FeSe2 encapsulated in nitrogen-doped mesoporous carbon nanowires as efficient anode for K-ion batteries

Abstract

The development of high-performance anodes is one of the key steps for the application of K-ion batteries (KIBs). Herein, small FeSe2 nanoparticles have been uniformly encapsulated into nitrogen-doped (N-doped) mesoporous carbon nanowires to achieve FeSe2@N-MCNWs composite anode by a dual-templating method. In this anode, anisotropic one-dimensional (1D) nanostructure of carbon facilitates the electron transport, and mesoporous structure makes more active sites expose, mitigates the volume change of FeSe2 and offers rapid ions/electrolyte diffusion path. Furthermore, the N-C sites can chemically adsorb discharge product, promoting cycling stability. Therefore, the FeSe2@N-MCNWs can approach a high specific capacity of 124.2 mAh g−1 at 5 A g−1 and deliver a discharge capacity of 139.2 mAh g−1 after 1000 cycles at 1 A g−1. This study may provide useful guidelines for designing other 1D nanostructured anodes for KIBs.