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Unexpected intercalation-dominated process is observed during K+ insertion in WS2 in a voltage range of 0.01-3.0 V.This is different from the previously reported two-dimensional (2D) transition metal dichalcogenides that undergo a conversion reaction in a low voltage range when used as anodes in potassium-ion batteries.Charge/discharge processes in the K and Na cells are studied in parallel to demonstrate the different ion storage mechanisms.The Na+ storage proceeds through intercalation and conversion reactions while the K+ storage is govemed by an intercalation reaction.Owing to the reversible K+ intercalation in the van der Waals gaps,the WS2 anode exhibits a low decay rate of 0.07％ per cyde,delivering a capacity of 103 mAh·g-1 after 100 cycles at 100 mA·g-1.It maintains 57％ capacity at 800 mA·g-1 and shows stable cyclability up to 400 cycles at 500 mA·g-1.Kinetics study proves the facilitation of K+ transport is derived from the intercalation-dominated mechanism.Furthermore,the mechanism is verified by the density functional theory (DFT) calculations,showing that the progressive expansion of the interlayer space can account for the observed results.