Sodium battery with long cycle life and preparation process thereof

Abstract

The invention discloses a sodium battery with long cycle life and a preparation process thereof, and relates to the technical field of sodium batteries. The method specifically comprises the following steps: S1, adding a sodium rhodizonate composite material, conductive carbon black and polyvinylidene fluoride into a solvent, and uniformly mixing to obtain electrode slurry; s2, uniformly coating an aluminum foil with the electrode slurry, and performing vacuum drying to obtain a positive plate; s3, in an argon atmosphere, assembling the negative electrode shell, the sodium sheet, the diaphragm, the positive plate, the gasket, the elastic sheet and the positive electrode shell in sequence, and meanwhile, fully infiltrating the interior of the battery by using electrolyte; the sodium battery with long cycle life is obtained; the sodium rhodizonate composite material is obtained by taking sodium rhodizonate as an active material, taking modified sodium alginate as a load type gel matrix and taking modified graphene oxide as a conductive reinforcing framework through cooperative treatment of an anti-solvent method and a hydrothermal method. And the cycle performance of the battery under high current density is obviously improved.

Description

Technical Field

[0001] This invention relates to the field of sodium battery technology, specifically to a sodium battery with high cycle life and its manufacturing process. Background Technology

[0002] Sodium-ion batteries are considered an ideal technology to replace lithium-ion batteries in the field of new energy vehicles due to the advantages of abundant sodium resources, low cost, and environmental friendliness. However, due to the large radius of sodium ions, their insertion and extraction kinetics in electrode materials are slow, which can easily lead to significant structural and volume changes. This makes the positive electrode active material prone to pulverization and active material detachment during battery cycling, ultimately resulting in poor battery cycle performance. In particular, the reversible capacity under high current density is severely reduced, which limits its practical application.

[0003] In conclusion, solving the above problems and developing a sodium battery with high cycle life is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a sodium battery with high cycle life and its manufacturing process to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A process for fabricating a sodium battery with high cycle life includes the following steps: S1: Add sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride to a solvent and mix evenly to obtain electrode slurry; S2: The electrode paste is evenly coated on aluminum foil and vacuum dried to obtain the positive electrode sheet; S3: In an argon atmosphere, the battery is assembled in the following order: negative electrode shell, sodium plate, separator, positive electrode plate, gasket, spring, and positive electrode shell. At the same time, the inside of the battery is fully wetted with electrolyte to obtain a sodium battery with high cycle life.

[0006] Preferably, the raw materials of the electrode slurry include sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride in a mass ratio of 6~8:3~5:1.

[0007] Preferably, the raw materials of the sodium roserate composite material include sodium roserate, modified sodium alginate, and modified graphene oxide in a mass ratio of 100:10~15:25~30.

[0008] A preferred method for preparing the modified graphene oxide includes the following steps: adding the NVP / MA copolymer to acetone and stirring until homogeneous, adding amino-modified graphene oxide, stirring and reacting at 25-30°C for 8-12 hours, filtering, adding the product to deionized water, adjusting the pH to 7-7.5, filtering and washing, drying, and obtaining the modified graphene oxide.

[0009] More preferably, the raw materials for the modified graphene oxide include NVP / MA copolymer and amino-modified graphene oxide in a mass ratio of 1 to 1.5:2. The NVP / MA copolymer is obtained by copolymerizing N-vinylpyrrolidone and maleic anhydride in a mass ratio of 20:3~5. The amino-modified graphene oxide is obtained by modification with 3-aminopropyltriethoxysilane.

[0010] Preferred method for preparing modified sodium alginate includes the following steps: under a nitrogen atmosphere, sodium alginate and N-vinylpyrrolidone are added to deionized water and stirred until homogeneous. Benzophenone is added, and the mixture is stirred and reacted for 2-3 hours under ultraviolet light. The mixture is then precipitated with acetone, washed with anhydrous ethanol, and dried under vacuum to obtain modified sodium alginate.

[0011] More preferably, the raw materials for the modified sodium alginate include sodium alginate and N-vinylpyrrolidone in a mass ratio of 1:2.5~3; benzophenone accounts for 0.02~0.05wt% of sodium alginate.

[0012] Preferred method for preparing the sodium roserate composite material includes the following steps: adding modified sodium alginate and sodium roserate to deionized water and stirring until uniform; adding modified graphene oxide and ultrasonically dispersing until uniform to obtain reaction solution A; adding anhydrous ethanol dropwise to reaction solution A; allowing it to stand for 12-24 hours after the addition is complete; and then hydrothermally treating it at 180-185℃ for 8-16 hours to obtain the sodium roserate composite material.

[0013] Preferably, the mass ratio of the reaction solution A to anhydrous ethanol is 3~5:1; and the dropping rate is 1~2 drops / second during the dropping process.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present invention uses sodium roserate as the active material, NVP-grafted modified sodium alginate as the supported gel matrix, and NVP / MA copolymer-modified graphene oxide as the conductive reinforcing skeleton. The sodium roserate composite material is obtained by synergistic treatment of antisolvent method and hydrothermal method. When used as a cathode material for sodium-ion batteries, it significantly improves the cycle performance of batteries under high current density.

[0015] The modified sodium alginate is prepared by graft copolymerization of N-vinylpyrrolidone and sodium alginate under ultraviolet light irradiation and photoinitiation.

[0016] The preparation process of amino-modified graphene oxide involves the hydrolytic condensation of oxygen-containing groups on the surface of graphene oxide with 3-aminopropyltriethoxysilane to obtain amino-modified graphene oxide. The NVP / MA copolymer is obtained by free radical copolymerization of N-vinylpyrrolidone and maleic anhydride under the initiation of azobisisobutyronitrile. The preparation method of modified graphene oxide involves the ring-opening reaction of amino groups on amino-modified graphene oxide and anhydride in NVP / MA copolymer to generate grafted amide bonds and carboxyl groups, followed by deprotonation to obtain NVP / MA copolymer-modified graphene oxide containing sodium carboxylate.

[0017] The preparation method of the sodium roserate composite material is as follows: sodium roserate, modified sodium alginate, and modified graphene oxide are uniformly dispersed in water by anti-solvent precipitation, and then added dropwise to anhydrous ethanol. The reactants are combined together through hydrogen bonding. Further hydrothermal reaction reduces the graphene oxide and improves the stability and conductivity of the composite material. At the same time, the dropping rate is controlled to make the composite material smaller and more uniform in size, which significantly improves the cycle performance of the battery under high current density.

[0018] In this process, sodium alginate is modified by N-vinylpyrrolidone copolymer grafting. The PVP side chain is photoinitiated and connected to the hydroxyl active sites of the sodium alginate backbone. Due to the steric hindrance effect of the PVP side chain, the intramolecular hydrogen bonds of the sodium alginate chain are disrupted, inhibiting its tendency to tightly pack and crystallize. This results in the formation of more nanoscale pores and ion transport channels in the composite material, providing an intercalation loading space for sodium roserate molecules during the composite process. Furthermore, the pyrrolidone carbonyl group on the PVP side chain can provide additional hydrogen bond sites, forming multiple interactions with sodium roserate. This improves the loading rate and stability of sodium roserate on the conductive framework, reduces shedding or pulverization during charge and discharge, and thus improves the conductivity of sodium roserate, thereby enhancing battery performance.

[0019] Among them, the NVP / MA copolymer in modified graphene oxide is prepared by grafting acid anhydride and amino-modified graphene oxide. The PVP segments in the grafted copolymer are easily compatible with the side chains of modified sodium alginate, making it easier to form an interpenetrating polymer network with modified sodium alginate and increasing the loading of sodium rose oleate. At the same time, during the grafting process, the carboxyl groups generated by the ring opening of acid anhydride form sodium carboxylate after deprotonation, which is conducive to promoting the formation of a sodium ion fast transport layer and improving stability, thereby improving battery performance.

[0020] It is important to note that when synthesizing the NVP / MA copolymer, the ratio of N-vinylpyrrolidone to maleic anhydride must be controlled at 20:3~5. At this ratio, the polymer is dominated by flexible PVP segments, ensuring good compatibility with the modified sodium alginate side chains and the ability to form an interpenetrating network. The maleic anhydride monomer serves as a reaction site with amino-modified graphene oxide, and its proportion must be moderate. If the proportion is too high, it will increase the rigidity of the polymer segments, which is not conducive to effective interweaving with the modified sodium alginate. At the same time, too many sodium carboxylate groups formed by ring opening will make the material too hydrophilic, prone to swelling, and cause the composite material to become loose during cycling. Conversely, if the proportion of maleic anhydride monomer is too low, there will be insufficient grafting sites, resulting in a reduced grafting rate with graphene oxide, which will also affect the overall stability of the composite material and reduce battery performance. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0022] It should be noted that the following quantities are by weight. There are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: sodium alginate, grade S11053; N-vinylpyrrolidone, CAS number: 88-12-0; graphene oxide, sheet diameter 0.5~10μm; 3-aminopropyltriethoxysilane, CAS number: 919-30-2; maleic anhydride, CAS number: 108-31-6; sodium roserate, CAS number: 523-21-7; conductive carbon black, grade JK-R1006; polyvinylidene fluoride, grade V30214.

[0023] In the following embodiments, the electrolyte used is a 0.6 mol / L sodium hexafluorophosphate-diethylene glycol dimethyl ether solution; the solvent is N-methyl-2-pyrrolidone.

[0024] In the following examples, parts refer to parts by weight, and all raw materials mentioned above and others not mentioned are commercially available.

[0025] Example 1: A fabrication process for a sodium battery with high cycle life includes the following steps: Step 1: Preparation of modified sodium alginate: Under a nitrogen atmosphere, sodium alginate and N-vinylpyrrolidone were added to deionized water and stirred until homogeneous. Benzophenone was then added, and the mixture was stirred and reacted for 2 hours under ultraviolet light. The mixture was precipitated with acetone, washed with anhydrous ethanol, and vacuum dried to obtain modified sodium alginate. The raw materials for modified sodium alginate included sodium alginate and N-vinylpyrrolidone in a mass ratio of 1:2.7; benzophenone accounted for 0.03 wt% of the sodium alginate. Step 2: Preparation of modified graphene oxide: (1) Graphene oxide and 3-aminopropyltriethoxysilane were added to a 90wt% aqueous ethanol solution and ultrasonically dispersed evenly. The mixture was stirred at 50℃ for 8 hours, filtered, washed, and dried to obtain amino-modified graphene oxide. The raw materials for amino-modified graphene oxide included graphene oxide and 3-aminopropyltriethoxysilane in a mass ratio of 1:0.6. (2) Under a nitrogen atmosphere, N-vinylpyrrolidone and maleic anhydride were added to toluene and mixed evenly. Azobisisobutyronitrile was then added and the mixture was stirred at 80°C for 8 hours. The product was precipitated with dichloromethane, filtered, and dried to obtain the NVP / MA copolymer. The raw materials for the NVP / MA copolymer included N-vinylpyrrolidone and maleic anhydride in a mass ratio of 20:4; and azobisisobutyronitrile accounted for 0.5 wt% of the reactants. (3) Add the NVP / MA copolymer to acetone and stir evenly. Add amino-modified graphene oxide and stir at 25°C for 12 hours. Filter and add the product to deionized water. Adjust the pH to 7.5±0.1. Filter, wash, and dry to obtain modified graphene oxide. The raw materials for the modified graphene oxide include NVP / MA copolymer and amino-modified graphene oxide in a mass ratio of 1.3:2. Step 3: Preparation of sodium roserate composite material: Modified sodium alginate and sodium roserate were added to deionized water and stirred evenly at 80°C. Modified graphene oxide was added, and the mixture was ultrasonically dispersed for 2 hours to obtain reaction solution A. Anhydrous ethanol was added dropwise to reaction solution A. After the addition was complete, the mixture was allowed to stand for 16 hours and then hydrothermally treated at 180°C for 12 hours to obtain sodium roserate composite material. The raw materials of the sodium roserate composite material include sodium roserate, modified sodium alginate, and modified graphene oxide in a mass ratio of 100:12:27. The mass ratio of reaction solution A to anhydrous ethanol was 4:1. The dropwise addition rate was 1 drop / second.

[0026] Step 4: Fabrication of a sodium battery with high cycle life: S1: Add sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride to a solvent and mix evenly to obtain an electrode slurry; wherein, the raw materials of the electrode slurry include sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride in a mass ratio of 8:4:1. S2: The electrode paste is evenly coated on aluminum foil and vacuum dried to obtain the positive electrode sheet; S3: In an argon atmosphere, the battery is assembled in the following order: negative electrode shell, sodium plate, separator, positive electrode plate, gasket, spring, and positive electrode shell. At the same time, the inside of the battery is fully wetted with electrolyte to obtain a sodium battery with high cycle life.

[0027] Example 2: A fabrication process for a sodium battery with high cycle life includes the following steps: Step 1: Preparation of modified sodium alginate: Under a nitrogen atmosphere, sodium alginate and N-vinylpyrrolidone were added to deionized water and stirred until homogeneous. Benzophenone was then added, and the mixture was stirred and reacted for 2 hours under ultraviolet light. The mixture was precipitated with acetone, washed with anhydrous ethanol, and vacuum dried to obtain modified sodium alginate. The raw materials for modified sodium alginate included sodium alginate and N-vinylpyrrolidone in a mass ratio of 1:2.7; benzophenone accounted for 0.03 wt% of the sodium alginate. Step 2: Preparation of modified graphene oxide: (1) Graphene oxide and 3-aminopropyltriethoxysilane were added to a 90wt% aqueous ethanol solution and ultrasonically dispersed evenly. The mixture was stirred at 50℃ for 8 hours, filtered, washed, and dried to obtain amino-modified graphene oxide. The raw materials for amino-modified graphene oxide included graphene oxide and 3-aminopropyltriethoxysilane in a mass ratio of 1:0.6. (2) Under a nitrogen atmosphere, N-vinylpyrrolidone and maleic anhydride were added to toluene and mixed evenly. Azobisisobutyronitrile was then added and the mixture was stirred at 80°C for 8 hours. The product was precipitated with dichloromethane, filtered, and dried to obtain the NVP / MA copolymer. The raw materials for the NVP / MA copolymer included N-vinylpyrrolidone and maleic anhydride in a mass ratio of 20:4; and azobisisobutyronitrile accounted for 0.5 wt% of the reactants. (3) Add the NVP / MA copolymer to acetone and stir evenly. Add amino-modified graphene oxide and stir at 25°C for 12 hours. Filter and add the product to deionized water. Adjust the pH to 7.5±0.1. Filter, wash, and dry to obtain modified graphene oxide. The raw materials for the modified graphene oxide include NVP / MA copolymer and amino-modified graphene oxide in a mass ratio of 1.3:2. Step 3: Preparation of sodium roserate composite material: Modified sodium alginate and sodium roserate were added to deionized water and stirred evenly at 80°C. Modified graphene oxide was added, and the mixture was ultrasonically dispersed for 2 hours to obtain reaction solution A. Anhydrous ethanol was added dropwise to reaction solution A. After the addition was complete, the mixture was allowed to stand for 16 hours and then hydrothermally treated at 180°C for 12 hours to obtain sodium roserate composite material. The raw materials of the sodium roserate composite material include sodium roserate, modified sodium alginate, and modified graphene oxide in a mass ratio of 100:12:27. The mass ratio of reaction solution A to anhydrous ethanol was 4:1. The dropwise addition rate was 1 drop / second.

[0028] Step 4: Fabrication of a sodium battery with high cycle life: S1: Add sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride to a solvent and mix evenly to obtain an electrode slurry; wherein, the raw materials of the electrode slurry include sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride in a mass ratio of 6:3:1. S2: The electrode paste is evenly coated on aluminum foil and vacuum dried to obtain the positive electrode sheet; S3: In an argon atmosphere, the battery is assembled in the following order: negative electrode shell, sodium plate, separator, positive electrode plate, gasket, spring, and positive electrode shell. At the same time, the inside of the battery is fully wetted with electrolyte to obtain a sodium battery with high cycle life.

[0029] Example 3: A fabrication process for a sodium battery with high cycle life includes the following steps: Step 1: Preparation of modified sodium alginate: Under a nitrogen atmosphere, sodium alginate and N-vinylpyrrolidone were added to deionized water and stirred until homogeneous. Benzophenone was then added, and the mixture was stirred and reacted for 2 hours under ultraviolet light. The mixture was precipitated with acetone, washed with anhydrous ethanol, and vacuum dried to obtain modified sodium alginate. The raw materials for modified sodium alginate included sodium alginate and N-vinylpyrrolidone in a mass ratio of 1:2.7; benzophenone accounted for 0.03 wt% of the sodium alginate. Step 2: Preparation of modified graphene oxide: (1) Graphene oxide and 3-aminopropyltriethoxysilane were added to a 90wt% aqueous ethanol solution and ultrasonically dispersed evenly. The mixture was stirred at 50℃ for 8 hours, filtered, washed, and dried to obtain amino-modified graphene oxide. The raw materials for amino-modified graphene oxide included graphene oxide and 3-aminopropyltriethoxysilane in a mass ratio of 1:0.6. (2) Under a nitrogen atmosphere, N-vinylpyrrolidone and maleic anhydride were added to toluene and mixed evenly. Azobisisobutyronitrile was then added and the mixture was stirred at 80°C for 8 hours. The product was precipitated with dichloromethane, filtered, and dried to obtain the NVP / MA copolymer. The raw materials for the NVP / MA copolymer included N-vinylpyrrolidone and maleic anhydride in a mass ratio of 20:4; and azobisisobutyronitrile accounted for 0.5 wt% of the reactants. (3) Add the NVP / MA copolymer to acetone and stir evenly. Add amino-modified graphene oxide and stir at 25°C for 12 hours. Filter and add the product to deionized water. Adjust the pH to 7.5±0.1. Filter, wash, and dry to obtain modified graphene oxide. The raw materials for the modified graphene oxide include NVP / MA copolymer and amino-modified graphene oxide in a mass ratio of 1.3:2. Step 3: Preparation of sodium roserate composite material: Modified sodium alginate and sodium roserate were added to deionized water and stirred evenly at 80°C. Modified graphene oxide was added, and the mixture was ultrasonically dispersed for 2 hours to obtain reaction solution A. Anhydrous ethanol was added dropwise to reaction solution A. After the addition was complete, the mixture was allowed to stand for 16 hours and then hydrothermally treated at 180°C for 12 hours to obtain sodium roserate composite material. The raw materials of the sodium roserate composite material include sodium roserate, modified sodium alginate, and modified graphene oxide in a mass ratio of 100:12:27. The mass ratio of reaction solution A to anhydrous ethanol was 4:1. The dropwise addition rate was 1 drop / second.

[0030] Step 4: Fabrication of a sodium battery with high cycle life: S1: Add sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride to a solvent and mix evenly to obtain an electrode slurry; wherein, the raw materials of the electrode slurry include sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride in a mass ratio of 8:5:1. S2: The electrode paste is evenly coated on aluminum foil and vacuum dried to obtain the positive electrode sheet; S3: In an argon atmosphere, the battery is assembled in the following order: negative electrode shell, sodium plate, separator, positive electrode plate, gasket, spring, and positive electrode shell. At the same time, the inside of the battery is fully wetted with electrolyte to obtain a sodium battery with high cycle life.

[0031] Comparative Example 1: Based on Example 1, the graphene oxide was not modified, and the remaining processes remained unchanged, as follows: Step 1: Preparation of modified sodium alginate: Under a nitrogen atmosphere, sodium alginate and N-vinylpyrrolidone were added to deionized water and stirred until homogeneous. Benzophenone was then added, and the mixture was stirred and reacted for 2 hours under ultraviolet light. The mixture was precipitated with acetone, washed with anhydrous ethanol, and vacuum dried to obtain modified sodium alginate. The raw materials for modified sodium alginate included sodium alginate and N-vinylpyrrolidone in a mass ratio of 1:2.7; benzophenone accounted for 0.03 wt% of the sodium alginate. Step 2: Preparation of sodium roserate composite material: Modified sodium alginate and sodium roserate were added to deionized water and stirred evenly at 80°C. Graphene oxide was added, and the mixture was ultrasonically dispersed for 2 hours to obtain reaction solution A. Anhydrous ethanol was added dropwise to reaction solution A. After the addition was complete, the mixture was allowed to stand for 16 hours and then hydrothermally treated at 180°C for 12 hours to obtain sodium roserate composite material. The raw materials of the sodium roserate composite material include sodium roserate, modified sodium alginate, and graphene oxide in a mass ratio of 100:12:27. The mass ratio of reaction solution A to anhydrous ethanol was 4:1. The dropwise addition rate was 1 drop / second.

[0032] Step 3: Preparation of sodium batteries with high cycle life: S1: Add sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride to a solvent and mix evenly to obtain an electrode slurry; wherein, the raw materials of the electrode slurry include sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride in a mass ratio of 8:4:1. S2: The electrode paste is evenly coated on aluminum foil and vacuum dried to obtain the positive electrode sheet; S3: In an argon atmosphere, the battery is assembled in the following order: negative electrode shell, sodium plate, separator, positive electrode plate, gasket, spring, and positive electrode shell. At the same time, the inside of the battery is fully wetted with electrolyte to obtain a sodium battery with high cycle life.

[0033] Comparative Example 2: Based on Example 1, sodium alginate was not modified, and the remaining processes remained unchanged, as follows: Step 1: Preparation of modified graphene oxide: (1) Graphene oxide and 3-aminopropyltriethoxysilane were added to a 90wt% aqueous ethanol solution and ultrasonically dispersed evenly. The mixture was stirred at 50℃ for 8 hours, filtered, washed, and dried to obtain amino-modified graphene oxide. The raw materials for amino-modified graphene oxide included graphene oxide and 3-aminopropyltriethoxysilane in a mass ratio of 1:0.6. (2) Under a nitrogen atmosphere, N-vinylpyrrolidone and maleic anhydride were added to toluene and mixed evenly. Azobisisobutyronitrile was then added and the mixture was stirred at 80°C for 8 hours. The product was precipitated with dichloromethane, filtered, and dried to obtain the NVP / MA copolymer. The raw materials for the NVP / MA copolymer included N-vinylpyrrolidone and maleic anhydride in a mass ratio of 20:4; and azobisisobutyronitrile accounted for 0.5 wt% of the reactants. (3) Add the NVP / MA copolymer to acetone and stir evenly. Add amino-modified graphene oxide and stir at 25°C for 12 hours. Filter and add the product to deionized water. Adjust the pH to 7.5±0.1. Filter, wash, and dry to obtain modified graphene oxide. The raw materials for the modified graphene oxide include NVP / MA copolymer and amino-modified graphene oxide in a mass ratio of 1.3:2. Step 2: Preparation of sodium roserate composite material: Sodium alginate and sodium roserate were added to deionized water and stirred evenly at 80°C. Modified graphene oxide was added, and the mixture was ultrasonically dispersed for 2 hours to obtain reaction solution A. Anhydrous ethanol was added dropwise to reaction solution A. After the addition was complete, the mixture was allowed to stand for 16 hours and then hydrothermally treated at 180°C for 12 hours to obtain sodium roserate composite material. The raw materials of the sodium roserate composite material include sodium roserate, sodium alginate, and modified graphene oxide in a mass ratio of 100:12:27. The mass ratio of reaction solution A to anhydrous ethanol was 4:1. The dropwise addition rate was 1 drop / second.

[0034] Step 3: Preparation of sodium batteries with high cycle life: S1: Add sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride to a solvent and mix evenly to obtain an electrode slurry; wherein, the raw materials of the electrode slurry include sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride in a mass ratio of 8:4:1. S2: The electrode paste is evenly coated on aluminum foil and vacuum dried to obtain the positive electrode sheet; S3: In an argon atmosphere, the battery is assembled in the following order: negative electrode shell, sodium plate, separator, positive electrode plate, gasket, spring, and positive electrode shell. At the same time, the inside of the battery is fully wetted with electrolyte to obtain a sodium battery with high cycle life.

[0035] Comparative Example 3: Based on Example 1, neither sodium alginate nor graphene oxide was modified, and the remaining processes remained unchanged, as follows: Step 1: Preparation of sodium roserate composite material: Sodium alginate and sodium roserate were added to deionized water and stirred evenly at 80°C. Graphene oxide was added, and the mixture was ultrasonically dispersed for 2 hours to obtain reaction solution A. Anhydrous ethanol was added dropwise to reaction solution A. After the addition was complete, the mixture was allowed to stand for 16 hours and then hydrothermally treated at 180°C for 12 hours to obtain sodium roserate composite material. The raw materials of the sodium roserate composite material include sodium roserate, sodium alginate, and graphene oxide in a mass ratio of 100:12:27. The mass ratio of reaction solution A to anhydrous ethanol was 4:1. The dropwise addition rate was 1 drop / second.

[0036] Step 2: Preparation of sodium batteries with high cycle life: S1: Add sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride to a solvent and mix evenly to obtain an electrode slurry; wherein, the raw materials of the electrode slurry include sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride in a mass ratio of 8:4:1. S2: The electrode paste is evenly coated on aluminum foil and vacuum dried to obtain the positive electrode sheet; S3: In an argon atmosphere, the battery is assembled in the following order: negative electrode shell, sodium plate, separator, positive electrode plate, gasket, spring, and positive electrode shell. At the same time, the inside of the battery is fully wetted with electrolyte to obtain a sodium battery with high cycle life.

[0037] Comparative Example 4: Based on Example 1, the monomer exchange ratio was changed during the preparation of the NVP / MA copolymer, while the other processes remained the same, as follows: Step 1: Preparation of modified sodium alginate: Under a nitrogen atmosphere, sodium alginate and N-vinylpyrrolidone were added to deionized water and stirred until homogeneous. Benzophenone was then added, and the mixture was stirred and reacted for 2 hours under ultraviolet light. The mixture was precipitated with acetone, washed with anhydrous ethanol, and vacuum dried to obtain modified sodium alginate. The raw materials for modified sodium alginate included sodium alginate and N-vinylpyrrolidone in a mass ratio of 1:2.7; benzophenone accounted for 0.03 wt% of the sodium alginate. Step 2: Preparation of modified graphene oxide: (1) Graphene oxide and 3-aminopropyltriethoxysilane were added to a 90wt% aqueous ethanol solution and ultrasonically dispersed evenly. The mixture was stirred at 50℃ for 8 hours, filtered, washed, and dried to obtain amino-modified graphene oxide. The raw materials for amino-modified graphene oxide included graphene oxide and 3-aminopropyltriethoxysilane in a mass ratio of 1:0.6. (2) Under a nitrogen atmosphere, N-vinylpyrrolidone and maleic anhydride were added to toluene and mixed evenly. Azobisisobutyronitrile was then added and the mixture was stirred at 80°C for 8 hours. The product was precipitated with dichloromethane, filtered, and dried to obtain the NVP / MA copolymer. The raw materials for the NVP / MA copolymer included N-vinylpyrrolidone and maleic anhydride in a mass ratio of 4:20, and azobisisobutyronitrile accounted for 0.5 wt% of the reactants. (3) Add the NVP / MA copolymer to acetone and stir evenly. Add amino-modified graphene oxide and stir at 25°C for 12 hours. Filter and add the product to deionized water. Adjust the pH to 7.5±0.1. Filter, wash, and dry to obtain modified graphene oxide. The raw materials for the modified graphene oxide include NVP / MA copolymer and amino-modified graphene oxide in a mass ratio of 1.3:2. Step 3: Preparation of sodium roserate composite material: Modified sodium alginate and sodium roserate were added to deionized water and stirred evenly at 80°C. Modified graphene oxide was added, and the mixture was ultrasonically dispersed for 2 hours to obtain reaction solution A. Anhydrous ethanol was added dropwise to reaction solution A. After the addition was complete, the mixture was allowed to stand for 16 hours and then hydrothermally treated at 180°C for 12 hours to obtain sodium roserate composite material. The raw materials of the sodium roserate composite material include sodium roserate, modified sodium alginate, and modified graphene oxide in a mass ratio of 100:12:27. The mass ratio of reaction solution A to anhydrous ethanol was 4:1. The dropwise addition rate was 1 drop / second.

[0038] Step 4: Fabrication of a sodium battery with high cycle life: S1: Add sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride to a solvent and mix evenly to obtain an electrode slurry; wherein, the raw materials of the electrode slurry include sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride in a mass ratio of 8:4:1. S2: The electrode paste is evenly coated on aluminum foil and vacuum dried to obtain the positive electrode sheet; S3: In an argon atmosphere, the battery is assembled in the following order: negative electrode shell, sodium plate, separator, positive electrode plate, gasket, spring, and positive electrode shell. At the same time, the inside of the battery is fully wetted with electrolyte to obtain a sodium battery with high cycle life.

[0039] Comparative Example 5: Based on Example 1, the dropping rate was increased during the antisolvent precipitation process, while the rest of the process remained unchanged, as follows: Step 1: Preparation of modified sodium alginate: Under a nitrogen atmosphere, sodium alginate and N-vinylpyrrolidone were added to deionized water and stirred until homogeneous. Benzophenone was then added, and the mixture was stirred and reacted for 2 hours under ultraviolet light. The mixture was precipitated with acetone, washed with anhydrous ethanol, and vacuum dried to obtain modified sodium alginate. The raw materials for modified sodium alginate included sodium alginate and N-vinylpyrrolidone in a mass ratio of 1:2.7; benzophenone accounted for 0.03 wt% of the sodium alginate. Step 2: Preparation of modified graphene oxide: (1) Graphene oxide and 3-aminopropyltriethoxysilane were added to a 90wt% aqueous ethanol solution and ultrasonically dispersed evenly. The mixture was stirred at 50℃ for 8 hours, filtered, washed, and dried to obtain amino-modified graphene oxide. The raw materials for amino-modified graphene oxide included graphene oxide and 3-aminopropyltriethoxysilane in a mass ratio of 1:0.6. (2) Under a nitrogen atmosphere, N-vinylpyrrolidone and maleic anhydride were added to toluene and mixed evenly. Azobisisobutyronitrile was then added and the mixture was stirred at 80°C for 8 hours. The product was precipitated with dichloromethane, filtered, and dried to obtain the NVP / MA copolymer. The raw materials for the NVP / MA copolymer included N-vinylpyrrolidone and maleic anhydride in a mass ratio of 20:4; and azobisisobutyronitrile accounted for 0.5 wt% of the reactants. (3) Add the NVP / MA copolymer to acetone and stir evenly. Add amino-modified graphene oxide and stir at 25°C for 12 hours. Filter and add the product to deionized water. Adjust the pH to 7.5±0.1. Filter, wash, and dry to obtain modified graphene oxide. The raw materials for the modified graphene oxide include NVP / MA copolymer and amino-modified graphene oxide in a mass ratio of 1.3:2. Step 3: Preparation of sodium roserate composite material: Modified sodium alginate and sodium roserate were added to deionized water and stirred evenly at 80°C. Modified graphene oxide was added, and the mixture was ultrasonically dispersed for 2 hours to obtain reaction solution A. Anhydrous ethanol was added dropwise to reaction solution A. After the addition was complete, the mixture was allowed to stand for 16 hours and then hydrothermally treated at 180°C for 12 hours to obtain sodium roserate composite material. The raw materials of the sodium roserate composite material include sodium roserate, modified sodium alginate, and modified graphene oxide in a mass ratio of 100:12:27. The mass ratio of reaction solution A to anhydrous ethanol was 4:1. The dropwise addition rate was 4 drops / second.

[0040] Step 4: Fabrication of a sodium battery with high cycle life: S1: Add sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride to a solvent and mix evenly to obtain an electrode slurry; wherein, the raw materials of the electrode slurry include sodium rose oleate composite material, conductive carbon black, and polyvinylidene fluoride in a mass ratio of 8:4:1. S2: The electrode paste is evenly coated on aluminum foil and vacuum dried to obtain the positive electrode sheet; S3: In an argon atmosphere, the battery is assembled in the following order: negative electrode shell, sodium plate, separator, positive electrode plate, gasket, spring, and positive electrode shell. At the same time, the inside of the battery is fully wetted with electrolyte to obtain a sodium battery with high cycle life.

[0041] Performance Testing: The discharge specific capacity of each embodiment and comparative battery was tested during cycling using a multi-functional battery testing system; the charge / discharge voltage range was 0.5~3.2V; the experimental data are shown in the table below: Group Discharge specific capacity (mAh / g) at a current density of 500 mA / g for 100 cycles Discharge specific capacity (mAh / g) at a current density of 1000 mA / g for 500 cycles Example 1 175.8 149.2 Example 2 173.4 147.3 Example 3 170.1 145.0 Comparative Example 1 158.3 136.7 Comparative Example 2 162.1 140.2 Comparative Example 3 147.2 131.4 Comparative Example 4 144.9 125.4 Comparative Example 5 151.0 128.6 Conclusions: As shown in the table above, in Comparative Example 1, the unmodified graphene oxide could not form an interpenetrating network structure with the modified sodium alginate, resulting in a loose composite structure, limited improvement in conductivity, weakened bonding between sodium roserate and the backbone, easy detachment during cycling, and reduced discharge specific capacity. In Comparative Example 2, the unmodified sodium alginate molecular chains easily formed a tight packing, resulting in low porosity, which was not conducive to the intercalation and ion transport of sodium roserate, and reduced discharge specific capacity. In Comparative Example 3, neither sodium alginate nor graphene oxide was modified, and the composite material could not form an enhanced conductive network, resulting in poor stability. During cycling, sodium roserate powdered and detached, and the performance decreased significantly. In Comparative Example 4, the exchange monomer ratio during the preparation of the NVP / MA copolymer was too high, the maleic anhydride ratio was too high, the polymer chain rigidity increased, and the excessive sodium carboxylate groups led to excessive hydrophilicity of the material, easy swelling, unstable structure during cycling, and significantly reduced performance. In Comparative Example 5, increasing the dropping rate during the anti-solvent precipitation process resulted in uneven precipitation of the composite material, increased particle size and wide distribution, and reduced discharge specific capacity.

[0042] In summary, this invention uses sodium roserate as the active material, NVP-grafted modified sodium alginate as the supported gel matrix, and NVP / MA copolymer-modified graphene oxide as the conductive reinforcing framework. The sodium roserate composite material is obtained through a combination of antisolvent and hydrothermal methods. When used as a cathode material for sodium-ion batteries, it significantly improves the cycle performance of the battery under high current density.

[0043] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. 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 process for the preparation of a sodium battery with high cycle life, characterized in that: The preparation method comprises the following steps: S1: adding sodium rose bengal composite material, conductive carbon black and polyvinylidene fluoride into a solvent and mixing uniformly to obtain electrode slurry; S2: uniformly coating the electrode slurry on an aluminum foil and vacuum drying to obtain a positive electrode sheet; S3: assembling in the order of negative electrode shell, sodium sheet, separator, positive electrode sheet, gasket, spring and positive electrode shell in an argon atmosphere, and fully infiltrating the electrolyte in the battery; and obtaining a sodium battery with high cycle life.

2. The process for the preparation of a sodium battery with high cycle life according to claim 1, characterized in that: The raw materials of the electrode slurry include sodium rose bengal composite material, conductive carbon black and polyvinylidene fluoride with a mass ratio of 6-8:3-5:

1.

3. The process for the preparation of a sodium battery with high cycle life as claimed in claim 1, wherein: The raw materials of the sodium rose bengal composite material include sodium rose bengal, modified sodium alginate and modified graphene oxide with a mass ratio of 100:10-15:25-30.

4. The process for preparing a sodium battery with high cycle life according to claim 3, characterized in that: The preparation method of the modified graphene oxide comprises the following steps: adding NVP / MA copolymer into acetone and stirring uniformly, adding amino-modified graphene oxide, stirring and reacting at 25-30℃ for 8-12h, filtering, adding the product into deionized water, adjusting the pH to 7-7.5, filtering and washing, and drying to obtain the modified graphene oxide.

5. The process for the preparation of a sodium battery with high cycle life according to claim 4, characterized in that: The raw materials of the modified graphene oxide include NVP / MA copolymer and amino-modified graphene oxide with a mass ratio of 1-1.5:

2. The NVP / MA copolymer is obtained by copolymerization of N-vinylpyrrolidone and maleic anhydride with a mass ratio of 20:3-5. The amino-modified graphene oxide is obtained by modification of 3-aminopropyltriethoxysilane.

6. The process for the preparation of a sodium battery with high cycle life as claimed in claim 3, wherein: The preparation method of the modified sodium alginate comprises the following steps: under a nitrogen atmosphere, adding sodium alginate and N-vinylpyrrolidone into deionized water and stirring uniformly, adding benzophenone, stirring and reacting under ultraviolet light for 2-3h, precipitating with acetone, washing with anhydrous ethanol, and vacuum drying to obtain the modified sodium alginate.

7. The process for the preparation of a sodium battery with high cycle life according to claim 6, characterized in that: The raw materials of the modified sodium alginate include sodium alginate and N-vinylpyrrolidone with a mass ratio of 1:2.5-3; and the benzophenone accounts for 0.02-0.05wt% of the sodium alginate.

8. The process for preparing a sodium battery with high cycle life as claimed in claim 1, wherein: The preparation method of the sodium rose bengal composite material comprises the following steps: adding the modified sodium alginate and sodium rose bengal into deionized water and stirring uniformly, adding the modified graphene oxide, and ultrasonic dispersing uniformly to obtain reaction liquid A; adding the reaction liquid A into anhydrous ethanol dropwise, standing for 12-24h after the dropwise addition is completed, and then hydrothermally treating at 180-185℃ for 8-16h to obtain the sodium rose bengal composite material.

9. The process for preparing a sodium battery with high cycle life according to claim 8, characterized in that: The mass ratio of the reaction liquid A and the anhydrous ethanol is 3-5:1; and the speed of dropwise addition is 1-2 drops / s.

10. The sodium battery with high cycle life prepared by the preparation process according to any one of claims 1-9.