JP2018526763A5 - - Google Patents

Description

Electrolyte solution of high voltage lithium ion battery, preparation method thereof and application thereof

  The present invention is included in the technical field of electrolytes for lithium ion batteries, and in particular, high voltage lithium Involved in the preparation and use of electrolytes in mu-ion batteries. The stability of the electrolyte solution of the present invention is good It is also simple and will increase the cycling life and high temperature performance of high voltage lithium ion batteries if used.

  Lithium-ion batteries have high energy, small size, light weight, memorylessness, cycle life, etc. From the merits of the new high-energy storage battery that is the fastest growing and important to date. In the last few years, portable electronic devices have evolved rapidly to have good hardware configurations and large The energy density of lithium-ion batteries from the perspective of The demand becomes severe. Ordinary lithium ion batteries can not meet people's requirements already.

  In order to increase the energy density of lithium-ion batteries, researchers usually Develop high voltage anode materials. For example, lithium cobalt oxide and lithium manganese Increase the oxide voltage and develop high voltage lithium nickel manganese oxide etc. Only The high voltage causes the solvent of the anode material to change its structure, and the transition metal tends to dissolve easily. Precipitate on the cathode. Then, ordinary electrolyte decomposes when it is higher than 4V, and gas is generated. Ru. Thus, the performance of the battery is reduced. In order to solve the above problems, researchers usually Protect or dope the surface of the material. Therefore, the circulation performance is enhanced in the case of high voltage Make it However, this method consumes battery capacity. And the way it is complicated and costly Will also be high. New high-voltage battery electrolyte to replace the system of electrolytes often used so far There is a way to improve high voltage lithium ion batteries to develop. The voltage currently used Electrolyte to enhance, always increase the amount of FEC (Eurocarbonated Carbonate) to increase the withstand voltage Ru. However, when the voltage goes above 4.5 V, if the amount of FEC is increased, the cycling performance of the battery Will go lower quickly. Therefore, developing high-voltage electrolyte additives does not allow for a moment.

  To increase the power density of lithium ion batteries and to increase the voltage electrolyte in current technology In order to solve the deterioration of the cycling performance of the battery by Provided are an electrolytic solution, a preparation method thereof and an application thereof.

  The present invention is a technical solution adopted to realize the purpose.
  The organic solvent contains an organic solvent, a lithium salt and an additive, and the organic solvent is a cyclic carbonate solvent, a fluorine-containing solvent An electrolyte for a high voltage lithium ion battery comprising a solvent and a carbonate solvent, the additive Is 3-cyano-1,3 propene sultone, and the additive in the electrolyte of a lithium ion battery Content of 0.5% to 10%.

  The concentration of lithium salt in the organic solvent is 1 to 1.5 mol / L, and The mass percentage of the fluorinated solvent is 2 to 50%.

  The cyclic carbonate solvent is ethylene carbonate, propylene carbonate, γ-butyrolactone, γ- It is selected from one or more of valerolactone.

  The fluorine-containing solvent is a fluorine-containing carbonic ester whose structural formula is the following chemical formula 1, and a structural formula is Fluorine-containing carbonate ester represented by Chemical Formula 2; and Fluorine-containing fluorinated ester represented by Chemical Formula 3 At least one of the following: ₁ ~ R ₆ Are both C _x F _y H _z And 1 ≦ x ≦ 6, y> 0, z ≧ 0.

  Carbonic ester solvents are dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, propionic acid Selected from one or more of methyl, ethyl propionate and propyl propionate Ru.

  Lithium salt is LiPF ₆ , LiBF ₄ , LiSO ₃ CF ₃ , LiClO ₄ , LiN ( CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ Selected from one or more of

  A method of preparing an electrolyte solution of the above high voltage lithium ion battery, comprising: After uniformly mixing the fluorinated solvent and the carbonate solvent, the impurities and water are removed, and the room temperature is removed. The lithium salt is dissolved in the solvent after the above mixing and stirred uniformly, and then 3-cyano- Add 1,3 propene sultone, dissolve until it becomes clear and filter. An electrolyte of a lithium ion battery is obtained.

  After uniformly mixing cyclic carbonate solvent, fluorine-containing solvent and carbonate solvent, 4 Å Remove impurities and water using molecular sieve and lithium hydride.

  To the preparation of high voltage lithium ion battery in the electrolyte of the above high voltage lithium ion battery It is an application.

  The structural formula of the additive 3-cyano-1,3 propene sultone is as shown in the following chemical formula 4 Indicated.

  Good effect of the present invention
  If a fluorine-containing solvent is mixed with the electrolyte solvent, decomposition of the electrolyte is reduced due to the high voltage. The oxidation stability of the electrolyte is increased. At the same time, since fluorinated solvents have good infiltration properties, electrolytes Improve the infiltration of And adding 3-cyano-1,3 propene sultone is an anode Good protection can reduce the elution of transition metals in the anode material. At the same time, The SEI film is formed, reducing the precipitation and reduction left on the cathode by the transition metal. Therefore, the cathode Are protected safely. This is to enhance the cycling stability and high temperature performance of the battery in the case of high voltage It is also advantageous to prevent the occurrence of safety problems such as fires and explosions caused by lithium ion batteries. Stop and increase battery stability. Lithium-ion batteries have high charging efficiency and good circulation performance. It can meet the requirement of 85% charge and discharge in 500 times. Especially high temperature of lithium ion battery The circulation performance can be improved, the storage performance of the battery is improved, and the other performance of the lithium ion battery is Not affected

  The method of preparing the electrolyte of the high voltage lithium ion battery of the present invention is simple and at the same time The cathode improves the surface properties with the electrolyte. The stability of the electrolyte is very good, high voltage lithium Increase the cycling life and high temperature performance of ion batteries.

  The high voltage lithium ion produced by the electrolyte of the high voltage lithium ion battery in the present invention On-battery has high circulating life, good expansion rate, high temperature performance, battery voltage is higher than 4.5 V Yes.

  In addition, 3-cyano-1,3 propene sultone oxidizes the electrolyte at the surface of the electrode and It is possible to prevent reductive decomposition. This reduces damage to the electrode and Improve compatibility with poles.

FIG. 1 is of circulation performance to the base electrolyte.

  In the figure, ▲ indicates the base electrolyte (EC: DMC = 1: 2,1M LiPF ₆ , FEC 1%) Represents the electrolytic solution of the present invention.

  The invention will now be described on the basis of specific examples.
  Example 1
  The electrolyte of high voltage lithium ion battery is organic solvent, LiPF ₆ And 3-cyano-1,3 It consists of ropensulton. Organic solvents are ethylene carbonate (EC), ethyl methyl carbonate (EMC ), Fluoroethylene carbonate (FEC), 1,2,2-tetrafluoroethyl-2 2,3,3-Tetrafluoropropyl ether (CF ₂ HCF ₂ CH ₂ -O-CF ₂ C F ₂ H). Among them, the weight ratio of EC to EMC is EC: EMC = 1: 2. 1,2,2-Tetrafluoroethyl-2,2,3,3- with a content of EFC of 10 wt% Tetrafluoropropyl ether (CF ₂ HCF ₂ CH ₂ -O-CF ₂ CF ₂ H) content The amount is 5 wt%. Addition of 3-cyano-1,3 propene sultone in this electrolyte The content of the agent is 2 wt%, and the concentration of the organic solvent is 1.2 mol / L.

  Method of preparing electrolyte of the above high voltage lithium ion battery
(1) After uniformly mixing the organic solvent, use 4 Å molecular sieves, lithium hydride, impurities, water Get rid of
(2) Dissolve the lithium salt in the mixed solvent at room temperature and stir uniformly.
(3) Then, 3-cyano-1,3 propene sultone was added and dissolved until it became transparent The solution is then filtered to obtain the electrolyte of the high voltage lithium ion battery.

  The preparation method of said 3-cyano-1,3 propene sultone is performed as follows.
  Starting from 1-propene 1,3-sultone, 1 mol with 800 ml of dichloromethane Dissolve 1-propene 1,3-sultone of At 1.03 mol NBS at 35 ° C Divide into pieces and add. After 7.5 hours the intermediate 3-bromo-1,3 propene sultone is obtained . Then add the intermediate and sodium fluoride to the dichloromethane to give 15-crown-5 Exchange reaction to give 3-cyano-1,3 propene sultone.

  The electrolyte of the high voltage lithium ion battery of this embodiment is lithium cobaltate / graphite 3.0 to 4.95 V for lithium cobaltate / graphite cells at ambient temperature, used in ponds 1C Test the circulation performance of the charge and discharge. After circulation in 200 cycles, the The retention rate is 94% or more, and after circulation in 300 cycles, the retention rate of electrical capacity is 91% or more. Above, and after being circulated for 400 cycles, the retention of the electrical capacity is about 90%, 500 times After being cycled through, the retention of the electrical capacity still reaches 85% or more.

  Example 2
  The electrolyte of the high voltage lithium ion battery is an organic solvent, LiN (CF ₃ SO ₂ ) ₂ And 3- It consists of cyano-1,3 propene sultone. Organic solvents are ethylene carbonate (EC), carbon dioxide Tylmethyl (EMC), fluoroethylene carbonate (FEC) and 1,2,2-tet Lafluoroethyl-2,2,3,3-tetrafluoropropyl ether (CF ₂ HCF ₂ CH ₂ -O-CF ₂ CF ₂ H). Among them, the weight ratio of EC to EMC is EC: E MC = 1: 2. 1,2,2-Tetrafluoroethene with an EFC content of 15 wt% 2,2,3,3-Tetrafluoropropyl ether (CF) ₂ HCF ₂ CH ₂ -OC F ₂ CF ₂ The content of H) is 10 wt%. In the present electrolyte, 3-cyano-1,3 pro The additive content of pensultone is 4wt% and the concentration of organic solvent is 1.2mol / L. is there.

  Method of preparing electrolyte of the above high voltage lithium ion battery
(1) After uniformly mixing the organic solvent, use 4 Å molecular sieves, lithium hydride, impurities, water Get rid of
(2) Dissolve the lithium salt in the mixed solvent at room temperature and stir uniformly.
(3) Then, 3-cyano-1,3 propene sultone was added and dissolved until it became transparent The solution is then filtered to obtain the electrolyte of the high voltage lithium ion battery.

  The electrolyte of the high voltage lithium ion battery of this embodiment is lithium cobaltate / graphite 3.0 to 4.95 V for lithium cobaltate / graphite cells at ambient temperature, used in ponds 1C Test the circulation performance of the charge and discharge. After circulation in 200 cycles, the The retention rate is 94%, and after circulation in 300 cycles, the retention rate of electrical capacity is 91% and After the cycle of 400 cycles, the retention rate of the electric capacity is 90%, and the cycle of 500 cycles is repeated. After ringing, the retention of capacitance still reaches 85% or more.

  Example 3
  The electrolyte of the high voltage lithium ion battery is an organic solvent, LiClO ₄ And 3-cyano-1, It consists of 3 propene sultones. Organic solvents are ethylene carbonate (EC) and ethyl methyl carbonate ( EMC), fluoroethylene carbonate (FEC) and 1,2,2-tetrafluoroether Chill-2,2,3,3-tetrafluoropropyl ether (CF ₂ HCF ₂ CH ₂ -O- CF ₂ CF ₂ H). Among them, the weight ratio of EC to EMC is EC: EMC = 1; 2 It is. 1,2,2-Tetrafluoroethyl-2,2,2 with a content of EFC of 12 wt% 3,3-tetrafluoropropyl ether (CF ₂ HCF ₂ CH ₂ -O-CF ₂ CF ₂ H Content of 6 wt%. 3-cyano-1,3 propene sultone in this electrolyte and The content of the additive is 3 wt%, and the concentration of the organic solvent is 1.2 mol / L.

  Method of preparing electrolyte of the above high voltage lithium ion battery
(1) After uniformly mixing the organic solvent, use 4 Å molecular sieves, lithium hydride, impurities, water Get rid of
(2) Dissolve the lithium salt in the mixed solvent at room temperature and stir uniformly.
(3) Then, 3-cyano-1,3 propene sultone was added and dissolved until it became transparent The solution is then filtered to obtain the electrolyte of the high voltage lithium ion battery.

  The electrolyte of the high voltage lithium ion battery of this embodiment is lithium cobaltate / graphite 3.0 to 4.95 V for lithium cobaltate / graphite cells at ambient temperature, used in ponds 1C Test the circulation performance of the charge and discharge. After circulation in 200 cycles, the The retention rate is 94%, and after circulation in 300 cycles, the retention rate of electrical capacity is 91% and After the cycle of 400 cycles, the retention rate of the electric capacity is 90%, and the cycle of 500 cycles is repeated. After ringing, the retention of capacitance still reaches 85% or more.

  Example 4
  The electrolyte of high voltage lithium ion battery is organic solvent, LiSO ₃ CF ₃ And 3-cyano- It consists of 1,3 propene sultone. Organic solvents are ethylene carbonate (EC) and ethyl carbonate (EMC), fluoro ethylene carbonate (CH ₃ -OCOO-CH ₂ CF ₃ )as well as 1,2,2-Tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (CF ₂ HCF ₂ CH ₂ -O-CF ₂ CF ₂ H). Among them, the weight of EC and EMC The quantitative ratio is EC: EMC = 1: 2. CH ₃ -OCOO-CH ₂ CF ₃ Content of 14 wt%, 1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropene Ruether (CF ₂ HCF ₂ CH ₂ -O-CF ₂ CF ₂ The content of H) is 7 wt%. Content of additive called 3-cyano-1,3 propene sultone in this electrolytic solution is 1wt% The concentration of the organic solvent is 1.2 mol / L.

  Method of preparing electrolyte of the above high voltage lithium ion battery
(1) After uniformly mixing the organic solvent, use 4 Å molecular sieves, lithium hydride, impurities, water Get rid of
(2) Dissolve the lithium salt in the mixed solvent at room temperature and stir uniformly.
(3) Then, 3-cyano-1,3 propene sultone was added and dissolved until it became transparent The solution is then filtered to obtain the electrolyte of the high voltage lithium ion battery.

  The electrolyte of the high voltage lithium ion battery of this embodiment is lithium cobaltate / graphite 3.0 to 4.95 V for lithium cobaltate / graphite cells at ambient temperature, used in ponds 1C Test the circulation performance of the charge and discharge. After circulation in 200 cycles, the The retention rate is 94%, and after circulation in 300 cycles, the retention rate of electrical capacity is 91% and After the cycle of 400 cycles, the retention rate of the electric capacity is 90%, and the cycle of 500 cycles is repeated. After ringing, the retention of capacitance still reaches 85% or more.

  Comparative Example 1
  Raw materials for electrolytes of high-voltage lithium-ion batteries are mainly organic solvents, lithium salts for electrical conduction And functional additives. Organic solvents are ethylene carbonate (EC), ethyl methyl carbonate (EM C), fluoroethylene carbonate (FEC) and 1,2,2-tetrafluoroethyl -2,2,3,3-tetrafluoropropyl ether (CF ₂ HCF ₂ CH ₂ -O-CF ₂ CF ₂ H). Among them, the weight ratio of EC to EMC is EC: EMC = 1: 2. Ru. 1,2,2-Tetrafluoroethyl-2,2,3, with an EFC content of 10 wt% 3-tetrafluoropropyl ether (CF ₂ HCF ₂ CH ₂ -O-CF ₂ CF ₂ H) The content is 5 wt%. Lithium salt is LiPF ₆ At a concentration of 1.2 m in organic solvent It is ol / L. The functional additive had a content of 2 wt% 1-propene 1,3-sultone ( PES).

  Method of preparing electrolyte of the above high voltage lithium ion battery
(1) After uniformly mixing the organic solvent, using 5 Å molecular sieves and lithium hydride, impurities, water Get rid of
(2) Dissolve the lithium salt in the mixed solvent at room temperature and stir uniformly.
(3) A functional additive is added to obtain an electrolyte solution of the high voltage lithium ion battery.

  Lithium nickel manganese (LiNi) was used as the electrolyte for the high voltage lithium ion battery of this example. _0.5 Mn _1.5 O ₄ ) Used in batteries, LiNi at normal temperature _0.5 Mn _1.5 O ₄ About battery Test the circulation performance of 3.0-4.95V, 1C magnification charge and discharge. Circulation in 200 cycles After ringing, the retention rate of the electrical capacity is 92%, and after being circulated for 300 cycles, The retention rate is 90%, and the retention rate of electrical capacity is 88% after circulation in 400 cycles. After the cycle of 500 times, the retention rate of electric capacity reaches 80%.

  Comparative Example 2
  Raw materials for electrolytes of high voltage lithium ion batteries mainly consist of organic solvents, lithium salts and additives including. Organic solvents include cyclic carbonate solvents (ethylene carbonate EC) and linear carbonates It consists of solvents (ethyl methyl carbonate EMC and diethyl carbonate DEC). EC and linear carbon dioxide S The weight ratio of tellurium is EC: EMC: DEC = 1: 1: 1. Lithium salt is LiPF ₆ so And the concentration in the organic solvent is 1.0 mol / L. Ordinary additives have a content of 1.0 w It consists of t% vinylene carbonate and sultone. Tetrafluoroterephthaloni in additives The content of tolyl is 1.0wt% and the content of 3-fluorobenzonitrile is 2.0wt% It is.

  Method of preparing the above electrolyte
(1) After uniformly mixing the organic solvent, using 5 Å molecular sieves and lithium hydride, impurities, water Get rid of
(2) Dissolve the lithium salt in the mixed solvent at room temperature and stir uniformly.
(3) Add commonly used additives such as vinylene carbonate and sultone and uniformly stir .
(4) adding tetrafluoroterephthalonitrile and 3-fluorobenzonitrile, An electrolyte for a high voltage lithium ion battery is obtained.

  The electrolyte of the high voltage lithium ion battery of this embodiment is lithium cobaltate / graphite Used for ponds, 3.0 to 4.5 V, 1 for lithium cobaltate / graphite cells at ambient temperature C Test circulation performance of charge and discharge. After circulation in 200 cycles, the capacity maintenance The holding rate is 90%, and after 300 cycles, the capacity retention rate is 85%, After the cycle of 400 cycles, the retention rate of electric capacity is 80%, and the cycle of 500 cycles After that, the capacity retention rate reaches 70%.

Claims (7)

  An organic solvent, a lithium salt and an additive, wherein the organic solvent is a cyclic carbonate solvent, An electrolyte for a high voltage lithium ion battery, comprising a fluorine solvent and a carbonate solvent,
  The additive is 3-cyano-1,3 propene sultone,
  The content of the additive in the electrolyte of the lithium ion battery is 0.5% to 1% by mass 0%,
  The fluorine-containing solvent is a fluorine-containing carbonic ester whose structural formula is the following chemical formula 1, and a structural formula is Fluorine-containing carbonate ester represented by Chemical Formula 2; and Fluorine-containing fluorinated ester represented by Chemical Formula 3 At least one of the following: ₁ ~ R ₆ Are both C _x F _y H _z And 1 ≦ x ≦ 6, y> 0, z ≧ 0,
  The said carbonate solvent is dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, propio Selected from one or more of methyl propionate, ethyl propionate and propyl propionate The electrolyte of high-voltage lithium-ion batteries.
  The concentration of the lithium salt in the organic solvent is 1 to 1.5 mol / L, and The high content according to claim 1, wherein the mass percentage of the fluorine-containing solvent in the solution is 2 to 50%. Electrolyte of voltage lithium ion battery.   The cyclic carbonate solvent is ethylene carbonate, propylene carbonate, γ-butyrolactone, γ The high voltage lithium according to claim 1, wherein the high voltage lithium is selected from one or more of valerolactones. The electrolyte of a mu-ion battery.   The lithium salt is LiPF ₆ , LiBF ₄ , LiSO ₃ CF ₃ , LiClO ₄ , Li N (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ Selected from one or more of The electrolyte of the high voltage lithium ion battery according to claim 1.   A method of preparing an electrolyte solution of a high voltage lithium ion battery according to claim 1,
  Impurity after mixing cyclic carbonate solvent, fluorine-containing solvent and carbonate solvent uniformly Substances and water are removed, and the lithium salt is dissolved in the mixed solvent at room temperature and stirred uniformly. Stir, then add 3-cyano-1,3 propene sultone and dissolve until clear High-voltage lithium-ion battery which is filtered to obtain an electrolyte of the high-voltage lithium-ion battery Method of preparing electrolyte solution.   After uniformly mixing cyclic carbonate solvent, fluorine-containing solvent and carbonate solvent, 4 Å The high voltage according to claim 5, wherein impurities and water are removed using a molecular sieve and lithium hydride. Method of preparing electrolyte of lithium ion battery.   The high current in the electrolyte solution of the high voltage lithium ion battery according to any one of claims 1 to 4. Application to the preparation of high pressure lithium ion batteries.