Interlayer Sodium Plating/Stripping in Van der Waals‐Layered Quantum Dot Superstructure

Abstract

AbstractAssembling quantum dots (QDs) into van der Waals (vdW)‐layered superstructure holds great promise for the development of high‐energy‐density metal anode. However, designing such a superstructure remains to be challenging. Here, a chemical‐vapor Oriented Attachment (OA) growth strategy is proposed to achieve the synthesis of vdW‐layered carbon/QDs hybrid superlattice nanosheets (Fe7S8@CNS) with a large vdW gap of 3 nm. The Fe7S8@CNS superstructure is assembled by carbon‐coated Fe7S8 (Fe7S8@C) QDs as building blocks. Interestingly, the Fe7S8@CNS exhibits two kinds of edge dislocations similar to traditional atom‐layered materials, suggesting that Fe7S8@C QDs exhibit quasi‐atomic growth behavior during the OA process. More interestingly, when used as host materials for sodium metal anodes, the Fe7S8@CNS shows the interlayer sodium plating/stripping behavior, which well suppresses Na dendrite growth. As a result, the cell with Fe7S8@CNS anode can keep stable cycling for 1000 h with a high Coulombic efficiency (CE) of ≈99.5% at 3.0 mA cm−2 and 3.0 mAh cm−2. Noticeably, the Na@Fe7S8@CNS||Na3V2(PO4)3 full cells can attain a capacity of 88.8 mAh g−1 with a retention of 97% after 1000 cycles at 1.0 A g−1 (≈8 C), showing excellent cycle stability for practical applications. This work enriches the vdW‐layered QDs superstructure family and their application toward energy storage.