Electrochemically active nanocomposites of Li4Ti5O12 2D nanosheets and SnO2 0D nanocrystals with improved electrode performance

Abstract

Electrochemically active nanocomposites consisting of Li4Ti5O12 2D nanosheets and SnO2 0D nanocrystals are synthesized by the crystal growth of tin dioxide on the surface of 2D nanostructured lithium titanate. According to powder X-ray diffraction and electron microscopic analyses, the rutile-structured SnO2 nanocrystals are stabilized on the surface of spinel-structurecl Li4Ti5O12 2D nanosheets. The homogeneous hybridization of tin dioxide with lithium titanate is confirmed by elemental mapping analysis. Ti K-edge X-ray absorption near-edge structure and Sn 3d X-ray photoelectron spectroscopy indicate the stabilization of tetravalent titanium ions in the spinel lattice of Li4Ti5O12 and the formation of SnO2 phase with tetravalent Sn oxidation state. The electrochemical measurements clearly demonstrate the promising functionality of the present nanocomposites as anode for lithium secondary batteries. The Li4Ti5O12-SnO2 nanocomposites show larger discharge capacity and better cyclability than do the uncomposited Li4Ti5O12 and SnO2 phases, indicating the synergistic effect of nanocomposite formation on the electrode performance of Li4Ti5O12 and SnO2. The present experimental findings underscore the validity of 2D nanostructured lithium titanate as a useful platform for the stabilization of nanocrystalline electrode materials and also for the improvement of their functionality. (C) 2012 Elsevier Ltd. All rights reserved.