Method for preparing iron oxalate

Abstract

The present invention discloses a method for preparing ferrous oxalate, which belongs to the technical field of powdered material preparation. The aim of the invention is to provide a preparation method of ferrous oxalate which is high in purity, controllable in granularity, even in grain size, and high in conductivity. The method comprises the following steps of locating ferrous sulfate into dilute sulphuric acid, adding scrap iron with stirring, and obtaining a ferrous sulfate solution after suction filtration; dissolving oxalic acid or/and ammonium oxalate in distilled water with stirring and heating, and obtaining a mixed solution of oxalic acid or/and ammonium oxalate through suction filtration after dissolution; and, slowly adding the ferrous sulfate solution into oxalic acid solution, keeping the temperature, stirring, separating ferrous sulfate from the original synthetic solution after keeping stand, and obtaining ferrous oxalate powder through washing and drying. The ferrous oxalate prepared by the preparation method is a powder with a medium grain diameter of between 0.5 and 80 mu m. The granularity is completely controllable. The product purity is greater than 99.0 percent. The conductivity is high. The electrochemical performance of the ferrous phosphate salt composite material is largely improved. The conductivity of lithium iron phosphate is improved by 5 orders of magnitude.

Description

technical field [0001] The invention relates to a preparation method of ferrous oxalate, belonging to the technical field of powder material preparation. Background technique [0002] As a chemical raw material, ferrous oxalate is widely used in the production of ceramics, glass, and photosensitive materials. In addition, it is especially used to prepare the iron source of lithium iron phosphate, the preferred positive electrode material for power batteries. As a green high-energy battery, lithium-ion batteries have many advantages such as high voltage, high energy density, good cycle performance, small self-discharge, no memory effect and wide working range. They are widely used in mobile phones, notebook computers, digital cameras and other emerging industries. IT products. In addition, in terms of electric vehicles, electric tools, automotive 42V batteries, and large photovoltaic energy storage batteries, traditional lead-acid batteries have also begun to be gradually re...

AI Technical Summary

Problems solved by technology

However, the existing ferrous oxalate cannot meet the requirements for preparing high-quality ferric phosphate, because it has low purity, uneven particle size distribution, and especially unstable and not single crystal forms, which are orthorhombic, monoclinic and triclinic The mixed crystal form of the crystal system, in the production process of lithium ferrous phosphate, the physical appearance of the raw material has a great influence on the finished product, so the ferrous phosphate material prepared by the existing ferrous oxalate has poor appearance, The tap density of the prepared lithium iron phosphate powder is low, and the current commercially available materials are lower than 1.2g / cm 3 , which is only one-third of its true density, resulting in a battery with low energy density

In addition, lithium iron phosphate also has a disadvantage in that its low electronic conductivity (about 10 -8 S / cm), at present, the impact of low conductivity is alleviated mainly by adding conductive agents (such as carbon black, copper powder, high-temperature pyrolytic coated carbon) for metal ion doping, and synthesizing nano-particles.

However, the method of doping metal ions is mainly to mix some oxides in the mixing stage. Since there are many reacting materials, it is difficult to ensure the uniformity in the mixing process.

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