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CN-122025879-A - Sodium supplementing coating based on spiral iron-carbon-based composite material and preparation method thereof

CN122025879ACN 122025879 ACN122025879 ACN 122025879ACN-122025879-A

Abstract

The invention relates to the technical field of sodium battery materials, in particular to a sodium supplementing coating based on a spiral iron-carbon-based composite material and a preparation method thereof, wherein a spiral polypyrrole template is synthesized through a chiral template method, fe 3 C@CNS spiral carbon composite material rich in Fe 3 C nanocrystalline and iron single atom sites is prepared through iron loading, vulcanization and high-temperature pyrolysis, sodium oxalate is highly dispersed and loaded on the surface and in a pore canal of the spiral carbon composite material through a recrystallization method to prepare a Na 2 C 2 O 4 @Fe 3 C@CNS composite material, and finally, slurry is prepared through mixing with a conductive agent and a binder and is coated on the surface of an electrode to form a functional sodium supplementing coating. The sodium supplementing coating based on the spiral iron-carbon-based composite material and the preparation method thereof solve the problems of irreversible sodium loss at the first week and poor interface stability of the existing sodium ion battery, realize high-efficiency pre-sodification and interface cooperative regulation and control, and improve the comprehensive performance of the battery.

Inventors

  • MA YUE
  • LI CHUNWEI
  • LIU TING

Assignees

  • 西北工业大学

Dates

Publication Date
20260512
Application Date
20260413

Claims (10)

  1. 1. The preparation method of the sodium supplementing coating based on the spiral iron-carbon-based composite material is characterized by comprising the following steps of: S1, preparing a chiral surfactant, namely dissolving glutamic acid in an alkaline solution in an ice bath, adding stearoyl chloride for reaction, acidifying and separating out, washing and drying in vacuum to obtain the chiral surfactant; S2, synthesizing a spiral polypyrrole template, namely polymerizing pyrrole monomers at a low temperature by taking the chiral surfactant of S1 as a template and ammonium persulfate as an oxidant to prepare a polypyrrole template T-PPy with a spiral morphology; s3, preparing an iron load and vulcanization precursor, namely dispersing the polypyrrole template T-PPy of S2 in methanol by ultrasonic, adding an iron salt solution, carrying out ultrasonic load, centrifugally drying to obtain Fe@T-PPy, and carrying out reflux vulcanization on the Fe@T-PPy and thiophene in an inert atmosphere to obtain an Fe-S@T-PPy precursor; s4, preparing a spiral carbon composite material, namely pyrolyzing and carbonizing the Fe-S@T-PPy precursor obtained in the step S3 in an inert atmosphere to obtain the Fe 3 C@CNS spiral carbon composite material; S5, sodium oxalate load and coating preparation, namely dispersing the Fe 3 C@CNS spiral carbon composite material of S4 in a sodium oxalate saturated solution, adding ethanol to induce sodium oxalate to recrystallize and load to prepare a Na 2 C 2 O 4 @Fe 3 C@CNS composite material, mixing the Na 2 C 2 O 4 @Fe 3 C@CNS composite material with a conductive agent and a binder to prepare slurry, coating the slurry on the surface of an electrode, and drying to form the sodium supplementing coating.
  2. 2. The preparation method of the sodium supplementing coating based on the spiral iron-carbon-based composite material is characterized in that glutamic acid in S1 comprises one or more of L-glutamic acid, D-glutamic acid and DL-glutamic acid, the molar charge ratio of glutamic acid to stearoyl chloride is 1:1-1.2, and the vacuum drying temperature is 60-80 ℃.
  3. 3. The preparation method of the sodium supplementing coating based on the spiral iron-carbon-based composite material, which is disclosed in claim 1, is characterized in that in S1, the alkaline solution is sodium hydroxide aqueous solution, the acid used for acidification is hydrochloric acid, and the vacuum drying temperature is 60-80 ℃.
  4. 4. The preparation method of the sodium supplementing coating based on the spiral iron-carbon-based composite material, which is characterized in that in S2, pyrrole monomers are N-substituted pyrrole, wherein the N-substituted pyrrole comprises one of N-methyl pyrrole and N-ethyl pyrrole, the mass ratio of chiral surfactant to pyrrole monomers is 1:100-150, the polymerization reaction temperature is 0-5 ℃, and the reaction time is 4-6 hours.
  5. 5. The preparation method of the sodium supplementing coating based on the spiral iron-carbon-based composite material, which is characterized in that in S3, the ferric salt comprises one of ferric nitrate nonahydrate, ferric chloride and ferric sulfate, the mass ratio of the ferric salt to the polypyrrole template T-PPy is 1:2-4, the vulcanization reaction temperature is 60-70 ℃, and the reaction time is 10-12 hours.
  6. 6. The preparation method of the sodium supplementing coating based on the spiral iron-carbon-based composite material, which is disclosed in claim 1, is characterized in that in S4, pyrolytic carbon is heated to 800-900 ℃ at a heating rate of 3-5 ℃ per minute, and the temperature is kept for 1-2 hours at a constant temperature.
  7. 7. The method for preparing the sodium supplementing coating based on the spiral iron-carbon-based composite material, which is disclosed in claim 1, is characterized in that in S5, the mass load ratio of Fe 3 C@CNS spiral carbon composite material to sodium oxalate is 1:0.5-2, and the mass ratio of Na 2 C 2 O 4 @Fe 3 C@CNS composite material to conductive agent and binder is (70-80): 10-20): 5-10.
  8. 8. The method for preparing the sodium supplementing coating based on the spiral iron-carbon-based composite material, as claimed in claim 1, wherein in the step S5, the ethanol is added dropwise at a flow rate of 0.5-2mL/min under stirring in the recrystallization process.
  9. 9. The preparation method of the sodium supplementing coating based on the spiral iron-carbon-based composite material, which is disclosed in claim 1, is characterized in that in S5, the coating thickness is 5-15 μm, and the drying is carried out under vacuum drying at 60-120 ℃ for 6-12 hours.
  10. 10. The sodium supplementing coating based on the spiral iron-carbon-based composite material is characterized in that the sodium supplementing coating based on the spiral iron-carbon-based composite material is prepared by the preparation method of the sodium supplementing coating based on the spiral iron-carbon-based composite material as claimed in any one of claims 1-9, sodium oxalate in the sodium supplementing coating is uniformly loaded on the surface and in a pore canal of the Fe 3 C@CNS spiral carbon composite material, and Fe 3 C nanocrystalline and sodium oxalate form a heterogeneous interface.

Description

Sodium supplementing coating based on spiral iron-carbon-based composite material and preparation method thereof Technical Field The invention relates to the technical field of sodium battery materials, in particular to a sodium supplementing coating based on a spiral iron-carbon-based composite material and a preparation method thereof. Background Lithium Ion Batteries (LIBs) have become the dominant energy storage technology in the portable and automotive fields by virtue of their excellent performance. However, lithium resources are scarce and geographically distributed, and it is difficult to meet the explosive demands of the global energy storage market for a long period of time. In this context, sodium Ion Batteries (SIBs) are a very potential alternative to lithium ion batteries due to the abundance of sodium resources and the significant cost effectiveness. However, sodium ion batteries have problems in practical applications that severely limit their energy density and cycling stability (1) the initial cycle irreversible sodium depletion problem is that during the initial cycling of sodium ion batteries, the negative electrode (especially the Hard Carbon (HC) negative electrode in mainstream applications) will irreversibly consume sodium ions released from the positive electrode, resulting in a lower Initial Coulombic Efficiency (ICE) (the ICE of hard carbon negative electrodes is typically only 70% -90%). This phenomenon directly causes a large loss of active sodium in the positive electrode, so that the full battery cannot fully release the inherent capacity of the positive electrode material, and finally the energy density is greatly reduced, which becomes a key obstacle for restricting the practical application of the sodium ion battery. (2) The performance degradation problem in long-term circulation is that the sodium ion battery is subjected to multiple factors to cause continuous degradation of performance after long-term circulation, on one hand, active elements (such as vanadium) in positive electrode materials (such as NVP) can be dissolved (in the form of V 3+、V4+) to cause collapse of a positive electrode structure, dissolved vanadium ions can migrate to the surface of a negative electrode to damage the integrity of a solid electrolyte interface film (SEI) and catalyze sodium dendrite growth to cause cross contamination of the positive electrode and the negative electrode, on the other hand, the migrated vanadium ions can also cause continuous side reaction inside the battery through redox shuttle effect, and in addition, the problems of parasitic irreversible reaction between active sodium exposed on the surface of the negative electrode and an electrolyte organic solvent, incomplete stripping of sodium ions and the like can further deplete active sodium ion stock in the positive electrode lattice to cause ion transmission blockage and deterioration of battery circulation stability. Accordingly, there is a need to provide a viable solution that maximizes the increase in the practical volumetric and gravimetric energy density of sodium ion batteries. Disclosure of Invention The invention aims to provide a sodium supplementing coating based on a spiral iron-carbon-based composite material and a preparation method thereof, solve the problems of irreversible sodium loss at the first week and poor interface stability of the existing sodium ion battery, realize high-efficiency pre-sodification and interface cooperative regulation and control, and improve the comprehensive performance of the battery. In order to achieve the above purpose, the invention provides a preparation method of a sodium supplementing coating based on a spiral iron-carbon-based composite material, which comprises the following steps: S1, preparing a chiral surfactant, namely dissolving glutamic acid in an alkaline solution in an ice bath, adding stearoyl chloride for reaction, acidifying and separating out, washing and drying in vacuum to obtain the chiral surfactant; S2, synthesizing a spiral polypyrrole template, namely polymerizing pyrrole monomers at a low temperature by taking the chiral surfactant of S1 as a template and ammonium persulfate as an oxidant to prepare a polypyrrole template T-PPy with a spiral morphology; s3, preparing an iron load and vulcanization precursor, namely dispersing the polypyrrole template T-PPy of S2 in methanol by ultrasonic, adding an iron salt solution, carrying out ultrasonic load, centrifugally drying to obtain Fe@T-PPy, and carrying out reflux vulcanization on the Fe@T-PPy and thiophene in an inert atmosphere to obtain an Fe-S@T-PPy precursor; s4, preparing a spiral carbon composite material, namely pyrolyzing and carbonizing the Fe-S@T-PPy precursor obtained in the step S3 in an inert atmosphere to obtain the Fe 3 C@CNS spiral carbon composite material; S5, sodium oxalate load and coating preparation, namely dispersing the Fe 3 C@CNS spiral carbon composite material of S4 in a s