4741results about "Phosphorus compounds" patented technology

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 discloses a chitosan modified lithium iron phosphate and carbon composite positive electrode material and a preparation method thereof.The preparation method comprises the steps that 1, lithium hydroxide, phosphoric acid and ferrous sulfate heptahydrate are mixed to prepare a uniform and stable solution, and a lithium iron phosphate precursor is prepared through a solvothermal method; step 2, dissolving chitosan in an acetic acid aqueous solution, and magnetically stirring under a water bath condition until the chitosan is completely dissolved to prepare a chitosan solution; and 3, adding the lithium iron phosphate precursor into a chitosan solution, uniformly mixing, carrying out ball milling and freeze drying, and carrying out high-temperature carbonization treatment in an inert gas to obtain the chitosan modified lithium iron phosphate and carbon composite positive electrode material. The method is simple to operate, low in cost and uniform in product particle size distribution.

The invention provides a method for preparing a high-performance lithium manganese iron phosphate positive electrode material based on a manganese iron phosphate precursor, and relates to the technical field of batteries. A method for preparing a high-performance lithium manganese iron phosphate positive electrode material based on a manganese iron phosphate precursor comprises the following steps: S1, mixing a phosphorus source, an iron source and a manganese source in a water medium, adding a surfactant, and carrying out ball milling, drying and sintering to obtain the manganese iron phosphate precursor; and S2, mixing the manganese iron phosphate precursor, a lithium source, a carbon source, a doping agent, an auxiliary agent and deionized water, and carrying out ball milling, drying and sintering to obtain the lithium manganese iron phosphate positive electrode material. The method can improve the surface / interface stability while improving the surface conductivity of the material, thereby prolonging the cycle life of the battery and improving the charge-discharge capacity of the battery.

This invention discloses a method for leaching lithium iron phosphate mixed powder with iron salts and recovering all components, belonging to the field of battery recycling. The invention uses an iron salt solution to leach the mixed powder, obtaining a lithium-containing leachate and leaching residue. Ferrous ions in the leachate are regenerated into ferric iron through acidification and oxidation, and recycled for leaching the next batch of mixed powder. After reaching a preset number of cycles, the leachate is used for re-leaching multiple batches of leaching residue to improve the lithium leaching rate. Ultimately, a enriched solution containing Li, Fe, Cu, and Al and graphite-containing iron phosphate residue are obtained. Copper is recovered from the enriched solution through iron powder replacement, and a high-purity lithium chloride solution is obtained through extraction and separation, while ferric chloride (recycled) and aluminum chloride crystals are also recovered. The leaching residue is treated with hydrochloric acid to obtain regenerated graphite, and the pH is adjusted with alkali to obtain high-purity iron phosphate. This method achieves full component recovery under mild conditions, reducing separation steps and chemical consumption through a "leaching-regeneration-leaching" cycle mechanism, thus achieving both environmental and economic benefits.

The invention discloses an intelligent gradient extraction process and method for nutritional ingredients in yak bone marrow, and belongs to the technical field of bioactive substance extraction. The extraction method comprises the following four steps: gradient pressure supercritical degreasing, double-enzyme synergistic gradient enzymolysis, acid concentration gradient demineralization and temperature gradient gelatin extraction, and through the process coupling design of gradient pressure degreasing, buffer enzymolysis, graded acidolysis and membrane separation of gelatin, the high yield of the product in the previous stage is ensured; active structures of follow-up components are reserved to the greatest extent. Meanwhile, a sensing-decision-execution closed-loop system is constructed, real-time data sources such as NIR moisture sensing, online OPA detection and XRD in-situ analysis are integrated, technological parameters are dynamically adjusted through a multi-objective optimization algorithm, and global optimization of the yield, the purity and the energy consumption is achieved.

The present application provides a lithium iron phosphate composite material, a preparation method and use. The lithium iron phosphate composite material includes a core and a shell coated on the core, in particular, the core is Li6MnO4, and the shell is carbon-coated lithium iron phosphate. The lithium iron phosphate composite material provided by the present application adopts Li6MnO4 as the positive electrode lithium supplement material, and solves problems of active lithium loss and capacity depletion under high-rate charge and discharge of lithium iron phosphate positive electrode, thereby improving the rate performance of the lithium iron phosphate materials and the cycle life of batteries at high rates.

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 a production method of ferrous dihydrogen phosphate, which comprises the following steps of: changing an iron source of iron-process iron phosphate from traditional iron blocks or iron powder into oxide scale, compounding phosphoric acid and sulfuric acid into mixed acid, and controlling the granularity of the oxide scale and the components and acidity of the mixed acid to solve the problems of dissolution and passivation of the oxide scale. According to the method, iron oxide scale can be better dissolved, the residual problem of ferric ions is solved by reducing excessive iron blocks or iron powder, undissolved impurities such as carbon, silicon and iron are removed by filtering, and finally, the stability problem of a reaction system is solved by adjusting the pH value of the system through industrial phosphoric acid and pure water, so that a ferrous dihydrogen phosphate solution required for producing iron phosphate is obtained. The production cost of an iron source required by iron phosphate is greatly reduced, other impurities are not contained, and mixed acid-containing filtrate and washing water generated in the production process can be recycled through an evaporation device.

The invention provides a lithium iron phosphate-based positive electrode material and a preparation method thereof, a positive plate and a battery, the lithium iron phosphate-based positive electrode material comprises a lithium iron phosphate matrix and a carbon material existing on the surface of the lithium iron phosphate matrix, and the lithium iron phosphate-based positive electrode material comprises mesopores and macropores. The conductivity and the ion transmission performance of the lithium iron phosphate-based positive electrode material can be both improved, and the energy density and the rate capability of the battery are improved.

The invention relates to the technical field of sludge reduction and resource utilization, in particular to a method for resource utilization of sludge gasification slag. According to the method, municipal sludge gasification slag is smashed and then subjected to acid leaching, acid leaching liquid and acid leaching slag are obtained, iron in the acid leaching liquid is recycled, meanwhile, the acid leaching slag is subjected to alkaline leaching, under the strong alkaline condition, a calcium source is added into alkaline leaching liquid, then calcium phosphate sediment can be obtained, and iron in alkaline leaching separation liquid is recycled; a calcium ion solution can be generated in the processes of recovering iron in the pickle liquor and refining calcium phosphate, and the obtained calcium ion solution can be used as a calcium source for comprehensive utilization. The method disclosed by the invention can be used for realizing extraction and resource utilization of phosphorus, iron, aluminum and calcium in the sludge gasification slag, and has important significance on environmental protection and resource saving.

The preparation method comprises the following steps: S1, preparing a phosphoric acid solution, a hydrogen peroxide solution, a Ti salt, a phosphor salt solution and a ferrite solution; s2, Ti salt and the ferrite solution are mixed, and a titanium iron salt solution is obtained; mixing the phosphoric acid solution and the phosphorus salt solution to obtain a phosphorus source solution; s3, adding the titanium iron salt solution into a reaction kettle, and adding the hydrogen peroxide solution; s4, adding the phosphorus salt solution into the reaction kettle to obtain yellow slurry; s5, after the color of the slurry is heated to be white, white slurry is obtained; s6, carrying out solid-liquid separation on the white slurry to obtain an iron phosphate dihydrate filter cake; and S7, drying and calcining the iron phosphate dihydrate filter cake to obtain the Ti-doped battery-grade anhydrous iron phosphate. The titanium-doped iron phosphate is firstly prepared by a one-step method, the pH value of the reaction system is controlled by controlling the molar ratio of the iron element to all phosphorus elements in total phosphorus, ammonium phosphate and phosphoric acid in the reaction system, and the retention of the Ti element in the finished product and the regulation and control of the iron-phosphorus ratio in a specified range are ensured.

The invention discloses a process and equipment for synthesizing fluorapatite from wastewater, the equipment comprises a blending tank, a dispensing tank, a crystallization fluidized bed reactor, a reaction tank, a coagulation tank, a flocculation tank, a sedimentation tank, a pH detection device, a lift pump and a control system, fluorine-containing sewage and phosphorus-containing sewage are mixed in the blending tank, so that the molar ratio of fluorine to phosphorus is 0.34-0.4; the method comprises the following steps: adding fluorapatite into a reaction tank, adjusting the pH value to 7.5-8.5, pumping the fluorapatite and lime slurry into a crystallization fluidized bed reactor according to a calcium-phosphorus molar ratio of (3-3.5): 1, carrying out a crystallization reaction, naturally airing the generated fluorapatite crystals, carrying out a reaction on crystallization treatment water and the lime slurry in the reaction tank to remove fluorine and phosphorus, carrying out coagulation, flocculation and precipitation treatment, and discharging the effluent after reaching the standard. The high-quality fluorapatite product is prepared from the fluorine-containing sewage and the phosphorus-containing sewage, so that the preparation cost is low, and resourceful treatment of the fluorine-containing sewage and the phosphorus-containing sewage is realized.

The invention relates to the technical field of lithium ion batteries, in particular to a composite lithium-rich manganese-based positive electrode material and a preparation method and application thereof. The composite lithium-rich manganese-based positive electrode material is of a three-layer structure and sequentially comprises a lithium-rich manganese-based oxide positive electrode material matrix, a first coating layer and a second coating layer from inside to outside, the first coating layer is a mixture of halide solid electrolyte and lithium-containing oxide; and the second coating layer is an oxide solid electrolyte. The conductivity of a contact interface with a positive electrode material can be improved, the resistance is reduced, the moisture absorption degradation of halide is inhibited, the packaging difficulty is reduced, and the cycle performance of the halide-added solid electrolyte after moisture absorption is improved.

A lithium manganese iron phosphate cathode material, including a first lithium manganese iron phosphate particle and a second lithium manganese iron phosphate particle. A molar ratio of Mn to Fe in the first lithium manganese iron phosphate particle is greater than or equal to 1. A molar ratio of Mn to Fe in the second lithium manganese iron phosphate particle is smaller than or equal to the molar ratio of Mn to Fe in the first lithium manganese iron phosphate particle. A particle size of the first lithium manganese iron phosphate particle is smaller than or equal to a particle size of the second lithium manganese iron phosphate particle. A preparation method of the lithium manganese iron phosphate cathode material and an application thereof are provided. The first precursor, having a manganese content greater than or equal to that of iron, inhibits crystal growth during sintering, resulting in a smaller particle size. The second precursor, having a manganese to iron ratio smaller than or equal to the ratio in the first precursor, promotes crystal growth during sintering, resulting in a larger particle size. This results in a particle size grading between large particles and small particles, improves the spatial utilization of particle packing, and enhances the compaction density and volumetric capacity of the lithium manganese iron phosphate cathode material.

The invention discloses a reaction kettle device for synthesis of an iron phosphate material, and particularly relates to the technical field of synthesis of battery materials, and the device comprises a kettle body, a driving motor, a transmission disc and a turbo-type paddle. A sealing cover is arranged at the top of the kettle body, a driving motor is connected with a rotating shaft, an anchor blade is arranged below the rotating shaft, and the bottom realizes turbine blade lifting and sleeve guide limiting through transmission of a piston cavity and compressed gas; and a ratchet wheel on the outer wall of the rotating shaft is meshed with a pawl in the transmission disc in a one-way mode, and intermittent wall scraping is achieved. According to the device, dead angles are broken through synergistic stirring of the double blades, the mixing uniformity and the reaction rate are improved, materials adhering to the wall are efficiently removed through intermittent wall scraping, the stable reaction environment is guaranteed through multiple sealing, the structure is flexible to adjust, maintenance is convenient and fast, efficient and high-quality synthesis of the iron phosphate material can be achieved, and the device is suitable for industrial large-scale production.

A kind of preparation method of high compaction lithium iron phosphate of multistage gradation, including step one: iron source, phosphorus source, lithium source, carbon source, dispersing agent, element dopant and solvent are dispersed according to proportion, slurry after dispersion is divided into A, B, C three slurry according to proportion, three slurry are grinded respectively, and then are respectively carried out spray drying;Step two: three spray materials are respectively pre-sintered at different temperatures, and pre-sintered material is respectively crushed;Step three: the material after pre-sintering is mixed to realize multistage particle gradation.Certain mass ratio of carbon source and pre-crushed material are dry mixed;Step four: after secondary sintering, crushing and magnetic removal process, the multistage gradation high compaction lithium iron phosphate positive material is obtained.The present application realizes particle gradation of once sintered material, secondary carbon coating and sintering strengthening by grading particle size design, and realizes the collaborative improvement of compaction density and specific capacity of lithium iron phosphate positive material.

The invention relates to the technical field of electrode materials, and discloses a preparation method of a lithium iron manganese phosphate material and a lithium ion battery. The lithium iron manganese phosphate material is prepared by the following steps: performing in-situ growth in a cavity of polyethylene glycol-sucrose hybrid aerogel with a three-dimensional porous network structure to form a manganese iron phosphate precursor; the hybrid aerogel can control excessive agglomeration and disordered growth of ferromanganese phosphate precursor particles and avoid particle agglomeration, so that the finally formed lithium ferromanganese phosphate material particles are finer and more uniformly distributed, and an amorphous carbon-aluminum layer is formed during later calcination, so that the performance of the material is improved. The surface of lithium manganese iron phosphate particles is tightly coated with the composite material, electron transmission can be accelerated, particle pulverization can be reduced, meanwhile, corrosion of corrosive components in electrolyte can be inhibited, interface side reactions such as transition metal ion dissolution can be reduced, and finally the conductivity and cycling stability of the lithium ion battery are remarkably improved.

The invention provides a battery monomer, a battery device and a power utilization device. The battery monomer comprises a carbon-coated lithium iron phosphate material. By regulating and controlling the relative proportion of the specific surface areas of carbon structures with different micromorphologies in the surface layer of the carbon-coated lithium iron phosphate material, specifically, the carbon-coated lithium iron phosphate material disclosed by the invention has a carbon coating factor eta, and when eta is more than or equal to 0.81 and less than or equal to 0.95, the lithium iron phosphate material has high-quality carbon coating; the lithium iron phosphate material capacity exertion is facilitated, the pole piece dehydration efficiency is remarkably improved, and the prepared battery monomer has excellent energy density, cycle performance and processing performance.

The present invention belongs to the technical field of battery materials, and particularly relates to a composite phosphate-based positive electrode material, and a preparation method therefor and the use thereof. The composite phosphate-based positive electrode material comprises a phosphate-based active core, wherein the outer surface of the phosphate-based active core is sequentially coated with a carbon coating layer, a nitrogen-doped carbon coating layer and a nitrogen-phosphorus co-doped carbon coating layer from inside to outside, wherein the carbon coating layer can improve the electronic and ionic conductivity of the composite positive electrode material, and optimize the particle size and morphology of the composite positive electrode material. The nitrogen-doped carbon coating layer improves the consistency and integrity of coating; and nitrogen-atom-doped carbon further enhances the electronic conductivity and lithium-ion diffusion of the carbon coating layer. Electron-rich clouds of P and N atoms in the nitrogen-phosphorus co-doped carbon coating layer can provide a rich conductive network, mutual contact is formed among different particles to form a series network, thus promoting the interfacial electron transport of the composite material during a charging and discharging process, and improving the cycling and rate performance of the composite phosphate-based positive electrode material during the charging and discharging process.

The invention relates to the field of positive electrode materials, in particular to a lithium manganese iron phosphate / carbon fiber composite positive electrode material and a preparation method thereof, which are used for solving the problems of poor electronic conductivity of lithium manganese iron phosphate and the like. The preparation method comprises the following steps: firstly, carrying out graft modification and ZrO2 film coating on carbon fibers, and then compounding the modified carbon fibers with lithium iron manganese phosphate to obtain the lithium iron manganese phosphate / carbon fiber composite positive electrode material. The lithium manganese iron phosphate / carbon fiber composite positive electrode material can greatly improve the electronic conductivity and improve the rate capability; active substance dissolution and side reaction can be inhibited, and the cycling stability is improved; a lithium ion diffusion channel can be optimized, and the ion conduction efficiency is improved; the electrode mechanical performance can be enhanced, and the structural reliability is improved. Meanwhile, the advantages of all the components are exerted, and finally the electrochemical performance and structural stability of the composite positive electrode are remarkably improved.

The invention discloses a lithium iron manganese phosphate positive electrode material and a preparation method thereof, and belongs to the technical field of lithium ion batteries, the lithium iron manganese phosphate positive electrode material at least comprises lithium iron manganese phosphate particles and a coating layer coating the lithium iron manganese phosphate particles; the raw material of the coating layer comprises an aluminum fluoride embedded poly (ethylenedioxythiophene)-lithium polystyrene sulfonate compound. And the coating layer can be used as a physical barrier to form dynamic interface protection, so that dissolution of manganese and erosion of electrolyte are directly inhibited, and side reaction between the electrolyte and the positive electrode material is reduced. Meanwhile, a more flexible transmission channel is provided for lithium ions and electrons, the conductivity of the positive electrode material is enhanced while the transmission efficiency of the lithium ions is improved, and the lithium manganese iron phosphate positive electrode material with stable structure, high rate capability and cycling stability is obtained.

In order to solve the problems that an existing positive electrode material is unstable in structure and low in energy density, 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 cobalt oxide of a layered structure, the chemical formula of the lithium cobalt oxide is Li < 1-alpha-beta > Na < alpha > (Mg < gamma > Ti < delta > Co < 1-gamma-delta >) O2, alpha is smaller than or equal to 0.005, and beta is 0.02-0.05; gamma is equal to 0.002 to 0.004, delta is equal to 0.001 to 0.003, and gamma + delta is equal to 0.003 to 0.006.

The invention belongs to the technical field of batteries, and discloses a carbon-coated modified lithium manganese iron phosphate positive electrode material and a preparation method and application thereof, and the carbon-coated modified lithium manganese iron phosphate positive electrode material comprises carbon-coated modified lithium manganese iron phosphate positive electrode material particles, the carbon-coated modified lithium manganese iron phosphate positive electrode material particle comprises a lithium manganese iron phosphate core, a first carbon coating layer and a second carbon coating layer, wherein the first carbon coating layer is positioned between the lithium manganese iron phosphate and the second carbon coating layer; the graphitization degree of the first carbon coating layer is greater than that of the second carbon coating layer. The carbon-coated modified lithium manganese iron phosphate positive electrode material has relatively high conductivity, compaction density and the like, and a battery using the carbon-coated modified lithium manganese iron phosphate positive electrode material has relatively high charge-discharge rate, excellent energy density, excellent capacity and the like.

The invention provides equipment and a process for leaching battery-grade lithium phosphate by using waste lithium iron phosphate, and relates to the technical field of resource recovery and battery material preparation, the equipment comprises a support frame, a heating seat, a leaching tank, a driving mechanism and a discharging mechanism; the heating base is installed in the middle of the interior of the supporting frame, the leaching tank is installed on the inner wall of the heating base, an installation cover is installed on the top of the leaching tank in a sealed mode, a main material pipe and an auxiliary material pipe are installed on the two sides of the leaching tank respectively, and a discharging pipe is installed at the bottom end of the leaching tank; the driving mechanism comprises a mounting seat and a motor, the mounting seat is fixedly arranged at the inner bottom of the mounting cover, and the motor is mounted at the top of the mounting seat. According to the scheme, caked industrial-grade sodium phosphate or sodium hydroxide can be crushed into fine particles by adopting rotary grinding, and a reagent can be uniformly dispersed into a purification solution by matching with rotary dispersion blanking, so that the pH of a system and the concentration of sodium phosphate are integrally stable, local reaction abnormity is avoided, and more stable preparation of battery-grade lithium phosphate is ensured.

The invention discloses a preparation method of a lithium iron phosphate positive electrode material, three iron sources with different forms and different particle sizes participate in preparation of the lithium iron phosphate positive electrode material, and gradation is formed to improve the compaction density and rate capability of the material. The EDTMPA reduces the viscosity of the slurry, is anchored on the surface of FePO4 particles through strong adsorption, inhibits particle aggregation through steric hindrance and electrostatic repulsion effect, and introduces hydrophilic groups to enhance wettability, reduce the viscosity of the system, optimize dispersion stability, accelerate particle crushing and refining, reduce the particle size and shorten the grinding time; in the sintering process, a reducing agent is generated through pyrolysis to inhibit too fast oxalic acid decomposition to cooperate with the generated reducing gas, Fe < 3 + > is completely reduced, the reduction temperature is reduced to inhibit grain growth, and the grading effect between large and small particles is improved; in addition, an N-doped carbon coating layer is formed through high-temperature cracking, pores are filled with residual carbon generated through decomposition of ferrous oxalate, the coating density is improved, the carbon-coated graphitization degree is improved, and then the electronic conductivity and the rate capability of the material are improved.

The invention provides a preparation method of grain size grading iron phosphate and high compaction type lithium iron phosphate. Removing impurities from the titanium dioxide byproduct ferrous sulfate, and filtering to obtain a purified ferrous sulfate base solution; the method comprises the following steps: reacting phosphoric acid with ammonia water to prepare ammonium phosphate solutions with different reaction pH values and phosphorus molar concentrations, respectively mixing the ammonium phosphate solutions with a certain amount of hydrogen peroxide, and sequentially adding an iron source, a first phosphorus salt solution, a second phosphorus salt solution and a third phosphorus salt solution into a tubular reactor for reaction to obtain iron phosphate slurry; and sequentially converting, filtering, washing, drying and calcining the completely reacted slurry to finally prepare the anhydrous iron phosphate. According to the invention, a mode of controlling solution nucleation and growth is adopted, nucleation and growth rates are controlled by preparing phosphorus salt solutions with different concentrations, size grading of precursor particles is directly realized in a synthesis reaction section, and slurry grading uniformity is further realized through aging crystal transformation. Lithium iron phosphate prepared from the iron phosphate precursor has high compaction density.

The invention provides a battery monomer, a battery device and a power utilization device. The battery monomer comprises a carbon-coated lithium iron phosphate material. By regulating and controlling the relative proportion of the specific surface areas of carbon structures with different micromorphologies in the surface layer of the carbon-coated lithium iron phosphate material, specifically, the carbon-coated lithium iron phosphate material disclosed by the invention has a carbon coating factor eta, and when eta is more than or equal to 0.81 and less than or equal to 0.95, the lithium iron phosphate material has high-quality carbon coating; the lithium iron phosphate material capacity exertion is facilitated, the pole piece dehydration efficiency is remarkably improved, and the prepared battery monomer has excellent energy density, cycle performance and processing performance.

The present application relates to the technical field of battery materials, and provides iron phosphate having low sulfur content and a high iron-phosphorus ratio, a preparation method therefor, and a use thereof. The preparation method for the iron phosphate having low sulfur content and a high iron-phosphorus ratio comprises: providing amorphous iron phosphate; adding water and phosphoric acid into the amorphous iron phosphate for slurrying treatment, and then heating and aging to obtain an aged slurry; carrying out slurry washing and filter pressing on the aged slurry to obtain a first filter cake; adding water and a first pH regulator into the first filter cake for slurry washing to obtain a first slurry having a pH value range of 3.0-5.0, and carrying out filter pressing on the first slurry to obtain a second filter cake; and rinsing, drying and calcining the second filter cake to obtain iron phosphate having low sulfur content and a high iron-phosphorus ratio. The present application facilitates preparation of iron phosphate having low sulfur content, a high iron-phosphorus ratio, and a large specific surface area. The iron phosphate can be used for preparing lithium iron phosphate having good electrochemical performance, and the lithium iron phosphate can be further used for preparing a positive electrode sheet and a secondary battery having good electrochemical performance.

The invention discloses a lithium manganese iron phosphate material prepared by taking lithium iron phosphate as a template agent as well as a preparation method and application of the lithium manganese iron phosphate material. Specifically, lithium iron phosphate is taken as a template agent, other iron sources, manganese sources, lithium sources, phosphorus sources and carbon sources are added, high-energy ball milling mixing is carried out in water or an organic solvent, rheological phase reaction is carried out, and the surface of the lithium iron phosphate is uniformly coated with the raw materials. And then drying, pre-calcining, secondary carbon coating and high-temperature calcining are carried out, and bulk phase diffusion and epitaxial growth of the raw materials are synchronously carried out on the surface of the lithium iron phosphate by utilizing a solid phase diffusion-epitaxial growth coupling mechanism, so that the lithium iron manganese phosphate material is finally obtained. The lithium iron manganese phosphate prepared by taking lithium iron phosphate as a template agent and matching with other iron sources has the characteristic of manganese element concentration gradient distribution, and meanwhile, nanoscale particle refinement is realized. The secondary battery prepared by taking the lithium manganese iron phosphate as the positive electrode material has excellent electrochemical performance and cycling stability.

Provided is a semiconductor nanoparticle complex in which a ligand is coordinated to a surface of a semiconductor nanoparticle. The semiconductor nanoparticle includes In and P, the ligand includes a mercapto fatty acid ester represented by the following general formula, and the mercapto fatty acid ester has an SP value of 9.30 or less. General formula: HS—R1—COOR2 (where R1 is a C1-11 hydrocarbon group and R2 is a C1-30 hydrocarbon group). The present invention can provide a semiconductor nanoparticle complex that keeps high fluorescence quantum yield before and after purification.