EP3721497A1 - Procédé de fabrication d'un composé à base d'oxyde de graphène pour électrode à air d'une batterie métal-air et composé associé - Google Patents
Procédé de fabrication d'un composé à base d'oxyde de graphène pour électrode à air d'une batterie métal-air et composé associéInfo
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- EP3721497A1 EP3721497A1 EP18826431.1A EP18826431A EP3721497A1 EP 3721497 A1 EP3721497 A1 EP 3721497A1 EP 18826431 A EP18826431 A EP 18826431A EP 3721497 A1 EP3721497 A1 EP 3721497A1
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- Prior art keywords
- graphene oxide
- sulfur
- nitrogen
- compound
- sheet
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M12/00—Hybrid cells; Manufacture thereof
- H01M12/04—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type
- H01M12/06—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type with one metallic and one gaseous electrode
- H01M12/065—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type with one metallic and one gaseous electrode with plate-like electrodes or stacks of plate-like electrodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M12/00—Hybrid cells; Manufacture thereof
- H01M12/08—Hybrid cells; Manufacture thereof composed of a half-cell of a fuel-cell type and a half-cell of the secondary-cell type
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/04—Processes of manufacture in general
- H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/364—Composites as mixtures
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/581—Chalcogenides or intercalation compounds thereof
- H01M4/5815—Sulfides
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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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
Definitions
- the invention relates to the field of metal-air batteries, and more particularly to the processes for manufacturing graphene-based compounds for reversible air electrodes of metal-air batteries.
- Lithium-ion batteries widely used in portable electrical appliances, offer a high energy capacity and have a long life, of the order of 5000 cycles of charge / discharge. However, these batteries have reached a maturation threshold that limits their use in more demanding applications in electricity such as residential electricity storage, network storage or electric vehicles.
- Metal-air battery cells typically consist of a metal-based negative electrode such as zinc, iron, or lithium, coupled to an air electrode. These two electrodes are generally in contact with an aqueous alkaline electrolyte.
- the advantage of the metal-air systems lies in the use of a positive electrode of infinite capacity, the oxygen consumed at the positive electrode does not need to be stored in the electrode but can be taken from the electrode. 'ambiant air.
- Electrochemical generators metal-air type are known for their high mass energies, which can reach several hundred Wh / kg.
- Air electrodes are for example used in alkaline fuel cells which are particularly advantageous compared to other systems because of the kinetics reaction at the electrodes and because of the absence of noble metals such as platinum.
- An air electrode is a porous solid structure, usually in carbon powder, in contact with the liquid electrolyte.
- the interface between the air electrode and the liquid electrolyte is a so-called "triple contact" interface where the active solid material of the electrode (this electrode generally also comprising a catalyst), the gaseous oxidant, is simultaneously present. , that is, air, and the liquid electrolyte.
- the air electrode is usually composed of high surface area carbon powder, making it possible to offer a high reaction surface and therefore a high current density relative to the geometrical surface of the electrode.
- a large reaction surface is advantageous for compensating for the difference between the density of gaseous oxygen and that of a liquid.
- the molar density of oxygen in air is about 0.03 mol / L compared to water that has a density of 55 mol / L.
- the large carbon surface makes it possible to multiply the reaction sites in the air electrode.
- the catalyst commonly used in air electrodes disintegrates in contact with the alkaline electrolyte of the metal-air batteries and is found in the electrolyte. This effect is particularly accentuated when the electrical potential applied to the electrode increases (especially in the recharge phase).
- the manganese oxide MnO 2 is transformed into MnO 4 then MnO 4 .
- the carbon grains of the structure of the air electrodes corrode by oxidation during operation of the battery. This effect is all the more important as the potential applied to the electrode is high. Unfortunately, the conditions of this corrosion are always encountered during the recharging of the battery, since this recharge generally imposes a potential greater than 0.6 V at the discharge potential of the air electrode.
- the present invention proposes a method of manufacturing a graphene oxide compound for an air electrode of a metal-air battery, the process comprising:
- This process makes it possible to manufacture an original compound consisting of nitrogen and sulfur doped graphene oxide, further comprising nanoparticles of cobalt oxide.
- This compound has a strong stability in alkaline media of pH greater than 13, which makes it a compound of choice for application in the porous structure of a metal-air battery air electrode.
- the method allows better control of the incorporation of nitrogen and sulfur in graphene oxide, in particular by the step of heating the graphene oxide powder.
- the conditions of this heating make it possible in particular to substantially modify the proportion of graphitic sites occupied by the nitrogen atoms in graphene oxide.
- the method proposes in particular to synthesize the cobalt oxide nanoparticles directly in an aqueous solution containing the support consisting of graphene oxide doped with nitrogen and sulfur. This technique differs from the prior art which generally proposes to manufacture nanoparticles separately before reacting them with a support at a later stage.
- the powder may be heated under an inert atmosphere at a temperature between 700 ° C and 1100 ° C.
- the powder may be gradually heated by increasing the temperature under an inert atmosphere at a rate of between 1 ° C per minute and 20 ° C per minute.
- Such conditions for heating the graphene oxide powder in the presence of the sulfur-based organic compound and nitrogen make it possible to control the speciation of nitrogen and sulfur in the structure of graphene oxide.
- speciation refers to the different forms of possible linkages of a chemical element (in this case sulfur and nitrogen) in a given environment (in this case a graphene oxide sheet).
- the temperature and the rise in temperature favor a gradual sublimation of the organic compound based on nitrogen and sulfur, without destroying graphene oxide.
- Such temperature conditions also favor graphitic speciation of nitrogen.
- the organic compound based on nitrogen and sulfur may be thiourea.
- Thiourea has the advantage of being an organic compound that is easy to handle and to produce, and in which the stoichiometric proportions of nitrogen and sulfur are suitable for the manufacture of the compound of the invention.
- the second aqueous suspension can be heated to a temperature of between 80 ° C and 150 ° C.
- Such a temperature makes it possible to create favorable deposition conditions for a homogeneous distribution of nanoparticles directly on the graphene oxide doped with nitrogen and sulfur, avoiding local agglomeration of nanoparticles.
- the second aqueous suspension is heated in a microwave oven.
- Microwave heating seems to favor growth of cobalt oxide nanoparticles directly on nitrogen and sulfur doped graphene oxide with a rate of nearly 90%.
- a heating mode leads to the creation of nanoparticles having a substantially spherical shape and a size of between 2 nm and 5 nm.
- This method differs in particular from hydrothermal heating techniques commonly used to make cobalt oxide crystals, which then have larger sizes and do not bind with such a large proportion on the layers.
- a proportion of between 80% and 95% of the cobalt nitrate compound can be fixed in the form of nanoparticles of cobalt oxide on the surface of the at least one sheet of graphene oxide.
- the method may further comprise:
- the compound obtained by the method described above makes it possible to halve the weight of an air electrode relative to a conventional electrode using as catalyst manganese.
- the compound is stable in cycling and does not deteriorate in the presence of an alkaline electrolyte of strongly basic pH (greater than 13), commonly used in metal-air batteries.
- the invention also relates to the compound based on graphene oxide for an air electrode of a metal-air battery obtained by the method described above.
- Such a compound comprises at least one sheet of oxidized graphene oxide doped with nitrogen and sulfur heteroatoms and comprising on one surface of the at least one sheet of oxidized graphene oxide doped with nitrogen heteroatoms and of sulfur cobalt oxide nanoparticles.
- This compound has the advantage of being light and stable in an alkaline medium. In addition, it does not degrade during potential variations experienced by the electrodes of a battery, and in particular a reversible air electrode metal-air battery in which it can be used in place of dispersed manganese oxide on a carbon powder such as carbon black.
- the nitrogen heteroatoms present in the carbonaceous structure of graphene oxide make it possible to modify the charge density (by making it positive) on the adjacent carbon atoms, which then form sites facilitating both the adsorption of the species.
- oxygen such as the oxygen dioxygen used in metal-air batteries or hydroxyl ions), and their transformation into oxidation and reduction products.
- the nitrogen doping makes it possible to significantly increase the activity of graphene oxide during the dioxygen reduction reaction.
- Sulfur doping accentuates this effect, and also contributes to better stability in alkaline medium and cycling in a metal-air battery. This effect of improving the electrochemical stability in alkaline medium and in cycling is accentuated by the presence of nanoparticles of cobalt oxide.
- the cobalt oxide nanoparticles make it possible to improve the electrical performance of the compound during the oxidation reactions of the water, for example during the charging of a battery.
- the electrical conduction properties of the graphene oxide combined with the electrocatalytic properties of the cobalt oxide nanoparticles make it possible to facilitate the charge transfer at the interface between the oxygenated species and the structure of the compound. Used in an air electrode, this effectively channels the charges between the reaction sites on the air electrode and the battery.
- Such a compound, used in a metal-air battery air electrode makes it possible to reduce the weight of the air electrode by about 50% and to reduce the energy losses during cycling of a metal battery. about 30% air.
- the nitrogen may represent a proportion of between 3% and 5% atomic in the at least one sheet
- the sulfur may represent a proportion of between 0.4% and 0.8% atomic in the at least one a sheet
- the oxygen may represent a proportion of between 1.2% and 1.6% atomic in the at least one sheet
- the carbon may represent a proportion of between 97.4% and 98% atomic in the at least one sheet.
- Nitrogen heteroatoms provide graphene sheets with p- and n-type semiconductor properties favorable to oxygen reduction (ORR) and oxygen production (OER) reactions. evolution in N-doped graphene materials: Development of highly efficient metal-free bifunctional electrocatalyst, Hong Bin Yang et al., Sci., Adv., 2016, 2: el 501, 22).
- the p-type domains created by the N-pyridinic heteroatoms accept the electrons of the adjacent carbons thus facilitating the adsorption of the OH and OOH type intermediates of the oxidation reaction (OER) in an alkaline medium.
- the p-type domains of graphene accept the electrons of the OH species adsorbed on the surface thus accelerating the intermediate step OH ® OH adSOrbé ⁇
- a proportion of nitrogen of between 3% and 5% by weight in the at least one sheet of graphene oxide is favorable to oxygen reduction (ORR) and oxygen evolution (OER) reactions in an alkaline medium, thereby improving the catalytic activity of the graphene oxide compound.
- the nitrogen heteroatoms can occupy graphitic, pyrrolic and pyrinidic sites in the at least one sheet in the proportions following: between 15% and 50% of graphitic sites, between 25% and 25% of pyrrolic sites, between 30% and 40% of pyrinidic sites and between 10% and 20% of NO x type groups.
- Such speciation of nitrogen atoms in particular with the presence of graphitic nitrogen in proportions of up to more than 30%, contributes to creating the electronic conditions allowing the oxygen species to react on a major part of the surface of the oxide. graphene, not just on its edges.
- a proportion of between 70% and 80% of the sulfur heteroatoms can be distributed in the form of carbon-sulfur-carbon CSC or carbon-sulfur-hydrogen CSH groups, and a proportion of between 20% and 30%.
- sulfur heteroatoms may be distributed in the form of C-SO n groups .
- the presence of sulfur heteroatoms makes it possible to further increase the polarization of carbon.
- the presence of sulfur heteroatoms further enhances the catalytic activity of the graphene oxide compound for both the oxygen reduction reaction (ORR) and the oxygen production reaction (OER). ).
- the nanoparticles of cobalt oxide can be distributed substantially homogeneously on the at least one graphene oxide sheet, and the average distance between two nanoparticles of cobalt oxide on at least one a sheet of graphene oxide may be between 0.5 nm and 3 nm.
- This substantially homogeneous distribution of the cobalt oxide nanoparticles on the support formed by nitrogen and sulfur-doped graphene oxide also contributes to making this compound effective in an application as a catalyst of an air electrode for a metal-air battery.
- the nanoparticles are not agglomerated, but distributed over the entire surface of the graphene oxide, the compound offers a greater amount of reaction sites. This reduces the amount of compound used in an air electrode, further contributing to reducing its weight.
- the cobalt oxide nanoparticles have a substantially spherical shape and a size less than 10 nm, preferably between 2 nm and 5 nm on the at least one sheet, preferably 4 nm.
- the nanoparticles of cobalt oxide represent between 40% and 60% of the mass of the compound. Cobalt oxide promotes the oxygen production reaction (OER).
- nanoparticles of cobalt oxide having a size of less than 10 nm, preferably of between 2 nm and 5 nm on at least one sheet make it possible to obtain a stable compound and sufficiently cover the surface of graphene without cover it completely, thus avoiding blocking any oxygen reduction reaction (ORR).
- ORR oxygen reduction reaction
- the use of 4 nm cobalt oxide nanoparticles is particularly advantageous.
- the invention also provides an air electrode comprising a compound as described above.
- the invention also relates to a metal-air battery comprising at least one air electrode as described above.
- FIG. 1 is a flow chart showing steps of the process for manufacturing a graphene oxide compound for an air electrode of a metal-air battery
- FIG. 2 is a schematic representation of a graphene sheet doped with nitrogen, integrated in the sheet so as to occupy different sites within the sheet: graphitic, pyrrolic and pyrinidic sites;
- FIG. 3 is a schematic representation of a graphene oxide sheet identifying various possible configurations for binding oxygen to carbon in the sheet;
- FIG. 4 is a schematic representation of a metal-air battery comprising an air electrode manufactured from the compound,
- FIG. 5 is an X-ray diffractogram of nanoparticles of cobalt oxide on the surface of reduced graphene oxide films doped with nitrogen and sulfur;
- FIG. 6 represents a histogram of the distances separating two nanoparticles of cobalt oxide; nearest neighbors, showing a homogeneous distribution of cobalt oxide nanoparticles on the sheets of graphene oxide doped with nitrogen and sulfur,
- FIG. 7 is a graph showing the repeatability of the electrical behavior of an air electrode comprising the compound of the invention in cycling.
- the present invention provides an original manufacturing method of a compound usable to improve the service life, optimize the structure and reduce the weight of air electrode metal-air batteries.
- the compound resulting from the process is incorporated in a metal-air battery air electrode
- the air electrode displays equivalent electrical performances better than those of the electrodes using manganese oxide as a catalyst, but does not encounter the degradation problems observed in the prior art air electrodes in cycling.
- the term "cycling" refers to the periodic charges and discharges that occur during operation of the metal-air battery.
- the compound of the present invention into a metal-air battery air electrode, it becomes possible to use solid or gelled electrolytes in metal-air batteries, thus avoiding the maintenance constraints that arise during the use of liquid electrolytes.
- a solid or gelled electrolyte is particularly advantageous for application in portable systems.
- the compound presented below may also be used for other applications, especially those in which an electrochemical resistance to alkaline pHs typically greater than 13 is desired.
- Figure 1 schematically illustrates a few steps of a method of manufacturing a compound according to the invention.
- a first aqueous solution 1 of a graphene oxide 10 is obtained.
- This step can be carried out using a known technique for synthesizing graphene oxide, such as for example the so-called “Hummers” method, described in the document Hummers, William S .; Offeman, Richard E. (March 20, 1958). "Preparation ofGraphitic Oxide", Journal of the American Chemical Society. 80 (6): 1339.
- This method provides a graphite oxide which can then be exfoliated in an ultrasonic bath to prepare the graphene oxide used in step S1.
- the first aqueous solution 1 may typically contain water and several layers of graphene oxide.
- an organic compound 2 based on nitrogen and sulfur is added to the aqueous suspension 1.
- This compound may for example be chosen from thiourea or thiourea derivatives.
- the water of the first aqueous suspension is evaporated with mechanical stirring by heating in an oil bath to obtain a powder comprising graphene oxide sheets.
- the powder is heated in an oven at temperatures typically between 700 ° C and 1100 ° C under an inert atmosphere (eg argon) for about 2 hours.
- This step allows the nitrogen and sulfur of the nitrogen and sulfur compound 2 to be inserted into the graphene oxide.
- the oven gradually increases in temperature to favor the incorporation of nitrogen preferentially into graphite sites of graphene oxide.
- the intermediate compound 20 based on nitrogen-doped graphene oxide 21 and sulfur 31 thus obtained is added in a second aqueous suspension 3 comprising a water / ethanol mixture in proportions of 50/50 during a step S5.
- Cobalt oxide 4 or cobalt nitrate hexahydrate is added to the second aqueous suspension.
- Ammonia may be added to the second aqueous suspension 3 which is then heated at a temperature of 100 ° C for about 10 minutes so as to promote the growth of cobalt oxide nanoparticles 41 on a surface of at least one sheet of graphene oxide doped with nitrogen and sulfur, during a step S6.
- the heating of the second aqueous solution can be done by microwave heating, while the prior art generally uses a hydrothermal heating.
- Microwave heating appears to contribute to forming spherical cobalt oxide nanoparticles having a size between 2 nm and 5 nm, directly on the surface of a sheet of graphene oxide doped with nitrogen and sulfur, with a homogeneous distribution. on this surface.
- step S7 comprises graphene oxide sheets comprising nitrogen heteroatoms 21, sulfur heteroatoms 31 and cobalt oxide nanoparticles 41 substantially uniformly distributed over the surface of the leaflets.
- the process of the present invention naturally leads to the formation of a compound in which nitrogen 21 represents up to 4 atomic% of a sheet of compound 30, and occupies different sites in the sheet.
- nitrogen 21 occupies between 15% and 50% of graphitic sites, between 25% and 35% of pyrrolic sites and between 30% and 40% of pyrinidic sites in the compound 30.
- the nitrogen doping 21 may lead to a distribution of nitrogen either on the edges of the graphene oxide sheet, or in substitution of carbon atoms in the leaflet itself.
- the sulfur 31 occupies up to 0.6 atomic% of a sheet of the compound 30, the oxygen occupies about 1.4 atomic% of a sheet of the compound 30 and the carbon about 93.7 atomic%.
- the sulfur atoms in the compound 30 are 76% in the form of CSC or CSF groups and 24% in the form of C-SO n groups .
- FIG. 2 schematically represents a two-dimensional plan of graphene 200 doped with nitrogen.
- This figure illustrates an example of a graphitic site 201, an example of a pyrrolic site 202, an example of a pyridinic site 203, a pyridinium 204 and a pyridine nitrogen N-oxide 205.
- FIG. 3 schematically shows a graphene oxide sheet 10 comprising carbon atoms 12, oxygen atoms 11 and hydrogen atoms 13.
- Oxygen can typically form three different chemical bonds in graphene.
- a first type of bond 101 consists of forming an epoxide group.
- a second Linkage type 102 consists of forming a hydroxyl group.
- a third type of bond 103 consists of forming a carboxyl group.
- FIG. 4 schematically illustrates a metal-air battery 400 comprising a negative terminal 410, and at least one positive terminal 411.
- the battery comprises an electrolyte 403 separating a negative electrode 401 from at least one positive electrode 402.
- the positive electrode 402 is in the case of the invention an air electrode comprising the compound 30 described above in its structure.
- the precursor material is commercial graphite powder (with grain sizes less than 20 ⁇ m).
- the graphite powder typically 3 g is dispersed in a solution of sulfuric acid (46 ml) with magnetic stirring for 10 min.
- Sodium nitrate 1.5 g is added to the suspension.
- the mixture is stirred mechanically for 10 minutes. This entire process is carried out at 20 ° C.
- the suspension is then cooled using an ice bath. 9 g of potassium permanganate are then added to the suspension which is still kept under magnetic stirring.
- the whole mixture is then brought to the temperature of 35 ° C. for 30 min by means of heating by an oil bath.
- An amount (for example 10 mL) of pure water is added to the mixture.
- the temperature of the oil bath is then raised to 98 ° C for 15 minutes.
- the mixture is then cooled with an ice bath.
- 420 ml of water and then 5 ml of hydrogen peroxide are then added to the reaction mixture.
- the suspension is kept under magnetic stirring for 30 minutes.
- the material then undergoes a recovery and washing protocol.
- the suspension is centrifuged for 15 min at a radial centrifugal acceleration (ACR) of 2744 g and at a controlled temperature of 5 ° C. Following the centrifugation step the supernatant is removed. The pellet is resuspended in a hydrochloric acid solution.
- the suspension is again centrifuged for 15 min at an ACR of 2744 g and at a controlled temperature of 5 ° C.
- This washing operation is repeated twice. The same washing operation is repeated 5 times by replacing the hydrochloric acid with pure water but this time at a temperature of 20 ° C.
- the solid is dried in an oven (typical temperature of 40 ° C) for 48 hours. The powder is then ground manually in a mortar.
- the graphene oxide sheets are doped with nitrogen, with sulfur as well as with nanoparticles of cobalt oxide.
- Graphene oxide is first exfoliated by the application of ultrasonic waves.
- An aqueous suspension (pure water, volume 200 mL) containing a concentration of 1 mg / mL of the previously obtained solid is firstly produced.
- the suspension is placed in an ultrasonic bath (800 W) for 1 h.
- 8 mg / ml of thiourea are added.
- the suspension is then stirred mechanically for 30 min.
- the water is then evaporated with mechanical stirring by heating in an oil bath at 100 ° C.
- a heat treatment of the powder thus obtained is then carried out at 700 ° C. under an argon atmosphere for 2 hours.
- the temperature rise of the oven is 10 ° C / min.
- the oven is then cooled by inertia.
- cobalt oxide nanoparticles also called Co-based nanostructured spinels
- the deposition of cobalt oxide nanoparticles can be achieved by the method described below.
- the reduced graphene oxide powder doped with sulfur and nitrogen atoms (N, S-RGO, for "nitrogen, sulfur and reduced graphene oxide”), obtained at the end of the steps of synthesis described in the preceding paragraph, is re-dispersed in a mixture of pure water / ethanol in a proportion of 50/50 by volume, at a rate of 1 mg of powder per milliliter of liquid.
- This suspension is kept under magnetic stirring for 24 hours in order to ensure the dispersion of the layers of reduced and doped graphene oxide in the water / ethanol mixture.
- the suspension is then placed in an ultrasonic bath for 1 h, to ensure that exfoliation of the material is maintained.
- the 20 ml of suspension are transferred to a 30 ml volume glass reactor for a monomode microwave oven.
- the control of the synthesis temperature is ensured by a temperature probe (for example a plunging probe ruby). After a rise in temperature in a few seconds until reaching 100 ° C. in the reaction medium, this temperature is kept constant for 10 minutes.
- the reactor is then cooled in the microwave by a flow of compressed air for a few minutes.
- the material is obtained in the form of an unstable suspension which sediments in a few seconds. He undergoes a protocol of recovery and washing. The suspension is centrifuged at an ACR of 29220 g for 30 minutes. The supernatant is then removed. The black powder remaining on the wall of the tube is then resuspended in pure water. This washing operation is repeated until the pH of the supernatant reaches a value between 7 and 7.5. Finally, the solid is dried under vacuum at 45 ° C for 12 h and the recovered powder is ground manually in a mortar.
- the material is characterized by X-ray diffraction.
- Fig. 5 shows an X-ray diffractogram of Co 3 O 4 on reduced nitrogen and sulfur doped graphene oxide.
- the ordinate axis 501 represents the intensity of the signal detected by diffractometry
- the abscissa axis 502 represents the orientation angle of the X-ray beam, 2 theta.
- Reference peaks (indicated by the lines 503) show a single crystalline phase Co 3 0 4 as well as the presence of a small amount of stacked GRO sheets, evidenced by a 504large peak at about 31 ° (2-theta Lambda Co). Ka).
- the morphology is characterized by transmission electron microscopy.
- the monocrystalline CO 3 O 4 particles are in spherical form with a diameter varying between 2 and 5 nm.
- a peculiarity of the material is the selective deposition of the CO 3 O 4 nanoparticles on the N, S-RGO sheets: the proportion of unsupported nanoparticles is very small, less than about 10% by number.
- the charge rate is estimated at 50% by mass (ratio of the mass of the nanoparticles supported on the total mass of the material, considering that 90% of the particles are actually deposited on the GRO) by thermogravimetric analysis.
- FIG. 6 shows that the nanoparticles are distributed in a substantially homogeneous manner on each sheet of graphene oxide doped with nitrogen and sulfur.
- FIG. 6 represents the percentage of nanoparticles while the axis 602 represents the distance in nanometers separating two neighboring nanoparticles of cobalt oxide.
- 80% of the distances separating two neighboring nanoparticles of cobalt oxide 41 are between 0.5 nm and 3 nm, and only 16% of the nanoparticles are aggregated.
- Electrochemical measurements to evaluate the catalytic properties of the material vis-à-vis oxygen release and reduction reactions are performed using a potentiostat.
- the measurements are carried out in an aqueous electrolytic medium consisting of potassium hydroxide at a concentration of 1 mol / l.
- the measurements are carried out in an electrochemical cell with 3 electrodes of volume 50 ml.
- a saturated calomel reference electrode is employed.
- a counter electrode consisting of a vitreous carbon plate is used.
- the electrolyte is previously saturated with oxygen for 30 min.
- the electrolyte (100 mL) is made by dissolving 6.4 g of potassium hydroxide pellets in pure water.
- an ink is first produced.
- This ink consists of 750 ⁇ l of pure water, 250 ⁇ l of isopropanol and 60 ⁇ l of a solution of Nafion® 5% by weight in a mixture of aliphatic alcohols and 5 mg of powder of the previously synthesized material.
- the electrochemical measurements are performed under quasi-stationary conditions using a rotating disk electrode.
- the measurements to determine the activity of the material with respect to the oxygen reduction reaction are carried out at rotating rotational electrode speeds of 400, 900, 1600 and 2500 rotations per minute in the range.
- potential of between 1 and 0.25 V / ERH (ERH designating the reference electrode with hydrogen) at a linear variation rate of potential of 5 mV / s.
- the measurements to determine the activity of the materials with respect to the oxygen evolution reaction were carried out at a rotational speed of the rotating disk electrode of 1600 rotations per minute in the range of potential between 1 and 1,8 V / ERH at a linear rate of variation of potential of 5 mV / s.
- the reversibility criterion is determined by calculating the potential difference between the potential required to have a current density of 10 mA / cm during the oxygen evolution reaction and the potential required to have current density of -1 mA / cm during the reduction reaction.
- a reversibility criterion of 0.78 V is obtained for the composite material comprising a carbon loading rate of 50%.
- An evaluation of the stability of the materials was subsequently performed using an air electrode.
- This electrode consists of a Teflon body.
- the electrical connection is provided via a gold wire.
- the mechanical conductive support used to deposit the catalyst is a nickel foam previously treated by immersion in a 6 mol / L hydrochloric acid solution for 30 min.
- the foam is subsequently washed and dried in an oven at 80 ° C.
- a catalytic ink consisting of 54 ⁇ l of a 60% aqueous PTLE solution, 2 ml of ethanol and 8 mg of catalytic powder is produced.
- the homogenization of the ink is carried out by using an ultrasonic bath at 800 W for 1 h.
- the nickel foam is impregnated with catalytic dip ink or "dip coating" according to the English terminology.
- the deposited catalyst mass is verified by weighing.
- the cycling stability of the catalytic material is then evaluated in an aqueous electrolytic medium containing an electrolyte consisting of potassium hydroxide at a concentration of 6 mol / L.
- Electrochemical measurements by chronopotentiometry are carried out by using a potentiostat in an electrochemical cell with 3 electrodes of volume 50 ml.
- a saturated silver chloride reference electrode is employed.
- a counter electrode consisting of a vitreous carbon plate is used.
- Current densities of -8 mA / cm and 10 mA / cm are respectively applied during the discharge and charge cycles.
- the charging and discharging cycles have respective durations of 8 and 12 h and the total duration of the test is 214 h.
- Figure 7 illustrates the results of these cycling tests, performed by alternately applying current densities of -8 mA / cm (for 12 h) and 10 mA / cm (for 8 h).
- the axis 701 denotes the measured potential with respect to the Ag / AgCl / KCl (saturated) pair in volts.
- the axis 702 designates the current density measured in mA / cm 2 and the axis 703 designates the time in hours. This figure shows that the air electrode comprising the compound 30 described above does not undergo degradation in cycling, and keep the same electrical performance even after several cycles of charging / discharging.
- a second test was performed on electrodes containing the material object of the invention bound with PTFE only on a nickel grid. These electrodes were cycled at +30 mA / cm 2 and -30 mA / cm 2 under ambient air in an 8 mol / L solution of KOH. No degradation was observed over 50 cycles.
Abstract
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FR1761794A FR3074968B1 (fr) | 2017-12-07 | 2017-12-07 | Electrode a air reversible a base d'un oxyde de graphene |
PCT/FR2018/053125 WO2019110933A1 (fr) | 2017-12-07 | 2018-12-05 | Procédé de fabrication d'un composé à base d'oxyde de graphène pour électrode à air d'une batterie métal-air et composé associé |
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EP3721497A1 true EP3721497A1 (fr) | 2020-10-14 |
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EP18826431.1A Pending EP3721497A1 (fr) | 2017-12-07 | 2018-12-05 | Procédé de fabrication d'un composé à base d'oxyde de graphène pour électrode à air d'une batterie métal-air et composé associé |
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US (1) | US11489159B2 (fr) |
EP (1) | EP3721497A1 (fr) |
CN (1) | CN111602276A (fr) |
FR (1) | FR3074968B1 (fr) |
WO (1) | WO2019110933A1 (fr) |
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CN110492108B (zh) * | 2019-07-30 | 2022-09-02 | 武汉理工大学 | 氮硫共掺杂石墨烯基负载核壳纳米粒子复合材料及其制备方法和应用 |
FR3104828B1 (fr) | 2019-12-13 | 2022-11-11 | Electricite De France | Procédé de fabrication d’une électrode à gaz présentant un gradient de composition |
CN114583127B (zh) * | 2022-02-28 | 2023-05-09 | 南京工业大学 | 一种制备CoNi-S@3D-C纳米复合材料和改性电池隔膜的方法 |
CN114515552B (zh) * | 2022-03-11 | 2023-03-07 | 山东大学 | 一种NiCo合金@氮掺杂石墨烯多级孔气凝胶及其制备方法与在锌-空气电池中的应用 |
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EP2687483A1 (fr) * | 2012-07-16 | 2014-01-22 | Basf Se | Graphène contenant de l'azote et éventuellement du fer et/ou du cobalt |
US20180093893A1 (en) * | 2015-04-02 | 2018-04-05 | Case Western Reserve University | Metal-free bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions |
US20170098843A1 (en) * | 2015-10-06 | 2017-04-06 | Board Of Regents, The University Of Texas System | Membraneless direct liquid fuel cells |
CN105268440A (zh) * | 2015-11-06 | 2016-01-27 | 河南理工大学 | 一种石墨烯负载氧化钴催化剂及其制备方法 |
CN105417532A (zh) * | 2015-12-22 | 2016-03-23 | 北京理工大学 | 一步法制备高氮掺杂石墨烯 |
KR101854514B1 (ko) * | 2016-02-12 | 2018-05-04 | 영남대학교 산학협력단 | 3차원 니켈폼 상의 다층 메조기공 구조의 그래핀/니켈-코발트-황화물 배열 복합체 및 이의 제조방법 |
CN106684389A (zh) * | 2016-12-30 | 2017-05-17 | 温州大学 | 硫氮双掺杂石墨烯纳米材料及其制备方法与应用 |
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2018
- 2018-12-05 EP EP18826431.1A patent/EP3721497A1/fr active Pending
- 2018-12-05 CN CN201880086568.6A patent/CN111602276A/zh active Pending
- 2018-12-05 US US16/769,344 patent/US11489159B2/en active Active
- 2018-12-05 WO PCT/FR2018/053125 patent/WO2019110933A1/fr unknown
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US11489159B2 (en) | 2022-11-01 |
US20200313185A1 (en) | 2020-10-01 |
CN111602276A (zh) | 2020-08-28 |
FR3074968A1 (fr) | 2019-06-14 |
FR3074968B1 (fr) | 2021-09-17 |
WO2019110933A1 (fr) | 2019-06-13 |
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