Interfacial Kinetics Regulation of MoS2/Cu2Se Nanosheets toward Superior High‐Rate and Ultralong‐Lifespan Sodium‐Ion Half/Full Batteries

Abstract Sodium‐ion batteries (SIBs) have aroused great attention because of the low cost and environmental benignity of sodium resources. However, practical applications of SIBs are plagued by the sluggish kinetics of sodium ions with large size in the host structure, which results in poor rate performance and rapid capacity decline. Herein, a self‐templated approach was developed to synthesize MoS 2 /Cu 2 Se nanosheets with improved interfacial electron‐ and ion‐transfer kinetics. The MoS 2 /Cu 2 Se nanosheets provided superior sodium storage performance, delivering 139 mAh g −1 at a high current density of 100 A g −1 and 222 mAh g −1 after 14000 cycles (at 20 A g −1 ). The outstanding electrochemical performance was attributed to the synergetic engineering of interface and structure, which could enhance the electrochemical kinetics and gave excellent mechanical properties to deal with the volume expansion phenomenon. Combined with a high‐voltage cathode, the full battery demonstrated a high energy density of 152 Wh kg −1 at a power density of 420 W kg −1 , which opens a new avenue for the development of high‐performance SIBs.