리튬의 선택적 회수를 위한 NCM 폐리튬이온배터리 블랙매스의 탄산화배소 공정에 관한 연구 = Research on Carbonation Roasting for Selective Lithium Recovery from NCM Spent Lithium-Ion Battery Black Mass

다국어 초록 (Multilingual Abstract)

With the rapid growth of the electric vehicle market, the generation of spent lithium-ion batteries has surged, highlighting the urgent need for environmentally benign and efficient lithium recovery technologies. Traditional inorganic acid leaching methods often suffer from significant environmental drawbacks and complicated purification steps.1 To overcome these challenges, this study presents an integrated lithium recovery scheme for black mass (BM) obtained from crushed battery cells, combining carbonation roasting, water leaching, and purification. The research systematically analyzes the reaction mechanisms and the behavior of impurities throughout the process. Results from the carbonation roasting stage reveal that lithium species were successfully transformed into water-soluble lithium carbonate(Li2CO3) at 800 °C under a CO2 atmosphere. Subsequent water leaching yielded a lithium recovery rate of 78% at a solid-to-liquid ratio of 1:35. Notably, valuable metals like Co, Ni, and Mn remained in the solid residue, demonstrating high selectivity. The process ultimately produced high-purity lithium carbonate (99.9 wt%) via evaporation and purification, proving the practical viability of this approach.
A key finding of this study is the identification of lithium fluoride (LiF) as the primary cause of lithium loss. Fluorine (F), originating from the decomposition of the electrolyte (LiPF6) and PVDF binder in the cell-based BM, reacts with lithium to form insoluble LiF, resulting in a lithium loss of approximately 24.2% during the purification process. To mitigate this issue, fluoride removal via precipitation was investigated by injecting Ca(OH)2 and CO2 gas into the leachate. Thermodynamic analysis indicated that the fluoride removal reaction becomes spontaneous (ΔG) under CO2 injection conditions. Experimentally, the fluoride removal efficiency increased markedly from 29.8% without CO2 to 75.1% with CO2 injection. However, XRD analysis revealed that the injected CO2 induced a competitive reaction forming CaCO3 by consuming available calcium ions, which consequently limited further fluoride removal efficiency.
In conclusion, this study demonstrates the feasibility of selective lithium recovery via carbonation roasting and elucidates mechanistically that fluoride control is an essential prerequisite for practical application. These findings are expected to serve as valuable fundamental data for the optimization and industrial commercialization of lithium recycling processes.

목차 (Table of Contents)

• 1. 서론 1
• 1.1 연구배경 1
• 1.2 연구목표 8
• 2. 이론배경 9
• 2.1 Black Mass 생산과정 9
• 2.2 배소의 정의 10
• 2.3 리튬 Eh-pH Diagram 14
• 2.4 리튬 회수 방법 16
• 3. 실험재료 및 방법 18
• 3.1 실험 재료 18
• 3.2 배소 실험방법 20
• 3.3 수침출 실험방법 21
• 3.4 결정화 실험방법 22
• 3.5 시료 분석방법 23
• 4. 실험결과 및 고찰 24
• 4.1 배소 가스별 BM 변화 특성 및 Li 회수율 비교 24
• 4.2 CO2 Gas 배소 조건 최적화 33
• 4.2.1 가스 유량에 따른 Li 침출률 비교 33
• 4.2.2 배소 온도에 따른 Li 침출률 비교 37
• 4.2.3 배소 체류시간에 따른 Li 침출률 비교 41
• 4.2.4 탄산화 배소조건(가스유량-배소시간-온도) 통합 최적조건 도출 43
• 4.3 수침출 조건 최적화 45
• 4.4 결정화 공정 및 정제 공정 49
• 4.4.1 수침액 증발농축을 통한 탄산리튬 결정화 50
• 4.4.2 정제공정을 통한 탄산리튬 고순도화 52
• 4.5 NCM 블랙매스로부터 선택적 Li 회수를 위한 공정도 59
• 4.6 F제거 방법 연구 61
• 4.6.1 Ca(OH)2를 이용한 F 침전 연구 61
• 5. 결론 및 향후 연구 68
• 5.1결론 68
• 5.2 연구 요약 69
• 5.3 향후 연구 71
• 5.3.1 불소(F) 제어를 위한 전처리 및 고도화 기술 개발 71
• 5.3.2 리튬 회수 후 잔사(Residue)의 고부가가치화 연구 72
• 6. 참고문헌 73