WO2018099092A1 - 一种非水电解液及锂离子电池 - Google Patents

一种非水电解液及锂离子电池 Download PDF

Info

Publication number
WO2018099092A1
WO2018099092A1 PCT/CN2017/093197 CN2017093197W WO2018099092A1 WO 2018099092 A1 WO2018099092 A1 WO 2018099092A1 CN 2017093197 W CN2017093197 W CN 2017093197W WO 2018099092 A1 WO2018099092 A1 WO 2018099092A1
Authority
WO
WIPO (PCT)
Prior art keywords
lithium
electrolyte
salt
substituted
group
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2017/093197
Other languages
English (en)
French (fr)
Inventor
张昌明
付成华
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Contemporary Amperex Technology Co Ltd
Original Assignee
Contemporary Amperex Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Contemporary Amperex Technology Co Ltd filed Critical Contemporary Amperex Technology Co Ltd
Publication of WO2018099092A1 publication Critical patent/WO2018099092A1/zh
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • 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
    • 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
    • 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

Definitions

  • the present application relates to the field of lithium battery technology, and in particular to a non-aqueous electrolyte and a lithium ion battery.
  • Lithium-ion batteries are widely used in consumer electronics and energy storage and power batteries because of their high specific energy, long cycle life and low self-discharge. With the wide application of lithium-ion batteries, the use environment has long been versatile, and the requirements for battery life and safety performance are getting higher and higher. For example, the battery still has a long life in the case of rapid charging and discharging at a large rate, and there is no safety risk when working at a high temperature for a long time.
  • the life and safety performance of lithium-ion batteries are affected by many factors. Among them, non-aqueous electrolytes have an important impact on them as an important part of lithium-ion batteries.
  • the non-aqueous electrolyte can improve the dynamic performance of the battery, reduce the stability of the positive and negative interfaces in the polarization, cycle and high-temperature storage process, thereby achieving the purpose of improving the life and safety performance.
  • One of the objects of the present application is to provide a nonaqueous electrolyte.
  • the second object of the present application is to provide a lithium ion battery.
  • the present application relates to a nonaqueous electrolyte comprising an organic solvent, an electrolyte salt and an additive, the additive comprising a barbituric acid compound and an additive lithium salt, the additive lithium salt being different from the electrolyte salt.
  • the barbituric acid compound is selected from at least one of the compounds represented by the formula (I).
  • R 11, R 12 are each independently selected from substituted or unsubstituted C 1 ⁇ 12 alkyl group, a substituted or unsubstituted C 2 ⁇ 12 alkylene group, a substituted or unsubstituted C 6 ⁇ 26 aryl group;
  • R 13, R 14 are each independently selected from hydrogen, an amino group, a substituted or unsubstituted C 1 ⁇ 12 alkyl group, a substituted or unsubstituted C 2 ⁇ 12 alkylene group, a substituted or unsubstituted C 6 ⁇ 26 aryl group, -NH-R', wherein R' is a substituted or unsubstituted C 1-4 alkyl group;
  • X is selected from O or S
  • the substituent is selected from halogen.
  • R 11 and R 12 are each independently selected from a substituted or unsubstituted C 1-5 alkyl group, a substituted or unsubstituted phenyl group;
  • R 13 and R 14 are each independently selected from hydrogen, substituted or unsubstituted C 1-5 alkyl, substituted or unsubstituted phenyl, amino.
  • the barbituric acid compound is selected from at least one of the following compounds,
  • the barbituric acid compound is contained in the non-aqueous electrolyte in an amount of 0.01% to 3% by mass; preferably 0.05% to 2%.
  • the electrolyte salt is lithium hexafluorophosphate.
  • the additive lithium salt is selected from at least one of a sulfonimide lithium salt, a boron-containing lithium salt, and a fluorine-containing lithium phosphate salt; preferably, the lithium sulfonimide salt is selected from the group consisting of bistrifluoromethanesulfonyl Lithium imide and/or lithium bis(fluorosulfonyl)imide, the boron-containing lithium salt being selected from at least one of lithium bis(oxalate)borate, lithium difluorooxalate borate, and lithium tetrafluoroborate, the fluorine-containing phosphoric acid
  • the lithium salt is lithium difluorophosphate.
  • the electrolyte salt is contained in the non-aqueous electrolyte in an amount of 0.5% to 30% by mass; preferably 10% to 20%.
  • the additive lithium salt is contained in the non-aqueous electrolyte in an amount of 0.01% to 5% by mass; preferably 0.1% to 2%.
  • the present application relates to a lithium ion battery comprising a positive electrode sheet, a negative electrode sheet, a separator disposed between the positive electrode sheet and the negative electrode sheet, and the foregoing electrolyte solution.
  • the present application by using a barbituric acid compound and an additive lithium salt as an additive, not only forms a stable passivation film on the surface of the battery positive electrode, but also contains an inorganic salt substance on the passivation film. .
  • the solvent can be isolated, the positive electrode active material can be inhibited from being oxidized by the electrolyte, the lithium ion migration rate can be enhanced, the polarization can be reduced, and the kinetic performance of the battery and the performance of the hot box after the cycle can be remarkably improved.
  • the present application relates to a non-aqueous electrolyte comprising an organic solvent, an electrolyte salt and an additive.
  • the additive of the present application contains both a barbituric acid compound and an additive lithium salt different from the electrolyte salt.
  • the oxidation potential of barbituric acid compounds is lower than that of solvents, and can be oxidized and polymerized on the surface of the positive electrode of the cell to form a dense solid electrolyte phase interface film (CEI), effectively reducing the solvent in the positive electrode.
  • the decomposition is very beneficial to the performance of the battery; this is because the polymer formed of the barbituric acid compound and lithium covers the surface of the positive electrode more difficult to be dissolved by the solvent than the alkyl lithium, and the CEI is more stable.
  • the side reaction between the positive electrode material and the non-aqueous electrolyte on the surface of the positive electrode can be effectively prevented, and the increase in the impedance of the positive electrode interface during the cycle can be effectively reduced, and the capacity loss caused by the polarization of the positive electrode during the cycle can be reduced.
  • the barbituric acid compound is polymerized into a film, elution of elements such as Mn and Co of the positive electrode material can be prevented, and oxidation of the non-aqueous electrolyte can be suppressed to cause the battery to expand.
  • the electrolyte salt compound has good thermal stability, high electrical conductivity in the electrolyte, and low viscosity, which can reduce the concentration polarization of the electrolyte and improve the kinetic performance.
  • Certain electrolyte salts such as the lithium salt of the additive in the present application, are easily reacted at high potential to form inorganic salts such as borate, phosphate or nitrofluoride, which facilitate the transport of lithium ions. Therefore, after the barbituric acid compound is combined with the additive lithium salt, a stable passivation film is formed on the positive electrode of the battery, and an inorganic salt substance is also interposed on the passivation film.
  • the positive electrode is not oxidized by the electrolyte, but also the lithium ion migration rate can be enhanced, and the polarization can be reduced, thereby significantly improving the cycle performance, rate performance and cycle performance of the battery after the cycle.
  • the barbituric acid compound of the present application is selected from at least one of the compounds represented by the formula (1).
  • R 11, R 12 are each independently selected from substituted or unsubstituted C 1 ⁇ 12 alkyl group, a substituted or unsubstituted C 2 ⁇ 12 alkylene group, a substituted or unsubstituted C 6 ⁇ 26 aryl group;
  • R 13, R 14 are each independently selected from hydrogen, an amino group, a substituted or unsubstituted C 1 ⁇ 12 alkyl group, a substituted or unsubstituted C 2 ⁇ 12 alkylene group, a substituted or unsubstituted C 6 ⁇ 26 aryl group, -NH-R', wherein R' is a substituted or unsubstituted C 1-4 alkyl group;
  • X is selected from O or S
  • the substituent is selected from halogens such as F and Cl.
  • R 11 and R 12 are each independently selected from substituted or unsubstituted C 1-6 alkyl, substituted or unsubstituted C 2-6 alkenyl, substituted or unsubstituted phenyl;
  • R 13 and R 14 are each independently selected from hydrogen, substituted or unsubstituted C 1-6 alkyl, substituted or unsubstituted C 2-6 alkenyl, substituted or unsubstituted phenyl, substituted or unsubstituted An amino group of C 1-6, an amino group, or an imino group substituted by a C 1-6 alkyl group.
  • R 11 and R 12 are each independently selected from a substituted or unsubstituted C 1-5 alkyl group, a substituted or unsubstituted phenyl group;
  • R 13 and R 14 are each independently selected from hydrogen, substituted or unsubstituted C 1-5 alkyl, substituted or unsubstituted phenyl, amino.
  • an alkyl group having 1 to 12 carbon atoms may be a chain alkyl group or a cycloalkyl group, and the hydrogen group on the ring of the cycloalkyl group may be substituted by an alkyl group, and the number of carbon atoms in the alkyl group Preferred lower limit values are 2, 3, 4, 5, and preferred upper limit values are 3, 4, 5, 6, 8, 10, 12.
  • an alkyl group having 1 to 10 carbon atoms is selected, and more preferably, a chain alkyl group having 1 to 6 carbon atoms and a cycloalkyl group having 3 to 8 carbon atoms are selected, and still more preferably, A chain alkyl group having 1 to 5 carbon atoms is selected.
  • alkyl group examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, and new. Pentyl, cyclopentyl, cyclohexyl.
  • the alkenyl group having 2 to 12 carbon atoms may be a cyclic alkenyl group or a chain alkenyl group. Further, the number of double bonds in the alkenyl group is preferably one.
  • the lower limit of the number of carbon atoms in the alkenyl group is preferably 2, 3, 4, and the preferred upper limit is 3, 4, 5, 6, 8, 10, 12.
  • an alkenyl group having 2 to 10 carbon atoms is selected, and more preferably an alkenyl group having 2 to 6 carbon atoms is selected, and more preferably an alkenyl group having 2 to 5 carbon atoms is selected.
  • alkenyl group examples include a vinyl group, an allyl group, an isopropenyl group, a pentenyl group, a cyclohexenyl group, a cycloheptenyl group, and a cyclooctenyl group.
  • An aryl group having 6 to 26 carbon atoms such as a phenyl group, a phenylalkyl group, an aryl group containing at least one phenyl group such as a biphenyl group, a fused ring aromatic hydrocarbon group such as naphthalene, anthracene or phenanthrene, a biphenyl group and a thick group.
  • Cycloaromatic hydrocarbon groups can also It is substituted by an alkyl group or an alkenyl group.
  • an aryl group having 6 to 16 carbon atoms is selected, and more preferably, an aryl group having 6 to 14 carbon atoms is selected, and even more preferably an aryl group having 6 to 9 carbon atoms is selected.
  • Specific examples of the aryl group include a phenyl group, a benzyl group, a biphenyl group, a p-tolyl group, an o-tolyl group, and an m-tolyl group.
  • alkyl group having 1 to 12 carbon atoms, alkenyl group having 2 to 12 carbon atoms, or aryl group having 6 to 26 carbon atoms is substituted by a halogen atom, the corresponding number of carbon atoms is sequentially formed.
  • a halogenated alkyl group of 1 to 12 a halogenated alkenyl group having 2 to 12 carbon atoms, or a halogenated aryl group having 6 to 26 carbon atoms, wherein the halogen atom is F, Cl or Br, and preferably F or Cl.
  • the halogen atom may be substituted for a part of hydrogen atoms or all hydrogen atoms, and the number of halogen atoms may be 1, 2, 3 or 4.
  • a halogenated alkyl group having 1 to 10 carbon atoms, a halogenated alkenyl group having 2 to 10 carbon atoms, or a halogenated aryl group having 6 to 16 carbon atoms is selected, and more preferably, the number of carbon atoms is selected.
  • a halogenated chain alkyl group having 1 to 4 carbon atoms, a halogenated cycloalkyl group having 5 to 7 carbon atoms, a halogenated alkenyl group having 2 to 5 carbon atoms, and carbon are selected.
  • the atom is a halogenated aryl group of 6 to 10.
  • halogenated group examples include trifluoromethyl (-CF 3 ), 2-fluoroethyl, 3-fluoro-n-propyl, 2-fluoroisopropyl, 4-fluoro-n-butyl, 3-fluorosec-butyl, 5-fluoro-n-pentyl, 4-fluoroisopentyl, 1-fluorovinyl, 3-fluoroallyl, 6-fluoro-4-hexenyl, o-fluorophenyl, p- Fluorophenyl, m-fluorophenyl, 4-fluoromethylphenyl, 2,6-difluoromethylphenyl, 2-fluoro-1-naphthyl, fluoromethoxy, 1-fluoroethoxy, 2-fluoro-n-propoxy, 1-fluoro-isopropoxy, 3-fluoro-n-butoxy, 4-fluoro-n-pentyloxy, 2,2-difluoromethylpropoxy, 5- Fluoro
  • the barbituric acid compound is selected from at least one of the following compounds:
  • the barbituric acid compound of the present application is further selected from at least one of the following compounds, but is not limited thereto:
  • the mass percentage of the barbituric acid compound of the present application in the nonaqueous electrolytic solution is 0.01% to 3%.
  • the content of the barbituric acid compound is less than 0.01%, a complete and effective CEI film cannot be formed on the surface of the positive electrode, thereby failing to effectively prevent side reactions caused by electron transfer between the nonaqueous electrolyte and the electrode;
  • the content of the bitter acid compound is more than 3%, a thick CEI film is formed on the surface of the positive electrode, which leads to an increase in lithium ion migration resistance, which is disadvantageous to the stability of the positive electrode interface of the battery during the cycle.
  • the upper limit of the mass percentage range of the barbituric acid compound in the non-aqueous electrolyte solution is selected from the group consisting of 3%, 2.8%, 2.5%, 2.0%, 1.5%, and 1.0%, and the lower limit is selected from the lower limit. 0.01%, 0.03%, 0.05%, 0.1%, 0.3%, 0.5%, 0.6%. Still more preferably, the percentage of the barbituric acid compound in the non-aqueous electrolyte is from 0.05% to 2%.
  • Lithium hexafluorophosphate (LiPF 6 ) is the most widely used lithium salt in commercial lithium batteries because it is compared with other additive lithium salts.
  • the electrochemical window is wide, the electrochemical stability is strong, and the aluminum current collector is not corroded, the synthetic route is mature, and the comprehensive performance is superior to other lithium salts, so it is used as the electrolyte salt in the non-aqueous electrolyte of the present application.
  • the decomposition temperature of lithium hexafluorophosphate is 80 ° C, the thermal stability is poor, and it can be decomposed even in a high purity state.
  • the decomposition products are lithium fluoride (LiF) and phosphorus pentafluoride (PF 5 ).
  • the gaseous PF 5 has a strong Lewis acidity and reacts with the lone pair of oxygen atoms in the solvent molecule to decompose the solvent.
  • other kinds of lithium salts have better thermal stability and film forming properties. Therefore, the present application further uses an additive lithium salt in the additive to make up for the disadvantage that lithium hexafluorophosphate is easily decomposed at 80-90 ° C.
  • the additive lithium salt is selected from at least one of a sulfonimide lithium salt, a boron-containing lithium salt, and a fluorine-containing lithium phosphate; further preferably a bistrifluoromethanesulfonimide Lithium LiN(CF 3 SO 2 ) 2 (abbreviated as LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO 2 F) 2 ) (abbreviated as LiFSI), lithium bis(oxalate)borate LiB (C 2 O 4 ) 2 (abbreviated as LiBOB), lithium difluorooxalate borate lithium difluorooxalate borate LiBF 2 (C 2 O 4 ) (abbreviated as LiDFOB), lithium difluorophosphate (LiPO 2 F 2 ), lithium tetrafluoroborate (LiBF 4) At least one of them.
  • LiTFSI bistrifluoromethanesulfonimide Lithium
  • the mass percentage of the electrolyte salt in the nonaqueous electrolyte is from 0.5% to 30%.
  • the conductivity of an electrolyte is proportional to the concentration of the electrolyte salt and inversely proportional to the viscosity of the solvent. Specifically, as the electrolyte salt concentration increases, the free ions that are electrolyzed also increase, thereby increasing the conductivity; but at the same time, the viscosity of the electrolyte and the degree of ion association are also It will increase as the electrolyte salt concentration increases, which in turn will lower the conductivity.
  • the upper limit of the mass percentage range of the electrolyte salt of the present application in the non-aqueous electrolyte is selected from 5%, 10%, 15%, 20%, 25%, 30%, and the lower limit is selected from 0.5%. 1%, 2%, 3%, 5%, 10%. Still more preferably, the percentage of the electrolyte salt in the non-aqueous electrolyte is from 10% to 20%. For a common electrolyte system, 15% by mass has both higher conductivity and relatively lower cost.
  • the mass percentage of the additive lithium salt in the nonaqueous electrolytic solution is 0.01% to 5%.
  • the content of the additive lithium salt in the non-aqueous electrolyte is too small, and the effect of forming a stable passivation film is not obvious when combined with the barbituric acid compound; when the lithium salt content of the additive is too large, a large amount of lithium ions in the electrolyte cause electrolysis.
  • the viscosity of the liquid and the internal resistance of the battery increase, which is not conducive to the improvement of electrochemical properties.
  • the upper limit of the mass percentage range of the additive lithium salt in the non-aqueous electrolyte solution is selected from 1%, 2%, 3%, 4%, 5%, and the lower limit is selected from 0.01%, 0.1%. , 0.5%, 0.3%, 0.5%, 1%.
  • the percentage of the additive lithium salt in the nonaqueous electrolytic solution is from 0.1% to 2%, more preferably from 1% to 2%.
  • the organic solvent of the present application is selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, fluoroethylene carbonate, ethyl methyl carbonate, and carbonic acid.
  • EC ethylene carbonate
  • PC propylene carbonate
  • DEC diethyl carbonate
  • dipropyl carbonate methyl propyl carbonate
  • ethylene propyl carbonate ethylene propyl carbonate
  • 1,4-butyrolactone 1,4-butyrolactone
  • methyl propionate methyl butyrate
  • propyl propionate acetic acid
  • acetic acid At least one of ethyl ester, ethyl propionate, and ethyl butyrate.
  • the present application also relates to a lithium ion battery comprising a positive electrode sheet, a negative electrode sheet, a separator disposed between the positive electrode sheet and the negative electrode sheet, and an electrolyte; the electrolyte solution is a non-aqueous electrolyte solution according to any of the preceding paragraphs. .
  • the present application also provides a lithium ion battery comprising a positive electrode sheet, a negative electrode sheet, a separator disposed between the positive electrode sheet and the negative electrode sheet, an electrolyte solution, and a packaging foil;
  • the positive electrode sheet includes a cathode current collector and coating A positive electrode membrane on a positive electrode current collector, the negative electrode sheet comprising a negative electrode current collector and an negative electrode film coated on the negative electrode current collector;
  • the electrolyte solution being the non-aqueous electrolyte solution according to any of the preceding paragraphs.
  • the positive electrode film of the present application includes a positive electrode active material Materials, binders and conductive agents.
  • the positive electrode active material of the present application is at least one selected from the group consisting of lithium cobaltate LiCoO 2 , lithium nickel manganese cobalt ternary material, lithium (lithium) phosphate, and lithium manganate.
  • the positive electrode active material of the present application is a mixture of lithium cobaltate and lithium nickel manganese cobalt ternary material.
  • the negative electrode film of the present application includes a negative electrode active material, a binder, and a conductive agent.
  • the anode active material of the present application is graphite and/or silicon.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PC propionic acid B in an argon atmosphere glove box with a water content of ⁇ 10 ppm
  • the ester was uniformly mixed at a mass ratio of 20:30:20:30 to obtain a nonaqueous solvent, and the sufficiently dried electrolyte salt LiPF 6 was dissolved in the above nonaqueous solvent to prepare a base electrolyte.
  • Examples of the barbituric acid compound are: 1,3-dimethylbarbituric acid (B1, as shown in Formula I-1), and 1,3-dibutylbarbituric acid (B2, such as Formula I). -2), 1,3-diphenylbarbituric acid (B3, as shown in Formula I-3), 1,3-dimethyl-2-thiobarbituric acid (B4, as in the formula I-4), 5-amino-2-thiobarbituric acid (B5, as shown in Formula I-5).
  • lithium salt as an additive examples include LiBF 4 , LiFSI, LiTFSI, LiBOB, LiDFOB, LiPO 2 F 2 .
  • Positive electrode sheet The positive electrode active material lithium cobaltate (LiCoO 2 molecular formula), conductive agent acetylene black, binder polyvinylidene fluoride (abbreviated as PVDF) in a weight ratio of 96:2:2 in an appropriate amount
  • the N-methylpyrrolidone (abbreviated as NMP) solvent was thoroughly stirred and mixed to form a uniform positive electrode slurry; the slurry was coated on a positive electrode current collector Al foil, dried, and cold pressed to obtain a positive electrode sheet.
  • NMP N-methylpyrrolidone
  • negative electrode sheet The negative electrode active material graphite, conductive agent acetylene black, binder styrene-butadiene rubber (abbreviated as SBR), thickener sodium carboxymethyl cellulose (abbreviated as CMC) according to the weight ratio of 95:2 2:1 was thoroughly stirred and mixed in an appropriate amount of deionized water solvent to form a uniform negative electrode slurry; the slurry was coated on a negative current collector Cu foil, dried, and cold pressed to obtain a negative electrode sheet.
  • SBR binder styrene-butadiene rubber
  • CMC thickener sodium carboxymethyl cellulose
  • Isolation film A PE porous polymer film is used as a separator.
  • the positive electrode sheet, the separator film and the negative electrode sheet are stacked in order, so that the separator is in the role of isolation between the positive electrode sheet and the negative electrode sheet, and then wound to obtain a bare cell;
  • the core is placed in the outer packaging foil, and the prepared electrolyte is injected into the dried battery, and after vacuum encapsulation, standing, formation, shaping, and the like, the preparation of the lithium ion battery is completed.
  • the electrolytic solutions and lithium ion batteries of Examples 1 to 20 and Comparative Examples 1 to 6 were prepared according to the above preparation methods; the additives in the electrolytic solution and the respective addition amounts thereof are shown in Table 1.
  • the prepared lithium ion batteries were each subjected to the following tests:
  • Lithium-ion battery is charged at different rates of 0.5C, 1C, 2C, 3C, 5C at 25 °C To 4.4 V, the charging capacity was recorded separately, and the capacity of charging at different rates was calculated with the capacitance of 0.5 C as a reference (100%). See Table 2 for the electrolytes selected for each lithium-ion battery and the relevant test data obtained.
  • the charging capacity at a large rate is improved, but the effect is not significant, as in Examples 12-15.
  • the increase in the content of the electrolyte salt is also unfavorable for the improvement of the charging capacity, as in Examples 19 and 20, because the electrical conductivity decreases as the viscosity of the electrolyte and the degree of ion association increase.
  • the prepared lithium ion batteries were each subjected to the following tests:
  • the lithium-ion battery is charged to 4.4V with a constant current of 1C, then charged to a current of 0.05C at a constant voltage, and then discharged to 3.0V with a constant current of 1C, which is the first cycle, according to the above
  • the conditions were carried out in such a plurality of cycles of charging/discharging, and the capacity retention ratios of the lithium ion batteries after 50, 100, 200, 300, and 500 cycles were calculated. There were 5 batteries in each group, and the capacity retention rate after the cycle was calculated according to the following formula.
  • the electrolytes selected for each of the lithium ion batteries and the relevant test data obtained are shown in Table 3.
  • the internal charge transfer of the battery can be satisfied.
  • the amount of the electrolyte salt when the amount of the electrolyte salt is controlled within the range of 10% to 20%, the cycle performance of the battery is mainly affected by the additive. . However, when the amount of the electrolyte salt is more than 20%, the content of the organic solvent in the electrolyte is lowered, and the cycle performance of the battery is attenuated.
  • the battery after 500 cycles of 25 °C will be charged at a constant current of 0.5 C at 25 ° C to 4.4 V, and charged at a constant voltage of 4.4 V until the current is 0.025 C, so that it is in a fully charged state of 4.4 V, and then the battery is charged. It was kept in a high temperature furnace at 150 ° C for 1 hour while testing the voltage change of the battery in the high temperature furnace and the surface temperature of the cell, and observing the state of the battery after the test. The results of the post-circulation hot box test are shown in Table 4.
  • Example 2 5/5OK Example 3 5/5OK Example 4 5/5OK Example 5 5/5OK Example 6 5/5OK Example 7 5/5OK Example 8 5/5OK Example 9 5/5OK Example 10 5/5OK Example 11 5/5OK Example 12 5/5OK Example 13 5/5OK Example 14 5/5OK Example 15 5/5OK Example 16 5/5OK Example 17 3/5OK, 2/5fire Example 18 3/5OK, 2/5fire Example 19 2/5OK, 3/5fire Example 20 1/5OK, 4/5fire Comparative example 1 3/5OK, 2/5fire Comparative example 2 1/5OK, 4/5fire Comparative example 3 1/5OK, 4/5fire Comparative example 4 0/5OK, 5/5fire Comparative example 5 2/5OK, 3/5fire Comparative example 6 0/5OK, 5/5fire

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Secondary Cells (AREA)

Abstract

本申请涉及一种非水电解液，包括有机溶剂、电解质盐和添加剂，在添加剂中含有巴比妥酸化合物和添加剂锂盐，其中的添加剂锂盐与电解质盐不同。本申请通过将巴比妥酸化合物和添加剂锂盐混合作为添加剂使用，可显著改善电池性能。

Description

一种非水电解液及锂离子电池 技术领域
本申请涉及锂电池技术领域，具体涉及一种非水电解液及锂离子电池。
背景技术
锂离子电池因具有比能量高、循环寿命长、自放电小等优点，被广泛应用于消费类电子产品以及储能与动力电池中。随着锂离子电池的广泛应用，其使用环境也早已趋于多种多样，对电池的寿命、安全性能要求越来越高。例如，电池在大倍率快速充放电的情况下仍具有较长的寿命，在高温长时间工作仍无安全风险等。
锂离子电池的寿命、安全性能受到诸多因素的影响，其中，非水电解液作为锂离子电池的重要组成部分，对其有着重大的影响。通过非水电解液能够改善电池的动力学性能，减小极化，循环及高温存储过程中正负极界面稳定性从而达到改善寿命和安全性能的目的。
发明内容
本申请的目的之一在于提供一种非水电解液。
本申请的目的之二在于提供一种锂离子电池。
本申请的具体技术方案为：
本申请涉及一种非水电解液，包括有机溶剂、电解质盐和添加剂，所述添加剂中含有巴比妥酸化合物和添加剂锂盐，所述添加剂锂盐与所述电解质盐不同。
优选的，所述巴比妥酸化合物选自结构式为式(Ⅰ)所示的化合物中的至少一种，
Figure PCTCN2017093197-appb-000001
其中，
R11、R12各自独立地选自取代或未取代的C1～12烷基、取代或未取代的C2～12烯基、取代或未取代的C6～26芳基；
R13、R14各自独立地选自氢、氨基、取代或未取代的C1～12烷基、取代或未取代的C2～12烯基、取代或未取代的C6～26芳基、-NH-R’,其中R’为取代或未取代的C1～12的烷基；
X选自O或S；
取代基选自卤素。
优选的，R11、R12各自独立地选自取代或未取代的C1～5烷基、取代或未取代的苯基；
R13、R14各自独立地选自氢、取代或未取代的C1～5烷基、取代或未取代的苯基、氨基。
优选的，所述巴比妥酸化合物选自以下化合物中的至少一种，
Figure PCTCN2017093197-appb-000002
优选的，所述巴比妥酸化合物在所述非水电解液中的质量百分含量为0.01％～3％；优选为0.05％～2％。
优选的，所述电解质盐为六氟磷酸锂。
优选的，所述添加剂锂盐选自磺酰亚胺锂盐、含硼锂盐、含氟磷酸锂盐中的至少一种；优选所述磺酰亚胺锂盐选自双三氟甲烷磺酰亚胺锂和/或双(氟磺酰)亚胺锂，所述含硼锂盐选自双草酸硼酸锂、二氟草酸硼酸锂、四氟硼酸锂中的至少一种，所述含氟磷酸锂盐为二氟磷酸锂。
优选的，所述电解质盐在所述非水电解液中的质量百分含量为0.5％～30％；优选为10％～20％。
优选的，所述添加剂锂盐在所述非水电解液中的质量百分含量为0.01％～5％；优选为0.1％～2％。
本申请涉及一种锂离子电池，包括正极片、负极片、间隔设置于正极片和负极片之间的隔离膜、以及前述电解液。
本申请提供的技术方案可以达到以下有益效果：
与现有技术相比，本申请通过将巴比妥酸化合物和添加剂锂盐共同作为添加剂，不仅在电池正极表面生成稳定的钝化膜，而且在此钝化膜上还夹杂着无机盐类物质。从而能够隔离溶剂，抑制正极活性物质被电解液氧化，还能增强锂离子迁移速率，降低极化，显著改善电池的循动力学性能及循环后的热箱性能。
具体实施方式
为使本申请的目的、技术方案和优点更加清楚，下面将结合本申请实施例及附图，对本申请的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请提供的技术方案及所给出的实施例，本领域技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
本申请涉及一种非水电解液，包括有机溶剂、电解质盐和添加剂。作为本申请非水电解液的改进，本申请的添加剂中同时含有巴比妥酸化合物和与电解质盐不同的添加剂锂盐。
研究表明，巴比妥酸化合物的氧化电位比溶剂低，可以在电芯正极表面氧化聚合形成致密的固体电解质相界面膜(CEI)，有效减少溶剂在正极 的分解，对电池的性能非常有益；这是因为巴比妥酸化合物与锂形成的聚合物覆盖在正极表面相对于烷基锂更难被溶剂溶解，CEI更加稳定。从而能够有效阻止正极材料与非水电解液在正极表面发生副反应，并且能够有效的减少循环过程中正极界面阻抗的增加，减小循环过程中正极极化造成的容量损失。巴比妥酸化合物聚合成膜后，可防止正极材料的如Mn、Co元素的溶出，抑制非水电解液发生氧化产气使电池膨胀。
在锂离子电池中，电解质盐类化合物热稳定性较好，在电解液中电导率高，粘度低，可以降低电解液的浓差极化，改善动力学性能。某些电解质盐类，如本申请中的添加剂锂盐在高电位下易反应生成硼酸盐、磷酸盐或氮氟化类等无机盐类物质，有利于锂离子的传输。因此将巴比妥酸化合物与添加剂锂盐结合后，除在电池正极生成稳定的钝化膜，在此钝化膜上还夹杂着无机盐类物质。不仅能够隔离溶剂，使正极不被电解液氧化，还能增强锂离子迁移速率，降低极化，从而显著改善电池的循环性能、倍率性能及循环后的热箱性能。
作为本申请非水电解液的一种改进，本申请巴比妥酸化合物选自结构式为式(1)所示的化合物中的至少一种，
Figure PCTCN2017093197-appb-000003
其中，
R11、R12各自独立地选自取代或未取代的C1～12烷基、取代或未取代的C2～12烯基、取代或未取代的C6～26芳基；
R13、R14各自独立地选自氢、氨基、取代或未取代的C1～12烷基、取代或未取代的C2～12烯基、取代或未取代的C6～26芳基、-NH-R’,其中R’为取代或未取代的C1～12的烷基；
X选自O或S；
取代基选自卤素，如F、Cl。
作为本申请的一种改进，
R11、R12各自独立地选自取代或未取代的C1～6烷基、取代或未取代的C2～6烯基、取代或未取代的苯基；
R13、R14各自独立地选自氢、取代或未取代的C1～6的烷基、取代或未取代的C2～6的烯基、取代或未取代的苯基、取代或未取代的C1～6的氨基烷基、氨基、被C1～6烷基取代的亚氨基。
作为本申请的一种改进，
R11、R12各自独立地选自取代或未取代的C1～5烷基、取代或未取代的苯基；
R13、R14各自独立地选自氢、取代或未取代的C1～5烷基、取代或未取代的苯基、氨基。
在上述式Ⅰ中，取代基的含义如下所述。
碳原子数为1～12的烷基，烷基可为链状烷基，也可为环烷基，位于环烷基的环上的氢可被烷基取代，所述烷基中碳原子数优选的下限值为2，3，4，5，优选的上限值为3，4，5，6，8，10，12。优选地，选择碳原子数为1～10的烷基，进一步优选地，选择碳原子数为1～6的链状烷基，碳原子数为3～8的环烷基，更进一步优选地，选择碳原子数为1～5的链状烷基。作为烷基的实例，具体可以举出：甲基、乙基、正丙基、异丙基、正丁基、异丁基、仲丁基、叔丁基、正戊基、异戊基、新戊基、环戊基、环己基。
碳原子数为2～12的烯基，可为环状烯基，也可为链状烯基。另外，烯基中双键的个数优选为1个。所述烯基中碳原子数优选的下限值为2，3，4，优选的上限值为3，4，5，6，8，10，12。优选地，选择碳原子数为2～10的烯基，进一步优选地，选择碳原子数为2～6的烯基，更进一步优选地，选择碳原子数为2～5的烯基。作为烯基的实例，具体可以举出：乙烯基、烯丙基、异丙烯基、戊烯基、环己烯基、环庚烯基、环辛烯基。
碳原子数为6～26的芳基，例如苯基、苯烷基、至少含有一个苯基的芳基如联苯基、稠环芳烃基如萘、蒽、菲均可，联苯基和稠环芳烃基还可 被烷基或是烯基所取代。优选地，选择碳原子数为6～16的芳基，进一步优选地，选择碳原子数为6～14的芳基，更进一步优选地，选择碳原子数为6～9的芳基。作为芳基的实例，具体可以举出：苯基、苄基、联苯基、对甲苯基、邻甲苯基、间甲苯基。
当前述提到的碳原子数为1～12的烷基、碳原子数为2～12的烯基、碳原子数为6～26的芳基被卤原子取代后，依次相应的形成碳原子数为1～12的卤代烷基、碳原子数为2～12的卤代烯基、碳原子数为6～26的卤代芳基，其中卤原子为F、Cl、Br，优选为F、Cl。在所形成的卤代基团中，卤原子对部分氢原子或者全部氢原子进行取代，卤原子的个数可为1个、2个、3个或4个。
优选地，选择碳原子数为1～10的卤代烷基、碳原子数为2～10的卤代烯基、碳原子数为6～16的卤代芳基，进一步优选地，选择碳原子数为1～6的卤代链状烷基、碳原子数为3～8的卤代环烷基、碳原子数为2～6的卤代烯基、碳原子数为6～14的卤代芳基，更进一步优选地，选择碳原子数为1～4的卤代链状烷基、碳原子数为5～7的卤代环烷基、碳原子数为2～5的卤代烯基、碳原子为6～10的卤代芳基。
作为卤代基团的实例，具体可以举出：三氟甲基(-CF3)、2-氟乙基、3-氟正丙基、2-氟异丙基、4-氟正丁基、3-氟仲丁基、5-氟正戊基、4-氟异戊基、1-氟乙烯基、3-氟烯丙基、6-氟-4-己烯基、邻氟苯基、对氟苯基、间氟苯基、4-氟甲基苯基、2,6-二氟甲基苯基、2-氟-1-萘基、氟代甲氧基、1-氟乙氧基、2-氟-正丙氧基、1-氟-异丙氧基、3-氟-正丁氧基、4-氟-正戊氧基、2,2-二氟甲基丙氧基、5-氟-正己氧基、1,1,2-三氟甲基丙氧基、6-氟-正庚基氧基、7-氟-正辛基氧基、3-氟-环戊氧基、4-氟-2-甲基环戊氧基、3-氟-环己氧基、3-氟环庚氧基、4-氟-2-甲基环庚氧基、3-氟环辛氧基。在上述具体的实例中，F可被Cl和/或Br取代。
所述巴比妥酸化合物选自以下化合物中的至少一种:
Figure PCTCN2017093197-appb-000004
作为本申请非水电解液的一种改进，本申请巴比妥酸化合物还选自以下化合物中的至少一种，但不限于此：
Figure PCTCN2017093197-appb-000005
作为本申请非水电解液的一种改进，本申请巴比妥酸化合物在非水电解液中的质量百分含量为0.01％～3％。当巴比妥酸化合物的含量低于0.01％时，不能在正极表面形成完整而有效的CEI膜，从而不能有效阻止非水电解液与电极之间的电子转移所引起的副反应；而当巴比妥酸化合物含量大于3％时，会在正极表面形成较厚的CEI膜，导致锂离子迁移阻力增大，不利于循环过程中电池的正极界面稳定性。
进一步优选地，本申请巴比妥酸化合物在非水电解液中的质量百分含量范围的上限任选自3％、2.8％、2.5％、2.0％、1.5％、1.0％，下限任选自0.01％、0.03％、0.05％、0.1％、0.3％、0.5％、0.6％。更进一步优选地，所述巴比妥酸化合物在非水电解液中的百分含量为0.05％～2％。
由于与其它添加剂锂盐相比，六氟磷酸锂(LiPF6)是目前商品化锂电池使用最多的锂盐。其电化学窗口较宽，电化学稳定性强，且不腐蚀铝集流体，合成路线成熟，综合性能优于其他锂盐，因此将其作为本申请非水电解液中的电解质盐。但由于六氟磷酸锂的分解温度为80℃，热稳定性较差，即使是在高纯状态下也能分解。分解产物为氟化锂(LiF)和五氟化磷(PF5)，气态的PF5具有较强的路易斯酸性，会与溶剂分子中氧原子的孤电子对作用而使溶剂发生分解反应。与六氟磷酸锂相比，其它种类的锂盐具有更好的热稳定性和成膜性能，因此本申请进一步在添加剂中使用添加剂锂盐，以弥补六氟磷酸锂在80-90℃下易分解的缺点。
作为本申请非水电解液的一种改进，添加剂锂盐选自磺酰亚胺锂盐、含硼锂盐、含氟磷酸锂盐中的至少一种；进一步优选双三氟甲烷磺酰亚胺锂LiN(CF3SO2)2(简写为LiTFSI)、双(氟磺酰)亚胺锂Li(N(SO2F)2)(简写为LiFSI)、双草酸硼酸锂LiB(C2O4)2(简写为LiBOB)、二氟草酸硼酸锂二氟草酸硼酸锂LiBF2(C2O4)(简写为LiDFOB)、二氟磷酸锂(LiPO2F2)、四氟硼酸锂(LiBF4)中的至少一种。
作为本申请非水电解液的一种改进，电解质盐在非水电解液中的质量百分含量为0.5％～30％。通常来说，电解液的电导率与电解质盐浓度成正比，与溶剂的粘度成反比。具体地，电解质盐浓度增加，电解出的自由离子也会增多，从而增大电导率；但同时电解液的粘度和离子缔合的程度也 会随电解质盐浓度增加而增大，这又会降低电导率。
进一步优选地，本申请电解质盐在非水电解液中的质量百分含量范围的上限任选自5％、10％、15％、20％、25％、30％，下限任选自0.5％、1％、2％、3％、5％、10％。更进一步优选地，电解质盐在非水电解液中的百分含量为10％～20％。对于常见的电解液体系来说，15％的质量百分含量既有较高的电导率，成本也相对较低。
作为本申请非水电解液的一种改进，添加剂锂盐在非水电解液中的质量百分含量为0.01％～5％。添加剂锂盐在非水电解液中的含量过小，与巴比妥酸化合物结合，生成稳定钝化膜的效果不明显；当添加剂锂盐含量过大时，电解液中大量的锂离子导致电解液粘度和电池内阻增大，不利于电化学性质的改善。
进一步优选地，本申请添加剂锂盐在非水电解液中的质量百分含量范围的上限任选自1％、2％、3％、4％、5％，下限任选自0.01％、0.1％、0.5％、0.3％、0.5％、1％。更进一步优选地，添加剂锂盐在非水电解液中的百分含量为0.1％～2％，更优选1％～2％。
作为本申请非水电解液的一种改进，本申请有机溶剂选自碳酸乙烯酯(EC)、碳酸丙烯脂(PC)、碳酸丁烯酯、氟代碳酸乙烯酯、碳酸甲乙酯、碳酸二甲酯、碳酸二乙酯(DEC)、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、1,4-丁内酯、丙酸甲酯、丁酸甲酯、丙酸丙酯、乙酸乙酯、丙酸乙酯、丁酸乙酯中的至少一种。
本申请还涉及一种锂离子电池，包括正极片、负极片、间隔设置于正极片和负极片之间的隔离膜、以及电解液；所述电解液为前述任一段落所述的非水电解液。
本申请还提供了一种锂离子电池，包括正极片、负极片、间隔设置于正极片和负极片之间的隔离膜、电解液、以及包装箔；所述正极片包括正极集流体及涂布在正极集流体上的正极膜片，负极片包括负极集流体及涂布在负极集流体上的负极膜片；所述电解液为前述任一段落所述的非水电解液。
作为本申请锂离子电池的一种改进，本申请正极膜片包括正极活性材 料、粘结剂和导电剂。
作为本申请锂离子电池的一种改进，本申请正极活性材料任选自钴酸锂LiCoO2、锂镍锰钴三元材料、磷酸(亚)铁锂、锰酸锂中的至少一种。
作为本申请锂离子电池的一种改进，本申请正极活性材料为钴酸锂与锂镍锰钴三元材料的混合物。
作为本申请锂离子电池的一种改进，本申请负极膜片包括负极活性材料、粘结剂和导电剂。
作为本申请锂离子电池的一种改进，本申请负极活性材料为石墨和/或硅。
以下通过具体实施例对本申请的技术方案做示例性描述：
电解液的制备：在含水量<10ppm的氩气气氛手套箱中，将碳酸乙烯酯(简写为EC)、碳酸二乙酯(简写为DEC)、碳酸丙烯酯(简写为PC)、丙酸乙酯、按照20:30:20:30的质量比混合均匀后，得到非水溶剂，再将充分干燥的电解质盐LiPF6溶解于上述非水溶剂，配成基础电解液。
按照表1所示，在基础电解液中加入巴比妥酸化合物及添加剂锂盐作为添加剂。
作为巴比妥酸化合物的实例为：1,3-二甲基巴比妥酸(B1,如式I-1所示)、1,3-二丁基巴比妥酸(B2,如式I-2所示)、1,3-二苯基巴比妥酸(B3，如式I-3所示)，1,3-二甲基-2-硫代巴比妥酸(B4，如式I-4所示)，5-氨基-2-硫代巴比妥酸(B5，如式I-5所示)。
Figure PCTCN2017093197-appb-000006
Figure PCTCN2017093197-appb-000007
作为添加剂锂盐的实例为：LiBF4、LiFSI、LiTFSI、LiBOB、LiDFOB、LiPO2F2。
锂离子电池的制备：
1)正极片的制备：将正极活性物质钴酸锂(分子式为LiCoO2)、导电剂乙炔黑、粘结剂聚偏二氟乙烯(简写为PVDF)按重量比96:2:2在适量的N-甲基吡咯烷酮(简写为NMP)溶剂中充分搅拌混合，使其形成均匀的正极浆料；将此浆料涂覆于正极集流体Al箔上，烘干、冷压，得到正极片。
2)负极片的制备：将负极活性物质石墨、导电剂乙炔黑、粘结剂丁苯橡胶(简写为SBR)、增稠剂羧甲基纤维素钠(简写为CMC)按照重量比95:2:2:1在适量的去离子水溶剂中充分搅拌混合，使其形成均匀的负极浆料；将此浆料涂覆于负极集流体Cu箔上，烘干、冷压，得到负极片。
3)隔离膜：以PE多孔聚合物薄膜作为隔离膜。
4)锂离子电池的制备：将正极片、隔离膜、负极片按顺序叠好，使隔离膜处于正极片和负极片之间起到隔离的作用，然后卷绕得到裸电芯；将裸电芯置于外包装箔中，将上述制备好的电解液注入到干燥后的电池中，经过真空封装、静置、化成、整形等工序，即完成锂离子电池的制备。
按照上述制备方法制备实施例1～20以及对比例1～6的电解液及锂离子电池；电解液中添加剂及各自的添加量如表1所示。
表1实施例1～20以及对比例1～6的电解质、电解液添加剂及添加量
Figure PCTCN2017093197-appb-000008
Figure PCTCN2017093197-appb-000009
以下将通过实验对本申请各对比例和实施例制得的锂离子电池进行性能测试。
测试一、充电倍率测试
将制备得到的锂离子电池均分别进行下述测试：
在25℃下，将锂离子电池，以不同倍率0.5C、1C、2C、3C、5C充电 至4.4V，分别记录充电容量，以0.5C的电容量作为基准(100％)，计算不同倍率充电的容量。各个锂离子电池中所选用的电解液以及得到的相关测试数据参见表2。
表2.实施例1～20以及对比例1～6的锂离子电池充电倍率测试结果
Figure PCTCN2017093197-appb-000010
Figure PCTCN2017093197-appb-000011
结合表1和表2中可以看出，与对比例6相比，对比例1的电解液中单独加入1％巴比妥酸化合物时，锂离子电池的充电倍率有明显改善。在实施例1～11中，电解液中同时加入质量分数为1％的巴比妥酸化合物和质量分数为1％的添加剂锂盐时，电池的充电容量显著提升。特别是实施例10，LiPO2F2在正负极反应后具有更低的阻抗，所以充电速度快，充电倍率高。然而，当电解液中巴比妥酸化合物的含量超过3％时，电池的充电容量非但没有改善，甚至会恶化，原因是巴比妥酸化合物过多时会导致成膜厚且电解液粘度高，锂离子传导变得困难，特别是电解液中添加4％巴比妥酸化合物的对比例2，其电池的充电容量远低于其他组别。同样的，如实施例16和17，当电解液中添加剂锂盐的含量过小或过大时，电池性能均开始下降。当电解液中使用两种添加剂锂盐的组合时，大倍率的充电容量有所提高，但效果不明显，如实施例12-15。电解质盐的含量提高也不利于充电容量的改善，如实施例19和20，原因是随着电解液的粘度和离子缔合的程度增大而电导率降低。
测试二、循环测试
将制备得到的锂离子电池均分别进行下述测试：
在45℃下，将锂离子电池，以1C恒流充电至4.4V，然后恒压充电至电流为0.05C，再用1C恒流放电至3.0V，此时为首次循环，按照上述 条件进行如此多次循环充电/放电，分别计算得出锂离子电池循环50次、100次、200次、300次和500次后的容量保持率。每组各5只电池，其中，循环后的容量保持率按照下式进行计算。各个锂离子电池中所选用的电解液以及得到的相关测试数据参见表3。
循环后的容量保持率＝(对应循环的放电容量/首次循环的放电容量)×100％，循环测试的结果如表3所示。
表3实施例1～20以及对比例1～6的锂离子电池循环后的容量保持率
Figure PCTCN2017093197-appb-000012
Figure PCTCN2017093197-appb-000013
结合表1和表3中可以看出，与对比例1相比，实施例1～11的电解液中加入1％的添加剂锂盐时，锂离子电池的循环性能显著提升。然而，当电解液中添加剂锂盐的含量小于0.01％和高于5％时，电池的循环性能改善幅度较小。当电解液中添加剂锂盐的含量超过10％时，电池的循环性能非但没有改善，甚至会恶化，如对比例4，其电池的循环保持率低于其他组别。当电解液添加剂中使用两种添加剂锂盐时，循环性能几乎没有变化，如实施例12-15。由于电解液中仅使用六氟磷酸锂就能够满足电池内部电荷传递的需要，在实施例1-18中，当电解质盐的用量控制在10％～20％的范围内时，电池的循环性能主要受添加剂影响。但当电解质盐的用量大于20％后，降低了电解液中的有机溶剂含量，造成电池的循环性能衰减。
测试三、循环后的热箱测试
将进行过500次25℃循环后的电池，在25℃下以0.5C电流恒流充电至4.4V，4.4V恒压充电至电流为0.025C，使其处于4.4V满充状态，然后将电池放在150℃的高温炉中保持1小时，同时测试电池在高温炉中电压变化以及电芯表面温度，并观察测试后电池的状态。循环后热箱测试的结果如表4所示。
表4实施例1～20以及对比例1～6锂电池在25℃循环后在热箱测试后结果
组别 热箱测试
实施例1 5/5OK
实施例2 5/5OK
实施例3 5/5OK
实施例4 5/5OK
实施例5 5/5OK
实施例6 5/5OK
实施例7 5/5OK
实施例8 5/5OK
实施例9 5/5OK
实施例10 5/5OK
实施例11 5/5OK
实施例12 5/5OK
实施例13 5/5OK
实施例14 5/5OK
实施例15 5/5OK
实施例16 5/5OK
实施例17 3/5OK,2/5fire
实施例18 3/5OK,2/5fire
实施例19 2/5OK,3/5fire
实施例20 1/5OK,4/5fire
对比例1 3/5OK,2/5fire
对比例2 1/5OK,4/5fire
对比例3 1/5OK,4/5fire
对比例4 0/5OK,5/5fire
对比例5 2/5OK,3/5fire
对比例6 0/5OK,5/5fire
结合表1和表4中可以看出，巴比妥酸化合物作为电解液添加剂同时搭配添加剂锂盐添加剂使用时，可以显著提高电池在循环后的热箱性能。 当巴比妥酸化合物的含量高于3％，或添加剂锂盐的含量高于10％时，将会导致循环后电池热箱测试着火，其原因可以考虑是因为过多的巴比妥酸化合物或添加剂锂盐在循环过程中膜阻抗增加，导致电池在循环过程中金属锂析出，恶化电池负极的热稳定性，恶化电池循环后的热箱性能。电解质盐的含量升高也会导致热箱性能的下降。
本申请虽然以较佳实施例公开如上，但并不是用来限定权利要求，任何本领域技术人员在不脱离本申请构思的前提下，都可以做出若干可能的变动和修改，因此本申请的保护范围应当以本申请权利要求所界定的范围为准。

Claims (10)

  1. 一种非水电解液，包括有机溶剂、电解质盐和添加剂，其特征在于，所述添加剂中含有巴比妥酸化合物和添加剂锂盐，所述添加剂锂盐与所述电解质盐不同。
  2. 根据权利要求1所述的非水电解液，其特征在于，所述巴比妥酸化合物选自结构式为式Ⅰ所示的化合物中的至少一种，
    Figure PCTCN2017093197-appb-100001
    其中，
    R11、R12各自独立地选自取代或未取代的C1～12烷基、取代或未取代的C2～12烯基、取代或未取代的C6～26芳基；
    R13、R14各自独立地选自氢、氨基、取代或未取代的C1～12烷基、取代或未取代的C2～12烯基、取代或未取代的C6～26芳基、-NH-R’,其中R’为取代或未取代的C1～12的烷基；
    X选自O或S；
    取代基选自卤素。
  3. 根据权利要求2所述的非水电解液，其特征在于，其中，
    R11、R12各自独立地选自取代或未取代的C1～5烷基、取代或未取代的苯基；
    R13、R14各自独立地选自氢、取代或未取代的C1～5烷基、取代或未取代的苯基、氨基。
  4. 根据权利要求3所述的非水电解液，其特征在于，所述巴比妥酸化合物选自以下化合物中的至少一种，
    Figure PCTCN2017093197-appb-100002
  5. 根据权利要求1所述的非水电解液，其特征在于，所述巴比妥酸化合物在所述非水电解液中的质量百分含量为0.01％～3％；优选为0.05％～2％。
  6. 根据权利要求1所述的非水电解液，其特征在于，所述电解质盐为六氟磷酸锂。
  7. 根据权利要求1所述的非水电解液，其特征在于，所述添加剂锂盐选自磺酰亚胺锂盐、含硼锂盐、含氟磷酸锂盐中的至少一种；优选所述磺酰亚胺锂盐选自双三氟甲烷磺酰亚胺锂和/或双(氟磺酰)亚胺锂，所述含硼锂盐选自双草酸硼酸锂、二氟草酸硼酸锂、四氟硼酸锂中的至少一种，所述含氟磷酸锂盐为二氟磷酸锂。
  8. 根据权利要求1所述的非水电解液，其特征在于，所述电解质盐在所述非水电解液中的质量百分含量为0.5％～30％；优选为10％～20％。
  9. 根据权利要求1所述的非水电解液，其特征在于，所述添加剂锂盐在所述非水电解液中的质量百分含量为0.01％～5％；优选为0.1％～2％。
  10. 一种锂离子电池，包括正极片、负极片、间隔设置于正极片和负极片之间的隔离膜、以及电解液，其特征在于，所述电解液为权利要求1～9任一所述的非水电解液。
PCT/CN2017/093197 2016-11-30 2017-07-17 一种非水电解液及锂离子电池 Ceased WO2018099092A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN201611079073.X 2016-11-30
CN201611079073.XA CN106654370A (zh) 2016-11-30 2016-11-30 一种非水电解液及锂离子电池

Publications (1)

Publication Number Publication Date
WO2018099092A1 true WO2018099092A1 (zh) 2018-06-07

Family

ID=58813395

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2017/093197 Ceased WO2018099092A1 (zh) 2016-11-30 2017-07-17 一种非水电解液及锂离子电池

Country Status (2)

Country Link
CN (1) CN106654370A (zh)
WO (1) WO2018099092A1 (zh)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108862231A (zh) * 2018-07-06 2018-11-23 河南省法恩莱特新能源科技有限公司 一种二氟磷酸锂的制备方法
US20220085414A1 (en) * 2019-01-10 2022-03-17 Gs Yuasa International Ltd. Energy storage device and method for manufacturing energy storage device
CN114300745A (zh) * 2021-11-24 2022-04-08 惠州市豪鹏科技有限公司 一种非水电解液、二次电池及硫代磷酰胺作为电解液添加剂的应用

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106654370A (zh) * 2016-11-30 2017-05-10 宁德时代新能源科技股份有限公司 一种非水电解液及锂离子电池
CN109390628B (zh) * 2017-08-08 2020-09-01 张家港市国泰华荣化工新材料有限公司 一种非水电解液及锂离子电池
CN109659619B (zh) * 2019-01-04 2022-03-22 蜂巢能源科技有限公司 电解液及其制备方法和应用
CN109830749B (zh) 2019-01-25 2021-06-04 宁德新能源科技有限公司 一种电解液及电化学装置
CN110994021A (zh) * 2019-11-19 2020-04-10 惠州市豪鹏科技有限公司 电解液添加剂、电解液和锂离子电池
CN114430068B (zh) * 2020-10-29 2024-01-23 深圳市研一新材料有限责任公司 一种锂离子电池电解液

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080160418A1 (en) * 2006-12-29 2008-07-03 Industrial Technology Research Institute Nonaqueous electrolyte having maleimide additives and secondary cells employing the same
CN103887561A (zh) * 2012-12-20 2014-06-25 财团法人工业技术研究院 锂离子二次电池用的电解液添加剂以及锂离子二次电池
WO2016063964A1 (ja) * 2014-10-22 2016-04-28 三井化学株式会社 リチウム二次電池
CN105914402A (zh) * 2016-07-01 2016-08-31 宁德新能源科技有限公司 一种非水电解液及锂离子电池
CN106654370A (zh) * 2016-11-30 2017-05-10 宁德时代新能源科技股份有限公司 一种非水电解液及锂离子电池

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4137452B2 (ja) * 2002-01-16 2008-08-20 三菱化学株式会社 非水系電解液及びそれを用いたリチウム二次電池
JPWO2014046283A1 (ja) * 2012-09-21 2016-08-18 富士フイルム株式会社 非水二次電池用電解液および非水二次電池
JP2014127354A (ja) * 2012-12-26 2014-07-07 Fujifilm Corp 非水二次電池用電解液および非水二次電池、電解液用添加剤
CN104995784A (zh) * 2013-02-27 2015-10-21 三菱化学株式会社 非水电解液及使用该非水电解液的非水电解质电池
DE102015008345A1 (de) * 2015-06-27 2015-12-10 Daimler Ag Elektrochemischer Energiespeicher

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080160418A1 (en) * 2006-12-29 2008-07-03 Industrial Technology Research Institute Nonaqueous electrolyte having maleimide additives and secondary cells employing the same
CN103887561A (zh) * 2012-12-20 2014-06-25 财团法人工业技术研究院 锂离子二次电池用的电解液添加剂以及锂离子二次电池
WO2016063964A1 (ja) * 2014-10-22 2016-04-28 三井化学株式会社 リチウム二次電池
CN105914402A (zh) * 2016-07-01 2016-08-31 宁德新能源科技有限公司 一种非水电解液及锂离子电池
CN106654370A (zh) * 2016-11-30 2017-05-10 宁德时代新能源科技股份有限公司 一种非水电解液及锂离子电池

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108862231A (zh) * 2018-07-06 2018-11-23 河南省法恩莱特新能源科技有限公司 一种二氟磷酸锂的制备方法
US20220085414A1 (en) * 2019-01-10 2022-03-17 Gs Yuasa International Ltd. Energy storage device and method for manufacturing energy storage device
CN114300745A (zh) * 2021-11-24 2022-04-08 惠州市豪鹏科技有限公司 一种非水电解液、二次电池及硫代磷酰胺作为电解液添加剂的应用

Also Published As

Publication number Publication date
CN106654370A (zh) 2017-05-10

Similar Documents

Publication Publication Date Title
WO2018099091A1 (zh) 一种电解液及二次电池
CN101510622B (zh) 一种用于锂离子二次电池的电解液及含有该电解液的电池
WO2018099092A1 (zh) 一种非水电解液及锂离子电池
CN106785044B (zh) 一种电解液及二次电池
WO2021110165A1 (zh) 一种低内阻的锂二次电池电解液及锂二次电池
CN107871889B (zh) 电解液及二次电池
CN107293781B (zh) 电解液及锂离子电池
CN105914399A (zh) 一种电解液以及含有该电解液的锂离子电池
CN107331893B (zh) 一种高温锂离子电池电解液及其制备方法和高温锂离子电池
CN105161753B (zh) 锂离子电池及其电解液
CN105895957B (zh) 一种电池液及锂离子电池
WO2019200656A1 (zh) 锂二次电池电解液及其锂二次电池
WO2018107745A1 (zh) 电解液及锂二次电池
WO2020238191A1 (zh) 一种降低电池阻抗的锂二次电池电解液及锂二次电池
CN110797544A (zh) 一种高性能锂一次电池及其制备方法
CN105762410B (zh) 一种非水电解液及使用该非水电解液的锂离子电池
CN105098236B (zh) 锂离子电池及其电解液
CN105789684A (zh) 锂离子二次电池及其电解液
CN110120553A (zh) 一种电解液和锂离子电池
CN105655643B (zh) 电解液以及包括该电解液的锂离子电池
CN109004275B (zh) 电解液及二次电池
CN109390629B (zh) 一种电解液以及电池
CN116344933A (zh) 一种钠离子电池电解液和钠离子电池
CN105789701A (zh) 电解液以及包括该电解液的锂离子电池
CN105489936A (zh) 一种非水电解液以及含有该电解液的锂离子电池

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17875530

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 17875530

Country of ref document: EP

Kind code of ref document: A1