A kind of high-voltage lithium-ion battery electrolyte and use the lithium ion battery of this electrolyte
Technical field
The present invention relates to field of lithium ion battery, be specifically related to a kind of high-voltage lithium-ion battery electrolyte and use the lithium ion battery of this electrolyte.
Background technology
In recent years, along with the multifunction of the electronic product such as mobile phone, panel computer, consumer requires also more and more higher to the energy density of lithium ion battery.
At present, in order to improve lithium ion battery energy density, mainly through improving active material compacted density and selecting the positive electrode active materials that charge cutoff current potential is higher, as: high voltage lithium and cobalt oxides, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, Li, Ni, Mn oxide etc.But improve positive electrode active materials charge cutoff current potential and can improve its oxidation activity, when facing the conditions of high temperature such as ambient temperature rising, continuous discharge heating when lithium ion battery, more accelerate the reaction of active material and electrolyte, so cause cell expansion even to blast, the security incident such as burning.Therefore, the electrolyte that developing electrode/electrolyte interface compatibility is good, oxidative resistance is strong, wettability is good is one of key improving lithium ion battery energy density and security performance.
Present stage, lithium-ion battery electrolytes generally adopted the solvent of cyclic carbonate and linear carbonate to combine, electrolyte viscosity is higher, be applied in high-pressure solid battery system, the wettability of electrolyte to electrode material and barrier film is poor, easily affects battery capacity and plays and reduce battery cycle life.Select the carboxylate solvent that viscosity is low, liquid journey is wide in the electrolytic solution, electrolytic conductivity and the wetting property to pole piece can be significantly improved, increase discharge capacity of the cell, reduce the real battery cryogenic conditions of high voltage under analyse lithium.
But carbonate-based solvent of comparing, carboxylate solvent is easily in negative terminal surface reduction deposition in cyclic process, and hot conditions stability inferior also shows slightly not enough.Therefore need to select suitable additive combination, to improve electrolyte and both positive and negative polarity interface stability, reduce the capacity attenuation in battery use procedure and high temperature aerogenesis.
Summary of the invention
In view of Problems existing in background technology, the object of the present invention is to provide a kind of high-voltage lithium-ion battery electrolyte and use the lithium ion battery of this electrolyte, the reaction of effective suppression more than 4.35V high-voltage battery active material and electrolyte, improves lithium ion battery energy density, improves lithium ion battery circulation and high-temperature storage performance.
To achieve these goals, the technical solution used in the present invention is:
A kind of high-voltage lithium-ion battery electrolyte, comprises non-aqueous organic solvent, lithium salts and additive, and described non-aqueous organic solvent comprises carbonate solvent and accounts for the carboxylate solvent that electrolyte quality percentage is 5 ~ 50%; Described additive package is containing Hydrofluoroether compounds and at least one sulfonic acid that has in general formula I, general formula I I, cyclic disulfonic acid acid anhydride represented by general formula III, chain disulfonate, cyclic disulfonic acid ester:
In general formula I ~ III: m, p, n are respectively the integer of 1 ~ 5, R
1, R
2for carbon number is the alkyl of 1 ~ 3.
Described sulfonic acid be following material any one and more than: ethylene-sulfonic acid acid anhydride, 1,3-propylene acid anhydride, Isosorbide-5-Nitrae-butylidene disulfonic acid acid anhydride, 1,5-pentylidene disulfonic acid acid anhydride, Busulfan, methane-disulfonic acid methylene ester.
Described sulfonic acid quality accounts for 0.5% ~ 5.0% of described electrolyte gross mass.
Described hydrogen fluorine ether be following material any one and more than: CF
2hCF
2cH
2oCF
2cF
2h, CF
3cFHCF
2cH (CH
3) OCF
2cFHCF3, CF
3cFHCF
2oCH
2cF
3, CF
3cF (CF
3) CF (CF
2cF
3) OCH
3.
Described hydrogen fluorine ether quality accounts for 1.0% ~ 10.0% of described electrolyte gross mass.
Described carbonate solvent is one or the combination of following material: ethylene carbonate, propene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate; Described carboxylate solvent is one or the combination of following material: n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, n propyl propionate, methyl butyl, ethyl butyrate.
Described lithium salts is LiPF
6, in LiFSI, LiTFSI, LiDFOB, LiBOB any one and more than.
Described additive also comprise in vinylene carbonate, 1,3-propane sultone, sulfuric acid vinyl ester, fluorinated ethylene carbonate, succinonitrile, adiponitrile, ethylene glycol bis (propionitrile) ether any one and more than; It accounts for 0.5% ~ 10.0% of lithium-ion battery electrolytes gross mass.
A kind of lithium ion battery: comprise positive plate, negative plate, barrier film and above-described high-voltage lithium-ion battery electrolyte; Described positive plate active material be cobalt acid lithium, LiMn2O4, nickle cobalt lithium manganate, nickel cobalt lithium aluminate or nickel ion doped in any one, described negative plate active material be in Delanium, native graphite, Si-C composite material, lithium titanate any one.
The invention has the advantages that:
1, the present invention selects viscosity is low, liquid journey is wide carboxylate as one of main solvent, can significantly improve electrolytic conductivity and the wetting property to pole piece, increase discharge capacity of the cell, reduce the real battery cryogenic conditions of high voltage under analyse lithium.In addition, low viscous carboxylate solvent effectively can also shorten the battery liquid-filling time, improve battery multiplying power property.
2, the sulfonic acid additive that the present invention selects has good filming performance, at the interface diaphragm good stability that electrode surface is formed, can effectively suppress the capacity attenuation of battery in cyclic process and the aerogenesis under hot environment to expand.
3, the fluorocarbon chain in hydrogen fluorine ether can improve electrolyte to the wettability of electrode material, reduce electrode interface impedance; The replacement of fluorine element simultaneously improves the oxidizing potential of ether compound, hydrogen fluorine ether joins in electrolyte as additive, can effectively strengthen electrolyte oxidative resistance, reduce electrolyte in the decomposition reaction of electrode surface, improve battery high voltage cycle performance and storge quality.
Accompanying drawing explanation
Fig. 1 is graphite/LiNi prepared by the lithium-ion battery electrolytes of embodiment 1 and comparative example 1
0.5mn
0.3co
0.2o
2battery 3.0V ~ 4.35V1C cycle charge-discharge test capacity comparison diagram.
Embodiment
Be described further the present invention below in conjunction with embodiment, enforcement of the present invention includes but not limited to following execution mode.Any do not depart from content of the present invention change or replace and can be understood by those skilled in the art, all should within protection scope of the present invention.
The preparation of electrolyte is carried out in the glove box being full of argon gas.Preparing process is as follows: mixed by each solvent first in proportion, then adds each additive in component design ratio, after solution to be mixed fully cools, slowly adds required electrolyte lithium salt, is fully uniformly mixed and obtains required electrolyte.
The quality proportioning of specific embodiment and comparative example lists in table 1:
Lithium-ion battery electrolytes proportioning shown in table 1 prepared injects through fully dry graphite/LiNi
0.5mn
0.3co
0.2o
2battery, battery leaves standstill through an envelope, preliminary filling changes into, carry out 3.0V ~ 4.35V1C cycle charge discharge electrical testing after two envelope partial volumes and the full electric state 85 DEG C/6H of 4.35V stores test.
3.0V ~ 4.35V1C cycle charge discharge electrical testing:
Under the condition of room temperature 25 ± 2 DEG C, carry out the test of 3.0V-4.35V circulating battery to embodiment and comparative example experimental cell, testing procedure is: A, 1C constant current charge is to 4.35V, and then constant voltage charge is to cut-off current 0.01C, leaves standstill 5 minutes; B, 1C constant-current discharge, to 3.0V, leaves standstill 5 minutes; C, circulation step A and B, cycle-index is 500 times.
The full electric state 85 DEG C/6H of 4.35V stores test:
A, under the condition of room temperature 25 ± 2 DEG C, 0.5C charge-discharge test is carried out to embodiment and comparative example experimental cell, capacity before record stores; B, 0.5C constant-current constant-voltage charging is to 4.35V, and cut-off current is 0.01C, the full electric state thickness of test battery; C, full electric state battery is transferred in 85 DEG C of insulating boxs, stores the hot thickness of test battery after 6 hours, thickness * 100% before hot thickness swelling=(before the hot thickness-storage of battery thickness)/store; D, by cooled battery 0.5C constant-current discharge to 3.0V, residual capacity after record stores, the front capacity * 100% of residual capacity/storage after battery capacity surplus ratio=storages; E, battery is carried out 0.5C charge-discharge test again, record can recover capacity after storing, and can recover the front capacity * 100% of capacity/storages after capacity resuming rate=storage.
Test result is as shown in table 2:
From Comparative result in table 2:
1, in electrolyte, add any one sulfonic acid in the present invention and hydrogen fluorine ether can improve battery high voltage cycle performance and storge quality, effectively improve battery 500 cycle circulation volume conservation rate and suppress high-temperature storage aerogenesis, increase store after battery capacity surplus ratio and capacity restoration rate.
2, carboxylate of the present invention is introduced as one of electrolyte main solvent, battery capacity can be made to play maximize and improve cycle performance, simultaneously because sulfonate derivatives and hydrogen fluorine ether are to the improvement result of electrolyte/electrode interface, the Stability Bound facial mask formed ensure that carboxylate stability, and carboxylic acid ester groups electrolyte is applied in high-voltage battery has good high-temperature storage performance.
Be more than illustrating for section Example of the present invention, not for limiting the scope of the claims of the present invention, all change or replacements not departing from content of the present invention, all should within protection scope of the present invention.