Wydział Chemii

Paweł Dziewoński

Maria Grzeszczuk

2009

Journal of Power Sources

190

545-552

10.1016/j.jpowsour.2009.01.041

Naukowa

Angielski

Artykuł

Starting from the aqueous solution of titanium(IV) oxalate complexes and controlling electrochemical conditions using a cyclic voltammetry (CV) method, the thin layers of TiO₂ on platinum were obtained, which after additional heat treatment, at 450 °C, were still of amorphous nature. The amorphous state of the samples, containing an admixture of crystalline anatase, was confirmed by Raman spectroscopy and by a variety of electrochemical techniques. The new electrochemical procedure allows preparing the oxide with different morphologies. By the comparison with the peroxotitanium route, the oxalate precursor method offers the possibility of the synthesis of amorphous TiO₂ at higher temperatures that is the essential key for the cycling stability of the oxide if one is used as an anode material in lithium ion batteries. The results from cycling voltammetry revealed that electrodeposited TiO₂ reversibly and fast intercalates lithium ions due to its high internal surface area. Therefore, the nanostructural morphology facilitates lithium ion intercalation which was monitored and confirmed in all electrochemical testing. The specific capacity of the TiO₂ approaches the value of 145 mAh g⁻¹ at 8 C-rate in the best case. From the electrochemical impedance spectroscopy (EIS) measurements in connection with SEM investigations, it was concluded that Li⁺ diffusion is the finite space process and its rate is depending on the size of the crystallites building the oxide films. Evaluated values of the D-coefficients are of the order of 10⁻¹⁴ cm² s⁻¹.

Titanium(IV) oxide, Li+ intercalation, Cyclic electrodeposition, Impedance analysis

https://doi.org/10.1016/j.jpowsour.2009.01.041

http://www.elsevier.com