Manganese Oxide/reduced Graphene Oxide Hybrids as Anode Materials For High-performance Lithium-ion Batteries

Open Access
Author:
Ayhan, Ismail Alperen
Graduate Program:
Materials Science and Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
December 11, 2014
Committee Members:
  • Qing Wang, Thesis Advisor
Keywords:
  • Energy storage
  • Lithium-ion batteries
  • Hybrid materials
  • Graphenes
  • Manganese oxides
Abstract:
In this thesis project, Mn3O4/rGO hybrid nanomaterials using as anode for lithium-ion batteries have been studied. These anode materials have been characterized by variety of techniques to show the effect of the structures and composition on the electrochemical performance of lithium-ion batteries. A literature review summarizes the overview and the principles of lithium-ion battery, electrode materials and compounds. Nanosized manganese oxide (Mn3O4) particles, active materials for specific capacity, grown on reduced graphene oxide (rGO), support material for electrical conductivity, have been prepared via a facile in-situ synthesis method in the mass ratios of 1:1(MRG1), 2:1 (MRG2) and 3:1 (MRG3) for negative electrode at high performance lithium ion batteries (LIBs). Optimizing weight feed ratio of Mn3O4 on the rGO surface has demonstrated better results within MRG2 hybrid material in terms of physical, structural and electrochemical properties. X-ray diffraction (XRD) results of MRG2 hybrid material present that all peaks are outstandingly indexed to Hausmannite phase of Mn3O4, and the excellent purity of Mn3O4 crystalline phase is obtained. Raman spectroscopy also confirms the presence of Mn3O4 and rGO in MRG2 hybrid material. Besides, SEM and TEM images of MRG2 hybrid material show that Mn3O4 nanoparticles are homogenously dispersed on rGO nanosheets (rGOs) as well as high crystallinity. Electrochemical testing shows that the MRG2 electrode has possessed a high reversible capacity, cycling stability, and rate capability by the virtue of efficient electron conduction pathways and high surface area properties promoted by rGOs. Cyclic voltammetry measurements of MRG2 materials are indicated overlapped peaks corresponding to lithium insertion and extraction. In A.C. impedance measurements, low conduction loss is observed after a certain number of cycling in MRG2 electrode.