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LiFePO4 composite type positive pole material preparation method

A technology of positive electrode materials and composite materials, which is applied in the field of lithium battery positive electrode materials, can solve the problems of low electronic conductivity ion diffusion rate, inability to form electronic conduction, and the influence of intercalation and detachment movement, etc., to achieve high rate, good rate, and increase energy density and the effect of pole piece processability

Active Publication Date: 2013-02-20
NINGBO RONBAY LITHIUM BATTERY MATERIAL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since there is no consecutive MO 6 co-edge octahedral network, it can not form electronic conduction; at the same time, due to the PO between the octahedron 4 The tetrahedron confines the change in lattice volume, thus making the Li + The intercalation and detachment movement is affected, resulting in LiMPO 4 The material has an extremely low electronic conductivity (approximately 10 -9 S / cm) and ion diffusion rate
Due to the extremely low electronic conductivity and ion diffusion rate during high-rate charge and discharge, the electrochemical interface of the material is severely polarized, and the electrochemically inert region spreads, which increases the proportion of dead lithium in the material, which makes it extremely stable during high-rate and high-current charge and discharge. Poor electrochemical performance

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0011] Nasicon Lithium Fast Ion Conductor Li 3 Fe 2 (PO 4 ) 3 Crystal nuclei and LiFePO 4 Composite material for / C shell.

[0012] The preparation steps are as follows:

[0013] LiOH·H 2 O, NH 4 h 2 PO 4 , Fe(NO 3 ) 3 9H 2 O is dissolved in secondary water respectively, to Fe(NO 3 ) 3 A certain amount of citric acid is added to the solution, and the ratio of citric acid to metal ions is 1:1. Then, while stirring, the LiOH·H 2 O, NH 4 h 2 PO 4 Slowly add the solution into the above-mentioned iron salt solution, adjust the pH to 3-5 with dilute ammonia water, stir in a water bath at 60-80°C for 4-6 hours to form a dark green sol, and dry at 120°C to obtain a xerogel. Cool and grind the dry gel, then pretreat it in a common horse-boiling furnace at 300-600°C for 4-8 hours, cool and grind it to obtain Nasicon lithium fast ion conductor Li with good crystallinity 3 Fe 2 (PO 4 ) 3 . Then with the above-prepared Li 3 Fe 2 (PO 4 ) 3 For the crystal nucleus,...

Embodiment 2

[0016] Nasicon Lithium Fast Ion Conductor Li 3 V 2 (PO 4 ) 3 Crystal nuclei and LiFePO 4 Composite material for / C shell.

[0017] The preparation steps are as follows:

[0018] Respectively weigh the LiOH·H according to the stoichiometric ratio 2O, NH4VO3 is dissolved in secondary water, and a certain amount of citric acid is weighed and dissolved in secondary water according to the ratio of citric acid to metal ions of 1:1. Then various aqueous solutions were stirred with H 3 PO 4 Mix, adjust the pH to 3-6 with dilute ammonia water, stir in a water bath at 70-90°C for 4-8 hours to form a sol, and dry at 120°C to obtain a gel. Cool and grind the dry gel, then pretreat it in a horse-boiler furnace at 300-600°C for 4-8 hours, cool and grind it to obtain Nasicon lithium fast ion conductor Li with good crystallinity 3 V 2 (PO 4 ) 3 . Then with the above-prepared Li 3 V 2 (PO 4 ) 3 For the crystal nucleus, add a certain amount of FeC 2 o 4 2H 2 O, NH 4 h 2 PO...

Embodiment 3

[0021] Nasicon Lithium Fast Ion Conductor Li 3 In 2 (PO 4 ) 3 Crystal nuclei and LiFePO 4 Composite material for / C shell.

[0022] The preparation steps are as follows:

[0023] First weigh a certain amount of lithium hydroxide and indium nitrate and dissolve them in secondary water respectively, then weigh a certain amount of citric acid and dissolve them in secondary water according to the ratio of citric acid to metal ions of 1:1. Then various aqueous solutions were stirred with H 3 PO 4 Mix, adjust the pH to 4-6.5 with dilute ammonia water, stir in a water bath at 70-90°C for 4-8 hours to form a sol, and dry at 120°C to obtain a gel. Cool and grind the dry gel, then pretreat it in a horse-boiler furnace at 300-600°C for 4-8 hours, cool and grind it to obtain Nasicon lithium fast ion conductor Li with good crystallinity 3 In 2 (PO 4 ) 3 . Then with the above-prepared Li 3 In 2 (PO 4 ) 3 For the crystal nucleus, add a certain amount of FeC 2 o 4 2H 2 O, N...

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Abstract

The invention relates to a LiFePO4 composite type positive pole material and a preparation method thereof. The invention adopts the essentials that the LiFePO4 composite type positive pole material consists of a Nasicon lithium superionic conductor crystal nucleus and an LiFePO4 / C shell. The preparation method comprises the following steps of: preparing a Nasicon lithium superionic conductor by adopting a sol-gel method; with the Nasicon lithium superionic conductor as a crystal nucleus, adding a certain quantity of FeC2O4.2H2O, NH4H2PO4, Li2CO3 and glucose to an alcohol medium, ball milling for 4-8 hours for uniformly mixing, and drying; and sintering at 400-600 DEG C for 4-8 hours in an inert atmosphere; sieving and then sintering at 600-800 DEG for 10-24 hours in the inert atmosphere; and cooling and porphyrizing to obtain the like spherical LiFePO4 composite type positive pole material. The LiFePO4 composite type positive pole material has the advantages of good conductivity, highmultiplying power and good heavy-current charge / discharge properties; and the like spherical structure improves the energy density and the pole piece processing property of the material.

Description

technical field [0001] The present invention relates to lithium battery cathode material, is a kind of LiFePO 4 A method for preparing a composite cathode material. Background technique [0002] With the continuous progress of society, lithium-ion batteries play an important role in many fields, such as portable electronic products, automobiles, home appliances, and energy storage. However, with the continuous updating of industries in various fields, the requirements for lithium-ion batteries in terms of energy density, safety, and cycle life are also getting higher and higher. Most of the existing commercial lithium-ion battery cathode materials are LiCoO 2 , but its security concerns inhibit its wider application. [0003] LiFePO 4 It is non-toxic and has good cycle stability, making it an ideal candidate for the cathode material of secondary lithium-ion batteries. It and LiCoO 2 In comparison, it has high theoretical specific capacity (170mAh / g), low price and good...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/136H01M4/1397
CPCY02E60/12Y02E60/122Y02E60/10
Inventor 宋翠环叶劲袁徐俊
Owner NINGBO RONBAY LITHIUM BATTERY MATERIAL CO LTD