Double-shelled support and confined void strategy to improve the lithium storage properties of SnO2/C anode materials for lithium-ion batteries

Abstract

As promising anode materials for lithium-ion batteries, SnO₂ materials have triggered significant research efforts due to their high theoretical capacity. However, their practical applications are impeded by their poor cycle life, which is caused by structural pulverization and large volume changes during cycling. Thus, the development of strategies to improve the cycling performance of SnO₂ anodes is indispensable. Herein, a peculiar nanostructured SnO₂/C composite (denoted as SnO₂@DSC) with a double-shelled carbon support and confined void is fabricated, in which SnO₂ is quasi confined in the void-space between two shells. It is suggested that the as-prepared SnO₂@DSC has two unique advantages: on the one hand, SnO₂ is quasi encapsulated into the confined void between two shells, huge volume change is largely buffered and its electrical connectivity is guaranteed, because even if SnO₂ detaches from the outer shell, it can be immobilized again in the interior shell; on the other hand, the structural integrity of the electrode could be guaranteed by virtue of the dual-support of mechanically flexible double-shelled hollow carbon nanospheres. As a result, the as-prepared SnO₂@DSC exhibited an excellent cycling performance, delivering a high reversible capacity of 838.2 mA h g⁻¹ at 200 mA g⁻¹ even after 500 cycles.