Doctor of Philosphy
Institute for Superconducting and Electronic Materials (ISEM)
Rajagopalan, Ranjusha, Nasicon based materials for high voltage lithium-ion and sodium-ion batteries, Doctor of Philosphy thesis, Institute for Superconducting and Electronic Materials (ISEM), University of Wollongong, 2017. http://ro.uow.edu.au/theses1/129
Durability, power density, and energy density are the three key factors for an energy storage system that make the device promising for any portable electronic and automobile applications. For the past few decades, lithium-ion battery (LIB) technology has attracted considerable attention because of its promising electrochemical properties. As a classic example, olivine structured LiFePO4 cathode has risen to prominence as a key material for batteries in many commercial applications. The increasing demands for lithium based batteries are yet to be complemented by its supply. Thus, it will be difficult for stand-alone lithium based batteries to meet the increasing demands for electric vehicles, grid-scale energy storage, and portable electronic devices markets. These huge demands have made researchers to focus on improving the performance of existing lithium material by introducing conducting secondary phases such as carbon, doping the active material with a cationic phase, nanostructuring the active material, engineering the device, etc. The realization of increasing energy demands has also led scientists to work on alternate energy storage areas such as sodium ion batteries (SIBs), potassium ion batteries (PIBs), magnesium ion batteries (MIBs), etc. Among them, SIBs are considered to be an ideal substitute or alternative to LIBs, since the properties and electrochemical storage mechanism of lithium and sodium are more or less similar. Another attractive feature of sodium is its abundance (considered to be practically inexhaustible) and its even distribution around the world, with a Clarke’s number of 2.644 (an indication of material’s abundance), which makes sodium cost effective and potentially able to satisfy increasing energy demands in the future. Nevertheless, considering their energy density as well as their durability, the SIBs are still behind the LIBs. In order to address this issue, new high voltage materials which can provide stable performance are highly sought after. The scope of this thesis work is mainly to try to understand ix and address the aforementioned problems from the perspective of both LIBs and SIBs.