WO2017084109A1 - Non-aqueous electrolyte of lithium ion battery and lithium ion battery - Google Patents

Abstract

Disclosed are a non-aqueous electrolyte of a lithium ion battery and the lithium ion battery. The non-aqueous electrolyte of the lithium ion battery comprises a non-aqueous organic solvent, a lithium salt and additives, wherein the additives comprise an additive A and an additive B, the additive A is selected from a compound represented by structural formula 1, wherein R is selected from an alkyl with the carbon atom number of 1-3, m is a natural integer of 1-2, and the content of the additive A is 0.1 percent -2 percent with respect to the total mass of the non-aqueous electrolyte of the lithium ion battery; the additive B is selected from at least one of vinylene carbonate, vinylethylene carbonate and fluoroethylene carbonate, and the content of the additive B is 0.5 percent -3 percent with respect to the total mass of the non-aqueous electrolyte of the lithium ion battery. The high- and low- temperature performances of the non-aqueous electrolyte of the lithium ion battery of the present invention are excellent. DARWING: AA Structural formula 1

Description

Lithium ion battery non-aqueous electrolyte and lithium ion battery Technical field

The invention relates to the technical field of lithium ion battery electrolytes, in particular to a lithium ion battery non-aqueous electrolyte and a lithium ion battery.

Background technique

With the development of new energy vehicles, non-aqueous electrolyte lithium-ion batteries have great application prospects in power supply systems for new energy vehicles. Although these non-aqueous electrolyte batteries have been put to practical use, they have not been satisfactory in durability, especially at a high temperature of 45 ° C for a short service life. Especially for power vehicles and energy storage systems, non-aqueous electrolyte lithium-ion batteries require normal operation in cold regions, and high temperature performance.

In the non-aqueous electrolyte lithium ion battery, the non-aqueous electrolyte is a key factor affecting the high and low temperature performance of the battery. In particular, the additive in the non-aqueous electrolyte is particularly important for the performance of the high-low temperature performance of the battery. During the initial charging of the lithium ion battery, lithium ions in the positive electrode material of the battery are deintercalated and embedded in the carbon negative electrode through the electrolyte. Due to its high reactivity, the electrolyte reacts on the surface of the carbon negative electrode to produce a compound such as Li ₂ CO ₃ , LiO, LiOH, etc., thereby forming a passivation film on the surface of the negative electrode, which is called a solid electrolyte interface film (SEI). The SEI film formed during the initial charging process not only prevents the electrolyte from further decomposing on the surface of the carbon negative electrode, but also acts as a lithium ion tunneling, allowing only lithium ions to pass. Therefore, the SEI film determines the performance of the lithium ion battery.

In order to improve the performance of the battery, many researchers have improved the performance of the SEI film by adding different additives to the electrolyte to improve the performance of the battery. For example, it is proposed in Japanese Patent Laid-Open Publication No. 2000-123867 to improve battery characteristics by adding vinylene carbonate to an electrolytic solution. The method inactivates the surface of the electrode by polymerizing the polymer produced by polymerizing vinylene carbonate to prevent decomposition of the electrolyte on the surface of the electrode, thereby improving the cycle performance of the battery. However, since it is difficult for lithium ions to pass through the passivation film, the internal resistance of the battery rises, resulting in poor performance of the battery below zero. At the same time, the battery is prone to gas production during high temperature and causes the battery to bulge. The Chinese patent application CN 1385919A discloses an electrolyte containing a compound of RSO ₃ Si(C _m H _2m+1 ) ₃ which can improve the low-temperature discharge performance of the battery. However, in the experiment, we found that the electrolyte containing RSO ₃ Si(C _m H _2m+1 ) ₃ compound can improve the low-temperature discharge performance of the battery, but the high-temperature performance of the battery is not ideal, and the battery cannot be put into practical use.

Summary of the invention

The present invention provides a lithium ion battery nonaqueous electrolyte capable of achieving both high and low temperature performance of a battery, and further provides a lithium ion battery including the lithium ion battery nonaqueous electrolyte.

According to a first aspect of the present invention, there is provided a lithium ion battery nonaqueous electrolyte comprising a nonaqueous organic solvent, a lithium salt and an additive, the additive comprising an additive A and an additive B, wherein the additive A is selected from the formula 1 a compound wherein R is selected from a hydrocarbon group having 1 to 3 carbon atoms, and m is a natural integer of 1-2,

The content of the above additive A is 0.1% to 2% with respect to the total mass of the nonaqueous electrolyte of the lithium ion battery; the additive B is selected from the group consisting of vinylene carbonate (VC), ethylene carbonate (VEC), and fluoroethylene carbonate. At least one of the esters (FEC), the content of the above additive B is from 0.5% to 3% based on the total mass of the nonaqueous electrolyte of the lithium ion battery.

As a preferred embodiment of the invention, wherein R is selected from the group consisting of methyl, ethyl or propyl.

As a preferred embodiment of the invention, m is 1.

As a preferred embodiment of the present invention, the additive A is at least one selected from the group consisting of trimethylsilyl methanesulfonate, trimethylsilylethanesulfonate, and trimethylsilylpropanesulfonate.

As a further improvement of the present invention, the nonaqueous organic solvent is a mixture of a cyclic carbonate and a chain carbonate, and the cyclic carbonate is selected from the group consisting of ethylene carbonate, propylene carbonate and butylene carbonate. Alternatively, the chain carbonate may be one or more selected from the group consisting of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and methyl propyl carbonate.

As a further improvement of the present invention, the above lithium salt is selected from the group consisting of LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiN(SO ₂ CF ₃ ) ₂ , LiN(SO ₂ C ₂ F ₅ ) ₂ , LiC (SO _{2 )} One or more of CF ₃ ) ₃ and LiN(SO ₂ F) ₂ .

As a further improvement of the present invention, the above additives further include 1,3-propane sultone (1,3-PS), 1,4-butane sultone (BS), and 1,3-propene sultone. One or more of (PST).

According to a second aspect of the present invention, there is provided a lithium ion battery comprising a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode, and further comprising the lithium ion battery nonaqueous electrolyte of the first aspect.

As a further improvement of the present invention, the above positive electrode is selected from the group consisting of LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiCo _1-y M _y O ₂ , LiNi _1-y M _y O ₂ , LiMn _2-y M _y O ₄ and one of _{2 LiNi x Co y Mn z M} 1-xyz O , or two or more thereof, wherein, M is selected Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr One or more of Sr, V and Ti, and 0 ≤ y ≤ 1, 0 ≤ x ≤ 1, 0 ≤ z ≤ 1, x + y + z ≤ 1.

The non-aqueous electrolyte of the lithium ion battery of the invention contains the additive A and the additive B, and the additive A can be decomposed on the negative electrode to form a passivation film, and the passivation film has low impedance, which is favorable for the passage of lithium ions and improves the low temperature of the battery. Performance, but the passivation film has poor stability and the battery high temperature performance is not ideal. At this time, if it coexists with the additive B, the additive B can be decomposed on the surface of the positive electrode and the negative electrode to form a passivation film, thereby forming a passivation film in which the additive A and the additive B decomposition product are combined, which shows that the additive cannot be reached when it exists alone. Low temperature performance takes into account the characteristics.

detailed description

The invention will now be further described in detail by way of specific embodiments.

One embodiment of the present invention provides a lithium ion battery nonaqueous electrolyte comprising a nonaqueous organic solvent, a lithium salt and an additive, the additive comprising an additive A and an additive B, wherein the additive A is selected from the group consisting of the compound of the formula 1, wherein R It is selected from a hydrocarbon group having a carbon number of 1-3, and m is a natural integer of 1-2.

The above additive B is at least one selected from the group consisting of vinylene carbonate (VC), ethylene carbonate (VEC), and fluoroethylene carbonate (FEC).

In the present invention, R is selected from a hydrocarbon group having 1 to 3 carbon atoms, wherein the hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group, that is, an alkyl group, an alkenyl group or an alkynyl group, and an alkyl group such as a methyl group or an ethyl group. Examples of propyl, isopropyl, alkenyl groups such as vinyl, propenyl, allyl, alkynyl groups such as ethynyl, propynyl, propargyl.

In the present invention, in the first charging process, the compound of the structural formula 1 can be decomposed on the surface of the negative electrode in preference to the solvent molecule, and the decomposition product thereof is mainly RSO ₃ Li, which is advantageous for the passage of lithium ions. As a result of intensive studies, the inventors have found that R is selected from a hydrocarbon group having 1 to 3 carbon atoms, and the above-described excellent effect for facilitating the passage of lithium ions can be remarkably obtained. However, when R is selected from a hydrocarbon group having a carbon number of more than 3, since the R group is too large, an increase in the component which is unfavorable for the passage of lithium ions in the decomposition product may hinder the passage of lithium ions and lower the low-temperature performance of the battery. Additive B also forms a polymer passivation film on the positive and negative electrodes during the first charging process, further preventing the decomposition of solvent molecules. However, the passivation film has a large impedance, and the low-temperature performance of the battery is poor. At the same time, the battery is severely produced when the battery is stored at a high temperature, and the high-temperature storage performance of the battery is lowered. When the additive A and the additive B are used at the same time, a passivation film in which the additive A and the additive B decomposition product are combined on the surface of the negative electrode can be formed, and the high-low temperature performance characteristics which cannot be attained when each additive is present alone are exhibited.

In a preferred embodiment of the invention, the content of the additive A is from 0.1% to 2% based on the total mass of the nonaqueous electrolyte of the lithium ion battery described above. When it is less than 0.1%, it is difficult to form a passivation film on the surface of the negative electrode sufficiently, so that it is difficult to sufficiently improve the low-temperature discharge performance of the non-aqueous electrolyte battery, and when it exceeds 2%, the compound of Structural Formula 1 is formed too thick on the surface of the positive and negative electrodes. Passivation of the film to reduce the high temperature performance of the battery. The content of the additive B is 0.5% to 3% with respect to the total mass of the nonaqueous electrolyte of the above lithium ion battery. When it is less than 0.5%, it is difficult to form a passivation film on the surface of the positive and negative electrodes sufficiently, so that it is difficult to sufficiently improve the high temperature performance of the nonaqueous electrolyte battery, and when it exceeds 3%, the additive B forms an excessively thick passivation on the positive and negative electrodes. The membrane increases the internal resistance of the battery and generates a large amount of gas, thereby lowering the low temperature performance and high temperature performance of the battery.

In the electrolyte solution for a nonaqueous lithium ion battery of the present invention, by simultaneously using the additive A and the additive B, the high-temperature storage characteristics and low-temperature characteristics of the battery are remarkably improved as compared with the separate addition, and the mechanism of action is not well understood. It is also speculated that when the two additives are used together, through some interaction (eg If synergistic, the composite passivation film formed by the two additives is more stable, and it is easy to conduct lithium ions even at low temperatures.

In a preferred embodiment of the present invention, the nonaqueous organic solvent is a mixture of a cyclic carbonate and a chain carbonate, and the cyclic carbonate is selected from the group consisting of ethylene carbonate, propylene carbonate and butylene carbonate. The above chain carbonate is one or more selected from the group consisting of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and methyl propyl carbonate.

A mixture of a high dielectric constant cyclic carbonate organic solvent and a low viscosity chain carbonate organic solvent is used as a solvent for a lithium ion battery electrolyte, so that the organic solvent mixture has high ionic conductivity and high at the same time. Dielectric constant and low viscosity.

In a preferred embodiment of the invention, the above lithium salt is selected from the group consisting of LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiN(SO ₂ CF ₃ ) ₂ , LiN(SO ₂ C ₂ F ₅ ) ₂ , LiC (SO) One or two or more of ₂ CF ₃ ) ₃ and LiN(SO ₂ F) ₂ , and the lithium salt is preferably a mixture of LiPF ₆ or LiPF ₆ and other lithium salts.

In a preferred embodiment of the present invention, the above additive further comprises 1,3-propane sultone (1,3-PS), 1,4-butane sultone (BS), and 1,3-propene sulfonate. One or more of esters (PST).

The above film-forming additive can form a more stable SEI film on the surface of the graphite negative electrode, thereby further improving the performance of the lithium ion battery.

One embodiment of the present invention provides a lithium ion battery comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and further includes the lithium ion battery nonaqueous electrolyte of the first aspect.

In a preferred embodiment of the present invention, the above positive electrode is selected from the group consisting of LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiCo _1-y M _y O ₂ , LiNi _1-y M _y O ₂ , LiMn _2-y M _y O ₄ and _{LiNi x Co y Mn z M 1} -xyz O 2 in one or two or more, wherein, M is selected Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, One or more of Cr, Sr, V, and Ti, and 0 ≤ y ≤ 1, 0 ≤ x ≤ 1, 0 ≤ z ≤ 1, x + y + z ≤ 1.

In one embodiment of the invention, the positive electrode material is LiNi _0.5 Co _0.2 Mn _0.3 O ₂ and the negative electrode material is artificial graphite.

The invention is described in detail below by means of specific examples. It is to be understood that the examples are merely illustrative and are not intended to limit the scope of the invention.

Example 1

1) Preparation of electrolyte

Ethylene carbonate (EC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of EC:DEC:EMC=1:1:1, and then lithium hexafluorophosphate (LiPF ₆ ) was added to the mole. The concentration was 1 mol/L, and then 0.5% of trimethylsilyl methanesulfonate based on the total mass of the electrolyte and 1% of vinylene carbonate (VC) based on the total mass of the electrolyte were added.

2) Preparation of positive electrode plate

The positive active material lithium nickel cobalt manganese oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , conductive carbon black Super-P and binder polyvinylidene fluoride (PVDF) were mixed at a mass ratio of 93:4:3, and then they were mixed. Dispersion in N-methyl-2-pyrrolidone (NMP) gave a positive electrode slurry. The slurry was uniformly coated on both sides of the aluminum foil, dried, calendered and vacuum dried, and the aluminum lead wire was welded by an ultrasonic welder to obtain a positive electrode plate having a thickness of 120-150 μm.

3) Preparation of negative electrode plate

The negative active material artificial graphite, conductive carbon black Super-P, binder styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) were mixed at a mass ratio of 94:1:2.5:2.5, and then dispersed. In the ionic water, a negative electrode slurry was obtained. 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 welder to obtain a negative electrode plate having a thickness of 120-150 μm.

4) Preparation of the battery core

A polyethylene microporous film having a thickness of 20 μm is placed as a separator between the positive electrode plate and the negative electrode plate, and then a sandwich structure composed of a positive electrode plate, a negative electrode plate and a separator is wound, and the wound body is flattened and placed in a square aluminum. In the metal shell, the lead wires of the positive and negative electrodes are respectively welded to the corresponding positions of the cover plate, and the cover plate and the metal shell are welded together by a laser welding machine to obtain a battery core to be injected.

5) Injecting and forming of the battery core

In the glove box whose dew point is controlled below -40 ° C, the electrolyte prepared above is injected into the cell through the injection hole, and the amount of the electrolyte is required to fill the gap in the cell. Then proceed according to the following steps: 0.05C constant current charging for 3min, 0.2C constant current charging for 5min, 0.5C constant current charging for 25min, after 1 hr, after shaping, sealing, and then further charging to 4.2V with constant current of 0.2C, leaving at room temperature After 24 hr, it was discharged at a constant current of 0.2 C to 3.0 V.

6) High temperature cycle performance test

The battery was placed in an oven at a constant temperature of 45 ° C, charged at a constant current of 1 C to 4.2 V and then charged at a constant voltage until the current dropped to 0.1 C, and then discharged at a constant current of 1 C to 3.0 V, thus circulating for 300 weeks, recording The discharge capacity at the first week and the discharge capacity at the 300th week are calculated by the following formula:

Capacity retention rate = discharge capacity at week 300 / discharge capacity at week 1 * 100%

7) High temperature storage performance test

The formed battery was charged to 4.2 V at a normal temperature with a constant current of 1 C, and the initial discharge capacity of the battery and the initial battery thickness were measured, and then stored at 60 ° C for 7 days, discharged at 1 C to 3 V, and the battery retention capacity and recovery were measured. Capacity and battery thickness after storage. Calculated as follows:

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

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

Thickness expansion ratio (%) = (battery thickness after storage - initial battery thickness) / initial battery thickness × 100%.

8) Low temperature performance test

The formed battery was charged to 4.2 V with a constant current of 1 C at 25 ° C, and then discharged to 3.0 V with a constant current of 1 C to record the discharge capacity. Then, 1C constant current and constant voltage were charged to 4.2V, and after being placed in an environment of -20 ° C for 12 hours, a constant current of 0.3 C was discharged to 3.0 V, and the discharge capacity was recorded.

Low-temperature discharge efficiency value at -20 ° C = 0.3 C discharge capacity (-20 ° C) / 1 C discharge capacity (25 ° C) × 100%.

Example 2

As shown in Table 1, except that 0.5% of trimethylsilyl methanesulfonate was changed to 0.5% of trimethylsilylethanesulfonate in the preparation of the electrolytic solution, the same as in Example 1, the test was carried out. The obtained high temperature cycle performance, high temperature storage performance and low temperature performance data are shown in Table 2.

Example 3

As shown in Table 1, except that 0.5% of trimethylsilyl methanesulfonate was changed to 0.5% of trimethylsilylpropanesulfonate in the preparation of the electrolytic solution, the same as in Example 1, the test was carried out. The obtained high temperature cycle performance, high temperature storage performance and low temperature performance data are shown in Table 2.

Example 4

As shown in Table 1, except that 1% of vinylene carbonate (VC) was replaced with 1% of fluoroethylene carbonate (FEC) in the preparation of the electrolytic solution, the same high temperature as that of Example 1 was obtained. The data of cycle performance, high temperature storage performance and low temperature performance are shown in Table 2.

Example 5

As shown in Table 1, except that 1% of vinylene carbonate (VC) was replaced with 1% ethylene carbonate (VEC) in the preparation of the electrolytic solution, the same high temperature as that of Example 1 was tested. The data of cycle performance, high temperature storage performance and low temperature performance are shown in Table 2.

Comparative example 1

As shown in Table 1, except for the absence of the addition of vinylene carbonate (VC) in the preparation of the electrolytic solution, as in the case of Example 1, the data of the high-temperature cycle performance, the high-temperature storage property and the low-temperature property obtained by the test are shown in Table 2.

Comparative example 2

As shown in Table 1, except for the absence of the addition of trimethylsilyl methanesulfonate in the preparation of the electrolyte, the same as in Example 1, the high temperature cycle performance, high temperature storage performance and low temperature performance of the test are shown in Table 2. .

Comparative example 3

As shown in Table 1, except for the absence of the addition of trimethylsilyl methanesulfonate in the preparation of the electrolyte, the same as in Example 5, the high temperature cycle performance, high temperature storage performance and low temperature performance of the test are shown in Table 2. .

Comparative example 4

As shown in Table 1, except for the absence of the addition of trimethylsilyl methanesulfonate in the preparation of the electrolyte, the same as in Example 4, the high temperature cycle performance, high temperature storage performance and low temperature performance of the test are shown in Table 2. .

Comparative Example 5

As shown in Table 1, except for the absence of the addition of trimethylsilyl methanesulfonate and vinylene carbonate (VC) in the preparation of the electrolytic solution, the high-temperature cycle performance and high-temperature storage properties obtained in the same manner as in Example 1 were tested. See Table 2 for data on low temperature performance.

Table 1

Table 2

By comparing with Comparative Example 1 - Comparative Example 5, the addition of additive A alone can improve the low-temperature discharge performance of the battery, but the high-temperature storage and cycle performance of the battery is poor, and the addition of the additive B alone can improve the cycle and high-temperature storage performance of the battery, but the battery High-temperature storage produces severe gas and low-temperature discharge performance (except FEC). When the additive A and the additive B are used at the same time, since the two can form a composite passivation film, a synergistic effect is produced, and the high-temperature storage, cycle and low-temperature discharge performance of the battery can be simultaneously improved. At the same time, it can be seen that as the number of carbon atoms in the additive A increases from 1 to 3, the low-temperature discharge performance tends to be poor, which is mainly due to the increase in the number of carbon atoms, and the formation of the passivation film is not conducive to the passage of lithium ions. Increased, resulting in increased internal resistance of the battery.

Example 6

As shown in Table 3, the test was the same as in Example 1 except that 0.5% of trimethylsilyl methanesulfonate was changed to 0.1% of trimethylsilyl methanesulfonate in the preparation of the electrolytic solution. The obtained high temperature cycle performance, high temperature storage performance and low temperature performance data are shown in Table 4.

Example 7

As shown in Table 3, the test was the same as in Example 1 except that 0.5% of trimethylsilyl methanesulfonate was changed to 1% of trimethylsilyl methanesulfonate in the preparation of the electrolytic solution. The obtained high temperature cycle performance, high temperature storage performance and low temperature performance data are shown in Table 4.

Example 8

As shown in Table 3, the test was the same as in Example 1 except that 0.5% of trimethylsilyl methanesulfonate was changed to 2% of trimethylsilyl methanesulfonate in the preparation of the electrolytic solution. The obtained high temperature cycle performance, high temperature storage performance and low temperature performance data are shown in Table 4.

Example 9

As shown in Table 3, except that 1% of vinylene carbonate (VC) was replaced with 0.5% of vinylene carbonate in the preparation of the electrolytic solution, the same high-temperature cycle performance and high temperature were obtained as in Example 1. The storage performance and low temperature performance data are shown in Table 4.

Example 10

As shown in Table 3, except for the preparation of the electrolyte, 1% of vinylene carbonate (VC) was replaced by 2%. Other than Example 1, the data of the high temperature cycle performance, high temperature storage performance and low temperature performance of the test were as shown in Table 4 except for the vinylene carbonate (VC).

Example 11

As shown in Table 3, the high temperature cycle was tested in the same manner as in Example 1 except that 1% of vinylene carbonate (VC) was changed to 3% of vinylene carbonate (VC) in the preparation of the electrolytic solution. The performance, high temperature storage performance and low temperature performance data are shown in Table 4.

Comparative Example 6

As shown in Table 3, the test was the same as in Example 1 except that 0.5% of trimethylsilyl methanesulfonate was changed to 3% of trimethylsilyl methanesulfonate in the preparation of the electrolytic solution. The obtained high temperature cycle performance, high temperature storage performance and low temperature performance data are shown in Table 4.

Comparative Example 7

As shown in Table 3, the high temperature cycle was tested in the same manner as in Example 1 except that 1% of vinylene carbonate (VC) was replaced with 5% of vinylene carbonate (VC) in the preparation of the electrolytic solution. The performance, high temperature storage performance and low temperature performance data are shown in Table 4.

Comparative Example 8

As shown in Table 3, except for the preparation of the electrolyte, 0.5% of trimethylsilyl methanesulfonate was changed to 3% of trimethylsilyl methanesulfonate and 1% of vinylene carbonate (VC). The data of high temperature cycle performance, high temperature storage performance and low temperature performance which were tested in the same manner as in Example 1 except for 5% vinylene carbonate (VC) are shown in Table 4.

table 3

Table 4

By comparison with Comparative Example 6 - Comparative Example 8, when the content of the additive A was in the range of 0.1% to 2%, and the content of the additive B was in the range of 0.5% to 3%, the cycle performance, high-temperature storage performance and low-temperature discharge performance of the battery were very high. Excellent. However, when the content of the additive A exceeds 2% or the content of the additive B exceeds 3%, the cycle performance, high-temperature storage performance, and low-temperature discharge performance of the battery are remarkably deteriorated.

Example 12

As shown in Table 5, except that 1% of 1,3-propane sultone (1,3-PS) based on the total mass of the electrolyte was additionally added to the preparation of the electrolytic solution, the same as in Example 1, the test was carried out. The obtained high temperature cycle performance, high temperature storage performance and low temperature performance data are shown in Table 6.

Example 13

As shown in Table 5, except for the addition of 1% of 1,4-butane sultone (BS) based on the total mass of the electrolyte in the preparation of the electrolytic solution, the same high temperature as in Example 1 was obtained. The data of cycle performance, high temperature storage performance and low temperature performance are shown in Table 6.

Example 14

As shown in Table 5, the high temperature cycle was tested in the same manner as in Example 1 except that 1% of 1,3-propene sultone (PST) based on the total mass of the electrolyte was additionally added to the preparation of the electrolytic solution. The performance, high temperature storage performance and low temperature performance data are shown in Table 6.

Comparative Example 9

As shown in Table 5, except for the preparation of the electrolyte, 0.5% trimethylsilyl methanesulfonate was not added and 1% of 1,3-propane sultone was added in addition to the total mass of the electrolyte (1, 3). Other than Example 1, the data of the high temperature cycle performance, high temperature storage performance and low temperature performance obtained in the test were as shown in Table 6.

Comparative Example 10

As shown in Table 5, except for the preparation of the electrolyte, 0.5% trimethylsilyl methanesulfonate was not added and 1% of 1,4-butane sultone (BS) was added in addition to the total mass of the electrolyte. Other than the same as in Example 1, the data of the high temperature cycle performance, high temperature storage performance and low temperature performance obtained by the test are shown in Table 6.

Comparative Example 11

As shown in Table 5, except for the preparation of the electrolyte, 0.5% trimethylsilyl methanesulfonate was not added and 1% of 1,3-propene sultone (PST) was added in addition to the total mass of the electrolyte. In the same manner as in Example 1, the data of the high temperature cycle performance, high temperature storage performance and low temperature performance obtained by the test are shown in Table 6.

table 5

Table 6

By comparing with Comparative Example 9 - Comparative Example 11, the addition of trimethylsilyl methanesulfonate to the combination of VC and other additives can further improve the cycle and high-temperature storage performance of the battery.

The above is a further detailed description of the present invention in connection with the specific embodiments, and the specific embodiments of the present invention are not limited to the description. It will be apparent to those skilled in the art that the present invention may be made without departing from the spirit and scope of the invention.

Claims (9)

1. A lithium ion battery nonaqueous electrolyte comprising a nonaqueous organic solvent, a lithium salt and an additive, characterized in that the additive comprises an additive A and an additive B, the additive A being selected from the group consisting of the compound of the formula 1, wherein R is selected From a hydrocarbon group having a carbon number of 1-3, m is a natural integer of 1-2,

   

   The content of the additive A is 0.1% to 2% with respect to the total mass of the nonaqueous electrolyte of the lithium ion battery; the additive B is selected from the group consisting of vinylene carbonate, ethylene carbonate, and fluoroethylene carbonate. In at least one, the content of the additive B is 0.5% to 3% with respect to the total mass of the nonaqueous electrolyte of the lithium ion battery.
2. The nonaqueous electrolyte for a lithium ion battery according to claim 1, wherein R is selected from a methyl group, an ethyl group or a propyl group.
3. The lithium ion battery nonaqueous electrolyte according to claim 1, wherein m is 1.
4. The nonaqueous electrolyte for a lithium ion battery according to claim 1, wherein the additive A is selected from the group consisting of trimethylsilyl methanesulfonate, trimethylsilylethanesulfonate, and trimethylsilyl group. At least one of propane sulfonates.
5. The nonaqueous electrolyte for a lithium ion battery according to claim 1, wherein the nonaqueous organic solvent is a mixture of a cyclic carbonate and a chain carbonate, and the cyclic carbonate is selected from the group consisting of ethylene carbonate, One or more of propylene carbonate and butylene carbonate, the chain carbonate being selected from one or two of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and methyl propyl carbonate More than one species.
6. The nonaqueous electrolyte for a lithium ion battery according to claim 1, wherein the lithium salt is selected from the group consisting of LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiN(SO ₂ CF ₃ ) ₂ , LiN (SO _{2 )} One or more of C ₂ F ₅ ) ₂ , LiC(SO ₂ CF ₃ ) ₃ and LiN(SO ₂ F) ₂ .
7. The nonaqueous electrolyte for a lithium ion battery according to claim 1, wherein the additive further comprises 1,3-propane sultone, 1,4-butane sultone, and 1,3-propene sulfonate. One or more of the esters.
8. A lithium ion battery comprising a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode, The lithium ion battery nonaqueous electrolyte according to any one of claims 1 to 7 is further included.
9. The lithium ion battery according to claim 8, wherein said positive electrode is selected from _{LiCoO 2, LiNiO 2, LiMn 2} O 4, LiCo 1-y M y O 2, LiNi 1-y M y O 2, LiMn _{One or more of 2-y} M _y O ₄ and LiNi _x Co _y Mn _z M _1-xyz O ₂ , wherein M is selected from the group consisting of Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, One or more of Sn, B, Ga, Cr, Sr, V, and Ti, and 0 ≤ y ≤ 1, 0 ≤ x ≤ 1, 0 ≤ z ≤ 1, x + y + z ≤ 1.