Electrolyte and preparation method and application thereof

Abstract

The invention discloses an electrolyte and a preparation method and application thereof. The electrolyte comprises the following components: a lithium salt, a gas production inhibition additive, a solvent and a negative electrode film-forming additive, the gas production inhibiting additive comprises at least one of phenyl vinyl sulfone and a disilane compound containing alkylene. According to the electrolyte capable of reducing gas production of the lithium ion battery, provided by the invention, at least one of the alkylene-containing disilane compound and the phenyl vinyl sulfone is used as the additive to be added into the electrolyte, and the prepared electrolyte can effectively inhibit gas production of the battery.

Description

Technical Field

[0001] The invention belongs to the technical field of ion batteries, and in particular relates to an electrolyte and a preparation method and application thereof. Background Art

[0002] The rapid development of portable devices, electric vehicles, and energy storage facilities has put forward higher requirements on the cost, charging rate, service life, and safety of lithium-ion batteries. However, lithium-ion batteries produce gas during the cycle and storage process, which causes battery volume expansion, pole piece / diaphragm misalignment, and increased battery polarization, which is an important reason for the battery life degradation and even safety problems. Common gas production inhibitory additives include nitriles and sulfonates. Sulfonates such as PS can be reduced on the negative electrode surface before EC to form a chemically and electrochemically stable SEI film, which effectively inhibits the further decomposition of electrolyte components. The SEI components formed with the participation of PS reduction products accelerate the Li + The lithium insertion dynamics on the graphite surface effectively inhibits high-temperature side reactions and reduces gas production, but it will increase the internal resistance of the battery. PS is the most effective additive in the electrolyte to inhibit battery gas production, but it is controlled due to its carcinogenicity.

[0003] Therefore, it is necessary to provide an electrolyte that reduces gas production in lithium-ion batteries. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides 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 an additive added to the electrolyte, and the prepared electrolyte can effectively inhibit gas production in the battery.

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

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

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

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

[0009]

[0010] wherein R1 to R4 are independently selected from a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 10 carbon atoms and having a heteroatom, or a silyl group having 1 to 10 silicon atoms and having a substituent,

[0011] R1 to R4 may be bonded to each other to form a ring.

[0012] n and m may be the same or different, and are independently 1 to 6.

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

[0014] Compared with the prior art, the present invention uses disilane additives containing phenyl vinyl sulfone and olefin groups, which can effectively inhibit the gas production of the battery without affecting the stability of the battery performance. This is because the disilane containing olefin groups can participate in the film formation of positive and negative electrodes to form silane polymers with high lithium ion conductivity. At the same time, the olefin silicon group can also remove active oxygen and trace water in the electrolyte, which can significantly inhibit the gas production of the battery and the impedance growth during high-temperature storage. Phenyl vinyl sulfone has a wide electrochemical window. Its presence changes the reaction pathway of the electroreduction reaction and the subsequent oxidation reaction, which helps to build a stable SEI interface and reduce the gas production of SEI dissolution and regeneration. Both of these substances are non-carcinogenic and have high safety.

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

[0016] The gas generation inhibiting additive is calculated by weight as follows: 2 parts of divinyltetramethyldisilane and 1 part of phenyl vinyl 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 a gas generation inhibiting additive, 77 to 86 parts of a solvent, and 0.5 to 5 parts of a negative electrode film-forming additive.

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

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

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

[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 concentration of the lithium salt is 1.0 to 1.5 mol / L.

[0025] In some embodiments of the present invention, the concentration of the lithium salt 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] The lithium salt is dissolved in an organic solvent to obtain a mixed solution, and a negative electrode film-forming additive and a gas generation inhibiting additive are added into 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 the above-mentioned electrolyte. DETAILED DESCRIPTION

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

[0030] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of the present invention.

[0032] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0033] Example 1

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

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

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

[0037] The gas generation inhibitor is divinyltetramethyldisilane (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 comprises the following steps:

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

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

[0043] Example 2

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

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

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

[0047] The gas generation suppressing additive is divinyltetramethyldisilane: 2 parts;

[0048] The organic solvent is: 80.5 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;

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

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

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

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

[0053] Example 3

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

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

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

[0057] The gas generation inhibitor additive is phenyl vinyl sulfone (CAS number: 5535-48-8): 1 part;

[0058] 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;

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

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

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

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

[0063] Example 4

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

[0065] An electrolyte comprising 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 generation suppressing additive is phenyl vinyl sulfone: 2 parts;

[0068] The organic solvent 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 comprises the following steps:

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

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

[0073] Example 5

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

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

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

[0077] The gas generation inhibiting additive is 1 part of divinyltetramethyldisilane and 1 part of phenyl vinyl sulfone;

[0078] The organic solvent is: 80.5 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;

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

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

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

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

[0083] Example 6

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

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

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

[0087] The gas generation suppressing additive is 2 parts of divinyltetramethyldisilane and 1 part of phenyl vinyl sulfone;

[0088] The organic solvent is 79.5 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;

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

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

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

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

[0093] Example 7

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

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

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

[0097] The gas generation inhibiting additive is 1 part of divinyltetramethyldisilane and 2 parts of phenyl vinyl sulfone;

[0098] The organic solvent is 79.5 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;

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

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

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

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

[0103] Example 8

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

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

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

[0107] The gas generation inhibitor additive is 2 parts of dipropylene tetramethyl disilane (cas: 17955-81-6) and 1 part of phenyl vinyl sulfone;

[0108] The organic solvent is 79.5 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;

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

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

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

[0112] S2. Add FEC additive, dipropylene tetramethyl disilane, and phenyl vinyl sulfone additive to the mixed solution one by one to obtain electrolyte 8.

[0113] Comparative Example 1

[0114] This comparative example provides an electrolyte and a preparation method thereof. The difference between this comparative example and the embodiment is that no gas generation inhibitor additive is included, specifically:

[0115] An electrolyte comprising 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, and the mass ratio of propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) is 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 comprises the following steps:

[0120] S1. Propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) are mixed in a weight ratio of 1:1:2:1 to obtain an organic solvent, and a lithium salt is dissolved 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 a preparation method thereof. The difference between this comparative example and the embodiment is that the gas generation inhibiting additive is organic silicon nitrile, and the structural formula of organic silicon nitrile is shown in Formula II:

[0124]

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

[0126] Specifically:

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

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

[0129] The gas generation inhibiting additive is 2 parts of organic silicon nitrile;

[0130] The organic solvent is: 80.5 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;

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

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

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

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

[0135] Comparative Example 3

[0136] This comparative example provides an electrolyte and a preparation method thereof. The difference between this comparative example and the embodiment is that the gas generation inhibitory additive is divinyl sulfone, specifically:

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

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

[0139] The gas generation inhibiting additive is divinyl sulfone: 2 parts;

[0140] The organic solvent is: 80.5 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;

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

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

[0143] S1. Propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) are mixed in a weight ratio of 1:1:2:1 to obtain an organic solvent, and a lithium salt is dissolved 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 example

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

[0147] Positive electrode: ternary NCM622 active material, (13-15 μm 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 test of cycle performance: the voltage range is 2.8 to 4.25 V; the gas production is detected after continuous storage at 60°C for 10 days, and the gas production between the embodiment and the comparative example is shown in Table 1; after 800 cycles at room temperature 1C, the capacity retention rate of the embodiment and the comparative example is shown in Table 1.

[0151] Table 1 Gas production and capacity retention rate of the embodiments 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] From the above examples and comparative examples, it can be seen that the battery made of olefin-containing disilane and phenyl vinyl sulfone additives of the present invention has significantly reduced gas production, and the capacity retention rate of 800 cycles at room temperature is higher than that of the conventional battery in comparative example 1. It can be seen that the gas production inhibitor additive significantly improves the stability and safety of the ternary NCM622 battery. The gas production inhibitor additive in comparative example 2 is organic silicon nitrile, and the gas production inhibitor additive in comparative example 3 is divinyl sulfone. The inhibitory effect on battery gas production is not as good as the simultaneous addition of divinyltetramethyldisilane and phenyl vinyl sulfone in the present invention.

[0154] The present invention is not limited to the above-mentioned embodiments, and various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. An electrolyte, characterized in that: The invention comprises the following components: a lithium salt, a gas generation inhibiting additive, a solvent and a negative electrode film forming additive; The gas generation inhibiting additive comprises at least one of phenyl vinyl sulfone and a disilane compound containing an olefin group as shown in Formula I; wherein R1 to R4 are independently selected from a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 10 carbon atoms and having a heteroatom, or a silyl group having 1 to 10 silicon atoms and having a substituent, R1 to R4 may be bonded to each other to form a ring. n and m may be the same or different, and are independently 1 to 6.

2. An electrolyte according to claim 1, characterized in that: The electrolyte comprises the following components in parts by weight: 12.5 to 15 parts of lithium salt, 1 to 3 parts of a gas generation inhibiting additive, 77 to 86 parts of a solvent and 0.5 to 5 parts of a negative electrode film-forming additive.

3. An electrolyte according to claim 1, characterized in that: The lithium salt includes lithium hexafluorophosphate.

4. An electrolyte according to claim 1, characterized in that: The solvent includes at least one of a cyclic carbonate and a linear carbonate.

5. An electrolyte according to claim 4, characterized in that: The cyclic carbonate includes at least one of ethylene carbonate and propylene carbonate.

6. An electrolyte according to claim 4, characterized in that: The linear carbonate includes at least one of dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate.

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

8. An electrolyte according to claim 1, characterized in that: The concentration of the lithium salt is 1.0-1.5 mol / L.

9. A method for preparing an electrolyte according to any one of claims 1 to 8, characterized in that: The following steps are involved: The lithium salt is dissolved in an organic solvent to obtain a mixed solution, and a negative electrode film-forming additive and a gas generation inhibiting additive are added into the mixed solution to obtain the electrolyte.

10. A lithium ion battery, characterized in that: The invention comprises a positive electrode, a negative electrode, a separator and an electrolyte as claimed in any one of claims 1 to 8.

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