A carbon nano - horn inorganic filler composite solid electrolyte, its preparation method and application

Abstract

The present invention discloses a carbon nano - horn inorganic filler composite solid electrolyte, its preparation method and application, which relates to the technical field of solid - state batteries. Its raw materials include a polymer, carbon nano - horns, and an alkali metal salt. The carbon nano - horns are prepared by a direct - current arc plasma method; the polymer is poly(vinylidene fluoride - hexafluoropropylene) (PVDF - HFP); the alkali metal salt is sodium bis(fluorosulfonyl)imide or lithium bis(fluorosulfonyl)imide. The present invention first introduces carbon nano - horns with a high specific surface area into the solid electrolyte, aiming to utilize its high specific surface area and defective structure to improve the ionic conductivity of the polymer solid electrolyte. Through its unique structural characteristics, it can provide more ion - transport channels in the composite material and enhance the mobility of lithium ions. The carbon nano - horn inorganic filler composite solid electrolyte exhibits good mechanical properties and a thickness as low as 15 μm, and the ionic conductivity can reach 0.87 mS / cm; when it is used in a solid - state battery, it shows good rate and cycling performance.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state batteries, and particularly to a carbon nano-angle inorganic filler composite solid electrolyte, a preparation method thereof, and an application thereof. Background Art

[0002] Solid electrolytes have attracted much attention in lithium-ion batteries and other electrochemical energy storage devices due to their superior safety and stability. Compared with traditional liquid electrolytes, solid electrolytes have the advantages of being non-flammable, non-leaking, and having high chemical stability, so they show great potential in improving the safety performance and extending the service life of batteries. However, existing solid electrolytes, especially polymer-based solid electrolytes, usually have problems such as low ionic conductivity and insufficient mechanical properties, which limit their wide application in high-performance batteries.

[0003] In the research of solid electrolytes, in order to improve the ionic conductivity and mechanical properties, researchers have tried to introduce various inorganic fillers. However, the introduction of these fillers often causes phase interface problems in the composite material, affecting the overall performance of the electrolyte. To overcome these challenges, the introduction of new materials has become an important direction for improving the performance of solid electrolytes.

[0004] For example, CN100405648C polymer film, thin film electrode assembly for fuel cells, and fuel cell system containing the same, but there are problems of complex preparation process and high cost; CN111164813A polymer electrolyte membrane, a preparation method thereof, and a membrane electrode assembly including the polymer electrolyte membrane, the filler used is expensive, which is not conducive to popularization.

[0005] Therefore, it is urgent to introduce an inorganic filling material with low cost and simple preparation process, and it can greatly improve the physical and chemical properties of the electrolyte. Summary of the Invention

[0006] The purpose of the present invention is to provide a carbon nano-angle inorganic filler composite solid electrolyte, a preparation method thereof, and an application thereof, so as to solve the problem that existing filling materials cannot balance cost, manufacturing process, and performance.

[0007] The solution of the present invention is as follows:

[0008] A carbon nano-angle inorganic filler composite solid electrolyte, comprising the following raw materials in parts by weight:

[0009] Polymer 10 parts;

[0010] Alkali metal salt 5 parts;

[0011] Carbon nano-angle aggregates 0.1 - 1 part.

[0012] As a preferred technical solution, the polymer is polyvinylidene fluoride - hexafluoropropylene (PVDF - HFP).

[0013] As a preferred technical solution, the carbon nano - horns are prepared by a direct - current arc plasma method.

[0014] As a preferred technical solution, the direct - current arc plasma method is as follows: Using pure graphite rods as the anode and cathode, the diameter of each graphite rod is 10 mm, the distance between the two electrodes is 1 mm, the anode and cathode are placed vertically. After the arc furnace is evacuated to a vacuum degree of 3 Pa, nitrogen with a pressure of 70 KPa is filled and then the arc is started. The direct - current arc discharge current is 220 A, the discharge time is 5 min, and the carbon nano - horns are obtained by collecting the deposits on the inner wall of the reaction chamber.

[0015] As a preferred technical solution, the density of the carbon nano - horns is increased to obtain carbon nano - horn aggregates.

[0016] As a preferred technical solution, when the carbon nano - horn inorganic filler composite solid electrolyte is used in a sodium - based battery, the alkali metal salt is sodium bis(fluorosulfonyl)imide.

[0017] As a preferred technical solution, when the carbon nano - horn inorganic filler composite solid electrolyte is used in a lithium - based battery, the alkali metal salt is lithium bis(fluorosulfonyl)imide.

[0018] In the technology of the present invention, taking advantage of the large specific surface area and many defects of the carbon nano - horns, the interface between the polymer and the carbon nano - horns can provide a channel for ion transport, so that the ionic conductivity of the obtained composite solid electrolyte can reach 0.87×10 – 3 S / cm.

[0019] The present invention also discloses a method for preparing a carbon nano - horn inorganic filler composite solid electrolyte, which includes the following steps:

[0020] 1) Adding carbon nano - horns into an ethanol solution for pretreatment to increase the density of the carbon nano - horns and obtain carbon nano - horn aggregates;

[0021] 2) Measuring acetone and N,N - dimethylacetamide and adding them to a beaker for mixing as a solvent, adding 0.1 - 1 part of the carbon nano - horn aggregates, 10 parts of the polymer and 5 parts of the alkali metal salt obtained in step 1) into the beaker and stirring evenly to obtain a precursor slurry;

[0022] 3) Uniformly coating the precursor slurry obtained in 2) onto an insulating plate for solvent evaporation; after the surface solvent evaporation is completed, putting it into a drying oven for drying to obtain the carbon nano - horn inorganic filler composite solid electrolyte.

[0023] As a preferred technical solution, the pretreatment in 1) is as follows:

[0024] a. Mix the ethanol and carbon nano - horns at a mass ratio of 18 - 20:1, and ultrasonicate for 30 - 45 min to obtain a carbon nano - horn ethanol slurry;

[0025] b. Place the carbon nano - horn ethanol slurry obtained in a in a vacuum drying oven and dry for 4 - 6 h to obtain carbon nano - horn aggregates.

[0026] As a preferred technical solution, the solvent in 2) is prepared by mixing acetone and N,N - dimethylacetamide at a volume ratio of 1:1 - 1.5, and the amount of the solvent is 30 - 35 parts by mass.

[0027] The present invention also discloses an application of a carbon nano - horn inorganic filler composite solid electrolyte. The carbon nano - horn inorganic filler composite solid electrolyte is assembled with the positive and negative electrodes into a battery.

[0028] Advantages of the present invention:

[0029] The carbon nano - horn inorganic filler composite solid electrolyte of the present invention is composed of a polymer, carbon nano - horns and an alkali metal salt. It realizes the application of carbon nano - horns in the composite solid electrolyte for the first time, aiming to utilize its high specific surface area and defect structure to improve the ionic conductivity of the polymer solid electrolyte. Through its unique structural characteristics, it can provide more ion transport channels in the composite material and enhance the mobility of lithium ions. At the same time, the introduction of carbon nano - horns can enhance the mechanical strength and thermal stability of the composite material, providing guarantee for the efficient operation of the solid electrolyte.

[0030] 1) Improve ionic conductivity: By introducing carbon nano - horns, the composite solid electrolyte utilizes the high specific surface area and surface defect structure of carbon nano - horns to provide more ion transport channels, effectively enhancing the mobility of ions in the electrolyte, thus significantly improving the ionic conductivity of the solid electrolyte.

[0031] 2) Optimize interfacial compatibility: The composite solid electrolyte of the present invention can improve the interfacial compatibility between the polymer matrix and the inorganic filler by adding carbon nano - horns, reduce the interfacial impedance, and improve the overall electrochemical performance of the composite material. The high surface activity of carbon nano - horns helps to form a more stable interface, thus enhancing the charge - discharge performance and cycle stability of the battery.

[0032] 3) Simple preparation method: The preparation method of the present invention is simple and easy to implement. It adopts conventional solution coating method and drying process, without complex equipment, is easy to realize large - scale production, and has high industrial application prospects.

[0033] 4) Ethanol makes the carbon nano - horns more aggregated, and the solvent enables the carbon nano - horns to be fully mixed with the polymer and the alkali metal salt to form a uniform composite material, making its performance better. This composite solid electrolyte can be widely applied in sodium - based and lithium - based batteries, providing excellent electrochemical performance and stability. Description of the Drawings

[0034] Figure 1 It is the ionic conductivity graph of Examples 1 to 5 and Comparative Example 1 of the present invention;

[0035] Figure 2 It is the interfacial scanning electron microscopy image of Example 1 of the present invention;

[0036] Figure 3 It is the cycling performance graph of Comparative Example 1 at a current density of 1C;

[0037] Figure 4 It is the cycling performance graph of Example 2 at 1C (for the first 100 cycles) and 10C. Detailed Description of the Invention

[0038] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0039] The following embodiments only further illustrate the present invention in detail, but do not constitute any limitation to the present invention; this experiment aims to verify the influence of different carbon nano - horn contents on the performance of poly(vinylidene fluoride - hexafluoropropylene) - based composite solid electrolytes. Sodium bis(fluorosulfonyl)imide is uniformly selected as the alkali metal salt in this experiment. The preparation of all embodiments is carried out according to the preparation method of the present invention.

[0040] Example 1

[0041] Preparation of a carbon nano - horn inorganic filler composite solid electrolyte containing 0.2 parts of carbon nano - horns, specifically:

[0042] Preparation of carbon nano - horns:

[0043] Using pure graphite rods as the anode and cathode, the diameter of the graphite rods is 10 mm, the distance between the two electrodes is 1 mm, the anode and cathode are placed vertically, after the arc furnace is pumped to a vacuum of 3 Pa, nitrogen is filled to 70 KPa and then the arc is started, the DC arc discharge current is 220 A, and the discharge is for 5 minutes. The sediment on the inner wall of the reaction chamber is collected to obtain carbon nano - horns.

[0044] Preparation of carbon nano - horn - based composite solid electrolyte:

[0045] 1) First, mix carbon nano - horns and ethanol at a mass ratio of 20:1 and ultrasonically treat for 30 minutes to obtain a carbon nano - horn ethanol slurry.

[0046] 2) Place the above - mentioned carbon nano - horn ethanol slurry in a vacuum drying oven and dry for 6 hours to obtain carbon nano - horn aggregates.

[0047] 3) Measure acetone and N,N-dimethylacetamide and mix them in a volume ratio of 1:1 to obtain a solvent. Mix well according to the mass ratio of the total mass of the composite solid electrolyte components to the mass of the solvent of 1:20. Add 0.2 parts of carbon nanocone aggregates, 10 parts of poly(vinylidene fluoride-hexafluoropropylene), and 5 parts of sodium bis(fluorosulfonyl)imide to 304 parts of the solvent, and stir to obtain a uniform precursor slurry.

[0048] 4) Uniformly coat the precursor slurry on an insulating board, and perform solvent evaporation. After the surface solvent evaporation is completed, put the coated film into a drying oven for drying to obtain a carbon nanocone inorganic filler composite solid electrolyte.

[0049] Example 2: Carbon nanocone inorganic filler composite solid electrolyte containing 0.4 parts of carbon nanocones

[0050] 1) Repeat the steps in Example 1, and adjust the carbon nanocone content to 0.4.

[0051] 2) Prepare the composite solid electrolyte by the same process.

[0052] Example 3: Carbon nanocone inorganic filler composite solid electrolyte containing 0.6 carbon nanocones

[0053] 1) Repeat the steps in Example 1, and adjust the carbon nanocone content to 0.6 parts.

[0054] 2) Prepare the composite solid electrolyte by the same process.

[0055] Example 4: Carbon nanocone inorganic filler composite solid electrolyte containing 0.8 parts of carbon nanocones

[0056] 1) Repeat the steps in Example 1, and adjust the carbon nanocone content to 0.8 parts.

[0057] 2) Prepare the composite solid electrolyte by the same process.

[0058] Example 5: Carbon nanocone inorganic filler composite solid electrolyte containing 1 part of carbon nanocones

[0059] 1) Repeat the steps in Example 1, and adjust the carbon nanocone content to 1 part.

[0060] 2) Prepare the composite solid electrolyte by the same process.

[0061] Example 6: Carbon nanocone inorganic filler composite solid electrolyte containing 0.1 part of carbon nanocones

[0062] 1) Repeat the steps in Example 1, and adjust the carbon nanocone content to 0.1 part.

[0063] 2) Prepare the composite solid electrolyte by the same process.

[0064] Comparative Example 1: Poly(vinylidene fluoride - hexafluoropropylene)-based solid electrolyte without carbon nanohorns

[0065] 1) When preparing the precursor slurry, no carbon nanohorns were added.

[0066] 2) 10 parts of poly(vinylidene fluoride - hexafluoropropylene) and 5 parts of sodium bis(fluorosulfonyl)imide were mixed, and the solvents were acetone and N,N - dimethylacetamide.

[0067] 3) Other operation steps were the same as those in Example 1.

[0068] Example 7

[0069] Preparation of carbon nanohorns:

[0070] Using pure graphite rods as the anode and cathode, the diameter of the graphite rods was 10 mm, the distance between the two electrodes was 1 mm, the anode and cathode were placed vertically. After the arc furnace was evacuated to a vacuum degree of 3 Pa, nitrogen with a pressure of 70 kPa was filled and then the arc was started. The direct current arc discharge current was 220 A, and the discharge lasted for 5 min. The deposits on the inner wall of the reaction chamber were collected to obtain carbon nanohorns.

[0071] Preparation of carbon nanohorn - based composite solid electrolyte:

[0072] 1) First, carbon nanohorns and ethanol were mixed at a mass ratio of 18:1 and ultrasonicated for 40 min to obtain a carbon nanohorn ethanol slurry.

[0073] 2) The above - mentioned carbon nanohorn ethanol slurry was placed in a vacuum drying oven and dried for 6 hours to obtain carbon nanohorn aggregates.

[0074] 3) Acetone and N,N - dimethylacetamide were measured and mixed at a volume ratio of 1:1.2 to prepare a solvent. The total mass of the composite solid electrolyte components and the mass of the solvent were mixed evenly at a ratio of 1:25. 0.4 part of carbon nanohorn aggregates, 10 parts of poly(vinylidene fluoride - hexafluoropropylene), and 5 parts of lithium bis(fluorosulfonyl)imide were added to 385 parts of the solvent and stirred to obtain a uniform precursor slurry.

[0075] 4) The precursor slurry was uniformly coated on an insulating plate, and solvent evaporation was carried out. After the surface solvent evaporation was completed, the coated film was placed in a drying oven and dried to obtain a carbon nanohorn inorganic filler composite solid electrolyte.

[0076] Example 8

[0077] Preparation of carbon nanohorns:

[0078] Using pure graphite rods as the anode and cathode, the diameter of the graphite rods is 10 mm, the distance between the two electrodes is 1 mm, the anode and cathode are placed vertically. After the arc furnace is pumped to a vacuum of 3 Pa, nitrogen is filled to 70 KPa and then the arc is started. The DC arc discharge current is 220 A, and the discharge lasts for 5 minutes. The carbon nano - horns are obtained by collecting the deposits on the inner wall of the reaction chamber.

[0079] Preparation of carbon nano - horn - based composite solid electrolyte:

[0080] 1) First, mix carbon nano - horns and ethanol at a mass ratio of 20:1, and perform ultrasonic treatment for 45 minutes to obtain a carbon nano - horn ethanol slurry.

[0081] 2) Place the above - mentioned carbon nano - horn ethanol slurry in a vacuum drying oven and dry it for 6 hours to obtain carbon nano - horn aggregates.

[0082] 3) Measure acetone and N,N - dimethylacetamide and mix them in a volume ratio of 1:1.5 to obtain a solvent. Mix them evenly according to the ratio of the total mass of the composite solid electrolyte components to the mass of the solvent of 1:20. Add 0.6 parts of carbon nano - horn aggregates, 10 parts of poly(vinylidene fluoride - hexafluoropropylene), and 5 parts of lithium bis(fluorosulfonyl)imide to 312 parts of the solvent, and stir to obtain a uniform precursor slurry.

[0083] 4) Uniformly coat the precursor slurry on an insulating plate, perform solvent evaporation. After the surface solvent evaporation is completed, put the coated film into a drying oven to dry, and obtain a carbon nano - horn inorganic filler composite solid electrolyte.

[0084] Performance testing

[0085] For the above - mentioned comparative examples and examples, the results of testing their ionic conductivity at room temperature are as follows:

[0086] Ionic conductivity: The ionic conductivities of Examples 1 - 5 are all significantly higher than that of Comparative Example 1. As the content of carbon nano - horns increases, the ionic conductivity gradually increases until it reaches the highest value in Example 2; after further increasing the content of carbon nano - horns (Examples 3, 4, and 5), the ionic conductivity decreases slightly but is still higher than that of Comparative Example 1. This is because carbon nano - horns are inert fillers, and excessive content will hinder ion transport.

[0087] The cross - section of Example 1 was tested using a scanning electron microscope. The thickness of the composite solid electrolyte is about 15 μm, meeting the requirements of the current battery development for thin solid electrolytes.

[0088] Furthermore, use the composite solid electrolytes of Example 2 and Comparative Example 1 to assemble Na||NaV(PO 4 ) 3The battery was tested. After introducing carbon nanohorns, the increase in the ionic conductivity of the composite solid electrolyte enabled the battery to exhibit better rate performance and cycling performance. Comparative Example 1 had a specific capacity of only 92 mAh / g at a current density of 1C, and the battery failed after three cycles; while the battery of Example 2 had a specific capacity of 103 mAh / g at a current density of 1C and could cycle stably. Even when the current increased to 10C, the battery could still cycle stably. This is the beneficial effect brought about by the significant increase in ionic conductivity after the introduction of carbon nanohorns.

[0089] In summary, the carbon nanohorn inorganic filler composite solid electrolyte of the present invention exhibits excellent performance in terms of ionic conductivity, mechanical strength, and electrochemical stability. In particular, the composite material containing 0.4 to 0.6 parts of carbon nanohorns shows the best performance.

[0090] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A carbon nanohorn inorganic filler composite solid electrolyte, characterized in that: The invention comprises the following raw materials in parts by weight: 10 parts of polymer; 5 parts of alkali metal salt; 0.1 to 1 part of carbon nanohorn; The polymer is polyvinylidene fluoride-hexafluoropropylene; The carbon nanohorns are prepared by a direct current arc plasma method; the direct current arc plasma method comprises: using pure graphite rods as anodes and cathodes, the diameter of the graphite rods is 10 mm, the distance between the two electrodes is 1 mm, the cathodes and cathodes are placed vertically, the arc furnace is evacuated to a vacuum degree of 3 Pa, and then filled with 70 KPa of nitrogen to start the arc, the direct current arc discharge current is 220 A, the discharge time is 5 min, and the sediment on the inner wall of the reaction chamber is collected to obtain the carbon nanohorns; The method for preparing the carbon nanohorn inorganic filler composite solid electrolyte comprises the following steps: 1) Pre-treating the carbon nanohorns by adding them into an ethanol solution to increase the density of the carbon nanohorns and obtain carbon nanohorn aggregates; 2) acetone and N,N-dimethylacetamide are weighed and added to a beaker to mix as a solvent, and 0.1 to 1 part of the carbon nanohorn aggregates, 10 parts of the polymer and 5 parts of the alkali metal salt in step 1) are added to the beaker and stirred to obtain a precursor slurry; 3) uniformly coating the precursor slurry described in 2) onto an insulating plate to evaporate the solvent; after the surface solvent is evaporated, the plate is placed in a drying oven for drying to obtain a carbon nanohorn inorganic filler composite solid electrolyte; The preprocessing steps in 1) are: a. mixing the ethanol and the carbon nanohorns in a mass ratio of 18 to 20:1, and performing ultrasonication for 30 to 45 minutes to obtain a carbon nanohorn ethanol slurry; b. Place the carbon nanohorn ethanol slurry in a vacuum drying oven and dry it for 4 to 6 hours to obtain carbon nanohorn aggregates.

2. A carbon nanohorn inorganic filler composite solid electrolyte according to claim 1, characterized in that: When the carbon nanohorn inorganic filler composite solid electrolyte is used in a sodium-based battery, the alkali metal salt is sodium bis(fluorosulfonyl)imide.

3. The carbon nanohorn inorganic filler composite solid electrolyte according to claim 1, characterized in that: When the carbon nanohorn inorganic filler composite solid electrolyte is used in a lithium-based battery, the alkali metal salt is lithium bis(fluorosulfonyl)imide.

4. The carbon nanohorn inorganic filler composite solid electrolyte according to claim 1, characterized in that: The solvent in 2) is prepared by mixing acetone and N,N-dimethylacetamide in a volume ratio of 1:1 to 1.5, and the amount of the solvent used is 30 to 35 parts by mass.

5. An application of a carbon nanohorn inorganic filler composite solid electrolyte, characterized in that: The carbon nanohorn inorganic filler composite solid electrolyte according to any one of claims 1 to 4 is assembled with positive and negative electrodes into a battery.

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