3547 results about "Iron phosphate" patented technology

The invention discloses a preparation method of a high-compaction-density lithium iron phosphate material, through grading of large and small particle lithium iron phosphate, optimization of a sintering process and reasonable selection of a carbon source and a titanium dopant, the compaction density and the electrochemical performance of the material are remarkably improved, and the preparation method specifically comprises the following steps: mixing iron phosphate, lithium carbonate, the carbon source and auxiliary materials; the preparation method comprises the following steps: carrying out coarse grinding and fine grinding, respectively preparing large-particle lithium iron phosphate and small-particle lithium iron phosphate (a material A and a material B) by adopting spray drying and high-temperature calcination processes, mixing the material A and the material B according to a ratio, adding auxiliary materials, grinding, further carrying out spray drying, calcining and crushing to obtain a final lithium iron phosphate product, and the maximum compaction density of the prepared material can reach 2.712 g / cm < 3 >. According to the present invention, the maximum 1C discharge specific capacity can achieve 140.5 mAh / g, the maximum 1C 3.2 V discharge platform retention rate is 91.4%, and the prepared lithium ion battery negative electrode material has characteristics of excellent conductivity, high discharge capacity and good cycle stability, and is suitable for power batteries and energy storage batteries.

The invention relates to a waste lithium iron phosphate battery recycling method, in particular to a graded recycling method for lithium, iron, phosphorus and graphite in a waste lithium iron phosphate battery, and belongs to the technical field of lithium ion batteries and resource recycling of the lithium ion batteries. According to the method, the mode that oxidizing roasting and selective leaching are combined is adopted, the leaching rate and selectivity of lithium are effectively improved, the leaching rate of the lithium element is close to 100% under the optimized condition, and limit recovery of the lithium element is achieved; meanwhile, aiming at the problem that iron and phosphorus in the leaching residues are difficult to utilize, a wet ball milling and secondary acid leaching method is combined, phosphorus and iron elements are separated from negative electrode graphite firstly, and graded recovery of iron, phosphorus and graphite is achieved. According to the method, the high recovery rate of lithium is realized, and meanwhile, high-added-value products such as ferric oxide and sodium phosphate are prepared by efficiently recovering ferric phosphate.

The invention discloses a preparation method of a high-compaction lithium manganese iron phosphate positive electrode material, which comprises the following steps: placing a manganese source, an iron source and a phosphorus source in deionized water, stirring, carrying out primary high-speed ball milling, carrying out constant-temperature water bath, adding an oxidizing agent, stirring and oxidizing, and drying the slurry to obtain manganese iron phosphate precursor powder; carrying out primary sintering on the ferromanganese phosphate precursor powder to obtain a ferromanganese phosphate primary sintering material; putting the ferromanganese phosphate primary sintering material into deionized water, adding a lithium source and a carbon source at the same time, and performing stirring, secondary high-speed ball milling and drying to obtain lithium ferromanganese phosphate precursor powder; and carrying out secondary sintering on the lithium manganese iron phosphate precursor powder to obtain the high-compaction lithium manganese iron phosphate positive electrode material. The void ratio is well reduced and good carbon coating is realized by means of secondary grinding and secondary sintering, and compared with the prior art, the method has the advantages that good capacity can be maintained, the powder compaction density of the material can be improved, the conductivity can be improved, and the specific surface area of the material can be effectively reduced.

The invention relates to the technical field of lithium iron phosphate production, and discloses a carbon-coated titanium-doped lithium iron phosphate positive electrode material and a preparation method thereof.The preparation method comprises the following steps that 1, a ferrous solution and a phosphorus source solution are mixed in proportion, dopamine hydrochloride is added, a pH regulator is dropwise added in the stirring state, the pH of the solution is adjusted to 4.0-5.5, a reaction is conducted, a titanium source solution is added, and a reaction solution is obtained; after uniformly stirring, continuously dropwise adding a pH regulator to regulate the pH value of the solution to 5.5-6.5; the iron phosphate octahydrate coated with the titanium-embedded polydopamine is obtained; 2) calcining the titanium-embedded polydopamine-coated ferrous phosphate octahydrate in an inert gas atmosphere to obtain carbon-coated titanium-doped anhydrous ferrous phosphate; 3) mixing the carbon-coated titanium-doped anhydrous ferrous phosphate with lithium phosphate and a carbon source, ball-milling, mixing, spray-drying and calcining to obtain a carbon-coated titanium-doped lithium iron phosphate positive electrode material; the synthesis process is simple, and energy consumption is reduced.

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 provides a positive electrode material and a preparation method thereof, a positive electrode plate and a battery, the positive electrode material comprises lithium manganese iron phosphate particles, a first shell layer and a second shell layer, the first shell layer and the second shell layer sequentially coat the surfaces of the lithium manganese iron phosphate particles, the material of the first shell layer comprises nanoscale SiO2 particles, and the material of the second shell layer comprises nanoscale TiO2 particles. The surfaces of the lithium manganese iron phosphate particles are sequentially coated with the SiO2 layer and the TiO2 layer, so that the contact between the lithium manganese iron phosphate particles and an electrolyte can be reduced, the side reaction between the lithium manganese iron phosphate particles and the electrolyte in the electrochemical reaction process is reduced, the cycle life attenuation of the battery is relieved, the dissolution of Mn element is reduced, and the service life of the battery is prolonged. Therefore, the battery impedance increase caused by deposition of Mn < 2 + > on the negative electrode in the circulation process is relieved.

The invention provides a battery monomer, a battery device and a power utilization device. The battery monomer comprises an electrode assembly, wherein the electrode assembly comprises a positive plate, a negative plate and a non-aqueous electrolyte; the positive plate comprises a positive current collector and a positive film layer, and the negative plate comprises a negative current collector and a negative film layer; the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises a lithium manganese iron phosphate material and a nickel cobalt lithium manganate material; in the nickel cobalt lithium manganate material, the molar ratio of Ni in the sum of the three elements of Ni, Co and Mn is 0.5-0.95; the non-aqueous electrolyte comprises vinylene carbonate, and the mass content of the vinylene carbonate in the non-aqueous electrolyte is 0.5%-2%; the non-aqueous electrolyte comprises at least one of linear carbonic ester and linear carboxylic ester, and the conductivity of the non-aqueous electrolyte is 9-14 mS / cm. The energy density, the cycle performance and the power performance of the battery monomer are improved at the same time.

The invention provides a lithium iron manganese phosphate positive electrode material and a preparation method and application thereof, the lithium iron manganese phosphate positive electrode material comprises a doped type iron manganese phosphate inner core and a coating layer coating the surface of the doped type iron manganese phosphate inner core, and the coating layer is a lithium-containing carbon layer; the doped iron manganese phosphate inner core comprises doped ions, and in the particles of the doped iron manganese phosphate inner core from inside to outside, the content gradient of manganese ions and iron ions is reduced, and the content gradient of the doped ions is increased. According to the lithium manganese iron phosphate positive electrode material with the structure, a series of problems caused by poor phase structure stability, poor conductivity and Jahn-Teller effect and manganese dissolution of the material in the lithium manganese iron phosphate positive electrode material can be effectively improved; further, the conductivity of the lithium manganese iron phosphate positive electrode material and the comprehensive performance of gram volume, cycling stability and the like when the lithium manganese iron phosphate positive electrode material is applied to a battery are improved.

The invention provides a lithium iron phosphate material and a preparation method thereof, a positive pole piece and a secondary battery, and relates to the field of positive pole materials. The lithium iron phosphate material meets the condition that sigma b / sigma f is larger than or equal to 1.10 and smaller than or equal to 5.00, sigma b is the sample standard deviation of the circularity C of large-particle lithium iron phosphate, sigma f is the sample standard deviation of the circularity C of small-particle lithium iron phosphate, and the large-particle lithium iron phosphate and the small-particle lithium iron phosphate with different morphologies are matched with each other through the difference of the sample standard deviation of the circularity of the large-particle lithium iron phosphate and the sample standard deviation of the circularity of the small-particle lithium iron phosphate. Therefore, the lithium iron phosphate material has good tap density and specific surface area. According to the preparation method of the lithium iron phosphate material, the large-particle-size iron phosphate seed crystal partially coated with polydopamine is subjected to vacuum dehydration to obtain the modified iron phosphate seed crystal with the dehydrated surface layer, the morphology of the large-particle iron phosphate prepared by precipitation reaction is influenced, and the iron phosphate material is obtained by utilizing the large and small seed crystals through a coprecipitation method. And finally, the lithium iron phosphate material with good tap density and specific surface area is prepared.

The invention provides an iron-based phosphate positive electrode material as well as a preparation method and application thereof. The preparation method of the positive electrode material comprises the following steps: reacting a mixed material containing metallic iron and a phosphorus source at normal temperature to 100 DEG C to form a solid-liquid mixture containing a phosphate iron salt compound; mixing the solid-liquid mixture with an acidity regulator, a carbon source and a sodium source, and sanding to obtain slurry; performing drying treatment on the slurry to obtain a precursor material; and sintering the precursor material under a protective atmosphere condition to obtain the iron-based phosphate positive electrode material. According to the method provided by the invention, the metal iron and the phosphorus source do not need to be mixed and completely dissolved to form a solution in the reaction process, and anhydrous iron phosphate does not need to be formed firstly, so that the method for preparing the iron-based phosphate positive electrode material is short in process and relatively low in requirements on reaction conditions, and is applicable to industrial production and large-scale production.

The invention provides a lithium ion battery and electric equipment, the lithium ion battery comprises a positive pole piece and an electrolyte, active substances in the positive pole piece comprise a phosphate lithium positive pole material and nickel cobalt manganese lithium oxide, and the electrolyte comprises a positive pole film-forming agent, a negative pole film-forming agent and a lithium salt, the lithium salt comprises lithium hexafluorophosphate and lithium bis (fluorosulfonyl) imide, the lithium ion battery meets the following formula: # imgabs0 #, NL is the mass ratio of the lithium nickel cobalt manganese oxide to the lithium phosphate positive electrode material, Salt is the sum of the molar concentrations of the lithium hexafluorophosphate and the lithium bis (fluorosulfonyl) imide in the electrolyte by taking mol / L as the unit, and the sum of the molar concentrations of the lithium hexafluorophosphate and the lithium bis (fluorosulfonyl) imide in the electrolyte is the sum of the molar concentrations of the lithium hexafluorophosphate and the lithium bis (fluorosulfonyl) imide. Add is the mass ratio of the positive electrode film-forming agent to the negative electrode film-forming agent. When the ternary material is doped in the lithium manganese iron phosphate or the lithium iron phosphate, the proportion of the positive and negative electrode film-forming agents and the proportion of the heat-resistant high-lithium salt can be adjusted according to the mixing proportion of the lithium manganese iron phosphate and the lithium iron phosphate, so that the cycle performance of the battery is improved.

The invention provides a preparation method for regenerating waste lithium iron phosphate into sodium ferric pyrophosphate, and belongs to the technical field of battery material production.The recovery process comprises the steps that a high-grade oxide serves as an oxidizing agent, a waste lithium iron phosphate positive electrode material and a current collector are stripped under the acid or strong alkaline condition, and lithium iron phosphate is oxidized; recovering to obtain iron phosphate containing impurities and a solution containing lithium ions; in the regeneration process, recycling slag obtained in the recycling process is uniformly mixed with a sodium source and a phosphorus source, sintering regeneration is performed to prepare ferric sodium pyrophosphate, conductive carbon in waste lithium iron phosphate is used as a reducing agent, and a high-performance ferric sodium pyrophosphate positive electrode material is obtained without an additional reducing agent; recycled slag obtained in the recycling process mainly comprises high-purity iron phosphate, and the content of impurities can be controlled to be 0.1% or below by controlling the solid-to-liquid ratio, the temperature and the reaction time in the recycling process.

The invention belongs to the technical field of iron phosphate preparation, and discloses an energy-saving control system for iron phosphate preparation based on an energy consumption scheduling model. The system is composed of a data acquisition module, an energy consumption sensing module, a preparation process modeling module, an energy consumption prediction module, an energy-saving scheduling module, an intelligent execution module, a feedback correction module, a man-machine interaction module and a remote operation and maintenance module. The energy consumption sensing module intelligently senses an energy consumption state, the preparation process modeling and energy consumption prediction module accurately predicts energy consumption, the energy-saving scheduling module generates an optimal scheduling strategy, the intelligent execution module accurately executes an instruction, and the feedback correction module realizes closed-loop adaptive regulation and control; all the modules cooperatively operate, process parameters are adjusted in real time according to actual working conditions of iron phosphate preparation, energy consumption in the preparation process is remarkably reduced, the energy utilization rate is increased, and energy-saving optimization of iron phosphate preparation is achieved.

The invention provides a low-cost preparation method of high-performance titanium-doped iron phosphate, and relates to the technical field of batteries. The low-cost preparation method comprises the following steps: S1, respectively preparing a phosphoric acid solution, a hydrogen peroxide solution, a phosphorus salt solution and a ferrite solution; s2, adding titanium sulfate into the ferrite solution to obtain an iron-titanium mixed solution; s3, directly adding ammonia water and a hydrogen peroxide solution into the phosphorus salt solution to obtain a phosphorus-oxygen mixed solution; s4, the iron-titanium mixed solution is heated, the phosphorus-oxygen mixed solution is put into the iron-titanium mixed solution, and slurry A is obtained; s5, obtaining a filter cake A; s6, adding pure water and a phosphoric acid solution, and heating to obtain slurry B; s7, obtaining anhydrous iron phosphate; the synthesized iron phosphate is compact and compact in morphology, internal pore channels of primary particles are still rich, the compaction density of the lithium iron phosphate material obtained through grinding and sintering reaches 2.613 g / cc, the 0.1 C discharge capacity can still reach 156.35 mAh / g, and the 1C discharge capacity reaches 131.47 mAh / g.

The invention provides a lithium manganese iron phosphate battery. The battery comprises a positive pole piece, a negative pole piece and a non-aqueous electrolyte, the positive pole piece comprises a positive active material and a positive active coating arranged on at least one surface of the positive active material; the positive electrode active material comprises lithium manganese iron phosphate LiMnxFe1-xPO4 coated with a carbon coating layer, and x is more than or equal to 0.5 and less than or equal to 0.8; the negative pole piece comprises a negative active material and a negative active coating arranged on at least one surface of the negative active material; the battery satisfies the following relational expressions: 4.5 < = (a / 20 + d) / (b + c) < = 12.8; a is a coated diaphragm resistor of the positive pole piece; b is the compaction density of the positive pole piece; c is the mass percentage content of vinylene carbonate in the positive electrode slurry; and d is the mass percentage content of the lithium bis (fluorosulfonyl) imide in the non-aqueous electrolyte. By optimizing the composition of the lithium ion battery, the low-temperature discharge performance of the battery is improved, and meanwhile, the high-temperature cycle performance is considered.

The invention relates to a preparation method and application of high-compaction-density composite sodium ferric phosphate. The preparation method comprises the following steps: weighing a sodium source, an iron source and a phosphorus source according to a stoichiometric ratio of [xNa + (a-x) A]: [yFe + (b-y) B]: P = a: b: (c + 2), mixing and dispersing the iron source, the sodium source, the phosphorus source and a chelating agent into pure water, reacting for a period of time at a certain temperature, transferring into a sand mill for grinding, adding a dispersing agent, cane sugar, the dopants A and B, and obtaining slurry F after grinding; and carrying out spray drying on the slurry F to obtain powder K. The powder K is transferred to a tubular furnace, and the oxygen content is 1t under the N2 protective atmosphere; and calcining at the temperature of 450-600 DEG C under the pressure of 50 ppm, and then carrying out air jet pulverization to obtain sodium ferric pyrophosphate positive electrode material powder with high compaction density and a molecular formula of (NaxAa-x) (FeyBb-y) (PO4) cP2O7. When the product is used, the compaction density is high, the dynamic performance of the material is enhanced, the thermal stability and chemical stability of the material are improved, and the electrochemical performance is good.

Provided are a lithium manganese iron phosphate material and a preparation method therefor, a positive electrode sheet, and a lithium ion battery. The lithium manganese iron phosphate material comprises a core and a coating layer that coats the surface of the core. The chemical formula of the material of the core is LiaMnbFecMdPO4, wherein M comprises at least one element among magnesium, calcium, strontium, cobalt, titanium, zirconium, molybdenum, vanadium, niobium, nickel, scandium, chromium, copper, zinc, beryllium, lanthanum and aluminum. The coating layer is formed by sintering a carbon source, and the carbon coating layer comprises graphitized carbon.

The invention provides a positive active material and a preparation method thereof, a positive plate and a battery, and belongs to the technical field of batteries, the positive active material comprises a ternary material and lithium manganese iron phosphate; wherein the mass of the lithium manganese iron phosphate is A, the total mass of the ternary material and the lithium manganese iron phosphate is B, and A / B is more than 0 and less than 50%; the lithium manganese iron phosphate is of a hollow spherical structure, and the median particle size of the lithium manganese iron phosphate is 0.5-3 microns. According to the positive electrode active material provided by the embodiment of the invention, the cost of the positive electrode active material can be reduced, relatively high rate capability, cycle performance and energy density are considered, and the comprehensive electrochemical performance is improved.

The invention relates to the technical field of electrochemistry, and particularly discloses a positive pole piece, an electrochemical device comprising the positive pole piece and an electric device. The positive pole piece comprises a first active material with a particle size of 4-20 [mu] m and a second active material with a particle size of 200-600 nm, the first active material comprises lithium manganese iron phosphate with the manganese content of m%, the second active material comprises lithium manganese iron phosphate and / or lithium iron phosphate with the manganese content of n%, and m and n meet the condition that m-n is larger than or equal to 15 and smaller than or equal to 85. According to the invention, by controlling the particle size distribution in the positive electrode active material and the manganese content relationship, the electrochemical device containing the positive electrode plate has excellent fast charging performance and energy density.

The invention discloses a preparation method and application of low-magnetic foreign matter and high-compaction lithium iron phosphate. The preparation method comprises the following steps: S1, mixing a lithium source, an iron source, a phosphorus source, a carbon source and water, grinding, drying, sintering in an inert atmosphere at 770-830 DEG C, and cooling to obtain a lithium iron phosphate material; and S2, placing the lithium iron phosphate material obtained in the step S1 in an inert atmosphere for secondary sintering, controlling the oxygen content to be less than 5ppm, and controlling the secondary sintering temperature to be 700-830 DEG C, so as to obtain the low-magnetic foreign matter and high-compaction lithium iron phosphate. The content of magnetic foreign matter iron phosphide in the prepared low-magnetic foreign matter and high-compaction lithium iron phosphate is lower than 50 ppb, the compaction density reaches 2.75 cm < 3 > / g or above, the 0.1 C discharge specific capacity is 163 mAh / g or above, and the 1C discharge specific capacity is 150 mAh / g or above.

The invention discloses a method for preparing a composite positive electrode material by using a waste battery, and belongs to the technical field of battery recovery. The method comprises the following steps: discharging, disassembling and sorting a waste lithium iron phosphate battery to obtain a positive plate, carrying out water treatment, separating from an aluminum foil to obtain a waste lithium iron phosphate sheet, adding sodium hypochlorite, tetraethoxysilane, deionized water and hydrochloric acid, stirring to obtain SiO2-coated iron phosphate precipitate particles and a lithium-containing solution, adding sodium hydroxide into the lithium-containing solution to adjust the pH value, and carrying out solid-liquid separation to obtain the lithium-ion battery cathode material. Adding sodium carbonate, heating and drying to obtain lithium carbonate precipitate. And adding a carbon source and alcohol into the SiO2-coated iron phosphate precipitate particles and lithium carbonate, carrying out ball milling, taking out, drying, and calcining in a protective atmosphere to obtain the positive electrode composite material. Compared with the prior art, according to the prepared positive electrode composite material, material particles contain a lithium silicate network, so that the specific discharge capacity of a battery material is effectively improved. The method is simple in process and suitable for comprehensive utilization of waste batteries.

The present application belongs to the technical field of battery materials. Disclosed are a doped iron (III) phosphate, a method for preparing same, and use thereof. The chemical formula of the doped iron (III) phosphate is (MnxFe1−x)@FePO4·2H2O, wherein 0<x<1. According to the present application, ferromanganese phosphate is used as a template agent for preparing the doped iron (III) phosphate. The doped iron (III) phosphate is regular in morphology and good in fluidity, facilitates washing and conveying, and can improve the electrochemical performance of the subsequently prepared LiFePO4 / C. When the doping amount of Mn is 11000 ppm, the specific discharge capacity of LiFePO4 / C at room temperature at 0.1 C rate can reach 165 mAh / g; the retention rate of the discharge capacity of 1000 cycles at 45° C. at 1 C rate can reach 97.4%; and at a low temperature of −15° C. the specific discharge capacity at 0.1 C rate is still 134 mAh / g.

The invention discloses a salt leaching-extraction method for recycling lithium iron phosphate and ternary lithium battery powder through cascade circulation, and belongs to the technical field of waste lithium battery recycling. According to the method, ferric salt is adopted as a leaching agent, a circulation mechanism is constructed through iron ion valence state conversion, and cascade leaching circulation of waste lithium iron phosphate and nickel cobalt lithium manganate battery powder is achieved. A concentrated enrichment liquid containing lithium, nickel, cobalt and manganese, iron phosphate and a graphite crude product can be obtained through multiple leaching cycles. In the leaching circulation process, a mixed solvent is developed as an extraction agent of iron ions, and after extraction and hydrochloric acid reverse extraction are carried out on a leaching solution containing iron salt, the leaching agent and the extraction agent can be recycled. According to the method, the valuable metal in the waste battery powder is efficiently leached under the milder reaction condition, consumption of chemicals such as acid and alkali, a leaching agent, an oxidizing agent and an extracting agent is effectively reduced through research of a circulation mechanism, the cost is remarkably reduced, and good environmental benefits and economic benefits are achieved.

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 relates to the technical field of battery positive electrode materials, and provides a lithium iron phosphate positive electrode material and a preparation method thereof. The lithium iron phosphate positive electrode material has the characteristic of high energy density, the proportion of iron phosphide impurities in the total mass of the lithium iron phosphate positive electrode material is 0.001-0.008 PPM, the compaction density under the pressure of 3T is 2.68-2.8 g / cm < 3 >, the powder resistivity is 8-15 omega.cm, the 0.1 C discharge capacity is 161-163 mAh / g, the 0.1 C charge-discharge efficiency is 98.5-100%, and the 1C discharge capacity is 145-148 mAh / g. The preparation process is simple and safe, low in cost and high in stability. The content of iron phosphide impurities in a final lithium iron phosphate product can be regulated and controlled by regulating and controlling the phosphorus-iron ratio of the iron phosphate precursor and the ratio of the carbon source to the iron phosphate precursor in two-time burdening and controlling the sintering temperature in cooperation with secondary sintering, and the high-energy-density lithium iron phosphate positive electrode material is obtained.

The invention discloses a preparation method and application of an amorphous nickel-cobalt-iron phosphate anode catalyst, and belongs to the technical field of alkaline water electrolysis hydrogen production, the preparation method comprises the following steps: (1) dissolving transition metal salt in a solvent, and stirring to obtain a metal salt solution; (2) dissolving phosphate in a solvent, and stirring to obtain a phosphate solution; and (3) adding the phosphate solution into the metal salt solution for reaction, washing with deionized water and ethanol, centrifugally separating, and drying to obtain the amorphous nickel-cobalt-iron phosphate anode catalyst. According to the preparation method and application of the amorphous nickel-cobalt-iron phosphate anode catalyst, process safety improvement and environmental friendliness optimization are achieved through an all-water-phase green synthesis system, the obtained catalyst shows excellent performance in an AEM electrolytic cell, the cell voltage is only 1.87 V under the current density of 2 A / cm, and the method has remarkable industrial application prospects.

The invention discloses a gradient composite coated modified lithium manganese iron phosphate positive electrode material and a preparation method thereof, and belongs to the technical field of positive electrode materials. An LMFP precursor is pretreated through a citric acid-ethanol mixed solution, an active crystal face is exposed, and then a three-dimensional gradient coating structure of a polydopamine (PDA) chemical bonding layer, an MXene nanosheet middle layer and a polyaniline (PANI) conductive outer layer is sequentially constructed on the surface of the material, so that the electronic conductivity of the lithium manganese iron phosphate positive electrode material is increased to 10 <-3 > S / cm magnitude, and the performance of the lithium manganese iron phosphate positive electrode material is improved. The capacity retention ratio (1C) of 500 cycles is larger than 90%, the coating layer is not prone to falling off, and meanwhile dissolution of manganese ions is effectively inhibited.

The invention provides a positive pole piece. The positive pole piece comprises a positive current collector, a first material layer arranged on at least one surface of the positive current collector, and a second material layer arranged on the surface, far away from the positive current collector, of the first material layer, the first material layer comprises an active material A and an active material B; the second material layer comprises an active material C; the active material A is selected from lithium iron phosphate and / or lithium manganese iron phosphate; the active material B is selected from one or more of nickel cobalt lithium manganate, lithium cobalt oxide, lithium manganate and nickel lithium manganate; the active material C is selected from one or more of nickel cobalt lithium manganate, lithium cobalt oxide, lithium manganate and nickel lithium manganate; by using the positive pole piece provided by the invention, the interface impedance of the pole piece can be reduced, the problem that the expansion rates of different areas of the pole piece are different is solved, and the cycle life of the battery is prolonged.

The invention discloses a method for regenerating waste lithium iron phosphate into a lithium manganese iron phosphate positive electrode material under assistance of element doping. According to the method, the waste lithium iron phosphate is successfully regenerated into the lithium manganese iron phosphate material with excellent performance through solid-phase sintering and element doping. Compared with a traditional repairing and regenerating method, the method has the advantages that upgrading and regenerating of the waste lithium iron phosphate are realized, and the market competitiveness of regenerated products is improved. Compared with other methods, the method does not need an acid leaching step, and the recovery process is simpler and more environment-friendly. And an element doping modification means is introduced, so that the performance of the regenerated lithium manganese iron phosphate material is further improved. The invention aims to provide a green, efficient and high-valued method for upgrading and regenerating the waste lithium iron phosphate positive electrode material into the lithium iron manganese phosphate positive electrode material with industrial application prospects.

In one aspect, a preparation method for ferric phosphate includes the following steps: (a) feeding a ferrous sulfate solution and a phosphate solution including hydrogen peroxide simultaneously into a first reactor for mixing and reacting to obtain nucleated ferric phosphate; wherein a molar ratio of iron element to phosphorus element in the feeding process is 1:1, and a stirring speed is 500-600 r / min; (b) discharging the nucleated ferric phosphate to a second reactor for growth to obtain amorphous ferric phosphate slurry, and post-processing the amorphous ferric phosphate slurry to obtain the high tap density ferric phosphate; wherein a stirring speed is 120-150 r / min. The first reactor is a small-volume reactor, and the second reactor is a large-volume reactor.