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

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...

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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 and lithium salt as raw materials, and using liquid phase synthesis The process directly synthesizes lithium iron phosphate materials with excellent electrochemical properties, avoiding the shortcomings of uneven mixing in other synthesis methods