Well-Aligned Liquid Crystal Interface and Expanded Solvation Sheath Accelerate Zn²⁺ Desolvation Kinetics for Stable Zinc Batteries

Abstract

The straightforward processing and assembly of zinc batteries enable large-scale production and cost-effective energy storage solutions. However, nonuniform Zn plating and parasitic reactions impede practical deployment, which can be addressed <i>through</i> advanced interfacial modifications and enhanced Zn²⁺ transport kinetics. Herein, we developed a trace additive based on a tailored liquid crystal molecule (4-pentyl-4'-cyanobiphenyl, 5CB), which preferentially adsorbs onto the zinc surface to form a dynamic ordered interfacial layer and modulate the Zn²⁺ solvation shell due to its self-assembling and anisotropic properties. The interfacial layer inhibits solvent decomposition and side reactions, while the expanded solvation shell weakens Zn²⁺ interactions with both solvents and anion, lowering the desolvation barrier and enabling fast, uniform Zn²⁺ transport. Consequently, the Zn²⁺ transfer number increases from 0.29 to 0.71, and epitaxial deposition of Zn²⁺ along the (002) crystal plane is promoted, ensuring uniform zinc deposition. Benefiting from the liquid crystal interfacial layer, the Zn∥Zn symmetric cell demonstrates exceptional cycling stability for up to 2000 h, surpassing that without 5CB (only 400 h) while asymmetric Zn∥Ti cells with 5CB maintain >99.1% Coulombic efficiency after 1100 cycles, compared to rapid degradation without 5CB. The Zn∥PANI full cells deliver 157.6 mAh g^-1 at 0.1 A g^-1, retaining 130.1 mAh g^-1 at a high current density of 5 A g^-1, and achieves 86% capacity retention over 500 cycles. These findings highlight the effectiveness of liquid crystal interfacial engineering in improving Zn-ion transport kinetics and stabilizing Zn anodes, paving the way for high-performance, long-lifetime zinc batteries.