2016/05/24 by Alexander M. Smith, Alpha A. Lee, Susan Perkin · 2 citations
Chemistry · Physics and Astronomy · #Electrostatics and Colloid Interactions #Spectroscopy and Quantum Chemical Studies #Electrochemical Analysis and Applications
paper · doi:10.1021/acs.jpclett.6b00867
openalex publication_date 2016/05/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
According to classical electrolyte theories interactions in dilute (low ion density) electrolytes decay exponentially with distance, with the Debye screening length the characteristic length scale. This decay length decreases monotonically with increasing ion concentration due to effective screening of charges over short distances. Thus, within the Debye model no long-range forces are expected in concentrated electrolytes. Here we reveal, using experimental detection of the interaction between two planar charged surfaces across a wide range of electrolytes, that beyond the dilute (Debye-Hückel) regime the screening length increases with increasing concentration. The screening lengths for all electrolytes studied-including aqueous NaCl solutions, ionic liquids diluted with propylene carbonate, and pure ionic liquids-collapse onto a single curve when scaled by the dielectric constant. This nonmonotonic variation of the screening length with concentration, and its generality across ionic liquids and aqueous salt solutions, demonstrates an important characteristic of concentrated electrolytes of substantial relevance from biology to energy storage.