Rational Design of Solid-Liquid Interphases for High-Energy Sodium Metal Batteries

Abstract

Advances in the basic science and engineering principles of electrochemical energy storage is imperative for significant progress in electronic devices. Metal based batteries comprising of a reactive metal (like Li, Na, Al) as the anode have attracted remarkable attention due to their promise of improving the anode-specific capacity by as much as 10-fold, compared to the current state-of-art Li-ion battery that uses a graphitic anode. A persistent challenge with batteries based on the metallic anode, concerns their propensity to fail due to short-circuits produced by dendrite growth during battery recharge, as well as by runaway of the cell resistance due to internal side reactions with the liquid electrolyte. In this talk, I will discuss my research that utilizes ion transport modeling and contemporary experimental efforts to fundamentally understand and to thereby develop rational designs for electrode-electrolyte interphases that overcome these challenges. On the basis of a linear stability analysis of dendrite growth during metal electrodeposition, we have showed that a small fraction of immobilized anions near the electrodes is important in stabilizing metals against dendrite formation. To evaluate this proposal, we designed polymeric electrolytes with tunable molecular weight and quantified the stability of metal electrodeposition in these systems. Direct visualization of electrodeposition using these electrolytes showed remarkable agreement with the theoretical predictions. Furthermore, when operated in a battery, the polymeric electrolytes demonstrated stable and dendrite-free galvanostatic polarization of sodium metal metals for over 100 hours at relatively high current density.