Solid electrolyte of solid lithium battery

Abstract

The present invention relates to the technical field of solid-state lithium batteries, and discloses a solid-state electrolyte of a solid-state lithium battery, the solid-state electrolyte comprises a solid-state electrolyte, and the solid-state electrolyte comprises the following components: a lithium salt as an ion source; the substrate is used for providing mechanical support and forming an ion transmission channel; the inorganic filler is used for enhancing the mechanical property of the electrolyte and improving the ionic conductivity; and the rare earth element is used for improving the lithium ion conductivity of the solid electrolyte. According to the solid-state electrolyte of the solid-state lithium battery provided by the invention, the material combination of the solid-state electrolyte is optimized, so that the solid-state electrolyte has high ionic conductivity and excellent thermal and mechanical stability, short circuit and thermal runaway are reduced, the solid-state electrolyte can safely work under high-temperature and high-pressure conditions, and the overall performance of the solid-state battery is effectively improved; therefore, the conductivity and the stability of the solid-state lithium battery during use are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state lithium batteries, and in particular to a solid electrolyte of a solid-state lithium battery. Background Art

[0002] Since lithium-ion batteries were industrialized by Sony in the 1990s, they have played an important role in 3C products, large-scale storage, and now new energy power batteries. With the advancement of science and technology, society has put forward higher requirements for lithium-ion batteries, including high safety and long cycle life. Traditional lithium-ion batteries mostly use liquid organic electrolytes such as ether carbonates as electrolytes, but liquid electrolytes have problems such as leakage, volatility, flammability and explosion. In addition, during the battery cycle, unevenly deposited lithium dendrites will pierce the diaphragm, causing battery short circuits and even safety accidents; in order to solve the above problems, people have turned their attention to solid electrolytes. Generally speaking, solid electrolytes have the advantages of thermal stability, chemical stability, electrochemical stability and good mechanical strength. Therefore, the use of solid electrolytes can fundamentally eliminate safety hazards; With the widespread use of electric vehicles and portable electronic devices, the safety, energy density and cycle stability of lithium-ion batteries are increasingly required. In recent years, solid-state lithium batteries have attracted widespread attention due to their excellent safety, environmental adaptability and high energy density. At present, solid electrolytes include inorganic solid electrolytes, gel polymer electrolytes and solid polymer electrolytes. Among them, solid polymer electrolytes have high lithium ion conductivity and electrode / electrolyte contact interface, and their excellent flexibility and ductility make them promising. As the core component of solid-state lithium batteries, solid electrolytes determine the performance of batteries; However, the electrolyte materials in common all-solid-state lithium batteries generally have low conductivity, so when used, they often cause a large amount of energy loss and waste, which brings high production costs to enterprises. Therefore, it is urgent to design a solid electrolyte for solid-state lithium batteries to solve the above problems. Summary of the invention

[0003] The object of the present invention is to provide a solid electrolyte for a solid-state lithium battery to solve the above-mentioned deficiencies in the prior art.

[0004] In order to achieve the above object, the present invention provides the following technical solutions: A solid electrolyte for a solid-state lithium battery, comprising a solid electrolyte, wherein the solid electrolyte is composed of the following components: a lithium salt as an ion source; A substrate, the substrate is used to provide mechanical support and form ion transport channels; Inorganic fillers, which are used to enhance the mechanical properties of the electrolyte and improve the ionic conductivity; Rare earth elements, which are used to improve the lithium ion conductivity of the solid electrolyte; Ceramic material, the ceramic material is used to enhance the toughness of the electrolyte.

[0005] The lithium salt is one of lithium fluoride, lithium sulfide or lithium phosphate.

[0006] The matrix is ​​a polymer matrix, and the polymer matrix is ​​a copolymer formed by combining one or more of polyoxyethylene, polyvinylidene fluoride, polyacrylonitrile and polyurethane.

[0007] The inorganic filler is a copolymer formed by combining one or more of lithium oxide, lithium titanate, lithium phosphate, aluminum oxide and silicon oxide.

[0008] The inorganic filler is a nano-scale filler, and the particle size of the inorganic filler is 1-100 nanometers.

[0009] The rare earth element is a copolymer formed by combining one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, erbium, lutetium and yttrium.

[0010] The ceramic material is one of zirconium oxide, silicon nitride, silicon dioxide, titanium disulfide and lithium sulfide.

[0011] The method for preparing the solid electrolyte comprises the following steps: S1, mixing the matrix, the lithium salt, the inorganic filler, the rare earth element and the ceramic material in proportion; S2, heating the mixture to above the melting point of the matrix to fully melt it, adding an organic solvent after the melting and mixing is completed, and then stirring the melted mixture to ensure that the components are evenly distributed to form a uniform slurry; S3, coating the slurry on the polymer substrate to form a uniform film with a thickness controlled between 20 microns and 100 microns; S4, drying at a temperature of 50° C. to 80° C. to remove the solvent and form a solid electrolyte sheet; S5. The dried electrolyte sheet or block is sintered in an inert atmosphere to improve its density and ion conductivity.

[0012] The stirring in S2 is performed by ultrasonic mixing, the frequency of the ultrasonic mixing is 15 kHz to 60 kHz, and the mixing time is 1 hour to 2 hours to ensure that the components are evenly dispersed.

[0013] The inert atmosphere in S5 is nitrogen or helium. The sintering temperature in S5 is set to 300° C. to 600° C., and the duration is 2 hours to 10 hours.

[0014] In the above technical solution, the present invention provides a solid electrolyte for a solid-state lithium battery, which has the following beneficial effects: (1) The solid electrolyte of the solid-state lithium battery provided by the present invention optimizes the material combination of the solid electrolyte so that it has high ionic conductivity and excellent thermal and mechanical stability, reduces the occurrence of short circuit and thermal runaway, can work safely under high temperature and high pressure conditions, and effectively improves the overall performance of the solid-state battery, thereby improving the conductivity and stability of the solid-state lithium battery during use.

[0015] (2) The solid electrolyte of the solid-state lithium battery provided by the present invention has a simple preparation method, readily available raw materials, low cost, is suitable for large-scale production, and has good economic efficiency, thereby effectively reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0017] Figure 1 A schematic diagram of the solid electrolyte structure provided for a solid-state lithium battery embodiment of the present invention.

[0018] Figure 2 A schematic diagram of the manufacturing process structure of a solid electrolyte embodiment of a solid-state lithium battery provided by the present invention.

[0019] Figure 3 A schematic diagram of a stacked structure of several electrolyte sheets provided for a solid electrolyte embodiment of a solid-state lithium battery of the present invention. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0021] like Figure 1-3 As shown, a solid electrolyte of a solid-state lithium battery provided by an embodiment of the present invention includes a solid electrolyte, and the solid electrolyte is composed of the following components: Lithium salt, lithium salt is used as an ion source, and the lithium salt adopts one of lithium fluoride, lithium sulfide or lithium phosphate; A matrix, the matrix is ​​used to provide mechanical support and form an ion transmission channel, the matrix is ​​a polymer matrix, and the polymer matrix is ​​a copolymer composed of one or more of polyoxyethylene, polyvinylidene fluoride, polyacrylonitrile and polyurethane; Inorganic filler, which is used to enhance the mechanical properties of the electrolyte and improve the ionic conductivity. The inorganic filler is a copolymer composed of one or more of lithium oxide, lithium titanate, lithium phosphate, aluminum oxide and silicon oxide. The inorganic filler is a nano-scale filler, and the particle size of the inorganic filler is 1-100 nanometers; Rare earth elements, which are used to improve the lithium ion conductivity of solid electrolytes. Rare earth elements are copolymers formed by combining one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, erbium, lutetium and yttrium; Ceramic material: Ceramic material is used to enhance the toughness of the electrolyte. The ceramic material adopts one of zirconium oxide, silicon nitride, silicon dioxide, titanium disulfide and lithium sulfide.

[0022] In this embodiment, the solid electrolyte is composed of a number of stacked electrolyte sheets. By optimizing the material combination of the solid electrolyte, it has high ionic conductivity and excellent thermal and mechanical stability, reduces the occurrence of short circuits and thermal runaway, can work safely under high temperature and high pressure conditions, and effectively improves the overall performance of the solid-state battery, thereby improving the conductivity and stability of the solid-state lithium battery during use.

[0023] The method for preparing the solid electrolyte comprises the following steps: S1. Mixing the matrix, lithium salt, inorganic filler, rare earth element and ceramic material in proportion; S2, heating the mixture to above the melting point of the matrix to fully melt it, adding an organic solvent after the melting and mixing is completed, and then stirring the melted mixture to ensure that the components are evenly distributed to form a uniform slurry; S3, coating the slurry on the polymer substrate to form a uniform film with a thickness controlled between 20 microns and 100 microns; S4, drying at a temperature of 50° C. to 80° C. to remove the solvent and form a solid electrolyte sheet; S5, sintering the dried electrolyte sheet or block in an inert atmosphere to improve its density and ion conductivity; The stirring in S2 is carried out by ultrasonic mixing, the frequency of the ultrasonic mixing is 15kHz to 60kHz, and the mixing time is 1 hour to 2 hours to ensure that the components are evenly dispersed. The inert atmosphere in S5 is one of nitrogen or helium. The sintering temperature in S5 is set to 300℃ to 600℃, and the duration is 2 hours to 10 hours.

[0024] In this embodiment, high-purity lithium salts and ceramic materials are selected to ensure their effectiveness and stability in the electrolyte. The organic solvent is dimethylsulfamide DMSO. After the solid electrolyte is prepared, the solid electrolyte is tested for ionic conductivity by AC impedance method, its amplitude and phase angle are measured, its conductivity is recorded, and heat resistance and mechanical strength tests are performed to evaluate its conductivity and practical application performance. The preparation method is simple, the raw materials are easily available, the cost is low, it is suitable for large-scale production, and it has good economy.

[0025] Embodiment 1: Lithium sulfide is used as lithium salt, the addition amount of lithium salt is 60%, polyethylene oxide is used as polymer matrix, the addition amount of polymer matrix is ​​25%, 8% mass fraction of nano lithium phosphate is added, 3% of copolymer composed of neodymium, gadolinium and yttrium rare earth elements is added, and 4% of lithium sulfide is added. The solid electrolyte prepared by the above method has an ionic conductivity of 1.3×10^-3 S / cm at 25°C and a thermal stability higher than 165°C. After 1000 charge and discharge cycles, the battery capacity attenuation rate is less than 11.5%.

[0026] Embodiment 2: Lithium fluoride is used as lithium salt, the addition amount of lithium salt is 65%, polyethylene oxide is used as polymer matrix, the addition amount of polymer matrix is ​​25%, 12% mass fraction of nano-alumina is added, 7% of copolymer composed of lanthanum, cerium and praseodymium rare earth elements is added, and 5% of silicon nitride is added. The solid electrolyte prepared by the above method has an ionic conductivity of 1.0×10^-3 S / cm at 25°C and a thermal stability higher than 180°C. After 1000 charge and discharge cycles, the battery capacity attenuation rate is less than 10%.

[0027] Embodiment 3: Lithium phosphate is used as lithium salt, and the addition amount of lithium salt is 63%. Polyethylene oxide is used as polymer matrix, and the addition amount of polymer matrix is ​​22%. 7% mass fraction of nano-alumina is added, 3% of copolymer composed of erbium, lutetium and yttrium rare earth elements is added, and 5% of silicon nitride is added. The solid electrolyte prepared by the above method has an ionic conductivity of 1.2×10^-3 S / cm at 25°C, a thermal stability higher than 170°C, and after 1000 charge and discharge cycles, the battery capacity attenuation rate is less than 10.5%.

[0028] After testing the results of the solid electrolytes prepared in Example 1, Example 2 and Example 3, it was found that the solid electrolyte prepared in Example 2 had the best effect, could effectively meet the working requirements of solid-state lithium batteries, exhibited good electrochemical and mechanical properties, and effectively solved the problem of low conductivity efficiency commonly found in existing solid electrolyte materials.

[0029] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A solid electrolyte for a solid-state lithium battery, characterized in that: The invention comprises a solid electrolyte, wherein the solid electrolyte is composed of the following components: a lithium salt as an ion source; A substrate, the substrate is used to provide mechanical support and form ion transport channels; Inorganic fillers, which are used to enhance the mechanical properties of the electrolyte and improve the ionic conductivity; Rare earth elements, which are used to improve the lithium ion conductivity of the solid electrolyte; Ceramic material, the ceramic material is used to enhance the toughness of the electrolyte.

2. The solid electrolyte of a solid-state lithium battery according to claim 1, characterized in that: The lithium salt is one of lithium fluoride, lithium sulfide or lithium phosphate.

3. The solid electrolyte of a solid-state lithium battery according to claim 1, characterized in that: The matrix is ​​a polymer matrix, and the polymer matrix is ​​a copolymer formed by combining one or more of polyoxyethylene, polyvinylidene fluoride, polyacrylonitrile and polyurethane.

4. The solid electrolyte of a solid-state lithium battery according to claim 1, characterized in that: The inorganic filler is a copolymer formed by combining one or more of lithium oxide, lithium titanate, lithium phosphate, aluminum oxide and silicon oxide.

5. The solid electrolyte of a solid-state lithium battery according to claim 1, characterized in that: The inorganic filler is a nano-scale filler, and the particle size of the inorganic filler is 1-100 nanometers.

6. The solid electrolyte of a solid-state lithium battery according to claim 1, characterized in that: The rare earth element is a copolymer formed by combining one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, erbium and lutetium.

7. The solid electrolyte of a solid-state lithium battery according to claim 1, characterized in that: The ceramic material is one of zirconium oxide, silicon nitride, silicon dioxide, titanium disulfide and lithium sulfide.

8. The solid electrolyte of a solid-state lithium battery according to claim 1, characterized in that: The method for preparing the solid electrolyte comprises the following steps: S1, mixing the matrix, the lithium salt, the inorganic filler, the rare earth element and the ceramic material in proportion; S2, heating the mixture to above the melting point of the matrix to fully melt it, adding an organic solvent after the melting and mixing is completed, and then stirring the melted mixture to ensure that the components are evenly distributed to form a uniform slurry; S3, coating the slurry on the polymer substrate to form a uniform film with a thickness controlled between 20 microns and 100 microns; S4, drying at a temperature of 50° C. to 80° C. to remove the solvent and form a solid electrolyte sheet; S5. The dried electrolyte sheet or block is sintered in an inert atmosphere to improve its density and ion conductivity.

9. The solid electrolyte of a solid-state lithium battery according to claim 8, characterized in that: The stirring in S2 is performed by ultrasonic mixing, the frequency of the ultrasonic mixing is 15 kHz to 60 kHz, and the mixing time is 1 hour to 2 hours to ensure that the components are evenly dispersed.

10. The solid electrolyte of a solid-state lithium battery according to claim 8, characterized in that: The inert atmosphere in S5 is one of nitrogen or helium, the sintering temperature in S5 is set to 300° C. to 600° C., and the duration is 2 hours to 10 hours.

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