1079 results about "Pyrophosphoric acid" patented technology

The invention provides a sodium ferric pyrophosphate positive electrode material cooperatively doped with anions and cations, a preparation method of the sodium ferric pyrophosphate positive electrode material and a sodium ion battery, and relates to the field of sodium ion batteries. The anion and cation synergistically doped ferric sodium phosphate pyrophosphate positive electrode material comprises an inner core and a coating layer covering the outer surface of the inner core, the inner core comprises ferric sodium phosphate pyrophosphate, the coating layer comprises carbon, the chemical formula of the ferric sodium phosphate pyrophosphate is Na4-2yFe2.91-xQx (PO4) 2-yP2O7Fy, x is more than 0 and less than or equal to 0.3, and y is more than or equal to 0.03 and less than or equal to 0.08; q comprises at least one of Sn, Ni, Cu, Mg and Mn. The introduced Q positive ions and F negative ions can keep the crystal structure of the body material stable, and the positive ions and the negative ions have a synergistic effect, so that the band gap of the positive electrode material is reduced, the state density near the Fermi level of the positive electrode material is increased, the conductivity of the positive electrode material is enhanced, the specific capacity of the positive electrode material is improved, and the rate and the cycle performance are promoted.

The present invention relates to a sodium-ion battery material, and specifically relates to a sodium ferric phosphate pyrophosphate composite material, and a preparation process, evaluation method and process optimization method therefor and the use thereof. The sodium ferric phosphate pyrophosphate composite material has a spinel-type NaFePO4 phase; and in an XRD diffraction pattern obtained by subjecting the sodium ferric phosphate pyrophosphate composite material to XRD diffraction using CuKα radiation, there are a characteristic diffraction peak T of sodium ferric phosphate pyrophosphate and a characteristic diffraction peak O of spinel-type NaFePO4 at 2θ of 33.6±0.2° and 32.8±0.2°, respectively, the peak intensities thereof are respectively IT and IO, and the diffraction peak intensity ratio Ir is equal to IT / IO, wherein 6.19≤Ir≤13.

The invention provides a doped and coated composite sodium battery positive electrode material as well as a preparation method and application thereof. The doped and coated composite sodium battery positive electrode material comprises an inner core and a coating layer on the surface of the inner core, the chemical general formula of the inner core is NabNixFeyMnzMjO2, x + y + z + j = 1, 0.2 < = x < = 0.6, 0.2 < = y < = 0.5, 0.2 < = z < = 0.5, 0 < j < = 0.2, 0.8 < = b < = 1.2; the coating layer comprises a ferric sodium pyrophosphate material; raw materials for preparing the doped and coated composite sodium battery positive electrode material comprise an inner core, a phosphoric acid ferric sodium pyrophosphate precursor material and a sodium source. The metal elements are doped in the inner core, and the surface is coated with the ferric sodium pyrophosphate material with relatively high stability, so that the inner core can be prevented from being in direct contact with an electrolyte, and the cycle performance of the sodium battery positive electrode material is improved.

The invention relates to a preparation method and application of a manganese ion doped modified ferric sodium pyrophosphate positive electrode material, and belongs to the technical field of sodium ion battery positive electrodes. The preparation method comprises the following steps: adding a sodium source, a phosphorus source and a carbon source into ethanol, uniformly mixing to form a mixed solution, sequentially adding an iron source and a manganese source into the mixed solution, uniformly mixing to form slurry, and drying the slurry to obtain precursor powder; calcining in a protective atmosphere to obtain a manganese-doped carbon-coated ferric pyrophosphate sodium material; the calcining conditions are as follows: heating to the temperature of 300-350 DEG C at the heating rate of 2-3 DEG C / min, carrying out first-stage constant-temperature calcination for 2-3 hours, heating to the temperature of 500-550 DEG C at the heating rate of 5-8 DEG C / min, and carrying out second-stage constant-temperature calcination for 10-12 hours. By doping the manganese ions, the electronic conductivity and the ion diffusivity of the ferric sodium phosphate pyrophosphate composite material are improved, so that the discharge capacity of the ferric sodium phosphate pyrophosphate composite material at high rate is improved, and the battery has relatively high cycle stability.

The invention relates to an anti-static PP composite material and a preparation method thereof, and belongs to the technical field of high polymer materials. The antistatic PP composite material is prepared from the following components in parts by weight: 60 to 80 parts of PP resin, 10 to 20 parts of glass fiber, 0.1 to 0.5 part of a lubricant, 0.3 to 2 parts of a modified antistatic agent, 0.5 to 1.5 parts of a modified flame retardant and 0.2 to 0.8 part of an antioxidant, in the modified antistatic agent, an alkanolamide bond intermediate forms a conductive film, so that the resistivity is reduced, static dissipation is promoted, the material is endowed with lubricity, and the generation of static electricity is reduced; in addition, maleic anhydride forms a conductive layer and cooperates with quaternary ammonium salt to enhance hydrophilicity and accelerate charge transfer; a piperazine pyrophosphate derivative in the modified flame retardant and a phosphorus-nitrogen flame retardant cooperate to construct an expanded carbon layer to isolate a fire source and oxygen, so that the service life is prolonged; the anti-static PP composite material prepared by the invention not only has a good anti-static effect, but also has excellent flame-retardant and tensile properties.

The invention belongs to the field of sodium ion batteries, and particularly discloses a positive electrode material and a preparation method and application thereof. The positive electrode material is carbon nitride coated fluorine-doped pyrophosphate sodium manganese iron phosphate, the chemical formula of the positive electrode material is NaaFe3-bMnb (PO4-x) 2F4xP2O7 / C3N4, a is larger than or equal to 3.95 and smaller than or equal to 4.1, b is larger than or equal to 0.3 and smaller than or equal to 2.4, and x is larger than or equal to 0.005 and smaller than or equal to 0.05. The sodium ferromanganese pyrophosphate is subjected to fluorine doping and carbon nitride coating, so that the electronic conductivity and the structural stability of the sodium ferromanganese pyrophosphate can be improved, the capacity of the sodium ferromanganese pyrophosphate can be well exerted, and the capacity and the voltage platform of the sodium-ion battery are improved.

The invention relates to the technical field of flame-retardant polypropylene composite materials, in particular to a flame-retardant reinforced polypropylene composite material containing flame-retardant modified glass fibers and a preparation method of the flame-retardant reinforced polypropylene composite material. The flame-retardant modified glass fiber-containing flame-retardant reinforced polypropylene composite material is prepared from the following raw materials: 30 to 60 parts of polypropylene, 5 to 60 parts of flame-retardant modified glass fiber, 5 to 20 parts of piperazine pyrophosphate, 5 to 20 parts of melamine polyphosphate, 0.5 to 5 parts of flame-retardant synergist, 1 to 6 parts of maleic anhydride ester-grafted polypropylene, 0.5 to 3 parts of coupling agent, 0.3 to 3 parts of lubricant and 0.2 to 0.5 part of antioxidant. The flame-retardant modified glass fibers are glass fibers subjected to surface modification by using a focused piperazine phosphate-melamine polyphosphate random copolymer. According to the technical scheme, the problem that the mechanical property and flame retardant property of glass fiber reinforced polypropylene in the prior art are difficult to optimize at the same time can be solved, and the glass fiber reinforced polypropylene has ideal popularization and application prospects.

The invention discloses a modified carbon-coated sodium manganese ferric phosphate pyrophosphate / sodium ferric phosphate pyrophosphate positive electrode material as well as a preparation method and application thereof, and relates to the technical field of new energy materials. The preparation method comprises the following steps: preparing MnFe-MOF from a manganese source, a first iron source and a first organic ligand under a hydrothermal reaction; a second iron source, the MnFe-MOF and a second organic ligand are subjected to a hydrothermal reaction, and MnFe-MOF / Fe-MOF is obtained; uniformly mixing with a sodium source and a phosphorus source, and sintering to obtain a positive electrode material; and carrying out high-temperature gas-phase etching treatment to obtain the fluorine-doped carbon-coated modified sodium manganese ferric phosphate pyrophosphate / sodium ferric phosphate pyrophosphate positive electrode material. The material disclosed by the invention has a coating modified structure, so that an interface side reaction caused by direct contact between sodium ferromanganese phosphate and an electrolyte can be effectively avoided, a manganese dissolution phenomenon is reduced, and the structural stability of the material is improved; and meanwhile, the material has high conductivity, excellent structural stability, excellent long cycle life and excellent rate capability.

The invention belongs to the technical field of new energy materials, and particularly relates to a low-sulfur metal cation doped ammonium manganese ferric phosphate precursor, carbon-coated modified sodium manganese ferric pyrophosphate and a preparation method and application thereof. According to the invention, the low-sulfur metal cation doped ammonium manganese ferric phosphate precursor is successfully prepared. A proper amount of phosphoric acid source is added into the prepared metal cation doped ammonium manganese ferric phosphate precursor for treatment, so that the sulfur content of the precursor is remarkably reduced, and the molar ratio of manganese, iron, doped elements and phosphorus elements is regulated and controlled to be slightly smaller than 1. The atomic-scale distribution of elements in the precursor is realized, the tap density is also improved, and the subsequent preparation of a high-performance carbon-coated modified manganese ferric sodium phosphate pyrophosphate material is facilitated. The sodium ion battery constructed based on the material has excellent charge-discharge capacity, capacity retention ratio and cycling stability. In addition, the preparation method of the precursor is simple and convenient to operate and easy to control, and has the advantage of wide application.

The invention discloses a method for preparing a composite iron-based polyanion positive electrode material. The structural formula of the positive electrode material is represented as Na4Fe3 (PO4) 2 (P2O7) (at) Camp, mXenes are sodium ferric pyrophosphate compositely coated by an MXenes material and a carbonaceous precursor, and the preparation method comprises the following steps: weighing a sodium source, a ferrous source, a phosphorus source and a carbon source according to a stoichiometric ratio, uniformly mixing, grinding, spray-drying and sintering at high temperature to obtain the composite iron-based polyanion positive electrode material, and the carbon source comprises iron-nickel doped polyethylene glycol. The composite iron-based polyanion positive electrode material provided by the invention is remarkably improved in the aspects of energy density, rate capability and cycle life, and the preparation process is simple to operate, reliable in flow, quick in preparation process and easy for industrial production, so that an ideal scheme is provided for commercialized sodium ion battery positive electrode materials.

The invention relates to the technical field of sodium ion battery positive electrode materials, in particular to a carbon-coated sodium ferric phosphate pyrophosphate positive electrode material and a preparation method and application thereof.The preparation method includes the steps that carbon nanotubes and an organic carbon source serve as carbon sources to prepare two kinds of sodium ferric phosphate pyrophosphate particles, and the two kinds of particles are mixed in proportion and then sintered to obtain the carbon-coated sodium ferric phosphate pyrophosphate positive electrode material. In the carbon layer coated on the surface of the material, the carbon nanotubes and the organic carbon source exert respective conductive advantages to form a strong conductive network, so that the conductivity of the material is improved, and the overall structural rigidity of the material is enhanced.

The invention discloses a vanadium-doped modified ferric sodium pyrophosphate material based on spray drying as well as a preparation method and application of the vanadium-doped modified ferric sodium pyrophosphate material. The material has a spherical porous morphology, and the particle size is 1-10 microns; the chemical formula is Na (4-x) Fe (3-x) Vx (PO4) 2P2O7, wherein x is more than 0 and less than or equal to 0.1. The material is prepared by adopting a spray drying method, and atomic-scale mixing of vanadium and iron is ensured through a uniform and stable complexing ion solution; and the formation of porous spherical morphology is promoted through the volatilization of the acidic base solution in the rapid drying process. A spray drying method and a trace vanadium doping technology are combined, so that more active sodium sites in the ferric sodium phosphate pyrophosphate positive electrode material can be activated, the reversible de-intercalation sodium capacity can be improved, sodium ion diffusion can be promoted, the polarization voltage can be reduced, and the cycling stability of the material can be improved.

The invention provides a sodium ferric phosphate pyrophosphate positive electrode material and a preparation method thereof, and a sodium ion battery, the molecular formula of the sodium ferric phosphate pyrophosphate positive electrode material is Na4Fe3 (PO4) 2P2O7 / D1D2, D1 is a first conductive agent, the first conductive agent is a metal oxide, the second conductive agent is phosphate, D2 is a second conductive agent, and D1D2 is a metal oxide. And the molar ratio of the sodium element to the iron element to the phosphorus element to the first conductive agent to the second conductive agent in the ferric sodium phosphate pyrophosphate positive electrode material is (4.0 to 4.1) to (2.8 to 3.0) to (3.0 to 3.1) to (0.001 to 0.0.005) to (0.05 to 0.10). According to the embodiment of the invention, the first conductive agent increases the lattice volume, so that conduction channels of Na < + > and doped ions are increased, and higher electronic conductivity is achieved; and the phosphate of the second conductive agent forms coating points on the surface layers of the sodium iron phosphate particles, so that the interfacial effect in the electrochemical reaction process of the sodium iron phosphate pyrophosphate positive electrode material is slowed down, the electrochemical performance of the sodium iron phosphate pyrophosphate positive electrode material is further improved, and the electrochemical specific capacity is improved.

The invention discloses a ferric sodium pyrophosphate positive electrode material, a preparation method thereof and a battery, and relates to the technical field of batteries. Pre-sintering is performed; sanding and spray drying; and high-temperature sintering. Wherein the pH value of the reaction is controlled by using a Tris-HCl buffer solution in the hydrothermal reaction, so that the precursor is uniformly crystallized and has high crystallinity, and low-temperature segmented presintering is adopted later, so that the compaction density of the material can be controlled, and the related electrical properties of the material are relatively good. In the preparation process, a carbon source and a doping element are supplemented twice, so that carbon coating is uniform in the sintering process, the compaction density of the NFPP positive electrode material is further improved, the properties such as theoretical specific capacity of the positive electrode material are better through doping and carbon coating modification, and the high-compaction and high-capacity ferric sodium pyrophosphate positive electrode material is obtained.

The invention belongs to the technical field of preparation of electrode materials, and particularly relates to a high-tap-density spherical ferric sodium pyrophosphate electrode material and a preparation method thereof. According to the preparation method, a uniform precursor is prepared by utilizing solution gel, and a strategy of combining spray drying with secondary sintering is adopted, so that uniform carbon coating and doping modification of ferric sodium pyrophosphate can be successfully realized, and the strategy provides an important experimental basis for an industrialization process of a sodium ion battery. And the method has great potential of large-scale preparation.

The invention relates to a copper plating electroplating solution as well as a preparation method and application thereof. The copper plating electroplating solution comprises the following components: copper pyrophosphate, a complexing agent, ammonia water, a bath building agent, a gloss agent, a pH regulator and water, the complexing agent is selected from potassium pyrophosphate or sodium pyrophosphate; the mass percentage concentration of the ammonia water is 20%-30%, and the volume concentration of the ammonia water in the copper plating electroplating solution is 2-10 mL / L; the mass concentration of the gloss agent in the copper plating electroplating solution is 10 to 50 mg / L; and the pH value of the copper plating electroplating solution is 7.8-10. When the copper plating solution is used for silver grid line copper plating, on the premise that the cost is reduced, the silver grid line copper plating has a good plating effect, the silver grid line is firm and does not fall off, and good conductive performance is kept.

The invention provides a modified ferric sodium phosphate pyrophosphate positive electrode material and a preparation method and application thereof, the modified ferric sodium phosphate pyrophosphate positive electrode material comprises a ferric sodium phosphate pyrophosphate positive electrode material and a carbon and sodium ion conductor, the carbon and sodium ion conductor is enriched on the surface and grain boundary of the ferric sodium phosphate pyrophosphate positive electrode material in a uniform composite phase, and the sodium ion conductor is NaxMOy. A composite phase material formed by carbon and a sodium ion conductor is used for coating primary particles and secondary particles of the positive electrode material, a three-dimensional conductive / conductive ion network is formed on the grain boundary and the surface of the material, and the charge and ion transmission rate of the material is high; and the three-dimensional coating layer can protect the material from being eroded by electrolyte, the structure stability is good, and the cycle performance and the rate performance of the material are excellent.

The invention discloses a composite positive electrode material, a positive plate and a secondary battery, the composite positive electrode material comprises a composite sodium ferric sulfate material and a carbon-coated ferric sodium pyrophosphate material, the composite sodium ferric sulfate material comprises a first carbon material and sodium ferric sulfate, and the first carbon material and the sodium ferric sulfate are blended; the carbon-coated ferric sodium phosphate pyrophosphate material comprises a second carbon material and ferric sodium phosphate pyrophosphate, and the second carbon material coats the ferric sodium phosphate pyrophosphate; the composite sodium ferric sulfate material is coated with the carbon-coated sodium ferric pyrophosphate material. The composite sodium ferric sulfate material is coated with the carbon-coated sodium ferric pyrophosphate material, so that the high-temperature resistance of the composite positive electrode material can be improved; through the coating effect of the whole carbon-coated ferric pyrophosphate material on the composite sodium ferric sulfate material, the second carbon material can be coated on the composite sodium ferric sulfate material, equivalently, a carbon coating layer is formed on the surface of sodium ferric sulfate, the coating property is good, sodium ion removal is facilitated, and the service life of the composite sodium ferric sulfate material is prolonged. Further, the gram volume and the energy density of the composite positive electrode material are improved.

A positive electrode material, and a preparation method therefor and the use thereof. The positive electrode material has a core-shell structure, wherein a core part comprises a carbon-coated Cu2+-doped iron-based phosphate sodium-ion material, and a shell layer is CuO. The iron-based phosphate sodium-ion material is selected from ferric sodium pyrophosphate, ferric sodium phosphate or ferric sodium phosphate pyrophosphate. The preparation method for the positive electrode material comprises: mixing the carbon-coated iron-based phosphate sodium-ion material, a copper source and a first solvent, and then subjecting the mixture to first drying and first calcination.

The invention discloses a multiphase ferric sodium pyrophosphate positive electrode material as well as a preparation method and application thereof, and belongs to the technical field of positive electrode materials. The complex-phase phosphoric acid and sodium ferric pyrophosphate positive electrode material has the following chemical formula: xNa4Fe3 (PO4) 2 (P2O7). (1-x) Na3. 12Fe2. 44 (P2O7) 2 / C, C is a carbon coating layer, and the content of the C is 8-10 wt% of the total mass of the composite-phase phosphoric acid and sodium ferric pyrophosphate positive electrode material; xNa4Fe3 (PO4) 2 (P2O7). (1-x) Na3.12Fe2.44 (P2O7) 2 is a core layer, and x is greater than or equal to 0.76 and less than or equal to 0.88. Under the condition that transition metal elements are not added for doping, the electrochemical performance of the complex-phase ferric sodium phosphate pyrophosphate positive electrode material can be obviously improved by regulating and controlling the ratio of positive ions to negative ions of original components of ferric sodium phosphate pyrophosphate, and the complex-phase ferric sodium phosphate pyrophosphate positive electrode material is low in cost, simple to prepare and suitable for large-scale production and application.

The invention provides a Na / P double-site doped phosphoric acid ferric sodium pyrophosphate / carbon positive electrode active material and a preparation method and application of the Na / P double-site doped phosphoric acid ferric sodium pyrophosphate / carbon positive electrode active material. The material comprises a Na / P double-site doped ferric sodium pyrophosphate base material and a carbon coating layer coating the surface of the base material, the general formula of the base material is Na (4-x) MxFe3 (PO4) 2-y (QO4) y (P2O7), 0 lt, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 X is less than or equal to 0.4, 0lt; y < = 0.2; m is at least one of K, Li, Mg, Ca and Sr, and Q is at least one of Si, Ge, B and S; specific elements are introduced to the Na site and the P site to form a synergistic doping structure, so that the crystal structure and charge distribution are regulated and controlled, and the electrochemical performance of the material is further improved; the material disclosed by the invention is simple and convenient to prepare, wide in raw material source, suitable for electrochemical energy storage systems such as sodium ion batteries and the like, and excellent in rate capability and long in cycle life.

The invention discloses super-hydrophobic high-thermal-stability piperazine pyrophosphate and a preparation method thereof.The super-hydrophobic high-thermal-stability piperazine pyrophosphate comprises piperazine pyrophosphate, the surface of piperazine pyrophosphate is coated with a vesicle structure, and the vesicle structure is a self-assembly structure obtained after alcoholysis reaction of a polysulfide silane compound and piperazine pyrophosphate. According to the sulfur-containing silane material with piperazine pyrophosphate coated with the vesicle structure, piperazine pyrophosphate has super-hydrophobic performance due to the vesicle structure, super-hydrophobic durability is achieved, good water resistance and extremely low moisture absorption can be kept in a high-humidity environment, and the problem that piperazine pyrophosphate powder absorbs moisture and is agglomerated can be solved. The vesicle structure has the effects of blocking heat and substance transfer and reducing the thermal oxidation rate of PAPP, so that the piperazine pyrophosphate provided by the invention also has excellent thermal stability and final char forming performance, and is beneficial to reducing the dosage of the piperazine pyrophosphate in a flame-retardant high polymer material.

The invention belongs to the technical field of sodium ion batteries, and particularly relates to a sodium ferric pyrophosphate positive electrode material as well as a preparation method and application thereof. The invention provides a preparation method of a sodium ferric pyrophosphate positive electrode material, which comprises the following steps: (1) mixing an iron source, a sodium source, a phosphorus source and citric acid for the first time, and performing spray drying for the first time to prepare a first precursor with D50 of 10-12 [mu] m; performing secondary mixing on an iron source, a sodium source, a phosphorus source and citric acid, and performing secondary spray drying to prepare a second precursor with D50 of 3-5 microns; the iron source comprises a first iron source with D50 of 1.1-1.8 [mu] m and a second iron source with D50 of 0.3-0.8 [mu] m; the mass ratio of the first iron source to the second iron source is (0.3-0.5): (0.5-0.7); and (2) mixing the first precursor, the second precursor and sodium metaborate, and sintering to obtain the sodium ferric pyrophosphate positive electrode material. After the prepared pyrophosphate ferric phosphate sodium positive electrode material is prepared into a pole piece, the compaction density is proper, and the prepared battery is high in specific capacity and cycle performance.

The invention discloses a method for synthesizing ferric phosphate pyrophosphate and preparing a sodium ferric phosphate pyrophosphate positive electrode material. The method comprises the following steps: S1, preparing a raw material solution; s2, adding the ferric salt solution, the phosphate radical solution and the pyrophosphate radical solution into the reaction base solution, controlling the pH value, and carrying out coprecipitation reaction; s3, filtering and washing, adding water, and pulping again; s4, heating and crystallizing; s5, filtering and drying; s6, sintering to obtain ferric pyrophosphate Fe6 (PO4) 2 (P2O7) 3; s7, adding ferric pyrophosphate, a sodium source and a carbon source into water, pulping, and sanding; s8, spray drying; and S9, sintering is carried out, such that Na4Fe3 (PO4) 2 (P2O7) / C is obtained. According to the method, a precursor Fe6 (PO4) 2 (P2O7) 3 is synthesized firstly, long-range ordered mixing of Fe and P elements on the atomic scale is achieved, the morphology and particle size of the precursor are controllable, the problem of generation of inactive impure-phase NaFePO4 in the synthesis process of ferric sodium pyrophosphate can be effectively solved, the raw material utilization rate is high, and the synthesized positive electrode material is large in tap density and compaction density and excellent in electrochemical performance.

The invention relates to the technical field of batteries, and discloses a high-compaction ferric sodium pyrophosphate positive electrode material and a preparation method thereof.The chemical formula of the positive electrode material is Na4Fe2.9VxTiyZrz (PO4) 2P2O7, 0.001 < = x < = 0.01, 0.002 < = y < = 0.01, and 0.001 < = z < = 0.01. The preparation method comprises the following steps that a sodium source, an iron source, a phosphorus source, a carbon source, a vanadium source, a titanium source and a zirconium source are weighed and mixed to be uniform, and a mixture is obtained; carrying out primary sanding treatment to obtain first sanding slurry, carrying out spray drying, and carrying out primary sintering treatment to obtain a pre-sintered material; adding a proper amount of carbon source into the pre-sintered material, and carrying out secondary sanding treatment to obtain a second ground material; and carrying out spray drying on the second grinding material, and carrying out secondary sintering treatment to obtain the positive electrode material. The high-compaction ferric sodium pyrophosphate positive electrode material provided by the invention has high compaction density and excellent rate capability and cycle performance, and can be used for preparing a sodium ion battery with high compaction density, high capacity and good rate capability and cycle performance.

The invention discloses ferric sodium pyrophosphate, a preparation method, a positive pole piece and a sodium ion battery, and belongs to the technical field of secondary batteries. The preparation method comprises the following steps: S1, mixing a phosphorus element, an iron element, a sodium element and a carbon element in a phosphorus source, an iron source, a sodium source and a carbon source according to a molar ratio of (1-5): (1-3): (1-5): (0.1-0.5); adding a dispersing agent and an organic solvent; s2, carrying out ball milling on the mixture obtained in the step S1; s3, carrying out vacuum drying on the mixture subjected to ball milling; and S4, sintering the material treated in the step S3 to obtain the ferric sodium pyrophosphate. The preparation method of the ferric sodium pyrophosphate comprises the following steps: uniformly mixing a phosphorus source, an iron source, a sodium source and a carbon source through ball milling, and sintering to obtain the ferric sodium pyrophosphate. The ferric sodium pyrophosphate is prepared by adopting a solid phase method, the preparation steps are simple, and large-scale production is easier.

The invention discloses a battery-grade doped modified manganese ferric sodium pyrophosphate positive electrode material as well as a preparation method and application thereof, and belongs to the field of battery materials. An ammonium manganese ferric phosphate precursor is prepared on the basis of an iron process and an ion exchange method, and is prepared into secondarily coated nitrogen-doped carbon-coated sodium manganese ferric phosphate pyrophosphate. According to the method, the content of sulfur impurities in the precursor can be controlled by adopting an ion exchange method, and a secondary sulfur removal process is avoided, so that the content (less than or equal to 100ppm) of the sulfur impurities in the modified manganese ferric ammonium phosphate reaches a battery level, and the cycle performance of the sodium ion battery is improved. The doped metal elements are uniformly distributed in the crystal lattice of the precursor in an atomic scale, so that the internal crystal electronic structure of the manganese ferric sodium phosphate pyrophosphate is effectively regulated and controlled, the structural stability of the manganese ferric sodium phosphate pyrophosphate is improved, meanwhile, the volume expansion effect of sodium ions in the embedding / removing process is relieved, and the electrochemical performance of the positive electrode material is further improved.

The invention discloses an in-situ formed sodium ferric phosphate coated sodium ion positive electrode layered oxide material, a sodium ion battery positive electrode and a sodium ion battery, the method comprises the following steps: preparing a sodium ion positive electrode layered oxide material to be coated, and measuring the residual alkali content of the sodium ion positive electrode layered oxide material; the method comprises the following steps: mixing ferric pyrophosphate with the content equal to that of residual alkali with a raw material for preparing a sodium ion positive electrode layered oxide to form a premix, sintering and slowly cooling, and forming a sodium ferric phosphate coating layer on the sodium ion positive electrode layered oxide material in situ by a residual sodium substance separated out from the surface of the sodium ion positive electrode layered oxide material and ferric pyrophosphate to prepare the sodium ion positive electrode layered oxide material. The sodium iron phosphate in-situ coated sodium ion positive electrode layered oxide material is prepared. According to the sodium ion positive electrode layered oxide material, a dense, uniform and thickness-controllable sodium ferric phosphate coating layer is formed in situ, so that residual alkali on the surface of the material can be effectively reduced, the pH value is reduced, meanwhile, the cell processing performance of the material is improved, the electrolyte corrosion resistance of the surface of the material is effectively enhanced, and the service life of the material is prolonged. The subsequent complicated process flow for reducing the residual alkali is reduced, the capacity of the sodium-ion battery positive electrode material is improved, and the production cost of the sodium-ion battery positive electrode material is reduced.

The invention provides sodium vanadium ferric phosphate pyrophosphate as well as a preparation method and application thereof. The sodium vanadium ferric phosphate pyrophosphate comprises an inner core and a coating layer coating at least part of the surface of the inner core; the molecular formula of the inner core is as shown in formula 1; na (10 + 6x) / 3 Fe (7-3x) / 3 V2x (PO4) (6x + 4) / 3 (P2O7) Formula 1; wherein x is greater than or equal to 0.25; the coating layer comprises a carbon element, a boron element and a nitrogen element. The sodium ferric vanadium phosphate pyrophosphate has excellent reversible capacity and conductivity.

The invention discloses a sodium ferric pyrophosphate material with a sodium storage dominant crystal face regulated and controlled by cation doping as well as a preparation method and application of the sodium ferric pyrophosphate material. The chemical formula of the prepared sodium ferric pyrophosphate material with the regulated and controlled crystal structure is Na < 4 > Fe < 2.97 > M < 0.03 > (PO4) < 2 > P < 2 > O < 7 >. Wherein M = Sr, or Sr and a second doping element, and the second doping element is selected from one of Cd, Bi, Mo, Ni and Al. The material is prepared by adopting a sol-gel method, an iron source, a chelating agent, a sodium source, a phosphorus source and doping elements are dissolved in deionized water, and stirring is performed until a gel state is formed; and drying and calcining twice to obtain a final product. The sodium ferric pyrophosphate electrode material prepared by the invention has more sodium storage dominant crystal faces, shows good electrochemical performance, has the advantages of simple preparation process, easily available raw materials and low cost, has remarkable industrial application value, and is easy for large-scale production.