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Method for preparing spherical ferric lithium phosphate by oxidation control crystal-carbon thermal reduction method

A lithium iron phosphate technology for controlling crystallization, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve the problems of poor product consistency and insufficient stability, and achieve the effects of low cost, simple process and wide source of raw materials

Inactive Publication Date: 2009-01-07
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the ferrous ammonium phosphate precursor contains uncertain crystal water and is not stable enough, when the above method is used to produce lithium iron phosphate, the product consistency is poor, and the control requirements for process conditions are strict, which needs to be improved

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] Prepare a mixed aqueous solution of ferrous sulfate and phosphoric acid, wherein the concentration of ferrous sulfate is 1.0 mol / L and the concentration of phosphoric acid is 1.0 mol / L; prepare ammonium persulfate solution with a concentration of 0.6 mol / L; prepare ammonia with a concentration of 2 mol / L aqueous solution. The mixed aqueous solution of ferrous sulfate and phosphoric acid, the ammonium persulfate solution and the ammonia solution were input into a reactor with a capacity of 3 liters filled with deionized water in advance and reacted with a metering pump. Control the flow of ferrous sulfate and phosphoric acid mixed aqueous solution to be 120 ml / hour, control the flow of ammonium persulfate solution to be 120 ml / hour, adjust the flow of ammonia solution, and control the pH value of the reaction solution in the reactor to be 2.30 ± 0.05. The temperature in the reactor was controlled to be 50°C. The mixed material in the reactor naturally overflows into the...

Embodiment 2

[0043] Prepare the mixed aqueous solution of ferrous chloride and phosphoric acid, wherein the concentration of ferrous chloride is 2.0 mol / liter, and the concentration of phosphoric acid is 2.0 mol / liter. Prepare a sodium hypochlorite solution with a concentration of 1.0 mol / L. Prepare an ammonia solution with a concentration of 4 mol / L. A mixed aqueous solution of ferrous chloride and phosphoric acid, a sodium hypochlorite solution and an aqueous ammonia solution were input into a reactor with a capacity of 3 liters filled with deionized water in advance and reacted with a metering pump. Control the flow rate of ferrous chloride and phosphoric acid mixed aqueous solution to be 150 ml / hour, control the flow rate of sodium hypochlorite solution to be 150 ml / hour, adjust the flow rate of ammonia solution, and control the pH value of the reaction solution in the reactor to be 3.30 ± 0.05. The temperature inside the reactor was controlled to be 40°C. The mixed material in the r...

Embodiment 3

[0045] Prepare a mixed aqueous solution of ferrous sulfate and phosphoric acid, wherein the concentration of ferrous sulfate is 0.2 mol / liter, and the concentration of phosphoric acid is 0.2 mol / liter; prepare a solid hydrogen peroxide solution with a concentration of 0.1 mol / liter; prepare an ammonia solution with a concentration of 1 mol / liter . A mixed aqueous solution of ferrous sulfate and phosphoric acid, a solid hydrogen peroxide solution and an aqueous ammonia solution were input into a 3-liter reactor previously filled with deionized water with a metering pump for reaction. Control the flow of ferrous sulfate and phosphoric acid mixed aqueous solution to be 200 ml / hour, control the flow of solid hydrogen peroxide solution to be 200 ml / hour, adjust the flow of ammonia solution, and control the pH value of the reaction solution in the reactor to be 3.90 ± 0.05. The temperature inside the reactor was controlled to be 40°C. The mixed material in the reactor naturally ove...

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Abstract

The invention discloses a method for preparing spherical lithium iron phosphate by adopting oxidation control crystallization-carbon thermal reduction. The preparation method comprises the steps of conducting reaction among a mixed water solution of bivalence malysite and phosphoric acid, an aqueous solution of ammonia and an oxidant; synthesizing a spherical precursor of a spherical hydration iron phosphate through the process of oxidation control crystallization; washing; drying; pre-burning for dewatering; mixing with lithium carbonate and a carbon source; and obtaining the lithium iron phosphate through high temperature carbon thermal reduction under the protection of inertial or reducing atmosphere. By using the preparation method, the spherical lithium iron phosphate, an anode material of a lithium ion battery, is prepared, and has high bulk density and high volume specific capacity. The average grain size of the spherical lithium iron phosphate is between 6 and 8 mum, the electric discharge specific capacity thereof for the first time can reach up to 145-150mAh / g at the room temperature of 0.5C.

Description

technical field [0001] The invention belongs to the technical field of energy material preparation. In particular, it relates to a method for preparing spherical lithium iron phosphate by using oxidation-controlled crystallization-carbothermal reduction for positive electrode materials of lithium-ion batteries. Background technique [0002] Lithium-ion batteries are a new generation of green high-energy batteries, which have many advantages such as high voltage, high energy density, good cycle performance, small self-discharge, no memory effect, and wide operating temperature range. They are widely used in mobile phones, notebook computers, and digital cameras. , camcorders, electronic instruments, etc., also have bright application prospects in UPS, electric tools, electric bicycles, electric vehicles, energy storage batteries and other fields. In recent years, the output of lithium-ion batteries has grown rapidly, and the application fields have continued to expand. It ha...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45H01M4/58
CPCY02E60/10
Inventor 应皆荣高剑姜长印万春荣
Owner TSINGHUA UNIV
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