Flat–Zigzag Interface Design of Chalcogenide Heterostructure toward Ultralow Volume Expansion for High‐Performance Potassium Storage

Heterostructure construction of layered metal chalcogenides can boost their alkali-metal storage performance, where the charge transfer kinetics can be promoted by the built-in electric fields. However, these heterostructures usually undergo interface separation due to severe layer expansion, especially for large-size potassium accommodation, resulting in the deconstruction of heterostructures and battery performance fading. Herein, first a stable interface design strategy where two metal chalcogenides with totally different layer-morphologies are stacked to form large K+ transport channels, rendering ultralow interlayer expansion, is presented. As a proof of concept, the flat-zigzag MoS2 /Bi2 S3 heterostructures stacked with zigzag-morphology Bi2 S3 and flat-morphology MoS2 present an ultralow expansion ratio (1.98%) versus MoS2 (9.66%) and Bi2 S3 (9.61%), which deliver an ultrahigh potassium storage capacity of above 600 mAh g-1 and capacity retention of 76% after 500 cycles, together with the built-in electric field of heterostructures. Once the heterostructures are used as an anode for potassium-based dual-ion batteries (K-DIBs), it achieves a superior full-cell capacity of ≈166 mAh g-1 with a capacity retention of 71% after 400 cycles, which is an outstanding performance among the reported K-DIBs. This proposed interface stacking strategy may offer a new way toward stable heterostructure design for metal ions storage and transport applications.