Novel carbon coating on aluminum current collectors for lithium-ion batteries

Abstract

In this work a significant improvement of the performance of LiFePO4 (LFP) composite cathodes, in particular at high rates (up to 12C), is demonstrated by the use of carbon-coated aluminum current collectors. The coating procedure is novel, and allows for application of a thin carbon layer without the use of solvent and binder. The presence of the thin carbon coating is verified by collecting the Raman spectra. The spectra are dominated by the D-band, indicating a low the degree of graphitization and a high amount of disordered carbon in the sample. LFP cathodes with an area capacity of 1.7 mAh/cm2 show an excellent rate capability of 89% upon cycling at 5C. A dramatic reduction of the contact resistance towards the active cathode material has been verified for the coated current collectors. It is furthermore shown that the electrochemical impedance spectra for cathodes applied on uncoated current collectors is dominated by the contact resistance, while the charge transfer resistance dominates the spectrum for cathodes applied to the carbon-coated current collector.