Work

Hard–Soft Acid–Base Interactions Control Ionic Conductivity in Molecular-Crystal-Based Electrolytes

Year: 2026

Type: article

Abstract: The influence of hard and soft base coordination on ionic conductivity was systematically investigated using diamine (hard base)- and dinitrile (soft base)-based ligands in molecular crystal-based solid electrolytes. For molecular crystals (Gln)2LiPF6, (Gln)2CuPF6, (DAB)2LiPF6 and (DAB)2CuPF6 (Gln = glutaronitrile, DAB = 1,4-diaminobutane) with isomorphic crystal structures in the P421c space group and with comparable metal–metal (Li+–Li+ or Cu+-Cu+) distances, the less favorable soft–hard interactions (Cu⁺–amine or Li+-nitrile) resulted in nearly two orders of magnitude improvement in ionic conductivity compared to the more favorable soft–soft and hard-hard pairing (Cu⁺–nitrile or Li+-amine). This significant enhancement is attributed to the weaker, more labile coordination between the soft nitrile donors and hard Li+ ions or hard -NH2 donors and soft Cu⁺, which facilitates faster ion migration in both cases. This result reinforces the critical role of HSAB-guided coordination chemistry in modulating ion mobility in soft-solid molecular electrolytes and provides valuable insights for the rational design of high-performance solid electrolytes in energy storage applications.

Source: ACS Materials Letters

DOI: 10.1021/acsmaterialslett.5c01234

Authors: Shujit Chandra Paul, Stephanie L. Wunder, Michael J. Zdilla

Institution: Temple University

Language: English

Topic: Advanced Battery Materials and Technologies

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: green

Funders: U.S. Department of Energy, Division of Materials Research

Awards: A NEW PARADIGM FOR WATER SPLITTING IN LAYERED MATERIALS BY MODULATION OF CATALYST OXIDATION STATE, G7513262028