FeS quantum dots as an ultrastable host material for potassium-ion intercalation

Potassium-ion battery (PIB) is a potential candidate for future large-scale energy storage devices. Constructing electrode materials with fast ions and electron transport channels is an effective solution to achieve high-power-density and long-cycle PIBs. Herein, the composite composed of FeS quantum dots and nitrogen-doped porous carbon (FeS@NPC) is reported as anode material for PIBs. The unique uniform nanostructure is confirmed to be able to reduce the ion diffusion length, increase the migration rate of potassium ions, improve electronic conductivity, and alleviate volume fluctuation. These advantages deliver enhanced potassium storage properties with high capacity and excellent cycling stability. FeS@NPC-based anode obtains a specific capacity of 224 mAh g-1 at 1 A g-1 and 180 mAh g-1 at 5 A g-1 even after 1200 cycles.