Cointercalation and In-Situ Plating for Advanced Sodium Batteries

Abstract

In the push to decarbonize our electricity and transportation sectors, the continued reduction in the cost of electrical energy storage is critical. While Li-ion batteries have emerged as the best-suited technology for grid storage and electric vehicles, the cost sensitivity of these applications and concerns over the limited reserves of Li motivate the development of alternative strategies for low-cost electrical energy storage. In this dissertation, I explore opportunities for developing advanced batteries based on Na chemistries. Rather than working on Na-ion cells analogous to commercial Li-ion cells, I focus on the unique advantages of Na. Specifically, I study (1) the fast cointercalation of Na ions and diglyme solvent into graphitic carbon, and (2) the stable electroplating of Na metal on carbon and Na alloy substrates. Building on my findings, I develop the first sodium metal battery using an "anode-free" assembly, where all the sodium is initially stored in an air-stable cathode material. Through this approach, I demonstrate cell performance attributes (such as specific energy, energy efficiency, and voltage stability) that are attractive for low-cost, high-performance electrical energy storage applications.