CN112980436A - Carbon quantum dot derived carbon nanosheet composite silicon dioxide cathode material and preparation method thereof - Google Patents
Carbon quantum dot derived carbon nanosheet composite silicon dioxide cathode material and preparation method thereof Download PDFInfo
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title claims abstract description 89
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 84
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 67
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 66
- 239000002135 nanosheet Substances 0.000 title claims abstract description 64
- 239000002131 composite material Substances 0.000 title claims abstract description 49
- 239000000377 silicon dioxide Substances 0.000 title claims abstract description 39
- 235000012239 silicon dioxide Nutrition 0.000 title claims abstract description 31
- 239000010406 cathode material Substances 0.000 title claims abstract description 22
- 238000002360 preparation method Methods 0.000 title claims abstract description 11
- 239000008367 deionised water Substances 0.000 claims abstract description 19
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 19
- 238000010438 heat treatment Methods 0.000 claims abstract description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 19
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 12
- 239000011593 sulfur Substances 0.000 claims abstract description 12
- 238000004108 freeze drying Methods 0.000 claims abstract description 8
- 238000002156 mixing Methods 0.000 claims abstract description 8
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 7
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 7
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims abstract description 7
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 7
- 239000002019 doping agent Substances 0.000 claims abstract description 7
- 239000005543 nano-size silicon particle Substances 0.000 claims abstract description 5
- 239000013078 crystal Substances 0.000 claims abstract description 3
- 239000002245 particle Substances 0.000 claims abstract description 3
- 239000007787 solid Substances 0.000 claims description 24
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 18
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 claims description 12
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 12
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 12
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 12
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 12
- 239000011248 coating agent Substances 0.000 claims description 12
- 238000000576 coating method Methods 0.000 claims description 12
- 238000001816 cooling Methods 0.000 claims description 12
- 239000011889 copper foil Substances 0.000 claims description 12
- 239000004570 mortar (masonry) Substances 0.000 claims description 12
- 238000004080 punching Methods 0.000 claims description 12
- 239000002002 slurry Substances 0.000 claims description 12
- 239000010405 anode material Substances 0.000 claims description 11
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 claims description 10
- 239000007773 negative electrode material Substances 0.000 claims description 10
- 238000011056 performance test Methods 0.000 claims description 10
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 7
- 229910052744 lithium Inorganic materials 0.000 claims description 7
- 229910013872 LiPF Inorganic materials 0.000 claims description 6
- 101150058243 Lipf gene Proteins 0.000 claims description 6
- 239000002033 PVDF binder Substances 0.000 claims description 6
- 239000004743 Polypropylene Substances 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 238000004140 cleaning Methods 0.000 claims description 6
- 239000003792 electrolyte Substances 0.000 claims description 6
- 238000000227 grinding Methods 0.000 claims description 6
- 239000003273 ketjen black Substances 0.000 claims description 6
- 238000003760 magnetic stirring Methods 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 6
- -1 polypropylene Polymers 0.000 claims description 6
- 229920001155 polypropylene Polymers 0.000 claims description 6
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 6
- 238000003756 stirring Methods 0.000 claims description 6
- 238000009210 therapy by ultrasound Methods 0.000 claims description 6
- 238000001291 vacuum drying Methods 0.000 claims description 6
- 238000005406 washing Methods 0.000 claims description 6
- 238000005303 weighing Methods 0.000 claims description 6
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 claims description 2
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 claims description 2
- 238000000967 suction filtration Methods 0.000 claims description 2
- 230000007935 neutral effect Effects 0.000 claims 1
- 238000005265 energy consumption Methods 0.000 abstract description 2
- 239000000463 material Substances 0.000 abstract description 2
- 238000003980 solgel method Methods 0.000 abstract description 2
- 238000001354 calcination Methods 0.000 abstract 1
- 230000001351 cycling effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 8
- 230000002441 reversible effect Effects 0.000 description 8
- 238000001914 filtration Methods 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000006138 lithiation reaction Methods 0.000 description 2
- 239000002064 nanoplatelet Substances 0.000 description 2
- FUJCRWPEOMXPAD-UHFFFAOYSA-N Li2O Inorganic materials [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 229910003481 amorphous carbon Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- XUCJHNOBJLKZNU-UHFFFAOYSA-M dilithium;hydroxide Chemical compound [Li+].[Li+].[OH-] XUCJHNOBJLKZNU-UHFFFAOYSA-M 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 239000002096 quantum dot Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/65—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing carbon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a carbon quantum dot derived carbon nanosheet composite silicon dioxide cathode material and a preparation method thereof. In the carbon quantum dot derived carbon nanosheet composite nano silicon dioxide cathode material, the thickness of the carbon quantum dot derived carbon nanosheet is less than or equal to 2nm, the carbon quantum dot derived carbon nanosheet contains 0.8-1.3% of sulfur by mass ratio, the silicon dioxide is spherical in shape, the crystal structure is an amorphous structure, and the average particle size is about 150 nm. Mixing carbon quantum dots and a sulfur dopant, calcining and heating to prepare a sulfur-doped carbon quantum dot derived carbon nanosheet, ultrasonically dispersing the carbon quantum dot derived carbon nanosheet in absolute ethyl alcohol, adding ammonia water, ethyl orthosilicate and deionized water, mixing, and preparing the sulfur-doped carbon quantum dot derived carbon nanosheet composite silicon dioxide cathode material by a sol-gel method and freeze drying. The preparation process is simple and has low energy consumption; the carbon quantum dot derived carbon nanosheet is used as a core supporting framework, the material is uniform in thickness, stable in structure and enhanced in conductivity, so that the cycling stability is enhanced.
Description
Technical Field
The invention belongs to the field of lithium ion battery electrode materials, and particularly relates to a carbon quantum dot derived carbon nanosheet composite silicon dioxide cathode material and a preparation method thereof.
Background
Lithium Ion Batteries (LIBs) are of great interest due to high energy density and long cycle life. Commercial graphite with a theoretical capacity of only 372mAh/g has failed to meet the ever-increasing power demand, and therefore, a silicon-based negative electrode material with a higher theoretical specific capacity (4200mAh/g) is considered as an optimal negative electrode material for the next generation of lithium ion batteries, however, the huge volume expansion (> 300%) during the lithiation process thereof causes defects of structural breakage and phase change during electrochemical reaction, which causes rapid capacity decay and significantly limits the commercial application thereof.
In recent years, amorphous silica with theoretical capacity up to 1965mAh/g has attracted attention, and its lithiation reaction produces Li2O may act as a buffer component for volume changes. However, the application is limited due to low initial coulombic efficiency and low conductivity. In order to solve the problems of pure silicon dioxide cathode materials, the invention creatively uses carbon quantum dot derived carbon nanosheet composite silicon dioxide to prepare the lithium battery cathode material, under the current density of 200mA/g, the first discharge specific capacity can reach 1124.8mAh/g, the first charge specific capacity can reach 725.7mAh/g, and the reversible specific capacity of 568.7mAh/g can be kept after 60 cycles; under the current density of 4A/g, the reversible specific capacity of 568.7mAh/g can be kept after 200 cycles.
Disclosure of Invention
The invention aims to provide a carbon quantum dot derived carbon nanosheet composite silicon dioxide cathode material and a preparation method thereof.
In the carbon quantum dot derived carbon nanosheet composite nano silicon dioxide cathode material, the thickness of the carbon quantum dot derived carbon nanosheet is less than or equal to 2nm, the sulfur is contained in the carbon quantum dot derived carbon nanosheet in a mass ratio of 0.8-1.3%, the shape of the silicon dioxide is spherical, the crystal structure is an amorphous structure, and the average particle size is about 150 nm.
The preparation method of the carbon quantum dot derived carbon nanosheet composite nano silicon dioxide cathode material comprises the following specific steps:
(1) putting 40mL of acetaldehyde solution with volume percentage concentration of 40% into a 100mL beaker, slowly adding 8g of NaOH solid under vigorous magnetic stirring, reacting for 1 hour, standing for 72 hours in a room temperature environment, taking out black oily solid obtained by the reaction, putting the black oily solid into the beaker, adding 50mL of hydrochloric acid solution with concentration of 1mol/L, stirring for 1 hour, repeatedly centrifuging and cleaning with deionized water to neutrality, putting solid powder into an oven, and preserving heat at 70 ℃ for 12 hours to obtain the carbon quantum dots.
(2) Weighing 1g of the carbon quantum dots obtained in the step (1) and 6g of the sulfur dopant, putting the carbon quantum dots and the sulfur dopant into a mortar, putting the mortar into a 5mL alumina crucible, putting the alumina crucible into a tube furnace, heating to 800 ℃ at a rate of 3 ℃/min under a nitrogen atmosphere, preserving heat for 1 hour, cooling to room temperature, washing with deionized water, performing suction filtration for 3-5 times, putting the tube furnace into an oven, heating to 70 ℃, and preserving heat for 12 hours to obtain the carbon quantum dot derived carbon nanosheet.
(3) Dispersing 50-200 mg of the carbon quantum dot derived carbon nanosheet obtained in the step (2) in 8mL of analytically pure absolute ethyl alcohol, performing ultrasonic treatment for 30 minutes, adding 28% ammonia water by mass percentage to enable the pH value of the system to be 8-10, adding 0.5mL of analytically pure ethyl silicate, standing for 12 hours, adding 1mL of deionized water to form gel, and putting the gel into a freeze dryer for freeze drying to obtain the carbon quantum dot derived carbon nanosheet composite silicon dioxide cathode material.
(4) Mixing 0.1g of the carbon quantum dot derived carbon nanosheet composite silicon dioxide negative electrode material obtained in the step (3), ketjen black and polyvinylidene fluoride according to the mass ratio of 5:3:2, adding 1-1.5 mL of analytically pure N-methyl-2-pyrrolidone solvent, grinding to prepare slurry, coating the slurry on a copper foil current collector with the coating thickness of 10 micrometers, placing the copper foil current collector into a vacuum drying oven, heating to 110 ℃, preserving heat for 10 hours, cooling to room temperature, and then punching into a circular pole piece with the diameter of 16mm by using a punching machine.
(5) The metal lithium sheet is used as a counter electrode, the diaphragm is made of polypropylene with a microporous structure, and the electrolyte is dissolved with LiPF with the concentration of 1mol/L6The volume ratio of EC, DMC and DEC is 1:1:1, and the solution is maintained in argonAnd assembling a CR2025 type battery in the protective glove box, sealing, standing for 12 hours, and carrying out electrochemical performance test at a test voltage of 3-0.01V and a current density of 200 mA/g-4A/g.
The sulfur dopant is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate and sulfur.
The invention has the following advantages:
(1) in the prepared carbon quantum dot derived carbon nanosheet composite silicon dioxide cathode material, the carbon quantum dot derived carbon nanosheet is used as a core supporting framework, so that the structure is stable, the conductivity is enhanced, and the cycle stability is enhanced.
(2) In the aspect of the cost advantage of preparation, the preparation of the quantum dot derived carbon nanosheet composite silicon dioxide cathode material is realized by a simple sol-gel method and freeze drying treatment, and the preparation method has the characteristics of less operation steps and low energy consumption and fully embodies the cost advantage.
Drawings
Fig. 1 is a Scanning Electron Microscope (SEM) image of carbon quantum dot derived carbon nanoplatelets prepared in example 1 of the present invention.
Fig. 2 is an X-ray diffraction (XRD) pattern of the carbon quantum dot-derived carbon nanosheet prepared in example 1 of the present invention.
Fig. 3 is a charge-discharge curve diagram of the first two times of the carbon quantum dot derived carbon nanosheet composite silica anode material prepared in example 1 of the present invention.
Fig. 4 is a cycle performance diagram of the carbon quantum dot derived carbon nanosheet composite silica anode material prepared in example 1 of the present invention.
Fig. 5 is a charge-discharge curve diagram of the carbon quantum dot derived carbon nanosheet composite silica negative electrode material prepared in embodiment 2 of the present invention.
Fig. 6 is a cycle performance diagram of the carbon quantum dot derived carbon nanosheet composite silica anode material prepared in embodiment 2 of the present invention.
FIG. 7 is a charge-discharge curve diagram of the carbon quantum dot derived carbon nanosheet composite silica anode material prepared in example 3 of the present invention,
Fig. 8 is a cycle performance diagram of the carbon quantum dot derived carbon nanosheet composite silica anode material prepared in example 3 of the present invention.
Fig. 9 is a Scanning Electron Microscope (SEM) image of the carbon quantum dot derived carbon nanosheet composite silica anode material prepared in example 4 of the present invention.
FIG. 10 is a charge-discharge curve diagram of the carbon quantum dot derived carbon nanosheet composite silica anode material prepared in example 4 of the present invention
Fig. 11 is a cycle performance diagram of the carbon quantum dot derived carbon nanosheet composite silica anode material prepared in example 4 of the present invention.
Fig. 12 shows that the carbon quantum dot derived carbon nanosheet composite silica anode material prepared in embodiment 4 of the present invention has a current density of 2A g-1Cycle performance graph below.
Fig. 13 shows that the carbon quantum dot derived carbon nanosheet composite silica anode material prepared in embodiment 4 of the present invention has a current density of 4A g-1Cycle performance graph below.
Detailed Description
Example 1:
(1) putting 40mL of acetaldehyde solution with volume percentage concentration of 40% into a 100mL beaker, slowly adding 8g of NaOH solid under vigorous magnetic stirring, reacting for 1 hour, standing for 72 hours in a room temperature environment, taking out black oily solid obtained by the reaction, putting the black oily solid into the beaker, adding 50mL of hydrochloric acid solution with concentration of 1mol/L, stirring for 1 hour, repeatedly centrifuging and cleaning with deionized water to neutrality, putting solid powder into an oven, and preserving heat at 70 ℃ for 12 hours to obtain the carbon quantum dots.
(2) Weighing 1g of the carbon quantum dots obtained in the step (1) and 6g of sodium dodecyl sulfate, putting the carbon quantum dots and the sodium dodecyl sulfate into a mortar, putting the mortar into a 5mL alumina crucible, putting the alumina crucible into a tube furnace, heating the tube furnace to 800 ℃ at a speed of 3 ℃/min under a nitrogen atmosphere, preserving heat for 1 hour, cooling the tube furnace to room temperature, washing and filtering the tube furnace for 3 times by using deionized water, putting the tube furnace into an oven, heating the tube furnace to 70 ℃, and preserving heat for 12 hours to obtain the carbon quantum dot derived carbon nanosheet. Scanning Electron Microscope (SEM) test analysis is carried out on the carbon quantum dot derived carbon nanosheet, and as shown in figure 1, the micro-morphology of the carbon quantum dot derived carbon nanosheet is a sheet-shaped structure with the thickness of less than or equal to 2 nm. X-ray diffraction (XRD) analysis of the carbon quantum dot-derived carbon nanoplatelets (fig. 2) indicated that the material was amorphous carbon.
(3) Dispersing 50mg of the carbon quantum dot derived carbon nanosheet obtained in the step (2) in 8mL of analytically pure absolute ethyl alcohol, performing ultrasonic treatment for 30 minutes, adding 28% ammonia water by mass percentage to enable the pH value of the system to be 8, adding 0.5mL of analytically pure ethyl silicate, standing for 12 hours, adding 1mL of deionized water to form gel, and putting the gel into a freeze dryer for freeze drying to obtain the carbon quantum dot derived carbon nanosheet composite silicon dioxide cathode material.
(4) Mixing 0.1g of the carbon quantum dot derived carbon nanosheet composite silicon dioxide negative electrode material obtained in the step (3), ketjen black and polyvinylidene fluoride according to the mass ratio of 5:3:2, adding 1mL of analytically pure N-methyl-2-pyrrolidone, grinding to prepare slurry, coating the slurry on a copper foil current collector with the coating thickness of 10 micrometers, placing the copper foil current collector into a vacuum drying oven, heating to 110 ℃, preserving heat for 10 hours, cooling to room temperature, and then punching into a circular pole piece with the diameter of 16mm by using a punching machine.
(5) The metal lithium sheet is used as a counter electrode, the diaphragm is made of polypropylene with a microporous structure, and the electrolyte is LiPF dissolved with the concentration of 1mol/L6The EC + DMC + DEC solution is assembled into a CR2025 type battery in an argon-protected glove box, the CR2025 type battery is sealed and then stands for 12 hours, and an electrochemical performance test is carried out, wherein the test voltage is 3-0.01V, and the current density is 200 mA/g. Electrochemical performance tests show that the first charge-discharge specific capacity of the composite material is 408.7 and 1467mAh/g respectively (figure 3), the reversible capacity still remained after 100 cycles is 379.8mAh/g, the coulombic efficiency is maintained to be more than 90% (figure 4), and the composite material shows better electrochemical performance.
Example 2:
(1) putting 40mL of acetaldehyde solution with volume percentage concentration of 40% into a 100mL beaker, slowly adding 8g of NaOH solid under vigorous magnetic stirring, reacting for 1 hour, standing for 72 hours in a room temperature environment, taking out black oily solid obtained by the reaction, putting the black oily solid into the beaker, adding 50mL of hydrochloric acid solution with concentration of 1mol/L, stirring for 1 hour, repeatedly centrifuging and cleaning with deionized water to neutrality, putting solid powder into an oven, and preserving heat at 70 ℃ for 12 hours to obtain the carbon quantum dots.
(2) Weighing 1g of the carbon quantum dots obtained in the step (1) and 6g of sodium dodecyl sulfate, putting the carbon quantum dots and the sodium dodecyl sulfate into a mortar, putting the mortar into a 5mL alumina crucible, putting the alumina crucible into a tube furnace, heating the tube furnace to 800 ℃ at a speed of 3 ℃/min under a nitrogen atmosphere, preserving heat for 1 hour, cooling the tube furnace to room temperature, washing and filtering the tube furnace with deionized water for 4 times, putting the tube furnace into an oven, heating the tube furnace to 70 ℃, and preserving heat for 12 hours to obtain the carbon quantum dot derived carbon nanosheet.
(3) Dispersing 100mg of the carbon quantum dot derived carbon nanosheet obtained in the step (2) in 8mL of analytically pure absolute ethyl alcohol, performing ultrasonic treatment for 30 minutes, adding 28% ammonia water by mass percentage to enable the pH value of the system to be 9, adding 0.5mL of analytically pure ethyl silicate, standing for 12 hours, adding 1mL of deionized water to form gel, and putting the gel into a freeze dryer for freeze drying to obtain the carbon quantum dot derived carbon nanosheet composite silicon dioxide cathode material.
(4) Mixing 0.1g of the carbon quantum dot derived carbon nanosheet composite silicon dioxide negative electrode material obtained in the step (3), ketjen black and polyvinylidene fluoride according to the mass ratio of 5:3:2, adding 1mL of analytically pure N-methyl-2-pyrrolidone, grinding to prepare slurry, coating the slurry on a copper foil current collector with the coating thickness of 10 micrometers, placing the copper foil current collector into a vacuum drying oven, heating to 110 ℃, preserving heat for 10 hours, cooling to room temperature, and then punching into a circular pole piece with the diameter of 16mm by using a punching machine.
(5) The metal lithium sheet is used as a counter electrode, the diaphragm is made of polypropylene with a microporous structure, and the electrolyte is LiPF dissolved with the concentration of 1mol/L6The EC + DMC + DEC solution is assembled into a CR2025 type battery in an argon-protected glove box, the CR2025 type battery is sealed and then stands for 12 hours, and an electrochemical performance test is carried out, wherein the test voltage is 3-0.01V, and the current density is 200 mA/g. Electrochemical performance tests show that the first charge-discharge specific capacity of the composite material is 673.4 and 1990.7mAh/g (figure 5), the reversible capacity still remained after 100 cycles is 510.2mAh/g, the coulombic efficiency is maintained to be more than 90% (figure 6), and the composite material shows better electrochemical performance.
Example 3:
(1) putting 40mL of acetaldehyde solution with volume percentage concentration of 40% into a 100mL beaker, slowly adding 8g of NaOH solid under vigorous magnetic stirring, reacting for 1 hour, standing for 72 hours in a room temperature environment, taking out black oily solid obtained by the reaction, putting the black oily solid into the beaker, adding 50mL of hydrochloric acid solution with concentration of 1mol/L, stirring for 1 hour, repeatedly centrifuging and cleaning with deionized water to neutrality, putting solid powder into an oven, and preserving heat at 70 ℃ for 12 hours to obtain the carbon quantum dots.
(2) Weighing 1g of the carbon quantum dots obtained in the step (1) and 6g of sodium dodecyl sulfate, putting the carbon quantum dots and the sodium dodecyl sulfate into a mortar, putting the mortar into a 5mL alumina crucible, putting the alumina crucible into a tube furnace, heating the tube furnace to 800 ℃ at a speed of 3 ℃/min under a nitrogen atmosphere, preserving heat for 1 hour, cooling the tube furnace to room temperature, washing and filtering the tube furnace for 5 times by using deionized water, putting the tube furnace into an oven, heating the tube furnace to 70 ℃, and preserving heat for 12 hours to obtain the carbon quantum dot derived carbon nanosheet.
(3) Dispersing 150mg of the carbon quantum dot derived carbon nanosheet obtained in the step (2) in 8mL of analytically pure absolute ethyl alcohol, performing ultrasonic treatment for 30 minutes, adding 28% ammonia water by mass percentage to enable the pH value of the system to be 10, adding 0.5mL of analytically pure ethyl silicate, standing for 12 hours, adding 1mL of deionized water to form gel, and putting the gel into a freeze dryer for freeze drying to obtain the carbon quantum dot derived carbon nanosheet composite silicon dioxide cathode material.
(4) Mixing 0.1g of the carbon quantum dot derived carbon nanosheet composite silicon dioxide negative electrode material obtained in the step (3), ketjen black and polyvinylidene fluoride according to the mass ratio of 5:3:2, adding 1.2mL of analytically pure N-methyl-2-pyrrolidone, grinding to prepare slurry, coating the slurry on a copper foil current collector with the coating thickness of 10 micrometers, placing the copper foil current collector into a vacuum drying oven, heating to 110 ℃, preserving heat for 10 hours, cooling to room temperature, and then punching into a circular pole piece with the diameter of 16mm by using a punching machine.
(5) The metal lithium sheet is used as a counter electrode, the diaphragm is made of polypropylene with a microporous structure, and the electrolyte is LiPF dissolved with the concentration of 1mol/L6The EC + DMC + DEC solution is assembled into a CR2025 type battery in an argon-protected glove box, the CR2025 type battery is sealed and then stands for 12 hours, and an electrochemical performance test is carried out, wherein the test voltage is 3-0.01V, and the current density is 200 mA/g. Electrochemical performance tests show that the first charge-discharge specific capacity of the composite material is 725.7 and 1914.8mAh/g (figure 7),the reversible capacity still remained after 80 cycles is 638.2mAh/g, the coulombic efficiency is maintained above 90% (figure 8), and the electrochemical performance is better.
Example 4:
(1) putting 40mL of acetaldehyde solution with volume percentage concentration of 40% into a 100mL beaker, slowly adding 8g of NaOH solid under vigorous magnetic stirring, reacting for 1 hour, standing for 72 hours in a room temperature environment, taking out black oily solid obtained by the reaction, putting the black oily solid into the beaker, adding 50mL of hydrochloric acid solution with concentration of 1mol/L, stirring for 1 hour, repeatedly centrifuging and cleaning with deionized water to neutrality, putting solid powder into an oven, and preserving heat at 70 ℃ for 12 hours to obtain the carbon quantum dots.
(2) Weighing 1g of the carbon quantum dots obtained in the step (1) and 6g of sodium dodecyl sulfate, putting the carbon quantum dots and the sodium dodecyl sulfate into a mortar, putting the mortar into a 5mL alumina crucible, putting the alumina crucible into a tube furnace, heating the tube furnace to 800 ℃ at a speed of 3 ℃/min under a nitrogen atmosphere, preserving heat for 1 hour, cooling the tube furnace to room temperature, washing and filtering the tube furnace for 5 times by using deionized water, putting the tube furnace into an oven, heating the tube furnace to 70 ℃, and preserving heat for 12 hours to obtain the carbon quantum dot derived carbon nanosheet.
(3) Dispersing 200mg of the carbon quantum dot derived carbon nanosheet obtained in the step (2) in 8mL of analytically pure absolute ethyl alcohol, performing ultrasonic treatment for 30 minutes, adding 28% ammonia water by mass percentage to enable the pH value of the system to be 10, adding 0.5mL of analytically pure ethyl silicate, standing for 12 hours, adding 1mL of deionized water to form gel, and putting the gel into a freeze dryer for freeze drying to obtain the carbon quantum dot derived carbon nanosheet composite silicon dioxide cathode material. Scanning Electron Microscope (SEM) test analysis was performed on the carbon quantum dot derived carbon nanosheet composite silica negative electrode material, and as shown in fig. 9, the micro-morphology of the composite material was a lamellar structure with uniform thickness.
(4) Mixing 0.1g of the carbon quantum dot derived carbon nanosheet composite silicon dioxide negative electrode material obtained in the step (3), ketjen black and polyvinylidene fluoride according to the mass ratio of 5:3:2, adding 1.5mL of analytically pure N-methyl-2-pyrrolidone, grinding to prepare slurry, coating the slurry on a copper foil current collector with the coating thickness of 10 micrometers, placing the copper foil current collector into a vacuum drying oven, heating to 110 ℃, preserving heat for 10 hours, cooling to room temperature, and then punching into a circular pole piece with the diameter of 16mm by using a punching machine.
(5) The metal lithium sheet is used as a counter electrode, the diaphragm is made of polypropylene with a microporous structure, and the electrolyte is LiPF dissolved with the concentration of 1mol/L6The EC + DMC + DEC solution is assembled into a CR2025 type battery in an argon-protected glove box, the CR2025 type battery is sealed and then stands for 12 hours, and an electrochemical performance test is carried out, wherein the test voltage is 3-0.01V, and the current density is 200 mA/g. Electrochemical performance tests show that the first charge-discharge specific capacity of the composite material is 1124.8 and 2812.9mAh/g (figure 10), the reversible capacity still remained after 80 cycles is 775.9mAh/g (figure 11), and the composite material shows good electrochemical performance. The cycle performance of the composite material under the conditions that the large current density is 2A/g and 4A/g is respectively shown in figures 12 and 13, the reversible specific capacity of 501.9mAh/g is still reserved after 120 cycles (figure 12), the reversible specific capacity of 426.4mAh/g is still reserved after 200 cycles (figure 13), and the coulombic efficiency is maintained to be more than 90%.
Claims (2)
1. The carbon quantum dot derived carbon nanosheet composite silicon dioxide cathode material is characterized in that in the carbon quantum dot derived carbon nanosheet composite nano silicon dioxide cathode material, the thickness of the carbon quantum dot derived carbon nanosheet is less than or equal to 2nm, the carbon quantum dot derived carbon nanosheet composite nano silicon dioxide cathode material contains 0.8-1.3% of sulfur by mass ratio, the shape of silicon dioxide is spherical, the crystal structure is an amorphous structure, and the average particle size is about 150 nm.
2. The preparation method of the carbon quantum dot derived carbon nanosheet composite silica anode material according to claim 1, characterized by comprising the following specific steps:
(1) putting 40mL of acetaldehyde solution with volume percentage concentration of 40% into a 100mL beaker, slowly adding 8g of NaOH solid under vigorous magnetic stirring, reacting for 1 hour, standing for 72 hours in a room temperature environment, taking out black oily solid obtained by the reaction, putting the black oily solid into the beaker, adding 50mL of hydrochloric acid solution with concentration of 1mol/L, stirring for 1 hour, repeatedly centrifuging and cleaning with deionized water until the solution is neutral, putting solid powder into an oven, and preserving heat for 12 hours at 70 ℃ to obtain the carbon quantum dots;
(2) weighing 1g of the carbon quantum dots obtained in the step (1) and 6g of the sulfur dopant, putting the carbon quantum dots and the sulfur dopant into a mortar, putting the mortar into a 5mL alumina crucible, putting the alumina crucible into a tube furnace, heating to 800 ℃ at a rate of 3 ℃/min under a nitrogen atmosphere, preserving heat for 1 hour, cooling to room temperature, washing with deionized water, performing suction filtration for 3-5 times, putting the tube furnace into an oven, heating to 70 ℃, and preserving heat for 12 hours to obtain carbon quantum dot derived carbon nanosheets;
(3) dispersing 50-200 mg of the carbon quantum dot derived carbon nanosheet obtained in the step (2) in 8mL of analytically pure absolute ethyl alcohol, performing ultrasonic treatment for 30 minutes, adding 28% ammonia water by mass percentage to adjust the pH value of the system to 8-10, adding 0.5mL of analytically pure ethyl silicate, standing for 12 hours, adding 1mL of deionized water to form gel, and putting the gel into a freeze dryer for freeze drying to obtain the carbon quantum dot derived carbon nanosheet composite silicon dioxide cathode material;
(4) mixing 0.1g of the carbon quantum dot derived carbon nanosheet composite silicon dioxide negative electrode material obtained in the step (3), ketjen black and polyvinylidene fluoride according to the mass ratio of 5:3:2, adding 1-1.5 mL of analytically pure N-methyl-2-pyrrolidone, grinding to prepare slurry, coating the slurry on a copper foil current collector, wherein the coating thickness is 10 mm, placing the copper foil current collector into a vacuum drying oven, heating to 110 ℃, preserving heat for 10 hours, cooling to room temperature, and then punching into a circular pole piece with the diameter of 16mm by using a punching machine;
(5) the metal lithium sheet is used as a counter electrode, the diaphragm is made of polypropylene with a microporous structure, and the electrolyte is dissolved with LiPF with the concentration of 1mol/L6The EC + DMC + DEC solution is assembled into a CR2025 type battery in an argon-protected glove box, the CR2025 type battery is sealed and then stands for 12 hours, and an electrochemical performance test is carried out, wherein the test voltage is 3-0.01V, and the current density is 200 mA/g-4A/g;
the sulfur dopant is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate and sulfur.
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| CN114430062A (en) * | 2022-01-24 | 2022-05-03 | 中南大学 | Composite electrolyte based on lithiation carbon point modification and preparation method and application thereof |
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| GUOQIANG ZOU ET AL.: "Controllable Interlayer Spacing of Sulfur-Doped Graphitic Carbon Nanosheets for Fast Sodium-Ion Batteries", 《SMALL》 * |
| JINXIANG MAO ET AL.: "Synthesis of uniform silica nanospheres wrapped in nitrogen-doped carbon nanosheets with stable lithium-ion storage properties", 《J MATER SCI.》 * |
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| CN114284553A (en) * | 2021-12-25 | 2022-04-05 | 西安交通大学 | Lithium metal battery without negative electrode and preparation method thereof |
| CN114430062A (en) * | 2022-01-24 | 2022-05-03 | 中南大学 | Composite electrolyte based on lithiation carbon point modification and preparation method and application thereof |
| CN114430062B (en) * | 2022-01-24 | 2023-10-10 | 中南大学 | Composite electrolyte based on lithiated carbon point modification and preparation method and application thereof |
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Application publication date: 20210618 Assignee: Nanning Jiepin Paper Products Processing Factory Assignor: GUILIN University OF TECHNOLOGY Contract record no.: X2023980044310 Denomination of invention: A carbon quantum dot derived carbon nanosheet composite silica negative electrode material and its preparation method Granted publication date: 20230530 License type: Common License Record date: 20231027 Application publication date: 20210618 Assignee: Sales and Operation Department of Qiyue Paper Products in Xixiangtang District, Nanning Assignor: GUILIN University OF TECHNOLOGY Contract record no.: X2023980044309 Denomination of invention: A carbon quantum dot derived carbon nanosheet composite silica negative electrode material and its preparation method Granted publication date: 20230530 License type: Common License Record date: 20231027 |