Monday, 30 May 2022
West Ballroom B/C/D (Vancouver Convention Center)
We live in a world where we find ourselves in constant need of better materials. Today, we have a need to not only discover materials with enhanced properties but to do them urgently—there is a need to establish a quantitative design framework to accelerate materials development. Finding these design principles is the focus of my research group. In this talk, I will share some of our ongoing work to enhance the lifespans of lithium battery materials. We demonstrated how film straining of intercalation electrodes can circumvent its structural degradation upon repeated cycling. While suppressing chemo-mechanical degradation has been a longstanding problem, our paper initiates a new line of research by using mechanical stress states to regulate the energy landscape in intercalation materials and to thus improve their lifespans. For example, in our recent work [1], we propose a strategy to prevent the chemo-mechanical degradation of intercalation electrodes: we show that by engineering suitable film strains we can regulate the phase transformations in thin-film intercalation electrodes and circumvent the large volume changes. We test this strategy using a combination of theory and experiment to a representative example (LixV2O5 with multiple phase transformations). Our findings show that tensile film strains lower the voltage for phase transformations in thin-film V2O5 electrodes and facilitate their reversible cycling across a wider voltage window without chemo-mechanical degradation. These results suggest that film strain engineering is an alternative approach to preventing chemo-mechanical degradation in intercalation electrodes. Beyond thin-film electrodes, our findings from this study are applicable to the study of stress-induced phase transformations in particle-based electrodes and the thin surface layers forming on cathode particles.
Reference
[1] Zhang, Delin; Sheth, Jay; Sheldon, Brian W.; Renuka Balakrishna, Ananya. "Film strains enhance the reversible cycling of intercalation electrodes". Journal of the Mechanics and Physics of Solids 155, p104551 (2021).