Development of Sustainable Battery Materials from Steel Waste, Particle size and morphology control of the swarf-derived iron phosphate precursors

Abstract

The global transition away from fossil fuels has driven surging demand for battery production and the associated materials such as lithium iron phosphate (LFP). Yet the LFP supply chain remains heavily concentrated in China, posing significant sup ply chain vulnerabilities through geopolitical tensions. In order to onshore battery manufacturing in the European and North American markets new feedstocks must be developed. This thesis investigates the feasibility of producing LFP from steel machining swarf through the lens of particle size optimization utilizing high energy ball milling. Surfactant assisted ball milling with 5 wt% myristic acid addition was identified as the optimal condition for sufficient particle size reduction of the iron phosphate precursor, reducing the median particle size from approximately 3 µm to 0.5 µm. The resulting LFP cathode achieved a specific capacity of 102 mAhg−1 at 0.5C with approximately 85% capacity retention after 90 cycles, demonstration the viability of converting steel waste into LFP cathode material while necessitating further optimization to become competitive with commercial LFP.