Dual carbon regulated yolk-shell ZnSe microsphere anode materials towards high performance potassium ion batteries

Abstract

ZnSe is considered to be an intriguing anode material arising from its high theoretical capacity and low cost in potassium ion batteries (PIBs). The poor reaction kinetics and unfavorable structural stability, however, largely impede the performance. Herein, a dual carbon manipulated yolk-shell ZnSe microsphere (ZnSe-C@NC) is rationally envisaged, with ideal construction stability and efficient K + diffusion process. A high discharge capacity of 549.9 mAh g −1 with favorable initial Coulombic efficiency of 81.8% can be achieved at 100 mA g −1 . Even at the current density of 1000 mA g −1 , the reversible capacity is as high as 456.4 mAh g −1 . Concurrently, a full PIB based on ZnSe-C@NC is designed with a high energy density of 133.8 Wh kg −1 at the power density of 236 W kg −1 . The experiment and in-depth density functional theory (DFT) calculation results demonstrate that the N doped carbon decoration on ZnSe would greatly accelerate charge transportation, narrow the bandgap and minimize K + movement energy barrier. On the other hand, the dual carbon protection endow that the unique yolk-shell construction with superb mechanical stability during long circulation, bringing about exceptional electrochemical performance.