Optimization of the Process Parameters for the Synthesis Process of Battery-Grade Ferrous Oxalate by Response Surface Method

Abstract

This study investigates the optimal conditions for the synthesis of battery-grade ferrous oxalate as a raw material for preparing cathode material. Ferrous oxalate was prepared by liquid-phase precipitation method using ferrous sulfate and oxalic acid. Central composite design (CCD) was used to determine the effects of three preparation variables on purity and particle size: reaction temperature, aging time and concentration of ferrous sulfate. Based on CCD, the significant factors on each experimental design response identified the analysis of variance (ANOVA). The optimum ferrous oxalate preparation conditions were obtained reaction temperature of 31.32[Formula: see text]C, aging time of 56.52[Formula: see text]min, and ferrous sulfate concentration of 5%. Under these optimum conditions, ferrous oxalate with purity of 99.69% and particle size of 4.92[Formula: see text][Formula: see text]m was obtained as best product which met and exceed the requirements of battery-grade ferrous oxalate. In addition, the special morphologies of ferrous oxalate prepared under different dispersant proportion was characterized by scanning electron microscope (SEM) to analyze the mechanism of synthesis. Morphology control study revealed that the dispersant could effectively change the surface energy between crystallographic planes, then result in anisotropic growth of the crystal structure and change the morphology of synthetic products.