Sodium-ion battery electrolyte

Abstract

The invention relates to a sodium-ion battery electrolyte, and belongs to the technical field of sodium-ion batteries. The electrolyte comprises sodium salt, a non-aqueous organic solvent, an additive A and an additive B. The additive A comprises a cyclic sulfate compound, and the additive B comprises an alkyl dicarbonate compound. The alkyl dicarbonate compound and the cyclic sulfate compound are combined to be used as the additive and play a synergistic effect, and the sodium-ion battery electrolyte is applied to the sodium-ion battery, so that the cycle performance of the sodium-ion battery can be effectively improved, the high-temperature storage gas production rate of the sodium-ion battery is reduced, and the service life of the sodium-ion battery is prolonged. And the performance of the sodium ion battery is improved.

Description

Technical Field

[0001] The present application relates to the technical field of sodium ion batteries, and in particular to a sodium ion battery electrolyte. Background Art

[0002] In recent years, with the rapid development of electronic devices, power tools, and low-power electric vehicles, research on energy storage materials with high energy efficiency, abundant resources, and environmental friendliness is a necessary condition for the sustainable development of human society. In order to meet the huge market demand, it is far from enough to measure battery materials only by performance such as energy density and charge and discharge rate. Whether the manufacturing cost and energy consumption of the battery cause pollution to the environment and the recycling rate of resources will also become important indicators for evaluating battery materials. Sodium is one of the most abundant elements on the earth, and its chemical properties are similar to those of sodium, so it can also be applied to lithium-ion battery systems. Sodium-ion batteries have many advantages over lithium-ion batteries, such as low cost and good safety. With the deepening of research, sodium-ion batteries will become more and more cost-effective and are expected to replace lithium-ion batteries in the future and be widely used. As a new type of energy storage battery, sodium-ion batteries need to meet performance requirements at different temperatures and high cycle requirements.

[0003] The layered positive electrode active materials of existing sodium ion batteries have poor stability in the air, especially in humid air, the impact will be further aggravated. This is mainly because the unstable positive electrode active materials will undergo Na-H exchange reaction with water to generate more NaOH, and react with CO2 in the air to generate electrochemically inert Na2CO3. The generated alkaline impurities (NaOH and Na2CO3) will cause the slurry to gel during the processing, making it difficult to coat. Subsequently, in the electrochemical reaction process, the alkaline impurities will react with the electrolyte to increase gas production, seriously affecting the cycle performance and safety performance.

[0004] Therefore, there is an urgent need to provide an electrolyte material with good stability to improve its processing performance and enhance the cycle performance of sodium ion batteries. Summary of the invention

[0005] The present application provides a sodium ion battery electrolyte to improve the cycle performance of the sodium ion battery.

[0006] The present application provides a sodium ion battery electrolyte, the components of the electrolyte including: sodium salt, non-aqueous organic solvent, additive A and additive B, the additive A includes a cyclic sulfate compound, and the additive B includes an alkyl dicarbonate compound.

[0007] As an optional embodiment, the cyclic sulfate ester compound includes:

[0008] At least one of;

[0009] Wherein, R1, R2, R3 and R4 are independently selected from one of H, C1-C3 hydrocarbon group, halogen, nitrile group, carboxyl group, sulfonic acid group, C1-C20 alkyl group, C1-C20 halogenated alkyl group, C2-C20 unsaturated hydrocarbon group and C2-C20 halogenated unsaturated hydrocarbon group; m is 1, 2 or 3.

[0010] As an optional embodiment, the cyclic sulfate ester compound includes at least one of vinyl sulfate, 4-methylethylene sulfate, 4-propylethylene sulfate, propylene sulfate, 4-methylpropylene sulfate and 4-propylpropylene sulfate.

[0011] As an optional implementation manner, the mass proportion of the cyclic sulfate ester compound in the electrolyte is 0.5% to 6%.

[0012] As an optional embodiment, the alkyl dicarbonate compound includes:

[0013]

[0014] Wherein, R5 and R6 are independently selected from C1-C4 alkyl groups.

[0015] As an optional embodiment, the alkyl dicarbonate compound includes at least one of dimethyl pyrocarbonate, diethyl pyrocarbonate, and di-tert-butyl dicarbonate.

[0016] As an optional implementation manner, the mass proportion of the alkyl dicarbonate compound in the electrolyte is 0.3% to 5%.

[0017] As an optional embodiment, the sodium salt includes NaPF6, NaClO4, NaAlCl4, NaFeCl4, NaSO3CF3, NaBCl4, NaNO3, NaPOF4, NaSCN, NaCN, NaAsF6, NaCF3CO2, NaSbF6, NaC6H5CO2, Na(CH 3) At least one of C6H4SO3, NaHSO4 and NaB(C6H5)4; and / or

[0018] The non-aqueous organic solvent includes at least two of ethylene carbonate, propylene carbonate, butylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, 1,4-butyrolactone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, ethyl butyrate, sulfolane, dimethyl sulfone, ethyl methyl sulfone and diethyl sulfone.

[0019] As an optional embodiment, the molar concentration of the sodium salt is 0.5-2.0M; and / or

[0020] The non-aqueous organic solvent is two of ethylene carbonate, propylene carbonate, butylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, 1,4-butyrolactone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, ethyl butyrate, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone, and the volume ratio of the two non-aqueous organic solvents is (3:7) to (7:3).

[0021] As an optional embodiment, the electrolyte further includes: at least one of vinylene carbonate, ethylene carbonate, fluoroethylene carbonate, succinonitrile, adiponitrile, 1,3-propylene sultone, tris(trimethylsilane) phosphate, and tris(trimethylsilane) borate.

[0022] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0023] The electrolyte provided in the embodiment of the present application uses an alkyl dicarbonate compound and a cyclic sulfate compound in combination as additives, and the two exert a synergistic effect. The sodium ion battery electrolyte is applied to a sodium ion battery, which can effectively improve the cycle performance of the sodium ion battery, reduce the high-temperature storage gas production of the sodium ion battery, and improve the performance of the sodium ion battery. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments in the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0026] An embodiment of the present application provides a sodium ion battery electrolyte, wherein the components of the electrolyte include: a sodium salt, a non-aqueous organic solvent, an additive A and an additive B, wherein the additive A includes a cyclic sulfate ester compound, and the additive B includes an alkyl dicarbonate compound.

[0027] In some embodiments, the cyclic sulfate ester compound comprises:

[0028] At least one of;

[0029] Wherein, R1, R2, R3 and R4 are independently selected from one of H, C1-C3 hydrocarbon group, halogen, nitrile group, carboxyl group, sulfonic acid group, C1-C20 alkyl group, C1-C20 halogenated alkyl group, C2-C20 unsaturated hydrocarbon group and C2-C20 halogenated unsaturated hydrocarbon group; m is 1, 2 or 3.

[0030] Specifically, the cyclic sulfate ester compound includes at least one of vinyl sulfate, 4-methylethylene sulfate, 4-propylethylene sulfate, propylene sulfate, 4-methylpropylene sulfate and 4-propylpropylene sulfate. More preferably, at least one of vinyl sulfate, 4-methylethylene sulfate, propylene sulfate and 4-methylpropylene sulfate is used, and vinyl sulfate is further preferred.

[0031] In some embodiments, the mass proportion of the cyclic sulfate ester compound in the electrolyte is 0.5% to 6%, preferably 1% to 5%, and more preferably 3%.

[0032] The addition of cyclic sulfate compounds helps sodium-ion batteries to better balance high-temperature cycle performance, high-temperature storage performance and power performance.

[0033] In some embodiments, the alkyl dicarbonate compound comprises:

[0034]

[0035] Wherein, R5 and R6 are independently selected from C1-C4 alkyl groups.

[0036] Specifically, the alkyl dicarbonate compound includes at least one of dimethyl pyrocarbonate, diethyl pyrocarbonate, and di-tert-butyl dicarbonate.

[0037] In some embodiments, the mass proportion of the alkyl dicarbonate compound in the electrolyte is 0.3% to 5%, preferably 1% to 4%.

[0038] In some embodiments, the sodium salt includes NaPF6, NaClO4, NaAlCl4, NaFeCl4, NaSO3CF3, NaBCl4, NaNO3, NaPOF4, NaSCN, NaCN, NaAsF6, NaCF3CO2, NaSbF6, NaC6H5CO2, Na(CH 3)At least one of C6H4SO3, NaHSO4 and NaB(C6H5)4; preferably, the sodium salt includes at least one of NaPF6, NaClO4, NaSO3CF3 and Na(CH3)C6H4SO3, and more preferably, the sodium salt includes NaClO4. The concentration of the sodium salt can be the conventional concentration of the sodium salt in the sodium ion battery electrolyte in the art. In this embodiment, the molar concentration of the sodium salt is 0.5-2.0M, and more preferably the molar concentration is 0.8-1.2M, such as 1M.

[0039] In some embodiments, the non-aqueous organic solvent includes at least two of ethylene carbonate, propylene carbonate, butylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, 1,4-butyrolactone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, ethyl butyrate, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone; when the non-aqueous organic solvent is two of ethylene carbonate, propylene carbonate, butylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, 1,4-butyrolactone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, ethyl butyrate, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone, the volume ratio of the two non-aqueous organic solvents is (3:7) to (7:3). The preferred volume ratio of the two non-aqueous organic solvents is (3:2) to (2:3).

[0040] In some embodiments, the electrolyte further includes: at least one of vinylene carbonate (VC), vinyl ethylene carbonate (VEC), fluoroethylene carbonate (FEC), succinonitrile (SN), adiponitrile (ADN), 1,3-propylene sultone (PST), tris(trimethylsilyl) phosphate (TMSP), and tris(trimethylsilyl) borate (TMSB).

[0041] The electrolyte uses a combination of an alkyl dicarbonate compound and a cyclic sulfate compound as additives, and the two play a synergistic role, which is beneficial to improving the quality of the SEI film. On the one hand, it improves the high temperature performance of the sodium ion battery and inhibits the gas production of the sodium ion battery. On the other hand, it improves the cycle performance of the sodium ion battery and adjusts the impedance of the sodium ion battery. And the quality of the SEI film can be further improved by adjusting the amount of additive A and additive B added to achieve a high-performance sodium ion battery. That is, the application of sodium ion battery electrolyte to sodium ion batteries can effectively improve the cycle performance of sodium ion batteries, reduce the high-temperature storage gas production of sodium ion batteries, and improve the performance of sodium ion batteries.

[0042] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0043] Example 1

[0044] A sodium ion battery electrolyte, the composition of the electrolyte is shown in the following table:

[0045]

[0046]

[0047] Comparative Example 1

[0048] A sodium ion battery electrolyte, the composition of the electrolyte is shown in the following table:

[0049]

[0050] The electrolyte provided in Example 1 and Comparative Example 1 was applied to a sodium ion battery, the positive electrode of which was a layered oxide and the negative electrode was hard carbon. After the sodium ion battery was stored at a high temperature of 45°C for 15 days, the performance was compared, and the results are shown in the following table:

[0051]

[0052] It can be seen from the above table that the use of the electrolyte provided in the embodiments of the present application can effectively improve the cycle performance of the sodium ion battery and reduce the high-temperature storage gas production of the sodium ion battery.

[0053] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0054] In the description of the specification of the present application, the terms "include", "comprise", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second", etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" means one or more, and "plurality" means two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc or abc, where a, b, c can be single or plural, respectively.

[0055] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A sodium ion battery electrolyte, characterized in that: The electrolyte comprises sodium salt, non-aqueous organic solvent, additive A and additive B, wherein the additive A comprises a cyclic sulfate compound and the additive B comprises an alkyl dicarbonate compound.

2. The sodium ion battery electrolyte according to claim 1, characterized in that The cyclic sulfate compounds include: At least one of; Wherein, R1, R2, R3 and R4 are independently selected from one of H, C1-C3 hydrocarbon group, halogen, nitrile group, carboxyl group, sulfonic acid group, C1-C20 alkyl group, C1-C20 halogenated alkyl group, C2-C20 unsaturated hydrocarbon group and C2-C20 halogenated unsaturated hydrocarbon group; m is 1, 2 or 3.

3. The sodium ion battery electrolyte according to claim 1 or 2, characterized in that: The cyclic sulfate ester compound includes at least one of vinyl sulfate, 4-methylethylene sulfate, 4-propylethylene sulfate, propylene sulfate, 4-methylpropylene sulfate and 4-propylpropylene sulfate.

4. The sodium ion battery electrolyte according to claim 1, characterized in that The mass percentage of the cyclic sulfate ester compound in the electrolyte is 0.5% to 6%.

5. The sodium ion battery electrolyte according to claim 1, characterized in that The alkyl dicarbonate compounds include: Wherein, R5 and R6 are independently selected from C1-C4 alkyl groups.

6. The sodium ion battery electrolyte according to claim 4 or 5, characterized in that: The alkyl dicarbonate compound includes at least one of dimethyl pyrocarbonate, diethyl pyrocarbonate, and di-tert-butyl dicarbonate.

7. The sodium ion battery electrolyte according to claim 1, characterized in that The mass percentage of the alkyl dicarbonate compound in the electrolyte is 0.3% to 5%.

8. The sodium ion battery electrolyte according to claim 1, characterized in that: The sodium salts include NaPF6, NaClO4, NaAlCl4, NaFeCl4, NaSO3CF3, NaBCl4, NaNO3, NaPOF4, NaSCN, NaCN, NaAsF6, NaCF3CO2, NaSbF6, NaC6H5CO2, Na(CH 3) At least one of C6H4SO3, NaHSO4 and NaB(C6H5)4; and / or The non-aqueous organic solvent includes at least two of ethylene carbonate, propylene carbonate, butylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, 1,4-butyrolactone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, ethyl butyrate, sulfolane, dimethyl sulfone, ethyl methyl sulfone and diethyl sulfone.

9. The sodium ion battery electrolyte according to claim 8, characterized in that: The molar concentration of the sodium salt is 0.5-2.0M; and / or The non-aqueous organic solvent is two of ethylene carbonate, propylene carbonate, butylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, 1,4-butyrolactone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, ethyl butyrate, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone, and the volume ratio of the two non-aqueous organic solvents is (3:7) to (7:3).

10. The sodium ion battery electrolyte according to claim 1, characterized in that: The electrolyte further comprises: at least one of vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, succinonitrile, adiponitrile, 1,3-propylene sultone, tris(trimethylsilane)phosphate, and tris(trimethylsilane)borate.

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