CN101941686A

CN101941686A - Preparation method of LiFePO4

Info

Publication number: CN101941686A
Application number: CN 201010278154
Authority: CN
Inventors: 左一村; 伍儒锋; 喻国强
Original assignee: MIANYANG TIANMING NEW ENERGY TECHNOLOGY Co Ltd
Current assignee: MIANYANG TIANMING NEW ENERGY TECHNOLOGY Co Ltd
Priority date: 2010-09-10
Filing date: 2010-09-10
Publication date: 2011-01-12

Abstract

The invention discloses a preparation method of LiFePO4, belonging to the preparation field of the chemical raw material. The method comprises the following steps: dissolving and mixing raw materials, performing ball milling, drying, grinding, performing high-temperature roasting, and cooling to obtain LiFePO4 with a high-density olivine structure. The invention has simple technology and easy operation method and is easy to realize industrialization; the composition of the raw materials and the formula of the product are easy to control, the synthesized LiFePO4 has high tap density, high purity and excellent electrochemical performance; and the product is suitable to prepare the positive electrode material of the lithium ion battery.

Description

The preparation method of LiFePO 4

Affiliated technical field

The present invention relates to a kind of preparation method of industrial chemicals, especially the preparation method of LiFePO 4 belongs to the industrial chemicals preparation field.

Background technology

At present, directly the method for synthesizing lithium ferrous phosphate mainly contains high-temperature solid phase reaction method, hydrothermal method; Divide sol-gel method, coprecipitation method, mechanochemistry activation method etc. in addition according to the presoma preparation section.There is following shortcoming in above method, has hindered its practical application: the Fe during (1) is synthetic ²⁺Easily be oxidized to Fe ³⁺, be difficult to obtain monophasic LiFePO ₄(2) lithium ion is at LiFePO ₄Middle diffusion difficulty causes the utilization ratio of active material low; (3) LiFePO ₄The specific conductivity of itself is also very low, causes its heavy-current discharge performance poor.

Summary of the invention

The deficiency that exists at aforesaid method, but the invention provides a kind of preparation method of LiFePO 4 of high-energy-density heavy-current discharge.

The technical solution adopted for the present invention to solve the technical problems is:

The preparation method of LiFePO 4 may further comprise the steps:

A. ferric iron source, phosphorus source, lithium source, doped element chemicals, carbon source are pressed a mole usage ratio 0.5～1: 1: 0.5～1: 0～1: 0.05～0.1 uniform mixing is in the dispersion agent of 2 times of volumes;

B. said mixture is put into ball mill container, ball milling 1～8 hour,

C. the ball milling product places non-oxidizing atmosphere in 200～300 ℃ of bakings 5～10 hours, naturally cooling;

D. grind then, obtain the LiFePO 4 precursor;

E. this precursor is placed High Temperature Furnaces Heating Apparatus, in reducing atmosphere, heat up with 15～40 ℃/min heating rate, at 500～900 ℃ of constant temperature calcining 8～15h,

F. be cooled to below 40 ℃ with 15～40 ℃/min cooling rate then, make ferrous phosphate lithium powder or ferrous phosphate doping lithium powder.

Described ferric iron source is a kind of in iron(ic) chloride, iron nitrate, tertiary iron phosphate, the ferric ammonium sulfate; The phosphorus source is phosphoric acid, ammonium hydrogen phosphate, a kind of in tertiary iron phosphate, the primary ammonium phosphate; The lithium source is a kind of in Lithium Oxide 98min, Lithium Acetate, lithium chloride, lithium nitrate, the Quilonum Retard; The doped element chemicals are MnCO ₃, Mn (NO ₃) ₂, Mn ₂O ₃, MnPO ₄, M _OO ₃, Mg (OH) ₂, Mg (NO ₃) ₂, NiPO ₄In a kind of; Carbon source is a kind of in sucrose, glucose, dextrin, polypropylene, polyacrylamide, citric acid, the starch; Dispersion agent is a kind of in water, the ethanol.

Directly use ferric iron to be source of iron, avoided ferrous salt synthesis step loaded down with trivial details in other synthetic technologys, solved the impure problem of product of using in air the easy ferrous salt raw material of oxidation often to have.Adopt this mechanical process for solid phase synthesis, synthetic grain is through little, narrowly distributing, purity height, and jolt ramming is big, can obtain the good ferrousphosphate lithium material of chemical property.

By the control synthesis technique, at first synthetic a kind of high-density LiFePO 4 precursor is calcined this precursor more under given conditions, obtains high-density olivine structural LiFePO 4.Its median size 1～5 μ m, loose density 〉=0.5g/cm ³, tap density 1.0～1.7g/cm ³, specific surface≤20m ²/ g, first discharge specific capacity (3C) 〉=125mAh/g.

The invention has the beneficial effects as follows that technology is simple, easy to operate, material composition and product prescription are controlled easily, and the jolt ramming of synthetic LiFePO 4 is big, purity is high, chemical property is good; Synthetic LiFePO of the present invention ₄/ C material and carbon negative pole are assembled into test battery, and specific storage reaches 130mAh/g when the 1C multiplying power discharging, and show outstanding stable circulation performance.Employed material is large Chemicals, easily realizes the technical scale cleaner production, three-waste free discharge.

Embodiment

The present invention is further described below in conjunction with embodiment.

Embodiment one:

A. take by weighing iron(ic) chloride 1000 grams, primary ammonium phosphate 800 grams, Lithium Acetate 450 grams, manganous carbonate 40 grams, sucrose 530 grams, uniform mixing is in 1L ethanol;

B. said mixture is put into ball mill container, ball milling 6 hours;

C. the ball milling product places air atmosphere in 300 ℃ of bakings 10 hours, naturally cooling;

D. grind, obtain compound;

E. compound is placed High Temperature Furnaces Heating Apparatus, in the mixed atmosphere of hydrogen+nitrogen, heat up with 35 ℃/min heating rate, at 800 ℃ of constant temperature calcining 15h;

F. be cooled to make the ferrous phosphate doping lithium powder below 40 ℃ with 35 ℃/min cooling rate then.

The median size that records this product is 3～5 μ m, tap density 1.6g/cm ³, specific surface 19m ²/ g, under the room temperature, first discharge specific capacity (3C) 〉=125mAh/g.

Embodiment two:

A. take by weighing tertiary iron phosphate 1500 grams, primary ammonium phosphate 800 grams, Quilonum Retard 250 grams, magnesium hydroxide 20 grams, glucose 550 grams, uniform mixing is in 2L water;

B. said mixture is put into ball mill container, ball milling 5 hours;

C. the ball milling product places air atmosphere in 200 ℃ of bakings 10 hours, naturally cooling;

D. grind, obtain compound;

E. compound is placed High Temperature Furnaces Heating Apparatus, in the mixed atmosphere of hydrogen+nitrogen, heat up with 35 ℃/min heating rate, at 900 ℃ of constant temperature calcining 15h;

The median size that records this product is 1～3 μ m, tap density 1.7g/cm ³, specific surface 20m ²/ g, under the room temperature, first discharge specific capacity (3C) 〉=125mAh/g.

Claims

1. the preparation method of a LiFePO 4 is characterized in that, may further comprise the steps:

B. said mixture is put into ball mill container, ball milling 1～8 hour;

D. grind then, obtain the LiFePO 4 precursor;

E. this precursor is placed High Temperature Furnaces Heating Apparatus, in reducing atmosphere, heat up with 15～40 ℃/min heating rate, at 500～900 ℃ of constant temperature calcining 8～15h;

F. be cooled to below 40 ℃ with 15～40 ℃/min cooling rate then, make ferrous phosphate lithium powder or ferrous phosphate doping lithium powder;