Sodium Metal Anodes – The Influence of Neglected Parameters

R. Rupp, A. Vlad
Université Catholique de Louvain,
Belgium

Keywords: sodium metal, batteries, energy storage, reliability

Summary:

Next generation rechargeable batteries that go beyond the currently leading lithium-ion technology and replace lithium with sodium, awakened high interest in the past. This is mainly due to the high natural abundance and low cost of sodium, as well as the possible use of aluminum as current collector. Designing a suitable anode, however, is still a major problem. Avoiding host materials for ions and using sodium metal as an anode would be the ideal case, since metal anodes - Na as well as Li - offer theoretically the highest possible energy density in the respective batteries. Failure due to dendrite growth and persistent decomposition of electrolyte, however, still preclude the application of metal anodes. Finding a solution to these problems is rendered difficult by the simultaneous influence of many battery elements, including - but not limited to - the electrolyte, separator, nature of the current collector, cell architecture and the cycling procedure. One might find himself for example discarding an electrolyte, because the respective half-cells fail after a few cycles, while a simple change of the utilized separator could have led to hundreds of stable cycles. Facing the problem of dealing with many interacting components within a commonly used half-cell and the inconsistency in literature, a comparative study of many different influence factors is conducted here as a baseline for further improvements of Na-metal anodes. With this, we also try to shine some light on why many research groups find it so difficult to assemble half-cells with reproducible cycling behavior and why the performance of seemingly similar half-cells in literature can vary drastically from article to article