Silicon-oxycarbide based thin film anodes for lithium ion batteries

摘要

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 ~1000℃; at this point they are ready for constructing electrochemical cells. They show a capacity of ~1000mAhg~(-1), 100% coulombic efficiency, good capacity at very high C-rates, and minimal fading at ~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 1μm thick. An analytical method for estimating this transition is presented.