Rational Design of Sn-based Multicomponent Anodes for High Performance Lithium-Ion Batteries: Hollow SnO2@TiO2@rGO Nanotubes

Abstract

Tin (IV) oxide (SnO2) is one of highly promising candidates for anodes for next generation lithium-ion batteries, owing to high theoretical capacity and rate capability along with environmental safety. However, severe volume expansion and subsequent pulverization problem of SnO2 have always been critical issues. To resolve such issues, two different methods have been suggested: I) SnO2/Sn-C composite materials and ii) SnO2-TiO2 composite materials. Nevertheless, limitation is present for both approaches: the former has relatively low theoretical capacity with increasing loading amount of carbon and the latter shows lack of improvements in rate capability due to the low conductivity of both TiO2 and SnO2. Here, we have tried to improve both the capacity retention and rate capability of SnO2 by coating TiO2 on SnO2 through sol-gel process and subsequent reduced graphene oxide (rGO)-wrapping. With such hybrid structure, it can overcome both cycle retention and conductivity limitations that are applicable to most of metal oxides. As a result of such design in mind, rGO-wrapped SnO2@TiO2 exhibits better rate capability and retains discharge capacity of over 860 mAh g-1 at a current density of 200 mA g-1 even after 100 cycles.