Production method of lithium iron phosphate

A technology of lithium iron phosphate and its production method, which is applied in the field of preparation of cathode materials for lithium-ion batteries, and can solve problems such as poor electrical conductivity, restrictions on large-scale application, and poor battery stability

Active Publication Date: 2014-03-12
YIYANG SHENGLI CHEM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the electrical conductivity of lithium iron phosphate cathode material is very poor, the electric capacity is less than 125mAh/g, and the stability of the produced battery is poor. Use a half-cell to assem

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] (1) By weight, according to the ratio of iron phosphate: lithium carbonate: silver nitrate: deionized water = 1.0: 0.2~0.22: 0.001~0.002: 0.5~0.6, add the above raw materials into the ball mill and mill for 3 hours to 4 hours to make the material Mix well;

[0018] In this embodiment, ferric phosphate: lithium carbonate: silver nitrate: deionized water = 18 kg: 3.6 kg: 0.018 kg: 9 kg were added to a ball mill and ball milled for 4 hours to fully mix the materials.

[0019] The iron phosphate described in step (1) is iron phosphate dihydrate, the content of ferric iron is ≥ 29.70%, and the tap density is 1.13 g / cm 3 ~1.59g / cm 3 , Fe:P=0.99:1, the particle size appearance is spherical, the particle size distribution range is 0.1μm ~ 10μm, 3μm≤D50≤5μm, the maximum particle size is not more than 10μm, and its sulfate, calcium, magnesium, sodium, potassium, copper , nickel, cadmium, lead, zinc, chromium, and chlorine concentrations are all less than 10ppm. Described lithi...

Embodiment 2

[0029] In this embodiment, ferric phosphate: lithium carbonate: silver nitrate: deionized water = 18 kg: 3.6 kg: 0.018 kg: 9 kg and 2 kg of reducing agent sucrose were added to a ball mill and ball milled for 4 hours to fully mix the materials. In step (3), the reducing agent in this embodiment is sucrose in organic sugars. The rest are the same as embodiment 1.

[0030] The prepared lithium iron phosphate product is detected by an X-ray diffractometer (XRD, Rigaku, Japan), and it can be seen that the lithium iron phosphate is a pure phase. The above-mentioned lithium iron phosphate was assembled into a button-type battery using a half-cell, and the battery was charged and discharged at a rate of 0.5C. The average discharge mass specific capacity was 151mAh / g, the first charge specific capacity was 167 mAh / g, and the first discharge specific capacity It is 153 mAh / g, the cycle Coulombic efficiency is 91.2%, the charge constant current ratio is 98.7%, the discharge median volt...

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Abstract

The invention discloses a production method of lithium iron phosphate with stable product quality and performances. The production method is characterized by comprising the following steps: adding raw materials into a ball mill for ball milling according to the proportion of iron phosphate to lithium carbonate to silver nitrate to deionized water of 1.0: (0.2-0.22): (0.001-0.002): (0.5-0.6), filtering, drying, reducing, calcining and crushing to prepare the nano-scale lithium iron phosphate taking silver oxide as a conductive agent. The method disclosed by the invention is simple and feasible, the synthesized lithium iron phosphate is pure phase and has good electrochemical performances and stable quality, the electrical gram capacity is above 150mAh/g and the tap density is 1.65g/cm<3>-1.70g/cm<3>. The lithium iron phosphate is assembled into a button cell by using a half-cell, charge-discharge testing is performed on the cell at the rate of 0.5C, the average discharge mass specific capacity is more than 150mAh/g, the cyclic coulombic efficiency is more than 95.0%, the charge constant current ratio is more than 98%, the discharge mean voltage is more than 3.4V, and the capacity retention rate after 100 cycles is more than 97.0%.

Description

technical field [0001] The invention relates to a preparation method of a positive electrode material of a lithium ion battery, in particular to a production method of lithium iron phosphate. Background technique [0002] In order to meet the society's requirements for power batteries, electric vehicles and various portable appliances, as well as new chemical power sources, the demand for lithium-ion batteries is increasing. At present, due to the toxicity of lithium cobaltate, the poor cycle performance and high temperature performance of lithium manganate, and the difficulty in the preparation of lithium nickelate, the application of these materials has been greatly restricted in the cathode materials of lithium ion batteries. Lithium iron phosphate with an olivine structure is an excellent new type of cathode material for lithium-ion batteries. Its theoretical specific capacity is up to 170mAh / g, and the charge and discharge voltage platform is about 3.4V. It has the adv...

Claims

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Application Information

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IPC IPC(8): H01M4/58H01M4/62C01B25/45
CPCC01B25/45H01M4/5825H01M4/624Y02E60/10
Inventor 邓超群唐磊
Owner YIYANG SHENGLI CHEM IND
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