Solid-state electrolyte material with high conductivity and high stability to lithium and preparation method and application thereof

Abstract

The application belongs to the technical field of halide solid-state electrolyte, and relates to a modified halide solid-state electrolyte material with high conductivity and high stability to lithium, a preparation method and application of the modified halide solid-state electrolyte material. The preparation method is that halide solid-state electrolyte is taken as a base body, ammonium halide salt is taken as a solid source, and the halide solid-state electrolyte is modified by nitrogen, fluorine / chlorine / bromine and other element collaborative doping by using plasma technology to obtain the modified halide solid-state electrolyte material. The modified halide solid-state electrolyte material has excellent conductivity and lithium-lithium symmetrical battery performance, and has a wide market application prospect. Meanwhile, the preparation method is simple, fast, efficient, convenient and easy to control, and is helpful to promote the development and application of high-performance halide solid-state electrolyte materials.

Description

Technical Field

[0001] This invention relates to the field of halide solid electrolyte materials technology, specifically to a modified halide solid electrolyte material with high conductivity and high lithium stability constructed by solid source plasma, its preparation method and application. Background Technology

[0002] Lithium-ion batteries, due to their high energy density and long cycle life, have been widely used in portable digital electronic products, electric vehicles, and renewable energy storage systems. However, the organic electrolytes used in traditional lithium-ion batteries are flammable and explosive, posing a serious safety hazard. In contrast, solid-state batteries, using solid electrolytes, offer not only higher safety but also higher energy density, and are therefore considered a key direction for future battery technology development. During the development of solid-state batteries, the lithium-ion conductivity, chemical / electrochemical stability, and processability of solid electrolyte materials are crucial factors that need to be considered.

[0003] Currently, researchers are actively exploring various potential all-solid-state electrolyte candidates. Sulfide, oxide, boride, and halide electrolytes among inorganic solid electrolytes are the main research targets. Halide electrolytes exhibit good electrochemical stability, but their lithium-ion conductivity is relatively low. Density functional theory (DFT) calculations show that elemental doping can further improve the lithium-ion conductivity of halide electrolytes. However, existing doping methods mainly involve mechanical ball milling and sintering, which are time-consuming, cumbersome, and energy-intensive. Therefore, developing simple, rapid, and clean synthesis methods for halide solid-state electrolytes is considered to have high development potential and is expected to become an important component of future solid-state battery technology.

[0004] Based on this, the present invention proposes a modified halide solid electrolyte material with high conductivity and high lithium stability constructed by solid source plasma, as well as its preparation method and application. By effectively combining the above strategies, the halide solid electrolyte material is doped and modified, thereby improving the conductivity of the halide electrolyte and the interfacial stability between the halide electrolyte and the lithium anode, which helps to promote the development and application of halide electrolyte materials. Summary of the Invention

[0005] This invention addresses the problems of low electronic conductivity, poor lithium stability, and insufficient cycle stability of halide electrolyte materials. It provides a modified halide solid electrolyte material with high conductivity and high lithium stability constructed by solid-source plasma, along with its preparation method and applications. By employing plasma technology, a large number of highly active free radicals are excited by ammonium salt solid-source plasma, enabling nitrogen, fluorine / chlorine / bromine element doping and coating of halide electrolytes at low temperatures. This optimizes the conductivity and improves the poor lithium stability of the halide electrolyte material, thereby enhancing its electrochemical performance.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] A method for preparing modified halide solid electrolyte materials with high conductivity and high lithium stability by solid-source plasma construction. The method uses halide solid electrolyte as a matrix and ammonium halide salt as a solid source. The halide electrolyte is doped with nitrogen and halogen elements fluorine / chlorine / bromine by a one-step plasma method to obtain modified halide solid electrolyte materials.

[0008] Preferably, the method includes the following steps:

[0009] (1) Place the halide solid electrolyte inside the plasma reactor and connect it to the plasma generator to perform vacuum treatment on the reaction area of ​​the plasma reactor.

[0010] (2) Connect an external solid source. The solid source sublimates into the plasma reaction device to a certain vacuum level. The ignition of the solid source plasma is controlled by adjusting the radio frequency power. The solid source plasma is then reacted with the halide solid electrolyte material. After a certain reaction time, the radio frequency power is turned off to obtain the modified halide solid electrolyte material doped with nitrogen and halogen elements fluorine / chlorine / bromine.

[0011] The following are preferred technical solutions of the present invention:

[0012] Preferably, in step (1), the halide solid electrolyte is Li3MX6 solid electrolyte, wherein M is selected from at least one of In, Sc, Y, Er, Tb, Zr, Zn, Sn, Yb, or Lu, and X is selected from at least one of Cl, Br, or I.

[0013] Preferably, in step (1), the selected halide electrolyte sample is at least one of flake and powder form. More preferably, the sample can be processed more uniformly by a rotating plasma device, and can react more fully with the introduced solid source plasma.

[0014] Preferably, in step (1), the vacuum is evacuated to a vacuum level of 1-70 Pa, and the vacuum state is maintained.

[0015] Preferably, in step (2), the solid source is at least one of ammonium fluoride, ammonium chloride, or ammonium bromide.

[0016] Preferably, in step (2), the solid source is heated to a sublimation state and then sublimates into the plasma reactor. If the solid source and solid electrolyte are directly mixed and placed in the plasma reactor for reaction, it will be difficult to control the reaction process and impurities will easily remain. Therefore, by sublimating the solid source, the solid source is introduced into the plasma reactor to better excite the solid source into a plasma state and react with the solid electrolyte.

[0017] Preferably, in step (2), the vacuum level of the system after the solid source is introduced is 5-200 Pa.

[0018] Preferably, in step (2), the plasma reaction device can be heated before introducing the solid source, and the system temperature can be heated to the reaction temperature, specifically from room temperature to 500°C. o C. This temperature range, especially heating, makes it easier to excite the introduced solid source into a plasma state.

[0019] Preferably, in step (2), the reaction conditions are: the radio frequency power is 50-300 W, the reaction temperature is room temperature to 500 ℃, and the reaction time is 1-30 min; furthermore, the vacuum degree is preferably 5-200 Pa.

[0020] Preferably, in step (2), nitrogen and halogen elements are co-doped and modified, and the halogen elements include at least one of fluorine, chlorine and bromine; more preferably, the amount of nitrogen doping is 0.5-5% of the mass of the modified halide solid electrolyte material, and the amount of halogen doping is 0.5-5% of the mass of the modified halide solid electrolyte material.

[0021] Preferably, the room temperature in this invention is 10-40°C, more preferably 15-25°C.

[0022] The present invention also provides a modified halide solid electrolyte material with high conductivity and high lithium stability constructed by solid source plasma prepared by any of the above preparation methods.

[0023] Preferably, the halide solid electrolyte is modified by synergistic doping with nitrogen and halogen elements fluorine / chlorine / bromine.

[0024] This invention also provides an application of a modified halide solid electrolyte material with high conductivity and high lithium stability prepared by any of the above preparation methods in the field of lithium-ion batteries.

[0025] This invention utilizes plasma technology to excite a solid source ammonium salt, generating a large number of highly reactive free radicals. Under low-temperature heating conditions, this allows for the synergistic doping modification of a halide solid electrolyte with nitrogen and fluorine / chlorine / bromine elements, thereby optimizing the conductivity and lithium stability of the halide solid electrolyte. The amount of nitrogen and fluorine / chlorine / bromine doping prepared by this invention can be controlled by parameters such as reaction time, radio frequency power, and heating temperature.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) By means of solid plasma effect, a one-step method is used to prepare nitrogen and fluorine / chlorine / bromine doped halide electrolyte materials. The preparation method is simple, fast and efficient and the conditions are mild.

[0028] (2) Co-doping with nitrogen and fluorine / chlorine / bromine elements can simultaneously optimize the bulk structure and surface interface properties of materials, overcoming the limitations of single doping. It can improve the ionic conductivity of halide electrolytes, enhance the stability of materials to lithium, and effectively improve material performance;

[0029] (3) By precisely adjusting the doping amount of nitrogen and fluorine / chlorine / bromine elements through temperature-plasma synergy, the chemical composition and interfacial characteristics of halide electrolytes can be improved, thereby achieving the controllability of material properties and further expanding the application of materials;

[0030] This invention involves a one-step reaction between solid-state plasma excitation and halide electrolyte materials. Co-doping with nitrogen and fluorine / chlorine / bromine elements is a highly effective way to optimize halide solid-state electrolyte materials, improving their ionic conductivity and lithium stability, resulting in excellent conductivity and lithium-lithium symmetric battery performance. Furthermore, the preparation method provided by this invention is simple, rapid, efficient, convenient, and easy to control, contributing to the development and application of high-performance halide solid-state electrolyte materials. Attached Figure Description

[0031] Figure 1 SEM images of the nitrogen and fluorine co-doped Li3InCl6 halide electrolyte in Example 1 and the unmodified Li3InCl6 halide electrolyte in Comparative Example 1.

[0032] Figure 2 The elemental distribution diagram of the Li3InCl6 halide electrolyte co-doped with nitrogen and fluorine elements in Example 1 is shown.

[0033] Figure 3 The images show the XRD patterns of the nitrogen and fluorine co-doped Li3InCl6 halide electrolyte prepared in Example 1 and Comparative Example 1.

[0034] Figure 4The diagram shows the ionic conductivity of the nitrogen and fluorine co-doped Li3InCl6 halide electrolyte prepared in Example 1. Detailed Implementation

[0035] To facilitate understanding, the technical solutions and implementation methods of the present invention will be further described clearly, completely, and in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the embodiments described herein are implemented based on the technical solutions of the present invention, providing detailed implementation methods and specific operating procedures, but are only some embodiments of the present invention, not all embodiments. The specific implementation methods described are limited to illustrating and explaining the present invention and do not limit the present invention. Based on the embodiments of the present invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Unless otherwise specified, the experimental methods and conditions used in the following embodiments are conventional methods and conditions. The materials, reagents, instruments, and equipment used in the embodiments, unless otherwise specified, are all conventional substances or equipment known to those skilled in the art and are commercially available. The reaction conditions described in the invention can all achieve the reactions and obtain the desired products. Due to space limitations, only some embodiments are listed below to further illustrate the advantages of the technical solution of the present invention.

[0037] Example 1

[0038] A powder sample of Li3InCl6 halide electrolyte (refer to the method in Comparative Example 1) was placed in the reaction zone of a rotating plasma reactor. Copper rings were connected to both ends of the reactor, and the rings were connected to the generator (plasma generator) of the radio frequency power supply using wires. The plasma reactor was then evacuated to 10 Pa and maintained under vacuum. The temperature was raised to 200 °C, and an ammonium fluoride solid source was connected. The ammonium fluoride solid source was heated and sublimated into the plasma reactor using a heating mantle, raising the vacuum level to 40 Pa. The radio frequency power switch was turned on, and the radio frequency power was adjusted to 100 W. The vacuum pump was adjusted to maintain the vacuum level at 20 Pa, and the reaction temperature was maintained at 200 °C. After ignition, a large number of highly active free radicals were excited in the ammonium fluoride plasma reaction zone and reacted with the surface of the halide solid electrolyte. After 5 min of plasma reaction, the radio frequency power supply was turned off, yielding a nitrogen- and fluorine co-doped Li3InCl6 halide electrolyte material.

[0039] Example 2-25

[0040] Based on Example 1, the reaction conditions were changed, including the solid source, reaction temperature, reaction power, and reaction time. The specific conditions are shown in Table 1 below.

[0041]

[0042] Examples 26-35

[0043] Based on Example 1, the precursor was changed to Li3InBr6 solid electrolyte (refer to the method of Comparative Example 9), and some of the reaction conditions in Table 1 were selected for the experiment. The specific conditions are shown in Table 2 below.

[0044]

[0045] Comparative Example 1

[0046] Lithium chloride and indium chloride in a molar ratio of 3:1 were weighed and ball-milled at 500 r / min for 24 h in an argon atmosphere. The ball-milled powder was then subjected to further grinding in an argon atmosphere at 4... o C·min -1 Heat up to 260 o C, keep warm for 5 h and then cool naturally to obtain Li3InCl6 halide electrolyte powder.

[0047] Comparative Example 2

[0048] The Li3InCl6 halide electrolyte material from Comparative Example 1 was placed in a conventional tube furnace, and nitrogen protective gas was introduced, followed by a 5% [temperature / pressure]. o C·min -1 The temperature was increased to 200 °C, held for 2 hours, and then allowed to cool naturally, but element doping was not successfully achieved.

[0049] Comparative Example 3

[0050] The Li3InCl6 halide solid electrolyte material from Comparative Example 1 was placed in a conventional tube furnace, and 5% (by mass) of ammonium fluoride solid was added. Nitrogen protective gas was introduced, followed by a 5% induction furnace. o C·min -1 Heating rate increased to 200 o C, after holding at this temperature for 2 hours, was allowed to cool naturally, but element doping was not successfully achieved.

[0051] Comparative Example 4

[0052] The Li3InCl6 halide electrolyte material from Comparative Example 1 was placed in a conventional tube furnace, and 5% (by mass) of ammonium chloride solid (Li3InCl6 halide solid electrolyte) was added. Nitrogen protective gas was introduced, followed by a 5% [unclear - possibly a specific pressure or flow rate]. o C·min -1 Heating rate increased to 200 o C, after holding at this temperature for 2 hours, was allowed to cool naturally, but element doping was not successfully achieved.

[0053] Comparative Example 5

[0054] The Li3InCl6 halide electrolyte material from Comparative Example 1 was placed in a conventional tube furnace, and 5% (by mass) of ammonium bromide solid (Li3InCl6 halide solid electrolyte) was added. Nitrogen protective gas was introduced, followed by a 5%... o C·min -1 Heating rate increased to 200 o C, after holding at this temperature for 2 hours, was allowed to cool naturally, but element doping was not successfully achieved.

[0055] Comparative Example 6

[0056] The Li3InCl6 halide electrolyte material from Comparative Example 1 was placed in a hydrothermal high-pressure reactor, and 5% ammonium fluoride solid (by mass) of Li3InCl6 halide solid electrolyte was added. The reactor was then placed in a hydrothermal oven at 180°C for 10 h. After natural cooling, elemental doping was not successfully achieved.

[0057] Comparative Example 7

[0058] The Li3InCl6 halide electrolyte material from Comparative Example 1 was placed in the reaction zone of a rotating plasma reactor. Copper rings were connected to both ends of the reactor, and the rings were connected to the generator (plasma generator) of the radio frequency power supply via wires. The plasma reactor was then evacuated to 10 Pa and maintained under vacuum, while the temperature was raised to 200 °C. An ammonium fluoride solid source was introduced, the radio frequency power switch was turned on, and the radio frequency power was adjusted to 10 W. The vacuum pump was adjusted to maintain the vacuum at 30 Pa. After processing for 10 min, the material was allowed to cool naturally to obtain the modified Li3InCl6 halide electrolyte material, but doping was not successfully achieved.

[0059] Comparative Example 8

[0060] The Li3InCl6 halide electrolyte material from Comparative Example 1 was placed in the reaction zone of a rotating plasma reactor. Copper rings were connected to both ends of the reactor, and the rings were connected to the generator (plasma generator) of the radio frequency power supply with wires. The plasma reactor was then evacuated to 10 Pa and maintained under vacuum, while the temperature was raised to 200 °C. An ammonium fluoride solid source was introduced, the radio frequency power switch was turned on, and the radio frequency power was adjusted to 500 W. The vacuum pump was adjusted to maintain a vacuum of 30 Pa. After processing for 10 min, the material was allowed to cool naturally to obtain the modified Li3InCl6 halide electrolyte material, but doping was not successfully achieved.

[0061] Comparative Example 9

[0062] Lithium bromide and indium bromide in a molar ratio of 3:1 were weighed and ball-milled at 500 r / min for 24 h in an argon atmosphere. The ball-milled powder was then subjected to further grinding in an argon atmosphere at 4... o C·min -1 Heat up to 260 o C, keep warm for 5 h and then cool naturally to obtain Li3InBr6 halide electrolyte powder.

[0063] Performance Test 1

[0064] The Li3InCl6 halide electrolyte sample powders prepared in Examples 1-25 and Comparative Examples 1-8 were compressed into tablets. To test the ionic conductivity of the electrolyte, carbon-coated aluminum foil was placed at both ends of the tablet, which was then placed in a coin cell and subjected to pressure before testing. An electrochemical workstation was connected, test parameters were set, and the test was started. The AC impedance test frequency range was 1MHz to 0.1Hz, and the voltage amplitude was 5-10mV. To test the lithium stability of the electrolyte, the battery was assembled in the following order: positive electrode shell, lithium sheet, halide electrolyte sheet, lithium sheet, and negative electrode shell, and then sealed using a packaging machine. After the battery was left to stand for 24 hours, electrochemical tests were performed using a Newway testing system.

[0065] The performance test results are shown in Table 3 below.

[0066]

[0067] As shown in Table 3, the performance test results of the various embodiments and comparative examples reveal that Examples 1-25, which used plasma doping modification with ammonium salt solid sources as the excitation source, generally exhibited excellent electrochemical performance of the resulting halide solid electrolytes, with significant improvements in ionic conductivity and lithium-lithium symmetric battery cycle time. Comparative Examples 1-8, which employed conventional interface treatment methods and other inorganic source plasma treatments, also showed improved electrochemical performance compared to the untreated halide solid electrolytes, but the effects were significantly less than those of the plasma-modified electrolytes containing nitrogen, fluorine / chlorine / bromine elements as specified in this invention. This indicates that halide solid electrolytes are more suitable for plasma doping modification with nitrogen, fluorine / chlorine / bromine elements to improve various related electrochemical properties of the electrolyte.

[0068] Performance Test 2

[0069] The Li3InBr6 halide electrolyte sample powders prepared in Examples 26-35 and Comparative Example 9 were pressed into tablets, and their ionic conductivity and lithium stability were tested according to the method in Performance Test 1. The performance test results are shown in Table 4 below.

[0070]

[0071] As shown in Table 4, the performance test results of the various examples and comparative examples reveal that Examples 26-35, which employed plasma doping modification with ammonium salt solid sources as the excitation source and Li3InBr6 halide electrolyte as the precursor, exhibited superior electrochemical performance compared to the untreated Comparative Example 9. The ionic conductivity and cycle time of the lithium-lithium symmetric battery were significantly improved. This indicates that not only Li3InCl6 halide solid electrolytes, but also other halide solid electrolytes (such as Li3InBr6 mentioned above) can have their various related electrochemical properties enhanced through plasma doping modification with nitrogen, fluorine / chlorine / bromine elements.

[0072] Figure 1 SEM images of the nitrogen and fluorine co-doped Li3InCl6 halide electrolyte in Example 1 and the unmodified Li3InCl6 halide electrolyte in Comparative Example 1 are shown. Compared with the unmodified Li3InCl6 halide electrolyte, the nitrogen and fluorine co-doped Li3InCl6 halide electrolyte shows uniformly distributed small particles on its surface.

[0073] Figure 2 The image shows the elemental distribution of the Li3InCl6 halide electrolyte co-doped with nitrogen and fluorine in Example 1. Fluorine and nitrogen are uniformly distributed in the Li3InCl6 halide electrolyte, achieving effective fluorine and nitrogen doping.

[0074] Figure 3 The images show the XRD patterns of the nitrogen and fluorine co-doped Li3InCl6 (LIC-NH4F) halide electrolyte prepared in Example 1 and the unmodified Li3InCl6 halide electrolyte (LIC) in Comparative Example 1, as well as the PDF card image of Li3InCl6 with the standard powder diffraction database number PDF#70-3274. The XRD test results of the nitrogen and fluorine co-doped Li3InCl6 halide electrolyte are not significantly different from those of the unmodified Li3InCl6 halide electrolyte, indicating that plasma doping technology does not change the crystal structure of Li3InCl6 halides, can well maintain the structure of the material, and effectively achieve elemental doping without changing the structure.

[0075] Figure 4 The diagram shows the ionic conductivity of the nitrogen- and fluorine co-doped Li3InCl6 (LIC-NH4F) halide electrolyte prepared in Example 1 and the unmodified Li3InCl6 halide electrolyte (LIC) in Comparative Example 1. The ionic conductivity of the nitrogen- and fluorine co-doped Li3InCl6 halide electrolyte is 0.58 mS / cm, while the ionic conductivity of the unmodified Li3InCl6 halide electrolyte is only 0.44 mS / cm. The ionic conductivity of the halide electrolyte after plasma treatment is significantly improved.

[0076] This application modifies halide electrolytes by doping with nitrogen, fluorine / chlorine / bromine elements using solid-source plasma technology, resulting in higher ionic conductivity and lithium stability.

[0077] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Other variations and modifications may be made without departing from the technical solutions described in the claims.

Claims

1. A method for producing a modified halide solid-state electrolyte material having high conductivity and high stability against lithium, which is a solid source plasma construction, characterized by, The method is based on a halide solid-state electrolyte, an ammonium halide salt as a solid source, and a one-step plasma method for nitrogen and halogen element doping modification of the halide solid-state electrolyte to obtain a modified halide solid-state electrolyte material. The halide solid-state electrolyte is a Li3MX6 solid-state electrolyte, wherein M is at least one of In, Sc, Y, Er, Tb, Zr, Zn, Sn, Yb, or Lu, and X is at least one of Cl, Br, or I. The solid source is at least one of ammonium fluoride, ammonium chloride, or ammonium bromide. The plasma reaction conditions are: a radio frequency power of 50-300 W, a reaction temperature of room temperature-200 ℃, and a reaction time of 1-30 min.

2. The method of claim 1, wherein the modified halide solid-state electrolyte material is prepared by a solid source plasma method. The method comprises the following steps: (1) placing the halide solid-state electrolyte in the plasma reaction device and connecting it with the plasma generator, and performing vacuum treatment; (2) connecting the external solid source, sublimating the solid source into the plasma reaction device to a certain vacuum degree, adjusting the radio frequency power, and reacting for a certain time after ignition to obtain a modified halide solid-state electrolyte material.

3. The method of claim 2, wherein the method is characterized by: In step (1), the vacuum degree is 1-70 Pa.

4. The method for preparing a modified halide solid-state electrolyte material with high conductivity and high stability to lithium according to claim 3, characterized in that, In step (2), the vacuum degree of the system after the solid source is introduced is 5-200 Pa. And / or, the temperature of the reaction device when the solid source is introduced is room temperature to 500 ℃.

5. The method of claim 2, wherein the modified halide solid-state electrolyte material is prepared by a solid source plasma method. The doping amount of nitrogen and halogen elements in the modified halide solid-state electrolyte material is 0.5-5% of the mass of the modified halide solid-state electrolyte material.

6. A solid source plasma constructed high conductivity and high lithium stability modified halide solid-state electrolyte material prepared by the preparation method of any one of claims 1-5.

7. The application of the solid source plasma constructed high conductivity and high lithium stability modified halide solid-state electrolyte material of claim 6 in the field of lithium ion batteries.

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