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 ZnxMnO2 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.