Organic-catalysis-free and low-temperature synthesis of vertically aligned graphene nano-stripes for enhancing performance of LiFePO4-based Li-ion batteries

Abstract

Practical and efficient integrations of graphene into real applications are identically important as their various superior properties. Among various graphene-related materials, vertical graphene stripes (VGSs, in nanoscale) are one kind of interconnected graphene sheet oriented perpendicularly to the growth substrate with 3-dimensional porous structures. Due to the high surface-to-volume ratio, VGSs could be an even better candidate than pure graphene when considering the physical mixing of graphene-related materials with other substances. In this study, we demonstrate an organic-catalysis-free and low-temperature approach (<300 °C) to efficiently grow VGSs without utilizing any environmentally harmful chemicals. The as-synthesized VGSs were comprehensively characterized by means of different microscopes, Raman spectra, X-ray diffractometers, and electrochemical tests. Compare with existing literature, a discrepancy in terms of growth mechanism was first discovered via time-independent Raman spectra, showing that the horizontal buffer layers are not necessary prior to the formation of VGSs. More importantly, the as-synthesized VGSs were introduced into the cathode of Li-ion batteries, and outstanding functionalities such as specific capacity and charge/discharge stabilities were found to even outperform carbon black (C65), the classic commercial conductive additive.

Keywords

• Vertical graphene stripe
• Plasma enhanced chemical vapor deposition
• Organic-catalysis-free
• Low-temperature synthesis
• Raman spectroscopy
• Li-ion battery