Method for greatly improving electrochemical performance of low-temperature hydrothermal synthesized LiFePO4

A hydrothermal synthesis and large-scale technology, applied in chemical instruments and methods, inorganic chemistry, phosphorus compounds, etc., can solve the problems of low yield per unit volume and high price of surfactants, achieve excellent electrochemical performance, increase yield, The effect of high yield

Active Publication Date: 2012-08-29
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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Problems solved by technology

[0007] The object of the present invention is to provide a method for greatly improving low-temperature hydrothermal synthesis of LiFePO 4 The method of electrochemical performance solves the problem of hydrothermal synthesis of LiFePO with excellent electrochemical performance 4 Requires high temperature conditions and expensive surfactants and low yield per unit volume

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  • Method for greatly improving electrochemical performance of low-temperature hydrothermal synthesized LiFePO4
  • Method for greatly improving electrochemical performance of low-temperature hydrothermal synthesized LiFePO4
  • Method for greatly improving electrochemical performance of low-temperature hydrothermal synthesized LiFePO4

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Embodiment 1

[0037] Example 1: Nanorod-shaped LiFePO was prepared by changing the order of precursor addition by using water as the reaction medium by the hydrothermal method 4 . In this embodiment, the iron salt is ferrous sulfate heptahydrate, the antioxidant is ascorbic acid, and the lithium salt is lithium hydroxide monohydrate.

[0038] Many problems faced by traditional methods are further solved only by changing the order of addition to prepare precursors. The method is: select 6.69g of lithium salt and dissolve it in 60mL of water. After the dissolution is complete, 4 mL of phosphoric acid (85wt.%) is added to it, and Li 3 PO 4 Suspension, where Li 3 PO 4 It is white precipitated nano-agglomerated particles. After the reaction was completed, 0.225 g of ascorbic acid and 14.6 g of iron salt were added thereto to finally form a blue slurry. The blue slurry was quickly transferred to a sealed reaction kettle, and hydrothermally reacted at 180° C. for 3 hours. Then separated to...

Embodiment 2

[0040] Example 2: Rod-shaped LiFePO prepared by changing the order of precursor addition and adding a certain amount of ethylene glycol 4 . The iron salt adopts ferrous sulfate heptahydrate, the antioxidant adopts ascorbic acid, and the lithium salt adopts lithium hydroxide monohydrate.

[0041] The method is: select 6.69g of lithium salt and dissolve it in 30mL of water so that the concentration of the lithium salt solution is 0.223gmL -1 . After the dissolution is complete, 4 mL of phosphoric acid (85wt.%) is added to it, and Li 3 PO 4 Suspension, where Li 3 PO 4 It is white precipitated nano-agglomerated particles. After the reaction was completed, 0.225 g of ascorbic acid and 14.6 g of iron salt were added thereto to finally form a blue slurry. Subsequently, a certain amount of ethylene glycol solution 60mL was added thereto, and after being uniformly mixed, it was quickly transferred to a sealed reaction kettle, and hydrothermally reacted at 180° C. for 3 hours. T...

Embodiment 3

[0043] Embodiment 3: the difference from embodiment 2 is that the synthesis temperature and reaction time used in the experiment are different. The prepared rod-shaped LiFePO 4 , with a diameter of 50-80nm and an aspect ratio of 1-8. In this embodiment, the iron salt is ferrous sulfate heptahydrate, the antioxidant is ascorbic acid, and the lithium salt is lithium hydroxide monohydrate.

[0044] The volume ratio of ethylene glycol: water in the ethylene glycol solution is 1:1. The hydrothermal conditions are: temperature 150° C., time 10 hours.

[0045] The obtained product is LiFePO 4 Simplex. The first discharge specific capacity at 0.1C charge and discharge rate reached 160mAh g -1 , and good cycle performance.

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Abstract

The invention relates to the field of lithium ion batteries, in particular to a method for greatly improving the excellent electrochemical performance of positive electrode materials LiFePO4 of low-temperature hydrothermal synthesized lithium ion batteries. The method solves the problems that the hydrothermal synthesized LiFePO4 with excellent electrochemical performance needs high temperature conditions and expensive surfactants, and the yield in unit volume is too low. According to the method, lithium salts, ferric salts and phosphoric acid are prepared into paste precursors in water according to a certain addition sequence and a certain mixture ratio, then, a certain number of organic solvents are added, and next, the nanometer LiFePO4 positive electrode materials with excellent electrochemical performance are prepared under the hydrothermal conditions. The LiFePO4 positive electrode materials with the excellent electrochemical performance can be prepared at lower temperature, so the pressure-proof performance requirement on a hydrothermal reaction kettle is greatly reduced. The method has the advantages that through changing the addition sequences of raw materials, the precursors are changed from the sticky state into the slurry state and are not sticky, so more raw materials can be fed into the reaction kettle, and the yield of LiFePO4 powder in the unit volume is greatly improved.

Description

technical field [0001] The invention relates to the field of lithium-ion batteries, in particular to a greatly improved low-temperature hydrothermally synthesized lithium-ion battery cathode material LiFePO 4 method for electrochemical performance. The method has low reaction temperature, lower requirements on the pressure resistance of the reactor, high product yield, excellent electrochemical performance, greatly improved production efficiency, and is suitable for industrial production. Background technique [0002] At present, the energy issue is one of the main issues affecting the future survival and development of human beings. Therefore, the development and utilization of new energy and environmental protection technology has become a very urgent issue. The green and environment-friendly lithium-ion secondary battery meets the demand in this respect. In recent years, lithium-ion secondary batteries have been widely used in portable electronic products and communica...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45B82Y40/00
Inventor 王晓辉秦学谢杰周延春
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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