A kind of synthetic method of graphene in-situ nucleation lithium iron phosphate

Abstract

The invention discloses a method for synthesizing graphene in-situ nucleation lithium iron phosphate, the steps of which include (1) weighing Fe(OH) 2 (2) Add phosphoric acid, LiOH and graphene oxide into deoxygenated water, and ultrasonically vibrate to form a modified graphene oxide suspension; (3) Fe(OH) 2 and reducing agent are added to the modified graphene oxide suspension to form a mixed solution; (4) the mixed solution obtained in step (3) is added to the reaction kettle, and an inert gas is introduced, heated and kept warm, cooled to room temperature, filtered, and dried to obtain Lithium iron phosphate for in situ nucleation of graphene. The graphene in-situ nucleated lithium iron phosphate prepared by the method has excellent discharge performance in the range of 20-50°C.

Description

technical field [0001] The invention relates to the field of positive electrode materials for lithium ion batteries, in particular to a method for synthesizing graphene in-situ nucleated lithium iron phosphate. Background technique [0002] In recent years, the application of lithium-ion batteries in the field of new energy has attracted more and more attention. Subsequently, as one of the core parts of lithium-ion batteries, cathode materials have become a research hotspot. The lithium iron phosphate material has the advantages of wide sources, low cost, low toxicity, easy recycling, good safety performance, long service life and high specific capacity, and is currently one of the most popular and reliable candidate cathode materials. [0003] There are many preparation methods for lithium iron phosphate, mainly including solid phase method, hydrothermal method, sol-gel method and co-precipitation method. However, no matter which method is used as a lithium iron phosphate ...

AI Technical Summary

Problems solved by technology

The above carbon coating methods all have the following defects: ① It is difficult for carbon to form a uniform coating layer on the surface of lithium iron phosphate particles, the surface structure of the coated elemental carbon and oxide is complex, the interface resistance is large, and the rate charge and discharge capacity will be large The amplitude decreases, and the improvement of the conductive behavior of lithium iron phosphate is limited, which affects its electrochemical performance; ②Carbon coating will greatly reduce the tap density of raw material lithium iron phosphate 3 ;③ High temperature calcination is required, high energy consumption

It can be seen from the above two preparation processes that the final product needs to be carbonized at a high temperature (about 700 degrees in the traditional method), resulting in increased cost and uneven carbonization. Decrease, affecting its electrochemical performance

And carbon coating will greatly reduce the tap density of raw material lithium iron phosphate 3

[0005] In addition, it is well known that the low temperature performance of lithium iron phosphate batteries is worrying

Although people have improved ion and electronic conductivity through various methods, such as doping lithium, iron, and even phosphoric acid, controlling the effective reaction area by improving the particle size and morphology of primary or secondary particles, and adding additional conductive materials. However, the low-temperature performance of lithium iron phosphate materials is still inferior to other positive electrode materials such as lithium manganate

The reason is that the low-temperature performance of lithium iron phosphate has a relatively large attenuation, and the battery consistency is poor at low temperatures.

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