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

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.

Rational Construction of Nitrogen‐Doped Hierarchical Dual‐Carbon for Advanced Potassium‐Ion Hybrid Capacitors

“…More importantly, upon discharge, the I D / I G ratio decreases from 1.09 to 0.94, indicating a lower degree of disorder, which can be explained by the intercalation of the abundant K + to vacancies and defects. [ 37 ] The observation further confirms the reversibility of NMCP@rGO upon charge/discharge cycling. The I D / I G ratio can return to its original value without noticeable change.…”

“…The capacity decay is caused by the decomposition of the K + ‐electrolyte and the production of a stable SEI. [ 37 ] Compared with other carbon materials with a high SAA, the high initial CE of 50.8% in NMCP@rGO is ascribed to its unique “dual‐carbon” structure. [ 3,6,8 ] Subsequently, the CE of the NMCP@rGO electrode rapidly rises over 90% after three cycles and approaches ≈100% after 20 cycles, owing to the gradual stabilization of the formed SEI.…”

Effect of Intrinsic Defects of Carbon Materials on the Sodium Storage Performance

“…In the case of anode materials, the research have exhibited a trend of blowout development. Carbon, alloys, transition‐metal oxides/sulfides have been extensively explored as promising anodes of SIBs . Among these materials, carbon have gained increasing research attentions as a kind of resource abundant, conductive, and thermodynamically stable material .…”

Dual-doped hierarchical porous carbon derived from biomass for advanced supercapacitors and lithium ion batteries

“…[20][21][22] Compared with single heteroatom doping, co-doping can further enhance electrochemical properties of the carbon materials owing to the synergistic effect. [23][24][25][26][27] For example, nitrogen and oxygen have received considerable attention for improving the wettability between electrolyte and electrode material and facilitating the occurrence of surface redox reaction further to achieve extra pseudocapacitance. 13,24 As a kind of natural resource, biomass has been considered as potential precursor for the preparation of carbon materials owing to its easily available, fast-renewable, low-cost and environmentally benign features.…”