TY - JOUR
T1 - A mechanism study of synthesis of Li4Ti5O 12 from TiO2 anatase
AU - Yuan, Tao
AU - Cai, Rui
AU - Ran, Ran
AU - Zhou, Yingke
AU - Shao, Zongping
PY - 2010/8/27
Y1 - 2010/8/27
N2 - The formation mechanism of a spinel-type lithium titanate Li 4Ti5O12 with TiO2 anatase as raw material, in both a conventional solid-state reaction (SSR) and a cellulose-assisted glycine-nitrate combustion (cellulose-GN) process are comparatively studied. XRD characterization demonstrates high-purity Li 4Ti5O12 forms at 750 °C by the cellulose-GN synthesis, which occurs at a temperature at least 100 °C lower than that via SSR. The solid-phase reaction between TiO2 and lithium compounds to form Li-Ti-O spinel and the phase transition of TiO2 from anatase to "inert" rutile phase occur competitively during both synthesis processes. SEM results suggest that the solid precursor from the cellulose-GN process has a smaller particle size and a more homogenous mixing of the reactants than that in the SSR. Temperature-programmed oxidation experiments demonstrate that cellulose thermal pyrolysis creates a reducing atmosphere, which may facilitate the oxygen-ion diffusion. Both factors facilitate the formation of Li-Ti-O spinel, while the TiO2 anatase transforms to TiO2 rutile during the SSR, which has slow lithium-insertion kinetics. As a result, a high calcination temperature is necessary to obtain a phase-pure Li4Ti5O12. Charge-discharge and EIS tests demonstrate the Li4Ti5O12 obtained by the cellulose-GN process shows much better low-temperature electrochemical performance than that obtained by standard SSR. This improvement attributes to the reduced particle size due to the lower synthesis temperature.
AB - The formation mechanism of a spinel-type lithium titanate Li 4Ti5O12 with TiO2 anatase as raw material, in both a conventional solid-state reaction (SSR) and a cellulose-assisted glycine-nitrate combustion (cellulose-GN) process are comparatively studied. XRD characterization demonstrates high-purity Li 4Ti5O12 forms at 750 °C by the cellulose-GN synthesis, which occurs at a temperature at least 100 °C lower than that via SSR. The solid-phase reaction between TiO2 and lithium compounds to form Li-Ti-O spinel and the phase transition of TiO2 from anatase to "inert" rutile phase occur competitively during both synthesis processes. SEM results suggest that the solid precursor from the cellulose-GN process has a smaller particle size and a more homogenous mixing of the reactants than that in the SSR. Temperature-programmed oxidation experiments demonstrate that cellulose thermal pyrolysis creates a reducing atmosphere, which may facilitate the oxygen-ion diffusion. Both factors facilitate the formation of Li-Ti-O spinel, while the TiO2 anatase transforms to TiO2 rutile during the SSR, which has slow lithium-insertion kinetics. As a result, a high calcination temperature is necessary to obtain a phase-pure Li4Ti5O12. Charge-discharge and EIS tests demonstrate the Li4Ti5O12 obtained by the cellulose-GN process shows much better low-temperature electrochemical performance than that obtained by standard SSR. This improvement attributes to the reduced particle size due to the lower synthesis temperature.
KW - Combustion synthesis
KW - Lithium titanate
KW - Solid-state reaction
KW - Titanium dioxide
UR - http://www.scopus.com/inward/record.url?scp=77955582891&partnerID=8YFLogxK
U2 - 10.1016/j.jallcom.2010.04.253
DO - 10.1016/j.jallcom.2010.04.253
M3 - 文章
AN - SCOPUS:77955582891
SN - 0925-8388
VL - 505
SP - 367
EP - 373
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
IS - 1
ER -