Polymer Electrolyte Applications in Supercapacitor Technology

The advent of polymer electrolytes has transformed the landscape of supercapacitor technology by marrying the high power density and long cycle life of electrochemical capacitors with enhanced safety, flexibility and design versatility. In contrast to traditional liquid systems, polymer-based electrolytes offer leak-free operation, mechanical robustness and the potential for integration into flexible and wearable devices. Various classes of polymer electrolytes, including gel polymer electrolytes (GPEs), solid polymer electrolytes (SPEs) and redox-active polymer gels, have been explored to optimise ionic transport, potential window and interfacial compatibility with electrode materials. Crosslinking strategies, incorporation of ionic liquids, functional nanofillers and bio-derived polymers have been adopted to tailor conductivity and mechanical properties. These advances have yielded devices with energy densities approaching those of batteries, rapid charge–discharge capability and stability over tens of thousands of cycles. The development of proton-conducting pathways via the Grotthuss mechanism, and the use of redox-active polymers to store charge, further broadens the functional scope of polymer electrolytes in next-generation supercapacitor architectures.

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A recent study has demonstrated that brief atmospheric plasma treatment of a polyvinyl alcohol matrix markedly enhances its hydrophilicity and wettability, leading to a two-fold increase in ion transport when soaked in various aqueous electrolytes. The plasma-induced carbonyl groups on the polymer backbone reduce interfacial resistance and double the specific capacitance of the resulting solid-state supercapacitor without compromising cycle stability.

Innovative composite solid-state electrolytes have been formulated by embedding functionalised two-dimensional metallic nanoflakes into a sulfonated poly(ether ether ketone) matrix. The strong hydrogen-bond network between sulfonate groups and the polymer scaffold enables proton conduction via the Grotthuss mechanism, achieving conductivities close to 100 mS cm⁻¹ at room temperature. Supercapacitors assembled with this composite deliver specific capacitance in excess of 100 F g⁻¹, exhibit excellent rate capability and maintain performance under mechanical deformation.

Architectural tuning of PVA-based gel electrolytes through systematic variation of acid concentration and polymer molecular weight has been shown to optimise ionic conductivity and elasticity for flexible supercapacitor applications. By adjusting the PVA:H₃PO₄ ratio, ionic conductivities up to 15 mS cm⁻¹ were obtained while retaining high mechanical resilience, making these gels promising candidates for integration into wearable energy storage devices.

Polymer Electrolyte Applications in Supercapacitor Technology publication trend

The graph below shows the total number of articles in polymer electrolyte applications in supercapacitor technology across all publications each year (not limited to Nature Index journals).

Technical terms

Polymer electrolyte: A polymeric matrix that conducts ions, used to separate electrodes and enable charge transport in electrochemical devices.

Gel polymer electrolyte (GPE): A polymer electrolyte swollen with a liquid or ionic liquid, combining solid-like mechanical properties with liquid-like ionic conduction.

Ionic conductivity: A measure of how readily ions migrate through an electrolyte under an electric field, expressed in millisiemens per centimetre.

Solid-state supercapacitor: A supercapacitor in which the liquid electrolyte is replaced by a solid or quasi-solid polymer electrolyte, enhancing safety and form factor.

Specific capacitance: The capacitance per unit mass of active material, indicating how much charge is stored per gram at a given potential difference.

References

1. Performance-tuning of PVA-based gel electrolytes by acid/PVA ratio and PVA molecular weight. Discover Applied Sciences (2021).
2. Functionalized Metallic 2D Transition Metal Dichalcogenide-Based Solid-State Electrolyte for Flexible All-Solid-State Supercapacitors. ACS Nano (2022).
3. Facile Enhancement of Electrochemical Performance of Solid-State Supercapacitor via Atmospheric Plasma Treatment on PVA-Based Gel-Polymer Electrolyte. Gels (2023).