Nanostructured Carbon Materials as High Capacity Anodes for Lithium Ion Battery

K, Manohar (2015) Nanostructured Carbon Materials as High Capacity Anodes for Lithium Ion Battery. PhD thesis, Indian Institute of Technology Hyderabad.

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Abstract

One of the major objective of this work is to identify the key parameters in hard carbon materials to improve their electrochemical performance when used as anode materials for lithium ion battery. We have used different polymer precursors for carbon such as SU-8 negative photoresist, candle soot and resorcinol-formaldehyde xerogel. Although each of these precursors yields hard carbon upon pyrolysis, they are different in terms of their microstructure, texture and crystallinity as characterized thoroughly using X-ray diffraction, Raman spectroscopy, small angle X-ray scattering, scanning electron microscopy, high resolution transmission electron microscopy and Brunauer Emmett Teller surface area. We have employed different synthesis methods such as spin coating, electrospinning and sol-gel emulsion to fabricate these nanostructured carbon materials with wide range of morphology from thin films to nanofibers to nanoparticles. We have then studied in detail the electrochemical behavior of all these carbon nanomaterials and developed an understanding to correlate the crystallinity and morphology with their electrochemical performance in terms of charge/discharge capacity, cyclic stability, coulombic efficiency and cyclic life time. Based on this understanding, we have devised several strategies to minimize the irreversible capacity losses in first cycle associated to solid electrolyte interface formation, and on the other hand, maximize the reversible capacity. One such approach was based on fine-tuning the pyrolysis temperature profile. Another scheme used was graphitization of hard carbons at reduced temperature using metal as catalyst in polymer precursors.

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