Application of the factorial design of experiments to hydrothermal synthesis of lithium iron phosphate

The mathematical model of lithium iron phosphate prepared by hydrothermal method was established by factor experimental design. The effect of individual variables and their interactions were studied by the main effects plot and Interaction plot. The influence of ascorbic acid dosage on the discharge specific capacity was greater than the hydrothermal time and the hydrothermal temperature, and the influence degree of the latter two was equivalent and the interaction effect of hydrothermal time and ascorbic acid dosage has the greatest influence on the discharge specific capacity in three interaction effects. The optimized hydrothermal condition was hydrothermal time of 9 hours, hydrothermal temperature of 210°C and ascorbic acid dosage of 1.5 mmol in the experimental design range, with the initial discharge specific capacity of 0.1 C as 152.5 mAh g⁻¹. The corresponding characterization was performed using electrochemical methods, XRD, SEM, and TEM. This study provided a protocol to factorially design better experiments to achieve excellent battery criterion in the context of lithium iron phosphate preparation.