The known-unknowns of anomalous underscreening in concentrated electrolytes

Electrolytes are central to life and technology but lack complete understanding. Recent experiments with highly concentrated electrolytes have revealed electrostatic decay lengths orders of magnitude larger than those predicted by theory and simulation. This phenomenon, dubbed 'anomalous underscreening' and its origin is still lack a comprehensive understanding. Herein we provide a perspective over recent developments in this field and discuss phenomena that, while potentially pertinent to electrolyte underscreening, are yet to be fully explored - i.e. the 'known-unknowns' of electrostatic underscreening in concentrated electrolytes.