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

Abstract

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.