Composite solid electrolyte and all-solid-state lithium battery cell
By recombining Ce-doped lithium titanate nanoribbons with polymer electrolytes, forming a composite solid electrolyte with one-dimensional band shape and crossing into a three-dimensional network structure, the safety hazards and insufficient performance of liquid electrolytes are solved, and electrolyte preparation with high conductivity and good mechanical strength is achieved.
Patent Information
- Application Number
- CN202510482994.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-16
- Publication Date
- 2025-08-08
AI Technical Summary
Traditional lithium-ion batteries use liquid organic electrolytes with safety risks, and lithium dendrites cause short circuits and increased interface resistance, which cannot meet the actual application needs.
The composite solid electrolyte with Ce doped lithium titanate nanoribbon is combined with the polymer electrolyte as an inorganic filler to form a one-dimensional band structure and cross-form a three-dimensional network structure. It is prepared by solution casting method to enhance ionic conductivity and mechanical strength.
The prepared composite solid electrolyte has excellent ionic conductivity, electrochemical stability and mechanical properties, improving the safety and performance of lithium-ion batteries.
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Figure CN120453472A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of lithium-ion batteries, and in particular to a composite solid electrolyte and an all-solid-state lithium battery cell. Background Art
[0002] Lithium-ion batteries, due to their long cycle life and high energy density, have been widely used in electronics, energy storage, automotive, and other fields. Traditional lithium-ion batteries typically use liquid organic electrolytes, which pose risks such as explosion and flammability, significantly reducing the safety of secondary batteries. Furthermore, liquid organic electrolytes also present problems such as lithium dendrites causing short circuits and increased interfacial resistance, making them unsuitable for practical applications. Compared to liquid electrolytes, solid-state electrolytes offer advantages such as improved safety, high energy density, excellent electrochemical stability, long cycle life, and good low-temperature performance, and have garnered widespread attention.
[0003] Solid-state electrolytes are divided into three categories: inorganic solid electrolytes, polymer solid electrolytes, and composite solid electrolytes. Composite solid electrolytes are generally composed of inorganic fillers and polymer solid electrolytes. They combine the advantages of inorganic solid electrolytes and organic solid electrolytes, with higher ionic conductivity, good flexibility, stability, safety, and assembly flexibility. These advantages make composite solid electrolytes have broad application prospects in various electrochemical fields such as lithium-ion batteries, sodium-ion batteries, and fuel cells. At the same time, the research and development of composite solid electrolytes will also provide more possibilities for improving the performance and ensuring the safety of electrochemical devices. In composite solid electrolytes, the material and structure of the inorganic filler directly affect the ionic conductivity, mechanical properties, etc. of the electrolyte. Therefore, optimizing the inorganic filler is one of the important directions for improving the performance of solid electrolytes.
[0004] The purpose of the present invention is to obtain a composite solid electrolyte with excellent ionic conductivity, high electrochemical stability and good mechanical properties by optimizing the inorganic filler in the composite solid electrolyte. Summary of the Invention
[0005] In order to achieve the above object, the present invention provides the following technical solutions:
[0006] A composite solid electrolyte is prepared by weighing 30-60 parts of a polymer electrolyte, 30-40 parts of an inorganic filler, and 10-20 parts of a lithium salt in an organic solvent, mixing them uniformly, and casting the mixture into a mold using a solution casting method. The mixture is then dried in a drying oven to obtain a composite solid electrolyte membrane.
[0007] Among them, the inorganic filler is Ce-doped lithium titanate, and its preparation process is as follows:
[0008] A. Adding a soluble lithium source, titanium source, and Ce source into ethylene glycol in a certain molar ratio and mixing them by ultrasonication to form a solution 1;
[0009] B. adding cetyltrimethylammonium bromide to solution 1 and continuing ultrasonic mixing to obtain solution 2;
[0010] C. After transferring solution 2 into a high-pressure reactor, placing it in a microwave reactor to react for a certain period of time to obtain a Ce-lithium titanate precursor;
[0011] D. Wash and dry the Ce-lithium titanate precursor and then heat and calcine it to obtain the Ce-lithium titanate material.
[0012] Furthermore, the molar ratio of the lithium source, the titanium source, the Ce source, and the hexadecyltrimethylammonium bromide is 0.8:1:(0.01-0.05):(0.5-1).
[0013] Furthermore, the reaction temperature of the microwave reactor is 150-180° C.; and the reaction time is selected to be 1-2 h.
[0014] Furthermore, the calcination temperature is 300-500 degrees Celsius, the calcination time is 1-3 hours, and the calcination atmosphere is air atmosphere.
[0015] Furthermore, the ultrasonic mixing power is 50-150w.
[0016] Furthermore, solution 2 accounts for 60-80% of the volume of the autoclave.
[0017] Furthermore, the polymer electrolyte is PEO or PVDF.
[0018] Furthermore, the lithium salt includes one or more of lithium perchlorate, lithium bis(trifluoromethylsulfonyl)imide, and lithium hexafluorophosphate.
[0019] Furthermore, the lithium source is selected from lithium chloride or lithium nitrate; the titanium source is selected from tetrabutyl titanate or isopropyl titanate; and the Ce source is selected from cerium nitrate.
[0020] Furthermore, the organic solvent is selected from N,N-dimethylacetamide.
[0021] The present invention assembles the composite solid electrolyte prepared above with positive and negative electrodes to obtain an all-solid-state battery cell.
[0022] Compared with the prior art, the present invention can achieve the following technical effects:
[0023] The present invention uses Ce-doped lithium titanate nanoribbon structures as inorganic fillers for composite solid electrolytes. Ce-doped lithium titanate has high lithium ion conductivity, and the one-dimensional ribbon structure can further form continuous ion conduction channels, thereby improving the ion conductivity of lithium-ion batteries. In addition, the one-dimensional ribbon structure can cross to form a three-dimensional network structure, thereby serving as a supporting skeleton to improve the mechanical strength of the composite solid electrolyte. The composite solid electrolyte prepared by the present invention has a simple preparation process, good ionic conductivity, excellent electrochemical stability and good mechanical strength, and has good application prospects and practical value. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is a scanning electron microscope image of Ce-doped lithium titanate prepared in the present invention. DETAILED DESCRIPTION
[0025] Example 1
[0026] Preparation of Ce-lithium titanate:
[0027] A. Add 8 mmol of lithium chloride, 10 mmol of tetrabutyl titanate, and 0.2 mmol of cerium nitrate to 60 mL of ethylene glycol and mix thoroughly with ultrasonic waves to form solution 1.
[0028] B. Add 5 mmol of hexadecyltrimethylammonium bromide to solution 1 and continue ultrasonic mixing to obtain solution 2;
[0029] C. After transferring solution 2 into an 80 mL high-pressure reactor, place it in a microwave reactor for reaction for 1 h. The reaction temperature was set to 180 degrees Celsius and the power was 300 W to obtain a Ce-lithium titanate precursor;
[0030] D. Wash the Ce-lithium titanate precursor with deionized water and anhydrous ethanol, dry it, and then heat it up and calcine it at a heating rate of 5°C / min and a calcination temperature of 400°C. Keep it warm for 1 hour to obtain the Ce-lithium titanate material.
[0031] Preparation of composite solid electrolytes:
[0032] Weigh 200 mg of polymer electrolyte PEO; 150 mg of inorganic filler Ce-lithium titanate material; 75 mg of lithium salt lithium hexafluorophosphate; dissolve them in 20 mL of N,N-dimethylacetamide; cast them into a mold using a solution casting method, and dry them to obtain a composite solid electrolyte membrane.
[0033] Example 2
[0034] Preparation of Ce-lithium titanate:
[0035] A. Add 8 mmol lithium chloride, 10 mmol tetrabutyl titanate, and 0.1 mmol cerium nitrate to 60 mL ethylene glycol and mix thoroughly with ultrasonic waves to form solution 1.
[0036] B. Add 6 mmol hexadecyltrimethylammonium bromide to solution 1 and continue ultrasonic mixing to obtain solution 2;
[0037] C. After transferring solution 2 into an 80 mL high-pressure reactor, place it in a microwave reactor for reaction for 1 h. The reaction temperature was set to 180 degrees Celsius and the power was 300 W to obtain a Ce-lithium titanate precursor;
[0038] D. Wash the Ce-lithium titanate precursor with deionized water and anhydrous ethanol, dry it, and then heat it up and calcine it at a heating rate of 5°C / min and a calcination temperature of 400°C. Keep it warm for 1 hour to obtain the Ce-lithium titanate material.
[0039] Preparation of composite solid electrolytes:
[0040] Weigh 200 mg of polymer electrolyte PEO; 150 mg of inorganic filler Ce-lithium titanate material; 75 mg of lithium salt lithium hexafluorophosphate; dissolve them in 20 mL of N,N-dimethylacetamide; cast them into a mold using a solution casting method, and dry them to obtain a composite solid electrolyte membrane.
[0041] Example 3
[0042] Preparation of Ce-lithium titanate:
[0043] A. Add 8 mmol lithium chloride, 10 mmol tetrabutyl titanate, and 0.3 mmol cerium nitrate to 60 mL ethylene glycol and mix thoroughly with ultrasonic waves to form solution 1.
[0044] B. Add 6 mmol hexadecyltrimethylammonium bromide to solution 1 and continue ultrasonic mixing to obtain solution 2;
[0045] C. After transferring solution 2 into an 80 mL high-pressure reactor, the mixture was placed in a microwave reactor for reaction for 1 h. The reaction temperature was set at 160 degrees Celsius and the power was 400 W to obtain a Ce-lithium titanate precursor.
[0046] D. Wash the Ce-lithium titanate precursor with deionized water and anhydrous ethanol, dry it, and then heat it up and calcine it at a heating rate of 3°C / min and a calcination temperature of 400°C. Keep it warm for 1 hour to obtain the Ce-lithium titanate material.
[0047] Preparation of composite solid electrolytes:
[0048] Weigh 200 mg of polymer electrolyte PEO; 150 mg of inorganic filler Ce-lithium titanate material; 75 mg of lithium salt lithium hexafluorophosphate; dissolve them in 20 mL of N,N-dimethylacetamide; cast them into a mold using a solution casting method, and dry them to obtain a composite solid electrolyte membrane.
[0049] Comparative Example 1
[0050] Preparation of lithium titanate:
[0051] A. Add 8 mmol lithium chloride and 10 mmol tetrabutyl titanate to 60 mL ethylene glycol and mix thoroughly by ultrasonication to form solution 1.
[0052] B. Add 6 mmol hexadecyltrimethylammonium bromide to solution 1 and continue ultrasonic mixing to obtain solution 2;
[0053] C. After transferring solution 2 into an 80 mL high-pressure reactor, place it in a microwave reactor for reaction for 1 h. The reaction temperature is set to 180 degrees Celsius and the power is 300 W to obtain a lithium titanate precursor;
[0054] D. Wash the lithium titanate precursor with deionized water and anhydrous ethanol, dry it, and then heat it up and calcine it at a heating rate of 5°C / min and a calcination temperature of 400°C to obtain the lithium titanate material.
[0055] Preparation of composite solid electrolytes:
[0056] Weigh 200 mg of polymer electrolyte PEO; 150 mg of inorganic filler lithium titanate material; 75 mg of lithium hexafluorophosphate; dissolve them in 20 mL of N,N-dimethylacetamide; cast them into a mold using a solution casting method, and dry them to obtain a composite solid electrolyte membrane.
[0057] Comparative Example 2
[0058] A. Add 8 mmol lithium chloride, 10 mmol tetrabutyl titanate, and 0.2 mmol cerium nitrate to 60 mL deionized water and mix thoroughly with ultrasonic waves to form solution 1.
[0059] B. Add 5 mmol hexadecyltrimethylammonium bromide to solution 1 and continue ultrasonic mixing to obtain solution 2;
[0060] C. After transferring solution 2 into an 80 mL high-pressure reactor, place it in a microwave reactor for reaction for 1 h. The reaction temperature was set to 180 degrees Celsius and the power was 300 W to obtain a Ce-lithium titanate precursor;
[0061] D. Wash the Ce-lithium titanate precursor with deionized water and anhydrous ethanol, dry it, and then heat it up and calcine it at a heating rate of 5°C / min and a calcination temperature of 400°C. Keep it warm for 1 hour to obtain the Ce-lithium titanate material.
[0062] Preparation of composite solid electrolytes:
[0063] Weigh 200 mg of polymer electrolyte PEO; 150 mg of inorganic filler Ce-lithium titanate material; 75 mg of lithium salt lithium hexafluorophosphate; dissolve them in 20 mL of N,N-dimethylacetamide; cast them into a mold using a solution casting method, and dry them to obtain a composite solid electrolyte membrane.
[0064] Comparative Example 3
[0065] Preparation of Ce-lithium titanate:
[0066] A. Add 8 mmol lithium chloride, 10 mmol tetrabutyl titanate, and 0.2 mmol cerium nitrate to 60 mL ethylene glycol and mix thoroughly with ultrasonic waves to form solution 1.
[0067] B. Add 5 mmol hexadecyltrimethylammonium bromide to solution 1 and continue ultrasonic mixing to obtain solution 2;
[0068] C. After transferring solution 2 into an 80 mL autoclave, the mixture was placed in a conventional hydrothermal oven for reaction for 1 h at a reaction temperature of 180°C to obtain a Ce-lithium titanate precursor.
[0069] D. Wash the Ce-lithium titanate precursor with deionized water and anhydrous ethanol, dry it, and then heat it up and calcine it at a heating rate of 5°C / min and a calcination temperature of 400°C. Keep it warm for 1 hour to obtain the Ce-lithium titanate material.
[0070] Preparation of composite solid electrolytes:
[0071] Weigh 200 mg of polymer electrolyte PEO; 150 mg of inorganic filler Ce-lithium titanate material; 75 mg of lithium salt lithium hexafluorophosphate; dissolve them in 20 mL of N,N-dimethylacetamide; cast them into a mold using a solution casting method, and dry them to obtain a composite solid electrolyte membrane.
[0072] Comparative Example 4
[0073] Preparation of Ce-lithium titanate:
[0074] A. Add 8 mmol lithium chloride, 10 mmol tetrabutyl titanate, and 0.2 mmol cerium nitrate to 60 mL ethylene glycol and mix thoroughly with ultrasonic waves to form solution 1.
[0075] B. Solution 1 was transferred to an 80 mL high-pressure reactor, and then placed in a microwave reactor for reaction for 1 h. The reaction temperature was set at 180 degrees Celsius and the power was 300 W to obtain a Ce-lithium titanate precursor.
[0076] C. Wash the Ce-lithium titanate precursor with deionized water and anhydrous ethanol, dry it, and then heat it at a rate of 5°C / min, at a calcination temperature of 400°C, and keep it warm for 1 hour to obtain the Ce-lithium titanate material.
[0077] Preparation of composite solid electrolytes:
[0078] Weigh 200 mg of polymer electrolyte PEO; 150 mg of inorganic filler Ce-lithium titanate material; 75 mg of lithium salt lithium hexafluorophosphate; dissolve them in 20 mL of N,N-dimethylacetamide; cast them into a mold using a solution casting method, and dry them to obtain a composite solid electrolyte membrane.
[0079] All-solid-state battery cell assembly:
[0080] Positive electrode preparation: Weigh 4g of ternary material NCM811, 0.5g of superconducting carbon black and 0.5g of PVDF and mix them evenly to obtain a positive electrode slurry, which is then applied to the current collector to obtain the positive electrode of the battery cell;
[0081] The composite solid electrolytes and lithium sheets prepared in Examples 1-3 and Comparative Examples 1-4 were assembled into lithium-ion batteries to obtain all-solid-state batteries, and the test performance was as follows.
[0082] Table 1: Performance Test
[0083]
[0084] As can be seen from Table 1 above, the ionic conductivity, first discharge capacity and cycle retention rate of Examples 1-3 are all better than those of Comparative Examples 1-4. From the comparison between Comparative Example 1 and Example 1, it can be seen that the introduction of Ce affects the ionic conductivity, thereby affecting the electrochemical performance; and in Comparative Examples 2-3, after changing the preparation conditions of Ce-lithium titanate, it was found that the formed materials were agglomerated blocks or spheres, and the agglomerated blocks or spheres could not efficiently form ion shuttle channels and form a high-strength skeleton structure, which directly led to a decrease in electrolyte performance.
Claims
1. A composite solid electrolyte, characterized in that The preparation method is as follows: Weigh 30-60 parts of polymer electrolyte, 30-40 parts of inorganic filler, and 10-20 parts of lithium salt according to the mass ratio, dissolve them in an organic solvent, mix them evenly, cast them into a mold using a solution casting method, and place them in a drying oven to dry, thereby obtaining a composite solid electrolyte membrane; Among them, the inorganic filler is Ce-doped lithium titanate, and its preparation process is as follows: A. Add lithium source, titanium source and Ce source to ethylene glycol and mix them by ultrasonication to form solution 1; B. adding cetyltrimethylammonium bromide to solution 1 and continuing ultrasonic mixing to obtain solution 2; C. After transferring solution 2 into a high-pressure reactor, placing it in a microwave reactor for reaction to obtain a Ce-lithium titanate precursor; D. Wash and dry the Ce-lithium titanate precursor and then heat and calcine it to obtain Ce-doped lithium titanate material.
2. A composite solid electrolyte according to claim 1, characterized in that: The molar ratio of the lithium source, the titanium source, the Ce source and the hexadecyltrimethylammonium bromide is 0.8:1:(0.01-0.05):(0.5-1).
3. A composite solid electrolyte according to claim 1, characterized in that: The reaction temperature of the microwave reactor is 150-180°C; the reaction time is selected to be 1-2h.
4. A composite solid electrolyte according to claim 1, characterized in that: The calcination temperature is 300-500 degrees Celsius, the calcination time is 1-3 hours, and the calcination atmosphere is air atmosphere.
5. A composite solid electrolyte according to claim 1, characterized in that: The ultrasonic mixing power of steps A and B is 50-150W; solution 2 accounts for 60-80% of the volume of the high-pressure reactor.
6. A composite solid electrolyte according to claim 1, characterized in that: The polymer electrolyte is PEO or PVDF.
7. A composite solid electrolyte according to claim 1, characterized in that: The lithium salt includes one or more of lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, and lithium hexafluorophosphate.
8. A composite solid electrolyte according to claim 1, characterized in that: The lithium source is selected from lithium chloride or lithium nitrate; the titanium source is selected from tetrabutyl titanate or isopropyl titanate; and the Ce source is selected from cerium nitrate.
9. An all-solid-state battery cell, characterized in that: The composite solid electrolyte prepared according to any one of claims 1 to 8 is assembled with positive and negative electrodes to obtain an all-solid-state battery cell.