Multimodal Analysis Unveils the Correlation Between Graphite Anode Characteristics and Operational Longevity in Pr/Nd Rare Earth Metals Electrolysis

The service life of graphite anodes—key consumables in the Pr/Nd fluoride molten salt electrolysis process—directly governs production continuity, cost-efficiency, and supply chain stability. This study systematically evaluated five industrial-grade anodes produced from different raw materials and processes. Multimodal characterization—combining macroscopic and microscopic morphology, SEM/EDS, XRD, Raman, and physical property analysis—was employed to correlate initial anode properties with corrosion-induced morphological and mass changes during electrolysis. The results show that the raw material quality and preparation methods synergistically regulate both the crystal structure and microstructure, thereby governing the corrosion behaviour and mass loss. Anodes #2 and #3, which were fabricated from high-quality petroleum coke and subjected to full densification and graphitization, exhibited high graphitization (93.7–94.5%), large crystallites (59.6–64.5 nm), minimal defects (low ID/IG), and suppressed microporosity, leading to the lowest mass loss (10.2 ± 0.8 kg and 10.6 ±0.9 kg). In contrast, anodes #1, #4, and #5, made from recycled graphite without graphitization, contained abundant structural defects and large pores and led to greater morphological changes and quality losses. Moreover, for recycled graphite anodes, the presence of large pores and cracks is one of the important reasons for their failure. This work clarifies the “process–microstructure–mass loss” relationship in graphite anodes for Pr/Nd electrolysis, offering key insights for designing high-performance anodes and advancing sustainable rare earth production.