A high-entropy halide solid electrolyte material, its preparation method and application

Abstract

The present invention relates to a high-entropy halide solid electrolyte material, a preparation method thereof, and an application thereof. The general formula of the high-entropy halide solid electrolyte material is: Li a M n X x , where M includes at least 5 metal elements from groups IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and VB, and X includes one or more halogen elements; 1 < a < 5, 0.3 < n < 2, x = a + nε, and ε is the weighted average valence of M. The electrolyte material of the present invention is prepared by the following preparation method: Weigh the precursors LiX and the halides MX corresponding to at least 5 metal elements according to the stoichiometric ratio of the general formula ε and perform ball milling treatment to obtain a mixed powder. Press the mixed powder into tablets, then perform heat treatment sintering in an argon atmosphere, and then grind to obtain the target product. Compared with the prior art, the high-entropy halide solid electrolyte material of the present invention has better electrochemical stability and cycling stability in solid-state batteries, while ensuring high Li + ionic conductivity, and the preparation method has a simple process and easy-to-control conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and relates to a high-entropy halide solid electrolyte material, a preparation method thereof, and an application thereof. Background Art

[0002] Lithium-ion batteries based on traditional liquid electrolytes have been widely used in various fields such as portable electronic products and new energy vehicles. However, with the improvement of the battery energy density, the risk of explosion and combustion has also increased. In particular, in recent years, safety accidents of new energy vehicles have occurred frequently. This is mainly because traditional lithium-ion batteries use flammable organic solvents as electrolytes, and safety problems such as leakage, volatilization, and combustion may occur during use, posing safety hazards and affecting the battery life. Solid-state lithium batteries use non-flammable solid electrolytes to replace organic liquid electrolytes, and are expected to achieve the intrinsic safety of the battery, installing "safety genes" for new energy vehicles. As one of the most core materials in solid-state lithium batteries, the main function of solid electrolytes is to isolate the positive and negative electrodes and prevent electrons from passing through, while allowing ions to pass through, so as to complete the rapid transmission of lithium ions between the positive and negative electrodes during the charge and discharge process.

[0003] At present, the research on solid electrolytes mainly focuses on materials such as polymers, oxides, sulfides, and halides. Among them, halide-based solid electrolytes (Li3YCl6, Li3YBr6, Li3InCl6, etc.) are a new type of solid electrolytes emerging in recent years, with good ionic conductivity (>10 -3 S / cm), a relatively wide electrochemical window, excellent stability for high-voltage oxide cathodes, and halides have certain advantages in processing technology (aqueous medium liquid-phase synthesis) and raw material costs. However, the electrochemical stability of halide solid electrolytes and lithium metal anodes is poor, and side reactions are likely to occur during the cycling of solid-state batteries, which in turn cause problems such as damage to the structure of solid electrolytes, reduction of cycling stability, and battery failure. Therefore, it is urgent to develop halide solid electrolyte materials with good structural stability. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-entropy halide solid electrolyte material, a preparation method thereof, and an application thereof, in order to overcome the problem of poor stability of halide solid electrolytes in the prior art, aiming to prepare a high-entropy halide solid electrolyte and improve the electrochemical stability and cycling stability of halide solid electrolytes in solid-state batteries.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] One of the technical solutions of the present invention provides a high-entropy halide solid electrolyte material, and the general formula of the high-entropy halide solid electrolyte material is:

[0007] Li a M n X x ,

[0008] In the formula, M includes at least 5 metal elements from groups IIA, IIB, IIIA, IIIB, IVA, IVB, VA, and VB, and X includes one or more halogen elements; 1<a<5, 0.3<n<2, x=a+nε, and ε is the weighted average valence of M.

[0009] Furthermore, M includes at least five metal elements selected from the group consisting of Mg, Zn, Al, Sc, Ga, Y, In, Zr, Hf, Sb, Bi, and lanthanide elements.

[0010] Furthermore, X includes one or more of F, Cl, Br, and I.

[0011] Furthermore, the chemical formula of the high entropy halide solid electrolyte material is:

[0012] Y3 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 6.2 、Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.3 Cl 6.6 ,

[0013] Y3 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.4 Cl7、Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.5 Cl 7.4 ,

[0014] Y3 0.2 In 0.2 Er 0.2 Sc 0.2 Zr 0.2 Cl 6.2 or Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 3.2 Br3.

[0015] Furthermore, the Li + ionic conductivity of this high-entropy halide solid electrolyte material is greater than 1×10 -3 S / cm.

[0016] The second technical solution of the present invention provides a preparation method of the above high-entropy halide solid electrolyte material, and the preparation method is as follows:

[0017] Weigh the precursor LiX and halides MX corresponding to at least five metal elements according to the stoichiometric ratio of the general formula ε and perform ball milling treatment to obtain a mixed powder. Press the mixed powder into tablets, then perform heat treatment sintering in an argon atmosphere, and then grind to obtain the target product.

[0018] Furthermore, the ball milling speed is 300 - 800 rpm, and the ball milling treatment time is 10 - 50 h.

[0019] Furthermore, during the tablet pressing process, the pressure is 1 - 5 t, and the pressure holding time is 1 - 10 min.

[0020] Furthermore, the temperature of the heat treatment sintering is 150 - 650 °C, the time is 2 - 15 h, and the heating rate is 2 °C / min.

[0021] The third technical solution of the present invention provides an application of the above high-entropy halide solid electrolyte material, and this high-entropy halide solid electrolyte material is used to prepare a solid electrolyte or a composite positive and negative electrode additive of a solid-state lithium battery.

[0022] Furthermore, the solid-state lithium battery includes a semi-solid-state lithium battery, a quasi-solid-state lithium battery or a full-solid-state lithium battery.

[0023] The high-entropy halide solid electrolyte material of the present invention has a relatively high Li + ionic conductivity.

[0024] Due to the diversity of its composition and the stability of its structure, high-entropy materials (HEMs) have great development potential in the energy field. Research reports show that (Energy & Environmental Science. 2021, 14, 2883), when high-entropy materials are used in battery applications, their entropy-stabilized conversion mechanism plays a role during the electrochemical cycle process, and the original structure is retained to a certain extent. It is the conversion host, inhibiting the phase change of the host structure during the cycle, maintaining the structural stability, thus improving the stability of the solid electrolyte to the electrode, reducing the side reactions between the solid electrolyte and the electrode, and enhancing the cycle life of the solid-state battery.

[0025] During the synthesis process of the high-entropy halide solid electrolyte material of the present invention, the precursor LiX and MXε During the reaction in high-speed mechanical ball milling, element M occupies the Li sites in the LiX lattice and introduces a large number of Li vacancies, generating Li + halide solid electrolyte Li with high conductivity a M n X x (1 < a < 5, 0.3 < n < 2, x = a + nε), so the ionic radius of element M needs to be close to that of element Li to meet the element doping requirements. The value ranges of a and n ensure an appropriate doping concentration, introducing an appropriate amount of Li vacancies while retaining migratable Li ions. The subsequent tablet pressing and heat treatment processes are beneficial to improving the crystallinity of the halide solid electrolyte, reducing the defect concentration, and increasing the grain boundary conductivity. Appropriate process conditions during the preparation are beneficial to increasing the Li + conductivity of the product high-entropy halide solid electrolyte.

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

[0027] (1) The present invention designs the above high-entropy halide solid electrolyte material from the structure of the material itself. Compared with general halide solid electrolyte materials, the present invention adopts a high-entropy synthesis strategy, which can effectively regulate the conductivity, electrochemical window, etc. of the halide solid electrolyte. At the same time, due to the high-entropy effect, the structure of the high-entropy halide solid electrolyte material is more complex and diverse. The high-entropy halide solid electrolyte material of the present invention is used to prepare the solid electrolyte of a solid-state lithium battery, which improves the electrochemical stability and cycle stability of the halide solid electrolyte in the solid-state battery while ensuring high Li + conductivity.

[0028] (2) The preparation method of the high-entropy halide solid electrolyte material of the present invention has a simple process and easy-to-control conditions, can obtain stable products, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 X-ray diffraction pattern of the high-entropy halide solid electrolyte material of Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 6.2 in Example 1;

[0030] Figure 2 X-ray diffraction pattern of the high-entropy halide solid electrolyte material of Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 6.2Scanning electron microscope images of the high-entropy halide solid electrolyte material;

[0031] Figure 3 For Li3Y in Example 1 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 6.2 Elemental distribution maps of the high-entropy halide solid electrolyte material;

[0032] Figure 4 Electrochemical impedance spectra of the high-entropy halide solid electrolyte material in Example 1;

[0033] Figure 5 For Li3Y in Example 2 0.2 In 0.2 Er 0.2 Sc 0.2 Zr 0.2 Cl 6.2 Electrochemical impedance spectra of the high-entropy halide solid electrolyte material;

[0034] Figure 6 For Li3Y in Example 3 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 3.2 Electrochemical impedance spectra of the Li3YBr3 high-entropy halide solid electrolyte material. Detailed implementation manners

[0035] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0036] In the following embodiments, unless otherwise specified for raw materials or processing techniques, it means that the conventional commercially available raw material products or conventional processing techniques in the art are used.

[0037] Example 1:

[0038] This example is Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 6.2 、Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.3Cl 6.6 、Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.4 Cl7、Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.5 Cl 7.4 Preparation and Electrochemical Properties of High-Entropy Halide Solid Electrolyte Materials.

[0039] Weigh respectively under a high-purity argon atmosphere:

[0040] 1)Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 6.2 : 0.64 g of LiCl, 0.20 g of YCl3, 0.22 g of InCl3, 0.27 g of ErCl3, 0.28 g of YbCl3, 0.23 g of ZrCl4;

[0041] 2)Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.3 Cl 6.6 : 0.64 g of LiCl, 0.20 g of YCl3, 0.22 g of InCl3, 0.27 g of ErCl3, 0.28 g of YbCl3, 0.35 g of ZrCl4;

[0042] 3)Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.4 Cl7: 0.64 g of LiCl, 0.20 g of YCl3, 0.22 g of InCl3, 0.27 g of ErCl3, 0.28 g of YbCl3, 0.47 g of ZrCl4;

[0043] 4)Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.5 Cl 7.4 : 0.64 g of LiCl, 0.20 g of YCl3, 0.22 g of InCl3, 0.27 g of ErCl3, 0.28 g of YbCl3, 0.58 g of ZrCl4;

[0044] Add the raw materials in the above ratios to a zirconia ball milling jar and add zirconia milling beads with a diameter of 3 - 5 mm. The ball-to-material ratio is 30:1. Ball mill using a planetary ball mill under an argon atmosphere. First, ball mill at a low speed of 300 r / min for 30 min to uniformly mix the raw materials; then use a high speed of 550 r / min to ball mill for 15 h. After ball milling, press the obtained powder sample into tablets under a pressure of 3 t to obtain a solid electrolyte tablet sample with a diameter of 10 mm; then place it in a crucible and transfer it to a muffle furnace under an argon atmosphere for heat treatment. The heat treatment temperature is 250 °C, the time is 5 h, and the heating rate is 2 °C / min. Cool naturally; transfer the obtained solid electrolyte tablet sample to an agate mortar and grind for 10 min until the powder particle diameter is evenly distributed, and finally obtain a high-entropy halide solid electrolyte powder sample corresponding to the chemical formula.

[0045] Figure 1 For Li3Y in this example 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 6.2 The X-ray diffraction pattern of the material, where, from Figure 1 The comparison of characteristic peaks shows that the synthesized high-entropy halide solid electrolyte powder material is a crystalline material with low crystallinity, and the anion stacking mode is cubic close-packed (ccp structure), which is similar to the structures of Li3InCl6 and LiCl.

[0046] Figure 2 For Li3Y in this example 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 6.2 The scanning electron microscope image of the material. It can be seen from Figure 2 that the diameters of the synthesized high-entropy halide solid electrolyte powder particles are evenly distributed in the range of 0.1 - 0.4 μm.

[0047] Figure 3 For Li3Y in this example 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 6.2 The elemental distribution map of the material. It can be seen from Figure 3 that the synthesized high-entropy halide solid electrolyte powder material has a uniform distribution of Y, In, Er, Yb, and Zr elements, indicating that the obtained target product is Li3Y 0.2 In 0.2Er 0.2 Yb 0.2 Zr 0.2 Cl 6.2 High-entropy halide solid electrolyte materials.

[0048] Figure 4 This is the electrochemical impedance spectrum of the high-entropy halide solid electrolyte powder material in this example. It can be seen from Figure 4 that the conductivity of the high-entropy halide solid electrolyte Li + first increases and then decreases with the increase of the doping amount of ZrCl4. When the chemical formula is Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.4 Cl7, the conductivity reaches the maximum value of 1.33 mS / cm. The conductivities of other ratios are Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 6.2 (0.44 mS / cm), Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.3 Cl 6.6 (0.65 mS / cm), Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.5 Cl 7.4 (0.83 mS / cm).

[0049] Example 2:

[0050] Weigh under a high-purity argon atmosphere:

[0051] Li3Y 0.2 In 0.2 Er 0.2 Sc 0.2 Zr 0.2 Cl 6.2 : LiCl 0.64 g, YCl3 0.20 g, InCl3 0.22 g, ErCl3 0.27 g, ScCl3 0.15 g, ZrCl4 0.23 g;

[0052] Add the above raw materials into a zirconia ball milling jar and add zirconia ball milling beads with a diameter of 3 - 5 mm. The ball-to-material ratio is 30:1. Use a planetary ball mill in an argon atmosphere. First, ball mill at a low speed of 300 r / min for 30 min to evenly mix the raw materials; then use a high speed of 550 r / min to ball mill for 15 h. After ball milling, press the obtained powder sample. The pressure is 3 t to obtain a solid electrolyte sheet sample with a diameter of 10 mm; then place it in a crucible and transfer it to a muffle furnace in an argon atmosphere for heat treatment. The heat treatment temperature is 250 °C, the time is 5 h, and the heating rate is 2 °C / min. Cool it naturally; transfer the obtained solid electrolyte sheet sample to an agate mortar and grind it for 10 min until the powder particle diameter distribution is uniform, and finally obtain a high-entropy halide solid electrolyte powder sample with the corresponding chemical formula.

[0053] Figure 5 Li3Y in this example 0.2 In 0.2 Er 0.2 Sc 0.2 Zr 0.2 Cl 6.2 Electrochemical impedance spectrum of the high-entropy halide solid electrolyte powder material. From Figure 5 It can be seen that Li3Y 0.2 In 0.2 Er 0.2 Sc 0.2 Zr 0.2 Cl 6.2 High-entropy halide solid electrolyte Li + The conductivity is 1.43 mS / cm.

[0054] Example 3:

[0055] Weigh in a high-purity argon atmosphere:

[0056] Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 3.2 Br3: 1.30 g of LiBr, 0.20 g of YCl3, 0.22 g of InCl3, 0.27 g of ErCl3, 0.28 g of YbCl3, 0.23 g of ZrCl4;

[0057] Add the above raw materials into a zirconia ball milling jar and add zirconia ball milling beads with a diameter of 3 - 5 mm. The ball-to-material ratio is 30:1. Use a planetary ball mill in an argon atmosphere. First, ball mill at a low speed of 300 r / min for 30 min to make the raw materials mix evenly; then use a high speed of 550 r / min to ball mill for 15 h. After ball milling, press the obtained powder sample. The pressure is 3 t to obtain a solid electrolyte tablet sample with a diameter of 10 mm; then put it into a crucible and transfer it to a muffle furnace in an argon atmosphere for heat treatment. The heat treatment temperature is 250 °C, the time is 5 h, the heating rate is 2 °C / min, and it is cooled naturally; transfer the obtained solid electrolyte tablet sample to an agate mortar and grind it for 10 min until the powder particle diameter distribution is uniform, and finally obtain a high-entropy halide solid electrolyte powder sample with the corresponding chemical formula.

[0058] Figure 6 Li3Y in this example 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 3.2 The electrochemical impedance spectrum of the Li3Y Figure 6 It can be seen that 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 3.2 Br3 high-entropy halide solid electrolyte Li + The conductivity is 1.67 mS / cm.

[0059] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A high-entropy halide solid electrolyte material, characterized in that, The general formula of the high-entropy halide solid electrolyte material is Li a M n X x , and the specific chemical formula is Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.4 Cl7, Li3Y 0.2 In 0.2 Er 0.2 Sc 0.2 Zr 0.2 Cl 6.2 or Li3Y 0.2 In 0.2 Er 0.2 Yb 0.2 Zr 0.2 Cl 3.2 Br3; The high-entropy halide solid electrolyte material is prepared by the following method: Weigh the precursors LiX and the halides MX corresponding to at least five metal elements according to the stoichiometric ratio of the general formula. ε Perform ball milling treatment to obtain a mixed powder. Press the mixed powder, then conduct heat treatment sintering under an argon atmosphere, and then obtain the target product through grinding. 1 < a < 5, 0.3 < n < 2, x = a + nε, where ε is the weighted average valence of M; M includes at least 5 metal elements selected from Mg, Zn, Al, Sc, Ga, Y, In, Zr, Hf, Sb, Bi, and lanthanide elements; X includes one or more of F, Cl, Br, and I; The ball milling speed is 300 - 800 rpm, and the ball milling time is 10 - 50 h; The Li + ionic conductivity of the high-entropy halide solid electrolyte material is greater than 1×10 -3 S / cm.

2. The preparation method of a high-entropy halide solid electrolyte material according to claim 1, characterized in that, The preparation method is as follows: Weigh the precursors LiX and halides MX corresponding to at least five metal elements according to the stoichiometric ratio of the general formula ε Perform ball milling treatment to obtain a mixed powder. Press the mixed powder, then conduct heat treatment sintering in an argon atmosphere, and then obtain the target product through grinding.

3. The preparation method of a high-entropy halide solid electrolyte material according to claim 2, characterized in that, During the tabletting process, the pressure is 1 - 5 t, and the pressure holding time is 1 - 10 min; The temperature for heat treatment sintering is 150 - 650 °C, the time is 2 - 15 h, and the heating rate is 2 °C / min.

4. The application of a high-entropy halide solid electrolyte material as described in claim 1, characterized in that, The high-entropy halide solid electrolyte material is used to prepare a solid electrolyte or a composite positive and negative electrode additive for a solid-state lithium-ion battery.

5. The application of a high-entropy halide solid electrolyte material according to claim 4, characterized in that, The solid-state lithium-ion battery includes a semi-solid-state lithium-ion battery, a quasi-solid-state lithium-ion battery, or a full-solid-state lithium-ion battery.

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