Effects of current collectors on power performance of Li4Ti5O12 anode for Li-ion battery

The effects of current collector on the charge/discharge capacity and cycle stability of Li4Ti5O12 (LTO) electrode under high C-rates (up to 20C) have been investigated by applying five types of current collectors, including a Al foil, an anodization-etched Al (E-Al), the same etched Al with a conformal C coating (C-E-Al), a Cu foil (Cu) and the same Cu foil with a C coating (C-Cu). The C coatings on both metal current collectors are deposited by a chemical vapor deposition process using CH4 at 600 degrees C. The capacities of the LTO electrodes above 1 C rate are in the order of Al < E-Al < Cu similar to C-E-Al < C-Cu, exhibiting remarkable enhancement in rate performance by the C-coating for both metals. Surface analyses indicate that the enhancement can be attributed to the combination of two factors, including removal of the native oxide layer and modification of surface hydrophobicity, which improves adhesion of active layer, on the current collector surface. Both contribute to the reduction of the resistance at the current-collector/active layer interface. All electrodes show good cycle stability. (C) 2011 Elsevier B.V. All rights reserved.