Sodium-ion battery electrolyte and sodium-ion battery

Abstract

The invention discloses a sodium battery electrolyte and a sodium ion battery, the sodium battery electrolyte comprises a non-aqueous organic solvent, a sodium salt and an oxamide derivative additive, the structural formula of the oxamide derivative additive is shown as a formula I or a formula II, # imgabs0 #, and R1-R2 are respectively and independently selected from one of-SO2F and-CH2CH2SO2F. The sodium-ion battery electrolyte can form a good protective film on an electrode material interface, meanwhile, the sodium ion conduction efficiency is remarkably improved, and the sodium-ion battery electrolyte has good stability under the high-voltage or high-temperature condition and has good compatibility with an electrode material, so that the high-temperature performance and the rate performance of a sodium-ion battery are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of secondary batteries, and particularly relates to a sodium battery electrolyte and a sodium-ion battery. Background Art

[0002] As a highly potential new electrochemical energy storage technology, sodium-ion batteries have significant advantages in that sodium resources are abundant and widely distributed in the earth's crust. Compared with lithium-ion batteries, their cost can be greatly reduced, which makes sodium-ion batteries show broad application prospects in large-scale energy storage fields, such as peak shaving of smart grids, distributed energy storage, etc. At the same time, in some fields sensitive to cost, such as low-speed electric vehicles and power tools, sodium-ion batteries are also expected to be an ideal choice for power sources. However, the current development of sodium-ion batteries still faces many challenges, and the insufficient performance of the electrolyte is one of the key factors restricting its further development. The specific manifestations are as follows: Poor stability of the electrode / electrolyte interface: During the charge and discharge process of sodium-ion batteries, complex physical and chemical reactions occur between the electrode and the electrolyte, resulting in an unstable electrode / electrolyte interface. For example, on the surface of the negative electrode, the insertion and extraction of sodium ions cause volume changes, damaging the originally formed solid electrolyte interface film (SEI film), so that the electrolyte continuously reacts with the electrode material in a side reaction, causing rapid attenuation of the battery capacity. On the surface of the positive electrode, due to the relatively high working potential, the electrolyte is easily oxidized to form an unstable positive electrode electrolyte interface film (CEI film), which also affects the performance and life of the battery.

[0003] Low ion conduction efficiency: The radius of sodium ions is relatively large, and their migration speed in the electrolyte is slower than that of lithium ions, which results in a lower ionic conductivity of the electrolyte. In addition, in the existing electrolyte systems, the interaction between the solvent and sodium ions is relatively strong, forming a relatively stable solvation sheath, which hinders the migration of sodium ions and further reduces the ion conduction efficiency, limiting the charge and discharge speed of the battery and making it difficult to meet the requirements of high-power application scenarios.

[0004] Narrow electrochemical window of the electrolyte: The commonly used sodium battery electrolytes currently have a relatively narrow electrochemical window and cannot meet the requirements of high-voltage positive electrode materials. When using high-voltage positive electrode materials, the electrolyte is easily oxidized and decomposed on the surface of the positive electrode, which will not only reduce the energy density of the battery, but also may produce by-products such as gas, resulting in an increase in the internal pressure of the battery and posing a safety hazard.

[0005] Poor compatibility with electrode materials: There is a poor compatibility between some electrolytes and specific electrode materials. For example, some electrolytes will react violently with the negative electrode material, resulting in the destruction of the electrode material structure; or an uneven interface film is formed on the surface of the positive electrode material, affecting the charge and discharge performance and cycle stability of the battery.

[0006] To solve the above problems, researchers are committed to developing new additives to optimize the performance of sodium battery electrolytes. However, existing additives still have certain limitations in improving the stability of the electrode / electrolyte interface and enhancing the ionic conduction efficiency, etc. Summary of the Invention

[0007] In view of the above problems, the object of the present invention is to provide a sodium battery electrolyte and a sodium ion battery. The sodium battery electrolyte can form a good protective film at the interface of the electrode material, significantly increase the sodium ion conduction efficiency at the same time, have good stability under high voltage or high temperature conditions, and have good compatibility with the electrode material, thereby improving the high-temperature performance and rate performance of the battery.

[0008] To achieve the above object, the present invention provides a sodium battery electrolyte, which includes a non-aqueous organic solvent, a sodium salt, and an oxamide derivative additive. The structural formula of the oxamide derivative additive is shown in Formula 1 or Formula 2,

[0009] wherein each of R1 to R2 is independently selected from one of -SO2F and -CH2CH2SO2F.

[0010] Compared with the prior art, the sodium battery electrolyte of the present invention uses the oxamide derivative shown in Formula 1 or Formula 2 as an additive. This oxamide derivative additive can form a stable cathode electrolyte interface film (CEI film) on the electrode surface, and the cyano group in this additive can participate in the construction of the SEI film, making the SEI film structure more stable, which prevents the further decomposition of the sodium battery electrolyte and improves the cycle stability of the sodium ion battery. In addition, the sulfonyl fluoride group in this additive helps to improve the conduction performance of sodium ions in the sodium battery electrolyte, increase the ion transference number, reduce the internal resistance of the electrolyte, thereby improving the charge and discharge efficiency and rate performance of the sodium ion battery. Moreover, the additive with this structure also has a certain stability, which can inhibit the decomposition of the sodium battery electrolyte under high voltage or high temperature conditions, maintain the stability of the sodium battery electrolyte system, reduce side reactions, and enhance the safety and reliability of the sodium ion battery under different working conditions. In addition, this oxamide derivative additive shows excellent compatibility with the sodium electrode and conventional non-aqueous organic solvents, which means that this additive can be evenly dispersed in the sodium battery electrolyte and play a stable role, while ensuring the normal and efficient operation of the battery without causing violent side reactions with the electrode material. Therefore, the sodium battery electrolyte of the present invention can form a good protective film at the interface of the electrode material, significantly increase the sodium ion conduction efficiency at the same time, have good stability under high voltage or high temperature conditions, and have good compatibility with the electrode material, thereby improving the high-temperature performance and rate performance of the battery.

[0011] Furthermore, the oxamide derivative additive of the present invention includes at least one of Compound 1 to Compound 4: 。

[0012] Furthermore, Compounds 1 to 4 of the present invention can be prepared according to the synthetic routes provided below, but are not limited thereto. In addition to the illustrated synthetic methods, other different synthetic routes can also be employed to obtain Compounds 1 to 4.

[0013]

[0014]

[0015]

[0016] 。

[0017] Furthermore, the mass percentage of the oxamide derivative additive of the present invention in the sodium battery electrolyte is 0.05 to 5%. Specifically, the mass percentage of the oxamide derivative additive in the sodium battery electrolyte can be, but is not limited to, 0.05%, 0.1%, 0.2%, 0.5%, 0.8%, 1.0%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 4.8%, 5%. Preferably, the mass percentage of the oxamide derivative additive in the sodium battery electrolyte is 0.1 to 2%.

[0018] Furthermore, the non-aqueous organic solvent of the present invention is selected from at least one of carbonates, ethers, and fluoroethers.

[0019] Furthermore, the non-aqueous organic solvent of the present invention is selected from at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), ethylene glycol dimethyl ether (DME), diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran (THF), furan, 1,3-dioxolane (DOL), 1,4-dioxane, and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether.

[0020] Furthermore, the mass percentage of the non-aqueous organic solvent of the present invention in the sodium battery electrolyte is 60 to 90%. Specifically, the mass percentage of the non-aqueous organic solvent of the present invention in the sodium battery electrolyte can be, but is not limited to, 60%, 65%, 68%, 70%, 75%, 78%, 80%, 82%, 85%, 88%, 90%.

[0021] Further, the sodium salt of the present invention is selected from at least one of sodium difluorooxalate borate (NaDFOB), sodium bis(oxalate) borate (NaBOB), sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethylsulfonyl)imide (NaTFSI), sodium trifluoromethanesulfonate (NaCF3SO3), sodium difluorophosphate (NaPO2F2), and sodium hexafluorophosphate (NaPF6).

[0022] Further, the mass percentage of the sodium salt of the present invention in the sodium-ion battery electrolyte is 8-20%. Specifically, the mass percentage of the sodium salt in the sodium-ion battery electrolyte can be, but is not limited to, 8%, 9%, 11%, 13%, 15%, 16%, 18%, 19%, 20%. Preferably, the mass percentage of the sodium salt in the sodium-ion battery electrolyte is 10-15%.

[0023] Correspondingly, the present invention also provides a sodium-ion battery, which includes a positive electrode and a negative electrode, and also includes the above-mentioned sodium-ion battery electrolyte. This sodium-ion battery has good high-temperature performance and rate performance.

[0024] Further, the charging cut-off voltage of the sodium-ion battery of the present invention is not less than 4.0V.

[0025] Further, the active material of the positive electrode of the present invention is selected from α-NaFeO2, NaCoO2, Na 0.7 [Fe 0.7 Mn 0.3 O2, Na(Mn 0.25 Fe 0.25 Co 0.25 Ni 0.25 )O2, NaMnO2, Na 0.5 [Fe 1 / 2 Mn 1 / 2 O 2、 Na 0.67 [Fe 1 / 2 Mn 1 / 2 O2, Na[Ni 0.35 Fe 0.4 Mn 0.25 O 2、 Na[Ni 0.3 Fe 0.45 Mn 0.25 O 2、 Na[Ni 0.25 Fe 0.5 Mn 0.25 O 2、 Na[Ni 0.2 Fe 0.55 Mn 0.25 O2, Na 0.67 [Mn 0.6 Ni 0.15 Fe0.25 O2, Na[Li 0.05 (Ni 0.25 Fe 0.25 Mn 0.5 ) 0.95 O2, Na2FePO4F, Na4Fe2(CN)6, NaNi 0.33 Fe 0.33 Mn 0.33 O2, NaFePO4, Na2FeP2O7, Na2MnPO4F, NaCoPO4, Na3V2(PO4)3, NaCrO2, Na2Fe2(SO4)3, or at least one of them. Preferably, the active material of the positive electrode is selected from NaNi 0.33 Fe 0.33 Mn 0.33 O2.

[0026] Furthermore, the active material of the negative electrode of the present invention is selected from soft carbon, hard carbon, sodium titanate, FeS x , Cu x O, MoS2, Sn x O, CoS x , Fe2O3, Fe3O4, ZnS, Sb, SbSn, or at least one of them. Specifically, FeS x can be FeS2 (pyrite) and FeS (ferrous sulfide); Cu x O can be Cu2O (cuprous oxide) and CuO (copper oxide); Sn x O can be SnO (tin monoxide) and SnO2 (tin dioxide); CoS x can be CoS (cobalt sulfide). Among them, soft carbon is amorphous carbon that can be graphitized at a high temperature above 2500°C; while hard carbon is difficult to be graphitized even after high-temperature treatment, thus showing stronger sodium storage capacity and lower working potential. Therefore, the active material of the negative electrode is preferably hard carbon. Specific Embodiments

[0027] To better illustrate the purpose, technical solution and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be noted that the methods described in the following embodiments are further explanatory descriptions of the present invention and should not be regarded as limitations of the present invention.

[0028] It should be noted that Compounds 1 to 4 used in the examples can be prepared according to the following preparation methods: Preparation of Compound 1: 10 g of oxamide and 5.7 g of triethylamine were added to 150 g of N,N-dimethylformamide. After stirring and mixing evenly, 6.0 g of triphenylphosphine (Pph3) was added under nitrogen protection. The temperature was lowered to 0 °C while stirring, and then 56.3 g of vinylsulfonyl fluoride was added dropwise. The temperature was then raised to 25 °C and the reaction was carried out for 20 h. The resulting reaction product was filtered, precipitated with ice water, recrystallized, and vacuum dried at 40 °C to obtain 21.1 g of Compound 1.

[0029] Preparation of Compound 2: 10 g of oxamide and 49.3 g of triethylamine were added to 150 g of N,N-dimethylformamide. After stirring and mixing evenly, 6.9 g of DBU and 3.0 g of bismuth trifluoride were added under nitrogen protection. The temperature was lowered to 0 °C while stirring, and then the gas in the reaction flask was replaced with sulfonyl fluoride gas. Then, it was continuously bubbled into the reaction solution and the reaction was carried out under stirring conditions. When the airbag on the reaction flask bulged, the introduction of sulfonyl fluoride gas was stopped, and the temperature was raised to 25 °C and the reaction was carried out for 12 h. The resulting reaction product was filtered, precipitated with ice water, recrystallized, and vacuum dried at 40 °C to obtain 19.64 g of Compound 2.

[0030] Preparation of Compound 3: 10 g of cyanamide and 5.8 g of 4-dimethylaminopyridine were added to anhydrous acetonitrile and stirred and mixed evenly. The temperature was lowered to 0 °C while stirring, and then 28.8 g of vinylsulfonyl fluoride was added dropwise. The temperature was then raised to 25 °C and the reaction was carried out for 15 h. The solvent of the resulting mixture was evaporated to dryness, and vacuum distillation was carried out at 125 °C to obtain 20.4 g of a colorless liquid intermediate. Then, 10 g of the intermediate was added to 150 g of N,N-dimethylformamide. The temperature was lowered to 0 °C under a nitrogen atmosphere, and then 6.95 g of sodium tert-butoxide was slowly added and stirred for 30 min. Then, the first mixture (prepared by dissolving 4.17 g of oxalyl chloride in 20 g of N,N-dimethylformamide) was added dropwise. After the addition was complete, the temperature was raised to 30 °C and the reaction was stirred for 10 h. The resulting reaction product was filtered, precipitated with ice water, recrystallized, and vacuum dried at 40 °C to obtain 8.14 g of Compound 3.

[0031] Preparation of Compound 4: 10.0 g of cyanamide and 26.45 g of triethylamine were added to anhydrous acetonitrile. After stirring and mixing evenly, 2.9 g of 4-dimethylaminopyridine and 3.16 g of bismuth trifluoride were added and stirred and mixed evenly. Then, while stirring, the temperature was lowered to 0 °C, and the gas in the reaction flask was replaced with sulfuryl fluoride gas. Then, it was continuously bubbled into the solution and reacted under stirring conditions. When the airbag on the reaction flask bulged, the introduction of sulfuryl fluoride gas was stopped, and the temperature was raised to 25 °C for reaction for 12 h. Then, the solvent of the obtained mixture was evaporated to dryness, dissolved in dichloromethane, washed with water, dried, and the dichloromethane was rotary-evaporated to obtain 14.2 g of intermediate; then 10 g of the intermediate was added to 150 g of N,N-dimethylformamide and stirred and mixed evenly. Then, while cooling to 0 °C under a nitrogen atmosphere, 8.53 g of sodium tert-butoxide was slowly added and stirred for reaction for 30 min. Then, the first mixture (prepared by dissolving 5.12 g of oxalyl chloride in 20 g of N,N-dimethylformamide) was added dropwise. After the addition was completed, the temperature was raised to 30 °C and stirred for reaction for 10 h. Then, the obtained reaction product was filtered, precipitated with ice water, recrystallized, and vacuum-dried at 40 °C to obtain 10.53 g of compound 4.

[0032] Example 1 1.1 Preparation of Sodium Battery Electrolyte In a glove box filled with nitrogen (O2 < 1 ppm, H2O < 1 ppm), 26 g of diethyl carbonate (DEC) and 50 g of ethyl methyl carbonate (EMC) were mixed evenly, and then 10 g of diethylene glycol dimethyl ether was added to obtain 86 g of a mixed solvent as a non-aqueous organic solvent. Then, 1.5 g of compound 1 was added. The mixed solution was sealed and packed and placed in a freezer (-4 °C) for 2 h and then taken out. In a glove box filled with nitrogen (O2 < 1 ppm, H2O < 1 ppm), 12.5 g of sodium hexafluorophosphate (NaPF6) was slowly added to the mixed solution. After mixing evenly, the sodium battery electrolyte was prepared.

[0033] 1.2 Preparation of Positive Electrode Sheet NaNi 0.33 Fe 0.33 Mn 0.33 O2, binder PVDF, and conductive agent SuperP were mixed evenly according to a mass ratio of 95:1:4 to form a positive electrode paste with a certain viscosity. After the prepared paste was coated on both sides of the aluminum foil, it was dried and roll-pressed to obtain a positive electrode sheet.

[0034] 1.3 Preparation of Negative Electrode Sheet The negative electrode active material hard carbon, conductive agent Ketjenblack, binder styrene-butadiene rubber, and thickener carboxymethyl cellulose sodium (CMC) were fully stirred and mixed evenly in a deionized water solvent system according to a mass ratio of 96:2:1:1, and then coated on the copper foil, dried, and cold-pressed to obtain a negative electrode sheet.

[0035] 1.4 Preparation of Sodium Ion Battery The positive electrode sheet, separator, and negative electrode sheet are wound to form a soft-pack battery cell, which is packaged with a polymer aluminum-plastic film and filled with the sodium-ion battery electrolyte prepared above. After processes such as formation and grading, a sodium-ion battery with a capacity of 1400 mAh is made.

[0036] The formulations of the sodium-ion battery electrolytes in Examples 1-8 and Comparative Example 1 are shown in Table 1. The steps for preparing the sodium-ion battery electrolytes and sodium-ion batteries in Examples 2-8 and Comparative Example 1 are the same as those in Example 1.

[0037] Table 1 Formulations of Sodium-Ion Battery Electrolytes in Each Example and Comparative Example

[0038] The sodium-ion batteries prepared in Examples 1-8 and Comparative Example 1 were respectively subjected to high-temperature storage performance tests, high-temperature cycle tests, and rate performance tests according to the following specific test conditions. The performance test results are shown in Table 2.

[0039] High-temperature storage test of sodium-ion battery: Under normal temperature (25 °C) conditions, the sodium-ion battery is charged and discharged once at 0.5C / 0.5C (the battery discharge capacity is recorded as C0), and the upper limit voltage is 4.0V; the battery is placed in an oven at 60 °C for 30 days, taken out, placed in an environment at 25 °C, and discharged at 0.5C. The discharge capacity is recorded as C1; then the sodium-ion battery is charged and discharged once at 0.5C / 0.5C (the battery discharge capacity is recorded as C2); Capacity retention rate = (C1 / C0) × 100% Capacity recovery rate = (C2 / C0) × 100%.

[0040] High-temperature cycle test of sodium-ion battery: The sodium-ion battery is placed in a constant-temperature oven at 45 °C and left standing for 30 minutes to make the sodium-ion battery reach a constant temperature. It is charged at a constant current of 1C until the voltage reaches 4.0V, then charged at a constant voltage of 4.0V until the current reaches 0.05C, and then discharged at a constant current of 1C until the voltage reaches 2.0V. The first-cycle discharge capacity of the battery is recorded. This is one charge-discharge cycle. Such cycles are carried out 400 times, and the discharge capacity of the first cycle and the last cycle are recorded. The capacity retention rate is calculated according to the following formula; Capacity retention rate = Discharge capacity of the last cycle / Discharge capacity of the first cycle × 100%.

[0041] Rate performance test of sodium-ion battery: Charge the sodium-ion battery at a constant current of 0.5C to 4.0V at 25°C, then charge it at a constant voltage until the current reaches 0.05C, and then discharge it at a constant current of 0.5C to 2.0V. This is one charge-discharge cycle. Repeat the charge-discharge process 3 times. The discharge capacity of the last cycle is C0. Then charge it at a constant current of 0.5C to 4.0V, then charge it at a constant voltage until the current reaches 0.05C, and then discharge it at a constant current of 5C to 2.0V. The discharge capacity is C1; Capacity retention rate = C1 / C0 × 100%.

[0042] Table 2 Performance test results of sodium-ion batteries

[0043] As can be seen from Table 2, compared with Comparative Example 1, the sodium-ion batteries of Examples 1-8 have better high-temperature performance and rate performance. This is because the sodium-ion battery electrolyte of the present invention uses an oxamide derivative shown in Formula 1 or Formula 2 as an additive. This oxamide derivative additive can form a stable cathode electrolyte interface film (CEI film) on the electrode surface, and the cyano group in this additive can participate in the construction of the SEI film, making the SEI film structure more stable, which prevents the further decomposition of the sodium-ion battery electrolyte and improves the cycle stability of the sodium-ion battery. In addition, the sulfonyl fluoride group in this additive helps to improve the conduction performance of sodium ions in the sodium-ion battery electrolyte, increase the ion transference number, and reduce the internal resistance of the electrolyte, thereby improving the charge-discharge efficiency and rate performance of the sodium-ion battery. Furthermore, the additive with this structure also has a certain stability, which can inhibit the decomposition of the sodium-ion battery electrolyte under high voltage or high temperature conditions, maintain the stability of the sodium-ion battery electrolyte system, reduce side reactions, and enhance the safety and reliability of the sodium-ion battery under different working conditions. In addition, this oxamide derivative additive shows excellent compatibility with the sodium electrode and conventional non-aqueous organic solvents, which means that this additive can be evenly dispersed in the sodium-ion battery electrolyte and play a stable role, while ensuring the normal and efficient operation of the battery without causing violent side reactions with the electrode material. Therefore, the sodium-ion batteries of the present invention have good high-temperature performance and rate performance.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it is not limited to only the embodiments listed. Those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A sodium battery electrolyte, characterized in that, It includes a non-aqueous organic solvent, a sodium salt, and an oxamide derivative additive, and the structural formula of the oxamide derivative additive is shown in Formula 1 or Formula 2, wherein each of R1 to R2 is independently selected from one of -SO2F and -CH2CH2SO2F.

2. The sodium battery electrolyte according to claim 1, characterized in that, The oxamide derivative additive includes at least one of Compound 1 to Compound 4: 。 3. The sodium-ion battery electrolyte according to claim 1, wherein, The mass percentage of the oxamide derivative additive in the sodium-ion battery electrolyte is 0.05% to 5%.

4. The sodium-ion battery electrolyte according to claim 1, characterized in that, The non-aqueous organic solvent is selected from at least one of carbonates, ethers, and fluoroethers.

5. The sodium-ion battery electrolyte according to claim 4, wherein The non-aqueous organic solvent is selected from at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, furan, 1,3-dioxolane, 1,4-dioxane, and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether.

6. The sodium battery electrolyte according to claim 1, wherein, The sodium salt is selected from at least one of sodium difluorooxalate borate, sodium bis(oxalato)borate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethylsulfonyl)imide, sodium trifluoromethanesulfonate, sodium difluorophosphate, and sodium hexafluorophosphate.

7. A sodium-ion battery, comprising a positive electrode and a negative electrode, characterized in that, It also includes a sodium-ion battery electrolyte according to any one of claims 1 to 6.

8. The sodium ion battery according to claim 7, wherein, Its charging cut-off voltage is not less than 4.0V.

9. The sodium ion battery according to claim 7, characterized in that, The active material of the positive electrode is selected from at least one of α-NaFeO2, NaCoO2, Na 0.7 [Fe 0.7 Mn 0.3 O2, Na(Mn 0.25 Fe 0.25 Co 0.25 Ni 0.25 )O2, NaMnO2, Na 0.5 [Fe 1 / 2 Mn 1 / 2 O 2、 Na 0.67 [Fe 1 / 2 Mn 1 / 2 O2, Na[Ni 0.35 Fe 0.4 Mn 0.25 O 2、 Na[Ni 0.3 Fe 0.45 Mn 0.25 O 2、 Na[Ni 0.25 Fe 0.5 Mn 0.25 O 2、 Na[Ni 0.2 Fe 0.55 Mn 0.25 O2, Na 0.67 [Mn 0.6 Ni 0.15 Fe 0.25 O2, Na[Li 0.05 (Ni 0.25 Fe 0.25 Mn 0.5 ) 0.95 O2, Na2FePO4F, Na4Fe2(CN)6, NaNi 0.33 Fe 0.33 Mn 0.33 O2, NaFePO4, Na2FeP2O7, Na2MnPO4F, NaCoPO4, Na3V2(PO4)3, NaCrO2, Na2Fe2(SO4)3.

10. The sodium-ion battery according to claim 7, characterized in that, The active material of the negative electrode is selected from at least one of soft carbon, hard carbon, sodium titanate, FeS x , Cu x O, MoS2, Sn x O, CoS x , Fe2O3, Fe3O4, ZnS, Sb, SbSn.

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