Method for improving performance of anode material LiFePO4 for lithium ion cell

A technology for lithium-ion batteries and cathode materials, applied in battery electrodes, chemical instruments and methods, circuits, etc., can solve problems such as high processing costs, complicated process steps, and increased battery production costs, and achieve high electronic conductivity and good circulation Performance and Rate Capability, Effect of Excellent Li-ion Diffusion Rate

Inactive Publication Date: 2013-08-21
NANJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, most of these methods involve high processing costs and complicated process steps, which greatly increase the production cost of batteries.

Method used

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  • Method for improving performance of anode material LiFePO4 for lithium ion cell
  • Method for improving performance of anode material LiFePO4 for lithium ion cell
  • Method for improving performance of anode material LiFePO4 for lithium ion cell

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] This experiment is realized through the following steps: 1. The Fe(CH 3 COO) 2 4H 2 O (analytical grade), LiCH 3 COO·2H 2 O (analytical pure) and NH 4 h 2 PO 4 (Analytical pure) in triethylene glycol (TEG for short) mixed evenly and boiled and refluxed for 16h to prepare pure phase LiFePO 4 Materials; 2. Pure phase LiFePO with deionized water 4 Mix evenly with graphene oxide and carbon nanotubes (the mass fraction of graphene in the final electrode material is 2%, the mass fraction of carbon nanotubes is 3%, that is, the total carbon content is 5%), in the air at 60°C Drying for 24 hours; 3. Heat-treat the powder obtained in step 2 at a high temperature of 700° C. for 2 hours in argon.

[0022] figure 1 is LiFePO before modification 4Cathode material (a) and LiFePO obtained after modification 4 Comparison of the microscopic morphology of the positive electrode material (b). It can be seen from the figure that the pure phase LiFePO without doped graphene and c...

Embodiment 2

[0027] This experiment is realized through the following steps: 1. The Fe(CH 3 COO) 2 4H 2 O (analytical grade), LiCH 3 COO·2H 2 O (analytical pure) and NH 4 h 2 PO 4 (Analytical pure) in triethylene glycol (TEG for short) mixed evenly and boiled and refluxed for 32h to prepare pure phase LiFePO 4 Materials; 2. Pure phase LiFePO with deionized water 4 Mix evenly with graphene oxide and glucose (the mass fraction of graphene in the final electrode material is 1%, the mass fraction of amorphous carbon is 2%, that is, the total carbon content is 3%), and dry at 80°C in the air for 16h 3. Heat the powder obtained in step 2 at 600°C for 3 hours in argon.

[0028] Modified LiFePO 4 The electrode, electronic conductivity and ion diffusion rate are significantly improved, the charge transfer ability is greatly increased, and the cycle performance and rate performance are significantly improved. Figure 5 It is the LiFePO obtained after modification treatment 4 The discharge...

Embodiment 3

[0031] This experiment is realized through the following steps: 1. The Fe(CH 3 COO) 2 4H 2 O (analytical grade), LiCH 3 COO·2H 2 O (analytical pure) and NH 4 h 2 PO 4 (Analytical pure) Mix well in tetraethylene glycol and boil and reflux for 12h to prepare pure phase LiFePO 4 Materials; 2. Pure phase LiFePO with deionized water 4 Mix it with glucose evenly (the total carbon content in the final electrode material is 4%), and dry it in the air at 50°C for 24h; 3. Heat the powder obtained in step 2 at 800°C in nitrogen for 1h. The results showed that, compared with before modification, the modified LiFePO 4 The electronic conductivity of the electrode and the diffusion rate of lithium ions are significantly improved, and the discharge specific capacity is also greatly improved.

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Abstract

The invention belongs to the field of a lithium ion cell and provides a method for improving the performance of an anode material LiFePO4 for a lithium ion cell. The method comprises the specific steps of: 1. utilizing a polyhydric alcohol reduction method to prepare a pure-phase LiFePO4 material; 2. uniformly mixing the pure-phase LiFePO4 material and appropriate amount of a carbon precursor in de-ionized water; carrying out drying heat treatment in an air atmosphere at a certain temperature; and 3. carrying out high-temperature heat treatment on powder obtained by the step 2 under an inert atmosphere for a period of time to obtain the nano-grade lithium ion anode material LiFePO4 with uniform flake-shaped appearance, increasing of electron conductivity and improvement of ion diffusion rate. According to the method, the process is simple, and expensive experimental apparatuses are not needed. Intrinsic electronic conductivity and lithium ion diffusion rate of the anode material are improved obviously, so that the electrochemical performance of the anode material is obviously improved.

Description

technical field [0001] The invention relates to a method of improving lithium-ion battery cathode material LiFePO 4 A performance method belongs to the field of lithium ion batteries. Background technique [0002] Currently, lithium-ion batteries are commonly used in the consumer electronics market and may play a very important role in the electric vehicle and hybrid electric vehicle market in the near future. However, there are still some technical problems to be solved before large-scale application. The application and development of lithium-ion batteries are mainly determined by its safety performance, energy density, durability and cost price. It is especially worth mentioning that choosing a Suitable cathode materials are of great significance to the performance of the entire lithium-ion battery system. In recent years, lithium iron phosphate (LiFePO 4 ) has been carefully studied by many scientific research groups due to its potential to be a cathode material for n...

Claims

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Application Information

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IPC IPC(8): H01M4/58H01M4/62C01B25/45
CPCY02E60/10
Inventor 邵宗平吴关
Owner NANJING UNIV OF TECH
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