MSE Graduate Seminar: Development of a Next-generation Rechargeable Aluminum-ion Battery

Date: Apr 22, 2021

Presenter: Kok Long Ng (PhD candidate, 2nd Seminar)

Supervisor: Prof. G. Azimi

ABSTRACT: The ever-increasing demands for clean and sustainable energy storage solutions have driven researchers around the world to explore beyond lithium-based battery chemistries that utilize earth-abundant materials. To this end, aluminum (Al)-ion battery presents itself as a promising alternative as it can offer good power and energy densities, better safety features while at a lower material cost. Advanced Al-ion batteries integrate dialkylimidazolium chloride-based chloroaluminate ionic liquids (ILs) into battery chemistry due to desirable properties including high conductivity, high ionicity, and wide liquidus range. However, drawbacks including small-scale productivity, high cost, and non-biodegradability greatly shadow the scalability of Al-ion batteries employing these ILs. As the field is in its infancy, there is still considerable room for improvement, particularly regarding the charge-storage capacity of positive electrode materials. To address these challenges, the main objective of this Ph.D. research is to develop a new generation of high-performance Al-ion batteries employing environmentally sustainable and economically viable battery components. Two major research focuses have been identified: (i) exploration of cost-effective electrolyte systems that demonstrate comparable, or even superior properties compared with existing electrolytes, and (ii) exploration of novel electrode materials that can offer better charge-storage capacity. Initial efforts are focused on investigating the electrochemical performance and fundamental properties of a cost-effective electrolyte, made of AlCl3 and widely available urea. Critical insights including Al electroplating/stripping mechanism, attainable cell-level energy, relative abundance of ionic and neutral speciation, are obtained. Subsequent effort has led to the development of a novel Al-ion battery employing trimethylamine hydrochloride (TMAHCl)-based IL. The TMAHCl IL is a low-cost alternative to conventional dialkylimidazolium chlorides, and it offers superior performance to conventional ILs in terms of electrochemical stability window (ESW), specific-, and volumetric anodic capacity. To obtain fundamental insights into designing high-performance ILs, the following study is focused on providing a clear and quantitative description of the underlying effects of AlCl3/organic chloride molar ratio (r) and organic chloride type, particularly on the electrochemical and transport properties of chloroaluminate ILs. Finally, to explore high ion-storage capacity positive electrode material for Al-ion batteries, a novel C3N/black phosphorene heterostructure is under development. The knowledge developed throughout this Ph.D. research is expected to pave the path towards achieving a low environmental footprint, cost-effective, and performant Al-ion batteries suitable for large-scale applications.