High Young's modulus solid electrolyte, all-solid-state lithium battery, and method for manufacturing the same.

Abstract

The present invention provides a method for manufacturing a high Young's modulus solid electrolyte, which has a simple process and produces a solid electrolyte with good mechanical performance, as well as a method for manufacturing an all-solid-state lithium battery with good electrochemical performance and a long service life. [Solution] A method for producing a high Young's modulus solid electrolyte, comprising the step of melting an electrolyte raw material under dry, oxygen-free conditions. The melting temperature is 405 to 700°C, and the melting time is 1 to 20 hours. The method also comprises the steps of rapidly cooling the molten liquid electrolyte into a solid block and controlling the cooling rate to 600 to 1200°C / min, and polishing the cooled solid block into a powder to produce a high Young's modulus solid electrolyte.

Description

[Technical Field]

[0001] This invention belongs to the field of battery technology, and more specifically, to a high Young's modulus solid electrolyte, an all-solid-state lithium battery, and a method for manufacturing the same. [Background technology]

[0002] Solid-state lithium-ion batteries are a current research focus and future research trend due to their advantages such as high safety, high energy density, and circulating performance. However, compared to liquid lithium-ion batteries, solid-state batteries have the problem of solid-solid contact, resulting in low lithium-ion transport efficiency and problems with chemical reactions and mechanical stress at the interface. Furthermore, the stability of the solid-solid interface seriously affects the electrochemical performance and safety of the battery, hindering the practical application of solid-state batteries.

[0003] Currently, most research on interface problems in solid-state batteries focuses on chemical reactions. However, unfavorable electrochemical-mechanical dynamics can lead to poor material utilization, mechanical degradation, and impaired ion transport, potentially affecting battery performance and lifespan. Mechanical performance, as a crucial physical property of solid materials, significantly impacts the mechanical stability and electrochemical performance of solid-state batteries. Therefore, studying the material mechanical properties of each component of a solid-state battery and the resulting mechanical failure behavior is of great importance. Since the solid electrolyte is in direct contact with the positive and negative electrodes, its mechanical properties significantly affect the mechanical integrity of the electrodes, and the mechanical stability of a solid lithium battery largely depends on the mechanical properties of the solid electrolyte. Therefore, developing an electrolyte that improves the physical and mechanical stability of solid-state batteries and releases structural stress accumulated during the circulation process is a technical challenge that those skilled in the art must address urgently. Currently, strategies to improve the mechanical properties of solid electrolytes mainly involve controlling the phase components, grain size, and porosity of the solid electrolyte itself, or reducing electrolyte defects by adding other components to the electrolyte to improve its performance. However, these control methods involve complex manufacturing processes and make it difficult to control the variables. [Overview of the project]

[0004] An object of the embodiments of the present invention is to provide a method for producing a high Young's modulus solid electrolyte that is simple in process and produces a solid electrolyte with good mechanical performance.

[0005] Another object of the embodiments of the present invention is to provide a method for manufacturing an all-solid-state lithium battery that is simple in process, has good electrochemical performance, and has a long service life.

[0006] Embodiments of the present invention are realized as follows. Embodiments of the present invention provide a method for producing a high Young's modulus solid electrolyte, comprising the following steps S1 to S3. S1: The electrolyte raw material is melted under dry, oxygen-free conditions, with a melting temperature of 405-700°C and a melting time of 1-20 hours. S2: The molten liquid electrolyte is rapidly cooled to a solid block, and the cooling rate is controlled to 600-1200°C / min. S3: The cooled solid block is polished into a powder to produce a high Young's modulus solid electrolyte.

[0007] Furthermore, in step S1, the melting temperature is 405°C and the time is 20 hours, or the melting temperature is 500°C and the time is 15 hours, or the melting temperature is 600°C and the time is 10 hours, or the melting temperature is 700°C and the time is 1 hour.

[0008] Furthermore, in step S2, the cooling rate is 600°C / min, 800°C / min, 1000°C / min, or 1200°C / min.

[0009] Furthermore, the electrolyte raw material is Li 2+x M x N 1-x It is Cl6, where M is one or more of Y, Er, Yb, Ho, In, La, Sc, Tb, and Dy, and N is one or two of Zr and Hf, and 0 ≤ x ≤ 1.

[0010] Furthermore, the electrolyte raw material is Li 2.5Y 0.5 Zr 0.5 Cl6, Li 2.6 Y 0.6 Hf 0.4 Cl6, Li3YCl6, or Li 2.5 Yb 0.5 Hf 0.5 is Cl6.

[0011] Embodiments of the present invention further provide a high Young's modulus solid electrolyte obtained by using the above-described method for manufacturing a solid electrolyte.

[0012] Embodiments of the present invention further provide an all-solid-state lithium battery including a positive electrode active material layer, a negative electrode active material layer, and the high Young's modulus solid electrolyte, wherein the high Young's modulus solid electrolyte is compressed into a block shape and provided between the positive electrode active material layer and the negative electrode active material layer.

[0013] Embodiments of the present invention further provide a method for manufacturing the above-described all-solid-state lithium battery, including the following steps A1 to A5. A1: After mixing a layered positive electrode material and a high Young's modulus solid electrolyte at a mixing ratio of 7:3 by mass ratio, grind them into powder to obtain positive electrode powder. A2: Weigh an appropriate amount of sulfide solid electrolyte and put it into the inner tank of the mold battery. Apply a pressure of 100 MPa to press-mold to obtain a first electrolyte layer. Then, take an appropriate amount of high Young's modulus solid electrolyte and uniformly place it on one side in the thickness direction of the first electrolyte layer, and apply a pressure of 150 MPa to press-mold to obtain a second electrolyte layer. A3: Uniformly place the positive electrode powder on the side of the second electrolyte layer far from the first electrolyte layer, and apply a pressure of 350 MPa to press-mold to obtain a positive electrode active material layer. A4: Place a metal indium sheet on the side of the first electrolyte layer away from the second electrolyte layer, and apply a pressure of 50 MPa to press-mold to obtain a negative electrode active material layer. A5: Put the inner tank into the mold battery, lock and seal it to manufacture an all-solid-state lithium battery.

[0014] Advantageous Effects of the Present Invention (1) The process for manufacturing the electrolyte provided in the embodiments of the present invention is simple. The solid electrolyte manufactured by the rapid cooling method of the present invention has a relatively high Young's modulus and better mechanical performance. (2) The all-solid-state lithium battery provided by the embodiments of the present invention can significantly improve the stability of the lithium battery interface, improve solid-solid mechanical contact, and improve the battery's circulation performance and efficiency. [Brief explanation of the drawing]

[0015] To more clearly illustrate the technical concept of the embodiments of the present invention, the drawings necessary for use in the embodiments are briefly described below. Since the following drawings show only a few embodiments of the present invention, they should not be considered a limitation to the scope, and those skilled in the art should understand that other relevant drawings can be obtained based on these drawings without any creative effort. [Figure 1] This is a computed tomography (CT) three-dimensional pore map of the cathode composite material after 100 cycles of the battery manufactured from the solid electrolyte of Example 1. [Figure 2] This is a CT three-dimensional pore map of the cathode composite material after 100 cycles of a battery manufactured from the solid electrolyte of Comparative Example 1. [Figure 3] This is a focused ion beam scanning electron microscope (FIB-SEM) image of the cathode composite material of a battery manufactured from the solid electrolyte of Example 1 after 100 cycles. Here, YZr-Q is the sample from Example 1, and LCO is the positive electrode active material LiCoO2. [Figure 4] This is a focused ion beam scanning electron microscope image of the cathode composite material of a sample after 100 cycles of a battery manufactured from the solid electrolyte of Comparative Example 1. Here, YZr-N is the sample from Comparative Example 1, and LCO is the positive electrode active material LiCoO2. [Modes for carrying out the invention]

[0016] To further clarify the purpose, technical proposal, and advantages of the embodiments of the present invention, the technical proposal of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments. It is clear that the embodiments described are only some embodiments of the present invention, and not all embodiments.

[0017] Therefore, the detailed description of embodiments of the present invention provided below in the drawings is not intended to limit the scope of the invention for which protection is claimed, but rather to illustrate only selected embodiments of the invention.

[0018] Furthermore, if there is no conflict, the embodiments and features of the present invention may be combined with each other.

[0019] The present invention provides a method for producing a high Young's modulus solid electrolyte, comprising the following steps S1 to S3. S1: The electrolyte raw material is melted under dry, oxygen-free conditions, with a melting temperature of 405-700°C and a melting time of 1-20 hours. S2: The molten liquid electrolyte is rapidly cooled to a solid block, and the cooling rate is controlled to 600-1200°C / min. S3: The cooled solid block is polished into a powder to produce a high Young's modulus solid electrolyte.

[0020] In the present invention, the electrolyte raw material is Li 2+x M x N 1-x It is Cl6, where M is one or more of Y, Er, Yb, Ho, In, La, Sc, Tb, and Dy, and N is one or two of Zr and Hf, and 0 ≤ x ≤ 1. For example, Li 2.5 Y 0.5 Zr 0.5 Cl6, Li 2.6 Y 0.6 Hf 0.4 Cl6, Li3YCl6, or Li 2.5 Yb 0.5 Hf 0.5 Cl6 and similar instruments can be used.

[0021] Example 1 Example 1 of the present invention produces a high Young's modulus solid electrolyte using the following methods S1 to S3. S1:Li 2.5 Y 0.5 Zr 0.5 Cl6(YZr-Q) was melted under dry, oxygen-free conditions, with a melting temperature of 405°C and a melting time of 20 hours. S2: The molten liquid electrolyte is rapidly cooled to a solid block, and the cooling rate is controlled to 600°C / min. S3: The cooled solid block is polished into a powder to produce a high Young's modulus solid electrolyte.

[0022] Example 2 Example 2 of the present invention produces a high Young's modulus solid electrolyte using the following methods S1 to S3. S1:Li 2.5 Y 0.5 Zr 0.5 Cl6 was melted under dry, oxygen-free conditions, with a melting temperature of 600°C and a melting time of 10 hours. S2: The molten liquid electrolyte is rapidly cooled to a solid block, and the cooling rate is controlled to 1000°C / min. S3: The cooled solid block is polished into a powder to produce a high Young's modulus solid electrolyte.

[0023] Example 3 Example 3 of the present invention produces a high Young's modulus solid electrolyte using the following methods S1 to S3. S1:Li 2.6 Y 0.6 Hf 0.4 Cl6 was melted under dry, oxygen-free conditions, with a melting temperature of 500°C and a melting time of 15 hours. S2: The molten liquid electrolyte is rapidly cooled to a solid block, and the cooling rate is controlled to 800°C / min. S3: The cooled solid block is polished into a powder to produce a high Young's modulus solid electrolyte.

[0024] Example 4 Example 4 of the present invention produces a high Young's modulus solid electrolyte using the following methods S1 to S3. S1:Li3YCl6 was melted under dry, oxygen-free conditions, with a melting temperature of 700°C and a melting time of 1 hour. S2: The molten liquid electrolyte is rapidly cooled to a solid block, and the cooling rate is controlled to 1200°C / min. S3: The cooled solid block is polished into a powder to produce a high Young's modulus solid electrolyte.

[0025] Example 5 Example 5 of the present invention produces a high Young's modulus solid electrolyte using the following methods S1 to S3. S1:Li 2.5 Yb 0.5 Hf 0.5 Cl6 was melted under dry, oxygen-free conditions, with a melting temperature of 550°C and a melting time of 8 hours. S2: The molten liquid electrolyte is rapidly cooled to a solid block, and the cooling rate is controlled to 900°C / min. S3: The cooled solid block is polished into a powder to produce a high Young's modulus solid electrolyte.

[0026] Comparative Example 1 Comparative Example 1 involves producing a solid electrolyte using the following methods S1 to S3. S1:Li 2.5 Y 0.5 Zr 0.5 Cl6(YZr-N) was melted under dry, oxygen-free conditions, with a melting temperature of 405°C and a melting time of 20 hours. S2: Allow the molten liquid electrolyte to cool naturally into a solid block. S3: The cooled solid block is polished into a powder to produce a solid electrolyte.

[0027] Comparative Example 2 Comparative Example 2 involves producing a solid electrolyte using the following methods S1 to S3. S1:Li 2.5 Yb 0.5 Hf 0.5 Cl6 was melted under dry, oxygen-free conditions, with a melting temperature of 550°C and a melting time of 8 hours. S2: Allow the molten liquid electrolyte to cool naturally into a solid block. S3: The cooled solid block is polished into a powder to produce a solid electrolyte.

[0028] The solid electrolytes produced by the methods of Examples 1 to 5, Comparative Example 1, and Comparative Example 2 were sequentially subjected to Young's modulus tests. The test method is as follows: 150 milligrams of solid electrolyte were placed in a mold cell in a glove box and compressed to obtain a sheet-like sample at a compression pressure of 400 MPa. Subsequently, the sheet-like sample was removed, and the dynamic curve of the sample was measured using an atomic force microscope. The Young's modulus was then analyzed based on the dynamic curve.

[0029] The test results are shown in Table 1. [Table 1]

[0030] As can be seen from Table 1, solid electrolytes manufactured by the rapid cooling method have a relatively high Young's modulus. Solid electrolytes with a relatively high Young's modulus are less prone to deformation under the same stress, can maintain good contact with the material when faced with volume expansion in the cathode material, and have better mechanical properties.

[0031] The present invention further provides a method for manufacturing an all-solid-state lithium battery, comprising the following steps A1 to A5. A1: Layered cathode material and solid electrolyte are mixed in a mass ratio of 7:3, then polished into a powder to obtain cathode powder. The layered cathode material can be selected from LiCoO2, NMC811, etc. In this step, polishing for about 10 minutes is sufficient. A2: A suitable amount of sulfide solid electrolyte is weighed and placed in the inner chamber of the molded battery, and a pressure of 100 MPa is applied to compress it into a tablet to obtain the first electrolyte layer. Then, a suitable amount of high Young's modulus solid electrolyte is taken and placed uniformly on one side in the thickness direction of the first electrolyte layer, and a pressure of 150 MPa is applied to compress it into a tablet to obtain the second electrolyte layer. In step A2, the sulfide solid electrolyte can be selected as Li6PS5Cl. Of course, the sulfide solid electrolyte can also be replaced with an oxide solid electrolyte, a halide electrolyte, a nitride electrolyte, a polymer electrolyte, an organic electrolyte, or a combination thereof. In step A2, the high Young's modulus solid electrolyte used was one of the high Young's modulus solid electrolytes prepared in Examples 1 to 5. A3: The positive electrode powder is uniformly placed on the side of the second electrolyte layer furthest from the first electrolyte layer, and a pressure of 350 MPa is applied to compress the tablet to obtain the positive electrode active material layer. A4: A metallic indium sheet is placed on the side of the first electrolyte layer away from the second electrolyte layer, and a pressure of 50 MPa is applied to compress the tablet to obtain the negative electrode active material layer. A5: The inner chamber is placed in a molded battery, locked and sealed to manufacture an all-solid-state lithium battery.

[0032] According to the method described above, all-solid-state lithium batteries were manufactured using the high Young's modulus solid electrolytes from Examples 1 to 5, and were designated as 1#, 2#, 3#, 4#, and 5#, respectively.

[0033] The high Young's modulus solid electrolyte in step A2 above was replaced with the solid electrolytes in Comparative Example 1 and Comparative Example 2 to manufacture all-solid-state lithium batteries, which were designated as 6# and 7#, respectively.

[0034] Performance tests were conducted on all-solid-state lithium batteries #1 through #7, and the test items were as follows:

[0035] (1) Ionic conductivity test. Ionic conductivity was measured using the AC impedance method on an electrochemical workstation. The measurement temperature was room temperature, the frequency range was 1 Hz to 7 MHz, and the constant voltage was 10 mV. Solid electrolyte (SE) powder was cold-pressed into pellets using a 10 mm diameter mold at a pressure of 300 MPa. The results are shown in Table 2. [Table 2] The data in Table 2 shows that the solid electrolyte provided by the present invention has high ionic conductivity, and that changing the heat treatment method of the material without changing its chemical composition does not fundamentally affect its ion transport performance. This indicates that it is possible to adjust its mechanical performance by changing the heat treatment method.

[0036] (2) Circulation stability test. Charge and discharge tests were performed using a current density of 1000 microamperes under a magnification of 1C, with cutoff voltages ranging from 2.6 to 4.6 volts. The results are shown in Table 3. [Table 3] Table 3 shows that electrolytes with high Young's modulus and high ionic conductivity exhibit better circulation capabilities. This indicates that high Young's modulus electrolytes can maintain mechanical stability in assembled batteries, effectively resist external strain, maintain good particle contact with the cathode material, and ultimately exhibit superior electrochemical performance.

[0037] (3) After 100 cycles of the 1# and 6# batteries, computed tomography (CT) scans were performed on the cathode composite materials. CT diagrams are shown in Figure 1 (Example 1) and Figure 2 (Comparative Example 1). As can be seen from the figures, the large and connected pores in the cathode composite material cube of Example 1 explain that this solid electrolyte has rigidity to resist crack propagation and toughness to withstand circulating stress biased from the electrodes. The small and separated pores in the cathode composite material cube of Comparative Example 1 explain that, due to biasing by undesirable stress, these solid electrolyte particles are crushed into powder and mainly appear as an electrolyte sample in the slice.

[0038] (4) After 100 cycles of the 1# battery and the 6# battery, the cathode composite material was subjected to focused ion beam scanning electron microscopy (FIB-SEM) testing. When volume expansion occurs in the positive electrode particles, the electrolyte in Figure 3 (Example 1) can effectively release the volume change caused by the LiCoO2 particles, maintaining good physical contact between the electrolyte and the positive electrode particles. In contrast, significant pores appear between the positive electrode particles and Figure 4 (Comparative Example 1), and simultaneously, structural powdering occurs in the electrolyte of Comparative Example 1, ultimately leading to a loss of physical contact between the positive electrode particles and the electrolyte of Comparative Example 1. The experimental results described above demonstrate that controlling the cooling rate of the electrolyte can effectively alter its mechanical properties. Under similar ion transport performance conditions, high Young's modulus solid electrolytes not only achieve both chemical and electrochemical stability but are also less prone to strain. Simultaneously, materials with relatively high toughness can absorb more energy before the material particles burst, better overcoming volume changes when the volume of the positive electrode particles expands, maintaining particle integrity, and further ensuring effective physical contact between particles, resulting in a longer battery life. In contrast, low Young's modulus solid electrolytes are prone to volumetric strain when the positive electrode material particles expand, and their low toughness makes them susceptible to structural fracture and collapse, ultimately leading to a shorter battery life and poor stability.

[0039] The present invention is not limited to any of the embodiments described above, and any other embodiments or technical ideas within the scope of the claims of the present invention that any person may have derived from the suggestions of the present invention are all within the scope of protection of the present invention.

Claims

1. S1: The electrolyte raw material is melted under dry, oxygen-free conditions, with a melting temperature of 405-700°C and a melting time of 1-20 hours. S2: The molten liquid electrolyte is rapidly cooled to a solid block, and the cooling rate is controlled to 600-1200°C / min. S3: A method for producing a high Young's modulus solid electrolyte, characterized by comprising polishing a cooled solid block into a powder to produce a high Young's modulus solid electrolyte.

2. The method for producing a high Young's modulus solid electrolyte according to claim 1, characterized in that in step S1, the melting temperature is 405°C and the time is 20h, or the melting temperature is 500°C and the time is 15h, or the melting temperature is 600°C and the time is 10h, or the melting temperature is 700°C and the time is 1h.

3. The method for producing a high Young's modulus solid electrolyte according to claim 1, characterized in that in step S2, the cooling rate is 600°C / min, 800°C / min, 1000°C / min, or 1200°C / min.

4. The electrolyte raw material is Li ２+ｘ M ｘ N １-ｘ Cl ６ And, The method for producing a high Young's modulus solid electrolyte according to claim 1, characterized in that M is one or more of Y, Er, Yb, Ho, In, La, Sc, Tb, and Dy, N is one or two of Zr and Hf, and 0 ≤ x ≤ 1.

5. The electrolyte raw material is Li ２.５ Y ０.５ Zr ０.５ Cl ６ 、Li ２.６ Y ０.６ Hf ０.４ Cl ６ 、Li ３ YCl ６ 、or Li ２.５ Yb ０.５ Hf ０.５ Cl ６ The method for producing a high Young's modulus solid electrolyte according to claim 4, characterized in that it is

6. A high Young's modulus solid electrolyte, characterized by being obtained using a method for producing a solid electrolyte according to any one of claims 1 to 5.

7. An all-solid-state lithium battery comprising a positive electrode active material layer, a negative electrode active material layer, and a high Young's modulus solid electrolyte as described in claim 6, wherein the high Young's modulus solid electrolyte is compressed into a block shape and provided between the positive electrode active material layer and the negative electrode active material layer.

8. A1: A layered cathode material and a high Young's modulus solid electrolyte are mixed in a mass ratio of 7:3, and then polished into a powder to obtain cathode powder. A2: A suitable amount of sulfide solid electrolyte is weighed and placed in the inner chamber of the molded battery, and a pressure of 100 MPa is applied to compress it into a tablet to obtain the first electrolyte layer. Then, a suitable amount of high Young's modulus solid electrolyte is taken and placed uniformly on one side in the thickness direction of the first electrolyte layer, and a pressure of 150 MPa is applied to compress it into a tablet to obtain the second electrolyte layer. A3: The positive electrode powder is uniformly placed on the side of the second electrolyte layer furthest from the first electrolyte layer, and a pressure of 350 MPa is applied to compress the tablet to obtain the positive electrode active material layer. A4: A metallic indium sheet is placed on the side of the first electrolyte layer away from the second electrolyte layer, and a pressure of 50 MPa is applied to compress the tablet to obtain the negative electrode active material layer. A5: A method for manufacturing an all-solid-state lithium battery according to claim 7, characterized in that it includes placing an inner chamber into a molded battery, locking and sealing it, and manufacturing an all-solid-state lithium battery.

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