Extended Electrochemical Window Via Interfacial Microdomain Regulation by a Bicontinuous Microemulsion‐Based Heterogel Electrolyte
Yuzhen Qian, Long Su, Hongyue Jing, Chunxiao Chai, Fengjin Xie, Xiaoyong Qiu, Jingcheng Hao
Abstract
ABSTRACT Regulating the freedom and distribution of H 2 O molecules has become the decisive factor in enlarging the electrochemical stability window (ESW) of aqueous electrolytes. Compared with the water in a bulk electrolyte, H 2 O molecules at the electrode–electrolyte interface tend to directly split under bias potential. Therefore, the composition and properties of the interfacial microenvironment are the crux for optimizing ESW. Herein, we developed a heterogel electrolyte with wide ESW (4.88 V) and satisfactory ionic conductivity (4.4 mS/cm) inspired by the bicontinuous architecture and surfactant self‐assembly behavior in the ionic liquid microemulsion‐based template. This electrolyte was capable of expanding the ESW through the dynamic oil/water/electrode interface ternary structure, which enriched the oil phase and assembled the hydrophobic surfactant tails at the interface to prevent H 2 O molecules from approaching the electrode surface. Moreover, the surfactant Tween 20 and polymer network effectively suppressed the activity of H 2 O molecules through H‐bond interactions, which was beneficial in expanding the operating voltage range and improving the temperature tolerance. The prepared gel electrolyte demonstrated unparalleled adaptability in various aqueous lithium‐based energy storage devices. Notably, the lithium‐ion capacitor showed an extended operating voltage of 2.2 V and could provide a high power density of 1350.36 W/kg at an energy density of 6 Wh/kg. It maintained normal power output even in the challenging harsh environment, which enabled 11,000 uninterrupted charge–discharge cycles at 0°C. This work focuses on the regulation of the interfacial microdomain and the restriction of the degree of freedom of H 2 O molecules to boost the ESW of aqueous electrolytes, providing a promising strategy for the advancement of energy storage technologies.