Sodium-ion battery electrolyte

Abstract

This invention discloses a sodium-ion battery electrolyte, belonging to the field of sodium-ion battery technology, comprising an organic solvent, a sodium salt, and additives; the organic solvent includes ethylene carbonate, propylene carbonate, methyl ethyl carbonate, and ethyl acetate; the sodium salt includes sodium hexafluorophosphate and sodium difluorosulfonylimide; the additives include fluoroethylene carbonate, vinylene sulfate, sodium difluorophosphate, sodium difluorooxalate borate, and tris(trimethylsilane)phosphate. The sodium-ion battery electrolyte of this invention, through precise adjustment of the solvent and sodium salt ratio, maintains high conductivity at extremely low temperatures, significantly raising the lower limit operating temperature of the battery to -70°C. Simultaneously, through the synergistic effect of the sodium salt and additives, a high-temperature resistant SEI film rich in inorganic components is formed, reducing side reactions at high temperatures and raising the upper limit operating temperature of the battery to 85°C, achieving a wide temperature range application of the battery from -70°C to 85°C.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion battery technology, and in particular relates to a sodium-ion battery electrolyte. Background Technology

[0002] Sodium-ion batteries, with their significant advantages of low theoretical cost and outstanding safety performance, have shown broad application prospects in the field of low-speed electric vehicles. However, the vast differences in temperature environments across different latitudes around the world pose stringent challenges to the wide-temperature-range operating performance of batteries: extreme low temperatures in high-latitude regions such as Northeast China and Russia can reach -60°C; tropical and subtropical regions such as the Middle East and Southeast Asia maintain year-round temperatures of 30°C-40°C, and battery temperatures can easily rise to 60°C-80°C after exposure to sunlight. Currently, the operating temperature range of conventional sodium-ion batteries is limited to -40°C to 60°C, making it difficult to adapt to the above-mentioned extreme high and low temperature scenarios. Therefore, developing wide-temperature-range adaptable sodium-ion batteries has become a key research direction for expanding their application boundaries. Summary of the Invention

[0003] To overcome the above problems, the present invention provides a sodium-ion battery electrolyte, which aims to broaden the operating temperature range of sodium-ion batteries.

[0004] The technical solution adopted in this invention is: A sodium-ion battery electrolyte includes an organic solvent, a sodium salt, and additives; The organic solvents, by mass, include 8-9 parts of ethylene carbonate (EC), 10-40 parts of propylene carbonate (PC), 20-30 parts of ethyl methyl carbonate (EMC), and 30-50 parts of ethyl acetate (EA). The sodium salt, by mass fraction, includes 6-8 parts of sodium hexafluorophosphate (NaPF6) and 6-8 parts of sodium difluorosulfonamide (NaFSI). The additives, by mass percentage, include 0.5-1.5 parts of fluoroethylene carbonate (FEC), 1-3 parts of vinylene sulfate (DTD), 0.1-0.5 parts of sodium difluorophosphate (NaPO2F2), 0.1-0.3 parts of sodium difluorooxalate borate (NaODFB), and 0.3-0.7 parts of tris(trimethylsilane) phosphate (TMSP).

[0005] As one implementation method: The organic solvents, by mass, include 8.5 parts ethylene carbonate, 18.2 parts propylene carbonate, 25.2 parts methyl ethyl carbonate, and 32.1 parts ethyl acetate. The sodium salt, by mass fraction, includes 6 parts sodium hexafluorophosphate and 6 parts sodium difluorosulfonamide. The additives, by mass, include 1 part fluoroethylene carbonate, 2 parts vinylene sulfate, 0.3 parts sodium difluorophosphate, 0.2 parts sodium difluorooxalate borate, and 0.5 parts tris(trimethylsilane) phosphate.

[0006] As one implementation method: The organic solvents, by mass, include 8 parts ethylene carbonate, 10 parts propylene carbonate, 20 parts methyl ethyl carbonate, and 30 parts ethyl acetate. The sodium salt, by mass fraction, includes 6 parts sodium hexafluorophosphate and 6 parts sodium difluorosulfonamide. The additives, by mass, include 0.5 parts fluoroethylene carbonate, 1 part vinylene sulfate, 0.1 parts sodium difluorophosphate, 0.1 parts sodium difluorooxalate borate, and 0.3 parts tris(trimethylsilane) phosphate.

[0007] As one implementation method: The organic solvents, by mass fraction, include 9 parts ethylene carbonate, 40 parts propylene carbonate, 30 parts methyl ethyl carbonate, and 50 parts ethyl acetate. The sodium salt, by mass fraction, includes 8 parts sodium hexafluorophosphate and 8 parts sodium difluorosulfonamide. The additives, by mass, include 1.5 parts fluoroethylene carbonate, 3 parts vinylene sulfate, 0.5 parts sodium difluorophosphate, 0.3 parts sodium difluorooxalate borate, and 0.7 parts tris(trimethylsilane) phosphate.

[0008] As one implementation method: The organic solvents, by mass, include 8 parts ethylene carbonate, 40 parts propylene carbonate, 20 parts methyl ethyl carbonate, and 50 parts ethyl acetate. The sodium salt, by mass fraction, includes 6 parts sodium hexafluorophosphate and 8 parts sodium difluorosulfonamide. The additives, by mass, include 0.5 parts fluoroethylene carbonate, 3 parts vinylene sulfate, 0.1 parts sodium difluorophosphate, 0.3 parts sodium difluorooxalate borate, and 0.3 parts tris(trimethylsilane) phosphate.

[0009] As one implementation method: The organic solvents, by mass fraction, include 9 parts ethylene carbonate, 10 parts propylene carbonate, 30 parts methyl ethyl carbonate, and 30 parts ethyl acetate. The sodium salt, by mass fraction, includes 8 parts sodium hexafluorophosphate and 6 parts sodium difluorosulfonamide. The additives, by mass, include 1.5 parts of fluoroethylene carbonate, 1 part of vinylene sulfate, 0.5 parts of sodium difluorophosphate, 0.1 parts of sodium difluorooxalate borate, and 0.7 parts of tris(trimethylsilane) phosphate.

[0010] The advantages of this invention are as follows: The sodium-ion battery electrolyte of this invention, by precisely adjusting the ratio of solvent and sodium salt, enables the electrolyte to maintain high conductivity at extremely low temperatures, significantly increasing the lower limit operating temperature of the battery to -70°C. At the same time, through the synergistic effect of sodium salt and additives, a high-temperature resistant SEI film rich in inorganic components is formed, reducing side reactions at high temperatures and raising the upper limit operating temperature of the battery to 85°C, thus achieving a wide temperature range application of the battery from -70°C to 85°C. Attached Figure Description

[0011] Figure 1 A schematic diagram of an 85°C high-temperature cycling test performed on Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of a -70°C 1C rate discharge as described in Embodiment 1 of the present invention. Detailed Implementation

[0012] Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0013] A sodium-ion battery electrolyte includes an organic solvent, a sodium salt, and additives; The organic solvents, by mass fraction, include 8-9 parts ethylene carbonate, 10-40 parts propylene carbonate, 20-30 parts methyl ethyl carbonate, and 30-50 parts ethyl acetate. The sodium salt, by mass fraction, includes 6-8 parts sodium hexafluorophosphate and 6-8 parts sodium difluorosulfonamide. The additives, by mass fraction, include 0.5-1.5 parts of fluoroethylene carbonate, 1-3 parts of vinylene sulfate, 0.1-0.5 parts of sodium difluorophosphate, 0.1-0.3 parts of sodium difluorooxalate borate, and 0.3-0.7 parts of tris(trimethylsilane) phosphate.

[0014] Example 1 This embodiment provides a sodium-ion battery electrolyte, comprising an organic solvent, a sodium salt, and additives; The organic solvents include 8.5g of ethylene carbonate, 18.2g of propylene carbonate, 25.2g of methyl ethyl carbonate, and 32.1g of ethyl acetate; The sodium salts consist of 6g of sodium hexafluorophosphate and 6g of sodium difluorosulfonamide. The additives include 1g of fluoroethylene carbonate, 2g of vinylene sulfate, 0.3g of sodium difluorophosphate, 0.2g of sodium difluorooxalate borate, and 0.5g of tris(trimethylsilane) phosphate.

[0015] Example 2 A sodium-ion battery electrolyte includes an organic solvent, a sodium salt, and additives; The organic solvents include 8g of ethylene carbonate, 10g of propylene carbonate, 20g of methyl ethyl carbonate, and 30g of ethyl acetate; The sodium salts consist of 6g of sodium hexafluorophosphate and 6g of sodium difluorosulfonamide. The additives include 0.5g of fluoroethylene carbonate, 1g of vinylene sulfate, 0.1g of sodium difluorophosphate, 0.1g of sodium difluorooxalate borate, and 0.3g of tris(trimethylsilane) phosphate.

[0016] Example 3 A sodium-ion battery electrolyte includes an organic solvent, a sodium salt, and additives; The organic solvents include 9g of ethylene carbonate, 40g of propylene carbonate, 30g of methyl ethyl carbonate, and 50g of ethyl acetate; The sodium salt consists of 8g of sodium hexafluorophosphate and 8g of sodium difluorosulfonamide. The additives include 1.5g of fluoroethylene carbonate, 3g of vinylene sulfate, 0.5g of sodium difluorophosphate, 0.3g of sodium difluorooxalate borate, and 0.7g of tris(trimethylsilane) phosphate.

[0017] Example 4 A sodium-ion battery electrolyte includes an organic solvent, a sodium salt, and additives; The organic solvents include 8g of ethylene carbonate, 40g of propylene carbonate, 20g of methyl ethyl carbonate, and 50g of ethyl acetate; The sodium salt consists of 6g of sodium hexafluorophosphate and 8g of sodium difluorosulfonamide. The additives include 0.5g of fluoroethylene carbonate, 3g of vinylene sulfate, 0.1g of sodium difluorophosphate, 0.3g of sodium difluorooxalate borate, and 0.3g of tris(trimethylsilane) phosphate.

[0018] Example 5 A sodium-ion battery electrolyte includes an organic solvent, a sodium salt, and additives; The organic solvents include 9g of ethylene carbonate, 10g of propylene carbonate, 30g of methyl ethyl carbonate, and 30g of ethyl acetate; The sodium salt consists of 8g of sodium hexafluorophosphate and 6g of sodium difluorosulfonamide. The additives include 1.5g of fluoroethylene carbonate, 1g of vinylene sulfate, 0.5g of sodium difluorophosphate, 0.1g of sodium difluorooxalate borate, and 0.7g of tris(trimethylsilane) phosphate.

[0019] Example 1 above is the preferred embodiment. The sodium-ion battery prepared using this electrolyte underwent a high-temperature cycling test at 85°C. Figure 1 As shown, the cycle life is expected to reach 3000cls, a significant improvement compared to conventional batteries (approximately 2000cls cycle life at 60℃); simultaneously, the battery is discharged at -70℃ at a 1C rate, such as... Figure 2 As shown, the capacity retention rate is 86.9%, which is a significant improvement compared to conventional batteries (capacity retention rate of about 60% at -40℃ 1C discharge).

[0020] The embodiments described above are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A sodium-ion battery electrolyte, characterized in that: Including organic solvents, sodium salts, and additives; The organic solvent, by mass parts, includes 8-9 parts of ethylene carbonate, 10-40 parts of propylene carbonate, 20-30 parts of methyl ethyl carbonate, and 30-50 parts of ethyl acetate. The sodium salt comprises, by mass parts, 6-8 parts sodium hexafluorophosphate and 6-8 parts sodium difluorosulfonamide; The additives, by mass fraction, include 0.5-1.5 parts of fluoroethylene carbonate, 1-3 parts of vinylene sulfate, 0.1-0.5 parts of sodium difluorophosphate, 0.1-0.3 parts of sodium difluorooxalate borate, and 0.3-0.7 parts of tris(trimethylsilane) phosphate.

2. The sodium-ion battery electrolyte according to claim 1, characterized in that: in, The organic solvent comprises, by mass parts, 8.5 parts ethylene carbonate, 18.2 parts propylene carbonate, 25.2 parts methyl ethyl carbonate, and 32.1 parts ethyl acetate; The sodium salt comprises, by mass parts, 6 parts sodium hexafluorophosphate and 6 parts sodium difluorosulfonamide; The additives, by mass, include 1 part fluoroethylene carbonate, 2 parts vinylene sulfate, 0.3 parts sodium difluorophosphate, 0.2 parts sodium difluorooxalate borate, and 0.5 parts tris(trimethylsilane) phosphate.

3. The sodium-ion battery electrolyte according to claim 1, characterized in that: in, The organic solvent comprises, by mass parts, 8 parts ethylene carbonate, 10 parts propylene carbonate, 20 parts methyl ethyl carbonate, and 30 parts ethyl acetate; The sodium salt comprises, by mass parts, 6 parts sodium hexafluorophosphate and 6 parts sodium difluorosulfonamide; The additives, by mass, include 0.5 parts of fluoroethylene carbonate, 1 part of vinylene sulfate, 0.1 parts of sodium difluorophosphate, 0.1 parts of sodium difluorooxalate borate, and 0.3 parts of tris(trimethylsilane) phosphate.

4. The sodium-ion battery electrolyte according to claim 1, characterized in that: in, The organic solvent comprises, by mass parts, 9 parts ethylene carbonate, 40 parts propylene carbonate, 30 parts methyl ethyl carbonate, and 50 parts ethyl acetate; The sodium salt comprises, by mass parts, 8 parts sodium hexafluorophosphate and 8 parts sodium difluorosulfonamide; The additives, by mass, include 1.5 parts of fluoroethylene carbonate, 3 parts of vinylene sulfate, 0.5 parts of sodium difluorophosphate, 0.3 parts of sodium difluorooxalate borate, and 0.7 parts of tris(trimethylsilane) phosphate.

5. The sodium-ion battery electrolyte according to claim 1, characterized in that: in, The organic solvent comprises, by mass parts, 8 parts ethylene carbonate, 40 parts propylene carbonate, 20 parts methyl ethyl carbonate, and 50 parts ethyl acetate; The sodium salt comprises, by mass parts, 6 parts sodium hexafluorophosphate and 8 parts sodium difluorosulfonamide; The additives, by mass, include 0.5 parts of fluoroethylene carbonate, 3 parts of vinylene sulfate, 0.1 parts of sodium difluorophosphate, 0.3 parts of sodium difluorooxalate borate, and 0.3 parts of tris(trimethylsilane) phosphate.

6. The sodium-ion battery electrolyte according to claim 1, characterized in that: in, The organic solvent comprises, by mass parts, 9 parts ethylene carbonate, 10 parts propylene carbonate, 30 parts methyl ethyl carbonate, and 30 parts ethyl acetate; The sodium salt comprises, by mass parts, 8 parts sodium hexafluorophosphate and 6 parts sodium difluorosulfonamide; The additives, by mass, include 1.5 parts of fluoroethylene carbonate, 1 part of vinylene sulfate, 0.5 parts of sodium difluorophosphate, 0.1 parts of sodium difluorooxalate borate, and 0.7 parts of tris(trimethylsilane) phosphate.

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