cm9b01334_si_001.pdf (1.41 MB)
Dense Charge Accumulation in MXene with a Hydrate-Melt Electrolyte
journal contribution
posted on 2019-06-11, 00:00 authored by Kijae Kim, Yasunobu Ando, Akira Sugahara, Seongjae Ko, Yuki Yamada, Minoru Otani, Masashi Okubo, Atsuo YamadaElectrochemical
double-layer (EDL) capacitors operating at high
charge/discharge rates are an important class of electrochemical energy
storage devices. Aqueous EDL capacitors show great potential for use
as inexpensive devices with much higher power; however, their energy
density is severely limited by the narrow electrochemical window of
water (1.23 V) and the small specific capacity of the electrodes.
Here, we develop a high-voltage aqueous supercapacitor based on a
highly concentrated Li+ aqueous electrolyte (hydrate melt)
and a two-dimensional titanium carbide MXene electrode. Experimental
and theoretical analyses reveal the existence of dense hydrated Li+ in the interlayer space of the deeply charged MXene, which
is realized by the wide electrochemical window of a hydrate-melt electrolyte.
The hydrate-melt electrolyte together with the large-capacitance MXene
Ti2CTx improves the performance
of an aqueous lithium-ion supercapacitor, offering a promising strategy
for advanced aqueous capacitors.