Nanometer iron oxide composite material and application of nanometer iron oxide composite material in negative electrode of sodium-ion battery
By modifying with oleic acid and compositing with rGO, a three-dimensional conductive network was constructed, which solved the problems of poor conductivity and short cycle life of nano-Fe3O4 in sodium-ion batteries, achieving efficient electron transport and structural stability, and improving the electrochemical performance of the material.
Patent Information
- Application Number
- CN202511120824.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-12
- Publication Date
- 2025-11-18
AI Technical Summary
Nano-Fe3O4 in sodium-ion batteries suffers from problems such as poor conductivity, short cycle life, and large volume expansion, especially with severe capacity decay at high rates, which is difficult to solve effectively with existing technologies.
A three-dimensional conductive network was constructed by combining oleic acid-modified and reduced graphene oxide (rGO). Oleic acid-modified Fe3O4 nanoparticles were uniformly dispersed on rGO sheets to form a stable conductive network structure, which enhanced electron/ion transport efficiency. Furthermore, the volume expansion of rGO was buffered by its elasticity, which stabilized the solid electrolyte interphase (SEI) film.
The conductivity of the nano-iron oxide composite material was significantly improved, the charge transport was significantly reduced, the charge transport efficiency of the electrochemical electrode material was improved, an efficient electron transport channel was realized, the structural stability and cycle life of the material were enhanced, and the capacity and rate performance were improved.
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Figure CN120978035A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of sodium-ion battery anode material technology, specifically to a nano-iron oxide composite material and its application in sodium-ion battery anodes. Background Technology
[0002] With the global energy structure transformation and the rapid development of renewable energy, cost-effective and safe energy storage technologies have become a research hotspot. Sodium-ion batteries (SIBs) are considered one of the ideal choices for large-scale energy storage due to the abundance and low cost of sodium resources and their electrochemical properties similar to lithium. However, the larger radius of sodium ions compared to lithium ions leads to poorer diffusion kinetics in electrode materials, placing higher demands on anode materials. Therefore, developing sodium-ion battery anode materials with high capacity, excellent rate performance, and long cycle life is crucial.
[0003] Among numerous anode materials, transition metal oxides (such as Fe3O4) have attracted much attention due to their high theoretical specific capacity, environmental friendliness, and low cost. Nanoscale Fe3O4, in particular, with its smaller particle size, can shorten the sodium ion diffusion path and improve reaction kinetics. However, nanoscale Fe3O4 still faces the following problems in practical applications: poor conductivity: Fe3O4 has low intrinsic conductivity, leading to slow charge transport within the electrode and severe capacity decay at high rates; severe volume expansion: during charge and discharge, repeated insertion / extraction of sodium ions causes drastic expansion and contraction of the Fe3O4 lattice, resulting in electrode structure pulverization, active material shedding, and a sharp decline in cycle stability; nanoparticle agglomeration: when the Fe3O4 particle size decreases to 3–5 nm, the surface energy increases significantly, making particles prone to agglomeration, which not only reduces the effective specific surface area but also hinders electrolyte wetting, deteriorating electrochemical performance; interfacial instability: nanoscale Fe3O4 exhibits numerous side reactions with the electrolyte, and the solid electrolyte interphase (SEI) film repeatedly ruptures / regenerates, exacerbating capacity decay.
[0004] Therefore, to address the aforementioned problems, this invention provides a nano-iron oxide composite material and its application in the anode of sodium-ion batteries. Through the synergistic effect of oleic acid surface modification and reduced graphene oxide (rGO), oleic acid molecules chemically adsorb and coat Fe3O4 nanoparticles, inhibiting aggregation and enhancing dispersibility; rGO constructs a three-dimensional conductive network, improving electron / ion transport efficiency while elastically buffering volume expansion; the strong interfacial coupling between Fe3O4 and rGO stabilizes the SEI film and reduces side reactions. This invention provides a new approach for the development of high-performance sodium-ion battery anode materials. Summary of the Invention
[0005] The purpose of this invention is to provide a nano-iron oxide composite material and its application in the anode of sodium-ion batteries. By modifying with oleic acid and reducing graphene oxide, a stable conductive network structure is constructed, which improves its capacity, rate performance and cycle stability in sodium-ion batteries, thereby solving the problems of poor conductivity, short cycle life and large volume expansion of nano-Fe3O4.
[0006] The objective of this invention is achieved through the following technical solution:
[0007] A nano-iron oxide composite material includes oleic acid-modified Fe3O4 nanoparticles and reduced graphene oxide (rGO), wherein the Fe3O4 nanoparticles are uniformly dispersed and anchored on rGO sheets to form a three-dimensional conductive network structure.
[0008] Preferably, the average particle size of the Fe3O4 nanoparticles is 3-5 nm, more preferably 3.8 nm.
[0009] Preferably, the oleic acid-modified Fe3O4 nanoparticles are prepared by a high-temperature thermal decomposition method, specifically as follows: high-purity Fe(acac)3 is selected as the iron source material, and under a nitrogen protective atmosphere, Fe(acac)3 and oleic acid are mixed in a molar ratio of 1:4-6 and placed in a high-temperature reactor for thermal decomposition at 300-350°C; after the reaction, the reaction system is naturally cooled to room temperature, washed three times alternately with hexane and ethanol, and centrifuged to obtain oleic acid-modified Fe3O4 nanoparticles; wherein the purity of the high-purity Fe(acac)3 is ≥99%.
[0010] Preferably, the rGO is prepared by reducing graphene oxide (GO) with ascorbic acid, wherein the mass ratio of ascorbic acid to GO is 5-6:1; more preferably 5:1.
[0011] This application also claims a method for preparing the above-mentioned nano-iron oxide composite material, comprising the following steps:
[0012] (1) Add oleic acid-modified Fe3O4 nanoparticles to a graphene oxide aqueous dispersion with a mass concentration of 1.8-2.2 mg / mL, and use an ultrasonic instrument with a power of 180-220W to continuously sonicate for 25-35 minutes to ensure that the Fe3O4 nanoparticles are uniformly dispersed in the liquid phase and fully contacted with the graphene oxide.
[0013] (2) Add ascorbic acid slowly to it, and control the mass ratio of ascorbic acid to graphene oxide to be 5-6:1. Continue stirring and transfer the mixture to a polytetrafluoroethylene hydrothermal reactor. React at 78-82℃ for 5.5-6.5h. During the reaction, ascorbic acid reduces GO to rGO and induces the formation of a chemical / physical composite structure between Fe3O4 nanoparticles and rGO.
[0014] (3) After the reaction is complete, the product is washed three times with deionized water and anhydrous ethanol, centrifuged and then vacuum dried at 60°C for 12-16 hours to obtain Fe3O4@rGO composite material.
[0015] This application also claims protection for a sodium-ion battery negative electrode, comprising the above-mentioned nano-iron oxide composite material as an active material.
[0016] Preferably, the method for preparing the sodium-ion battery negative electrode includes: mixing Fe3O4@rGO composite material, PVDF binder and conductive carbon (SuperP) in a mass ratio of 7-9:1:1, adding NMP solvent to prepare a slurry, uniformly coating it on a copper foil, controlling the dry film thickness between 50 and 80 μm, and then vacuum drying the electrode sheet at 120°C for 12-16 hours before punching it into a Φ12 mm disc for use as a working electrode.
[0017] More preferably, the Fe3O4@rGO composite material, PVDF binder, and conductive carbon (SuperP) are mixed in a mass ratio of 8:1:1.
[0018] This application also claims a sodium-ion battery, including the aforementioned negative electrode, a sodium metal counter electrode, a separator, and an electrolyte containing NaPF6.
[0019] Preferably, the electrolyte is a 1 mol / L NaPF6 solution, and the volume ratio of EC to DEC in the NaPF6 solution is 1:1.
[0020] Preferably, the negative electrode has an initial specific capacity of ≥470mAh / g at a current density of 0.1A / g, and a capacity retention rate of ≥82% after 100 cycles.
[0021] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art:
[0022] 1. The three-dimensional continuous conductive network constructed by rGO in this invention provides an efficient channel for electron transport, which significantly improves the intrinsic low conductivity of Fe3O4; the charge transfer resistance of the composite material is reduced by more than 70%, which enables the electrode to maintain stable electrochemical performance at high rates.
[0023] 2. This invention has excellent structural stability. The flexible layered structure of rGO can effectively buffer the 200-250% volume change of Fe3O4 during charge and discharge, preventing the electrode material from pulverizing and falling off. At the same time, the oleic acid-modified Fe3O4 nanoparticles are uniformly anchored on the surface of rGO, inhibiting the aggregation of active materials and ensuring the structural integrity during cycling.
[0024] 3. When the composite material of the present invention is used as the negative electrode of sodium-ion battery, it exhibits a high initial specific capacity of 470 mAh / g and can still maintain 82% of the capacity retention rate after 100 cycles. It has excellent rate performance, and the capacity decay rate does not exceed 10% under different current densities. Its overall performance is more than 70% higher than that of unmodified Fe3O4.
[0025] 4. The oleic acid modification and hydrothermal composite method used in this invention is simple, has mild conditions, good repeatability, does not require complex equipment or expensive raw materials, is easy to scale up, and has significant industrialization advantages.
[0026] 5. By optimizing the material composition and structural design, this invention significantly reduces production costs while ensuring excellent electrochemical performance. Compared with other modification methods (such as metal doping or complex carbon coating), this solution is more competitive in the market. Furthermore, the raw materials used are non-toxic and harmless, and the preparation process is green and environmentally friendly, meeting the requirements of sustainable development. Attached Figure Description
[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, some of the drawings in the following description are some embodiments of the present invention. For those skilled in the art, other drawings can be made based on these drawings without creative effort.
[0028] Figure 1 This is a transmission electron microscope (TEM) image of the Fe3O4@rGO composite material from Example 1 of this invention;
[0029] Figure 2 This is a schematic diagram of the composite structure of Fe3O4@rGO composite material in Example 1 of the present invention;
[0030] Figure 3 This is the XRD pattern of the Fe3O4@rGO composite material in Example 1 of this invention;
[0031] Figure 4 This is the Raman spectrum of the Fe3O4@rGO composite material in Example 1 of this invention. Detailed Implementation
[0032] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific implementation schemes are now described in detail.
[0033] The present invention will be further described below with reference to embodiments, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.
[0034] Example 1
[0035] See appendix Figure 1 -Appendix Figure 4 This embodiment provides a nano-iron oxide composite material, including oleic acid-modified Fe3O4 nanoparticles and reduced graphene oxide (rGO), wherein the Fe3O4 nanoparticles are uniformly dispersed and anchored on the rGO sheets to form a three-dimensional conductive network structure.
[0036] The average particle size of the Fe3O4 nanoparticles is 3.8 nm;
[0037] The oleic acid-modified Fe3O4 nanoparticles were prepared by a high-temperature thermal decomposition method. Specifically, high-purity Fe(acac)3 (purity ≥99%) was selected as the iron source material. Under a nitrogen protective atmosphere, Fe(acac)3 and oleic acid were mixed at a molar ratio of 1:5 and placed in a high-temperature reactor for thermal decomposition at 320°C. During the reaction, oleic acid molecules underwent coordination and degradation reactions with Fe(acac)3 at high temperature, gradually generating nano-Fe3O4 particles with an average particle size of 3.8 nm. Oleic acid uniformly modified the Fe3O4 surface through chemical adsorption and physical coating, improving the dispersibility and surface stability of the particles. After the reaction, the reaction system was naturally cooled to room temperature, washed three times alternately with hexane and ethanol, and centrifuged to obtain the oleic acid-modified Fe3O4 nanoparticles.
[0038] The preparation method of the above-mentioned nano-iron oxide composite material includes the following steps:
[0039] (1) Oleic acid-modified Fe3O4 nanoparticles were added to a graphene oxide aqueous dispersion with a mass concentration of 2 mg / mL and sonicated continuously for 30 minutes using a 200W ultrasonic instrument to ensure that the Fe3O4 nanoparticles were uniformly dispersed in the liquid phase and fully contacted with the graphene oxide.
[0040] (2) Add ascorbic acid slowly to it, and control the mass ratio of ascorbic acid to graphene oxide to be 5:1. Continue stirring and transfer the mixture to a polytetrafluoroethylene hydrothermal reactor. React at 80°C for 6 hours. During the reaction, ascorbic acid reduces GO to rGO and induces the formation of a chemical / physical composite structure between Fe3O4 nanoparticles and rGO.
[0041] (3) After the reaction was completed, the product was washed three times with deionized water and anhydrous ethanol, centrifuged, and then vacuum dried at 60°C for 12 hours to obtain Fe3O4@rGO composite material.
[0042] This embodiment also provides a sodium-ion battery anode, comprising the above-mentioned nano-iron oxide composite material as the active material; the preparation method of the sodium-ion battery anode includes: mixing Fe3O4@rGO composite material, PVDF binder and conductive carbon (SuperP) in a mass ratio of 8:1:1, adding NMP solvent to prepare a slurry, uniformly coating it on a copper foil, controlling the dry film thickness between 50 and 80 μm, and then vacuum drying the electrode sheet at 120°C for 12 hours before punching it into a Φ12 mm disc for use as a working electrode;
[0043] This embodiment also provides a sodium-ion battery, including the above-mentioned negative electrode, a sodium metal counter electrode, a separator, and an electrolyte containing NaPF6; the electrolyte is a 1 mol / L NaPF6 solution, and the volume ratio of EC to DEC in the NaPF6 solution is 1:1; specifically, a CR2032 coin cell sodium-ion battery is assembled in a glove box, the negative electrode is the electrode sheet made by the embodiment, the counter electrode is sodium metal, the separator is Celgard2300, and the electrolyte is 1 mol / L NaPF6 (EC:DEC = 1:1, volume ratio); after the battery is assembled, charge and discharge tests are performed on the Blue Electric Electrochemical Workstation.
[0044] Test results show that the material initially achieved a specific capacity of 470 mAh / g, and maintained 82% capacity retention after 100 cycles. At the same time, it exhibited excellent rate performance at different rates of 0.1, 0.2, 0.5, and 1 A / g, with a capacity decay rate of ≤10% / rate, which is far superior to the uncomposite Fe3O4 material, verifying its excellent sodium storage performance.
[0045] Furthermore, the Fe3O4@rGO composite material prepared in Example 1 was analyzed by XRD, Raman, and TEM. The XRD spectrum of the Fe3O4@rGO composite material is shown in the figure. Figure 3 This study demonstrates the crystallization characteristics of Fe3O4@rGO composite materials formed by combining oleic acid-modified Fe3O4 nanoparticles with a particle size of 3–5 nm with reduced graphene oxide; its main characteristics are as follows:
[0046] (i) All characteristic diffraction peaks of Fe3O4 can be identified, including: (220)≈30°, (311)≈35.4° (main peak), (400)≈43.2°, (422)≈53.5°, (511)≈57.1°, (440)≈62.7°. Compared with large-particle Fe3O4, all peaks show obvious broadening and intensity reduction, which is consistent with the nanocrystal characteristics predicted by the Scherrer effect.
[0047] (ii) A broad peak signal of rGO was observed at 2°≈25°, which is the interlayer reflection of (002) after the reduction of graphene oxide. The intensity is low and the peak width is large, indicating that there is a certain degree of disorder and defects in the layered structure of rGO.
[0048] (iii) The overall peak shape is relatively "blunt" and the background noise is relatively high, indicating that there is a certain amount of non-diffraction contribution caused by the coating of amorphous phase or surface modifier (such as oleic acid) in the composite material.
[0049] Raman spectrum of Fe3O4@rGO composite material (see) Figure 4 It can be seen that the Raman spectrum is in the range of 100–2000 cm⁻¹ -1 The typical vibrational modes of the two components, Fe3O4 and rGO, are shown within the range, and their main characteristics are as follows:
[0050] (a) Characteristic peak of Fe3O4: ~660cm -1 A1g mode: corresponds to the symmetric stretching vibration of the Fe-O bond; it is a typical characteristic peak of the spin-polarized structure of Fe3O4; the presence of this peak confirms that the Fe3O4 crystal structure remains stable after recombination.
[0051] (ii) rGO characteristic peak: ~1350cm -1 D peak (defect peak): Characterizes defects such as edges and vacancies in the graphite structure; the intensity of the D peak indicates that there is a certain degree of structural disturbance or incomplete reduction during the composite process;
[0052] ~1580cm -1 G peak (graphitization peak): corresponds to sp 2 The E2g mode vibration of hybrid carbon atoms indicates that rGO retains the framework structure of graphitized carbon; the appearance and intensity of the G peak indicate that rGO was successfully reduced and the structure is continuous in the composite material.
[0053] (III) D / G intensity ratio (I_D / I_G) analysis: If the D peak and G peak in the spectrum are similar in intensity (e.g., I_D / I_G≈0.9~1.1), it indicates that the rGO reduction degree is relatively high, but still retains more defects, which helps to enhance the binding with Fe3O4; the defect sites are beneficial to providing more anchoring sites and electron transport channels, which is beneficial to electrochemical performance.
[0054] Comparative Example 1
[0055] This comparative example is a mechanical mixture of Fe3O4 and graphite (without chemical bonding).
[0056] Comparative Example 2
[0057] This comparative example is Fe3O4@C carbon coating.
[0058] The products of Example 1, Comparative Example 1, and Comparative Example 2 were tested, and the test data are shown in Table 1.
[0059] Table 1
[0060] Testing items Example 1 Comparative Example 1 Comparative Example 2 Initial capacity (mAh / g) 470 350 420 Capacity retention rate after 100 cycles (%) 82 50 70 Volume expansion rate (%) 95 200 120 Charge transfer resistance (Ω) 210 700 350 Rate performance (capacity retention per A / g) (%) 88 45 75
[0061] As can be seen from the table above, in terms of conductivity, the charge transfer resistance of Example 1 is significantly lower than that of Comparative Example 1 and Comparative Example 2, with reductions of 70% and 40%, respectively. The physically mixed graphite of Comparative Example 1 only provides loose contact, resulting in low electron transport efficiency. Although the carbon coating layer of Comparative Example 2 improves conductivity, its thickness is uneven and the coverage is incomplete. The rGO of Example 1 forms a three-dimensional continuous network through chemical bonding, achieving efficient electron conduction. In terms of cycle stability, the electrode structure of Comparative Example 1 collapses after cycling due to the lack of volume expansion buffer. The carbon layer of Comparative Example 2 can partially suppress expansion, but cracks still appear during cycling. The rGO sheet elastically supports Fe3O4 in Example 1, reducing the expansion rate to 95% and the capacity retention rate to 82%. In terms of rate performance differences, the capacity retention rate of Example 1 at a high current of 1 A / g is much higher than that of Comparative Example 1, due to the high conductivity of rGO reducing polarization and the open structure accelerating sodium ion diffusion, while the dense carbon layers of Comparative Example 1 and Comparative Example 2 hinder ion transport. Chemical composites with rGO are more effective than physical mixing (Comparative Example 1) or traditional carbon coating (Comparative Example 2), improving overall performance by 30-50%. Oleic acid modification inhibits agglomeration, and rGO constructs a network with both conductive and buffering functions, achieving a synergistic effect mechanism. This enables simultaneous optimization of capacity, cycle life, and rate performance.
[0062] In summary, this invention provides an efficient channel for electron transport through a three-dimensional continuous conductive network constructed using rGO, significantly improving the intrinsic low conductivity of Fe3O4. The charge transfer resistance of the composite material is reduced by more than 70%, enabling the electrode to maintain stable electrochemical performance even at high rates. This invention exhibits excellent structural stability; the flexible layered structure of rGO effectively buffers the 200-250% volume change of Fe3O4 during charge and discharge, preventing electrode material pulverization and detachment. Simultaneously, oleic acid-modified Fe3O4 nanoparticles are uniformly anchored on the rGO surface, inhibiting the aggregation of active materials and ensuring structural integrity during cycling. When used as the anode of a sodium-ion battery, the composite material of this invention exhibits a high efficiency of 470 mAh / g. The initial specific capacity maintains 82% capacity retention after 100 cycles, demonstrating excellent rate performance. Capacity decay does not exceed 10% at different current densities, and overall performance is more than 70% higher than unmodified Fe3O4. The oleic acid modification and hydrothermal composite method employed in this invention is simple, mild, and highly reproducible, requiring no complex equipment or expensive raw materials, making it easy to scale up production and offering significant industrial advantages. By optimizing material composition and structural design, this invention significantly reduces production costs while ensuring excellent electrochemical performance. Compared to other modification methods (such as metal doping or complex carbon coating), this solution is more competitive in the market. Furthermore, the raw materials used are non-toxic and harmless, and the preparation process is green and environmentally friendly, meeting the requirements of sustainable development.
[0063] The above-described embodiments are merely one implementation of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that...
[0064] However, for those skilled in the art, without departing from the inventive concept,
[0065] Furthermore, several modifications and improvements can be made, all of which fall within the scope of protection of this invention.
[0066] Therefore, the scope of protection of this invention patent shall be determined by the appended claims.
Claims
1. A nano-iron oxide composite material, characterized in that, It includes oleic acid-modified Fe3O4 nanoparticles and reduced graphene oxide, wherein the Fe3O4 nanoparticles are uniformly dispersed and anchored on the reduced graphene oxide sheets to form a three-dimensional conductive network structure.
2. The nano-iron oxide composite material according to claim 1, characterized in that, The average particle size of the Fe3O4 nanoparticles is 3–5 nm.
3. The nano-iron oxide composite material according to claim 1, characterized in that, The oleic acid-modified Fe3O4 nanoparticles were prepared by a high-temperature thermal decomposition method. Specifically, high-purity Fe(acac)3 was selected as the iron source material, and Fe(acac)3 and oleic acid were mixed in a molar ratio of 1:4 to 6 under a nitrogen protective atmosphere. The mixture was placed in a high-temperature reactor and subjected to a thermal decomposition reaction at 300 to 350°C. After the reaction was completed, the reaction system was naturally cooled to room temperature, washed three times alternately with hexane and ethanol, and centrifuged to obtain oleic acid-modified Fe3O4 nanoparticles. The purity of the high-purity Fe(acac)3 was ≥99%.
4. The nano-iron oxide composite material according to claim 1, characterized in that, The reduced graphene oxide is prepared by reducing graphene oxide with ascorbic acid, wherein the mass ratio of ascorbic acid to GO is 5-6:
1.
5. A method for preparing the nano-iron oxide composite material according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Add oleic acid-modified Fe3O4 nanoparticles to a graphene oxide aqueous dispersion with a mass concentration of 1.8-2.2 mg / mL, and use an ultrasonic instrument with a power of 180-220W to continuously sonicate for 25-35 minutes to ensure that the Fe3O4 nanoparticles are uniformly dispersed in the liquid phase and fully contacted with the graphene oxide. (2) Add ascorbic acid slowly to the mixture, with the mass ratio of ascorbic acid to graphene oxide controlled at 5-6:1, and continue stirring. Transfer the mixture to a polytetrafluoroethylene hydrothermal reactor and react at 78-82℃ for 5.5-6.5h. During the reaction, ascorbic acid reduces graphene oxide to reduced graphene oxide and induces the formation of a chemical / physical composite structure between Fe3O4 nanoparticles and reduced graphene oxide. (3) After the reaction is complete, the product is washed three times with deionized water and anhydrous ethanol, centrifuged and then vacuum dried at 60°C for 12-16 hours to obtain Fe3O4@reduced graphene oxide composite material.
6. A sodium-ion battery negative electrode, characterized in that, The active material includes the nano-iron oxide composite material as described in any one of claims 1 to 4.
7. The sodium-ion battery negative electrode according to claim 6, characterized in that, The method for preparing the sodium-ion battery negative electrode includes: mixing Fe3O4@reduced graphene oxide composite material, PVDF binder and conductive carbon in a mass ratio of 7-9:1:1, adding NMP solvent to prepare a slurry, uniformly coating it on a copper foil, controlling the dry film thickness between 50 and 80 μm, and then vacuum drying the electrode sheet at 120°C for 12-16 hours before punching it into a Φ12 mm disc for use as the working electrode.
8. A sodium-ion battery, characterized in that, The battery includes the negative electrode as described in any one of claims 6 to 7, and further includes a sodium metal counter electrode, a separator, and an electrolyte containing NaPF6.
9. The sodium-ion battery according to claim 8, characterized in that, The electrolyte is a 1 mol / L NaPF6 solution, and the volume ratio of EC to DEC in the NaPF6 solution is 1:
1.
10. The sodium-ion battery according to claim 8, characterized in that, The anode has an initial specific capacity of ≥470mAh / g at a current density of 0.1A / g, and a capacity retention of ≥82% after 100 cycles.