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Method for preparing LiFePO4 positive electrode material through carbon cladding and Na+ doping in one step

A positive electrode material and carbon coating technology, which is applied in the synthesis and performance improvement of lithium-ion battery positive electrode materials, can solve the problems of limiting industrialization process, slow diffusion speed, low electronic conductivity, etc., and achieve good rate and cycle performance, sample The effect of performance improvement and uniform particle size distribution

Inactive Publication Date: 2014-05-14
DALIAN JIAOTONG UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But LiFePO 4 Its own electronic conductivity is low, Li + Insufficiency of slow diffusion rate limits its industrialization process

Method used

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  • Method for preparing LiFePO4 positive electrode material through carbon cladding and Na+ doping in one step
  • Method for preparing LiFePO4 positive electrode material through carbon cladding and Na+ doping in one step
  • Method for preparing LiFePO4 positive electrode material through carbon cladding and Na+ doping in one step

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Effect test

Embodiment 1

[0028] One step of the present invention realizes carbon coating and Na + Preparation of LiFePO by doping 4 The method of positive electrode material

[0029] Will Li 2 CO 3 (97%, AR), FePO 4 4H 2 O (98%, AR) is weighed at a molar ratio of 1:2, and sodium polyacrylate (polypropylene) is weighed with Li 2 CO 3 (97%, AR) with FePO 4 4H 2Weigh 10% of the O(98%, AR) mass sum, put it into a ball mill jar, add the dispersant absolute ethanol to 1 / 3 of the height of the ball mill jar, and then perform ball milling. After ball milling for 12 hours, dry in an oven at 70°C for 8 hours. After grinding evenly, burn at 700°C for 8 hours in a nitrogen-filled tube furnace to obtain carbon-coated and Na+-doped LiFePO 4 Cathode material.

Embodiment 2

[0031] Preparation of LiFePO by Reduction of Polymer Pyrolysis 4 Lithium-ion battery cathode material

[0032] LiOH·H 2 O (AR, 90%), Fe (NO 3 ) 3 9H 2 O (AR, 98.5%) and NH 4 h 2 PO 4 (AR, 99.0%) and dissolved in acrylic acid solution containing cross-linking agent in a given proportion, nitrogen gas was passed into the solution under constant stirring, an appropriate amount of initiator was added, and it was polymerized at 80°C. Then place it in an oven at 120° C. for 12 hours to obtain a polyacrylate polymer precursor. Then it was fired at 800° C. for 5 h in a tube furnace with nitrogen gas to obtain the product. During the burning process, due to the reducing atmosphere formed by the pyrolysis of organic matter, ferric iron can be reduced to ferrous iron, thereby generating LiFePO, a product containing cracked carbon. 4 Material.

Embodiment 3

[0034] Li site doping to prepare Li 0.95 Na 0.05 FePO 4 / C and its electrochemical performance

[0035] All raw materials in the preparation process are analytically pure, first CH 3 COOLi, NH 4 h 2 PO 4 and CH 3 COONa was dissolved in distilled water at a molar ratio of 0.95:1:0.05, and then FePO 4 Powder, conductive agent and reducing agent acetylene black are added to the mixture. The mixture was sonicated for 12 h to make it well mixed. Then in a nitrogen environment, the temperature was raised to 650°C at a rate of 2°C / Min, and then the temperature was kept at a constant temperature for 7 hours and then naturally cooled to room temperature to obtain Li0.95Na0.05FePO 4 / C composite product.

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Abstract

The invention discloses a method for preparing a LiFePO4 positive electrode material through carbon cladding and Na+ doping in one step. According to the method, a sodium polyacrylate high-temperature reduction method is used for preparing the LiFePO4 positive electrode material and meanwhile the purpose of metal Na+ doping is achieved. A test for preparation of LiFePO4 through high-temperature solid-phase reduction serves as a contrast test, wherein polypropylene serves as a carbon source in the preparation process. Through XRD and SEM analysis, the prepared LiFePO4 with sodium polyacrylate serving as the carbon source has a good olivine-type structure, the crystal form is good, particle size distribution is even, and the performance in each aspect of the LiFePO4 with the sodium polyacrylate serving as the carbon source is greatly improved compared with that of the LiFePO4 with the polypropylene serving as the carbon source. Electricity is discharged at the first time under 0.1 C. The discharging ratio electric capacity of the material reaches up to 168 mAh / g and the circulation performance is good. Thus, the method for preparing the LiFePO4 through sodium polyacrylate high-temperature solid-phase reduction is novel and practical.

Description

technical field [0001] The invention relates to the field of synthesis and performance improvement of positive electrode materials of lithium ion batteries. Background technique [0002] Energy, environmental issues and information technology have become the hottest topics in the 21st century. Since the beginning of human civilization, energy research aimed at providing a comfortable life for human beings has begun, and its fields involve fossil fuels, nuclear energy, solar energy, etc. Entering the information age, energy research with higher efficiency, more convenience, safety and pollution-free energy has been on the rise. At present, the internal combustion engine consumes 1 / 3 of the energy needed by human beings every year, and it is the main consumption mode of fossil fuels. At the same time, people are increasingly concerned about global warming and air pollution. As an alternative energy source, batteries have many advantages. Nowadays, lithium-ion batteries, fu...

Claims

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Application Information

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IPC IPC(8): H01M4/62H01M4/58
CPCH01M4/366H01M4/5825H01M4/625H01M10/0525Y02E60/10
Inventor 赵红李明露丁敏韩苗高攀刘博文
Owner DALIAN JIAOTONG UNIVERSITY
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