Cyanosulfonate additive and application thereof in sodium ion battery

Abstract

The invention discloses a cyano sulfonate additive and an application of the cyano sulfonate additive in a sodium-ion battery electrolyte, and belongs to the technical field of battery electrolyte additives. The structural formula of the cyano sulfonate additive is as shown in (I). The cyano group in the cyano sulfonate additive can participate in sodium ion coordination, and a stable interfacial film rich in inorganic components is derived. The cyano sulfonate can also react with nucleophilic species in the electrolyte, so that the reaction of the nucleophilic species and the electrolyte is inhibited, the gas production is effectively reduced, and the cycle stability of the battery is improved.

Description

Technical Field

[0001] This invention belongs to the field of battery electrolyte additive technology, specifically relating to a cyanosulfonate additive and its application in sodium-ion battery electrolytes. Background Technology

[0002] Sodium-ion batteries, with their high cost-effectiveness, abundant resources, and excellent low-temperature performance, have become a potential alternative technology to lithium-ion batteries in the field of electrochemical energy storage. However, their commercial application is still severely constrained by safety issues, among which gas production is particularly prominent and differs significantly from that of lithium-ion batteries. Gas production in lithium-ion batteries is mainly related to electrolyte decomposition, especially under extreme conditions such as overcharging, overheating, or short circuits, where solvents and additives in the electrolyte decompose to produce large amounts of flammable gases such as CO2, C2H4, and C2H6. In contrast, gas production in sodium-ion batteries mainly originates from the instability of the cathode material, side reactions between the electrode and the electrolyte, and the decomposition of the electrolyte under high temperature / high pressure, producing gases such as CO2, H2, and O2.

[0003] Currently, the most commonly used cathode material in commercial sodium-ion batteries is layered transition metal oxide, whose structure is similar to that of similar cathodes in lithium-ion batteries. Because Na... + The ionic radius is greater than that of Li + During the insertion and extraction processes, layered structure rearrangement or collapse is more likely to occur, leading to lattice oxygen escape and the dissolution of high-valence transition metal ions. Both of these can cause side reactions with the electrolyte, resulting in decreased electrochemical performance, capacity decay, and gas generation. In addition, during sintering, some sodium ions cannot enter the bulk phase and accumulate on the surface, reacting with water and CO2 to generate CO3. 2- and OH - This process forms residual alkalis such as Na2CO3 and NaOH on the surface. During battery cycling, these residual alkalis react with trace amounts of HF in the electrolyte to generate CO2, causing the battery to expand and potentially leading to safety issues.

[0004] Therefore, optimizing electrolyte properties is the core strategy for reducing the risk of gas generation in sodium-ion batteries, and the introduction of electrolyte additives is particularly crucial. Suitable additives can form a dense and stable protective film on the surface of electrode materials, effectively isolating the electrolyte from direct contact with the electrode materials, inhibiting electrolyte decomposition, and reducing gas generation caused by side reactions, thereby significantly improving the cycle stability and safety performance of the battery. Summary of the Invention

[0005] To address the problem of gas generation in sodium-ion batteries during cycling and use, this invention proposes a cyanosulfonate additive and its application in sodium-ion battery electrolytes.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows: This invention provides a cyanosulfonate compound having the structure shown in formula (Ⅰ): , Wherein, R1 is one of the CH3, CH2CH3, CF3, CH2CF3, C2F5, Ph, PhMe groups; R2 is one of the cyanoalkyl alkanes and cyanobenzenes with 2-5 carbon atoms.

[0007] Furthermore, R2 is selected from any of the following groups: .

[0008] The present invention provides a method for preparing the cyanosulfonate compounds, comprising the following steps: firstly, dissolving a hydroxynitrile compound and a catalyst in an organic solvent to obtain a mixed solution, then adding the mixed solution dropwise to a solution of a sulfonic anhydride compound to carry out the reaction, and obtaining the cyanosulfonate compounds after washing, separation, drying, filtration and rotary evaporation.

[0009] The molar ratio of the hydroxynitrile compound, the sulfonic anhydride compound, and the catalyst is 1:1-1.1:1-1.1.

[0010] The hydroxynitrile compounds are selected from any one of aliphatic hydroxynitriles and hydroxybenzonitriles having 2-5 carbon atoms; the sulfonic anhydride compounds are selected from any one of methanesulfonic anhydride, ethanesulfonic anhydride, trifluoromethanesulfonic anhydride, trifluoroethanesulfonic anhydride, benzenesulfonic anhydride, and p-toluenesulfonic anhydride.

[0011] The catalyst is selected from any one of triethylamine, N-methylmorpholine, pyridine, ethylenediamine, and N,N-diisopropylethylamine; the organic solvent is selected from any one of dichloromethane, acetonitrile, 2-methyltetrahydrofuran, and cyclopentyl methyl ether.

[0012] This invention provides the application of the aforementioned cyanosulfonate compounds in sodium-ion battery electrolytes.

[0013] The present invention also provides a sodium-ion battery electrolyte, comprising a sodium salt, an organic solvent, and the aforementioned cyanosulfonate compound additive.

[0014] The sodium salt is selected from at least one of sodium hexafluorophosphate, sodium tetrafluoroborate, sodium difluorooxalate borate, sodium bis(trifluoromethanesulfonyl)imide, and sodium di(fluorosulfonyl)imide; the organic solvent is at least one of propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and fluoroethylene carbonate; the volume fraction of the cyanosulfonate compound additive is 0.1%-10%.

[0015] The reaction mechanism between the cyanosulfonate and the nucleophile in the electrolyte used in this invention is as follows: Figure 1As shown, cyanosulfonate undergoes an SN2 nucleophilic substitution reaction under the attack of the nucleophile Nu, resulting in the departure of the alkyl sulfonate group and the formation of the NuCH2CH2CN compound. The nucleophile Nu loses its catalytic activity.

[0016] The present invention has the following beneficial effects: 1. In the cyanosulfonate additives prepared by this invention, the cyano functional group reacts with Na... + It has strong coordination ability, preferentially replaces carbonate solvents, and enters the Na+ process. + The first solvation shell promotes the formation of anion-rich solvation structures, and the anions preferentially decompose to generate inorganic components such as NaF, NaO, and Na3N, which have higher chemical stability and mechanical strength, significantly improving the stability of the electrode-electrolyte interface. Simultaneously, the cyano functional group can coordinate with transition metal ions, effectively inhibiting transition metal dissolution and preventing gas generation in the electrolyte due to transition metal catalytic decomposition. The sulfonate functional group is easy to leave, making it easy for cyanosulfonate compounds to undergo nucleophilic substitution reactions with active oxygen generated during the phase transition of the cathode material, as well as residual hydroxide and carbonate ions on the cathode surface. This inhibits the oxidative decomposition of the electrolyte and blocks the reaction pathway between residual alkali on the cathode surface and hydrofluoric acid, fundamentally reducing the risk of gas generation.

[0017] 2. The preparation method of this invention uses sulfonic anhydride compounds with low reactivity and readily available hydroxynitriles as substrates to synthesize sulfonate compounds in one step. It has the advantages of simple synthesis process, safe operation and high product purity. When applied to sodium-ion secondary batteries, it exhibits excellent electrochemical performance and has broad prospects for industrial application. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a diagram illustrating the reaction mechanism between cyanosulfonate and nucleophiles in the electrolyte.

[0020] Figure 2 The 1H NMR spectrum of the compound prepared in Example 1.

[0021] Figure 3 The cycling performance of the batteries with the electrolyte prepared in Example 1 and the electrolyte obtained in Comparative Example 1 is shown in the graph. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Unless otherwise specified, the experimental methods used in the following experimental examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0024] Example 1 A method for preparing a cyanosulfonate compound, the synthetic route is as follows: The specific steps are as follows: At room temperature, triethylamine (105 mmol, 10.6 g) and 3-hydroxypropionitrile (105 mmol, 7.4 g) were added separately to 50 mL of dichloromethane (DCM) solution. Then, the above solution was slowly added dropwise to a DCM solution of methanesulfonic anhydride (100 mmol, 17.4 g) (40 mL), and the reaction was carried out at room temperature for 24 h. After the reaction was complete, the mixture was washed three times with water, then separated. The lower layer was dried over anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain the final product (86 mmol, 12.8 g, yield: 86%).

[0025] The reaction products were characterized by proton nuclear magnetic resonance spectroscopy, and the results are as follows: Figure 2 As shown, the results are as follows: 1 H NMR(400MHz, CDCl3): δ(ppm): 4.36ppm(t, 2H, O CH 2 CH2CN), 3.06ppm (s, 3H, CH 3 SO3), 2.81ppm (t, 2H, OCH2) CH 2 CN).

[0026] Example 2 A method for preparing a cyanosulfonate compound, the synthetic route is as follows: The specific steps are as follows: At room temperature, triethylamine (105 mmol, 10.6 g) and 3-hydroxypropionitrile (105 mmol, 7.4 g) were added separately to 50 mL of dichloromethane (DCM) solution. Then, the above solution was slowly added dropwise to a DCM solution of trifluoromethanesulfonic anhydride (100 mmol, 28.2 g) (40 mL) at -78 °C, and the temperature was gradually raised to room temperature for 24 h. After the reaction was complete, the mixture was washed three times with water, then separated. The lower layer was dried over anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain the final product (73 mmol, 14.8 g, yield: 73%).

[0027] The reaction products were characterized by proton nuclear magnetic resonance (NMR) spectroscopy, and the results are as follows: 1 H NMR (400MHz, CDCl3): δ(ppm): 3.85ppm (t, 2H, O CH 2 CH2CN), 2.63ppm (t, 2H, OCH2 CH 2 CN).

[0028] Example 3 A method for preparing a cyanosulfonate compound, the synthetic route is as follows: The specific steps are as follows: At room temperature, triethylamine (105 mmol, 10.6 g) and 3-hydroxypropionitrile (105 mmol, 7.4 g) were added separately to 50 mL of dichloromethane (DCM) solution. Then, the above solution was slowly added dropwise to a DCM solution of p-toluenesulfonic anhydride (100 mmol, 32.6 g) (40 mL) at -78 °C, and the temperature was gradually raised to room temperature for 24 h. After the reaction was complete, the mixture was washed three times with water, then separated. The lower layer was dried over anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain the final product (78 mmol, 17.6 g, yield: 78%).

[0029] The reaction products were characterized by proton nuclear magnetic resonance (NMR) spectroscopy, and the results are as follows: 1 H NMR (400MHz, CDCl3): δ(ppm): 7.75ppm (d, 2H, Me Ph SO3), 7.41ppm (d, 2H, Me Ph SO3), 3.92ppm (t, 2H,O CH 2 CH2CN), 2.58ppm (t, 2H, OCH2 CH 2CN), 2.43ppm (s, 3H, Me PhSO3).

[0030] Example 4 A method for preparing a cyanosulfonate compound, the synthetic route is as follows: The specific steps are as follows: At room temperature, triethylamine (105 mmol, 10.6 g) and o-hydroxyphenyl cyanide (105 mmol, 11.9 g) were added separately to 50 mL of dichloromethane (DCM) solution. Then, the above solution was slowly added dropwise to a DCM solution of p-toluenesulfonic anhydride (100 mmol, 17.4 g) (40 mL), and the mixture was gradually heated to room temperature for 24 h. After the reaction was complete, the mixture was washed three times with water, then separated. The lower layer was dried over anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain the final product (83 mmol, 16.4 g, yield: 83%).

[0031] The reaction products were characterized by proton nuclear magnetic resonance (NMR) spectroscopy, and the results are as follows: 1 H NMR (400MHz, CDCl3): δ(ppm): 7.68-7.41ppm (m, 4H, CN Ph SO3Me), 3.52ppm (s, 3H, CNPhSO3 Me ).

[0032] Example 5 A method for preparing a cyanosulfonate compound, the synthetic route is as follows: The specific steps are as follows: At room temperature, triethylamine (105 mmol, 10.6 g) and o-hydroxyphenyl cyanide (105 mmol, 11.9 g) were added separately to 50 mL of dichloromethane (DCM) solution. Then, the above solution was slowly added dropwise to a DCM solution of trifluoromethanesulfonic anhydride (100 mmol, 28.2 g) in 40 mL at -78 °C, and the temperature was gradually raised to room temperature for 24 h. After the reaction was complete, the mixture was washed three times with water, then separated. The lower layer was dried over anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain the final product (75 mmol, 18.8 g, yield: 75%).

[0033] The reaction products were characterized by proton nuclear magnetic resonance (NMR) spectroscopy, and the results are as follows: 1 H NMR (400MHz, CDCl3): δ(ppm): 7.73-7.45ppm (m, 4H, CN Ph SO3CF3).

[0034] Application Example 1 Using the compound prepared in Example 1 as an electrolyte additive and in the preparation of sodium-ion batteries The specific method is as follows: (1) Electrolyte preparation: In an argon glove box, an electrolyte was prepared by preparing 15g of ethylene carbonate, 15g of propylene carbonate, 70g of methyl ethyl carbonate, 17g of sodium hexafluorophosphate, 0.2g of fluoroethylene carbonate, and the cyanosulfonate additive prepared in Example 1.

[0035] (2) Preparation of pouch cell: The positive electrode material used in this application example is sodium nickel iron manganese oxide (NaNi). 1 / 3 Fe 1 / 3 Mn 1 / The sodium-ion soft-pack battery is made from materials such as 3O2, NFM, hard carbon (HC), conductive agent (Super-P), conductive carbon nanotubes (CNT), polyvinylidene fluoride (PVDF), N-methylpyrrolidone (NMP), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), and separator, all of which are directly purchased and undergo no further processing except for necessary drying. A mixed slurry of NFM, Super-P, PVDF, and CNT in a mass ratio of 96:1.5:2:0.5 is uniformly coated onto aluminum foil, and a mixed slurry of HC, Super-P, CMC, SBR, and CNT in a mass ratio of 92:2.5:2:3:0.5 is also uniformly coated onto aluminum foil. After drying, rolling, die-cutting, stacking, electrolyte injection, and encapsulation, the sodium-ion soft-pack battery is obtained.

[0036] Application Example 2 Using the compound prepared in Example 2 as an electrolyte additive and in the preparation of sodium-ion batteries The specific method is as follows: (1) Electrolyte preparation: In an argon glove box, an electrolyte was prepared by preparing 15g of ethylene carbonate, 15g of propylene carbonate, 70g of methyl ethyl carbonate, 17g of sodium hexafluorophosphate, 0.2g of fluoroethylene carbonate and the cyanosulfonate additive prepared in Example 2.

[0037] (2) Preparation of pouch cell: The positive electrode material used in this application example is sodium nickel iron manganese oxide (NaNi). 1 / 3 Fe 1 / 3 Mn 1 / The sodium-ion soft-pack battery is made from materials such as 3O2, NFM, hard carbon (HC), conductive agent (Super-P), conductive carbon nanotubes (CNT), polyvinylidene fluoride (PVDF), N-methylpyrrolidone (NMP), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), and separator, all of which are directly purchased and undergo no further processing except for necessary drying. A mixed slurry of NFM, Super-P, PVDF, and CNT in a mass ratio of 96:1.5:2:0.5 is uniformly coated onto aluminum foil, and a mixed slurry of HC, Super-P, CMC, SBR, and CNT in a mass ratio of 92:2.5:2:3:0.5 is also uniformly coated onto aluminum foil. After drying, rolling, die-cutting, stacking, electrolyte injection, and encapsulation, the sodium-ion soft-pack battery is obtained.

[0038] Application Example 3 Using the compound prepared in Example 3 as an electrolyte additive and in the preparation of sodium-ion batteries The specific method is as follows: (1) Electrolyte preparation: In an argon glove box, an electrolyte was prepared by preparing 15g of ethylene carbonate, 15g of propylene carbonate, 70g of methyl ethyl carbonate, 17g of sodium hexafluorophosphate, 0.2g of fluoroethylene carbonate and the cyanosulfonate additive prepared in Example 3.

[0039] (2) Preparation of pouch cell: The positive electrode material used in this application example is sodium nickel iron manganese oxide (NaNi). 1 / 3 Fe 1 / 3 Mn 1 / The sodium-ion soft-pack battery is made from materials such as 3O2, NFM, hard carbon (HC), conductive agent (Super-P), conductive carbon nanotubes (CNT), polyvinylidene fluoride (PVDF), N-methylpyrrolidone (NMP), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), and separator, all of which are directly purchased and undergo no further processing except for necessary drying. A mixed slurry of NFM, Super-P, PVDF, and CNT in a mass ratio of 96:1.5:2:0.5 is uniformly coated onto aluminum foil, and a mixed slurry of HC, Super-P, CMC, SBR, and CNT in a mass ratio of 92:2.5:2:3:0.5 is also uniformly coated onto aluminum foil. After drying, rolling, die-cutting, stacking, electrolyte injection, and encapsulation, the sodium-ion soft-pack battery is obtained.

[0040] Application Example 4 Using the compound prepared in Example 4 as an electrolyte additive and in the preparation of sodium-ion batteries The specific method is as follows: (1) Electrolyte preparation: In an argon glove box, an electrolyte was prepared by preparing 15g of ethylene carbonate, 15g of propylene carbonate, 70g of methyl ethyl carbonate, 17g of sodium hexafluorophosphate, 0.2g of fluoroethylene carbonate, and the cyanosulfonate additive prepared in Example 4.

[0041] (2) Preparation of pouch cell: The positive electrode material used in this application example is sodium nickel iron manganese oxide (NaNi). 1 / 3 Fe 1 / 3 Mn 1 / The sodium-ion soft-pack battery is made from materials such as 3O2, NFM, hard carbon (HC), conductive agent (Super-P), conductive carbon nanotubes (CNT), polyvinylidene fluoride (PVDF), N-methylpyrrolidone (NMP), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), and separator, all of which are directly purchased and undergo no further processing except for necessary drying. A mixed slurry of NFM, Super-P, PVDF, and CNT in a mass ratio of 96:1.5:2:0.5 is uniformly coated onto aluminum foil, and a mixed slurry of HC, Super-P, CMC, SBR, and CNT in a mass ratio of 92:2.5:2:3:0.5 is also uniformly coated onto aluminum foil. After drying, rolling, die-cutting, stacking, electrolyte injection, and encapsulation, the sodium-ion soft-pack battery is obtained.

[0042] Application Example 5 Using the compound prepared in Example 5 as an electrolyte additive and in the preparation of sodium-ion batteries The specific method is as follows: (1) Electrolyte preparation: In an argon glove box, an electrolyte was prepared by preparing 15g of ethylene carbonate, 15g of propylene carbonate, 70g of methyl ethyl carbonate, 17g of sodium hexafluorophosphate, 0.2g of fluoroethylene carbonate, and the cyanosulfonate additive prepared in Example 5.

[0043] (2) Preparation of pouch cell: The positive electrode material used in this application example is sodium nickel iron manganese oxide (NaNi). 1 / 3 Fe 1 / 3 Mn 1 / The sodium-ion soft-pack battery is made from materials such as 3O2, NFM, hard carbon (HC), conductive agent (Super-P), conductive carbon nanotubes (CNT), polyvinylidene fluoride (PVDF), N-methylpyrrolidone (NMP), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), and separator, all of which are directly purchased and undergo no further processing except for necessary drying. A mixed slurry of NFM, Super-P, PVDF, and CNT in a mass ratio of 96:1.5:2:0.5 is uniformly coated onto aluminum foil, and a mixed slurry of HC, Super-P, CMC, SBR, and CNT in a mass ratio of 92:2.5:2:3:0.5 is also uniformly coated onto aluminum foil. After drying, rolling, die-cutting, stacking, electrolyte injection, and encapsulation, the sodium-ion soft-pack battery is obtained.

[0044] Comparative Example The preparation method of the electrolyte without cyanosulfonate additives and the fabrication method of the sodium-ion battery are as follows: (1) Electrolyte preparation: In an argon glove box, an electrolyte was prepared with the following composition: 15g ethylene carbonate, 15g propylene carbonate, 70g methyl ethyl carbonate, 17g sodium hexafluorophosphate, and 0.2g fluoroethylene carbonate.

[0045] (2) Preparation of pouch cell: The positive electrode material used in this application example is sodium nickel iron manganese oxide (NaNi). 1 / 3 Fe 1 / 3 Mn 1 / The sodium-ion soft-pack battery is made from materials such as 3O2, NFM, hard carbon (HC), conductive agent (Super-P), conductive carbon nanotubes (CNT), polyvinylidene fluoride (PVDF), N-methylpyrrolidone (NMP), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), and separator, all of which are directly purchased and undergo no further processing except for necessary drying. A mixed slurry of NFM, Super-P, PVDF, and CNT in a mass ratio of 96:1.5:2:0.5 is uniformly coated onto aluminum foil, and a mixed slurry of HC, Super-P, CMC, SBR, and CNT in a mass ratio of 92:2.5:2:3:0.5 is also uniformly coated onto aluminum foil. After drying, rolling, die-cutting, stacking, electrolyte injection, and encapsulation, the sodium-ion soft-pack battery is obtained.

[0046] Implementation Results Example The performance of the sodium-ion batteries prepared for use cases 1-5 and the comparative example was tested as follows: The room-temperature cycling performance and gas production of sodium-ion batteries were tested using the following method: At room temperature (25℃), the batteries were charged to 3.9 V using a constant current and constant voltage of 1 C (1 A), with a cutoff current of 0.05 C. After being fully charged and allowed to rest for 10 minutes, the batteries were discharged to 2.0 V using a constant current of 1 C and allowed to rest for 10 minutes. This cycle was repeated 200 times. The capacity retention rate after cycling was calculated as (discharge capacity after 200 cycles / initial discharge capacity) × 100%.

[0047] The volume of the soft-pack battery before and after cycling was tested using the water displacement method. First, the mass of the battery was weighed using a balance. m Then, immerse the battery in a beaker filled with water, ensuring that the battery does not touch the beaker wall. Place a dynamometer above the beaker and record the pulling force after the battery is fully submerged in water. F According to Archimedes' principle, the buoyant force on an object immersed in a still fluid is equal to the weight of the fluid displaced by the object. ρVg = mg - F The volume of the battery can be calculated from this. V .

[0048] The cycle performance and gas production test results of the sodium-ion batteries are shown in Table 1 below. Figure 3 The graph shows the cycle performance of the batteries with the electrolyte prepared in Example 1 and the electrolyte obtained in Comparative Example 1. It can be seen that the cycle performance of the electrolyte with the compound prepared in Example 1 is significantly better than that of Comparative Example 1.

[0049] Table 1. Cycle performance and gas production test results of sodium-ion batteries prepared for use cases 1-5 and the comparative example. As can be seen from the data in Table 1, adding cyanosulfonate additives to the electrolyte can improve the cycle performance of sodium-ion batteries and reduce gas production during cycling. When the additive prepared in Example 1 is added, after 200 cycles at room temperature, the capacity retention of the sodium-ion battery can reach as high as 91.2%, which is much higher than that of the sodium-ion battery without additives (66.1%), and the gas production after cycling also decreases from 11.5 mL to 2.1 mL.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cyanosulfonate compound, characterized in that, The cyanosulfonate compounds have the structure shown in formula (Ⅰ): ， Wherein, R1 is one of the CH3, CH2CH3, CF3, CH2CF3, C2F5, Ph, PhMe groups; R2 is one of the cyanoalkyl alkanes and cyanobenzenes with 2-5 carbon atoms.

2. The cyanosulfonate compound according to claim 1, characterized in that, R2 is selected from any of the following groups: 。 3. The method for preparing the cyanosulfonate compound according to claim 1 or 2, characterized in that, The process includes the following steps: First, a hydroxynitrile compound and a catalyst are dissolved in an organic solvent to obtain a mixed solution. Then, the mixed solution is added dropwise to a solution of a sulfonic anhydride compound to carry out the reaction. After washing, separation, drying, filtration, and rotary evaporation, a cyanosulfonate compound is obtained.

4. The preparation method according to claim 3, characterized in that: The molar ratio of the hydroxynitrile compound, the sulfonic anhydride compound, and the catalyst is 1:1-1.1:1-1.

1.

5. The preparation method according to claim 4, characterized in that: The hydroxynitrile compounds are selected from any one of aliphatic hydroxynitriles and hydroxybenzonitriles with 2-5 carbon atoms.

6. The preparation method according to claim 5, characterized in that: The sulfonic anhydride compounds are selected from any one of methanesulfonic anhydride, ethanesulfonic anhydride, trifluoromethanesulfonic anhydride, trifluoroethanesulfonic anhydride, benzenesulfonic anhydride, and p-toluenesulfonic anhydride.

7. The preparation method according to claim 6, characterized in that: The catalyst is selected from any one of triethylamine, N-methylmorpholine, pyridine, ethylenediamine, and N,N-diisopropylethylamine; the organic solvent is selected from any one of dichloromethane, acetonitrile, 2-methyltetrahydrofuran, and cyclopentyl methyl ether.

8. The use of the cyanosulfonate compound according to any one of claims 1 or 2 in sodium-ion battery electrolytes.

9. A sodium-ion battery electrolyte, characterized in that: The sodium salts, organic solvents, and cyanosulfonate compounds as described in claim 1 or 2 are included as additives.

10. A sodium-ion battery electrolyte according to claim 9, characterized in that: The sodium salt is selected from at least one of sodium hexafluorophosphate, sodium tetrafluoroborate, sodium difluorooxalate borate, sodium bis(trifluoromethylsulfonyl)imide, and sodium bis(fluorosulfonyl)imide; the organic solvent is at least one of propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and fluoroethylene carbonate; the volume fraction of the cyanosulfonate compound additive is 0.1%-5%.

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