A SnO2@carbon nanocluster anode material with superior cyclability and rate capability for lithium-ion batteries.

A nanocluster composite assembled by interconnected ultrafine SnO2-C core-shell (SnO2@C) nanospheres is successfully synthesized via a simple one-pot hydrothermal method and subsequent carbonization. As an anode material for lithium-ion batteries, the thus-obtained nano-construction can provide a three-dimensional transport access for fast transfer of electrons and lithium ions. With the mixture of sodium carboxyl methyl cellulose and styrene butadiene rubber as a binder, the SnO2@C nanocluster anode exhibits superior cycling stability and rate capability due to a stable electrode structure. Discharge capacity reaches as high as 1215 mA h g(-1) after 200 cycles at a current density of 100 mA g(-1). Even at 1600 mA g(-1), the capacity is still 520 mA h g(-1) and can be recovered up to 1232 mA h g(-1) if the current density is turned back to 100 mA g(-1). The superior performance can be ascribed to the unique core-shell structure. The ultrafine SnO2 core gives a high reactive activity and accommodates volume change during cycling; while the thin carbon shell improves electronic conductivity, suppresses particle aggregation, supplies a continuous interface for electrochemical reaction and alleviates mechanical stress from repeated lithiation of SnO2.