Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Chemistry

Supervisor

Oleg A Semenikhin

Abstract

This thesis focuses on the development of new anodes for Li ion batteries. Aluminium has been long considered as promising anode material for Li ion batteries because of its low cost, abundance, and low toxicity. Aluminium undergoes alloying with lithium through intermetallic LiAl formation which offers a relatively high theoretical capacity of 993 mAh/g compared to 372 mAh/g for graphite that is currently the principal anode material in commercial Li ion batteries. However, despite intensive research, all aluminium-based anodes tested so far suffered from rapid capacity fading and failure within first few cycles. Furthermore, there is insufficient understanding of the mechanisms of such capacity fading and the lack of ideas how to overcome this problem. In this work, we were able to demonstrate that the problems that have been plaguing Al anodes are not insurmountable and can be solved by judicious selection of the anode materials, their conditioning and treatment, as well as battery design. An important difference from all other studies is that we propose and justify the use of electrochemical approach to formation of the LiAl nanostructure directly on the bulk anode surface, as opposed to usual methods tested in the literature that involve application of various kinds of nanoparticles, nanowires, as well as thin evaporated or sputtered films. Using the approach developed in this work, we were able to fabricate and test battery prototypes with Al anodes, LiFePO4 cathodes and solid polymer electrolyte that showed sustained performance for more than 400 cycles over wide range of charge-discharge rates with high output voltage of 2.6 – 2.8 V and over 90% coulombic efficiency without any failure or capacity fading.

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