Sodium is currently being investigated as efficient energy storage due to its abundance in nature. Na-ion hybrid capacitors (NHCs) exhibit the characteristics of high power density as well as high specific energy. The need for development on the NHCs arises as they incorporate the advantages of capacitors and rechargeable batteries as well as cost-effectiveness. As one of the main components in NHCs, an electrolyte plays an essential role in several aspects such as safety, electrochemical characteristics and cycling performance. Conventional liquid electrolytes provide high ionic conductivity and good electrochemical properties, however, they raise safety concerns. A gel polymer electrolyte (GPE) is a promising alternative for liquid electrolyte, as it possesses great safety features and mechanical properties, but suffers from low ionic conductivity due to poor ion transport. In this study, to develop a gel polymer electrolyte with high ionic conductivity and enhanced safety, PVdF-HFP copolymer was electrospun with core-shell structured SiO₂(Na⁺) particles. Core-shell structured SiO₂(Na⁺) nanoparticles were synthesized and utilized as fillers to increase ionic conductivity by releasing Na⁺ ions into gel polymer electrolyte. Incorporation of core-shell structured nanoparticle fillers can also improve mechanical properties as well as thermal stability. Composition of the composite separators was optimized in consideration of ionic conductivity and mechanical property. Finally, the electrochemical performance of the Na-ion hybrid capacitors employing optimized gel polymer electrolyte was evaluated.

References

1. S. H. Ju, Y.-S. Lee, Y.-K. Sun, and D.-W. Kim, J. Mater. Chem. A, 1 (2013) 395-401.
2. S.-R. Park, Y.-C. Jung, W.-K. Shin, K. H. Ahn, C. H. Lee, and D.-W. Kim, J. Membr. Sci., 527 (2017) 129-136.