Remarkable anodic performance of lead titanate 1D nanostructures via in-situ irreversible formation of abundant Ti~(3+) as conduction pathways

PX-phase PbTiO_3 (PT) nanowires with open channels running along the length direction have been investigated as an anode material for lithium ion batteries. This material shows a stabilized reversible specific capacity of about 410 mAh·g~(-1) up to 200 cycles with a charge/discharge voltage plateau of around 0.3-0.65 V. In addition, it exhibits superior high-rate performance, with 90% and 77% capacity retention observed at 1 and 2 A·g~(-1), respectively. At a very high current rate of 10 A·g~(-1), a specific capacity of over 170 mAh·g~(-1) is retained up to 100 cycles, significantly outperforming the rate capability reported for Pb and Pb oxides. The results of X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analyses along with the cyclic voltammogram results reveal that the PX-phase PT nanowires undergo irreversible structural amorphization and reduction reactions during the initial cycle, which allow them to transform into a composite structure composed of 2-5 nm Pb nanoparticles uniformly dispersed in the 1D amorphous Li2O·TiO_2·LiTiO_2 matrix. In this composite structure, the presence of abundant amounts of Ti~(3+) in both the charged and discharged states enhances the electrical conductance of the system, whereas the presence of ultrafine Pb nanoparticles imparts high reversible capacity. The structurally stable TiO_2-based amorphous matrix can also considerably buffer the volume variation during the charge/discharge process, thereby facilitating extremely stable cycling performance. This compound combines the high specific capacity of Pb-based materials and the good rate capability of Ti~(3+)-based wiring. Our results might furnish a possible route for achieving superior cycling and rate performance and contribute towards the search for next-generation anode materials.