Nano SnO2 and Sb2O3 combined with CNTs as a high-capacity lithium storage material

Abstract

The combination of Sb2O3 or SnO2 with graphene has become a research hotpot in recent years. However, several problems, namely the loading of the active materials, space utilization in composites, and the intrinsic volume expansion of Sb2O3 and SnO2, have yet to be fully resolved. To overcome these disadvantages, in this work Sb2O3/carbon nanotubes (CNTs)/SnO2 composite have been synthesized, in which the CNTs act as a network to ensure the electronic conductivity and buffer of the volume expansion. The SnO2 nanoparticles are aligned by the CNTs and Sb2O3 is dispersed in the voids between them. Space utilization and the loading of the oxides are thereby maximized. Moreover, the resultant composite retains small amount of water or alcohol, which does not affect the cyclic stability, but may have increased the ionic and electronic conductivity, improving the electrochemical performance. A discharge capacity of 910 mAh g−1 after 250 cycles at 100 mA g−1 is realized for Sb2O3/CNT/SnO2. Moreover, the contribution of the pseudocapacitance to the rate discharge capability is obvious, which arises from the different heterointerfaces between Sb2O3/CNTs, CNTs/SnO2 or Sb2O3/SnO2. The homogenous distribution of Sn and Sb in CNTs after cycling leads to a lower discharge voltage, improving the application prospects. Although some collapse and cracks are detected, the CNTs network connects the oxides, ensuring the structural stability and the cyclic stability of Sb2O3/CNT/SnO2. This strategy represents a new concept for the design of multi-component materials for lithium storage.