CN107919497A - Electrolyte and secondary cell - Google Patents
Electrolyte and secondary cell Download PDFInfo
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- CN107919497A CN107919497A CN201610875160.XA CN201610875160A CN107919497A CN 107919497 A CN107919497 A CN 107919497A CN 201610875160 A CN201610875160 A CN 201610875160A CN 107919497 A CN107919497 A CN 107919497A
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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
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
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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
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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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- Secondary Cells (AREA)
Abstract
The present invention provides a kind of electrolyte and secondary cell.The electrolyte includes electrolytic salt, organic solvent and additive.The additive includes benzene mono-nitrile compound, cyclic sulfates and fluorinated ethylene carbonate.After the electrolyte of the present invention is applied to secondary cell, the anti-overcharge performance of secondary cell can be significantly improved, while secondary cell also has relatively low circulation impedance and higher circulation volume conservation rate.
Description
Technical field
The present invention relates to battery technology field, more particularly to a kind of electrolyte and secondary cell.
Background technology
Secondary cell especially lithium rechargeable battery has high energy density, operating voltage height, self-discharge rate is low, circulates
The unique advantage such as long lifespan, pollution-free, is widely used in the electronic products such as camera, mobile phone as power supply.In recent years, with
The fast development of smart electronics product, the requirement of higher is proposed to the cruising ability of secondary cell.In order to improve secondary electricity
The energy density in pond, exploitation high voltage secondary cell is one of effective ways.At present, operating voltage is in the secondary of more than 4.35V
Battery has become the hot spot of numerous R＆D institutions and business research.However, under high voltage secondary cell security performance, such as anti-mistake
Fill performance and face very big challenge.Common anti-overcharge additive such as biphenyl, has preferable anti-overcharge performance, but in 4.2V
Hereinafter, electric polymerization reaction just occurs for biphenyl, causes secondary cell impedance to dramatically increase, causes secondary cell to fail.Therefore, in height
Under voltage, some common anti-overcharge additive such as biphenyl, cyclohexyl benzene etc. can not be used, it is necessary to find electropolymerization voltage higher
Anti-overcharge additive.
The content of the invention
In view of problem present in background technology, it is an object of the invention to provide a kind of electrolyte and secondary cell, when
After the electrolyte is applied to secondary cell, the anti-overcharge performance of secondary cell can be significantly improved, while secondary cell also has
There are relatively low circulation impedance and higher circulation volume conservation rate.
In order to achieve the above object, in one aspect of the invention, the present invention provides a kind of electrolyte, it includes electrolyte
Salt, organic solvent and additive.The additive includes benzene mono-nitrile compound, cyclic sulfates and fluorinated ethylene carbonate
(FEC)。
In another aspect of this invention, the present invention provides a kind of secondary cell, it includes institute according to an aspect of the present invention
The electrolyte stated.
Relative to the prior art, beneficial effects of the present invention are：
After the electrolyte of the present invention is applied in secondary cell, the anti-overcharge performance of secondary cell can be significantly improved,
Secondary cell also has relatively low circulation impedance and higher circulation volume conservation rate at the same time.
Brief description of the drawings
Fig. 1 overcharges test curve figure for comparative example 1 with embodiment 3.
Embodiment
The following detailed description of electrolyte according to the present invention and secondary cell.
Illustrate electrolyte according to a first aspect of the present invention first.
Electrolyte according to a first aspect of the present invention includes electrolytic salt, organic solvent and additive.The additive
Including benzene mono-nitrile compound, cyclic sulfates and fluorinated ethylene carbonate (FEC).
In the electrolyte described according to a first aspect of the present invention, since the strong electrophilic of-CN in benzene mono-nitrile compound is made
With, reduce the Cloud Distribution on phenyl ring, the electropolymerization voltage of such compound can be improved, realize high voltage (>=
Itself do not occur in normal range of operation 4.35V) significantly, rapidly electric polymerization reaction, secondary cell will not be caused to fail, and
When the voltage of secondary cell, which is crossed, is charged to more than 4.8V, electric polymerization reaction can occur rapidly for benzene mono-nitrile compound so that impedance is anxious
Increase severely and add, block charging current, avoid secondary cell that combustion explosion occurs.Benzene mono-nitrile compound is due to only containing a suction at the same time
Electron group-CN, avoids when nitrile compound more using benzene, since multiple electron withdrawing group-CN cause carbon atom on phenyl ring strong
Strong electropositive, causes the more nitrile compounds of benzene that reduction reaction easily occurs in anode, secondary cell is failed.
On the other hand, due to the effect of the upper lone pair electrons of-CN, just having stronger adsorptivity, and working normally
In voltage range, benzene mono-nitrile compound also can occur slow electropolymerization in cathode and cause impedance to increase.And cyclic sulfates are easy
Reacted in cathode, one layer of fine and close passivation layer is generated in positive electrode surface, be conducive to suppress benzene mono-nitrile compound in normal work electricity
Slow electropolymerization, which occurs, in cathode in the range of pressure causes impedance to increase.FEC is that a kind of widely applied excellent cathode film formation adds
Add agent.When the electrolyte adds benzene mono-nitrile compound, cyclic sulfates and FEC at the same time, FEC can be formed in anode and protected
Layer, while coordinate the protective effect of benzene mono-nitrile compound and cyclic sulfates in cathode, suppress the increase of cathode impedance, improve two
The anti-overcharge performance of primary cell, while make secondary cell that there is relatively low circulation impedance and higher circulation volume conservation rate.
In the electrolyte described according to a first aspect of the present invention, the benzene mono-nitrile compound is selected from the chemical combination shown in formula I
One or more in thing.Wherein, R1Selected from the alkyl that carbon number is 0~5, R2、R3、R4、R5、R6Be each independently selected from H,
F, the sulfonic acid that carboxylic acid ester groups that Cl, Br, I, carbon number are 1~5 alkyl, carbon number are 2~5, carbon number are 1~5
One kind in ester group, the sulfate group that carbon number is 1~5.It should be noted that the carboxylic acid ester groups that carbon number is 2~5 is
Finger-(C=O) OR, wherein R represents the alkyl that carbon number is 1~4；The sulfonate group that carbon number is 1~5 refers to-(O=S
=O) OR ', wherein R ' represent carbon number be 1~5 alkyl；The sulfate group that carbon number is 1~5 refers to-O- (O=S=
O) OR ", wherein R " represent the alkyl that carbon number is 1~5.
In the electrolyte described according to a first aspect of the present invention, specifically, the benzene mono-nitrile compound is selected from followingization
One or more in compound；
In the electrolyte described according to a first aspect of the present invention, the cyclic sulfates are selected from the compound shown in formula II
In one or more.Wherein, n be 1~4 in integer, R21、R22、R23、R24It is each independently selected from H, F, Cl, Br, I, carbon
Atomicity is one kind in 1~5 alkyl, and the alkyl that carbon number is 1~5 can also be by the one or more in F, Cl, Br, I
Part substitution or all substitution.It should be noted that the recurring group in bracket may be the same or different.
In the electrolyte described according to a first aspect of the present invention, specifically, the cyclic sulfates are selected from following chemical combination
One or more in thing；
In the electrolyte described according to a first aspect of the present invention, the content of the benzene mono-nitrile compound is the electrolyte
The 0.1%~3% of gross mass.The content of benzene mono-nitrile compound is too low, is not enough to lift secondary electricity in the protective layer that cathode is formed
Capacity retention ratio after the circulation of pond, while when overcharging generation, be unfavorable for that electric polymerization reaction blocking charging current quickly occurs, rise
Less than the effect for significantly improving the anti-overcharge performance of secondary cell；The content of benzene mono-nitrile compound is too high, although secondary electricity can be lifted
The anti-overcharge performance in pond, but since the content of benzene mono-nitrile compound is too high, it is also difficult even if with the addition of cyclic sulfates passivation cathode
Cause impedance to increase in the slow electropolymerization of cathode to completely inhibit benzene mono-nitrile compound, be unfavorable for secondary cell during normal use
Cycle performance improvement.Preferably, the content of the benzene mono-nitrile compound is the 0.2%~3% of the electrolyte gross mass.
It is further preferred that the content of the benzene mono-nitrile compound is the 0.5%~2% of the electrolyte gross mass.
In the electrolyte described according to a first aspect of the present invention, the content of the cyclic sulfates is total for the electrolyte
The 0.1%~3% of quality.The content of cyclic sulfates is too low, can not suppress benzene mono-nitrile compound in the slow electropolymerization of cathode；
The content of cyclic sulfates is too high, then forms a film at cathode interface thicker, to capacity retention ratio and impedance after the circulation of secondary cell
It is unfavorable on the contrary to increase control.Preferably, the content of the cyclic sulfates is the 0.2%~3% of the electrolyte gross mass.Into
Preferably, the content of the cyclic sulfates is the 0.5%~2% of the electrolyte gross mass to one step.
In the electrolyte described according to a first aspect of the present invention, the content of fluorinated ethylene carbonate is electrolyte gross mass
0.5%~15%.Preferably, the content of fluorinated ethylene carbonate is the 1%~10% of electrolyte gross mass.Further preferably
Ground, the content of fluorinated ethylene carbonate are the 2%~7% of electrolyte gross mass.The too low FEC of content cannot be formed fully in anode
Protective layer, it is impossible to reach suppress nitrile compounds anode side reaction；Content is too high, and thicker SEI films are generated in anode,
Impedance is brought to increase.
In the electrolyte described according to a first aspect of the present invention, the electrolytic salt may be selected from lithium salts, sodium salt or zinc salt,
According to the electrolyte application secondary cell it is different and different.
In the electrolyte described according to a first aspect of the present invention, the organic solvent is preferably non-aqueous organic solvent.Tool
Body, the organic solvent may be selected from ethylene carbonate (EC), propene carbonate (PC), dimethyl carbonate (DMC), carbonic acid diethyl
Ester (DEC), methyl ethyl carbonate (EMC), gamma-butyrolacton (BL), methyl formate (MF), Ethyl formate (MA), ethyl propionate (EP),
One or more in propyl propionate (PP) and tetrahydrofuran (THF).
Secondly the secondary cell of explanation according to a second aspect of the present invention.
Secondary cell according to a second aspect of the present invention includes the electrolyte described according to a first aspect of the present invention.
In the secondary cell described according to a second aspect of the present invention, the secondary cell further includes：Positive plate, including just
Pole collector and it is arranged on plus plate current-collecting body and cathode diaphragm containing a positive electrode active material；Negative plate, including negative pole currect collecting
Body and it is arranged on negative current collector and cathode membrane containing a negative electrode active material；Isolation film, is interval in positive plate and anode
Between piece；And packaging bag.
In the secondary cell described according to a second aspect of the present invention, the upper limit cut-off during secondary cell normal use
Voltage is 4.35V~5V, is preferably 4.35V~4.8V.
In the secondary cell described according to a second aspect of the present invention, the secondary cell can be lithium rechargeable battery,
Sodium ion secondary battery or zinc ion secondary cell.
When secondary cell is that the electrolytic salt may be selected from LiPF in lithium rechargeable battery6、LiClO4、LiAsF6、LiN
(CF3SO2)2、LiCF3SO3And the one or more in LiBOB.The positive electrode active materials may be selected from cobalt acid lithium, LiMn2O4,
One or more in LiFePO4, lithium-nickel-manganese-cobalt ternary material, lithium nickel cobalt aluminium ternary material.The negative active core-shell material is optional
From graphite, silicon or the mixture of the two.
When secondary cell is sodium ion secondary battery or zinc ion secondary cell, it is only necessary to change corresponding positive-active material
Material, negative active core-shell material, electrolytic salt.
With reference to embodiment, the application is expanded on further.It is to be understood that these embodiments be merely to illustrate the application without
For limiting scope of the present application.The situation that secondary cell is lithium rechargeable battery, but the present invention are only shown in embodiment
Not limited to this.
In the examples below, used material, reagent and instrument be not as having specified otherwise, commercially
Purchase obtains.
Embodiment 1
(1) preparation of electrolyte
It is EC in mass ratio by EC, PC, DEC in drying shed:PC:DEC=1:1:After 1 is mixed, it is mixed with
Solvent, then the lithium salts LiPF that will fully dry6It is dissolved in above-mentioned mixed organic solvents, then adds compound 1 thereto
(i.e. cyanophenyl), compound 7 (i.e. sulfuric acid vinyl ester) and fluorinated ethylene carbonate (FEC), after stirring evenly, obtain electrolyte.Its
In, in the electrolytic solution, the mass fraction of compound 1, compound 7 and FEC is respectively 1%, 0.2% and 2%, LiPF6Concentration
For 1mol/L.
(2) preparation of positive plate
Weigh 1.42kg Solvents N-methyls -2-Pyrrolidone (NMP), the binding agent that 1.2kg mass fractions are 10% gathers partially
Difluoroethylene (PVDF), 0.16kg conductive agents electrically conductive graphite and 7.2kg positive electrode active materials LiCoO2It is sufficiently mixed and stirs
To anode sizing agent, anode sizing agent is uniformly coated on the plus plate current-collecting body aluminium foil that thickness is 16 μm afterwards, afterwards at 120 DEG C
Baking 1h obtains cathode diaphragm, obtains positive plate through overcompaction, cutting afterwards.
(3) preparation of negative plate
Weigh thickener sodium carboxymethylcellulose (CMC) solution, 0.07kg mass point that 1.2kg mass fractions are 1.5%
Count the binding agent SBR emulsion for 50%, 2.4kg negative active core-shell material powdered graphites are sufficiently mixed stirring and obtain anode slurry
Cathode size, is uniformly coated on the negative current collector copper foil that thickness is 12 μm by material afterwards, and toasting 1h at 120 DEG C afterwards obtains
To cathode membrane, negative plate is obtained through overcompaction, cutting afterwards.
(4) preparation of lithium rechargeable battery
Above-mentioned positive plate, negative plate are separated with the polypropylene isolation film that thickness is 12 μm and wind the naked electricity of squarely
Core, loads aluminum foil sack afterwards, and after 80 DEG C of baking water removals, injection electrolyte, sealing, chemical conversion, exhaust and test capacity obtain
To the lithium rechargeable battery of finished product.
Embodiment 2
The preparation process of lithium rechargeable battery with embodiment 1, difference lies in：In the electrolytic solution, the quality of compound 1 point
Number is 1%, and the mass fraction that the mass fraction of compound 7 is 0.5%, FEC is 2%.
Embodiment 3
The preparation process of lithium rechargeable battery with embodiment 1, difference lies in：In the electrolytic solution, the quality of compound 1 point
Number is 1%, and the mass fraction that the mass fraction of compound 7 is 1%, FEC is 2%.
Embodiment 4
The preparation process of lithium rechargeable battery with embodiment 1, difference lies in：In the electrolytic solution, the quality of compound 1 point
Number is 1%, and the mass fraction that the mass fraction of compound 7 is 2%, FEC is 2%.
Embodiment 5
The preparation process of lithium rechargeable battery with embodiment 1, difference lies in：In the electrolytic solution, the quality of compound 1 point
Number is 1%, and the mass fraction that the mass fraction of compound 7 is 3%, FEC is 2%.
Embodiment 6
The preparation process of lithium rechargeable battery with embodiment 1, difference lies in：In the electrolytic solution, the quality of compound 1 point
Number is 0.2%, and the mass fraction that the mass fraction of compound 7 is 1%, FEC is 2%.
Embodiment 7
The preparation process of lithium rechargeable battery with embodiment 1, difference lies in：In the electrolytic solution, the quality of compound 1 point
Number is 0.5%, and the mass fraction that the mass fraction of compound 7 is 1%, FEC is 2%.
Embodiment 8
The preparation process of lithium rechargeable battery with embodiment 1, difference lies in：In the electrolytic solution, the quality of compound 1 point
Number is 2%, and the mass fraction that the mass fraction of compound 7 is 1%, FEC is 2%.
Embodiment 9
The preparation process of lithium rechargeable battery with embodiment 1, difference lies in：The mass fraction of compound 1 is 3%, is changed
The mass fraction that the mass fraction of compound 7 is 1%, FEC is 2%.
Comparative example 1
The preparation process of lithium rechargeable battery with embodiment 1, difference lies in：Compound 1 is not added in electrolyte and is changed
Compound 7, the mass fraction for adding FEC are 2%.
Comparative example 2
The preparation process of lithium rechargeable battery with embodiment 1, difference lies in：Mass fraction is only added in electrolyte is
1% compound 1 and mass fraction is 2% FEC, does not add compound 7.
Comparative example 3
The preparation process of lithium rechargeable battery with embodiment 1, difference lies in：Mass fraction is only added in electrolyte is
1% compound 7 and mass fraction is 2% FEC, does not add compound 1.
Comparative example 4
The preparation process of lithium rechargeable battery with embodiment 1, difference lies in：In the electrolytic solution, the quality of compound 1 point
Number is 1%, and the mass fraction of compound 7 is 1%, does not add FEC.
The test process of lithium rechargeable battery will be illustrated next.
(1) the over-charging test of lithium rechargeable battery
At 25 DEG C, by lithium rechargeable battery using 0.5C constant-current charges to voltage as 4.35V, afterwards with 4.35V constant pressures
It is 0.05C to charge to electric current, and lithium rechargeable battery reaches fully charged state (i.e. 100%SOC) at this time, and charging capacity, which is denoted as, completely fills
Capacity.
By lithium rechargeable battery using 0.5C constant-current charges to voltage as 10V, afterwards with 10V continue constant-voltage charge 2 it is small when,
Observe the state of lithium rechargeable battery.
When lithium rechargeable battery is not by overcharging test, charging when record lithium rechargeable battery overcharges failure is held
Amount, obtains SOC states when lithium rechargeable battery overcharges failure.Peak value temperature when lithium rechargeable battery overcharges is recorded at the same time
Degree.SOC states (%) when lithium rechargeable battery overcharges failure=(charging capacity when overcharging failure/completely fill capacity) ×
100%.
When lithium rechargeable battery is by overcharging test, the charging capacity in lithium rechargeable battery 2h is recorded, is obtained
The SOC states of lithium rechargeable battery.
(2) the cycle performance test of lithium rechargeable battery
At 25 DEG C, lithium rechargeable battery is stood 30 minutes, afterwards using 0.5C constant-current charges to voltage as 4.35V,
Afterwards using 4.35V constant-voltage charges to electric current as 0.05C, 5 minutes are stood, afterwards using 0.5C constant-current discharges to voltage as 3.0V, this
For a charge and discharge cycles process, this discharge capacity is the discharge capacity circulated first of lithium rechargeable battery.By lithium
Ion secondary battery carries out 300 cycle charge discharge electrical testings in a manner described, and detection obtains the discharge capacity of n-th circulation.
Capacity retention ratio (%) after the circulation of lithium rechargeable battery n times=discharge capacity of n-th circulation/circulates first
Discharge capacity × 100%.
(3) the circulation impedance of lithium rechargeable battery increases test
It is permanent with 3.85V afterwards by the lithium rechargeable battery after initial discharge using 0.5C constant-current charges to voltage as 3.85V
It is 0.05C that pressure, which charges to electric current, and the internal resistance that lithium rechargeable battery at this time is tested using universal meter is denoted as lithium rechargeable battery
Initial impedance, then carry out above-mentioned cycle charge discharge electrical testing, often circulate 100 times after test lithium rechargeable battery impedance.
Lithium rechargeable battery circulation impedance growth rate (%)=(impedance/initial impedance -1 of n-th circulation) ×
100%.
1 lithium rechargeable battery of table overcharges test result
| Overcharge failure state | SOC states (%) | Peak temperature (DEG C) | |
| Comparative example 1 | Do not pass through | 171 | >400 |
| Comparative example 2 | Pass through | 196 | 66 |
| Comparative example 3 | Do not pass through | 173 | >400 |
| Comparative example 4 | Pass through | 196 | 62 |
| Embodiment 1 | Pass through | 195 | 64 |
| Embodiment 2 | Pass through | 196 | 61 |
| Embodiment 3 | Pass through | 197 | 61 |
| Embodiment 4 | Pass through | 195 | 63 |
| Embodiment 5 | Pass through | 196 | 60 |
| Embodiment 6 | Do not pass through | 177 | >400 |
| Embodiment 7 | Do not pass through | 184 | >400 |
| Embodiment 8 | Pass through | 193 | 62 |
| Embodiment 9 | Pass through | 189 | 64 |
The cycle performance test result of 2 lithium rechargeable battery of table
The circulation impedance test results of 3 lithium rechargeable battery of table
Fig. 1 overcharges test curve figure for comparative example 1 with embodiment 3, it will be seen from figure 1 that embodiment 3 adds in the electrolytic solution
After adding cyanophenyl, 1% sulfuric acid vinyl ester and 2% FEC that mass fraction is 1%, pass through and overcharged test.Work as lithium ion secondary
When over-charging of battery is to 165%SOC, electric polymerization reaction takes place in cyanophenyl in electrolyte, and impedance gradually increases, and is finally reached blocking
The effect of charging current.And in comparative example 1, lasting overcharging causes constant temperature to rise, and thermal runaway finally occurs, with reference to table 1
Understand, peak temperature is more than 400 DEG C, and lithium rechargeable battery has burnt failure.
It was found from the test result of table 2 and table 3, in comparative example 2-3, cyanophenyl or sulfuric acid ethene are individually added in electrolyte
Ester is used cooperatively the effect that can act as certain improvement lithium rechargeable battery circulation volume conservation rate with FEC, but single
Solely addition cyanophenyl (comparative example 2) increases the circulation impedance of lithium rechargeable battery very fast, and individually adds sulfuric acid vinyl ester and use up
Pipe can suppress the quick increase of cyclic process middle impedance, but lithium rechargeable battery can not be by overcharging test.
It can be seen that from the test result of comparative example 4 and embodiment 3 after adding cyanophenyl and sulfuric acid vinyl ester in electrolyte,
Lithium rechargeable battery, which has all passed through, overcharges test, but FEC is not added with comparative example 4, and the circulation of lithium rechargeable battery is held
Quickly, impedance rate of rise is also very fast for amount decay.
Can be seen that from the test result of comparative example 2 and embodiment 1-5 and mass fraction is added in electrolyte is 1% cyanophenyl
After 2% FEC, while add sulfuric acid vinyl ester and can reach and be obviously improved lithium rechargeable battery circulation volume conservation rate
Effect, while impedance growth of the lithium rechargeable battery in cyclic process is inhibited.The wherein additive amount of sulfuric acid vinyl ester
For 0.5%~2% when improvement become apparent.When sulfuric acid vinyl ester additive amount is higher, reference implementation example 5, sulfuric acid ethene
Ester additive amount is 3%, and since cathode interface film forming is thicker, the circulation volume conservation rate of lithium rechargeable battery is declined slightly and follows
Ring impedance, which increases, slightly to be risen, therefore the additive amount of sulfuric acid vinyl ester needs to control below 3%.
Can be seen that addition mass fraction in electrolyte from the test result of comparative example 3, embodiment 3 and embodiment 6-9 is
After 1% sulfuric acid vinyl ester and 2% FEC, while cyanophenyl is added in addition to it can improve over-charging, may also reach up lifting lithium
The effect of ion secondary battery circulation volume conservation rate.Improvement is more bright when wherein the additive amount of cyanophenyl is 0.5%~2%
It is aobvious.When cyanophenyl additive amount is relatively low, reference implementation example 6-7, although lithium rechargeable battery under 10V by not overcharging test
(being probably to cause since the overcharged voltage of test is excessive), but SOC when lithium rechargeable battery overcharges failure is improved.
When cyanophenyl additive amount is higher, reference implementation example 9, although the anti-overcharge performance of lithium rechargeable battery can be lifted, due to
The too high levels of cyanophenyl, even if with the addition of sulfuric acid vinyl ester passivation cathode, it is also difficult to which cyanophenyl is just when completely inhibiting normal use
Extremely slow electropolymerization, the growth for ultimately resulting in circulation impedance are accelerated, therefore the additive amount of cyanophenyl needs to control below 3%.
The above, is only several embodiments of the application, any type of limitation is not done to the application, although this Shen
Please with preferred embodiment disclose as above, but and be not used to limitation the application, any person skilled in the art, is not taking off
In the range of technical scheme, make a little variation using the technology contents of the disclosure above or modification is equal to
Case study on implementation is imitated, is belonged in the range of technical solution.
Claims (10)
1. a kind of electrolyte, including：
Electrolytic salt；
Organic solvent；And
Additive；
It is characterized in that,
The additive includes benzene mono-nitrile compound, cyclic sulfates and fluorinated ethylene carbonate.
2. electrolyte according to claim 1, it is characterised in that the benzene mono-nitrile compound is selected from the chemical combination shown in formula I
One or more in thing；
Wherein, R1Selected from the alkyl that carbon number is 0~5, R2、R3、R4、R5、R6It is each independently selected from H, F, Cl, Br, I, carbon
Sulfonate group that carboxylic acid ester groups that alkyl that atomicity is 1~5, carbon number are 2~5, carbon number are 1~5, carbon number
For one kind in 1~5 sulfate group.
3. electrolyte according to claim 1, it is characterised in that the cyclic sulfates are selected from the compound shown in formula II
In one or more；
Wherein, n be 1~4 in integer, R21、R22、R23、R24It is 1~5 to be each independently selected from H, F, Cl, Br, I, carbon number
Alkyl in one kind, the alkyl that carbon number is 1~5 can also be by one or more of part substitutions or complete in F, Cl, Br, I
Portion substitutes.
4. electrolyte according to claim 2, it is characterised in that the benzene mono-nitrile compound is in following compounds
It is one or more of；
5. electrolyte according to claim 3, it is characterised in that the cyclic sulfates in following compounds one
Kind is several；
6. electrolyte according to claim 1, it is characterised in that the content of the benzene mono-nitrile compound is the electrolyte
The 0.1%~3% of gross mass, is preferably 0.2%~3%, and more preferably 0.5%~2%.
7. electrolyte according to claim 1, it is characterised in that the content of the cyclic sulfates is total for the electrolyte
The 0.1%~3% of quality, is preferably 0.2%~3%, and more preferably 0.5%~2%.
8. electrolyte according to claim 1, it is characterised in that the content of the fluorinated ethylene carbonate is total for electrolyte
The 0.5%~15% of quality, is preferably 1%~10%, and more preferably 2%~7%.
9. electrolyte according to claim 1, it is characterised in that the organic solvent is selected from ethylene carbonate, carbonic acid third
Enester, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, gamma-butyrolacton, methyl formate, Ethyl formate, ethyl propionate, third
One or more in propyl propionate and tetrahydrofuran.
10. a kind of secondary cell, it is characterised in that including the electrolyte according to any one of claim 1-9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610875160.XA CN107919497A (en) | 2016-10-08 | 2016-10-08 | Electrolyte and secondary cell |
Applications Claiming Priority (1)
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115189022A (en) * | 2022-05-24 | 2022-10-14 | 惠州锂威新能源科技有限公司 | Electrolyte, preparation method and application thereof, and lithium ion battery |
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