Year: 2026
Type: article
Abstract: Polymer separators have been established as critical components for supercapacitors, as their molecular constitution, pore morphology, wettability, thickness, and interfacial properties directly govern ion transport, internal resistance, safety, and electrochemical stability. In this review article, the evolution of polymeric separators over the past three decades is thoroughly reviewed, and the existing materials are classified into three main categories: synthetic polymers, natural and bio-polymer separators, and advanced polymer composite separators. Special emphasis is devoted to the structure-property-performance relationship of electrospun nanofibers, hydrogels, regenerated cellulose matrices, inorganic nanoparticles, 2D fillers, ionic liquids, and piezoelectric phases. The reviewed studies report substantial variations in operating voltage, specific capacitance, energy density, power density, and cycling stability across different separator systems. These performance metrics depend on the combined effects of separator properties, electrode configuration, electrolyte composition, and testing conditions, highlighting the importance of consistent reporting and careful cross-study comparisons. Special attention is devoted to the correlation between polymer chemistry, separator thickness, porosity, pore morphology, electrolyte wettability, mechanical and thermal stability, fabrication route, and electrochemical performance of the device. The proposed multi-criteria assessment methodology assesses separator materials based on the combination of weighted criteria such as ionic conductivity, cycles, energy and power densities, mechanical stability, thermal stability, and electrolyte affinity, while the Ashby-type analysis compares ion-transport capacity with structural stability. It turns out that synthetic polymers are generally better in terms of processability, mechanical stability, and thermal stability, while natural polymers excel in terms of wettability, sustainability, biodegradability, and ion transport. More advanced composite separator materials are capable of combining these qualities and adding more functionalities such as self-charging, piezoelectric response, thermal protection, and self-discharge prevention. According to the review, inconsistent test conditions, lack of manufacturing scalability, incompatibility at the interface, and lack of standardized testing procedures are significant challenges for accurate comparison of materials. Both analyses conclude that advanced composite separators are the most versatile material family, but it is also revealed that inconsistent test conditions are one of the major problems for reliable cross-study comparison and material choice.
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,050
OpenAlex ID: W7225856502