A Partial Sulfuration Strategy Derived Multi-Yolk-Shell Structure for Ultra-Stable K/Na/Li-ion Storage.

ABSTRACT

Metal sulfides are attractive anodes for alkali metal ion batteries due to the high theoretical capacity, while their practical implementation is hampered by the inherent poor conductivity and vast volume variation during cycles. Approaching rational designed microstructures with good stability and fast charge transfer is of great importance in response to these issues. Herein, a partial sulfuration strategy for the rational construction of multi-yolk-shell (m-Y-S) structures, from which multiple Fe1- x S nanoparticles are confined within hollow carbon nanosheet with tunable interior void space is reported. As anode materials, the m-Y-S Fe1- x S@C composite can display high capacity and excellent rate capability (134, 365, and 447 mA h g-1 for K+ , Na+ , and Li+ storage at 20 A g-1 ). Remarkably, it exhibits ultra-stable potassium storage up to 1200, 6000, and 20 000 cycles under current densities of 0.1, 0.5, and 1 A g-1 , which is much superior to previous yolk-shell structures and metal-sulfide anodes. Based on comprehensive experimental analysis and theoretical calculations, the exceptional performance of m-Y-S structure can be ascribed to the optimized interior void space for good structure stability, as well as the multiple connection points and conductive carbon layer for superior electron/ion transportation.