A Flexible Multi-Channel Hollow CNT/Carbon Nanofiber Composites with S/N Co-Doping for Sodium/Potassium Ion Energy Storage

Abstract

Carbon fibrous materials are the promising candidate for the anode of flexible sodium-ion batteries and potassium-ion batteries due to the structural advantages. However, the progress of mechanically robust anode materials with high electrochemical properties is still unsatisfactory for the flexible electrodes. Herein, the comprehensive design of the morphology with unique multi-channel hollow 1D/1D carbon nanotube/carbon nanofiber network and the lattice structure of carbon with S/N co-doping has been proposed. Benefiting from the enlarged interlayer spacing and the flexible fibrous network, the S/N doped carbon nanotube/carbon nanofiber composites (CNT/SNCF) possess not only high conductivity but also good structural stability during sodiation and potassiation processes. When used as anode materials in SIBs and PIBs, the free-standing CNT/SNCF electrodes exhibit high discharge capacities (274.1 and 212.5 mA h g–1 at 1 A/g after 1000 cycles, respectively), superior cycle stability (150.4 and 100.1 mA h g–1 at 5 A/g after 5000 cycles, respectively) and rate performance (109.3 mA h g–1 at 10 A/g and 108.7 mA h g–1 at 5 A/g, respectively), showing great prospects in flexible energy storage devices.

Research progress on carbon materials as negative electrodes in sodium‐ and potassium‐ion batteries

“…Zhang et al 179 synthesized a sandwich doped carbon nanotube @Nb 2 C (N‐CNT@Nb 2 C), which showed excellent electrochemical performance in LIBs, SIBs, and PIBs, such as stable cycle performance of more than 500 cycles. Chen et al 180 used S/N‐doped carbon nanotube/carbon nanofiber composites (CNT/SNCF) as negative electrode materials for SIBs and PIBs. Independent CNT/SNCF electrodes show high discharge capacity (274.1 and 212.5 mAh g −1 at 1 A g −1 after 1000 cycles, respectively) and excellent cycle stability (150.4 and 100.1 mAh g −1 after 5000 cycles at 5 A g −1 , respectively) and rate performance (109.3 mAh g −1 at 10 A g −1 and 108.7 mAh g −1 at 5 A g −1 , respectively) (Table 3).…”

Phosphorus-Regulated Nitrogen Sites in Ultrathin Carbon Scrolls for Stable Potassium Storage

“…The P-N/UCS anode maintains a high specific capacity of 265.8 mAh g –1 after 2000 cycles at 1.0 A g –1 , and the corresponding average capacity attenuation is just 0.017% per cycle, which is considerably superior to those of most reported carbonaceous anodes (Figure e and Table S5). ,,,,,,,− ,− The outstanding electrochemical performances of the P-N/UCS anode can be ascribed to the expanded interlayer distance, increased specific surface area, enhanced proportions of active N sites, and improved electronic conductivity based on the foregoing results, which can accelerate charge transport and K + diffusion kinetics through the extra P doping.…”

Review on Recent Applications of Nitrogen‐Doped Carbon Materials in CO2 Capture and Energy Conversion and Storage

“…In another study, Chen et al [ 68 ] investigated sulfur and nitrogen doping (S/N doping) impact on sodium‐ion batteries (NIBs) and potassium‐ion batteries (KIBs). The researchers designed a morphology with unique multi‐channel hollow 1D/1D carbon nanotube/carbon nanofiber network and lattice structure of carbon with S/N co‐doping (Figure 10b).…”

“…Copyright 2021, Elsevier. b) Reproduced with permission [68]. Copyright 2021, American Chemical Society.…”