Binder free Silicon Anodes for Advanced Lithium Ion Batteries

Choudhury, Rini and Martha, Surendra Kumar (2016) Binder free Silicon Anodes for Advanced Lithium Ion Batteries. Masters thesis, Indian Institute of Technology Hyderabad.

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Abstract

Silicon has emerged as an attractive anode material for Lithium Ion Batteries since it has a high theoretical capacity of 4200 mAh/g, corresponding to the formation of Li22Si5 alloy. Unlike graphite anodes which rely on intercalation and deintercalation of Li+, silicon anodes depend on an alloying-dealloying process. However, the formation of Li-Si binary alloys involves volume modification of ~400%, and the repeated expansion and contraction during lithiation- delithiation leads to pulverization and consequent failure of the cell. To meet this challenge, we have designed binder-free silicon anodes that can circumvent the problem of pulverization. This work describes the synthesis of Si nanoparticles (NPs) by reverse micelle approach, followed by structural characterization of the material by X -Ray diffraction, Scanning Electron Microscopy and Raman Spectroscopy. The electrochemical performance of the Si active material as anode material for Lithium Ion Batteries was tested in two-electrode Swagelok type cells using galvanostatic charge-discharge cycling at different levels of depth-of-discharge, and also by impedance spectroscopy. Two approaches have been employed in the designing of the electrodes: firstly, the Si NPs were manually embedded on Cu foil as current collector by the application of pressure, and secondly, chitosan, polypyrrole -hydrogel and P-Pitch were used as novel binders in developing 3D electrode architecture on carbon fibre.

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