233 results about "Iron pyrophosphate" patented technology

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.

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 relates to a preparation method of a nickel ion doped modified ferric sodium pyrophosphate positive electrode material, and belongs to the technical field of sodium ion battery positive electrode materials. The nickel ion doped modified ferric sodium pyrophosphate positive electrode material is prepared by adopting an integrated process system of liquid phase uniform mixing, spray granulation and precise segmented calcination. According to the process system, atomic-scale uniform doping of nickel ions and a specific microstructure of a precursor are realized through spray drying, and a plurality of inherent key technical problems of low electronic conductivity, low ion diffusion rate, impurity phase generation and the like of an NFPP material are solved together through a synergistic effect with a subsequent calcining process; furthermore, the discharge capacity of the ferric sodium phosphate pyrophosphate composite material at high rate is improved, so that the battery has relatively high cycling stability.

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 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.

The invention belongs to the field of battery materials, and discloses a ferric sodium pyrophosphate material as well as a preparation method and application thereof. The preparation method of the ferric sodium pyrophosphate comprises the following steps: step 1, mixing a phosphorus source, an iron source, a sodium source, a biomass carbon source and an alcohol additive, and uniformly stirring to obtain a mixed material A; step 2, carrying out hydrothermal reaction on the mixed material A, and then centrifuging and drying to obtain an intermediate product B; and 3, roasting the intermediate product C in a protective atmosphere to obtain the carbon-coated ferric sodium pyrophosphate. A three-dimensional conductive network is formed after the biomass carbon source and the NFPP are compounded, the interface resistance is reduced, the charge transfer efficiency is improved, and after the biomass carbon source is carbonized, biomass carbon with mechanical supporting and buffering effects can relieve volume expansion of the NFPP in the charge-discharge or reaction process and inhibit material pulverization, so that the cycling stability is improved.

The invention discloses a preparation method of a carbon-coated single-crystal sodium ferric pyrophosphate positive electrode material, which is specifically implemented according to the following steps: step 1, dissolving sodium salt, ferric salt and phosphate in deionized water in proportion, then adding a carbon source into the solution, and uniformly stirring to obtain a mixed solution; step 2, fully drying the mixed solution obtained in the step 1 to obtain precursor powder; and 3, carrying out heat treatment on the precursor powder in a protective atmosphere, and cooling to obtain the carbon-coated single-crystal sodium ferric pyrophosphate positive electrode material. The invention also discloses a coating prepared by the method, a single-crystal structure is combined with uniform carbon coating, grain boundary defects are eliminated, conductivity is improved, high specific capacity and long cycle life are realized, single-crystal growth and carbon layer in-situ coating are synchronously realized by a synthesis process, and structural integrity and efficient conductive network construction can be ensured.

The invention provides a sodium ferric phosphate pyrophosphate-based composite material as well as a preparation method and application thereof, and relates to the technical field of sodium ion battery electrode materials. The composite material is of a core-shell structure and sequentially comprises a base material, a heterogeneous interface layer and a coating layer from inside to outside, the chemical formula of the base material is Na4Fex( PO4) 2P2O7, the heterogeneous interface layer is iron-based phosphide nanoparticles distributed on the surface of the base material, and the coating layer is a carbon layer; the iron-based phosphide is prepared from at least one of FeP and Fe2P; 3 < = x < = 4; iron-based phosphide nanoparticles are generated on the surface of the ferric sodium phosphate pyrophosphate material through in-situ reduction, a tightly-combined heterogeneous interface network is formed, the electron and ion transmission performance of the material is remarkably improved, and the rate performance is improved; the preparation method is simple and easy to implement on a large scale.

The invention provides a sodium ferric pyrophosphate positive electrode diaphragm as well as a dry preparation method and application thereof. The dry preparation method comprises the following steps: dividing the conductive agent into a conductive agent A and a conductive agent B; mixing the conductive agent A with the ferric sodium pyrophosphate positive electrode material, and performing first stirring to obtain a first material; mixing a conductive agent B with sodium trifluoromethanesulfonate, and performing second stirring to obtain a second material; mixing the first material with the second material, and performing third stirring to obtain a third material; mixing the third material with a binder, and performing fourth stirring to obtain a fourth material; and the fourth material is subjected to fibrosis treatment and rolling in sequence to obtain the sodium ferric pyrophosphate positive electrode diaphragm. By designing the contents and proportions of the sodium ferric pyrophosphate positive electrode material, the conductive agent, the binder and the sodium trifluoromethanesulfonate and controlling the mixing method, sequence and steps, the sodium ferric pyrophosphate positive electrode diaphragm with high compaction density, high conductivity and excellent ion transmission channels is prepared.

The present invention discloses a method for preparing a composite sodium ferric pyrophosphate cathode material, which relates to the technical field of sodium batteries and includes the following steps: Step S1, preparing a precursor; Step S2, combining it with a carbon source; and Step S3, sintering it. The composite sodium ferric pyrophosphate cathode material disclosed in the present invention has excellent electrochemical performance, good electrical conductivity, strong cycle performance and rate performance, and high initial charge and discharge efficiency.

The preparation method comprises the following steps: (1) weighing a sodium source, an iron source, a phosphorus source and a carbon source, quickly and uniformly mixing, and then pre-sintering at low temperature to obtain a precursor; wherein the low-temperature presintering comprises two stages, in the first stage, the temperature is increased to 60-150 DEG C and kept for 1-3 h, and in the second stage, the temperature is increased to 200-350 DEG C and kept for 1-8 h; and (2) adding a carbon source into the precursor to prepare slurry, sanding the slurry, carrying out centrifugal spray drying, and carrying out high-temperature sintering to obtain the ferric sodium pyrophosphate positive electrode material. The precursor of the high-solid-content slurry can be prepared, the problem that the solid content of the slurry is low in the grinding stage of the sodium ferric pyrophosphate positive electrode material prepared by a solid-phase method is effectively solved, the solid content of the slurry is increased, the yield of the precursor is increased, the production cost is reduced, and meanwhile, the product quality is improved. The prepared ferric sodium pyrophosphate positive electrode material has relatively high compaction density, capacity and other performances, and the performance of the product is improved.

The invention relates to the technical field of sodium-ion battery positive electrode materials, in particular to a titanium-doped high-density spherical nano sodium ferric pyrophosphate sodium-ion battery positive electrode material and a preparation method of the titanium-doped high-density spherical nano sodium ferric pyrophosphate sodium-ion battery positive electrode material. The chemical general formula of the titanium-doped high-density spherical nano sodium ferric pyrophosphate sodium ion battery positive electrode material is NaFe3-xTix (PO) PO), x is more than or equal to 0.05 and less than or equal to 0.2, the particle size of the positive electrode material is 20-300 nm, and the surface of the positive electrode material is coated with a layer of carbon. Through multi-dimensional innovation of material-process-structure, the invention provides a high-performance positive electrode solution for commercialization of the sodium ion battery, and has both technical advancement and engineering potential.

The invention discloses a high-magnification ferric sodium pyrophosphate composite material as well as a preparation method and application thereof, and belongs to the technical field of sodium ion battery positive electrode materials. According to the positive electrode material, phosphoric acid and ferric pyrophosphate sodium nano-microspheres grow on multi-walled carbon nanotubes (MCNTs), so that the MCNTs are coated with the phosphoric acid and ferric pyrophosphate sodium nano-microspheres, and a composite material composed of a matrix MCNTS and a phosphoric acid and ferric pyrophosphate sodium microsphere coating layer is formed. The chemical formula of the material is Na4Fe3 (PO4) P2O7 (at) MCNTS. The ultrahigh-rate ferric sodium phosphate pyrophosphate composite material comprises an MCNTS carrier and a coating layer coated on the surface of the MCNTS. According to the pyrophosphate and ferric phosphate sodium nanosphere coated multi-walled carbon nanotube composite material provided by the invention, due to a cross-linked three-dimensional network structure, a sodion deintercalation path is greatly shortened, electrons are transferred among nanospheres at an ultra-fast speed, and aggregation of the nanospheres is also inhibited. Due to ultrahigh electronic and ionic conductivity, the nanospheres show remarkable high capacity, ultrahigh rate capability and super-long cycle performance.

The preparation method comprises the following steps: mixing a sodium source, an iron source, a manganese source, a phosphorus source, a carbon source, water and a polyethylene glycol additive with the weight-average molecular weight of 5000-6000, and carrying out sanding, drying, sintering, crushing and other operations on the obtained mixed slurry to obtain the sodium ferromanganese pyrophosphate positive electrode material. The sodium ferromanganese pyrophosphate positive electrode material is obtained. The sodium ferromanganese pyrophosphate positive electrode material is prepared by adopting a wet ball milling-carbon thermal reduction method, and polyethylene glycol with the weight-average molecular weight of 5000-6000 is added as an additive in the preparation process, so that the prepared sodium ferromanganese pyrophosphate positive electrode material is nano spherical particles which are uniform in size distribution and have an excellent carbon conductive network structure. When the material is applied to a sodium-ion battery, the material has good electronic and ionic conductivity, and the electrochemical performance such as discharge capacity, platform voltage, rate capability and cycle performance can be greatly improved.

The invention relates to the field of battery materials, and discloses a preparation method and application of a carbon-coated cobalt-doped ferric sodium pyrophosphate positive electrode material. The preparation method comprises the following steps: (1) preparing a clear solution from an iron source, a phosphorus source, a sodium source, a cobalt source and a carbon source; (2) converting the settled solution into precursor powder by using a spray drying method; (3) calcining the precursor powder in an inert atmosphere; and (4) crushing and grinding the calcined product to obtain the carbon-coated cobalt-doped sodium ferric pyrophosphate positive electrode material. The sodium ferric phosphate pyrophosphate positive electrode material is doped and modified through a spray drying method, the electrochemical performance of the positive electrode material is improved, and the material is high in purity, controllable in particle morphology and easy to commercially produce.

The present application discloses a method for preparing a composite sodium ferric pyrophosphate material, comprising the following steps: S1, uniformly dispersing a sodium source, an iron source, a phosphorus source, a carbon source, and a surfactant in a solvent according to a stoichiometric ratio to form a dispersion; S2, sand-milling the dispersion at a temperature T1 and discharging the slurry, controlling the discharge temperature of the slurry to T2; wherein temperatures T1 and T2 satisfy the following conditions: 20°C ≤ T1 ≤ 40°C, 20°C ≤ T2 ≤ 40°C, and T1 > T2; S3, spray-drying the slurry obtained in step S2 and sintering it to obtain the composite sodium ferric pyrophosphate material. This preparation method can greatly improve the problem of slurry agglomeration, thereby obtaining a high-quality composite sodium ferric pyrophosphate material with excellent electrochemical performance.

The invention belongs to the technical field of sodium ion battery positive electrode materials, and discloses a preparation method and application of a cobalt-containing sodium ion battery positive electrode material. The preparation method comprises the following steps: adding a sodium source, an iron source, a cobalt source, a phosphorus source and a carbon source into isopropanol, uniformly mixing to form slurry, carrying out ball milling on the slurry, drying to obtain a precursor, and calcining in an argon atmosphere to obtain the cobalt-doped carbon-coated ferric sodium pyrophosphate (Na4Fe3-xCox (PO4) 2P2O7) positive electrode material, in which x is greater than or equal to 0 and less than or equal to 0.3. The synthesis method of the ferric sodium pyrophosphate positive electrode material provided by the invention has the advantages of simplicity in operation and low energy consumption, industrial production is facilitated, meanwhile, the synthesized material ensures the stability of a crystal structure in a Na < + > intercalation / deintercalation process, the specific capacity and the rate capability of the material are improved, and the application prospect is wide. The problems of low specific discharge capacity, poor rate capability and the like of the pyrophosphate ferric phosphate sodium material are effectively solved.

The invention belongs to the technical field of sodium ion battery materials, and discloses a double-doped sodium ferric pyrophosphate positive electrode material, a preparation method and a long-circulation sodium ion battery. The rate capability of the prepared double-doped ferric sodium pyrophosphate is remarkably improved, and the double-doped ferric sodium pyrophosphate has excellent high-rate long-cycle performance and good thermal stability. In addition, elements forming the positive electrode material are elements which are widely distributed and rich in content in the earth crust at present, so that the positive electrode material is environment-friendly and relatively low in cost, and can be widely applied to secondary batteries.

The invention provides a doped ferric sodium pyrophosphate material as well as a preparation method and application thereof. The preparation method comprises the following steps: S1, blending ferrite, phosphate, strong acid and an antioxidant to form a solution A; s2, adding doped metal salt, sodium salt and a chelating agent into the solution A to form a solution B; s3, co-dropwise adding the solution B and the coprecipitation solution into grinding equipment, and maintaining the pH value to be 4.5-5.5 in the grinding process; s4, mixing and stirring the reaction product and water to form a suspension, and freeze-drying to obtain a precursor material; and S5, mixing the precursor material with a carbon source, and performing high-temperature heat treatment to obtain the doped ferric sodium pyrophosphate material. The material has excellent electrochemical performance, high compaction density and regular product morphology.

The invention relates to a preparation method of a porous sodium-ion battery ferric phosphate sodium pyrophosphate positive electrode material, and belongs to the technical field of sodium-ion battery positive electrode materials. The method comprises the steps of precursor slurry preparation, sanding, spray drying, low-temperature heat treatment, surface activation, double-stage etching, high-temperature calcination and the like. Wherein an isopropanol-hydrofluoric acid system is adopted to perform first-stage etching on the precursor so as to open the carbon coating layer and improve the permeability of subsequent etching liquid; and then, carrying out second-stage deep etching under a heating condition by adopting a hydrofluoric acid-sodium citrate system, so as to effectively remove the silicon dioxide template and form a through type porous structure. The obtained positive electrode material has a good pore structure and a conductive network, and electrolyte infiltration and construction of a sodium ion diffusion channel are facilitated, so that the rate capability and the cycle stability of the positive electrode material are improved. The preparation method disclosed by the invention is simple and convenient in process and suitable for large-scale preparation of the high-performance sodium-ion battery positive electrode material.

The invention discloses a preparation method of a composite ferric sodium pyrophosphate material, which comprises the following steps: S1, uniformly dispersing a sodium source, an iron source, a phosphorus source, a carbon source and a surfactant in a solvent according to a stoichiometric ratio to form a dispersion liquid; s2, sanding the dispersion liquid at the temperature T1, discharging, and controlling the discharging temperature of the slurry to be T2; wherein the temperatures T1 and T2 meet the following conditions: 20 DEG C < = T1 < = 40 DEG C, 20 DEG C < = T2 < = 40 DEG C, and T1 > T2; and S3, carrying out spray drying on the slurry obtained in the step S2, and sintering to obtain the composite ferric sodium pyrophosphate material. According to the preparation method, the problem of slurry agglomeration can be improved to a great extent, so that the composite ferric sodium pyrophosphate material with high quality and good electrochemical performance is obtained.

The invention discloses a rapidly synthesized ferric sodium pyrophosphate electrode material, a preparation method thereof and a positive electrode. Relates to the technical field of batteries. The preparation method comprises the following steps: S1, mixing a sodium source, an iron source, a phosphorus source and a carbon source, adding a preset volume of deionized water, and stirring until the raw materials are completely dissolved to obtain a light yellow transparent solution; s2, adding a preset amount of modified carbon nanotubes into the light yellow transparent solution, and dispersing in an ultrasonic environment to obtain a stable suspension; s3, starting a spray dryer, and collecting yellow green spherical precursor powder from a discharge port; s4, placing the yellow green spherical precursor powder obtained by spray drying in a magnetic boat, and carrying out heat preservation at 300 DEG C in a pure argon environment at a heating rate of 2 DEG C / min for 5 h to obtain black powder; and S5, transferring the black powder into Joule thermal equipment, and reacting for a preset time under a preset condition to obtain a final black powdery product. Through innovative process design and material modification, the core problems of long period, poor conductivity, low tap density and the like in the traditional preparation technology are solved.

The invention belongs to the technical field of sodium ion battery positive electrode materials, and relates to a gas-liquid mixture source plasma constructed high-capacity interface dual-modified sodium ferric pyrophosphate composite positive electrode material and a preparation method and application thereof. The preparation method comprises the following steps: taking sodium ferric phosphate pyrophosphate as a matrix, taking sulfur hexafluoride as a gas source, introducing a liquid source, and carrying out fluorine and sulfur element synergistic doping modification and surface carbon layer coating on sodium ferric phosphate pyrophosphate by utilizing a plasma technology to obtain the sodium ferric phosphate pyrophosphate composite positive electrode material. The composite positive electrode material shows excellent sodium storage cycle stability and rate capability, and has a wide market application prospect. Meanwhile, the preparation method provided by the invention is simple, rapid, efficient and convenient, is easy to control, and contributes to promoting the development and application of the high-performance sodium-ion battery positive electrode material.

The invention discloses a multi-layer continuously coated mixed electrode material sodium-ion battery and a preparation method thereof, a positive electrode adopts a layered oxide material continuously coated by multi-layer carbon-phosphoric acid ferric sodium pyrophosphate, a carbon-based dispersant adopted in the coating process has the effect of dispersing slurry and also has the effect of coating a carbon source, and wet-process mixed coating is adopted, so that the coating efficiency is greatly improved, and the service life of the battery is prolonged. And the continuity and the uniformity of the coating layer are ensured. The negative electrode adopts a carbon-coated sodium titanium phosphate material, a carbon-based dispersant is still adopted as a carbon source in the coating process, and a secondary sintering method is adopted, so that the obtained negative electrode material is purer in phase, more stable in structure and better in carbon coating effect. And finally, the prepared positive electrode material, the prepared negative electrode material and a non-aqueous electrolyte are assembled into a battery for testing, and a test result shows that the specific capacity of the battery adopting the layered oxide material continuously coated with the multi-layer carbon-phosphoric acid ferric sodium pyrophosphate as the positive electrode is not influenced, and the cycle performance is better.

The structural formula of the sodium ion battery positive electrode material is NaxFey (PO4) 2P2O7, x is more than or equal to 3.92 and less than or equal to 4.2, y is more than or equal to 2.8 and less than or equal to 3, and x-y is more than or equal to 1.1 and less than or equal to 1.4. The preparation method comprises the following steps: calcining a precursor and then cooling, or calcining the precursor and then quenching, or heating and calcining the precursor and then quenching and tempering; and S2, crushing the semi-finished product obtained by sintering in the step S1. The sintering method of the sodium ferric phosphate pyrophosphate is substantially improved, the heating-cooling process is controlled, the structure of the positive electrode material is improved, the structural formula of the positive electrode material is controlled to be NaxFey (PO4) 2P2O7, 3.92 < = x < = 4.2, 2.8 < = y < = 3 and 1.1 < = x-y < = 1.4, the tap density and the specific capacity of the sodium ferric phosphate pyrophosphate are improved, and the sodium ferric phosphate pyrophosphate has more excellent cell processing performance.

The invention relates to a perovskite oxide coated ferric sodium pyrophosphate composite material as well as a preparation method and application thereof. The composite material comprises a base material and a coating layer, the base material is ferric sodium pyrophosphate / carbon; the coating layer is a perovskite oxide, the general formula of the perovskite oxide is ABO3, and A site comprises at least one of La, Ce, Sm, Gd, K, Rb, Cs, Be, Mg, Ca and Ba; b comprises at least one of Co, Mn, Ti, Ni, Fe, Cr and Cu; the mass of the coating layer is 0.5%-10% of the mass of the composite material; the thickness of the coating layer is 10 to 1000 nm; according to the invention, the surface of the sodium ferric phosphate pyrophosphate / carbon matrix material is coated with the perovskite oxide layer, so that the ionic and electronic conductivity and stability of the sodium ferric phosphate pyrophosphate material can be effectively improved, and meanwhile, the modified composite material has excellent rate cycle performance.

The invention provides a sodium-rich ferric sodium pyrophosphate positive electrode precursor and a preparation method and application thereof.The preparation method comprises the following steps that a ferrite solution, a phosphoric acid source solution, a pyrophosphoric acid source solution, an alkaline solution and a sodium persulfate solution are injected into a base solution in a parallel flow mode for a co-precipitation reaction, the sodium-rich ferric sodium pyrophosphate positive electrode precursor is obtained; wherein the base solution is pure water. The method disclosed by the invention is simple to operate, the sodium-rich ferric sodium pyrophosphate positive electrode precursor with high sodium content, uniform element distribution and uniform phase can be prepared, the sodium-rich ferric sodium pyrophosphate positive electrode precursor is low in gas production rate in the subsequent sintering process, and the sodium-rich ferric sodium pyrophosphate positive electrode material with high compaction density can be prepared.

The invention relates to the technical field of batteries, discloses a preparation method of a high-capacity ferric sodium phosphate pyrophosphate positive electrode material, and aims to solve the problems of impurity phase generation, high drying energy consumption, complex process flow and the like caused by element segregation in an existing ferric sodium phosphate pyrophosphate material preparation process. The invention provides a preparation method for improving the capacity of a sodium ferric phosphate pyrophosphate positive electrode material and the sodium ferric phosphate pyrophosphate positive electrode material, and the preparation method comprises the following steps: preferentially grinding an iron source into fine particles, then pouring soluble raw materials into the fine particles, stirring and waiting for solidification, and then directly sintering a solidified precursor. According to the method, the slurry is instantly solidified when being uniformly stirred, fluidity does not exist, the element segregation influence caused by conventional fluidity slurry in the drying process is avoided, the prepared precursor element distribution is more uniform, the phase crystal form is better, the purity is higher, the electrochemical performance is better, and the competitiveness of the material in the low-cost market is effectively improved.

The invention provides a porous ferric sodium pyrophosphate positive electrode precursor and a preparation method and application thereof, and the preparation method comprises the following steps: carrying out a co-precipitation reaction on a ferrous source solution, a phosphorus source solution, a pyrophosphate source solution, an oxidant solution, a precipitator solution and an organic polymer solution to obtain an intermediate material; and pre-calcining the intermediate material to obtain the porous ferric sodium pyrophosphate positive electrode precursor. According to the preparation method, a porous ferric sodium pyrophosphate positive electrode material precursor is prepared through in-situ coprecipitation and pre-calcination, in the coprecipitation process, an organic high-molecular compound is introduced in situ, after precipitation is completed, an intermediate product is calcined, the organic high-molecular compound is decomposed, and the porous ferric sodium pyrophosphate positive electrode material is obtained. The porous ferric sodium pyrophosphate positive electrode precursor with excellent charge-discharge capacity and cycle performance is obtained.

The invention discloses a sodium ion battery positive electrode modification method based on a high-performance positive electrode sodium supplement additive, which is characterized in that a proper amount of sodium carboxymethyl cellulose (CMC) is introduced as the positive electrode sodium supplement additive in a positive electrode material preparation process, an ultrahigh electronic conductive network can be established, and a channel beneficial to sodium ion transmission can be formed in a positive electrode material; the migration resistance of sodium ions in the electrode material is reduced, so that the sodium ion conductivity of the electrode is improved, the sodium ions are embedded and separated more smoothly in the charging and discharging process of the battery, and the charging and discharging efficiency and the rate capability of the battery are improved. In addition, the sodium carboxymethyl cellulose serving as a positive sodium supplement additive can stabilize the electrode structure and reduce damage and structural collapse of the material in the circulation process, so that the cycle life of the battery is prolonged. A series of characterization tests prove that the rate, cycle and other electrochemical properties of the modified ferric sodium pyrophosphate material are greatly improved.