Method for preparing composite anode material LiFePO4/C for lithium ion battery

A composite cathode material, lithium-ion battery technology, applied in battery electrodes, chemical instruments and methods, circuits, etc., can solve the problems of insufficient high rate discharge and insufficient uniformity of particles, and achieve a stable charge and discharge voltage platform, excellent performance, The effect of structural stabilization

Inactive Publication Date: 2011-01-05
HEFEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the cathode material LiFePO prepared by these methods 4 / C has performance limitations such as insufficiently uniform particles and insufficient high-rate discharge.

Method used

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  • Method for preparing composite anode material LiFePO4/C for lithium ion battery
  • Method for preparing composite anode material LiFePO4/C for lithium ion battery
  • Method for preparing composite anode material LiFePO4/C for lithium ion battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] 1) Weigh 0.5mol lithium hydroxide, 0.65mol ferrous chloride, 0.70mol diammonium hydrogen phosphate and dissolve them in deionized water, then add 1.2mol resorcinol and 0.45mol polyethylene glycol to the mixed solution (PEG-2000), mix well. Measure the formaldehyde solution so that the molar ratio of formaldehyde to resorcinol is 2:1 and add it to the above solution. Stir continuously under a magnetic stirrer, stir at a constant temperature of 35°C for 6 hours, and adjust the pH value to about 8.9 with ammonia water, and form a sol after ultrasonic dispersion;

[0029]2) After drying the prepared sol at 160° C. for 5 hours, evaporate the solvent to obtain a xerogel;

[0030] 3) Then ball mill for 6 hours on a planetary ball mill with a rotating speed of 600 rpm. Pre-fire at 380°C for 8 hours after fully grinding. Calcining at 700°C for 10 hours under the atmosphere of nitrogen and hydrogen (5%-10%), the gas flow rate is 0.1-10L / min. Cool down to room temperature to g...

Embodiment 2

[0034] 1) Weigh 0.75mol lithium chloride, 0.95mol ferrous oxalate, 0.80mol lithium phosphate, dissolve in deionized water, then add 1.56mol resorcinol and 0.65mol polyethylene glycol (PEG -2000), mix well. Measure the formaldehyde solution so that the molar ratio of formaldehyde to resorcinol is 2:1 and add it to the above solution. Stir continuously under a magnetic stirrer, stir at a constant temperature of 55°C for 5 hours, and adjust the pH value to about 4.2 with hydrochloric acid, and form a sol after ultrasonic dispersion;

[0035] 2) After drying the prepared sol at 120° C. for 9 hours, evaporate the solvent to obtain a xerogel;

[0036] 3) Then ball mill on a planetary ball mill for 10 hours at a speed of 500 rpm. Pre-fire at 450°C for 5 hours after fully grinding. Calcining at 900°C for 5 hours under an atmosphere of nitrogen and carbon monoxide (5% to 10%), with a gas flow rate of 0.1 to 10 L / min. Cool down to room temperature to get powdered LiFePO 4 / C Compos...

Embodiment 3

[0039] 1) Weigh 1.06mol of lithium acetate, 1.36mol of iron citrate, and 1.47mol of ammonium phosphate and dissolve them in deionized water, then add 2.52mol of resorcinol and 0.95mol of polyethylene glycol (PEG-2000 ),well mixed. Measure the formaldehyde solution so that the molar ratio of formaldehyde to resorcinol is 2:1 and add it to the above solution. Stir continuously under a magnetic stirrer, stir at a constant temperature of 80°C for 2 hours, and adjust the pH value to about 6.9 with different ratios of ammonia water and hydrochloric acid, and form a sol after ultrasonic dispersion;

[0040] 2) After drying the prepared sol at 90° C. for 20 h, evaporate the solvent to obtain a xerogel;

[0041] 3) Then ball mill for 3 hours on a planetary ball mill at a speed of 600 rpm. Pre-fire at 300°C for 10 hours after fully grinding. Calcining at 650°C for 10 hours under a protective atmosphere of nitrogen and hydrogen (5% to 10%), with a gas flow rate of 0.1 to 10 L / min. Co...

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Abstract

The invention relates to a method for preparing a composite anode material LiFePO4/C for a lithium ion battery. The method comprises the steps of mixing, reacting, drying, calcining and cooling and is characterized in that: lithium salt, ferric salt and phosphate are mixed with a chemical substance, namely, formaldehyde capable of forming an ideal carbon gel pre-condensed substance and a resorcinol composition so as to form a complex rheological phase reaction system for preparing an LiFePO4/C high molecular polymer; and reaction substances for preparing the LiFePO4 are uniformly distributed in the carbon gel pre-condensed substance. Simultaneously, polyethylene glycol (PEG) is added, pH is controlled and a reaction system is adjusted so as to adjust the structure of the carbon gel pre-condensed substance, a netlike porous structural material which is distributed uniformly can be obtained by calcining and carbon is uniformly coated on the surface of the LiFePO4. Under the condition of10C multiplying power, discharge specific capacity is up to 120.56mAh/g and circulating performance is high. The prepared anode material has a stable structure and high cyclical stability, does not contain any heavy metal and is an environmentally-friendly material.

Description

1. Technical field [0001] The invention relates to a method for preparing a positive electrode material of a lithium ion battery, specifically a lithium ion battery composite positive electrode material LiFePO 4 / C preparation method. 2. Background technology [0002] LiFePO with olivine structure 4 Capable of reversibly intercalating and deintercalating lithium ions, it is considered to be one of the alternative electrode materials for lithium-ion batteries. The research shows that the material has the following advantages: cheap raw materials, no heavy metals, rich resources, and environmental friendliness; moderate working voltage (3.4V), good platform characteristics; large theoretical capacity, stable structure, good safety performance; high temperature performance and cycle Good performance; good compatibility with most electrolyte systems and good storage performance. [0003] Preparation of LiFePO 4 The methods mainly include solid-phase method, sol-gel method, m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/139C01B25/45
CPCY02E60/12Y02E60/122Y02E60/10
Inventor 李学良郭丽彬罗梅刘沛
Owner HEFEI UNIV OF TECH
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