Event Description
Zhi Li, PhD,
Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada “Sustainable Electrode Materials for Supercapacitors and Batteries” Renewable energy and energy storage technologies have been attracting attention because of their potential to minimize the environmental impact associated with energy conversion and consumption. An important question often overlooked is how renewable are the energy storage devices themselves? In the first part of this seminar, I will demonstrate that the nanostructures created by nature as biomass can be readily converted into renewable carbon materials with fine nanostructures. With individually optimized structures and compositions, these carbons exhibit excellent performance as electrode materials for aqueous supercapacitors (550F/g), ultrafast ionic liquid electric double-layer capacitors (150 F/g), Li-ion batteries (over 1,000 mAh/g) and Na-ion batteries (300 mAh/g). Low-cost hybrid energy storage devices have been developed based on these carbons. With energy densities about 15-50% of Li-ion batteries and 10 times longer cycle life, these hybrid devices hold promise in stationary energy storage. Na-ion batteries (SIBs) are gaining interest as a potentially lower cost alternative to Li-ion batteries (LIBs), with markedly lower cost of sodium (1/20th of lithium) due to wider global abundance. Unfortunately SIBs do not perform as well as LIBs in term of capacity and cycle life. The second part of my talk will focus on the Na storage and failure mechanism of tin oxides and antimony anodes. By systematically investigating the phase transition and kinetics of sodiation v.s. lithiation process, we demonstrated that both the conversion process of SnO2 and the subsequent alloying process of Sn are completely reversible in LIBs, but not in SIBs. By combining in situ TEM with ex situ characterization technologies, we show that the time-dependent buckling and localized separation of the sodiated Sb films are responsible for the poor cycle of Sb anode. These findings pave the way for developing robust SIBs anode materials. |
