Fabrication of graphene oxide and graphene foams for Li-ion batteries

Bakhtiari, Bahareh (2019) Fabrication of graphene oxide and graphene foams for Li-ion batteries. [Thesis]

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Graphene based materials are very promising owing to their fascinating characteristics such as extremely tunable surfaces, outstanding electrical conductance, good chemical stability and outstanding mechanical performance for energy storage applications. This project summarizes recent developments on 3D graphene network electrodes for Li-ion battery applications. A foam-like graphene material can be prepared by chemical vapor deposition and hydrothermal reduction of graphene oxide suspensions. The graphene foam has a much higher capacity than conventional graphite anode, and it possesses better rate capability as compared to powder like graphene active materials. A new super-light graphene aerogel (GA) was effectively synthesized with a high electrical technique using a low cost and accessible method. More importantly, our synthesis approach compared to the common graphene oxide (GO) reduction temperature (180 °C) involves low temperature (95°C) where the promising GO reduced with different reducing agents is achieved through freezing. In this work, we systematically investigate the effects of various reducing agents including ammonia, hydro-iodic acid, and ascorbic acid at different hydrothermal reaction time (4, 8, 24 hours) and reducing agent dosages (0, 50, 120, 200 μL) on the formation of foam, electrical conductivity, and morphology of GA. The results reveal that graphene aerogel reduced by ascorbic acid possesses the most outstanding performance on mechanical strength and reutilization but has moderate electrical conductivity (9.4 S/m). Whereas, the sample obtained with HI exhibits the highest electrical conductivity (12.1 S/m). However, this sample reveals poor mechanical strength. The graphene aerogel reduced by ammonia is very sensitive to the reaction time and temperature and has moderate mechanical strength and the lowest electrical conductivity (7.5 S/m). Therefore, ascorbic acid is a very promising reducing agent for the hydrothermal process as the resulted graphene aerogel had good electrical conductivity and great mechanical strength
Item Type: Thesis
Uncontrolled Keywords: Graphene. -- Graphene oxide. -- Graphene foam. -- Graphene aerogel. -- CVD method. -- Grafen. -- Grafen oksit. -- Grafen köpük. -- Grafen aerojel. -- CVD metot.
Subjects: T Technology > TA Engineering (General). Civil engineering (General) > TA401-492 Materials of engineering and construction. Mechanics of materials
Divisions: Faculty of Engineering and Natural Sciences > Academic programs > Materials Science & Eng.
Faculty of Engineering and Natural Sciences
Depositing User: IC-Cataloging
Date Deposited: 12 Mar 2020 15:41
Last Modified: 26 Apr 2022 10:33
URI: https://research.sabanciuniv.edu/id/eprint/39763

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