Repurposing Waste Tires as Tunable Frameworks for Use in Sodium-Ion and Lithium–Sulfur Batteries

Abstract

Selectively resourcing electrode components can provide a significant advantage in the uptake of next generation battery systems especially considering the performance of currently incumbent lithium-ion battery technology. This work systematically explores the use of a waste stream to generate electrode components and the influence that treatment and preparation factors have on electrochemical performance. A series of carbonaceous materials derived from waste rubber tires are prepared, involving pyrolysis at 700 and 900 °C as well as physical activation using a feed of CO2 gas. Results from Raman spectroscopy and X-ray powder diffraction (XRD) show an increase in graphitic character and larger particle size distribution of the carbon with increasing temperatures of pyrolyzation. They also reveal the impact of air and moisture on the evolution of crystalline impurities such as ZnS, CaCO3, and Ca(OH)2, and consequently their impact on the evolution of the carbon morphology. Galvanostatic cycling of Na-ion and Li–S cells involving the pyrolyzed rubber tires as an electrode component reveal different priorities as to which parameters to improve when designing materials for different cell systems. While higher specific capacities are achieved with more graphitic carbon morphologies in Na half-cells (300 mAh g–1 discharge capacity maintained after 20 cycles at 10 mA g–1), less graphitic morphologies were observed to reduce capacity fading experienced in Li–S cells (1003 mAh g–1 discharge capacity maintained after 18 cycles at 167.2 mA g–1, ∼ 76% of initial value). Ex situ Raman, XRD, and X-ray absorption near-edge structure (XANES) spectroscopies were used to elucidate the mechanisms involved in post electrochemical treatment. This work highlights a pathway to use waste tires to generate valuable electrode components (active material in Na half-cells and S hosts in Li–S cells), and a similar methodology could be applied to other waste streams.