Flame-Retardant High-Conductivity Urea/EMIMBF4 Eutectic Ion Gel Electrolyte for Symmetric Supercapacitors
Shiyao Tang1,2, Rui Teng1,2, Chunling Cao1,2
1State Key Laboratory of Woody Oil Resources Utilization, Northeast Forestry University, Harbin 150040, China.
ACS Applied Materials & Interfaces
|May 4, 2026
Summary
This study introduces a novel ionic-liquid-assisted eutectic electrolyte for safer, flexible supercapacitors. The new gel polymer electrolyte enhances ionic conductivity and device performance for advanced energy storage.
Area of Science:
- Materials Science
- Electrochemistry
- Polymer Science
Background:
- Gel polymer electrolytes (GPEs) are crucial for safe and flexible supercapacitors (SCs).
- Existing eutectic-based GPEs often exhibit high viscosity and limited ionic conductivity due to their electrolyte phase composition.
- These limitations hinder efficient ion transport and overall device performance in supercapacitors.
Purpose of the Study:
- To develop a quasi-solid ion-gel electrolyte with improved ionic conductivity and electrochemical stability.
- To investigate the potential of an ionic-liquid-assisted eutectic electrolyte for next-generation energy storage devices.
- To create a safe, wide-temperature, and eco-friendly electrolyte solution for supercapacitors.
Main Methods:
- Developed a quasi-solid ion-gel electrolyte by blending urea (hydrogen-bond donor) with 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4, hydrogen-bond acceptor) at a 3:7 molar ratio.
- Incorporated the eutectic mixture into a polyvinylidene fluoride-hexafluoro propylene (PVDF-HFP) matrix via solution casting and vacuum drying.
- Characterized the resulting PVDF-HFP/Urea/EMIMBF4 (PUE) gel for ionic conductivity, electrochemical stability, and thermal properties.
Main Results:
- The PUE gel achieved a high ionic conductivity of 3.52 mS cm⁻¹, a wide electrochemical stability window of 2.6 V, and stable operation up to 60 °C.
- Supercapacitors utilizing PUE gel exhibited a specific capacitance of 173.1 F g⁻¹, an energy density of 40.7 Wh kg⁻¹, and 80.1% capacitance retention after 5000 cycles.
- The PUE gel demonstrated intrinsic flame retardancy and a lowered solidification point due to the binary eutectic mixture formation.
Conclusions:
- The ionic-liquid-assisted eutectic electrolyte offers a facile and effective route to high-safety, wide-temperature quasi-solid electrolytes.
- This approach significantly enhances ionic conductivity and electrochemical performance for supercapacitors.
- The developed PUE gel represents a promising material for advanced, eco-friendly energy storage applications.
Related Concept Videos
01:18Capacitor With A Dielectric
4.3K
Parallel plate capacitors consist of two conducting plates separated by a certain distance. However, it is mechanically difficult to hold the large plates parallel to each other without actual contact. Hence, a dielectric layer is commonly placed between the plates, which provides an easy solution for holding the plates together with a small gap and increases the capacitance of the capacitor.
Dielectrics are non-conducting materials with no free or loosely bound electrons. When a dielectric is...
Dielectrics are non-conducting materials with no free or loosely bound electrons. When a dielectric is...
4.3K
01:31Dielectric Polarization in a Capacitor
5.5K
The presence of a dielectric medium in a capacitor not only changes the voltage and capacitance but also affects the electric field. In general, dielectrics can be of two types: polar and nonpolar. In a polar dielectric, the positive and negative charges in the molecules are separated by a distance and hence have a permanent dipole moment. In contrast, no such charge separation exists in a nonpolar dielectric, however the nonpolar molecules get polarized in the presence of an external electric...
5.5K
01:25MOS Capacitor
1.8K
A Metal-Oxide-Semiconductor (MOS) capacitor is a fundamental structure used extensively in semiconductor device technology, particularly in the fabrication of integrated circuits and MOSFETs (metal-oxide-semiconductor field-effect transistors). The MOS capacitor consists of three layers: a metal gate, a dielectric oxide, and a semiconductor substrate.
The metal gate is typically made from highly conductive materials such as aluminum or polysilicon. Beneath the metal gate lies a thin layer of...
The metal gate is typically made from highly conductive materials such as aluminum or polysilicon. Beneath the metal gate lies a thin layer of...
1.8K
01:24Electrochemical Systems
179
Electrochemical systems provide a fascinating insight into the dynamic interplay of charged species within various phases. One notable example is the interaction between a membrane permeable to K⁺ ions but not to Cl⁻ ions, separating an aqueous KCl solution from pure water. As K⁺ ions diffuse through the membrane, they generate net charges on each phase, leading to a potential difference between them.Similarly, when a piece of Zn is immersed in an aqueous ZnSO₄ solution,...
179
01:26Energy Stored in a Capacitor: Problem Solving
1.8K
In 1749, Benjamin Franklin coined the word battery for a series of capacitors connected to store energy. Capacitors store electric potential energy that can be released over a short time. This property means capacitors have a wide range of applications.
Capacitor-discharge ignition is a type of ignition system commonly found in small engines where the energy released from a capacitor ignites an induction coil that, in turn, fires the spark plug.
To calculate the energy stored in a capacitor of...
Capacitor-discharge ignition is a type of ignition system commonly found in small engines where the energy released from a capacitor ignites an induction coil that, in turn, fires the spark plug.
To calculate the energy stored in a capacitor of...
1.8K