Oxidation halide solid electrolyte as well as preparation method and application thereof

Abstract

The invention discloses an oxyhalide solid electrolyte as well as a preparation method and application thereof, and the oxyhalide solid electrolyte with a relatively low crystallization degree is synthesized by a two-step method of extracting rare earth oxide from a neodymium ore raw material and performing high-energy ball milling by taking fluorocarbon perovskite as a raw material. The chemical general formula of the material is [Li (6-ac-3b) MaNdb] < 6 + > [OyX (6-2y)] < 6->, wherein M is at least one element of Ti, Zr, Hf, V, Nb and Ta; x is at least one element of F, Cl, Br and I. The conductivity of the electrolyte prepared by the method is higher than 1mS / cm at room temperature, the chemical composition can be freely adjusted, and the electrolyte has the electrochemical properties of higher ionic conductivity and wider electrochemical window, and can be directly applied to all-solid-state lithium ion batteries. The process for directly extracting the rare earth elements from the minerals has the advantage of low cost.

Description

Technical Field

[0001] This invention relates to the fields of mineral screening technology and battery technology, specifically to halide oxide solid electrolytes, their preparation methods, and applications. Background Technology

[0002] All-solid-state batteries are considered an ideal choice for future energy storage technology, promising to overcome the safety challenges faced in the commercialization of traditional lithium-ion batteries and achieve breakthroughs in energy density. To fundamentally address a series of safety issues that may arise during the use of conventional commercial lithium-ion batteries, such as leakage, combustion, and explosion of flammable organic electrolytes, researchers have proposed designing novel all-solid-state lithium batteries using non-flammable inorganic solid electrolytes instead of organic electrolytes. Furthermore, all-solid-state lithium batteries are expected to overcome the energy density bottleneck faced by commercial lithium-ion batteries. However, the practical industrial application of all-solid-state lithium batteries still faces many challenges in terms of electrolytes. For example, currently, no solid electrolyte can simultaneously meet all the requirements for industrialization, namely high ionic conductivity, a wide electrochemical window, ease of processing, and low material and manufacturing costs. Although currently developed halide solid electrolytes have advantages such as high ionic conductivity and a wide electrochemical stability window, the M element must be expensive trivalent rare earth elements such as Sc, Lu, and La, and the high raw material cost limits their commercialization.

[0003] Professors Sun Xueliang and Mo Yifei reported on the multi-factor balance transport mechanism and regulation strategy in halide solid-state ion conduction (J. Am. Chem. Soc. 2020, 142, 15, 7012–7022). Professor Xie Jia (Chin. Chem. Lett. 33(2022) 4635-4639) successfully transported In... 3+ Doping was incorporated into the Li₂ZrCl₆ crystal structure, and the maximum ionic conductivity (1.08 mS / cm) was obtained at a doping level of 0.25. Professor Ma Cheng developed an oxychloride solid electrolyte, Li₂ZrCl₆. 1.75 ZrCl 4.75 O 0.5 This satisfies the three conditions of ionic conductivity, deformability, and cost competitiveness very well (Nat Commun 14, 3807 (2023)). Professor Yao Hongbin of the University of Science and Technology of China reported a lithium superionic conductor based on LaCl3, which has good interfacial compatibility with lithium metal electrodes (Nature 616, 77–83 (2023)). Professor Sun Xueliang's team further regulated the transformation from crystalline to amorphous state of halide-based solid electrolytes and established the correlation between structure and ionic conductivity, synthesizing optimized amorphous Li3ZrCl4O 1.5Electrolytes (J. Am. Chem. Soc. 2024, 146, 5, 297–2985). However, current halide solid electrolytes still have problems such as difficulty in obtaining raw materials, high synthesis costs, and low ionic conductivity and reduction stability that urgently need to be solved. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a new halide oxide electrolyte, its preparation method and application, which can directly use minerals as raw materials to synthesize solid electrolytes, and use the oxygen source in rare earth oxides to induce the halide crystal structure to transform into halide oxides, thereby reducing the lithium ion migration activation energy and obtaining higher ionic conductivity.

[0005] This invention provides a novel halide oxide electrolyte, its preparation method, and its application. The solid halide oxide electrolyte exhibits an ionic conductivity greater than 1.0 mS / cm at 25°C, demonstrates excellent electrochemical performance, and its composition can be freely adjusted. This further expands the family of halide oxide electrolytes, including but not limited to applications in lithium-ion batteries. Its preparation process is relatively simple, and the raw material cost is lower than that of other halide and halide oxide electrolytes, which facilitates large-scale production.

[0006] This invention discloses a neodymium-based halide oxide all-solid-state electrolyte, which effectively solves the high cost problem of halide electrolytes by leveraging the advantages of high neodymium yield and low cost. my country has abundant neodymium ore production, including the world's largest rare earth deposit, the Bayan Obo mine, which has considerable reserves of fluorocarbonate-calcium neodymium ore. Its neodymium oxide content is approximately 30%, and its rare earth oxide content is approximately 60%. The abundant rare earth content supports the direct extraction of rare earth oxides from the minerals. The rich mineral reserves of neodymium significantly reduce the manufacturing cost of halide solid-state electrolytes, and its excellent ionic conductivity (>1.0 mS / cm) makes it a promising direction for the future industrialization of halide solid-state electrolytes. This invention is achieved through the following technical solution: A halide oxide solid electrolyte material with the chemical formula [Li (6-ac-3b) M a Nd b ] 6+ [O y X (6-2y) ] 6- ,in: M is at least one element selected from Ti, Zr, Hf, V, Nb, and Ta; X is at least one element selected from F, Cl, Br, and I; 0 < b ≤ 2, 0 ≤ a < 0.75, 4 ≤ c ≤ 5 (the value of c is determined by the valence state of element M; when M is Ti, Zr, or Hf, c = 4; when M is V, Nb, or Ta, c = 5; when M is multiple metals, 4 ≤ c ≤ 5), 0 < y ≤ 2. Preferably, to balance the comprehensive performance of the solid electrolyte in terms of electrochemical window, mechanical processability, ionic conductivity, and electronic conductivity, the halide oxide electrolyte can also be selected from various combinations where M is at least one element selected from Ti, Zr, Hf, V, Nb, or Ta, and X is at least one element selected from F, Cl, Br, or I. Preferably, to further improve the ionic conductivity and mechanical processability of the electrolyte, X is selected as Cl or Br, 0.4 < b < 0.8, 0.3 ≤ a ≤ 0.6, 4 ≤ c ≤ 5, 0.1 < y ≤ 0.4. Preferably, the X-ray diffraction pattern of the halide oxide electrolyte indicates that the main body matches the P63 / m space group.

[0007] A method for preparing the above-mentioned halide oxide solid electrolyte material includes the following steps: S1 involves roasting and acid leaching one or more rare earth minerals such as fluorocarbonate, fluorocarbonate, and fluorocarbonate, followed by multi-stage extraction of the neodymium-containing mother liquor. The neodymium oxalate in the mother liquor is then precipitated, filtered, and calcined to extract Nd2O3 of a certain purity for subsequent preparation of halide oxide electrolytes. S2, in an argon atmosphere with H2O and O2 both less than 0.01 ppm, LiCl and MCl... m NdCl3 and Nd2O3 obtained from mineral processing are mixed in stoichiometric ratio and ball-milled to obtain a mixed powder. The ball milling speed is 300–1200 rpm, and the ball milling time is 12–50 hours.

[0008] S3, the raw material contains Nd ions or Ce ions, and also contains Li ions, O atoms and halogen (F, Cl, Br, I) atoms. The mixed powder is cold-pressed at 100-600 MPa for 2-5 minutes to obtain the halide oxide electrolyte layer for a solid-state lithium-ion battery.

[0009] In one embodiment, the diameter of the grinding balls in the ball milling process is 5-10 mm; the ball-to-material ratio in the ball milling process is (10-60):1.

[0010] Preferably, the calcination step in S1 is carried out under Ar atmosphere protection by introducing O2 and calcining at 500-1100℃ for 5-12 hours.

[0011] Preferably, the extraction step in S1 uses an extractant including but not limited to 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

[0012] Preferably, the electrochemical window of the halide oxide solid electrolyte is 1–4.5 V, and the ionic conductivity at room temperature is greater than [value missing]. .

[0013] The present invention also discloses an all-solid-state lithium-ion battery, comprising a positive electrode, a negative electrode and an electrolyte; The electrolyte includes the above-mentioned halide oxide solid electrolyte material or the halide oxide solid electrolyte material prepared by the above preparation method.

[0014] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0015] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0016] Figure 1 SEM and EDS images of the halide oxide solid electrolyte electrode material prepared in Example 1 of this invention; Figure 2 The XRD pattern of the ball-milled premixed amorphous precursor powder prepared in Example 1 of this invention; Figure 3 The calcined Li prepared in Example 1 of this invention 2.8 Ti 0.8 Zr 0.2 XRD pattern of Cl6; Figure 4 This is a flowchart of the synthesis of halide oxide solid electrolytes from raw materials extracted from fluorocarbon calcium neodymium ore in Embodiment 2 of the present invention. Detailed Implementation

[0017] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0018] Example 1 A halogen oxide solid electrolyte for use in all-solid-state batteries, the chemical formula of the material is [Li(6-ac-3b) M a Nd b ] 6+ [O y X (6-2y) ] 6- Wherein: M is at least one element selected from Ti, Zr, Hf, V, Nb, and Ta; X is at least one element selected from F, Cl, Br, and I; 0.5 < b < 0.55, 0.4 ≤ a < 0.5, 4 ≤ c ≤ 5 (the value of c is determined by the valence state of element M; when M is Ti, Zr, or Hf, c = 4; when M is V, Nb, or Ta, c = 5; when M is multiple metals, 4 ≤ c ≤ 5), 0 < y ≤ 2. In this halide oxide electrolyte, the NdCl3-type crystal configuration can enhance the lithium-ion channel. The heterovalent doping of elements such as Zr, Ti, Hf, V, Nb, and Ta creates cation vacancies, further expanding the fast lithium-ion transport channel. Neodymium oxide transforms halides in the system into halide oxides, effectively reducing the repulsion of highly electronegative halide ions on lithium ions, improving ionic conductivity, and helping to form an oxide interlayer on the electrode side to improve electrochemical stability.

[0019] In this embodiment, the Li raw material for the halide oxide solid electrolyte is derived from one or more of Li chloride, hydroxide, oxide, or carbonate. The Nd raw material is derived from Nd trichloride or neodymium oxide extracted from fluorocarbonate neodymium ore. The M element (M is at least one of Ti, Zr, Hf, V, Nb, and Ta) originates from a chloride or oxide containing the M element. The above raw materials are ball-milled according to a stoichiometric ratio at a speed of 800 rpm for 32 hours. The diameter of the ball beads used in the ball milling process is 5 mm; the ball-to-material ratio is 30:1. This synthesizes the desired halide oxide solid electrolyte with an ionic conductivity ≥0.73 mS·cm⁻¹.

[0020] The prepared solid electrolyte was then annealed. Figure 1 Here is the XRD pattern of the halide oxide.

[0021] Example 2 A method for preparing a halide oxide solid electrolyte includes the following steps: S1 involves roasting and acid leaching fluorocarbon calcium neodymium ore, followed by multi-stage extraction of the neodymium-containing mother liquor. The neodymium oxalate in the mother liquor is then precipitated, filtered, and calcined to extract Nd2O3 of a certain purity for subsequent preparation of halide oxide electrolytes.

[0022] S2, Nd2O3 prepared in step S1 was ball-milled at 750 rpm for 35 hours using LiCl, ZrCl4, and NdCl3. After ball milling, heat treatment was performed. EIS testing before heat treatment showed... Figure 3The EIS diagram of the treated halide oxide solid electrolyte is as follows: Figure 2 Its ionic conductivity is ≥1.02 mS·cm-1.

[0023] S3, the raw material contains Nd ions or Ce ions, and also contains Li ions, O atoms and halogen atoms. In step S1, the calcination is carried out under Ar protection with dry oxygen introduced, and calcined at 1000°C for 6 hours. In step S1, the acid leaching uses 2 mol / L hydrochloric acid. In step S1, the extraction requires preparing a 30% (v / v) P507 sulfonated kerosene solution, using 3.0 mol / L HCl as the washing acid to obtain a neodymium-loaded organic phase. After extraction, back-extraction is performed using a 3.5 mol / L hydrochloric acid solution. This process is repeated four times to obtain a neodymium-containing acid solution of a certain concentration.

[0024] In step S1, the precipitation and calcination steps involve adding oxalic acid to the final solution obtained from the extraction step, followed by filtration, washing, and drying to obtain neodymium oxalate precipitate. Dry oxygen is then introduced under Ar protection, and the precipitate is calcined at 600°C for 10 hours to obtain the final Nd₂O₃.

[0025] For a detailed flowchart of step S1, please refer to Figure 4 .

[0026] In step S2, the ball milling is performed at a speed of 600 rpm for 40 hours. The diameter of the milling balls used in the ball milling process is 10 mm, and the ball-to-material ratio is 50:1.

[0027] In step S2, the heat treatment is carried out at 150°C for 5 hours in an Ar atmosphere where both oxygen and water are less than 0.01 ppm.

[0028] Example 3 S1 involves processing fluorocarbon calcium neodymium ore through roasting, acid leaching, extraction, precipitation, and calcination to extract Nd2O3 of a certain purity for subsequent preparation of halide oxide electrolytes.

[0029] S2, Nd2O3 prepared in step S1 is ball-milled with LiCl, TaCl5, NdCl3, and then heat-treated. The ionic conductivity of the product is ≥0.48 mS·cm-1.

[0030] S3, the raw material contains Nd ions or Ce ions, and also contains Li ions, O atoms and halogen atoms.

[0031] In step S1, the calcination is carried out under Ar protection by introducing dry oxygen and calcining at 900°C for 6 hours.

[0032] In step S1, the acid leaching uses 3 mol / L hydrochloric acid.

[0033] In step S1, the extraction requires preparing a 30% (v / v) P507 sulfonated kerosene solution, using 3.0 mol / L HCl as the washing acid to obtain a neodymium-loaded organic phase. After extraction, back-extraction is performed using a 3.5 mol / L hydrochloric acid solution. This process is repeated four times to obtain a neodymium-containing acid solution of a certain concentration.

[0034] In step S1, the precipitation and calcination steps involve adding oxalic acid to the final solution obtained from the extraction step, followed by filtration, washing, and drying to obtain neodymium oxalate precipitate. Dry oxygen is then introduced under Ar protection, and the precipitate is calcined at 400°C for 12 hours to obtain the final Nd₂O₃.

[0035] In step S2, the ball milling is performed at a speed of 800 rpm for 35 hours. The diameter of the milling balls is 5 mm, and the ball-to-material ratio is 30:1.

[0036] Example 4 S1 involves processing fluorocarbon calcium neodymium ore through roasting, acid leaching, extraction, precipitation, and calcination to extract Nd2O3 of a certain purity for subsequent preparation of halide oxide electrolytes.

[0037] S2, Nd2O3 prepared in step S1 is ball-milled using LiCl, TiCl4, NbCl5, NdCl3, and then heat-treated to achieve an ionic conductivity ≥0.52 mS·cm. -1 .

[0038] S3, the raw material contains Nd ions or Ce ions, and also contains Li ions, O ions and halide ions.

[0039] In step S1, the calcination is carried out under Ar protection by introducing dry oxygen and calcining at 1100°C for 5.5 hours.

[0040] In step S1, the acid leaching uses 3 mol / L hydrochloric acid.

[0041] In step S1, the extraction requires preparing a 30% (v / v) P507 sulfonated kerosene solution, using 2.5 mol / L HCl as the washing acid to obtain a neodymium-loaded organic phase. After extraction, back-extraction is performed using a 3.5 mol / L hydrochloric acid solution. This process is repeated four times to obtain a neodymium-containing acid solution of a certain concentration.

[0042] In step S1, the precipitation and calcination steps involve adding oxalic acid to the final solution obtained from the extraction step, followed by filtration, washing, and drying to obtain neodymium oxalate precipitate. Dry oxygen is then introduced under Ar protection, and the precipitate is calcined at 550°C for 8 hours to obtain the final Nd₂O₃.

[0043] In step S2, the ball milling is performed at a speed of 550 rpm for 50 hours. The diameter of the milling balls is 5 mm, and the ball-to-material ratio is 50:1.

[0044] The obtained neodymium oxide active component halide oxide solid electrolyte electrode material powder, commercial lithium iron phosphate (LiFePO4), and conductive carbon (VGCF) were mixed in a ratio of 45:45:10 to obtain an active component composite cathode material. A Li-In alloy was matched as the anode, and LPSC was used as the interphase layer to assemble a full cell for testing. During the assembly of the full cell, the pressure of the halide oxide solid electrolyte sheet was 350 MPa, and the holding time was 4 minutes.

[0045] Table 1 below shows the ionic conductivity of the synthesized halide oxide solid electrolytes obtained in steps (S1, S2, S3) and Examples 1, 2, 3, and 4, as well as the capacity retention and initial capacity of all-solid-state lithium-ion batteries prepared with commercial ternary cathode materials and lithium-indium alloys after 100 cycles of constant current charge-discharge cycling at a rate of 0.2C within a voltage window of 2.2-3.7V. As can be seen from the table, the electrochemical performance of the halide oxide electrolytes prepared in Examples 1, 2, 3, and 4 is significantly improved compared with that of traditional halide electrolytes (commercial Li3InCl6).

[0046] Table 1 Electrochemical properties of the prepared materials (voltage range 2.2-3.7V)

[0047] The above description only illustrates certain exemplary embodiments of the present invention. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention.

Claims

1. A halide oxide solid electrolyte material, characterized in that, The chemical formula of the material is [Li (6-ac-3b) M a Nd b ] 6+ [O y X (6-2y) ] 6- Where: M is at least one element selected from Ti, Zr, Hf, V, Nb, and Ta; X is at least one element selected from F, Cl, Br, and I; 0 < b ≤ 2, 0 ≤ a < 0.75, 4 ≤ c ≤ 5, and 0 < y ≤ 2, where the value of c is determined by the valence state of element M. When M is Ti, Zr, or Hf, c = 4; when M is V, Nb, or Ta, c = 5; and when M is multiple metals, 4 ≤ c ≤ 5.

2. The halide oxide solid electrolyte material according to claim 1, characterized in that, The chemical formula of the halide oxide solid electrolyte is [Li (6-ac-3b) M a Nd b ] 6+ [O y X (6-2y) ] 6- Where: M is at least one element selected from Ti, Zr, Hf, V, Nb, and Ta; X is at least one element selected from F, Cl, Br, and I; 0.4 < b < 0.8, 0.3 ≤ a ≤ 0.6 (which conflicts with claim 1), 4 ≤ c ≤ 5, where the value of c is determined by the valence state of element M. When M is Ti, Zr, or Hf, c = 4; when M is V, Nb, or Ta, c = 5. When M is multiple metals, 4 ≤ c ≤ 5, and 0.1 < y ≤ 0.

4.

3. A method for preparing a halide oxide solid electrolyte material as described in any one of claims 1-2, characterized in that, The specific steps include: in an argon atmosphere where both H2O and O2 are less than 0.01 ppm, adding LiCl and MCl... m (where M is at least one element selected from Ti, Zr, Hf, V, Nb, and Ta), NdCl3 and Nd2O3 obtained from mineral processing are mixed in stoichiometric ratio and ball-milled to obtain a mixed powder; the mixed powder is then cold-pressed into sheets to obtain the halide oxide solid electrolyte material.

4. The preparation method according to claim 3, characterized in that, The mineral is one or more of fluorocarbonate-calcium neodymium ore, fluorocarbonate-calcium cerium ore, and fluorocarbonate-cerium ore. It is processed by roasting, acid leaching, extraction, precipitation, and calcination steps to extract Nd2O3 with a purity ≥98%.

5. The preparation method according to claim 3, characterized in that, The ball milling process is performed at a speed of 300–1200 rpm for 12–50 hours.

6. The preparation method according to claim 5, characterized in that, The ball milling process is performed at a speed of 600–900 rpm for 30–40 hours.

7. The preparation method according to claim 3, characterized in that, The diameter of the grinding balls in the ball milling process is 5-10 mm; the ball-to-material ratio in the ball milling process is (10-60):

1.

8. The preparation method according to claim 7, characterized in that, The diameter of the grinding balls in the ball milling process is 8 mm; the ball-to-material ratio in the ball milling process is (30-40):

1.

9. The preparation method according to claim 3, characterized in that, The pressure of the cold-pressed sheet is 100-600 MPa, and the holding time is 2-5 minutes.

10. A fully solid-state lithium-ion battery, characterized in that, Includes positive electrode, negative electrode, and electrolyte; The electrolyte includes the halide oxide solid electrolyte material according to any one of claims 1-2 or the halide oxide solid electrolyte material prepared by any one of the preparation methods according to claims 3-9.

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