3D Sulfur and Nitrogen Codoped Carbon Nanofiber Aerogels with Optimized Electronic Structure and Enlarged Interlayer Spacing Boost Potassium‐Ion Storage

Abstract

Abstract Carbonaceous materials are promising anodes for potassium‐ion batteries (PIBs). However, it is hard for large K ions (1.38 Å) to achieve long‐distance diffusion in pristine carbonaceous materials. In this work, the following are synthesized: S/N codoped carbon nanofiber aerogels (S/N‐CNFAs) with optimized electronic structure by S/N codoping, enhanced interlayer spacing by S doping, and a 3D interconnected porous structure of aerogel, through a pyrolysis sustainable seaweed (Fe‐alginate) aerogel strategy. Specifically, the S/N‐CNFAs electrode delivers high reversible capacities of 356 and 112 mA h g −1 at 100 and 5000 mA g −1 , respectively. The capacity reaches 168 mA h g −1 at 2000 mA g −1 after 1000 cycles. A full cell with a S/N‐CNFAs anode and potassium prussian blue cathode displays a specific capacity of 198 mA h g −1 at 200 mA g −1 . Density functional theory calculations indicate that S/N codoping is beneficial to synergistically improve K ions storage of S/N‐CNFAs by enhancing the adsorption of K ions and reducing the diffusion barrier of K ions. This work offers a facile heteroatom doping paradigm for designing new carbonaceous anodes for high‐performance PIBs.