Nano lithium iron phosphate/graphene oxide composite material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of electrode materials, and particularly relates to a nano lithium iron phosphate / graphene oxide composite material and a preparation method thereof. The preparation method comprises the following steps of 1, mixing and stirring graphene oxide dispersion liquid and nano lithium iron phosphate to obtain mixed liquid; 2) heating and concentrating the mixed solution to obtain a viscous substance; 3) dialyzing the viscous substance; and 4) carrying out vacuum drying on the dialyzed substance to obtain the nano lithium iron phosphate / graphene oxide composite material. In addition, the invention also relates to an application of the nano lithium iron phosphate / graphene oxide composite material in a lithium ion battery. Compared with the prior art, thepreparation method provided by the invention has the advantages that the reaction conditions are easy to control, the sufficient mixing of graphene is facilitated, the prepared composite material hasgood conductivity and high capacity, and the rate capability and cycle performance of the lithium ion battery are favorably improved.

Description

technical field [0001] The invention belongs to the technical field of electrode materials, and in particular relates to a nano-lithium iron phosphate / graphene oxide composite material and a preparation method and application thereof. Background technique [0002] Lithium iron phosphate with an olivine structure is regarded as one of the most promising cathode materials for power batteries. It has many advantages such as abundant raw material sources, safety and environmental protection, and stable cycle performance, but its electronic and ionic conductivity is low due to its structural limitations. , resulting in a lower actual capacity. [0003] The composite of graphene and lithium iron phosphate can obviously improve its electrochemical performance. At present, the methods for preparing lithium iron phosphate / graphene oxide composite cathode materials are mainly liquid-phase method and solid-phase method. Among them, the liquid phase method can control the particle siz...

AI Technical Summary

Problems solved by technology

In the preparation process, the molar ratio of raw materials in the solvothermal reaction and the reaction temperature need to be strictly controlled, and a large amount of ethylene glycol is required as a solvent in the reaction process, which not only increases the cost of raw materials, but also causes a lot of waste of raw materials, making it difficult to realize industrial production

The powder particles prepared by the solid-state method have no agglomeration, good filling performance, low cost, large output, and simple preparation process, but the obtained LiFePO 4 / Graphene composite materials are all granular, which will affect the transmission rate of ions, and the capacity will easily decay during high-current discharge; at the same time, there are problems such as uneven dispersion and easy agglomeration of graphene, which leads to the conductivity and rate performance of the composite material. and cycle performance may be affected. At the same time, the preparation process has the disadvantages of high energy consumption, low efficiency, powder is not fine enough, and impurities are easily mixed

Images