Directionally Tailoring Macroporous Honeycomb-Like Structured Carbon Nanofibers toward High-Capacitive Potassium Storage

Constructing high-capacitive potassium storage materials can avoid the sluggish and unstable bulk diffusion process via a surface-induced process, which is conducive to swift and frequent potassium storage. Herein, we demonstrated the use of macroporous honeycomb-like carbon nanofibers (MHCNFs) as an excellent anode material for high-capacitive potassium storage. The as-made MHCNFs feature abundant well-controlled macropores, an amorphous structure, and a large specific surface area of around 595.9 m² g^-1. These structural characteristics could significantly reduce the transferring distance of electrons/ions, offer abundant active sites, enable high-capacitive contribution, and thus substantially improve the kinetics and structural stability of MHCNFs. Experimental investigation demonstrated that MHCNFs enable ultrahigh potassium storage ability (329.1 mAh g^-1 at 100 mA g^-1) and competitive rate capability (168.5 mAh g^-1 at 5000 mA g^-1). More impressively, even when cycled at 1000 mA g^-1, the robust structure of MHCNFs can still enable the electrodes a capacity of 252.6 mAh g^-1 over repeating 2500 cycles. This work offers a promising strategy that macropore engineering coupled with amorphous structure can make effectively elevated K⁺ diffusion kinetic performance and promoted K⁺ adsorption/intercalation storage possible.