CN100463257C - Anode active material, method of preparing the same, and anode and lithium battery employing the same - Google Patents
Anode active material, method of preparing the same, and anode and lithium battery employing the same Download PDFInfo
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- CN100463257C CN100463257C CNB200610006053XA CN200610006053A CN100463257C CN 100463257 C CN100463257 C CN 100463257C CN B200610006053X A CNB200610006053X A CN B200610006053XA CN 200610006053 A CN200610006053 A CN 200610006053A CN 100463257 C CN100463257 C CN 100463257C
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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
- H01M4/366—Composites as layered products
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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
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
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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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- 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
- H01M4/626—Metals
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/40—Electric properties
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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
- 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
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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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/134—Electrodes based on metals, Si or alloys
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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
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/386—Silicon or alloys based on silicon
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
An anode active material including a metal core and a coating layer formed on a surface of the metal core is provided. The coating layer includes a conductive metal material. The coating layer covering the metal core is carbon-based and includes a conductive metal material. The anode active material has good electron conductivity and elasticity, thereby enhancing charge/discharge capacity and reducing the stress caused by expansion of the carbon-based coating layer and the metal core during charge/discharge cycles. Direct contact between the metal core and the electrolyte solution is remarkably reduced. In addition, anodes and lithium batteries including the anode active material exhibit excellent charge/discharge characteristics, such as discharge capacity and initial charge/discharge efficiency.
Description
Technical field
The present invention relates to anode active material and preparation method thereof, and the anode and the lithium battery that adopt it.More specifically, the present invention relates to anode active material that has excellent initial charge/discharge efficient and discharge capacity and preparation method thereof, and the anode and the lithium battery that adopt it.
Background technology
Adopt lithium compound to have high voltage and high-energy-density, thereby it has been carried out a lot of researchs as the nonaqueous electrolytic solution secondary battery of anode material.Particularly, main research is to have jumbo lithium metal in early days, and in this period, people are more interested to be that lithium is used as anode material.Yet, when using lithium anodes, on the lithium surface too much Li dendrite can appear between charge period.Therefore, charge/discharge efficient can reduce, and also can cause the short circuit between anode and the negative electrode.In addition, the shortcoming that lithium anodes involved is the unsteadiness of lithium, i.e. the high response of lithium.
On the other hand, if the anode that uses carbonaceous material to make though compare with the anode that lithium or lithium alloy are made, can reduce expansion and contraction during the charge.Yet, can occur such as the Capacity Ratio lithium reduce (about 350mAh/g) and initially charge/discharge efficient than the problem of lithium reduction.
Thereby although metal anode has the problems referred to above, the anode of still attempting energetically utilizing metal such as lithium to make strengthens the capacity of battery.
Know that lithium metal and lithium alloy such as lithium-aluminium, lithium-lead, lithium-Xi and lithium-silicon etc. can provide the capacitance (2000mAh/g or bigger) bigger than carbonaceous material.Yet, when independent use lithium metal or lithium alloy, can cause the formation of Li dendrite and change in volume rapidly.Thereby, studied appropriate combination with lithium metal or lithium alloy and carbonaceous material as anode material, with the increase capacitance and prevent anode and negative electrode between short circuit.
Proposed much to adopt the routine techniques of this composite material as anode material.
Japanese patent unexamined discloses and discloses for 1993-286763 number by similar carbonaceous material and the metal material of assorted size, and this mixture is coated with organic compound, then carries out sintering and the anode material that obtains.Here, described metal material is used to compensate the low-voltage capacity of carbonaceous material.This anode material has the good charge/discharge efficient and the charge/discharge capacity of relative enhancing.
Japanese patent unexamined discloses 1998-003920 number and discloses the anode that comprises metallic particles and coat the carbonaceous material of surface of metal particles.Here, metallic particles is used to strengthen charge/discharge capacity, and carbonaceous material is used for reducing the change in volume of metallic particles in charge.The metallic particles that scribbles carbonaceous material has the discharge capacity and the initial charge/discharge efficient of enhancing.
Japanese patent unexamined discloses the anode that discloses the surperficial coated with conductive material that contains lithium composite nitride composition granule for 2001-015101 number.Here, in order to strengthen the conductivity that contains lithium composite nitride composition granule, this is contained lithium composite nitride composition granule be coated with electric conducting material rather than mixing with it.Therefore, high speed characteristics and cycle characteristics are enhanced.
Japanese patent unexamined discloses the metal electrode that discloses with the electrically conductive particles coating 2002-516643 number.Here, in order to reduce the resistance between metal electrode and the electrolyte, this electrically conductive particles is not to coat on the electrode active material but be present on the metal electrode.
The basis of above-mentioned routine techniques is with coated metal powder surfaces such as carbon granules, with formation (being the shortcoming of metallic particles) and the low charge/discharge capacity (being the shortcoming of carbonaceous material) of enhancing that prevents Li dendrite.
Yet these routine techniquess are because carbonaceous material low-voltage capacity and conductivity and being restricted aspect the enhancing of initial charge/discharge efficient and discharge capacity in essence.
Therefore, because carbonaceous material is above-mentioned restricted, still need to develop more practical anode active material with good initial charge/discharge efficient and high discharge capacity.
Summary of the invention
The invention provides a kind of the have initial charge/discharge efficient of enhancing and the anode active material of discharge capacity.
The present invention also provides anode and the lithium battery that comprises this anode active material.
The present invention also provides a kind of method for preparing this anode active material.
According to an aspect of the present invention, provide a kind of anode active material, it comprises: metal-cored; And coating, this coating is formed on the metal-cored surface and comprises conductive metallic material.
The conductive metallic material of coating may reside on the metal-cored surface.
Conductive metallic material also can be included in metal-cored in.
By the total weight of anode active material, the content of conductive metallic material is 0.1～20 weight %.
Conductive metallic material can have 5.5 * 10
-8Ω m or littler resistivity and 200GPa or littler coefficient of elasticity.
Conductive metallic material can have 1.4 * 10
-8Ω m～5.5 * 10
-8The resistivity of Ω m and the coefficient of elasticity of 40～200GPa.
According to a further aspect in the invention, provide anode that comprises this anode active material and the lithium battery that adopts this anode.
According to another aspect of the invention, provide a kind of method for preparing anode active material, this method comprises: be added to polymeric material and conductive metallic material in the solvent and stir this reaction solution; Metallic particles is added in this reaction solution, then stirs and drying; And sintering dry product to form coating.
Description of drawings
By the reference accompanying drawing in detail its exemplary is described in detail, above-mentioned and other feature and advantage of the present invention will be more readily apparent from, in the accompanying drawings:
Fig. 1 is the charge/discharge curve of charge/discharge characteristics of the lithium battery of the diagram anode active material that adopts the embodiment of the invention 1 and Comparative Examples 1 and 2;
Fig. 2 A is transmission electron microscopy (TEM) image of the anode active material of Comparative Examples 3, and Fig. 2 B is the TEM image of the anode active material of the embodiment of the invention 9; And
Fig. 3 is the schematic diagram of anode active material according to embodiments of the present invention.
Embodiment
Now illustrate in greater detail the present invention.
Anode active material according to the present invention comprises the coating that contains conductive metallic material.Conventional anode active material comprises the metal-cored of the carbonaceous material that only scribbles low-voltage capacity and conductance, thereby is being restricted aspect initial charge/discharge efficient and the discharge capacity.This is opposite with anode active material of the present invention, in anode active material of the present invention, also comprises conductive metallic material in the coating extraly, thereby initial charge/discharge efficient and discharge capacity are enhanced.
Anode active material of the present invention comprises and is formed at the coating on metal-cored surface that this coating comprises conductive metallic material metal-cored.
Metal-cored can be by the metal that can embed and deviate from lithium, the metal that promptly can form lithium alloy is made.For example, can use silicon, aluminium, lead, tin, germanium etc.In order under high potential, to carry out sufficient charge, preferably use silicon, silicon alloy or silicon/graphite composite, it can carry out reversible redox reaction with lithium in the charge process, and has the charge/discharge electromotive force that is similar to graphite granule.
Silicon alloy can be silicon be selected from following at least a combination: nickel, copper, cobalt, manganese, magnesium, aluminium, molybdenum, lead, tin, zinc, and titanium.
Silicon/graphite composite can be to grind at least a compound that obtains in silicon and graphite flake, graphite fibre and the fine graphite powders by high energy mechanical.
The effect that comprises the coating of conductive metallic material is to strengthen metal-cored capacitance extraly.Coating is present in metal-cored surface at least in part.More specifically, the coating of anode active material of the present invention can be coated on the metal core particles.Thus, inner anode active material and electrolyte solution are isolated.
Coating can have sandwich construction.For example, when coating was made by carbon, carbon coating can be filmed by a plurality of rather than single carbon and be constituted.
In anode active material of the present invention, metal-cored can taking various forms is as the single metallic particles or the aggregation of metallic particles.The preferable alloy core is the form of single metal particle.Yet, because the phenomenon that two or more metallic particles are assembled can take place during anode active material in preparation, so the metal-cored form that also can be particle aggregate etc.
For example, anode active material can so prepare, and promptly comprises the carbon coating of conductive metallic material in metal-cored surface coated, and this is metal-cored to be made of a plurality of metallic particles, and has conductive metallic material between each metallic particles.
In this anode active material, the conductive metallic material that coating comprised can mainly be present on the surface of metal core particles.Yet except the surface of metal core particles, conductive metallic material also can be present in coating inside widely.Preferred conductive metallic material is dense and mainly be present on the surface of metal core particles.Thus, the anode material that is made of graphite granule and conductive metallic material can have higher capacitance (electric capacity).Conductive metallic material can also be present among the metal core particles extraly.
Most preferably coating is formed uniformly on the whole surface of metal core particles.Yet although coating has thickness deviation or partly is formed on the surface of metal core particles, advantage of the present invention still can realize.
The metal-cored average grain diameter that constitutes anode active material there is not concrete restriction.Yet conductive metallic material can have the average grain diameter of 0.01～1 μ m.If the average grain diameter of conductive metallic material is less than 0.01 μ m, then this material can not suitably be handled in processing.On the other hand, if described average grain diameter surpasses 1 μ m, then be difficult to suitably disperse this conductive metallic material in anode active material.
By the total weight of anode active material, the content of conductive metallic material can be 0.1～20wt%.If the content of conductive metallic material is less than 0.1wt%, then the effect of aspect such as capacity may be insufficient.On the other hand, if this content surpasses 20wt%, then the capacity of the anode active material of per unit weight can reduce.
In the present invention, metal-coredly embed and deviate from and stand big change in volume in the process at lithium.Thereby, require described conductive metallic material to have low coefficient of elasticity, so that when change in volume takes place, do not break away from metal-coredly, and stand metal-cored change in volume.This conductive metallic material also should have the favorable conductive rate, to keep the electrical connection between the particle and to strengthen battery performance.In order to satisfy all these requirements, conductive metallic material can be that resistivity is 5.5 * 10
-8Ω or littler and coefficient of elasticity are 200GPa or littler metal or its alloy.This conductive metallic material can also be that resistivity is 1.4 * 10
-8Ω m to 5.5 * 10
-8Ω m and coefficient of elasticity are metal or its alloy of 40GPa to 200GPa.
The conductive metallic material that satisfies above-mentioned requirements can be to be selected from least a in following: Cu, Ag, Al, Mg, Zn, and alloy.Yet, should be appreciated that also and can use other metal.
In anode active material of the present invention, the coating that covers conductive metallic material can be the carbon-coating of being made by the sintered product of polymeric material.This polymeric material can be to be selected from least a in following: vinylite, celluosic resin, phenol resin, asphaltic resin, and tar resin.More preferably polyvinyl alcohol.
The carbon-coating that covers conductive metallic material can have
Or bigger interplanar distance (d
002) or amorphous carbon.The carbon-coating that covers conductive metallic material also can have
Extremely
Interplanar distance (d
002) or amorphous carbon.
If carbon-coating is a highly crystalline, its effect is equivalent to graphite.Therefore, the electrolyte solution reaction that this carbon-coating can be surperficial with it.Low crystallization or unbodied carbon-coating do not react with electrolyte solution in the charge process.Therefore, can prevent that electrolyte solution from decomposing, and then guarantee high charge/discharge efficient.
Carbon-coating can be of compact construction, so that contacting between metal core particles and the electrolyte solution do not taken place.Thus, can avoid reacting between electrolyte solution and the metal core particles/silicon grain.In other words, carbon-coating can serve as anti-conversion zone, to stop the reaction between electrolyte solution and anode material such as the graphite granule.
The present invention also provides the anode that utilizes above-mentioned anode active material preparation.
For example, can be by preparing anode by the anode mixture that anode active material and binding agent constitute with predetermined shape molding.Anode also can prepare on collector body (as Copper Foil) by the described anode mixture of coating.
More specifically, prepare the anode material composition earlier.This anode material composition can directly be coated on collector body such as the Copper Foil, also can curtain coating (cast) on independent carrier.For the latter, will be combined on collector body such as the Copper Foil from the anode active material rete that carrier is peeled off, obtain positive plate thus.The method for preparing anode of the present invention is not limited to above-mentioned embodiment.
Battery needs the charge/discharge of big electric current, to guarantee high power capacity.For this reason, need battery electrode to have low resistance.Thereby, in order to reduce the resistance of electrode, generally can add various electric conducting materials.Main carbon black, the graphite particulates etc. of using are as electric conducting material.
The present invention also provides the lithium battery that comprises described anode.Lithium battery of the present invention can be prepared as follows.
At first, mix cathode active material, electric conducting material, binding agent and solvent, make the cathode active material composition.Directly be coated on the metal current collector this cathode active material composition and drying, make minus plate.As selection, can be on independent carrier with cathode active material composition curtain coating.Then, the frlml laminating that will peel off from carrier makes minus plate on metal current collector.
Cathode active material can be any lithium metal oxide that contains as known in the art.For example, can use LiCoO
2, LiMn
xO
2x, LiNi
1-xMn
xO
2x(x=1,2), Ni
1-x-yCo
xMn
yO
2(0≤x≤0.5,0≤y≤0.5) etc.More specifically, can use the oxidation that can cause lithium and the compound such as the LiMn of reduction reaction
2O
4, LiCoO
2, LiNiO
2, LiFeO
2, V
2O
5, TiS and MoS.
Electric conducting material can be carbon black.Binding agent can be vinylidene fluoride/hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene or its mixture, also can be styrene butadiene rubber polymeric.Solvent can be N-methyl pyrrolidone, acetone, water etc.At this moment, the content of cathode active material, electric conducting material, binding agent and solvent is level commonly used in the lithium battery.
Can use known any dividing plate in the lithium battery field.More specifically, dividing plate can have lower resistance to the ion migration of electrolyte, and has the excellent electrolyte wettability.For example, dividing plate can be made by the material that is selected from glass fibre, polyester, teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE) and combination thereof, also can be made by non-woven fibre or textile fabric.More specifically, in lithium ion battery, can use the dividing plate of making by materials such as polyethylene or polypropylene that coils.On the other hand, in lithium ion polymer battery, can use organic electrolyte solution is had good infiltrating dividing plate.These dividing plates can be according to following method preparation.
That is to say,, make the dividing plate composition fluoropolymer resin, filler and solvent.Then, directly be coated on the electrode dividing plate composition and drying, form separator film.As selection, also can dividing plate composition curtain coating is also dry on carrier, will be combined on the electrode from the carrier ring that carrier is peeled off then.
Described fluoropolymer resin is not had special restriction, and it can be can be as any material of battery lead plate binding agent.For example, can use vinylidene fluoride/hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate or its mixture.
Can be used in electrolyte solution of the present invention can so prepare: with one or more lithium salts electrolyte such as LiPF
6, LiBF
4, LiSbF
6, LiAsF
6, LiClO
4, LiCF
3SO
3, Li (CF
3SO
2)
2N, LiC
4F
9SO
3, LiSbF
6, LiAlO
4, LiAlCl
4, LiN (C
xF
2x+1SO
2) (C
yF
2y+1SO
2) (x and y are natural number), LiCl and LiI, be dissolved in one or more and be selected from propylene carbonate, ethylene carbonate, diethyl carbonate, methyl ethyl carbonate, carbonic acid first propyl ester, butylene carbonate, benzonitrile, acetonitrile, oxolane, the 2-methyltetrahydrofuran, gamma-butyrolacton, dioxolanes, 4-methyl dioxolanes, N, dinethylformamide, dimethylacetylamide, methyl-sulfoxide, dioxane, 1, the 2-dimethoxy-ethane, sulfolane, dichloroethanes, chlorobenzene, nitrobenzene, dimethyl carbonate, the Methylethyl carbonic ester, diethyl carbonate, the methyl-propyl carbonic ester, the isopropyl methyl carbonic ester, the ethyl propyl carbonic ester, the dipropyl carbonic ester, the dibutyl carbonic ester, in the solvent of diethylene glycol and dimethyl ether.
Dividing plate is placed between minus plate and the positive plate, forms battery structure.In this battery structure coiling or folding and pack into cylindrical battery shell or rectangular cell shell, to wherein injecting organic electrolyte solution, make lithium ion battery thus then.
Also can stacked described battery structure, forming dual-battery structure, and flood with organic electrolyte solution.With resulting structures pack into the bag (pouch) in and the sealing, make lithium ion polymer battery thus.
The method of anode active material that the present invention also provides preparation to be used for lithium battery, this method comprise and are added to polymeric material and conductive metallic material in the solvent and stir this reaction solution; Metallic particles is added in this reaction solution, then stirs and drying; And sintering dry product, to form coating.
Prepare in the method for anode active material at this, described polymeric material can carry out sintering under 500～1250 ℃ temperature.Carbonization does not take place in this polymeric material under less than 500 ℃ sintering temperature.On the other hand, silicon may melt under greater than 1250 ℃ sintering temperature.
Described conductive metallic material can be the form of slaine.In this case, conductive metallic material exists in solution with ionic species, and is dispersed in ionic species in the surface or coating of metallic particles.When its counter ion evaporated during sintering or changes, the conductive metallic material of ionic species was transformed into metallic forms, and the conductive metallic material of this metallic forms appears in the anode active material.Therefore, this conductive metallic material can appear in the anode active material comparatively equably.
Described slaine can be SnCl
4, Ni (NO
3)
2, AgNO
3, Cu (NO
3)
2, Zn (NO
3)
2Deng, but be not limited to these.Can also use any compound that can be used for conductive metallic material of the present invention that comprises.
In preparing the method for anode active material, described polymeric material can be to be selected from least a in vinylite, celluosic resin, phenol resin, asphaltic resin and the tar resin.
The coating that forms by method of the present invention has good electrical conductivity, and can prevent contacting between graphite and/or silicon grain and the electrolyte solution.
Fig. 3 is the schematic diagram according to the anode active material of specific embodiments of the present invention.
Hereinafter, more specifically set forth the present invention with reference to the following examples.The following examples only are used to illustrate rather than to the restriction of scope of the present invention.
The preparation of anode active material
Embodiment 1
Silver nitrate (AgNO with 0.7g
3) and the 0.2g molecular weight be that 500 polyvinyl alcohol (PVA) is added in the distilled water of 10mL and stirs, till PVA dissolves fully.Then, to wherein adding the 3g average grain diameter, and with reactant mixture progressively heating under agitation, till water evaporates fully, obtain comprising the solid of the mixture that above-mentioned three components constitute thus less than 43 μ m Si powder.
With this solid in argon atmospher and 600 ℃ heating 12 hours down, so that the PVA carbonization.Then, in mortar, grind the product of carbonization, obtain wherein powder by the silicon grain of the carbon-coating coating that contains conductive metallic material.
Carry out with embodiment 1 in identical experiment, only be to use the silver nitrate of 0.5g.
Embodiment 3
Carry out with embodiment 1 in identical experiment, only be to use the silver nitrate of 0.3g.
Embodiment 4
Carry out with embodiment 1 in identical experiment, only be to use the silver nitrate of 1.4g.
Embodiment 5
Carry out with embodiment 1 in identical experiment, only be to use the butter of tin (SnCl of 1.1g
4) the replacement silver nitrate.
Embodiment 6
Carry out with embodiment 1 in identical experiment, only be to use the nickel nitrate (Ni (NO of 1.2g
3)
2) the replacement silver nitrate.
Embodiment 7
Carry out with embodiment 1 in identical experiment, only be to use the copper nitrate (Cu (NO of 0.8g
3)
2) the replacement silver nitrate.
Embodiment 8
Carry out with embodiment 1 in identical experiment, only be to use the zinc nitrate (Zn (NO of 1.2g
3)
2) the replacement silver nitrate.
Embodiment 9
The 1g primary average particle size is mixed in the mortar less than the Si powder of 50 μ m and the 2g average grain diameter powdered graphite less than 20 μ m less than 0.5 μ m and secondary average grain diameter, and mechanical lapping 1 hour, silicon/graphite composite powder obtained.Silver nitrate (AgNO with 0.2g
3) and the 1g molecular weight be that 500 PVA is added in the distilled water of 20mL and stirs, till PVA dissolves fully.Then,, and under agitation this reactant mixture progressively is heated to water and evaporates fully, obtain comprising the solid of the mixture that constitutes by above-mentioned three kinds of components thus to the silicon that wherein adds 1g/graphite composite powder.
With this solid argon atmospher and 900 ℃ down heating 3 hours with carbonization PVA.Then, in mortar, grind the product of carbonization, obtain wherein powder by the silicon/graphite composite particle of the carbon-coating coating that contains conductive metallic material.
Comparative Examples 1
Use the Si powder of average grain diameter less than 43 μ m.
Comparative Examples 2
With the 0.2g molecular weight is that 500 PVA is added in the distilled water of 10mL and stirs, till PVA dissolves fully.Then, to wherein adding the Si powder of 3g average grain diameter, and under agitation this reactant mixture progressively is heated to water and evaporates fully, obtain comprising the solid of the mixture that constitutes by above-mentioned two kinds of components thus less than 43 μ m.
With this solid argon atmospher and 600 ℃ down heating 12 hours with carbonization PVA.Then, in mortar, grind the product of carbonization, obtain powder with the silicon grain of carbon-coating coating.
Comparative Examples 3
The 1g primary average particle size is mixed in the mortar less than the Si powder of 50 μ m and the 2g average grain diameter powdered graphite less than 20 μ m less than 0.5 μ m and secondary average grain diameter, and mechanical lapping 1 hour, silicon/graphite composite powder obtained.
Comparative Examples 4
With the 0.1g molecular weight is that 500 PVA is added in the distilled water of 10mL and stirs, till PVA dissolves fully.Then,, under agitation this reactant mixture progressively is heated to water and evaporates fully, obtain comprising the solid of the mixture that constitutes by above-mentioned two kinds of components thus to the silicon that wherein adds 1g Comparative Examples 3/graphite composite powder.
With this solid argon atmospher and 900 ℃ down heating 3 hours with carbonization PVA.Then, in mortar, grind the product of carbonization, obtain powder with the silicon grain of carbon-coating coating.
Comparative Examples 5
With the 0.2g molecular weight is that 500 PVA is added in the distilled water of 10mL and stirs, till PVA dissolves fully.Then,, and under agitation this reactant mixture progressively is heated to water and evaporates fully, obtain comprising the solid of the mixture that constitutes by above-mentioned three kinds of components thus to the silicon that wherein adds 1g Comparative Examples 3/graphite composite powder.
With this solid argon atmospher and 900 ℃ down heating 3 hours with carbonization PVA.Then, in mortar, grind the product of carbonization, obtain powder with the silicon grain of carbon-coating coating.
Comparative Examples 6
The 0.2333g primary average particle size is mixed in the mortar less than the Si powder of 50 μ m and the average grain diameter powdered graphite less than 20 μ m less than 0.5 μ m and secondary average grain diameter, obtains silicon/graphite mixture powder.
The preparation of anode
The active material powder that 0.3g is prepared in each in embodiment 1～8 and Comparative Examples 1～2,2.4g average grain diameter is the powdered graphite of 20 μ m, 0.6g average grain diameter is the powdered graphite of 2 μ m, 0.06g butadiene-styrene rubber (SBR), and the mixing of the carboxymethyl cellulose (CMC) of 0.06g, and to the distilled water that wherein adds 5mL.Utilize mechanical agitator that reactant mixture was stirred 3 hours, make slurry.
With doctor this slurry is coated with the thickness of about 200 μ m on copper (Cu) collector body, carries out drying then.Resulting structures once more in vacuum and 110 ℃ of following dryings, is made positive plate.
The active material powder that 0.7g is prepared in each in embodiment 9 and Comparative Examples 3～6,0.2g average grain diameter is the powdered graphite of 6 μ m, and 0.1g is as the polyvinylidene fluoride (PVDF of binding agent, KF1100, Kureha Chemical Industry Corporation, Japan) be mixed in N-methyl pyrrolidone (NMP) solution, make slurry.
With doctor this slurry is coated with the thickness of about 100 μ m on copper (Cu) collector body, carries out drying then.Resulting structures once more in vacuum and 130 ℃ of following dryings, is made positive plate.
The preparation of lithium battery
Prepare 2015 type standard coinage formula batteries, adopt the positive plate of the anode active material preparation that utilizes embodiment 1～9 and Comparative Examples 1～6, the metal counterelectrode of lithium, the PTFE dividing plate reaches the 1M LiPF as electrolyte solution
6Solution in the mixed solvent that 3:7 is made of EC (ethylene carbonate)+DEC (diethyl carbonate).
The charge/discharge experiment
Just utilizing the coin cell of the anode active material preparation of embodiment 1～8 and Comparative Examples 1～2, carry out constant current charge with the constant charge current of 50mA electric current/1g active material, is 0.001V until battery to the voltage of Li electrode.Then, carry out constant voltage charge, reduce to 5mA electric current/1g active material until the electric current of battery with the constant charging voltage of 0.001V.
The battery of charging was fully placed about 30 minutes.Then, carrying out constant-current discharge with the constant discharge current of 50mA electric current/1g active material, is 1.5V until the voltage of battery.
Above-mentioned result of experiment is shown among following table 1 and Fig. 1.For convenience of explanation, " silicon discharge capacity " used herein is meant that to Li be discharge capacity under 0.25V or the bigger voltage.
Just utilizing the coin cell of the anode active material preparation of embodiment 9 and Comparative Examples 3～6, carry out constant current charge with the constant charge current of 100mA electric current/1g active material, is 0.001V until battery to the voltage of Li electrode.
The battery of charging was fully placed about 30 minutes.Then, carrying out constant-current discharge with the constant discharge current of 100mA electric current/1g active material, is 1.5V until the voltage of battery.Above-mentioned result of experiment is shown in the following table 2.
Table 1
| Project | Charging capacity (mAh/g) | Discharge capacity (mAh/g) | Starting efficiency (mAh/g) |
| Embodiment 1 | 672.3 | 600.1 | 89.2 |
| |
672.9 | 594.4 | 88.6 |
| Embodiment 3 | 673.1 | 590.7 | 87.2 |
| Embodiment 4 | 668.2 | 565.2 | 84.5 |
| Embodiment 5 | 670.3 | 481.7 | 71.8 |
| Embodiment 6 | 644.3 | 468.9 | 72.7 |
| Embodiment 7 | 655.5 | 524.6 | 80.0 |
| Embodiment 8 | 652.3 | 489.7 | 75.1 |
| Comparative Examples 1 | 750.0 | 451.8 | 60.2 |
| Comparative Examples 2 | 680.1 | 506.2 | 74.4 |
As table 1 and shown in Figure 1, compare with the lithium battery of the metal-cored preparation of silicon of only adopting Comparative Examples 1, utilize the lithium battery of the conductive metallic material preparation of embodiment 1～8 to show the discharge capacity and the initial charge/discharge efficient of remarkable enhancing.Simultaneously, compare with the lithium battery of the metal-cored preparation that only scribbles carbonaceous material that utilizes Comparative Examples 2, according to the employing high conductivity of embodiment 1～4 and 7～8 preparations and silver, copper and the zinc of low elasticity coefficient lithium battery, show the discharge capacity and the initial charge/discharge efficient of relative enhancing as electric conducting material., demonstrate equally and the suitable performance of lithium battery of utilizing the metal-cored preparation that only scribbles carbonaceous material according to Comparative Examples 2 as the lithium battery of electric conducting material according to the employing tin of embodiment 5～6 preparation and nickel.This is owing to the existence of the conductive metallic material with satisfactory electrical conductivity and low elasticity coefficient, and this conductive metallic material promotes the migration of electronics and ion, and alleviates metal-cored change in volume, thereby the invertibity that can more easily cause lithium embeds and deviates from.
Table 2
| Project | Charging capacity (mAh/g) | Discharge capacity (mAh/g) | Starting efficiency (%) | Charge/discharge capacity conservation rate (50 circulation) (%) |
| Embodiment 9 | 1050 | 1325 | 79.2 | 80.5 |
| Comparative Examples 3 | 1010 | 1425 | 70.8 | 52.3 |
| Comparative Examples 4 | 901 | 1115 | 80.8 | 70.9 |
| Comparative Examples 5 | 822 | 1017 | 80.8 | 75.8 |
| Comparative Examples 6 | 861 | 1078 | 79.8 | 21 |
Fig. 2 A is transmission electron microscopy (TEM) image of the silicon/graphite composite powder of Comparative Examples 3, and Fig. 2 B is the TEM image of the silicon that the comprises conductive metallic material/graphite composite powder of the embodiment of the invention 9.Different with the silicon shown in Fig. 2 A/graphite composite powder, in the silicon that the comprises conductive metallic material/graphite composite powder shown in Fig. 2 B, be distributed with the conductive metallic material particulate.
As shown in table 2, compare with the lithium battery that utilizes silicon/graphite composite preparation of Comparative Examples 3 and the lithium battery that utilizes silicon/graphite mixture preparation of Comparative Examples 6, the lithium battery that utilizes silicon/graphite composite core and conductive metallic material preparation of embodiment 9 has higher capacity and capability retention characteristic; Simultaneously, the lithium battery that only scribbles the silicon/graphite composite powder preparation of carbonaceous material with Comparative Examples 4 and 5 utilization is compared, and also has identical starting efficiency, higher capacity and better charge/discharge capacity conservation rate.As mentioned above, this is owing to the existence of the conductive metallic material with satisfactory electrical conductivity and low elasticity coefficient, this conductive metallic material promotes the migration of electronics and ion, and alleviates metal-cored change in volume, thereby the invertibity that can more easily cause lithium embeds and deviates from.
According to anode active material of the present invention, cover metal-cored carbon-base coating and comprise electron conduction and elasticity favorable conductive metal material.Therefore, charge/discharge capacity is enhanced, and can remove simultaneously in the charge process stress that causes because of carbon-base coating and metal-cored expansion.In addition, can also reduce direct contact the between metal-cored and the electrolyte solution significantly.In addition, comprising the anode of this anode active material and lithium battery is excellent in charge/discharge characteristics aspect discharge capacity and initial charge/discharge efficient.
Claims (14)
1. anode active material comprises:
Comprise the metal-cored of the metal that can form lithium alloy; And
Coating, this coating is formed on the metal-cored surface, and comprises conductive metallic material.
2. according to the anode active material of claim 1, the conductive metallic material of wherein said coating is present on the metal-cored surface.
3. according to the anode active material of claim 1, wherein this conductive metallic material also is contained in metal-cored inside.
4. according to the anode active material of claim 1, wherein by the total weight of anode active material, the content of described conductive metallic material is 0.1～20wt%.
5. according to the anode active material of claim 1, wherein this conductive metallic material is that resistivity is 5.5 * 10
-8Ω m or littler and coefficient of elasticity are 200GPa or littler metal or its alloy.
6. according to the anode active material of claim 5, wherein this conductive metallic material is that resistivity is 1.4 * 10
-8Ω m～5.5 * 10
-8Ω m and coefficient of elasticity are metal or its alloy of 40～200GPa.
7. according to the anode active material of claim 5, wherein this conductive metallic material is to be selected from least a in following: Cu, Ag, Al, Mg, Zn, and alloy.
8. according to the anode active material of claim 1, wherein this coating is made by low crystalline carbon or amorphous carbon, the interplanar distance (d of described low crystalline carbon
002) be
Or it is bigger.
9. anode active material according to Claim 8, wherein this coating is made by low crystalline carbon or amorphous carbon, the interplanar distance (d of described low crystalline carbon
002) be 3.45～
10. according to the anode active material of claim 1, be selected from least a in following wherein said metal-cored comprising: silicon, aluminium, lead, tin, germanium, silicon alloy, and silicon/graphite composite.
11. an anode, it comprises in the claim 1 to 10 each anode active material.
12. a lithium battery, it adopts anode according to claim 10.
13. a method for preparing anode active material, this method comprises:
Be added to polymeric material and slaine in the solvent and stir this reaction solution;
Metallic particles is added in this reaction solution, then stirs and drying; And
Sintering dry product forming coating,
Wherein the metal of metallic particles can form lithium alloy.
14. according to the method for claim 13, wherein said sintering is to carry out under 500～1250 ℃ temperature.
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| KR100745733B1 (en) * | 2005-09-23 | 2007-08-02 | 삼성에스디아이 주식회사 | Anode active material, producing method thereof and lithium battery using the same |
| KR100759556B1 (en) * | 2005-10-17 | 2007-09-18 | 삼성에스디아이 주식회사 | Anode active material, method of preparing the same, and anode and lithium battery containing the material |
| KR100905691B1 (en) * | 2007-06-20 | 2009-07-03 | 금호석유화학 주식회사 | Anode active material hybridizing carbon nanofiber for lithium secondary battery |
| CN1913200B (en) * | 2006-08-22 | 2010-05-26 | 深圳市贝特瑞电子材料有限公司 | Silicon carbone compound negative polar material of lithium ion battery and its preparation method |
| KR101113008B1 (en) * | 2008-08-04 | 2012-03-13 | (주)썬텔 | Silicon anode composite active material for lithium secondary battery |
| US20140370380A9 (en) * | 2009-05-07 | 2014-12-18 | Yi Cui | Core-shell high capacity nanowires for battery electrodes |
| US20100285358A1 (en) | 2009-05-07 | 2010-11-11 | Amprius, Inc. | Electrode Including Nanostructures for Rechargeable Cells |
| US8450012B2 (en) | 2009-05-27 | 2013-05-28 | Amprius, Inc. | Interconnected hollow nanostructures containing high capacity active materials for use in rechargeable batteries |
| JP6124906B2 (en) * | 2011-11-09 | 2017-05-10 | ロックウッド リチウム ゲゼルシャフト ミット ベシュレンクテル ハフツングＲｏｃｋｗｏｏｄ Ｌｉｔｈｉｕｍ ＧｍｂＨ | Lithium metal product having a shell made of carbon-containing lithium sulfide, process for its production and use thereof |
| KR101463970B1 (en) * | 2012-03-09 | 2014-11-26 | 최대규 | Electrode material for lithium secondary battery,electrode structure comprising the electrode materialand secondary battery comprising the electrodestructure |
| KR101476043B1 (en) * | 2012-07-20 | 2014-12-24 | 주식회사 엘지화학 | Carbon-silicone composite, preparation method thereof, and anode active material comprising the same |
| KR101508480B1 (en) * | 2014-02-19 | 2015-04-07 | 한국화학연구원 | Electrode for lithium secondary battery and manufacturing method of thereof |
| KR102192087B1 (en) | 2014-02-26 | 2020-12-16 | 삼성전자주식회사 | Anode active material, lithium battery comprising the same, and preparation method thereof |
| EP3143657B1 (en) | 2014-05-12 | 2019-07-10 | Amprius, Inc. | Structurally controlled deposition of silicon onto nanowires |
| KR20160008041A (en) * | 2014-07-11 | 2016-01-21 | 오씨아이 주식회사 | Anode active material for lithium secondary battery and manufacturing mehtod of the same |
| KR101632564B1 (en) * | 2014-07-16 | 2016-06-23 | 한국에너지기술연구원 | Silicon nanoparticle having excess atom p or b and preparing method of the same |
| KR101592773B1 (en) * | 2014-10-17 | 2016-02-11 | 오씨아이 주식회사 | Anode active material and secondary battery comprising the same |
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