Growth of ultrathin SnO2 on carbon nanotubes by atomic layer deposition and their application in lithium ion battery anodes

There is a great need for depositing SnO2 film onto micro/nano-structures in various fields. However, the growth of SnO2 on micro/nano-structures by atomic layer deposition (ALD) using tetrakis(dimethylamido) tin and water needs to be further investigated. In this work, ultrathin SnO2 were deposited uniformly and conformally on carbon nanotubes (CNTs) by ALD. The effects of deposition temperature on ALD-growth and the effect of film thickness on crystallographic state were investigated in detail. There is exceptionally high deposition rate at low deposition temperature. SnO2 tends to be deposited on the surface layer of CNTs substrate with CVD-like manner below 165 degrees C, but it can be deposited uniformly on each CNT mainly by chemical adsorption at high deposition temperature. In addition, the crystallographic state of SnO2 can also be controlled by regulating the film thickness. Using this feature, the electrochemical performances of SnO2@CNT composites with various thicknesses as the anode materials for lithium ion batteries (LIBs) were studied. The enhanced cycling stability and rate capability of SnO2@CNT could be attributed to small SnO2 thickness and limited crystal growth in ultrathin SnO2, which can overcome electrode degradation and enhance the lithium ion diffusion coefficient and electron kinetics of electrode.