Boosting the Sensitivity and Hysteresis of a Gel Polymer Electrolyte by Embedding SiO2 Nanoparticles and PVP for Humidity Applications

Michelle Cedeño Mata; Albert Orpella; Manuel Dominguez-Pumar; Sandra Bermejo

doi:10.3390/gels10010050

Boosting the Sensitivity and Hysteresis of a Gel Polymer Electrolyte by Embedding SiO₂ Nanoparticles and PVP for Humidity Applications

Gels. 2024 Jan 10;10(1):50. doi: 10.3390/gels10010050.

Authors

Michelle Cedeño Mata¹, Albert Orpella¹, Manuel Dominguez-Pumar¹, Sandra Bermejo¹

Affiliation

¹ MNT Group, Electronic Engineering Department, Polytechnic University of Catalonia (UPC), C/Jordi Girona 1-3, 08034 Barcelona, Spain.

Abstract

Enhancing sensitivity and hysteresis in capacitance humidity sensors is vital for precise, reliable, and consistent humidity control. This study explores this concern by incorporating polyvinylpyrrolidone (PVP) and SiO₂ nanoparticles into a polyvinyl alcohol (PVA)-based ionic liquid gel polymer electrolyte (ILGPE), studying two capacitor types: ILGPE and SiO₂ composite ILGPE (CILGPE) capacitors. These novel electrolytes use ammonium acetate as a plasticiser, 1-butyl-3-methylimidazolium bromide as an ionic liquid, SiO₂ nanoparticles as a composite, and PVA and PVP as host polymers. Capacitors were characterised and modelled using impedance spectroscopy (IS), providing an electrophysical insight into their working principle. Sensitivity and hysteresis were evaluated within a 20-90% relative humidity (RH) range at 25 °C. The SiO₂ CILGPE capacitor with PVP presented superior sensitivity and hysteresis, revealing the beneficial combination of SiO₂ nanoparticles and PVP. These benefits are due to the creation of pathways that facilitate water molecule diffusion and crystallinity reduction in PVA-ILGPE. In particular, at 10 kHz, it demonstrates a calibrated capacitance sensitivity of 2660 pF/%RH and a hysteresis of 3.28 %RH. This optimised capacitor outperforms some previous humidity capacitive sensors in sensitivity while exhibiting low hysteresis.

Keywords: colloidal nanoparticles; gel polymer electrolytes; impedance spectroscopy; ionic liquid.

Grants and funding

This work has been supported by the Secretariat for Universities and Research of the Ministry of Research and Universities, the European Social Fund, and the projects TED2021-131552B-C22 and PID2021-126719OB-C42.