Anionic Hofmeister Effect Regulated Conductivity in Polyelectrolyte Hydrogels for High-Performance Supercapacitor.
Qingqing Guo1, Huawei Su1, Xingxiang Ji1
1School of Chemistry and Chemical Engineering, State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology Shandong Academy of Sciences, Jinan, 250353, P. R. China.
Small Methods
|July 8, 2024
Summary
The Hofmeister effect influences polyelectrolyte hydrogel conductivity, with kosmotropic ions decreasing it and chaotropic ions increasing it. This study explores its impact on electrochemical properties and energy storage devices at subzero temperatures.
Area of Science:
- Electrochemistry
- Materials Science
- Polymer Science
Background:
- The Hofmeister effect describes how ions alter the properties of aqueous solutions.
- Polyelectrolyte hydrogels are sensitive to ionic environments, affecting their stability and solubility.
- Understanding ion-specific effects is crucial for designing advanced materials.
Purpose of the Study:
- To investigate the Hofmeister effect on the electrochemical properties of polyelectrolyte hydrogels.
- To explore these effects at both room and subzero temperatures.
- To evaluate the performance of polyzwitterion hydrogels in energy storage devices.
Main Methods:
- Systematic study of polyelectrolyte hydrogels in varying ammonium salt concentrations.
- Measurement of hydrogel conductivity at different temperatures (room and subzero).
- Assembly and cycling of supercapacitors using polyzwitterion electrolytes.
Main Results:
- Polyelectrolyte hydrogels show an anti-polyelectrolyte effect at low salt concentrations and a Hofmeister effect at high concentrations.
- Kosmotropic ions reduce conductivity, while chaotropic ions increase it due to differential interactions.
- Polyzwitterion hydrogels exhibit enhanced conductivity in chaotropic ions, reaching 6.2 mS cm⁻¹ at -40 °C.
- Supercapacitors using polyzwitterion electrolytes maintained 85% capacitance retention and ~100% coulombic efficiency after 15,000 cycles at -40 °C.
Conclusions:
- The Hofmeister effect significantly impacts the conductivity of polyelectrolyte hydrogels, particularly polyzwitterions.
- Ion type and concentration are key factors in modulating hydrogel conductivity.
- This research offers a new approach to enhance the performance of energy storage devices operating at low temperatures.
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