Soft-Chemical Synthesis and Electrochemical Property of H2Ti12O25 as a Negative Electrode Material for Rechargeable Lithium-Ion Batteries

Upon heating the as-prepared H2Ti3O7 sample, single-phase samples of H2Ti6O13, H2Ti12O25 and TiO2(B) were prepared with different heating conditions; at 120 degrees C for 48 h in a vacuum of 20 Pa for H2Ti6O13, at 260 degrees C for 5 h in air for H2Ti12O25, and at 350 degrees C for 5 h in air for TiO2(B). The chemical compositions of these compounds were determined by the DTA-TG and ICP analyses. The coordination environments around hydrogen atoms in these compounds were examined by using FTIR and H-1-MAS-NMR data. The reversible Li insertion and extraction reactions around 1.5-1.6 V with initial intercalation capacities of 283 and 236 mAh g(-1), were observed for H2Ti6O13 and H2Ti12O25, respectively. The structural changes upon cycling were clarified for H2Ti3O7 and TiO2(B). Among the four compounds, H2Ti12O25 showed superior cycling performance with the discharge capacity retention rate of 96% after 50 cycles. H2Ti12O25 is suggested to be one of the promising high-voltage oxide negative electrodes in advanced lithium-ion batteries. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3562207] All rights reserved.