Akkisetty, B
(2014)
Molybdenum Oxide and Tin Oxide/Sulfide Nanostructured Materials for Anodes in Lithium Ion Batteries.
PhD thesis, Indian Institute of Technology, Hyderabad.
Abstract
The ever-increasing global warming due to gaseous emissions, the burgeoning fuel costs and their limited availability have escalated the search for viable energy efficient alternatives. During the last two decades, most of the portable electronic devices such as cellular phones, laptops, camcorders and notebooks etc., have been using the Li-ion battery (LIB) technology. Li-ion batteries (LIBs) are considered promising for even powering electric and hybrid electric vehicles (EVs). However, the current electrode materials are too costly to penetrate into the EV industry, for not only, does it need high performance materials, but at the same time, the materials should be environmentally benign. In terms of performance, nanostructured materials offer many advantages; the large contact area between the electrode and the electrolyte and the short diffusion path lengths due to small sized crystallites, lead to higher charge storage capacity and increased power rate compared to their bulk counterparts. In commercially available LIBs, the anode is, typically, graphite, which, is characterized by a rather low theoretical specific capacity of 374 mAh g-1. The low capacity of the anode material limits the performance of battery. Benefiting from nanotechnology, metal oxides (e.g. MoO2) through conversion and tin based oxides and sulfides through alloy/dealloy mechanisms can offer a large lithium storage capacity i.e., almost two times more than the current graphite anodes. However, despite delivering high energy densities, these materials experience substantial volume variation during Li+ insertion/extraction process, which manifests in the pulverization of the electrode material and rapid decline of capacity. To counter the aforementioned issues, oxides/sulfides in nanostructured forms and their composites with carbonaceous materials such as graphene, multiwalled carbon nanotubes or MWCNTs and conducting polymers are used.
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