Biomass Derived Hard Carbon as Anode Materials for Sodium Ion Batteries

Yadav, Alisha and Martha, Surendra Kumar (2018) Biomass Derived Hard Carbon as Anode Materials for Sodium Ion Batteries. Masters thesis, Indian Institute of Technology Hyderabad.

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Abstract

The era of wide-scale implementation of renewable energy sources like sun, wind, hydrothermal energy etc., calls the urge for inexpensive and efficient energy storage systems for the smooth integration of these intermittent energies into stationary as well as grid application. Though the Li-ion batteries (LIBs) have become essential in everyday technology, the problems like safety, lifetime, poor low-temperature performance, non-ideal for grid-scale energy storage, less abundance of Li resources, cost etc. are still prevailing. To overcome these issues, Na-ion batteries (NIBs) have been attained a considerable interest in the recent years as a possible alternative to LIBs. The advantages of natural abundance, low cost, similar chemical properties like Li and comparative redox potential (2.714 V vs. Na/Na+) of Na compared with Li (3.06 V vs. Li/Li+), making NIBs as a promising alternative to LIBs for large-scale energy storage systems and sustainable applications. Even though Na and Li have comparative redox potential, and the same valence of lithium, the volume of sodium ions is ~2 times more than that of lithium and ~3 times in terms of atomic weight. Therefore, sodium-based materials have disadvantageous to lithium-based materials in terms of energy density. Besides, the current versions have a very low capacity and cycle life. The conventional anodes for LIBs such as graphite and Si based materials are found to be badly inefficient as anodes for NIBs. Hence, hard carbon is used as the anode (NaxC6), in Na-ion cells. In the present study, we have used rice husk for the synthesis of hard carbon. Rice husk is a biowaste and is easily available so the synthesis process is economical and easy. The hard carbons have been synthesized by acid activation and pyrolysis of rice husk at different carbonization temperatures (700, 900, 11000c). The three samples that are prepared are ARH-700, ARH-900 and ARH-1100. The phase structure of the synthesized hard carbon sample was characterized by recording the X-ray diffraction (XRD) pattern. The crystalline structures of the carbons are further characterized by Raman spectroscopy analysis. The morphology of the synthesized hard carbon sample was studied using SEM analysis which confirms the presence disordered structure of hard carbons. The electrochemical studies were carried out and it was found that ARH-1100 shows the best performance with initial irreversible capacity of 735 mAhg-1 and the first charging capacity of 335 mAhg-1 .

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