Preparation method of lithium iron phosphate monocrystalline nanorods

Abstract

The invention relates to a preparation method of lithium iron phosphate monocrystalline nanorods. The method is characterized in that: mixed solvent required by solvothermal reaction is constituted by ethylene glycol and water at volume ratio of 3:1-1:3; and polyethylene glycol is introduced to influence crystal nucleus formation and crystal growth, and realize solvothermal synthesis of lithium iron phosphate monocrystalline nanorods. The preparation method includes dissolving antioxidant ascorbic acid in the mixed solvent of ethylene glycol and water; sequentially dissolving phosphoric acid and ferrous sulfate hexahydrate in the mixed solvent; dropwise adding lithium hydroxide dissolved in ethylene glycol and water into the above solution containing phosphoric acid, ferrous sulfate and ascorbic acid; mixing with appropriate amount of polyethylene glycol; sealing in a reaction kettle system; and performing solvothermal reaction under high temperature 160-240 DEG C and high pressure, to obtain lithium iron phosphate monocrystalline nanorods. The product has stable quality, high purity and good particle dispersivity, which facilitates lithium ion diffusion and improves electrochemical performance of lithium ion battery. The preparation method has the advantages of simple preparation process, easy control, no pollution, low cost, and easy mass production.

Description

technical field [0001] The invention relates to a preparation method of lithium iron phosphate single crystal nanorods, belonging to the fields of inorganic non-metallic materials and energy storage battery materials. Background technique [0002] Lithium-ion battery, as a high-performance rechargeable green power source, has been widely used in various portable electronic products and communication tools in recent years, and has been gradually developed as a power source for electric vehicles, thereby promoting its development towards safety, environmental protection, Development in the direction of low cost and high specific energy. Among them, the development of new electrode materials, especially positive electrode materials, is extremely critical. At present, the widely studied cathode materials for lithium-ion batteries focus on transition metal oxides of lithium such as LiMO with a layered structure. 2 (M=Co, Ni, Mn) and LiMn with spinel structure 2 o 4 . However...

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Problems solved by technology

The study found that the lithium iron phosphate material has a moderate working voltage (3.4V), a good platform, a theoretical capacity of 170mAh / g, excellent cycle performance, and low cost. Its high energy density and high safety performance make it suitable for use in power lithium-ion batteries It has outstanding application prospects, but its disadvantages are its poor conductivity and slow diffusion rate of lithium ions, which has a great relationship with the microscopic morphology of lithium iron phosphate cathode materials

At present, the academic community is still in the stage of proposing hypotheses about the specific mechanism and process of lithium iron phosphate deintercalation lithium, which is difficult to verify through experiments.

At present, the industrialized lithium iron phosphate cathode materials are basically synthesized by high-temperature solid-state method, and the microscopic morphology is spherical. According to the literature search, the microscopic morphology of lithium iron phosphate prepared in the laboratory is still difficult to control, and it is concentrated in the diamond-shaped block. And spherical, such as the positive electrode material prepared by Kang Byoungwoo et al. high temperature solid phase method (nature. 2009,458,190.), or the lithium iron phosphate prepared by Yang SF et al. by hydrothermal method (ELECTROCHEMISTRY COMMUNICATIONS. 2001,3,505.) are all Spherical, none of the above is conducive to improving the energy density of lithium-ion batteries, and makes it difficult to study the dynamic changes in the crystal structure of cathode materials through in-situ TEM and other observation methods

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