Rare-earth ions induced pre-excitation of intercalation-conversion anode to achieve fast potassium-ion storage

K-ions storage system play an important role in the up-coming clean-energy era. However, its performance is severely restricted by the difficulties in the insertion and diffusion of large-sized K-ions. In this work, a rare-earth ion induced pre-excitation strategy is proposed to significantly improve the K-ion storage performance of MoSe2-based anode materials. A series of rare-earth ions (Re = Lu3+, Tm3+, Y3+, Gd3+, Sm3+, Nd3+, and La3+) are introduced into the Se-Mo-Se basal plane (labeled as Re-MoSe2-x@C), resulting in the abundance of fracture surfaces with active sites (Se-vacancy) up to 14.2% and increased interlayer spacing. Interestingly, such structure with sufficient active Se-vacancy defects enable K-ions to be preferentially adsorbed onto the fractured Se-Mo-Se basal plane. Subsequently, these adsorbed K-ions cross the layered plane through the defect sites, rather than the edge sides, to complete the subsequent facilitated intercalation and conversion reaction. Thanks to this well-integrated mechanism, the assembled K-ion capacitor delivers an outstanding energy/power characteristic (form 146 Wh kg−1/500 W kg−1 to 86 Wh kg−1/10 kW kg−1) and cycling stability (nearly 100% retention after 10000 cycles), demonstrating its promising prospects in practical applications.