Heteroatom-doped SP2-enriched hybrid composite carbon modified polyanion electrode material and preparation method and application thereof

Abstract

The invention relates to a heteroatom-doped SP2-enriched hybrid composite carbon modified polyanion electrode material and a preparation method and application thereof, and belongs to the technical field of sodium ion battery electrode materials, and the specific scheme is as follows: the heteroatom-doped SP2-enriched hybrid composite carbon modified polyanion electrode material comprises a polyanion compound and a long-range SP2 carbon material, the surface of the polyanionic compound is coated with a heteroatom-doped carbon layer rich in an SP2 hybrid structure; and the long-range SP2 carbon material constructs a long-range conductive carbon network between the polyanionic compounds coated with the carbon layer. A heteroatom doped SP2 carbon layer and a Mn-O bond form a strong coordination effect, heteroatoms with high electronegativity are coupled with a d orbit of Mn < 3 + > through an SP2 hybrid orbit, electrons are driven to be transferred from Mn atoms to the heteroatoms, the electron occupation asymmetry of Mn < 3 + > is reduced, and Jahn-Teller distortion is inhibited.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium ion battery electrode materials, and specifically relates to a heteroatom-doped SP-rich 2 Hybrid composite carbon modified polyanion electrode material and its preparation method and application. Background Art

[0002] As human demand for energy continues to increase and fossil energy is scarce, it is imperative to rationally develop and use traditional energy and increase the scale and proportion of renewable energy. Battery-based chemical energy storage has the advantages of not being restricted by the geographical environment and having a fast response speed. Among them, lithium-ion batteries are currently the fastest-growing and most widely used secondary batteries. However, as the scope of use continues to expand, the demand for lithium-ion batteries is also increasing, and the shortage of lithium resources has gradually become prominent.

[0003] Sodium-ion batteries have the same working principle as lithium-ion batteries, and have abundant sodium reserves and low cost, so they have attracted widespread attention. Among the positive electrode materials of sodium-ion batteries, polyanion materials have good safety and high output voltage due to their strong electronegativity, stable polyanion groups and open framework structure. They are considered to be highly promising positive electrode materials for sodium-ion batteries and are widely studied.

[0004] Among the many mixed polyanionic compounds, mixed phosphate materials have attracted extensive attention from scholars. The most representative one is the Na4M3(PO4)2P2O7 (M=Ni, Co, Mn, Fe) type compound. However, it is a one-dimensional ion transport structure with slow intrinsic transport kinetics, which limits its application in power batteries. Among them, the manganese-rich Na4M3(PO4)2P2O7 material has a low Mn content. 3+ During the charge and discharge process, Jahn-Teller distortion induces structural stress, which leads to the dissolution of manganese ions and aggravates capacity decay. The material's discharge capacity is poor at low temperature or high current density. Therefore, it is necessary to regulate the electronic structure of the Mn-O bond to fundamentally inhibit manganese dissolution. Summary of the Invention

[0005] Aiming at the problem that the manganese-rich mixed polyanion NFPP series materials have poor discharge capacity at low temperature or high current density due to the dissolution of manganese ions caused by Jahn-Teller distortion of manganese ions, the present invention provides a heteroatom-doped SP-rich 2 Hybrid composite carbon modified polyanion electrode materials and their preparation methods and applications. SP by heteroatom doping 2 The carbon layer forms a strong coordination with the Mn-O bond, and the highly electronegative heteroatoms form a strong coordination with the Mn-O bond. 2 Hybrid orbitals and Mn 3+The d-orbital coupling drives the electron transfer from Mn atoms to heteroatoms, reducing the 3+ electron occupancy asymmetry of Mn and suppressing the Jahn-Teller distortion.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A heteroatom-doped polyanion electrode material modified with rich SP 2 hybrid composite carbon, comprising a polyanion compound and a long-range SP 2 carbon material. The surface of the polyanion compound is coated with a heteroatom-doped carbon layer rich in SP 2 hybrid structure, and the characteristic parameter range of I D / I G in its Raman spectrum is 0.1 - 0.8. The heteroatom is one or a combination of several of N, P, O, B, S, Si, Br, Cl, F, and the molar ratio of the heteroatom source to the carbon source of the carbon layer is 0.1:1 - 10; the long-range SP 2 carbon material constructs a long-range conductive carbon network between the polyanion compounds coated with the carbon layer, and the characteristic parameter range of I D / I G in its Raman spectrum is 0.1 - 0.5.

[0008] The chemical formula of the polyanion compound is Na 4+λ Fe x Mn y M z (PO4)2(P2O7), where -0.5 ≤ λ ≤ 0.5, 2.5 ≤ x + y + z ≤ 3.5, 1.5 < x < 2, 0.5 < y < 1.5, 0 < z < a combination of at least three of transition metals Co, Ni, V, Cr, Ti, Mg, Ca, Cu, Zn, Zr, Mo, Nb, Sb, Y, Sc, lanthanide elements. The heteroatom forms a stable coordination structure with the Mn-O bond,

[0009] The thickness of the carbon layer is 0.5 - 5 nm.

[0010] The mass ratio of the polyanion compound is 89% - 99%, and the total mass ratio of the carbon layer and the long-range SP 2 carbon material is 0.5% - 10%. The characteristic parameter range of I 2 / I D / I G in the Raman spectrum of the reaction-rich SP

[0011] The carbon source of the carbon layer includes one or more of toluene, xylene, aniline, biphenyl, benzoic acid, 3-methylbenzoic acid, 2,4-dihydroxybenzoic acid, naphthalene-2,3-dicarboxylic acid, and conjugated microporous polymers containing a benzene ring structure; 2 The carbon material includes one or a combination of carbon nanotubes and their derivatives, graphene and their derivatives, carbon fibers and their derivatives, and graphite flakes and their derivatives.

[0012] A heteroatom-doped SP-rich 2 The preparation method of the hybrid composite carbon modified polyanion electrode material comprises the following steps: firstly reducing iron powder, chelating agent, heteroatom source and SP-rich 2 The carbon source of the hybrid structure is mixed and dissolved in deionized water for pre-reaction. The reaction temperature range is 0-100 ° C to form a heteroatom-Mn coordination structure. After the reaction is complete, the manganese source, transition metal source, and sodium source are added in sequence to form a precursor solution. Then, the long-range SP is dispersed with a phosphorus source. 2 The carbon material is added to the precursor solution, and the dispersant is added last. When all the reactants are mixed evenly, the temperature is raised to form a gel, and after vacuum drying at 100-120°C for 12-15h, the mixture is sintered at 450-650°C in a protective atmosphere for 6-10h at a heating rate of 5-10°C / min to obtain the heteroatom-doped SP-rich 2 The polyanion electrode material modified by hybrid composite carbon. The protective atmosphere is one of argon, hydrogen argon and nitrogen.

[0013] The chelating agent includes one or more of citric acid, ferric citrate, oxalic acid, and glucose; the manganese source is one or more of manganese acetate, manganese carbonate, manganese citrate, manganese oxalate, manganese nitrate, and manganese gluconate; the transition metal source is a combination of at least three of Co, Ni, V, Cr, Ti, Mg, Ca, Cu, Zn, Zr, Mo, Nb, Sb, Y, Sc, and lanthanide elements; the sodium source is one or more of sodium dihydrogen phosphate, sodium acetate, sodium carbonate, sodium pyrophosphate, sodium oxalate, and sodium dihydrogen citrate; the phosphorus source is one or more of sodium dihydrogen phosphate, ammonium dihydrogen phosphate, sodium pyrophosphate, diammonium hydrogen phosphate, and pyrophosphoric acid; and the dispersant is one of ethylene glycol, methanol, ethanol, and propanol.

[0014] A sodium ion battery, wherein the positive electrode sheet of the sodium ion battery comprises the heteroatom-doped SP-rich 2 Hybrid composite carbon modified polyanion electrode material or heteroatom doped SP-rich prepared by the preparation method according to any one of claims 6 to 8 2 Hybrid composite carbon modified polyanion electrode materials.

[0015] The preparation method of the positive electrode sheet is: doping the heteroatom-rich SP 2 The hybrid composite carbon-modified polyanion electrode material is continuously stirred with a conductive agent, a binder and a solvent for 8-12 hours to mix evenly to prepare an electrode slurry, and then the electrode slurry is evenly coated on the surface of the aluminum foil current collector with a thickness of 0.20 mm using a scraper, and vacuum dried at 100-110°C for 8-12 hours to obtain a positive electrode sheet for assembling a battery.

[0016] Preferably, the conductive agent is SuperP, the binder is PVDF, and the solvent is NMP.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention adopts sol-gel method to prepare a heteroatom-doped SP-rich 2 Hybrid composite carbon modified entropy-regulated polyanion electrode material. The core innovation of this invention is the SP doped with heteroatoms. 2 The hybrid carbon layer forms a stable coordination with the Mn-O bond on the surface of the polyanionic compound material, driving the electron transfer from the Mn atom to the highly electronegative heteroatom, reducing the Mn 3+ Jahn-Teller distortion, inhibiting the dissolution of manganese from the electronic structure level. 2 Carbon materials build long-range conductive carbon networks and form three-dimensional ion / electron transmission channels. By doping with multiple transition metal elements and adjusting the types and proportions of doping elements, the configuration entropy of the material can be effectively increased. By regulating the entropy, the crystal structure band gap of the material is changed, thereby improving its conductivity and structural stability. 4+λ Fe x Mn y M z (PO4)2(P2O7) electrode material as the positive electrode of sodium ion battery has good cycle stability and excellent rate and low temperature performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a structural diagram of the positive electrode material of Example 1 of the present invention;

[0020] Figure 2 is the XRD of the positive electrode material of Example 1 of the present invention;

[0021] Figure 3 is the Raman curve of the positive electrode material of Example 1 of the present invention;

[0022] Figure 4 is a charge and discharge curve diagram of the positive electrode material of Example 1 of the present invention;

[0023] Figure 51C cycle curves of Example 1 of the present invention and the comparative example materials;

[0024] Figure 6 This is a rate performance diagram of Example 1 of the present invention and the comparative example material;

[0025] Figure 7 This is a rate performance diagram of the positive electrode material of Example 1 of the present invention at -20°C. DETAILED DESCRIPTION

[0026] The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0027] Example 1:

[0028] A heteroatom-doped SP-rich 2 The preparation method of the hybrid composite carbon modified polyanion electrode material is carried out according to the following steps:

[0029] Step 1: Weigh 8.75mmol of reduced iron powder, 13.125mmol of anhydrous citric acid, 1.3mmol of melamine, and 5mg of naphthalene-2,3-dicarboxylic acid and add them to 45mL of deionized water. Stir at 80°C in a water bath for 12h until the iron powder is completely dissolved. Add 3.75mmol of manganese acetate and stir for 30min until completely dissolved. Add 0.625mmol of magnesium acetate, 0.625mmol of copper acetate, 0.625mmol of nickel acetate, and 0.625mmol of cobalt acetate and stir for 30min until completely dissolved. Add 20mmol of sodium acetate and stir for 30min until completely dissolved to form a precursor solution. Then, add 5mg of carbon nanotubes to 20mmol of ammonium dihydrogen phosphate and ultrasonically disperse for 1h until completely mixed. Add the dispersed solution to the precursor solution and stir for 30min. Add 8.75mmol of ethylene glycol and stir for 30min. Raise the water bath temperature to 90°C and stir for 2h to form a gel. The gel is vacuum dried at 100°C for 12h. The dried product was ground to obtain a precursor, which was then sintered in a tube furnace at 550 ° C for 8 h to obtain Na4Fe 1.75 Mn 0.75 (Mg,Cu,Ni,Co) 0.5 (PO4)2(P2O7) / CN cathode material, the heating rate during sintering is 5℃·min -1 , the atmosphere is 5% H2 / Ar mixed gas.

[0030] Step 2: The prepared cathode material, conductive agent (SuperP), and binder (PVDF) were weighed in a mass ratio of 8:1:1. A certain amount of NMP was added and stirred continuously for 12 hours. The resulting slurry was evenly spread on the surface of aluminum foil with a spatula to a thickness of 0.20 mm and vacuum-dried at 110°C for 12 hours to obtain the cathode electrode. A half-cell was then assembled with a sodium sheet for electrochemical performance testing. The electrolyte used was a 1M NaClO₄ solution in DEC / EC + 5% FEC, and the separator was a glass fiber membrane.

[0031] The structural diagram of the positive electrode material prepared in this embodiment is shown in FIG. Figure 1 As shown, the carbon coating layer is heteroatom-doped SP-rich 2 Hybrid structured carbon layer and the introduction of long-range SP 2 Carbon materials build long-range conductive carbon networks.

[0032] The XRD pattern of the positive electrode material prepared in this example is as follows: Figure 2 As shown, the characteristic peaks are obvious and sharp, and correspond well to the standard card (PDF#97-023-6316), without obvious impurity peaks.

[0033] The Raman curve of the positive electrode material prepared in this embodiment is as follows Figure 3 As shown in the curve, there are two groups of obvious diffraction peaks, corresponding to the D peak and G peak of carbon, respectively. The entropy regulation of Na4Fe 1.75 Mn 0.75 (Mg,Cu,Ni,Co) 0.5 I of (PO4)2(P2O7) / CN D / I G The value is 0.57, indicating that the material has a high degree of graphitization and good conductivity.

[0034] The charge and discharge curve of the positive electrode sheet prepared in this embodiment at 0.1C is as follows: Figure 4 shown.

[0035] The cycle performance of the positive electrode sheet prepared in this embodiment at 1C is as follows: Figure 5 After 500 cycles at 1C, it can still contribute 103.0 mAh g -1 The discharge specific capacity and capacity retention rate reach 96.10%.

[0036] The rate performance of the positive electrode sheet prepared in this embodiment is as follows Figure 6 As shown in the figure, it can still contribute a specific capacity of 87.3mAh / g at a high current density of 20C, and after 20C discharge, the material performance has no obvious change, and it can still cycle stably when further charged and discharged at 0.1C.

[0037] The rate performance of the positive electrode sheet prepared in this embodiment at -20°C is as follows: Figure 7 As shown, it can still contribute a specific capacity of 51.2 mAh / g at a high current density of 20C.

[0038] After cycling, the battery was disassembled to remove the positive electrode sheet, which was then cleaned with propylene carbonate (PC) to remove any residual separator and electrolyte. The positive electrode sheet was then immersed in a 5% HNO3 solution and ultrasonically treated for 1 hour. The solution was then subjected to ICP testing to determine the amount of manganese released. The results are shown in Table 1.

[0039] Comparative Example 1:

[0040] Step 1: Weigh 8.75mmol of reduced iron powder, 13.125mmol of anhydrous citric acid, and 5mg of naphthalene-2,3-dicarboxylic acid and add them to 45mL of deionized water. Stir at 80℃ in a water bath for 12h until the iron powder is completely dissolved. Add 3.75mmol of manganese acetate and stir for 30min until completely dissolved. Add 0.625mmol of magnesium acetate, 0.625mmol of copper acetate, 0.625mmol of nickel acetate, and 0.625mmol of cobalt acetate and stir for 30min until completely dissolved. Add 20mmol of sodium acetate and stir for 30min until completely dissolved to form a precursor solution. Then, add 5mg of carbon nanotubes to 20mmol of ammonium dihydrogen phosphate and ultrasonically disperse for 1h until completely mixed. Add the dispersed solution to the precursor solution and stir for 30min. Add 8.75mmol of ethylene glycol and stir for 30min. Raise the water bath temperature to 90℃ and stir for 2h to form a gel. Dry the gel at 100℃ in vacuum for 12h. The dried product was ground to obtain a precursor, which was then sintered in a tube furnace at 550 ° C for 8 h to obtain Na4Fe 1.75 Mn 0.75 (Mg,Cu,Ni,Co) 0.5 (PO4)2(P2O7) / C cathode material, the heating rate during sintering is 5℃·min -1 , the atmosphere is 5% H2 / Ar mixed gas.

[0041] Step 2: Same as step 2 of Example 1.

[0042] The cycle performance of the positive electrode prepared in Comparative Example 1 at 1C is as follows: Figure 5 After 500 cycles at 1C, the battery capacity was 83.6 mAh g -1 The discharge specific capacity and capacity retention rate reached 84.04%.

[0043] The rate performance of the positive electrode prepared in Comparative Example 1 is as follows: Figure 6 As shown, the discharge specific capacity is 79.2 mAh / g at a current density of 20C.

[0044] After cycling, the battery was disassembled to remove the positive electrode sheet, which was then cleaned with propylene carbonate (PC) to remove any residual separator and electrolyte. The positive electrode sheet was then immersed in a 5% HNO3 solution and ultrasonically treated for 1 hour. The solution was then subjected to ICP testing to determine the amount of manganese released. The results are shown in Table 1.

[0045] Comparative Example 2:

[0046] Step 1: Weigh 8.75mmol of reduced iron powder and 13.125mmol of anhydrous citric acid and add them to 45mL of deionized water. Stir in a water bath at 80℃ for 12h until the iron powder is completely dissolved. Add 3.75mmol of manganese acetate and stir for 30min until completely dissolved. Add 0.625mmol of magnesium acetate, 0.625mmol of copper acetate, 0.625mmol of nickel acetate, and 0.625mmol of cobalt acetate and stir for 30min until completely dissolved. Add 20mmol of sodium acetate and stir for 30min until completely dissolved to form a precursor solution. Add 20mmol of ammonium dihydrogen phosphate and stir for 30min until completely mixed. Then add 8.75mmol of ethylene glycol and stir for 30min. Raise the water bath temperature to 90℃ and stir for 2h to form a gel. Dry the gel at 100℃ in vacuum for 12h. Grind the dried product to obtain a precursor. Sinter the precursor in a tube furnace at 550℃ for 8h to finally obtain Na4Fe 1.75 Mn 0.75 (Mg,Cu,Ni,Co) 0.5 (PO4)2(P2O7) cathode material, the heating rate during sintering is 5℃·min -1 , the atmosphere is 5% H2 / Ar mixed gas.

[0047] Step 2: Same as step 2 of Example 1.

[0048] The cycle performance of the positive electrode prepared in Comparative Example 2 at 1C is as follows: Figure 5 After 500 cycles at 1C, the capacity is 76.8 mAh g -1 The discharge specific capacity and capacity retention rate reach 77.35%.

[0049] The rate performance of the positive electrode prepared in Comparative Example 2 is as follows: Figure 6 As shown, the discharge specific capacity is 69.3 mAh / g at a current density of 20C.

[0050] After cycling, the battery was disassembled to remove the positive electrode sheet, which was then cleaned with propylene carbonate (PC) to remove any residual separator and electrolyte. The positive electrode sheet was then immersed in a 5% HNO3 solution and ultrasonically treated for 1 hour. The solution was then subjected to ICP testing to determine the amount of manganese released. The results are shown in Table 1.

[0051] Comparative Example 3:

[0052] Step 1: Weigh 7.5mmol of reduced iron powder and 11.25mmol of anhydrous citric acid and add them to 45mL of deionized water. Stir in a water bath at 80℃ for 12h until the iron powder is completely dissolved. Add 7.5mmol of manganese acetate and stir for 30min until it is completely dissolved. Add 20mmol of sodium acetate and stir for 30min until it is completely dissolved to form a precursor solution. Then add 20mmol of ammonium dihydrogen phosphate and stir for 30min until it is completely dissolved. Add 7.5mmol of ethylene glycol and stir for 30min. Raise the water bath temperature to 90℃ and stir for 2h to form a gel. Dry the gel at 100℃ in vacuum for 12h. Grind the dried product to obtain a precursor. Sinter the precursor in a tube furnace at 550℃ for 8h to finally obtain Na4Fe 1.5 Mn 1.5 (PO4)2(P2O7) cathode material, the heating rate during sintering is 5℃·min -1 , the atmosphere is 5% H2 / Ar mixed gas.

[0053] Step 2: Same as step 2 of Example 1.

[0054] The cycle performance of the positive electrode prepared in Comparative Example 3 at 1C is as follows: Figure 5 After 500 cycles at 1C, the battery capacity is 37.5 mAh g -1 The discharge specific capacity and capacity retention rate reached 49.07%.

[0055] The rate performance of the positive electrode prepared in Comparative Example 3 is as follows: Figure 6 As shown, the discharge capacity is 46.9 mAh / g at a current density of 20C.

[0056] After cycling, the battery was disassembled to remove the positive electrode sheet, which was then cleaned with propylene carbonate (PC) to remove any residual separator and electrolyte. The positive electrode sheet was then immersed in a 5% HNO3 solution and ultrasonically treated for 1 hour. The solution was then subjected to ICP testing to determine the amount of manganese released. The results are shown in Table 1.

[0057] Table 1

[0058]

[0059]

[0060] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A heteroatom-doped SP-rich 2 Hybrid composite carbon modified polyanion electrode material, characterized by: Including polyanionic compounds and long-range SP 2 Carbon material, the surface of the polyanion compound is coated with heteroatom-doped SP-rich 2 The carbon layer of the hybrid structure, the heteroatom is one or a combination of N, P, O, B, S, Si, Br, Cl, F, wherein the molar ratio of the heteroatom source to the carbon source of the carbon layer is 0.1:1-10; the long-range SP 2 The carbon material constructs a long-range conductive carbon network between the polyanionic compounds covering the carbon layer.

2. A heteroatom-doped SP-rich substrate according to claim 1 2 Hybrid composite carbon modified polyanion electrode material, characterized by: The chemical formula of the polyanionic compound is Na 4+λ Fe x Mn y M z (PO4)2(P2O7), where -0.5 ≤ λ ≤ 0.5, 2.5 ≤ x + y + z ≤ 3.5, 1.5 < x < 2, 0.5 < y < 1.5, 0 < z < 0.5, and M is a combination of at least three of the transition metals Co, Ni, V, Cr, Ti, Mg, Ca, Cu, Zn, Zr, Mo, Nb, Sb, Y, Sc, and lanthanide elements.

3. The heteroatom-doped SP-rich nanoparticle according to claim 1 2 Hybrid composite carbon modified polyanion electrode material, characterized by: The thickness of the carbon layer is 0.5-5 nm.

4. The heteroatom-doped SP-rich nanoparticle according to claim 1 2 Hybrid composite carbon modified polyanion electrode material, characterized by: The mass proportion of the polyanion compound is 89%-99%, and the carbon layer and the long-range SP 2 The carbon material accounts for 0.5%-10% of the total mass.

5. The heteroatom-doped SP-rich nanoparticle according to claim 1 2 Hybrid composite carbon modified polyanion electrode material, characterized by: The carbon source of the carbon layer includes toluene, xylene, aniline, biphenyl, benzoic acid, 3-methylbenzoic acid, 2,4-dihydroxybenzoic acid, naphthalene-2,3-dicarboxylic acid, a conjugated microporous polymer or a combination thereof; the long-range SP 2 The carbon material includes one or a combination of carbon nanotubes and their derivatives, graphene and their derivatives, carbon fibers and their derivatives, and graphite flakes and their derivatives.

6. A heteroatom-doped SP-rich material according to any one of claims 1 to 5 2 The preparation method of hybrid composite carbon modified polyanion electrode material is characterized in that: The following steps are involved: First, reduced iron powder, chelating agent, heteroatom source and SP-rich 2 The carbon source of the hybrid structure is mixed and dissolved in deionized water for pre-reaction. The reaction temperature range is 0-100 ° C to form a heteroatom-Mn coordination structure. After the reaction is complete, the manganese source, transition metal source, and sodium source are added in sequence to form a precursor solution. Then, the long-range SP is dispersed with a phosphorus source. 2 The carbon material is added to the precursor solution, and finally the dispersant is added. When all the reactants are mixed evenly, the temperature is raised to form a gel, and after drying, it is sintered at 450-650 ° C in a protective atmosphere to obtain the heteroatom-doped SP-rich 2 Hybrid composite carbon modified polyanion electrode materials.

7. The heteroatom-doped SP-rich nanoparticle according to claim 6 2 The preparation method of the hybrid composite carbon modified polyanion electrode material is characterized by: The chelating agent includes one or more of citric acid, ferric citrate, oxalic acid, and glucose; the manganese source is one or more of manganese acetate, manganese carbonate, manganese citrate, manganese oxalate, manganese nitrate, and manganese gluconate; the transition metal source is a combination of at least three of Co, Ni, V, Cr, Ti, Mg, Ca, Cu, Zn, Zr, Mo, Nb, Sb, Y, Sc, and lanthanide elements; the sodium source is one or more of sodium dihydrogen phosphate, sodium acetate, sodium carbonate, sodium pyrophosphate, sodium oxalate, and sodium dihydrogen citrate; the phosphorus source is one or more of sodium dihydrogen phosphate, ammonium dihydrogen phosphate, sodium pyrophosphate, diammonium hydrogen phosphate, and pyrophosphoric acid; and the dispersant is one of ethylene glycol, methanol, ethanol, and propanol.

8. The heteroatom-doped SP-rich nanoparticle according to claim 6 2 The preparation method of the hybrid composite carbon modified polyanion electrode material is characterized by: The drying temperature is 100-120° C., and the drying time is 12-15 hours. The protective atmosphere is one of argon, hydrogen argon, and nitrogen. The sintering time is 6-10 hours, and the heating rate is 5-10° C. / min.

9. A sodium ion battery, characterized in that: The positive electrode sheet of the sodium ion battery comprises the heteroatom-doped SP-rich 2 Hybrid composite carbon modified polyanion electrode material or heteroatom doped SP-rich prepared by the preparation method according to any one of claims 6 to 8 2 Hybrid composite carbon modified polyanion electrode materials.

10. The sodium ion battery according to claim 9, characterized in that: The preparation method of the positive electrode sheet is: doping the heteroatom-rich SP 2 The hybrid composite carbon modified polyanion electrode material is evenly mixed with a conductive agent, a binder and a solvent to prepare an electrode slurry, and then the electrode slurry is evenly coated on a current collector and dried to obtain a positive electrode sheet.

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