Controlled synthesis of SnO2@carbon core-shell nanochains as high-performance anodes for lithium-ion batteries

Abstract

A new low-flow-rate inert atmosphere strategy has been demonstrated for the synthesis of perfect SnO₂@carbon core-shell nanochains (SCNCs) by carbonization of an SnO₂@carbonaceous polysaccharide (CPS) precursor at a relatively high temperature. This strategy results in the thorough carbonization of CPS whilst avoiding the carbothermal reduction of SnO₂ at 700 °C. It has been investigated that a moderate carbon content contributes to the 1-D growth of SCNCs, and the thickness of the carbon shell can be easily manipulated by varying the hydrothermal treatment time in the precursor process. Such a unique nanochain architecture could afford a very high lithium storage capacity as well as resulting in a desirable cycling performance. SCNCs with about 8 nm carbon shell synthesized by optimized routes were demonstrated for optimal electrochemical performances. More than 760 mAh g^¬1 of reversible discharge capacity was achieved at a current density of 300 mA g⁻¹, and above 85% retention can be obtained after 100 charge-discharge cycles. TEM analysis of electrochemically-cycled electrodes indicates that the structural integrity of the SnO₂@carbon core-shell nanostructure is retained during electrochemical cycling, contributing to the good cycleability demonstrated by the robust carbon shell.