Method for preparing carbon coated phosphates positive pole material by super critical fluid

A carbon-coated phosphate and lithium-ion battery technology, which is applied in battery electrodes, circuits, electrode manufacturing, etc., can solve the problems of complex surface structure and large specific surface area, and achieve simple preparation process, uniform and dense carbon coating layer, The effect of easy operation

Inactive Publication Date: 2009-03-18
天津斯特兰能源科技有限公司
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  • Summary
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] In short, in the existing coating methods, due to the small particle size, large specific surface area and complex surface structure of lithium iron phosphate, uniform coating on the surface of lithium iron phosphate particles cannot be achieved.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] Example 1 500g lithium iron phosphate [LiFePO 4 ] The positive electrode material is placed in a high-pressure stirred reactor, and the carbon dioxide dissolved in 25g of polyvinyl alcohol is pumped into the reactor with a high-pressure pump, controlled at 30°C and 7.3Mpa, and stirred for more than 30 minutes, and then the supercritical fluid and The mixed slurry of active materials is quickly ejected from the expansion separation chamber through the nozzle to form a phosphate cathode material pre-coated with organic polymers. Putting the pre-coated positive electrode material into a high-temperature furnace, and roasting at a constant temperature at a set temperature for different times in a nitrogen atmosphere to crack the organic polymer material and form a uniform carbon coating layer on the surface of the phosphate positive electrode material, Then cooled to room temperature to prepare a uniform carbon-coated phosphate cathode material.

[0019] Table 1 Experiment...

Embodiment 2

[0021] Example 2 500g lithium iron phosphate [LiFePO 4 ] The positive electrode material is placed in a high-pressure stirred reactor, and the carbon dioxide dissolved in different organic polymer materials is pumped into the reactor with a high-pressure pump, controlled at 30°C and 7.3Mpa, and stirred for more than 30 minutes, and then the mixed slurry , quickly ejected through the nozzle in the expansion separation chamber to form a phosphate cathode material pre-coated with organic polymers. Put the pre-coated positive electrode material into a high-temperature furnace, and bake it at a set temperature of 800°C for 10 hours under a nitrogen atmosphere to crack the organic polymer material and form a uniform carbon coating on the surface of the phosphate positive electrode material layer, and then cooled to room temperature to obtain a uniform carbon-coated phosphate cathode material.

[0022] Table 2 Experimental conditions and results of Example 2

[0023] make ...

Embodiment 3

[0024] Example 3 500g lithium iron phosphate [LiFePO 4 ] The positive electrode material and different qualities of polyvinyl alcohol are placed in a high-pressure stirred reactor, and carbon dioxide is pumped into the reactor with a high-pressure pump, controlled at 30°C and 7.3Mpa, and stirred for more than 30 minutes, and then the mixed slurry , quickly ejected through the nozzle in the expansion separation chamber to form a phosphate cathode material pre-coated with organic polymers. Put the pre-coated positive electrode material into a high-temperature furnace, and bake it at a set temperature of 800°C for 10 hours under a nitrogen atmosphere to crack the organic polymer material and form a uniform carbon coating on the surface of the phosphate positive electrode material layer, and then cooled to room temperature to obtain a uniform carbon-coated phosphate cathode material.

[0025] Table 3 Experimental conditions and results of Example 3

[0026] make up

[...

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PUM

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Abstract

The invention discloses a process for preparing carbon-coated phosphate cathode material of a lithium ion battery through utilizing supercritical fluid, which comprises placing to-be-coated phosphate anode active material in a high-pressure stirred tank reactor, pumping supercritical fluid which dissolves with polymer solution into the reactor through a high-pressure pump, fully stirring under the condition of preset temperature and pressure to fully moisten the polymer solution and anode active substances, then fast spraying the mixed paste of supercritical fluid and active substances in an expansion separating chamber through nozzles, thereby making polymer solutes reach highly super-saturation state in a shorter time and grow on the surface of coated substances to form an even coating layer, and then conducting with high-temperature treatment under the non-oxidizing atmosphere to split off organic polymer material to form an even carbon-coated layer on the surface of the phosphate anode material.

Description

technical field [0001] The invention belongs to a method for modifying positive electrode materials of lithium ion batteries, in particular to a method for improving the conductivity of phosphate positive electrode active materials and preparing carbon-coated phosphate positive electrode materials for lithium ion batteries by using supercritical fluid. Background technique [0002] At present, great progress has been made in the negative electrode materials and electrolyte systems of lithium-ion batteries, while the development of positive electrode materials is relatively lagging behind, which seriously affects the powerization process of lithium-ion batteries. Its main performance is as follows: First, safety issues, the only commercial cathode material LiCoO 2 It is not stable enough, and it will decompose when overcharged and overheated, which may cause the battery to explode, which is especially prominent in power batteries; the second is the cost issue. The global coba...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/04H01M4/1397
CPCY02E60/10
Inventor 段镇忠
Owner 天津斯特兰能源科技有限公司
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