Method for preparing ferric phosphate lithium anode material combining solid and liquid

Abstract

A method for preparing a lithium iron phosphate anode material through solid-liquid combination comprises the following steps that a lithium source compound, an iron source compound, a phosphoric acid and phosphorus source compound and a small amount of carbonic organic precursor are weighed in proportion and mixed evenly, and then dried at a temperature of between 80 and 120 DEG C; the dried mixture undergoes ball milling inside a star-type ball-milling tank for 10 to 60 minutes so as to obtain a precursor powder material; the precursor powder material undergoes sweeping in the inert atmosphere or the reducing atmosphere for 3 to 5 minutes and then is sealed; the precursor powder material is heated to 400 to 800 DEG C at a heating rate of between 1 and 30 DEG C / min, and the temperature is maintained for 3 to 8 hours; and finally, the material is cooled down to room temperature, and is crushed to prepare lithium iron phosphate powder. Due to adopting solid-liquid combined raw materials, the method not only ensures that the raw materials are mixed more evenly, but also provides effective reducing atmosphere to synthesize the anode material with excellent electrochemical property during later sintering; moreover, a high-temperature solid-liquid combination method is adopted to reduce reaction temperature, reaction time and production cost.

Description

technical field [0001] The invention relates to a preparation method of a positive electrode material of a lithium battery, in particular to a method for preparing a positive electrode material lithium iron phosphate by using a compound phosphorus source compound combined in a solid phase and a liquid phase. Background technique [0002] With the increasing popularity of various portable electronic products, the battery as a portable power supply device has attracted increasing attention. my country has become a big country in battery production and consumption. The environment has caused great pollution. Facing the increasingly stringent requirements for environmental protection in the world, the development of green energy is imminent. High-performance rechargeable green lithium-ion secondary batteries have been widely used in various portable electronic products and communication tools in recent years, and have been gradually developed as power sources for electric vehicl...

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Problems solved by technology

Wherein solid-phase synthesis method is the most mature method, and this method is simple and convenient, easy to operate, as the preparation LiFePO disclosed in Chinese patent (CN1255888C) 4 The raw material phosphorus sources used in the method are mainly iron phosphate and lithium phosphate, and the raw materials are all solid, and the production method is solid-phase synthesis; the pure solid-phase method reactants are usually mixed unevenly, the particles of the product are large, and there is still a cost High problem; the liquid-phase co-deposition method is to co-precipitate ferrous phosphate and lithium phosphate precursors from the solution under certain conditions, and roast the precursors at 650-800 ° C to obtain lithium iron phosphate. The materials obtained by this method The electrochemical performance is good, but the whole process needs to be carried out in a nitrogen protective atmosphere, and the operation is more complicated

Chinese patent (CN1208241C) adopts precipitation method to prepare LiFePO 4 , the precipitation method needs to be filtered during the preparation process, the process is more complicated and the cost is higher

The liquid phase combination method disclosed in the Chinese patent (CN100395907C) is to participate in the raw materials of the reaction, the lithium source, the iron source and the phosphorus-containing chelating agent reaction, and the used iron source lithium source must be dissolved in the reaction solution. Expensive (cheating agent raw materials are expensive), which increases the preparation cost, and there are few types of raw materials available, and a large amount of nitrogen oxides will be produced during the sintering process, which will cause large pollution and is not conducive to environmental protection

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