Tailor-made overstable 3D carbon superstructures towards efficient zinc-ion storage

Abstract

Designing carbon materials with ideal stable hierarchical porous structures and flexible functional properties for efficient and sustainable Zn²⁺ ion storage still faces great challenges. Herein, the three-dimensional carbon superstructures with spherical nanoflower-like structures were tailor-made by the self-assembly strategy. Specifically, organic polymer units (i.e. organic motifs) were formed by tetrachloro-p-benzoquinone (TBQ) and 2,6-diamino anthraquinone (DAQ) via a noble-metal-free catalyzed coupling reaction. Subsequently, the organic motifs assemble into spherical nanoflower-like superstructures induced by intermolecular hydrogen bonding and aromatic π-π stacking interactions. Well-designed carbon superstructures can provide a stable backbone that effectively blocks structural stacking and collapse. Meanwhile, the hierarchical porous structures in 3D carbon superstructures provide continuous charge transport pathways to greatly shorten the ion diffusion distance, and as a result, the carbon superstructures-based zinc-ion hybrid capacitors (ZIHCs) provide a capacity of 245 mAh/g at 0.5 A/g, a high energy density of 152 Wh/kg and an ultra-long life of 300,000 cycles at 20 A/g. The excellent electrochemical performance is also attributed to the corresponding charge storage mechanism, i.e., the alternate binding of Zn²⁺/CF₃SO₃⁻ ions. Besides, the high-level N/O motifs improve the surface properties of the carbon superstructures and reduce the ion migration barriers for more efficient charge storage. This paper provides insights into the design of advanced carbon-based cathodes and presents a fundamental understanding of their charge storage mechanisms.