Insights into Interlayer Dislocation Augmented Zinc-ion Storage Kinetics in MoS2 Nanosheets for Rocking-Chair Zinc-Ion Batteries with Ultralong Cycle-life

Increasing attention on sustainability and cost-effectiveness in the energy storage sector has catalyzed the rise of rechargeable Zinc-ion batteries (ZIBs). However, their limited cycle life arising from the Zn-metal anode is a major challenge, and replacing Zn-metal with high-capacity anode materials for rocking-chair ZIB configuration is a promising solution. Molybdenum disulfide (MoS2), an insertion-type 2D layered material with good surface area, shows promising characteristics as ZIB anode. Nevertheless, its high Zn-ion diffusion barrier because of limited interlayer spacing substantiates the need for interlayer modifications. In this study, 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 for enhancing charge storage capacity. Consequently, MoS2@N-CQDs attain a high specific capacity (258 mAh/g at 0.1 A/g), good cycle life (94.5 % after 2000 cycles), and an ultrahigh diffusion coefficient (10-6 to 10-8 cm2/s), much better than pristine MoS2. Ex-situ Raman studies at charge/discharge states reveal that the N-CQDs-induced interlayer expansion and dislocations could sufficiently and 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 was unveiled by molecular dynamic simulations. Finally, a Zn-metal free 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 and excellent cyclic stability with 97% retention after 15000 cycles, further substantiating its future application prospects.