FeSe₂ Microspheres as a High‐Performance Anode Material for Na‐Ion Batteries

FeSe2 microspheres assembled by nano-octahedra are used as an anode material for Na-ion batteries for the first time, showing a high discharge capacity (447 mA h g(-1) at 0.1 A g(-1)), excellent rate performance (388 mA h g(-1) at 5 A g(-1) and 226 mA h g(-1) at 25 A g(-1)), and long cycling stability (372 mA h g(-1) after 2000 cycles at 1 A g(-1)).