电池级磷酸铁中硫酸根的脱除研究

水热法合成的磷酸铁粗产品中硫酸根的去除已成为磷酸铁制造行业的关键技术。分别以纯水,热水,柠檬酸溶液为洗水洗涤粗产品,结果表明,纯水和热水洗涤之后的产品中硫酸根含量可降低至行业标准的要求(0.01%),继续加大洗水量也无法再脱除硫酸盐杂质,而柠檬酸溶液的洗涤可将产品中硫酸盐完全脱出,且洗水量大大降低,经分析无残留柠檬酸存在产品中。硫酸根含量对磷酸铁锂正极材料电化学性能影响明显。

Study on removal of sulfate impurity in battery-grade ferric phosphate

The removal of sulfate from crude iron phosphate synthesized byhydrothermal methodhas become the key technology in iron phosphate industry. The crude product were washed by pure water,hot water and citric acid solution, respectively. The results indicated that sulfate content of the product washed by pure water andhot water can be reduced to 0.01% of the industry standard, sulfate impurity cannot be removed when continue to increase the amount of washing water. Sulfate was completely removed by citric acid solution, washing water wasgreatly reduced and no citric acid remained in the product. The effect of sulfate content on the electrochemical performance of Li Fe PO4 cathode material was obvious.