Incorporation of amorphous TiO_2 into one-dimensional SnO_2 nanostructures as superior anodes for lithium-ion batteries

摘要

Lithium-ion batteries (LIBs) with higher energy density are necessary to meet the increasing demands of energy storage system (ESS) in near future. Tin (IV) oxide, SnO2, is one of highly promising anode candidates due to its high theoretical capacity (782 mAh g−1), abundance, environmental friendliness, and safety with organic electrolytes. However, a rapid capacity fading and poor rate capabilities arising from the large volume expansion and subsequent agglomeration of Sn nanoparticles have been major issues of SnO2. Here, we have synthesized one-dimensional (1D) SnO2-amorphous titanium (IV) oxide NTs (SnO2-a-TiO2NTs), which allow both facile ionic and electron transport as well as easy penetration of electrolytes. The resultant SnO2-a-TiO2NTs not only alleviate volume expansion by maintaining their structural integrity but also possess minimal charge transfer resistance even after a number of cycles. SnO2-a-TiO2NTs exhibit both excellent cycle retention characteristics (1050.2 mAh g−1after 250 cycles) and outstanding rate capability (522.3 mAh g−1at a current density of 5000 mA g−1), which is attributed to the introduction of amorphous TiO2that not only acts as buffer agent for volume changes of SnO2but also allows fast surface-controlled diffusion process due to its pseudocapacitive charge storage mechanisms.