Optimization of the Process Parameters for the Synthesis of LiFe1−x−yMgxTiyPO4/C Cathode Material Using Response Surface Methodology

Abstract

A systematic approach was used to develop the empirical model for optimizing the preparation process parameters for the synthesis of LiFe[Formula: see text]MgxTiyPO4/C composite cathode material. For optimizing the production parameters, response surface methodology (RSM) was applied to develop a linear regression model and maximize the discharge capacity. Analysis of the variance (ANOVA) showed that the three variables (Mg-dopant, Ti-dopant and sintering temperature) and the interactions among them were significant factors. Response surfaces formed by RSM illustrated that the doping of Mg and Ti on Fe site had obviously synergistic effect on the discharge capacity. In the process optimization, the parameters were 2.9% of Mg-dopant, 3.0% of Ti-dopant and sintering temperature of 678.5[Formula: see text]C, corresponding to a discharge capacity of 136.7[Formula: see text]mAh/g predicted by the model. This predicted value was in good agreement with the actual value (136.4[Formula: see text]mAh/g) by confirmatory experiment. The optimized LiFe[Formula: see text]Mg[Formula: see text]Ti[Formula: see text]PO4/C composite exhibits a good rate performance and cycling stability due to the enhancement of electronic conductivity and lithium diffusion coefficient ([Formula: see text][Formula: see text]cm2/s) by the co-doping of Mg and Ti ions.