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Method for preparing mixing phase positive pole material of iron phosphide and lithium iron phosphate by reaction method

A technology of lithium iron phosphate and positive electrode materials, applied in the direction of phosphorus compounds, chemical instruments and methods, phosphides, etc., can solve the problems of uncontrollable Fe2P amount and structure, etc., achieve excellent discharge performance, good cycle performance, and less time-consuming Effect

Inactive Publication Date: 2008-12-31
FUJIAN NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the Fe in the sample 2 P is obtained by carbon reduction, and Fe in the sample cannot be controlled 2 The amount and structure of P

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] The preparation of lithium iron phosphate consists of the following steps:

[0027] According to the molar ratio of reactants Li + : Fe 2+ :PO 4 3- :H 3 PO 2 =1.20: 1.10: 0.60: 1.20 Weigh lithium carbonate, ferrous oxalate, ammonium phosphate, hypophosphorous acid, then weigh 1% vitamin C and 3% hydroboration Sodium and 1% polypropylene.

[0028] Mix lithium carbonate, ferrous oxalate and vitamin C evenly, add sodium borohydride and 1 / 10 volume of acetone of the solid volume to be milled, then add ammonium phosphate, hypophosphorous acid and polypropylene, and mill for 3 hours with an ordinary ball mill. Dry under vacuum at 55°C. The dried powder is placed in a high-purity nitrogen atmosphere, pre-calcined at 200°C for 15 hours, and cooled to room temperature to prepare the pre-calcined precursor. Add the same volume of acetone as the volume of the solid to be ball-milled into the precursor calcined material, mill it with a common ball mill for 3 hours, and dry ...

Embodiment 2

[0030] The preparation of lithium iron phosphate consists of the following steps:

[0031] According to reactant Li + : Fe 2+ :PO 4 3- : Molar ratio of hypophosphorous acid 0.80: 0.80: 0.999: 0.003 Weigh lithium hydroxide, ferrous acetate, diammonium hydrogen phosphate, hypophosphorous acid, then weigh 5% of the lithium iron phosphate mass calculated based on the reactant mass citric acid, 1% potassium borohydride and 20% sucrose.

[0032] Mix lithium hydroxide, ferrous acetate and citric acid evenly, add potassium borohydride, then add deionized water twice the volume of the solid to be ball-milled, mix evenly, add diammonium hydrogen phosphate, hypophosphorous acid and sucrose, use ordinary Ball milling for 3 hours, and vacuum drying at 60°C. The dry powder is placed in a high-purity nitrogen atmosphere, pre-calcined at 200°C for 15 hours, and cooled to room temperature to prepare the precursor pre-calcined material. Add acetone 5 times the volume of the solid to be ba...

Embodiment 3

[0034] The preparation of lithium iron phosphate consists of the following steps:

[0035] According to reactant Li + : Fe 2+ :PO 4 3- : NaH 2 PO 2 The molar ratio is 0.45: 0.95: 0.60: 0.75 Weigh lithium oxalate, ferrous chloride, ammonium dihydrogen phosphate, sodium hypophosphite, weigh 12% formaldehyde, 1 % hydrazine hydrate and 10% sucrose.

[0036] Mix lithium oxalate, ferrous chloride, and formaldehyde evenly, add hydrazine hydrate and an aqueous solution of 90% ethanol that is 5 times the volume of the solid to be ball-milled, mix evenly, and then add ammonium dihydrogen phosphate, NaH 2 PO 2 and sucrose, milled with a high-energy ball mill for 15 hours, and dried under vacuum at 80°C. The dried powder is placed in a mixed atmosphere of 90% nitrogen and 10% hydrogen, heated from room temperature to 200 °C at a heating rate of 0.5 °C / min, kept at the temperature for pre-calcination for 15 hours, and cooled to room temperature to prepare the precursor calcined mat...

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PUM

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Abstract

The invention relates to a method for preparing ferrous phosphide and lithium iron phosphate mixed phase cathode materials by reduction method and is characterized in that the preparing process includes the following steps: lithium salt, ferrous salt, phosphate, and hypophosphorous acid or hypophosphite are taken by weighing while the mol ratio of Li: Fe: PO4<3->: hypophosphorous acid or hypophosphite is x: y (1-z): k. The ferrous salt is uniformly blended with medium strong reducing agent and then mixed with a strong reducing agent. The lithium salt, phosphate, hypophosphorous acid or hypophosphite, carbon-containing compound or carbon powder and wet milling liquid are added, ball milling is carried out for 3-15 hours, and the mixture is dried in atmospheric pressure or vacuum at 55-105 DEG C. The dried powder is put in inert atmosphere or weakly reducing atmosphere for preparing the ferrous phosphide and lithium iron phosphate mixed phase cathode materials by two-stage sintering process or temperature programmed two-stage sintering process.

Description

technical field [0001] The invention belongs to the technical field of battery electrode material preparation, and in particular relates to a preparation method of a lithium ferrous phosphate cathode material that can be used for lithium batteries, lithium ion batteries, polymer batteries and supercapacitors. technical background [0002] Lithium iron phosphate (LiFePO) with olivine structure 4 ) is a new type of material for the positive electrode of lithium-ion batteries. Wide range of resource sources, cheap price, high theoretical specific capacity, good thermal stability, and environmental friendliness, etc., are expected to become the first choice for the new generation of cathode materials that can replace lithium cobalt oxide. However, lithium iron phosphate still has many disadvantages in lithium-ion batteries. For example, lithium iron phosphate has low electronic conductivity, low ion conductivity, small tap density and true density, and poor low temperature per...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/08C01B25/45H01M4/58
CPCY02E60/10
Inventor 童庆松
Owner FUJIAN NORMAL UNIV
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