Scalable synthesis of VN quantum dots encapsulated in ultralarge pillared N-doped mesoporous carbon microsheets for superior potassium storage

Abstract

Potassium-ion batteries (KIBs) are promising alternatives to lithium-ion batteries (LIBs) due to the advantages of low-cost and abundant natural resource. To date, the researches on KIBs are still in their early stage and only a few materials have been explored. Herein, we design VN quantum dots encapsulated in ultralarge pillared N-doped mesoporous carbon microsheets (VN-QDs/CM) via a large-scale and ultrafast (within two minutes) solution combustion synthesis method and a subsequent ammonia reduction process. The VN quantum dots with high mass loading and dispersity on conductive carbon microsheets could reduce the K-intercalation stress in particle dimensions and mitigate the volume expansion. In addition, the ultralarge pillared N-doped mesoporous carbon microsheets not only facilitate the transfer of electrons and K ions and but also prevent the active materials from breaking away from the electrode during cycling. As an advanced anode material for KIBs, a high reversible capacity and a superior cycling stability (228 mAh g−1 at 0.1 A g−1 after 100 cycles, 215 mAh g−1 at 0.5 A g−1 after 500 cycles) are obtained, among the best anodes reported. More importantly, the effective strategy can be potentially used for mass production of quantum dots encapsulated in ultralarge carbon microsheets for energy storage.