재활용 황산철을 이용한 리튬인산철 양극재 합성 및 불순물 영향 분석

초록

The growing demand for lithium-ion batteries (LIBs) in the electric vehicle (EV) market underscores the need for sustainable production of battery materials. Lithium iron phosphate (LiFePO₄, LFP) has emerged as a promising cathode material due to its stability, cost-effectiveness, and scalability. This study explores the synthesis of LFP using iron sulfate (FeSO₄) recovered from stainless-steel scrap, with a particular focus on the effects of nickel (Ni) impurities introduced during recycling. Experimental results reveal that nickel incorporation into the LFP lattice induces structural distortion and phase inhomogeneity, leading to performance degradation. Within the operational voltage range, nickel remains electrochemically inactive, contributing to capacity loss rather than enhancement. Across various nickel concentrations, no performance improvement was observed, confirming that nickel consistently acts as a detrimental impurity rather than a beneficial dopant. These findings underscore the importance of controlling nickel impurities below a critical threshold in recovered iron sulfate to preserve LFP’s electrochemical stability. Furthermore, this study highlights the necessity of rigorous impurity management in recycled materials while demonstrating the potential of stainless-steel scrap recycling for sustainable cathode production.