Nitrogen gas interaction on silica aerogel – Effects on hydrophobicity, surface area, porosity, and lithium-ion battery performance

Abstract

The present study evaluates in-situ pressurized nitrogen gas (N2) purging effect on tuning hydrophobicity of silica aerogel, and the effect on lithium-ion battery applications. The mesoporous silica aerogels are prepared using sol-gel process, followed by supercritical drying with ethanol solvent extraction, and dry nitrogen gas is pressurized and purged to remove the condensed ethanol vapor from the hydrothermal vessel. The pressurized nitrogen gas molecules interact with silica aerogel at 255 °C and remove surface reactive OH groups and increase the surface roughness and hydrophobicity, which is evident from the reduction of Si-OH infrared vibration bands, porous electron microscopic images and increased contact angle. It also increases the surface area, compresses the pores, and carbonizes the organics, which is confirmed from surface area measurements and quantitative X-ray photoelectron spectroscopy analysis. Also, the powder X-ray diffraction patterns confirm the amorphous nature of silica aerogel. The Li-ion battery performance of the obtained amorphous silica aerogel is examined using cyclic voltammogram and charge-discharge studies. The present study enumerates that apart from surface area and in-situ carbon, the pore size is also an important criterion in maintaining better battery performance.