Negative dielectric constant of water confined in nanosheets

Akira Sugahara, Yasunobu Ando, Satoshi Kajiyama, Koji Yazawa, Kazuma Gotoh, Minoru Otani, Masashi Okubo, Atsuo Yamada*


研究成果: Article査読

98 被引用数 (Scopus)


Electric double-layer capacitors are efficient energy storage devices that have the potential to account for uneven power demand in sustainable energy systems. Earlier attempts to improve an unsatisfactory capacitance of electric double-layer capacitors have focused on meso- or nanostructuring to increase the accessible surface area and minimize the distance between the adsorbed ions and the electrode. However, the dielectric constant of the electrolyte solvent embedded between adsorbed ions and the electrode surface, which also governs the capacitance, has not been previously exploited to manipulate the capacitance. Here we show that the capacitance of electric double-layer capacitor electrodes can be enlarged when the water molecules are strongly confined into the two-dimensional slits of titanium carbide MXene nanosheets. Using electrochemical methods and theoretical modeling, we find that dipolar polarization of strongly confined water resonantly overscreens an external electric field and enhances capacitance with a characteristically negative dielectric constant of a water molecule.

ジャーナルNature communications
出版ステータスPublished - 2019 12月 1

ASJC Scopus subject areas

  • 化学 (全般)
  • 生化学、遺伝学、分子生物学(全般)
  • 物理学および天文学(全般)


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