A Dipole‐Engineered Electrolyte Paradigm to Overcome Desolvation Barriers for Exceptional Ultralow‐Temperature Energy Storage
Yiheng Qi, Chuang Bao, X. D. Li, Jianhua Yan, Kefa Cen, Zheng Bo, Huachao Yang
Abstract
Electrochemical energy storage (EES) devices often exhibit poor low-temperature performance due to high interfacial desolvation energy barriers. While conventional strategies targeting ion-dipole interactions have improved desolvation kinetics, they suffer from a fundamental trade-off with bulk-phase ion diffusion. Here, a dipole-engineered electrolyte paradigm is proposed to overcome desolvation barriers for enhanced ultralow-temperature energy storage. Following this new paradigm, a weakly-dipolar-interacting electrolyte (WDIE) is developed by regulating dipole-dipole interactions within ionic solvates between primary and co-solvents. Through comprehensive experimental characterization and theoretical analyses, the interplay between dipole-dipole interactions and solvation dynamics across both interfacial and bulk phases is elucidated. Specifically, WDIE transforms the ionic solvate from conventional double-layer to distinctive mono-layer with attenuated solvent coordination number, effectively lowering solvent residence time and desolvation energy barriers. Simultaneously, it promotes solvent cluster dissociation, disrupting cross-linked electrolyte networks and enhancing bulk ion diffusion. As a proof of concept, WDIE-based supercapacitors exhibit optimized ultralow temperature performance, which retain 97.15% capacity from 20 to -70 °C, surpassing moderately- and strongly-dipolar-interacting electrolytes and ranking among the best reported. Moreover, theoretical calculations further demonstrate the broad applicability of this strategy when ionic radius exceeds 3.84 Å. This work demonstrates a scalable dipole-engineered electrolyte paradigm to overcome low-temperature EES limitations.