Nanoarchitectured TiO₂/SnO: A Future Negative Electrode for High Power Density Li-Ion Microbatteries?

Abstract

The synthesis of a nanoarchitectured composite material consisting of tin and tin oxide nanowires grown onto titania nanotubes by anodization of titanium and tin electrodeposition is reported. The crystallinity of the electrodes can be tuned by optional heat treatment, but the initial morphology is preserved. XRD patterns revealed the presence of Sn onto an amorphous titania matrix and Sn/SnO onto a crystalline titania matrix. Here, we highlight that tin and tin oxide nanowires are obtained when using a titania nanotubes matrix. This particular morphology is not obtained using a titania compact seed layer. Their different electrochemical behavior in lithium test cells is studied by a galvanostatic technique at a rate of 100 and 50 μA cm −2 . Only tin and tin oxides are checked as electroactive material by limiting voltage ranges to 1.2 and 0.01 V. The nanocomposite with this particular geometry (2 μm of tin/tin oxide thickness) has a remarkable reversible capacity of about 140 μA h cm −2 which is kept about 85% over 50 cycles. It is demonstrated that the matrix based on titania nanotubes can allow the volume expansion of lithium−tin alloys and thus enhances the electrochemical performances as compared with usual tin-based electrodes. The obtained capacities compare very favorably with the best literature data for Li-ion microbatteries.