Spherical micro-nano ferric phosphate/carbon composite material and preparation method thereof

Abstract

The invention discloses a spherical micro-nano ferric phosphate / carbon composite material and a preparation method thereof. The preparation method comprises the following steps: (1) preparing aqueous solution of ferric salt and a phosphorous compound, wherein the mole ratio of the ferric element to the phosphorus element is (0.9-1.2): 1, and the solution concentration is 0.2-5 mol / L; (2) dispersing a high polymer material binder in the solution in the step (1), wherein the dosage of the high polymer material binder is 0.5-90 wt / % of the ferric salt; (3) adding the solution prepared in the step (2) into a reaction still, continuously adding alkali solution to ensure that the pH in the reaction still is kept in 2-4, and reacting at a temperature of 20-90DEG C for 1-60 hours to obtain a crystal water-containing spherical micro-nano ferric phosphate / carbon composite material; and (4) under an inert atmosphere, roasting the spherical micro-nano ferric phosphate / carbon composite material prepared in the step (3) at a temperature of 300-800DEG C for 3-12 hours, and cooling to obtain the product. According to the preparation method, the coating of carbon materials is realized, and a crucial role is played in subsequently preparing high-density high-performance lithium ion battery LiFePO4 anode materials.

Description

Technical field [0001] The invention belongs to the technical field of lithium ion batteries, in particular a spherical micro-nano iron phosphate / carbon composite material and a preparation method thereof. Background technique [0002] Iron Phosphate (FePO 4 ) Is a monoclinic crystal with a white or off-white powder appearance. It was initially widely used in agriculture, ceramic glass, steel and surface passivation, and later research found FePO 4 It also has applications in the fields of oxidative dehydrogenation catalysis, ion exchange and electrochemical performance. In the application of electrochemistry, FePO 4 Can be used as LiFePO for preparing lithium ion batteries 4 The framework material of the cathode material. Research shows that using FePO 4 Preparation of LiFePO as a precursor 4 Cathode materials have the following advantages: (1) FePO 4 Has a fixed Fe / P ratio, so it is easier to obtain pure LiFePO 4 Cathode material; (2) FePO 4 And LiFePO 4 Has a similar crystal s...

AI Technical Summary

Problems solved by technology

[0003] Spherical lithium iron phosphate micro-nanostructure materials meet the design requirements of high energy density and high rate performance lithium-ion batteries, but most of the existing technologies directly use iron salts, phosphates, and carbon materials as raw materials to prepare lithium iron phosphate. On the one hand, the mixing degree of the reaction raw materials is uncontrollable, on the other hand, the prepared LiFePO 4 Cathode materials are not spherical

Most of the existing carbon coating technology is to add carbon source when the raw materials are mixed. Although the process is simple, it cannot guarantee the complete carbon coating of the material, and it is usually a carbon coating, which has no obvious effect on material modification.

Currently, the FePO 4 The production process is relatively rare and immature

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