A core-shell solid electrolyte material, a preparation method thereof and a full-solid-state lithium metal battery

Abstract

The present application relates to a kind of core-shell solid electrolyte material and its preparation method and full solid lithium metal battery.The core-shell solid electrolyte material takes chloride solid electrolyte as inner core, and forms fluoride coating layer as shell on the surface of the chloride solid electrolyte by in-situ fluorination.The core-shell solid electrolyte material of the present application can avoid the contact of chloride electrolyte inner core with water vapor and can inhibit the side reaction of chloride electrolyte inner core with metal lithium and the growth of lithium dendrite, thereby realizing the excellent stability of chloride electrolyte to humid air and metal lithium.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of solid electrolyte, and particularly relates to a fluoride-coated core-shell chloride solid electrolyte and a preparation method thereof and a full-solid-state lithium metal battery. BACKGROUND

[0002] As a new generation of energy storage technology, the full-solid-state lithium metal battery has attracted extensive attention due to its high safety, large energy density and long-term cycle life. Compared with the traditional liquid lithium ion battery, the full-solid-state lithium metal battery uses solid electrolyte material, which not only effectively solves the safety problems such as flammability and explosion of organic electrolyte, but also significantly improves the energy density by using lithium metal negative electrode. Therefore, the full-solid-state lithium metal battery is considered as one of the core technologies to promote the development of the next generation of electric vehicles, smart grids and portable electronic devices.

[0003] In the development process of the full-solid-state lithium metal battery, the selection of solid electrolyte material is crucial. At present, chloride solid electrolyte has become a research hotspot due to its high ionic conductivity and high voltage stability. However, the existing chloride solid electrolyte still faces some technical bottlenecks in practical application, especially in terms of air stability and metal lithium compatibility. First, the chloride solid electrolyte is extremely sensitive to moisture in the air, and will undergo hydrolysis reaction when exposed to air, resulting in the generation of toxic HCl gas and a significant reduction in ionic conductivity, which seriously limits its large-scale application. In addition, the interface stability between the chloride electrolyte and the metal lithium is poor, and the interface reaction will occur spontaneously to generate ion-insulating interface byproducts, thereby reducing the cycle stability of the battery. In addition, the chloride electrolyte may also induce lithium dendrite growth due to side reactions during charge and discharge cycles, further deteriorating the battery performance and possibly causing safety hazards. Therefore, developing chloride solid electrolyte materials that are stable to metal lithium and humid air is of great significance to promote the practical application of full-solid-state lithium metal batteries.

[0004] Patent document 1 (CN117996164A) discloses a composite solid electrolyte, which includes a halide solid electrolyte and a coating layer coated on the surface of the halide solid electrolyte, the coating layer includes a first lithium salt, the first lithium salt includes at least one of lithium difluorophosphate (LiPO2F2), lithium difluorophosphate (LiDFOB), lithium difluorophosphate (LiBOB), lithium difluorophosphate (LiODFP). In the patent document 1, a layer of lithium salt is coated on the surface of the halide solid electrolyte, and a material with high oxidation stability and fast lithium conduction such as LiF, LiBO2, Li3PO4, etc. is formed in situ on the surface of the halide solid electrolyte during charging, thereby isolating the electron path.

[0005] Although the electron passage is blocked by forming a coating layer on the surface of the halide solid electrolyte in Patent Document 1, the lithium salt is required to be decomposed to form a fast lithium-conducting material during charging, which is likely to cause insufficient decomposition of the lithium salt, resulting in uneven coating. In addition, in actual industrial production, cost is a very important factor to be considered. The lithium salts used in Patent Document 1 are all high in price, resulting in a significant increase in cost in actual application. SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In view of the problems existing in the prior art, it is necessary to provide a chloride solid electrolyte which not only can avoid the contact of the chloride electrolyte with water vapor, inhibit the side reaction between the chloride electrolyte and lithium metal and the growth of lithium dendrites, but also is low in cost.

[0008] SOLUTION TO THE PROBLEM

[0009] To achieve the above-mentioned purpose, the technical solution adopted by the present application is: taking a chloride solid electrolyte as the inner core, and forming a fluorine coating on the surface thereof by in-situ fluorination to form a shell structure. Under the protection of the fluorine shell, the chloride electrolyte inner core can not only avoid the contact with water vapor, but also inhibit the side reaction between the chloride electrolyte inner core and lithium metal and the growth of lithium dendrites, thereby realizing the excellent stability of the chloride electrolyte to humid air and lithium metal.

[0010] Specifically, the present application provides a core-shell solid electrolyte material, which takes a chloride solid electrolyte as the inner core, and forms a fluorine coating on the surface of the chloride solid electrolyte by in-situ fluorination as the shell,

[0011] The chemical general formula of the chloride solid electrolyte is Li a M 6-a Cl6, wherein M is one or more elements selected from the group consisting of In 3+ , Y 3+ , Al 3+ , Fe 3+ , Lu 3+ , Tb 3+ , Ti 3+ , Sc 3+ , Er 3+ , Ho 3+ , Yb 3+ , Dy 3+ , Tm 3+ , Zr 4+ , and 1≤a≤3.

[0012] According to the core-shell solid electrolyte material described above, wherein the fluoride is one or more of LiF, NaF, KF, CaF2, MgF2, MnF2, InF3, YF3, AlF3, FeF3, LuF3, TbF3, TiF3, ScF3, ErF3, HoF3, YbF3, DyF3, TmF3, ZrF4.

[0013] According to the core-shell solid electrolyte material described above, wherein the room temperature ionic conductivity of the core-shell solid electrolyte material is ≥ 2.0 x 10 -4 S / cm; and / or

[0014] The core-shell solid electrolyte material retains ≥ 40% of its room temperature ionic conductivity when exposed to air with 20-50% relative humidity for 2-24h.

[0015] According to the core-shell solid electrolyte material described above, wherein the thickness of the fluoride coating layer is 1-10nm.

[0016] According to the core-shell solid electrolyte material described above, wherein the particle size of the chloride solid electrolyte is 1-30μm.

[0017] The present application also provides a preparation method of the core-shell solid electrolyte material described above, comprising the following steps:

[0018] mixing a fluorination agent with the chloride solid electrolyte and performing heat treatment, thereby obtaining the core-shell solid electrolyte material coated with fluoride on the surface.

[0019] According to the preparation method described above, wherein the fluorination agent is one or more of NH4F, LiHF2, LiNH4HF2, NaHF2, KHF2, MnHF2, NaNH4HF2, CaHF2, MgHF2.

[0020] According to the preparation method described above, wherein the mass ratio of the fluorination agent to the chloride solid electrolyte is 1:200-1:2, preferably 1:50-1:5.

[0021] According to the preparation method described above, wherein the heat treatment is performed under argon atmosphere; the temperature rising speed is 1-5℃ / min, the heat treatment temperature is 100-1000℃, and the heat treatment time is 1-48h.

[0022] The present application further provides an all-solid-state lithium metal battery, comprising a positive electrode, a negative electrode and an electrolyte layer, wherein at least one of the positive electrode, the electrolyte layer and the negative electrode contains the core-shell solid electrolyte material described above or obtained by the preparation method described above.

[0023] The effects of the invention

[0024] The above-described technical solution of the present invention has the following beneficial effects:

[0025] (1) The core-shell solid electrolyte material of the present invention forms a fluoride coating layer on the surface of the chloride electrolyte core by in-situ fluorination. Therefore, the interface stability between the fluoride shell and the chloride electrolyte core is good, which can improve the battery capacity and capacity retention rate.

[0026] (2) In the core-shell solid electrolyte material of the present invention, due to the presence of a fluoride shell, the contact between the chloride electrolyte core and water vapor can be avoided and the side reaction between the chloride electrolyte core and lithium metal and the growth of lithium dendrites can be suppressed, thereby achieving excellent stability of the chloride electrolyte against humid air and lithium metal; the core-shell solid electrolyte material of the present invention has a high conductivity retention rate under humid air.

[0027] (3) The present invention utilizes the strong corrosiveness of HF, the gas-phase decomposition product of a low-cost fluorinating agent, to perform in-situ fluorination on the surface of a chloride electrolyte, thereby obtaining a core-shell solid electrolyte material of a chloride solid electrolyte coated with fluoride. It has the advantages of simple operation method, low cost and easy large-scale production. Attached Figure Description

[0028] Figure 1 The X-ray diffraction patterns are those of the LiF-ZrF4-coated core-shell LiF-ZrF4@Li2ZrCl6 chloride electrolyte of Example 1 and the Li2ZrCl6 chloride electrolyte of Comparative Example 1.

[0029] Figure 2 This is a high-resolution transmission electron microscope image of the LiF-ZrF4-coated core-shell LiF-ZrF4@Li2ZrCl6 chloride electrolyte of Example 1 of the present invention.

[0030] Figure 3 Cycling diagram of a lithium symmetric battery assembled based on the LiF-ZrF4-coated core-shell LiF-ZrF4@Li2ZrCl6 chloride electrolyte of Example 1 and the Li2ZrCl6 chloride electrolyte of Comparative Example 1.

[0031] Figure 4 The charge-discharge cycle diagram shows the all-solid-state lithium metal battery assembled based on the LiF-ZrF4-coated core-shell LiF-ZrF4@Li2ZrCl6 chloride electrolyte of Example 1 and the Li2ZrCl6 chloride electrolyte of Comparative Example 1. Detailed Implementation

[0032] For a better understanding of the present application, numerous specific details are given in the following detailed description. One skilled in the art will understand, however, that the application can be practiced without certain specific details. In other instances, well-known methods, devices, equipment, and procedures have not been described in detail so as not to obscure the application.

[0033] In the present specification, units used are international standard units, and numerical values, numerical value ranges appearing in the present application should be understood to include systematic errors that are unavoidable in industrial production, unless otherwise specified.

[0034] In the present specification, the meaning indicated by "may" includes both the meaning of performing a certain process and the meaning of not performing the certain process.

[0035] In the present specification, the expressions "some embodiments / prefeπed embodiments", "other embodiments / prefeπed embodiments", "embodiments", and the like mean that the specific elements (e.g., features, structures, properties, and / or characteristics) described in relation to the embodiments are included in at least one of the embodiments described herein, and can or can not be present in other embodiments. In addition, it should be understood that the described elements can be combined in various embodiments in any suitable manner.

[0036] In the present specification, the numerical value range indicated by "numerical value A to numerical value B" means a range including the end point numerical values A, B.

[0037] In the present specification, "plurality", "a plurality of", "a plurality of" and the like mean a numerical value of 2 or more, unless otherwise specified.

[0038] In the present specification, "substantially", "generally", or "essentially" means an error of 5% or less, or 3% or less, or 1% or less, compared to a perfect standard or a theoretical standard related thereto.

[0039] In the present specification, "%" means a mass percentage, unless otherwise specified.

[0040] In the present specification, the meaning indicated by "may" includes both the meaning of performing a certain process and the meaning of not performing the certain process.

[0041] In the present specification, "optional" or "optionally" means that the event or circumstance described next can or can not occur, and the description includes the case where the event occurs and the case where the event does not occur.

[0042] In the present specification, when "room temperature", "ordinary temperature", and the like appear, the temperature can generally be 25±5°C.

[0043] First aspect

[0044] The first aspect of the present application provides a core-shell solid electrolyte material. The core-shell solid electrolyte material of the present application has a chloride solid electrolyte as an inner core, and a fluoride coating layer as an outer shell formed on the surface of the chloride solid electrolyte by in-situ fluorination.

[0045] In the present application, the chemical formula of the chloride solid electrolyte is Li a M 6-a Cl6, wherein M is one or more elements selected from the group consisting of In 3+ , Y 3+ , Al 3+ , Fe 3 + , Lu 3+ , Tb 3+ , Ti 3+ , Sc 3+ , Er 3+ , Ho 3+ , Yb 3+ , Dy 3+ , Tm 3+ , Zr 4+ , and a is 1 to 3. In some specific embodiments, M can be preferably Zr 4+ , In 3+ , or Y 3+ , and a is 2 or 3.

[0046] In some specific embodiments, the fluoride mentioned above can be one or more of LiF, NaF, KF, CaF2, MgF2, MnF2, InF3, YF3, AlF3, FeF3, LuF3, TbF3, TiF3, ScF3, ErF3, HoF3, YbF3, DyF3, TmF3, ZrF4. In some embodiments, the fluoride mentioned above can be a combination of LiF and one or more selected from the group consisting of NaF, KF, CaF2, MgF2, MnF2, InF3, YF3, AlF3, FeF3, LuF3, TbF3, TiF3, ScF3, ErF3, HoF3, YbF3, DyF3, TmF3, ZrF4.

[0047] The core-shell solid electrolyte material of the present application has a room temperature ionic conductivity of ≥ 2.0 x 10 -4 S / cm, for example, can be 2.0 x 10 -4 S / cm, 2.5 x 10 -4 S / cm, 3.0 x 10 -4 S / cm, 5.0 x 10 -4 S / cm, 8.0 x 10 -4 S / cm, 1.0 x 10-3 S / cm, 3.0×10 -3 S / cm, etc.

[0048] When the core-shell solid electrolyte material is exposed to air with a relative humidity of 20-50% for 2-24 hours, its room temperature ionic conductivity retention rate is ≥40%, for example, it can be 50%, 60%, 70%, 80%, etc.

[0049] In the core-shell solid electrolyte material of the present invention, the thickness of the fluoride coating layer can be 1-10 nm, for example, 3 nm, 5 nm, 8 nm, 10 nm, etc.

[0050] In the core-shell solid electrolyte material of the present invention, the particle size of the chloride solid electrolyte can be 1-30 μm, for example, 1 μm, 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 20 μm, 25 μm, 30 μm, etc.

[0051] Second aspect

[0052] A second aspect of the present invention provides a method for preparing the core-shell solid electrolyte material described in the first aspect above.

[0053] The preparation method of the present invention includes the following steps: mixing a fluorinating agent with a chloride solid electrolyte and subjecting it to heat treatment, and then cooling to obtain a core-shell solid electrolyte material with a surface coated with fluoride.

[0054] When the mixture of fluorinating agent and chloride solid electrolyte is heat-treated, the fluorinating agent decomposes to produce highly corrosive HF gas. This HF gas fluorinates the surface of the chloride solid electrolyte, resulting in an in-situ fluorination reaction and forming a fluoride coating layer on the surface of the chloride solid electrolyte. The core-shell structure formed through in-situ fluorination provides good interfacial stability between the fluoride shell and the chloride electrolyte core. This fluoride coating layer acts as a shell to protect the chloride solid electrolyte core, preventing contact with moisture and preventing the chloride solid electrolyte from reacting with metallic lithium.

[0055] The chloride solid electrolyte in this aspect is the same as that in the first aspect above, and will not be repeated here.

[0056] The fluorinating agent used in this invention may be one or more selected from NH4F, LiHF2, LiNH4HF2, NaHF2, KHF2, MnHF2, NaNH4HF2, CaHF2, and MgHF2. From a cost perspective, NH4F is preferred.

[0057] In the present application, the mass ratio of the fluorination agent to the chloride solid electrolyte can be 1:200 to 1:2, for example, 1:150, 1:120, 1:100, 1:80, 1:50, 1:30, 1:10, 1:8, 1:5, 1:3, etc.

[0058] In the present application, after mixing the fluorination agent with the chloride solid electrolyte, they can be ground by a mortar or the like to mix them uniformly. After mixing the fluorination agent with the chloride solid electrolyte uniformly, they are subjected to heat treatment, and after cooling, a core-shell solid electrolyte material having a core of the chloride solid electrolyte and a shell of the fluoride is obtained.

[0059] The heat treatment can be performed under an argon atmosphere. The temperature increase rate can be 1 to 5°C / min. The heat treatment temperature can be 100 to 1000°C, for example, 150°C, 200°C, 250°C, 300°C, 500°C, 700°C, 900°C, etc. The heat treatment time can be 1 to 48 h, for example, 1.5 h, 2 h, 5 h, 10 h, 15 h, 20 h, 30 h, 40 h, etc.

[0060] In the present application, the method for preparing the chloride solid electrolyte is not particularly limited, and a conventional preparation method in the art can be used, for example, a solid ball milling method can be used.

[0061] In the case where the solid ball milling method is used to prepare the chloride solid electrolyte, under argon protection, LiCl and the chloride of the element M can be mixed uniformly in a stoichiometric ratio, and then the obtained mixture is subjected to high-speed ball milling for a period of time, for example, 15 to 30 h, to obtain the chloride solid electrolyte.

[0062] Third aspect

[0063] The third aspect of the present application further provides a full solid-state lithium battery, which comprises a positive electrode, a negative electrode, and an electrolyte layer, wherein at least one of the positive electrode, the electrolyte layer, and the negative electrode contains the core-shell solid electrolyte material described above or obtained by the preparation method described above.

[0064] In the present application, other materials for the positive electrode, the negative electrode, and the electrolyte layer are not particularly limited, and materials known in the art can be used.

[0065] Examples

[0066] The embodiments of the present application will be described in detail below with reference to examples, but those skilled in the art will understand that the following examples are only for illustration of the present application and should not be regarded as limiting the scope of the present application. In the examples, the specific conditions not noted are carried out according to the conventional conditions or the conditions recommended by the manufacturers. The reagents or instruments not noted by the manufacturers are all conventional products that can be obtained by marketing.

[0067] Example 1: Preparation of LiF-ZrF4@Li2ZrCl6 chloride solid electrolyte material

[0068] 1) Under the protection of argon, LiCl and ZrCl4 raw materials were mixed uniformly according to the stoichiometric ratio, and then the obtained mixture was high-speed ball milled at 800 rpm for 20 h to obtain a Li2ZrCl6 chloride solid electrolyte.

[0069] 2) Fluorination agent NH4F and Li2ZrCl6 chloride solid electrolyte were weighed according to a mass ratio of 1:10, and were mixed uniformly with a mortar to obtain a precursor;

[0070] 3) The obtained precursor was heated from room temperature to 200°C at a heating rate of 1°C / min under an argon atmosphere, and was kept for 2 h. The highly corrosive HF gas generated by the thermal decomposition of NH4F can fluorinate the surface of Li2ZrCl6, and a core-shell LiF-ZrF4@Li2ZrCl6 coated with LiF and ZrF4 was obtained.

[0071] Figure 1 and Figure 2 respectively are the X-ray diffraction patterns and high-resolution transmission electron micrographs of the LiF-ZrF4@Li2ZrCl6 chloride electrolyte coated with LiF and ZrF4 prepared by the present application. From the characteristic peaks of Figure 1 , it can be seen that in addition to the original peaks of Li2ZrCl6, additional diffraction peaks are observed in Example 1, which can be indexed with the standard peaks of LiF (PDF #45-1460) and ZrF4 (PDF #46-1201), indicating that the coating layers of LiF and ZrF4 are successfully formed in the fluorination process. Further from the high-resolution transmission electron micrograph shown in Figure 2 , it can be seen that the thickness of the coating layer is about 5 nm.

[0072] The LiF-ZrF4@Li2ZrCl6 prepared based on Example 1 was used to assemble a stainless steel symmetric battery to test the change of ion conductivity before and after exposure to air. In an argon-filled glove box, 100 mg of LiF-ZrF4@Li2ZrCl6 electrolyte before and after exposure to air was respectively placed in a mold with a diameter of 10 mm, and was pressed into an electrolyte sheet under a pressure of 300 MPa. Subsequently, a stainless steel disc was placed on both sides to assemble a symmetric battery. The mold pressure was kept at 100 MPa, and impedance test was performed by an electrochemical workstation (the same method was used in the following examples). The ion conductivity of the core-shell LiF-ZrF4@Li2ZrCl6 chloride solid electrolyte before exposure to wet air was measured to be 2.15 x 10 -4S / cm, the ion conductivity retention rate was 68.37%. -4 S / cm, the ion conductivity retention rate was 68.37%.

[0073] Example 2: Preparation of LiF-InF3@Li3InCl6 chloride solid electrolyte material

[0074] 1) Under the protection of argon, LiCl and InCl3 raw materials were mixed uniformly according to the stoichiometric ratio, and then the obtained mixture was high-speed ball milled at 800 rpm for 20 h. The ball-milled sample was heated from room temperature to 260°C at a heating rate of 1°C / min, and was kept for 5 h. After cooling, Li3InCl6 chloride solid electrolyte was obtained.

[0075] 2) Under the protection of argon atmosphere, fluorinating agent NH4F and Li3InCl6 chloride solid electrolyte were weighed according to the mass ratio of 1:10, and were mixed uniformly with a mortar to obtain a precursor;

[0076] 3) The obtained precursor was heated from room temperature to 200°C at a heating rate of 1°C / min under argon atmosphere, and was kept for 2 h. The highly corrosive HF gas generated by the thermal decomposition of NH4F can fluorinate the surface of Li3InCl6, and a core-shell LiF-InF3@Li3InCl6 with LiF and InF3 coating was obtained.

[0077] The ion conductivity of the core-shell LiF-InF3@Li3InCl6 chloride solid electrolyte before exposure to humid air was measured to be 3.15×10 -3 S / cm, the ion conductivity retention rate was 68.37%. - 4 S / cm, the ion conductivity retention rate was 68.37%.

[0078] Example 3: Preparation of LiF-YF3@Li3YCl6 chloride solid electrolyte material

[0079] 1) Under the protection of argon, LiCl and YCl3 raw materials were mixed uniformly according to the stoichiometric ratio, and then the obtained mixture was high-speed ball milled at 800 rpm for 20 h. The ball-milled sample was heated from room temperature to 260°C at a heating rate of 1°C / min, and was kept for 5 h. After cooling, Li3YCl6 chloride solid electrolyte was obtained.

[0080] 2) Under the protection of argon atmosphere, fluorinating agent NH4F and Li3YCl6 chloride solid electrolyte were weighed according to the mass ratio of 1:10, and were mixed uniformly with a mortar to obtain a precursor;

[0081] 3) The precursor obtained was heated from room temperature to 200 °C at a heating rate of 1 °C / min under argon atmosphere, and kept for 2 h. The highly corrosive HF gas generated by the thermal decomposition of NH4F fluoridizes the surface of Li3YCl6, and LiF-YF3@Li3YCl6 with LiF and YF3 coating is obtained.

[0082] The ionic conductivity of the LiF-YF3@Li3YCl6 chloride solid electrolyte measured before exposure to humid air was 2.68 x 10 -3 S / cm, and the ionic conductivity retention rate was 65.67%. -4 S / cm, and the ionic conductivity retention rate was 65.67%.

[0083] Comparative Example 1: Preparation of Li2ZrCl6 chloride solid electrolyte material

[0084] LiCl and ZrCl4 raw materials were mixed uniformly in stoichiometric ratio under the protection of argon, and then the obtained mixture was high-speed ball-milled at 800 rpm for 20 h to obtain Li2ZrCl6 chloride solid electrolyte.

[0085] The ionic conductivity of the Li2ZrCl6 chloride solid electrolyte measured before exposure to humid air was 5.62 x 10 -4 S / cm, and the ionic conductivity retention rate was 65.67%. -6 S / cm, and the ionic conductivity retention rate was 65.67%.

[0086] Lithium metal stability test

[0087] LiF-ZrF4@Li2ZrCl6 prepared based on Example 1 and Li2ZrCl6 chloride solid electrolyte material prepared in Comparative Example 1 were assembled into lithium symmetric batteries. In an argon-filled glove box, 100 mg of LiF-ZrF4@Li2ZrCl6 and Li2ZrCl6 electrolyte were taken respectively, placed in a mold with a diameter of 10 mm, and pressed into electrolyte sheets under a pressure of 300 MPa. Then, lithium sheets with a diameter of 9 mm were placed on both sides of the electrolyte sheets to assemble lithium symmetric batteries. The mold pressure was kept at 100 MPa, and long cycle tests were carried out by a blue electric device at a current density and surface capacity of 0.1 mA / cm and 0.1 mAh / cm, respectively.

[0088] Figure 3The cycle test comparison graph of lithium symmetric batteries assembled with LiF-ZrF4@Li2ZrCl6 prepared based on Example 1 and Li2ZrCl6 chloride solid electrolyte material prepared in Comparative Example 1 was carried out at current density and surface capacity of 0.1 mA / cm and 0.1 mAh / cm, respectively. It can be found that Figure 3 (a) the lithium symmetric battery assembled in Comparative Example 1 has an increase in overpotential with the increase in cycle number, and reaches the cut-off voltage of 5 V after 156 h. In sharp contrast is that Figure 3 (b) it can be found that the lithium symmetric battery assembled in Example 1 can be stably cycled for more than 800 h. The test result shows that the fluoride-coated core-shell chloride electrolyte based on the present application has excellent stability to metal lithium.

[0089] Application of solid electrolytes in all-solid-state metal batteries

[0090] LiCoO2 cathode, metal lithium anode and LiF-ZrF4@Li2ZrCl6 prepared in Example 1 or Li2ZrCl6 chloride solid electrolyte material prepared in Comparative Example 1 were assembled into a full solid-state lithium metal battery, and galvanostatic charge-discharge test was carried out in the voltage range of 2.8-4.3 V using a blue electric device, and the charge-discharge rate was 0.2 C.

[0091] Figure 4 The cycle curve graph of a full solid-state lithium battery assembled with LiF-ZrF4@Li2ZrCl6 prepared based on Example 1 or Li2ZrCl6 chloride solid electrolyte material prepared in Comparative Example 1 at 0.2 C. It can be seen that the discharge capacity of the first cycle of the full solid-state lithium battery assembled based on Comparative Example 1 is 102.8 mAh / g, and it decreases to 22.3 mAh / g after only 6 cycles, and the capacity retention rate after 6 cycles is only 21.7%. In contrast, the initial capacity of the full solid-state lithium battery assembled based on Example 1 is 128.6 mAh / g, and the capacity after 100 cycles is 90.8 mAh / g, and the capacity retention rate after 100 cycles is 71%. The test result shows that the full solid-state battery prepared based on the fluoride-coated core-shell chloride electrolyte has more excellent cycle stability.

[0092] The above has described various embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A core-shell solid electrolyte material, characterized by, It takes chloride solid electrolyte as the core, and forms fluoride coating layer as the shell on the surface of the chloride solid electrolyte by in-situ fluorination, The chemical general formula of the chloride solid electrolyte is Li a M 6-a Cl6, wherein M is In 3+ or Zr 4+ , 1≤a≤3; The fluoride is LiF and InF3 or LiF and ZrF4. The thickness of the fluoride coating layer is 1-5 nm.

2. The core-shell solid electrolyte material of claim 1, wherein The core-shell solid electrolyte material has a room temperature ionic conductivity ≥ 2.0 × 10 -4 S / cm; and / or The core-shell solid electrolyte material retains ≥40% of room temperature ionic conductivity after being exposed to air with 20-50% relative humidity for 2-24 h.

3. The core-shell solid electrolyte material according to claim 1 or 2, characterized in that, The particle size of the chloride solid electrolyte is 1-30 μm.

4. A method for producing the core-shell solid electrolyte material according to any one of claims 1 to 3, characterized by, It comprises the following steps: The fluoride coating layer is formed on the surface of the chloride solid electrolyte by in-situ fluorination.

5. The preparation method according to claim 4, characterized in that, The fluoride is LiF and InF3 or LiF and ZrF4.

6. The production method according to claim 4 or 5, characterized by, The thickness of the fluoride coating layer is 1-5 nm.

7. The preparation method according to claim 6, characterized in that, The core-shell solid electrolyte material retains ≥40% of room temperature ionic conductivity after being exposed to air with 20-50% relative humidity for 2-24 h.

8. The production method according to claim 4 or 5, characterized by, The particle size of the chloride solid electrolyte is 1-30 μm.

9. An all-solid-state lithium metal battery, characterized by, It comprises the following steps: The fluoride coating layer is formed on the surface of the chloride solid electrolyte by in-situ fluorination. The fluoride is LiF and InF3 or LiF and ZrF4. The thickness of the fluoride coating layer is 1-5 nm. The core-shell solid electrolyte material retains ≥40% of room temperature ionic conductivity after being exposed to air with 20-50% relative humidity for 2-24 h. The particle size of the chloride solid electrolyte is 1-30 μm. It comprises the following steps: The fluoride coating layer is formed on the surface of the chloride solid electrolyte by in-situ fluorination. The fluoride is LiF and InF3 or LiF and ZrF4. The thickness of the fluoride coating layer is 1-5 nm. The core-shell solid electrolyte material retains ≥40% of room temperature ionic conductivity after being exposed to air with 20-50% relative humidity for 2-24 h. The particle size of the chloride solid electrolyte is 1-30 μm. It comprises the following steps: The fluoride coating layer is formed on the surface of the chloride solid electrolyte by in-situ fluorination. The fluoride is LiF and InF3 or LiF and ZrF4. The thickness of the fluoride coating layer is 1-5 nm. The core-shell solid electrolyte material retains ≥40% of room temperature ionic conductivity after being exposed to air with 20-50% relative humidity for 2-24 h. The particle size of the chloride solid electrolyte is 1-30 μm.

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