Directional Li⁺ Flux Control via Liquid-Crystalline Polymer Separators for Fast-Charging Lithium Metal Batteries

Here, we report liquid-crystalline polymers (LCPs) as nanoporous films that regulate Li⁺ flux through directionally aligned ion pathways. Crosslinked LCP films form aligned nanoporous channels (∼19 nm), while tethered poly(ethylene glycol) (PEG) chains lining the pore walls provide coordination sites that facilitate Li⁺ transport.

Vertically aligned PEG-LCP films establish through-plane ion pathways, reducing effective tortuosity by ∼2.5-fold compared with planar alignment despite comparable pore architectures. This structural anisotropy leads to high ionic conductivity (1.77 mS cm^–1) and a reduced activation energy (0.12 eV) for Li⁺ migration in carbonate-based electrolytes. The resulting uniform Li⁺ flux suppresses dendritic and porous Li growth, enabling more uniform Li deposition and mitigating excessive interphase formation.