Synthesis of Li4Ti5O12 negative electrode material in a fluidized bed thermogravimetric analyzer

Abstract

AbstractSpinel lithium titanate (Li4Ti5O12) is the most promising negative electrode material for energy storage which can be applied in lithium‐ion batteries lithium‐sulphur batteries, and supercapacitors. However, the high cost of Li4Ti5O12 powder and its high molecular weight limit its application due to the complicated synthesis process. In this work, a facile solid‐state reaction in a fluidized bed reactor was used for the first time to synthesize spinel Li4Ti5O12 using lithium carbonate and titanium oxide as solid reactants. We investigated the fluidization behaviour of starting materials and studied different synthesis temperature in fluidized and fixed beds. X‐ray diffraction and scanning electron microscopy were employed to characterize the samples. The results demonstrate that the mixture of Li2CO3 and TiO2 had a complete fluidization velocity of 0.88 cm/s and showed good fluidization behaviour. Pure spinel Li4Ti5O12 was obtained via solid‐state reaction in a fluidized bed reactor at 800°C for 30 minutes, which is much lower than a conventional solid‐state reaction in a fixed bed or muffle furnace. By this novel method, the micro‐sized Li4Ti5O12 particles (6‐8 μm) have hollow porous structure composed of nano‐sized particles (<100 nm) synthesized. According to the experimental results, we proposed a different reaction mechanism for the synthesis of Li4Ti5O12 in fluidized beds which explains how the Li2CO3 and TiO2 react to form hollow lithium titanate nano‐structured micro‐particles in fluidized beds. The bulk density, surface area, and bulk conductivity of the synthesized Li4Ti5O12 are 3240 kg/m3, 4.6 m2/g, and 3.90 × 10−6 S/cm, respectively.