A kind of electrolyte that contains benzene three nitriles and the lithium rechargeable battery that contains this electrolyte
Technical field
The present invention designs lithium ion battery preparation field, is specifically related to a kind of electrolyte that contains benzene three nitriles and contains this electrolyteLithium rechargeable battery.
Background technology
Lithium ion battery because its specific energy is high, volume is little, quality is light, memory-less effect, the advantage extensive use such as have extended cycle lifeIn portable electric appts. But, along with the fast development of portable type electronic product, propose more next to the specific energy of lithium ionHigher requirement.
But be full of under electricity condition, the whole chemical system of lithium rechargeable battery has high chemism. When electronics producesWhen product continue to use or environment temperature raises, all may make lithium rechargeable battery in the condition of high temperature, at this moment as anodal activeThe metal oxide of material demonstrates very strong oxidisability, and easy and electrolyte generation oxidation reaction, causes electrolyte decomposition.In addition,, along with the high voltage words of lithium rechargeable battery, electrolyte can aggravate in the oxidation Decomposition on anodal surface, causes lithium ionThe storge quality of secondary cell declines. Therefore, suppressing electrolyte and positive electrode active materials oxidation reaction is before to prevent lithium ionThe key that secondary cell high-temperature storage performance worsens.
Current in order to improve the energy density of lithium rechargeable battery, mainly to adopt some nickel element content the to increase active material of positive poleMaterial, as nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide etc. But the positive electrode active materials of high nickel content at charge cutoff voltageGao Shi, can improve positive plate oxidation uh management, cause the problem of oxidation of electrolyte more serious. Therefore for this high-energyPositive electrode active materials or when lithium rechargeable battery is in the time that high voltage uses, solve the decomposition of electrolyte particularly urgent.
Summary of the invention
In view of the existing problem of background technology, the object of the present invention is to provide a kind of electrolyte for lithium ion battery, itsOperating voltage, in the time that 4.2V is above, can effectively suppresses the oxidation of electrolyte and improve the high-temperature storage characteristics of lithium rechargeable batteryCan, solving that lithium rechargeable battery stores at high pressure-temperature is the decomposition of the electrolyte that causes and the lithium ion secondary electricity causing thusThe problem of pond inflatable.
The present invention is achieved through the following technical solutions:
An electrolyte that contains benzene three nitriles, comprises organic solvent, electric conducting lithium salt and additive, wherein: described organic solvent choosingFor cyclic carbonate and linear carbonates more than one, described additive structural formula (1) is as follows:
The service property (quality) of described additive is equivalent to 0.1%~10% of described lithium salts and described organic solvent gross mass.
Described organic solvent comprises cyclic carbonate ester solvent and linear carbonate solvent, and cyclic carbonate ester solvent and linear carbonate are moltenThe proportioning of agent is that mass ratio is 1:1~3:2, and the final concentration of electric conducting lithium salt is 0.8~1.5mol/L.
Described cyclic carbonate ester solvent be ethylene carbonate, propene carbonate, fluorinated ethylene carbonate, gamma-butyrolacton and γ-More than one in valerolactone.
Described linear carbonate solvent be in dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate or methyl propyl carbonate at leastA kind of.
Described electric conducting lithium salt is lithium hexafluoro phosphate (LiPF6), LiBF4 (LiBF4), dioxalic acid lithium borate (LiBOB), twoFluorine Lithium bis (oxalate) borate (LiDFOB), trifluoromethyl sulfonic acid lithium (LiSO3CF3), lithium perchlorate (LiClO4), hexafluoroarsenate lithium(LiAsF6), bis trifluoromethyl sulfimide lithium (Li (CF3SO2)2N) at least one in.
Described electrolyte also comprises conventional additive, described typical additives be vinylene carbonate, vinylethylene carbonate,Propane sultone, butyl sultone, sulfuric acid vinyl ester, adiponitrile, succinonitrile, LiBOB, LiDFOB, in more than one,Described typical additives accounts for the 0.1-5.0% of nonaqueous electrolytic solution gross mass.
Another object of the present invention is to provide the preparation side of the described electrolyte that contains benzene three nitriles for lithium rechargeable batteryMethod.
A kind of preparation method of electrolyte:
(1) organic solvent is mixed to rear use in proportionMolecular sieve, calcium hydride, lithium hydride clarification, dewater;
(2) at ambient temperature, electric conducting lithium salt is dissolved in above-mentioned organic solvent, and stirs;
(3) add typical additives, and stir; Add additive, make the electrolyte that contains benzene three nitriles of the present invention.
A kind of lithium rechargeable battery, comprises positive electrode active materials, negative active core-shell material and barrier film, also comprises of the present inventionThe electrolyte that contains benzene three nitriles.
Described positive electrode active materials is a kind of lithium-containing transition metal oxide, more than one that positive electrode active materials is following material:LiCoO2、LiNiO2、LiMnO2、LiMn2O4、Li(NiaCobMnc)O2(0<a<1,0<b<1,0<C<1,a+b+C=1)、 LiNi1-yMnyO2、LiNi1-yMnyO2(0≦z≦2)、LiMx(PO4)y(M is Ni, Co, Mn, Ti, V, 0≤x≤5,0≤y≤ 5); Negative active core-shell material be one in material with carbon element, lithium metal, silicon or tin and the oxide thereof that can embed/deviate from lithium ion withOn; Barrier film be from weaving cotton cloth, nonwoven, synthetic resin micro-porous film any.
The invention has the advantages that:
Described benzene three nitriles and transition metal have stronger complexing, can effectively suppress the stripping of positive plate transition metal,Can, at positive plate surface enrichment, form layer protecting film, suppress the catalytic decomposition of electrolyte component on positive plate surface, therebyImprove the high-temperature storage performance of secondary cell.
Detailed description of the invention
Further detailed explanation the present invention of following examples, but the present invention is not limited to this embodiment.
Below in conjunction with embodiment, the present invention is described in further detail, but embodiments of the present invention are not limited to this.
Embodiment 1
(1) by cyclic carbonate ester solvent ethylene carbonate (EC) and linear carbonate solvent methyl ethyl carbonate (EMC), diethyl carbonate(DEC) EC: EMC:DEC=3:5:2 mixes in mass ratio, and adopts molecular sieve, calcium hydride, lithium hydride pureEliminate assorted, dewater;
(2) at ambient temperature, by electric conducting lithium salt LiPF6Be dissolved in the solvent that step (1) obtains, final concentration is 1.0mol/L, stirsMix evenly, obtain common electrolyte;
(3) in the common electrolyte of preparing in step (2), be added into TFMS trifluoro ethyl ester, consumption is electrolyte quality1.5%; Obtain the high-voltage electrolyte for lithium ion battery.
Embodiment 2
(1) by cyclic carbonate ester solvent ethylene carbonate (EC) and linear carbonate solvent methyl ethyl carbonate (EMC), diethyl carbonate(DEC) EC: EMC:DEC=3:5:2 mixes in mass ratio, adopts molecular sieve, calcium hydride, lithium hydride purifyingRemoval of impurities, dewater;
(2) at ambient temperature, by electric conducting lithium salt LiPF6Be dissolved in the solvent that step (1) obtains, final concentration is 1mol/L, stirsMix evenly, be made into common electrolyte;
(3) in the common electrolyte of preparing in step (2), add TFMS trifluoro ethyl ester, consumption is electrolyte quality 0.5%;Obtain the high voltage functionality electrolyte for lithium ion battery.
Embodiment 3
(1) by cyclic carbonate ester solvent ethylene carbonate (EC) and linear carbonate solvent methyl ethyl carbonate (EMC), diethyl carbonate(DEC) EC: EMC:DEC=3:5:2 mixes in mass ratio, adopts molecular sieve, calcium hydride, lithium hydride purifying to removeMix, dewater;
(2) at ambient temperature, by electric conducting lithium salt LiPF6Be dissolved in the solvent that step (1) obtains, final concentration is 1.0mol/L,Stir, be made into common electrolyte;
(3) in the common electrolyte of preparing in step (2), add TFMS trifluoro ethyl ester, consumption is electrolyte quality 1%; ?To the boracic film forming function electrolyte for lithium ion battery.
Embodiment 4
(1) by cyclic carbonate ester solvent ethylene carbonate (EC) and linear carbonate solvent methyl ethyl carbonate (EMC), diethyl carbonate(DEC) EC: EMC:DEC=3:5:2 mixes in mass ratio, adopts molecular sieve, calcium hydride, lithium hydride purifyingRemoval of impurities, dewater;
(2) at ambient temperature, by electric conducting lithium salt LiClO4Be dissolved in the solvent that step (1) obtains, final concentration is 1.0mol/L,Stir, be made into common electrolyte;
(3) in the common electrolyte of preparing in step (2), add TFMS trifluoro ethyl ester, consumption is electrolyte quality 2%; ?To the high-voltage electrolyte for lithium ion battery.
Embodiment 5
(1) by cyclic carbonate ester solvent ethylene carbonate (EC) and linear carbonate solvent methyl ethyl carbonate (EMC), diethyl carbonate(DEC) EC: EMC:DEC=3:5:2 mixes in mass ratio, adopts molecular sieve, calcium hydride, lithium hydride purifyingRemoval of impurities, dewater;
(2) at ambient temperature, by electric conducting lithium salt LiAsF6Be dissolved in the solvent that step (1) obtains, final concentration is 1.2mol/L,Stir, be made into common electrolyte;
(3) in the common electrolyte of preparing in step (2), add TFMS trifluoro ethyl ester, consumption is electrolyte quality2%; Obtain the high-voltage electrolyte for lithium ion battery.
Embodiment 6
(1) by cyclic carbonate ester solvent ethylene carbonate (EC) and linear carbonate solvent methyl ethyl carbonate (EMC), diethyl carbonate(DEC) EC: EMC:DEC=3:5:2 mixes in mass ratio, adopts molecular sieve, calcium hydride, lithium hydride purifyingRemoval of impurities, dewater;
(2) at ambient temperature, by electric conducting lithium salt Li (CF3SO2)2N is dissolved in the solvent that step (1) obtains, and final concentration is1.2mol/L, stirs, and is made into common electrolyte;
(3) in the common electrolyte of preparing in step (2), add TFMS trifluoro ethyl ester, consumption is electrolyte quality 1.5%;Obtain the high-voltage electrolyte for lithium ion battery.
Embodiment 7
(1) by cyclic carbonate ester solvent ethylene carbonate (EC) and linear carbonate solvent methyl ethyl carbonate (EMC), diethyl carbonate(DEC) EC: EMC:DEC=3:5:2 mixes in mass ratio, adopts molecular sieve, calcium hydride, lithium hydride purifyingRemoval of impurities, dewater;
(2) at ambient temperature, by electric conducting lithium salt LiC (CF3SO2)3Be dissolved in the solvent that step (1) obtains, final concentration is1.2mol/L, stirs, and is made into common electrolyte;
(3) in the common electrolyte of preparing in step (2), add TFMS trifluoro ethyl ester, consumption is electrolyte quality 0.5%;Obtain the high-voltage electrolyte for lithium ion battery.
The high-voltage electrolyte of lithium ion battery prepared embodiment 1-7 and common electrolyte are assembled into lithium secondary battery, and performance is as followsTable
Above-described embodiment is preferably embodiment of the present invention, but embodiments of the present invention are not restricted to the described embodiments,Other any do not deviate from change, the modification done under Spirit Essence of the present invention and principle, substitutes, combination, simplify, all shouldFor equivalent substitute mode, within being included in protection scope of the present invention.