Rational nanostructured FeSe2 wrapped in nitrogen-doped carbon shell for high-rate capability and long cycling sodium-ion storage

Transition metal selenides (TMSs) have drawn substantial attention as promising anode materials for sodium-ion batteries (SIBs) on account of their rapid reaction kinetics and high reversible capacity. However, the undesirable capacity decay and inferior rate performance still hamper their large-scale application. Herein, an anode material comprising combination of olivary nanostructure FeSe2 core and nitrogen-doped carbon shell (designated as FeSe2@NC) is well designed by in-situ polymerization and selenization method. The well-designed nitrogen-doped carbon shell can not only alleviate the volume variation during the electrode cycling but also provide an optimized ion/electron transport pathway. The resulting FeSe2@NC electrodes exhibit a superior rate capability of 228.4 mA h g(-1) at 10 A g(-1) and a long cycling performance of 246.5 mA h g(-1) at 5 A g(-1) after 1000 cycles, which can be assigned to the enhanced structural integrity and improved electrical conductivity. The strategy would present a promising thought for structure design of TMSs as anode materials, which could enhance high-rate and long-lasting cycle performances for SIBs. (C) 2022 Elsevier Inc. All rights reserved.

Automated summary

This study designs an anode material consisting of a FeSe2 core and a nitrogen-doped carbon shell, which exhibits superior rate capability and long cycling performance. The material also alleviates volume variation during electrode cycling.