A Recyclable and Sustainable Hydroxypropyl Methylcellulose Electrolyte for Electrochromic Devices

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Energy

Background:

• Gel electrolytes are crucial for electrochromic devices (ECDs) but often involve complex, hazardous preparation methods.
• Current gel electrolytes limit the widespread adoption of ECDs due to environmental and safety concerns.

Purpose of the Study:

• To develop a straightforward and environmentally friendly method for fabricating large-area gel electrolytes for ECDs.
• To enhance the performance of gel electrolytes using deep eutectic solvents (DES) and SiO2 nanoparticles.
• To evaluate the properties and performance of a novel HPMC/DES-SiO2 gel electrolyte in an ECD.

Main Methods:

• Solution casting technique in an aqueous system using hydroxypropyl methylcellulose (HPMC).
• Incorporation of deep eutectic solvents (DES) and SiO2 nanoparticles to improve ionic conductivity.
• Fabrication and characterization of W18O49/NiO electrochromic devices (ECDs) using the developed gel electrolyte.

Main Results:

• The HPMC/DES-SiO2 gel electrolyte demonstrated high transparency (>92%), ionic conductivity (7.55 × 10^-4 S/cm), a wide electrochemical window (±3 V), and excellent thermal stability.
• The assembled ECD exhibited robust cycling stability (94.8% retention after 1000 cycles) and broad operational temperature range (-50°C to 200°C).
• Significant recyclability of HPMC and key components (up to 82.7% of LiTFSI and NMA) was achieved.

Conclusions:

• The developed HPMC/DES-SiO2 gel electrolyte offers a sustainable and high-performance alternative for electrochromic devices.
• This method addresses the limitations of conventional gel electrolytes, paving the way for greener and more efficient ECDs.
• The material's recyclability highlights its potential for circular economy principles in electronic device manufacturing.