Nano/micro structured porous Li4Ti5O12 synthesized by a polyethylene glycol assisted hydrothermal method for high rate lithium-ion batteries

Abstract

In this study, a new polyethylene glycol (PEG)-assisted hydrothermal method was proposed to prepare nano/micro structured porous Li₄Ti₅O₁₂ for high rate lithium-ion batteries. The fabrication process involves a modified hydrothermal synthesis using PEG as a structure directing agent and a subsequent calcination procedure. X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and nitrogen adsorption–desorption analysis were used to characterize their morphologies and structures. Such Li₄Ti₅O₁₂ shows spheroidic morphology with a size of 1–4 μm, assembled by well-crystalline nanoparticles of ca. 15 nm. The nano/micro structured Li₄Ti₅O₁₂ presents rich pores of 10–70 nm with a specific surface area of 80.1 m² g⁻¹ and a pore volume of 0.45 cm³ g⁻¹. The Li₄Ti₅O₁₂ annealed at 600 °C has the perfect crystallization and developed porosity, and exhibits ultrahigh rate capability with a reversible capacity of 132 mA h g⁻¹ at 20 C, and excellent capacity retention over 100 cycles.