Electrochemically active nanocomposites consisting of Li 4Ti 5O 12 2D nanosheets and SnO 2 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 SnO 2 nanocrystals are stabilized on the surface of spinel-structured Li 4Ti 5O 12 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 Li 4Ti 5O 12 and the formation of SnO 2 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 Li 4Ti 5O 12-SnO 2 nanocomposites show larger discharge capacity and better cyclability than do the uncomposited Li 4Ti 5O 12 and SnO 2 phases, indicating the synergistic effect of nanocomposite formation on the electrode performance of Li 4Ti 5O 12 and SnO 2. 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.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea Grant funded by the “Korean Government (MEST)” (NRF-2010-C1AAA001-2010-0029065), by the Korea Ministry of Environment as “Converging Technology Project” (191-101-001), and by National Research Foundation of Korea Grant funded by the Korean Government (2010-0001485). The experiments at Pohang Accelerator Laboratory (PAL) were supported in part by MOST and POSTECH.
- Anode materials
- Lithium secondary batteries