The Effect of Pore Size Controlled Carbon for Lithium Oxygen Batteries

The lithium-oxygen battery has been attracting great attention around the world due to its extremely high energy density (i.e., 1-2 kWh kg^-1), which could well satisfy the ever increased energy requirement from electronic devices, especially the electric vehicle and plug-in hybrid electric vehicle.^1-3

This exceptional energy potentiality has trigged the worldwide interest in this super energy storage system. However, despite large R&D efforts devoted to its implementation, several issues, associated with both electrodes and electrolytes, have so far limited the performance of the lithium oxygen battery due to few discharge-charge cycles and low rate capability.^{4, 5}

Many materials are used for cathode in lithium oxygen battery. Among them, carbon is the mostly used material because of the advantage in the way that amount and cost, although it has been talked making by-product like Li₂CO₃. (Some paper told that not only carbon but also electrolyte makes the problem in lithium oxygen battery system)

In this study, we show that Ordered mesoporous carbon (OMC) with highly ordered pore channels which was applied as an oxygen-side electrode for a lithium-oxygen battery.

To evaluate the effect of the pore channel size on battery performance, OMCs possessing two different pore sizes (6 and 17 nm) were employed. When cycled at a current density of 200 mA g^-1carbon, the OMC electrodes reduced polarization in the oxygen evolution reaction by 0.1 V compared to those consisting of conventional super P carbon electrode. X-ray diffraction and transmission electron microscopy of the discharged oxygen electrodes provided evidence for the formation of amorphous Li₂O₂, a product of the oxygen reduction reaction, inside the OMC pores rather than on the electrode surface as in the case of the super P electrode. The OMC electrodes were also effective at high current densities (500 mA g^-1carbon and 1000 mA g^-1carbon).

References

[1] K.M. Abraham, Journal of The Electrochemical Society, 143 (1996) 1.

[2] G. Girishkumar, B. McCloskey, A.C. Luntz, S. Swanson, and W. Wilcke, J Phys Chem Lett, 1 (2010) 2193-2203.

[3] B. Scrosati, J. Hassoun, and Y.K. Sun, Energ Environ Sci, 4 (2011) 3287-3295.

[4] S.A. Freunberger, Y. Chen, Z. Peng, J.M. Griffin, L. J. Hardwick, F. Bard, P. Novak, P. G. Bruce, J. Am. Chem. Soc. 133 (2011) 8040-8047.

[5] G.R. Mettam, L.B. Adams in: B.S. Jones, R.Z. Smith (Eds.), Introduction to the Electronic Age, E-Publishing Inc., New York, (2009), pp. 281–304.