Electrolyte, preparation method and application thereof

Abstract

This invention discloses an electrolyte, its preparation method, and its application. The electrolyte comprises the following components: a lithium salt, a gas-suppressing additive, a solvent, and a negative electrode film-forming additive; the gas-suppressing additive includes at least one of phenyl vinyl sulfone and a disilane compound containing an olefin group. This invention proposes an electrolyte for reducing gas production in lithium-ion batteries, using at least one of a disilane compound containing an olefin group and phenyl vinyl sulfone as additives in the electrolyte, resulting in an electrolyte that effectively suppresses gas production in the battery.

Description

Technical Field

[0001] This invention belongs to the field of ion battery technology, specifically relating to an electrolyte, its preparation method, and its application. Background Technology

[0002] The rapid development of portable devices, electric vehicles, and energy storage facilities has placed higher demands on the cost, charging rate, lifespan, and safety of lithium-ion batteries. However, lithium-ion batteries generate gas during cycling and storage, causing battery volume expansion, electrode / separator misalignment, and increased battery polarization, which are significant causes of battery life degradation and even safety issues. Common additives to suppress gas generation include nitrile and sulfonate esters. Sulfonate esters, such as PS, can preferentially reduce on the negative electrode surface before EC to form a chemically and electrochemically stable SEI film, effectively inhibiting further decomposition of electrolyte components. The SEI component formed with the participation of PS reduction products accelerates the degradation of Li-ion batteries to some extent. + The lithium intercalation kinetics on the graphite surface effectively suppresses high-temperature side reactions and reduces gas production, but it leads to increased battery internal resistance. PS, as the additive with the best effect on suppressing battery gas production in the electrolyte, is subject to regulation due to its carcinogenicity.

[0003] Therefore, there is a need to provide an electrolyte that reduces gas production in lithium-ion batteries. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes an electrolyte for reducing gas production in lithium-ion batteries, which uses at least one of a disilane compound containing an olefin group and a phenyl vinyl sulfone as an additive to the electrolyte, and the resulting electrolyte can effectively suppress gas production in the battery.

[0005] The present invention also proposes a method for preparing the electrolyte.

[0006] The present invention also provides a lithium-ion battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte.

[0007] According to one aspect of the present invention, an electrolyte is provided, comprising the following components: lithium salt, gas-inhibiting additive, solvent, and negative electrode film-forming additive;

[0008] The gas-suppressing additive includes at least one of phenyl vinyl sulfone and a disilane compound containing an olefin group as shown in Formula I;

[0009]

[0010] Among them, R1 to R4 are independently selected from hydrogen atoms, halogen atoms, hydrocarbon groups with 1 to 10 carbon atoms having heteroatoms, or silane-hydrogen groups with 1 to 10 silicon atoms having substituents.

[0011] R1 to R4 can bond together to form a ring.

[0012] n and m can be the same or different, and the independent ones are 1 to 6.

[0013] The embodiments of the first aspect of the present invention have at least the following beneficial effects:

[0014] Compared with existing technologies, this invention, by using disilane additives containing phenyl vinyl sulfone and olefin groups, can effectively suppress battery gas generation without affecting battery performance stability. This is because the olefin-containing disilanes can participate in the formation of silane polymers with high lithium-ion conductivity in both the positive and negative electrodes. Simultaneously, the olefin-based silicon groups can remove active oxygen and trace water from the electrolyte, significantly suppressing battery gas generation and impedance growth during high-temperature storage. Phenyl vinyl sulfone has a wide electrochemical window; its presence alters the reaction pathways of electroreduction and subsequent oxidation, contributing to the construction of a stable SEI interface and reducing gas generation during SEI dissolution and regeneration. Both of these substances are non-carcinogenic and have high safety profiles.

[0015] In some embodiments of the present invention, the electrolyte comprises the following components in parts by weight: 12.5 to 15 parts of lithium salt, 3 parts of gas-inhibiting additive, 77 to 86 parts of solvent, and 5 parts of negative electrode film-forming additive.

[0016] The gas-inhibiting additive is, by weight, 2 parts of divinyltetramethyldisilane and 1 part of phenylvinyl sulfone.

[0017] In some embodiments of the present invention, the electrolyte comprises the following components in parts by weight: 12.5 to 15 parts of lithium salt, 3 parts of gas-inhibiting additive, 77 to 86 parts of solvent, and 0.5 to 5 parts of negative electrode film-forming additive.

[0018] In some embodiments of the present invention, the gas-suppressing additive is a phenyl vinyl sulfone and a disilane compound containing an olefin group.

[0019] In some embodiments of the present invention, the lithium salt includes lithium hexafluorophosphate.

[0020] In some embodiments of the present invention, the solvent includes at least one of cyclic carbonates and linear carbonates.

[0021] In some embodiments of the present invention, the cyclic carbonate includes at least one of ethylene carbonate and propylene carbonate.

[0022] In some embodiments of the present invention, the linear carbonate includes at least one of dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.

[0023] In some embodiments of the present invention, the negative electrode film-forming additive includes at least one of fluoroethylene carbonate and vinylene carbonate.

[0024] In some embodiments of the present invention, the lithium salt concentration is 1.0 to 1.5 mol / L.

[0025] In some embodiments of the present invention, the lithium salt concentration is 1.3 to 1.5 mol / L.

[0026] According to two aspects of the present invention, a method for preparing the electrolyte is provided, comprising the following steps:

[0027] Lithium salt is dissolved in an organic solvent to obtain a mixed solution. A negative electrode film-forming additive and a gas-inhibiting additive are added to the mixed solution to obtain the electrolyte.

[0028] According to two aspects of the present invention, a lithium-ion battery is provided, comprising a positive electrode, a negative electrode, a separator, and an electrolyte. Detailed Implementation

[0029] The terms "preferred," "more preferably," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0030] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of the present invention.

[0032] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0033] Example 1

[0034] This embodiment provides an electrolyte and its preparation method, specifically:

[0035] An electrolyte comprises the following components in parts by weight:

[0036] The lithium salt is lithium hexafluorophosphate: 12.5 parts;

[0037] The gas-producing inhibitor is diallyltetramethyldisilane (CAS No.: 1450-29-9): 1 part;

[0038] The organic solvent is 81.5 parts, and the mass ratio of propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) is 1:1:2:1.

[0039] The negative electrode film-forming additive is fluoroethylene carbonate (FEC): 5 parts;

[0040] The method for preparing the above electrolyte includes the following steps:

[0041] S1. Mix propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a weight ratio of 1:1:2:1 to obtain an organic solvent. Dissolve the lithium salt in the organic solvent to obtain a mixed solution.

[0042] S2. Add FEC additive and divinyltetramethyldisilane additive one by one to the mixed solution to obtain electrolyte 1.

[0043] Example 2

[0044] This embodiment provides an electrolyte and its preparation method, specifically:

[0045] An electrolyte comprises the following components in parts by weight:

[0046] The lithium salt is lithium hexafluorophosphate: 12.5 parts;

[0047] The gas-producing inhibitor is divinyltetramethyldisilane: 2 parts;

[0048] The organic solvent is 80.5 parts, with a mass ratio of propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) of 1:1:2:1.

[0049] The negative electrode film-forming additive is fluoroethylene carbonate (FEC): 5 parts;

[0050] The method for preparing the above electrolyte includes the following steps:

[0051] S1. Mix propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a weight ratio of 1:1:2:1 to obtain an organic solvent, and dissolve the lithium salt in the organic solvent to obtain a mixed solution.

[0052] S2. Add FEC additive and divinyltetramethyldisilane additive one by one to the mixed solution to obtain electrolyte 2.

[0053] Example 3

[0054] This embodiment provides an electrolyte and its preparation method, specifically:

[0055] An electrolyte comprises the following components in parts by weight:

[0056] The lithium salt is lithium hexafluorophosphate: 12.5 parts;

[0057] The gas-inhibiting additive is phenyl vinyl sulfone (CAS No.: 5535-48-8): 1 part;

[0058] The organic solvent is 81.5 parts, with a mass ratio of propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) of 1:1:2:1.

[0059] The negative electrode film-forming additive is fluoroethylene carbonate (FEC): 5 parts;

[0060] The method for preparing the above electrolyte includes the following steps:

[0061] S1. Mix propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a weight ratio of 1:1:2:1 to obtain an organic solvent, and dissolve the lithium salt in the organic solvent to obtain a mixed solution.

[0062] S2. Add FEC additive and phenyl vinyl sulfone additive one by one to the mixed solution to obtain electrolyte 3.

[0063] Example 4

[0064] This embodiment provides an electrolyte and its preparation method, specifically:

[0065] An electrolyte comprises the following components in parts by weight:

[0066] The lithium salt is lithium hexafluorophosphate: 12.5 parts, concentration: 1.0 mol / L;

[0067] The gas-inhibiting additive is phenyl vinyl sulfone: 2 parts;

[0068] The organic solvent content is 80.5 parts. The mass ratio of propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) is 1:1:2:1.

[0069] The negative electrode film-forming additive is fluoroethylene carbonate (FEC): 5 parts;

[0070] The method for preparing the above electrolyte includes the following steps:

[0071] S1. Mix propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a weight ratio of 1:1:2:1 to obtain an organic solvent, and dissolve the lithium salt in the organic solvent to obtain a mixed solution.

[0072] S2. Add FEC additive and phenyl vinyl sulfone additive one by one to the mixed solution to obtain electrolyte 4.

[0073] Example 5

[0074] This embodiment provides an electrolyte and its preparation method, specifically:

[0075] An electrolyte comprises the following components in parts by weight:

[0076] The lithium salt is lithium hexafluorophosphate: 12.5 parts;

[0077] The gas-inhibiting additive is 1 part of divinyltetramethyldisilane and 1 part of phenylvinyl sulfone.

[0078] The organic solvent is 80.5 parts, with a mass ratio of propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) of 1:1:2:1.

[0079] The negative electrode film-forming additive is fluoroethylene carbonate (FEC): 5 parts;

[0080] The method for preparing the above electrolyte includes the following steps:

[0081] S1. Mix propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a weight ratio of 1:1:2:1 to obtain an organic solvent, and dissolve the lithium salt in the organic solvent to obtain a mixed solution.

[0082] S2. Add FEC additive, divinyltetramethyldisilane and phenylvinylsulfone additive one by one to the mixed solution to obtain electrolyte 5.

[0083] Example 6

[0084] This embodiment provides an electrolyte and its preparation method, specifically:

[0085] An electrolyte comprises the following components in parts by weight:

[0086] The lithium salt is lithium hexafluorophosphate: 12.5 parts;

[0087] The gas-inhibiting additive is 2 parts of divinyltetramethyldisilane and 1 part of phenylvinyl sulfone;

[0088] The organic solvent is 79.5 parts, with a mass ratio of propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) of 1:1:2:1.

[0089] The negative electrode film-forming additive is fluoroethylene carbonate (FEC): 5 parts;

[0090] The method for preparing the above electrolyte includes the following steps:

[0091] S1. Mix propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a weight ratio of 1:1:2:1 to obtain an organic solvent, and dissolve the lithium salt in the organic solvent to obtain a mixed solution.

[0092] S2. Add FEC additive, divinyltetramethyldisilane, and phenylvinylsulfone additive one by one to the mixed solution to obtain electrolyte 6.

[0093] Example 7

[0094] This embodiment provides an electrolyte and its preparation method, specifically:

[0095] An electrolyte comprises the following components in parts by weight:

[0096] The lithium salt is lithium hexafluorophosphate: 12.5 parts;

[0097] The gas-inhibiting additive is 1 part of divinyltetramethyldisilane and 2 parts of phenylvinyl sulfone.

[0098] The organic solvent is 79.5 parts, with a mass ratio of propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) of 1:1:2:1.

[0099] The negative electrode film-forming additive is fluoroethylene carbonate (FEC): 5 parts;

[0100] The method for preparing the above electrolyte includes the following steps:

[0101] S1. Mix propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a weight ratio of 1:1:2:1 to obtain an organic solvent, and dissolve the lithium salt in the organic solvent to obtain a mixed solution.

[0102] S2. Add FEC additive, divinyltetramethyldisilane, and phenylvinylsulfone additive one by one to the mixed solution to obtain electrolyte 7.

[0103] Example 8

[0104] This embodiment provides an electrolyte and its preparation method, specifically:

[0105] An electrolyte comprises the following components in parts by weight:

[0106] The lithium salt is lithium hexafluorophosphate: 12.5 parts;

[0107] The gas-inhibiting additive is diallyltetramethyldisilane (CAS: 17955-81-6): 2 parts, phenylvinyl sulfone 1 part;

[0108] The organic solvent is 79.5 parts, with a mass ratio of propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) of 1:1:2:1.

[0109] The negative electrode film-forming additive is fluoroethylene carbonate (FEC): 5 parts;

[0110] The method for preparing the above electrolyte includes the following steps:

[0111] S1. Mix propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a weight ratio of 1:1:2:1 to obtain an organic solvent, and dissolve the lithium salt in the organic solvent to obtain a mixed solution.

[0112] S2. Add FEC additive, diallyltetramethyldisilane, and phenylvinyl sulfone additive one by one to the mixed solution to obtain electrolyte 8.

[0113] Comparative Example 1

[0114] This comparative example provides an electrolyte and its preparation method. The difference between this comparative example and the embodiments is that it does not include gas-inhibiting additives. Specifically:

[0115] An electrolyte comprises the following components in parts by weight:

[0116] The lithium salt is lithium hexafluorophosphate: 12.5 parts;

[0117] The organic solvent is 74-83 parts, with a mass ratio of propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) of 1:1:2:1.

[0118] The negative electrode film-forming additive is fluoroethylene carbonate (FEC): 5 parts;

[0119] The method for preparing the above electrolyte includes the following steps:

[0120] S1. Mix propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a weight ratio of 1:1:2:1 to obtain an organic solvent, and dissolve the lithium salt in the organic solvent to obtain a mixed solution.

[0121] S2. Add the FEC additive to the mixed solution to obtain electrolyte 9.

[0122] Comparative Example 2

[0123] This comparative example provides an electrolyte and its preparation method. The difference between this comparative example and the embodiment is that the gas-suppressing additive is an organosilicone nitrile, the structural formula of which is shown in Formula II:

[0124]

[0125] Where n = 1; where X is F, Y is CH3, and Z is CH3;

[0126] Specifically:

[0127] An electrolyte comprises the following components in parts by weight:

[0128] The lithium salt is lithium hexafluorophosphate: 12.5 parts;

[0129] The gas-inhibiting additive is organosilicone nitrile: 2 parts;

[0130] The organic solvent is 80.5 parts, with a mass ratio of propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) of 1:1:2:1.

[0131] The negative electrode film-forming additive is fluoroethylene carbonate (FEC): 5 parts;

[0132] The method for preparing the above electrolyte includes the following steps:

[0133] S1. Mix propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a weight ratio of 1:1:2:1 to obtain an organic solvent, and dissolve the lithium salt in the organic solvent to obtain a mixed solution.

[0134] S2. Add FEC additive and organosilicone nitrile to the mixed solution to obtain electrolyte 10.

[0135] Comparative Example 3

[0136] This comparative example provides an electrolyte and its preparation method. The difference between this comparative example and the previous examples is that the gas-inhibiting additive is divinyl sulfone, specifically:

[0137] An electrolyte comprises the following components in parts by weight:

[0138] The lithium salt is lithium hexafluorophosphate: 12.5 parts;

[0139] The gas-producing inhibitor is divinyl sulfone: 2 parts;

[0140] The organic solvent is 80.5 parts, with a mass ratio of propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) of 1:1:2:1.

[0141] The negative electrode film-forming additive is fluoroethylene carbonate (FEC): 5 parts;

[0142] The method for preparing the above electrolyte includes the following steps:

[0143] S1. Mix propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a weight ratio of 1:1:2:1 to obtain an organic solvent, and dissolve the lithium salt in the organic solvent to obtain a mixed solution.

[0144] S2. Add FEC additive and divinyl sulfone to the mixed solution to obtain electrolyte 11.

[0145] Test case

[0146] This application example provides a lithium-ion secondary battery, specifically:

[0147] Positive electrode: Ternary NCM622 active material (13-15μm aluminum foil), binder: (polyvinylidene fluoride, PVDF) and conductive agent: (SuperP);

[0148] Negative electrode: artificial graphite, 6-8μm copper foil, binder: (styrene-butadiene rubber, SBR) and conductive agent: (SuperP);

[0149] Battery size: 18650 cylindrical battery.

[0150] In the cycle performance test: the voltage range was 2.8 to 4.25V; after continuous storage at 60°C for 10 days, the gas production was measured. The gas production between the examples and the comparative examples is shown in Table 1; after 800 cycles at room temperature 1°C, the capacity retention of the examples and the comparative examples is shown in Table 1.

[0151] Table 1. Gas production and capacity retention rates of the examples and comparative examples.

[0152] Gas production (mg / L) Capacity retention rate (%) Example 1 0.38 83.9 Example 2 0.32 84.6 Example 3 0.44 80.3 Example 4 0.39 81.5 Example 5 0.23 82.2 Example 6 0.13 83.7 Example 7 0.20 80.4 Example 8 0.25 76.3 Comparative Example 1 0.86 78.9 Comparative Example 2 0.38 77.3 Comparative Example 3 0.46 78.32

[0153] As can be seen from the above examples and comparative examples, the battery made with the olefin-based disilane and phenyl vinyl sulfone additives of the present invention exhibits significantly reduced gas production, and its capacity retention rate after 800 cycles at room temperature is higher than that of the conventional battery in Comparative Example 1. This demonstrates that the gas-suppressing additive significantly improves the stability and safety of the ternary NCM622 battery. The gas-suppressing additives in Comparative Example 2 were organosilicon nitrile, and in Comparative Example 3 were divinyl sulfone; neither of these additives showed as effective a gas-suppressing effect as the simultaneous addition of divinyltetramethyldisilane and phenyl vinyl sulfone in the present invention.

[0154] This invention is not limited to the embodiments described above. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this invention. Furthermore, unless otherwise specified, the embodiments of this invention and the features thereof can be combined with each other.

Claims

1. An electrolyte, characterized in that, The electrolyte is composed of the following components in parts by weight: 12.5-15 parts lithium salt, 1-3 parts gas-inhibiting additive, 77-86 parts solvent, and 0.5-5 parts negative electrode film-forming additive. The gas-inhibiting additive consists of 1 part phenyl vinyl sulfone and 2 parts divinyltetramethyldisilane.

2. The electrolyte according to claim 1, characterized in that, The lithium salt includes lithium hexafluorophosphate.

3. The electrolyte according to claim 1, characterized in that, The solvent includes at least one of cyclic carbonates and linear carbonates.

4. The electrolyte according to claim 3, characterized in that, The cyclic carbonates include at least one of ethylene carbonate and propylene carbonate.

5. The electrolyte according to claim 3, characterized in that, The linear carbonate includes at least one of dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.

6. The electrolyte according to claim 1, characterized in that, The negative electrode film-forming additive includes at least one of fluoroethylene carbonate and vinylene carbonate.

7. The electrolyte according to claim 1, characterized in that, The concentration of the lithium salt is 1.0~1.5 mol / L.

8. A method for preparing an electrolyte as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Lithium salt is dissolved in an organic solvent to obtain a mixed solution. A negative electrode film-forming additive and a gas-inhibiting additive are added to the mixed solution to obtain the electrolyte.

9. A lithium-ion battery, characterized in that, It includes a positive electrode, a negative electrode, a separator, and an electrolyte as described in any one of claims 1 to 7.

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