A tantalum-oxygen co-doped aluminum-based oxyhalide solid-state electrolyte, a preparation method and applications thereof

Abstract

The application provides a tantalum-oxygen co-doped aluminum-based oxyhalide solid electrolyte and a preparation method and application thereof, and belongs to the technical field of solid electrolytes. 5+ ) and oxygen (O 2‑ ) are introduced for co-doping, an amorphous structure containing Ta-O strong bonds is formed through low-temperature calcination, lithium ion migration barriers are significantly reduced, and conductivity and structural stability are improved. The application uses a crystalline hydrate (AlCl3.6H2O) as an in-situ oxygen source and a low-temperature two-step annealing process, utilizes "in-situ active oxygen" generated by the thermal decomposition of crystalline water to participate in the reaction, realizes uniform doping of oxygen at the molecular / atomic level, and avoids the generation of heterogeneous phases caused by local oxygen enrichment or oxygen deficiency. Through the introduction of the Ta-O strong chemical bond, compared with the weak Al-Cl bond, the Ta-O bond has higher bond energy and oxidation stability, and the resistance of the solid electrolyte to high voltage is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte technology, specifically to a tantalum-oxygen co-doped aluminum-based halide oxide solid electrolyte, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries, as crucial energy storage devices, are widely used in electric vehicles and large-scale energy storage. While currently dominant, their traditional organic liquid electrolytes are flammable and have a limited electrochemical window, posing significant safety risks and limiting further improvements in energy density. Therefore, all-solid-state batteries are considered one of the most promising disruptive technologies. Their core principle is to replace liquid electrolytes with solid electrolytes, fundamentally solving safety issues and potentially achieving compatibility with lithium metal anodes and high-voltage cathodes, thus enabling further increases in energy density.

[0003] However, the development of all-solid-state batteries is fundamentally limited by the inherent limitations of solid-state electrolytes—the trade-off between conductivity and stability. Sulfide electrolytes exhibit extremely high ionic conductivity, but their electrochemical window is narrow and they are extremely sensitive to humidity, leading to a series of problems such as increased processing costs and reduced safety performance. Oxide electrolytes have excellent stability, but they usually require high-temperature sintering, and the huge grain boundary resistance leads to a decrease in ionic conductivity.

[0004] Recently emerging halide electrolytes have achieved a balance between good ionic conductivity and excellent electrochemical stability, but their compatibility with lithium metal anodes remains unsatisfactory, and their ion transport capabilities lag behind sulfides. For example, LiAlCl4 exhibits high oxidative stability, cost-effectiveness, and mechanical deformability, making it a promising candidate for solid-state electrolytes (SSEs). However, the application of LiAlCl4 as an SSE is hindered by its low ionic conductivity at room temperature. Therefore, developing a solid-state electrolyte material that combines sulfide-level ionic conductivity with oxide-level stability is crucial for the development of all-solid-state batteries. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a tantalum-oxygen co-doped aluminum-based halide oxide solid electrolyte, its preparation method, and its application. The tantalum-oxygen co-doped aluminum-based halide oxide solid electrolyte provided by this invention has high ionic conductivity, electrochemical window, and oxidation stability.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a tantalum-oxygen co-doped aluminum-based halide oxide solid electrolyte, the raw materials for which include LiCl, AlCl3, TaCl5 and AlCl3·6H2O, wherein the molar ratio of LiCl, AlCl3, TaCl5 and AlCl3·6H2O is A:(Bx):x:1, where A=8~12, B=5~10 and x=0.05~5.0.

[0007] Preferably, the molar ratio of LiCl, AlCl3, TaCl5 and AlCl3·6H2O is 9:(8-x):x:1, where x=0.05~5.0.

[0008] Preferably, the room temperature ionic conductivity of the tantalum-oxygen co-doped aluminum halide oxide solid electrolyte is ≥1.0 mS / cm.

[0009] This invention provides a method for preparing the above-mentioned tantalum-oxygen co-doped aluminum-based halide oxide solid electrolyte, comprising the following steps: Under an inert atmosphere, LiCl, AlCl3, TaCl5 and AlCl3·6H2O were mixed and annealed in a two-step process to obtain a tantalum-oxygen co-doped aluminum halide oxide solid electrolyte.

[0010] Preferably, the mixing is ball milling, and the ball milling rate is 100 rpm for 5 to 10 minutes.

[0011] Preferably, the mixing is a grinding mixture, and the grinding time is 5-6 minutes.

[0012] Preferably, the inert atmosphere is an argon atmosphere.

[0013] Preferably, the two-step annealing includes a first-stage annealing and a second-stage annealing, wherein the temperature of the first-stage annealing is 80~160℃ and the holding time is 0.5~5h; The second stage of annealing is performed at a temperature of 160~300℃ and a holding time of 1~10h.

[0014] This invention provides the application of the above-mentioned tantalum-oxygen co-doped aluminum halide oxide solid electrolyte in all-solid-state batteries.

[0015] The present invention provides an all-solid-state lithium-ion battery comprising the above-mentioned tantalum-oxygen co-doped aluminum halide oxide solid electrolyte.

[0016] This invention provides a tantalum-oxygen co-doped aluminum-based halide oxide solid electrolyte. The raw materials include LiCl, AlCl3, TaCl5, and AlCl3·6H2O, wherein the molar ratio of LiCl, AlCl3, TaCl5, and AlCl3·6H2O is A:(Bx):x:1, where A = 8~12, B = 5~10, and x = 0.05~5.0. This invention dops high-valence Ta in the aluminum-based halide oxide solid electrolyte. 5+ High price Ta 5+ Replace part of Al 3+ This process introduces lithium vacancies or alters charge distribution in the crystal lattice, increasing carrier concentration. XRD confirms that the tantalum-oxygen co-doped aluminum halide oxide solid electrolyte of this invention has an amorphous structure, eliminating grain boundary resistance and providing isotropic lithium-ion transport channels, thereby achieving a significant improvement in ionic conductivity. Furthermore, this invention uses crystalline hydrate (AlCl3·6H2O) as an in-situ oxygen source and a low-temperature two-step annealing process (120℃+190℃), utilizing the "in-situ active oxygen" generated by the thermal decomposition of crystal water to participate in the reaction. Compared to the traditional solid-state method of directly mixing oxide powders (such as Ta2O5 or Li2O), this invention achieves uniform oxygen doping at the molecular / atomic level, avoiding impurities caused by localized oxygen enrichment or depletion. Moreover, the solid electrolyte of this invention exhibits good stability against metallic lithium, and the oxidation decomposition potential (electrochemical window) can reach approximately 4.2V (vs. Li / Li). + This allows it to be adapted to high-voltage cathode materials (such as high-nickel ternary materials). This effect stems from the introduction of strong Ta-O chemical bonds, which have higher bond energy and oxidation stability compared to the weaker Al-Cl bonds. Under high voltage, the polyanionic framework containing Ta-O bonds is less prone to losing electrons and being oxidized, thus significantly improving the material's tolerance to high voltage.

[0017] Compared to existing aluminum-based halide electrolytes or simple oxygen-doped electrolytes, the core advantage of this invention is a significantly improved room-temperature ionic conductivity. The room-temperature ionic conductivity of the tantalum-oxygen co-doped aluminum-based halide oxide solid electrolyte of this invention can reach above 1.5 mS / cm, which is significantly better than that of undoped LiAlCl4 electrolytes (typically around 10 mS / cm). -4 The solid electrolyte of this invention has a simple and low energy consumption synthesis process, produces products with uniform chemical composition and good batch stability, and the preparation process does not require high-temperature sintering (usually oxides require ≥700℃), which greatly reduces energy consumption and production costs, and is easy to realize industrial mass production. Attached Figure Description

[0018] Figure 1 The XRD results are for the synthesis of halide solid electrolytes by gradient doping of Ta and O in Examples 1-8 and Comparative Example 1. Figure 2 Impedance diagrams and ionic conductivity comparison diagrams of halide solid electrolytes synthesized by gradient doping of Ta and O in Examples 1-8 and Comparative Example 1; Figure 3 LSV results for the halide solid electrolyte LATOC-6; Figure 4 XPS results for the halide solid electrolytes LATOC-6 and LAOC; Figure 5 The rate performance diagram for the halide solid electrolyte LATOC-6 is shown. Figure 6 The graph shows the long-cycle performance of the halide solid electrolyte LATOC-6. Figure 7 This is a graph showing the long-cycle performance of the halide solid electrolyte LAOC. Detailed Implementation

[0019] This invention provides a tantalum-oxygen co-doped aluminum-based halide oxide solid electrolyte, the raw materials for which include LiCl, AlCl3, TaCl5 and AlCl3·6H2O, wherein the molar ratio of LiCl, AlCl3, TaCl5 and AlCl3·6H2O is A:(Bx):x:1, wherein A=8~12, preferably 9~10; B=5~10, preferably 6~8; and x=0.05~5.0, preferably 1.0~4.0, more preferably 3.0~4.0.

[0020] In this invention, the molar ratio of LiCl, AlCl3, TaCl5 and AlCl3·6H2O is preferably 9:(8-x):x:1, where x = 0.05~5.0, preferably 1.0~4.0, and more preferably 3.0~4.0.

[0021] In this invention, the room temperature ionic conductivity of the tantalum-oxygen co-doped aluminum halide oxide solid electrolyte is preferably ≥1.0 mS / cm.

[0022] This invention provides a method for preparing the above-mentioned tantalum-oxygen co-doped aluminum-based halide oxide solid electrolyte, comprising the following steps: Under an inert atmosphere, LiCl, AlCl3, TaCl5 and AlCl3·6H2O were mixed and annealed in a two-step process to obtain a tantalum-oxygen co-doped aluminum halide oxide solid electrolyte.

[0023] In this invention, the inert atmosphere is an argon atmosphere; in this invention, the mixing is preferably ball milling, the ball milling rate is preferably 100 rpm, and the time is preferably 5 to 10 min, more preferably 6 to 8 min.

[0024] Alternatively, the mixing is preferably a grinding mixture, and the grinding time is preferably 5 to 6 minutes.

[0025] In this invention, the two-step annealing is preferably carried out in a closed container, and the atmosphere is preferably an inert atmosphere. The two-step annealing includes a first-stage annealing and a second-stage annealing. The temperature of the first-stage annealing is preferably 80~160℃, more preferably 100~120℃, and the holding time is preferably 0.5~5h, more preferably 2~4h. The heating rate to the first-stage annealing is preferably 3℃ / min. This invention uses the first-stage annealing to perform a dehydration pre-reaction. Specifically, at the beginning of heating, the powder begins to "sweat," releasing adsorbed water. Around 100℃, the powder begins to "bubble" violently. Due to Al... 3+ With its extremely strong polarization ability, the water of crystallization undergoes a hydrolysis reaction. The OH bonds in the water molecules break, leaving O to combine with Al, while H steals the neighboring Cl to form HCl gas, which escapes and releases a pungent HCl gas. Meanwhile, the oxygen atoms are forced to remain in the aluminum lattice.

[0026] In this invention, the preferred temperature for the second-stage annealing is 160-300℃, more preferably 190-240℃, and the preferred holding time is 1-10h, more preferably 3-6h; the preferred heating rate to the second-stage annealing is 3℃ / min. Through the second-stage annealing, a melting reaction occurs. At approximately 180℃, bubbles decrease, the powder becomes viscous and moist, and some areas begin to melt. At this point, Ta and Al atoms meet in the melt and successfully bond through the previously remaining oxygen atoms, forming a Ta-O-Al connection. After the second-stage annealing, this invention preferably allows the furnace to cool naturally to room temperature (25℃). This invention preferably grinds and pulverizes the resulting product to obtain a powdered tantalum-oxygen co-doped aluminum halide oxide solid electrolyte.

[0027] This invention introduces high-priced tantalum (Ta) 5+ ) and oxygen (O 2- Co-doping is performed, and an amorphous structure containing strong Ta-O bonds is formed by low-temperature calcination, which significantly reduces the lithium-ion migration barrier and improves conductivity and structural stability.

[0028] This invention provides the application of tantalum-oxygen co-doped aluminum halide oxide solid electrolyte in all-solid-state batteries.

[0029] This invention provides an all-solid-state lithium-ion battery, comprising the aforementioned tantalum-oxygen co-doped aluminum-based halide oxide solid electrolyte, and preferably further comprising a positive electrode, a negative electrode, and a stabilizing layer. In this invention, the positive electrode is preferably lithium cobalt oxide or a ternary material, wherein the lithium cobalt oxide is preferably LCO, and the ternary material is preferably NCM9055 and / or NCM811; in this invention, the material of the stabilizing layer is preferably Li6PS5Cl, and the particle size is preferably 5~30 μm.

[0030] The following detailed description, in conjunction with embodiments, illustrates the tantalum-oxygen co-doped aluminum halide oxide solid electrolyte, its preparation method, and its applications. However, these descriptions should not be construed as limiting the scope of protection of this invention.

[0031] The reagents and instruments used in the following examples are shown in Table 1.

[0032] Table 1. Reagents and Instruments Used

[0033] Example 1 Anhydrous LiCl, AlCl3, TaCl5, and AlCl3·6H2O were weighed and mixed evenly in a molar ratio of 9:7.1:0.9:1. The mixed material was placed in a sealed alumina crucible and annealed at low temperature in a tube furnace under an Ar atmosphere. The annealing was first carried out at 120℃ for 2 hours and then at 190℃ for 3 hours to obtain a tantalum-oxygen co-doped aluminum halide oxide solid electrolyte, designated LATOC-1.

[0034] Example 2 Anhydrous LiCl, AlCl3, TaCl5, and AlCl3·6H2O were weighed and mixed evenly in a molar ratio of 9:6.2:1.8:1. The mixed material was placed in a sealed alumina crucible and annealed at low temperature in a tube furnace under an Ar atmosphere. The annealing was first carried out at 120℃ for 2 hours and then at 190℃ for 3 hours to obtain a tantalum-oxygen co-doped aluminum halide oxide solid electrolyte, designated LATOC-2.

[0035] Example 3 Anhydrous LiCl, AlCl3, TaCl5, and AlCl3·6H2O were weighed and mixed evenly in a molar ratio of 9:5.75:2.25:1. The mixed material was placed in a sealed alumina crucible and annealed at low temperature in a tube furnace under an Ar atmosphere. The annealing was first carried out at 120℃ for 2 hours and then at 190℃ for 3 hours to obtain a tantalum-oxygen co-doped aluminum halide oxide solid electrolyte, designated LATOC-3.

[0036] Example 4 Anhydrous LiCl, AlCl3, TaCl5, and AlCl3·6H2O were weighed and mixed evenly in a molar ratio of 9:5.3:2.7:1. The mixed material was placed in a sealed alumina crucible and annealed at low temperature in a tube furnace under an Ar atmosphere. The annealing was first carried out at 120℃ for 2 hours and then at 190℃ for 3 hours to obtain a tantalum-oxygen co-doped aluminum halide oxide solid electrolyte, designated LATOC-4.

[0037] Example 5 Anhydrous LiCl, AlCl3, TaCl5, and AlCl3·6H2O were weighed and mixed evenly in a molar ratio of 9:4.85:3.15:1. The mixed material was placed in a sealed alumina crucible and annealed at low temperature in a tube furnace under an Ar atmosphere. The annealing was first carried out at 120℃ for 2 hours and then at 190℃ for 3 hours to obtain a tantalum-oxygen co-doped aluminum halide oxide solid electrolyte, designated LATOC-5.

[0038] Example 6 Anhydrous LiCl, AlCl3, TaCl5, and AlCl3·6H2O were weighed and mixed evenly in a molar ratio of 9:4.4:3.6:1. The mixed material was placed in a sealed alumina crucible and annealed at low temperature in a tube furnace under an Ar atmosphere. The annealing was first carried out at 120℃ for 2 hours and then at 190℃ for 3 hours to obtain a tantalum-oxygen co-doped aluminum halide oxide solid electrolyte, designated LATOC-6.

[0039] Example 7 Anhydrous LiCl, AlCl3, TaCl5, and AlCl3·6H2O were weighed and mixed evenly in a molar ratio of 9:3.5:4.51. The mixed material was placed in a sealed alumina crucible and annealed at low temperature in a tube furnace under an Ar atmosphere. The annealing was first carried out at 120℃ for 2 hours and then at 190℃ for 3 hours to obtain a tantalum-oxygen co-doped aluminum halide oxide solid electrolyte, designated LATOC-7.

[0040] Example 8 Anhydrous LiCl, AlCl3, TaCl5, and AlCl3·6H2O were weighed and mixed evenly in a molar ratio of 9:2.6:5.4:1. The mixed material was placed in a sealed alumina crucible and annealed at low temperature in a tube furnace under an Ar atmosphere. The annealing was first carried out at 120℃ for 2 hours and then at 190℃ for 3 hours to obtain a tantalum-oxygen co-doped aluminum halide oxide solid electrolyte, designated LATOC-8.

[0041] Comparative Example 1 Anhydrous LiCl, AlCl3, and AlCl3·6H2O were weighed and mixed evenly in a molar ratio of 9:8:1. The mixed material was placed in a sealed alumina crucible and annealed at low temperature in a tube furnace under an Ar atmosphere. The annealing was first carried out at 120℃ for 2 hours and then at 190℃ for 3 hours to obtain a halide oxide electrolyte doped only with O element, which was designated as LAOC.

[0042] Structural characterization and performance testing (1) The XRD results of halide solid electrolytes synthesized by gradient doping of Ta and O in Examples 1-8 and Comparative Example 1 are as follows: Figure 1 As shown, with increasing Ta doping (from LAOC to LATOC-6), the sharp diffraction peaks (corresponding to the LiCl crystal phase) gradually weaken, replaced by broadened amorphous halo peaks around 15°~35° and 40°~50°. LATOC-6 appears to have the highest degree of amorphization. However, at LATOC-8, sharp diffraction peaks reappear (due to recrystallization or impurity phase precipitation), indicating that there is a threshold for doping; excessive Ta will disrupt the amorphous network or lead to phase separation.

[0043] (2) Impedance diagrams and ionic conductivity comparison diagrams of halide solid electrolytes synthesized by gradient doping of Ta and O in Examples 1-8 and Comparative Example 1 are shown below. Figure 2 As shown. Figure 2 The conductivity of the undoped (LAOC) electrolyte is only 0.23 mS / cm. LATOC-6 reaches a peak of 1.7 mS / cm, an increase of nearly 7.4 times compared to the starting point. LATOC-8 drops sharply back to 0.23 mS / cm, which is consistent with the XRD results of the halide solid electrolyte synthesized by gradient doping with Ta and O mentioned above.

[0044] (3) The LSV results of the halide solid electrolyte LATOC-6 are as follows: Figure 3 As shown in Figure 3, the electrochemical window of this electrolyte material can reach approximately 4.2V.

[0045] (4) XPS results of halide solid electrolytes LATOC-6 and LAOC are as follows: Figure 4 As shown, X-ray photoelectron spectroscopy analysis revealed that the binding energy of Ta in the material of this invention is between Ta-Cl and Ta-O, and the broadening of the Al 2p peak confirmed the modification of the aluminum coordination environment by oxygen. This special multiple coordination ring is the key to achieving high lithium-ion mobility.

[0046] (5) Rate performance graph of LATOC-6 halide solid electrolyte is shown in Figure 1. Figure 5 As shown, the rate performance test conditions are: rate testing at 35℃ from 0.2°C to 5°C, conducted by... Figure 5 It can be seen that the capacity performance was not lost after the rate test, and the capacity at 0.5 C is still about 175mAh / g.

[0047] Application Example 1 An all-solid-state battery was constructed. The battery consists of a composite positive electrode (NCM9055:LATOC-6:CNT=70:30:1), a halide solid electrolyte layer (LATOC-6), a stabilizing layer (Li6PS5Cl), and a negative electrode with a thickness of 100 μm (Li-In alloy negative electrode).

[0048] The long-cycle performance of the halide solid electrolyte LATOC-6 is shown in the figure below. Figure 6 As shown, the battery assembled with this electrolyte retains 94.4% of its capacity after 250 cycles at 1 C, and its charge specific capacity remains at 148 mAh / g.

[0049] The long-cycle performance of halide solid electrolyte LAOC is shown in the figure below. Figure 7 As shown in the figure, the battery assembled with this electrolyte retains 93.55% of its capacity after 177 cycles at 1 C, and its charge specific capacity remains at around 105 mAh / g.

[0050] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A tantalum-oxygen co-doped aluminum-based halide oxide solid electrolyte, characterized in that, The raw materials for preparation include LiCl, AlCl3, TaCl5 and AlCl3·6H2O, wherein the molar ratio of LiCl, AlCl3, TaCl5 and AlCl3·6H2O is 9:(8-x):x:1, and x=0.05~5.0; The preparation method of the tantalum-oxygen co-doped aluminum-based halide oxide solid electrolyte includes the following steps: Under an inert atmosphere, LiCl, AlCl3, TaCl5 and AlCl3·6H2O were mixed and annealed in a two-step process to obtain a tantalum-oxygen co-doped aluminum halide oxide solid electrolyte. The two-step annealing method includes a first-stage annealing and a second-stage annealing. The temperature of the first-stage annealing is 80~160℃, and the holding time is 0.5~5h. The second stage of annealing is performed at a temperature of 160~300℃ and a holding time of 1~10h.

2. The tantalum-oxygen co-doped aluminum-based halide oxide solid electrolyte according to claim 1, characterized in that, The room temperature ionic conductivity of the tantalum-oxygen co-doped aluminum halide oxide solid electrolyte is ≥1.0 mS / cm.

3. The method for preparing the tantalum-oxygen co-doped aluminum-based halide oxide solid electrolyte according to claim 1 or 2, characterized in that, Includes the following steps: Under an inert atmosphere, LiCl, AlCl3, TaCl5 and AlCl3·6H2O were mixed and annealed in a two-step process to obtain a tantalum-oxygen co-doped aluminum halide oxide solid electrolyte. The two-step annealing method includes a first-stage annealing and a second-stage annealing. The temperature of the first-stage annealing is 80~160℃, and the holding time is 0.5~5h. The second stage of annealing is performed at a temperature of 160~300℃ and a holding time of 1~10h.

4. The preparation method according to claim 3, characterized in that, The mixing is ball milling, with a mixing rate of 100 rpm and a mixing time of 5-10 min.

5. The preparation method according to claim 3, characterized in that, The mixing is a grinding mixture, and the grinding time is 5-6 minutes.

6. The preparation method according to claim 3, characterized in that, The inert atmosphere is an argon atmosphere.

7. The application of the tantalum oxide co-doped aluminum halide oxide solid electrolyte according to claim 1 or 2, or the tantalum oxide co-doped aluminum halide oxide solid electrolyte prepared by any one of claims 3 to 6, in all-solid-state batteries.

8. A fully solid-state lithium-ion battery, characterized in that, Includes the tantalum-oxygen co-doped aluminum halide oxide solid electrolyte as described in claim 1 or 2, or the tantalum-oxygen co-doped aluminum halide oxide solid electrolyte prepared by the preparation method described in any one of claims 3 to 6.

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