A preparation method of an inorganic solid-state electrolyte with a pre-constructed ion rapid transmission interface through in-situ heat treatment
By forming an amorphous phase through element diffusion at the oxide/sulfide interface, the problem of poor interfacial contact in the prior art is solved, achieving efficient lithium-ion transport and improving the electrochemical performance of all-solid-state batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2026-05-09
- Publication Date
- 2026-07-10
AI Technical Summary
In existing oxide/sulfide composite solid electrolyte materials, the interfacial contact is poor, and the migration of lithium ions between different crystal structures is hindered, resulting in poor ionic conductivity. Existing preparation methods cannot effectively utilize the advantages of composite materials, resulting in high interfacial impedance and discontinuous lithium ion transport paths.
Using LLZO and LGPS with a particle size of 1-10μm as raw materials, the mixture is dry-mixed and ball-milled in an inert atmosphere, then cold-pressed in a sealed state, and then hot-pressed and sintered in an inert atmosphere. The hot-pressing parameters are controlled to achieve element diffusion at the oxide/sulfide interface, form an amorphous phase, optimize the interface structure, and promote lithium-ion transport.
The room temperature ionic conductivity of the composite solid electrolyte was significantly improved, the lithium-ion transport energy barrier was lowered, a continuous lithium-ion fast transport channel was formed, and the electrochemical performance was enhanced.
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Figure CN122370481A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of all-solid-state lithium batteries, specifically, it relates to a method for preparing an inorganic solid electrolyte by pre-constructing an ion fast transport interface through in-situ heat treatment. Background Technology
[0002] All-solid-state lithium batteries are the ideal next-generation energy storage devices, but the core solid electrolyte materials face practical bottlenecks: sulfide systems have high ionic conductivity but insufficient stability, while oxide systems have good stability but are limited by low ionic conductivity and huge interfacial impedance.
[0003] To combine the advantages of both types of materials, researchers have proposed a strategy to construct oxide / sulfide composite solid electrolytes. Initially, the composite method was mostly a simple physical mixing, where oxide and sulfide powders were cold-pressed or sintered at low temperatures to form a bulk mass. However, this method has fundamental drawbacks. First, the cold-pressing process relies solely on mechanical force to bring the particles into contact, lacking sufficient energy to drive effective physicochemical interactions between the oxide and sulfide interfaces. The resulting physical interface is weak, with extremely high interfacial impedance. The lithium-ion transport pathway within the composite electrolyte still primarily depends on the sulfide matrix, with the oxide particles largely acting as inert fillers. This can even degrade performance by blocking continuous conductive pathways within the sulfide, severely hindering lithium-ion transport. Second, while low-temperature sintering can promote partial bonding between the oxide and sulfide electrolytes, the processing temperature and time are extremely limited to prevent decomposition or harmful phase transitions of the sulfide electrolyte at high temperatures (typically >500°C), leading to insufficient interfacial fusion.
[0004] In the field of sulfide solid electrolytes, various improvement schemes have been proposed in the existing technology, but each still has its own limitations. CN202211054909.6 discloses a method for treating sulfide electrolytes using CO2 adsorption, which inhibits their reaction with water by generating sulfur-carbon bonds or a sulfur-carbon adsorption layer. However, this method depends on the integrity of the surface adsorption layer, which is easily damaged under mechanical pressure or long-term use, leading to the re-exposure of internal active sulfides and a decrease in stability. CN202310451917.2 introduces Bi into the Li4SnS4 system. 3+ Doping is used to improve air stability, but the ionic conductivity after simple cation doping modification is only 1.35 × 10⁻⁶. -3 S / cm, with limited performance improvement. Regarding oxide solid electrolytes, to improve their ionic conductivity, CN202111063606.6 describes the preparation of Li using magnetron sputtering. x La y TiO3 thin films were rapidly annealed, but the ionic conductivity of the electrolyte obtained by this method was only 10. -7 ~10-4 The low intrinsic conductivity of oxide electrolytes (S / cm) is due to high equipment requirements, slow deposition rates, and low production capacity, making it difficult to meet the needs of large-scale applications. CN202411255522.6 reduces grain boundary impedance by coating the surface of oxide electrolyte sheets with lithium aluminate, but this approach cannot fundamentally improve the problem of low intrinsic conductivity of oxide electrolytes, and requires high-temperature sintering and multi-step liquid phase deposition, resulting in a complex and energy-intensive manufacturing process.
[0005] In the field of composite electrolytes, CN202510912007.9 proposes a process for preparing oxide / sulfide composite solid-state batteries using mechanical ball milling combined with hot pressing. The process involves mechanically ball milling the raw materials to obtain a sulfide solid electrolyte precursor at a milling speed of 500-800 rpm for 4-12 hours. This precursor is then ball-milled with oxide raw materials and synergists, followed by hot pressing to obtain the composite solid-state electrolyte at a mass ratio of 30-50:10:5-10. The hot pressing reaction temperature is 73-85℃, and the reaction time is 60-100 minutes. This method uses relatively long milling speeds and times, involves the preparation of the sulfide precursor and subsequent hot pressing, and involves many parameter variations, making the preparation process quite complex. Furthermore, while this method uses a high proportion of sulfides, the conductivity does not exhibit ideal performance; even if a high conductivity is achieved, it may be due to the sulfide itself. In addition, the organic synergists introduced in this scheme are prone to decomposition and gas generation at high temperatures or during long-term electrochemical cycling, which contradicts the requirement of all-solid-state batteries for the stability of inorganic systems and introduces new side reaction risks.
[0006] Therefore, the oxide / sulfide composite solid electrolytes prepared by existing technologies have highly ordered and high-resistivity internal interfaces, failing to fully utilize the potential advantages brought by the composite process. How to achieve atomic / ionic scale structural control at the oxide-sulfide interface through effective processing methods, reduce the interface energy barrier, and construct a continuous and efficient lithium-ion fast transport channel has become a key scientific and technological problem urgently needing to be solved in this field.
[0007] In summary, developing a preparation method that can actively regulate and optimize the oxide / sulfide interface is crucial for significantly improving the overall electrochemical performance of composite solid electrolytes and promoting their application in high-performance all-solid-state batteries. Summary of the Invention
[0008] This invention aims to solve the technical problem of poor interfacial contact and hindered lithium ion migration between different crystal structures in existing oxide / sulfide composite solid electrolyte materials, resulting in poor ionic conductivity. It provides an inorganic solid electrolyte preparation method that pre-constructs a rapid ion transport interface through in-situ heat treatment.
[0009] To address the problems existing in solid electrolyte materials, this invention selects LLZO (Li7La3Zr2O) with a particle size of 1-10 μm. 12 ), and LGPS (Li) with a particle size range of 1-10 μm. 10 GeP2S 12 Using this as a raw material, a hot-pressing method for composite solid electrolyte materials is proposed. This hot-pressing method can achieve different degrees of element diffusion at the oxide / sulfide phase interface, regulate the formation of the amorphous phase at the interface, thereby improving the interface structure and promoting lithium-ion transport, and ultimately effectively improving the electrochemical performance of the composite solid electrolyte material.
[0010] To address the aforementioned technical problems, the present invention adopts the following technical solution: The purpose of this invention is to provide a method for preparing inorganic solid electrolytes by pre-constructing a rapid ion transport interface through in-situ heat treatment, characterized by comprising the following steps: Step 1: Under an inert atmosphere, LLZO (Li7La3Zr2O) with a particle size of 1~10 μm is... 12 ) and LGPS (Li) with a particle size of 1~10 μm 10 GeP2S 12 The mixture is then dry-mixed and ball-milled under sealed conditions. Step 2: Then, it is placed into a mold, cold-pressed and sintered under an inert atmosphere. After sintering, it is cooled to room temperature in the furnace to obtain the inorganic solid electrolyte.
[0011] Further specifying, in step 1, the mass ratio of LLZO to LGPS is 1:1.
[0012] Further specifying, in step 1, the ball mill speed is 200~400 rpm.
[0013] To further specify, in step 1, the ball-to-material ratio is 10:1.
[0014] Further specifying, in step 1, the grinding balls are zirconia grinding balls with diameters of 5 mm and 10 mm, and the volume ratio of the two types of grinding balls is 1:1.
[0015] Further specifying, in step 2, cold pressing is performed under a pressure of 200~500 MPa.
[0016] Further specifying step 2, hot pressing sintering: the temperature is programmed to rise to 250℃~370℃ at a rate of 2~5℃ / min, held for 2~9 h, and a pressure of 200~500 MPa is continuously applied.
[0017] To further specify, in steps 1 and 2, the inert atmosphere is argon.
[0018] Further specifying, in step 2, the cooling rate is 1~5 ℃ / min.
[0019] Another object of the present invention is to provide an inorganic solid electrolyte prepared by any of the above methods.
[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention addresses the problems of traditional cold pressing failing to form effective physicochemical interactions at the composite electrolyte interface, and insufficient interfacial fusion due to limited low-temperature sintering temperature and time, resulting in low room-temperature ionic conductivity caused by hindered lithium-ion migration at different interfaces. It utilizes LLZO (Li7La3Zr2O) with a particle size of 1-10 μm. 12 ) and LGPS (Li) with a particle size of 1-10 μm 10 GeP2S 12 Using the same raw material as the composite solid electrolyte, a method is proposed to process the mixed ball-milled electrolyte powder into a sleeve mold by hot pressing to obtain a composite solid electrolyte with a controllable amorphous interface phase. This method aims to reduce the lithium-ion transport energy barrier and improve the room temperature ionic conductivity of the composite solid electrolyte, thereby solving a series of problems existing in the composite solid electrolyte as an important component of solid-state batteries.
[0021] For a deeper understanding of the features and technical content of this invention, please refer to the accompanying detailed description and drawings. It should be noted that the drawings are provided for illustrative purposes only and are not intended to limit the scope of the invention. Attached Figure Description
[0022] Figure 1 The image shows the morphology of the composite solid electrolyte surface obtained in Example 1. Figure 2 XRD patterns and magnified views of composite solid electrolytes prepared at different hot-pressing temperatures; Figure 3 Raman plots of composite solid electrolytes prepared at different hot-pressing temperatures; Figure 4 XPS images of composite solid electrolytes prepared at different hot-pressing temperatures; Figure 5 TEM images of composite solid electrolytes prepared at different hot-pressing temperatures; Figure 6(a) shows the EIS diagrams of composite solid electrolytes prepared at different hot-pressing temperatures; Figure 6(b) shows the Arrhenius diagrams of composite solid electrolytes prepared at different hot-pressing temperatures. Detailed Implementation
[0023] The present invention will be described in detail below with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but should not be considered as limiting the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.
[0024] Example 1: Step 1: Preparation of solid electrolyte mixed powder: Under an argon protective atmosphere, Li with an average particle size of 5.5 μm was selected. 10 GeP2S 12 Compared with Li7La3Zr2O with an average particle size of 7.0 μm 12 The powder was initially dry-mixed and ground in a mortar at a 1:1 mass ratio. Then, the initially mixed powder was transferred to a sealed planetary ball mill jar and mechanically ball-milled at 300 rpm for 3 hours to obtain a mixed solid electrolyte powder with uniform composition and good structural stability.
[0025] The ball-to-material ratio is 10:1, and the grinding balls are zirconia grinding balls with diameters of 5 mm and 10 mm, with a volume ratio of 1:1 between the two types of grinding balls.
[0026] Step 2: Preparation of the composite solid electrolyte bulk material: An appropriate amount of the above-mentioned uniform composite powder was loaded into an extrusion mold. First, a cold-pressing pre-forming process was performed at room temperature with a pressure of 500 MPa, held for 20 min. Then, the mold containing the pre-formed blank was transferred to a muffle furnace for hot-pressing sintering under an inert atmosphere: the temperature was programmed to rise to a sintering temperature of 250℃ at a heating rate of 5 ℃ / min, and held at this temperature for 3 h, while continuously applying a pressure of 500 MPa. After sintering, the material was cooled to room temperature with the furnace at a cooling rate of 5 ℃ / min, ultimately obtaining a composite solid electrolyte bulk material with high densification and excellent ionic conductivity, named CSE-250.
[0027] Example 2: The difference between this example and Example 1 is that the sintering temperature in step two is 280℃, while the remaining process steps and parameter settings are the same as in Example 1, resulting in a solid electrolyte named CSE-280.
[0028] Example 3: The difference between this example and Example 1 is that the sintering temperature in step two is 310℃, while the remaining process steps and parameter settings are the same as in Example 1, resulting in a solid electrolyte named CSE-310.
[0029] Example 4: The difference between this example and Example 1 is that the sintering temperature in step two is 340℃, while the remaining process steps and parameter settings are the same as in Example 1, resulting in a solid electrolyte named CSE-340.
[0030] Figure 1 The image shows the surface morphology of the composite solid electrolyte obtained by this method. Compared with the electrolyte material obtained by cold pressing, the composite solid electrolyte after hot pressing has a dense structure without obvious pores and cracks. This is because the sulfides in the electrolyte soften during the hot pressing process, coat the oxides, and fill the original pores under continuous pressure. This is conducive to achieving a tight bond between LLZO and LGPS so that a transition phase can be generated at the interface between the two, thereby facilitating the conduction of lithium-ion transport channels.
[0031] Figure 2 The XRD pattern and magnified view of the composite solid electrolyte show that the LGPS characteristic peak shifts to a higher angle within the temperature range of 250℃ to 310℃. This is due to O / S interdiffusion. 2- The ionic radius (1.84 Å) is much larger than that of O. 2- With an ionic radius of 1.40 Å, O enters the LGPS lattice and partially substitutes for S, resulting in a reduction in the LGPS unit cell volume and a shift of the characteristic peak to a higher angle.
[0032] Figure 3 Raman spectroscopy for the composite solid electrolyte. 367 cm⁻¹ -1 Corresponding to the vibrational peak of Li-O, this peak gradually broadens and decreases in intensity with increasing temperature, indicating partial fracture of Li-O. (275 cm⁻¹) -1 and 420 cm -1 All represent PS4 3- The vibration peak gradually broadens with increasing temperature, and the broadening is more obvious at 310℃. The increased local structural disorder indicates that the PS bonds are partially broken, forming short-range ordered PSP or PO bonds, suggesting that the interface phase is an amorphous phase.
[0033] To further verify that O and S interdiffusion and new bond formation do exist at the interface, X-ray photoelectron spectroscopy (XPS) was used to characterize the elemental composition and electronic structure of composite solid electrolytes prepared at different heat treatment temperatures. Figure 4 The image shows the XPS spectra of the composite solid electrolyte. In the fine P 2p spectrum of the composite solid electrolyte, the peaks with binding energies of 131.7 eV and 132.6 eV originate from PS4 in LGPS. 3-After the temperature was increased to 310℃, new peaks at 132.3 eV and 133.4 eV corresponded to the formation of PSP and PO bonds, respectively, which is consistent with the Raman analysis results. In the S 2p fine spectrum of the composite solid electrolyte, the peaks with binding energies of 161.3 eV and 162 eV corresponded to the (P / Ge)-S-Li structure in LGPS. After the temperature was increased to 310℃, new peaks appeared at the positions of binding energies of 162.4 eV and 163.2 eV, indicating that S 2p oxidation formed thiosulfates, polysulfides, and elemental sulfur.
[0034] To further prove that the interface phase is an amorphous phase, the composite solid electrolyte was characterized by TEM. Figure 5 This is a TEM image of the composite solid electrolyte. The image clearly shows a distinct elemental diffusion layer at the LLZO / LGPS interface. Furthermore, the thickness of this diffusion layer gradually increases with increasing hot-pressing temperature. Additionally, this interface layer exhibits a distinct amorphous phase. This amorphous phase provides a more continuous channel for lithium-ion transport, reduces severe lattice distortion at grain boundaries, lowers the energy barrier for lithium-ion crossing the interface, and achieves extremely low interfacial ion transport resistance.
[0035] Figure 6 shows the EIS and Arrhenius spectra of the composite solid electrolyte. From the AC impedance spectra and Arrhenius curves of the composite electrolytes prepared at different hot-pressing temperatures, it can be seen that the ionic conductivity first increases and then decreases with increasing hot-pressing temperature. Correspondingly, the XRD, Raman, and XPS test results indicate that the composite solid electrolyte treated at 310℃ exhibits a favorable interfacial amorphous phase due to O / S interdiffusion at the interface, which promotes lithium-ion transport. At a hot-pressing temperature of 310℃, the ionic conductivity of the composite solid electrolyte can reach 4.86 × 10⁻⁶. -3 The S / cm ratio corresponds to an activation energy of 0.31 eV.
[0036] In summary, based on the XRD, Raman, XPS, and EIS test results of composite solid electrolytes prepared at different hot-pressing temperatures, we can find that the composite solid electrolyte can achieve the best performance when a certain amount of element diffusion occurs at the interface and a certain amorphous phase is formed at the interface.
[0037] The specific embodiments of the present invention have been described in detail above. It should be noted that the present invention is not limited to the specific embodiments described above. Various modifications or alterations can be made by those skilled in the art without departing from the scope of protection defined by the claims, and all such modifications or alterations fall within the scope of the present invention.
Claims
1. A method for preparing an inorganic solid electrolyte by pre-constructing an ion-fast transport interface through in-situ heat treatment, characterized in that, Includes the following steps: Step 1: Under an inert atmosphere, LLZO (Li7La3Zr2O) with a particle size of 1-10 μm is... 12 ) and LGPS (Li) with a particle size of 1-10 μm 10 GeP2S 12 The mixture is then dry-mixed and ball-milled under sealed conditions. Step 2: Then, it is placed into a mold, cold-pressed and sintered under an inert atmosphere. After sintering, it is cooled to room temperature in the furnace to obtain the inorganic solid electrolyte.
2. The method according to claim 1, characterized in that, The mass ratio of LLZO to LGPS is 1:
1.
3. The method according to claim 1, characterized in that, The ball mill speed is 200~400 rpm.
4. The method according to claim 1, characterized in that, The ball-to-material ratio is 10:
1.
5. The method according to claim 1, characterized in that, The grinding balls are zirconia grinding balls with diameters of 5 mm and 10 mm, and the volume ratio of the two types of grinding balls is 1:
1.
6. The method according to claim 1, characterized in that, Cold pressing is performed under a pressure of 200 ~ 500 MPa.
7. The method according to claim 1, characterized in that, Hot pressing sintering: The temperature is programmed to rise to 250℃~340℃ at a rate of 2~5℃ / min, held for 2~9 h, and a pressure of 200~500 MPa is continuously applied.
8. The method according to claim 1, characterized in that, The inert atmosphere is argon.
9. The method according to claim 1, characterized in that, The cooling rate is 1~5 ℃ / min.
10. An inorganic solid electrolyte prepared by the method according to any one of claims 1-9.