# 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.

## Key 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.