Vapor–Solid Reaction Growth of Rutile TiO₂ Nanorods and Nanowires for Li-Ion-Battery Electrodes

Abstract

A new synthetic method to grow O-deficient rutile TiO2(s) nanorods (NRs) and nanowires (NWs) by a vapor–solid reaction growth method is developed. TiCl4(g) was employed to react with commercially supplied CaTiO3(s) (size 2–4 μm) at 973 K under atmospheric pressure to generate TiO2(s) NRs (diameters 80–120 nm, lengths 1–4 μm). The reaction employing TiCl4(g) and CaO(s) at 973 K also generated CaTiO3(s) (size 4–13 μm) as the intermediate which reacted further with TiCl4(g) to produce NWs (diameters 80–120 nm, lengths 4–15 μm). This is the first report of 1D rutile TiO2(s) nanostructure with such a high aspect ratio. Both of the NRs and the NWs, with compositions TiO1.81 and TiO1.65, respectively, were single crystals grown in the [001] direction. Their morphology was affected by the reaction temperature, the concentration of TiCl4(g), and the particle size of CaTiO3(s). The NRs and the NWs were investigated as anode materials for Li+-ion batteries. At constant current rates 1, 2, and 5 C (1 C = 170 mA g–1) for 100 cycles, the cycling (1.0–3.0 V) performance data of the NRs were 146, 123, and 104 mA h g–1, respectively. On the other hand, the cycling performance data of the NWs were 120, 80, and 52 mA h g–1, respectively. This is attributed to the high Li+ ion diffusion rate (DLi+) of the NRs (29.52 × 10–15 cm2 s–1), which exceeds that of the NWs (8.61 × 10–15 cm2 s–1). Although the [001] growth direction of the NR crystals would provide the fastest channels for the diffusion of Li+ ions and enhance the battery capacity, the extremely long channels in the NWs could hamper the diffusion of the Li+ ions. The O-deficiency in the structure would increase the conductivity of the electrode material and improve the stable cycling stability of the batteries also. The long-term cycling test at 2 C for the battery constructed from the NRs retained 121 mA h g–1 after 200 cycles and 99.2 mA h g–1 after 800 cycles. The device has an excellent long-term cycling stability with a loss of only 0.04% per cycle.

An investigation of Cu‐ZrO 2 ‐TiO 2 / CNTs anode material for lithium‐ion batteries

“…15 Since this breakthrough discovery, various crystallite morphologies of nanometer-sized rutile TiO 2 were fabricated in the development of anode materials for LIBs by other groups. For example, nanowires, 16 nanospheres, 17 nanotubes, 18 and nanorods 16,19,20 have been synthesized and reported to have high specific capacities. The nanostructures of such kinds of materials could significantly short the diffusion pathways of Li-ions, reduce the mechanical strains of electrode layer, and enlarge interfacial contact areas between the material and the electrolyte to provide more accessible reaction units.…”

Spindle Single-Crystalline Rutile TiO2 with Excellent Cyclability for Low-Cost Li-Storage Materials

“…These results indicate that the R s value is a critical determinant of the anode performance of rutile TiO 2 . Although better performances were very recently attained for electrodes made of finely decorated rutile TiO 2 synthesized on a laboratory scale, − spindle TiO 2 has a distinct advantage in terms of cost and mass production. Spindle rutile is also expected to be applied as an anode in oxide-based solid-state batteries .…”

Phosphorus-doped TiO2 mesoporous nanocrystals for anodes in high-current-rate lithium ion batteries

“…Moreover, the discharge capacity could be recovered to 176 mAh g -1 with approximately ∼94% capacity retention when the current rate returns to 0.2 C, which represents an excellent rate capability. Compared to the lithium storage performance of other previously reported high efficiency doped titanium oxide-based materials (figure 8(d)), the P-TMC sample exhibits competitive rate capability, owing to improved electronic conductivity induced by P-doping [56][57][58][59][60][61][62][63][64][65][66]. To further verify the improved rate capability of the P-TMC sample, the longer cycling at a high rate of 10 C was also carried out.…”