Silicon-oxycarbide based thin film anodes for lithium ion batteries

We show that anodes made by depositing thin films of polymer-derived silicon oxycarbide (SiCO) on copper have properties that are comparable to, or better than that of powder-based SiCO anodes. The great advantage of the thin film architecture is its simplicity, both in manufacturing and in application. The films are produced by spraying a film of the liquid polymer-precursor on copper, and then converting it into SiCO by heating at similar to 1000 degrees C; at this point they are ready for constructing electrochemical cells. They show a capacity of similar to 1000 mA h g(-1), 100% coulombic efficiency, good capacity at very high C-rates, and minimal fading at similar to 60 cycles. However, if the films are thick they delaminate due to the volume change as lithium is cycled in and out. The transition from thin-film to thick-film behavior occurs when the SiCO films are approximately 1 mu m thick. An analytical method for estimating this transition is presented. (C) 2011 Elsevier B.V. All rights reserved.