Method for synthesizing graphene-doped nanometer manganese-rich lithium iron phosphate under conditions of normal pressure and water phase

Abstract

The invention discloses a method for synthesizing graphene-doped nanometer manganese-rich lithium iron phosphate under conditions of normal pressure and water phase. The method comprises the following steps: preparing lithium phosphate, preparing a graphene or graphene oxide water suspension, preparing a lithium phosphate and graphene or graphene oxide mixed suspension, preparing a divalent manganese salt and ferrite mixed solution, preparing graphene-doped or graphene oxide-doped nano manganese-rich lithium iron phosphate, and recycling lithium from a mother solution. Compared with the prior art, the method has the advantages that the method for synthesizing graphene-doped nanometer manganese-rich lithium iron phosphate under conditions of normal pressure and water phase is mild in reaction conditions and low in equipment cost; the prepared product is high in electrical property and capacity, good in rate capability, stable in batch and uniform and controllable in granularity; the lithium in the mother solution can be recycled, so that the production cost is lowered, and the requirement of industrialized production is met.

Description

technical field [0001] The invention relates to the preparation of positive electrode materials for lithium ion batteries, in particular to a method for synthesizing graphene-doped nano manganese-rich ferrous phosphate in an aqueous phase at normal pressure. Background technique [0002] As a cathode material for lithium-ion batteries, lithium iron phosphate is popular because of its safe olivine structure, low-cost raw materials, and environmental protection. It is considered to be one of the ideal cathode materials for lithium-ion batteries. At present, the methods for synthesizing lithium ferrous phosphate mainly include: high-temperature solid-phase method, solution-gel method, hydrothermal method, solvothermal method, solution co-precipitation method, etc. Among them, the main problem of the high-temperature solid-phase method is that the batch stability of the product is poor, which directly leads to the short-plate reaction of the battery pack; the precursor obtained ...

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Problems solved by technology

Among them, the main problem of the high-temperature solid-phase method is that the batch stability of the product is poor, which directly leads to the short-plate reaction of the battery pack; the precursor obtained by the sol-gel method and the solution co-precipitation method is not lithium iron phosphate, but more The mixture of various substances, the components of the mixture are difficult to be consistent, and the obtained precursor needs to be calcined at a high temperature again to obtain the lithium iron phosphate crystal, which makes the process long, the product consistency is poor, and the equipment investment is large; hydrothermal Although the method and the solvothermal method can directly obtain lithium ferrous phosphate crystals, they require high temperature and high pressure reaction equipment, and the investment is huge, which is not suitable for large-scale industrial production, and the pure lithium ferrous phosphate has low capacity and poor rate performance.