Controlled Synthesis of Nitrogen-Doped Yolk–Shell\nCarbon Nanospheres: Tailoring Yolk Size for Lithium–Sulfur\nBatteries

Abstract

Nitrogen-doped\nyolk–shell carbon nanoparticles are one of\nthe most promising functional nanomaterials for various potential\napplications because of their functionality and adaptability in both\nthe hollow shells and yolks. Yolk–shell nanospheres are known\nfor widely adopted template-based routes, which prove to be expensive\nand cumbersome and showed inadequate capability to build complex internal\nstructures. Herein, a facile and controllable strategy for fabricating\nnitrogen-doped yolk–shell carbon nanospheres was proposed through\na simple leaching process. The production of the yolk–shell\nstructure is based on the selective dissolution of inhomogeneous solid\npolymer nanospheres using methanol as leaching agent. The yolk sizes\nof the nanospheres can be controlled in the range 110–360 nm\nby simply varying the number of leaching times. In particular, results\nof the electrochemical properties of the prepared nanospheres with\ndifferent yolk size suggest that the optimal yolk–shell nanospheres\nwith a yolk size of ∼230 nm delivered the best cycling performance\nand good capacity retention of 582 mAh g^–1 at 1\nC after 200 cycles. We believe that the proposed strategy will play\na crucial role in energy storage application.