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Sodium-ion batteries （SIBs） have great promise for sustainable and economicalenergy-storage applications. Nevertheless, it is a major challenge to developanode materials with high capacity, high rate capability, and excellent cyclingstability for them. In this study, FeSe2 clusters consisting of nanorods weresynthesized by a facile hydrothermal method, and their sodium-storage propertieswere investigated with different electrolytes. The FeSe2 clusters delivered highelectrochemical performance with an ether-based electrolyte in a voltage rangeof 0.5-2.9 V. A high discharge capacity of 515 mAh.g-1 was obtained after 400 cyclesat 1 A.g-1, with a high initial columbic efficiency of 97.4%. Even at an ultrahighrate of 35 A-g-1 a specific capacity of 128 mAh.g-1 was achieved. Using calculations,we revealed that the pseudocapacitance significantly contributed to the sodium-ionstorage, especially at high current rates, leading to a high rate capability. Thehigh comprehensive performance of the FeSe2 clusters makes them a promisinganode material for SIBs.