Chlorine Doping of Amorphous TiO2 for Increased Capacity and Faster Li+-Ion Storage
article
Titania (TiO2) offers a high theoretical capacity of 336 mAh g-1 with the insertion of one Li per Ti unit. Unfortunately, the poor ionic and electronic conductivity of bulk TiO2 electrodes limits its practical implementation. Nanosizing titania below ∼20 nm has shown to increase the rate performance and accessible capacity but still not more than 75% of the theoretical capacity at 1 C. In this work, we discovered that chlorine doping of amorphous TiO2 (TiO2-xCl2x) can achieve a high capacity without the need for nanosizing. By in situ doping during atomic layer deposition, an unprecedented 90% of the theoretical capacity was achieved at 1 C for 100 nm thick films. Even at a charging rate of 20 C, 40% of the maximum capacity was accessible for the film with highest Cl-content (x = 0.088). The capacity was found linearly dependent on the chloride content for a Cl/Ti atomic ratio from 0.06 to 0.09. The enhanced insertion kinetics are ascribed to enhanced electronic conductivity and facilitated Li+-ion diffusion as a result of Cl-doping. Furthermore, the potential of TiO2-xCl2x films as high rate anode were demonstrated on micropillar electrodes in a half-cell configuration using a liquid electrolyte solution, showing 10 times higher capacity at 10 C compared to the literature.
Topics
TNO Identifier
782919
ISSN
08974756
Source
Chemistry of Materials, 29(23), pp. 10007-10018.
Publisher
American Chemical Society
Pages
10007-10018
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