Construting stable 2 x 2 tunnel-structured K1.28Ti8O16@N-doped carbon nanofibers for ultralong cycling sodium-ion batteries

Sodium-ion batteries (SIBs) are one of the most potential candidates for large-scale energy storage due to the low cost and eco-friendliness, however, a stable and reversible anode is urgently developed. In this work, a novel 2 x 2 tunnel-structured K1.28Ti8O16@N-doped carbon nanofibers (KTO@N-CNFs) anode is successfully synthesized via simple electrospinning and subsequent thermal treatment with urea acted as the additional convenient nitrogen source. In-situ X-ray diffraction (XRD) measurement confirms the intercalation reaction mechanism and robust structure during Neinsertion/extraction. This composite material exhibits a reversible capacity of 116.4 mAh g(-1) at a current density of 100 mA g(-1 )after 1000 cycles. More impressively, even at a high current density of 1 A g(-1), the battery delivers capacity retention of 98.4 mAh g(-1) after 5000 cycles. The excellent electrochemical performance is attributed to the adequate 2 x 2 tunnel structure and the nano-confinement of N-doped nanofibers on K(1.28)Ti(8)O(16 )nanocrystals, which offers enough diffusion paths and enhance the ionic diffusion of sodium ions. This work provides a facile strategy to synthesis stable, reversible, and long-cycle anode for sodium-ion batteries. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study successfully synthesized a novel KTO@N-CNFs anode material with excellent electrochemical performance and high reversible capacity even at large current densities. The outstanding performance is attributed to the unique structure and nano-confinement of N-doped nanofibers on nanocrystals.