4374 results about "Lithium iron phosphate" patented technology

The invention relates to a method for preparing a lithium iron phosphate / carbon composite material of a lithium ion battery, which belongs to the technical field of lithium ion batteries. The method for preparing the lithium iron phosphate / carbon composite material of the lithium ion battery comprises the following steps of: 1) preparing a suspending graphene-dispersed aqueous solution system, namely, crushing graphite to 1 to 5 microns, adding the crushed graphite into distilled water or purified water, adding 0.1 to 5 percent of surfactant, heating with stirring the mixed solution to 180 to 250 DEG C in a sealing way, performing stirring for 2 to 6 hours and reducing the temperature; 2) crushing lithium iron phosphate to the particle size of 1 to 5 microns, adding the crushed lithium iron phosphate into the distilled water or the purified water, adding with stirring 0.01 to 1 percent of coupling agent, performing uniform stirring, adding the graphene-dispersed aqueous solution, and performing stirring and filtration; and 3) vacuum-drying solid powder obtained by the filtration, and calcinating the dried solid powder for 2 to 12 hours to obtain the graphene-coated lithium iron phosphate cathode material. The method has the advantages of simple process, high material performance, high conductivity, high bulk density, high compacted density and the like.

Systems, methods, and articles for a portable power case are disclosed. The portable power case is comprised of at least one battery and at least one PCB. The portable power case has at least one USB port and at least two access ports, at least two leads, or at least one access port and at least one lead. The portable power case is operable to supply power to an amplifier, a radio, a wearable battery, a mobile phone, and a tablet. The portable power case is operable to be charged using solar panels, vehicle batteries, AC adapters, non-rechargeable batteries, and generators. The portable power case provides for modularity that allows the user to disassemble and selectively remove the batteries installed within the portable power case housing.

The invention discloses a lithium iron phosphate positive electrode material, a preparation method thereof and a lithium battery, and relates to the technical field of lithium ion batteries. According to the method, the pressing index of the lithium iron phosphate positive electrode material is tested by adopting a specific method, so that the pressing index meets a specific range, meanwhile, the average circularity of larger particles in a Dv50-Dv100 range meets a proper range, the lithium iron phosphate positive electrode material has better particle movement capability, and the particles can move at a higher speed to be rearranged during pressing, so that the particle size of the lithium iron phosphate positive electrode material is reduced, and the quality of the lithium iron phosphate positive electrode material is improved. Therefore, the positive pole piece with high compaction density can be obtained, the charge-discharge capacity of the battery can be improved, and meanwhile, the particles can be prevented from being broken when being pressed, so that the positive pole piece has good anti-pressure capability. By adopting the lithium iron phosphate positive electrode material provided by the invention, the lithium battery has relatively high energy density and capacity retention ratio.

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 provides a battery monomer, a battery device and a power utilization device. The battery monomer comprises a positive pole piece, an isolating membrane, a negative pole piece and electrolyte, and the positive pole piece, the isolating membrane and the negative pole piece are arranged in a laminated manner; the positive pole piece comprises a positive current collector and a positive active layer arranged on at least one side of the positive current collector, the negative pole piece comprises a negative current collector and a negative active layer arranged on at least one side of the negative current collector, and the positive active layer comprises lithium iron phosphate primary particles; the isolating membrane comprises a base membrane and a bonding layer, the bonding layer is of a porous continuous structure, and the bonding layer is at least arranged on one side, facing the positive electrode active layer, of the base membrane; the electrolyte comprises a first solvent, and the first solvent comprises one or more of dimethyl carbonate and linear carboxylic ester. The battery monomer has relatively good cycle performance.

The invention discloses a lithium iron phosphate battery pack SOE dynamic prediction and life evaluation method and system fused with a P2D model, and relates to the technical field of battery management, and the method comprises the steps: collecting operation data, building a multi-physical field coupled P2D model, carrying out the SOE dynamic prediction based on the P2D model, building a life evaluation model in combination with a performance attenuation mechanism, and optimizing an operation strategy. According to the method, on the basis of historical operation data and real-time state parameters, an SOE dynamic prediction result of the battery pack is generated by using an electrochemical-thermal-mechanical multi-physics field coupled P2D model; and analyzing the prediction result in combination with a long-term performance attenuation mechanism, evaluating the residual life of the battery pack, and outputting an evaluation result. The SOE prediction precision is improved, the performance change rule is comprehensively reflected by using the life evaluation model, and the operation efficiency is remarkably improved and the service life is prolonged through real-time monitoring and optimization. According to the invention, efficient and reliable battery management requirements under complex working conditions can be met.

Disclosed are a lithium iron phosphate precursor, a lithium iron phosphate material, a preparation method therefor, and a use thereof. The lithium iron phosphate material comprises a flower cluster structure, the flower cluster structure comprises secondary particles, and the secondary particles are formed by agglomerating primary particles by means of a coating layer; the material of the primary particles is lithium iron phosphate. The lithium iron phosphate material of the present invention has good electrochemical properties and processing properties when used in batteries.

The present invention relates to the technical field of lithium battery state estimation, and in particular to a fuzzy EKF-AH algorithm-based state of charge (SOC) estimation and correction method for a lithium iron phosphate battery. The method comprises: by taking a certain startup of an energy storage device as a start, a BMS reading an SOC and a state of health (SOH) at the previous shutdown, and on the basis of a standby time, selecting an open circuit voltage (OCV) or an EKF algorithm to correct the SOC; using an EKF-AH algorithm to estimate the SOC, establishing, on the basis of fuzzy control, a fuzzy rule library associated with the SOC and the SOH, and dynamically adjusting a weight and a measurement noise deviation of the EKF-AH algorithm; and calculating estimation differences between the EKF algorithm and an ampere-hour integration method, and if the sum of the estimation differences is greater than a corresponding threshold, issuing an SOH correction warning. The present invention improves the estimation accuracy of the entire life cycle of the lithium iron phosphate battery, and assists the correction of the SOH.

The invention provides a method for preferentially extracting lithium from battery black powder, and relates to the field of battery recovery. The method comprises the following steps: mixing battery black powder with water and acid liquor, carrying out lithium extraction reaction on the battery black powder under the conditions of pressurization and heating to obtain reacted slurry, and carrying out solid-liquid separation to obtain a lithium-rich solution and residues; the battery black powder comprises at least one of waste ternary lithium ion battery positive electrode powder, waste ternary lithium ion battery positive and negative electrode mixed powder and waste lithium iron phosphate battery black powder. According to the method for preferentially extracting the lithium from the battery black powder, operation steps are simplified, energy consumption is reduced, efficient and preferential recovery of the lithium is achieved, the recovery rate of the lithium and the separation efficiency of the lithium and nickel / cobalt / manganese are remarkably improved, the lithium leaching rate can reach 96.5% or above, and the nickel-cobalt-manganese leaching rate is lt; and 0.5%.

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 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 discloses a solid-phase sintering repair method of a waste lithium iron phosphate battery material, and relates to the related field of battery recovery and repair, and the method comprises the following steps: disassembling the waste lithium iron phosphate battery material, taking out a battery positive plate, cleaning, drying and separating a positive material; a spectrograph is adopted for component analysis, the element component content is determined, and raw material adding and supplementing are conducted based on the deviation value of the theoretical element proportion; based on the characteristic information, sectional type sintering scheme analysis is conducted, and solid-phase sintering repair scheme parameters are obtained; the mixed lithium iron phosphate powder is pressed into a sheet shape and placed in sintering equipment for solid-phase sintering repairing treatment, and a repairing sample is obtained; and obtaining test performance parameters according to a battery application detection standard, and performing repair compensation control on the repair scheme parameters. The technical problem that the repairing effect is uncontrollable due to lack of precise analysis and targeted optimization in existing solid-phase sintering repairing is solved, and the technical effects of efficient repairing and performance improvement are achieved.

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.

Systems, methods, and articles for a portable power case are disclosed. The portable power case is comprised of at least one battery and at least one PCB. The portable power case has at least one USB port and at least two access ports, at least two leads, or at least one access port and at least one lead. The portable power case is operable to supply power to an amplifier, a radio, a wearable battery, a mobile phone, and a tablet. The portable power case is operable to be charged using solar panels, vehicle batteries, AC adapters, non-rechargeable batteries, and generators. The portable power case provides for modularity that allows the user to disassemble and selectively remove the batteries installed within the portable power case housing.

The invention discloses a multi-modal fusion lithium iron phosphate battery thermal runaway early warning method and system, and the method comprises the steps: collecting multi-source heterogeneous data, such as temperature, voltage, gas concentration and shell strain pressure, in real time through deploying a heterogeneous sensor network, and carrying out the noise reduction and time sequence feature extraction through employing a sub-linear time low-rank approximation algorithm of a Hankel matrix; constructing a cross-modal feature association network by applying a secondary time algorithm of a maximum weight sparse subgraph problem, inputting a fused feature vector into a Bayesian network health degree evaluation model for probabilistic reasoning calculation to obtain a battery health degree score and a thermal runaway risk level, generating a graded early warning signal through multi-level early warning threshold comparison, and performing early warning on the battery health degree score and the thermal runaway risk level. And corresponding prevention and control suggestions are matched. The method solves the technical problems that single physical quantity monitoring is difficult to comprehensively reflect the complex change in the battery and the response delay of a centralized processing architecture causes the early warning lag, and achieves the timely capture and accurate early warning of the early weak characteristics of thermal runaway.

The invention provides a preparation method of a lithium iron phosphate material, a lithium ion battery and electric equipment, and relates to the technical field of batteries. The method comprises the following steps: mixing raw materials of an iron source, a lithium source and a phosphorus source with a reagent serving as a reducing agent and a carbon source, and grinding to obtain precursor powder; wherein the molar ratio of the lithium source to the iron source is 1.03-1.05, and the molar ratio of the iron source to the phosphorus source is 0.965-0.99; carrying out high-temperature treatment on the precursor powder in an inert atmosphere to obtain a lithium iron phosphate base material; and crushing the lithium iron phosphate base material to obtain the lithium iron phosphate material meeting the particle size requirement. The high-capacity and high-compaction lithium iron phosphate material is obtained by accurately controlling key indexes such as the iron-phosphorus ratio, the carbon content, the graphitization degree and the particle size and combining an optimized processing technology, so that the fast charging performance of a lithium ion battery is improved, and the effect of not reducing the electric quantity while the fast charging requirement is met is achieved.

The present disclosure relates to the field of sodium-ion battery technology, and specifically, to a method for preparing carbon-coated sodium iron fluorophosphate from waste lithium iron phosphate and the application thereof. The method for preparing carbon-coated sodium iron fluorophosphate from waste lithium iron phosphate includes: mixing a waste lithium iron phosphate material with an alkaline solution for reaction, followed by solid-liquid separation, to obtain an aluminum-containing filtrate and a lithium iron phosphate filter residue; mixing the lithium iron phosphate filter residue, aluminum chloride and sodium chloride uniformly, followed by vacuum calcination, to obtain a calcination material; and mixing the calcination material with at least one of a sodium source, an iron source and a phosphorus source uniformly to obtain a mixture to which a fluorine source, a carbon source and a solvent are added for uniformly mixing, followed by drying and calcination sequentially to obtain the carbon-coated sodium iron fluorophosphate. The method has the advantages of low costs, a high added value, a short process, and a high recovery rate, and the carbon-coated sodium iron fluorophosphate obtained from the method has excellent electrochemical performance.

Systems, methods, and articles for a portable power case are disclosed. The portable power case is comprised of at least one battery and at least one PCB. The portable power case has at least one USB port and at least two access ports, at least two leads, or at least one access port and at least one lead. The portable power case is operable to supply power to an amplifier, a radio, a wearable battery, a mobile phone, and a tablet. The portable power case is operable to be charged using solar panels, vehicle batteries, AC adapters, non-rechargeable batteries, and generators. The portable power case provides for modularity that allows the user to disassemble and selectively remove the batteries installed within the portable power case housing.

The invention discloses a control method and system for an active equalization lithium iron phosphate hybrid battery device. The method comprises the following steps: full charge correction triggering: starting an active equalization program when the SOC of a battery pack reaches a threshold value; a low-current active equalization strategy is adopted, and charges are continuously transferred; performing dynamic voltage difference threshold control and real-time monitoring: acquiring the voltage of each single battery at intervals, calculating the voltage standard deviation sigma in the module, and if the voltage standard deviation sigma is greater than 30mV, judging that abnormal voltage difference exists; grading response: when the voltage difference between the single batteries exceeds 50mV, immediately stopping the equalization operation, and triggering an overvoltage / undervoltage protection mechanism; and when the voltage difference is between 30mV and 50mV, the equalizing current is reduced to 0.02 C, and if the voltage difference is not recovered to a safe range, the equalizing operation is terminated. According to the method, the active equalization program can be accurately started, capacity calibration is carried out to correct the capacity deviation, and meanwhile, the voltage difference of each single battery is synchronously monitored, so that the equalization efficiency and precision of the battery pack are remarkably 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 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 relates to a positive electrode active material, a preparation method, a battery monomer, a battery device and a power utilization device. The positive electrode active material comprises an inner core and a first coating layer arranged on at least part of the surface of the inner core, the inner core comprises lithium manganese iron phosphate; the first coating layer comprises lithium iron phosphate; an X-ray diffraction pattern of the positive electrode active material comprises a diffraction peak of a (020) crystal face and a diffraction peak of a (200) crystal face, the diffraction peak of the (020) crystal face and the diffraction peak of the (200) crystal face meet the condition that I (020) / I (200) is larger than or equal to 3.5, I (020) represents the intensity of the diffraction peak of the (020) crystal face, and I (200) represents the intensity of the diffraction peak of the (200) crystal face. The positive electrode active material provided by the embodiment of the invention has good lithium ion diffusion performance, and when the positive electrode active material is used for a battery, the battery can have good rate capability.

The invention relates to the technical field of lithium ion batteries, in particular to a gradient-doped lithium iron phosphate positive electrode material and a preparation method and application thereof. The invention provides a gradient doped lithium iron phosphate positive electrode material, on a particle cross section of the lithium iron phosphate positive electrode material, a particle center is taken as a circle center, a distance from the particle center to a nearest surface is taken as a radius R, a concentric circle region with a radius of 0.5 R is taken as a central region, and the rest part is a surface layer region, the metal doping amount of the central region is D1, the metal doping amount of the surface layer area is D2, D1 is larger than D2, delta D is equal to D1-D2, and delta D is larger than or equal to 2000 ppm and smaller than or equal to 4000 ppm. In the obtained lithium iron phosphate positive electrode material, sufficient compaction density can be ensured, the problem of poor dynamic performance of the positive electrode material can be well solved, and the discharge performance and rate capability of the lithium iron phosphate positive electrode material are effectively improved.

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 provides a lithium iron phosphate positive electrode material and a preparation method thereof, a positive electrode plate and a secondary battery, and belongs to the field of battery materials, the average particle size of primary particles of the lithium iron phosphate positive electrode material is 250-330 nm, and the lithium iron phosphate positive electrode material comprises first particles and second particles; the particle size of the first particles is less than or equal to 200nm, and the number ratio of the first particles is 35-45%; the second particles meet the following conditions: the particle size is greater than or equal to 1 mu m, and the quantity ratio is 1-5%; the second particle has a columnar structure, and the ratio of the length to the width of the columnar structure is (1.7-6): 1. According to the invention, the lithium iron phosphate positive electrode material with high compaction density and excellent discharge performance can be obtained.

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 lithium iron phosphate positive electrode material and a preparation method thereof, a positive electrode plate and a lithium ion battery, and relates to the technical field of lithium ion batteries. The preparation method of the lithium iron phosphate positive electrode material comprises the following steps: dispersing an iron source, a phosphorus source, a lithium source, a first carbon source, a first dopant and a first solvent to obtain first slurry; performing primary drying and primary sintering treatment on the first slurry to obtain a precursor material; adding a second carbon source, a second dopant and a second solvent into the precursor material, and performing dispersion treatment to obtain second slurry; and carrying out secondary drying and secondary sintering treatment on the second slurry to obtain the lithium iron phosphate positive electrode material. In the preparation process of the lithium iron phosphate positive electrode material, the first dopant and the second dopant are respectively added, and the cycle performance and the rate capability of the lithium iron phosphate positive electrode material are further remarkably improved by utilizing the synergistic effect of the first dopant and the second dopant.

The invention discloses a uniform carbon-coated lithium iron phosphate positive electrode material and a preparation method thereof, and relates to the technical field of lithium iron phosphate positive electrode materials, the uniform carbon-coated lithium iron phosphate positive electrode material comprises lithium iron phosphate matrix particles, the lithium iron phosphate matrix particles are coated with a composite carbon layer, and the composite carbon layer is doped with cerium modified tantalum carbide nanocrystals; the preparation method of the cerium modified tantalum carbide nanocrystal comprises the following steps: dissolving pentaethoxy tantalum and cerous nitrate in ethylene glycol, adding urea as a precipitator, and synthesizing a Ta-Ce-O precursor through a microwave-assisted solvothermal method; the Ta-Ce-O precursor and phenolic resin are mixed and then subjected to ball milling and sintering, and the cerium modified tantalum carbide nanocrystal is obtained. By introducing a small amount of cerium modified tantalum carbide nanocrystals into the composite carbon layer for many times, uniform coating of the composite carbon layer can be realized, and the electrochemical performance of the lithium iron phosphate positive electrode material is enhanced.

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.