Study on graphene based materials for lithium ion battery and supercapacitors applications

Abstract

The thesis explores the utilization of graphene-based materials for both supercapacitors and lithium-ion batteries (LIBs), highlighting their unique features and performance enhancements. It covers various aspects of graphene-based electrodes and their applications in energy storage devices. The first step described in the thesis involves the synthesis of microwave- radiated graphene for studying supercapacitor applications. This method is cost-effective and time-saving compared to traditional methods that involve chemical reagents. The structural and morphological properties of the synthesized graphene were analyzed using techniques such as X-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, and FTIR spectroscopy. The electrochemical properties of the graphene-based electrode were evaluated using both a three-electrode and a two-electrode system. The electrode exhibited a specific capacitance of 355.35 F/g at a scan rate of 5 mV/s and a Coulombic efficiency of 94.4% after 2000 cycles, indicating its favourable characteristics for supercapacitor applications. The study further explores the supercapacitive performance of graphene nanoribbons derived from multi-walled carbon nanotubes (GNRs). Acid- processed carbon nanotubes were exfoliated and reduced using microwaves to obtain high-quality graphene nanoribbons. Morphological and spectroscopic analysis confirmed the successful exfoliation of nanotubes. Additionally, the thesis investigates a novel approach to enhance the supercapacitive properties of holey carbon nanotubes (HCNTs). HCNTs were created by microwave treatment of carbon nanotubes containing intrinsic catalyst nanoparticles. The resulting HCNTs exhibited an improved specific capacitance due to their increased specific surface area and the formation of cavities/holes on the walls of nanotubes.