Uncharted Waters: Super-Concentrated Electrolytes

As a legacy left behind by classical analytical electrochemistry in pursuit of ideal electrodics, and classical physical electrochemistry in pursuit of the most conductive ionics, the study of non-aqueous electrolytes has been historically confined within a narrow concentration regime around 1 molarity (M). This confinement was breached in recent years when unusual properties were found to arise from the excessive salt presence, which often bring benefits to electrochemical, thermal, transport, interfacial, and interphasial properties that are of significant interest to the electrochemical energy storage community. This article provides an overview on this newly discovered and under-explored realm, with emphasis placed on their applications in rechargeable batteries.