NON-AQUEOUS ELECTROLYTE FOR A LITHIUM ION BATTERY AND LITHIUM ION BATTERY COMPRISING THE ELECTROLYTE

Abstract

The application provides a non-aqueous electrolyte for a lithium ion battery, including a non-aqueous organic solvent and lithium salt, and the non-aqueous electrolyte further includes one or more selected from the compounds represented by Formula 1 and Formula 2. R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each independently selected from a substituted or unsubstituted alkyl group and ether group and unsaturated hydrocarbon group, and at least one of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 is the substituted or unsubstituted unsaturated hydrocarbon group, and R.sub.5 is selected from a substituted or unsubstituted alkylene group and ether group; R.sub.6, R.sub.7 and R.sub.8 are each independently selected from a substituted or unsubstituted alkyl group and ether group and unsaturated hydrocarbon group, provided that at least one of R.sub.6, R.sub.7 and R.sub.8 is the substituted or unsubstituted unsaturated hydrocarbon group. The application also provides a lithium ion battery including the non-aqueous electrolyte.

##STR00001##

Claims

1. A non-aqueous electrolyte for a lithium ion battery, comprising a non-aqueous organic solvent and a lithium salt, characterized in that the non-aqueous electrolyte further comprises one or more selected from the group consisting of compounds represented by Formula 1 and compounds represented by Formula 2: ##STR00033## in Formula 1, R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each independently selected from a substituted or unsubstituted alkyl group of 1-5 carbon atoms, a substituted or unsubstituted ether group of 1-5 carbon atoms and a substituted or unsubstituted unsaturated hydrocarbon group of 2-5 carbon atoms, provided that at least one of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 is the substituted or unsubstituted unsaturated hydrocarbon group of 2-5 carbon atoms, and R.sub.5 is selected from a substituted or unsubstituted alkylene group of 1-5 carbon atoms and a substituted or unsubstituted ether group of 1-5 carbon atoms; in Formula 2, R.sub.6, R.sub.7 and R.sub.8 are each independently selected from a substituted or unsubstituted alkyl group of 1-5 carbon atoms, a substituted or unsubstituted ether group of 1-5 carbon atoms and a substituted or unsubstituted unsaturated hydrocarbon group of 2-5 carbon atoms, provided that at least one of R.sub.6, R.sub.7 and R.sub.8 is the substituted or unsubstituted unsaturated hydrocarbon group of 2-5 carbon atoms.

2. The non-aqueous electrolyte of claim 1, wherein the alkyl group of 1-5 carbon atoms is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl and neopentyl; the unsaturated hydrocarbon group of 2-5 carbon atoms is selected from vinyl, propenyl, allyl, butenyl, pentenyl, methyl vinyl, methyl allyl, ethynyl, propinyl, propargyl, butynyl and pentynyl; the alkylene group of 1-5 carbon atoms is selected from methylene, ethylidene, n-propylene, isopropylidene, n-butylene, isobutylidene, sec-butylidene, tertiary butyl, pentylene, isoamylidene, sec-pentylene and neopentylidene; the ether group of 1-5 carbon atoms is selected from a methyl ether, diethyl ether, methyl ethyl ether, propyl ether, methyl propyl ether and ethyl propyl ether; the “substituted” is that one or more hydrogen elements are substituted by halogen; preferably, the halogen is fluorine.

3. The non-aqueous electrolyte of claim 2, wherein the compounds represented by Formula 1 are following compounds 1-22: TABLE-US-00006 Compound 1 Compound 2 Compound 3 Compound 4 Compound 5 Compound 6 Compound 7 Compound 8 Compound 9 Compound 10 Compound 11 Compound 12 Compound 13 Compound 14 Compound 15 Compound 16 Compound 17 Compound 18 Compound 19 Compound 20 Compound 21 Compound 22

4. The non-aqueous electrolyte of claim 1, wherein the content of the compound represented by Formula 1 is 10 ppm or more relative to the total mass of the non-aqueous electrolyte.

5. The non-aqueous electrolyte of claim 4, wherein the content of the compound represented by Formula 1 is 2% or less relative to the total mass of the non-aqueous electrolyte.

6. The non-aqueous electrolyte of claim 1, wherein the content of the compound represented by Formula 2 is 0.1-2% relative to the total mass of the non-aqueous electrolyte.

7. The non-aqueous electrolyte of claim 1, further comprising at least one of unsaturated cyclic carbonate, fluorinated cyclic carbonate, cyclic sulfonate lactone and cyclic sulfate.

8. The non-aqueous electrolyte of claim 1, wherein the non-aqueous organic solvent is a mixture of cyclic carbonate and chain carbonate.

9. A lithium ion battery, comprising a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode, characterized in that the lithium ion battery further comprises the non-aqueous electrolyte of claim 1.

10. The lithium ion battery of claim 9, wherein the positive electrode comprises a positive electrode active material selected from at least one of LiNi.sub.xCo.sub.yMn.sub.zL.sub.(1-x-y-z)O.sub.2, LiCo.sub.x′L.sub.(1-x′) O.sub.2, LiNi.sub.x″L′.sub.y′Mn.sub.(2-x″-y′)O.sub.4 and Li.sub.z′MPO.sub.4, wherein L is at least one of Al, Sr, Mg, Ti, Ca, Zr, Zn, Si or Fe, 0≤x≤1, 0≤y≤1, 0≤z≤1, 0<x+y+z≤1, 0<x′≤1, 0.3≤x″≤0.6, 0.01≤y′≤0.2, L′ is at least one of Co, Al, Sr, Mg, Ti, Ca, Zr, Zn, Si and Fe; 0.5≤z′≤1, M is at least one of Fe, Mn and Co.

11. The non-aqueous electrolyte of claim 2, wherein the compound represented by Formula 2 is at least one of the following compounds 23-28. TABLE-US-00007 Compound 23 Compound 24 Compound 25 Compound 26 Compound 27 Compound 28

12. The non-aqueous electrolyte of claim 7, wherein based on the total mass of the non-aqueous electrolyte, content of the unsaturated cyclic carbonate is 0.1-5%, content of the fluorinated cyclic carbonate is 0.1-30%, content of the cyclic sulfonate lactone is 0.1-5%, and content of the cyclic sulfate is 0.1-5%.

13. The non-aqueous electrolyte of claim 7, wherein the unsaturated cyclic carbonate is selected from at least one of vinylene carbonate (CAS: 82-36-6), vinylethylene carbonate (CAS: 4427-96-7) and methylene ethylene carbonate (CAS: 124222-05-5), the fluorinated cyclic carbonate is selected from at least one of fluoroethylene carbonate (CAS: 114435-02-8), trifluoromethyl ethylene carbonate (CAS: 167951-80-6) and difluoroethylene carbonate (CAS: 311810-76-1), the cyclic sulfonate lactone is selected from at least one of 1,3-propane suhone (CAS: 1120-71-4), 1,4-butane sultone (CAS: 1633-83-6) and propene 1,3-sultone (CAS: 21806-61-1), and the cyclic sulfate is selected from at least one of ethylene sulfate (CAS: 1072-53-3) and 4-methyl ethylene sulfate (CAS: 5689-83-8).

14. The non-aqueous electrolyte of claim 8, wherein the cyclic carbonate is selected from at least one of ethylene carbonate, propylene carbonate and butylene carbonate, and the chain carbonate is selected from at least one of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and methyl propyl carbonate.

15. The non-aqueous electrolyte of claim 8, wherein the lithium salt is selected from at least one of LiPF.sub.6, LiBF.sub.4, LiPO.sub.2F.sub.2, LiTFSI, LiBOB, LiDFOB and LiN(SO.sub.2F).sub.2.

16. The non-aqueous electrolyte of claim 9, wherein the content of the compound represented by Formula 1 is 10 ppm or more relative to the total mass of the non-aqueous electrolyte.

17. The non-aqueous electrolyte of claim 16, wherein the content of the compound represented by Formula 1 is 2% or less relative to the total mass of the non-aqueous electrolyte.

18. The non-aqueous electrolyte of claim 9, wherein the content of the compound represented by Formula 2 is 0.1-2% relative to the total mass of the non-aqueous electrolyte.

19. The non-aqueous electrolyte of claim 9, wherein the non-aqueous organic solvent is a mixture of cyclic carbonate and chain carbonate; preferably, the cyclic carbonate is selected from at least one of ethylene carbonate, propylene carbonate and butylene carbonate, and the chain carbonate is selected from at least one of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and methyl propyl carbonate.

20. The non-aqueous electrolyte of claim 19, wherein the lithium salt is selected from at least one of LiPF.sub.6, LiBF.sub.4, LiPO.sub.2F.sub.2, LiTFSI, LiBOB, LiDFOB and LiN(SO.sub.2F).sub.2.

Description

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

[0033] The application is described in further detail below with specific embodiments and drawings. In which like element in different embodiments have been label with like reference signs. In the following embodiments, many details are set forth in order to provide a better understanding of the present application. However, those skilled in the art would readily recognize that some of the features may be omitted in various instances or may be replaced by other elements, materials, methods. In some instances, operations related to this application are not shown or described in the specification in order to avoid obscuring the core part of this application with too much description, and a detailed description of these operations is not necessary for those skilled in the art. They can fully understand the related operations according to the description in the specification and common technical knowledge in the art.

[0034] In addition, features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the steps or operations in the method description may be sequentially reversed or adjusted in ways that would be apparent to those skilled in the art. Accordingly, the various orders in the specification and drawings are for clarity of description of a particular embodiment only and do not intend to be a necessary order unless otherwise specified in which a particular order is to be followed.

[0035] The application provides a non-aqueous electrolyte for a lithium ion battery, including a non-aqueous organic solvent and a lithium salt, the non-aqueous electrolyte further includes one or more selected from the group consisting of compounds represented by Formula 1 and compounds represented by Formula 2;

##STR00031##

[0036] in Formula 1, R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each independently selected from a substituted or unsubstituted alkyl group of 1-5 carbon atoms, a substituted or unsubstituted ether group of 1-5 carbon atoms and a substituted or unsubstituted unsaturated hydrocarbon group of 2-5 carbon atoms, provided that at least one of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 is the substituted or unsubstituted unsaturated hydrocarbon group of 2-5 carbon atoms, and R.sub.5 is selected from a substituted or unsubstituted alkylene group of 1-5 carbon atoms and a substituted or unsubstituted ether group of 1-5 carbon atoms;

[0037] in Formula 2, R.sub.6, R.sub.7 and R.sub.8 are each independently selected from a substituted or unsubstituted alkyl group of 1-5 carbon atoms, a substituted or unsubstituted ether group of 1-5 carbon atoms and a substituted or unsubstituted unsaturated hydrocarbon group of 2-5 carbon atoms, provided that at least one of R.sub.6, R.sub.7 and R.sub.8 is the substituted or unsubstituted unsaturated hydrocarbon group of 2-5 carbon atoms.

[0038] The alkyl group of 1-5 carbon atoms may be selected from, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl and neopentyl.

[0039] The unsaturated hydrocarbon group of 2-5 carbon atoms may be selected from vinyl, propenyl, allyl, butenyl, pentenyl, methyl vinyl, methyl allyl, ethynyl, propinyl, propargyl, butynyl and pentynyl.

[0040] The alkylene group of 1-5 carbon atoms is selected from methylene, ethylidene, n-propylene, isopropylidene, n-butylene, isobutylidene, sec-butylidene, tertiary butyl, pentylene, isoamylidene, sec-pentylene and neopentylidene.

[0041] The ether group of 1-5 carbon atoms is selected from a methyl ether, diethyl ether, methyl ethyl ether, propyl ether, methyl propyl ether and ethyl propyl ether.

[0042] The “substituted” is that one or more hydrogen elements are substituted by halogen; preferably, the halogen is fluorine, chlorine, bromine and iodine; more preferably, the halogen is fluorine.

[0043] Specifically, the halogen-substituted alkyl group of 1-5 carbon atoms is a fluoroalkyl group of 1-5 carbon atoms obtained by replacing one or more hydrogen elements in the alkyl group of 1-5 carbon atoms with a fluorine element.

[0044] Specifically, the halogen-substituted unsaturated hydrocarbon group of 2-5 carbon atoms is a fluorinated unsaturated hydrocarbon group of 2-5 carbon atoms obtained by replacing one or more hydrogen elements in the unsaturated hydrocarbon group of 2-5 carbon atoms with a fluorine element.

[0045] Specifically, the halogen-substituted alkylene group of 1-5 carbon atoms is a fluoroalkylene group of 1-5 carbon atoms obtained by replacing one or more hydrogen elements in the alkylene group of 1-5 carbon atoms with a fluorine element.

[0046] Specifically, the halogen-substituted ether group of 1-5 carbon atoms is a fluoroether group of 1-5 carbon atoms obtained by replacing one or more hydrogen elements in the ether group of 1-5 carbon atoms with a fluorine element.

[0047] Specifically, the fluoroether group of 1-5 carbon atoms may be selected from, for example, fluoromethyl ether, fluoroethyl ether, fluoromethyl ethyl ether, fluoropropyl ether, fluoropropyl methyl ether and fluoropropyl ethyl ether.

[0048] Those skilled in the art, knowing the structural formula of the above compounds of Formula 1, may be aware of the preparation method of the above-mentioned compound according to the common knowledge in the field of chemical synthesis. For example, the compound of Formula 1 may be prepared by using triethylamine as acid-binding agent. In ether solvent, phosphorus oxychloride reacts with corresponding alcohols at low temperature (−10° C. to 0° C.) and normal pressure to generate corresponding phosphate, which is then purified by recrystallization or column chromatography. Take compounds 1, 6 and 15 as examples, and their synthetic routes are as follows:

##STR00032##

[0049] In addition, the present application provides a lithium ion battery, which includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and the non-aqueous electrolyte for a lithium ion battery mentioned above.

[0050] The present application will be further described in detail below with non-limiting embodiments and comparative examples.

I. Embodiments 1-17 and Comparative Examples 1-7

1) Preparation of Electrolyte

[0051] Ethylene carbonate (EC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC) were mixed according to the mass ratio of EC:DEC:EMC=1:1:1, and then lithium hexafluorophosphate (LiPF.sub.6) was added till the molar concentration was 1 mol/L to prepare the basic electrolyte. Then, as shown in Table 2, a specified amount of compound represented by Formula 1 listed in Table 1 and/or a specified amount of compound represented by Formula 2 and other compounds are added or not.

[0052] Specifically, based on the total mass of the basic electrolyte, 1% of Compound 23 was added in Embodiments 1-11 and Comparative Examples 1-6. On this basis, 20 ppm of Compound 1, 50 ppm of Compound 2, 100 ppm of Compound 4, 500 ppm of Compound 7, 1000 ppm of Compound 8 and 1% of Compound 12 were added in Embodiments 1-6, respectively. 500 ppm of Compound 1 and 1% vinylene carbonate (VC), 500 ppm of Compound 1 and 1% fluoroethylene carbonate (FEC), 500 ppm of Compound 1 and 1% of 1,3-propane sultone (PS), 500 ppm of Compound 1 and 1% of ethylene sulfate (DTD) and 500 ppm of Compound 1 and 1% LiN(SO.sub.2F).sub.2 were added in Embodiments 7-11, respectively. compounds represented by Formula 1 were not added in Comparative Example 1. compounds represented by Formula 1 were not added in Comparative Examples 2-6, but 1% VC, 1% FEC, 1% PS, 1% DTD and 1% LiN(SO.sub.2F).sub.2 were added, respectively.

[0053] In Embodiment 12, only 20 ppm of Compound 1 was added. In Embodiments 13-17, 500 ppm of Compound 7 was added, on this basis, 0.1%, 0.2%, 0.5%, 1.5% and 2.0% of Compound 23 were added respectively. In Comparative Example 7, 500 ppm of 2-alkynyl-1,4-bis (bis (2-propinyl)) phosphate (ABPP) was added.

2) Preparation of Positive Electrode

[0054] Positive electrode active material lithium nickel cobalt manganese oxide LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2, conductive carbon black Super-P and binder Poly(vinylidene fluoride) (PVDF) were mixed according to the mass ratio of 93:4:3, and then the mixture was dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry. The slurry was uniformly coated on both sides of the aluminum foil, dried, calendered and vacuum-dried, and an aluminum lead wire was welded by an ultrasonic welding machine to obtain a positive electrode plate with a thickness of 120-150 μm.

3) Preparation of Negative Electrode

[0055] Negative electrode active material artificial graphite, conductive carbon black Super-P, binder styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) were mixed according to the mass ratio of 94:1:2.5:2.5, and then the mixture was dispersed in deionized water to obtain a negative electrode slurry. The slurry was coated on both sides of the copper foil, dried, calendered and vacuum-dried, and the nickel lead wire was welded by an ultrasonic welding machine to obtain a negative electrode plate with a thickness of 120-150 μm.

4) Preparation of Battery Core

[0056] A three-layer separator with a thickness of 20 μm was placed between the positive electrode plate and negative electrode plate. And then the sandwich structure composed of the positive electrode plate, the negative electrode plate and the separator was wound. Then the winding body was flattened and placed in an aluminum foil packaging bag, vacuum-baked at 75° C. for 48 hours to obtain an unfilled battery core.

5) Injection and Formation of Battery Core

[0057] In a glove box with dew point controlled below −40° C., the electrolyte prepared above was injected into the battery core, and then vacuum packed to make a lithium ion battery, which was let stand for 24 hours.

[0058] Then follow the steps below to carry out the formation of the first charge: charging at 0.05 C constant current for 180 min, charging at 0.2 C constant current to 3.95V, vacuum sealing for the second time, then further charging to 4.4V at 0.2 C constant current, and then discharging to 3.0V at 0.2 C constant current after letting stand for 24 h.

II. Embodiments 18-24 and Comparative Examples 8-9

[0059] The basic electrolyte was prepared according to the method described in “I. Embodiments 1-17 and Comparative Examples 1-7” above, and then as shown in Table 3, a specified amount of compounds represented by Formula 1 and/or a specified amount of compounds represented by Formula 2 and other compounds were added or not. Specifically, according to the total mass of the electrolyte, 1% of Compound 26 was added in Embodiments 18-23 and Comparative Example 8. On this basis, 20 ppm of Compound 1, 50 ppm of Compound 2, 100 ppm of Compound 4, 500 ppm of Compound 7, 1000 ppm of Compound 8 and 1% of Compound 12 were added in Embodiments 18-23 respectively. compounds represented by Formula 1 were not added in Comparative example 8. In Embodiment 24, Only 20 ppm of Compound 1 was added. In Comparative example 9, only 500 ppm of 2-alkynyl-1,4-bis (bis (2-propinyl)) phosphate (ABPP) was added. In addition, the positive electrode active components of Embodiments 18-14 and Comparative Examples 8-9 were all LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 for preparing the positive electrode plate. According to the method described in “I. Embodiments 1-17 and Comparative Examples 1-7” above, the positive electrode plate and battery core were prepared, and the battery core was injected and formed.

II. Embodiments 25-31 and Comparative Examples 10-11

[0060] The basic electrolyte was prepared according to the method described in “I. Embodiments 1-17 and Comparative Examples 1-7” above, and then as shown in Table 4, a specified amount of compounds represented by Formula 1 listed in Table 1 and/or a specified amount of compounds represented by Formula 2 and other compounds were added or not. Specifically, according to the total mass of the electrolyte, 1% of Compound 27 was added in Embodiments 25-30 and Comparative Example 10. On this basis, 20 ppm of Compound 1, 50 ppm of Compound 2, 100 ppm of Compound 4, 500 ppm of Compound 7, 1000 ppm of Compound 10 and 1% of Compound 12 were added in Embodiments 25-30 respectively. compounds represented by Formula 1 were not added in Comparative example 8. In Embodiment 31, Only 20 ppm of Compound 1 was added. In Comparative example 11, only 500 ppm of 2-alkynyl-1,4-bis (bis (2-propinyl)) phosphate (ABPP) was added. In addition, the positive electrode active components of Embodiments 25-31 and Comparative Examples 10-11 were all LiCoO.sub.2 for preparing the positive electrode plate. According to the method described in “I. Embodiments 1-17 and Comparative Examples 1-7” above, the negative electrode plate and battery core were prepared, and the battery core was injected and formed.

Performance Tests of Lithium Ion Batteries Made in Embodiments and Comparative Examples

[0061] In order to verify the influence of the non-aqueous electrolyte for a lithium ion battery of the present application on the battery performance, the related performance tests of the lithium ion batteries made in Embodiments 1-31 and Comparative Examples 1-11 were carried out below. The test performance includes high-temperature cycle performance test, high-temperature storage performance test and low-temperature performance test. The specific test methods are as follows:

1. High-Temperature Cycle Performance Test

[0062] The lithium ion batteries made in Embodiments 1-31 and Comparative Examples 1-11 were placed in an oven with a constant temperature of 45° C., and charged to 4.4 V (LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2/artificial graphite battery, LiCoO.sub.2/artificial graphite battery) or 4.2 V (LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2/artificial graphite battery) at 1 C constant current, and then charged at constant voltage until the current dropped to 0.02 C, then discharged to 3.0 V at 1 C constant current. This cycle was repeated, and the first discharge capacity and the last discharge capacity were recorded.

[0063] The capacity retention rate of high-temperature cycle performance was calculated according to the following formula:

Battery capacity retention rate (%)=last discharge capacity/first discharge capacity×100%%.

2. High-Temperature Storage Performance Test

[0064] The lithium ion batteries made in Embodiments 1-31 and Comparative Examples 1-11 were charged to 4.4 V (LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2/artificial graphite battery, LiCoO.sub.2/artificial graphite battery) or 4.2 V (LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2/artificial graphite battery) at a constant current and constant voltage of 1 C at a normal temperature after being formed. Measure the initial discharge capacity and initial battery thickness of the battery. And then the batteries were discharged to 3 V at 1 C after being stored at 60° C. for 30 days. Measure the retention capacity and recovery capacity of the battery and the thickness of the battery after storage. The formulas are as follows:

Battery capacity retention rate (%)=retention capacity/initial capacity×100%;

Battery capacity recovery rate (%)=recovery capacity/initial capacity×100%;

Thickness expansion rate (%)=(battery thickness after storage−initial battery thickness)/initial battery thickness×100%.

3. Low-Temperature Performance Test

[0065] The lithium ion batteries made in Embodiments 1-31 and Comparative Examples 1-11 were charged to 4.4 V(LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2/artificial graphite battery) or 4.2 V (LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2/artificial graphite battery) at 25° C. after formation, and then discharged to 3.0 V at 1 C constant current, and the discharge capacity was recorded. Then the batteries were charged to 4.4V (LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2/artificial graphite battery, LiCoO.sub.2/artificial graphite battery) or 4.2V (LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2/artificial graphite battery) at 1 C constant current and constant voltage, let stand at −20° C. for 12 hours, then discharged to 3.0 V at 0.2 C constant current, and the discharge capacity was recorded.

Low-temperature discharge efficiency (−20° C.)=discharge capacity (0.2 C,−20° C.)/discharge capacity (1 C,25° C.)×100%.

TABLE-US-00003 TABLE 2 Positive electrode active components, electrolyte composition and battery performance of lithium ion batteries of Embodiments 1-17 and Comparative Examples 1-7 Discharge compounds compounds Capacity capacity represented represented Other retention Storage for 30 days at 60° C. retention by Formula by Formula compounds rate after Capacity Capacity Thickness rate Positive electrode 1 and their 2 and their and 500 cycles retention recovery expansion (0.2C, Embodiments active component contents contents contents at 45° C., 1 C rate rate rate −20° C.) Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound / 80.5% 79.9% 86.0% 13.6% 71.6% 1 1: 20 ppm 23: 1% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound / 82.7% 82.7% 87.9% 11.4% 74.4% 2 2: 50 ppm 23: 1% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound / 87.9% 82.8% 89.3% 9.3% 72.7% 3 4: 100 ppm 23: 1% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound / 89.6% 85.6% 90.2% 7.7% 71.2% 4 7: 500 ppm 23: 1% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound / 88.7% 86.3% 90.8% 6.0% 69.9% 5 8: 1000 ppm 23: 1% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound / 87.4% 85.1% 88.7% 7.2% 68.8% 6 12: 1% 23: 1% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound VC: 1% 90.9% 87.8% 92.3% 12.5% 69.6% 7 1: 500 ppm 23: 1% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound FEC: 1% 88.6% 86.3% 90.5% 15.4% 74.8% 8 1: 500 ppm 23: 1% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound PS: 1% 82.6% 85.4% 92.9% 7.9% 68.7% 9 1: 500 ppm 23: 1% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound DTD: 1% 87.6% 86.6% 90.1% 14.3% 76.7% 10 1: 500 ppm 23: 1% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound LiN(SO.sub.2F) 86.7% 87.8% 91.5% 10.9% 80.7% 11 1: 500 ppm 23: 1% 2: 1% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound 1: / / 79.2% 78.6% 84.7% 14.7% 70.3% 12 20 ppm Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound / 70.3% 69.5.%  78.0% 10.7% 61.5% 13 7: 500 ppm 23: 0.1% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound / 79.6% 76.3% 82.7% 8.9% 63.6% 14 7: 500 ppm 23: 0.2% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound / 83.6% 82.5% 87.8% 7.8% 68.1% 15 7: 500 ppm 23: 0.5% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound / 87.5% 84.3% 89.2% 8.7% 70.3% 16 7: 500 ppm 23: 1.5% Embodiment LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 Compound Compound / 85.3% 83.7% 86.7% 9.7% 69.8% 17 7: 500 ppm 23: 2.0% Comparative LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 / Compound / 62.3% 67.7% 71.9% 18.6% 67.6% Example 1 23: 1% Comparative LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 / Compound VC: 1% 77.2% 76.0% 79.9% 27.0% 65.8% Example 2 23: 1% Comparative LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 / Compound FEC: 1% 79.1% 73.9% 79.2% 28.2% 72.3% Example 3 23: 1% Comparative LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 / Compound PS: 1% 72.5% 77.3% 82.0% 17.1% 66.1% Example 4 23: 1% Comparative LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 / Compound DTD 76.5% 76.3% 79.5% 14.9% 75.5% Example 5 23: 1% Comparative LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 / Compound LiN(SO.sub.2F) 74.5% 78.2% 82.5% 15.7% 74.7% Example 6 23: 1% 2: 1% Comparative LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 / Compound ABPP: 68.1% 68.9% 76.4% 18.1% 61.3% Example 7 23: 1% 500 ppm

[0066] It can be seen from the data in Table 2 that when LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 was used as the positive electrode active component, compared with Comparative Example 1, the high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the corresponding lithium ion batteries of Embodiments 1-6 were significantly improved because of the addition of the representative compounds represented by Formula 1 whose contents were 20 ppm-1% relative to the total mass of the non-aqueous electrolyte for a lithium ion battery. Compared with Comparative Examples 2-6, the non-aqueous electrolyte for a lithium ion battery of Embodiments 7-11 contains 500 ppm of Compound 1 in addition to other compounds, and the high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the corresponding lithium ion batteries were also significantly improved. Comparing Embodiment 4 with Embodiments 13-17, the high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the lithium ion batteries were the best when the content of the compound represented by Formula 2 added in the non-aqueous electrolyte for a lithium ion battery is 1%. Therefore, for the following lithium ion batteries designed in Tables 3 and 4, the concentration of the compound represented by Formula 2 was 1%. Compared with Embodiment 12, the compound represented by Formula 2 in an amount of 1% relative to the total mass of non-aqueous electrolyte for a lithium ion battery was added in Embodiment 1, and the high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the corresponding lithium ion battery were also improved. Compared with Comparative Example 7, in which 2-alkynyl-1,4-bis (bis (2-propinyl)) phosphate (ABPP) with a content of 500 ppm relative to the total mass of non-aqueous electrolyte for a lithium ion battery was added, the high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the corresponding lithium-ion batteries of Embodiments 1-6 were significantly improved due to the addition of the representative compounds represented by Formula 1 with a content of 20 ppm-1% and the compounds represented by Formula 2 with a content of 1% relative to the total mass of the non-aqueous electrolyte for a lithium-ion battery. However, the use of ABPP in Comparative Example 7 also leaded to the decrease of low-temperature performance to some extent.

TABLE-US-00004 TABLE 3 Positive electrode active components, electrolyte composition and battery performance of lithium ion batteries of Embodiments 18-24 and Comparative Examples 8-9 Capacity compounds compounds retention Discharge represented represented Other rate after Storage for 30 days at 60° C. capacity by Formula by Formula compounds 500 cycles Capacity Capacity Thickness retention Positive electrode 1 and their 2 and their and at 45° C., retention recovery expansion rate (0.2C, Embodiments active component contents contents contents 1 C rate rate rate −20° C.) Embodiment 18 LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 Compound Compound / 77.5% 72.9% 76.2% 25.5% 72.4% 1: 20 ppm 26: 1% Embodiment 19 LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 Compound Compound / 82.6% 77.8% 82.6% 25.2% 72.4% 2: 50 ppm 26: 1% Embodiment 20 LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 Compound Compound / 87.1% 82.6% 86.3% 16.2% 70.4% 4: 100 ppm 26: 1% Embodiment 21 LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 Compound Compound / 86.6% 84.6% 88.5% 13.3% 69.9% 7: 500 ppm 26: 1% Embodiment 22 LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 Compound Compound / 87.6% 85.7% 90.3% 9.2% 72.0% 8: 26: 1% 1000 ppm Embodiment 23 LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 Compound Compound / 85.7% 87.3% 91.9% 6.0% 69.3% 12: 1% 26: 1% Embodiment 24 LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 Compound / / 76.2% 71.6% 74.9% 26.6% 71.3% 1: 20 ppm Comparative LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 / Compound / 67.3% 62.5% 66.0% 38.1% 68.2% Example 8 26: 1% Comparative LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 / Compound ABPP: 70.2% 66.7% 68.3% 33.8% 60.9% Example 9 26: 1% 500 ppm

[0067] It can be seen from the data in Table 3 that when .sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 was used as the positive electrode active component, compared with Comparative Example 8, the high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the corresponding lithium ion batteries of Embodiments 18-23 were significantly improved because of the addition of the representative compounds represented by Formula 1 whose contents were 20 ppm-1% relative to the total mass of the non-aqueous electrolyte for a lithium ion battery. Compared with Embodiment 24, the compound represented by Formula 2 in an amount of 1% relative to the total mass of non-aqueous electrolyte for a lithium ion battery was added in Embodiment 18, and the high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the corresponding lithium ion battery were also improved. Compared with Comparative Example 9, in which 2-alkynyl-1,4-bis (bis (2-propinyl)) phosphate (ABPP) with a content of 500 ppm relative to the total mass of non-aqueous electrolyte for a lithium ion battery was added, the high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the corresponding lithium-ion batteries of Embodiments 18-23 were significantly improved due to the addition of the representative compounds represented by Formula 1 with a content of 20 ppm-1% and the compounds represented by Formula 2 with a content of 1% relative to the total mass of the non-aqueous electrolyte for a lithium-ion battery. However, the use of ABPP in Comparative Example 9 also leaded to the decrease of low-temperature performance to some extent.

TABLE-US-00005 TABLE 4 Positive electrode active components, electrolyte composition and battery performance of lithium ion batteries of Embodiments 25-31 and Comparative Examples 10-11 Capacity compounds compounds retention Positive represented represented Other rate after Storage for 30 days at 60° C. Discharge electrode by Formula by Formula compounds 500 Capacity Capacity Thickness capacity active 1 and their 2 and their and cycles at retention recovery expansion retention rate Embodiments component contents conten contents 45° C., 1 C rate rate rate (0.2C, −20° C.) Embodiment LiCoO.sub.2 Compound 1: Compound / 79.6% 74.7% 79.4% 27.1% 74.4% 25 20 ppm 27: 1% Embodiment LiCoO.sub.2 Compound 2: Compound / 84.9% 79.9% 84.7% 27.3% 75.8% 26 50 ppm 27: 1% Embodiment LiCoO.sub.2 Compound 4: Compound / 88.3% 84.9% 88.5% 18.3% 72.2% 27 100 ppm 27: 1% Embodiment LiCoO.sub.2 Compound 7: Compound / 90.6% 87.9% 89.3% 17.9% 73.7% 28 500 ppm 27: 1% Embodiment LiCoO.sub.2 Compound 8: Compound / 88.4% 87.0% 83.9% 16.3% 71.2% 29 1000 ppm 27: 1% Embodiment LiCoO.sub.2 Compound Compound / 87.3% 89.4% 91.1% 6.7% 70.8% 30 12: 1% 27: 1% Embodiment LiCoO.sub.2 Compound 1: 78.3% 73.4% 78.1% 28.0% 73.1% 31 20 ppm Comparative LiCoO.sub.2 / Compound / 69.4% 64.5% 69.7% 38.8% 69.9% Example 10 27: 1% Comparative LiCoO.sub.2 / Compound ABPP: 72.8% 67.3% 73.1% 33.1% 54.9% Example 11 27: 1% 500 ppm

[0068] It can be seen from the data in Table 4 that when LiCoO.sub.2 was used as the positive electrode active component, compared with Comparative Example 10, the high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the corresponding lithium ion batteries of Embodiments 25-30 were significantly improved because of the addition of the representative compounds represented by Formula 1 whose contents were 20 ppm-1% relative to the total mass of the non-aqueous electrolyte for a lithium ion battery. Compared with Embodiment 31, the compound represented by Formula 2 in an amount of 1% relative to the total mass of non-aqueous electrolyte for a lithium ion battery was added in Embodiment 25, and the high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the corresponding lithium ion battery were also improved. Compared with Comparative Example 11, in which 2-alkynyl-1,4-bis (bis (2-propinyl)) phosphate (ABPP) with a content of 500 ppm relative to the total mass of non-aqueous electrolyte for a lithium ion battery was added, the high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the corresponding lithium-ion batteries of Embodiments 25-30 were significantly improved due to the addition of the representative compounds represented by Formula 1 with a content of 20 ppm-1% and the compounds represented by Formula 2 with a content of 1% relative to the total mass of the non-aqueous electrolyte for a lithium-ion battery. However, the use of ABPP in Comparative Example 11 also leaded to the decrease of low-temperature performance to some extent.

The above specific embodiments are used to illustrate the present application, which are only used to help understand the present application, but not to limit it. Further, the singular terms “a”, “an” and “the” include plural reference and vice versa unless the context clearly indicates otherwise. According to the concept of the present application, those skilled in the art may also make some simple deductions, variations or alternatives. These deductions, variations or alternatives also fall within the scope of the claims of the present application.