Optimization of Basic Parameters of New Sodium Electrolytes Based on Tailored Anions

Secondary battery technology is currently based on Li-ion technology. Assuming substantial  development of electrical vehicles and/or different portable devices, the lithium sources might be not sufficient to fulfill total market demands. Strategically, it is a suitable moment to  research alternatives to lithium-based energy storage technologies. A natural candidate for the replacement of lithium is sodium. Standard potential of the Na/Na⁺ (-2.71 V) is slightly lower than the potential of Li/Li⁺(-3.05 V). At the same time, sodium is both the most abundant alkali metal on Earth and cheaper than lithium.

The first sodium battery, Na (Hg)-C cell, was built in 1870. Later, sodium batteries which were built in 1960s (Na-S) and 1980s (Na-NiCl₂). All of these technologies exhibit low energy density. The Na-NaSICON-S system, built in early 2000s, exhibits a much higher energy density[1]. However, a major problem of this battery, which remains unsolved up to now, is its high working temperature. Therefore, the current challenge in sodium battery research is to reduce the operating temperature from 270-350°C to room temperature. In order to reach this goal, the ionic conductivity of the electrolyte must be optimized.

New sodium salts with heteroaromatic anions, used in electrolytic media are being investigated because they are environmentally benign, facile to synthesize and are not expensive to produce at an industrial level. In addition, they show promising ionic conductivities in liquid and solid electrolyte media and possess good electrochemical stability at room temperature. Moreover, these salts have been preliminary characterized in the half cells; where the anode specifically was fabricated using Microwave Plasma Chemical Vapor Deposition from germanium and antimony precursors[2] and cathodes were obtained from independent laboratory.

References:

[1] P.V. Wright, British Polym. J. 7 (1975) 319

[2] M. Marcinek, L. Hardwick, G. Żukowska, R. Kostecki Microwave Plasma Chemical Vapor Deposition of Graphitic Carbon Thin Films, Carbon 48 (5) 2010 1552-1557