Preparation method of lithium iron phosphate battery positive electrode material

A lithium iron phosphate battery and lithium iron phosphate technology, applied in battery electrodes, secondary batteries, circuits, etc., can solve problems such as unsuitable for high rate charge and discharge, poor conductivity, etc., and achieve high charge and discharge performance and good rate performance Effect

Pending Publication Date: 2021-09-28

上海钰丽新材料科技有限公司

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Problems solved by technology

[0003] However, the current lithium iron phosphate cathode material has poor conductivity and is not suitable for high-rate char...

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Method used

The present invention prepares the carbon-coated lithium iron phosphate positive electrode material with the ferric oxide particle of nanoscale as raw material and template, and product can obtain the morphology of template, is the better nano-spherical particle of homogeneity, and particle is relatively Small, so it has higher charge and discharge perf...

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Abstract

The preparation method of the lithium iron phosphate battery positive electrode material comprises the following steps: dissolving ferric chloride in ethylene glycol, adding sodium acetate and polyethylene glycol, and performing heating; performing cooling to obtain ferroferric oxide; oxidizing the obtained ferroferric oxide into nano ferric oxide particles; mixing lithium acetate, nano ferric oxide and ammonium dihydrogen phosphate, performing mixing with a carbon source, and carrying out ball milling; sintering the powder, and performing cooling to obtain a carbon-coated lithium iron phosphate positive electrode material; washing the lithium iron phosphate powder, and adding an ethanol wetting agent to prepare turbid liquid; mixing soluble lithium salt, ferric salt and phosphate in an ethanol solution, adding the mixture into the turbid liquid, and performing mixing and drying; and roasting in an inert gas atmosphere to obtain the qualified lithium iron phosphate positive electrode material. According to the method, the defects in the prior art are overcome, the carbon-coated lithium iron phosphate positive electrode material is prepared by taking the ferric oxide particles as the raw material and the template, and the product can obtain the morphology of the template, is nano spherical particles with better uniformity and is smaller.

Application Domain

Cell electrodesSecondary cells +1

Technology Topic

Ferriferrous OxideCarbon source +15

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[0020] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention.

[0021] The invention provides a method for preparing a positive electrode material of a lithium iron phosphate battery, comprising the following steps:

[0022] (1) dissolving ferric chloride in ethylene glycol, adding sodium acetate and polyethylene glycol, heating; cooling to obtain ferric oxide; oxidizing ferric oxide to nano ferric oxide particles;

[0023] (2) Ball milling: Mix lithium acetate, nanometer ferric oxide, and ammonium dihydrogen phosphate in a molar ratio of Li:Fe:P=1:1:1 and mix with carbon source for ball milling; the ball milling time is 4-6 hours .

[0024] (3) Synthesis of lithium iron phosphate: under protective gas, the powder in step (2) is sintered, and the carbon-coated lithium iron phosphate cathode material is obtained after cooling;

[0025] (4) Filtration, the lithium iron phosphate powder is washed with deionized water, and an ethanol wetting agent is added after washing to make a suspension;

[0026] (5) Drying: Mix soluble lithium salt, iron salt, and phosphate in the ethanol solution in proportion, add to the suspension and mix, and vacuum dry at 120-140°C;

[0027] (6) Roasting: Roasting at 650-850° C. for 3-6 hours under an inert gas atmosphere to obtain a qualified positive electrode material of lithium iron phosphate.

[0028] Wherein the sintering in step (3) includes a first-order sintering stage, a second sintering stage and a third sintering stage, and the first sintering stage adopts the first heating rate to rise from room temperature to the first sintering temperature, keeping The first sintering period; the second sintering stage is to use the second heating rate to rise from the first sintering temperature to the second sintering temperature, and maintain the second sintering period; the third sintering stage is to adopt the third heating rate from the second The sintering temperature is raised to a third sintering temperature and maintained for a third sintering time.

[0029] The present invention uses nanometer-level ferric oxide particles as raw materials and templates to prepare carbon-coated lithium iron phosphate positive electrode materials, and the product can obtain the shape of the template, which is nano-spherical particles with good uniformity, and the particles are small. This has higher charge and discharge performance and better rate performance. The synthesized nano-ferric oxide only needs to be stored in a dry place without being oxidized, and it will not affect the use after a period of time. In large-scale synthesis, the timeliness requirements are not strict, which is convenient for long-term storage and transportation, and the potential reduction loss.

[0030] Through X-ray diffraction (XRD), button battery and full battery analysis test on it and qualified raw materials respectively. As shown in Table 1 below:

[0031] Table 1 Comparison of XRD data between this application and qualified lithium iron phosphate raw materials

[0032]

[0033] It can be seen from Table 1 that the crystal structure of the lithium iron phosphate material recovered by the recycling method of lithium iron phosphate waste in the manufacturing process of the lithium iron phosphate battery of the present invention is nearly the same as that of the qualified material.

[0034] Recycled lithium iron phosphate cathode materials and qualified lithium iron phosphate raw materials were used as cathodes respectively to make full batteries, and their electrochemical performances were comprehensively evaluated. The negative electrode of the battery is made of artificial graphite, the diaphragm is made of single-layer polypropylene (PP), and a 10Ah battery is made according to the conventional manufacturing process of lithium-ion batteries. The test results are shown in Table 2 below.

[0035] Table 2 Comparison of button battery data between this application and qualified lithium iron phosphate raw materials

[0036]

[0037] It can be seen from the above table that the rate performance, normal temperature 25°C cycle performance, and high temperature 60°C cycle performance of recycled lithium iron phosphate cathode materials are almost the same as those of qualified lithium iron phosphate raw materials, which can be used in normal production in the workshop.

[0038] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be described in the foregoing embodiments Modifications are made to the recorded technical solutions, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

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Classification and recommendation of technical efficacy words

Improve charge and discharge performance
Good magnification performance

Non-aqueous electrolyte containing fluorine-substituted succinic anhydride and succinic anhydride derivatives, and alkali metal secondary battery comprising thereof

InactiveCN102324562AImprove charge and discharge performanceGood life cycleSecondary cellsSolventCharge and discharge

Owner:SHANGHAI INST OF SPACE POWER SOURCES

Preparation method of lithium iron phosphate battery positive electrode material

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