WO2014114068A1 - Non-aqueous organic electrolyte, preparation method therefor and lithium ion secondary battery - Google Patents

Abstract

Disclosed are a non-aqueous organic electrolyte, a preparation method therefor and a lithium ion secondary battery containing the non-aqueous organic electrolyte. The non-aqueous organic electrolyte comprises: a lithium salt, a non-aqueous organic solvent, and a non-aqueous organic electrolyte additive. The non-aqueous organic electrolyte additive is a non-aqueous organic electrolyte additive as shown in formula (I) and/or a non-aqueous organic electrolyte additive as shown in formula (II). The present invention solves the problem in the prior art of easy occurrence of side reaction between the non-aqueous organic electrolyte and a positive electrode active material in a fully-charged and high-voltage (a voltage of above 4.5 V) battery system which results in the cycle performance decrease, volume expansion and discharge capacity decrease of a lithium ion secondary battery. The non-aqueous organic electrolyte still shows good cycle performance in an operating environment with a high voltage of about 4.9 V.

Description

 Non-aqueous organic electrolyte and preparation method thereof and lithium ion secondary battery The present application claims to be submitted to the Chinese Patent Office on January 28, 2013, the application number 201310031863.0, the invention name is "a non-aqueous organic electrolyte and The priority of the preparation method and the Chinese patent application of the lithium ion secondary battery is hereby incorporated by reference in its entirety. Technical field

 The present invention relates to the field of lithium ion secondary batteries, and more particularly to a nonaqueous organic electrolyte and a method of preparing the same, and a lithium ion secondary battery. Background technique

 With the expansion of the application field of lithium ion secondary batteries, including the introduction of new application scenarios such as large-scale energy storage power stations and high-temperature base station backup power in recent years, the demand for high-energy lithium-ion secondary batteries has become more urgent. .

In order to realize high energy of a lithium ion secondary battery, it is generally achieved by increasing the operating voltage of a lithium ion secondary battery or developing a high energy positive electrode material. The high-voltage positive electrode material has been reported to have a lithium-rich solid solution xLi ₂ Mn0 ₃ ( lx)LiM0 ₂ and a spinel LiNio.sMn C^, etc., and the charging voltage is close to or higher than 5 V, but the matching non-aqueous organic electrolyte Existing reports. Currently the commonly used electrolyte lithium ion secondary battery mainly 1M LiPF ₆ dissolved in a carbonate-based solvent, but the high voltage at full charge (4.5V above voltage) of the battery system, the positive electrode active material are particularly vulnerable to side reactions Further, it is oxidatively decomposed, resulting in a decrease in cycle performance, volume expansion, and discharge capacity of the lithium ion secondary battery, and thus cannot be applied to a high-voltage lithium ion secondary battery system.

In recent years, some researchers have proposed to add anti-oxidation potentials to non-aqueous organic electrolytes to reach high-voltage solvents such as sulfones, nitriles, and ionic liquids above 5V to improve the resistance of non-aqueous organic electrolytes. The oxidizing property further enables the lithium ion secondary battery to be used at a voltage of 4.5 V or more. However, the high viscosity of these high-voltage solvents will lead to a decrease in the conductivity of the non-aqueous organic electrolyte. At the same time, these high-voltage solvent wettability oOR = I - poor, thus causing a decrease in the discharge capacity of the lithium ion secondary battery.

 o

 † R o o= I I

SUMMARY OF THE INVENTION In order to solve the above problems, a first aspect of embodiments of the present invention is directed to a non-aqueous organic electrolyte for solving a non-aqueous organic electrolyte in a prior art battery at a full charge high voltage (voltage greater than 4.5V). In the system, the side reaction of the positive electrode active material is liable to cause a problem of a decrease in cycle performance, volume expansion, and discharge capacity of the lithium ion secondary battery. The non-aqueous organic electrolyte still exhibits in a high voltage working environment of about 4.9V. Good cycle performance. A second aspect of the embodiment of the present invention is to provide a method for producing the above nonaqueous organic electrolyte. A third aspect of the embodiment of the invention is directed to a lithium ion secondary battery comprising the above nonaqueous organic electrolyte, which has a high energy density. In a first aspect, an embodiment of the present invention provides a non-aqueous organic electrolyte, comprising: a lithium salt; a non-aqueous organic solvent; and a non-aqueous organic electrolyte additive, wherein the non-aqueous organic electrolyte additive is of the formula (I) a non-aqueous organic electrolyte additive as shown and/or a non-aqueous organic electrolyte additive as shown in formula (II),

R — 0 — R ₄

3 (I),

R ₅ — 0― P— 0— P— 0— R ₈

 I I

 0 0

 1 I

R ₆ R ₇ (II),

Wherein R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are a straight or branched alkyl group of Cr^do, C^do Alkenyl group, Cr^do alkyne group or C ₆ -C ₁₄ aromatic group, or Ri, R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are halogen-containing: Cr^ a linear or branched alkyl group of do, an alkene group of Cu), an alkyne group of Cr^do or an aromatic group of C _{6 to} C ₁₄ .

The non-aqueous organic electrolyte additive represented by the formula (I) in the embodiment of the present invention is a derivative of pyrophosphate, and the non-aqueous organic electrolyte additive represented by the formula (II) is pyrophosphite. derivative. R ₂ , R ₃ and R ₄ may be the same structure or different. R ₅ , R ₆ , R ₇ and R ₈ may be the same structure or different.

Preferably, in the non-aqueous organic electrolyte additive represented by the formula (I), R ₂ , R ₃ and R 4 are a mercapto group, an ethyl group, an ethyl trifluoromethyl group, a trifluoroethyl group, a perfluoroethyl group, a phenyl group, Benzyl, partially or perfluoro substituted phenyl. R ₂ , R ₃ and R ₄ may be the same structure or different.

Preferably, in the non-aqueous organic electrolyte additive represented by the formula (II), R ₅ , R ₆ , R ₇ and R ₈ are an indenyl group, an ethyl group, a trifluoromethyl group, a trifluoroethyl group, a perfluoroethyl group. , phenyl, benzyl, partially or perfluoro substituted phenyl. R ₅ , R ₆ , R ₇ and R ₈ may be the same structure or different.

Lithium salt is used as a carrier to ensure the basic operation of lithium ions in lithium ion secondary batteries, including but not limited to lithium hexafluorophosphate (LiPF ₆ ), lithium perchlorate (LiC10 ₄ ), lithium tetrafluoroborate (LiBF ₄ ), hexafluoride Lithium arsenate (LiAsF ₆ ), lithium hexafluorosilicate (LiSiF ₆ ), lithium tetraphenylborate (LiB(C _{6 3⁄4} ) ₄ ), lithium chloride (LiCl), lithium bromide (LiBr), lithium chloroaluminate ( LiAlCl ₄ ), lithium bis(oxalate)borate (LiBOB), lithium trifluoromethanesulfonate (LiCF ₃ S0 ₃ ), lithium perfluorobutyl sulfonate (LiC ₄ F ₉ S0 ₃ ), lithium fluorosulfonimide ( LiN(C _x F _2x+1 S0 ₂ ) (C _y F _2y+1 S0 ₂ ) (where x and y are less than 21 natural numbers) and lithosium (Lil).

The final concentration of the lithium salt in the non-aqueous organic electrolyte is not limited and is usually from 0.5 to 2.0 mol/L. Preferably, the final concentration of the lithium salt in the non-aqueous organic electrolyte is from 0.7 to 1.6 mol/L. When the final concentration of the lithium salt is preferably within this range, the non-aqueous organic electrolyte of the embodiment of the present invention can simultaneously provide better lithium ion conductivity and lithium ion mobility. The non-aqueous organic solvent is selected from solvents conventional in the art and may be one or more of aliphatic or cyclic carbonates, ethers, sulfones, nitriles, ionic liquids, and derivatives thereof, including but not limited to Y-butyl Lactone (GBL), ethylene carbonate (EC), diethyl carbonate (DEC), dinonyl carbonate (DMC), vinylene carbonate (VC), ethyl cerium carbonate (EMC), dipropyl carbonate ( DPC), propyl propyl carbonate (MPC), propylene carbonate (PC), decyl decanoate (MF), decyl acrylate (MA), decyl butyrate (MB) ethyl acetate (EP), ethylene sulfite Ester (ES), propylene sulfite (PS), sulfonium sulfide (DMS), diethyl sulfite (DES), tetrahydrofuran, acid anhydride, N-mercaptopyrrolidone, N-mercaptocarboxamide, N-based Acetamide, acetonitrile, N, N-dimercaptoamide, sulfolane, disulfoxide, dinonyl sulfite, and other fluorine-containing, sulfur-containing or unsaturated bond-containing cyclic organic esters.

 Preferably, the non-aqueous organic solvent accounts for 85% to 99.5% of the non-aqueous organic electrolyte, and the non-aqueous organic electrolyte additive accounts for 0.5% to 15% of the non-aqueous organic electrolyte.

 More preferably, the non-aqueous organic solvent accounts for 92% to 99% of the non-aqueous organic electrolyte, and the non-aqueous organic electrolyte additive accounts for 1% to 8% of the non-aqueous organic electrolyte.

In order to meet the application requirements of the non-aqueous organic electrolyte in a specific situation, preferably, the non-aqueous organic electrolyte further includes a functional auxiliary agent selected from the group consisting of a cyclic additive, a high temperature additive, a flame retardant additive, and an overcharge additive. One or several. The functional auxiliaries include, but are not limited to, vinylene carbonate (VC), biphenyl, cyclohexylbenzene, 2,52 di-tert-butyl 21,42-dimethoxybenzene (DDB), thiophene, . Dithiazine, lithium carbonate, carbon dioxide, 1,3-propane sultone (PS), ethylene carbonate (FEC) and lithium tetrafluoroborate (LiBF ₄ ), tridecyl phosphate, triethyl phosphate, triphenyl phosphate Ester, tributyl phosphate and phosphazene compounds.

 Preferably, the functional additive accounts for 0.1% to 15% of the non-aqueous organic electrolyte by mass fraction.

The non-aqueous organic electrolyte provided by the first aspect of the present invention can be used in a working environment of full charge high voltage (voltage above 4.5V), has excellent chemical stability and electrochemical stability, and can avoid high voltage. The phenomenon of gas expansion under the lithium ion secondary battery, and the improvement of lithium ion II under high voltage The cycle performance and discharge capacity of the secondary battery. The non-aqueous organic electrolyte still exhibits good cycle performance in a high voltage working environment of about 4.9V. This may be because: During the charging process of the lithium ion secondary battery, the potential difference between the positive and negative electrodes is not OR OR=——I broken_, rises, when the potential difference reaches 4.5V and above 4.5V, non-aqueous organic electrolysis o

a non-aqueous organic electrolyte additive as shown in formula (I) and/or a non-aqueous one as shown in formula (II)

 † R . o= I I

Part of the phosphorus-oxygen bond of the organic electrolyte additive is broken, and part of the phosphorus-containing fraction interacts with a product formed by oxidative decomposition of a non-aqueous organic solvent or a lithium salt to form an electron-conducting, ion-conducting phosphorus-containing element on the surface of the positive electrode active material. The surface film covers the active site on the surface of the positive active material, blocks the direct contact between the active site on the surface of the positive active material and the non-aqueous organic electrolyte, and reduces the oxidation of the positive active material on the non-aqueous organic electrolyte, thereby improving The cycle performance of a lithium ion secondary battery at a high voltage, and the case where the volume expansion of the lithium ion secondary battery and the discharge capacity are prevented. In a second aspect, an embodiment of the present invention provides a method for preparing a non-aqueous organic electrolyte, comprising the steps of: dissolving a lithium salt in a non-aqueous organic solvent, and adding a non-aqueous organic electrolyte as shown in formula (I) Adding an additive and/or a non-aqueous organic electrolyte additive as shown in formula (II) to a non-aqueous organic electrolyte,

R — 0 — R ₄

3 (I),

R ₅ — 0― P— 0— P— 0— R ₈

 I I

 0 0

 1 I

R ₆ R ₇ (II),

Wherein R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are a straight or branched alkyl group of Cr^do, an alkene group of C^do, an alkyne group of Cr^do or C An aromatic group of _{6 to} C ₁₄ or Ri, R ₂ , R ₃ , R ₄ , R ₅ , R ₆ ,

R ₇ and R ₈ are halogen-containing: a straight or branched alkyl group of Cr^do, an alkene group of Cu), an alkyne group of CH^o or an aromatic group of C _{6 to} C ₁₄ . Preferably, in the non-aqueous organic electrolyte additive represented by the formula (I), R ₂ , R ₃ and R 4 are a mercapto group, an ethyl group, an ethyl trifluoromethyl group, a trifluoroethyl group, a perfluoroethyl group, a phenyl group, Benzyl, partially or perfluoro substituted phenyl. R ₂ , R ₃ and R ₄ may be the same structure or different.

Preferably, in the non-aqueous organic electrolyte additive represented by the formula (II), R ₅ , R ₆ , R ₇ and R ₈ are an indenyl group, an ethyl group, a trifluoromethyl group, a trifluoroethyl group, a perfluoroethyl group. , phenyl, benzyl, partially or perfluoro substituted phenyl. R ₅ , R ₆ , R ₇ and R ₈ may be the same structure or different.

 Preferably, the preparation method of the non-aqueous organic electrolyte is carried out in an argon-filled glove box.

 Preferably, the lithium salt is dissolved in a non-aqueous organic solvent for a controlled temperature of 20 to 35 °C. In the preferred temperature range, it is possible to avoid the volatilization of the non-aqueous organic solvent and to avoid the decomposition of the lithium salt, and to prevent the dissolution of the lithium salt due to the freezing of the non-aqueous organic solvent due to the excessive temperature.

Lithium salt is used as a carrier to ensure the basic operation of lithium ions in lithium ion secondary batteries, including but not limited to lithium hexafluorophosphate (LiPF ₆ ), lithium perchlorate (LiC10 ₄ ), lithium tetrafluoroborate (LiBF ₄ ), hexafluoride Lithium arsenate (LiAsF ₆ ), lithium hexafluorosilicate (LiSiF ₆ ), lithium tetraphenylborate (LiB(C _{6 3⁄4} ) ₄ ), lithium chloride (LiCl), lithium bromide (LiBr), lithium chloroaluminate ( LiAlCl ₄ ), lithium bis(oxalate)borate (LiBOB), lithium trifluoromethanesulfonate (LiCF ₃ S0 ₃ ), lithium perfluorobutyl sulfonate (LiC ₄ F ₉ S0 ₃ ), lithium fluorosulfonimide ( LiN(C _x F _2x+1 S0 ₂ ) (C _y F _2y+1 S0 ₂ ) (where x and y are less than 21 natural numbers) and lithosium (Lil).

 The final concentration of the lithium salt in the non-aqueous organic electrolyte is not limited and is usually 0.5 to 2.0 mol/L. Preferably, the final concentration of the lithium salt in the non-aqueous organic electrolyte is from 0.7 to 1.6 mol/L. When the final concentration of the lithium salt is preferably within this range, the non-aqueous organic electrolyte of the embodiment of the present invention can simultaneously provide better lithium ion conductivity and lithium ion mobility.

The non-aqueous organic solvent is selected from solvents conventional in the art and may be one or more of aliphatic or cyclic carbonates, ethers, sulfones, nitriles, ionic liquids, and derivatives thereof, including but not limited to Y-butyl Lactone (GBL), ethylene carbonate (EC), diethyl carbonate (DEC), dinonyl carbonate (DMC), vinylene carbonate (VC), Ethyl carbonate (EMC), dipropyl carbonate (DPC), propyl propyl carbonate (MPC), propylene carbonate (PC), decyl decanoate (MF), decyl acrylate (MA), decyl butyrate (MB) ethyl acetate (EP), vinyl sulfite (ES), propylene sulfite (PS), sulfonium sulfide (DMS), diethyl sulfite (DES), tetrahydrofuran, anhydride, N-曱Pyrrolidone, N-mercaptocarboxamide, N-yl acetamide, acetonitrile, N, N-dimercaptoamide, sulfolane, disulfoxide, dinonyl sulfite and other fluorine-containing, sulfur-containing or non-containing A cyclic organic ester of a saturated bond.

 Preferably, the non-aqueous organic solvent accounts for 85% to 99.5% of the non-aqueous organic electrolyte, and the non-aqueous organic electrolyte additive accounts for 0.5% to 15% of the non-aqueous organic electrolyte.

 More preferably, the non-aqueous organic solvent accounts for 92% to 99% of the non-aqueous organic electrolyte, and the non-aqueous organic electrolyte additive accounts for 1% to 8% of the non-aqueous organic electrolyte.

In order to meet the application requirements of the non-aqueous organic electrolyte in a specific situation, it is preferable to add a non-aqueous organic compound as shown in formula (I) to the preparation method of the non-aqueous organic electrolyte provided by the second aspect of the present invention. After the electrolyte additive and/or the non-aqueous organic electrolyte additive as shown in formula (II), further comprising adding a functional auxiliary agent selected from the group consisting of a cyclic additive, a high temperature additive, a flame retardant additive, and an overcharge additive One or more of the functional auxiliaries include, but are not limited to, vinylene carbonate (VC), biphenyl, cyclohexylbenzene, 2, 52 di-tert-butyl 21,42 didecyloxybenzene (DDB), Thiophene, phenothiazine, lithium carbonate, carbon dioxide, 1,3-propane sultone, ethylene carbonate (FEC) and lithium tetrafluoroborate (LiBF ₄ ), tridecyl phosphate, triethyl phosphate, triphenyl phosphate , tributyl phosphate and phosphazene compounds.

 Preferably, the functional additive accounts for 0.1% to 15% of the non-aqueous organic electrolyte by mass fraction.

 A method for preparing a non-aqueous organic electrolyte provided by a second aspect of the present invention provides a novel non-aqueous organic electrolyte, and the preparation method is simple.

In a third aspect, an embodiment of the present invention provides a lithium ion secondary battery, including: a positive electrode, a negative electrode, a separator, a casing, and a non-aqueous organic electrolyte, the non-aqueous organic electrolyte, including: lithium salt, non-aqueous Have a solvent, and a non-aqueous organic electrolyte additive as shown in formula (I) and/or a non-aqueous organic electrolyte additive as shown in formula (II),

(I),

R ₅ — 0― P— 0— P— 0— R ₈

 I I

 0 0

 1 I

R ₆ R ₇ (II),

Wherein R ₂ , R ₃ , R ₅ , R ₆ , R ₇ and R ₈ are a straight or branched alkyl group of Cr^o, an alkene group of C^do, an alkyne group of Cr^do or C ₆ 〜 An aromatic group of C ₁₄ or Ri, R ₂ , R ₃ , R ₄ , R ₅ , R ₆ ,

R ₇ and R ₈ are halogen-containing: a straight or branched alkyl group of Cr^do, an alkene group of Cu), an alkyne group of CH^o or an aromatic group of C _{6 to} C ₁₄ .

 The non-aqueous organic electrolyte is as described in the first aspect of the embodiment of the present invention, and details are not described herein again.

The positive electrode includes a positive active material capable of inserting or extracting lithium ions. Preferably, the positive active material has a high deintercalation lithium platform at a voltage of 4.5 V and above and above at the time of charge and discharge deintercalation of lithium ions. More preferably, the positive active material is LiM _x Mn _x )0 ₄ , wherein M is selected from one or more of transition metals Ni, Co and Fe, 0 X 2 . And more preferably, the positive active material is xLi ₂ Mn0 ₃ ( 1 -x)LiM0 ₂ , wherein ruthenium is selected from one or more of transition metals Ni, Co and Mn, 0 x 1. The lithium ion secondary battery provided in the third aspect of the embodiment of the present invention is not limited in form, and may be a square, cylindrical or soft pack battery, and the lithium ion secondary battery has high energy whether it is wound or laminated. Density, good cycle performance and discharge capacity.

The lithium ion secondary battery is prepared by forming a positive electrode, a negative electrode and a separator into a battery core, placing the same in a casing, injecting the non-aqueous organic electrolyte, and sealing to obtain a lithium ion secondary battery. Lithium ion The preparation method of the secondary battery is simple and feasible.

 The advantages of the embodiments of the present invention will be partially explained in the following description.

 o, a part of which is apparent from the description, † or o OR = -I can be known by the implementation of the embodiments of the present invention.

 o

DETAILED DESCRIPTION OF THE INVENTION † R o o=— I

 o

 The following is a preferred embodiment of the embodiment of the present invention, and it should be noted that those skilled in the art can make some improvements and refinements without departing from the principles of the embodiments of the present invention. Improvements and retouching are also considered to be the scope of protection of embodiments of the present invention.

 The first aspect of the present invention provides a non-aqueous organic electrolyte for solving the problem that the non-aqueous organic electrolyte in the prior art is easily generated with the positive active material in a fully charged high voltage (voltage above 4.5V) battery system. The side reaction causes a problem of a decrease in cycle performance, volume expansion, and discharge capacity of the lithium ion secondary battery, and the non-aqueous organic electrolyte exhibits good cycle performance in a high-voltage working environment of about 4.9V. A second aspect of the embodiment of the present invention provides a method of producing the above nonaqueous organic electrolyte. A third aspect of the present invention provides a lithium ion secondary battery comprising the above nonaqueous organic electrolyte, the lithium ion secondary battery having a high energy density.

 In a first aspect, an embodiment of the present invention provides a non-aqueous organic electrolyte, comprising:

 Lithium salt

 a non-aqueous organic solvent; and a non-aqueous organic electrolyte additive, the non-aqueous organic electrolyte additive as shown in formula (I) and/or a non-aqueous organic compound as shown in formula (II) Electrolyte additive,

R R ₅ — O— P— O— P— O— R ₈

 I I

 0 o

 1 I

R ₆ R ₇ (II),

Wherein R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are a linear or branched alkyl group of C^do, an alkene group of C^do, an alkyne group of Cr^do or C An aromatic group of _{6 to} C ₁₄ or Ri, R ₂ , R ₃ , R ₄ , R ₅ , R ₆ ,

R ₇ and R ₈ are halogen-containing: a straight or branched alkyl group of Cr^do, an olefin group of Cu), an alkyne group of Cr^do or an aromatic group of C _{6 to} C ₁₄ .

The non-aqueous organic electrolyte additive represented by the formula (I) in the embodiment of the present invention is a derivative of pyrophosphate, and the non-aqueous organic electrolyte additive represented by the formula (II) is pyrophosphite. derivative. R ₂ , R ₃ and R ₄ may be the same structure or different. R ₅ , R ₆ , R ₇ and R ₈ may be the same structure or different.

In the non-aqueous organic electrolyte additive represented by the formula (I), R ₂ , R ₃ and R ₄ are a mercapto group, an ethyl group, a trifluoromethyl group, a trifluoroethyl group, a perfluoroethyl group, a phenyl group, a benzyl group. , partial or perfluoro substituted phenyl. R ₂ , R ₃ and R ₄ may be the same structure or different.

In the non-aqueous organic electrolyte additive represented by the formula (II), R ₅ , R ₆ , R ₇ and R ₈ are an indenyl group, an ethyl group, an ethyl trifluoromethyl group, a trifluoroethyl group, a perfluoroethyl group, a phenyl group. , benzyl, partially or perfluoro substituted phenyl. R ₅ , R ₆ , R ₇ and R ₈ may be the same structure or different.

Lithium salt is used as a carrier to ensure the basic operation of lithium ions in lithium ion secondary batteries, including but not limited to lithium hexafluorophosphate (LiPF ₆ ), lithium perchlorate (LiC10 ₄ ), lithium tetrafluoroborate (LiBF ₄ ), hexafluoride Lithium arsenate (LiAsF ₆ ), lithium hexafluorosilicate (LiSiF ₆ ), lithium tetraphenylborate (LiB(C _{6 3⁄4} ) ₄ ), lithium chloride (LiCl), lithium bromide (LiBr), lithium chloroaluminate ( LiAlCl ₄ ), lithium bis(oxalate)borate (LiBOB), lithium trifluoromethanesulfonate (LiCF ₃ S0 ₃ ), lithium perfluorobutyl sulfonate (LiC ₄ F ₉ S0 ₃ ), lithium fluorosulfonimide ( LiN(C _x F _2x+1 S0 ₂ ) (C _y F _2y+1 S0 ₂ ) (where x and y are less than 21 natural numbers) and lithosium (Lil).

The final concentration of the lithium salt in the non-aqueous organic electrolyte is not limited and is usually from 0.5 to 2.0 mol/L. Specifically, The final concentration of the lithium salt in the non-aqueous organic electrolyte is 0.7 to 1.6 mol/L. When the final concentration of the lithium salt is preferably within this range, the non-aqueous organic electrolyte of the embodiment of the present invention can simultaneously provide better lithium ion conductivity and lithium ion mobility.

 The non-aqueous organic solvent is selected from solvents conventional in the art and may be one or more of aliphatic or cyclic carbonates, ethers, sulfones, nitriles, ionic liquids, and derivatives thereof, including but not limited to Y-butyl Lactone (GBL), ethylene carbonate (EC), diethyl carbonate (DEC), dinonyl carbonate (DMC), vinylene carbonate (VC), ethyl cerium carbonate (EMC), dipropyl carbonate ( DPC), propyl propyl carbonate (MPC), propylene carbonate (PC), decyl decanoate (MF), decyl acrylate (MA), decyl butyrate (MB) ethyl acetate (EP), ethylene sulfite Ester (ES), propylene sulfite (PS), sulfonium sulfide (DMS), diethyl sulfite (DES), tetrahydrofuran, acid anhydride, N-mercaptopyrrolidone, N-mercaptocarboxamide, N-based Acetamide, acetonitrile, N, N-dimercaptoamide, sulfolane, disulfoxide, dinonyl sulfite, and other fluorine-containing, sulfur-containing or unsaturated bond-containing cyclic organic esters.

 According to the mass fraction, the non-aqueous organic solvent accounts for 85% to 99.5% of the non-aqueous organic electrolyte, and the non-aqueous organic electrolyte additive accounts for 0.5% to 15% of the non-aqueous organic electrolyte. Specifically, the non-aqueous organic solvent accounts for 92% to 99% of the non-aqueous organic electrolyte, and the non-aqueous organic electrolyte additive accounts for 1% to 8% of the non-aqueous organic electrolytic solution.

In order to meet the application requirements of the non-aqueous organic electrolyte in a specific situation, the non-aqueous organic electrolyte may further include a functional auxiliary agent selected from the group consisting of a cyclic additive, a high-temperature additive, a flame retardant additive, and an overcharge additive. Kind or several. The functional auxiliaries include, but are not limited to, vinylene carbonate (VC), biphenyl, cyclohexylbenzene, 2, 52 di-tert-butyl 21,42 didecyloxybenzene (DDB), thiophene, phenothiazine, carbonic acid Lithium, carbon dioxide, 1,3 propane lactone (PS), ethylene carbonate (FEC) and lithium tetrafluoroborate (LiBF ₄ ), tridecyl phosphate, triethyl phosphate, triphenyl phosphate, tributyl phosphate Ester and phosphazene compounds.

According to the mass fraction, the functional additives account for 0.1% to 15% of the non-aqueous organic electrolyte. The non-aqueous organic electrolyte provided by the first aspect of the present invention can be used in a working environment of full charge high voltage (voltage above 4.5V), has excellent chemical stability and electrochemical stability, and can avoid high voltage. Under o OR=——I Lithium_, the phenomenon of gas expansion of ion secondary batteries, and the increase of lithium ion at high voltage

The cycle performance and discharge capacity of the secondary battery. The non-aqueous organic electrolyte is operated at a high voltage of about 4.9V.

 † R . o= I I

It still shows good cycle performance in the environment. This may be because: During the charging process of the lithium ion secondary battery, the potential difference between the positive and negative electrodes is continuously increased. When the potential difference reaches 4.5V and 4.5V or higher, the non-aqueous organic electrolyte is in the formula (I). The non-aqueous organic electrolyte additive and/or the non-aqueous organic electrolyte additive as shown in formula (II) are partially broken by phosphorus-oxygen bonds, and some of the phosphorus-containing fragments are formed by oxidative decomposition of a non-aqueous organic solvent or a lithium salt. The product interacts to form an electron-conducting, ion-conducting surface film containing phosphorus on the surface of the positive electrode active material, covering the active site on the surface of the positive electrode active material, blocking the active site on the surface of the positive electrode active material and non-aqueous organic electrolysis The direct contact of the liquid reduces the oxidation of the positive electrode active material to the non-aqueous organic electrolyte, thereby improving the cycle performance of the lithium ion secondary battery at a high voltage, and avoiding the volume expansion of the lithium ion secondary battery and the decrease in the discharge capacity. In a second aspect, an embodiment of the present invention provides a method for preparing a non-aqueous organic electrolyte, comprising the steps of: dissolving a lithium salt in a non-aqueous organic solvent, and adding a non-aqueous organic electrolyte as shown in formula (I) Adding an additive and/or a non-aqueous organic electrolyte additive as shown in formula (II) to a non-aqueous organic electrolyte,

R — 0 — R ₄

3 (I),

R ₅ — 0― P— 0— P— 0— R ₈

 I I

 0 0

 1 I

R ₆ R ₇ (II),

Wherein R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are a straight or branched alkyl group of Cr^do, C^do Alkenyl group, Cr^do alkyne group or C ₆ -C ₁₄ aromatic group, or Ri, R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are halogen-containing: Cr^ a linear or branched alkyl group of do, an alkene group of Cu), an alkyne group of Cr^do or an aromatic group of C _{6 to} C ₁₄ .

In the non-aqueous organic electrolyte additive represented by the formula (I), R ₂ , R ₃ and R ₄ are a mercapto group, an ethyl group, a trifluoromethyl group, a trifluoroethyl group, a perfluoroethyl group, a phenyl group, a benzyl group. , partial or perfluoro substituted phenyl. R ₂ , R ₃ and R ₄ may be the same structure or different.

In the non-aqueous organic electrolyte additive represented by the formula (II), R ₅ , R ₆ , R ₇ and R ₈ are an indenyl group, an ethyl group, an ethyl trifluoromethyl group, a trifluoroethyl group, a perfluoroethyl group, a phenyl group. , benzyl, partially or perfluoro substituted phenyl. R ₅ , R ₆ , R ₇ and R ₈ may be the same structure or different.

 The preparation method of the non-aqueous organic electrolyte is carried out in an argon-filled glove box.

 The lithium salt is dissolved in a non-aqueous organic solvent and the temperature is controlled at 20 to 35 °C. In this preferred temperature range, it is possible to avoid the volatilization of the non-aqueous organic solvent and to avoid the decomposition of the lithium salt, and to prevent the dissolution of the lithium salt due to the freezing of the non-aqueous organic solvent due to the low temperature.

Lithium salt is used as a carrier to ensure the basic operation of lithium ions in lithium ion secondary batteries, including but not limited to lithium hexafluorophosphate (LiPF ₆ ), lithium perchlorate (LiC10 ₄ ), lithium tetrafluoroborate (LiBF ₄ ), hexafluoride Lithium arsenate (LiAsF ₆ ), lithium hexafluorosilicate (LiSiF ₆ ), lithium tetraphenylborate (LiB(C _{6 3⁄4} ) ₄ ), lithium chloride (LiCl), lithium bromide (LiBr), lithium chloroaluminate ( LiAlCl ₄ ), lithium bis(oxalate)borate (LiBOB), lithium trifluoromethanesulfonate (LiCF ₃ S0 ₃ ), lithium perfluorobutyl sulfonate (LiC ₄ F ₉ S0 ₃ ), lithium fluorosulfonimide ( LiN(C _x F _2x+1 S0 ₂ ) (C _y F _2y+1 S0 ₂ ) (where x and y are less than 21 natural numbers) and lithosium (Lil).

The final concentration of the lithium salt in the non-aqueous organic electrolyte is not limited and is usually from 0.5 to 2.0 mol/L. Specifically, the final concentration of the lithium salt in the non-aqueous organic electrolyte is 0.7 to 1.6 mol/L. When the final concentration of the lithium salt is preferably within this range, the non-aqueous organic electrolyte of the embodiment of the present invention can simultaneously provide better lithium ion conductivity and lithium ion mobility. The non-aqueous organic solvent is selected from solvents conventional in the art and may be one or more of aliphatic or cyclic carbonates, ethers, sulfones, nitriles, ionic liquids, and derivatives thereof, including but not limited to Y-butyl Lactone (GBL), ethylene carbonate (EC), diethyl carbonate (DEC), dinonyl carbonate (DMC), vinylene carbonate (VC), ethyl cerium carbonate (EMC), dipropyl carbonate ( DPC), propyl propyl carbonate (MPC), propylene carbonate (PC), decyl decanoate (MF), decyl acrylate (MA), decyl butyrate (MB) ethyl acetate (EP), ethylene sulfite Ester (ES), propylene sulfite (PS), sulfonium sulfide (DMS), diethyl sulfite (DES), tetrahydrofuran, acid anhydride, N-mercaptopyrrolidone, N-mercaptocarboxamide, N-based Acetamide, acetonitrile, N, N-dimercaptoamide, sulfolane, disulfoxide, dinonyl sulfite, and other fluorine-containing, sulfur-containing or unsaturated bond-containing cyclic organic esters.

 According to the mass fraction, the non-aqueous organic solvent accounts for 85% to 99.5% of the non-aqueous organic electrolyte, and the non-aqueous organic electrolyte additive accounts for 0.5% to 15% of the non-aqueous organic electrolyte. Specifically, the non-aqueous organic solvent accounts for 92% to 99% of the non-aqueous organic electrolyte, and the non-aqueous organic electrolyte additive accounts for 1% to 8% of the non-aqueous organic electrolytic solution.

In order to meet the application requirements of the non-aqueous organic electrolyte in a specific situation, the non-aqueous organic electrolyte additive represented by the formula (I) is added to the preparation method of the non-aqueous organic electrolyte provided by the second aspect of the present invention. And/or after the non-aqueous organic electrolyte additive as shown in formula (II), further comprising adding a functional auxiliary agent selected from the group consisting of a cyclic additive, a high temperature additive, a flame retardant additive, and an overcharge additive. Or several, the functional auxiliaries include, but are not limited to, vinylene carbonate (VC), biphenyl, cyclohexylbenzene, 2, 52 di-tert-butyl 21,42 didecyloxybenzene (DDB), thiophene, . Dithiazine, lithium carbonate, carbon dioxide, 1,3-propane sultone, ethylene carbonate (FEC) and lithium tetrafluoroborate (LiBF ₄ ), tridecyl phosphate, triethyl phosphate, triphenyl phosphate, phosphoric acid Tributyl ester and phosphazene compounds.

 According to the mass fraction, the functional additives account for 0.1% to 15% of the non-aqueous organic electrolyte.

A method for preparing a non-aqueous organic electrolyte provided by a second aspect of the present invention provides a method The new non-aqueous organic electrolyte has a simple process. In a third aspect, an embodiment of the present invention provides a lithium ion secondary battery, including: a positive electrode, a negative electrode, and o

The separator, the shell and the OR OR II non-aqueous organic electrolyte, the non-aqueous organic electrolyte, including: lithium salt, non-aqueous o

a solvent, and a non-aqueous organic electrolyte additive as shown in formula (I) and/or as shown in formula (II)

 † R . o= I I

Non-aqueous organic electrolyte additive,

R — 0 — R ₄

3 (I),

R ₅ — 0― P— 0— P— 0— R ₈

 I I

 0 0

 1 I

R ₆ R ₇ (II),

Wherein R ₂ , R ₃ , R ₅ , R ₆ , R ₇ and R ₈ are a linear or branched alkyl group of C^Q, an alkene group of C^do, an alkyne group of Cr^do or C ₆ 〜 An aromatic group of C ₁₄ or Ri, R ₂ , R ₃ , R ₄ , R ₅ , R ₆ ,

R ₇ and R ₈ are halogen-containing: a straight or branched alkyl group of Cr^do, an alkene group of Cu), an alkyne group of CH^o or an aromatic group of C _{6 to} C ₁₄ . The non-aqueous organic electrolyte is as described in the first aspect of the embodiment of the present invention, and details are not described herein again. The positive electrode includes a positive active material capable of inserting or extracting lithium ions. The positive active material has a high deintercalation lithium platform at a voltage of 4.5 V and 4.5 V or higher during charge and discharge deintercalation of lithium ions. The positive active material may be LiM _x Mn^ _x )0 ₄ , wherein M is selected from one or more of transition metals Ni, Co, and Fe.

0 X 2. And, the positive active material may be xLi ₂ Mn0 ₃ ( 1 -x)LiM0 ₂ , wherein ruthenium is selected from one or more of transition metals Ni, Co, and Mn, 0 χ 1. The lithium ion secondary battery provided in the third aspect of the embodiment of the present invention is not limited in form, and may be a square, cylindrical or soft pack battery, and the lithium ion secondary battery has high energy whether it is wound or laminated. Density, good cycle performance and discharge capacity. The lithium ion secondary battery is prepared by forming a positive electrode, a negative electrode and a separator into a battery core, placing the same in a casing, injecting the non-aqueous organic electrolyte, and sealing to obtain a lithium ion secondary battery. The preparation method of the lithium ion secondary battery is simple and feasible.

 Embodiment 1

 A method for preparing a non-aqueous organic electrolyte, comprising the steps of:

Add 500 g of ethylene carbonate (EC) and 500 g of cesium carbonate (EMC) to the stirrer to form a non-aqueous organic solvent, and dissolve 125 g of lithium salt LiPF ₆ in a non-aqueous organic solvent, stir, and stir. 28 ° C ;

 Add 5.65 g of tetrakis(trifluorodecyl) pyrophosphate, a non-aqueous organic electrolyte additive as shown in Formula Ia, obtained from Beijing Jiashengyang Pharmaceutical Technology Co., Ltd., and stir to obtain a non-aqueous organic The electrolyte A, based on the mass fraction, the non-aqueous organic electrolyte additive I a accounts for 0.5% of the non-aqueous organic electrolyte.

 Hereinafter, a method for preparing a lithium ion secondary battery according to an embodiment of the present invention will be described by taking a production of a square-wound lithium ion secondary soft pack battery (model number 423450-800 mAh) as an example.

 Preparation of positive electrode sheet

 The positive active material LiNi sMn C conductive agent acetylene black and the binder PVDF powder material were mixed at a mass ratio of 80:10:10, and then N-decylpyrrolidone (NMP) solution was added and stirred in a vacuum mixer for 2 hours to prepare a solution. The oil-based slurry is finally coated on both sides of the aluminum current collector, dried at 110 ° C, and rolled to form a positive electrode sheet of a lithium ion secondary battery.

 Preparation of negative electrode sheets

Anode active material artificial graphite powder, binder carboxymethyl cellulose (CMC), binder styrene The styrene-butadiene rubber (SBR) emulsion is mixed at a mass ratio of 100:3:2, and then deionized water is added to prepare an aqueous negative electrode slurry, and finally the slurry is coated on both sides of the copper current collector to prepare lithium ions twice. The battery negative electrode, the negative electrode capacity is designed to be 1.2 times the capacity of the positive electrode.

 As the non-aqueous organic electrolyte, the non-aqueous organic electrolyte A obtained in the present example was used.

 Production of lithium ion secondary battery

 A composite separator composed of polypropylene and polyethylene is placed between the positive electrode tab and the negative electrode tab prepared above, such as a sandwich structure, and then rolled together into a 423450 square battery pole core, and finally a square-wound soft pack battery is completed. Finally, the nonaqueous organic electrolyte A was injected to obtain a lithium ion secondary battery A.

 For the lithium ion secondary battery, whether it is a square or a cylindrical or soft pack battery, whether it is a wound type or a laminated type, the same effect can be obtained by the above-described lithium ion secondary battery preparation method.

 Embodiment 2

 A method for preparing a non-aqueous organic electrolyte, comprising the steps of:

500 g of ethylene carbonate (EC), 1000 g of dinonyl carbonate (DMC) and 500 g of diethyl carbonate (DEC) were added to the stirrer to form a non-aqueous organic solvent, and 250 g of lithium salt LiC10 _{4 was} dissolved. In a non-aqueous organic solvent, stirring, stirring temperature is 20 ° C;

 Adding 22.73 g of tetrabenzyl pyrophosphate, a non-aqueous organic electrolyte additive as shown in Formula Ib, obtained from Beijing Jiashengyang Pharmaceutical Technology Co., Ltd., and stirring, to obtain a non-aqueous organic electrolyte B, The mass fraction, the non-aqueous organic electrolyte additive lb accounts for 1% of the non-aqueous organic electrolyte.

The following is a square-wound lithium ion secondary soft pack battery (model number is 423450-800mAh). As an example, a method of preparing a lithium ion secondary battery according to an embodiment of the present invention will be described.

 Preparation of positive electrode sheet

 The positive active material LiNi sMn C conductive agent carbon black powder and the binder PVDF powder material were mixed at a mass ratio of 85:10:5, and then N-decylpyrrolidone (NMP) solution was added and stirred in a vacuum mixer for 2 hours. The oil-based slurry is finally coated on both sides of the aluminum current collector, dried at 110 ° C, and rolled to form a positive electrode sheet of a lithium ion secondary battery.

 The non-aqueous organic electrolyte B was prepared by using the non-aqueous organic electrolyte B obtained in the present example, and the lithium ion secondary battery B was obtained by the same method as the lithium ion secondary battery of the first embodiment.

 Embodiment 3

 A method for preparing a non-aqueous organic electrolyte, comprising the steps of:

Add 500 g of ethylene carbonate (EC) and 500 g of diethyl carbonate (DEC) to a stirrer to form a non-aqueous organic solvent, and 200 g of lithium salt tetraphenylborate LiB (C _{6 3⁄4} ) ₄ In aqueous organic solvent, stir and stir at 25 °C;

 Adding 104.35 g of tetraethyl pyrophosphate, a non-aqueous organic electrolyte additive as shown in Formula Ic, obtained from Beijing Swanda Kangkee Co., Ltd., and stirring, to obtain a non-aqueous organic electrolyte C, The non-aqueous organic electrolyte additive I c accounts for 8% of the non-aqueous organic electrolyte by mass fraction.

 0 0

H ₃ CH ₂ C - 0 - P - 0 - P - 0 - CH ₂ CH ₃

CH2CH3 CH2CH3 I Q

 Hereinafter, a method for preparing a lithium ion secondary battery according to an embodiment of the present invention will be described by taking a production of a square-wound lithium ion secondary soft pack battery (model number 423450-800 mAh) as an example.

 Preparation of positive electrode sheet

Positive electrode active material 0.5 (Li ₂ MnO ₃ ) 0.5 (LiNi ₁ / ₃ Co ₁ / ₃ Mn _1/3 O ₂ ), conductive agent carbon black powder and sticky The cement PVDF powder material was mixed at a mass ratio of 85:10:5, then a solution of N-decylpyrrolidone (NMP) was added, and stirred in a vacuum mixer for 2 hours to prepare an oil-based slurry, and finally the slurry was coated on aluminum. The two sides of the current collector are dried at 110 ° C and rolled to form a positive electrode of a lithium ion secondary battery.

 As the non-aqueous organic electrolyte, the non-aqueous organic electrolyte C obtained in the present example was used, and another lithium ion secondary battery C was produced in the same manner as in the production method of the lithium ion secondary battery of the first embodiment.

 Embodiment 4

 A method for preparing a non-aqueous organic electrolyte, comprising the steps of:

Adding 500 g of ethylene carbonate (EC) and 500 g of dinonyl carbonate (DMC) to the stirrer to form a non-aqueous organic solvent, and 100 g of lithium salt trifluorosulfonylsulfonate (LiCF ₃ S0 ₃ ) In a non-aqueous organic solvent, stir and stir at a temperature of 25 °C;

 Adding 194 g of tetrabenzyl pyrophosphate, a non-aqueous organic electrolyte additive as shown in Formula Ib, obtained from Beijing Jiashengyang Pharmaceutical Technology Co., Ltd., and stirring, to obtain a non-aqueous organic electrolyte D, According to the mass fraction, the non-aqueous organic electro-hydraulic additive lb accounts for 15% of the non-aqueous organic electrolyte.

 Hereinafter, a method for preparing a lithium ion secondary battery according to an embodiment of the present invention will be described by taking a production of a square-wound lithium ion secondary soft pack battery (model number 423450-800 mAh) as an example.

 Preparation of positive electrode sheet

The positive electrode active material 0.7 (Li ₂ MnO ₃ ) 0.3 (LiNi ₁ / ₃ Co ₁ / ₃ Mn _1/3 O ₂ ), the conductive agent carbon black powder, and the binder PVDF powder material were subjected to a mass ratio of 85:10:5. Mixing, then adding N-decylpyrrolidone (NMP) solution, stirring in a vacuum mixer for 2 h, preparing an oil-based slurry, and finally coating the slurry in The aluminum current collector is coated on both sides, dried at 110 ° C, and rolled to form a positive electrode of a lithium ion secondary battery.

 As the non-aqueous organic electrolyte, the non-aqueous organic electrolyte D obtained in the present embodiment was used, and other lithium ion secondary batteries of the same manner as in the first embodiment were used to produce a lithium ion secondary battery D.

 Embodiment 5

 A method for preparing a non-aqueous organic electrolyte, comprising the steps of:

Add 500 g of ethylene carbonate (EC), 1000 g of dinonyl carbonate (DMC) and 500 g of cesium carbonate (EMC) to the stirrer to form a non-aqueous organic solvent, and 250 g of lithium salt LiPF ₆ In aqueous organic solvent, stir and stir at 25 °C;

 Adding a purity of 99.5% from Beijing Jiashengyang Pharmaceutical Technology Co., Ltd. as a non-aqueous organic electrolyte additive as shown in Formula Ib, 22.73 g of tetrabenzyl pyrophosphate and 2.27 g of vinylene carbonate (VC), stirring, A non-aqueous organic electrolyte E is obtained. According to the mass fraction, the non-aqueous organic electrolyte additive lb accounts for 1% of the non-aqueous organic electrolyte, and the functional additive vinylene carbonate (VC) accounts for 0.1% of the non-aqueous organic electrolyte. .

 Hereinafter, a method for preparing a lithium ion secondary battery according to an embodiment of the present invention will be described by taking a production of a square-wound lithium ion secondary soft pack battery (model number 423450-800 mAh) as an example.

 Preparation of positive electrode sheet

The positive active material LiNi sMn C conductive agent carbon black powder and the binder PVDF powder material were mixed at a mass ratio of 85:10:5, and then N-decylpyrrolidone (NMP) solution was added and stirred in a vacuum mixer for 2 hours. The oil-based slurry is finally coated on both sides of the aluminum current collector, dried at 110 ° C, and rolled to form a positive electrode sheet of a lithium ion secondary battery. The non-aqueous organic electrolyte solution was the non-aqueous organic electrolyte E obtained in the present example, and the lithium ion secondary battery E was produced in the same manner as in the production method of the lithium ion secondary battery of the first embodiment. Embodiment 6

 A method for preparing a non-aqueous organic electrolyte, comprising the steps of:

Adding 500 g of ethylene carbonate (EC) and 500 g of diethyl carbonate (DEC) to the stirrer to form a non-aqueous organic solvent, and 125 g of lithium salt LiPF ₆ in a non-aqueous organic solvent, stirring, stirring temperature is 25 ° C ; organic electrolyte additive 11.36 g of tetraethyl pyrite, stirred, to obtain a non-aqueous organic electrolyte F, according to the mass fraction, non-aqueous organic electrolyte additive Il a accounted for 1% of non-aqueous organic electrolyte .

H ₃ CH ₂ C― O― P― O― P― O― CH ₂ CH ₃

 0 I o I

 1 I

CH ₂ CH ₃ CH ₂ CH ₃ II ^

 Hereinafter, a method for preparing a lithium ion secondary battery according to an embodiment of the present invention will be described by taking a production of a square-wound lithium ion secondary soft pack battery (model number 423450-800 mAh) as an example.

 Preparation of positive electrode sheet

 The positive active material LiNi sMn C conductive agent carbon black powder and the binder PVDF powder material were mixed at a mass ratio of 85:10:5, and then N-decylpyrrolidone (NMP) solution was added and stirred in a vacuum mixer for 2 hours. The oil-based slurry is finally coated on both sides of the aluminum current collector, dried at 110 ° C, and rolled to form a positive electrode sheet of a lithium ion secondary battery.

The non-aqueous organic electrolyte solution was the non-aqueous organic electrolyte solution F obtained in the present example, and the lithium ion secondary battery F was produced in the same manner as in the production method of the lithium ion secondary battery of the first embodiment. Example 7 A method for preparing a non-aqueous organic electrolyte, comprising the steps of:

500 g of ethylene carbonate (EC), 1000 g of dinonyl carbonate (DMC) and 500 g of diethyl carbonate (DEC) were added to the stirrer to form a non-aqueous organic solvent, and 250 g of lithium salt LiB (C _{6 ) was added. 3⁄4} ) ₄ in a non-aqueous organic solvent, stirring, stirring temperature is 25 ° C;

 Adding 195.65 g of tetrabenzyl pyrophosphite, which is a non-aqueous organic electrolyte additive as shown by formula li b, obtained from Beijing Swanda Kangke Trading Co., Ltd., and stirring to obtain a non-aqueous organic electrolyte G According to the mass fraction, the non-aqueous organic electrolyte additive lib accounts for 8% of the non-aqueous organic electrolyte.

 Hereinafter, a method for preparing a lithium ion secondary battery according to an embodiment of the present invention will be described by taking a production of a square-wound lithium ion secondary soft pack battery (model number 423450-800 mAh) as an example.

 Preparation of positive electrode sheet

The positive electrode active material 0.4 (Li ₂ MnO ₃ ) 0.6 (LiNi ₁ / ₃ Co ₁ / ₃ Mn _1/3 O ₂ ), the conductive agent carbon black powder, and the binder PVDF powder material were subjected to a mass ratio of 85:10:5. Mixing, then adding N-decylpyrrolidone (NMP) solution, stirring in a vacuum mixer for 2 h to prepare an oil-based slurry, and finally coating the slurry on both sides of the aluminum current collector, drying at 110 ° C, rolling, A positive electrode of a lithium ion secondary battery was fabricated.

 As the non-aqueous organic electrolyte, the non-aqueous organic electrolyte G obtained in the present example was used, and other lithium ion secondary batteries of the same manner as in the first embodiment were used to produce a lithium ion secondary battery G.

 Example eight

 A method for preparing a non-aqueous organic electrolyte, comprising the steps of:

Add 500 g of ethylene carbonate (EC) and 500 g of dinonyl carbonate (DMC) to the blender. Combined into a non-aqueous organic solvent, 125 g of lithium salt LiCF ₃ S0 ₃ in a non-aqueous organic solvent, stirred, stirring temperature is 25 ° C; organic electrolyte additive tetrabenzyl phosphite 27.09 g and 202.58 g of phosphoric acid Ethyl ester (TEP), stirred to produce a non-aqueous organic electrolyte H. According to the mass fraction, the non-aqueous organic electrolyte additive li b accounts for 2% of the non-aqueous organic electrolyte, and the functional additive triethyl phosphate (TEP) It accounts for 15% of the non-aqueous organic electrolyte.

 Hereinafter, a method for preparing a lithium ion secondary battery according to an embodiment of the present invention will be described by taking a production of a square-wound lithium ion secondary soft pack battery (model number 423450-800 mAh) as an example.

 Preparation of positive electrode sheet

 The positive active material LiNi sMn C conductive agent carbon black powder and the binder PVDF powder material were mixed at a mass ratio of 85:10:5, and then N-decylpyrrolidone (NMP) solution was added and stirred in a vacuum mixer for 2 hours. The oil-based slurry is finally coated on both sides of the aluminum current collector, dried at 110 ° C, and rolled to form a positive electrode sheet of a lithium ion secondary battery.

 As the non-aqueous organic electrolyte, the non-aqueous organic electrolyte H obtained in the present example was used, and other lithium ion secondary batteries of the same manner as in the first embodiment were used to produce a lithium ion secondary battery H. Comparative example one

Adding 500 g of ethylene carbonate (EC) and 500 g of cesium carbonate (EMC) to the stirrer to form a non-aqueous organic solvent, and dissolving 125 g of lithium salt LiPF ₆ in a non-aqueous organic solvent, stirring, and obtaining Non Water organic electrolyte I.

 Next, a method of preparing a comparative lithium ion secondary battery of the present invention will be described by taking a production of a square-wound lithium ion secondary soft pack battery (model number 423450-800 mAh) as an example.

 Preparation of positive electrode sheet

 The positive active material LiNi sMn C conductive agent carbon black powder and the binder PVDF powder material were mixed at a mass ratio of 85:10:5, and then N-decylpyrrolidone (NMP) solution was added and stirred in a vacuum mixer for 2 hours. The oil-based slurry is finally coated on both sides of the aluminum current collector, dried at 110 ° C, and rolled to form a positive electrode sheet of a lithium ion secondary battery.

 The non-aqueous organic electrolyte I used the non-aqueous organic electrolyte I obtained in the comparative example, and other lithium ion secondary batteries of the same manner as in the first embodiment were used to produce a lithium ion secondary battery I.

Comparative example two

Add 500 g of ethylene carbonate (EC) and 500 g of diethyl carbonate (DEC) to a stirrer to prepare a non-aqueous organic solvent, and dissolve 125 g of lithium salt LiPF ₆ in a non-aqueous organic solvent, and add 198.53 g of function. The auxiliary triethyl phosphate (TEP) is stirred to obtain a non-aqueous organic electrolyte J. According to the mass fraction, the functional additive triethyl phosphate (TEP) accounts for 15% of the non-aqueous organic electrolyte.

 Next, a method of preparing a comparative lithium ion secondary battery of the present invention will be described by taking a production of a square-wound lithium ion secondary soft pack battery (model number 423450-800 mAh) as an example.

 Preparation of positive electrode sheet

The positive electrode active material 0.5 (Li ₂ MnO ₃ ) 0.5 (LiNi ₁ / ₃ Co ₁ / ₃ Mn _1/3 O ₂ ), the conductive agent carbon black powder, and the binder PVDF powder material were subjected to a mass ratio of 85:10:5. Mixing, then adding N-decylpyrrolidone (NMP) solution, stirring in a vacuum mixer for 2 h to prepare an oil-based slurry, and finally coating the slurry on both sides of the aluminum current collector, drying at 110 ° C, rolling, A positive electrode of a lithium ion secondary battery was fabricated.

The non-aqueous organic electrolyte solution is the non-aqueous organic electrolyte J prepared in the comparative example, and the others are implemented in the same manner. In the method for producing a lithium ion secondary battery of Example 1, a lithium ion secondary battery J was obtained. Effect embodiment

 1. Test of decomposition potential of non-aqueous organic electrolyte

For the first to eighth embodiments, the first and second examples were subjected to cyclic voltammetry using a three-electrode system. The working electrode was glassy carbon, the counter electrode and the reference electrode were lithium electrodes, and the scanning range was 0 to 5.5 V, and the scanning speed was 10 mV/ S _o

 The test results are shown in Table 1.

 Table 1. Decomposition potential test of Examples 1 to 8 and Comparative Example 1 to 2 non-aqueous organic electrolyte

 It can be seen from the results of Table 1 that the non-aqueous organic electrolytes provided in Examples 1 to 8 of the present invention have an oxidative decomposition potential of 5.0 V or more, and No pyrophosphate or pyrophosphite in Comparative Examples 1 and 2. The oxidative decomposition potential of the non-aqueous organic electrolyte of the additive-like additive is only 4.4 V, which is much lower than the decomposition potential of the non-aqueous organic electrolyte provided in Examples 1 to 8 of the present invention.

 2. Lithium ion secondary battery cycle performance test

The lithium ion secondary batteries prepared according to the above Examples 1 to 8 and Comparative Examples 1 and 2 were subjected to cycle performance tests. The test method is as follows: The lithium ion secondary battery is loaded into the secondary battery performance test in the correct way to BS-9300, first charged to 4.9V with constant current constant voltage of 1C (for spinel LiM _x Mn _x ) 0 ₄ , Wherein M is selected from one or more of transition metals Ni, Co and Fe, 0 x 2 ) or 4.6 V (for lithium-rich solid solution cathode material xLi ₂ Mn0 ₃ (lx)LiM0 ₂ , wherein M is selected from transition metal Ni , one or more of Co and Mn, 0 χ 1 ), set aside for 5 minutes, discharge to 3.0V with 1C, and then charge to 4.9V with constant current at 1C (for spinel LiM _x Mn _x )0 ₄ , wherein M is selected from one or more of transition metals Ni, Co and Fe, 0 x 2 ) or 4.6V (for lithium-rich solid solution cathode material xLi ₂ Mn0 ₃ ( 1 -x)LiM0 ₂ , wherein One or more of the transition metals Ni, Co and Mn, 0 < x < 1 ), are thus cycled 100 times. After the end of the cycle, wait until the battery temperature returns to normal temperature, fully charge with 1C, and then discharge to 3.0V with 0.2C to obtain the remaining capacity. Divide the remaining capacity by the first cycle capacity to obtain the capacity retention rate. The results are shown in Table 2. .

 Table 2. Example 1 to 8 and Comparative Example 1 to 2 Lithium Ion Secondary Battery Cycle Performance Test

 As can be seen from Table 2, the lithium ion secondary battery provided by Examples 1 to 8 of the present invention has a capacity retention rate of up to 95% and a minimum of 89% after 100 cycles, and is prepared in Comparative Examples 1 and 2. The capacity retention of the lithium ion secondary battery after only 100 cycles is only 56% and 43%, and it can be seen that the nonaqueous organic electrolyte provided in the first to eighth embodiments of the present invention has good high pressure resistance. At the same time, the cycle performance of the lithium ion secondary battery provided by the first to eighth embodiments of the present invention is improved.

Claims

Claim o OR=——I

1. A non-aqueous organic electrolyte, characterized by including:

o

Lithium salt; † R. o=II non-aqueous organic solvent; and non-aqueous organic electrolyte additive, the non-aqueous organic electrolyte additive is a non-aqueous organic electrolyte additive shown in formula (I) and/or a non-aqueous organic electrolyte additive shown in formula (II) Non-aqueous organic electrolyte additives,

R — 0 — R ₄

3 formula (I),

R ₅ — 0 — P — 0 — P — 0 — R ₈

I I

0 0

1 I

R ₆ R ₇ formula (II),

Among them, R ₂ , R ₃ , R ₅ , R ₆ , R ₇ and R ₈ are C^Q linear or branched chain alkyl groups, C^do alkenyl groups, Cr^do alkyne groups or C ₆ ~ C ₁₄ aryl group, or Ri, R ₂ , R ₃ , R ₄ , R ₅ , R ₆ ,

R ₇ and R ₈ are halogen-containing: linear or branched alkyl groups of Crdo, alkenyl groups of Cu), alkynyl groups of CHo, or aromatic groups of C ₆ to _{C 14} .

2. A non-aqueous organic electrolyte as claimed in claim 1, characterized in that, in the non-aqueous organic electrolyte additive represented by formula (I), R ₂ , R ₃ and R ₄ are methyl groups. , ethyl, trifluoromethyl, trifluoroethyl, perfluoroethyl, phenyl, benzyl, partially or perfluoro-substituted phenyl.

3. A non-aqueous organic electrolyte as claimed in claim 1, wherein R ₅ , R ₆ , R ₇ and R ₈ in the non-aqueous organic electrolyte additive represented by formula (II) are Methyl, ethyl, trifluoromethyl, trifluoroethyl, perfluoroethyl, phenyl, benzyl, partially or perfluorinated phenyl.

4. A non-aqueous organic electrolyte as claimed in claim 1, characterized in that, in terms of mass fraction, The non-aqueous organic solvent accounts for 85% to 99.5% of the non-aqueous organic electrolyte, and the non-aqueous organic electrolyte additive accounts for 0.5% to 15% of the non-aqueous organic electrolyte.

o

5. If the right is required o OR= II 1

_Seeking the non-aqueous organic electrolyte, characterized in that, the non-aqueous organic electrolyte is

The electrolyte also includes functional additives, which are selected from recycling additives, high-temperature additives, and flame retardant additives.

R. o= I I

One or more of additives and overcharge additives.

6. A method for preparing a non-aqueous organic electrolyte, characterized in that it includes the following steps: Dissolve lithium salt in a non-aqueous organic solvent, and add a non-aqueous organic electrolyte additive as shown in formula (I) and/or Stir the non-aqueous organic electrolyte additive shown in formula (II) to prepare the non-aqueous organic electrolyte,

R — 0 — R ₄

3 formula (I),

R ₅ — 0 — P — 0 — P — 0 — R ₈

I I

0 0

1 I

R ₆ R ₇ formula (II),

Among them, R ₂ , R ₃ , R ₅ , R ₆ , R ₇ and R ₈ are C^Q linear or branched chain alkyl groups, C^do alkenyl groups, Cr^do alkyne groups or C ₆ ~ C ₁₄ aryl group, or Ri, R ₂ , R ₃ , R ₄ , R ₅ , R ₆ ,

R ₇ and R ₈ are halogen-containing: linear or branched chain alkyl groups of Crdo, alkenyl groups of Cu), alkynyl groups of CHo, or aromatic groups of C ₆ to _{C 14} .

7. The preparation method of a non-aqueous organic electrolyte as claimed in claim 6, wherein R ₂ , R ₃ and R ₄ in the non-aqueous organic electrolyte additive represented by formula (I) are Methyl, ethyl, trifluoromethyl, trifluoroethyl, perfluoroethyl, phenyl, benzyl, partially or perfluorinated phenyl.

8. The method for preparing a non-aqueous organic electrolyte as claimed in claim 6, wherein R ₅ , R ₆ , R ₇ and R ₈ is methyl, ethyl, trifluoromethyl, trifluoroethyl, perfluoroethyl, phenyl, benzyl, partially or perfluoro-substituted phenyl.

9. The method for preparing a non-aqueous organic electrolyte as claimed in claim 6, wherein the non-aqueous organic solvent accounts for 85% to 99.5% of the non-aqueous organic electrolyte in terms of mass fraction. Non-water has o

Mechanical electrolyte additive o OR= II accounts for 0.5%~15%.

_Non-aqueous organic electrolytes

o

10. A lithium ion secondary battery, characterized by including: a positive electrode, a negative electrode, a separator, and a casing

R. o= I I

And a non-aqueous organic electrolyte, the non-aqueous organic electrolyte includes: lithium salt, non-aqueous organic solvent, and a non-aqueous organic electrolyte additive as shown in formula (I) and/or as shown in formula (II) non-aqueous organic power oral agent,

R — 0 — R ₄

3 formula (I),

R ₅ — 0 — P — 0 — P — 0 — R ₈

I I

0 0

1 I

R ₆ R ₇ formula (II),

Among them, R ₂ , R ₃ , R ₅ , R ₆ , R ₇ and R ₈ are C^Q linear or branched chain alkyl groups, C^do alkenyl groups, Cr^do alkyne groups or C ₆ ~ C ₁₄ aryl group, or Ri, R ₂ , R ₃ , R ₄ , R ₅ , R ₆ ,

R ₇ and R ₈ are halogen-containing: linear or branched alkyl groups of Crdo, alkenyl groups of Cu), alkynyl groups of CHo, or aromatic groups of C ₆ to _{C 14} .