A kind of lithium manganese iron phosphate composite material and its preparation method and lithium ion battery

Abstract

The invention discloses an iron, lithium and manganese phosphate composite material, a method for preparing the same and a lithium ion battery. The method includes dispersing lithium sources, iron sources, manganese sources and phosphorus sources in deionized water; adding citric acid into the deionized water to obtain sol; stirring the sol to form gel, drying and grinding the gel and then pre-sintering the gel to form LiFe<0.5-x>Mn<0.5+x>PO<4>; adding vanadium sources into oxalic acid solution, then adding phosphorus sources, lithium sources and the LiFe<0.5-x>Mn<0.5+x>PO<4> into the oxalic acid solution, uniformly stirring the vanadium sources, the phosphorus sources, the lithium sources, the LiFe<0.5-x>Mn<0.5+x>PO<4> and the oxalic acid solution to obtain mixtures, dropwise adding ethylene glycol and ethylenediamine into the mixtures and carrying out reaction to obtain precursors; drying the precursors under vacuum conditions, uniformly grinding the precursors and then sintering and cooling the precursors to obtain the iron, lithium and manganese phosphate composite material YLiFe<0.5-x>Mn<0.5+x>PO<4> / (1-Y)Li<3>V<2>(PO<4>)<3> / C. The X is larger than or equal to 0.1 and is smaller than or equal to 0.4, and the Y is larger than or equal to 0.5 and is smaller than 1. The iron, lithium and manganese phosphate composite material, the method and the lithium ion battery have the advantages that dissolution of manganese in the iron, lithium and manganese phosphate composite material can be relieved, and the ionic conductivity and the electronic conductivity can be improved.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a lithium manganese iron phosphate composite material, a preparation method thereof and a lithium ion battery. Background technique [0002] Lithium-ion batteries are more and more widely used in the field of new energy vehicles, which put forward higher requirements for the safety and energy density of lithium-ion batteries. The theoretical capacity of lithium manganese iron phosphate is 171mAh / g, which has a high safety similar to lithium iron phosphate, and has a higher potential than lithium iron phosphate (4.1V vs Li + / Li), which can meet the high energy density requirements of lithium-ion batteries, and has attracted extensive attention from technicians in the lithium battery industry. [0003] Lithium manganese iron phosphate also has its own shortcomings, which affect its practical large-scale use. The electronic conductivity of lithium manganese iron phosphate is ...

AI Technical Summary

Problems solved by technology

[0005] In view of the above deficiencies in the prior art, the object of the present invention is to provide a lithium manganese iron phosphate composite material and its preparation method and lithium ion battery, aiming at solving the problem of Mn in the existing charge and discharge cycle. 3+ Dissolution of ions and problems with low ion diffusivity and electronic conductivity