A metal-atom complexed rechargeable and dischargeable fluorinated carbon material and its applications

Abstract

This invention relates to a method for preparing a high-capacity, charge-discharge-cycle-compatible fluorinated carbon material with metal atom complexes. The method utilizes solution chemistry to obtain an M-C structure through the complexation between metal atoms and carbon atoms, and then employs controlled fluorination to obtain a C-F bond structure, thereby preparing a metal atom complexed fluorinated carbon material. Due to the catalytic effect of the metal atoms, the prepared fluorinated carbon material serves as the positive electrode, and sodium or potassium metal is used as the negative electrode, enabling the preparation of charge-discharge-cycle-compatible (CF2) fluorinated carbon materials. X -M y ) n / Na or (CF) X -M y ) n / K batteries have broadened the application fields of fluorinated carbon materials and developed a new electrochemical reaction battery system with high specific energy.

Description

Technical Field

[0001] This invention belongs to the field of novel fluorinated carbon material preparation and its battery application, specifically relating to a metal atom complexed fluorinated carbon material and its preparation method, which has reversible sodium / potassium storage performance. Background Technology

[0002] Traditional fluorinated carbon is a covalent interlayer compound composed of carbon and fluorine, with the chemical formula (CFx)n. Its traditional preparation method involves a fluorination reaction between graphite and fluorine gas or fluorine-containing substances to produce fluorinated graphite. Fluorinated carbon materials can be used as positive electrode materials in lithium-ion primary batteries, combined with a lithium metal anode to form lithium-fluorinated carbon batteries. Lithium-fluorinated carbon batteries have a theoretical specific energy of approximately 2180 Wh / kg. However, the discharge products of the lithium synthesis process in fluorinated carbon materials are C and LiF. Due to the strong bond energy of the Li-F bond (1023 kJ / mol), the Li-F bond is difficult to dissociate, making the Li / CFx battery system difficult to cycle and limiting the technological application of high-energy-density fluorinated carbon materials in the field of secondary batteries.

[0003] The structure and properties of fluorinated carbon materials significantly influence the electrochemical performance of lithium-ion fluorinated carbon batteries. Structural design of the fluorinated precursor can effectively control the structure of the prepared fluorinated carbon materials, thereby regulating their electrochemical performance. Utilizing catalytic active centers to catalyze the dissociation of the CF bond can improve the discharge reaction kinetics of fluorinated carbon materials. Furthermore, novel metal / fluorinated carbon battery systems prepared by using sodium or potassium metal to form redox couples with fluorinated carbon exhibit significantly lower metal-F bond energies (NaF and KF) compared to the Li / CFx system (519 kJ / mol and 498 kJ / mol, respectively), far lower than the Li-F bond energy of 1023 kJ / mol. Therefore, Na / CFx and K / CFx systems are easier to charge and discharge than Li / CFx systems, enabling the application of fluorinated carbon in the field of rechargeable batteries.

[0004] However, existing commercially available fluorinated carbon materials, prepared through a gas-solid phase reaction of fluorine gas and graphite, have relatively large particle sizes, resulting in slow electrochemical reaction kinetics. Secondly, metal fluorides require catalytic components to break the metal-fluorine bonds. Furthermore, the C-F ion combination in the discharge products also requires a catalyst to achieve bonding under electrochemical reaction conditions. Therefore, utilizing active centers with electrochemical catalytic activity to catalyze the electrochemical reaction of fluorinated carbon is an effective way to obtain rechargeable and dischargeable fluorinated carbon. Summary of the Invention

[0005] The purpose of this invention is to provide a rechargeable and dischargeable fluorinated carbon material with metal atom complexation and its preparation method.

[0006] The rechargeable and dischargeable fluorinated carbon material with metal atom complexation described in this invention has the following composition: (CF X -M y ) n The M-representing metal atom is complexed with the C atom through CM, and the material has reversible sodium and potassium storage properties.

[0007] To achieve the above objectives, the present invention adopts the following technical solution, and the preparation method steps are as follows: phenolic compounds and organic aldehyde compounds are polycondensed under a catalyst, and metal salts are added to the reaction system. After low-temperature aging and high-temperature pyrolysis, a carbon material with metal atoms complexed is obtained; after further controllable fluorination treatment, a fluorinated carbon material with metal atoms complexed is obtained.

[0008] In the preparation method, the phenolic compound is resorcinol, phloroglucinol, or a phenolic compound containing a substituent (R-ArOH), wherein the substituent R is one or two of -COOH, -SO3H, -NH2, and -CN;

[0009] In the preparation method, the organic aldehyde compound is one or a mixture of two of formaldehyde, terephthalaldehyde, benzaldehyde, and phenylacetaldehyde;

[0010] In the preparation method, the catalyst is one or a mixture of two of sodium carbonate, sodium bicarbonate, ammonia, and ethylenediamine;

[0011] In the preparation method, the metal salt is one or a mixture of two of ferric chloride, ferric nitrate, cobalt chloride, cobalt nitrate, nickel chloride, nickel nitrate, and molybdenum nitrate.

[0012] The molar ratio of the phenolic compound to the organic aldehyde compound is 1:0.2 to 5; the molar ratio of the phenolic compound to the catalyst is 1:0.01 to 0.1; and the molar ratio of the phenolic compound to the metal salt is 1:0.05 to 0.2.

[0013] The reaction was carried out in a mixed solution of water and ethanol, with a volume ratio of water to ethanol of 0.2 to 2:1; the mass percentage of phenolic compounds in the solution was 0.05 to 0.5 g / ml.

[0014] The low-temperature aging temperature is 90℃~120℃, and the aging time is 2h~8h; the high-temperature pyrolysis temperature is 600℃~1000℃, and the pyrolysis time is 2h~4h; the fluorination treatment temperature is 200℃~500℃, and the fluorination time is 2h~4h; the fluorine-nitrogen mixture used for fluorination has a fluorine content of 5%~20% by mass.

[0015] (CF x -M y ) n The specific surface area is 10m² 2 / g~150m 2 / g, the pore volume of the material's mesopores (pores with a diameter of 2-50nm) is 0.05cm³. 3 / g~0.10cm 3 / g, total pore volume is 0.15cm³ 3 / g~0.30cm 3 / g.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. The prepared fluorinated carbon material exhibits high electrochemical activity due to the presence of metal catalytic active centers, and its battery system with alkali metals demonstrates rapid electrochemical reaction kinetics. 2. The prepared fluorinated carbon material, when combined with sodium and potassium metals, forms a battery with charge-discharge cycle performance, thus broadening the application of fluorinated carbon materials in secondary battery systems.

[0018] Due to the catalytic effect of metal atoms, the prepared fluorinated carbon material serves as the positive electrode, while sodium or potassium metal is used as the negative electrode, enabling the preparation of charge-discharge cycle-capable (CF3) materials. X -M y ) n / Na or (CF) X -M y ) n / K batteries have broadened the application fields of fluorinated carbon materials and developed a new electrochemical reaction battery system with high specific energy. Attached Figure Description

[0019] Figure 1 Electron micrograph of carbon materials with iron atom complexes

[0020] Figure 2 Iron-atom-complexed fluorinated carbon materials (CF) 0.9 Fe 0.09 Electron micrograph Detailed Implementation

[0021] The following embodiments are intended to enable those skilled in the art to more fully understand the present invention, but are not intended to limit the invention in any way.

[0022] Example 1:

[0023] Take 1g of phloroglucinol, add 2ml of a 1:1 mixture of water and ethanol, stir to dissolve the phloroglucinol, add 0.05g of ferric nitrate, then add 0.5g of terephthalaldehyde and 0.1g of sodium carbonate, and stir. Then, age the above solution system at 90℃ in a sealed container for 4 hours, remove it, and dry it. Finally, pyrolyze it at 900℃ for 2 hours under a nitrogen atmosphere to obtain metal-atom complexed carbon nanomaterials. Figure 12g of metal-atom-complexed carbon material was fluorinated at 400℃ for 2h using a fluorine / nitrogen mixture with a fluorine mass content of 5% to obtain iron-atom-complexed fluorinated carbon material (CF). 0.9 Fe 0.09 )n( Figure 2 Its morphology is a cross-linked particle with a size of about 100 nm and a specific surface area of ​​15.3 m². 2 / g, mesopore volume is 0.065cm³ 3 / g, total pore volume is 0.18cm³ 3 / g.

[0024] Fluorocarbon materials (CF) 0.9 Fe 0.09 A slurry was prepared by mixing positive electrode active material, conductive carbon black, and PVDF in a ratio of 8:1:1. This slurry was then coated onto carbon-coated aluminum foil to form the positive electrode sheet. Potassium metal was used as the negative electrode to construct the battery. At a 0.1C rate, the charge / discharge voltage range was 1.0-3.7V, the initial discharge specific capacity reached 670mAh / g, and the reversible discharge specific capacity was 450mAh / g.

[0025] Example 2

[0026] Take 1.5g of resorcinol, add 4ml of a 1:1 mixture of water and ethanol, stir to dissolve the resorcinol, add 0.05g of cobalt nitrate, then add 1.5g of p-benzaldehyde and 0.1g of ethylenediamine, and stir. Then, age the above solution system at 90℃ in a sealed environment for 4 hours, remove it, and dry it. Then, pyrolyze it at 800℃ for 2 hours under a nitrogen atmosphere to obtain metal atom-complexed nano-carbon materials. Take 2g of the metal atom-complexed carbon material, and fluorinate it at 300℃ for 2 hours using a fluorine / nitrogen mixture with a fluorine content of 5% by mass to obtain cobalt atom-complexed fluorinated carbon material (CF). 0.9 Co 0.08 The morphology consists of cross-linked particles of approximately 100 nm in size, and the material has a specific surface area of ​​14.8 m². 2 / g, mesopore volume is 0.07cm³ 3 / g, total pore volume is 0.12cm³ 3 / g.

[0027] With (CF) 0.9 Co 0.08 A slurry was prepared by mixing positive electrode active material, conductive carbon black, and PVDF in a ratio of 8:1:1. This slurry was then coated onto carbon-coated aluminum foil to form the positive electrode sheet. Sodium metal was used as the negative electrode to assemble the battery. At a 0.1C rate, the charge / discharge voltage range was 1.5-4.7V, the initial discharge specific capacity reached 650mAh / g, and the reversible discharge specific capacity was 420mAh / g.

[0028] Example 3

[0029] Take 1.5g of p-aminobenzenesulfonic acid, add 4ml of a 1:1 mixture of water and ethanol, stir to dissolve the p-aminobenzenesulfonic acid, add 0.05g of nickel nitrate, then add 1.5g of terephthalaldehyde and 0.5g of formaldehyde, and add 0.15g of ammonia water and stir. Then, age the above solution system at 120℃ in a sealed environment for 4 hours, remove it, and dry it. Then, pyrolyze it at 800℃ for 2 hours under a nitrogen atmosphere to obtain metal atom-complexed nano-carbon materials. Take 2g of the metal atom-complexed carbon material, and fluorinate it at 250℃ for 2 hours using a fluorine / nitrogen mixture with a fluorine mass content of 10% to obtain nickel atom-complexed fluorinated carbon material (CF). 0.8 Ni 0.07 The material is composed of cross-linked nanoparticles with a size of approximately 150 nm, and has a specific surface area of ​​20.2 m². 2 / g, mesopore volume is 0.05cm³ 3 / g, total pore volume is 0.13cm 3 / g.

[0030] With (CF) 0.8 Ni 0.07 The positive electrode is prepared by coating a slurry (n: positive active material: conductive carbon black: PVDF = 8:1:1) onto carbon-coated aluminum foil to form a positive electrode sheet, with metallic sodium as the negative electrode. At a 0.1C rate, the charge / discharge voltage range is 1.5-4.7V, the initial discharge specific capacity reaches 550mAh / g, and the reversible discharge specific capacity is 390mAh / g.

[0031] Example 4

[0032] Take 1.5g of 4-cyanobenzodiol, add 5ml of a 1:1 mixture of water and ethanol, stir to dissolve the 4-cyanobenzodiol, add 0.07g of ferric nitrate, then add 1.5g of terephthalaldehyde and 0.5g of formaldehyde, and finally add 0.15g of ammonia water and stir. Then, age the above solution system at 90℃ in a sealed environment for 4 hours, remove it, and dry it. Then, pyrolyze it at 800℃ for 2 hours under a nitrogen atmosphere to obtain metal atom-complexed nano-carbon materials. Take 2g of the metal atom-complexed carbon material, and fluorinate it at 250℃ for 2 hours using a fluorine / nitrogen mixture with a fluorine content of 10% by mass to obtain iron atom-complexed fluorinated carbon material (CF). 0.75 Fe 0.07 The material is composed of cross-linked nanoparticles with a size of approximately 130 nm, and has a specific surface area of ​​21.2 m². 2 / g, mesopore volume is 0.049cm³ 3 / g, total pore volume is 0.12cm³ 3 / g.

[0033] With (CF) 0.75 Fe 0.07The positive electrode is prepared by coating a slurry (n: positive active material: conductive carbon black: PVDF = 8:1:1) onto carbon-coated aluminum foil to form a positive electrode sheet, with potassium metal as the negative electrode. At a 0.1C rate, the charge / discharge voltage range is 1.0-3.7V, the initial discharge specific capacity reaches 620mAh / g, and the reversible discharge specific capacity is 470mAh / g.

[0034] Example 5

[0035] Take 1.5g of 4-cyanobenzodiol, add 2ml of a 1:1 mixture of water and ethanol, stir to dissolve the 4-cyanobenzodiol, add 0.06g of nickel nitrate, then add 1.5g of p-phenylacetaldehyde and 0.15g of ammonia water, and stir. Then, age the above solution system at 90℃ in a sealed environment for 4 hours, remove it, and dry it. Then, pyrolyze it at 900℃ for 2 hours under a nitrogen atmosphere to obtain metal atom-complexed nano-carbon materials. Take 2g of the metal atom-complexed carbon material, and fluorinate it at 250℃ for 2 hours using a fluorine / nitrogen mixture with a fluorine content of 10% by mass to obtain nickel atom-complexed fluorinated carbon material (CF). 0.85 Ni 0.06 The material is an amorphous powder composed of cross-linked particles with a size of approximately 140 nm, and has a specific surface area of ​​17.5 cm². 2 / g, mesopore volume is 0.05cm³ 3 / g, total pore volume is 0.13cm 3 / g.

[0036] With (CF) 0.85 Ni 0.06 A slurry was prepared by mixing positive electrode active material (n), conductive carbon black, and PVDF in a ratio of 8:1:1. This slurry was then coated onto carbon-coated aluminum foil to form the positive electrode sheet, with metallic sodium as the negative electrode to form the battery. At a 0.1C rate, the charge / discharge voltage range was 1.5-4.7V, the initial discharge specific capacity reached 550mAh / g, and the reversible discharge specific capacity was 350mAh / g.

[0037] Comparative Example

[0038] Take 1.5g of resorcinol and 4ml of a 1:1 mixture of water and ethanol. Stir to dissolve the resorcinol, then add 1.5g of p-benzaldehyde and 0.1g of ethylenediamine and stir. Then, age the solution at 90℃ for 4 hours, remove it, and dry it. Next, pyrolyze it at 800℃ for 2 hours under a nitrogen atmosphere to obtain nano-carbon materials. Take 2g of the prepared nano-carbon materials and fluorinate them at 300℃ for 2 hours using a fluorine / nitrogen mixture with a fluorine content of 5% (by mass) to obtain fluorinated carbon materials (CF). 0.9 The morphology consists of cross-linked particles of approximately 100 nm in size, and the material has a specific surface area of ​​19.8 m². 2 / g, mesopore volume is 0.08cm³ 3 / g, total pore volume is 0.13cm 3 / g.

[0039] With (CF) 0.9 A slurry was prepared by mixing positive electrode active material, conductive carbon black, and PVDF in a ratio of 8:1:1. This slurry was then coated onto carbon-coated aluminum foil to form the positive electrode sheet. A battery was assembled using metallic sodium as the negative electrode. At a 0.1C rate, the charge / discharge voltage range was 1.5-4.7V, and the initial discharge specific capacity reached 640mAh / g. However, the material cannot undergo reversible charging, and its reversible specific capacity is only 20mAh / g.

Claims

1. A rechargeable and dischargeable fluorinated carbon material with metal atom complexation, characterized in that: The rechargeable and dischargeable fluorinated carbon material with metal atom complexes is abbreviated as (CF). x -M y ) n , (CF x -M y ) n The metal atom M in the formula is one, two, or more of Fe, Co, Ni, and Mo; x is the molar ratio of F to C, with a value of 0.5 to 1.2; y is the molar ratio of M to C, with a value of 0.05 to 0.1; (CF x -M y ) n The specific surface area is 10 m² 2 / g ~ 150 m 2 / g, the mesopore volume of the material is 0.05 cm³. 3 / g ~ 0.10 cm 3 / g, total pore volume is 0.15 cm³ 3 / g ~ 0.30 cm 3 / g.

2. The fluorinated carbon material according to claim 1, characterized in that: In the rechargeable fluorinated carbon material with metal atom complexes, x is the molar ratio of F to C, with a value of 0.9 to 1.1, and y is the molar ratio of M to C, with a value of 0.06 to 0.

09.

3. A method for preparing the fluorinated carbon material according to claim 1 or 2, characterized in that: Phenolic compounds and organic aldehydes are polycondensed under a catalyst, and metal salts are added to the reaction system. After low-temperature aging and high-temperature pyrolysis, carbon materials with metal atoms are obtained. After further controlled fluorination treatment, fluorinated carbon materials with metal atoms are obtained. The phenolic compounds are resorcinol, phloroglucinol, and phenolic compounds containing substituents (R-ArOH), wherein the substituent R is one or more of -COOH, -SO3H, -NH2, and -CN; The organic aldehyde compound is one or a mixture of two of formaldehyde, terephthalaldehyde, benzaldehyde, and phenylacetaldehyde; The catalyst is one or a mixture of two of sodium carbonate, sodium bicarbonate, ammonia, and ethylenediamine; The metal salt is one or a mixture of two of the following: ferric chloride, ferric nitrate, cobalt chloride, cobalt nitrate, nickel chloride, nickel nitrate, and molybdenum nitrate.

4. The preparation method according to claim 3, characterized in that: The molar ratio of the phenolic compound to the organic aldehyde compound is 1:0.2~5; the molar ratio of the phenolic compound to the catalyst is 1:0.01~0.1; and the molar ratio of the phenolic compound to the metal salt is 1:0.05~0.

2.

5. The preparation method according to claim 4, characterized in that: The molar ratio of the phenolic compound to the organic aldehyde compound is 1:1 to 3; the molar ratio of the phenolic compound to the catalyst is 1:0.05 to 0.1; and the molar ratio of the phenolic compound to the metal salt is 1:0.05 to 0.

15.

6. The preparation method according to claim 3, characterized in that: The reaction was carried out in a mixed solution of water and ethanol, with a volume ratio of water to ethanol of 0.2 to 2:1; the mass percentage of phenolic compounds in the solution was 0.05 to 0.5 g / ml.

7. The preparation method according to claim 3, characterized in that: The low-temperature aging temperature is 90℃~120℃, and the aging time is 2h~8h; the high-temperature pyrolysis temperature is 600℃~1300℃, and the pyrolysis time is 2h~4h. The fluorination treatment temperature is 200℃~500℃, and the fluorination time is 2h~4h; the fluorine-nitrogen mixture used for fluorination has a fluorine content of 5%~20% by mass.

8. A fluorinated carbon material as described in claim 1 or 2 as a positive electrode active material in (CF) x -M y ) n / Na or (CF) x -M y ) n Applications in / K batteries.

9. The application according to claim 8, characterized in that: Due to the catalytic effect of metal atoms complexed with carbon atoms, it can be used to prepare charge-discharge cycleable (CF) batteries. x -M y ) n / Na or (CF) x -M y ) n / K battery; Metal atoms (M) and C atoms are complexed through CM. During the electrochemical reaction, the metal atoms have a catalytic effect, which gives the material reversible sodium and potassium storage properties.

10. The application according to claim 8 or 9, characterized in that: Using sodium or potassium metal as the negative electrode, (CF x -M y ) n The initial discharge specific capacity is 500 mAh / g ~ 910 mAh / g, the reversible cycle specific capacity is 400 mAh / g ~ 500 mAh / g, and the median discharge voltage is 2.1 ~ 3.0 V.

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