Synthesis and Characterization of Electrode Materials for Lithium ion Batteries

Abstract

This doctoral work focuses on the cost-effective and scalable synthesis of transition metal newlineoxides (TMO) based high-performance anode materials for rechargeable Li-ion batteries newline(LIBs). Graphite is the most widely used anode material for LIBs for its low cost and high newlineabundance, however, the limited specific capacity of 372 mA h g-1 newline newlineis unable to satisfy the newlinegrowing energy demand. Although silicon as an alternative anode material possesses high newlinetheoretical specific capacity, the uncontrollable volume change during cycling puts a newlinesignificant barrier towards its practical implementation. On the other hand, transition metal newlineoxides can be a suitable alternative to that of graphite or silicon as anode materials, thanks to newlinetheir high theoretical capacity (800 1200 mA h g-1 newline newline), structural stability, and high abundance newline newlinewhich has attracted significant research attention recently. newlineThis doctoral thesis is focused on the development of different binary transition metal oxides newlineof the type AB2O4 (MgCo2O4, MnCo2O4, and CoFe2O4) and study the effect of different newlinesynthesis condition (different precipitating agent, annealing temperature, substitution, newlinecomposites formation, etc.) on their physiochemical properties evolution and electrochemical newlineperformance as LIB anode. The synthesized materials were characterized via different newlinetechniques, such as XRD, XPS, FESEM, TEM, BET, etc. The electrochemical performance newlinewas carried out in half cell against Li metal to determine specific capacity, rate capability, newlineand cycle stability for the selected anode. The cycled cells were further analyzed to newlineunderstand the effect of cycling on the phase and morphology change of the active materials. newlineMgCo2O4 was synthesized using a simple precipitation method and the effect of the newlineprecipitating agent (LiOH, NaOH, KOH), calcination temperature (400-800 and#778;C) on the newlineelectrochemical performance has been investigated. It is observed that the morphology and newlinecrystallinity play a crucial role in determining the electrochemical performance. MgO is newlineelectrochemically inactive towards lithium-ion storage, however, when present in controlled newlinefraction could stabilize MgCo2O4 during continuous cycling. CoFe2O4 nanoparticles were newlinesynthesized via cost effective molten salt method and were employed as anode materials. newlineThis thesis also demonstrates the effect of multi-walled carbon nanotubes (MWCNT) as a newlineconductive backbone towards improving the rate capability and cycle stability of TMO newline(MnCo2O4) based anode. newline