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.