CN108963339A - Electrolyte of lithium-ion secondary battery, lithium ion secondary battery - Google Patents
Electrolyte of lithium-ion secondary battery, lithium ion secondary battery Download PDFInfo
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- CN108963339A CN108963339A CN201810695651.5A CN201810695651A CN108963339A CN 108963339 A CN108963339 A CN 108963339A CN 201810695651 A CN201810695651 A CN 201810695651A CN 108963339 A CN108963339 A CN 108963339A
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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
- H01M10/0567—Liquid materials characterised by the additives
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
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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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- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
The present invention provides a kind of electrolyte of lithium-ion secondary battery, the electrolyte includes non-aqueous organic solvent, lithium salts and additive, wherein, the non-aqueous organic solvent comprises the following structure fluorine ether shown in formula I, and the additive comprises the following structure phosphoric acid cyclic anhydride shown in formula II:In structural formula I, Af1It is 2~3 containing fluoroalkyl, Af selected from carbon atom number2It is 2~4 containing fluoroalkyl selected from carbon atom number；In structural formula II, A1、A2、A3Independently selected from alkyl, contain one of fluoroalkyl, allyl, phenyl.
Description
Technical field
The invention belongs to technical field of lithium ion more particularly to a kind of electrolyte of lithium-ion secondary battery and a kind of lithium
Ion secondary battery.
Background technique
Lithium ion secondary battery is the most competitive battery of a new generation, is to solve to work as referred to as " the environmentally protective energy "
For the one preferred technique of problem of environmental pollution and energy problem.In recent years, lithium ion secondary battery has taken in high-energy battery field
Immense success was obtained, but consumer still it is expected that the higher battery of comprehensive performance emerges, and this is depended on to new electrode material
With the research and development of electrolyte system.Energy density of the electronic digitals such as smart phone, tablet computer product to battery at present
It is required that it is higher and higher, so that commercial li-ion secondary cell is difficult to meet the requirements.Promoted battery energy density can by with
Lower two ways: first is that the positive and negative pole material of selection high capacity and high-pressure solid；Second is that improving the operating voltage of battery.
Pure silicon cathode theory gram volume is up to 4200mAh/g, the cathode as lithium ion secondary battery, since volume is imitated
It answers, cell expansion and pole piece dusting are serious, poor circulation.People's consideration is compound by silicon materials and carbon material, and it is multiple to form silicon-carbon
Condensation material can largely improve the specific capacity of material, while can reduce the volume of silica-base material to a certain extent
Effect.For Si-C composite material with the nickelic anode collocation of high capacity, energy density can reach 300Wh/Kg or more, multiple with silicon-carbon
The condensation material electrolyte that nickelic system matches of arranging in pairs or groups also comes into being, and becomes the heat of electrolyte of lithium-ion secondary battery research
Point.
While positive electrode charging voltage improves, the oxygenolysis phenomenon of electrolyte can aggravate, so as to cause battery
The deterioration of performance.In addition, battery in use generally existing cathode metal Ion release the phenomenon that, especially battery is passing through
After crossing prolonged high-temperature storage, the dissolution of cathode metal ion is further exacerbated by, and causes the holding capacity of battery relatively low.It causes
The factor of these problems mainly has: (1) oxygenolysis of electrolyte.Under high voltages or nickelic positive system, positive-active
The oxidation activity of material is higher, so that its reactivity between electrolyte increases.Under high temperature, high-voltage anode or it is nickelic just
Reaction between pole and electrolyte is further exacerbated by, and the oxidative degradation products of electrolyte is caused constantly to deposit in positive electrode surface, bad
Positive electrode surface characteristic is changed, the internal resistance of battery and thickness is caused constantly to increase.(2) digestion of metallic ion of positive active material with
Reduction.On the one hand, at high temperature, the LiPF in electrolyte6It is easy to decompose, generates HF and PF5.Wherein HF can corrode anode, lead
Cause the dissolution of metal ion causes capacity to be lost to destroy cathode material structure；On the other hand, under high voltages, electrolyte
It is easy to be oxidized in anode, the metal ion of positive active material is caused to be easy to be reduced and dissolve out in electrolyte, thus broken
Bad cathode material structure leads to capacitance loss.Meanwhile the metal ion of electrolyte is arrived in dissolution, easily propagates through diaphragm and reaches cathode
Electron reduction is obtained into metal simple-substance, to destroy the structure of SEI, cathode impedance is caused to be continuously increased, self-discharge of battery adds
Play, irreversible capacity increase, penalty.
Fluorinated ethylene carbonate can form uniform and stable SEI film on silicon-carbon cathode surface, due to silicon-carbon cathode material
Particularity, generally require film for additive more more than graphite cathode system in electrolyte system, it usually needs using big
The fluorinated ethylene carbonate of amount, due to fluorinated ethylene carbonate in the high temperature environment or nickelic positive battery system be easy point
Solution is unable to satisfy battery high-temperature requirement etc., fluorinated ethylene carbonate is used alone, there are various disadvantages.To understand
Certainly flatulence problem of the lithium ion secondary battery containing fluorinated ethylene carbonate during high temperature storage, CN201110157665
By adding organic dinitrile material (NC- (CH in the electrolytic solution2)n- CN, wherein n=2~4) method inhibit flatulence.
US2008/0311481Al discloses ether/aryl compound of the itrile group containing there are two, improves battery under high voltage and hot conditions
Inflatable, improve high-temperature storage performance.But nitrile compounds are applied to the nickelic positive electrode system of ternary without improvement effect.
Summary of the invention
The purpose of the present invention is to provide a kind of electrolyte of lithium-ion secondary battery, it is intended to solve existing lithium ion secondary
Battery is under high temperature and/or high pressure operations, and electrolyte oxidation decomposes, cathode metal Ion release aggravates, and leads to battery
The problem of cycle performance, high-temperature storage performance and low temperature performance difference.
One aspect of the present invention provides a kind of lithium ion secondary battery containing electrolyte of lithium-ion secondary battery of the present invention.
For achieving the above object, The technical solution adopted by the invention is as follows:
A kind of electrolyte of lithium-ion secondary battery, the electrolyte include non-aqueous organic solvent, lithium salts and additive,
In, the non-aqueous organic solvent comprises the following structure fluorine ether shown in formula I, and the additive comprises the following structure shown in formula II
Phosphoric acid cyclic anhydride:
In structural formula I, Af1It is 2~3 containing fluoroalkyl, Af selected from carbon atom number2Selected from carbon atom number be 2~4 it is fluorine-containing
Alkyl；
In structural formula II, A1、A2、A3Independently selected from alkyl, contain one of fluoroalkyl, allyl, phenyl.
Preferably, in structural formula II, the alkyl is selected from methyl, ethyl, propyl, and at least one in isopropyl, isobutyl group
Kind.
Preferably, in structural formula II, it is described containing fluoroalkyl in trifluoromethyl, trifluoroethyl, hexafluoro isopropyl extremely
Few one kind.
It preferably, is the mass percentage of fluorine ether shown in structural formula I in terms of 100% by the gross mass of the electrolyte
It is 5%~35%.
It preferably, is the quality percentage of phosphoric acid cyclic anhydride shown in structural formula II in terms of 100% by the gross mass of the electrolyte
Content is 0.01%~2%.
Preferably, the non-aqueous organic solvent further includes ethylene carbonate, propene carbonate, butylene, carbonic acid two
Methyl esters, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, third
Acetoacetic ester, propyl propionate, methyl butyrate, ethyl butyrate, gamma-butyrolacton, gamma-valerolactone, δ-valerolactone, in 6-caprolactone extremely
Few one kind.
It preferably, is in terms of 100% by the gross mass of the electrolyte, the mass percentage of the non-aqueous organic solvent is
55%~75%.
And a kind of lithium ion secondary battery, the lithium ion secondary battery include anode, cathode, diaphragm and electrolyte,
And the electrolyte is electrolyte of lithium-ion secondary battery of the present invention.
Preferably, the active material of the anode is transition metal oxide；The active material of the cathode is graphite, contains
The composite material or lithium titanate of Si.
Preferably, the transition metal oxide is LiNixCoyMnzL(1-x-y-z)O2, wherein L Al, Sr, Mg, Ti,
The value of one of Ca, Zr, Zn, Si and Fe, x, y, z meet: 0≤x <, 1,0 < y≤1,0≤z < 1, and 0 < x+y+z≤
1。
Containing fluorine ether shown in structural formula I in electrolyte of lithium-ion secondary battery provided by the invention, the fluorine ether is used as
Electrolyte solvent reduces the side reaction of electrolyte and electrode interface, it is suppressed that the heat production of electrode interface and production gas improve electricity
The pressure-resistant stability of liquid is solved, so as to improve the high-temperature storage and cycle performance of lithium ion secondary battery.Further, lithium of the present invention
Containing phosphoric acid cyclic anhydride shown in structural formula II in ion secondary battery electrolyte, the phosphoric acid cyclic anhydride of above structure can be in electrode table
Face forms low-impedance protective film, inhibits the side reaction of electrode and electrolyte, reduces interface impedance, the comprehensive output for promoting battery
Performance.In addition, the presence of above-mentioned phosphoric acid cyclic anhydride compound, can improve the low temperature discharge property containing the dicyandiamide solution compared with Polyfluoroether
Energy.
In addition, the fluorine ether compares carbonate solvent system, it is not easy to flash burn, it is low with electrode interface reactivity, and contain
After the cyclic phosphate acid anhydride additive of ignition-proof element P is used in combination, there is certain flame retardant effect, to improve lithium to a certain extent
The security performance of ion secondary battery.
To sum up, electrolyte of lithium-ion secondary battery provided by the invention can improve high-nickel material (or positive-active material
Material under high voltages) stability, inhibit nonaqueous electrolytic solution in positive electrode surface oxygenolysis, improve nickelic system or high voltage
Under the conditions of lithium ion battery chemical property.
Lithium ion secondary battery provided by the invention can due to containing electrolyte of lithium-ion secondary battery of the invention
Improve cycle performance, high-temperature storage performance and the low temperature performance of lithium ion secondary battery.
Specific embodiment
In order to which technical problems, technical solutions and advantageous effects to be solved by the present invention are 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 used to explain
The present invention is not intended to limit the present invention.
In the description of the present invention, it is to be understood that, term " first ", " second " are used for description purposes only, and cannot
It is interpreted as indication or suggestion relative importance or implicitly indicates the quantity of indicated technical characteristic.Define as a result, " the
One ", the feature of " second " can explicitly or implicitly include one or more of the features.In the description of the present invention,
The meaning of " plurality " is two or more, unless otherwise specifically defined.
The embodiment of the invention provides a kind of electrolyte of lithium-ion secondary battery, the electrolyte includes non-aqueous organic molten
Agent, lithium salts and additive, wherein the non-aqueous organic solvent comprises the following structure fluorine ether shown in formula I, and the additive includes
Phosphoric acid cyclic anhydride shown in following structural formula II:
In structural formula I, Af1It is 2~3 containing fluoroalkyl, Af selected from carbon atom number2Selected from carbon atom number be 2~4 it is fluorine-containing
Alkyl；
In structural formula II, A1、A2、A3Independently selected from alkyl, contain one of fluoroalkyl, allyl, phenyl.
Contain fluorine ether shown in structural formula I, the fluorine in electrolyte of lithium-ion secondary battery provided in an embodiment of the present invention
Ether is used as electrolyte solvent, reduces the side reaction of electrolyte and electrode interface, it is suppressed that the heat production of electrode interface and production gas mention
The pressure-resistant stability of electrolyte is risen, so as to improve the high-temperature storage and cycle performance of lithium ion secondary battery.
It further, include structural formula II in the additive in electrolyte of lithium-ion secondary battery of the embodiment of the present invention
Shown in phosphoric acid cyclic anhydride, the phosphoric acid cyclic anhydride of above structure can form low-impedance protective film in electrode surface, inhibit electrode and
The side reaction of electrolyte reduces interface impedance, the comprehensive output performance for promoting battery.In addition, above-mentioned phosphoric acid cyclic anhydride compound
In the presence of, can improve containing compared with Polyfluoroether dicyandiamide solution low temperature performance.
In addition, the fluorine ether compares carbonate solvent system, it is not easy to flash burn, it is low with electrode interface reactivity, and contain
After the cyclic phosphate acid anhydride additive of ignition-proof element P is used in combination, there is certain flame retardant effect, to improve lithium to a certain extent
The security performance of ion secondary battery.
To sum up, it is provided in an embodiment of the present invention using fluorine ether shown in structural formula I as non-aqueous organic solvent ingredient, with structure formula
Electrolyte of lithium-ion secondary battery of the phosphoric acid cyclic anhydride as additive component shown in II can improve high-nickel material (or just
Pole active material is under high voltages) stability, inhibit nonaqueous electrolytic solution in positive electrode surface oxygenolysis, improve nickelic system or
The chemical property of lithium ion battery under person's high voltage condition.
In the embodiment of the present invention, in fluorine ether structure shown in structural formula I, Af1It is 2~3 containing fluothane selected from carbon atom number
Base, Af2It is 2~4 containing fluoroalkyl selected from carbon atom number.Specifically, the Af containing fluoroalkyl that carbon atom number is 2~31It can be alkane
A hydrogen atom in base be replaced by fluorine atoms to be formed containing fluoroalkyl, including but not limited to-CH (F) CH3、-CH2C(F)H2、-
CH2CH(F)CH3、-CH(F)CH2CH3、-CH2CH2CH2(F)；It is also possible to containing two or all hydrogen atoms quilt in fluoroalkyl
Replace what is formed to contain fluoroalkyl, including but not limited to-CF2CF3、-CH(F)C(F)H2、-CH2CH(F2)、-CH2CH(F)CH2
(F)、-CH(F)CH2CH2(F)、-CH(F)CH(F)CH2(F).The Af containing fluoroalkyl that carbon atom number is 2~42It can be in alkyl
A hydrogen atom be replaced by fluorine atoms to be formed containing fluoroalkyl, including but not limited to-CH (F) CH3、-CH2C(F)H2、-CH2CH
(F)CH3、-CH(F)CH2CH3、-CH2CH2CH2(F)、-CH2CH2CH(F)CH3、-CH2CH(F)CH2CH3、-CH2CH2CH2CH2
(F)；Be also possible to be substituted containing two in fluoroalkyl or all hydrogen atoms formed containing fluoroalkyl, including but not limited to-
CF2CF3、-CH(F)C(F)H2、-CH2CH(F2)、-CH2CH(F)CH2(F)、-CH(F)CH2CH2(F)、-CH(F)CH(F)CH2
(F)、-CH(F)CH2CH(F)CH3、-CH2CH(F)CH2CH2(F)、-CH2CH2CH2CF3。
In phosphoric acid cyclic anhydride shown in structural formula II, the skeleton structure and its substituent group of phosphoric acid cyclic anhydride codetermined its
Effect in electrolyte of lithium-ion secondary battery such as forms low-impedance protective film in electrode surface, inhibits electrode and electrolyte
Side reaction, reduce interface impedance, the comprehensive output performance for promoting battery, and can improve containing the dicyandiamide solution compared with Polyfluoroether
Low temperature performance.
Preferably, in structural formula II, the alkyl is selected from methyl, ethyl, propyl, and at least one in isopropyl, isobutyl group
Kind.Amount of carbon atom is excessively that carbochain is too long in the alkyl, can reduce the above-mentioned performance of phosphoric acid cyclic anhydride shown in structural formula II.
Preferably, described to be selected from trifluoromethyl, trifluoroethyl, hexafluoro isopropyl at least containing fluoroalkyl in structural formula II
It is a kind of.
On the basis of the above embodiments, it is further preferred that being structure in terms of 100% by the gross mass of the electrolyte
The mass percentage of fluorine ether shown in formula I is 5%~35%.If the mass percentage of fluorine ether shown in structural formula I is lower than
5%, inhibit the heat production of electrode interface and production gas effect unobvious, the high-temperature storage for improving lithium ion secondary battery is not achieved and follows
The effect of ring performance；If the mass percentage of fluorine ether shown in structural formula I is higher than 35%, bad to the dissociation of lithium salts (unfavorable
In the dissociation of lithium salts), the conductivity of electrolyte is reduced significantly, deteriorates the output performance of lithium ion secondary battery.
It preferably, is the quality percentage of phosphoric acid cyclic anhydride shown in structural formula II in terms of 100% by the gross mass of the electrolyte
Content is 0.01%~2%.If the mass percentage of phosphoric acid cyclic anhydride shown in structural formula II is lower than 0.01%, cannot be in electrode
Surface forms stable protective film, be not achieved " inhibit the side reaction of electrode and electrolyte, reduces interface impedance, it is comprehensive to promote electricity
The improvement of the output performance in pond " is into effect, in addition, can not improve the low temperature performance containing the dicyandiamide solution compared with Polyfluoroether；
It is blocked up in the protective film that electrode surface is formed if the mass percentage of phosphoric acid cyclic anhydride shown in structural formula II is higher than 2%,
Battery polarization increases, deterioration.
It should be noted that it is unique to be not intended as electrolyte for fluorine ether shown in the structural formula I in the embodiment of the present invention
Non-aqueous organic solvent, i.e., the described non-aqueous organic solvent further include other solvents.Specifically, being with the gross mass of the electrolyte
100% meter, the mass percentage of the non-aqueous organic solvent are 55%~75%.
Specific preferred, the non-aqueous organic solvent further includes ethylene carbonate, propene carbonate, butylene, carbon
Dimethyl phthalate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, methyl acetate, ethyl acetate, propyl acetate, propionic acid first
Ester, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, gamma-butyrolacton, gamma-valerolactone, δ-valerolactone, 6-caprolactone
At least one of.Preferred non-aqueous organic solvent can assign lithium ion secondary battery more excellent comprehensive performance.
In the embodiment of the present invention, the lithium salts be lithium hexafluoro phosphate, lithium perchlorate, LiBF4, di-oxalate lithium borate,
One of double fluorine Lithium bis (oxalate) borates, bis- (trimethyl fluoride sulfonyl) imine lithiums and double fluorine sulfimide lithiums are a variety of.It is further excellent
Choosing, it is 10%~18% that the dosage of the lithium salts, which accounts for the mass percent in electrolyte of lithium-ion secondary battery,.
And the embodiment of the invention provides a kind of lithium ion secondary battery, the lithium ion secondary battery include anode,
Cathode, diaphragm and electrolyte, and the electrolyte is electrolyte of lithium-ion secondary battery of the present invention.
Lithium ion secondary battery provided by the invention can due to containing electrolyte of lithium-ion secondary battery of the invention
Improve cycle performance, high-temperature storage performance and the low temperature performance of lithium ion secondary battery.
Preferably, the active material of the anode is transition metal oxide；The active material of the cathode is graphite, contains
The composite material or lithium titanate of Si.
It is further preferred that the transition metal oxide is LiNixCoyMnzL(1-x-y-z)O2, wherein L Al, Sr,
The value of one of Mg, Ti, Ca, Zr, Zn, Si and Fe, x, y, z meet: 0≤x <, 1,0 < y≤1,0≤z < 1, and 0 < x+
y+z≤1.It is illustrated combined with specific embodiments below.
In each embodiment, the Chinese paraphrase and its corresponding compound of alpha code that English is write a Chinese character in simplified form are explained as follows:
DEC: diethyl carbonate
EC: ethylene carbonate
EMC: methyl ethyl carbonate
LiPF6: lithium hexafluoro phosphate
PST:1,3- propene sultone
VEC: vinyl ethylene carbonate
S1 is HCF2CF2CH2OCF2CF2H
S2 is CF3CF2CH2OCF2CFHCF3
S3 is HCF2CF2CH2OCF2CFHCF3
S4 is CF3CF2CH2OCH2CF2CF2CF2CF2H
S5 is HCF2CF2CF2CH2OCF2CF2CF2CF2H
Embodiment 1
A kind of lithium ion secondary battery, including anode, cathode, diaphragm and electrolyte, wherein positive active material is cobalt acid
Lithium (LCO) material；Negative electrode active material is artificial graphite (AG), and the preparation method of the lithium ion secondary battery includes following step
It is rapid:
Gather inclined difluoro second than blended anode active material LCO, conductive carbon black and binder by the quality of 96.8:2.0:1.2
Alkene is dispersed in n-methyl-2-pyrrolidone, obtains anode sizing agent, and anode sizing agent is uniformly coated on the two sides of aluminium foil, warp
Drying, calendering and vacuum drying are crossed, and is burn-on with supersonic welder and obtains positive plate (positive plate) after aluminum lead-out wire, pole plate
Thickness is between 100~115 μm；
By the quality of 96:1:1.2:1.8 than admixed graphite, conductive carbon black, binder butadiene-styrene rubber and carboxymethyl cellulose,
Dispersion in deionized water, obtains negative electrode slurry, negative electrode slurry is coated on the two sides of copper foil, by drying, calendering and true
Sky is dry, and is burn-on with supersonic welder and obtained negative plate (negative electrode tab) after nickel lead-out wire, and the thickness of pole plate is in 115~135 μ
Between m；
In mass ratio it is that 30:50:20 is mixed by ethylene carbonate (EC), methyl ethyl carbonate (EMC), fluorine ether S1, mixes
The lithium hexafluoro phosphate based on electrolyte gross mass 12.5% is added after conjunction, the 1- ethyl phosphorus based on electrolyte gross mass 1% is added
Sour cyclic anhydride (P1), is prepared electrolyte.
Al is coated using single side2O3The ceramic diaphragm of preparation.
Positive plate obtained, diaphragm, negative electrode tab are folded in order, are in diaphragm among positive/negative plate, winding obtains
Naked battery core；Naked battery core is placed in outer packing, the electrolyte of above-mentioned preparation is injected into the battery after drying, encapsulate, stand,
Chemical conversion, shaping and partial volume, complete the preparation (soft-package battery model 435573PL) of lithium ion secondary battery.
2~embodiment of embodiment 15
2~embodiment of embodiment 15, in addition to additive composition is different from content (being based on electrolyte gross mass) in electrolyte
Outside, the preparation of remaining anode, cathode, diaphragm, lithium ion secondary battery is with embodiment 1, in each embodiment shown in structural formula I
The selection of phosphoric acid cyclic anhydride compound and its content shown in fluorine ether, structural formula II are as shown in table 1.
1~comparative example of comparative example 6
In 1~comparative example of comparative example 6, in addition to non-aqueous organic solvent, the type of additive and content (are based on electricity in electrolyte
Solve liquid gross mass) it is different outer, the preparation of remaining anode, cathode, diaphragm, lithium ion secondary battery is the same as embodiment 1, each comparative example
Middle non-aqueous organic solvent, the type of additive and content are as shown in table 1.
Lithium ion secondary battery prepared by embodiment 1~15, comparative example 1~6 is tested for the property, test method is such as
Under:
1) cycle performance is tested: at 25 ± 2 DEG C/45 DEG C ± 2 DEG C, the battery after chemical conversion being charged to 1C constant current constant voltage
4.5V, then with 1C constant-current discharge to 3.0V.The conservation rate that n-th circulation volume is calculated after charge/discharge n times circulation calculates public
Formula is as follows:
N-th circulation volume conservation rate (%)=(n-th cyclic discharge capacity/1st time cyclic discharge capacity) ×
100%；
2) high-temperature storage performance: the battery after chemical conversion is charged to 4.5V with 0.5C constant current constant voltage at normal temperature, measures battery
Original depth, initial discharge capacity, then after 60 DEG C store 7 days, heat surveys battery final thickness, calculates cell thickness expansion
Rate；The holding capacity of 3.0V measurement battery is discharged to 0.5C after cooling and restores capacity.Calculation formula is as follows:
Cell thickness expansion rate (%)=(heat surveys final thickness-original depth)/original depth × 100%；
Battery capacity conservation rate (%)=holding capacity/initial capacity × 100%；
Capacity resuming rate (%)=recovery capacity/initial capacity × 100%.
3) low temperature discharge: in room temperature with 1C constant-current constant-voltage charging to 4.5V, shelving 5min, and 0.2C is discharged to 3.0V, detection
Battery initial capacity.Shelve 5min, 1C constant-current constant-voltage charging to 4.5V (cut-off current 0.01C).Battery is put into -20 DEG C
4h is shelved in cryogenic box, and 3.0V is discharged to 0.2C with this condition, detects the discharge capacity under low temperature.
Low temperature discharge conservation rate (%)=low temperature discharge capacity/initial capacity × 100%.
Test result see the table below 1.
Table 1
In table 1 and the following table 3, the structure that P1-P5 is indicated is as shown in table 2.
Table 2
The battery system of each embodiment and comparative example is 4.5V cobalt acid lithium collocation artificial graphite.As can be seen from Table 2, using this hair
The embodiment 1 of bright technical solution to embodiment 15 has good cycle performance, high-temperature storage performance and low temperature performance；And
Battery portion output performance using comparative example 1 to 6 electrolyte of comparative example is poor, cannot combine high/low temperature and cycle performance.
Specifically, comparative example 1 and comparative example 6 use DEC to replace fluorine ether S1 and S5 compared with embodiment 1 and embodiment 9,
Low temperature performance and embodiment 1 and embodiment 9 are suitable；But high temperature circulation, normal temperature circulation and high-temperature storage performance are serious
Deterioration.The presence for illustrating fluorine ether S1 or S5 promotes the high temperature circulation and high-temperature storage characteristics of LCO/AG battery under the conditions of 4.5V
Can, but have negative effect to low temperature discharge.
Comparative example 2 and comparative example 5 contain fluorine ether S1 and S5, without cycli phosphate acid anhydride shown in II compound of formula, in -20 DEG C of conditions
Lower 0.2C electric discharge is 50.3%, 51.9%, far below the not only embodiment 1 containing fluorine ether but also containing cycli phosphate acid anhydride compound, is implemented
Example 5, embodiment 9, embodiment 10, embodiment 11, embodiment 12.Illustrate the presence of cycli phosphate acid anhydride, low temperature discharge property can be promoted
Can, it is combined with fluorine ether, takes into account the high temperature performance of battery to a certain extent.
Comparative example 3 and comparative example 4 by this be formulated in cycli phosphate acid anhydride alternative costs field positive electrode surface film forming agent PST and
VEC can not solve the problems, such as that the dicyandiamide solution low temperature performance of Polyfluoroether is poor.
Each embodiment is further advanced by learn with comparative example comparison:
Under the conditions of 4.5V, part carbonic ester is replaced using suitable fluorine ether, the pressure resistance under high voltage condition can be promoted
Stability improves the high temperature circulation and high-temperature storage performance of battery, but excessive fluorine ether replaces carbonate-based solvent, electrolyte
Conductivity reduces, and battery output capacity is also low, deteriorates low temperature performance.Therefore the present invention is containing suitable fluorine ether solvents
In system, additive cycli phosphate acid anhydride is introduced, cycle performance, high-temperature storage performance and the low temperature of battery under the conditions of 4.5V can be improved
Discharge performance.The output of (>=4.5V) lithium ion secondary battery can be effectively improved under high voltage condition using this technical solution
Energy.Therefore the technical solution that this case is combined by fluorine ether solvents and Low ESR additive cyclic acid anhydride, successfully solves
Problem is stated, and achieves unexpected effect.
16~embodiment of embodiment 29
In embodiment 16 into embodiment 29, lithium ion secondary battery anode material uses NCA, and negative electrode active material is silicon
Carbon, silicon-carbon cathode capacity are 500mAh/g.Diaphragm coats Al using single side2O3Ceramic diaphragm.Additive group in electrolyte used
At by addition shown in table 3, battery evaluation charge cutoff voltage is 4.2V, and discharge lower limit with content (being based on electrolyte gross mass)
Voltage is 2.75V.Remaining preparation process is the same as embodiment 1.
7~comparative example of comparative example 12
In 7~comparative example of comparative example 12, in addition to non-aqueous organic solvent, the type of additive and content (are based in electrolyte
Electrolyte gross mass) it is different outer, the preparation of remaining anode, cathode, diaphragm, lithium ion secondary battery with embodiment 16~29,
Non-aqueous organic solvent, the type of additive and content are as shown in table 3 in each comparative example.
Lithium ion secondary battery prepared by embodiment 16~29, comparative example 7~12 is tested for the property, test method is such as
Illustrated above, test result is shown in Table 3.
Table 3
The battery system of each embodiment and comparative example is NCA collocation silicon-carbon composite cathode in table 3.Seen from table 3, using this
The embodiment 16 of inventive technique scheme to embodiment 29 equally has preferable cycle performance, high-temperature storage and low temperature discharge property
Energy；And use the battery portion output performance of comparative example 7 to 12 electrolyte of comparative example poor, high/low temperature and circulation cannot be combined
Performance.
Specifically, replacing fluorine ether S1, normal temperature circulation and low temperature discharge property using FEC in comparative example 7 compared with embodiment 16
It can be suitable with embodiment；But 45 DEG C of the battery of comparative example 7 the 200th circle capacity attenuations of circulation are 36.7%, after 60 DEG C store 7 days
Flatulence is serious, and conservation rate and recovery rate are far below embodiment 1.Deduce in nickelic collocation silicon-carbon system, using fluorine ether of the invention
Replace FEC, the high temperature circulation and high-temperature storage performance of NCA/Si-C battery can be promoted significantly.
Comparative example 12 replaces fluorine ether S1 using DEC, and low temperature performance and embodiment 16 are suitable, but high temperature circulation, often
Temperature circulation and the equal serious deterioration of high-temperature storage performance.The presence for illustrating fluorine ether S1 is conducive to improve high-temperature behavior, but to low temperature
Electric discharge has negative effect.
Comparative example 8 and comparative example 11 contain fluorine ether S1 and S5, are free of cycli phosphate acid anhydride, and 0.2C, which discharges, under the conditions of -20 DEG C is
60.1%, 62.5%, far below the not only each group embodiment containing fluorine ether but also containing cycli phosphate acid anhydride compound.Illustrate cycli phosphate acid anhydride
In the presence of can promote low temperature performance, be combined with fluorine ether, high temperature performance can be taken into account.
Comparative example 9 and comparative example 10 by this be formulated in cycli phosphate acid anhydride alternative costs field positive electrode surface film forming agent PST
And VEC, low temperature discharge further deteriorate, and can not solve the problems, such as that the dicyandiamide solution low temperature performance of Polyfluoroether is poor.
It is further advanced by each embodiment and comparative example comparison finds that the embodiment of the present invention passes through fluorine ether shown in structural formula I
With cycli phosphate acid anhydride shown in structural formula II, generated synergistic effect is applied in combination in the two, so that the lithium containing this nonaqueous electrolytic solution
Ion secondary battery obtains good cell output.This technical solution not only can be applied to high voltage cobalt acid lithium system, but also
It can be used for nickelic positive system, significantly improve effect.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention
Made any modifications, equivalent replacements, and improvements etc., should all be included in the protection scope of the present invention within mind and principle.
Claims (10)
1. a kind of electrolyte of lithium-ion secondary battery, which is characterized in that the electrolyte includes non-aqueous organic solvent, lithium salts and adds
Add agent, wherein the non-aqueous organic solvent comprises the following structure fluorine ether shown in formula I, and the additive comprises the following structure formula
Phosphoric acid cyclic anhydride shown in II:
In structural formula I, Af1It is 2~3 containing fluoroalkyl, Af selected from carbon atom number2It is 2~4 containing fluoroalkyl selected from carbon atom number；
In structural formula II, A1、A2、A3Independently selected from alkyl, contain one of fluoroalkyl, allyl, phenyl.
2. electrolyte of lithium-ion secondary battery as described in claim 1, which is characterized in that in structural formula II, the alkyl choosing
From methyl, ethyl, propyl, at least one of isopropyl, isobutyl group.
3. electrolyte of lithium-ion secondary battery as described in claim 1, which is characterized in that described to contain fluothane in structural formula II
Base be selected from trifluoromethyl, trifluoroethyl, hexafluoro isopropyl at least one.
4. electrolyte of lithium-ion secondary battery as described in any one of claims 1-3, which is characterized in that with the electrolyte
Gross mass is 100% meter, and the mass percentage of fluorine ether shown in structural formula I is 5%~35%.
5. electrolyte of lithium-ion secondary battery as described in any one of claims 1-3, which is characterized in that with the electrolyte
Gross mass is 100% meter, and the mass percentage of phosphoric acid cyclic anhydride shown in structural formula II is 0.01%~2%.
6. electrolyte of lithium-ion secondary battery as described in any one of claims 1-3, which is characterized in that described non-aqueous organic molten
Agent further includes ethylene carbonate, propene carbonate, butylene, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, carbon
Sour first propyl ester, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, butyric acid
At least one of ethyl ester, gamma-butyrolacton, gamma-valerolactone, δ-valerolactone, 6-caprolactone.
7. electrolyte of lithium-ion secondary battery as claimed in claim 6, which is characterized in that the gross mass with the electrolyte is
100% meter, the mass percentage of the non-aqueous organic solvent are 55%~75%.
8. a kind of lithium ion secondary battery, which is characterized in that the lithium ion secondary battery includes anode, cathode, diaphragm and electricity
Liquid is solved, and the electrolyte is the described in any item electrolyte of lithium-ion secondary battery of claim 1-7.
9. lithium ion secondary battery as claimed in claim 8, which is characterized in that the active material of the anode is transition metal
Oxide；The active material of the cathode is graphite, composite material or lithium titanate containing Si.
10. lithium ion secondary battery as claimed in claim 9, which is characterized in that the transition metal oxide is
LiNixCoyMnzL(1-x-y-z)O2, wherein the value of one of L Al, Sr, Mg, Ti, Ca, Zr, Zn, Si and Fe, x, y, z are full
Foot: 0≤x <, 1,0 < y≤1,0≤z < 1, and 0 x+y+z≤1 <.
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| CN107658498A (en) * | 2017-10-24 | 2018-02-02 | 广州天赐高新材料股份有限公司 | Lithium secondary cell electrolyte and its lithium secondary battery |
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| JP2013222612A (en) * | 2012-04-17 | 2013-10-28 | Hitachi Maxell Ltd | Nonaqueous secondary battery |
| CN103779607A (en) * | 2014-01-17 | 2014-05-07 | 中南大学 | Electrolyte solution and lithium-ion secondary battery |
| US20160226104A1 (en) * | 2015-02-03 | 2016-08-04 | Blue Current, Inc. | Functionalized phosphorus containing fluoropolymers and electrolyte compositions |
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