A novel way to prepare battery-grade FePO4 2H2O from copper slag and Life cycle assessment

Copper slag (CS) contains a high content of valuable iron, the stockpile of CS occupies a large amount of land and leads to a waste of secondary resources. This study proposed producing battery-grade FePO 4 ·2H 2 O from CS through selective leaching, synthesis, and purification. The combined acid leaching/evaporation method was used to leach out Fe and inhibit Si from fayalite selectively, and then FePO 4 ·2H 2 O was formed by adding Na 2 HPO 4 ·12H 2 O without extra pH adjustment. The purity of FePO 4 ·2H 2 O obtained by using a reactor heated for 5 h at 180 ℃ with an HCl concentration of 2.5 M was 99.47 %, and the impurities were all by the industry standard for battery-grade FePO 4 ·2H 2 O (HG/T 4701–2021). The LiFePO 4 /C material was further synthesized and tested for battery performance. Under the test current of 0.1C, the charging-specific capacity of the battery in the first week was 175.8 mAh/g, and the discharge-specific ability was 159.3 mAh/g, which was close to the theoretical specific capacity and effective. Life cycle assessment (LCA) indicated that for each 1 kg of iron phosphate produced, the carbon emission of this study was reduced by 4.71 kg CO 2 eq compared with the traditional technology.