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.