One-pot synthesis of long-range aligned nanochannels for Li-ion transfer pathways

Abstract

Limited ionic conductivity (σ) of solid polymer electrolytes (SPEs) is a bottleneck for their practical application. Constructing ordered ionic transfer highways is a prospective direction to promote σ. Here, we propose a straightforward one-pot synthesis strategy for the obtention of long-range aligned nanochannels, which is based on the evaporation of the solvent to induce the self-assembly of Pluronic® F127-resol micelles. To obtain SPEs, dicyandiamide (DCD) and LiClO₄ are uniformly dispersed in the F127-resol nanochannels. Compared to the random counterpart, the accordingly synthesized ordered SPE significantly improves room-temperature σ by 2 orders of magnitude reaching 1.65 × 10⁻⁴ S cm⁻¹ at 20 °C. The FTIR spectra further demonstrate that the best performing sample possesses more Li⁺ ions coordinated to cyano groups from DCD and less coordinated to ether moieties from F127-resol, further decreasing the activation energy for Li⁺ mobility since cyano groups have lower binding energy to Li⁺ than ether ones. Both aligned nanostructures and beneficial coordinating groups synergistically accelerate the ionic transport, contributing to the formation of efficient Li-ion transfer pathways.