Cu6Sn5–TiC–C nanocomposite alloy anodes with high volumetric capacity for lithium ion batteries

Abstract

A Cu₆Sn₅–TiC–C nanocomposite alloy anode has been synthesized by first firing a mixture of Cu, Sn, and Ti metals and then ball milling the resultant material with carbon. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and scanning electron microscopy (SEM) reveal that these nanocomposites are composed of nanostructured Cu₆Sn₅ particles in a matrix of TiC and conductive carbon. The presence of TiC and conductive carbon improves the cycle life of Cu₆Sn₅ anodes compared to that found with plain Cu₆Sn₅. With a second cycle discharge capacity of 1340 mAh cm⁻³ (610 mAh g⁻¹) and a tap density of 2.2 g cm⁻³, the Cu₆Sn₅–TiC–C nanocomposite anode offers a volumetric capacity that is at least four times higher than that of the graphite anode and 30% higher than what can be achieved with silicon. A conductive Cu framework supports the electrochemically-active Sn particles, resulting in low impedance and good rate capability. TEM data from electrodes that were cycled between 0 and 200 cycles show that the Cu₆Sn₅ particles do not agglomerate, and the morphology of the particles does not change during extended cycling. Furthermore, this nanocomposite anode material exhibits excellent performance in full cells with manganese-containing cathodes at elevated temperatures, indicating that it may not be poisoned by dissolved Mn.