Sodium-ion battery electrolyte, sodium-ion battery and power-related equipment

Abstract

The invention provides a sodium-ion battery electrolyte, a sodium-ion battery and power-related equipment, and relates to the field of sodium-ion batteries. The sodium-ion battery electrolyte comprises the following raw materials in percentage by mass: 5-15% of sodium salt, 60-90% of organic solvent and 0.1-10% of film-forming additive, wherein the total mass of the raw materials is 100%; the sodium salt comprises one or more of sodium hexafluoroaluminate, tetrahydroxy sodium aluminate and high-chlorine sodium aluminate. By proportioning the sodium salt, the organic solvent and the additive, the comprehensive performance of the sodium-ion battery material can be improved, the cycle life of the battery can be prolonged, the first charge-discharge efficiency of the battery can be improved, the specific capacity can be improved, and the safety and the compatibility with the existing battery assembly process are good.

Description

Technical Field

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

[0002] Due to the growing energy demand and increasingly serious environmental problems, secondary ion batteries are gradually replacing traditional energy sources such as oil, natural gas and coal to become an important component of energy storage systems due to their environmentally friendly characteristics. Among them, lithium-ion batteries have been widely used in electronic portable devices and electric vehicles due to their high energy density. However, due to the limited lithium content in the earth's crust, it is urgent to develop new energy storage systems. Sodium-ion batteries have received widespread attention in recent years due to their abundant sodium reserves, low cost, and similar working principles to lithium-ion batteries.

[0003] Compared with lithium batteries, sodium batteries have the comprehensive advantages of low cost, wide high and low temperature range and good safety performance. However, sodium-ion batteries have disadvantages such as difficulty in charging during the cycle, poor cycle performance under high voltage and large gas production, which restrict their application. As one of the key materials of sodium-ion power batteries, electrolyte has a significant impact on the battery's cycle performance, storage performance and gas production.

[0004] Therefore, it is of great significance to develop sodium salts and electrolytes that meet the performance requirements of sodium-ion batteries. Summary of the invention

[0005] The purpose of this application is to provide a sodium ion battery electrolyte, a sodium ion battery and electrical equipment to solve the above problems.

[0006] To achieve the above objectives, the first aspect of the present application provides a sodium ion battery electrolyte, wherein the raw materials thereof, calculated by total mass as 100%, include:

[0007] Sodium salt 5%-15%, organic solvent 60%-90%, film-forming additive 0.1%-10%;

[0008] The sodium salt includes one or more of sodium hexafluoroaluminate, sodium tetrahydroxyaluminate, and sodium perchloroaluminate.

[0009] Optionally, the sodium ion battery electrolyte satisfies at least one of the following conditions:

[0010] A. the sodium salt accounts for 8%-12% of the total mass of the raw material;

[0011] B. The film-forming additive accounts for 1%-5% of the total mass of the raw materials.

[0012] Optionally, the sodium salt comprises sodium hexafluoroaluminate.

[0013] Optionally, the organic solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0014] Optionally, the organic solvent includes ethyl methyl carbonate, ethylene carbonate and propylene carbonate;

[0015] The mass ratio of the ethyl methyl carbonate, the ethylene carbonate and the propylene carbonate is 2.1-4.0:1.5-3.0:1.5-3.0.

[0016] Optionally, the film-forming additive includes one or more of fluoroethylene carbonate, vinylene carbonate, and 1,3-propylene sultone.

[0017] Optionally, the film-forming additive includes 1,3-propylene sultone and fluoroethylene carbonate;

[0018] The mass ratio of the 1,3-propylene sultone to the fluoroethylene carbonate is 1-3:1.

[0019] A second aspect of the present application provides a sodium ion battery, comprising the sodium ion battery electrolyte, a positive electrode sheet and a negative electrode sheet.

[0020] Optionally, the sodium ion battery satisfies at least one of the following conditions:

[0021] A. The positive electrode active material in the positive electrode sheet includes a layered oxide;

[0022] B. The negative electrode active material in the negative electrode plate includes hard carbon.

[0023] The third aspect of the present application provides an electrical device, including the sodium ion battery.

[0024] Compared with the prior art, the beneficial effects of this application include:

[0025] The sodium ion battery electrolyte provided in the present application can improve the comprehensive performance of sodium ion battery materials, extend the battery cycle life, improve its initial charge and discharge efficiency, increase specific capacity, and have good safety and compatibility with existing battery assembly processes through the ratio of sodium salt, organic solvent and additives.

[0026] The sodium ion battery provided in the present application has effectively improved initial coulombic efficiency and reversible capacity, prolonged subsequent cycle life, good safety and easy operation.

[0027] The electrical equipment provided in this application has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0029] Figure 1 This is a physical picture of the sodium ion battery electrolyte provided in Example 1. DETAILED DESCRIPTION

[0030] As used herein:

[0031] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0032] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0033] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0034] In these examples, parts and percentages are by mass unless otherwise indicated.

[0035] "Parts by mass" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass of all components is not limited to 100 parts.

[0036] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0037] The present application adopts a first aspect to provide a sodium ion battery electrolyte, wherein the raw materials thereof, calculated by total mass as 100%, include:

[0038] Sodium salt 5%-15%, organic solvent 60%-90%, film-forming additive 0.1%-10%;

[0039] Optionally, the raw materials of the sodium ion battery electrolyte are calculated based on the total mass of 100%, the sodium salt can be 5%, 9%, 12%, 15% or any value between 5% and 15%, the organic solvent can be 60%, 65%, 70%, 75%, 80%, 85%, 90% or any value between 60% and 90%, and the film-forming additive can be 0.1%, 0.5%, 1%, 5%, 10% or any value between 0.1% and 10%;

[0040] The sodium salt includes one or more of sodium hexafluoroaluminate, sodium tetrahydroxyaluminate, and sodium perchloroaluminate.

[0041] It should be noted that when the sodium ion battery is charging, the sodium ions are released from the positive electrode and embedded in the negative electrode through the electrolyte. At the same time, the compensating charge of the electrons is supplied to the negative electrode through the external circuit to ensure the charge balance between the positive and negative electrodes. The opposite is true during discharge, which ensures the efficient transmission of sodium ions, thereby realizing the normal charging and discharging function of the battery. The higher melting point makes it resistant to high temperatures and remains stable at room temperature and pressure. Based on this, the present application selects aluminate as the sodium salt and applies it to the electrolyte additive, which can improve the conductivity and stability of the electrolyte and improve the production efficiency and quality of aluminum.

[0042] In some embodiments, the sodium ion battery electrolyte satisfies at least one of the following conditions:

[0043] A. the sodium salt accounts for 8%-12% of the total mass of the raw material;

[0044] Optionally, the sodium salt may account for 8%, 9%, 10%, 11%, 12% or any value between 8% and 12% of the total mass of the raw material;

[0045] In some embodiments, the sodium salt accounts for 8%-12% of the total mass of the raw materials. Too much sodium salt will cause a problem of micro-water absorption, and a trace amount of precipitation will appear after long-term storage. Too little sodium salt will cause insufficient electron migration, and the electrons will flow from the negative electrode to the positive electrode through the external circuit, which will cause insufficient discharge and result in a low initial efficiency of the battery.

[0046] B. The film-forming additive accounts for 1%-5% of the total mass of the raw materials.

[0047] Optionally, the film-forming additive accounts for 1%, 2%, 3%, 4%, 5% or any value between 1% and 5% of the total mass of the raw material.

[0048] In some embodiments, the sodium salt comprises sodium hexafluoroaluminate.

[0049] It should be noted that sodium hexafluoroaluminate (Na3AlF6) has 3 Na atoms, which can alleviate the problem of insufficient sodium source supplementation in P2-type sodium-containing materials, and is safer and can improve the conductivity and stability of the electrolyte.

[0050] It should also be noted that sodium hexafluoroaluminate shows that each fluoride ion surrounds the aluminum ion at an equal distance, and has an octahedral structure. It has a high melting point, good stability, good corrosion resistance and oxidation resistance, can maintain stable physical and chemical properties over a wide temperature range, and is not easy to decompose, thereby improving the safety and service life of the battery.

[0051] In some embodiments, the organic solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0052] In some embodiments, the organic solvent includes ethyl methyl carbonate, ethylene carbonate, and propylene carbonate;

[0053] The mass ratio of the ethyl methyl carbonate, the ethylene carbonate and the propylene carbonate is 2.1-4.0:1.5-3.0:1.5-3.0.

[0054] Optionally, the mass ratio of ethyl methyl carbonate, ethylene carbonate and propylene carbonate can be 2.1:1.5:1.5, 3:1.5:1.5, 4:1.5:1.5, 2.1:2:1.5, 2.1:3:1.5, 2.1:1.5:2, 2.1:1.5:3, 3:3:3, 3:2:2, 4:3:3 or any value between 2.1-4.0:1.5-3.0:1.5-3.0.

[0055] In some embodiments, the mass ratio of ethyl methyl carbonate, ethylene carbonate and propylene carbonate is 4:3:3.

[0056] It should be noted that ethylene carbonate and propylene carbonate are carbon-based cyclic esters with high dielectric constants and large viscosities; ethyl methyl carbonate has good low-temperature performance and can effectively inhibit the precipitation of ethylene carbonate at low temperatures. Ethyl methyl carbonate is a carbon-based chain ester with low dielectric constants and low viscosity, which is more conducive to the transmission of sodium ions and reduces its impedance; the addition of ethylene carbonate can change the original Na + The solvation configuration forces the methyl ethyl carbonate molecules to move to the outer layer and form an orderly chain-like arrangement. This configuration makes Na + It is relatively easy to deposit, preventing the precipitation of sodium and avoiding Na + It forms an unstable zigzag configuration with ethyl methyl carbonate, thereby improving the stability of the electrolyte. By controlling the mass ratio of the three within the above-mentioned appropriate range, it is beneficial to improve the kinetic performance of sodium ion batteries.

[0057] In some embodiments, the film-forming additive includes one or more of fluoroethylene carbonate, vinylene carbonate, and 1,3-propylene sultone.

[0058] In some embodiments, the film-forming additive includes 1,3-propylene sultone and fluoroethylene carbonate;

[0059] The mass ratio of the 1,3-propylene sultone to the fluoroethylene carbonate is 1-3:1.

[0060] Optionally, the mass ratio of 1,3-propene sultone to fluoroethylene carbonate may be 1:1, 2:1, 3:1 or any value between 1-3:1.

[0061] It should be noted that 1,3-propene sultone, as a thio-organic solvent, is a good film-forming additive for the battery SEI film, which can further enhance the protection of the SEI film and thus improve the performance of the battery. Fluorinated ethylene carbonate mainly improves the chemical and electrochemical properties of the electrolyte. In addition, when these two film-forming additives are used together at the positive end of the electrolyte, they can decompose to generate RSO 3- 、RSO3 2- and SO3 2- Anions, and by forming transition metal sulfide salts insoluble in electrolyte with transition metal ions, form a dense positive electrode solid electrolyte interphase membrane that can not only inhibit the decomposition of electrolyte solvents and prevent further dissolution of transition metal ions, but also have good compatibility with organic solvents, have no side effects on battery performance, and do not have side reactions with other materials in the battery, further improving the safety and stability of the battery, as well as high-temperature cycle performance and high-temperature storage performance. Smaller amounts can improve multiple battery properties.

[0062] It should also be noted that by controlling the mass ratio of the three organic solvents of ethyl methyl carbonate, ethylene carbonate and propylene carbonate within the above-mentioned appropriate range, the precipitation of sodium can be prevented, the problem of difficulty in charging sodium ion batteries can be solved and the impedance can be reduced; the chemical and electrochemical properties of the electrolyte are improved by combining 1,3-propylene sultone and fluoroethylene carbonate, and the performance of the SEI film is enhanced to improve the overall performance of the battery; the high-temperature cycle performance and high-temperature storage performance can be better improved by the synergy of the organic solvent and the film-forming additive; therefore, the sodium salt, organic solvent and film-forming additive of the sodium ion electrolyte can improve the comprehensive performance of the sodium ion battery material, extend the battery cycle life, improve its initial charge and discharge efficiency, and improve the specific capacity.

[0063] A second aspect of the present application provides a sodium ion battery, comprising the sodium ion battery electrolyte, a positive electrode sheet and a negative electrode sheet.

[0064] In some embodiments, the sodium ion battery satisfies at least one of the following conditions:

[0065] A. The positive electrode active material in the positive electrode sheet includes a layered oxide;

[0066] In some embodiments, the positive electrode active material includes Na 0.8 [N i0.32 Mn 0.44 Ti 0.17 Mg 0.07 ]O2;

[0067] B. The negative electrode active material in the negative electrode plate includes hard carbon.

[0068] In some embodiments, hard carbon was purchased from Kuraray Japan.

[0069] The third aspect of the present application provides an electrical device, including the sodium ion battery.

[0070] In some embodiments, electrical equipment includes, but is not limited to, one or more of electric vehicles, electric bicycles, smart home devices, robots, heavy trucks, ships, and energy storage systems.

[0071] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0072] Example 1

[0073] In a first aspect, the present embodiment provides a sodium ion battery electrolyte, wherein the raw materials thereof, calculated based on the total mass of 100%, include:

[0074] Sodium salt 8%, organic solvent 85%, film-forming additive 7%;

[0075] The sodium salt is sodium hexafluoroaluminate, the organic solvent is a mixture of ethyl methyl carbonate, ethylene carbonate and propylene carbonate in a mass ratio of 4:3:3, and the film-forming additive is 1,3-propylene sultone and fluoroethylene carbonate in a mass ratio of 1:1.

[0076] The above raw materials are mixed in proportion to obtain the sodium ion battery electrolyte. The sodium ion battery electrolyte is as follows: Figure 1 As shown (the left picture shows the unopened use after matching and left to stand for 60 days, and the right picture shows the sodium sheet placed in the electrolyte after repeated opening and use for 60 days after preparation to check the water absorption. The sodium sheet did not change color, and the electrolyte did not change color, proving that the electrolyte has not deteriorated).

[0077] A second aspect of the present embodiment provides a sodium ion battery, wherein a positive electrode shell, a spring sheet, a gasket, a sodium sheet, a diaphragm, the above-mentioned sodium ion battery electrolyte, and a negative electrode shell are assembled into a CR2025 sodium ion button battery in a glove box filled with argon gas.

[0078] Example 2

[0079] The difference from Example 1 is that the sodium salt in this example is sodium tetrahydroxyaluminate.

[0080] Example 3

[0081] The difference from Example 1 is that the sodium salt in this example is sodium perchloroaluminate.

[0082] Example 4

[0083] The difference from Example 1 is that the raw materials, based on the total mass as 100%, include:

[0084] Sodium salt 15%, organic solvent 75%, film-forming additive 10%.

[0085] Example 5

[0086] The difference from Example 1 is that the sodium ion full battery provided in this embodiment has a sodium ion battery positive electrode material of Na 0.8 [N i0.32 Mn 0.44 Ti 0.17 Mg 0.07 ]O2, the negative electrode material was purchased from hard carbon of Kuraray of Japan, N:P=0.9 to match the full battery, and the electrolyte provided by this application was used to assemble a CR2025 sodium ion button full battery in a glove box filled with argon.

[0087] Example 6

[0088] The difference from Example 1 is that the organic solvent in this example is propylene carbonate.

[0089] Example 7

[0090] The difference from Example 1 is that the film-forming additive in this example is fluoroethylene carbonate.

[0091] Comparative Example 1

[0092] The difference from Example 1 is that the sodium salt is sodium hexafluorophosphate.

[0093] Comparative Example 2

[0094] The difference from Example 1 is that the sodium salt is sodium perchlorate.

[0095] Comparative Example 3

[0096] The difference from Example 1 is that the organic solvent is ethylene glycol dimethyl ether (DME).

[0097] Comparative Example 4

[0098] The difference from Example 1 is that the film-forming additives are ethylene and vinyl carbonate (VEC).

[0099] Comparative Example 5

[0100] The difference from Example 1 is that the raw materials, based on the total mass as 100%, include:

[0101] Sodium salt 30%, organic solvent 50%, film-forming additive 20%.

[0102] The sodium ion batteries obtained in the above examples and comparative examples were subjected to performance tests, and the specific results are shown in Table 1.

[0103] The test method for cycle life is as follows: the test temperature is 25°C, the battery open circuit voltage is 2.62V, the constant current is charged at 1C rate to 4.35V, and the constant current is discharged at 1C rate to 2.0V. This cycle is repeated for 500 cycles.

[0104] The test method for the first charge and discharge efficiency and the test method for specific capacity: the test temperature is 25°C, the battery open circuit voltage is 2.62V, the constant current is charged to 4.35V at a rate of 0.1C, and the constant current is discharged to 2.0V at a rate of 0.1C.

[0105] Table 1 Performance test

[0106] Test sample Cycle life First charge and discharge efficiency Specific capacity Example 1 97.62 99.81 146.33 Example 2 97.01 95.23 142.92 Example 3 90.27 98.46 151.24 Example 4 96.58 98.41 145.22 Example 5 98.11 81.24 140.16 Example 6 91.54 95.48 142.71 Example 7 92.38 96.24 143.75 Comparative Example 1 96.32 89.25 135.94 Comparative Example 2 70.51 90.46 150.19 Comparative Example 3 80.74 87.89 133.13 Comparative Example 4 74.32 81.59 130.47 Comparative Example 5 60.43 75.77 117.91

[0107] From the data in Table 1, it can be seen that sodium aluminate has a better performance in sodium ion battery than sodium phosphate. High-chloride sodium salts are poor in cycle, but have better capacity. Sodium perchlorate aluminate can improve the battery cycle by 20% compared with sodium perchlorate.

[0108] Film-forming additives are important components for improving electrolytes. The two additives used in this application, 1,3-propylene sultone and fluoroethylene carbonate, are both suitable for use in sodium batteries, but the performance is slightly reduced when only one is used.

[0109] It can be seen from Comparative Example 5 that the ratio of the electrolyte is the biggest factor affecting the performance of the electrolyte, and all materials cannot be too much or too little.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0111] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. A sodium ion battery electrolyte, characterized in that: The raw materials thereof, calculated based on the total mass as 100%, include: Sodium salt 5%-15%, organic solvent 60%-90%, film-forming additive 0.1%-10%; The sodium salt includes one or more of sodium hexafluoroaluminate, sodium tetrahydroxyaluminate, and sodium perchloroaluminate.

2. The sodium ion battery electrolyte according to claim 1, characterized in that At least one of the following conditions is met: A. the sodium salt accounts for 8%-12% of the total mass of the raw material; B. The film-forming additive accounts for 1%-5% of the total mass of the raw materials.

3. The sodium ion battery electrolyte according to claim 1, characterized in that The sodium salt includes sodium hexafluoroaluminate.

4. The sodium ion battery electrolyte according to claim 1, characterized in that The organic solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

5. The sodium ion battery electrolyte according to claim 4, characterized in that: The organic solvent includes ethyl methyl carbonate, ethylene carbonate and propylene carbonate; The mass ratio of the ethyl methyl carbonate, the ethylene carbonate and the propylene carbonate is 2.1-4.0:1.5-3.0:1.5-3.

0.

6. The sodium ion battery electrolyte according to any one of claims 1 to 5, characterized in that: The film-forming additive includes one or more of fluoroethylene carbonate, vinylene carbonate, and 1,3-propylene sultone.

7. The sodium ion battery electrolyte according to claim 6, characterized in that: The film-forming additives include 1,3-propylene sultone and fluoroethylene carbonate; The mass ratio of the 1,3-propylene sultone to the fluoroethylene carbonate is 1-3:

1.

8. A sodium ion battery, characterized in that: It comprises the sodium ion battery electrolyte, positive electrode sheet and negative electrode sheet as described in any one of claims 1 to 7.

9. The sodium ion battery according to claim 8, characterized in that: At least one of the following conditions is met: A. The positive electrode active material in the positive electrode sheet includes a layered oxide; B. The negative electrode active material in the negative electrode plate includes hard carbon.

10. An electrical equipment, characterized in that: Including the sodium ion battery according to claim 9 or 8.

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