Method for producing carbon coated nano stage lithium iron phosphate by precipitation

A technology of lithium iron phosphate and carbon coating, which is applied in the direction of electrode manufacturing, electrical components, battery electrodes, etc., can solve the problem of uneven mixing, and achieve the effect of simple process, excellent electrochemical performance, and easy operation of the process

Inactive Publication Date: 2009-03-25
南京海泰纳米材料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0018] In view of the shortcomings of the above method, the present invention provides a method for preparing carbon-coated nano-scale lithium iron phosphate by precipitation method, directly using ferrous salt, phosphorus-containing compound...

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Example 1: LiFePO 4 Synthesis of / C

[0035] Add 11.50 grams (0.1 mole) ammonium dihydrogen phosphate after 27.8 grams (0.1 moles) of ferrous sulfate, 300 grams of deionized water are mixed, add 6 grams of citric acid after stirring again, and add ammoniacal liquor to control pH5. 5. Stir the reaction in a container at 30°C for 5 hours, and after standing for 15 hours, filter and wash the precipitate.

[0036] Add 200 grams of deionized water, 5 grams of glucose, and 4.2 grams (0.1 mole) of lithium hydroxide to the precipitate, mix well, stir and react again in a container at 30°C for 4 hours, and dry at 100°C Moisture, crush the product, raise the temperature at a heating rate of 10°C / min under the protection of nitrogen, and burn at a constant temperature of 725°C for 600 minutes, then cool to room temperature with the furnace, and obtain lithium iron phosphate nano-scale products after crushing.

[0037] Make batteries and test: use oily system to coat the synthesi...

Embodiment 2

[0039] Example 2: LiFePO doped with metal element Mg 4 Synthesis of / C

[0040] After stirring and mixing 27.8 grams (0.1 moles) of ferrous sulfate and 400 grams of deionized water, add 11.50 grams (0.1 moles) of ammonium dihydrogen phosphate, and add 0.246 grams (0.001 moles) of MgSO after stirring again 4 .7H 2 O, continue to stir and add 4 grams of citric acid, and add ammonia water to control pH7.2, stir and react in a container at 50°C for 2 hours, and after standing for 5 hours, filter and wash the precipitate.

[0041] Add 600 grams of deionized water, 5 grams of glucose, and 4.16 grams (0.099 moles) of lithium hydroxide to the precipitate, mix well, stir and react again in a container at 50°C for 4 hours, and dry at 90°C Moisture, crush the product, raise the temperature at a heating rate of 10°C / min under the protection of nitrogen, and burn at a constant temperature of 650°C for 600 minutes, then cool to room temperature with the furnace, and obtain lithium iron ph...

Embodiment 3

[0042] Embodiment 3: LiFePO doped with metal elements Mn and W 4 Synthesis of / C

[0043] With 0.246 gram (0.001 mole) MgSO among the embodiment 2 4 .7H 2 O replaced by 0.0017 g (O.00001 mol) MnSO 4 .H 2 O and 0.13 gram (0.00099 moles) ammonium tungstate, other preparation proportioning and operating steps are with embodiment 2, make the lithium iron phosphate nanoscale product of metal element Mn and W doping.

[0044] Prepare the button battery according to the method of Example 1, and test its battery cycle performance. The average particle size of the product is 70nm, and the tap density can reach 1.5g / cm 3 , the first discharge specific capacity at room temperature can reach 150mAh / g.

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Abstract

The invention discloses a precipitation method for preparing nanometer level iron phosphate lithium coated with carbon. The method comprises the following steps: firstly, weighing iron salt, deionized water and a compound of metallic elements; after the stirring and the mixing are performed, adding a phosphorous compound and citric acid diluted with water to the mixture; after the stirring is performed again, adding a precipitation agent to the mixture and controlling to the neutrality; stirring to react in a container, and after the static placement, respectively adding the deionized water, a carbon source and lithium salt to mix uniformly after the precipitate is filtered and washed; stirring again to react, and drying the water at 30 to 160 DEG C and warming up at the heating rate under the protection of non-oxidized gas after a product is crashed; baking at a constant temperature of 450 to 850 DEG C, cooling down to a room temperature at a cooling rate or with a stove, and finally obtaining the nanometer level ferric phosphate lithium coated with the carbon after crashing is performed. The precipitation method has the advantage that the raw material cost and the processing cost are low because bivalent iron is taken as the raw material. The iron phosphate lithium prepared by using the process has the characteristics of good physical processing performance and good electrochemistry performance, and is suitable for industrialized production.

Description

technical field [0001] The invention relates to a method for preparing battery materials, more specifically, a method for preparing carbon-coated nanoscale lithium iron phosphate by liquid phase precipitation doped with metal elements. Background technique [0002] LiFePO was first reported since 1997 4 Since it has the function of deintercalating lithium, the olivine phosphate lithium intercalation material LiMPO 4 (M:Mn, Fe, Co, Ni), as a promising cathode material for lithium-ion batteries, has attracted much attention. LiFePO with a theoretical capacity of 170mAh / g 4 , with its rich iron resources, low price, excellent thermal stability and environmental friendliness, is considered to be the most promising cathode material for lithium-ion batteries. [0003] At present, the methods for synthesizing lithium iron phosphate include high-temperature solid-state reaction method, liquid-phase co-deposition method, sol-gel method, hydrothermal method, liquid-phase redox meth...

Claims

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Application Information

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IPC IPC(8): H01M4/04H01M4/1397
CPCY02E60/10
Inventor 周海燕姜华张玉梅杜彩侠张翠芬资利云
Owner 南京海泰纳米材料有限公司
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