High-temperature carbon-coated aluminum current collector for enhanced power performance of LiFePO4 electrode of Li-ion batteries

The charge/discharge capacity and cycle stability at high C-rate of LiFePo4 (LFPO) electrodes using three types of Al current collectors, including smooth un-etched Al foil, anodization-etched Al foil, and the etched Al foil covered with a conformal C coating grown at 600 degrees C in CH4, were investigated. The results unequivocally demonstrate the strong effects exerted by the surface structure and composition of the Al current collectors on the power performance. In particular, the use of the C-coated current collector not only remarkably increases the power-delivering capability, by 3-7-fold based on different comparison criteria, of the LFPO electrode, but also greatly enhances its cycle stability under high C-rate (5C). The rate enhancement exceeds that of a low-temperature organic-bound C-coating reported in the literature. The enhancements are consistent with observed reduction in overall charge-transfer resistance, which can be attributed to the removal of the native insulating oxide surface layer of the current collector and to the improved adhesion at the active layer/current collector interface. This current collector is also applicable to other cathode and anode (e.g., Li4Ti5O12) materials of Li-ion batteries for the same beneficial effects. (C) 2010 Elsevier B.V. All rights reserved.