Enhanced Electrochemical Properties of Carbon Coated TiO2 anode for Sodium-Ion Battery

Many types of commercial batteries use carbonaceous materials materials for the anode, such as meso-carbon microbeads (MCMB) or hard carbon. However, MCMB cannot be used as an anode material for sodium batteries because of the high potential of the Na/Na⁺(~0.3V higher than Li/Li⁺) redox reaction and the large ionic radii of the Na⁺(102 pm).^1,2 Therefore, many researchers have been efforts to find a suitable anode material for the sodium – ion battery system. In the case of insertion anodes, various types of non-graphitic carbon materials have been considered and tested.^3,4

Here, we confirmed that the carbon coated anatase-type micro-sphere TiO₂ anode material has several advantages for the sodium ion battery system, including excellent cycle retention, high efficiency, good rate capability, and high energy density. The carbon coating, introduced by sucrose addition, had an effect of suppressing the growth of the TiO₂ primary particles during calcination. The carbon coated TiO₂ (sucrose 20 wt.% coated) electrode exhibited excellent cycle retention during 50 cycles (100%) and superior rate capability up to 30 C-rate at room temperature. This cell delivered a high discharge capacity of 155 mAh g^-1 at 0.1 C, 149 mAh g^-1 at 1 C, and 82.7 mAh g^-1 at 10 C-rate, respectively.

(1) Stevens, D. A.; Dahn, J. R. High Capapcity Anode Materials for Rechargeable Sodium-Ion Batteries. J. Electrochem. Soc. 2000, 147, 1271−1273.

(2) Wenzel, S.; Hara, T.; Janek, J.; Adelhelm, P. Room-Temperature Sodium-Ion Batteries: Improving the Rate Capability of Carbon Anode Materials by Templating Strategies. Energy Environ. Sci. 2011, 4, 3342−3345.

(3) Stevens, D. A.; Dahn, J. R. The Mechanisms of Lithium and Sodium Insertion in Carbon Materials. J. Electrochem. Soc. 2001, 148, A803−A811.

(4) Thomas, P.; Ghanbaja, J.; Billaud, D. Electrochemical Insertion of Sodium in Pitch-Based Carbon Fibers in Comparison with Graphite in NaClO4-Ethylene Carbonate Electrolyte. Electrochim. Acta 1999, 45, 423−430.