CN104508870A - Negative electrode for lithium secondary battery - Google Patents
Negative electrode for lithium secondary battery Download PDFInfo
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- CN104508870A CN104508870A CN201380039082.4A CN201380039082A CN104508870A CN 104508870 A CN104508870 A CN 104508870A CN 201380039082 A CN201380039082 A CN 201380039082A CN 104508870 A CN104508870 A CN 104508870A
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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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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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
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0568—Liquid materials characterised by the solutes
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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
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0569—Liquid materials characterised by the solvents
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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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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0025—Organic electrolyte
- H01M2300/0028—Organic electrolyte characterised by the solvent
- H01M2300/0037—Mixture of solvents
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The present invention is a negative electrode for a lithium secondary battery, said negative electrode being provided with an active-material layer that contains a particulate silicon-based active material and a binder. Said silicon-based active material constitutes more than 50 mass% of the active-material layer, and upon repeating a charge/discharge cycle 20 times using the cell design and charging/discharging conditions given below, the discharge capacity the 20th time is at least 1,500 mAh per gram of the silicon-based active material. <Cell design> Battery: two-pole pouch cell counter electrode: metallic lithium electrolyte: 1 mol/L of LiPF6 dissolved in solvent mixture consisting of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate (with volume ratio of 1:1:1), <charging/discharging conditions> measurement temperature: 30 DEG C, voltage range: 0.01-2 V, and charging current and discharging current: 500 mA per gram of the silicon-based active material
Description
Technical field
The present invention relates to the negative electrode for lithium secondary battery utilizing silicon system particle as active material.
Background technology
In the past, the negative pole of lithium rechargeable battery used the negative pole active material layer of the adhesive containing the emboliform carbon system active materials such as powdered graphite and insulating properties being formed at the surface of the collector body of the foil-like such as Copper Foil.Adhesive uses Kynoar, polytetrafluoroethylene etc.
But, use the discharge capacity of the negative pole of carbon system active material to be at most about 350mAh/g, therefore need the active material of more high power capacity.Therefore, the negative pole using the emboliform silicon system active material instead follow-on active material of carbon system active material is proposed.Known silicon, by the alloying reaction with lithium, demonstrates the discharge capacity of more than the several times of graphite.
But this silicon system active material is large along with the change in volume of discharge and recharge, therefore along with repeated charge, the active material micronizing of silicon system, or depart from from collector body.Therefore, there is the electrical collector of negative pole and active matter quality declines, the problem that the discharge capacity of negative pole reduces significantly.As the method for the decline of the cycle characteristics caused by change in volume when improving this repeated charge, propose by will the polyimides of mechanical characteristic excellence bonding average grain diameter be used to be the method that negative pole is made on surface that active material that the silicon particle of 1 ~ 10 micron is formed is arranged at the collector body be made up of specific Copper Foil in patent documentation 1, propose in patent documentation 2 and use the compound be made up of silicon and carbon as active material, by the negative pole that this active material bonds with polyimides.In addition, the negative pole using polyamidoimide, polyacrylic acid as the adhesive of silicon particle is proposed in non-patent literature 1,2 respectively.
And then the conductivity adhesive linkage having proposed the surface engagement at collector body the adhesive of high concentration in patent documentation 3 is stacked, and is provided with the silicium cathode of the silicon active material layer containing adhesives such as polyimides at the outer surface of this conductivity adhesive linkage.
Prior art document
Patent documentation
Patent documentation 1: patent No. 4471836 specification
Patent documentation 2: No. 2011/056847th, International Publication
Patent documentation 3: patent No. 4212392 specification
Non-patent literature
Non-patent literature 1:Journal of Power Sources 177 (2008) 590-594
Non-patent literature 2:ACS Appl.Mater.Interfaces, 2010,2 (11), 3004-3010
Summary of the invention
But, even if use the negative pole recorded in above-mentioned prior art document, be also difficult to the decline of the discharge capacity suppressed fully along with repeated charge, after needing repeated charge, also maintain the negative pole of high discharge capacity.
Therefore, in the present invention, in order to solve above-mentioned problem, its objective is and provide a kind of when using silicon system active material, even if after repeated charge, also can maintain the lithium ion secondary battery cathode of high discharge capacity.
The present inventor furthers investigate repeatedly in order to solve above-mentioned problem, and its result completes the present invention.That is, purport of the present invention is as described below.
(1) a kind of negative electrode for lithium secondary battery, it is characterized in that, it is the negative electrode for lithium secondary battery of the active material layer be provided with containing emboliform silicon system active material and adhesive, the content of the silicon system active material in active material layer is greater than 50 quality %, under the formation of the battery unit shown in following and discharge and recharge condition, the discharge capacity of the 20th time during repeated charge 20 times is more than 1500mAh/g-silicon system active material.
The formation > of < battery unit
Battery: bipolar system pouch-type battery cell
To electrode: lithium metal
Electrolyte: LiPF
6the mixed solvent (volume ratio 1:1:1) of the ethylene carbonate dissolved with the concentration of 1mol/L, methyl ethyl carbonate and dimethyl carbonate
< discharge and recharge condition >
Measure temperature: 30 DEG C
Voltage range: 0.01 ~ 2V
Charging current and discharging current: 500mA/g-silicon system active material
(2) negative electrode for lithium secondary battery as described in (1), is characterized in that, the porosity of active material layer is 15 ~ 40 volume %, and its electrolyte infiltration rate is less than 300 seconds.
(3) negative electrode for lithium secondary battery as described in (1) or (2), wherein, the duplexer being laminated with active material layer by the outer surface of the conductivity adhesive linkage formed on the collector body of sheet is formed.
(4) negative electrode for lithium secondary battery according to any one of (1) ~ (3), is characterized in that, active material is the particle be made up of silicon monomer.
(5) negative electrode for lithium secondary battery according to any one of (1) ~ (4), is characterized in that, the average grain diameter of silicon system active material is less than 1 μm.
Even if negative pole of the present invention also maintains high discharge capacity after carrying out repeated charge, therefore negative electrode for lithium secondary battery can be used as well.
Accompanying drawing explanation
Fig. 1 is the figure of charging and discharging curve when representing the negative pole using embodiments of the invention 1.
Embodiment
Negative electrode for lithium secondary battery of the present invention is provided with the active material layer containing emboliform silicon system active material and adhesive, and the content of the silicon system active material in active material layer is greater than 50 quality %.Further, under the formation with the battery unit shown in following and discharge and recharge condition, the discharge capacity of the 20th time during repeated charge 20 times is the characteristic of more than 1500mAh/g-silicon system active material.
The formation > of < battery unit
Battery: bipolar system pouch-type battery cell
To electrode: lithium metal
Electrolyte: LiPF
6the mixed solvent (volume ratio 1:1:1) of the ethylene carbonate dissolved with the concentration of 1mol/L, methyl ethyl carbonate and dimethyl carbonate
< discharge and recharge condition >
Measure temperature: 30 DEG C
Voltage range: 0.01 ~ 2V
Charging current and discharging current: 500mA/g-silicon system active material
Here the unit as discharge capacity shows, and " mAh/g-silicon system active material " refers to premised on the situation of the discharge and recharge based on the silicon system active material coordinated in active material layer, by whole values being scaled every gram of silicon system active material of the electricity (mAh) during the electric discharge of measurement.
Above-mentioned discharge capacity is more preferably more than 1700mAh/g, more preferably more than 2000mAh/g.So, the negative electrode for lithium secondary battery of the high discharge capacity of cycle characteristics excellence can be made.
The mensuration of discharge capacity uses the battery unit of known pouch-type (lamination flap-type) to carry out.Battery unit of this battery unit and Coin shape etc. is different, use soft aluminium lamination press mold (stacked film of resin molding and aluminium foil) as the battery unit of exterior material, when being discharge and recharge under electrode does not execute stressed state, measure the battery unit of discharge capacity.The battery unit of this pouch-type can such as make in the following manner.
The negative pole of the sheet obtained is cut out the rectangle into 10mm × 40mm, leaves the active material area of 10mm × 10mm, be coated to deposition film.As to electrode, the lithium plate of thickness 1mm is cut out the rectangle into 30mm × 40mm, nickel down-lead (5mm × 50mm) doubling of thickness 0.5mm is crimped.After only negative pole being put into bag-shaped distance piece (30mm × 20mm), and to electrodes face, obtain electrode group.Distance piece uses the acrylic resin perforated membrane (thickness 25 μm) of rectangle.Cover this electrode group with the aluminium lamination press mold (50mm × 40mm) of the rectangle of two group, after sealing its three limits, in bag-shaped aluminium lamination press mold, inject the electrolyte of 1mL.Electrolyte is used in LiPF in mixed solvent EC, DEC and EMC mixed with volume ratio 1:1:1
6the electrolyte obtained with the dissolving of the concentration of 1 mole/L.Thereafter, by the sealing of a remaining limit, seal in bag-shaped aluminium lamination press mold.In addition, by when sealing in bag-shaped aluminium lamination press mold, one end of negative pole and nickel down-lead is extended to outside, as terminal.So, test cell unit is obtained.These operations are all carried out in the control box of argon atmospher.
The content of the particle (being sometimes abbreviated as below " silicon system particle ") of the silicon system active material in active material layer needs to be greater than 50 quality %, is preferably greater than 60 quality %.If below 50 quality %, even if the discharge capacity then as the silicon system active material every gram of active material is high, discharge capacity when being converted into every gram of active material layer also can decline, and is therefore difficult to obtain the high negative pole of discharge capacity.
As above-mentioned silicon system particle, such as, the particles such as silicon monomer, silicon alloy, silicon silica complex can be enumerated, any shapes such as its shape can be indefinite shape, spherical, threadiness.In these silicon system particles, the discharge capacity of the particle (being sometimes abbreviated as below " silicon particle ") of silicon monomer is the highest, therefore can preferably use.Here, silicon monomer refers to that purity is the crystalloid of more than 95 quality % or amorphous silicon.
The average grain diameter of silicon system particle is preferably less than 5 μm, is more preferably less than 1 μm.Average grain diameter is less, and the surface area of particle is larger, therefore can obtain high discharge capacity.Here, above-mentioned average grain diameter refers to the average grain diameter of the volume reference that such as laser diffraction formula particle size distribution device measures.After this average grain diameter also can use above-mentioned silicon system particle to obtain negative pole, by the SEM image confirming on its surface.
By coordinating adhesive in above-mentioned silicon system particle, above-mentioned silicon system particle being bonded to one another, forming membranaceous active material layer.The kind of adhesive used does not limit, and preferably uses mechanical characteristic excellent, and the polyimides system macromolecule of caking property excellence to silicon system particle.Here, polyimides system macromolecule refers to that main chain has the macromolecule of imide bond.As concrete example, can enumerate polyimides, polyamidoimide, polyesterimide etc., polyimides system macromolecule is not limited to them, as long as the resin that main chain has imide bond then can use any macromolecule.These resins are used alone, but also also mix together two or more usually.
In these polyimides system macromolecules, preferably use the polyimides of especially mechanical characteristic excellence, in polyimides, preferably use aromatic polyimide further.Here aromatic polyimide refers to the polyimides with the structure represented by following general formula (1).
[changing 1]
In general formula (1), R1 is the aromatic residue of 4 valencys, and R2 is the aromatic residue of divalent.
This aromatic polyimide can be thermoplasticity, also can be non-thermal plasticity.As polyimides, the polyimide precursor hot curings such as the polyamic acid by being dissolved in solvent can being used and the polyimides of precursor type, the polyimides of solvent-soluble type that obtain, can preferably use precursor type polyimides.In addition, for the detailed content of precursor type polyimides employing polyamic acid, tell about later.
As above-mentioned polyimides system macromolecule, also commercially available product can be used.Such as, the polyamide acid type varnish such as " U IMIDE AR ", " U IMIDE AH ", " U IMIDE CR ", " U IMIDE CH " (being UNITIKA Inc.) or U VARNISH A (Yu Buxingchan Inc.) can be used, make " RIKACOAT SN-20 " (new Japan Chemical Inc.) or " MATRIMID5218 " (Huntsman Inc.) etc. be dissolved in the polyamidoimide varnish such as solvent-soluble type polyimide varnish, VYLOMAX HR-11NN (Inc. is spun by Japan) of solvent.
From the view point of discharge capacity and cycle characteristics, the high molecular content of polyimides system in above-mentioned active material layer is preferably 5 ~ 30 quality %, is more preferably 15 ~ 25 quality %.By setting by this way, the porosity of active material layer described later can be made to be preferable range, the negative electrode for lithium secondary battery of the high discharge capacity of cycle characteristics excellence can be made.
The porosity of above-mentioned active material layer is preferably 15 ~ 40 volume %, is more preferably 25 ~ 35 volume %.By setting the porosity by this way, can absorb by this pore the stress to active material layer produced due to the change in volume of the discharge and recharge along with silicon active material, therefore can not obtain good cycle characteristics with producing be full of cracks at active material layer during discharge and recharge.Therefore, the porosity, when this scope is outer, cannot obtain the high discharge capacity after as the repeated charge of object sometimes.
The porosity of above-mentioned active material layer is the value calculated by the apparent density of active material layer, the real density (proportion) forming each material (silicon system particle, adhesive, electroconductive particle etc.) of active material layer and use level, changes according to the use level of each material, particle size.Specifically, silicon system particle (real density A g/cm
3) coordinate X quality %, adhesive (real density B g/cm
3) coordinate Y quality %, electroconductive particle (real density C g/cm
3) apparent density that coordinates the active material layer of Z quality % is Dg/cm
3time the porosity (volume %) calculated by following calculating formula.Here, the real density of each material obtains by carrying out measuring based on JIS Z8807.
The porosity (volume %)=100-D (X/A+Y/B+Z/C)
In the present invention, in order to obtain high discharge capacity after charge and discharge cycles, preferably the porosity is set to 15 ~ 40 volume %, and the electrolyte infiltration rate of active material layer is set to less than 300 seconds.Here, electrolyte infiltration rate is preferably less than 200 seconds, more preferably less than 100 seconds.By this electrolyte infiltration rate is set as less than 300 seconds, electrolyte can in the process of repeated charge, more effectively with the surface contact of the silicon system particle as active material, therefore can reach the high discharge capacity after repeated charge.Therefore, when electrolyte infiltration rate is outside this scope, the high discharge capacity after as the repeated charge of object cannot sometimes be obtained.In addition, for the detailed content of electrolyte infiltration rate, tell about later.
Here electrolyte infiltration rate can measure by the following method.That is, by ethylene carbonate (EC), diethyl carbonate (DEC)), methyl ethyl carbonate (EMC) drops to the surface of active material layer with the electrolyte 5 μ L of 20 DEG C that the volume ratio of 1:1:1 coordinates.Then, after electrolyte being dropped to the surface of active material layer, the electrolyte of dropping is completely absorbed to this layer from the surface of active material layer, with the time of visual mensuration drop till the surface of active material layer disappears.The time of this mensuration is set to electrolyte infiltration rate.
In the present invention, the thickness of above-mentioned active material layer is arbitrary, can be set to the thickness of about 10 ~ 300 μm.
In the present invention, in order to reduce the internal resistance of active material layer, preferably in above-mentioned active material layer, contain electroconductive particle.As electroconductive particle, such as, emboliform material with carbon element, metal material can be used.As material with carbon element, be preferably graphite, carbon black, be more preferably graphite.As metal material, such as, silver, copper, nickel can be used.As the particle diameter of these carbon particles, metallic, preferred average grain diameter is less than 5 μm.
The content of the electroconductive particle in above-mentioned active material layer is preferably 1 ~ 30 quality %, is more preferably 5 ~ 25 quality %.
Negative pole of the present invention is preferably provided with the duplexer of conductivity adhesive linkage between above-mentioned active material layer and the collector body of sheet.Thus, can relax along with the expansion of active material layer during discharge and recharge and contraction and the stress produced at the interface of active material layer and collector body, and inhibit activities material layer is peeled off from collector body.
Above-mentioned conductivity adhesive linkage is layer adhesive being coordinated to electroconductive particle.The kind of adhesive used herein does not limit, and such as, preferably can use above-mentioned polyimides system macromolecule.In polyimides system macromolecule, the particularly preferably polyamidoimide of adhesion properties excellence, the polyimides of solvent-soluble type of the collector body such as use and Copper Foil.Here polyamidoimide refers to the polyamidoimide with the structure represented by following general formula (2).
[changing 2]
In general formula (2), R3 is the aromatic residue of 3 valencys, and R4 is the aromatic residue of divalent.Adhesive in conductive adhesive layer can be that identical type also can be different from the adhesive in above-mentioned active material layer.
As the electroconductive particle used in above-mentioned conductivity adhesive linkage, such as, emboliform material with carbon element, metal material can be used.As material with carbon element, be preferably graphite, carbon black, be more preferably graphite.
As metal material, such as, silver, copper, nickel can be used.As the particle diameter of these carbon particles, metallic, preferred average grain diameter is less than 5 μm.These electroconductive particles can be that identical type also can be different from the electroconductive particle that above-mentioned active material layer coordinates.
The content of the adhesive in preferred above-mentioned conductivity adhesive linkage is less than 30 quality %, namely the content of electroconductive particle is more than 70 quality %, the content of the adhesive more preferably in above-mentioned conductivity adhesive linkage is less than 20 quality %, and namely the content of electroconductive particle is more than 80 quality %.
If the content using adhesive is more than 30 quality %, namely the content of electroconductive particle is less than the conductivity adhesive linkage of 70 quality %, be then difficult to make the porosity of active material layer be 15 ~ 40 volume % and make electrolyte infiltration rate be less than 300 seconds.Such as, be with regard to the negative pole of 80 quality % with regard to the polyimide content in the conductivity adhesive linkage recorded in the embodiment 1 of patent documentation 3, in the research of the present inventor etc., the electrolyte infiltration rate of active material layer is more than 1000 seconds.Its reason it be unclear that, but can confirm to have nothing to do with the adhesive kind in adhesive linkage, along with the content of adhesive uprises, the infiltration rate of the electrolyte of active material layer is slack-off, therefore thinks that the electrolyte infiltration rate of the formation of conductivity adhesive linkage on active material layer is without any impact.
In addition, amount of binder in conductivity adhesive linkage is relatively few, by the electroconductive particles such as the graphite of the dilation by almost not having volume with the adhesives of active material layer with the content of degree, and the collector body such as use and Copper Foil has the adhesive of high cementability, also can obtain the sufficient intensity as conductivity adhesive linkage.
From the view point of the conductivity between collector body and active material layer and cementability, the thickness of conductivity adhesive linkage is preferably 1 ~ 15 μm, is more preferably 2 ~ 5 μm.
As collector body, such as, the metal formings such as Copper Foil, stainless steel foil, nickel foil can be used, preferably use the Copper Foil as electrolytic copper foil, rolled copper foil and so on.The thickness of metal forming is preferably 5 ~ 50 μm, is more preferably 9 ~ 18 μm.In order to improve the cementability of metal forming and conductivity adhesive linkage, roughened process, antirust treatment can be implemented to the surface of metal forming.
Negative electrode for lithium secondary battery of the present invention such as manufactures simply by following operation.
1st operation: coordinate graphite particle and obtain graphite dispersion (conductivity adhesive linkage formation coating) in polyamideimide solution.
2nd operation: graphite dispersion is coated after on Copper Foil, dry, obtain conductive coat.
3rd operation: coordinate silicon particle and graphite particle and obtain silicon dispersion (active material layer formation coating) in polyimide precursor solution.
4th operation: silicon dispersion is coated after on conductive coat, dry, obtain containing silicon coating film.
5th operation: by heat-treating containing silicon coating film, polyimide precursor hot curing is transformed to polyimides.
By said method, the negative pole stacking gradually collector body, the conductivity adhesive linkage containing graphite particle and polyamidoimide and the active material layer containing silicon particle, graphite particle and polyimides easily can be manufactured.
Baking temperature in 2nd operation (conductive coat formation process) is preferably less than 200 DEG C, is more preferably less than 150 DEG C.From the view point of drying efficiency, the baking temperature in the 2nd operation (conductive coat formation process) is preferably more than 100 DEG C.
In 2nd operation, preferably conductive coat is dried to the degree of the solvent used in graphite dispersion residual about 5 ~ 30 quality % in conductive coat.This residual solvent contributes to the embodiment of the good adhesive strength of conductivity adhesive linkage and active material layer.
Baking temperature in 4th operation (active material film formation process) is preferably less than 200 DEG C, is more preferably less than 150 DEG C.From the view point of drying efficiency, the baking temperature in the 4th operation (active material film formation process) is preferably more than 100 DEG C.
Do not produce fire damage from anticathode, the aspect being transformed to polyimides containing the polyimide precursor in silicon coating film fully can be considered, the heat treatment temperature of the 5th operation is preferably 250 ~ 500 DEG C.Heat treatment is preferably carried out under the non-active gas atmosphere such as nitrogen, but also can carry out in atmosphere or under vacuum.In addition, also hot pressurized treatments can be carried out as required after heat treatment.
The coating of each dispersion of the 2nd operation and the 4th operation only can carry out 1 time, also can be divided into and repeatedly carrying out.
As electric conducting material dispersion being coated the method for collector body and active substance dispersion being coated the method for conductive coat, the either method in the method be coated with continuously by the mode of volume to volume, the method be coated with in the mode of sheet can be used.As apparatus for coating, such as, mould can be used to be coated with machine, multilayer film is coated with machine, gravure coater, comma coating machine, reverse roll coater, blade coating machine.
Polyamideimide solution can use commercially available product described above, but preferably uses and approximately wait a mole cooperation using as the trimellitic anhydride of raw material and vulcabond, makes it carry out polymerization reaction in a solvent and the solution that obtains.
As trimellitic anhydride, also can to use one aliquot replacement be pyromellitic dianhydride, the compound of benzophenone tetracarboxylic acid anhydride, biphenyl tetracarboxylic acid anhydrides.
As vulcabond, such as, m-benzene diisocyanate, PPDI, 4 can be used, 4 '-methyl diphenylene diisocyanate, 4,4 '-diphenyl ether diisocyanate, diphenyl sulphone (DPS)-4,4 '-vulcabond, diphenyl-4,4 '-vulcabond, o-tolidine vulcabond, 2,4-toluene di-isocyanate(TDI), 2,6-toluene di-isocyanate(TDI)s, XDI, naphthalene diisocyanate.They may be used singly or in combination of two or more.Among these, be preferably 4,4 '-methyl diphenylene diisocyanate.
The solid component concentration of the polyamidoimide in polyamideimide solution is preferably 1 ~ 50 quality %, is more preferably 10 ~ 30 quality %.
Viscosity in 30 DEG C of polyamideimide solution is preferably 1 ~ 150Pas, is more preferably 5 ~ 100Pas.
Polyimide precursor solution can use commercially available product described above, also preferably uses and approximately waits a mole cooperation using as the tetracarboxylic dianhydride of raw material and diamines, make it carry out polymerization reaction in a solvent and obtain polyamic acid.
As tetracarboxylic dianhydride, such as, PMA can be used, 3, 3 ', 4, 4 '-bibenzene tetracarboxylic, 3, 3 ', 4, 4 '-benzophenone tetracarboxylic, 3, 3 ', 4, 4 '-diphenyl sulfone tetraformic acid, 3, 3 ', 4, 4 '-diphenyl ether tetracarboxylic acid, 2, 3, 3 ', 4 '-benzophenone tetracarboxylic, 2, 3, 6, 7-naphthalenetetracarbacidic acidic, 1, 4, 5, 7-naphthalenetetracarbacidic acidic, 1, 2, 5, 6-naphthalenetetracarbacidic acidic, 3, 3 ', 4, 4 '-diphenyl methane tetracarboxylic acid, 2, 2-two (3, 4-dicarboxyphenyi) propane, 2, 2-two (3, 4-dicarboxyphenyi) HFC-236fa, 3, 4, 9, 10-tetra-Suo Ji perylene, 2, two [the 4-(3 of 2-, 4-di carboxyl phenyloxy) phenyl] propane, 2, two [the 4-(3 of 2-, 4-di carboxyl phenyloxy) phenyl] dianhydride of HFC-236fa etc.They may be used singly or in combination of two or more.Among these, be preferably PMA, 3,3 ', 4,4 '-bibenzene tetracarboxylic.
As diamines, such as, p-phenylenediamine (PPD) can be used, m-phenylene diamine (MPD), 3,4 '-diamino-diphenyl ether, 4,4 '-diamino-diphenyl ether, 4,4 '-diaminodiphenyl-methane, 3,3 '-dimethyl-4,4 '-diaminodiphenyl-methane, two [4-(4-amino-benzene oxygen) phenyl] propane of 2,2-, two (anilino-) ethane of 1,2-, diamino-diphenyl sulfone, diaminobenzene formailide, diaminobenzoic acid ester, diamino diphenyl sulfide, two (p-aminophenyl) propane of 2,2-, two (p-aminophenyl) HFC-236fa of 2,2-, 1,5-diaminonaphthalene, diaminotoluene, the borontrifluoride benzene of diaminourea, Isosorbide-5-Nitrae-bis-(p-aminophenyl oxygen base) benzene, 4,4 '-bis-(p-aminophenyl oxygen base) biphenyl, diamino-anthraquinone, 4,4 '-bis-(3-aminophenoxy phenyl) diphenyl sulphone (DPS), two (anilino-) HFC-236fa of 1,3-, Isosorbide-5-Nitrae-bis-(anilino-) octafluorobutane, two (anilino-) Decafluoropentane of 1,5-, 1,7-two (anilino-) ten tetrafluoro heptane.They may be used singly or in combination of two or more.Among these, be preferably p-phenylenediamine (PPD), 4,4 '-diamino-diphenyl ether, 2,2-two [4-(4-amino-benzene oxygen) phenyl] propane.
As the solid component concentration of the polyamic acid in polyimide precursor solution, be preferably 1 ~ 50 quality %, be more preferably 5 ~ 25 quality %.The polyamic acid contained in polyimide precursor solution also can partly imidizate.
Viscosity in 30 DEG C of polyimide precursor solution is preferably 1 ~ 150Pas, is more preferably 10 ~ 100Pas.
As the solvent used in polyamideimide solution, polyimide precursor solution, as long as the solvent of solubilized polyamidoimide, polyamic acid, there is no particular limitation, preferably uses acid amides series solvent.As acid amides series solvent, such as, METHYLPYRROLIDONE (NMP), DMF (DMF), DMA (DMAc) can be enumerated.They may be used singly or in combination of two or more.
The known additive as various surfactant, organo silane coupling agent can be added as required in polyamideimide solution, polyimide precursor solution in the scope not damaging effect of the present invention.In addition, also other polymer except polyamidoimide, polyimide precursor can be added as required in polyamideimide solution, polyimide precursor solution in the scope not damaging effect of the present invention.
Embodiment
Below, explain embodiments of the invention, but the present invention is not limited to these embodiments.
The mensuration of the various characteristic value in embodiment and comparative example and evaluate as described below.
(I) porosity of active material layer and electrolyte infiltration rate
For the porosity and the electrolyte infiltration rate of active material layer, measured by said method.
(II) flash-over characteristic of silicon system active material layer
First, using the negative pole of the sheet of gained, making the test cell unit of bipolar system pouch-type battery cell (laminated cell unit) as the discharge capacity for measuring negative pole by the following method.
The negative pole of the sheet obtained is cut out the rectangle into 10mm × 40mm, leaves the active material area of 10mm × 10mm, be coated to deposition film.As to electrode, the lithium plate of thickness 1mm is cut out the rectangle into 30mm × 40mm, nickel down-lead (5mm × 50mm) doubling of thickness 0.5mm is crimped.After only negative pole being put into bag-shaped distance piece (30mm × 20mm), and to electrodes face, obtain electrode group.Distance piece uses the acrylic resin perforated membrane (thickness 25 μm) of rectangle.Cover this electrode group with the aluminium lamination press mold (50mm × 40mm) of the rectangle of two group, after sealing its three limits, in bag-shaped aluminium lamination press mold, inject the electrolyte of 1mL.Electrolyte is used in LiPF in mixed solvent EC, DEC and EMC mixed with volume ratio 1:1:1
6the electrolyte obtained with the dissolving of the concentration of 1 mole/L.Thereafter, by the sealing of a remaining limit, seal in bag-shaped aluminium lamination press mold.In addition, by when sealing in bag-shaped aluminium lamination press mold, one end of negative pole and nickel down-lead is extended to outside, as terminal.So, test cell unit is obtained.These operations are all carried out in the control box of argon atmospher.
Then, use the test cell unit obtained, according to above-mentioned < discharge and recharge condition > repeated charge, obtain the discharge capacity of the 20th time.
The preparation method of the binder solution, active material layer formation silicon dispersion and the conductivity adhesive linkage formation graphite dispersion that use in embodiment and comparative example is as described below.
[preparation of polyimide precursor solution]
Make approximately equimolar 3,3 ', 4,4 '-bibenzene tetracarboxylic dianhydride (BPDA) and 4,4 '-oxygen diphenylamines (ODA) reacts in NMP, obtains being 20 quality % as the solid component concentration of polyimides and is the uniform polyamic acid solution (P-1) of 25Pas the viscosity of 30 DEG C.
[preparation of polyamideimide solution]
Make about equimolar trimellitic anhydride (TMA) and 4,4 '-methyl diphenylene diisocyanate (DMI) reacts in NMP, obtains solid component concentration and is 18 quality % and is the uniform polyamideimide solution (P-2) of 15Pas the viscosity of 30 DEG C.
[active material layer forms the preparation by silicon dispersion]
In solution obtained above (P-1), with the composition shown in table 1, to add average grain diameter be the silicon particle (purity: 99 quality %) of 0.7 μm and average grain diameter is the graphite particle of 3 μm, after stirring in the mode of disperseing equably, add NMP.So, the silicon dispersion (solid component concentration about 25 quality %) with the composition shown in table 1 is obtained.
[table 1]
< active material layer forms the composition > by silicon dispersion
[conductivity adhesive linkage forms the preparation by electroconductive particle dispersion]
In solution obtained above (P-1) or solution (P-2), add with the composition shown in table 2 graphite particle or the carbon black (Ketjen black) that average grain diameter is 3 μm, after stirring in the mode of disperseing equably, add NMP.So, the electroconductive particle dispersion a1 ~ a10 (solid component concentration about 30 quality %) with the composition shown in table 2 is obtained.
[table 2]
The composition > of < electroconductive particle dispersion
[table 3]
< cathode property >
< embodiment 1 >
After the surface of the side of the electrolytic copper foil (Furukawa Electric Industrial Co., Ltd system, F2-WS) of thickness 18 μm uses bar coater with the mode of sheet equably applying conductive particle dispersion a1,130 DEG C of dryings 10 minutes, obtain conductive coat.The coating weight of graphite dispersion is prepared by the mode being 3 ~ 4 μm with the thickness of the conductive adhesion layer of gained.Then, use on the surface of conductive coat bar coater with the mode of sheet silicon-coating dispersion A1 equably, 130 DEG C of dryings 10 minutes, obtain active material film.The coating weight of silicon dispersion is prepared by the mode being 40 ~ 50 μm with the thickness of the active material layer of gained.So, the duplexer stacking gradually electrolytic copper foil, conductive coat and active material film is obtained.Then, after the duplexer of gained was warming up to 350 DEG C with 2 hours from 100 DEG C in a nitrogen atmosphere, the heat treatment of 1 hour is carried out at 350 DEG C.By this heat treatment, the polyamic acid in active material film is transformed to polyimides.So, the negative pole A1a1 stacking gradually electrolytic copper foil, conductivity adhesive linkage and active material layer is obtained.The characteristic of this negative pole is shown in table 3.
In addition, the 1st time during the charge and discharge cycles of this negative pole, the 5th, the 10th time and the 20th time charging and discharging curve be shown in Fig. 1.As shown in Figure 1, only can obtain high discharge capacity the 1st time, in the repeated charge of the 20th time after the 2nd time, although charging and discharging curve has fluctuation, because the decline of the discharge capacity of negative pole repeatedly caused is slight.
< embodiment 2 ~ 5 >
Except changing to except electroconductive particle dispersion a2 ~ a5 by electroconductive particle dispersion a1, obtain negative pole A1a2 ~ A1a5 by method similarly to Example 1.The characteristic of this negative pole is shown in table 3.In these negative poles, charging and discharging curve also illustrates the trend same with negative pole A1a1.
< embodiment 6 ~ 7 >
Except changing to except silicon dispersion A2 ~ A3 by silicon dispersion A1, obtain negative pole A2a1 ~ A3a1 by method similarly to Example 1.The characteristic of this negative pole is shown in table 3.In these negative poles, charging and discharging curve also illustrates the trend same with negative pole A1a1.
< comparative example 1 ~ 5 >
Except changing to except electroconductive particle dispersion a6 ~ a10 by electroconductive particle dispersion a1, obtain negative pole A1a6 ~ A1a10 by method similarly to Example 1.The characteristic of this negative pole is shown in table 3.In these negative poles, along with repeated charge, discharge capacity declines significantly, and the discharge capacity of the 20th time is low to moderate and is less than 1000mAh/g-silicon system active material.
< comparative example 6 >
Except changing to except silicon dispersion A4 by silicon dispersion A1, obtain negative pole A4a1 by method similarly to Example 1.The characteristic of this negative pole is shown in table 3.In this negative pole, the value of the discharge capacity of the 20th time display 1500mAh/g-silicon system active material, but the content of silicon system active material in active material layer is low to moderate 45 quality %, and the discharge capacity therefore as negative pole is low.
As mentioned above, the negative pole of embodiments of the invention has high discharge capacity, and excellent charge/discharge cycle characteristics, therefore can be used as the negative pole of secondary lithium batteries well.
Claims (5)
1. a negative electrode for lithium secondary battery, is characterized in that, is the negative electrode for lithium secondary battery of the active material layer be provided with containing emboliform silicon system active material and adhesive,
The content of the silicon system active material in active material layer is greater than 50 quality %,
Under the formation of the battery unit shown in following and discharge and recharge condition, the discharge capacity of the 20th time during repeated charge 20 times is more than 1500mAh/g-silicon system active material,
The formation > of < battery unit
Battery: bipolar system pouch-type battery cell,
To electrode: lithium metal,
Electrolyte: LiPF
6the mixed solvent (volume ratio 1:1:1) of the ethylene carbonate dissolved with the concentration of 1mol/L, methyl ethyl carbonate and dimethyl carbonate,
< discharge and recharge condition >
Measure temperature: 30 DEG C,
Voltage range: 0.01 ~ 2V,
Charging current and discharging current: 500mA/g-silicon system active material.
2. negative electrode for lithium secondary battery as claimed in claim 1, it is characterized in that, the porosity of active material layer is 15 ~ 40 volume %, and its electrolyte infiltration rate is less than 300 seconds.
3. negative electrode for lithium secondary battery as claimed in claim 1 or 2, wherein, the duplexer being laminated with active material layer by the outer surface of the conductivity adhesive linkage formed on the current collector is formed.
4. the negative electrode for lithium secondary battery according to any one of claims 1 to 3, is characterized in that, active material is the particle be made up of silicon monomer.
5. the negative electrode for lithium secondary battery according to any one of Claims 1 to 4, is characterized in that, the average grain diameter of silicon system active material is less than 1 μm.
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| JP2012163737 | 2012-07-24 | ||
| JP2012-163737 | 2012-07-24 | ||
| PCT/JP2013/069978 WO2014017506A1 (en) | 2012-07-24 | 2013-07-24 | Negative electrode for lithium secondary battery |
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| JP6955660B2 (en) * | 2014-05-09 | 2021-10-27 | ユニチカ株式会社 | Power storage element |
| KR102602374B1 (en) * | 2015-05-04 | 2023-11-16 | 바스프 코포레이션 | Electrochemical hydrogen storage electrodes and cells |
| PL3306734T3 (en) * | 2016-03-30 | 2019-08-30 | Lg Chem, Ltd. | Lithium secondary battery production method |
| JP6689512B2 (en) * | 2016-03-30 | 2020-04-28 | エルジー・ケム・リミテッド | Method for manufacturing lithium secondary battery |
| JP2019535107A (en) * | 2016-10-05 | 2019-12-05 | ワッカー ケミー アクチエンゲゼルシャフトＷａｃｋｅｒ Ｃｈｅｍｉｅ ＡＧ | Lithium ion battery |
| KR102631899B1 (en) * | 2018-08-10 | 2024-01-30 | 주식회사 엘지화학 | Lithium Secondary Battery Comprising Si Anode and Method of Making the Same |
| CN113690481B (en) * | 2019-07-10 | 2022-08-05 | 宁德时代新能源科技股份有限公司 | Lithium ion battery and electric equipment comprising same |
| CN115148955A (en) * | 2021-03-29 | 2022-10-04 | 北京小米移动软件有限公司 | Negative pole piece and manufacturing method thereof, battery cell, battery and electronic equipment |
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| JP2004200011A (en) * | 2002-12-19 | 2004-07-15 | Mitsubishi Materials Corp | Cathode for lithium-ion secondary battery and lithium-ion secondary battery manufactured using the cathode |
| JP2007123141A (en) * | 2005-10-31 | 2007-05-17 | Sony Corp | Anode and battery |
| CN100431202C (en) * | 2002-02-26 | 2008-11-05 | 日本电气株式会社 | Negative electrode for secondary cell,secondary cell, and method for producing negative electrode for secondary cell |
| CN102460782A (en) * | 2009-05-07 | 2012-05-16 | 安普雷斯股份有限公司 | Electrode including nanostructures for rechargeable cells |
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| JPS57123653A (en) * | 1981-01-23 | 1982-08-02 | Matsushita Electric Ind Co Ltd | Manufacture of alkaline manganese battery |
| WO1998028804A1 (en) * | 1996-12-24 | 1998-07-02 | Kao Corporation | Nonaqueous electrolyte secondary battery |
| JP4366101B2 (en) * | 2003-03-31 | 2009-11-18 | キヤノン株式会社 | Lithium secondary battery |
| JP4952680B2 (en) * | 2008-08-05 | 2012-06-13 | ソニー株式会社 | Lithium ion secondary battery and negative electrode for lithium ion secondary battery |
| JP6056845B2 (en) * | 2012-02-13 | 2017-01-11 | 日本電気株式会社 | Method for producing negative electrode for lithium secondary battery |
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- 2013-07-24 CN CN201380039082.4A patent/CN104508870B/en active Active
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100431202C (en) * | 2002-02-26 | 2008-11-05 | 日本电气株式会社 | Negative electrode for secondary cell,secondary cell, and method for producing negative electrode for secondary cell |
| JP2004200011A (en) * | 2002-12-19 | 2004-07-15 | Mitsubishi Materials Corp | Cathode for lithium-ion secondary battery and lithium-ion secondary battery manufactured using the cathode |
| JP2007123141A (en) * | 2005-10-31 | 2007-05-17 | Sony Corp | Anode and battery |
| CN102460782A (en) * | 2009-05-07 | 2012-05-16 | 安普雷斯股份有限公司 | Electrode including nanostructures for rechargeable cells |
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| JPWO2014017506A1 (en) | 2016-07-11 |
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| CN104508870B (en) | 2017-09-22 |
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