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Doja, Somi

University of British Columbia

An indispensable component of many land-based transportation systems are tires. Tires are composed of materials resistant to both physical and chemical changes and do not readily degrade naturally in the environment. Particularly, mining tires are designed to operate in harsh environments and hence are highly resistant to degradation. However, despite their omnipresence, the recycling of mining tires has not been thoroughly researched, and without suitable end-of-life solutions, discarded mining tires pose dire ecological and economical challenges. In this research, chemical and heat treatment methods were employed to study the upgrading of carbon black obtained from a tire recycling operation. Chemical treatment was employed to remove inorganic impurities present in the char, while a heat treatment was required for the removal of volatiles (for example sulphur) which could not be removed by chemical treatments. Acids including HCl, HNO₃, H₂SO₄ were successful in removing Zn, Fe, and other metallic impurities, whereas NaOH and KOH were used to remove Si. Heat treatment experiments under N₂ proved to be successful in S removal. A combination of chemical treatment (5M HCl and 10M NaOH leaching), along with thermal treatment (950°C), was ideal for removing most impurities from the recovered carbon black (rCB) yielding a purity of >98 wt%. Activation experiments were performed on purified rCB using KOH and CO2. Activated carbon obtained from KOH treatment exhibited the highest surface area of 994 m²/g. Purified and activated rCB was tested for Li-ion battery applications. The activated rCB anode showed a maximum discharge capacity of 1853 mAh/g. However, the capacity drop for activated rCB cells was greater than 40% after the first cycle of charge, likely due to the formation of solid electrolyte interface and irreversible side reactions. In addition, rCB was also used as an additive material in lithium titanate oxide (LTO) battery anodes. rCB proved to be a stable additive to LTO anode with negligible irreversible capacity loss (<10%). Electrochemical testing of cells made with LTO electrodes revealed that activated rCB additives had better discharge capacity values compared to Super-P additive. Hence this study demonstrated that mining tire-derived rCB could be used as an additive material for commercial Li-ion battery applications.

Text

2023-06-07

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/81808

Mechanical Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/