Method for manufacturing composite solid electrolyte, composite solid electrolyte, and solid-state battery

Abstract

This invention relates to a method for manufacturing a composite solid electrolyte, comprising the following steps: preparing a porous preform from a first solid electrolyte component; introducing a precursor solution containing a second solid electrolyte component into the pores of the preform, such that the content of the second solid electrolyte component on the negative electrode side of the preform differs from its content on the positive electrode side of the preform; and co-sintering the preform with the introduced precursor solution to form a composite solid electrolyte. A corresponding composite solid electrolyte and solid-state battery are also involved. The advantages of different electrolyte materials can be combined to improve the overall mechanical strength, ionic conductivity, and electrode stability of the composite solid electrolyte.

Description

Technical Field

[0001] This invention relates to the technical field of batteries, and more particularly to a method for manufacturing a composite solid-state electrolyte. The invention also relates to a corresponding composite solid-state electrolyte and a corresponding solid-state battery. Background Technology

[0002] Solid-state batteries have attracted widespread attention due to their advantages in safety and energy density. As the core component of solid-state batteries, solid electrolytes need to simultaneously meet stringent requirements such as high ionic conductivity, a wide electrochemical stability window, high mechanical strength, and good interfacial compatibility.

[0003] Currently, different types of solid electrolytes exist, such as oxide ceramic solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes, but each type of solid electrolyte has its own advantages and disadvantages. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide an improved method for manufacturing composite solid electrolytes, which can combine the advantages of different electrolyte materials to improve the overall mechanical strength, ionic conductivity and stability of the electrodes of the composite solid electrolyte.

[0005] The present invention also aims to provide a corresponding composite solid electrolyte and a corresponding solid battery.

[0006] According to a first aspect of the present invention, a method for manufacturing a composite solid electrolyte is provided, wherein the manufacturing method comprises at least the following steps: S1: A porous preform is prepared from the first solid electrolyte component; S2: Introduce a precursor solution containing a second solid electrolyte component into the pores of the preform, such that the content of the second solid electrolyte component on the negative electrode side of the preform is different from the content on the positive electrode side of the preform. S3: The preform with the introduced precursor solution is co-sintered to form a composite solid electrolyte.

[0007] Compared to existing technologies, in the manufacturing method for composite solid electrolytes according to the present invention, a precursor solution containing a second solid electrolyte component is introduced into the pores of a preform prepared from a first solid electrolyte component, such that the content of the second solid electrolyte component on the negative electrode side of the preform differs from its content on the positive electrode side. The preform with the introduced precursor solution is then co-sintered. This composite solid electrolyte can fully utilize the advantages of different solid electrolyte components. The content of the second solid electrolyte component on the positive and negative electrode sides can be specifically adjusted according to the characteristics of the positive and negative electrodes, thereby improving the stability of contact with the negative electrode, enhancing the oxidation resistance on the positive electrode side, and effectively eliminating the physical interface between different materials and reducing ion transport resistance. This can improve the overall mechanical strength, ionic conductivity, and electrode stability of the composite solid electrolyte.

[0008] For example, the content of the second solid electrolyte component on the negative electrode side of the preform is greater than the content on the positive electrode side of the preform; and / or, the content of the second solid electrolyte component varies continuously between the negative electrode side and the positive electrode side and exhibits a gradient distribution.

[0009] For example, step S2 includes the following sub-steps: S21: The positive electrode side of the preform is brought into contact with a liquid-absorbing material that is wetted with the precursor solution; S22: Using capillary force, the precursor solution permeates from the positive electrode side to the negative electrode side; S23: Evaporate the solvent of the precursor solution on the negative electrode side, thereby enriching the second solid electrolyte component on the negative electrode side.

[0010] For example, in step S2, the preform is evacuated before the precursor solution is introduced to remove air from the pores.

[0011] For example, in step S2, the negative electrode side of the preform is lower than the positive electrode side along the direction of gravity.

[0012] For example, in step S1, the preform is made by pressing and pre-sintering oxide ceramic powder, which is the first solid electrolyte component, and a pore-forming agent; and / or, the preform has a controllable porosity, wherein the porosity of the negative electrode side of the preform is greater than the porosity of the positive electrode side.

[0013] For example, the second solid electrolyte component is a halide electrolyte; and / or, the solvent of the precursor solution is an anhydrous solvent.

[0014] For example, in step S3, co-sintering is performed at a low sintering temperature, particularly less than 300°C, with the addition of a transient sintering aid and / or the application of uniaxial pressure.

[0015] According to a second aspect of the present invention, a composite solid electrolyte is provided, wherein the composite solid electrolyte is manufactured by the manufacturing method according to the present invention, and the composite solid electrolyte comprises at least: - A porous matrix made of a first solid electrolyte component; and - A second solid electrolyte component filling the pores of the porous matrix, wherein the content of the second solid electrolyte component on the negative electrode side of the composite solid electrolyte is different from the content on the positive electrode side of the composite solid electrolyte.

[0016] For example, the content of the second solid electrolyte component on the negative electrode side is greater than that on the positive electrode side; and / or, the content of the second solid electrolyte component varies continuously between the negative electrode side and the positive electrode side and exhibits a gradient distribution.

[0017] For example, the second solid electrolyte component is a halide electrolyte; and / or, the first solid electrolyte component is an oxide ceramic electrolyte.

[0018] According to a third aspect of the present invention, a solid-state battery is provided, characterized in that the solid-state battery comprises at least a negative electrode, a positive electrode, and a composite solid-state electrolyte according to the present invention. Attached Figure Description

[0019] The invention will now be described in more detail with reference to the accompanying drawings, which will provide a better understanding of its principles, features, and advantages. The drawings include: Figure 1 A schematic flowchart of a method for manufacturing a composite solid electrolyte according to an exemplary embodiment of the present invention is shown. Detailed Implementation

[0020] To make the technical problems to be solved, the technical solutions, and the beneficial technical effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and several exemplary embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0021] This specification provides the operational steps for the methods described in the embodiments or flowcharts, but based on conventional or non-inventive labor, more or fewer operational steps may be included. The order of steps listed in the embodiments is merely one possible execution order among many and does not represent the only possible execution order.

[0022] Figure 1 A schematic flowchart of a method for manufacturing a composite solid electrolyte according to an exemplary embodiment of the present invention is shown.

[0023] like Figure 1 As shown, the manufacturing method according to the present invention includes at least the following steps: S1: A porous preform is prepared from the first solid electrolyte component, which will then form the matrix or framework of the composite solid electrolyte. Therefore, the first solid electrolyte component should have high mechanical strength and good electrochemical stability. S2: A precursor solution containing a second solid electrolyte component is introduced into the pores of the preform, such that the content of the second solid electrolyte component on the negative electrode side of the preform is different from the content on the positive electrode side of the preform. The negative electrode side is configured to contact the negative electrode of the solid-state battery, and the positive electrode side is configured to contact the positive electrode of the solid-state battery. The second solid electrolyte component is different from the first solid electrolyte component and should in particular have good compatibility with the electrode and high ionic conductivity. S3: The preform with the precursor solution introduced is co-sintered in the mold, so that the second solid electrolyte component in the precursor solution crystallizes in situ in the pores of the preform to form a composite solid electrolyte, the composite solid electrolyte having a porous matrix made of a first solid electrolyte component and a second solid electrolyte component filling the pores of the porous matrix.

[0024] Here, the composite solid electrolyte formed in this way can make full use of the advantages of the first solid electrolyte component and the second solid electrolyte component. By adjusting the content of the second solid electrolyte component on the positive and negative electrode sides, it can be well adapted to the characteristics of the positive and negative electrodes. This can not only improve the stability of the contact between the negative electrode and the negative electrode, but also improve the oxidation resistance of the positive electrode side. It can also effectively eliminate the physical interface between different materials, fundamentally avoid the risk of interlayer delamination and reduce ion transport resistance. This can effectively improve the overall mechanical strength, ionic conductivity and stability of the composite solid electrolyte against the electrode.

[0025] For example, the first solid electrolyte component used to prepare the preform is an oxide ceramic electrolyte, which has high mechanical strength and high Young's modulus to provide structural support and electrochemical stability at high voltages. Here, the oxide ceramic electrolyte is, for example, a NASICON-structured LATP, a garnet-structured LLZO, or a perovskite-type lithium-ion conductor.

[0026] For example, in step S1, the preform is made by pressing and pre-sintering oxide ceramic powder, which is a first solid electrolyte component, and a pore-forming agent. The oxide ceramic powder and the pore-forming agent, such as carbon black or starch granules, are first mixed, and then the mixture is pressed into a green sheet. Then, pre-sintering is performed at a sintering temperature of, for example, 600°C to 800°C, which should be able to burn off the pore-forming agent and form a preliminary sintering neck in the oxide ceramic powder, so as to give the preform a certain mechanical strength and generate a large number of interconnected three-dimensional pore networks.

[0027] For example, the second solid electrolyte component is a halide electrolyte, which has high ionic conductivity, good ductility, and a low sintering temperature. An example halide electrolyte is Li3InCl6. Here, the composite solid electrolyte formed by the oxide ceramic electrolyte as the first solid electrolyte component and the halide electrolyte as the second solid electrolyte component combines the mechanical strength of the oxide ceramic electrolyte, the high ionic conductivity of the halide electrolyte, and the electrode stability, thereby improving the overall performance of the composite solid electrolyte. Of course, other electrolyte components that are considered meaningful by those skilled in the art, such as sulfide electrolytes, can also be considered.

[0028] For example, the solvent for the precursor solution is an anhydrous solvent, such as tetrahydrofuran. This effectively prevents undesirable chemical reactions between the halide electrolyte and the aqueous solvent, thereby preventing the introduction of impurities.

[0029] For example, in step S2, the content of the second solid electrolyte component on the negative electrode side of the preform is greater than that on the positive electrode side of the preform. In particular, the halide electrolyte, as the second solid electrolyte component, is enriched on the negative electrode side of the preform, thereby utilizing the good ductility of the halide electrolyte to form a soft interfacial contact with the lithium metal negative electrode. This effectively buffers the stress during lithium deposition and suppresses dendrite growth, thereby significantly improving the stability of the negative electrode.

[0030] For example, in step S2, the content of the second solid electrolyte component continuously varies and exhibits a gradient distribution between the negative and positive electrode sides of the preform. This establishes a continuous, uninterrupted ion transport pathway and enables the regular and directional introduction or permeation of the precursor solution. In particular, the content of the halide electrolyte, as the second solid electrolyte component, continuously increases from the positive electrode side to the negative electrode side, resulting in the enrichment of the halide electrolyte on the negative electrode side of the preform.

[0031] For example, such as Figure 1 As shown, step S2 includes the following sub-steps: S21: The positive electrode side of the dried preform is brought into contact with a liquid-absorbing material impregnated with the precursor solution, such as filter paper, sponge, etc. S22: Using capillary force, the precursor solution permeates from the absorbent material to the positive electrode side and further to the negative electrode side; S23: The solvent in the precursor solution is evaporated on the negative electrode side by directional drying, which can be achieved, for example, by setting a heat source. As the solvent evaporates on the negative electrode side, the second solid electrolyte component in the precursor solution is deposited on the negative electrode side, while more precursor solution is replenished from the positive electrode side to the negative electrode side, thereby transferring more of the second solid electrolyte component to the negative electrode side, thus enriching the second solid electrolyte component on the negative electrode side.

[0032] For example, in step S2, the preform is evacuated before the precursor solution is introduced to remove air from the pores. This allows for a smoother permeation process of the precursor solution into the preform and avoids air entrainment in the resulting composite solid electrolyte.

[0033] For example, in step S2, the negative electrode side of the preform is lower than the positive electrode side along the direction of gravity. This can promote the flow of the precursor solution from the positive electrode side to the negative electrode side, which is beneficial to the gradient distribution of the second solid electrolyte component and its enrichment on the negative electrode side.

[0034] For example, the preform prepared in step S1 has a controllable porosity, for example, 30% to 50%, wherein the porosity on the negative electrode side of the preform is greater than that on the positive electrode side by controlling the mixing of the pore-forming agent. This allows the precursor solution to more easily permeate from the positive electrode side to the negative electrode side, thereby further promoting the gradient distribution of the second solid electrolyte component and its enrichment on the negative electrode side.

[0035] For example, in step S3, a transient sintering aid is added. This transient sintering aid can significantly reduce the sintering temperature, improve the interfacial bonding quality, and promote the densification of the composite solid electrolyte. Furthermore, a uniaxial pressure, such as 500 MPa, can be applied during the co-sintering process. This uniaxial pressure can also enhance the densification of the composite solid electrolyte. In particular, the combined effect of the transient sintering aid and the uniaxial pressure can promote the closure of residual pores in the porous preform and achieve the densification of the composite solid electrolyte.

[0036] For example, in step S3, co-sintering is performed at a low sintering temperature, particularly below 300°C, for example, 150°C. This significantly reduces energy consumption and makes it possible to co-sinter heat-sensitive halide electrolytes, preforms, and even cathode materials in a single unit, simplifying the manufacturing process of solid electrolytes.

[0037] According to the present invention, a composite solid electrolyte is also provided, said composite solid electrolyte being manufactured by the manufacturing method according to the present invention, said composite solid electrolyte comprising at least: - A porous matrix made of a first solid electrolyte component; and - A second solid electrolyte component filling the pores of the porous matrix, wherein the content of the second solid electrolyte component on the negative electrode side of the composite solid electrolyte is different from the content on the positive electrode side of the composite solid electrolyte.

[0038] For example, the first solid electrolyte component is an oxide ceramic electrolyte, such as LATP with a NASICON structure or LLZO with a garnet structure, while the second solid electrolyte component is a halide electrolyte, such as Li3InCl6.

[0039] For example, the content of the second solid electrolyte component on the negative electrode side is greater than that on the positive electrode side. In particular, the content of the second solid electrolyte component varies continuously and exhibits a gradient distribution between the negative electrode side and the positive electrode side.

[0040] According to the present invention, a solid-state battery is also provided, the solid-state battery comprising at least a negative electrode, a positive electrode, and a composite solid-state electrolyte according to the present invention. Here, the negative electrode side of the composite solid-state electrolyte is in contact with the negative electrode, and the positive electrode side is in contact with the positive electrode. In particular, the negative electrode of the solid-state battery is made of lithium metal, while the positive electrode is made of a high-voltage resistant composite material.

[0041] The foregoing description of the embodiments is limited to the framework of the examples given. Of course, the various features of the embodiments can be freely combined with each other without departing from the framework of the invention, as long as it is technically meaningful.

[0042] Other advantages and alternative embodiments of the present invention will be apparent to those skilled in the art. Therefore, the present invention is not, in its broader sense, limited to the specific details, representative structures, and exemplary embodiments shown and described. Rather, those skilled in the art can make various modifications and substitutions without departing from the basic spirit and scope of the invention.

Claims

1. A method for manufacturing a composite solid electrolyte, characterized in that, The manufacturing method includes at least the following steps: S1: A porous preform is prepared from the first solid electrolyte component; S2: Introduce a precursor solution containing a second solid electrolyte component into the pores of the preform, such that the content of the second solid electrolyte component on the negative electrode side of the preform is different from the content on the positive electrode side of the preform. S3: The preform with the introduced precursor solution is co-sintered to form a composite solid electrolyte.

2. The manufacturing method according to claim 1, characterized in that, The content of the second solid electrolyte component on the negative electrode side of the preform is greater than its content on the positive electrode side of the preform; and / or The content of the second solid electrolyte component varies continuously and exhibits a gradient distribution between the negative electrode side and the positive electrode side.

3. The manufacturing method according to claim 2, characterized in that, Step S2 includes the following sub-steps: S21: The positive electrode side of the preform is brought into contact with a liquid-absorbing material that is wetted with the precursor solution; S22: Using capillary force, the precursor solution permeates from the positive electrode side to the negative electrode side; S23: Evaporate the solvent of the precursor solution on the negative electrode side, thereby enriching the second solid electrolyte component on the negative electrode side.

4. The manufacturing method according to claim 3, characterized in that, In step S2, the preform is evacuated before the precursor solution is introduced to remove air from the pores; and / or In step S2, the negative electrode side of the preform is lower than the positive electrode side along the direction of gravity.

5. The manufacturing method according to any one of the preceding claims, characterized in that, In step S1, the preform is made by pressing and pre-sintering oxide ceramic powder, which is the first solid electrolyte component, and a pore-forming agent; and / or The preform has a controllable porosity, wherein the porosity of the negative electrode side of the preform is greater than the porosity of the positive electrode side.

6. The manufacturing method according to any one of the preceding claims, characterized in that, The second solid electrolyte component is a halide electrolyte; and / or The solvent for the precursor solution is an anhydrous solvent.

7. The manufacturing method according to any one of the preceding claims, characterized in that, In step S3, co-sintering is performed at a low sintering temperature, particularly less than 300°C, with the addition of a transient sintering aid and / or the application of uniaxial pressure.

8. A composite solid electrolyte, characterized in that, The composite solid electrolyte is manufactured by the manufacturing method according to any one of claims 1 to 7, and the composite solid electrolyte comprises at least: - A porous matrix made of a first solid electrolyte component; and - A second solid electrolyte component filling the pores of the porous matrix, wherein the content of the second solid electrolyte component on the negative electrode side of the composite solid electrolyte is different from the content on the positive electrode side of the composite solid electrolyte.

9. The composite solid electrolyte according to claim 8, characterized in that, The content of the second solid electrolyte component on the negative electrode side is greater than its content on the positive electrode side; and / or The content of the second solid electrolyte component varies continuously and exhibits a gradient distribution between the negative electrode side and the positive electrode side; and / or The second solid electrolyte component is a halide electrolyte; and / or The first solid electrolyte component is an oxide ceramic electrolyte.

10. A solid-state battery, characterized in that, The solid-state battery includes at least a negative electrode, a positive electrode, and a composite solid-state electrolyte according to claim 8 or 9.

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