CA2469407C - Carbon-carbon composite particles, their preparation and use therefore as negative electrode for li-ion batteries - Google Patents
Carbon-carbon composite particles, their preparation and use therefore as negative electrode for li-ion batteries Download PDFInfo
- Publication number
- CA2469407C CA2469407C CA2469407A CA2469407A CA2469407C CA 2469407 C CA2469407 C CA 2469407C CA 2469407 A CA2469407 A CA 2469407A CA 2469407 A CA2469407 A CA 2469407A CA 2469407 C CA2469407 C CA 2469407C
- Authority
- CA
- Canada
- Prior art keywords
- carbon
- particles
- high crystallinity
- crystallinity carbon
- heating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- 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
-
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- 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
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Composite Materials (AREA)
- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
There is provided a process for preparing a composite of particles of a high crystallinity carbon and a low crystallinity carbon comprising the steps of: (i) dispersing a carbon powder having a high crystallinity and a polymeric substance in a solvent and mixing until evaporation of 40 to 60% of the solvent; and (ii) heating the resulting mixture at a temperature ranging from 1200°C to 2500°C.
Description
CARBON-CARBON COMPOSITE PARTICLES, THEIR PREPARATION
AND USE THEREFORE AS NEGATIVE ELECTRODE FOR LI-ION
BATTERIES
TECHNICAL FIELD
The present invention relates to composite carbone-carbone particles obtained from a low cristallinity carbon and of a high cristallinity carbon.
The present invention also relates to a process for preparing the composite carbon-carbon particles of the invention by dispersing and mixing together low cristallinity carbon particles with high cristallinity carbon particles.
The present invention also relates to a process for preparing the composite carbone-carbone particles of the invention by mixing carbon particles with a polymeric substance and by heating the mixture thereby obtained until carbonization of the polymeric substance on the surface of the carbon particles.
A further aspect of the present invention is the use of the composite particles inter alia in foundry industry, in sports equipment, in the automobile and in aeronautic industries and the use of those particles as constituents of electrode material in electrochemical systems.
PRIOR ART
Li-ion batteries are now considered one of the best existing power sources for portable electronics such as cell-phones, camcorders, laptop computer and power tools. A Li-ion cell typically consists of a carbon-based negative electrode (NE), = porous polymer membrane separator (polypropylene and/or polyethylene) and a lithium transition metal oxide (LiM02, M=Co, Ni, or Mn) based positive electrode (PE), as described in Nishi in Advances in Lithium ¨ion batteries, edited by
AND USE THEREFORE AS NEGATIVE ELECTRODE FOR LI-ION
BATTERIES
TECHNICAL FIELD
The present invention relates to composite carbone-carbone particles obtained from a low cristallinity carbon and of a high cristallinity carbon.
The present invention also relates to a process for preparing the composite carbon-carbon particles of the invention by dispersing and mixing together low cristallinity carbon particles with high cristallinity carbon particles.
The present invention also relates to a process for preparing the composite carbone-carbone particles of the invention by mixing carbon particles with a polymeric substance and by heating the mixture thereby obtained until carbonization of the polymeric substance on the surface of the carbon particles.
A further aspect of the present invention is the use of the composite particles inter alia in foundry industry, in sports equipment, in the automobile and in aeronautic industries and the use of those particles as constituents of electrode material in electrochemical systems.
PRIOR ART
Li-ion batteries are now considered one of the best existing power sources for portable electronics such as cell-phones, camcorders, laptop computer and power tools. A Li-ion cell typically consists of a carbon-based negative electrode (NE), = porous polymer membrane separator (polypropylene and/or polyethylene) and a lithium transition metal oxide (LiM02, M=Co, Ni, or Mn) based positive electrode (PE), as described in Nishi in Advances in Lithium ¨ion batteries, edited by
2 W.Schalkwijik Cluwer Academic/plenum publishers, 2002, page 233, electrodes are made by casting slurries of active materials, polymer-based binder (i.e.
polyvinylidene difluoride, PVDF) and small amounts of high surface area carbon onto metal foil current collectors. Mixtures of Li-salts and organic solvents provide an electrolyte medium for Li-ions to shuttle between the PE and NE.
During charge, Li-ions deintercalate from the PE and intercalate into the NE, while the reverse takes place during discharge as mentioned in A. Webber and G.
Blomgren in Adavances in Lithium ¨ion batteries, edited by W.Schalkwijik Cluwer Academic/plenum publishers, 2002, on page 185.
The evolving products require a Li-ion cell with a longer cycle-life, higher energy and charge/discharge rate capabilities. Long cycle-life e.g. is critical for the Li-ion battery to last the lifetime of the host device (such as: embedded electronics and medical prosthesis); and high capacity and rate capability are needed for the EV, aerospace and military applications.
For the development of Li-ions of such unique properties, battery manufacturers and research groups have been investigating possible applications of new and/or modified PE and NE materials.
These included utilization of In/Si-based intermetallic alloys, metal-carbon and carbon-carbon composites as NE-materials, and mixed metal-oxides as PE-material, as disclosed in R. Huggins in Handbook of battery materials edited by J.
Besenhard Wiley-vch, 1999, page 359.
However, despite their high capacity, available NE-materials containing carbon-carbon composite, present the drawback of limited cyclic life, when available NE-materials containing In/Si-based intermetallic alloys despite their capacity present the drawback to be used commercial lithium-ion batteries.
3a SUMMARY OF INVENTION
In accordance with a first aspect of the invention, there is provided a composite of particles comprising a high crystallinity carbon and a low crystallinity carbon, wherein:
the low crystallinity carbon exhibits an average latice constant d¨(002) of 0.350 nm or more and a crystallite size L¨(002) in the diffraction of C axis of 25 nm or less, as characterized by wide-angle X-ray diffraction measurements;
the high crystallinity carbon exhibits an average latice constant d¨(002) of 0.338 nm or less and a crystallinity size L=(002) in the diffraction of C axis of 40 nm or more, as characterized by wide-angle X-ray diffraction measurements;
the high crystallinity carbon having at least 50% of its external surface embedded within or surrounded by a matrix of low crystallinity carbon; and the high crystallinity carbon forms particles having a particle size ranging from 1 to 50 micrometers, the high crystallinity carbon particles being at least partially covered by particles of low crystallinity carbon having a particle size ranging from 10 to 500 nm, the low crystallinity carbon particles being attached to the surface of the high crystallinity carbon particles.
In accordance with another aspect of the invention, there is provided a process for preparing a composite of particles of a high crystallinity carbon and a low crystallinity carbon, wherein:
the low crystallinity carbon exhibits an average lattice constant d=(002) of 0.350 nm or more and a crystallite size L=(002) in the direction of C axis of 25 nm or less, as characterized by wide-angle X-ray diffraction measurements;
the high crystallinity carbon exhibits an average lattice constant d-=(002) of 0.338 nm or less and a crystallinity size L¨(002) in the direction of C axis of 40 nm or more, as characterized by wide-angle X-ray diffraction measurements; and the high crystallinity carbon forms particles having a particle size ranging from 1 to 50 micrometers, the high crystallinity carbon particles being at least partially covered by particles of the low crystallinity carbon having a particle size ranging from 10 to 500 nm, the low crystallinity carbon particles being attached to the surface of the high crystallinity carbon particles;
said process comprising the steps of:
3b (i) dispersing a carbon powder having a high crystallinity and a polymeric substance in a solvent and mixing until evaporation of 40 to 60% of the solvent; and (ii) heating the resulting mixture at a temperature ranging from 1200 C to 2500 C.
In accordance with a further aspect of the invention, there is provided a process for preparing a negative electrode wherein:
- a high crystallinity carbon is dispersed in a liquid Phenolic Resin (PF) dissolved in alcohol and mixed using ball milling until complete dispersion of the high crystallinity carbon in the PF and vaporization of 40 to 60 wt % of the alcohol;
- the mixture obtained is pored on a flat Al -plate, then heated to 150 C
to 175 C
and thermally soaked for 2.0 hours, with a heating rate which varies from 3 C
to 8 C/min;
- the solid sheet obtained is removed from the Al -plate and submitted to a heat treatment comprising the steps of:
i) heating to 600 C and maintaining at 600 C for 2 hours, ii) heating to 1000 C at a heating rate of 20 C to 30 C/min and maintaining at 1000 C for 2 hours, and iii) heating at 2500 C at a heating rate of 100 C/min and maintaining at 2500 C for 1 min.
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 is a graph that represents the thermal profile of the heat treatment of a (Carbon#2: polymerized PF-matrix) prepared according to a process of the invention as described thereafter under "sample preparation".
Figures 2a to 2d are schematic pictorial model representations of the steps occurring during processing of the proposed carbon-carbon composite material for NE in Li-ion cells, in the case wherein carbon#2 progressively covers carbon#1 particles with a network of carbon#2.
Figure 3 A is an SEM image of the carbon-carbon material according to sample 1 hereinafter defined in Table I, the carbon#lis derived from carbonization of PF, which cover partially the surface of carbon#2(graphite).
Figure 3B is the same SEM image as in Figure 3A, but at a larger scale.
Figure 4A is an SEM image of the carbon-carbon material according to sample 2 defined hereinafter in Table I, the carbon#lis derived from carbonization of PF
and covers almost totally the surface of carbon#2 (graphite); the measured particle size of icarbon#lis from 39nm to 500nm.
Figure 4B is the same SEM image as in Figure 4A, at a larger scale.
Figure 5A is an SEM image of the carbon-carbon material according to sample 3 as defined hereinafter in Table I. The carbon#1 is derived from carbonization of PF, which covers partially the surface of carbon#2 (graphite), but still some graphite particles are not covered at all. The particle size of carbon#lis from 20nm to 500nm.
Figure 5B is the same image as in Figure 5A but at a larger scale.
Figure 6A is an SEM image of the carbon-carbon material according to sample 4 as defined hereinafter in Table I. The carbon#1 is derived from carbonization of PF, which covers almost totally the surface of carbon#2 (graphite). The carbon #1 5 is more compact and it's particle size is from 20nm to 500nm.
Figure 6B is the same image as in Figure 6A but at a larger scale.
Figure 7 shows Transmission Electron Micrograph a carbon-carbon composite according to the invention, that has been prepared according to samples 3 and and heat treated to 2.500 C.
DESCRIPTION OF DTP, INVENTION
A first object of the present invention is constituted by composite particles of carbon, thereafter named Carbon#1-Carbon#2 composite particles, wherein Carbon#1 means a low cristallinity carbon and Carbon#2 means a high cristallinity carbon.
In the framework of the present invention, the expression Carbon#1 means carbon particles, having a low cristallinity characterized by wide-angle X ray diffraction measurements, i.e by an average lattice constant d---(002) of 0.350 rim or more and a crystallite size L=(002) in the direction of C axis of 25 rim or less. Such low cristallinity carbon is more extensively described in Carbon electrochemical and physicochemical properties, John Wiley, New York, 1988.
According to a preferred embodiment of the invention low cristallinity carbons are selected in the group constituted by hard carbon, glassy carbons, polymer derived carbons and petroleum cokes.
In the framework of the present invention, the expression Carbon#2 means a high crystallinity carbon characterized by wide-angle X ray diffraction measurements, i.e by an average lattice constant d=(002) of 0.338 nm or less and a crystallinity size L=(002) in the direction of C axis of 40 nm or more. Such high cristallinity carbon is more extensively defined in Carbon electrochemical and physicochemical properties, John Wiley, New York, 1988. According to a preferred embodiment of the invention such high cristallinity carbon is selected in the group constituted by graphite, preferably natural graphites, kish graphite, pyrolytic graphite, gas-growth graphite or any artificial graphite.
A preferred family of Carbon#1-Carbon#2 composite particles of the invention is constituted by those composite particles having at least one of the following physical properties:
- a package density, according to the tap density method associated to the apparatus commercialized under the name Logan Instrument Corp. Model Tap-2, that is > 0,5 g/cc.
- a particle size, measured according to the SEM method associated with apparatus Microtac model X100 Particle Analyser, ranges from 0.5 to 100 micrometers; and - a specific surface area, measured according to the BET method, ranging from 1 to 50 m2/g.
As shown inter alia in Figures 2, the composite particles of the invention may be described as low cristallinity particles of Carbon#1 embedded or surrounded by a matrix (or by a network) of graphite Carbon#2.
According to an another aspect of the invention, the composite particles of the invention may be described as particles of Carbon#2 embedded or surrounded by a matrix (or a network) of Carbon#1.
Therefore, particles of a high cristallinity carbon (preferably a graphitic carbon) are embedded within or surrounded by the matrix of a second carbon that has lower degree of cristallinity (graphitization), also known as hard carbon.
A second object of the present invention is constituted by the use of the composite particles according to the first object of the present invention as a constituent of an electrode material, preferably as a constituent of a N-E (negative electrode) material in electrochemical systems, in the foundry industry, in the car and in aeronautic industries, in sports equipment.
A third object of the present invention is constituted by negative electrodes comprising between 2 to 98 % and preferably by those comprising at least 90 weight per cent of a composite particles of the invention, the remaining being preferably constituted by at least one binder. The binder is preferably of the PVDF
type.
A fourth object of the present invention is constituted by a battery system comprising at least one electrode containing carbon-carbon composite particles according the invention. Preferably, in the battery system of the invention, the electrode containing composite particles is a negative electrode.
According to an another embodiment, the battery system is of the N-E/electrolyte/PE type.
According to a further preferred embodiment of the invention the battery system consists, of wined/stacked layers or of winded/stacked layers of electrodes of electrodes, at least one of said electrodes comprising carbon-carbon composite particles according to the invention.
A preferred embodiment is constituted by Li-ion battery comprising a negative electrode, a positive electrode and a porous polymer membrane separator for example of the Celguard type, wherein at least one of said electrodes is a negative electrode according to the invention.
A fifth object of the present invention is constituted by a process for preparing the composite material particles according to the first object of the invention.
This process preferably comprises the steps of dispersing and mixing, preferably by using ball milling, at least one Carbon#1 powder, preferably in the form of a slurry of a polymeric substance that results in carbon particles by heat treatment.
The polymeric substance, preferably a polymer with a high carbon content, is preferably dispersed in an organic solvent in a slurry that can easily stick on the surface of the carbon particles to be covered. The polymeric material is preferably dispersed in a liquid Phenolic Resin (PF). Appropriate phenolic resins are for example those commonly used in the foundry industry. Phenolic resins are the most widely used resin binders in the foundry industry. They are produced by polycondensation of phenols with formaldehyde. The three types of resins presented in the following Table differ in catalyst and mole ratio of reactants used in their preparation. Furthermore, they have different molecular structures and reactivities and require different curing agents.
Table - Some examples of Phenolic Resins Novolacs Resoles Polybenzylic ethers ratio of phenol to >1 <1 <1 formaldehyde acidic basic neutral, metal sal pH conditions thermoplastic thermosetting anhydrous thermal behavior shell process hot-box process thermosetting foundry process no-bake process cold-box process no-bake process There are two further categories of epoxy resins that may be successfully used, namely the glycidyl epoxy, and non-glycidyl epoxy resins. The glycidyl epoxies are further classified as glycidyl-ether, glycidyl-ester and glycidyl-amine.
The diglycidyl ether of bisphenol-A (DGEBA) is a typical commercial epoxy resin and is synthesised by reacting bisphenol-A with epichlorohydrin in presence Of a basic catalyst.
The Novolac Epoxy Resins are glycidyl ethers of phenolic novolac resins.
The mixing process is advantageously continued until complete dispersion of Carbon#1 in the PF and preferably until vaporization of 40 to 60 wt % of the containing solvent (preferably water, or organic solvent such as an alcohol) from PF. Among preferred solvent for preparing the PF dispersions are water and organic solvents such as alcohols.
The heat treatment is preferably carried out at a temperature ranging from 400 to 2.800 Celsius, and more preferably at a temperature ranging from 1.000 to 2.500 C.
A sixth object of the present invention is constituted by a process for preparing a negative electrode. This process comprises the steps of:
- a) dispersing and mixing, preferably by using ball milling, at least 5 one Carbon#2 powder, in preferably a liquid Phenolic Resin (PF), the mixing process being preferably continued until complete dispersion of carbon#2 in the PF and preferably until vaporization of 40 to 60 wt % of the containing solvant (preferably water, or organic solvant such as an alcohol) from the PF;
b) poring the mixture obtained in the preceding step on a support, preferably on a flat Al-plate, on a Cu-plate, on an alu-Exmet or on a cupfer Exmet, then heated preferably to 150-175 C, more preferably to 160-170 C and thermally soaked, for 1 to 5 hours, preferably for about 2.0 hours, the heating rate varying preferably from 3-8 C/min depending on the thickness of the sample;
- c) after the preceding heating step, preferably converting the sample into solid sheets from which the support (AL-plate was separated);
and - d) treating the Carbon#2: polymerized PF-matrix obtained in the preceding step at a temperature ranging from 600 to 2.500 C, preferably at a temperature ranging from 600 to 1.000 C using 30-50 Chinn heating rate following thermal profile shown in Figure 1.
Then the carbon#lis produced by carbonization of PF-matrix.
Any polymeric material, particularly any polymeric material with a high carbon content and more preferably any PF transforms to graphite up to heating through the following process:
- 1. PF Polymerizes to a rubbery gel on heating to 85 C (gelling process);
- 2. on heating to 120 C, the rubbery gel cures to form a hard cross-linked polymer by condensation reaction which produces water;
polyvinylidene difluoride, PVDF) and small amounts of high surface area carbon onto metal foil current collectors. Mixtures of Li-salts and organic solvents provide an electrolyte medium for Li-ions to shuttle between the PE and NE.
During charge, Li-ions deintercalate from the PE and intercalate into the NE, while the reverse takes place during discharge as mentioned in A. Webber and G.
Blomgren in Adavances in Lithium ¨ion batteries, edited by W.Schalkwijik Cluwer Academic/plenum publishers, 2002, on page 185.
The evolving products require a Li-ion cell with a longer cycle-life, higher energy and charge/discharge rate capabilities. Long cycle-life e.g. is critical for the Li-ion battery to last the lifetime of the host device (such as: embedded electronics and medical prosthesis); and high capacity and rate capability are needed for the EV, aerospace and military applications.
For the development of Li-ions of such unique properties, battery manufacturers and research groups have been investigating possible applications of new and/or modified PE and NE materials.
These included utilization of In/Si-based intermetallic alloys, metal-carbon and carbon-carbon composites as NE-materials, and mixed metal-oxides as PE-material, as disclosed in R. Huggins in Handbook of battery materials edited by J.
Besenhard Wiley-vch, 1999, page 359.
However, despite their high capacity, available NE-materials containing carbon-carbon composite, present the drawback of limited cyclic life, when available NE-materials containing In/Si-based intermetallic alloys despite their capacity present the drawback to be used commercial lithium-ion batteries.
3a SUMMARY OF INVENTION
In accordance with a first aspect of the invention, there is provided a composite of particles comprising a high crystallinity carbon and a low crystallinity carbon, wherein:
the low crystallinity carbon exhibits an average latice constant d¨(002) of 0.350 nm or more and a crystallite size L¨(002) in the diffraction of C axis of 25 nm or less, as characterized by wide-angle X-ray diffraction measurements;
the high crystallinity carbon exhibits an average latice constant d¨(002) of 0.338 nm or less and a crystallinity size L=(002) in the diffraction of C axis of 40 nm or more, as characterized by wide-angle X-ray diffraction measurements;
the high crystallinity carbon having at least 50% of its external surface embedded within or surrounded by a matrix of low crystallinity carbon; and the high crystallinity carbon forms particles having a particle size ranging from 1 to 50 micrometers, the high crystallinity carbon particles being at least partially covered by particles of low crystallinity carbon having a particle size ranging from 10 to 500 nm, the low crystallinity carbon particles being attached to the surface of the high crystallinity carbon particles.
In accordance with another aspect of the invention, there is provided a process for preparing a composite of particles of a high crystallinity carbon and a low crystallinity carbon, wherein:
the low crystallinity carbon exhibits an average lattice constant d=(002) of 0.350 nm or more and a crystallite size L=(002) in the direction of C axis of 25 nm or less, as characterized by wide-angle X-ray diffraction measurements;
the high crystallinity carbon exhibits an average lattice constant d-=(002) of 0.338 nm or less and a crystallinity size L¨(002) in the direction of C axis of 40 nm or more, as characterized by wide-angle X-ray diffraction measurements; and the high crystallinity carbon forms particles having a particle size ranging from 1 to 50 micrometers, the high crystallinity carbon particles being at least partially covered by particles of the low crystallinity carbon having a particle size ranging from 10 to 500 nm, the low crystallinity carbon particles being attached to the surface of the high crystallinity carbon particles;
said process comprising the steps of:
3b (i) dispersing a carbon powder having a high crystallinity and a polymeric substance in a solvent and mixing until evaporation of 40 to 60% of the solvent; and (ii) heating the resulting mixture at a temperature ranging from 1200 C to 2500 C.
In accordance with a further aspect of the invention, there is provided a process for preparing a negative electrode wherein:
- a high crystallinity carbon is dispersed in a liquid Phenolic Resin (PF) dissolved in alcohol and mixed using ball milling until complete dispersion of the high crystallinity carbon in the PF and vaporization of 40 to 60 wt % of the alcohol;
- the mixture obtained is pored on a flat Al -plate, then heated to 150 C
to 175 C
and thermally soaked for 2.0 hours, with a heating rate which varies from 3 C
to 8 C/min;
- the solid sheet obtained is removed from the Al -plate and submitted to a heat treatment comprising the steps of:
i) heating to 600 C and maintaining at 600 C for 2 hours, ii) heating to 1000 C at a heating rate of 20 C to 30 C/min and maintaining at 1000 C for 2 hours, and iii) heating at 2500 C at a heating rate of 100 C/min and maintaining at 2500 C for 1 min.
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 is a graph that represents the thermal profile of the heat treatment of a (Carbon#2: polymerized PF-matrix) prepared according to a process of the invention as described thereafter under "sample preparation".
Figures 2a to 2d are schematic pictorial model representations of the steps occurring during processing of the proposed carbon-carbon composite material for NE in Li-ion cells, in the case wherein carbon#2 progressively covers carbon#1 particles with a network of carbon#2.
Figure 3 A is an SEM image of the carbon-carbon material according to sample 1 hereinafter defined in Table I, the carbon#lis derived from carbonization of PF, which cover partially the surface of carbon#2(graphite).
Figure 3B is the same SEM image as in Figure 3A, but at a larger scale.
Figure 4A is an SEM image of the carbon-carbon material according to sample 2 defined hereinafter in Table I, the carbon#lis derived from carbonization of PF
and covers almost totally the surface of carbon#2 (graphite); the measured particle size of icarbon#lis from 39nm to 500nm.
Figure 4B is the same SEM image as in Figure 4A, at a larger scale.
Figure 5A is an SEM image of the carbon-carbon material according to sample 3 as defined hereinafter in Table I. The carbon#1 is derived from carbonization of PF, which covers partially the surface of carbon#2 (graphite), but still some graphite particles are not covered at all. The particle size of carbon#lis from 20nm to 500nm.
Figure 5B is the same image as in Figure 5A but at a larger scale.
Figure 6A is an SEM image of the carbon-carbon material according to sample 4 as defined hereinafter in Table I. The carbon#1 is derived from carbonization of PF, which covers almost totally the surface of carbon#2 (graphite). The carbon #1 5 is more compact and it's particle size is from 20nm to 500nm.
Figure 6B is the same image as in Figure 6A but at a larger scale.
Figure 7 shows Transmission Electron Micrograph a carbon-carbon composite according to the invention, that has been prepared according to samples 3 and and heat treated to 2.500 C.
DESCRIPTION OF DTP, INVENTION
A first object of the present invention is constituted by composite particles of carbon, thereafter named Carbon#1-Carbon#2 composite particles, wherein Carbon#1 means a low cristallinity carbon and Carbon#2 means a high cristallinity carbon.
In the framework of the present invention, the expression Carbon#1 means carbon particles, having a low cristallinity characterized by wide-angle X ray diffraction measurements, i.e by an average lattice constant d---(002) of 0.350 rim or more and a crystallite size L=(002) in the direction of C axis of 25 rim or less. Such low cristallinity carbon is more extensively described in Carbon electrochemical and physicochemical properties, John Wiley, New York, 1988.
According to a preferred embodiment of the invention low cristallinity carbons are selected in the group constituted by hard carbon, glassy carbons, polymer derived carbons and petroleum cokes.
In the framework of the present invention, the expression Carbon#2 means a high crystallinity carbon characterized by wide-angle X ray diffraction measurements, i.e by an average lattice constant d=(002) of 0.338 nm or less and a crystallinity size L=(002) in the direction of C axis of 40 nm or more. Such high cristallinity carbon is more extensively defined in Carbon electrochemical and physicochemical properties, John Wiley, New York, 1988. According to a preferred embodiment of the invention such high cristallinity carbon is selected in the group constituted by graphite, preferably natural graphites, kish graphite, pyrolytic graphite, gas-growth graphite or any artificial graphite.
A preferred family of Carbon#1-Carbon#2 composite particles of the invention is constituted by those composite particles having at least one of the following physical properties:
- a package density, according to the tap density method associated to the apparatus commercialized under the name Logan Instrument Corp. Model Tap-2, that is > 0,5 g/cc.
- a particle size, measured according to the SEM method associated with apparatus Microtac model X100 Particle Analyser, ranges from 0.5 to 100 micrometers; and - a specific surface area, measured according to the BET method, ranging from 1 to 50 m2/g.
As shown inter alia in Figures 2, the composite particles of the invention may be described as low cristallinity particles of Carbon#1 embedded or surrounded by a matrix (or by a network) of graphite Carbon#2.
According to an another aspect of the invention, the composite particles of the invention may be described as particles of Carbon#2 embedded or surrounded by a matrix (or a network) of Carbon#1.
Therefore, particles of a high cristallinity carbon (preferably a graphitic carbon) are embedded within or surrounded by the matrix of a second carbon that has lower degree of cristallinity (graphitization), also known as hard carbon.
A second object of the present invention is constituted by the use of the composite particles according to the first object of the present invention as a constituent of an electrode material, preferably as a constituent of a N-E (negative electrode) material in electrochemical systems, in the foundry industry, in the car and in aeronautic industries, in sports equipment.
A third object of the present invention is constituted by negative electrodes comprising between 2 to 98 % and preferably by those comprising at least 90 weight per cent of a composite particles of the invention, the remaining being preferably constituted by at least one binder. The binder is preferably of the PVDF
type.
A fourth object of the present invention is constituted by a battery system comprising at least one electrode containing carbon-carbon composite particles according the invention. Preferably, in the battery system of the invention, the electrode containing composite particles is a negative electrode.
According to an another embodiment, the battery system is of the N-E/electrolyte/PE type.
According to a further preferred embodiment of the invention the battery system consists, of wined/stacked layers or of winded/stacked layers of electrodes of electrodes, at least one of said electrodes comprising carbon-carbon composite particles according to the invention.
A preferred embodiment is constituted by Li-ion battery comprising a negative electrode, a positive electrode and a porous polymer membrane separator for example of the Celguard type, wherein at least one of said electrodes is a negative electrode according to the invention.
A fifth object of the present invention is constituted by a process for preparing the composite material particles according to the first object of the invention.
This process preferably comprises the steps of dispersing and mixing, preferably by using ball milling, at least one Carbon#1 powder, preferably in the form of a slurry of a polymeric substance that results in carbon particles by heat treatment.
The polymeric substance, preferably a polymer with a high carbon content, is preferably dispersed in an organic solvent in a slurry that can easily stick on the surface of the carbon particles to be covered. The polymeric material is preferably dispersed in a liquid Phenolic Resin (PF). Appropriate phenolic resins are for example those commonly used in the foundry industry. Phenolic resins are the most widely used resin binders in the foundry industry. They are produced by polycondensation of phenols with formaldehyde. The three types of resins presented in the following Table differ in catalyst and mole ratio of reactants used in their preparation. Furthermore, they have different molecular structures and reactivities and require different curing agents.
Table - Some examples of Phenolic Resins Novolacs Resoles Polybenzylic ethers ratio of phenol to >1 <1 <1 formaldehyde acidic basic neutral, metal sal pH conditions thermoplastic thermosetting anhydrous thermal behavior shell process hot-box process thermosetting foundry process no-bake process cold-box process no-bake process There are two further categories of epoxy resins that may be successfully used, namely the glycidyl epoxy, and non-glycidyl epoxy resins. The glycidyl epoxies are further classified as glycidyl-ether, glycidyl-ester and glycidyl-amine.
The diglycidyl ether of bisphenol-A (DGEBA) is a typical commercial epoxy resin and is synthesised by reacting bisphenol-A with epichlorohydrin in presence Of a basic catalyst.
The Novolac Epoxy Resins are glycidyl ethers of phenolic novolac resins.
The mixing process is advantageously continued until complete dispersion of Carbon#1 in the PF and preferably until vaporization of 40 to 60 wt % of the containing solvent (preferably water, or organic solvent such as an alcohol) from PF. Among preferred solvent for preparing the PF dispersions are water and organic solvents such as alcohols.
The heat treatment is preferably carried out at a temperature ranging from 400 to 2.800 Celsius, and more preferably at a temperature ranging from 1.000 to 2.500 C.
A sixth object of the present invention is constituted by a process for preparing a negative electrode. This process comprises the steps of:
- a) dispersing and mixing, preferably by using ball milling, at least 5 one Carbon#2 powder, in preferably a liquid Phenolic Resin (PF), the mixing process being preferably continued until complete dispersion of carbon#2 in the PF and preferably until vaporization of 40 to 60 wt % of the containing solvant (preferably water, or organic solvant such as an alcohol) from the PF;
b) poring the mixture obtained in the preceding step on a support, preferably on a flat Al-plate, on a Cu-plate, on an alu-Exmet or on a cupfer Exmet, then heated preferably to 150-175 C, more preferably to 160-170 C and thermally soaked, for 1 to 5 hours, preferably for about 2.0 hours, the heating rate varying preferably from 3-8 C/min depending on the thickness of the sample;
- c) after the preceding heating step, preferably converting the sample into solid sheets from which the support (AL-plate was separated);
and - d) treating the Carbon#2: polymerized PF-matrix obtained in the preceding step at a temperature ranging from 600 to 2.500 C, preferably at a temperature ranging from 600 to 1.000 C using 30-50 Chinn heating rate following thermal profile shown in Figure 1.
Then the carbon#lis produced by carbonization of PF-matrix.
Any polymeric material, particularly any polymeric material with a high carbon content and more preferably any PF transforms to graphite up to heating through the following process:
- 1. PF Polymerizes to a rubbery gel on heating to 85 C (gelling process);
- 2. on heating to 120 C, the rubbery gel cures to form a hard cross-linked polymer by condensation reaction which produces water;
- 3. on heating to 225 C, the hard cross-linked polymer obtained in step 2 forms yellowish transparent material with lower density that its previous stages, this coincides with loss of more water and material having high porosity, at this stage neighboring carbon chains merge and start forming to 3D-carbon matrixes;
- 4. on heating to from 225 C to 500 C, the material obtained in the preceding step becomes free of water and yet contains appreciable amounts of hydrogen, this step is know as pre-carbonization carbonization step which was critical in controlling the porosity of the host material. Slower heating leads to smaller pore sizes;
= - 5. on heating to 1000-1250 C, material volume shrinks, its electrical conductivity increases by many orders of magnitudes;
- 6. at temperatures above 1200 C, the material being depleted of hydrogen;
and - 7. further cross-linking and carbon chains start growing in 2D & 3D
directions, this means that carbon#1 sticks on the surface of the carbon#2 particles and carbon#1 squeezes into itself when the temperature is increased to 2500 C.
In the following examples, the PF material used was supplied in the year 2001 by Georgia Pacific Co., Lawrenceville, GA, in the United States of America under the reference Products # PF211.
= - 5. on heating to 1000-1250 C, material volume shrinks, its electrical conductivity increases by many orders of magnitudes;
- 6. at temperatures above 1200 C, the material being depleted of hydrogen;
and - 7. further cross-linking and carbon chains start growing in 2D & 3D
directions, this means that carbon#1 sticks on the surface of the carbon#2 particles and carbon#1 squeezes into itself when the temperature is increased to 2500 C.
In the following examples, the PF material used was supplied in the year 2001 by Georgia Pacific Co., Lawrenceville, GA, in the United States of America under the reference Products # PF211.
5 Here, we are proposing the application of a new Carbon#1-Carbon#2 composite as N-E material for battery systems consisted of winded/stacked layers of electrodes with potential differences between them being dependant on their electrochemical properties. The other disclosing element of this proposal is the processing of the carbon-carbon composites noted above. The proposed material consists of carbon-carbon composite of 10-100 pm particles.
This consisted of a highly graphitic carbon (e.g. graphite) embedded within or surrounded by the matrix of a second carbon that has a low degree of graphitization (known as hard carbons).
The low cristallinity carbon constituting of Carbon#1 has a sloppy voltage and a high medium voltage about 500 mV vs Li/Li. This high sloppy voltage will be affected on the decreasing of the energy density of the batteries. However this is compatible with PC based electrolyte. This type of electrolyte is suitable for low temperature applications.
The high cristallinity carbon constituting of Carbon#2 has a flat voltage and low medium voltage about 100 mV vs Li+/Li. This low flat voltage will be affected on the increasing of the energy density of the batteries. However it is not compatible with PC based electrolyte.
EXAMPLES
The following examples are given for illustritative purpose only and may not be construted as constituing a limitation of the present invention.
Sample preparation:
The following steps were used to prepare the proposed material:
1- a Carbon#2 powder was dispersed in Liquid Phenolic Resin (PF) and the mixed using mixture ball milling. The mixing process was continued until complete dispersion of Carbon#2 in the PF and vaporization of 40 - 60 wt% of the containing alcohol from PF, both were assured.
2- the item-1 mixture was pored on flat Al-plate, then heated to 150-175 C
and thermally soaked for 2.0 hours. The heating rate could vary from 3-8 C/min depending on the thickness of the sample, in our case heating of 5 C/min was used. After this heating process, the sample converts into solid sheets from which the AL-plate was separated.
3- item-3 (Carbon#2: polymerized PF-matrix) heat treated to 600 C and then to 1000 or 2500 C using 30-50 C/min heating rate following thermal profile shown in Figure 1.
The PF matrix polymerizes and pre-carbonizes up to 450-475 C. During this step, PF generates water, which vaporizes while heating. This leads to increasing density and decreasing volume. Between 500-600 PF begins the early stages of carbonization steps, where the carbon graphite-sheets start buckling-up and building three-dimensional matrixes of randomly oriented short carbon layers with porous structure. PF porosity could depend on heat rate and thermal-soaking time in this temperature range. For longer heating time between 475-600 C, the PF
pores size to become smaller. Above 600 C, the graphitization step starts and the graphite layer cross-link further. This process tends to squeeze the carbon#2 particles closer together and provides carbon-carbon composites with the low graphitized carbon matrix pressing over the highly graphitized carbon particles.
Figure 3 shows Transmission Electron Micrograph of the carbon-carbon composite heat treated to 2.500 C and as prepared according to samples 3 and 4.
14 =
The following Table 1 lists the data of carbon-carbon composite samples prepared = for proof of the concept.
Skeletal Pore Area Ave.Bulk Density Density No. Sample Description1g) Dia. Qt) (g/cm3) (gicm3) _ 100g PF
1 50g-SPG-44 9.184 0.02 0.482 0.584 1.267 100g PF
2 40g-SPG-44/5%LiNO3 13.198 1 0.243 0.605 1.162 100g PF
3 70g-SPG-44 3.198 0.05 0.123 0.988 1.095 100g PF
4 70g-SPG-15 6.550 0.12 0.437 0.532 1.413 TABLE I
Carbon#1 is a carbon derived by heat treatment from 1.000 to 2.500 Celcius (preferably at 1.000 degrees Celcius) from phenolic resin.
Carbon#2 is an artificial graphite ¨ commercialized under the name SFG 44 (particles having a size of 44 micrometers) and under the name SFG 15 (particles having a size of 15 micrometers by the Company Timcal (anciently Lonzain Swiss).
Example 1 In this example the carbon-carbon composite was made by mixing 100g PF with 50g of SF0-44 (artificial graphite) commercialized by iiincal (Swiss) and heated at 1.000 C for 2 hours in argon atmosphere. The SEM image of the carbon-carbon material of the sample 1 is shown in Figure 1. The carbon#1 is derived from carbonization of PF, which cover partially the surface of carbon#2(graphite).
The electrochemical performance was obtained by using 1M LiC104 in EC-DMC
as electrolyte. Three electrodes cell was used with lithium metal as counter 5 electrode and reference. The reversible capacity of sample #1 is 218mAh/g at C/12 rate (charge and discharge in 12hours). The coulombic efficiency of the first cycle was 85%.
Example 2 In this example the carbon-carbon composite was made by mixing 100g PF with 40g-SFG-44/5%LiNO3 and heated at 1000 C for 2 hours in argon atmosphere. The SEM image of the carbon-carbon material of the sample 2 is shown in Figure 2.
The carbon# I is derived from carbonization of PF, which cover almost totally of the surface of carbon#2 (graphite). The particle size of carbon#1 is from 39 rim to 500nm. The electrochemical performance was obtained by using 1M LiC104 in EC-DMC as electrolyte. Three electrodes cell was used with lithium metal as counter electrode and reference. The reversible capacity of sample #2 is 259 mAh/g at C/12 rate (charge and discharge in 12h). The coulombic efficiency of the first cycle was 82%.
Example 3 In this example the carbon-carbon composite was made by mixing 100g PF with 70g-SFG-15 and heated at 2500 C for 1 minute in argon atmosphere. The SEM
image of the carbon-carbon material of the sample 3 is shown in figure 3. The carbon#1 is derived from carbonization of PF, which cover partially the surface of carbon#2 (graphite), but still some graphite particle not covered at all.
The particle size of carbon#1 is from 20nm to 500nm.
The electrochemical performance was obtained by using 1M LiC104 in EC-DMC
as electrolyte. Three electrodes cell was used with lithium metal as counter = 16 electrode and reference. The reversible capacity of sample #3 is 235mAh/g at C/12 rate (charge and discharge in 12h). The coulombic efficiency of the first cycle was 45%.
Example 4 In this example the carbon-carbon composite was made by mixing 100g PF with 70g-SFG-15 and heated at 2500 C for 2 hours in argon atmosphere. The SEM
image of the carbon-carbon material of the sample 3 is shown in Figure 4. The to carbon#1 is derived from carbonization of PF, which covers almost totally the surface of carbon#2(graphite). The carbon#lis more compact, it's particle size is from 20nm to 500nm.
The electrochemical performance was obtained by using 1M LiC104 in EC-DMC as electrolyte. A three electrodes cell was used with lithium metal as counter electrode and reference. The reversible capacity of sample #4 is 280mAh/g at C/12 rate (charge and discharge in 12h). The coulombic efficiency of the first cycle was 56%.
Among the improved properties of the new carbon-carbon material of the present invention over the known materials and particularly over the known NE
materials are inter alia:
- the compatibility with propylene carbonate (PC);
- the low volume expansion;
- the high electrode density; and - the low reactivity (safety).
, It is to be understood that the scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.
This consisted of a highly graphitic carbon (e.g. graphite) embedded within or surrounded by the matrix of a second carbon that has a low degree of graphitization (known as hard carbons).
The low cristallinity carbon constituting of Carbon#1 has a sloppy voltage and a high medium voltage about 500 mV vs Li/Li. This high sloppy voltage will be affected on the decreasing of the energy density of the batteries. However this is compatible with PC based electrolyte. This type of electrolyte is suitable for low temperature applications.
The high cristallinity carbon constituting of Carbon#2 has a flat voltage and low medium voltage about 100 mV vs Li+/Li. This low flat voltage will be affected on the increasing of the energy density of the batteries. However it is not compatible with PC based electrolyte.
EXAMPLES
The following examples are given for illustritative purpose only and may not be construted as constituing a limitation of the present invention.
Sample preparation:
The following steps were used to prepare the proposed material:
1- a Carbon#2 powder was dispersed in Liquid Phenolic Resin (PF) and the mixed using mixture ball milling. The mixing process was continued until complete dispersion of Carbon#2 in the PF and vaporization of 40 - 60 wt% of the containing alcohol from PF, both were assured.
2- the item-1 mixture was pored on flat Al-plate, then heated to 150-175 C
and thermally soaked for 2.0 hours. The heating rate could vary from 3-8 C/min depending on the thickness of the sample, in our case heating of 5 C/min was used. After this heating process, the sample converts into solid sheets from which the AL-plate was separated.
3- item-3 (Carbon#2: polymerized PF-matrix) heat treated to 600 C and then to 1000 or 2500 C using 30-50 C/min heating rate following thermal profile shown in Figure 1.
The PF matrix polymerizes and pre-carbonizes up to 450-475 C. During this step, PF generates water, which vaporizes while heating. This leads to increasing density and decreasing volume. Between 500-600 PF begins the early stages of carbonization steps, where the carbon graphite-sheets start buckling-up and building three-dimensional matrixes of randomly oriented short carbon layers with porous structure. PF porosity could depend on heat rate and thermal-soaking time in this temperature range. For longer heating time between 475-600 C, the PF
pores size to become smaller. Above 600 C, the graphitization step starts and the graphite layer cross-link further. This process tends to squeeze the carbon#2 particles closer together and provides carbon-carbon composites with the low graphitized carbon matrix pressing over the highly graphitized carbon particles.
Figure 3 shows Transmission Electron Micrograph of the carbon-carbon composite heat treated to 2.500 C and as prepared according to samples 3 and 4.
14 =
The following Table 1 lists the data of carbon-carbon composite samples prepared = for proof of the concept.
Skeletal Pore Area Ave.Bulk Density Density No. Sample Description1g) Dia. Qt) (g/cm3) (gicm3) _ 100g PF
1 50g-SPG-44 9.184 0.02 0.482 0.584 1.267 100g PF
2 40g-SPG-44/5%LiNO3 13.198 1 0.243 0.605 1.162 100g PF
3 70g-SPG-44 3.198 0.05 0.123 0.988 1.095 100g PF
4 70g-SPG-15 6.550 0.12 0.437 0.532 1.413 TABLE I
Carbon#1 is a carbon derived by heat treatment from 1.000 to 2.500 Celcius (preferably at 1.000 degrees Celcius) from phenolic resin.
Carbon#2 is an artificial graphite ¨ commercialized under the name SFG 44 (particles having a size of 44 micrometers) and under the name SFG 15 (particles having a size of 15 micrometers by the Company Timcal (anciently Lonzain Swiss).
Example 1 In this example the carbon-carbon composite was made by mixing 100g PF with 50g of SF0-44 (artificial graphite) commercialized by iiincal (Swiss) and heated at 1.000 C for 2 hours in argon atmosphere. The SEM image of the carbon-carbon material of the sample 1 is shown in Figure 1. The carbon#1 is derived from carbonization of PF, which cover partially the surface of carbon#2(graphite).
The electrochemical performance was obtained by using 1M LiC104 in EC-DMC
as electrolyte. Three electrodes cell was used with lithium metal as counter 5 electrode and reference. The reversible capacity of sample #1 is 218mAh/g at C/12 rate (charge and discharge in 12hours). The coulombic efficiency of the first cycle was 85%.
Example 2 In this example the carbon-carbon composite was made by mixing 100g PF with 40g-SFG-44/5%LiNO3 and heated at 1000 C for 2 hours in argon atmosphere. The SEM image of the carbon-carbon material of the sample 2 is shown in Figure 2.
The carbon# I is derived from carbonization of PF, which cover almost totally of the surface of carbon#2 (graphite). The particle size of carbon#1 is from 39 rim to 500nm. The electrochemical performance was obtained by using 1M LiC104 in EC-DMC as electrolyte. Three electrodes cell was used with lithium metal as counter electrode and reference. The reversible capacity of sample #2 is 259 mAh/g at C/12 rate (charge and discharge in 12h). The coulombic efficiency of the first cycle was 82%.
Example 3 In this example the carbon-carbon composite was made by mixing 100g PF with 70g-SFG-15 and heated at 2500 C for 1 minute in argon atmosphere. The SEM
image of the carbon-carbon material of the sample 3 is shown in figure 3. The carbon#1 is derived from carbonization of PF, which cover partially the surface of carbon#2 (graphite), but still some graphite particle not covered at all.
The particle size of carbon#1 is from 20nm to 500nm.
The electrochemical performance was obtained by using 1M LiC104 in EC-DMC
as electrolyte. Three electrodes cell was used with lithium metal as counter = 16 electrode and reference. The reversible capacity of sample #3 is 235mAh/g at C/12 rate (charge and discharge in 12h). The coulombic efficiency of the first cycle was 45%.
Example 4 In this example the carbon-carbon composite was made by mixing 100g PF with 70g-SFG-15 and heated at 2500 C for 2 hours in argon atmosphere. The SEM
image of the carbon-carbon material of the sample 3 is shown in Figure 4. The to carbon#1 is derived from carbonization of PF, which covers almost totally the surface of carbon#2(graphite). The carbon#lis more compact, it's particle size is from 20nm to 500nm.
The electrochemical performance was obtained by using 1M LiC104 in EC-DMC as electrolyte. A three electrodes cell was used with lithium metal as counter electrode and reference. The reversible capacity of sample #4 is 280mAh/g at C/12 rate (charge and discharge in 12h). The coulombic efficiency of the first cycle was 56%.
Among the improved properties of the new carbon-carbon material of the present invention over the known materials and particularly over the known NE
materials are inter alia:
- the compatibility with propylene carbonate (PC);
- the low volume expansion;
- the high electrode density; and - the low reactivity (safety).
, It is to be understood that the scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.
Claims (7)
1. A process for preparing a composite of particles of a high crystallinity carbon and a low crystallinity carbon, wherein:
the low crystallinity carbon exhibits an average lattice constant d=(002) of 0.350 nm or more and a crystallite size L=(002) in the direction of C axis of 25 nm or less, as characterized by wide-angle X-ray diffraction measurements;
the high crystallinity carbon exhibits an average lattice constant d=(002) of 0.338 nm or less and a crystallinity size L=(002) in the direction of C axis of 40 nm or more, as characterized by wide-angle X-ray diffraction measurements; and the high crystallinity carbon forms particles having a particle size ranging from 1 to 50 micrometers, the high crystallinity carbon particles being at least partially covered by particles of the low crystallinity carbon having a particle size ranging from 10 to 500 nm, the low crystallinity carbon particles being attached to the surface of the high crystallinity carbon particles;
said process comprising the steps of:
(i) dispersing a carbon powder having a high crystallinity and a polymeric substance in a solvent and mixing until evaporation of 40 to 60% of the solvent; and (ii) heating the resulting mixture at a temperature ranging from 1200°C
to 2500°C.
the low crystallinity carbon exhibits an average lattice constant d=(002) of 0.350 nm or more and a crystallite size L=(002) in the direction of C axis of 25 nm or less, as characterized by wide-angle X-ray diffraction measurements;
the high crystallinity carbon exhibits an average lattice constant d=(002) of 0.338 nm or less and a crystallinity size L=(002) in the direction of C axis of 40 nm or more, as characterized by wide-angle X-ray diffraction measurements; and the high crystallinity carbon forms particles having a particle size ranging from 1 to 50 micrometers, the high crystallinity carbon particles being at least partially covered by particles of the low crystallinity carbon having a particle size ranging from 10 to 500 nm, the low crystallinity carbon particles being attached to the surface of the high crystallinity carbon particles;
said process comprising the steps of:
(i) dispersing a carbon powder having a high crystallinity and a polymeric substance in a solvent and mixing until evaporation of 40 to 60% of the solvent; and (ii) heating the resulting mixture at a temperature ranging from 1200°C
to 2500°C.
2. The process according to claim 1, wherein the high crystallinity carbon is graphite, kish graphite, pyrolytic graphite, gas-growth graphite or artificial graphite.
3. The process according to claim 1 or 2, wherein the polymeric substance is a liquid Phenolic Resin (PF).
4. The process according to any one of claims 1 to 3, wherein the solvent is water.
5. The process according to any one of claims 1 to 3, wherein the solvent is an organic solvent.
6. The process according to claim 5, wherein the organic solvent is an alcohol.
7. A process for preparing a negative electrode wherein:
- a high crystallinity carbon is dispersed in a liquid Phenolic Resin (PF) dissolved in alcohol and mixed using ball milling until complete dispersion of the high crystallinity carbon in the PF and vaporization of 40 to 60 wt % of the alcohol;
- the mixture obtained is poured on a flat Al-plate, then heated to 150°C to 175°C and thermally soaked for 2.0 hours, with a heating rate which varies from 3°C to 8°C/min;
- the solid sheet obtained is removed from the Al-plate and submitted to a heat treatment comprising the steps of:
i) heating to 600°C and maintaining at 600°C for 2 hours, ii) heating to 1000°C at a heating rate of 20°C to 30°C/min and maintaining at 1000°C for 2 hours, and iii) heating at 2500°C at a heating rate of 100°C/min and maintaining at 2500°C for 1 min.
- a high crystallinity carbon is dispersed in a liquid Phenolic Resin (PF) dissolved in alcohol and mixed using ball milling until complete dispersion of the high crystallinity carbon in the PF and vaporization of 40 to 60 wt % of the alcohol;
- the mixture obtained is poured on a flat Al-plate, then heated to 150°C to 175°C and thermally soaked for 2.0 hours, with a heating rate which varies from 3°C to 8°C/min;
- the solid sheet obtained is removed from the Al-plate and submitted to a heat treatment comprising the steps of:
i) heating to 600°C and maintaining at 600°C for 2 hours, ii) heating to 1000°C at a heating rate of 20°C to 30°C/min and maintaining at 1000°C for 2 hours, and iii) heating at 2500°C at a heating rate of 100°C/min and maintaining at 2500°C for 1 min.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2469407A CA2469407C (en) | 2001-12-07 | 2002-12-06 | Carbon-carbon composite particles, their preparation and use therefore as negative electrode for li-ion batteries |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002364651A CA2364651A1 (en) | 2001-12-07 | 2001-12-07 | Carbon-carbon composite as negative electrode for li-ion batteries |
| CA2,364,651 | 2001-12-07 | ||
| CA2469407A CA2469407C (en) | 2001-12-07 | 2002-12-06 | Carbon-carbon composite particles, their preparation and use therefore as negative electrode for li-ion batteries |
| PCT/CA2002/001888 WO2003049215A2 (en) | 2001-12-07 | 2002-12-06 | Carbon-carbon composite particles, their preparation and use therefore as negative electrode for li-ion batteries |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2469407A1 CA2469407A1 (en) | 2003-06-12 |
| CA2469407C true CA2469407C (en) | 2014-05-27 |
Family
ID=32851581
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2469407A Expired - Lifetime CA2469407C (en) | 2001-12-07 | 2002-12-06 | Carbon-carbon composite particles, their preparation and use therefore as negative electrode for li-ion batteries |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2469407C (en) |
-
2002
- 2002-12-06 CA CA2469407A patent/CA2469407C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2469407A1 (en) | 2003-06-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Bao et al. | 3D metal carbide@ mesoporous carbon hybrid architecture as a new polysulfide reservoir for lithium‐sulfur batteries | |
| JP4137350B2 (en) | Negative electrode material for lithium secondary battery, electrode for lithium secondary battery, lithium secondary battery, and method for producing negative electrode material for lithium secondary battery | |
| KR101126425B1 (en) | Negative electrode material for lithium ion secondary battery, method for production thereof, negative electrode for lithium ion secondary battery, and lithium ion secondary battery | |
| JP5543533B2 (en) | Anode material for lithium ion secondary battery | |
| JP6279713B2 (en) | Carbonaceous molded body for electrode and method for producing the same | |
| WO2007072858A1 (en) | Composite graphite particles and lithium rechargeable battery using the same | |
| JP6939979B2 (en) | Silicon nanoparticles and non-aqueous secondary batteries using them Active materials for negative electrodes and secondary batteries | |
| CN101990719A (en) | Composite electrode material | |
| Wei et al. | Recycling of waste plastics and scalable preparation of Si/CNF/C composite as anode material for lithium-ion batteries | |
| JP6297746B2 (en) | Carbonaceous molded body for battery electrode and method for producing the same | |
| JP2020126771A (en) | Negative electrode layer and all-solid battery | |
| JP2007141677A (en) | Compound graphite and lithium secondary cell using same | |
| US20240120482A1 (en) | Negative electrode material for lithium-ion secondary battery, method of evaluating same, and method of producing same, negative electrode for lithium-ion secondary battery, and lithium-ion secondary battery | |
| JPWO2019009422A1 (en) | Method for producing negative electrode material for lithium ion secondary battery, and negative electrode material for lithium ion secondary battery | |
| EP1516379B1 (en) | Carbon-carbon composite particles, their preparation and use thereof as negative electrode for li-ion batteries | |
| CA2469407C (en) | Carbon-carbon composite particles, their preparation and use therefore as negative electrode for li-ion batteries | |
| Prosini et al. | A high-voltage lithium-ion battery prepared using a Sn-decorated reduced graphene oxide anode and a LiNi 0.5 Mn 1.5 O 4 cathode | |
| WO2017110796A1 (en) | Carbon material for secondary battery negative electrodes, active material for secondary battery negative electrodes, secondary battery negative electrode and secondary battery | |
| KR20230117194A (en) | Negative electrode material for lithium ion secondary battery and its manufacturing method, negative electrode for lithium ion secondary battery, and lithium ion secondary battery | |
| Yang et al. | A porous Li4SiO4 ceramic separator for lithium-ion batteries | |
| JP2019036378A (en) | Carbon material for secondary battery negative electrode, active material for secondary battery negative electrode, secondary battery negative electrode, and secondary battery | |
| CN111509202A (en) | Composite cathode material and preparation method and application thereof | |
| JP2017183233A (en) | Carbon material for secondary battery negative electrode, active material for secondary battery negative electrode, secondary battery negative electrode, and secondary battery |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |
Effective date: 20221206 |