CN115057443A - Silicon electrode material with good cycle stability and preparation method thereof - Google Patents
Silicon electrode material with good cycle stability and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a silicon electrode material with good cycling stability and a preparation method thereof, and the preparation method comprises the following processes: (1) reacting gamma-glycidoxypropyltrimethoxysilane with phytic acid; introducing and reacting with aminoquinoline, and complexing with copper ions to obtain a complex; mixing tetraethoxysilane, water and ethanol, adding magnesium powder and a complex, and gelling to prepare silicon dioxide aerogel; (2) mixing silicon dioxide aerogel and magnesium powder, and performing heat treatment; and soaking in hydrochloric acid, and drying to obtain the silicon electrode material. According to the preparation process, after the silicon dioxide is subjected to magnesiothermic reduction in cooperation with the silicon dioxide, the complex and the silicon substrate form co-doping, and the co-doping is used as a framework to limit and support the silicon substrate, so that the volume expansion of the silicon substrate in the battery circulation process is prevented, and the circulation stability of the silicon electrode material is effectively improved; and simultaneously, the carbon structure of the silicon electrode material is adjusted by the steric hindrance of the phytic acid, the specific capacitance of the silicon electrode material is improved, and the electrochemical performance is further improved.
Description
Technical Field
The invention relates to the technical field of silicon batteries, in particular to a silicon electrode material with good cycle stability and a preparation method thereof.
Background
The lithium ion battery has the advantages of high energy density, long service life, light weight and the like, and is widely applied to the fields of electric vehicles, electronic products and the like. As a battery component, the performance and the structure of a negative electrode material are important influence factors influencing the capacity and the electrochemical cycle performance of the lithium ion battery; the silicon electrode material is one of the cathode materials. Silicon is the substance with the highest lithium storage capacity and is the research focus and hot spot of the lithium ion battery cathode material; however, the single silicon particle structure can have serious volume expansion in the lithium ion battery charging and discharging lithiation process, so that the crystal structure can be damaged, and the silicon electrode material can collapse and fall off from the surface of the current collector along with the circulation, so that the capacity of the manufactured lithium ion battery can be rapidly attenuated in the circulation process. Therefore, a silicon electrode material with good cycling stability and a preparation method thereof are provided.
Disclosure of Invention
The invention aims to provide a silicon electrode material with good cycling stability and a preparation method thereof, so as to solve the problems in the background technology.
In order to solve the technical problems, the invention provides the following technical scheme: a preparation method of a silicon electrode material with good cycle stability comprises the following processes:
(1) preparation of silica aerogel:
reacting gamma-glycidoxypropyltrimethoxysilane with phytic acid; introducing and reacting with aminoquinoline, and complexing with copper ions to obtain a complex;
mixing ethyl orthosilicate, water and ethanol, adding magnesium powder and a complex, and gelling to prepare silicon dioxide aerogel;
(2) preparation of silicon electrode material:
mixing silicon dioxide aerogel and magnesium powder, and carrying out heat treatment in an argon atmosphere; and after cooling, soaking in hydrochloric acid, and drying to obtain the silicon electrode material.
Further, the method comprises the following processes:
(1) preparation of silica aerogel:
2.1. stirring gamma-glycidyl ether oxypropyltrimethoxysilane at the rotating speed of 300-500 rpm, heating to 50-75 ℃, adding catalysts N, N-dimethylformamide and phytic acid, and reacting at constant temperature for 3-5 hours to obtain a compound I;
furthermore, the mass ratio of the gamma-glycidoxypropyltrimethoxysilane to the phytic acid to the N, N-dimethylformamide is (2.2-4.0) to 1 (0.09-0.15).
Adding an alcohol aqueous solution and N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane into a compound I, mixing, stirring at the rotating speed of 500-800 rpm, adding hydrochloric acid to adjust the pH value of a system to 3.4-4.8, standing and hydrolyzing for 1-3 hours to obtain a compound II;
further, the mol ratio of the compound I to the N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane is (0.8-1.2) to 1;
the proportion of the compound I and the alcohol-water solution is 8-12/100 mL; the mass ratio of water to ethanol in the alcohol-water solution is 1 (12-18).
Under the protection of argon, mixing 1, 2-dichloroethane and absolute ethyl alcohol, adding 2-aldehyde-8- (N-acetyl) aminoquinoline and a compound II, stirring at room temperature for 60-90 min, adding sodium triacetoxyborohydride, and reacting for 12-15 h to obtain a compound III;
further, the molar ratio of the compound II, 2-aldehyde-8- (N-acetyl) aminoquinoline and sodium triacetoxyborohydride is (3.8-4.2) to 1 (3.8-4.2);
the proportion of the 2-aldehyde-8- (N-acetyl) aminoquinoline to the mixed solvent of 1, 2-dichloroethane and absolute ethyl alcohol is (6-8) g/100 mL;
the volume ratio of the 1, 2-dichloroethane to the absolute ethyl alcohol is (3-4) to 1.
Mixing absolute ethyl alcohol, deionized water and diethyl ether, adding the compound III, stirring, adding hydrochloric acid, and continuing stirring for 30-60 min; carrying out reduced pressure distillation, filtering, washing and drying the precipitate to obtain the aminoquinoline derivative;
further, the volume ratio of the absolute ethyl alcohol to the deionized water to the diethyl ether is (3-5) to (6-8) 1;
the mass ratio of the compound III to the hydrochloric acid is 1 (8-12); the concentration of the hydrochloric acid is 1.5-2.0 mol/L.
Mixing the aminoquinoline derivative and copper sulfate, adding a Tris-HCl/NaCl buffer solution (pH is 7.4), and stirring at the rotating speed of 300-500 rpm for 60-90 min to obtain a complex.
Furthermore, the mol ratio of the aminoquinoline derivative to the copper sulfate is 1 (6-10), and the ratio of the copper sulfate to the Tris-HCl/NaCl buffer solution is 3-5 mmol/L;
the concentration of Tris & HCl in the Tris & HCl/NaCl buffer solution is 20mmol/L, and the concentration of NaCl in the buffer solution is 150 mmol/L.
2.2. Taking ethyl orthosilicate, water and ethanol, and stirring and mixing at the temperature of 20-27 ℃; adding oxalic acid to adjust the pH of the system to 3.4-4.8, standing and hydrolyzing for 6-24 h; adding ammonia water, a complex and kh550 coupling modified magnesium powder, and adjusting the pH value of the system to 7.5-9.0; standing at room temperature to generate gel, and aging at room temperature for 7 d; and (3) soaking in normal hexane, filtering and drying to obtain the silicon dioxide aerogel.
Further, the molar ratio of the ethyl orthosilicate to the water to the ethanol is 1 (3.75-4.0) to (8.0-9.0);
the mass ratio of the ethyl orthosilicate to the complex compound to the kh550 coupling modified magnesium powder is 100 (10-20) to 7-12;
the dosage of the kh550 in the kh550 coupling modified magnesium powder is 1.5-2.0% of the mass of the magnesium powder.
(2) Preparation of silicon electrode material:
grinding silicon dioxide aerogel, dispersing in deionized water, adding sodium chloride, and drying; adding magnesium powder, uniformly mixing, heating to 680-750 ℃ at a heating rate of 5 ℃/min in an argon atmosphere, and preserving heat for 5-6 hours; cooling to room temperature; and soaking in hydrochloric acid for 6-8 hours, removing magnesium oxide and magnesium silicide in the hydrochloric acid, and drying in vacuum to obtain the silicon electrode material.
Further, the mass ratio of the magnesium powder to the silicon dioxide aerogel is (0.8-1.1): 1; the concentration of hydrochloric acid was 1M.
In the technical scheme, firstly, an epoxy group in gamma-glycidoxypropyltrimethoxysilane reacts with phosphoric acid in phytic acid; then, the siloxane structure in the reaction product, namely the compound I, is hydrolyzed and condensed with N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane; reacting the amino in the reaction product, namely a compound II, with the aldehyde in 2-aldehyde-8- (N-acetyl) aminoquinoline, and acidifying the obtained reaction product, namely a compound III, to obtain an aminoquinoline derivative; complexing the copper ions with copper ions provided by copper sulfate to obtain a complex; dispersing the complex and kh550 coupling modified magnesium powder in a silicon dioxide solution, and blending the mixture in a preparation system of silicon dioxide aerogel to prepare silicon dioxide aerogel doped with the complex and the magnesium powder; and mixing the cobalt dioxide aerogel magnesium powder, carrying out magnesium thermal reaction, and cleaning to obtain the silicon electrode material.
The coupling modified magnesium powder doped with the kh550 in the silicon dioxide aerogel can participate in magnesium thermal reaction, strengthen the reduction of the interior of the silicon dioxide aerogel, improve the internal pores of the prepared silicon electrode material, promote the lithiation reaction to move from the surface of the silicon electrode material to the interior, and improve the capacity of the prepared silicon electrode material; the complex contains elements such as copper, carbon and phosphorus, can form co-doping with a silicon substrate after being subjected to magnesiothermic reduction in cooperation with silicon dioxide, is used as a framework to limit and support the silicon substrate, relieves/prevents cracking, crushing, falling off, structural collapse and the like of a surface layer of the prepared silicon electrode material due to volume expansion in a circulation process, maintains high activity of the silicon electrode material, and effectively improves the circulation stability of the silicon electrode material; the conductivity of the prepared silicon electrode material can be improved, and the electrochemical performance of the silicon electrode material is improved; meanwhile, the carbon structure in the prepared silicon electrode material is effectively adjusted under the steric hindrance action of the phytic acid, so that the porosity and the conductivity of the silicon electrode material are improved, the contact angle is reduced, the specific capacitance is improved, and the prepared silicon electrode material can show excellent electrochemical performance.
Compared with the prior art, the invention has the following beneficial effects:
the silicon electrode material with good circulation stability and the preparation method thereof react with gamma-glycidoxypropyltrimethoxysilane and phytic acid; introducing and reacting with aminoquinoline, and complexing with copper ions to obtain a complex; introducing the magnesium powder and the silicon dioxide aerogel into a preparation system of the silicon dioxide aerogel; performing magnesiothermic reduction on the prepared silicon dioxide aerogel to obtain a silicon electrode material, and after performing magnesiothermic reduction on the silicon dioxide in cooperation, co-doping the complex and the silicon substrate to limit the silicon substrate and support the substrate as a framework, so that the volume expansion of the silicon substrate in the battery circulation process is prevented, and the circulation stability of the silicon electrode material is effectively improved; meanwhile, the carbon structure of the silicon electrode material is adjusted under the steric hindrance of the phytic acid, the specific capacitance of the prepared silicon electrode material is improved, and the electrochemical performance of the silicon electrode material is further improved.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
(1) Preparation of silica aerogel:
2.1. stirring gamma-glycidyl ether oxypropyltrimethoxysilane at the rotating speed of 300rpm, heating to 50 ℃, adding catalysts N, N-dimethylformamide and phytic acid, and reacting at constant temperature for 3 hours to obtain a compound I; the mass ratio of the gamma-glycidyl ether oxypropyl trimethoxy silane to the phytic acid to the N, N-dimethylformamide is 2.2:1: 0.09;
taking a compound I, adding an alcohol aqueous solution and N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane, mixing, stirring at the rotating speed of 500rpm, adding hydrochloric acid to adjust the pH value of a system to 4.8, standing and hydrolyzing for 1h to obtain a compound II; the mol ratio of the compound I to the N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane is 0.8: 1; the proportion of the compound I and the alcohol-water solution is 8/100 mL; the mass ratio of water to ethanol in the alcohol-water solution is 1: 12;
under the protection of argon, 1, 2-dichloroethane and absolute ethyl alcohol are mixed, 2-aldehyde-8- (N-acetyl) aminoquinoline and a compound II are added, the mixture is stirred for 60min at room temperature, sodium triacetoxyborohydride is added, and the reaction is carried out for 12h, so as to obtain a compound III; the molar ratio of the compound II to the 2-aldehyde-8- (N-acetyl) aminoquinoline to the sodium triacetoxyborohydride is 3.8:1: 3.8; the proportion of the 2-aldehyde-8- (N-acetyl) aminoquinoline to the mixed solvent of 1, 2-dichloroethane and absolute ethyl alcohol is 6g/100 mL; the volume ratio of the 1, 2-dichloroethane to the absolute ethyl alcohol is 3: 1;
mixing anhydrous ethanol, deionized water and diethyl ether, adding compound III, stirring, adding hydrochloric acid, and stirring for 30 min; carrying out reduced pressure distillation, filtering, washing and drying the precipitate to obtain the aminoquinoline derivative; the volume ratio of the absolute ethyl alcohol to the deionized water to the diethyl ether is 3:1: 6; the mass ratio of the compound III to the hydrochloric acid is 1: 8; the concentration of hydrochloric acid is 1.5 mol/L;
mixing the aminoquinoline derivative and copper sulfate, adding a Tris & HCl/NaCl buffer solution, and stirring at the rotating speed of 300rpm for 60min to obtain a complex; the mol ratio of the aminoquinoline derivative to the copper sulfate is 1:6, and the ratio of the copper sulfate to the Tris-HCl/NaCl buffer solution is 3 mmol/L;
2.2. taking ethyl orthosilicate, water and ethanol, and stirring and mixing at the temperature of 20 ℃; adding oxalic acid to adjust the pH of the system to 4.8, standing and hydrolyzing for 6 h; adding ammonia water, a complex and kh550 coupling modified magnesium powder, and adjusting the pH value of the system to 7.5; standing at room temperature to generate gel, and aging at room temperature for 7 d; soaking in n-hexane, filtering, and drying to obtain silica aerogel; the molar ratio of the ethyl orthosilicate to the water to the ethanol is 1:3.75: 8.0; the mass ratio of the ethyl orthosilicate to the complex to the kh550 coupling modified magnesium powder is 100:10: 7; the dosage of kh550 in the kh550 coupling modified magnesium powder is 1.5 percent of the mass of the magnesium powder;
(2) preparation of silicon electrode material:
grinding silicon dioxide aerogel, dispersing in deionized water, adding sodium chloride, and drying; adding magnesium powder, mixing uniformly, heating to 680 ℃ at a heating rate of 5 ℃/min in an argon atmosphere, and preserving heat for 5 hours; cooling to room temperature; soaking in hydrochloric acid for 6h, removing magnesium oxide and magnesium silicide therein, and vacuum drying to obtain silicon electrode material; the mass ratio of the magnesium powder to the silicon dioxide aerogel is 0.8: 1.
Example 2
(1) Preparation of silica aerogel:
2.1. stirring gamma-glycidyl ether oxypropyltrimethoxysilane at the rotating speed of 400rpm, heating to 62 ℃, adding catalysts N, N-dimethylformamide and phytic acid, and reacting at constant temperature for 4 hours to obtain a compound I; the mass ratio of the gamma-glycidyl ether oxypropyl trimethoxy silane to the phytic acid to the N, N-dimethylformamide is 3.0:1: 0.12;
taking a compound I, adding an alcohol aqueous solution and N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane, mixing, stirring at the rotating speed of 700rpm, adding hydrochloric acid to adjust the pH value of a system to 4.0, standing and hydrolyzing for 2 hours to obtain a compound II; the mol ratio of the compound I to the N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane is 1: 1; the proportion of the compound I and the alcohol-water solution is 10/100 mL; the mass ratio of water to ethanol in the alcohol-water solution is 1: 15;
under the protection of argon, 1, 2-dichloroethane and absolute ethyl alcohol are mixed, 2-aldehyde-8- (N-acetyl) aminoquinoline and a compound II are added, the mixture is stirred for 75min at room temperature, sodium triacetoxyborohydride is added, and the reaction is carried out for 13h, so as to obtain a compound III; the molar ratio of the compound II, 2-aldehyde-8- (N-acetyl) aminoquinoline and sodium triacetoxyborohydride is 4:1: 4; the proportion of the 2-aldehyde-8- (N-acetyl) aminoquinoline to the mixed solvent of 1, 2-dichloroethane and absolute ethyl alcohol is 7g/100 mL; the volume ratio of the 1, 2-dichloroethane to the absolute ethyl alcohol is 3.5: 1;
mixing anhydrous ethanol, deionized water and diethyl ether, adding compound III, stirring, adding hydrochloric acid, and stirring for 45 min; carrying out reduced pressure distillation, filtering, washing and drying the precipitate to obtain the aminoquinoline derivative; the volume ratio of the absolute ethyl alcohol to the deionized water to the diethyl ether is 4:1: 7; the mass ratio of the compound III to the hydrochloric acid is 1: 10; the concentration of hydrochloric acid is 1.8 mol/L;
mixing the aminoquinoline derivative and copper sulfate, adding a Tris & HCl/NaCl buffer solution, and stirring at the rotating speed of 400rpm for 75min to obtain a complex; the mol ratio of the aminoquinoline derivative to the copper sulfate is 1:8, and the ratio of the copper sulfate to the Tris-HCl/NaCl buffer solution is 4 mmol/L;
2.2. taking ethyl orthosilicate, water and ethanol, and stirring and mixing at the temperature of 24 ℃; adding oxalic acid to adjust the pH of the system to 4.0, standing and hydrolyzing for 18 h; adding ammonia water, a complex and kh550 coupling modified magnesium powder, and adjusting the pH value of the system to 8.2; standing at room temperature to generate gel, and aging at room temperature for 7 d; soaking in n-hexane, filtering, and drying to obtain silica aerogel; the molar ratio of the ethyl orthosilicate to the water to the ethanol is 1:3.84: 8.5; the mass ratio of the ethyl orthosilicate to the complex to the kh550 coupling modified magnesium powder is 100:15: 10; the dosage of kh550 in the kh550 coupling modified magnesium powder is 1.8 percent of the mass of the magnesium powder;
(2) preparation of silicon electrode material:
grinding silicon dioxide aerogel, dispersing in deionized water, adding sodium chloride, and drying; adding magnesium powder, mixing uniformly, heating to 700 ℃ at a heating rate of 5 ℃/min in an argon atmosphere, and preserving heat for 5.5 hours; cooling to room temperature; soaking in hydrochloric acid for 7h, removing magnesium oxide and magnesium silicide therein, and vacuum drying to obtain silicon electrode material; the mass ratio of the magnesium powder to the silicon dioxide aerogel is 1: 1.
Example 3
(1) Preparation of silica aerogel:
2.1. stirring gamma-glycidyl ether oxypropyltrimethoxysilane at the rotating speed of 500rpm, heating to 75 ℃, adding catalysts N, N-dimethylformamide and phytic acid, and reacting at constant temperature for 5 hours to obtain a compound I; the mass ratio of the gamma-glycidyl ether oxypropyl trimethoxy silane to the phytic acid to the N, N-dimethylformamide is 4.0:1: 0.15;
taking a compound I, adding an alcohol aqueous solution and N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane, mixing, stirring at the rotating speed of 800rpm, adding hydrochloric acid to adjust the pH value of a system to 3.4, standing and hydrolyzing for 3 hours to obtain a compound II; the mol ratio of the compound I to the N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane is 1.2: 1; the proportion of the compound I and the alcohol-water solution is 12/100 mL; the mass ratio of water to ethanol in the alcohol-water solution is 1: 18;
under the protection of argon, 1, 2-dichloroethane and absolute ethyl alcohol are mixed, 2-aldehyde-8- (N-acetyl) aminoquinoline and a compound II are added, the mixture is stirred for 90min at room temperature, sodium triacetoxyborohydride is added, and the reaction is carried out for 15h, so as to obtain a compound III; the molar ratio of the compound II, 2-aldehyde-8- (N-acetyl) aminoquinoline and sodium triacetoxyborohydride is 4.2:1: 4.2; the proportion of the 2-aldehyde-8- (N-acetyl) aminoquinoline to the mixed solvent of 1, 2-dichloroethane and absolute ethyl alcohol is 8g/100 mL; the volume ratio of the 1, 2-dichloroethane to the absolute ethyl alcohol is 4: 1;
mixing anhydrous ethanol, deionized water and diethyl ether, adding compound III, stirring, adding hydrochloric acid, and stirring for 60 min; carrying out reduced pressure distillation, filtering, washing and drying the precipitate to obtain the aminoquinoline derivative; the volume ratio of the absolute ethyl alcohol to the deionized water to the diethyl ether is 5: 1: 8; the mass ratio of the compound III to the hydrochloric acid is 1: 12; the concentration of hydrochloric acid is 2.0 mol/L;
mixing the aminoquinoline derivative and copper sulfate, adding Tris & HCl/NaCl buffer solution), and stirring at the rotating speed of 500rpm for 90min to obtain a complex; the mol ratio of the aminoquinoline derivative to the copper sulfate is 1:10, and the ratio of the copper sulfate to the Tris-HCl/NaCl buffer solution is 5 mmol/L;
2.2. taking ethyl orthosilicate, water and ethanol, and stirring and mixing at the temperature of 27 ℃; adding oxalic acid to adjust the pH value of the system to 3.4, standing and hydrolyzing for 24 h; adding ammonia water, adding the complex and kh550 coupling modified magnesium powder, and adjusting the pH value of the system to 9.0; standing at room temperature to generate gel, and aging at room temperature for 7 d; soaking in n-hexane, filtering, and drying to obtain silica aerogel; the molar ratio of the ethyl orthosilicate to the water to the ethanol is 1:4.0: 9.0; the mass ratio of the ethyl orthosilicate, the complex and the kh550 coupling modified magnesium powder is 100:20: 12; the dosage of kh550 in the kh550 coupling modified magnesium powder is 2.0 percent of the mass of the magnesium powder;
(2) preparation of silicon electrode material:
grinding silicon dioxide aerogel, dispersing in deionized water, adding sodium chloride, and drying; adding magnesium powder, mixing uniformly, heating to 750 ℃ at a heating rate of 5 ℃/min in an argon atmosphere, and keeping the temperature for 6 hours; cooling to room temperature; soaking in hydrochloric acid for 8h, removing magnesium oxide and magnesium silicide, and vacuum drying to obtain silicon electrode material; the mass ratio of the magnesium powder to the silicon dioxide aerogel is 1.1: 1.
Comparative example 1
Replacing the complex with equimolar amounts of aminoquinoline derivative; the process 2.2 is adjusted as follows:
2.2. taking tetraethoxysilane, water and ethanol, and stirring and mixing at the temperature of 20 ℃; adding oxalic acid to adjust the pH of the system to 4.8, standing and hydrolyzing for 6 h; adding ammonia water, adding aminoquinoline derivatives and kh550 coupling modified magnesium powder, and adjusting the pH value of the system to 7.5; standing at room temperature to generate gel, and aging at room temperature for 7 d; soaking in n-hexane, filtering, and drying to obtain silica aerogel;
the other processes were the same as in example 1 to obtain a silicon electrode material.
Comparative example 2
Replacing the complex by an equimolar amount of compound II; the process 2.2 is adjusted as follows:
2.2. taking ethyl orthosilicate, water and ethanol, and stirring and mixing at the temperature of 20 ℃; adding oxalic acid to adjust the pH of the system to 4.8, standing and hydrolyzing for 6 h; adding ammonia water, adding a compound II and kh550 coupling modified magnesium powder, and adjusting the pH value of the system to 7.5; standing at room temperature to generate gel, and aging at room temperature for 7 d; soaking in n-hexane, filtering, and drying to obtain silica aerogel;
the other processes were the same as in example 1 to obtain a silicon electrode material.
Comparative example 3
Replacing the complex with an equimolar amount of compound I; the process 2.2 is adjusted as follows:
2.2. taking ethyl orthosilicate, water and ethanol, and stirring and mixing at the temperature of 20 ℃; adding oxalic acid to adjust the pH of the system to 4.8, standing and hydrolyzing for 6 h; adding ammonia water, adding a compound I and kh550 coupling modified magnesium powder, and adjusting the pH value of the system to 7.5; standing at room temperature to generate gel, and aging at room temperature for 7 d; soaking in n-hexane, filtering, and drying to obtain silica aerogel;
the other process was the same as in example 1 to obtain a silicon electrode material.
Comparative example 4
Replacing the complex with equimolar amounts of copper phytate; the process 2.2 is adjusted as follows:
2.2. taking ethyl orthosilicate, water and ethanol, and stirring and mixing at the temperature of 20 ℃; adding oxalic acid to adjust the pH of the system to 4.8, standing and hydrolyzing for 6 h; adding ammonia water, adding copper phytate and kh550 coupling modified magnesium powder, and adjusting the pH value of the system to 7.5; standing at room temperature to generate gel, and aging at room temperature for 7 d; soaking in n-hexane, filtering, and drying to obtain silica aerogel;
the other process was the same as in example 1 to obtain a silicon electrode material.
Comparative example 5
Replacing the complex with an equimolar amount of phytic acid; the process 2.2 is adjusted as follows:
2.2. taking ethyl orthosilicate, water and ethanol, and stirring and mixing at the temperature of 20 ℃; adding oxalic acid to adjust the pH of the system to 4.8, standing and hydrolyzing for 6 h; adding ammonia water, phytic acid and kh550 coupling modified magnesium powder, and adjusting the pH value of the system to 7.5; standing at room temperature to generate gel, and aging at room temperature for 7 d; soaking in n-hexane, filtering, and drying to obtain silica aerogel;
the other process was the same as in example 1 to obtain a silicon electrode material.
Experiment of
Samples were prepared from the silicon electrode materials obtained in examples 1 to 3 and comparative examples 1 to 5, and the properties thereof were measured and the measurement results were recorded:
mixing a silicon electrode material, a conductive agent acetylene black and a binder polyvinylidene fluoride according to a mass ratio of 70:15:15, adding a solvent N-methylpyrrolidone, coating on a copper foil, and performing vacuum drying at 90 ℃ for 12 hours to prepare a wafer with the diameter of 8 mm; a lithium metal sheet is taken as a reference electrode, a polypropylene microporous membrane is taken as a diaphragm, and 1M LiPF6/EC + DMC + DEC (volume ratio of 1:1:1) is taken as electrolyte.
From the data in the table above, it is clear that the following conclusions can be drawn:
the silicon electrode materials obtained in examples 1 to 3 were compared with the silicon electrode materials obtained in comparative examples 1 to 5, and the results of the measurements were found to be,
compared with the comparative example 5, the silicon electrode materials obtained in the examples 1 to 3 have better specific capacity data, and the specific capacity of the silicon electrode materials prepared after 500 cycles of cycling still maintains better data; this fully demonstrates the improvement in electrochemical performance and cycling stability of the silicon electrode materials made in this application;
compared with the silicon electrode material obtained in the example 1, the silicon electrode materials obtained in the comparative examples 1 to 5 have the advantages that the preparation process of the silicon dioxide aerogel and the used components thereof are adjusted, and the specific capacity data after circulation show that the preparation process of the silicon dioxide aerogel and the used components thereof can improve the electrochemical performance and the circulation stability of the silicon electrode material.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Furthermore, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process method article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process method article or apparatus.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A preparation method of a silicon electrode material with good cycle stability is characterized by comprising the following steps: the method comprises the following processes:
(1) preparation of silica aerogel:
reacting gamma-glycidoxypropyltrimethoxysilane with phytic acid; introducing and reacting with aminoquinoline, and complexing with copper ions to obtain a complex;
mixing ethyl orthosilicate, water and ethanol, adding magnesium powder and a complex, and gelling to prepare silicon dioxide aerogel;
(2) preparation of silicon electrode material:
mixing silicon dioxide aerogel and magnesium powder, and carrying out heat treatment in an argon atmosphere; and after cooling, soaking in hydrochloric acid, and drying to obtain the silicon electrode material.
2. The method of claim 1, wherein the silicon electrode material has good cycling stability, and the method comprises the steps of: the (1) comprises the following processes:
stirring gamma-glycidyl ether oxypropyltrimethoxysilane at the rotating speed of 300-500 rpm, heating to 50-75 ℃, adding catalysts N, N-dimethylformamide and phytic acid, and reacting at constant temperature for 3-5 hours to obtain a compound I;
adding an alcohol aqueous solution and N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane into a compound I, mixing, stirring at the rotating speed of 500-800 rpm, adding hydrochloric acid to adjust the pH value of a system to 3.4-4.8, standing and hydrolyzing for 1-3 hours to obtain a compound II;
under the protection of argon, mixing 1, 2-dichloroethane and absolute ethyl alcohol, adding 2-aldehyde-8- (N-acetyl) aminoquinoline and a compound II, stirring at room temperature for 60-90 min, adding sodium triacetoxyborohydride, and reacting for 12-15 h to obtain a compound III;
mixing absolute ethyl alcohol, deionized water and diethyl ether, adding the compound III, stirring, adding hydrochloric acid, and continuing stirring for 30-60 min; carrying out reduced pressure distillation, filtering, washing and drying the precipitate to obtain the aminoquinoline derivative;
mixing an aminoquinoline derivative and copper sulfate, adding a Tris & HCl/NaCl buffer solution (pH is 7.4), and stirring at the rotating speed of 300-500 rpm for 60-90 min to obtain a complex;
taking ethyl orthosilicate, water and ethanol, and stirring and mixing at the temperature of 20-27 ℃; adding oxalic acid to adjust the pH of the system to 3.4-4.8, standing and hydrolyzing for 6-24 h; adding ammonia water, a complex and kh550 coupling modified magnesium powder, and adjusting the pH value of the system to 7.5-9.0; standing at room temperature to generate gel, and aging at room temperature for 7 d; and (3) soaking in normal hexane, filtering and drying to obtain the silicon dioxide aerogel.
3. A method of making a silicon electrode material with good cycling stability according to claim 2, characterized in that: the mass ratio of the gamma-glycidyl ether oxypropyl trimethoxy silane to the phytic acid to the N, N-dimethylformamide is (2.2-4.0) to 1 (0.09-0.15).
4. A method of making a silicon electrode material with good cycling stability according to claim 2, characterized in that: the molar ratio of the compound I to the N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane is (0.8-1.2): 1.
5. A method of making a silicon electrode material with good cycling stability according to claim 2, characterized in that: the molar ratio of the compound II, 2-aldehyde-8- (N-acetyl) aminoquinoline and sodium triacetoxyborohydride is (3.8-4.2) to 1 (3.8-4.2).
6. A method of making a silicon electrode material with good cycling stability according to claim 2, characterized in that: the molar ratio of the aminoquinoline derivative to the copper sulfate is 1 (6-10).
7. A method of making a silicon electrode material with good cycling stability according to claim 2, characterized in that: the mass ratio of the ethyl orthosilicate, the complex and the kh550 coupling modified magnesium powder is (10-20) to (7-12) 100.
8. The method of claim 1, wherein the silicon electrode material has good cycling stability, and the method comprises the steps of: the (2) comprises the following processes:
grinding silicon dioxide aerogel, dispersing in deionized water, adding sodium chloride, and drying; adding magnesium powder, uniformly mixing, heating to 680-750 ℃ at a heating rate of 5 ℃/min in an argon atmosphere, and preserving heat for 5-6 hours; cooling to room temperature; and soaking in hydrochloric acid for 6-8 hours, removing magnesium oxide and magnesium silicide in the hydrochloric acid, and drying in vacuum to obtain the silicon electrode material.
9. The method of claim 8, wherein the silicon electrode material has good cycling stability, and the method comprises the steps of: the mass ratio of the magnesium powder to the silicon dioxide aerogel is (0.8-1.1): 1.
10. A silicon electrode material having good cycle stability produced by the production method according to any one of claims 1 to 9.
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| CN115521645B (en) * | 2022-11-10 | 2023-09-12 | 贵州云天科贸有限公司 | Single-component inorganic zinc-rich antirust anti-slip coating |
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