CN108666575A - Combined conductive agent and preparation method thereof, Anode and battery - Google Patents
Combined conductive agent and preparation method thereof, Anode and battery Download PDFInfo
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- CN108666575A CN108666575A CN201710203307.5A CN201710203307A CN108666575A CN 108666575 A CN108666575 A CN 108666575A CN 201710203307 A CN201710203307 A CN 201710203307A CN 108666575 A CN108666575 A CN 108666575A
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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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
The present invention provides a kind of combined conductive agent, and the combined conductive agent includes internal layer and clad, and the material of the internal layer includes graphite, and the material of the clad is TiO2Or SnO2, the clad accounts for the mass percent ranging from 0.001 20% of the internal layer.Compared with prior art, the graphite that the combined conductive agent of the present invention is coated using titanium dioxide or stannic oxide, combined conductive agent can be very good to take into account electric conductivity and stability when as conductive agent, so as to avoid conductive agent graphitic corrosion, reduce self-discharge of battery, enhances the float life of battery.
Description
Technical field
The invention belongs to energy storage fields, and in particular to a kind of combined conductive agent and preparation method thereof including graphite.
Anode and battery the invention further relates to the purposes of the combined conductive agent and containing this combined conductive agent.
Background technology
Compared to lithium ion battery, the characteristic of the high security of aqoue seconary battery, high ion conductivity and low cost makes
It is in urgent need in extensive energy storage field such as renewable power supply, power grid, even hybrid vehicle.So far, water system
Secondary cell is based on the metal ion insertion principles of chemistry such as alkaline Zn-MnO2Battery, lead-acid battery, Ni-MH battery are just a large amount of
Research or commercialization.
Newly there is a kind of aqoue seconary battery exchanged based on inner ion.The operation principle of the battery is positive base
In abjection-insertion reaction of the first metal ion, deposition of the cathode based on the second metal ion-dissolving reaction, electrolyte is containing ginseng
The second metal ion reacted with the first metal ion of positive abjection-insertion reaction and participation cathode deposition-dissolving.The type
The theoretical energy density of battery is 160Wh/Kg, it is contemplated that actual energy density is up to 50~80Wh/Kg.In conclusion the type
Battery promises to be the next-generation energy-storage battery for substituting lead-acid battery very much, has great commercial value.Currently, this water
It is that secondary cell mainly uses LiMn2O4As a positive electrode active material, but its electric conductivity is not met by requirement.
But the battery is in floating charge at present, corrosion can occur for anode conductive agent graphite to be consumed, and lead to electricity
Pond self discharge is serious, to influence the float life of battery.
Invention content
The object of the present invention is to provide a kind of combined conductive agent, which exists for water system anode conductive agent
With good stability and corrosion resistance when charging.
The present invention provides a kind of combined conductive agent, the combined conductive agent includes internal layer and clad, the internal layer
Material includes graphite, and the material of the clad is TiO2 or SnO2, and the clad accounts for the mass percent model of the internal layer
It encloses for 0.001-20%.
Preferably, the clad accounts for the mass percent ranging from 1-15% of the internal layer.
Preferably, the average particle size particle size of the graphite is 10-50 μm.
The present invention also provides a kind of purposes of combined conductive agent as described above, the purposes is the conduction for battery
Agent.
The present invention also provides a kind of anode, the anode includes positive electrode, and the positive electrode includes positive-active
Substance and positive conductive agent, the positive conductive agent use combined conductive agent as described above.
The present invention also provides a kind of batteries, including anode, cathode and the electricity being arranged between the anode and cathode
Liquid is solved, the anode includes positive electrode, and the positive electrode includes positive active material and positive conductive agent, and the anode is led
Electric agent uses combined conductive agent as described above.
Preferably, the positive conductive agent accounts for the mass percentage ranging from 2%-15% of the positive electrode.
Preferably, mass percentage ranging from 80-90% of the positive active material in the positive electrode.
Preferably, the positive active material can it is reversible deviate from-be embedded in the first metal ion, first metal ion
Selected from lithium ion, sodium ion or magnesium ion；The electrolyte includes electrolyte and aqueous solvent；The electrolyte at least being capable of electricity
Separate out first metal ion and the second metal ion；First metal ion is in charge and discharge process in the positive energy
Enough reversible abjection-insertions；Second metal ion is deposited as the second metal in charging process in the cathodic reduction, described
Second metal oxidation dissolution in discharge process is the second metal ion；Second metal ion be selected from manganese ion, iron ion,
Copper ion, zinc ion, chromium ion, nickel ion, tin ion or lead ion；The anion of the electrolyte include sulfate ion,
Chlorion, acetate ion, nitrate ion, one or more of formate ion and alkyl sulfonate ion；The electricity
The pH value for solving liquid is 2-8；The battery further includes the diaphragm between anode and cathode.
The present invention also provides a kind of preparation methods of combined conductive agent as described above, and the preparation method includes following
Step：
Graphite, titanium source or tin source are weighed according to predetermined ratio；Titanium source or tin source are dispersed in alcohol solvent, stone is added
Ink stirs, dry, and mixture is made；The mixture is heated to 300-400 DEG C, keeps the temperature at least 1 hour, cooling, the tin
Source is stannic oxide or tin acetate, and the titanium source is titanium dioxide or butyl titanate.
Preferably, the heating rate when heating is 5-10 DEG C/min.
Compared with prior art, the graphite that combined conductive agent of the invention is coated using titanium dioxide or stannic oxide, it is multiple
Conductive agent is closed to can be very good to take into account electric conductivity and stability when as conductive agent, so as to avoid conductive agent graphitic corrosion,
Reduce self-discharge of battery, enhances the float life of battery.Meanwhile the method letter provided by the invention for preparing combined conductive agent
It is single, there is commercial applications foreground.
Specific implementation mode
In order to make the technical problems, technical solutions and beneficial effects solved by the present invention be more clearly understood, below in conjunction with
Embodiment, the present invention will be described in further detail.It should be appreciated that specific embodiment described herein is only explaining this
Invention, is not intended to limit the present invention.
The present invention provides a kind of combined conductive agent, combined conductive agent has included internal layer and clad.
The material of internal layer includes graphite, and internal layer mainly plays electric action, and the average particle size particle size of graphite is 10-50 μm, excellent
Choosing, the average particle size particle size of graphite is 20-30 μm.In this way, not only can effectively increase positive electrode active material in positive electrode
Contact area between matter and graphite improves conductive agent graphite and positive active material micro interface conductive capability, enhances
The compacted density and electric conductivity of positive electrode；Moreover, graphite itself has certain resistance to corrosion, while effective construction
The skeleton of firm, continuous conductive network in the normal charge and discharge of battery or float avoids conductive network skeleton
The consumption caved in conductive agent, improve battery cycle life.
Clad mainly shields to internal layer, and internal layer graphite is made to be not easy when battery charges and electrolyte contacts,
To inhibit internal layer graphite that side reaction occurs to be consumed.
Specifically, clad accounts for the mass percent ranging from 0.001-20% of internal layer.Preferably, clad accounts for internal layer
Mass percent ranging from 1-15%.It is furthermore preferred that clad accounts for the mass percent ranging from 5-15% of internal layer.Pass through control
Clad controls cladding degree of the clad to internal layer relative to the mass percent of internal layer, in the present invention combined conductive agent
Basic function be conductive agent, therefore, the amount of clad is had it both ways because usually setting, and being on the one hand will not be to multiple
The electric conductivity for closing conductive agent has apparent influence, is on the other hand to have significant protective effect to internal layer graphite.
The material of clad includes TiO2Or SnO2, TiO2Or SnO2Particle size be nanoscale, TiO2Average grain
Size is 20-30nm, SnO2Average particle size particle size be 50-100nm.In a specific embodiment, TiO2Average grain
Size is 25nm, and the average particle size particle size of SnO2 is 100nm.In this way, clad can play internal layer graphite good protection
The electric conductivity acted on without influencing graphite.
The present invention also provides a kind of preparation method of combined conductive agent, combined conductive agent is prepared by way of heat treatment
And it obtains.
Preparation method includes the following steps：
Graphite, titanium source or tin source are weighed according to predetermined ratio；Titanium source or tin source are dispersed in alcohol solvent, stone is added
Ink stirs, dry, and mixture is made；The mixture is heated to 300-400 DEG C, keeps the temperature at least 1 hour, it is cooling.
Specifically, tin source is selected from stannic oxide or tin acetate.In a preferred embodiment, tin source is tin acetate, this
The combined conductive agent that sample obtains has clad evenly.
Specifically, titanium source is selected from titanium dioxide or butyl titanate.In a preferred embodiment, titanium source is metatitanic acid four
Butyl ester, the combined conductive agent being achieved in that have clad evenly.
During heating, heating rate when heating is 5-10 DEG C/min, in this way, the particle of the combined conductive agent obtained
Size has distribution evenly.
In terms of titanium dioxide in titanium source, or in terms of stannic oxide in tin source, titanium dioxide or stannic oxide are opposite before coating
In the mass percent ranging from 0.001-20% of graphite, preferred mass percent ranging from 5-15%.
The present invention is mixed graphite and titanium source or graphite and tin source by the way of wet-mixing, while using ethyl alcohol conduct
Dispersant, titanium source such as butyl titanate can be hydrolyzed slowly in ethanol, and to form the particle of nanoscale, and tin source is in second
There is good dispersibility in alcohol, be thus uniformly mixed graphite and titanium source or graphite and tin source, the combined conductive agent tool of preparation
There is particle size distribution evenly.
Compared to the combined conductive agent for obtaining graphite and the direct mixed method of coating layer material, preparation method of the present invention obtains
The combined conductive agent obtained is used as having more preferably chemical property when conductive agent, can significantly promote battery float performance.Together
When preparation method provided by the invention be easy to amplify, have good commercial application prospect.
The present invention also provides a kind of anode, anode includes positive electrode, and positive electrode includes positive active material and just
Pole conductive agent, positive conductive agent use combined conductive agent as described above.
The present invention also provides a kind of batteries, include the electrolyte of positive, cathode and setting between a positive electrode and a negative electrode,
Anode includes positive electrode, and positive electrode includes positive active material and positive conductive agent, and positive conductive agent is using as described above
Combined conductive agent.
Positive active material participate in anode reaction, and can it is reversible deviate from-be embedded in the first metal ion.Preferably,
One metal ion is selected from lithium ion, sodium ion or magnesium ion.
Positive active material can meet general formula Li1+xMnyMzOkCan it is reversible deviate from-be embedded in the spinelle of lithium ion
The compound of structure, wherein -1≤x≤0.5,1≤y≤2.5,0≤z≤0.5,3≤k≤6, M be selected from Na, Li, Co, Mg, Ti,
At least one of Cr, V, Zn, Zr, Si, Al.Preferably, positive active material contains LiMn2O4.It is furthermore preferred that positive-active
Substance contains the LiMn through overdoping or coating modification2O4。
Positive active material can meet general formula Li1+xMyM′zM″cO2+nCan it is reversible deviate from-be embedded in the layer of lithium ion
The compound of shape structure, wherein -1<X≤0.5,0≤y≤1,0≤z≤1,0≤c≤1, -0.2≤n≤0.2, M, M ', M " points
Not Xuan Zi Ni, Mn, Co, Mg, Ti, Cr, V, Zn, Zr, Si or Al at least one of.
Positive active material, which can also be, meets general formula LixM1-yM′y(XO4)nCan it is reversible deviate from-be embedded in lithium ion
The compound of olivine structural, wherein 0<X≤2,0≤y≤0.6,1≤n≤1.5, M be selected from Fe, Mn, V or Co, M ' be selected from Mg,
At least one of Ti, Cr, V or Al, X is selected from least one of S, P or Si.
Preferably, positive active material is selected from LiMn2O4、LiFePO4Or LiCoO2Middle one or more.
In current battery industry, nearly all positive active material all can be through modifications such as overdoping, claddings.But it mixes
Miscellaneous, the means such as coating modification cause the chemical general formula of material to express complicated, such as LiMn2O4Can not represent makes extensively at present
The general formula of " LiMn2O4 ", and should be with general formula Li1+xMnyMzOkSubject to, include widely the LiMn by various modifications2O4
Positive active material.Likewise, LiFePO4And LiCoO2Also it should be construed broadly to include by various doping, cladding etc.
Modified, general formula corresponds with LixM1-yM′y(XO4)nAnd Li1+xMyM′zM″cO2+nPositive active material.
When positive active material is lithium ion abjection-inlaid scheme, it can select such as LiMn2O4、LiFePO4、
LiCoO2、LiMxPO4、LiMxSiOyCompounds such as a kind of (wherein M are variable valency metal).
In addition, can deviate from-be embedded in the compound N aVPO of sodium ion4F can deviate from-be embedded in the compound Mg M of magnesium ionxOy
(wherein M be a kind of metal, 0.5<x<3,2<y<6) and there are similar functions ,-the change of embedded ion or functional group can be deviate from
The positive active material that object all can serve as battery of the present invention is closed, therefore, the invention is not limited in lithium ion batteries.
Preferably, positive conductive agent accounts for the mass percentage ranging from 2%-15% of positive electrode, positive active material
In the mass percentage ranging from 80-90% of positive electrode, in this way, ensureing positive electrode with excellent conduction and leading
While ionic nature, make anode that there is higher capacity.More preferred, positive conductive agent accounts for the quality percentage of positive electrode
Content range is 3%-10%.
In the particular embodiment, when preparing anode, in positive electrode in addition to positive active material and positive conductive agent it
Outside, positive electrode binder usually can may also be added to promote the performance of anode.Exemplary, positive electrode binder is selected from polytetrafluoroethylene (PTFE)
(PTFE), Kynoar (PVDF) or butadiene-styrene rubber (SBR).
Positive active material is supported on plus plate current-collecting body, the carrier that plus plate current-collecting body is conducted and collected as electronics, no
Electrochemical reaction is participated in, i.e., within the scope of battery operating voltage, what plus plate current-collecting body can be stablized is present in electrolyte and base
Side reaction does not occur in this, to ensure that battery has stable cycle performance.
There are many selections for the selection of plus plate current-collecting body and composition.
Selection one
The one kind of the material of plus plate current-collecting body in carbon-based material, metal or alloy.
The one kind of carbon-based material in vitreous carbon, graphite foil, graphite flake, foamy carbon, carbon felt, carbon cloth, carbon fiber.Having
In the embodiment of body, plus plate current-collecting body is graphite, such as the foil of commercialized graphite compacting, the wherein weight ratio shared by graphite
Ranging from 90-100%.
Metal includes one in Ni, Al, Fe, Cu, Pb, Ti, Cr, Mo, Co, Ag or above-mentioned metal Jing Guo Passivation Treatment
Kind.
Alloy includes stainless steel, carbon steel, Al alloys, Ni alloys, Ti alloys, Cu alloys, Co alloys, Ti-Pt alloys, Pt-
Rh alloys or above-mentioned metal are by one kind in Passivation Treatment.
Stainless steel includes stainless (steel) wire, stainless steel foil, and the model of stainless steel includes but are not limited to stainless steel 304 or not
The one kind become rusty in steel 316 or Stainless steel 316 L.
Preferably, processing is passivated to plus plate current-collecting body, main purpose is that the surface of plus plate current-collecting body is made to form one layer
The oxidation film of passivation, to which stable collection and conduction electronics in battery charge and discharge process, can be played the role of, without joining
With cell reaction, ensure that battery performance is stablized.Plus plate current-collecting body deactivating process for the treatment of includes that chemical passivation processing or electrochemistry are blunt
Change is handled.
Chemical passivation processing includes so that plus plate current-collecting body surface is formed passivating film by oxidizing plus plate current-collecting body.
The principle that oxidant selects can make plus plate current-collecting body surface form one layer of passivating film without dissolving plus plate current-collecting body for oxidant.
Oxidant is selected from but is not limited only to concentrated nitric acid or ceric sulfate (Ce (SO4)2)。
Electrochemical passivation processing includes carrying out electrochemical oxidation to plus plate current-collecting body or to the battery containing plus plate current-collecting body
Charge and discharge electric treatment is carried out, plus plate current-collecting body surface is made to form passivating film.
Selection two
Preferably, conductive film is also wrapped on plus plate current-collecting body, the selection of wherein plus plate current-collecting body can be found in selection one, this
In just repeat no more.
The selection satisfaction of conductive film can be stabilized in aqueous electrolyte, insoluble in electrolyte, swelling does not occur, is high
Voltage cannot be aoxidized, be easily processed into fine and close, waterproof and conductive requirement.On the one hand, conductive film is to plus plate current-collecting body
It can play a protective role, avoid corrosion of the aqueous electrolyte to plus plate current-collecting body.On the other hand, advantageously reduce positive plate with
Contact internal resistance between plus plate current-collecting body, improves the energy of battery.
Preferably, the thickness of conductive film is 10 μm~2mm, and conductive film can not only effectively play protection plus plate current-collecting body
Effect, and advantageously reduce the contact internal resistance between positive active material and plus plate current-collecting body, improve the energy of battery.
Plus plate current-collecting body has the first face and the second face that are oppositely arranged, it is preferred that the first face of plus plate current-collecting body and the
Two faces are coated with conductive film.
Conductive film includes the polymer as necessary component, and the weight proportion that polymer accounts for conductive film is 50~95%, excellent
Choosing, polymer is selected from thermoplastic polymer.In order to keep conductive film conductive, there are two types of feasible forms：(1) polymer is
Conducting polymer；(2) other than polymer, conductive film also includes conductive filler.
Conducting polymer choice requirement be with conductive capability but electrochemicaUy inert, i.e., will not be as charge transfer medium
Ionic conduction.Specifically, conducting polymer include but are not limited to polyacetylene, polypyrrole, polythiophene, polyphenylene sulfide, polyaniline,
Polyacrylonitrile, poly quinoline, polyparaphenylene (polyparaphenylene) and its any mixture.Conducting polymer inherently has
It is conductive, it is also possible to be doped or be modified to conducting polymer to further increase its conductive capability.From electric conductivity
It is considered with the use of stablizing in battery, the preferred polyaniline of conducting polymer, polypyrrole, polythiophene and polyacetylene.
Likewise, the choice requirement of conductive filler is that surface area is small, be difficult to aoxidize, crystallinity is high, conductive but electric
Chemical inertness, i.e., will not be as the ionic conduction of charge transfer medium.
The material of conductive filler includes but are not limited to conducting polymer, carbon-based material or metal oxide.Conductive filler
Mass percent in the conductive film ranging from 5~50%.The average grain diameter of conductive filler is not particularly limited, usual range
In 100nm~100 μm.
When in conductive film including conductive filler, the polymer in conductive film, which preferably comprises, to be played the role of in conjunction with conductive filler
Non-conductive polymer, non-conductive polymer enhances the combination of conductive filler, improves the reliability of battery.Preferably, non-
Conducting polymer is thermoplastic polymer.
Specifically, thermoplastic polymer includes but are not limited to polyolefin such as polyethylene, polypropylene, polybutene, polychlorostyrene second
Alkene, polystyrene, polyamide, makrolon, polymethyl methacrylate, polyformaldehyde, polyphenylene oxide, polysulfones, polyether sulfone, butylbenzene rubber
It is one or more in glue or Kynoar.Wherein, preferably polyolefin, polyamide and Kynoar.These polymer
It is easy to melt by heat, therefore is easy to be combined with each other with plus plate current-collecting body.In addition, these polymer have big electrochemical window
Mouthful, to make positive stabilizer pole and save weight for battery output density.
It is exemplary, conductive film can it is compound hot pressing, vacuumize or be attached on plus plate current-collecting body by way of spraying.
Selection three
More preferred, plus plate current-collecting body includes carrier and the graphite that is coated on carrier.
In order to ensure that anode has high energy density, therefore the thickness of plus plate current-collecting body needs suitable selection.It is excellent
Choosing, the thickness range of graphite is 0.1-0.2mm；The thickness of carrier is less than 1mm, it is preferred that the thickness range of carrier is 0.1-
0.2mm。
Preferably, the content of carbon is more than 97% in graphite, avoids influence of the impurity in graphite to battery performance.
Preferably, the form of graphite is graphite paper (graphite foil), also known as graphite foil.In general, graphite paper is by stone
Ink powder passes through a series of processing, and pressure rolling is at flexible, frivolous paper-like graphite.Preferably, the density of graphite paper is more than 1.0g/cm3,
Graphite paper density is bigger, and structure is finer and close, and easy to foaming to ensure not allowing used in graphite paper surface in water system battery, performance is steady
It is fixed.
Carrier electrochemicaUy inert itself, according to well known to those skilled in the art, electrochemicaUy inert, that is, carrier is not involved in any
Electrochemical reaction.Carrier primarily serves the effect of carrying graphite, and to improve the mechanical performance of graphite, graphite primarily serves collection
With the effect of conduction electronics.
Exemplary, the material of carrier is selected from polyethylene terephthalate, polybutylene terephthalate, polyethylene, gathers
One kind in propylene, polyamide, polyurethanes, polyacrylonitrile.What these polymer materials can be stablized is present in anode
It is not involved in electrochemical reaction in collector, is that weight is saved in the higher energy density output of battery.Preferably, carrier is nylon
Net, i.e. polyamide.
Exemplary, graphite paper is compound by hot pressing, and the mode of rolling or gluing is coated on carrier.
Cathode can be following three kinds of different forms according to its structure and the difference of effect：
Cathode only includes negative current collector, and negative current collector is only conducted as electronics and the carrier of collection, is not involved in
Electrochemical reaction.
Exemplary, negative current collector is copper foil, stainless (steel) wire, stainless steel foil or graphite foil.
Cathode only includes negative electrode active material, and negative electrode active material is used as negative current collector simultaneously.It is exemplary, the second metal
Ion is zinc ion, and cathode is zinc foil.Zinc foil may participate in negative reaction.
Preferably, cathode includes negative electrode active material and negative current collector, and negative electrode active material is supported on negative current collector
On.Negative electrode active material and the second metal phase are same, as the second metal ion is Zn in electrolyte2+, the second metal is metal Zn, that
It is also metal Zn that negative electrode active material, which corresponds to,.More preferred, cathode includes filtter gold and zinc foil, and filtter gold is as cathode collection
Fluid, zinc foil correspond to negative electrode active material, may participate in negative reaction.
Negative electrode active material is with sheet or powdered presence.
When negative electrode active material is sheet, negative electrode active material forms composite layer with negative current collector.
When negative electrode active material is powder, slurry is made in the second metal powder, slurry is then coated in cathode collection
Cathode is made on fluid.In a particular embodiment, when preparing cathode, in addition to the second metal powder of negative electrode active material it
Outside, according to actual conditions, the performance of cathode is promoted also according to needing to add cathode conductive agent and negative electrode binder.
Electrolyte includes electrolyte and aqueous solvent；Electrolyte can at least ionize out the first metal ion and the second metal
Ion；First metal ion in charge and discharge process anode can it is reversible deviate from-be embedded in；Second metal ion is in charging process
In in cathodic reduction be deposited as the second metal, the second metal oxidation dissolution in discharge process is the second metal ion.
Second metal ion is selected from manganese ion, iron ion, copper ion, zinc ion, chromium ion, nickel ion, tin ion or lead
Ion.
Under a preferred embodiment, the first metal ion of the invention is selected from lithium ion, while the second metal ion is selected from
Zinc ion, i.e., cation is lithium ion and zinc ion in electrolyte.
Anion in electrolyte can any have substantially no effect on positive and negative anodes reaction and electrolyte in a solvent molten
The anion of solution.Such as can be sulfate ion, chlorion, acetate ion, formate ion, phosphate anion, alkyl
Sulfonate ion and its mixing etc..Specifically, alkyl sulfonate ion can be methanesulfonate ions etc..
The concentration of each ion in electrolyte, can be according to differences such as the application fields of different electrolyte, solvent and battery
Situation and be changed allotment.
Preferably, in the electrolytic solution, a concentration of 0.1~10mol/L of the first metal ion.
Preferably, in the electrolytic solution, a concentration of 0.5~15mol/L of the second metal ion.
Preferably, in the electrolytic solution, a concentration of 0.5~12mol/L of anion.
Preferably, the pH value of electrolyte is 2-8.
It is preferred that diaphragm is additionally provided between positive electrode and negative electrode in the electrolytic solution.Diaphragm can be made to avoid other unexpected factors
At positive and negative anodes be connected and caused by short circuit.
Diaphragm does not have particular/special requirement, as long as allow electrolyte by and electronic isolation diaphragm.Organic system lithium from
The various diaphragms that sub- battery uses, can be adapted for the present invention.Diaphragm can also be micropore ceramics partition board, glass fibre AGM
Or the other materials such as AFG.
The graphite that the combined conductive agent of the present invention is coated using titanium dioxide or stannic oxide, combined conductive agent are used as conduction
It can be very good to take into account electric conductivity and stability when agent, so as to avoid graphitic corrosion, reduce self-discharge of battery, enhance electricity
The float life in pond.Meanwhile the method provided by the invention for preparing combined conductive agent is simple, has commercial applications foreground.
Below by embodiment, the present invention is further described.
Embodiment 1-1
Graphite and butyl titanate are weighed according to predetermined ratio, butyl titanate is dispersed in 20 milliliters of alcohol solvent
In, graphite is then added, stirs evenly, mixed solution is made；Mixed solution is heated to 300 with the heating rate of 5 DEG C/min
DEG C, 3 hours then are kept the temperature at 240 DEG C, the graphite combined conductive agent of cooling obtained coated by titanium dioxide.With in butyl titanate
The quality of titanium dioxide is counted, and the mass percent that titanium dioxide accounts for graphite is 1%
By LiMn2O4 LiMn2O4(about 0.2 μm of grain size, MTI Co., Ltd.), the graphite of conductive agent coated by titanium dioxide, bonding
Agent polyvinyladine floride (Kynar, HSV900) is according to mass ratio 86:7:7 N-Methyl pyrrolidone (NMP Sigma-Aldrich,
Purity >=99.5%) in mixing, form uniform anode sizing agent.Anode sizing agent is coated in plus plate current-collecting body graphite foil (Alfa
Aesar on), it is dried in vacuo the disk for being cut into 12mm diameters for 24 hours at 60 DEG C, anode is made.
Cathode uses the zinc metal sheet (Rotometals, thickness 0.2mm) of 12mm diameters.
Electrolyte, which uses, contains 1mol/L zinc sulfate (AlfaAesar, purity >=98%) and 2mol/L lithium sulfates (Sigma
Aldrich, purity >=98%) aqueous solution.It is 4 to adjust electrolyte ph.
Diaphragm uses AGM diaphragms (NSG companies).
Anode, cathode and diaphragm are assembled into battery core, is packed into shell, is then injected into electrolyte, seals, is assembled into button
Formula battery, is denoted as B1-1.
Embodiment 1-2
In the combined conductive agent of embodiment 1-2, come by the quality of titanium dioxide in butyl titanate in terms of, titanium dioxide accounts for
The mass percent of graphite is 2%, and combined conductive agent remaining composition, preparation method, anode forms and preparation method, cathode and electricity
Liquid is solved with embodiment 1-1, manufactured button cell is denoted as B1-2.
Embodiment 1-3
In the combined conductive agent of embodiment 1-3, come by the quality of titanium dioxide in butyl titanate in terms of, titanium dioxide accounts for
The mass percent of graphite is 5%, and combined conductive agent remaining composition, preparation method, anode forms and preparation method, cathode and electricity
Liquid is solved with embodiment 1-1, manufactured button cell is denoted as B1-3.
Embodiment 1-4
In the combined conductive agent of embodiment 1-4, come by the quality of titanium dioxide in butyl titanate in terms of, titanium dioxide accounts for
The mass percent of graphite is 10%, combined conductive agent remaining composition, preparation method, anode forms and preparation method, cathode and
Electrolyte is denoted as B1-4 with embodiment 1-1, manufactured button cell.
Embodiment 1-5
In the combined conductive agent of embodiment 1-5, come by the quality of titanium dioxide in butyl titanate in terms of, titanium dioxide accounts for
The mass percent of graphite is 15%, combined conductive agent remaining composition, preparation method, anode forms and preparation method, cathode and
Electrolyte is denoted as B1-5 with embodiment 1-1, manufactured button cell.
Comparative example 1-1
Positive conductive agent is graphite in comparative example 1-1, and graphite does not have clad.
With embodiment 1-1, manufactured button cell is denoted as C1- for remaining composition of anode and preparation method, cathode and electrolyte
1。
Comparative example 1-2
In comparative example 1-2, for graphite with titanium dioxide not through Overheating Treatment, directly mixing is used as conductive agent, titanium dioxide
The mass percent that titanium accounts for graphite is 1%.
With embodiment 1-1, manufactured button cell is denoted as C1- for remaining composition of anode and preparation method, cathode and electrolyte
2。
Comparative example 1-3
In comparative example 1-3, for graphite with titanium dioxide not through Overheating Treatment, directly mixing is used as conductive agent, titanium dioxide
The mass percent that titanium accounts for graphite is 2%.
With embodiment 1-1, manufactured button cell is denoted as C1- for remaining composition of anode and preparation method, cathode and electrolyte
3。
Floating charge performance test
By battery B1-1 to B1-3, C1-1 to C1-3 first charge and discharge 3 times between voltage range 1.4V-2.1V with 0.2C,
After battery is charged to voltage 2.1V again, with 2.1V floating charges 24 hours.Floating current during record floating charge and floating charge capacity.
High rate performance is tested
By battery B1-1 to B1-3 and C1-1 with different multiplying (0.2C, 0.5C, 1C, 2C and 4C) in voltage range 1.4V-
Charge and discharge between 2.1V, each charge and discharge cycles 5 times, finally switch to 0.2C charge and discharge again under different multiplying.
Floating charge test result is as shown in Table 1.
Table one
| Battery | TiO2 amounts (%) | Preparation method | Floating current (mA/g) | Floating charge capacity (mAh/g) |
| B1-1 | 1% | Heat treatment | 0.71 | 3.64 |
| B1-2 | 2% | Heat treatment | 0.83 | 5.98 |
| B1-3 | 5% | Heat treatment | 1.16 | 7.62 |
| C1-1 | — | — | 1.79 | 13.22 |
| C1-2 | 1% | Directly mix | 1.13 | 7.98 |
| C1-3 | 2% | Directly mix | 1.23 | 8.34 |
It can be seen that from one result of table：By battery B1-1 to B1-3 compared with C1, it is coated with the graphite conduct of titanium dioxide
Combined conductive agent, battery float electric current and floating charge capacity directly use graphite to act on conductive agent compared to battery, reduce respectively
35-60% and 42-72%, this is the result shows that graphite coat titanium dioxide can be substantially reduced the self discharge of battery.Battery C1-
1 and C1-2, C1-3 be compared, can also further prove this conclusion.
Further, by battery B1-1, B1-2 and C1-2, C1-3 correspondence compare, the floating current of battery B1-1, B1-2 and
Floating charge capacity is also significantly lower than the floating current and floating charge capacity of battery C1-2, C1-3, illustrates that preparation method obtains through the invention
The combined conductive agent obtained has more obvious effect to the improvement of the floating charge performance of battery.
In addition, battery 1-4 and battery 1-5 has a significant effect to the improvement of the floating charge performance of battery.
High rate performance test result is shown：Battery B1-2 has best high rate performance, especially in the high magnification of 1C-4C
Under, followed by battery B1-3 and B1-1, battery B1-1 to B1-3 are also above battery C1-1 in the discharge capacity of different multiplying.
Embodiment 2-1
Graphite and stannic oxide (particle size are weighed according to predetermined ratio<100nm), stannic oxide is dispersed in 20 milliliters
Alcohol solvent in, graphite is then added, stirs evenly, be made mixed solution；By mixed solution with the heating rate of 5 DEG C/min
300 DEG C are heated to, then keeps the temperature 3 hours at 240 DEG C, the graphite combined conductive agent of cooling obtained stannic oxide cladding.Former material
In material, the mass percent that stannic oxide accounts for graphite is 1%.
Remaining anode, cathode, diaphragm and electrolyte are assembled into button cell, are denoted as B2-1 with embodiment 1-1.
Embodiment 2-2
In embodiment 2-2, graphite is coated using stannic oxide, stannic oxide accounts for the quality of graphite in raw material
Percentage is 2%, and combined conductive agent preparation method, anode, cathode and electrolyte are assembled into button cell with embodiment 2-1, note
Make B2-2.
Embodiment 2-3
In embodiment 2-3, graphite is coated using stannic oxide, stannic oxide accounts for the quality of graphite in raw material
Percentage is 5%, and combined conductive agent preparation method, anode, cathode and electrolyte are assembled into button cell with embodiment 2-1, note
Make B2-3.
Embodiment 2-4
In embodiment 2-4, graphite is coated using stannic oxide, stannic oxide accounts for the quality of graphite in raw material
Percentage is 10%, and combined conductive agent preparation method, anode, cathode and electrolyte are assembled into button cell with embodiment 2-1,
It is denoted as B2-4.
Embodiment 2-5
In embodiment 2-5, graphite is coated using stannic oxide, stannic oxide accounts for the quality of graphite in raw material
Percentage is 15%, and combined conductive agent preparation method, anode, cathode and electrolyte are assembled into button cell with embodiment 2-1,
It is denoted as B2-5.
Floating charge performance test
It charges by battery B2-1 to B2-3 first charge and discharge 3 times between voltage range 1.4V-2.1V with 0.2C, then by battery
To voltage 2.1V, with 2.1V floating charges 24 hours.Floating current during record floating charge and floating charge capacity.
Floating charge test result is as shown in Table 2.
It can be seen that from two result of table：By battery B2-1 to B2-3 compared with C1, it is coated with the graphite conduct of stannic oxide
Combined conductive agent, battery float electric current and floating charge capacity directly use graphite to act on conductive agent compared to battery, reduce respectively
20-44% and 43-47%, this is the result shows that graphite coat stannic oxide can be substantially reduced the self discharge of battery.
Table two
| Battery | SnO2 amounts (%) | Preparation method | Floating current (mA/g) | Floating charge capacity (mAh/g) |
| B2-1 | 1% | Heat treatment | 1.42 | 7.52 |
| B2-2 | 2% | Heat treatment | 1.23 | 7.11 |
| B2-3 | 5% | Heat treatment | 1.01 | 6.98 |
| C1-1 | — | — | 1.79 | 13.22 |
In addition, battery 2-4 and battery 2-5 has a significant effect to the improvement of the floating charge performance of battery.
Although inventor has done more detailed elaboration to technical scheme of the present invention and has enumerated, it should be understood that for
For those skilled in the art, above-described embodiment is modified and/or the flexible or equivalent alternative solution of use is obvious
, cannot all be detached from the essence of spirit of that invention, the term occurred in the present invention be used for elaboration to technical solution of the present invention and
Understand, can not be construed as limiting the invention.
Claims (10)
1. a kind of combined conductive agent, the combined conductive agent includes internal layer and clad, and the material of the internal layer includes graphite, institute
The material for stating clad is TiO2Or SnO2, the clad accounts for the mass percent ranging from 0.001-20% of the internal layer.
2. combined conductive agent according to claim 1, the clad accounts for the mass percent ranging from 1- of the internal layer
15%.
3. the average particle size particle size of combined conductive agent according to claim 1, the graphite is 10-50 μm.
4. a kind of anode, the anode includes positive electrode, and the positive electrode includes positive active material and positive conductive agent,
The positive conductive agent is using the combined conductive agent as described in any one of claim 1-3.
5. a kind of battery, including anode, cathode and the electrolyte being arranged between the anode and cathode, the anode include
Positive electrode, the positive electrode include positive active material and positive conductive agent, and the positive conductive agent is used as right is wanted
Seek the combined conductive agent described in any one of 1-3.
6. battery according to claim 5, it is characterised in that：The positive conductive agent accounts for the quality hundred of the positive electrode
It is 2%-15% to divide content range.
7. battery according to claim 5, it is characterised in that：Quality of the positive active material in the positive electrode
Percent ranges are 80-90%.
8. battery according to claim 5, it is characterised in that：The positive active material can it is reversible deviate from-be embedded in
One metal ion, first metal ion are selected from lithium ion, sodium ion or magnesium ion；The electrolyte include electrolyte and
Aqueous solvent；The electrolyte can at least ionize out first metal ion and the second metal ion；First metal from
Son in charge and discharge process the anode can it is reversible deviate from-be embedded in；Second metal ion is in charging process in institute
It states cathodic reduction and is deposited as the second metal, second metal oxidation dissolution in discharge process is the second metal ion；It is described
Second metal ion is selected from manganese ion, iron ion, copper ion, zinc ion, chromium ion, nickel ion, tin ion or lead ion；It is described
The anion of electrolyte includes sulfate ion, chlorion, acetate ion, nitrate ion, formate ion and alkyl sulphur
One or more of acid ion；The pH value of the electrolyte is 2-8；The battery further includes between anode and cathode
Diaphragm.
9. a kind of preparation method of combined conductive agent as described in claim 1, the preparation method comprises the following steps：
Graphite, titanium source or tin source are weighed according to predetermined ratio；Titanium source or tin source are dispersed in alcohol solvent, graphite is added, stirs
It mixes, it is dry, mixture is made；The mixture is heated to 300-400 DEG C, keeps the temperature at least 1 hour, cooling, the tin source is
Stannic oxide or tin acetate, the titanium source are titanium dioxide or butyl titanate.
10. preparation method according to claim 9, it is characterised in that：The heating rate when heating is 5-10 DEG C/
min。
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| CN111640942A (en) * | 2020-06-03 | 2020-09-08 | 超威电源集团有限公司 | Enhanced antioxidant conductive auxiliary agent, lead-acid storage battery positive lead paste and preparation method |
| CN112186174A (en) * | 2019-07-01 | 2021-01-05 | 中国科学院物理研究所 | Conductive additive and preparation method and application thereof |
| WO2021088167A1 (en) * | 2019-11-04 | 2021-05-14 | 宁德新能源科技有限公司 | Positive electrode and electronic device and electrochemical device including positive electrode |
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| CN1317520A (en) * | 2000-04-11 | 2001-10-17 | 中国科学院物理研究所 | Preparation method of titanium dioxide coated graphite composite particles |
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Application publication date: 20181016 |