(Keynote) Beta Alumina – Prelude to a Revolution in Solid State Electrochemistry

Abstract

In 1971 Bob Huggins and I presented a paper at NBS, titled as above*. Little did we realize how prophetic our title would be. The remarkable ion transport properties of the beta alumina family not only led to searches for other ion conducting solids, but also to the use of mixed conducting materials as electrodes for electrochemical cells and shortly thereafter to the use of mixed conducting intercalation compounds for rechargeable lithium batteries. The studies at Stanford identified several key parameters that control the ionic conductivity of such ions as Na+, Ag+, Cu+, Li+, K+, Tl+and NO+. These parameters include the ionic size, the lattice spacing (diffusion path size), the defect concentration, defect type and diffusion mechanism. Later, similar studies on the WO3, MoO3, TiO2and VOPO4materials, all of which exist in several different structures with varying molar volumes, show the criticality of matching the diffusion path size to the mobile cation. The learnings from these studies will be described. *NBS Special Publication 364, Washington DC: U.S. Department of Commerce and National Bureau of Standards, 1972, 139-154

Solid-State Electrochemical Synthesis of Silicon Clathrates Using a Sodium-Sulfur Battery Inspired Approach

“…In addition, the application of electrochemical analytical methods enables a deeper understanding of the thermodynamic processes involved in the formation of intermetallic clathrate phases. We therefore show that beta alumina, for which the original discovery was deemed by Whittingham and Huggins to be the z E-mail: candace.chan@asu.edu "prelude to a revolution in solid-state electrochemistry" due to its role in catalyzing the search for ion conducting materials crucial to the development of rechargeable batteries, 31 can also play a key role in enabling solid-state synthesis methods for the preparation of novel electrode materials for these batteries.…”