Insights into Interlayer Dislocation Augmented Zinc‐Ion Storage Kinetics in MoS₂ Nanosheets for Rocking‐Chair Zinc‐Ion Batteries with Ultralong Cycle‐Life

Abstract

Increasing attention to sustainability and cost-effectiveness in energy storage sector has catalyzed the rise of rechargeable Zinc-ion batteries (ZIBs). However, finding replacement for limited cycle-life Zn-anode is a major challenge. Molybdenum disulfide (MoS₂), an insertion-type 2D layered material, has shown promising characteristics as a ZIB anode. Nevertheless, its high Zn-ion diffusion barrier because of limited interlayer spacing substantiates the need for interlayer modifications. Here, N-doped carbon quantum dots (N-CQDs) are used to modify the interlayers of MoS₂, resulting in increased interlayer spacing (0.8 nm) and rich interlayer dislocations. MoS₂@N-CQDs attain a high specific capacity (258 mAh g^-1 at 0.1 A g^-1), good cycle life (94.5% after 2000 cycles), and an ultrahigh diffusion coefficient (10^-6 to 10^-8 cm² s^-1), much better than pristine MoS₂. Ex situ Raman studies at charge/discharge states reveal that the N-CQDs-induced interlayer expansion and dislocations can reversibly accommodate the volume strain created by Zn-ion diffusion within MoS₂ layers. Atomistic insight into the interlayer dislocation-induced Zn-ion storage of MoS₂ is unveiled by molecular dynamic simulations. Finally, rocking-chair ZIB with MoS₂@N-CQDs anode and a Zn_xMnO₂ cathode is realized, which achieved a maximum energy density of 120.3 Wh kg^-1 and excellent cyclic stability with 97% retention after 15 000 cycles.