Past event
School of Chemistry Colloquium: Dr Yang Xu (UCL) Charge storage mechanism of "star" electrode materials for post-lithium-ion batteries
Developing alternative energy storage technologies beyond lithium has become a prom¬inent slice of global energy research portfolio, shaping future electrified mobility, the utilization of renewable energies, and large-scale stationary energy storage. Na-ion batteries (NIBs) are receiving global attention in recent years due to the announcement of commercializing products by some of the largest NIB manufactures in the world, while the development of K-ion and Ca-ion batteries (KIBs and CIBs) is at an early stage. Understanding charge storage mechanism is crucial for the performance improvement of post-Li battery technologies. In this talk, I will first discuss utilizing K-ion battery cathodes, K-pre-intercalated Prussian blue analogs (K-PBAs), as NIB cathodes. I will show that having a level of [Fe(CN)6]4- anion vacancies in K-PBAs can maximize K-ion intercalation and minimize Na-ion intercalation, which results in the increase in discharge voltages and rate capability. Also, when utilizing K-PBAs and Na-PBAs in Ca-ion batteries, K-ion/Na-ion intercalation is preferred by the PBA structure over Ca-ion intercalation even in the Ca-ion electrolyte. This is a profound effect that has been overlooked in the literature of Ca-ion batteries. As a result, Ca-ion intercalation can be enhanced when the K-ion/Na-ion content in the pristine PBAs is reduced, shifting to a Ca/K or Ca/Na co-intercalation process. Then, I will discuss our recent investigation of the K-ion storage mechanism in commercial MoS2, which has not been exclusively investigated and therefore remains unclear. I will show that the conversion reaction of MoS2 is partially reversible and accompanied by S anionic redox reactions with K and furthermore, the reaction pathway differs when operating via different charge/discharge routes. By controlling the routes, dual reactions of cationic Mo and anionic S redox take place simultaneously, which can improve the stability of the MoS2 anode while maintaining K-S battery chemistry.
This event is open to final year undergraduate project students, MSc students, PhD students, post-doctoral research associates and academic staff.