Lithium ion battery electrolyte and lithium ion battery thereof

Abstract

The application discloses a lithium ion battery electrolyte and a lithium ion battery thereof, wherein the lithium ion battery electrolyte comprises a lithium salt, a nonaqueous organic solvent and an additive; the nonaqueous organic solvent comprises a carbonate compound; and the additive comprises a compound A shown in a structural formula I and a compound B shown in a structural formula II; wherein R1 is selected from halogen; R2-R4 are each independently selected from halogen, an alkyl group, an alkenyl group, an alkyne group or a silyl group; m is selected from 0 or 1; and X is selected from carbon, sulfur or phosphorus. The synergistic effect of the compound A and the compound B can reduce the interface side reaction of the lithium ion battery during the cycle and storage processes, effectively inhibit the decomposition of the SEI interface, and further improve the cycle performance and low-temperature performance of the lithium ion battery.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of lithium ion batteries, and particularly relates to a lithium ion battery electrolyte and a lithium ion battery thereof. BACKGROUND

[0002] Lithium ion batteries have been widely used in many fields due to their high operating voltage, high energy density, long cycle life, and relatively environmentally friendly characteristics. In particular, in the 3C (computer, communication, and consumer electronics) product field, lithium ion batteries have almost become the standard configuration of portable electronic devices. With the advancement of technology and the growing demand for thinner designs from consumers, lithium ion battery technology is also evolving to meet these new demands.

[0003] The performance of lithium ion batteries can be affected by the oxidative decomposition of the electrolyte, especially under cycling and high-temperature storage conditions, the dissolution of metal ions can further cause a significant decrease in battery performance. As the demand for lithium ion batteries in the market grows, the requirements for their overall performance are also increasing. In order to solve these problems and improve the overall performance of the battery, the use of additives has become an effective means. There are many types of additives, which can be divided into film-forming additives, overcharge protection additives, conductive additives, flame-retardant additives, electrolyte stabilizers, etc. according to the role of the additives in the electrolyte. No matter which additive, it accounts for a small proportion in the electrolyte, but it is widely researched and developed due to its obvious function.

[0004] In order to improve the high-temperature performance of lithium ion batteries, carbonic acid ester compounds are generally selected as the main component of non-aqueous organic solvents. However, the melting point of carbonic acid ester compounds is relatively high, and the conductivity of the electrolyte decreases very quickly at low temperatures, the battery impedance increases rapidly, and it is difficult to meet the low-temperature discharge performance of the battery. In terms of additives, in order to further improve the high-temperature performance, vinylene carbonate, vinyl ethylene carbonate and other additives are generally used, but this type of additive also causes the battery impedance to be large, especially at low temperatures, the battery impedance increases very obviously, resulting in a decrease in the low-temperature performance of the battery.

[0005] Therefore, there is an urgent need for a lithium ion battery electrolyte and a lithium ion battery thereof to solve the problems of the prior art. SUMMARY

[0006] In view of the above problems, the purpose of the present application is to provide a lithium ion battery electrolyte and a lithium ion battery thereof, which can improve the cycle performance and low-temperature performance of the lithium ion battery.

[0007] To achieve the above object, the present application provides a lithium ion battery electrolyte, comprising a lithium salt, a non-aqueous organic solvent and an additive, the non-aqueous organic solvent comprises a carbonate compound, and the additive comprises a compound A shown in structural formula I and a compound B shown in structural formula II.

[0008]

[0009] wherein R1 is selected from halogen, R2-R4 are each independently selected from halogen, alkyl, alkenyl, alkynyl or silyl, m is selected from 0 or 1, and X is selected from carbon, sulfur or phosphorus.

[0010] Compared with the prior art, the lithium ion electrolyte of the present application comprises a lithium salt, a non-aqueous organic solvent and an additive, the non-aqueous organic solvent comprises a carbonate compound, and the additive comprises a compound A and a compound B having a special structure, the compound A has a relatively low oxidation potential and can be oxidized on the electrode surface before the solvent, forming a thin interface layer, the interface layer has a relatively high lithium ion transmission efficiency, is not easy to shrink at low temperature, can maintain the lithium ion transmission channel at low temperature, and improves the low temperature performance of the lithium ion battery, but the F-S bond energy in the compound A is low and is easy to break, and then a defluorination reaction occurs with the alpha-H on the carbonate compound, resulting in an increase in the acid value of the electrolyte, so the compound A is easy to produce acidic substances, destroys the SEI film, and causes the cycle performance of the battery to deteriorate. The compound B of the present application not only can polymerize at the negative electrode to form a high-toughness SEI, but also has Lewis base properties, can complex the acidic substances produced by the compound A, inhibit the destruction of the acidic substances to the electrode electrolyte interface, and ensure the cycle performance of the battery. In summary, the synergistic effect of the compound A and the compound B can reduce the interface side reaction of the battery during the cycle and storage process, effectively inhibit the decomposition of the SEI interface, and then improve the cycle performance and low temperature performance of the lithium ion battery.

[0011] Further, R2-R4 of the present application are each independently selected from halogen, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, or C1-C6 silyl, and R2-R4 groups are the same. Specifically, halogen can be fluorine (F), chlorine (Cl), bromine (Br), iodine (I). C1-C6 alkyl refers to straight chain or branched saturated hydrocarbon groups containing 1 to 6 carbon atoms, which can be straight (n- normal) or with branches (iso- isomer), such as but not limited to methyl, ethyl, n-propyl, iso-propyl, n-butyl, t-butyl, and the like. C2-C6 alkenyl refers to unsaturated hydrocarbon groups containing 2 to 6 carbon atoms and at least one double bond. These alkenyl groups can be straight chain or branched, and the double bond can be in different positions; such as C2-C6 alkenyl can be but not limited to vinyl, propenyl, iso-propenyl, butenyl, pentenyl, hexenyl. C2-C6 alkynyl refers to unsaturated hydrocarbon groups containing 2 to 6 carbon atoms and at least one triple bond, which can be straight chain or branched, such as C2-C6 alkynyl can be but not limited to ethynyl, propynyl, butynyl, pentynyl, hexynyl. C1-C6 silyl refers to organic groups containing 1 to 6 carbon atoms and directly connected to silicon atom, which can be straight chain or branched, such as C1-C6 silyl can be but not limited to -Si(CH3)3, -Si(CH3)2(C2H5).

[0012] Further, compound A of the present application is selected from at least one of compound A1 to compound A3:

[0013]

[0014] Further, compound B of the present application is selected from at least one of compound B1 to compound B4:

[0015]

[0016] Further, the mass percentage of compound A of the present application in the lithium ion battery electrolyte is 0.1-10.0%, specifically, the mass percentage of compound A in the non-aqueous electrolyte can be but not limited to 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 7%, 8%, 9%, 10%. Preferably, the mass percentage of compound A in the lithium ion battery electrolyte is 0.1-2%.

[0017] Further, the mass percentage of the compound B in the lithium ion battery electrolyte is 0.1-10.0%. Specifically, the mass percentage of the compound B in the non-aqueous electrolyte can be, but is not limited to, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 6%, 7%, 8%, 9%, 10%. Preferably, the mass percentage of the compound B in the lithium ion battery electrolyte is 0.1-2%.

[0018] Further, the lithium salt of the present application includes at least one of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethylsulfonylimide (LiTFSI), lithium methanesulfonate, lithium trifluoromethanesulfonate, lithium fluorosulfonate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, lithium diphosphate and lithium lower aliphatic carboxylate. Specifically, the mass percentage of the lithium salt in the lithium ion battery electrolyte is 5-30%, such as the content of the lithium salt can be, but is not limited to, 5%, 10%, 15%, 20%, 25%, 30%; preferably, the mass percentage of the lithium salt in the lithium ion battery electrolyte is 5-18%.

[0019] Further, the carbonate compound of the present application includes at least one of cyclic carbonate and chain carbonate. Specifically, the cyclic carbonate can be, but is not limited to, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), pentylene carbonate, vinylene carbonate (VC) or derivatives thereof; the chain carbonate includes, but is not limited to, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), propylene carbonate.

[0020] Further, the non-aqueous organic solvent of the present application further includes at least one of carboxylic acid ester compound and ether compound. Both the carboxylic acid ester compound and the ether compound are polar solvents, which can well dissolve the lithium salt to form a stable lithium ion battery electrolyte. More specifically, the carboxylic acid ester compound can provide a higher dielectric constant, and the ether compound can provide better low-temperature performance.

[0021] Further, the carboxylic acid ester of the present application includes at least one of cyclic carboxylic acid ester and chain carboxylic acid ester, and the cyclic carboxylic acid ester can specifically include, but is not limited to, at least one of γ-butyrolactone (GBL), γ-valerolactone (GVL), δ-valerolactone (DVL); the chain carboxylic acid ester includes, but is not limited to, methyl acetate (MAC), ethyl acetate (EA), propyl acetate (PA), butyl acetate (BA), propyl propionate (PP), butyl propionate (BP).

[0022] Further, the ether compound of the present application includes a cyclic ether or a chain ether, the cyclic ether specifically can include but is not limited to at least one of 1,3-dioxolane (DOL), 1,4-dioxane (DX), crown ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH3-THF), 2-trifluoromethyltetrahydrofuran (2-CF3-THF); the chain ether specifically can include but is not limited to dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethyleneglycol di-n-propyl ether, ethyleneglycol di-n-butyl ether, diethyleneglycol dimethyl ether.

[0023] Further, the lithium ion battery electrolyte of the present application further includes an additive, the additive is selected from at least one of vinylene carbonate (VC), vinylidene carbonate (VEC), fluoroethylene carbonate (FEC), vinyl sulfite (ES), 1,3 propanesultone (PS), 1,3-propene sultone (PES), 1,4-butanesultone (BS), vinyl sulfate (DTD), succinic anhydride (SA), maleic anhydride (MA), 2-methyl maleic anhydride (MMA), methyl carbonic acid-2-propynyl ester, tetraethylenesilane, triallyl isocyanurate, hexamethylene diisocyanate, phenanthroline, p-phenylene diisocyanate, 2,4-toluene diisocyanate, N-phenyl bis(trifluoromethanesulfonyl)imide, bisvinyl sulfate, benzyl methanesulfonate, bisvinyl sulfate, bispropylene sulfite, hydroquinone difluorosulfonate, triallyl phosphate, tripropargyl phosphate, 2,4-butane sultone, isocyanatoethyl methacrylate, methanedi sulfonate methylene, tris(trimethylsilyl)borate, tris(trimethylsilyl)phosphate, tris(vinyldimethylsilyl)phosphate. Specifically, the mass percentage of the additive in the lithium ion battery electrolyte of the present application is 0.1-5%, such as the additive content can be but is not limited to 0.1%, 0.5%, 1%, 1.6%, 1.9%, 2.6%, 3.2%, 3.8%, 4.3%, 4.8%, 5%. Preferably, the mass percentage of the additive in the lithium ion battery electrolyte is 0.1-2%.

[0024] Correspondingly, the second aspect of the present application further provides a lithium ion battery, including a positive electrode, a negative electrode, and further including the above-mentioned lithium ion battery electrolyte. The lithium ion battery has good cycle performance and low temperature performance.

[0025] Further, the active material of the positive electrode of the present application includes at least one of lithium-containing phosphate of olivine structure, lithium transition metal oxide, and their respective modified compounds. Specifically, the lithium-containing phosphate of olivine structure includes, but is not limited to, at least one of lithium iron phosphate (e.g., LiFePO4), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite of lithium manganese iron phosphate and carbon. The lithium transition metal oxide includes, but is not limited to, lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi x Co y Mn 1-x-y M z O2, wherein 0.6≤x<0.9, x+y<1, 0≤z<0.08, and M is at least one of Al, Mg, Zr, and Ti). Preferably, the active material of the positive electrode of the present application is LiNi 0.8 Co 0.1 Mn 0.1 Zr 0.03 O2.

[0026] Further, the active material of the negative electrode of the present application includes at least one of carbon-based negative electrode, silicon-based negative electrode, tin-based negative electrode, and lithium negative electrode. The carbon-based negative electrode can include graphite, hard carbon, soft carbon, graphene, mesocarbon microbeads, etc.; the silicon-based negative electrode can include silicon material, oxide of silicon, silicon-carbon composite material, and silicon alloy material, etc.; the tin-based negative electrode can include tin, tin-carbon, tin-oxygen, tin metal compound; and the lithium negative electrode can include metallic lithium or lithium alloy. The lithium alloy can be at least one of lithium-silicon alloy, lithium-sodium alloy, lithium-potassium alloy, lithium-aluminum alloy, lithium-tin alloy, and lithium-indium alloy. DETAILED DESCRIPTION

[0027] For the purpose of further illustrating the objects, technical solutions, and advantages of the present application, a further description will be given with reference to the specific examples. It should be noted that, if the specific conditions are not specified in the examples and comparative examples, the conventional conditions or the conditions recommended by the manufacturers can be used, and the reagents or instruments not specified by the manufacturers are all conventional products available in the market.

[0028] Example 1

[0029] The present example provides a method for preparing a lithium ion battery, comprising the following steps:

[0030] (1) mixing a ternary material LiNi 0.8 Co 0.1 Mn 0.1 Zr 0.03O2, conductive agent Super P, binder PVDF and carbon nanotube (CNT) were mixed in a mass ratio of 96.5:1.5:1:1 to form a slurry of lithium ion battery cathode with a certain viscosity, which was coated on an aluminum foil current collector with a coating amount of 324 g / m 2 After drying at 85℃, cold pressing was performed; then edge cutting, piece cutting and striping were performed, and after striping, drying was performed at 85℃ under vacuum for 4h, and tab welding was performed to produce a required cathode sheet;

[0031] (2) Artificial graphite and silicon were mixed in a mass ratio of 90:10, and then mixed with conductive agent Super P, thickening agent CMC, and binder SBR (styrene-butadiene rubber emulsion) in a mass ratio of 95:1.5:1.0:2.5 to form a slurry, which was coated on both sides of a copper foil, and then dried and rolled to obtain a negative electrode sheet, thereby producing a required negative electrode sheet;

[0032] (3) In a glove box filled with nitrogen (O2<1 ppm, H2O<1 ppm), a mixed solvent obtained by mixing ethylene carbonate (EC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), propyl propionate (PP), and dimethoxy methane (DMM) in a mass ratio of 3:3:4:2:2 was used as a non-aqueous organic solvent, and then additives and adjuvants were added to obtain a mixed solution. The mixed solution was sealed, packaged, and frozen in a quick-freezing interval (-4℃) for 2h, and then taken out and mixed with lithium hexafluorophosphate in a glove box filled with nitrogen (O2<1 ppm, H2O<1 ppm) to obtain a lithium ion battery electrolyte;

[0033] (4) The above-mentioned cathode sheet, anode sheet and separator were stacked to produce a lithium ion battery with a thickness of 4.7 mm, a width of 55 mm, and a length of 60 mm, which was vacuum baked at 75℃ for 10h, and then injected with the above-mentioned lithium ion battery electrolyte. After standing for 24h, the battery was charged to 4.4V at a constant current of 0.1C (180mA), and then charged to a current of 0.05C (90mA) at a constant voltage of 4.4V; then the battery was discharged to 3.0V at 0.2C (180mA), and the above-mentioned charging and discharging was repeated twice, and finally the battery was charged to 3.8V at 0.2C (180mA) to obtain a lithium ion battery.

[0034] The formulations of the lithium ion battery electrolytes of Examples 1-16 and Comparative Examples 1-6 are shown in Table 1, wherein the preparation processes of the lithium ion battery electrolytes, cathode sheets, anode sheets and lithium ion batteries of Examples 2-16 and Comparative Examples 1-6 are the same as those of Example 1.

[0035] Table 1 Formulations of lithium ion battery electrolytes of examples and comparative examples

[0036]

[0037] Lithium ion battery electrolyte acidity test:

[0038] The lithium ion battery electrolyte prepared in the above Examples 1-9 and Comparative Example 5 was weighed at 20 g, placed in a conical flask, weighed and recorded as mass M, and 1-2 drops of neutral red methylene blue mixed indicator was added. The titration was performed using a concentrated triethylamine super dry acetonitrile solution with a concentration of C, and the titration volume of the standard solution V was recorded. The electrolyte acidity was calculated according to the following formula: electrolyte acidity (ppm) = 20.006 x 1000 x V x C / M;

[0039] The remaining lithium ion battery electrolyte was placed in a clean and dry aluminum plastic bottle, sealed and placed in a 60°C oven for three days. Then the lithium ion battery electrolyte was taken out and the acidity of the lithium ion battery electrolyte was determined again according to the above method. The test results are shown in Table 2.

[0040] Table 2 Test results of the acidity of lithium ion battery electrolyte

[0041] Group Acidity before storage / ppm Acidity after 3 days storage at 60°C / ppm Example 1 23.01 46.85 Example 2 25.32 46.35 Example 3 25.87 48.32 Example 4 25.85 45.37 Example 5 25.47 48.42 Example 6 24.39 47.18 Example 7 23.05 45.71 Example 8 23.61 48.60 Example 9 23.01 48.87 Comparative Example 5 24.68 189.73

[0042] From the test results in Table 2, if only compound A is present, the electrolyte acid value increases significantly. This is because the F-S bond in compound A has low bond energy and is easily broken, thereby undergoing defluorination with the α-H on the carbonate compound, resulting in an increase in electrolyte acid value. Compound B can complex the acidic substances produced by compound A, thereby inhibiting the increase in electrolyte acid value.

[0043] The lithium ion batteries prepared in Examples 1-16 and Comparative Examples 1-6 were subjected to high temperature storage performance test, high temperature cycle performance test, room temperature cycle performance test, and low temperature performance test according to the following conditions, and the results are shown in Table 3.

[0044] High temperature storage performance test :

[0045] At room temperature (25°C), the lithium ion battery was subjected to one 0.5C / 0.5C charge and discharge (the battery discharge capacity was recorded as C0), and the upper limit voltage was 4.4V. Then the battery was charged to 4.4V under 0.5C constant current and constant voltage conditions, and the battery thickness was measured (the thickness was recorded as D0). The battery was placed in a 60°C oven for 30d, taken out and the battery thickness was measured (the thickness was recorded as D1). The battery was placed in a 25°C environment and discharged at 0.5C (the discharge capacity was recorded as C1). The lithium ion battery was subjected to one 0.5C / 0.5C charge and discharge (the battery discharge capacity was recorded as C2) at room temperature (25°C), and the upper limit voltage was 4.4V. The capacity retention rate, capacity recovery rate and thickness expansion rate were calculated.

[0046] Capacity retention rate = (C1 / C0) x 100%

[0047] Capacity recovery rate = (C2 / C0) * 100%

[0048] Thickness expansion rate = (D1 / D0) * 100%

[0049] Normal temperature cycle performance test :

[0050] At room temperature (25°C), the lithium ion battery was charged and discharged once at 1.0C / 1.0C (battery discharge capacity was C0), and the upper limit voltage was 4.4V. Then, the battery was charged and discharged at 1.0C / 1.0C for 500 cycles at room temperature (battery discharge capacity was C1), and the capacity retention rate was calculated.

[0051] Capacity retention rate = (C1 / C0) * 100%

[0052] High temperature cycle performance test :

[0053] At an excessively high temperature (45°C), the lithium ion battery was charged and discharged once at 1.0C / 1.0C (battery discharge capacity was C0), and the upper limit voltage was 4.4V. Then, the battery was charged and discharged at 1.0C / 1.0C for 400 cycles at room temperature (battery discharge capacity was C1), and the capacity retention rate was calculated.

[0054] Capacity retention rate = (C1 / C0) * 100%

[0055] Low temperature performance test :

[0056] At room temperature (25°C), the lithium ion battery was charged and discharged once at 0.5C / 0.5 (battery cutoff voltage was 3.0V, and discharge capacity was C0), and the upper limit voltage was 4.4V (cutoff current was 0.05C). Then, the battery was charged to 4.4V at 0.5C at room temperature (25°C) (cutoff current was 0.05C), and then the battery was transferred to a condition of -20°C for 4 hours, and discharged at 0.5C to 3.0V, and the discharge capacity was C1, and the capacity retention rate was calculated.

[0057] Capacity retention rate = (C1 / C0) * 100%

[0058] Table 3: Test results of lithium ion battery performance

[0059]

[0060]

[0061] From Table 3, it can be seen that, compared with Comparative Example 1, the lithium ion batteries of Examples 1-16 not only have good high-temperature storage performance and high-temperature cycle performance, but also have good low-temperature performance at-20℃, because the non-aqueous electrolyte thereof comprises compound A and compound B. This is because compound A has a relatively low oxidation potential, can be oxidized on the electrode surface before the solvent, and forms a thin interface layer with a relatively optimal lithium ion transmission efficiency, is not prone to shrinkage at low temperature, can maintain a lithium ion transmission channel at low temperature, and improves the low-temperature performance of the lithium ion battery. However, the F-S bond in the compound A has low bond energy and is prone to breakage, and further defluorination occurs with the α-H on the carbonate compound, resulting in an increase in the acid value of the electrolyte. Therefore, the compound A is prone to produce acidic substances in the battery, which damages the SEI film and causes the cycle performance of the battery to deteriorate. The compound B of the present application not only can polymerize at the negative electrode to form a high-toughness SEI, but also exhibits Lewis base characteristics, can complex the acidic substances produced by compound A, and inhibit the damage of the acidic substances to the electrode-electrolyte interface, thereby ensuring the cycle performance of the battery. Therefore, the synergistic effect of compound A and compound B can reduce the interface side reactions of the lithium ion battery during the cycle and storage processes, effectively inhibit the decomposition of the SEI interface, and further improve the cycle performance and low-temperature performance of the lithium ion battery.

[0062] It can be seen from the comparison of Examples 8 and 10-13 that, by adding an additive to the additive of the present application, the cycle performance and low-temperature discharge performance of the lithium ion battery can be further improved.

[0063] It can be seen from the comparison of Examples 10-11 and Examples 14-16 that, when a VC / FEC mixed additive is used in the electrolyte of the lithium ion battery, the cycle performance and low-temperature performance of the lithium ion battery are greatly improved.

[0064] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not intended to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, it is not limited to the examples listed in the embodiments. Those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A lithium-ion battery electrolyte, characterized in that, The lithium salt, the non-aqueous organic solvent and the additive, wherein the non-aqueous organic solvent comprises a carbonate compound, and the additive comprises a compound A represented by structural formula I and a compound B represented by structural formula II. wherein R1 is selected from halogen, R2-R4 are each independently selected from halogen, alkyl, alkenyl, alkynyl or silyl, m is selected from 0 or 1, and X is selected from carbon, sulfur or phosphorus.

2. The lithium-ion battery electrolyte of claim 1, wherein, R2-R4 are each independently selected from halogen, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl or C1-C6 silyl, and the R2-R4 groups are the same.

3. The lithium-ion battery electrolyte of claim 1, wherein, The compound A is selected from at least one of compound A1-compound A3:

4. The lithium-ion battery electrolyte of claim 1, wherein, The compound B is selected from at least one of compound B1-compound B4:

5. The lithium-ion battery electrolyte of claim 1, wherein, The mass percentage of the compound A in the lithium ion battery electrolyte is 0.1-10.0%, and the mass percentage of the compound B in the lithium ion battery electrolyte is 0.1-10.0%.

6. The lithium-ion battery electrolyte of claim 1, wherein, The lithium salt comprises at least one of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethylsulfonylimide, lithium methylsulfate, lithium trifluoromethylsulfate, lithium fluorosulfate, lithium bisoxalate borate, lithium difluorobisoxalate borate, lithium difluorophosphate, lithium difluorobisoxalate phosphate, lithium diphosphate and lithium lower aliphatic carboxylate.

7. The lithium-ion battery electrolyte of claim 1, wherein, The non-aqueous organic solvent further comprises at least one of a carboxylic ester compound and an ether compound.

8. The lithium-ion battery electrolyte of claim 1, wherein, The additive is selected from at least one of vinylene carbonate, vinylidene carbonate, fluorinated ethylene carbonate, vinyl sulfite, 1,3 propanesultone, 1,3-propene sultone, 1,4-butanesultone, vinyl sulfate, succinic anhydride, maleic anhydride, 2-methyl maleic anhydride, methyl carbonic acid-2-propynyl ester, tetraethylenylsilane, triallyl isocyanurate, hexamethylene diisocyanate, phenanthroline, p-phenylene diisocyanate, 2,4-toluene diisocyanate, N-phenyl bis(trifluoromethanesulfonyl)imide, bisvinyl sulfate, methylsulfate phenyl, bisvinyl sulfate, bispropylene sulfate, hydroquinone difluorosulfonate, triallyl phosphate, tripropargyl phosphate, 2,4-butane sultone, isocyanatoethyl methacrylate, methanedi sulfonate, tris(trimethylsilyl)borate, tris(trimethylsilyl)phosphate, tris(vinyldimethylsilyl)phosphate.

9. A lithium ion battery comprising a positive electrode, a negative electrode, characterized in that, The lithium ion battery electrolyte as claimed in any one of claims 1-8.

10. The lithium-ion battery of claim 9, wherein, The active material of the positive electrode comprises a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide and a modified compound of each thereof.

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