least one of Ca and Sr; u is selected from any value from 0 to 1; M is any one of Nb, Mo, and W; w is any value between 0.4 and 0.5. E is selected from at least one of F and N; s is 1 or 3, and o is selected from any value from 0 to 2; v is selected from any value between 0.4 and 0.5; y is selected from any value between 0.4 and 0.5; Furthermore, v+w+x+y+z=2, and the range between v, z, x and y does not exceed 50% of the maximum value.

[0023] In a preferred embodiment, in formula (I), Al is Li, M is Nb, o is selected from any value from 0 to 1, and t is selected from any value from 0 to 0.25. The multi-component co-doped garnet solid electrolyte satisfying this preferred characteristic exhibits higher room-temperature ionic conductivity and lower activation energy.

[0024] According to some particularly preferred embodiments, the solid electrolyte is selected from at least one of the following: Li 6.6 La 3.0 Zr 0.4 Hf 0.4 Y 0.4 Ta 0.4 Nb 0.4 O 12 ; Li 6.4 La 3.0 Zr 0.4 Hf 0.4 Y 0.4 Ta 0.4 Nb 0.4 O 11.9 F 0.1 ; Li 6.4 Mg 0.1 La 3.0 Zr 0.4 Hf 0.4 Y 0.4 Ta 0.4 Nb 0.4 O 12 ; Li 5.6 La 3.0 Zr 0.4 Hf 0.4 Y 0.4 Ta 0.4 Nb 0.4 O 11 F1; Li 6.7 La 3.0 Zr 0.4 Hf 0.4 Y 0.4 Ta 0.4 Nb 0.4 O 11 N 0.1 .

[0025] In a preferred embodiment, the room temperature ionic conductivity of the multi-component co-doped garnet solid electrolyte is ≥1 mS / cm, preferably ≥2.0 mS / cm, more preferably ≥2.5 mS / cm, and particularly preferably ≥3.5 mS / cm.

[0026] Preferably, the activation energy of the multi-element co-doped garnet solid electrolyte is ≤0.35 eV, more preferably ≤0.3 eV, more preferably ≤0.25 eV, and particularly preferably ≤0.2 eV.

[0027] As previously described, a second aspect of the present invention provides a method for preparing the multi-component co-doped garnet solid electrolyte described in the first aspect, the method comprising: (1) The precursor materials are mixed to obtain mixture I; The precursor material is selected from at least one of the oxides, fluorides, sulfides, nitrides of the metal source corresponding to formula (1), and metal compounds that can form the oxide form of the metal source after calcination. The metal source includes Li source, Al source, La source, D source, Zr source, Hf source, Y source, Ta source, M source, and E source; the Al source is selected from at least one of Li, Na, and Mg; the D source is selected from at least one of Ca, Sr, and Ba; and the M source is selected from any one of Nb, Mo, and W. (2) The mixture I is subjected to multi-stage heat treatment to obtain a multi-element co-doped garnet solid electrolyte.

[0028] In this invention, the amount of each substance in the precursor material satisfies the chemical formula shown in formula (1) of the prepared multi-component co-doped garnet solid electrolyte.

[0029] According to a preferred embodiment of the present invention, in step (1), the mixing process is selected from at least one of dry mixing, mechanical vibration, ball milling, and wet milling.

[0030] In some embodiments, the dry mixing conditions include: a rotation speed of 1000~20000 rpm, preferably 8000~12000 rpm; and a time of 1~60 min, preferably 1~10 min.

[0031] In some embodiments, the ball milling mixing conditions include: a rotation speed of 100-800 rpm, preferably 400-800 rpm; and a time of 1-50 h, preferably 16-40 h.

[0032] Preferably, in step (2), the multi-stage heat treatment operation includes: S1: Under the presence of an inert atmosphere, the mixture I is subjected to a first heat treatment and a first cooling treatment in sequence to obtain mixture II; the temperature of the first heat treatment is 800~1100 °C and the time is 6~24h. S2: Under the presence of an inert atmosphere, the mixture II is subjected to a second heat treatment and a second cooling treatment in sequence to obtain mixture III; the temperature of the second heat treatment is 900~1300 °C and the time is 3~24h; S3: In the presence of a high oxygen atmosphere, the mixture III is subjected to a third heat treatment and a third cooling treatment in sequence to obtain the multi-element co-doped garnet solid electrolyte; the temperature of the third heat treatment is 500~900°C and the time is 3~24h.

[0033] In a preferred embodiment, the heating rates of the first heat treatment, the second heat treatment, and the third heat treatment are each 4-6°C / min independently.

[0034] Preferably, the cooling rates of the first cooling treatment, the second cooling treatment, and the third cooling treatment are each 4-6°C / min independently.

[0035] Preferably, the endpoint temperatures of the first cooling treatment and the second cooling treatment are each independently controlled to be between 30 and 200°C.

[0036] Furthermore, the temperature of the third heat treatment is lower than that of the second heat treatment.

[0037] According to a preferred embodiment of the present invention, the method in step (2) further includes: before performing the third heat treatment, grinding and pressing the mixture III in sequence.

[0038] The present invention does not impose any particular restrictions on the specific conditions of the grinding and pressing. Those skilled in the art can make selections based on known technical means in the art. For example, the mixture III is ground until there are no obviously large particles (e.g., particle diameter greater than 50 μm) and pressed into ceramic sheets under 2-3 tons.

[0039] Preferably, in steps S1 and S2, the inert atmosphere is selected from at least one of argon and nitrogen.

[0040] Preferably, in step S3, the oxygen volume content of the oxygen-containing atmosphere is 80-100%.

[0041] As previously stated, a third aspect of the present invention provides a solid electrolyte membrane containing a solid electrolyte and a binder; the content of the solid electrolyte is ≥80 wt% based on the total mass of the solid electrolyte membrane; the solid electrolyte includes the multi-component co-doped garnet solid electrolyte described in the first aspect above.

[0042] The binder described in this invention serves to bind electrolyte particles. Preferably, the binder is selected from at least one of polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), hydrogenated nitrile butadiene rubber (HNBR), nitrile butadiene rubber (NBR), styrene-ethylene-butene-styrene block copolymer (SEBS), styrene-butadiene-styrene block copolymer (SBS), polytetrafluoroethylene, and thermoplastic polyamide.

[0043] The present invention does not impose any particular limitation on the method for preparing the solid electrolyte membrane. Those skilled in the art can choose from the techniques known in the art. However, in order to obtain a solid electrolyte membrane with higher room temperature ionic conductivity and lower activation energy, the present invention preferably uses the following method to prepare the solid electrolyte membrane.

[0044] According to a preferred embodiment of the present invention, the method for preparing the solid electrolyte membrane includes: dispersing a solid electrolyte and a binder in the presence of an organic solvent to obtain a dispersion; and then sequentially casting and drying the dispersion to obtain the solid electrolyte membrane.

[0045] In a preferred embodiment, the organic solvent is selected from at least one of acetonitrile, toluene, p-xylene, anisole, ethyl acetate, and butyl butyrate.

[0046] In a preferred embodiment, the method for preparing the solid electrolyte membrane further includes: hot-pressing the product obtained after drying to obtain the solid electrolyte membrane.

[0047] The present invention does not impose any particular requirements on the methods of dispersion treatment, casting, drying and hot pressing, and those skilled in the art can use methods known in the art.

[0048] As previously stated, a fourth aspect of the present invention provides a cathode material comprising an intermediate layer and a solid electrolyte coating at least a portion of the surface of the intermediate layer; the solid electrolyte is the multi-component co-doped garnet solid electrolyte described in the first aspect above.

[0049] The present invention does not impose any particular restrictions on the specific operation of coating the solid electrolyte on the surface of the intermediate layer. Those skilled in the art can make selections based on known technical means in the art. The present invention provides a preferred specific embodiment in the following description, which should not be construed as a limitation of the present invention.

[0050] According to a preferred embodiment 1, the coating method is as follows: the multi-component co-doped garnet solid electrolyte and the intermediate layer are ball-milled and mixed to obtain the positive electrode material.

[0051] According to a preferred embodiment 2, the coating method is as follows: the corresponding raw materials for preparing the multi-component co-doped garnet solid electrolyte are dissolved in a solvent at a certain molar ratio to form a precursor solution, and then the intermediate layer is added thereto. After evaporating the solvent, a heating treatment is performed. The heating treatment conditions include: a temperature of 500~1200°C and a time of 1~6h.

[0052] Preferably, the coating thickness of the multi-component co-doped garnet solid electrolyte is 1~1000nm, more preferably 1~200nm, and even more preferably 5~10nm.

[0053] In a preferred embodiment, the intermediate layer is selected from at least one of the compounds shown in formula (2), formula (3), formula (4), formula (5), and formula (6); LiCoO2 formula (2); LiNi x1 Mn y1 Co 1-x1-y1 O2 formula (3); LiNi 1-x2-y2 Co x2 Al y2 O2 formula (4); LiNi x3 Mn 1-x3 O2 type (5); Li 1+x4 GO2 (6); Among them, x1, x2, x3, x4, y1, and y2 are each independently selected from any value between 0 and 1; G is selected from any one of Mn, Ni, Co, and Al.

[0054] As previously described, a fifth aspect of the present invention provides a lithium-ion battery comprising a positive electrode, a negative electrode, and an electrolyte; wherein the positive electrode active material in the positive electrode and / or the electrolyte contains the multi-component co-doped garnet solid electrolyte described in the first aspect.

[0055] In a preferred embodiment, the positive electrode includes a positive electrode current collector and a positive electrode active material layer covering the surface of the positive electrode current collector. The positive electrode active material layer contains a positive electrode active substance, a positive electrode binder, a positive electrode electronic conductive agent, and a positive electrode ion conductor. The positive electrode active substance is the positive electrode material described in the fourth aspect above.

[0056] According to a preferred embodiment, the positive electrode is prepared by a method comprising the following steps: The positive electrode active material, the positive electrode binder, the positive electrode electronic conductive agent, the positive electrode ionic conductor, and the solvent are mixed to obtain a positive electrode slurry; the positive electrode slurry is coated onto the surface of the positive electrode current collector, and then dried and rolled to obtain the positive electrode.

[0057] Preferably, the solvent is an organic solvent.

[0058] More preferably, the solvent is selected from at least one of toluene, p-xylene, anisole, acetonitrile, tetrahydrofuran, ethyl acetate, and butyl acetate.

[0059] The present invention does not have special requirements on the amount of solvent used, as long as it is sufficient to make the positive electrode slurry achieve the desired viscosity.

[0060] According to another preferred embodiment, the positive electrode is prepared by a method including the following steps: The positive electrode active material, the positive electrode binder, the positive electrode electronic conductive agent, and the positive electrode ionic conductor are dry-mixed to obtain a composite material, and the composite material is pressed onto the surface of the positive electrode current collector by hot rolling or hot rolling to obtain the positive electrode.

[0061] Preferably, based on the total mass of the composite material, the content of the positive electrode active material is 80-99 wt%, and the content of the positive electrode electronic conductive agent is 1-10 wt%.

[0062] The present invention does not particularly limit the positive electrode current collector, as long as it is conductive and does not cause chemical changes in the battery. For example, the positive electrode current collector can be selected from any one of elemental aluminum, stainless steel, and elemental nickel.

[0063] The positive electrode ion conductor described in this invention provides the function of lithium ion conduction in the positive electrode of a lithium-ion battery. It can be a common inorganic solid electrolyte or a polymer-based solid electrolyte, including but not limited to the aforementioned multi-component co-doped garnet solid electrolyte.

[0064] Preferably, the positive electrode binder is selected from at least one of polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), hydrogenated nitrile butadiene rubber (HNBR), nitrile butadiene rubber (NBR), styrene-ethylene-butene-styrene block copolymer (SEBS), and styrene-butadiene-styrene block copolymer (SBS).

[0065] The positive electrode conductive agent described in this invention is a material that provides conductivity without causing adverse chemical reactions in the battery. Preferably, the positive electrode conductive agent is selected from at least one of conductive carbon black Super-P, acetylene black, conductive carbon black SuperC65, carbon fiber (VGCF), multi-walled carbon nanotubes (MWCNTs), single-walled carbon nanotubes (SWCNTs), and graphene.

[0066] Preferably, the negative electrode includes a negative electrode current collector and a layer of negative electrode active material covering the surface of the negative electrode current collector.

[0067] The present invention does not particularly limit the negative electrode current collector, as long as it is conductive and does not cause chemical changes in the battery. Preferably, the negative electrode current collector is selected from any one of elemental copper, stainless steel, and elemental nickel.

[0068] According to a preferred embodiment, the negative electrode active material layer comprises elemental lithium and / or a lithium alloy, wherein the lithium alloy is selected from any one of lithium indium alloy, lithium magnesium alloy, lithium aluminum alloy, lithium bismuth alloy, lithium tin alloy, and lithium silicon alloy.

[0069] According to another preferred embodiment, the negative electrode active material layer includes a negative electrode active substance, a negative electrode ion conductor, a negative electrode binder, and a negative electrode electronic conductive agent.

[0070] Preferably, the negative electrode active material is a silicon-based active material and / or graphite. More preferably, the negative electrode active material is selected from at least one of elemental silicon, silicon suboxide, silicon carbide, artificial graphite, and natural graphite.

[0071] The negative electrode ion conductor described in this invention provides lithium ion conduction in the negative electrode. Preferably, the negative electrode ion conductor comprises Li7P2S8I, βLi2S-(100-β)P2S5 (70≤β≤80), Li 6-X5-X6 P 1-X6 T X6 S 5-X5-X7 R X7 Z X5+1 At least one of them; Wherein, 0≤X5<1, 0≤X6<1, 0≤X7<1; T is selected from at least one of Ge, Si, Sn, Sb, and As; R is O and / or Se; Z is selected from at least one of Cl, Br, and I.

[0072] The negative electrode binder described in this invention is used to bind the negative electrode active material, the negative electrode ionic conductor, and the negative electrode electronic conductive agent, and to adhere them to the negative electrode current collector.

[0073] Preferably, the negative electrode binder is selected from at least one of polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), nitrile rubber (NBR), styrene-ethylene-butene-styrene block copolymer (SEBS), and styrene-butadiene-styrene block copolymer (SBS).

[0074] Preferably, the negative electrode electronic conductive agent is selected from at least one of conductive carbon black Super-P, acetylene black, conductive carbon black SuperC65, carbon fiber (VGCF), multi-walled carbon nanotubes (MWCNT), single-walled carbon nanotubes (SWCNT), and graphene.

[0075] The present invention will be described in detail below through examples. Unless otherwise specified, the instruments, reagents, and materials involved in the following examples are all conventional instruments, reagents, and materials, which can be obtained through legitimate commercial channels. The room temperature mentioned in the following examples refers to 25±2℃.

[0076] Example 1 A multi-component co-doped garnet solid electrolyte with the stoichiometric formula Li 6.6 La 3.0 Zr 0.4 Hf 0.4 Y 0.4 Ta 0.4 Nb 0.4 O 12 The specific preparation process is as follows: (1) LiOH, La2O3, ZrO2, HfO2, Y2O3, Nb2O5, and Ta2O5 were mixed in a molar ratio of 6.6:1.5:0.4:0.4:0.2:0.2:0.2 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 400 rpm for 30 h. (2) The mixture I was annealed at 850°C in an argon atmosphere for 10 h and cooled to room temperature; then heated to 1100°C and annealed for 8 h and cooled to room temperature; the cooled product was manually ground for 30 min and then pressed at 3t pressure for 3 min, annealed at 700°C in an oxygen stream (oxygen concentration of 99.9 vol %) for 3 h and cooled to room temperature; multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 5 °C / min.

[0077] Example 2 A multi-component co-doped garnet solid electrolyte with the stoichiometric formula Li 6.4 La 3.0 Zr 0.4 Hf 0.4 Y 0.4 Ta 0.4 Nb 0.4 O 11.9 F 0.1 The specific preparation process is as follows: (1) Li2CO3, La2O3, ZrO2, HfO2, Nb2O5, Ta2O5, Y2O3, and LiF were mixed in a molar ratio of 3.15: 1.5: 0.4: 0.4:0.2: 0.2: 0.2:0.1 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 300 rpm for 24 h. (2) The mixture I was annealed in an argon flow at 850°C for 10 h and cooled to room temperature; then annealed at 1100°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 95%) at 750°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 4 °C / min.

[0078] Example 3 A multi-component co-doped garnet solid electrolyte with the stoichiometric formula Li 6.4 Mg 0.1 La 3.0 Zr 0.4 Hf 0.4 Y 0.4 Ta 0.4 Nb 0.4 O 12 The specific preparation process is as follows: (1) Li2CO3, MgO, La2O3, ZrO2, HfO2, Nb2O5, Ta2O5, and Y2O3 were mixed in a molar ratio of 3.2:0.1:1.5:0.4:0.4:0.2:0.2:0.2 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 300 rpm for 24 h. (2) The mixture I was annealed in an argon flow at 850°C for 10 h and cooled to room temperature; then annealed at 1100°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 90%) at 750°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 4 °C / min.

[0079] Example 4 A multi-component co-doped garnet solid electrolyte with the stoichiometric formula Li 5.6 La 3.0 Zr 0.4 Hf 0.4 Y 0.4 Ta 0.4 Nb 0.4 O 11 F1, the specific preparation process is as follows: (1) LiOH, La2O3, ZrO2, HfO2, Nb2O5, Ta2O5, Y2O3, and LiF were mixed in a molar ratio of 4.6:1.5:0.4:0.4:0.2:0.2:0.2:1 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 300 rpm for 24 h. (2) The mixture I was annealed in an argon flow at 850°C for 10 h and cooled to room temperature; then annealed at 1100°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 86%) at 750°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 4 °C / min.

[0080] Example 5 A multi-component co-doped garnet solid electrolyte with the stoichiometric formula Li 6.7 La 3.0 Zr 0.4 Hf 0.4 Y 0.4 Ta 0.4 Nb 0.4 O 11 N 0.1 The specific preparation process is as follows: (1) LiOH, La2O3, ZrO2, HfO2, Nb2O5, Ta2O5, Y2O3, and Li3N were mixed in a molar ratio of 6.4:1.5:0.4:0.4:0.2:0.2:0.2:0.1 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 400 rpm for 30 h. (2) The mixture I was annealed in an argon flow at 850°C for 10 h and cooled to room temperature; then annealed at 1100°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 82%) at 750°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 4 °C / min.

[0081] Comparative Example 1 A garnet solid electrolyte with the stoichiometric formula Li7La3Zr2O 12 The specific preparation process is as follows: (1) Mixing LiOH, La2O3 and ZrO2 in a molar ratio of 7:1.5:2 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 300 rpm for 48 h. (2) The mixture I was annealed in an argon flow at 850°C for 10 h and cooled to room temperature; then annealed at 1100°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 99.9%) at 700°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 5 °C / min.

[0082] Comparative Example 2 A garnet solid electrolyte with the stoichiometric formula Li 7.4 La3Zr 1.6 Y 0.4 O 12 The specific preparation process is as follows: (1) Mixing LiOH, La2O3, ZrO2 and Y2O3 in a molar ratio of 7.4:1.5:1.6:0.2 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 500 rpm for 48 h. (2) The mixture I was annealed in an argon flow at 850°C for 10 h and cooled to room temperature; then annealed at 1100°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 99.9%) at 700°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 5 °C / min.

[0083] Comparative Example 3 A garnet solid electrolyte with the stoichiometric formula Li 6.6 La3Zr 1.6 Ta0.4 O 12 The specific preparation process is as follows: (1) Mixing Li2CO3, La2O3, ZrO2 and Ta2O5 in a molar ratio of 3.3:1.5:1.6:0.2 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 500 rpm for 48 h. (2) The mixture I was annealed in an argon flow at 850°C for 10 h and cooled to room temperature; then annealed at 1100°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 99.9%) at 700°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 5 °C / min.

[0084] Comparative Example 4 A garnet solid electrolyte with the stoichiometric formula Li 6.2 La3Zr 1.2 Ta 0.4 Nb 0.4 O 12 The specific preparation process is as follows: (1) Mixing LiOH, La2O3, ZrO2, Nb2O5 and Ta2O5 in a molar ratio of 6.2:1.5:1.2:0.2:0.2 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 500 rpm for 48 h. (2) The mixture I was annealed in an argon flow at 850°C for 10 h and cooled to room temperature; then annealed at 1100°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 99.9%) at 700°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 5 °C / min.

[0085] Comparative Example 5 A garnet solid electrolyte with the stoichiometric formula Li 7.0 La 3.0 Zr 1.0 Y 0.5 Ta 0.5 O 12 The specific preparation process is as follows: (1) LiOH, La2O3, ZrO2, Ta2O5 and Y2O3 are mixed in a molar ratio of 7.0:1.5:1.0:0.25:0.25 to obtain mixture I; the mixing process is ball milling at a speed of 400 rpm for 30 h. (2) The mixture I was annealed in an argon flow at 850°C for 10 h and cooled to room temperature; then annealed at 1100°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 99.9%) at 700°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 5°C / min.

[0086] Comparative Example 6 A multi-component co-doped garnet solid electrolyte with the stoichiometric formula Li 6.2 La 3.0 Zr 0.4 Y 0.4 Nb 0.4 Ta 0.4 Mo 0.4 O 12 The specific preparation process is as follows: (1) Li2CO3, La2O3, ZrO2, Y2O3, Nb2O5, Ta2O5, and Mo2O5 are mixed in a molar ratio of 3.1: 1.5: 0.4: 0.2: 0.2: 0.2: 0.2 to obtain material I; the mixing process is performed by ball milling at a speed of 300 rpm for 24 h. (2) The mixture I was annealed in an argon flow at 850°C for 10 h and cooled to room temperature; then annealed at 1100°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 99.9%) at 700°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 5 °C / min.

[0087] Comparative Example 7 A multi-component co-doped garnet solid electrolyte with the stoichiometric formula Li 6.4 La 3.0 Hf 0.5 Y 0.5 Ta 0.4 Nb 0.5 W 0. 1O 12 The specific preparation process is as follows: (1) Li2CO3, La2O3, HfO2, Y2O3, Nb2O5, Ta2O5, and WO3 were mixed in a molar ratio of 3.2: 1.5: 0.5: 0.25: 0.2: 0.1 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 300 rpm for 24 h. (2) The mixture I was annealed in an argon flow at 850°C for 10 h and cooled to room temperature; then annealed at 1100°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 99.9%) at 700°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 6°C / min.

[0088] Comparative Example 8 A multi-component co-doped garnet solid electrolyte with the stoichiometric formula Li 6.8 La 3.0 Zr 0.6 Hf 0.4 Y 0.4 Ta 0.3 Nb 0.3 O 12 The specific preparation process is as follows: (1) LiOH, La2O3, ZrO2, HfO2, Y2O3, Nb2O5, and Ta2O5 were mixed in a molar ratio of 6.8: 1.5: 0.6: 0.4: 0.2: 0.15: 0.15 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 300 rpm for 24 h. (2) The mixture I was annealed in an argon flow at 850°C for 10 h and cooled to room temperature; then annealed at 1100°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 99.9%) at 750°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 4 °C / min.

[0089] Comparative Example 9 A multi-component co-doped garnet solid electrolyte with the stoichiometric formula Li 6.8 La 2.8 Sr 0.2 Zr 0.4 Hf 0.4 Y 0.4 Ta 0.4 Nb 0.4 O 12The specific preparation process is as follows: (1) Li2CO3, La2O3, SrO, ZrO2, HfO2, Nb2O5, Ta2O5, and Y2O3 were mixed in a molar ratio of 3.4:1.4:0.2:0.4:0.4:0.2:0.2:0.2 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 300 rpm for 24 h. (2) The mixture I was annealed in an argon flow at 850°C for 10 h and cooled to room temperature; then annealed at 1100°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 60%) at 750°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 4 °C / min.

[0090] Comparative Example 10 A multi-component co-doped garnet solid electrolyte with the stoichiometric formula Li 6.4 Na 0.2 La 3.0 Zr 0.4 Hf 0.4 Y 0.4 Ta 0.4 Nb 0.4 O 12 The specific preparation process is as follows: (1) LiOH, NaOH, La2O3, ZrO2, HfO2, Y2O3, Nb2O5, and Ta2O5 were mixed in a molar ratio of 6.4:0.2:1.5:0.4:0.4:0.2:0.2:0.2 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 400 rpm for 30 h. (2) The mixture I was annealed in an argon flow at 950°C for 10 h and cooled to room temperature; then annealed at 1200°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 99.9%) at 1250°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 5 °C / min.

[0091] Comparative Example 11 A multi-component co-doped garnet solid electrolyte with the stoichiometric formula Li 6.1 La 3.0 Hf 0.5 Y 0.5 Nb 0.5 Ta0.1 W 0. 4O 12 The preparation method of solid electrolytes, and the specific preparation process are as follows: (1) LiOH, La2O3, WO3, HfO2, Y2O3, Nb2O5, and Ta2O5 were mixed in a molar ratio of 6.1:1.5:0.4:0.5:0.25:0.25:0.05 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 400 rpm for 30 h. (2) The mixture I was annealed in an argon flow at 950°C for 10 h and cooled to room temperature; then annealed at 1200°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow (oxygen concentration 99.9%) at 800°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 5 °C / min.

[0092] Comparative Example 12 A multi-component co-doped garnet solid electrolyte with the stoichiometric formula Li 6.0 La 3.0 Hf 0.5 Y 0.5 Nb 0.5 Ta 0.1 W 0. 4O 11.9 F 0.1 The specific preparation process is as follows: (1) Mixing LiOH, La2O3, WO3, HfO2, Y2O3, Nb2O5, Ta2O5, and LiF in a molar ratio of 5.9:1.5:0.4:0.5:0.25:0.25:0.05:0.1 yields mixture I; the mixing process is performed by ball milling at a speed of 400 rpm for 30 h. (2) The mixture I was annealed in an argon flow at 950°C for 10 hours and cooled to room temperature; then annealed at 1200°C for 8 hours and cooled to room temperature; after grinding and pressing, it was annealed in an oxygen flow at 800°C for 3 hours and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 5 °C / min.

[0093] Comparative Example 13 A multi-component co-doped garnet solid electrolyte with the stoichiometric formula Li 6.6 La 3.0 Zr 0.4 Hf 0.4 Y0.4 Ta 0.4 Nb 0.4 O 12 The specific preparation process is as follows: (1) LiOH, La2O3, ZrO2, HfO2, Y2O3, Nb2O5, and Ta2O5 were mixed in a molar ratio of 6.6:1.5:0.4:0.4:0.2:0.2:0.2 to obtain mixture I; the mixing process was carried out by ball milling at a speed of 400 rpm for 30 h. (2) The mixture I was annealed in an argon gas flow at 850°C for 10 h and cooled to room temperature; then annealed at 1100°C for 8 h and cooled to room temperature; after grinding and pressing, it was annealed in air at 700°C for 3 h and cooled to room temperature; thus, a multi-component co-doped garnet solid electrolyte was obtained. The heating and cooling rates for all three annealing steps were 5 °C / min.

[0094] Application Example 1 Preparation of cathode material: The multi-component co-doped garnet solid electrolyte obtained in Example 1 was combined with LiNi 0.9 Co 0.06 Mn 0.04 The O2 cathode material was weighed at a mass ratio of 1:99, then ball-milled at 100 rpm. The resulting mixture was then heat-treated at 500°C for 2 hours to obtain LiNi coated with the solid electrolyte obtained in the example. 0.9 Co 0.06 Mn 0.04 O2 single crystal (named cathode material 1).

[0095] Using cathode material 1 as the cathode active material, Li 5.5 PS 4.5 Cl 1.5 Sulfide electrolyte serves as the positive electrode ion conductor, multi-walled carbon nanotubes as the positive electrode electron conductor, and HNBR as the binder; aluminum foil serves as the positive electrode current collector, and Li... 5.5 PS 4.5 Cl 1.5 A sulfide electrolyte is used as the electrolyte membrane, a lithium-indium alloy is used as the negative electrode active material layer, and stainless steel is used as the negative electrode current collector. The specific steps for assembling an all-solid-state lithium-ion battery are as follows: (1) Under an argon atmosphere, 8.5g of positive electrode material 1 and 1.5g of Li were mixed. 5.5 PS 4.5 Cl 1.50.1g of multi-walled carbon nanotubes and 0.1g of HNBR were added to 40mL of p-xylene and heated and stirred at 60°C for 3h to obtain a positive electrode slurry. The positive electrode slurry was then coated onto aluminum foil, the solvent was evaporated at 140°C, and then rolled to obtain a positive electrode sheet with a diameter of 10mm.

[0096] (2) Under an argon atmosphere, weigh 0.1 g of Li 5.5 PS 4.5 Cl 1.5 Electrolyte powder is added into a PEEK (polyether ether ketone) mold and pressed at 200 MPa to obtain an electrolyte membrane layer.

[0097] (3) The above positive electrode sheet, electrolyte membrane layer, lithium metal disc and indium metal disc (thickness of 10μm and diameter of 8mm) are stacked together, and then stainless steel is attached to the negative electrode side. Then, it is pressed for 3 minutes under a pressure of 150MPa (the lithium sheet and indium sheet will diffuse into each other under pressure to form a lithium-indium alloy) to obtain an all-solid-state lithium-ion battery.

[0098] Application Example 2 1.5 g of PEO was dissolved in 20 mL of acetonitrile solution, and then 0.62 g of LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) was added to the acetonitrile solution. The mixture was wet-mixed at 60°C and 500 rpm for 6 hours. Subsequently, 8.48 g of the solid electrolyte prepared in Example 1 was added to the solution and stirred. The wet-mixed slurry was coated onto a polytetrafluoroethylene plate, and the solvent was evaporated at 100°C to obtain a solid electrolyte membrane.

[0099] The present invention provides, by way of example, such as Figure 9 The photograph of the composite solid electrolyte membrane prepared in Application Example 1 shows that the solid electrolyte membrane is self-supporting, does not require substrate support, and has good flexibility, allowing it to detach from the substrate and be bent at will.

[0100] Application Comparative Example 1 LiNi using uncoated multi-component co-doped garnet solid electrolyte 0.9 Co 0.06 Mn 0.04 O2 single-crystal ternary cathode material is used as the cathode active material, Li 5.5 PS 4.5 Cl 1.5 Sulfide electrolyte serves as the positive electrode ion conductor, multi-walled carbon nanotubes as the positive electrode electron conductor, and HNBR as the binder; aluminum foil serves as the positive electrode current collector, and Li... 5.5 PS 4.5 Cl 1.5A sulfide electrolyte is used as the electrolyte membrane, a lithium-indium alloy is used as the negative electrode active material layer, and stainless steel is used as the negative electrode current collector. The specific steps for assembling an all-solid-state lithium-ion battery are as follows: (1) Under an argon atmosphere, 8.5 g of uncoated LiNi was placed... 0.9 Co 0.06 Mn 0.04 O2 and 1.5g of Li 5.5 PS 4.5 Cl 1.5 0.1g of multi-walled carbon nanotubes and 0.1g of HNBR were added to 40mL of p-xylene and heated and stirred at 60°C for 3h to obtain a positive electrode slurry. The positive electrode slurry was then coated onto aluminum foil, the solvent was evaporated at 140°C, and then rolled to obtain a positive electrode sheet with a diameter of 10mm.

[0101] (2) Under an argon atmosphere, weigh 0.1 g of Li 5.5 PS 4.5 Cl 1.5 Electrolyte powder is added into a PEEK mold and pressed at 200 MPa to obtain an electrolyte membrane layer.

[0102] (3) The above positive electrode sheet, electrolyte membrane layer, lithium metal disc and indium metal disc (thickness of 10μm and diameter of 8mm) are stacked together, and then stainless steel is attached to the negative electrode side. Then, it is pressed for 3 minutes under a pressure of 150MPa to obtain an all-solid-state lithium-ion battery.

[0103] Test Example 1 Impedance and activation energy tests were performed on the solid electrolytes prepared in the above embodiments and comparative examples. The room temperature ionic conductivity results calculated from the activation energy and impedance test results of the solid electrolytes are shown in Table 1. The test method for the impedance of solid electrolytes is as follows: Ion conductivity was tested according to the following standard methods: (1) The solid electrolytes obtained in the above examples and comparative examples are ground into powder, and then 0.2 g of electrolyte powder is weighed and pressed at 150 MPa to obtain ceramic sheets; then sintered at 1100°C for 8 h to obtain dense garnet ceramic electrolyte sheets.

[0104] (2) Spray 100 nm thick gold on both sides of the garnet ceramic electrolyte sheet, then attach stainless steel as a current collector, and use an electrochemical workstation to test the impedance of the electrolyte to obtain the impedance of the garnet ceramic electrolyte sheet.

[0105] Methods for calculating room temperature ionic conductivity: According to σ = L / RSWhere L is the thickness of the electrolyte sheet (in mm), R is the impedance of the electrolyte (in Ohms), and S is the contact area (in cm²). 2 The room temperature ionic conductivity of the electrolyte sheet was calculated.

[0106] Activation energy test method: The dense garnet ceramic electrolyte sheet obtained by sintering was sputter-coated with gold on both sides, and stainless steel cylindrical rods were attached to the top and bottom surfaces of the ceramic sheet as current collectors. AC impedance was measured using an impedance analyzer (ZAHNER, Zennium Pro) in the frequency range of 8MHz to 1Hz with an amplitude of 10mV. Data was collected every 10°C within the temperature range of 10–60°C, including impedance data at 25°C. According to the Arrhenius equation: σ(T)=Aexp(-E a / k B T) The activation energy E of the sample can be calculated. a Where T is the absolute temperature, A is the exponential factor, and k is the absolute temperature. B It is the Boltzmann constant.

[0107] Air stability test method: The sintered dense garnet ceramic electrolyte sheets were exposed to air for 0 hours, two weeks, and two months, respectively. The ionic conductivity of the resulting garnet ceramic electrolyte sheets was tested according to the following standard methods: (1) Spray 100 nm thick gold on both sides of the garnet ceramic electrolyte sheet, then attach stainless steel as a current collector, and use an electrochemical workstation to test the impedance of the electrolyte to obtain the impedance of the garnet ceramic electrolyte sheet.

[0108] Methods for calculating room temperature ionic conductivity: According to σ = L / RS Where L is the thickness of the electrolyte sheet (in mm), R is the impedance of the electrolyte (in Ohms), and S is the contact area (in cm²). 2 The room temperature ionic conductivity of the electrolyte sheet was calculated.

[0109] Table 1

[0110] As can be seen from the results in Table 1, the solid electrolyte prepared in the embodiments of the present invention has significantly higher room temperature ionic conductivity and lower activation energy.

[0111] The present invention provides, by way of example, such as Figure 1The XRD patterns of the solid electrolytes prepared in Examples 1-2 and Comparative Examples 6-8 are shown below. Figure 1 As can be seen from the above, the solid electrolyte prepared by this invention is a pure phase with a cubic crystalline structure and does not contain a tetragonal phase.

[0112] The present invention provides, by way of example, such as Figure 5 The impedance spectra of the solid electrolytes prepared in Examples 1-2 and Comparative Examples 6-7 are shown. Based on the impedance data, the calculated ionic conductivity is 4.6, 4.1, 3.5, and 2.6 mS / cm, respectively.

[0113] The present invention provides, by way of example, such as Figure 2 The XRD patterns of the solid electrolytes prepared in Examples 4-5 are shown below. Figure 3 As can be seen from the above, the solid electrolyte prepared by this invention is a pure phase with a cubic crystal structure and does not contain a tetragonal phase.

[0114] The present invention provides, by way of example, such as Figure 6 The impedance spectra of the solid electrolytes prepared in Examples 4-5 are shown. Based on the impedance data, the calculated ionic conductivity is 4.5 mS / cm and 4.3 mS / cm, respectively.

[0115] The present invention provides, by way of example, such as Figure 3 The XRD patterns of the solid electrolytes prepared in Comparative Examples 1-4 are shown below. Figure 3 As can be seen from this, the obtained electrolyte is a pure phase.

[0116] The present invention provides, by way of example, such as Figure 4 The XRD patterns of the solid electrolytes prepared in Comparative Examples 11-12 are shown below. Figure 4 As can be seen from the data, the solid electrolytes prepared in Comparative Examples 11-12 have a cubic crystalline phase, but contain a small amount of impurity phases. The main reason for these impurities is that W, as a high-valence dopant ion, is incompatible with the other dopant ions, illustrating the limitations of W as a dopant ion.

[0117] The present invention provides, by way of example, such as Figure 7 The impedance spectra of the solid electrolytes prepared in Comparative Examples 11-12 are shown. Based on the impedance data, the calculated ionic conductivity is 0.7 mS / cm and 0.6 mS / cm, respectively.

[0118] The solid electrolyte prepared by heat treatment in air according to Comparative Example 13 of the present invention has an ionic conductivity of 0.8 mS / cm, which is significantly lower than the conductivity obtained by heat treatment in a high oxygen atmosphere according to the present invention.

[0119] The present invention provides, by way of example, such as Figure 17The SEM image of the solid electrolyte prepared in Example 1 is shown. Figure 17 As can be seen from the data, the solid electrolyte has a particulate morphology with a size of approximately 1~20 μm.

[0120] Test Example 2 Table 2

[0121] As shown in Table 2, compared with Comparative Examples 7, 11, and 12, the solid electrolytes prepared in the embodiments of the present invention exhibit significantly improved stability in air, indicating that the solid electrolytes provided by the present invention achieve both high ionic conductivity and excellent air stability. Specifically, the products obtained in Examples 1-5 retained over 90% of their room temperature ionic conductivity after two months of exposure to air; particularly in Examples 2, 4, and 5, the introduction of halogen elements (such as N and F) for doping resulted in ionic conductivity retention rates exceeding 97%, further demonstrating the significant effect of halogen doping in improving the air stability of solid electrolytes. Based on the data in Table 2, we can obtain the following... Figure 9 All test cases are related to ionic conductivity data after being stored in air for 0 hours, 2 weeks, and 2 months.

[0122] The present invention provides, by way of example, such as Figure 9 The impedance spectra of Example 1, after being placed in air for 0 hours, two weeks, and two months, show that the calculated ionic conductivity based on the impedance data is 4.64 mS / cm, 4.59 mS / cm, and 4.36 mS / cm, respectively.

[0123] The present invention provides, by way of example, such as Figure 10 The impedance spectra of Example 2, after being placed in air for 0 hours, two weeks, and two months, show that the calculated ionic conductivity based on the impedance data is 4.14 mS / cm, 4.104 mS / cm, and 4.02 mS / cm, respectively.

[0124] The present invention provides, by way of example, such as Figure 11 The impedance spectra of Example 3, after being placed in air for 0 hours, two weeks, and two months, show that the calculated ionic conductivity based on the impedance data is 4.23 mS / cm, 4.18 mS / cm, and 3.98 mS / cm, respectively.

[0125] The present invention provides, by way of example, such as Figure 12 The impedance spectra of Example 4, after being placed in air for 0 hours, two weeks, and two months, show that the calculated ionic conductivity based on the impedance data is 4.5 mS / cm, 4.46 mS / cm, and 4.39 mS / cm, respectively.

[0126] The present invention provides, by way of example, such as Figure 13The impedance spectra of Example 5, after being placed in air for 0 hours, two weeks, and two months, show that the calculated ionic conductivity based on the impedance data is 4.3 mS / cm, 4.28 mS / cm, and 4.2 mS / cm, respectively.

[0127] The present invention provides, by way of example, such as Figure 14 The impedance spectra of Comparative Example 7, after being placed in air for 0 hours, two weeks, and two months, show that the calculated ionic conductivity based on the impedance data is 2.65 mS / cm, 2.58 mS / cm, and 2.02 mS / cm, respectively.

[0128] The present invention provides, by way of example, such as Figure 15 The impedance spectra of Comparative Example 11 after being placed in air for 0 hours, two weeks, and two months are shown. Based on the impedance data, the calculated ionic conductivity is 0.72 mS / cm, 0.7 mS / cm, and 0.57 mS / cm, respectively.

[0129] The present invention provides, by way of example, such as Figure 16 The impedance spectra of Comparative Example 12, after being placed in air for 0 hours, two weeks, and two months, show that the calculated ionic conductivity based on the impedance data is 2.65 mS / cm, 2.58 mS / cm, and 2.02 mS / cm, respectively.

[0130] Test Example 3 The all-solid-state lithium-ion batteries in the aforementioned application examples and comparative examples were tested for charge-discharge performance at room temperature, with a test voltage range of 2.4-3.7V (vs. LiIn / Li, potential pair In / InLi, which refers to lithium indium alloy with excess indium).

[0131] The present invention provides, by way of example, such as Figure 19 The performance of the all-solid-state batteries assembled in Application Example 1 and Application Comparative Example 1 is shown in the figure. It can be seen from the figure that the LiNi battery coated with the solid electrolyte of Example 1... 0.9 Co 0.06 Mn 0.04 All-solid-state batteries assembled with O2 ternary cathode materials have a significantly higher capacity retention rate than those with uncoated LiNi. 0.9 Co 0.06 Mn 0.04 All-solid-state battery assembled with O2 ternary cathode material.

[0132] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A multi-component co-doped garnet solid electrolyte, characterized in that, Compounds containing the chemical formula shown in formula (1): (Li 1+ α A1 m+ t (La) 3+ 3-u D 2+ u (Zr) 4+ x Hf 4+ y Y 3+ z Ta 5+ v M r+ w (O) 2- 12-o E s- o (1) In the formula, the value of α satisfies the requirement of valence equilibrium, and α≤6.8; A1 is selected from at least one of Na, Li, and Mg; D is selected from at least one of Ca, Sr, and Ba; M is selected from one or more of Nb, Mo, and W; E is selected from at least one of F, S, and N; m takes the value 1 or 2, t takes the value 0~0.75; u takes the value 0~1; x takes the value 0.38~0.52, y takes the value 0.38~0.52, z takes the value 0.38~0.52; v takes the value 0.38~0.52, r takes any integer value from 4 to 6, w takes the value 0.01~0.52; o takes the value 0~2, s takes any integer value from 1 to 3; Furthermore, v+w+x+y+z=2, and the range between v, x, y and z does not exceed 50% of the maximum value.

2. The multi-component co-doped garnet solid electrolyte according to claim 1, characterized in that, w takes values ​​of 0.3-0.5; t takes values ​​of 0-0.2; u takes values ​​of 0-0.2; o takes values ​​of 0-1.

3. A method for preparing the multi-component co-doped garnet solid electrolyte as described in claim 1, characterized in that, Includes the following steps: (1) The precursor materials are mixed to obtain mixture I; The precursor material is selected from at least one of the oxides, fluorides, sulfides, nitrides of the metal source corresponding to formula (1), and metal compounds that can form the corresponding metal source oxide after calcination. (2) The mixture I is subjected to multi-stage heat treatment to obtain a multi-element co-doped garnet solid electrolyte.

4. The preparation method according to claim 3, characterized in that, The multi-stage heat treatment steps include: S1: Under inert atmosphere conditions, the mixture I is subjected to a first heat treatment and a first cooling treatment in sequence to obtain mixture II; the temperature of the first heat treatment is 800~1100 °C and the time is 6~24h; S2: Under inert atmosphere conditions, the mixture II is subjected to a second heat treatment and a second cooling treatment in sequence to obtain mixture III; the temperature of the second heat treatment is 900~1300 °C and the time is 3~24h; S3: Under high oxygen atmosphere conditions, the mixture III is subjected to a third heat treatment and a third cooling treatment in sequence to obtain the multi-element co-doped garnet solid electrolyte; the temperature of the third heat treatment is 500~900°C and the time is 3~24h; The final temperatures of the first and second cooling processes are each independently controlled to be between 30 and 200°C.

5. The preparation method according to claim 4, characterized in that, The temperature of the third heat treatment is lower than that of the second heat treatment.

6. The preparation method according to claim 4, characterized in that, In the high-oxygen atmosphere, the oxygen content is above 80 vol%.

7. A solid electrolyte membrane, characterized in that, The solid electrolyte membrane contains a solid electrolyte and a binder; the solid electrolyte includes the multi-component co-doped garnet solid electrolyte as described in claim 1.

8. The solid electrolyte membrane according to claim 7, characterized in that, Based on the total mass of the solid electrolyte membrane, the content of the solid electrolyte is ≥80wt%.

9. A positive electrode material, characterized in that, The cathode material contains an intermediate layer and a solid electrolyte coating at least a portion of the surface of the intermediate layer; the solid electrolyte is the multi-component co-doped garnet solid electrolyte as described in claim 1; The intermediate layer is selected from at least one of the compounds shown in formulas (2) to (6); LiCoO2 formula (2); LiNi x1 Mn y1 Co 1-x1-y1 O2 formula (3); LiNi 1-x2-y2 Co x2 Al y2 O2 formula (4); LiNi x3 Mn 1-x3 O2 type (5); Li 1+x4 Formula GO2 (6); Among them, x1, x2, x3, x4, y1, and y2 are each independently selected from any value between 0 and 1; G is selected from any one of Mn, Ni, Co, and Al.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes a positive electrode, a negative electrode, and an electrolyte; the positive electrode active material in the positive electrode and / or the electrolyte contains the multi-component co-doped garnet solid electrolyte as described in claim 1.

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