From Lychee Seeds to Hierarchical Fe3O4/Carbon Composite Anodes for Lithium-Ion Batteries: A High Additional Value Conversion-Based Self-Assembly Strategy

As an abundant agricultural process residue, lycheeseeds are generally disposed of as waste because their practicalutilization has been limited to a narrow range of low-value items. Itis of great interest and highly desirable to explore a new conversionway from waste lychee seeds to high-value materials. Herein,natural polyphenols are directly extracted from waste lychee seedsand utilized as precursors of a state-of-the-art Fe3O4/carboncomposite for high-performance lithium-ion batteries. Thepolyphenols arefirst extracted from waste lychee seeds and thencoordinated with metal ions to assemble an inorganic-organichybrid coated on a carbon nanotube substrate. After high-temperature carbonization, metal oxide/carbon composites areobtained. The as-prepared Fe3O4/carbon composite possesses a unique hierarchical structure including a distinctively heterogeneouscarbonaceous skeleton comprised of a graphitic core and an amorphous shell and an intimate binding at the Fe3O4/carbon interface.Benefiting from the as-constructed beneficial structure, the hierarchical CNT@Fe3O4/C composite, selected as a proof-of-conceptproduct, shows impressive electrochemical performances when used as an advanced anode material of lithium-ion batteries. Thiswork provides a promising sustainable way for converting waste lychee seeds to high additional value materials and as well shedslight on the realization of advanced energy-storage devices besides lithium-ion batteries

Automated summary

In this study, natural polyphenols extracted from waste lychee seeds are used as precursors to prepare a high-performance Fe3O4/carbon composite for lithium-ion batteries. The hierarchical CNT@Fe3O4/C composite exhibits impressive electrochemical performances. This research provides a promising and sustainable approach for converting agricultural waste into high-value materials.