Lithium-ion conducting self-assembled organic nanowires: optimizing mechanical performance and ionic conductivity through programmable supramolecular interactions

TL;DR

Researchers developed self-assembled nanowires that improve both the mechanical strength and ionic conductivity of solid-state lithium-ion conductors.

Contribution

A new supramolecular design that optimizes noncovalent interactions to enhance both mechanical and ionic properties of nanowires.

Findings

Precise hydrogen bonding significantly improves mechanical properties like Young's modulus and toughness.

The nanowires achieve high ionic conductivity and a high Li-ion transference number.

Molecular dynamics show Li-ions prefer hopping through axial pathways in the nanowires.

Abstract

The emergence of wearable devices has led to a greater need for battery materials that are safe, resilient, and exhibit high levels of ionic conductivity. Here, we present a supramolecular design as a useful tactic through fine tuning of the noncovalent interactions to overcome the standard trade-off in solid state Li-ion conductors between ionic conductivity and mechanical resilience. We report solution processable self-assembled organic nanowires (SONs) with varying supramolecular interactions through structural mutation to boost Li-ion conductivity and mechanical integrity. The findings indicate that precise H-bonding plays a crucial role in achieving a maximum Young's modulus (1050.5 ± 38 MPa) and toughness (15 666 ± 423 kJ m−3), surpassing the impact of the number of H-bonding sites. The highly structured H-bonded morphology facilitated the creation of binding pockets, enhancing lithiation, in achieving the highest ionic conductivity (3.12 × 10−4 S cm−1) with a Li-ion transference number of 0.8 at 298 K. The molecular dynamics simulation demonstrates that, among the various interaction sites, the hopping of Li-ions through the axial pathway is favoured over the planar pathway. This study represents a pioneering example illustrating the methodology behind the impact of noncovalent interactions within nanoscale assemblies on the ion conductivity and mechanical characteristics of supramolecular Li-ion conductors.

We introduce self-assembled organic nanowires featuring programmable supramolecular interactions as an effective strategy to address the traditional trade-off between mechanical strength and ionic conductivity in solid-state Li-ion conductors.

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