Temperature-Induced Morphology Control of Fe-Polydopamine Coordination Complexes and Their Derivatives for Energy Storage Applications.

Controlling the morphology of organic-inorganic complexes at the nanometer scale is crucial for electrochemical applications. We present a novel method for controlling Fe-polydopamine (Fe-PD) coordination complexes into rod, urchin, and hollow structures at high (80-90 °C), medium (40-60 °C), and low (0-10 °C) synthesis temperatures, respectively. Morphological evolution was driven by the balance between oriented and random polymerization pathways, with hollow structures formed through random growth followed by selective inner-core etching. H- and U-Fe-PDs were converted to H- and U-Fe@C composites after carbonization. H-Fe@C exhibited superior performance in lithium-metal anodes, achieving stable cycling for over 2500 h with exceptional overpotentials as low as 7.4 mV and 76% capacity retention after 1000 cycles, significantly outperforming U-Fe@C due to enhanced mass transport through the thin carbon shell (∼50 nm). This temperature-controlled strategy provides a versatile approach for designing morphology-driven materials for advanced energy storage.