Ceiba flower-derived hard carbon with multi-dimensional self-supported structures and its ZnIn ₂ S ₄ -based composites: long-term stable anode materials for sodium-ion batteries

Biomass-derived functional carbon materials have attracted increasing research attention due to their cost-effectiveness, environmental friendliness, and easy adjustability of compositions and structures. Especially, for sodium-ion batteries (SIBs), which are widely recognized as a promising alternative to lithium-ion batteries, biomass-derived hard carbon holds the greatest potential as an anode material for commercialization in the near future. In this paper, through a facile carbonization process, a multi-dimensional structured N-doped hard carbon with rational pores and defects has been successfully synthesized from an abundant and easy-accessible biomass precursor of ceiba flower, which delivers a remarkable initial coulombic efficiency of 83.2%. When incorporated with ZnIn₂S₄ nanoarchitectures, the fabricated composites maintain the multi-dimensional structures with further-optimized pores, defects and electronic structures, achieving a high reversible capacity of 510.2 mA h g^-1 after 1000 cycles at 1 A g^-1. Considering the low-cost raw materials, environment-friendly and facile synthetic process, high initial coulombic efficiency and high reversible capacity, these ceiba-derived materials hold great application potential as anode materials for high-performance SIBs.