spectrophotometric determination of trace amounts of sulfate impurity in lithium carbonate used as cathode material for lithium ion batteries

Abstract lithium carbonate (li2co3) is a key raw material that is used to prepare cathode materials in a li-ion battery. also, any impurities present in the raw materials used to make the battery can affect its performance and lifespan. therefore, impurity analysis of battery-materials is vital for suppliers of the raw materials, battery manufacturers, and emerging industries such as the electric vehicle power battery sector. one of the impurities is sulfate ion. in this work, we developed a simple and selective method for the determination of sulfate ion impurity in lithium carbonate. the method is based on reaction of sulphonazo iii with barium ion, that the absorbance of barium - sulphonazo i11 chelate was decreased in the presence of sulfate because of formation of barium sulfate complex. the decrease in absorbance is proportional to the concentration of sulfate ion. under optimal conditions, at λmax= 640 nm, the linear range of determination of sulfate was 2.0-12.0 μg ml-1 with detection limits of 1.0 μg ml-1. the validity of the method was evaluated by means of the data statistical analysis. for this purpose, the method was applied to the determination of sulfate in lithium carbonate and the results were statistically compared with those obtained by the by hplc method using t- and f-tests. there was no significant difference between the mean values and the precisions of the two methods at the 95% confidence level. the proposed method was successfully applied for the determination of sulfate in lithium carbonate with good recoveries ranged from 99-104%, and rsd less than 2.0 %. the results showed that the proposed method offers an accuracy and reliable approach for the determination of sulfate in lithium carbonate raw materials, and can be suggested as a routine method in battery quality control laboratories.