34 results about "Iron oxalate" patented technology

The invention provides lithium manganese iron phosphate as well as a preparation method and application thereof, and relates to the technical field of lithium ion batteries. Specifically, the method comprises the following steps: preparing a solution containing an iron source, a manganese source and ammonium oxalate, adjusting the pH value to be acidic, and carrying out a water bath reaction on the solution in a sealed state; after the reaction, sequentially carrying out aging, solid-liquid separation and drying to obtain Fe < 1-x > Mn < x > C < 2 > O < 4 >. 2H < 2 > O; preparing a mixed solution containing Fe < 1-x > Mn < x > C < 2 > O < 4 >. 2H < 2 > O, a lithium source, a phosphorus source and a carbon source, and sequentially performing wet ball milling, spray drying and calcination to obtain the lithium manganese iron phosphate. According to the preparation method, the manganese iron oxalate precursor is synthesized in advance, so that uniform mixing of iron and manganese on an atomic level can be realized, and the lithium manganese iron phosphate positive electrode material with high electrochemical performance is prepared; and the preparation method is simple in preparation process and low in cost, and has a good batch production prospect.

The invention discloses a manganese iron oxalate precursor, a lithium manganese iron phosphate material and a preparation method and application of the manganese iron oxalate precursor and the lithium manganese iron phosphate material, and belongs to the technical field of battery materials. The lithium manganese iron phosphate material core layer is prepared by taking the oxalate manganese iron precursor with a specific particle size range, particle size distribution uniformity and a specific structure as a raw material, and meanwhile, the shell layer comprising the ionic conductive agent and carbon is introduced outside the core layer, so that the comprehensive performance of the lithium manganese iron phosphate material can be effectively improved; and thus, the capacity, the cycle performance and the first charge-discharge efficiency of the prepared corresponding secondary battery are improved.

The invention relates to the technical field of electrode materials, and particularly discloses a ferrocobalt oxalate / foamed nickel composite material and a preparation method and application thereof. Nanometer flower-shaped cobalt iron oxalate (CoFeC2O4) is loaded on a foamed nickel substrate through a simple coprecipitation method. Through the synergistic effect of components and morphology, the hydrazine oxidation reaction can be started at a lower overpotential, the reaction kinetics process is accelerated, meanwhile, the cathode hydrogen evolution reaction is promoted, and the efficiency of the whole water electrolysis hydrogen production system is synergistically improved; the chemical property of the ferrocobalt oxalate is relatively stable, and the structure and catalytic performance of the ferrocobalt oxalate can be maintained for a long time; in addition, the raw materials cobalt and iron are abundant in reserves, the cost is far lower than that of a noble metal catalyst, the preparation process is simple, the material can be prepared at the room temperature, industrial large-scale production is facilitated, the material shows huge application potential in the field of hydrazine oxidation assisted water electrolysis hydrogen production, and efficient and sustainable development of the hydrogen energy industry is expected to be promoted.

The utility model particularly relates to three-axis linkage synthesis mixing equipment, a mixing reaction method and a method for preparing ferric oxalate. The three-axis linkage synthesis mixing equipment comprises a motor and a gear box, a volute is arranged at the top of the outer barrel, and an air outlet is formed in one side of the volute and used for exhausting air; the three rotating shafts are arranged in the outer cylinder body, each rotating shaft is provided with an inner cylinder body, a plurality of vertically arranged gas-liquid separation plates are uniformly arranged on the upper part of each inner cylinder body along the peripheral side, and a plurality of layers of blades which are parallel to one another and are obliquely arranged are arranged on the lower part of each inner cylinder body along the peripheral side; the bottom of the volute is provided with an opening matched with the inner cylinder with the gas-liquid separation plate in size; the inner cylinders on the three rotating shafts are mutually enclosed to form an inner duct, and the rotating shafts are synchronously driven by a motor to rotate through a gearbox; a plurality of annular separation discs are arranged on the inner wall of the outer cylinder body; and an air inlet is further formed in the peripheral side of the outer cylinder body. The utility model has the advantages that the contact area and the contact time of the solvent and the air are fully increased and prolonged in a weightless state.

To provide a method for preparing an in situ metal doped manganese iron oxalate precursor.SOLUTION: Iron source, manganese source, doped metal elements (Mg, Zn, etc.) are weighed according to a stoichiometric ratio, and deionized water is added to the weighed metal to ultrasonically dissolve the weighed metal to obtain a mixed metal solution. The mixed metal solution is added to a prepared oxalic acid solution and subsequently a certain concentration of complexing agent is added to the solution to perform co-precipitation reaction under the protection of inert gas. A resultant suspension of metal doped manganese iron oxalate is recovered and then filtered, washed and dried to obtain a powder of manganese iron oxalate precursor.EFFECT: By using the manganese iron oxalate precursor as the iron and manganese sources, this can effectively avoid the problem of uneven mixing due to the iron and manganese sources. Moreover, lithium manganese iron phosphate synthesized from the manganese iron oxalate precursor after metal doping can significantly improve the electronic conductivity, thereby enhancing the electrochemical properties of lithium manganese iron phosphate.SELECTED DRAWING: Figure 1

The application provides a method for treating acid high-salt tungsten residue wastewater and recycling heavy metals and organic matters, which comprises four steps of precipitation, primary adsorption, secondary adsorption and oxidative deamination. First, ammonium oxalate is added into the tungsten residue wastewater to obtain intermediate effluent I and iron oxalate precipitate; then the intermediate effluent I is passed through a silver-copper exchange resin column to remove silver and copper in the wastewater, and intermediate effluent II is obtained; then the intermediate effluent II is passed through an organic matter exchange resin column to remove organic matters in the wastewater, and intermediate effluent III is obtained; finally, alkali is added into the intermediate effluent III to adjust the pH value to alkaline, an ammonia nitrogen remover is added, and aeration reaction is carried out; after the reaction is completed, PAM coagulant aid is added, and the mixture is statically deposited to obtain sludge and final effluent, and ammonia nitrogen in the wastewater is effectively removed. The method effectively removes heavy metals, ammonia nitrogen, COD and other pollutants in the acid high-salt tungsten residue wastewater, realizes recycling of iron, silver, copper and organic extractant, saves resources and protects the environment.

Provided are a composite carbon source-coated lithium manganese iron phosphate cathode material and a preparation method and use thereof.SOLUTION: (1) subjecting a two metal mixed solution containing a manganese source and an iron source to a co-precipitation reaction with an oxalic acid solution, followed by filtration, washing and drying to obtain a manganese iron oxalate precursor, and (2) mixing the manganese iron oxalate precursor with a lithium source and a carbon source, followed by sand grinding, spray drying, sintering and grinding to obtain the lithium manganese iron phosphate cathode material. The method has the advantages of simple preparation process, easy industrial mass production, good economic benefit and low preparation cost, and can effectively improve the charge and discharge specific capacity of the lithium manganese iron phosphate cathode material, and the composite carbon source-coated lithium manganese iron phosphate cathode material solves the problems of poor electron conductivity, low lithium ion diffusion rate and the like.SELECTED DRAWING: Figure 3

The invention discloses a thin-layer iron monatomic catalyst for efficiently degrading intracellular resistance genes and application, and relates to the technical field of material engineering and environmental engineering. The preparation method comprises the following steps: firstly, carrying out graded assembly on ferric oxalate, cyanuric acid and melamine according to a hydrogen bond acting force sequence to construct a supramolecular solid; by utilizing the low-boiling-point characteristic of a small-molecular alcohol compound, interlayer intercalation and stripping are realized by adopting a condensation reflux device, and a supramolecular precursor is obtained; and then pyrolyzing in argon to prepare the iron monatomic catalyst with controllable layer number. The iron monatomic catalyst with high loading capacity and a thin-layer structure is constructed through a strategy of oxalic acid bridging coordination and intercalation stripping, the exposure rate of active sites and the accessibility of a reaction substrate are essentially improved through the design, and a new material and a new technical scheme are provided for efficient and stable removal of intracellular resistance genes.

The invention discloses an application method of hydrothermal carbon loaded oxalyte in heavy metal adsorption. According to the application method, the effect of the hydrothermal carbon-loaded oxalatite on the adsorption of the arsenic element and the cadmium element is found for the first time, the effect of the hydrothermal carbon-loaded oxalatite on the combined and synergistic adsorption of the arsenic element and the cadmium element is particularly found, and particularly, the existence of the arsenic element can promote the adsorption of the cadmium element. According to the method, competitive adsorption between cadmium and arsenic can be avoided, the method has high adsorption capacity on both cadmium and arsenic, and a new way is provided for rapidly, efficiently and synchronously treating arsenic and cadmium in water.

To provide a method for preparing an in situ metal doped manganese iron oxalate precursor.SOLUTION: Iron source, manganese source, doped metal elements (Mg, Zn, etc.) are weighed according to a stoichiometric ratio, and deionized water is added to the weighed metal to ultrasonically dissolve the weighed metal to obtain a mixed metal solution. The mixed metal solution is added to a prepared oxalic acid solution and subsequently a certain concentration of complexing agent is added to the solution to perform co-precipitation reaction under the protection of inert gas. A resultant suspension of metal doped manganese iron oxalate is recovered and then filtered, washed and dried to obtain a powder of manganese iron oxalate precursor.EFFECT: By using the manganese iron oxalate precursor as the iron and manganese sources, this can effectively avoid the problem of uneven mixing due to the iron and manganese sources. Moreover, lithium manganese iron phosphate synthesized from the manganese iron oxalate precursor after metal doping can significantly improve the electronic conductivity, thereby enhancing the electrochemical properties of lithium manganese iron phosphate.SELECTED DRAWING: Figure 1

The application relates to the technical field of supercapacitor electrode materials, in particular to a MXene / iron oxalate composite material and a preparation method thereof. The preparation method comprises the following steps: preparing MXene nanosheets; mixing, stirring and then placing MXene suspension, FeSO4.7H2O, ascorbic acid and H2C2O4.2H2O into a muffle furnace to perform a hydrothermal reaction to obtain the MXene / iron oxalate composite material. The MXene and the iron oxalate are compounded by the hydrothermal method, the conductivity of the MXene is improved, a three-dimensional conductive network is generated after the in-situ compounding of the MXene and the iron oxalate, the conductivity of the composite material is further improved, the crystallinity of the iron oxalate is increased with the increase of the temperature under the hydrothermal condition, the ion transmission rate is improved after the cross-compounding of the MXene and the iron oxalate, and the performance of the composite material is improved.

The application provides a manganese iron oxalate precursor material and a preparation method thereof, a manganese iron lithium phosphate positive electrode material, a positive electrode sheet and a secondary battery, and relates to the technical field of secondary batteries. x Fe (1‑x) C2O4,0

The invention discloses a solvent extraction preparation method of high-purity ferrous oxalate, and relates to the technical field of ferrous oxalate preparation.The method comprises the steps that an acid solution is adopted for carrying out acid leaching treatment on an iron-containing raw material, and filtering is carried out to obtain iron-containing leachate; carrying out multi-stage extraction on the iron-containing leachate by adopting an organic phase containing an extracting agent, and selectively extracting iron to obtain an iron-loaded organic phase; washing the iron-loaded organic phase with a detergent to obtain a purified organic phase; carrying out back extraction on the purified organic phase by adopting an oxalic acid back extraction agent to obtain an iron oxalate back extraction solution; and the ferric oxalate strip liquor is subjected to reduction conversion treatment, and high-purity ferrous oxalate is obtained. According to the method, the problem that the purity of the ferrous oxalate is limited by the purity of the raw materials is solved, the ferrous oxalate with the purity larger than 99.99% is obtained, the yield of iron is larger than 98%, and high-purity, low-pollution, low-energy-consumption and low-production-cost preparation of the ferrous oxalate is achieved.

The invention relates to a porous ferroferric oxide / nitrogen-doped carbon composite material as well as a preparation method and application of the porous ferroferric oxide / nitrogen-doped carbon composite material, and belongs to the technical field of secondary battery materials. On one hand, nitrogen-doped carbon formed by pyrolysis of polyacrylonitrile can effectively improve the conductivity of the material and provide multiple active sites, and on the other hand, the synergistic effect of the two materials can effectively improve the electrochemical performance of the material as a lithium ion battery negative electrode material; in addition, the porous structure can provide a convenient lithium ion transmission channel and buffer volume expansion; the method is simple in preparation process, mild and controllable in reaction condition, high in product yield, low in cost and convenient to popularize and apply; the prepared porous ferroferric oxide / nitrogen-doped carbon composite material (Fe3O4 / NC) is excellent in electrochemical performance and has a wide application prospect.

The invention discloses a method for comprehensively utilizing titanium dioxide waste residues. The method comprises the following steps: mixing titanium dioxide waste residues with water, adding a reducing agent to obtain a first solid-liquid mixture, and separating to obtain a first solid and a first filtrate; adjusting the pH value of the first filtrate to 5.0-6.0 to obtain a second solid-liquid mixture, and separating to obtain a second solid and a second filtrate; the second solid is washed and treated with alkali liquor to obtain a sodium metaaluminate solution and a crude titanium solid, the sodium metaaluminate solution is concentrated and crystallized to obtain a sodium metaaluminate solid, and the crude titanium solid is washed and purified to obtain a high-purity titanium product and rare earth metal; adding a sodium sulfide solution into the second filtrate to obtain a third solid-liquid mixture, and separating to obtain a third solid and a third filtrate; adjusting the pH value of the third filtrate to 5.0-6.0 to obtain a fourth solid-liquid mixture, and separating to obtain a fourth solid and a fourth filtrate; the fourth filtrate is used for preparing ferric phosphate, ferric oxalate and / or ferrous sulfate. According to the method, a series of high-purity basic chemical raw materials can be obtained by performing grading treatment on the titanium dioxide waste residues.

The present disclosure provides a lithium iron manganese phosphate cathode material and its preparation method and application. The preparation method comprises the following steps: (1) mixing aniline, phytic acid and a solvent to obtain a mixed solution, and mixing the mixed solution with mesoporous manganese dioxide to carry out a one-step reaction; (2) adding a ferrous salt solution and an oxalic acid source solution to the mixture obtained by the one-step reaction, and carrying out a two-step reaction to obtain a manganese iron oxalate precursor; (3) mixing the manganese iron oxalate precursor with a lithium source and a phosphorus source, and sintering the precursor to obtain the lithium iron manganese phosphate cathode material. The present disclosure pre-prepares a manganese iron oxalate precursor having a polyaniline network structure inside. After sintering, an N and P-doped carbon network is formed inside the lithium iron manganese phosphate. Compared with carbon coating only on the outer layer, this method can make the material more uniformly conductive and improve the material's capacity and cycle stability.

The invention discloses a method for preparing lithium iron manganese phosphate, belonging to the technical field of lithium batteries; the invention provides a method for preparing lithium iron manganese phosphate, comprising the following steps: step 1: putting manganese iron oxalate, lithium dihydrogen phosphate, lithium carbonate, sucrose, and magnesium hydroxide into equipment in sequence, adding anhydrous ethanol and then ball milling to obtain slurry A; step 2: filtering the slurry A in step 1 through a 100-mesh drying net, spray drying to obtain powder B; step 3: placing the powder B in step 2 under an inert gas atmosphere, sintering to obtain sintered material C; step 4: ball milling the sintered material C in step 3, polyvinyl alcohol, and anhydrous ethanol to obtain slurry D; step 5: spray drying the slurry D in step 4 to obtain powder E; step 6: placing the powder E in step 4 under an inert gas atmosphere, sintering to obtain sintered material F, cooling and crushing the screen to obtain lithium iron manganese phosphate. The method is simple, low-cost, and suitable for industrialization.

The present disclosure is directed to processing iron-containing feedstocks using oxalic acid to cost-effectively and cleanly transform low-cost iron feedstocks into iron-containing products (e.g., metallic iron and / or iron oxide) of high purity. In general, the methods of production using the systems described herein may include leaching low-purity iron feedstocks using a lixiviant including oxalic acid and an iron-complexing additive. The iron-complexing additive may suppress formation of iron (II) oxalate crystals and iron (III) oxalate crystals as leaching of a low-purity iron feedstock is carried out using oxalic acid, thus improving process kinetics and increasing the amount of iron that goes into solution during the leaching operation and ultimately recovered as a high-purity iron-containing product (e.g., metallic iron and / or iron oxide).

The invention discloses ferromanganese oxalate, lithium ferromanganese phosphate, a preparation method of the ferromanganese oxalate and the lithium ferromanganese phosphate, and a positive pole piece, a battery and an electric device comprising the ferromanganese oxalate and the lithium ferromanganese phosphate, the preparation method of the ferromanganese oxalate comprises the following steps: adding manganese powder into an industrial manganese sulfate aqueous solution, and reacting under stirring and heating conditions to obtain a manganese sulfate suspension; filtering to obtain a refined manganese sulfate aqueous solution; uniformly mixing an iron source solid or an iron source aqueous solution with the refined manganese sulfate aqueous solution to obtain a manganese-iron mixed metal salt solution; adding the obtained manganese-iron mixed metal salt solution into a precipitant aqueous solution for reaction; and after the ferromanganese mixed metal salt solution is fed, adding an alkaline pH regulator for continuous reaction to obtain a ferromanganese oxalate suspension, and then filtering, washing and drying to obtain a ferromanganese oxalate solid. The preparation method of the oxalate ferromanganese provided by the invention is simple in process, low in cost, great in environmental protection advantage and easy for industrial production.

The invention relates to the technical field of catalyst recycling, in particular to a method for selectively removing iron ions in a cobalt-manganese acetate catalyst system, which comprises the following specific steps: mother liquor concentration, primary dissolution, redissolution, separation of organic liquid and cobalt-manganese carbonate, iron-cobalt complex separation, oxidation decomplexing, selective precipitation, solid-liquid separation and acidity recovery. Finally, cobalt acetate and manganese catalysts are obtained and sent to a catalyst collecting tank to be recycled by a process device, and separated ferric oxalate serves as a by-product. According to the method, the generated iron-cobalt complex is reduced by optimizing control conditions in the catalyst recovery process, after the produced iron-cobalt complex is decomplexed, Fe < 3 + > and oxalate ions in the precipitation stock solution are subjected to a complexation reaction to generate an iron oxalate coordination compound precipitate, so that the purpose of removing oxalic acid in the precipitation stock solution is achieved, and the recovery rate of the catalyst is improved. Furthermore, pure cobalt acetate and manganese acetate solutions are recovered, and the recovered catalyst can be directly reused in the original production of a process device.

The invention relates to a novel method for preparing an oxalate ferromanganese precursor, which comprises the following steps: mixing water-soluble manganese salt, water-soluble ferric salt, a doping aid 1 and water-soluble oxalate in a water-organic solvent system, and carrying out coprecipitation reaction. The invention also relates to a method for preparing the lithium manganese iron phosphate positive electrode material, which comprises the following steps of: mixing an oxalate manganese iron precursor with a lithium source, a phosphorus source and a doping auxiliary agent 2, drying, roasting at low temperature to obtain a lithium manganese iron phosphate precursor, mixing the precursor with an organic carbon source, drying, and sintering at high temperature to obtain the lithium manganese iron phosphate positive electrode material. The carbon-coated lithium manganese iron phosphate positive electrode material is obtained. The invention further relates to the manganese iron oxalate precursor and the lithium manganese iron phosphate positive electrode material prepared by the method.

This application provides a continuous reaction system, a manganese iron oxalate precursor, lithium manganese iron phosphate, a preparation method, and a secondary battery. The preparation method of the manganese iron oxalate precursor provided in this application is a continuous preparation method, which can improve production efficiency, simplify the production process, and obtain a manganese iron oxalate precursor with small particle size, narrow particle size distribution, uniform elemental distribution, high crystallinity, regular morphology, and high batch stability and consistency.

The invention discloses a method for removing oxalic acid and ferric oxalate complexes in a molten solution, which comprises the following steps: S1, carrying out UV illumination treatment on a solution containing target metabolic micromolecules, oxalic acid and ferric oxalate complexes at a low temperature of not higher than 77K, and then putting the solution into a dDNP spectrometer for polarization and melting to obtain the molten solution; s2, quickly adding a sodium hydroxide solution into the molten liquid, adjusting the pH value of the molten liquid to be alkaline, and starting to generate precipitates; s3, after the precipitation is completed, rapidly filtering to remove the precipitate to obtain a filtrate; s4, rapidly adding a hydrochloric acid solution into the filtrate, adjusting the pH value of the filtrate to be neutral, and starting to generate a precipitate; and S5, after the precipitation is completed, quickly filtering to remove the precipitation to obtain polarized clear liquid without oxalic acid and ferric oxalate complexes, and injecting the polarized clear liquid into the to-be-detected magnet of the dDNP spectrometer. Excessive sodium hydroxide and a pressure filtration type impurity removal device are introduced, and oxalic acid and oxalic acid complex iron in the molten liquid are successfully removed.

The invention provides an oxalate ferromanganese precursor material and a preparation method thereof, a lithium iron manganese phosphate positive electrode material, a positive electrode plate and a secondary battery, and relates to the technical field of secondary batteries. The chemical formula of the oxalate ferromanganese precursor material is MnxFe (1-x) C2O4, 0lt; xlt; 1; primary particles of the oxalate ferromanganese precursor material are of a sheet structure, the length of the primary particles ranges from 1000 nm to 1500 nm, the width of the primary particles ranges from 400 nm to 870 nm, and the thickness of the primary particles ranges from 300 nm to 500 nm. By controlling the composition of the manganese iron oxalate precursor material and the morphology and size of primary particles, the electrochemical performance of the lithium manganese iron phosphate positive electrode material prepared from the manganese iron oxalate precursor material in the aspects of charge-discharge specific capacity and first coulombic efficiency can be improved.

Provided are a lithium manganese iron phosphate positive electrode material, a preparation method therefor, and a use thereof. The preparation method comprises the following steps: (1) mixing aniline, phytic acid and a solvent to obtain a mixed solution, and mixing the mixed solution with mesoporous manganese dioxide for a one-step reaction; (2) simultaneously adding, to the mixed material obtained by the one-step reaction, a ferrous salt solution and an oxalic acid source solution for a two-step reaction to obtain a manganese iron oxalate precursor; and (3) mixing the manganese iron oxalate precursor with a lithium source and a phosphorus source, and carrying out sintering treatment to obtain the lithium manganese iron phosphate positive electrode material. The manganese iron oxalate precursor internally having a polyaniline mesh structure is prepared in advance, and upon sintering, N- and P-doped carbon networks are formed inside lithium manganese iron phosphate. Compared with carrying out carbon coating on an outer layer alone, the present invention makes a material be uniformly conductive, and improves the capacity and cycle stability of the material.

The application discloses a preparation method of in-situ carbon-coated sodium iron oxalate sulfate composite material and application thereof, and first takes H2C2O4.2H2O, FeC2O4.2H2O, a sulfate and a sodium source as reaction raw materials, adds a surfactant and a carbon source, and prepares in-situ carbon-coated sodium iron oxalate sulfate nanocomposite material through accurate control of heating time of a hydrothermal reaction. The nanocomposite material exhibits excellent sodium storage performance when used as a sodium battery positive electrode, and the NaFe(C2O4)SO4@C nanocomposite material prepared by the application is uniform in morphology, fast in preparation and uniform in crystal grain size distribution.

The present invention discloses a method for removing Cr(VI) from wastewater by preparing oxalate manganese-iron composite oxide using iron-rich manganese slag. The steps are as follows: first, the iron-rich manganese slag just discharged from the filter press workshop is transported to a slurry mixing tank, and then water and sulfuric acid in a set ratio are added to the slurry mixing tank. After the mixture is evenly mixed, solid-liquid separation is performed to obtain a leachate and a leach residue; second, iron powder and oxalic acid in a set ratio are added to the leachate, and after sufficient reaction, solid-liquid separation is performed to obtain a solid precipitate, which is the oxalate manganese-iron composite oxide; finally, the oxalate manganese-iron composite oxide in a set ratio is added to a certain concentration of chromium-containing wastewater, and Cr(VI) is removed from the chromium-containing wastewater under set reaction temperature, current density, reaction pH and other conditions, so that the wastewater can meet the discharge standards. The overall process of the present invention has the advantages of simple operation and low cost. It can not only effectively improve the recycling of iron and manganese resources in the iron-rich manganese slag, but also achieve efficient removal of Cr(VI) from wastewater.

The present disclosure is directed to processing iron-containing feedstocks using oxalic acid to cost-effectively and cleanly transform low-cost iron feedstocks into iron-containing products (e.g., metallic iron and / or iron oxide) of high purity. In general, the methods of production using the systems described herein may include leaching low-purity iron feedstocks using a lixiviant including oxalic acid and an iron-complexing additive. The iron-complexing additive may suppress formation of iron (II) oxalate crystals and iron (III) oxalate crystals as leaching of a low-purity iron feedstock is carried out using oxalic acid, thus improving process kinetics and increasing the amount of iron that goes into solution during the leaching operation and ultimately recovered as a high-purity iron-containing product (e.g., metallic iron and / or iron oxide).

The application relates to the technical field of battery material preparation, in particular to a method for preparing iron phosphate, iron phosphate and application. The method comprises the steps of adding a crystal form inhibitor into a crude iron phosphate product, aging, and calcining; the crystal form inhibitor comprises a phosphoric acid type crystal form inhibitor and an iron type crystal form inhibitor; the phosphoric acid type crystal form inhibitor comprises at least one of monoammonium phosphate, diammonium phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate and phosphoric acid; and the iron type crystal form inhibitor comprises at least one of iron hydroxide, iron hydroxyphosphate, iron sulfate and iron oxalate. The prepared iron phosphate has few by-products in the aging stage, high iron-phosphorus ratio, good capacity and rate performance, and long cycle life.

The application provides a preparation method of carbon composite divalent silicon material, comprising the following steps: grinding silicon-containing biomass into solid powder, mixing the solid powder with a metal oxalate mixture, calcining under an inert atmosphere, performing a carbothermic reduction reaction, and removing impurities to obtain the carbon composite divalent silicon material; the metal oxalate mixture is composed of two metal oxalates, namely a first metal oxalate and a second metal oxalate; the first metal oxalate is selected from one of tin oxalate or manganese oxalate; the second metal oxalate is selected from one of manganese oxalate, iron oxalate or zinc oxalate; the first metal oxalate is different from the second metal oxalate; and the molar ratio of the first metal oxalate to the second metal oxalate is 10:1-3. The molten metal ball formed by the metal oxalate mixture during high-temperature calcination catalyzes the reduction of tetravalent silicon in the silicon-containing biomass into divalent silicon, the catalytic efficiency is high, and the energy consumption and production cost of the reaction are reduced.