Bismuth Islands for Low-Temperature Sodium-Beta Alumina Batteries

Abstract

Wetting of the liquid metal on the solid electrolyte of a liquid metal battery controls the operating temperature and performance of the battery. Liquid sodium electrodes are particularly attractive because of their low cost, natural abundance, and geological distribution. However, they wet poorly on a solid electrolyte near its melting temperature, limiting their widespread suitability for low-temperature batteries to be used for large-scale energy storage systems. Herein, we develop an isolated metal-island strategy that can improve sodium wetting in sodium-beta alumina batteries that allows operation at lower temperatures. Our results suggest that in situ heat treatment of a solid electrolyte followed by bismuth deposition effectively eliminates oxygen and moisture from the surface of the solid electrolyte, preventing the formation of an oxide layer on the liquid sodium, leading to enhanced wetting. We also show that employing isolated bismuth islands significantly improves cell performance, with cells retaining 94% of their charge after the initial cycle, an improvement over cells without bismuth islands. These results suggest that coating isolated metal islands is a promising and straightforward strategy for the development of low-temperature sodium-β alumina batteries.

Low-Temperature Molten Sodium Batteries

“…The low temperature, however, creates additional challenges at the interfaces between the different components. Poor wetting between molten sodium and the solid electrolyte is a well-known issue in molten sodium batteries that utilize β″-Al 2 O 3 as a separator. ,,, Poor sodium wetting results in poor interfacial contact and introduces high interfacial resistances, contributing to high overpotentials during cycling. To overcome such high resistances, a coating of tin (Sn, ∼ 170 nm) was deposited on the NaSICON separator to enhance interfacial charge transfer.…”

From High‐ to Low‐Temperature: The Revival of Sodium‐Beta Alumina for Sodium Solid‐State Batteries

“…on another Na/NiCl 2 cell. Here, bismuth deposition on sodium‐beta alumina effectively eliminated moisture and enhanced the wetting of liquid sodium, resulting in a decreased Ohmic resistance (see Figure 8B) [117] . This makes the application of bismuth a viable coating especially for low‐temperature Na/NiCl 2 cells and therefore, also novel cell systems with sodium negative electrodes working at low‐temperature.…”

Kinetic 2D Crystals via Topochemical Approach

“…Thus, layered compounds have been an essential component on account of high specific surface areas, minimal volume expansion, fast charge rates, diffusion length, and competitive energy storage density. [204][205][206] Therefore, outstanding lithium and sodium storage performance are expected to be exhibited.…”