Full-cycle sodium supplement, preparation method and application thereof, and sodium ion battery
By combining a two-component, staged sodium replenishment strategy with a nanoparticle core-shell structure, dynamic sodium release control throughout the entire lifecycle of sodium-ion batteries was achieved, solving the problems of gas expansion and sodium loss in sodium-ion batteries and improving battery safety and lifespan.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING ELECTRIC VEHICLE
- Filing Date
- 2026-03-31
- Publication Date
- 2026-06-12
Smart Images
Figure CN122202575A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of sodium-ion battery technology, specifically to a full-cycle sodium replenishment agent, its preparation method and application, and sodium-ion batteries. Background Technology
[0002] Sodium-ion batteries have shown great potential in large-scale energy storage due to the abundance of sodium resources and low cost. However, two key issues hinder their development. First, existing sodium replenishment agents generate gases during operation. For example, carbonate and oxalate-based agents decompose to produce carbon dioxide, while azide-based agents produce nitrogen. The accumulation of these gases causes cell swelling, affecting battery safety and lifespan. Second, current sodium replenishment methods are mostly single-cycle replenishments, performed only during battery formation. This cannot meet the sodium loss compensation requirements caused by various irreversible reactions during long-term cycling, resulting in rapid capacity decay with increasing cycle count, making long-cycle use difficult. Therefore, there is an urgent need to develop a technical solution that can solve the gas generation problem and achieve full-cycle sodium compensation.
[0003] Based on this technical background, this invention studies a full-cycle sodium replenishment agent, its preparation method and application, as well as sodium-ion batteries. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a full-cycle sodium replenishment agent, its preparation method, its application, and a sodium-ion battery. This sodium replenishment agent employs a two-component, staged sodium replenishment strategy. Simultaneously, through the combination of nanoparticles and a core-shell structure, it achieves dynamic sodium release control for "rapid formation of sodium-ion battery + sodium-ion battery cycling," covering the entire sodium-ion battery lifecycle and solving the long-term sodium loss problem. It allows gas generation during the formation stage but removes it through the process, and employs a gas-free design during the cycling stage, completely eliminating the risk of gas expansion. This avoids the problems of existing single sodium replenishment agents or single-time sodium replenishment, single-potential sodium release, and gas generation and sodium release throughout the entire lifecycle.
[0005] To achieve the above objectives, a first aspect of the present invention provides a full-cycle sodium supplement, comprising: Low-potential, rapid sodium release component, existing in nanoparticle form, with a decomposition potential of 0.01-1.5V. Sodium-ion battery vs. sodium-ion battery. + / Na is used to replenish sodium to the negative electrode during the battery formation stage; Cyclic slow-release sodium replenishment component, with a core-shell structure, decomposition potential of 1.5-4.0V. Sodium-ion battery vs. sodium-ion battery Na. + / Na is used to continuously replenish sodium to the positive and negative electrodes during battery cycling.
[0006] A second aspect of the present invention provides a method for preparing the above-mentioned full-cycle sodium supplement, comprising: Low-potential, fast-release sodium components containing sodium and existing in the form of nanoparticles were prepared by ball milling or ultrasonic dispersion. The core-shell structure of the cyclically released sodium supplement component is formed by spray drying or electrospinning.
[0007] A third aspect of the present invention provides the application of the above-described full-cycle sodium replenishment agent or the full-cycle sodium replenishment agent prepared by the above-described preparation method in a sodium-ion battery, comprising: In the sodium battery preparation process, the low-potential fast sodium release component is mixed with the sodium battery negative electrode active material at a mass ratio of 1:5-1:10 and uniformly dispersed in the negative electrode slurry to ensure that the low-potential fast sodium release component is in close contact with the sodium battery negative electrode during the sodium battery formation stage, and timely replenishment of sodium to the sodium battery negative electrode. The cyclic slow-release sodium replenishing component is mixed with the positive electrode active material of the sodium battery at a mass ratio of 1:8 to 1:12 and uniformly dispersed in the positive electrode slurry of the sodium battery. During the cycle of the sodium battery, the cyclic slow-release sodium replenishing component slowly releases sodium ions with the charge and discharge reaction of the positive electrode of the sodium battery, so as to continuously replenish sodium to the positive and negative electrodes of the sodium battery.
[0008] A fourth aspect of the present invention provides a sodium-ion battery having the above-described full-cycle sodium replenishment agent or the full-cycle sodium replenishment agent prepared by the above-described preparation method, characterized in that it comprises: The positive electrode contains a cyclically released sodium replenishment component; The negative electrode has a low potential for rapid sodium release; The electrolyte is an organic electrolyte containing sodium ions; Diaphragm.
[0009] The beneficial effects of this invention include: (1) The sodium replenishment agent proposed in this invention adopts a two-component, staged sodium replenishment strategy. At the same time, through the combination of nanoparticles and core-shell structure, dynamic sodium release control of "rapid formation of sodium-ion battery + sodium-ion battery cycle" is realized, covering the entire cycle of sodium-ion battery and solving the long-term sodium loss problem. It allows gas generation during the formation stage but discharges it through the process. The cycle stage adopts a gas-free design, which completely solves the risk of gas expansion and avoids the problems of existing single sodium replenishment agents or single sodium replenishment, single potential sodium release, and gas generation and sodium release throughout the entire cycle.
[0010] (2) The sodium replenishment agent proposed in this invention utilizes highly active materials such as sodium metal sodium-ion battery / sodium alloy sodium-ion battery and sodium borohydride to rapidly and completely release sodium ions at low potential during the formation stage (sodium utilization rate of sodium-ion battery is 100%), accurately compensating for the sodium consumed in the formation of the SEI sodium-ion battery film of the negative electrode sodium-ion battery; at the same time, it allows gas generation during the formation stage, and avoids gas residue through process design (such as vacuum exhaust), thus solving the problem of gas expansion in subsequent cycles.
[0011] (3) The sodium replenishment agent proposed in this invention uses organic coordination compounds of sodium (such as Na-EDTA for sodium-ion batteries), Prussian blue analogues, etc., to slowly release sodium ions during the cycle, continuously compensating for the sodium loss of the positive and negative electrodes during long-term cycling; at the same time, the electrolyte is isolated by the core-shell structure to avoid side reaction gas production and improve cycle safety.
[0012] (4) The sodium replenishment agent proposed in this invention enhances the low-potential reaction with nanoparticles: the low-potential component adopts sodium-ion battery nanoparticles of 50-200 nm, which increases the specific surface area of the reaction and ensures rapid and complete decomposition in the formation stage; core-shell structure controlled-release cyclic sodium replenishment: the cyclic slow-release component adopts sodium-ion battery structure of "active material core sodium-ion battery + sodium-ion battery ion conduction polymer shell" (such as sodium-ion battery PVDF-HFP, with a thickness of 10-50 nm), which controls the sodium ion release rate and suppresses gas production.
[0013] (5) The sodium replenishment agent proposed in this invention adopts a phased sodium replenishment strategy: formation stage: low potential component focuses on replenishing sodium at the negative electrode to improve the first coulombic efficiency; cycling stage: high potential component continuously replenishes sodium loss at the positive and negative electrodes to extend cycle life; electrolyte synergistic adaptation: sodium salts such as NaPF6 / NaBF4 from sodium-ion batteries and carbonate solvents are used to match the potential window of the sodium replenishment agent, promote sodium ion conduction and suppress side reactions.
[0014] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description
[0015] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings.
[0016] Figure 1 This is a schematic flowchart of the preparation method of the full-cycle sodium supplement proposed in this invention. Detailed Implementation
[0017] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.
[0018] This invention provides a full-cycle sodium supplement, comprising: Low-potential, rapid sodium release component, existing in nanoparticle form, with a decomposition potential of 0.01-1.5V. Sodium-ion battery vs. sodium-ion battery. + / Na is used to replenish sodium to the negative electrode during the battery formation stage; Cyclic slow-release sodium replenishment component, with a core-shell structure, decomposition potential of 1.5-4.0V. Sodium-ion battery vs. sodium-ion battery Na. + / Na is used to continuously replenish sodium to the positive and negative electrodes during battery cycling.
[0019] This invention employs a two-component, staged sodium replenishment strategy. Simultaneously, through the combination of nanoparticles and a core-shell structure, dynamic sodium release control is achieved for "rapid formation of sodium-ion batteries + sodium-ion battery cycling," covering the entire sodium-ion battery lifecycle and solving the long-term sodium loss problem. Gas generation is allowed during the formation stage but is discharged through the process, while a gas-free design is adopted during the cycling stage, completely eliminating the risk of gas expansion and avoiding the problems of existing single sodium replenishment agents or single-time sodium replenishment, single-potential sodium release, and gas generation and sodium release throughout the entire lifecycle.
[0020] In this invention, highly active materials such as sodium metal sodium-ion batteries / sodium alloys and sodium borohydrides are used to rapidly and completely release sodium ions at low potential during the formation stage (sodium utilization rate of sodium-ion batteries is 100%), accurately compensating for the sodium consumed in the formation of the SEI sodium-ion battery film in the negative electrode sodium-ion battery; at the same time, gas generation is allowed during the formation stage, and gas residue is avoided through process design (such as vacuum degassing), solving the problem of subsequent cycle gas expansion.
[0021] According to the present invention, the average particle size of the nanoparticles is 50-200 nm; The outer shell of the core-shell structure has a thickness of 10-50 nm.
[0022] In this invention, nanoparticles enhance the low-potential reaction: the low-potential component uses sodium-ion battery nanoparticles of 50–200 nm to increase the specific surface area of the reaction and ensure rapid and complete decomposition during the formation stage; core-shell structure controlled-release cyclic sodium replenishment: the cyclic slow-release component uses a sodium-ion battery structure of "active material core sodium-ion battery + sodium-ion battery ion-conducting polymer shell" (such as sodium-ion battery PVDF-HFP, with a thickness of 10–50 nm) to control the sodium ion release rate and suppress gas production.
[0023] According to the present invention, the low-potential rapid sodium release component includes at least one of metallic sodium, sodium alloy or sodium borohydride; The core of the core-shell structure is a sodium-rich active substance, while the outer shell is a polymer with ion conductivity.
[0024] According to the present invention, the sodium-supplementing active substance is a sodium-ethylenediaminetetraacetic acid complex and / or a Prussian blue analogue of sodium: The ion-conducting polymer is polyvinylidene fluoride-hexafluoropropylene copolymer.
[0025] In this invention, organic coordination compounds of sodium (such as Na-EDTA for sodium-ion batteries) and Prussian blue analogues are used to slowly release sodium ions during cycling, continuously compensating for sodium loss from the positive and negative electrodes during long-term cycling; at the same time, the electrolyte is isolated by a core-shell structure to avoid side reactions and gas generation, thereby improving cycling safety.
[0026] In this invention, a phased sodium replenishment strategy is adopted: Formation stage: Low-potential components focus on replenishing sodium at the negative electrode to improve the initial coulombic efficiency; Cycling stage: High-potential components continuously replenish sodium loss at both the positive and negative electrodes to extend cycle life; Electrolyte synergistic adaptation: Sodium salts such as NaPF6 / NaBF4 from sodium-ion batteries are used with carbonate solvents to match the potential window of the sodium replenishment agent, promoting sodium ion conduction and suppressing side reactions.
[0027] This invention also provides a method for preparing the above-mentioned full-cycle sodium supplement, such as... Figure 1 As shown, this includes: preparing low-potential, rapidly releasing sodium components via melt emulsification-low-temperature solidification, high-energy ball milling-solid-phase reaction, solvothermal-recrystallization, or ultrasonic dispersion. Cyclic slow-release sodium supplement components can be prepared by spray drying, solvent evaporation, or electrostatic spraying.
[0028] According to the present invention, the preparation of a low-potential fast-release sodium component by melt emulsification-low-temperature solidification method includes: Under argon protection, metallic sodium is heated to molten state, and a dispersing stabilizer is added and stirred to obtain a molten sodium emulsion; The molten sodium emulsion is transferred to pre-cooled anhydrous mineral oil or white oil and sheared to emulsify, thus obtaining an emulsion. The emulsion was subjected to solid-liquid separation under argon protection. The obtained solids were washed and dried sequentially to obtain a low-potential rapid sodium release component with a particle size distribution of 50-200 nm. The low-potential, fast-release sodium components prepared by the high-energy ball milling-solid-phase reaction method include: The sodium metal, alloying elements, and ball milling aid are mixed and then ball milled. The ball-milled powder was sieved and classified under an inert atmosphere to obtain a low-potential rapid sodium-releasing component with a particle size distribution of 50-200 nm. The low-potential rapid sodium release components prepared by the solvothermal-recrystallization method include: Sodium borohydride is mixed with a sodium-containing compound and dissolved in a first organic solvent to prepare a mixed solution; A crystal form control agent is added to the mixed solution to carry out a crystallization reaction and obtain the reaction product; The reaction products were cooled, filtered, washed, and dried in sequence, and then refined by air jet milling or ball milling under argon protection to obtain low-potential rapid sodium release components with a particle size of 50-200 nm. The low-potential, fast-release sodium components prepared by ultrasonic dispersion include: Sodium borohydride was mixed with a surfactant and then added to a second organic solvent to prepare a dispersion. The dispersion was subjected to ultrasonic treatment, centrifugation, washing, and drying in sequence to obtain a low-potential rapid sodium-releasing component with a particle size of 50-200 nm. The cyclic slow-release sodium supplement component prepared by spray drying includes: Ethylenediaminetetraacetic acid (EDTA) and sodium hydroxide were mixed and dissolved in deionized water to carry out the reaction. After the reaction was completed, the mixture was concentrated under reduced pressure, cooled and crystallized, and filtered to obtain crude Na-EDTA. The crude Na-EDTA was then recrystallized and dried to obtain Na-EDTA powder with a particle size of 100-300 nm. The polyvinylidene fluoride-hexafluoropropylene copolymer is dissolved in N-methyl-2-pyrrolidone or acetone to prepare a first polymer solution; Na-EDTA powder was dispersed in a first polymer solution and coated by spray drying to obtain core-shell structured microsphere powder. The core-shell structured microsphere powder was dried to obtain a cyclically released sodium supplement component with a shell thickness of 10-50 nm. The preparation of cyclically released sodium supplement components via solvent evaporation includes: Sodium ferrocyanide and iron salt were dissolved in deionized water to prepare sodium ferrocyanide solution and iron salt solution, respectively. The iron salt solution was slowly added dropwise to the sodium ferrocyanide solution under stirring to carry out the reaction. The reaction products were then centrifuged, washed and dried to obtain Prussian blue analog powder. The second polymer solution is prepared by dissolving polyethylene oxide in acetonitrile or dichloromethane. Prussian blue analog powder was dispersed in a second polymer solution, and the solvent was removed by solvent evaporation while stirring or spray granulation was performed to obtain PEO-coated core-shell structure powder. The PEO-coated core-shell structure powder was dried to obtain a cyclically released sodium supplement component with a shell thickness of 10-50 nm. The cyclically sustained-release sodium supplement components prepared by electrostatic spraying include: Citric acid and sodium hydroxide were dissolved in anhydrous ethanol and stirred to react. The solvent was then removed by vacuum evaporation to obtain crude sodium citrate. The crude sodium citrate was then recrystallized and dried to obtain high-purity sodium citrate powder. Polyacrylonitrile was dissolved in N,N-dimethylformamide to prepare a third polymer solution; High-purity sodium citrate powder was dispersed in a third polymer solution, and PAN-coated core-shell structured microsphere powder was obtained by electrostatic spraying. The PAN-coated core-shell structured microsphere powder was dried to obtain a cyclically released sodium supplement component with a shell thickness of 10-50 nm.
[0029] According to the present invention, the melting temperature is 120-150°C; The dispersant stabilizer is selected from at least one of oleic acid, stearic acid, and paraffin oil, and its addition amount accounts for 0.5-5% of the mass of metallic sodium; Add the dispersant stabilizer and stir at 500-1500 rpm for 10-30 minutes; The pre-cooling temperature is -10 to -10℃; The shear emulsification rate is 3000-10000 rpm, and the time is 1-10 min; The washing agent used for washing the solids obtained from solid-liquid separation is anhydrous hexane or heptane, and the washing is performed 2-5 times. The drying is performed under vacuum at a temperature of 20-40℃ for 1-4 hours. Sodium metal, alloying elements, and ball milling aids are mixed in an atomic ratio of 1-4:1; The alloying element is selected from at least one of Sn, Sb, and Bi; The ball milling aid is stearic acid or graphite, and its addition amount accounts for 1-5% of the total mass of metallic sodium, alloying elements and ball milling aid; The ball milling is carried out under an argon atmosphere, with a ball-to-material ratio of 15-40:1, a rotation speed of 400-800 rpm, and a time of 5-30 hours. There is a 0.5-hour interval between each 1-2 hours of ball milling to prevent overheating. The molar ratio of sodium borohydride to sodium-containing compounds is 1:0.5-2; The sodium-containing compound is selected from at least one of sodium hydroxide, sodium carbonate, and sodium bicarbonate; The first organic solvent is anhydrous ethylenediamine or tetrahydrofuran; The concentration of the mixed solution is 0.5-2 mol / L; The crystal form control agent is polyethylene glycol or polyvinylpyrrolidone, and the amount added accounts for 0.1-1% of the total mass of the system; The crystallization reaction takes place at a temperature of 80-150℃ for 6-24 hours. The reaction products were cooled naturally, and anhydrous diethyl ether was used as the washing agent. The washing was performed 3-5 times. The drying was carried out under vacuum at a temperature of 40-60℃ for 12-24 hours. The mass ratio of sodium borohydride to surfactant is 10-50:1; The surfactant is Span-80, Tween-60, or CTAB; The second organic solvent is anhydrous tetrahydrofuran, ethylene glycol dimethyl ether, or toluene; The mass concentration of the dispersion is 5-20%; The ultrasonic cell disruptor used for ultrasonic treatment of the dispersion was an ultrasonic cell disruptor with a power of 200-800W and a treatment time of 10-60 min, while the system temperature was below 30℃. The detergent used for washing was anhydrous diethyl ether, and the number of washings was 2-4. The drying was carried out under vacuum at a temperature of 40-60℃ for 4-10 h. The molar ratio of ethylenediaminetetraacetic acid to sodium hydroxide is 1:3-5. The reaction is carried out in deionized water and stirred at 60-80℃ for 2-4 hours. The crude Na-EDTA was recrystallized 2-3 times and dried under vacuum at a temperature of 60-80℃ for 8-12 hours. The mass concentration of the first polymer solution is 5-15%; The mass ratio of Na-EDTA powder to the first polymer solution is 80-95:20-5; The inlet air temperature of the spray drying method is 120-160℃, the outlet air temperature is 60-80℃, and the feed rate is 5-20mL / min, to obtain PVDF-HFP coated Na-EDTA core-shell structured microspheres. The core-shell structured microsphere powder was dried under vacuum at a temperature of 50-70℃ for 6-10 hours. The molar ratio of sodium ferrocyanide to iron salt is 1:0.8-1.2; The iron salts are ferric chloride or ferric sulfate; The concentrations of the sodium ferrocyanide solution and the iron salt solution were each independently 0.1–0.5 mol / L; The iron salt solution is slowly added dropwise to the sodium ferrocyanide solution with stirring. The reaction temperature is 60-80℃ and the time is 4-8 hours. The reaction product was washed with deionized water and anhydrous ethanol alternately 3-5 times, and dried under vacuum at a temperature of 80-100℃ for 12-24 hours. The mass concentration of the second polymer solution is 3-10%; The solvent removal temperature by solvent evaporation is 40-60℃; The PEO-coated core-shell structure powder was dried under vacuum at a temperature of 40-60℃ for 8-12 hours. The molar ratio of citric acid to sodium hydroxide is 1:2.5-3.5; The concentration of the solution formed by dissolving citric acid and sodium hydroxide in anhydrous ethanol is 1-2 mol / L. The temperature for stirring the reaction of citric acid and sodium hydroxide in anhydrous ethanol is 50-70℃, and the time is 2-4 hours. The crude sodium citrate was recrystallized 2-3 times and dried under vacuum at a temperature of 50-70℃ for 6-10 hours. The mass concentration of the third polymer solution is 5-12%; The mass ratio of high-purity sodium citrate powder to citric acid is 80-90:20-10; The voltage for electrostatic spraying is 10-20kV, the receiving distance is 15-25cm, and the feeding rate is 1-5mL / h. The PAN-coated core-shell structured microsphere powder was dried under vacuum at a temperature of 60-80℃ for 6-10 hours.
[0030] In this invention, the composition and function of the sodium replenishment agent are defined: It protects the dual-component combination of a sodium-ion battery consisting of a "low-potential rapid sodium release component sodium-ion battery + a sodium-ion battery cyclic slow-release sodium replenishment component," clarifying the potential range, functional positioning (formation stage sodium-ion battery vs. cyclic stage sodium-ion battery), and material type (e.g., metallic sodium-ion battery / sodium-ion battery sodium alloy sodium-ion battery vs. sodium-ion battery sodium organic complex); The structure of the sodium replenishment agent is designed: it protects the nanoparticle morphology of the low-potential component (particle size 50–200 nm) and the core-shell structure of the cyclic slow-release component (core sodium-ion battery + sodium-ion battery ion-conducting polymer shell), emphasizing the role of structure in sodium release rate and gas generation suppression.
[0031] This invention also provides the application of the above-described full-cycle sodium replenishment agent or the full-cycle sodium replenishment agent prepared by the above-described preparation method in sodium-ion batteries, including: In the sodium battery preparation process, the low-potential fast sodium release component is mixed with the sodium battery negative electrode active material at a mass ratio of 1:5-1:10 and uniformly dispersed in the negative electrode slurry to ensure that the low-potential fast sodium release component is in close contact with the sodium battery negative electrode during the sodium battery formation stage and timely replenishes sodium to the sodium battery negative electrode. The cyclic slow-release sodium replenishment component is mixed with the positive electrode active material of the sodium battery at a mass ratio of 1:8 to 1:12 and uniformly dispersed in the positive electrode slurry of the sodium battery. During the cycle of the sodium battery, the cyclic slow-release sodium replenishment component slowly releases sodium ions with the charge and discharge reaction of the positive electrode of the sodium battery, so as to continuously replenish sodium to the positive and negative electrodes of the sodium battery.
[0032] In this invention, the mixing ratio and process of the protective sodium supplement with the positive and negative electrodes (e.g., the low potential component in the negative electrode slurry accounts for 5-20 wt% of sodium-ion batteries, and the cyclic slow-release component in the positive electrode slurry accounts for 5-15 wt% of sodium-ion batteries), and the specific formulation of the electrolyte (e.g., a mixed solvent of sodium-ion batteries NaPF6 / EC-DEC sodium-ion batteries).
[0033] The present invention further provides a sodium-ion battery having the above-described full-cycle sodium replenishment agent or the full-cycle sodium replenishment agent prepared by the above-described preparation method, comprising: The positive electrode contains a cyclically released sodium replenishment component; The negative electrode has a low potential for rapid sodium release; The electrolyte is an organic electrolyte containing sodium ions; Diaphragm.
[0034] This invention possesses the technical advantage of full-cycle sodium replenishment: protecting the synergistic effect of sodium-ion batteries with "controllable gas production + continuous sodium replenishment".
[0035] According to the present invention, the solute of the organic electrolyte is at least one of sodium hexafluorophosphate and sodium tetrafluoroborate, and the solvent is a mixture of at least two of ethylene carbonate, diethyl carbonate and propylene carbonate in a volume ratio of 1:1 to 2:1.
[0036] The present invention will be described in more detail below through embodiments.
[0037] Example 1
[0038] This embodiment provides a method for preparing a full-cycle sodium replenishment agent and the preparation and testing of a sodium-ion battery with the full-cycle sodium replenishment agent. The specific steps are as follows: (1) Preparation of sodium supplement: Low-potential rapid sodium release component: The sodium metal was melted at 135°C under argon protection using a melt emulsification-low-temperature solidification method. 1% oleic acid was added as a dispersant and stabilizer, and the mixture was stirred at 800 rpm for 20 min. The molten sodium was then transferred to anhydrous mineral oil at 0°C and emulsified at 5000 rpm for 5 min. The mixture was washed three times with anhydrous heptane and vacuum dried at 30°C for 2 h to obtain sodium metal nanoparticles with an average particle size of 80 nm. Circulating buffer components: A Na-EDTA complex was prepared as the core using spray drying. Polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) was dissolved in N-methyl-2-pyrrolidone (NMP) to prepare a 10% (w / w) solution. Then, Na-EDTA was dispersed in this solution (Na-EDTA:PVDF-HFP mass ratio = 90:10). The core-shell structure was formed by spray drying (inlet air temperature 150℃, outlet air temperature 70℃). The polymer shell thickness was approximately 20 nm. (2) Battery fabrication: Negative electrode preparation: Hard carbon, conductive acetylene black, and polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 85:10:5. A low-potential fast sodium release component (accounting for 8% of the mass of the negative electrode active material) is added. A negative electrode slurry is prepared using NMP as a solvent, coated on copper foil, and dried to form a negative electrode sheet. Positive electrode preparation: P2-Na 2 / 3 Ni 1 / 3 Mn 1 / 3 Ti 1 / 3 O2, conductive carbon nanotubes, and PVDF are mixed in a mass ratio of 80:10:10. A circulating buffer component (accounting for 10% of the mass of the positive electrode active material) is added. NMP is used as a solvent to prepare a positive electrode slurry, which is then coated on aluminum foil and dried to form a positive electrode plate. Electrolyte preparation: Sodium hexafluorophosphate (NaPF6) was dissolved in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) (volume ratio 1:1) to prepare an electrolyte with a concentration of 1.2 mol / L. Battery assembly: In a glove box filled with argon gas, the positive and negative plates are separated by a diaphragm, electrolyte is injected, and the sodium-ion battery is assembled. (3) Battery performance test: The assembled battery underwent its first formation at 0.01-1.5V vs. Na. + Within the Na decomposition potential range, the low-potential fast-release sodium component rapidly decomposes, releasing 100% of sodium ions. The gas generated during the formation process is removed by vacuum extraction. In subsequent cyclic tests, a 1C current was applied at 1.5-4.0V versus Na. + The battery is charged and discharged within the / Na decomposition potential range. The cycle buffer components slowly release sodium ions. After 1500 cycles, the battery capacity retention rate reaches 88%, and there is no obvious gas expansion phenomenon in the cell during the cycle.
[0039] Example 2
[0040] This embodiment provides a method for preparing a full-cycle sodium replenishment agent and the preparation and testing of a sodium-ion battery with the full-cycle sodium replenishment agent. The specific steps are as follows: (1) Preparation of sodium supplement: Low-potential rapid sodium release component: Sodium borohydride (NaBH4) and Span-80 surfactant were mixed at a mass ratio of 20:1 using ultrasonic dispersion, and then added to tetrahydrofuran to prepare a 10% dispersion. The dispersion was ultrasonically treated with an ultrasonic cell disruptor at 500W power for 30 min, while keeping the system temperature below 30℃. After centrifugation, the nanoparticles were washed three times with tetrahydrofuran and vacuum dried at 50℃ for 6 h to obtain sodium borohydride nanoparticles with an average particle size of 120 nm. The circulating buffer component: A Na-EDTA complex was prepared using spray drying to form the core. PVDF-HFP was dissolved in NMP to prepare a 12% (w / w) solution. Then, Na-EDTA was dispersed in the solution (Na-EDTA:PVDF-HFP mass ratio = 85:15). The core-shell structure was formed by spray drying (inlet air temperature 150℃, outlet air temperature 70℃). The polymer shell thickness was approximately 30 nm. (2) Battery fabrication: Negative electrode preparation: Soft carbon, conductive graphite, styrene-butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC) are mixed in a mass ratio of 80:10:5:5. A low-potential fast sodium release component (accounting for 7% of the mass of the negative electrode active material) is added. A negative electrode slurry is prepared using deionized water as a solvent, coated on copper foil, and dried to form a negative electrode sheet. Positive electrode preparation: O3-NaFeO2, conductive acetylene black, and PVDF are mixed in a mass ratio of 82:8:10. A circulating buffer component (accounting for 9% of the positive electrode active material mass) is added. A positive electrode slurry is prepared using NMP as a solvent, coated on aluminum foil, and dried to form a positive electrode plate. Electrolyte preparation: Sodium tetrafluoroborate (NaBF4) is dissolved in a mixed solvent of ethylene carbonate (EC) and propylene carbonate (PC) (volume ratio 2:1) to prepare an electrolyte with a concentration of 1.0 mol / L. Battery assembly: In a glove box filled with argon gas, the positive and negative plates are separated by a diaphragm, electrolyte is injected, and the sodium-ion battery is assembled. (3) Battery performance test: During the initial formation process, the low-potential rapid sodium release component occurs at 0.01-1.5 V vs. Na. + The reaction proceeds rapidly within the Na decomposition potential range, replenishing sodium at the negative electrode, and the generated gas is expelled through vacuum. This occurs at a 1C current and 1.5-4.0V vs. Na. + Cyclic testing was conducted at the / Na decomposition potential range. After 1000 cycles, the battery capacity retention rate was 90%. The battery appearance remained unchanged during the cycle, and no gas expansion was observed.
[0041] Comparative Example 1
[0042] This comparative example uses conventional sodium oxalate as a sodium supplement agent to prepare sodium-ion batteries according to standard methods. During battery formation, sodium oxalate decomposes to produce carbon dioxide gas. Although some gas is released during formation, it continues to be generated during subsequent cycles, causing the battery to gradually expand. This is observed at a current of 0.5C and a voltage range of 1.5-4.0V vs. Na... + After 200 cycles within the / Na decomposition potential range, the battery capacity retention rate is only 65%, and the cell thickness increases significantly.
[0043] Comparative Example 2
[0044] This comparative example only uses a low-potential, rapid sodium release component (same as the metallic sodium nanoparticles in Example 1) during the battery formation stage, and does not use a cyclically slow-release sodium replenishment component during cycling; at a current of 0.5C and a voltage of 1.5-4.0V vs. Na... + Cycling within the Na decomposition potential range effectively compensates for negative electrode losses during the formation stage, but as the number of cycles increases, the battery capacity rapidly declines due to the lack of continuous sodium replenishment, and the battery capacity retention drops to 60% after 150 cycles.
[0045] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.
Claims
1. A full-cycle sodium supplement, characterized in that, include: Low-potential, rapid sodium release component, existing in nanoparticle form, with a decomposition potential of 0.01-1.5V. Sodium-ion battery vs. sodium-ion battery. + / Na is used to replenish sodium to the negative electrode during the battery formation stage; Cyclic slow-release sodium replenishment component, with a core-shell structure, decomposition potential of 1.5-4.0V. Sodium-ion battery vs. sodium-ion battery Na. + / Na is used to continuously replenish sodium to the positive and negative electrodes during battery cycling.
2. The full-cycle sodium supplement according to claim 1, characterized in that, The average particle size of the nanoparticles is 50-200 nm. The outer shell of the core-shell structure has a thickness of 10-50 nm.
3. The full-cycle sodium supplement according to claim 1, characterized in that, The low-potential rapid sodium-releasing component includes at least one of metallic sodium, sodium alloy, or sodium borohydride. The core of the core-shell structure is a sodium-supplementing active substance, and the outer shell is a polymer with ion conductivity.
4. The full-cycle sodium supplement according to claim 3, characterized in that, The sodium-supplementing active substance is a sodium-ethylenediaminetetraacetic acid complex and / or a sodium Prussian blue analogue: The ion-conducting polymer is a polyvinylidene fluoride-hexafluoropropylene copolymer.
5. A method for preparing a full-cycle sodium supplement according to any one of claims 1-4, characterized in that, include: Low-potential, fast-release sodium components can be prepared by melt emulsification-low-temperature solidification, high-energy ball milling-solid-phase reaction, solvothermal-recrystallization, or ultrasonic dispersion. Cyclic slow-release sodium supplement components can be prepared by spray drying, solvent evaporation, or electrostatic spraying.
6. The preparation method according to claim 5, characterized in that, The low-potential, fast-release sodium components prepared by the melt emulsification-low-temperature solidification method include: Under argon protection, metallic sodium is heated to molten state, and a dispersing stabilizer is added and stirred to obtain a molten sodium emulsion; The molten sodium emulsion is transferred to pre-cooled anhydrous mineral oil or white oil and sheared and emulsified to obtain an emulsion; The emulsion was subjected to solid-liquid separation under argon protection. The resulting solid was washed and dried sequentially to obtain a low-potential rapid sodium release component with a particle size distribution of 50-200 nm. The low-potential, fast-release sodium components prepared by the high-energy ball milling-solid-phase reaction method include: The sodium metal, alloying elements, and ball milling aid are mixed and then ball milled. The ball-milled powder was sieved and classified under an inert atmosphere to obtain a low-potential rapid sodium-releasing component with a particle size distribution of 50-200 nm. The low-potential rapid sodium release components prepared by the solvothermal-recrystallization method include: Sodium borohydride is mixed with a sodium-containing compound and dissolved in a first organic solvent to prepare a mixed solution; A crystal form control agent is added to the mixed solution to carry out a crystallization reaction to obtain the reaction product; The reaction product was sequentially cooled, filtered, washed, and dried, and then refined by air jet milling or ball milling under argon protection to obtain a low-potential rapid sodium release component with a particle size of 50-200 nm. The low-potential, fast-release sodium components prepared by ultrasonic dispersion include: Sodium borohydride was mixed with a surfactant and then added to a second organic solvent to prepare a dispersion. The dispersion was subjected to ultrasonic treatment, centrifugation, washing, and drying in sequence to obtain a low-potential rapid sodium release component with a particle size of 50-200 nm. The cyclic slow-release sodium supplement component prepared by spray drying includes: Ethylenediaminetetraacetic acid (EDTA) and sodium hydroxide were mixed and dissolved in deionized water to carry out the reaction. After the reaction was completed, the mixture was concentrated under reduced pressure, cooled and crystallized, and filtered to obtain crude Na-EDTA. The crude Na-EDTA was then recrystallized and dried to obtain Na-EDTA powder with a particle size of 100-300 nm. The polyvinylidene fluoride-hexafluoropropylene copolymer is dissolved in N-methyl-2-pyrrolidone or acetone to prepare a first polymer solution; The Na-EDTA powder was dispersed in the first polymer solution and coated by spray drying to obtain core-shell structured microsphere powder. The core-shell structured microsphere powder was dried to obtain a cyclically released sodium supplement component with a shell thickness of 10-50 nm. The preparation of cyclically released sodium supplement components via solvent evaporation includes: Sodium ferrocyanide and iron salt were dissolved in deionized water to prepare sodium ferrocyanide solution and iron salt solution, respectively. The iron salt solution was slowly added dropwise to the sodium ferrocyanide solution under stirring to carry out the reaction. The reaction products were then centrifuged, washed and dried to obtain Prussian blue analog powder. The second polymer solution is prepared by dissolving polyethylene oxide in acetonitrile or dichloromethane. The Prussian blue analog powder is dispersed in the second polymer solution, the solvent is removed by solvent evaporation, and the mixture is stirred or spray granulated to obtain PEO-coated core-shell structure powder. The PEO-coated core-shell structure powder was dried to obtain a cyclically released sodium supplement component with a shell thickness of 10-50 nm. The cyclically sustained-release sodium supplement components prepared by electrostatic spraying include: Citric acid and sodium hydroxide were dissolved in anhydrous ethanol and stirred to react. The solvent was then removed by vacuum evaporation to obtain crude sodium citrate. The crude sodium citrate was then recrystallized and dried to obtain high-purity sodium citrate powder. Polyacrylonitrile was dissolved in N,N-dimethylformamide to prepare a third polymer solution; The high-purity sodium citrate powder was dispersed in the third polymer solution, and PAN-coated core-shell structured microsphere powder was obtained by electrostatic spraying. The PAN-coated core-shell structured microsphere powder is dried to obtain a cyclically released sodium supplement component with a shell thickness of 10-50 nm.
7. The preparation method according to claim 5, characterized in that, The melting temperature is 120-150℃; The dispersant stabilizer is selected from at least one of oleic acid, stearic acid, and paraffin oil, and is added in an amount of 0.5-5% of the mass of sodium metal. Add the dispersant stabilizer and stir at 500-1500 rpm for 10-30 minutes; The pre-cooling temperature is -10 to 10°C; The shear emulsification rate is 3000-10000 rpm, and the time is 1-10 min; The washing agent used for washing the solids obtained from solid-liquid separation is anhydrous hexane or heptane, and the washing is performed 2-5 times. The drying is performed under vacuum at a temperature of 20-40℃ for 1-4 hours. Sodium metal, alloying elements, and ball milling aids are mixed in an atomic ratio of 1-4:1; The alloying element is selected from at least one of Sn, Sb and Bi; The ball milling aid is stearic acid or graphite, and its addition amount accounts for 1-5% of the total mass of metallic sodium, alloying elements and ball milling aid; The ball milling is carried out under an argon atmosphere, with a ball-to-material ratio of 15-40:1, a rotation speed of 400-800 rpm, and a time of 5-30 hours, with a 0.5-hour interval between each 1-2 hours of ball milling to prevent overheating; The molar ratio of sodium borohydride to sodium-containing compounds is 1:0.5-2; The sodium-containing compound is selected from at least one of sodium hydroxide, sodium carbonate, and sodium bicarbonate; The first organic solvent is anhydrous ethylenediamine or tetrahydrofuran; The concentration of the mixed solution is 0.5-2 mol / L; The crystal form control agent is polyethylene glycol or polyvinylpyrrolidone, and the amount added accounts for 0.1-1% of the total mass of the system; The crystallization reaction is carried out at a temperature of 80-150℃ for 6-24 hours. The reaction product was cooled naturally, and the washing agent was anhydrous diethyl ether. The washing was performed 3-5 times, and the drying was performed under vacuum at a temperature of 40-60°C for 12-24 hours. The mass ratio of sodium borohydride to surfactant is 10-50:1; The surfactant is Span-80, Tween-60, or CTAB; The second organic solvent is anhydrous tetrahydrofuran, ethylene glycol dimethyl ether, or toluene; The mass concentration of the dispersion is 5-20%; The ultrasonic treatment of the dispersion was performed using an ultrasonic cell disruptor with a power of 200-800W, a treatment time of 10-60 minutes, and a system temperature below 30°C. The washing agent was anhydrous diethyl ether, and the washing was performed 2-4 times. The drying was performed under vacuum at a temperature of 40-60°C for 4-10 hours. The molar ratio of ethylenediaminetetraacetic acid to sodium hydroxide is 1:3-5. The reaction is carried out in deionized water and stirred at 60-80℃ for 2-4 hours. The crude Na-EDTA product is recrystallized 2-3 times and dried under vacuum at a temperature of 60-80°C for 8-12 hours. The mass concentration of the first polymer solution is 5-15%; The mass ratio of the Na-EDTA powder to the first polymer solution is 80-95:20-5; The spray drying method has an inlet air temperature of 120-160℃, an outlet air temperature of 60-80℃, and a feed rate of 5-20mL / min, to obtain PVDF-HFP coated Na-EDTA core-shell structured microspheres. The core-shell structured microsphere powder was dried under vacuum at a temperature of 50-70°C for 6-10 hours. The molar ratio of sodium ferrocyanide to iron salt is 1:0.8-1.2; The iron salt is ferric chloride or ferric sulfate; The concentrations of the sodium ferrocyanide solution and the iron salt solution are each independently 0.1-0.5 mol / L; The iron salt solution is slowly added dropwise to the sodium ferrocyanide solution under stirring at a temperature of 60-80°C for 4-8 hours. The reaction product was washed with deionized water and anhydrous ethanol alternately 3-5 times, and dried under vacuum at a temperature of 80-100℃ for 12-24 hours. The mass concentration of the second polymer solution is 3-10%; The solvent evaporation method is used to remove the solvent at a temperature of 40-60℃. The PEO-coated core-shell structure powder was dried under vacuum at a temperature of 40-60°C for 8-12 hours. The molar ratio of citric acid to sodium hydroxide is 1:2.5-3.5; The concentration of the solution formed by dissolving citric acid and sodium hydroxide in anhydrous ethanol is 1-2 mol / L. The temperature for stirring the reaction of citric acid and sodium hydroxide in anhydrous ethanol is 50-70℃, and the time is 2-4 hours. The crude sodium citrate is recrystallized 2-3 times, and the drying is carried out under vacuum at a temperature of 50-70°C for 6-10 hours. The mass concentration of the third polymer solution is 5-12%; The mass ratio of the high-purity sodium citrate powder to the citric acid is 80-90:20-10; The electrostatic spraying method has a voltage of 10-20kV, a receiving distance of 15-25cm, and a feeding rate of 1-5mL / h. The PAN-coated core-shell structured microsphere powder was dried under vacuum at a temperature of 60-80°C for 6-10 hours.
8. The application of a full-cycle sodium replenisher according to any one of claims 1-4, or a full-cycle sodium replenisher prepared by any one of claims 5-7, in a sodium-ion battery, characterized in that, include: In the sodium battery preparation process, the low-potential fast sodium release component is mixed with the sodium battery negative electrode active material at a mass ratio of 1:5-1:10 and uniformly dispersed in the negative electrode slurry to ensure that the low-potential fast sodium release component is in close contact with the sodium battery negative electrode during the sodium battery formation stage, and timely replenishment of sodium to the sodium battery negative electrode. The cyclic slow-release sodium replenishing component is mixed with the positive electrode active material of the sodium battery at a mass ratio of 1:8 to 1:12 and uniformly dispersed in the positive electrode slurry of the sodium battery. During the cycle of the sodium battery, the cyclic slow-release sodium replenishing component slowly releases sodium ions with the charge and discharge reaction of the positive electrode of the sodium battery, so as to continuously replenish sodium to the positive and negative electrodes of the sodium battery.
9. A sodium-ion battery having a full-cycle sodium replenisher as described in any one of claims 1-4 or a full-cycle sodium replenisher prepared by the preparation method described in any one of claims 5-7, characterized in that, include: The positive electrode contains a cyclically released sodium replenishment component; The negative electrode has a low potential for rapid sodium release; The electrolyte is an organic electrolyte containing sodium ions; Diaphragm.
10. The sodium-ion battery according to claim 9, characterized in that, The solute of the organic electrolyte is at least one of sodium hexafluorophosphate and sodium tetrafluoroborate, and the solvent is a mixture of at least two of ethylene carbonate, diethyl carbonate and propylene carbonate in a volume ratio of 1:1 to 2:1.