A halide oxide solid electrolyte and its preparation method and application

Abstract

The present invention discloses a halide oxide solid electrolyte and its preparation method and application. The preparation method of the halide oxide solid electrolyte comprises the following steps: in an inert atmosphere without water and oxygen, precursors AX and MX are mixed in a molar ratio of a:b:c. m and N x O y After mixing, the precursor mixture is pressed into tablets, and then the pressed precursor mixture is annealed to cause a solid phase reaction to obtain A a M b X a+mb‑2cy O cy Oxyhalide solid electrolyte; among them, N x O y is one or more of Sb2O3, TiO2, and SnO2. The values of a, b, and c are in the range of 0.1≤a≤3, 0.1≤b≤3, and 0.1≤c≤3; m is the valence of the metal element M. The preparation method provided by the present invention does not involve high-energy ball milling, is easily scalable, and has promising prospects for large-scale application.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a halide oxide solid electrolyte and a preparation method and application thereof. Background Art

[0002] All-solid-state batteries have become the most promising next-generation energy storage technology due to their high energy density and high safety. The development of solid electrolytes with high ionic conductivity, wide electrochemical stability window, and good air stability is the key to the practical application of all-solid-state batteries. Halide solid electrolytes have received great attention from academia and industry due to their high oxidation stability and the fact that they do not react with air to release toxic gases. However, the ionic conductivity of traditional Li-MX halide solid electrolyte systems is still not high enough (for example, Li3InCl6 is about 1.36×10 -3 S cm -1 ); and halide materials are generally easy to deliquesce and have inherent disadvantages of poor air stability, which restricts the large-scale application of halide solid electrolytes. Related technical literature shows that the strategy of mixing oxygen ions with halogen anions can significantly improve the ionic conductivity of the material, such as Li 2a (M 1-x N x )O a X 4-4x+bx The ionic conductivity of the electrolyte can reach up to 10.5×10 -3 S / cm.

[0003] However, the oxyhalide solid electrolytes disclosed in the related technical literature usually adopt high energy ball milling of lithium oxide (Li2O, LiOH or Li2O2) and metal halide MX n (e.g. TaCl5, ZrCl4, AlCl3, MgCl2) synthesis route, which has some bottleneck problems:

[0004] 1. It involves high-energy ball milling and is difficult to scale up.

[0005] 2. The lithium-oxygen ratio (Li / O) is limited by lithium oxide, and there is little room for regulation.

[0006] To address this shortcoming, the present invention provides a universal method for synthesizing an oxyhalide solid electrolyte, a solid electrolyte synthesized according to the method, and applications thereof. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a new method for synthesizing oxyhalides. The present invention provides an oxyhalide solid electrolyte and its preparation method and application to solve the above problems. The product NX 2y The low boiling point characteristic of the product NX 2yDuring the annealing process, the ions escape, inducing and driving the chemical reaction equilibrium to the right, resulting in oxyhalide solid electrolytes. A universal synthesis method for oxyhalide solid electrolytes was proposed. Using this universal method, a variety of oxyhalide solid electrolytes were synthesized with excellent electrochemical properties, which can be applied in all-solid-state batteries.

[0008] The present invention is achieved through the following technical solutions:

[0009] A method for preparing an oxyhalide solid electrolyte comprises the following steps:

[0010] In an inert atmosphere without water or oxygen, the precursors AX and MX were mixed at a molar ratio of a:b:c. m and N x O y After mixing, the precursor mixture is pressed into tablets, and then the pressed precursor mixture is annealed to cause a solid phase reaction to obtain A a M b X a+mb-2cy O cy Oxyhalide solid electrolytes;

[0011] Wherein, A is one of Li, Na, K, Ag, and Cu, M is one or more of Ta, Zr, Hf, Al, Nb, Ga, In, Sc, Y, Ho, Dy, Yb, Zn, and Mg, and X is one or more of F, Cl, Br, and I; N x O y One or more of Sb2O3, TiO2, and SnO2;

[0012] The value ranges of a, b, and c are: 0.1≤a≤3, 0.1≤b≤3, 0.1≤c≤3; m is the valence of the metal element M.

[0013] Utilize NX 2y The low boiling point characteristic is achieved through NX 2y During the annealing process, it escapes, inducing and pushing the chemical reaction equilibrium to the right, thus obtaining a halide oxide solid electrolyte. Taking Sb2O3 as an example, the principle of the halide oxide synthesis method provided by the present invention is:

[0014] aAX+bMX m +cSb2O3 △ A a M b X a+mb-6c O 3c +2cSbX3↑

[0015] Taking advantage of the low boiling point of the product SbX3 (the boiling points of SbF3, SbCl3, SbBr3, and SbI3 are 376°C, 223°C, 280°C, and 401°C, respectively), SbX3 escapes during the annealing process, inducing and pushing the chemical reaction equilibrium to the right, thereby obtaining a halide oxide solid electrolyte.

[0016] In the preparation method of the present invention, the steps including weighing, mixing and annealing are all carried out under an inert atmosphere free of water and oxygen; the inert atmosphere includes N2 gas or Ar gas, preferably, Ar gas is used.

[0017] The mixing step of the present invention can be performed by hand grinding with a mortar, or by using a mixer or a ball mill, as long as the mixing is uniform.

[0018] Further optionally, the value range of a, b, and c is: 0.1≤a≤3, 0.1≤b≤3, 0.1≤c≤3.

[0019] Further optionally, during the annealing treatment, the annealing temperature is set to 100° C.-400° C.; more preferably, the annealing time is set to 1 hour-10 hours.

[0020] Further optionally, the annealing treatment temperature rising rate is 1°C / min-10°C / min.

[0021] Further optionally, during the annealing treatment, when the annealing temperature is lower than 150° C., a device including an electric heating table is selected for addition, and when the temperature is higher than 150° C., a device including a muffle furnace is selected for addition.

[0022] The annealing step can be performed using a heating table or a muffle furnace, depending on the desired annealing temperature. The annealing temperature ranges from 100°C to 400°C. When the annealing temperature is below 150°C, a heating table is preferred, while when the temperature is above 150°C, a muffle furnace is preferred.

[0023] A halide oxide solid electrolyte, the halide oxide has the general formula A a M b X a+mb-2cy O cy ;

[0024] Wherein, A is one of Li, Na, K, Ag, and Cu, M is one or more of Ta, Zr, Hf, Al, Nb, Ga, In, Sc, Y, Ho, Dy, Yb, Zn, and Mg, and X is one or more of F, Cl, Br, and I;

[0025] The value ranges of a, b, and c are: 0.1≤a≤3, 0.1≤b≤3, 0.1≤c≤3; m is the valence of the metal element M.

[0026] Further optionally, it is prepared by the above preparation method.

[0027] Further optionally, the oxyhalide provided by the present invention has a crystalline phase-glass phase composite structure, wherein the crystalline phase is measured by X-ray powder diffraction using Cu target Kα line:

[0028] There are diffraction peaks at 2θ = 30.1° ± 0.2° and 2θ = 34.9° ± 0.2°;

[0029] and / or having diffraction peaks at 2θ=31.8°±0.2° and 2θ=45.6°±0.2°;

[0030] and / or having diffraction peaks at 2θ=24.5°±0.2° and 2θ=28.4°±0.2°;

[0031] and / or having a diffraction peak at 2θ=31.3°±0.2°;

[0032] and / or having a diffraction peak at 2θ=26.6°±0.2°;

[0033] And / or, it has a diffraction peak at the position of 2θ=27°±0.2°.

[0034] In this oxyhalide solid electrolyte, Al ions transport within the glass phase and at the glass / crystalline phase interface. The disordered long-range structure of the glass phase provides ample free volume, providing a transport channel for Al ion diffusion. Furthermore, ion transport within the glass phase is unimpeded by grain boundaries. Furthermore, due to the strong affinity of oxygen in the glass phase for Al ions, an Al ion-rich interfacial layer forms at the glass / crystalline phase interface, increasing the local concentration of Al ions and facilitating their transport.

[0035] The invention discloses an application of a halide oxide solid electrolyte in the field of batteries.

[0036] Further optionally, the application in solid-state A-ion batteries includes lithium-ion batteries, sodium-ion batteries, potassium-ion batteries, silver-ion batteries, and copper-ion batteries.

[0037] A solid-state battery comprises an oxyhalide solid electrolyte material prepared by the above-mentioned method for preparing an oxyhalide solid electrolyte, or an above-mentioned oxyhalide solid electrolyte material.

[0038] Solid-state batteries include all-solid-state batteries, semi-solid-state batteries or quasi-solid-state batteries.

[0039] Further optionally, it is an all-solid-state battery, including a positive electrode sheet, a negative electrode sheet, and a solid electrolyte sheet located between the positive electrode sheet and the negative electrode sheet; the solid electrolyte sheet is made of a solid electrolyte material.

[0040] The solid electrolyte sheet is obtained by cold pressing a solid electrolyte material, wherein the solid electrolyte material is one of the above-mentioned oxyhalide solid electrolytes or a solid electrolyte prepared by the above-mentioned preparation method of the oxyhalide solid electrolyte.

[0041] The positive electrode sheet is obtained by cold pressing or coating the positive electrode active material and positive electrode filler. The positive electrode active material includes but is not limited to lithium cobalt oxide, lithium iron phosphate, lithium-rich lithium manganese oxide, lithiated layered oxides, lithiated layered sulfides, or combinations thereof. The positive electrode filler is an ion conductor, a conductive agent, an adhesive, or a combination thereof; the ion conductor and the solid electrolyte between the positive and negative electrodes of the battery are made of the same material; the conductive agent may include graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or a combination thereof; the adhesive may include, for example, styrene-butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, or a combination thereof. Cold pressing or coating methods are common methods for preparing positive electrode sheets in this field.

[0042] The negative electrode sheet is obtained by cold pressing or coating the negative electrode active material and the negative electrode filler. The negative electrode active material refers to a material that can store and release Li ions, including but not limited to metal materials, graphite, and silicon; the metal material can be a single metal or an alloy; when a metal material is used as the negative electrode active material, the negative electrode filler can be omitted. The negative electrode filler is an ion conductor, a conductive agent, an adhesive, or a combination thereof; the ion conductor and the solid electrolyte between the positive and negative electrodes of the battery are of the same material; the conductive agent may include graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or a combination thereof; the adhesive may include, for example, styrene-butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, or a combination thereof. Cold pressing or coating methods are common methods for preparing negative electrode sheets in this field.

[0043] All-solid-state batteries can be assembled according to conventional methods in the art.

[0044] The present invention has the following advantages and beneficial effects:

[0045] The oxyhalide synthesis technology route provided by the present invention is suitable for introducing oxygen into various known and yet-to-be-developed halide solid electrolytes. It has wide applicability, and the lithium-oxygen ratio (Li / O) can be freely controlled, which greatly expands the oxyhalide system and provides support for the development of low-cost oxyhalide solid electrolytes.

[0046] The synthesis route of the road oxide electrolyte provided by the present invention does not involve the high-energy ball milling step, is easy to scale up the synthesis, and has a prospect for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0048] Figure 1 Li2Al prepared in Example 1 4.5 Cl 9.5 X-ray diffraction (XRD) spectrum of O3 solid electrolyte.

[0049] Figure 2 Li2Al prepared in Example 1 4.5 Cl 9.5 Ionic conductivity impedance spectroscopy of O3 solid electrolyte.

[0050] Figure 3 This is the ionic conductivity impedance spectrum of the Na2Al4O3Cl8 solid electrolyte prepared in Example 2.

[0051] Figure 4 The Li2Al prepared in Example 1 4.5 Cl 9.5 O3 solid electrolyte in InLi / / Li6PS5Cl / Li2Al 4.5 Cl 6.5 Voltage curve of the first charge and discharge cycle in O3 / / NCM88 all-solid-state battery.

[0052] Figure 5 The Na2Al4Cl8O3 solid electrolyte prepared in Example 3 is 0.83 [(Mn 0.75 Ni 0.25 ) 0.9 Li 0.1 ]O2 / / Na2Al4Cl8O3 / Na 2.9 PS 3.9 C l0.1 / / The first charge and discharge cycle voltage curve in NaSn all-solid-state battery. DETAILED DESCRIPTION

[0053] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0054] Example 1

[0055] This embodiment provides a halide oxide solid electrolyte Li2Al 4.5 Cl 9.5 O3, the specific preparation method is as follows:

[0056] LiCl, AlCl3, and Sb2O3 precursor powders were weighed in a molar ratio of 2:4.5:1 in an Ar atmosphere glove box and placed in an agate mortar. The powders were hand-ground using an agate pestle for 10 min, and the ground precursor powders were pressed into discs using a cylindrical pressing mold. Subsequently, the pressed precursor mixture was transferred to a crucible and annealed in a muffle furnace at 250°C for 5 h at a heating rate of 5°C / min, followed by natural cooling.

[0057] Example 2

[0058] This embodiment provides a halide oxide solid electrolyte Li2Al3Cl5O3, and the specific preparation method is as follows:

[0059] In an Ar atmosphere glove box, LiCl, AlCl3, and Sb2O3 precursor powders were weighed in a molar ratio of 2:3:1 and placed in an agate mortar; the ground precursor powders were hand-ground using an agate pestle for 10 minutes, and the ground precursor powders were pressed into discs using a cylindrical pressing mold; then, the pressed precursor mixture was transferred to a crucible and annealed in a muffle furnace at 250°C for 5 hours at a heating rate of 5°C / min, and then cooled naturally.

[0060] Example 3

[0061] This embodiment provides a halide oxide solid electrolyte Na2Al4Cl8O3, and the specific preparation method is as follows:

[0062] In an Ar atmosphere glove box, NaCl, AlCl3, and Sb2O3 precursor powders were weighed in a molar ratio of 2:4:1 and placed in an agate mortar; the ground precursor powders were hand-ground using an agate pestle for 10 minutes, and the ground precursor powders were pressed into discs using a cylindrical pressing mold; then, the pressed precursor mixture was transferred to a crucible and annealed in a muffle furnace at 250°C for 5 hours at a heating rate of 5°C / min, and then cooled naturally.

[0063] Example 4

[0064] This embodiment provides a halide oxide solid electrolyte K2Al4Cl8O3, and the specific preparation method is as follows:

[0065] In an Ar atmosphere glove box, KCl, AlCl3, and Sb2O3 precursor powders were weighed in a molar ratio of 2:4:1 and placed in an agate mortar; the ground precursor powders were hand-ground using an agate pestle for 10 minutes, and the ground precursor powders were pressed into discs using a cylindrical pressing mold; then, the pressed precursor mixture was transferred to a crucible and annealed in a muffle furnace at 250°C for 5 hours at a heating rate of 5°C / min, and then cooled naturally.

[0066] Example 5

[0067] This embodiment provides a halide oxide solid electrolyte Li2ZrCl4O, and the specific preparation method is as follows:

[0068] LiCl, ZrCl4, and Sb2O3 precursor powders were weighed in a molar ratio of 2:1:1 / 3 in an Ar atmosphere glove box and placed in an agate mortar. The powders were hand-ground using an agate pestle for 10 min, and the ground precursor powders were pressed into discs using a cylindrical pressing mold. Subsequently, the pressed precursor mixture was transferred to a crucible and annealed in a muffle furnace at 250°C for 5 h at a heating rate of 5°C / min, followed by natural cooling.

[0069] Example 6

[0070] This embodiment provides a halide oxide solid electrolyte Li2HfCl4O, and the specific preparation method is as follows:

[0071] LiCl, HfCl4, and Sb2O3 precursor powders were weighed in a molar ratio of 2:1:1 / 3 in an Ar atmosphere glove box and placed in an agate mortar. The powders were hand-ground using an agate pestle for 10 min, and the ground precursor powders were pressed into discs using a cylindrical pressing mold. Subsequently, the pressed precursor mixture was transferred to a crucible and annealed in a muffle furnace at 250°C for 5 h at a heating rate of 5°C / min, followed by natural cooling.

[0072] Example 8

[0073] This embodiment provides a halide oxide solid electrolyte Li2NbCl5O. The specific preparation method is as follows:

[0074] LiCl, NbCl5, and Sb2O3 precursor powders were weighed in a molar ratio of 2:1:1 / 3 in an Ar atmosphere glove box and placed in an agate mortar. The powders were hand-ground using an agate pestle for 10 min, and the ground precursor powders were pressed into discs using a cylindrical pressing mold. Subsequently, the pressed precursor mixture was transferred to a crucible and annealed in a muffle furnace at 250°C for 5 h at a heating rate of 5°C / min, followed by natural cooling.

[0075] Example 9

[0076] This embodiment provides a halide oxide solid electrolyte Li2AlCl3O, and the specific preparation method is as follows:

[0077] LiCl, AlCl3, and TiO2 precursor powders were weighed in a molar ratio of 2:1:1 / 2 in an Ar atmosphere glove box and placed in an agate mortar. The powders were hand-ground using an agate pestle for 10 min, and the ground precursor powders were pressed into discs using a cylindrical pressing mold. Subsequently, the pressed precursor mixture was transferred to a crucible and annealed in a muffle furnace at 250°C for 5 h at a heating rate of 5°C / min, followed by natural cooling.

[0078] Example 10

[0079] This embodiment provides a halide oxide solid electrolyte Li2AlCl3O, and the specific preparation method is as follows:

[0080] LiCl, AlCl3, and SnO2 precursor powders were weighed in a molar ratio of 2:1:1 / 2 in an Ar atmosphere glove box and placed in an agate mortar. The powders were hand-ground using an agate pestle for 10 min, and the ground precursor powders were pressed into discs using a cylindrical pressing mold. Subsequently, the pressed precursor mixture was transferred to a crucible and annealed in a muffle furnace at 250°C for 5 h at a heating rate of 5°C / min, followed by natural cooling.

[0081] Performance Testing

[0082] like Figure 1 As shown, the sample Li2Al obtained in Example 1 4.5 Cl 9.5 The ionic conductivity of O3 is as high as 1.24mS / cm.

[0083] like Figure 2 As shown, the sample Li2Al obtained in Example 1 4.5 Cl 9.5 The XRD of O3 shows the crystal structure of LiCl and LiAlCl4. The characteristic diffraction peaks of LiCl appear at 2θ=30° and 2θ=34.8°; and the characteristic diffraction peak of LiAlCl4 appears at 2θ=31.9°. It can also be seen from the spectrum that the synthesized Li2Al 4.5 Cl 9.5 The O3 electrolyte shows a higher amorphous content.

[0084] like Figure 3 As shown, the ionic conductivity of the sample Na2Al4Cl8O3 obtained in Example 3 is 0.5 mS / cm.

[0085] like Figure 4 As shown, the Li2Al obtained in Example 1 is used 4.5 Cl 9.5 The full battery assembled with O3 electrolyte is LiNi 0.88 Co 0.09Mn 0.03 O2 cathode, Li2Al 4.5 Cl 6.5 The full battery assembled with O3 and Li6PS5Cl as electrolyte and LiIn alloy as negative electrode was tested at 0.1c rate. The full battery with NCM88 as positive electrode showed high specific capacity, which is due to the Li2Al synthesized by the synthesis method proposed in this invention. 4.5 Cl 9.5 O3 electrolyte exhibits a crystalline-glass phase composite structure. Figure 2 It can be seen from the XRD spectrum of Li2Al 4.5 Cl 9.5 O3 has a high content of glass phase, in which the disordered long-range structure has a large amount of free volume, which is Li + Diffusion provides a transmission channel; and in the glass phase, ion transport is not hindered by grain boundaries. + The affinity is strong, forming a Li-rich + The interface layer increases the Li + The local concentration of Li + transmission, thus Li2Al 4.5 Cl 9.5 O3 exhibits high ionic conductivity, which ensures ion transport within the battery and exhibits high specific capacity.

[0086] And its excellent chemical stability with high nickel positive electrode.

[0087] like Figure 5 As shown, the full battery assembled with the Na2Al4Cl8O3 electrolyte obtained in Example 3 is Na 0.83 [(Mn 0.75 Ni 0.25 ) 0.9 Li 0.1 ]O2 as the positive electrode, Na2Al4Cl8O3 and Na 2.9 PS 3.9 Cl 0.1 As electrolyte, Na 15 The full battery assembled with Sn4 as the negative electrode was charged and discharged at a rate of 0.1c. 0.83 [(Mn 0.75 Ni 0.25 ) 0.9 Li 0.1 ]O2 as the positive electrode of the full battery shows a high specific capacity, the synthesis method of the present invention proposed by the Na2Al4Cl8O3 electrolyte shows a crystalline phase - glass phase composite structure, the high glass phase content contributes to the Na +transport, showing the high ionic conductivity of Na2Al4Cl8O3 electrolyte and its excellent chemical stability with the oxide positive electrode.

[0088] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing an oxyhalide solid electrolyte, characterized in that: The following steps are involved: In an inert atmosphere without water or oxygen, the precursors AX and MX were mixed at a molar ratio of a:b:c. m and N x O y After mixing, the precursor mixture is pressed into tablets, and then the pressed precursor mixture is annealed to cause a solid phase reaction to obtain A a M b X a+mb-2cy O cy Oxyhalide solid electrolytes; Wherein, A is one of Li, Na, K, Ag, and Cu, M is one or more of Zr, Hf, Al, Nb, Ga, In, Sc, Y, Ho, Dy, Yb, Zn, and Mg, and X is one or more of F, Cl, Br, and I; N x O y One or more of TiO2 and SnO2; The value ranges of a, b, and c are: 0.1≤a≤3, 0.1≤b≤3, 0.1≤c≤3; m is the valence of the metal element M; The annealing temperature is 250°C-400°C, and the annealing temperature is NX 2y It escapes during the annealing process, inducing and pushing the chemical reaction equilibrium to the right, resulting in a halide oxide solid electrolyte.

2. The method for preparing an oxyhalide solid electrolyte according to claim 1, wherein: The heating rate of the annealing treatment is 1 ℃ / min-10 ℃ / min.

3. The method for preparing an oxyhalide solid electrolyte according to claim 1, wherein: Annealing treatment is carried out using equipment including a muffle furnace.

4. A halide oxide solid electrolyte, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 3.

5. Use of the oxyhalide solid electrolyte according to claim 4 in the field of batteries.

6. A solid-state battery, characterized in that: An oxyhalide solid electrolyte material prepared by the method for preparing an oxyhalide solid electrolyte according to any one of claims 1 to 3, or an oxyhalide solid electrolyte material according to claim 4.

7. A solid-state battery according to claim 6, characterized in that: It is an all-solid-state battery, including a positive electrode sheet, a negative electrode sheet, and a solid electrolyte sheet located between the positive electrode sheet and the negative electrode sheet; the solid electrolyte sheet is made of solid electrolyte material.

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