Effect of carbon types on the electrochemical properties of negative electrodes for Li-ion capacitors

The electrochemical properties of various carbon materials (graphite and hard carbon) have been investigated for use as a negative electrode for Li-ion capacitors. The rate capabilities of the carbon electrodes are tested up to 40C using both half and full cell configurations. It is found that the capacitance of the hard carbon material at 40C could be maintained up to 70% of that at 0.2C in full cells with an activated carbon positive electrode, which is the best among the carbon materials. The cycle performance of the hard carbon demonstrates that the initial capacitance is retained up to 83% even after 10,000 cycles. The outperforming results could be ascribed to the microstructure of hard carbon, which indicates that hard carbon is more suitable as negative electrode materials for high power energy storage applications. (C) 2011 Elsevier B.V. All rights reserved.