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- Title
Surface terminals reconstruction: The way to widen the output voltage of MXene-based aqueous symmetrical micro-supercapacitors.
- Authors
Wu, Yudong; Fu, Jimin; He, Ningning; Liu, Jun; Hua, Tao; Qin, Chengbing; Hu, Haibo
- Abstract
The low anodic oxidation potential severely suppresses the output voltage (≤ 0.6 V) of MXene-based symmetrical aqueous micro-supercapacitors (MSA-MSCs) employing acidic electrolytes. Herein, a surface terminals reconstruction mechanism on cathode of MSA-MSCs adopting aqueous neutral electrolyte (1 M Na2SO4) is first revealed by systematical electrochemical experiments and in/ex-situ spectral analysis, which indicates that: the -O terminals on Ti3C2Tx flakes of cathode can combine with intercalated Na+ cations during charging process to reconstruct into -ONa units to (i) inhibit the splitting reaction of adjacent water molecules, decreasing cathodic hydrogen evolution potential, and more significantly, (ii) lower the potential of zero voltage (P0V) between the symmetrical electrodes to avoid anode oxidation, enabling full use of the unexploited potential range of cathode. Thus, the output voltage of the MSA-MSCs tremendously expanded from 0.6 V in acidic polyacrylamide (PAM)/1 M H2SO4 hydrogel electrolyte to 1.5 V in neutral polyacrylamide/1 M Na2SO4 hydrogel electrolyte, boosting the corresponding areal energy density from 9.9 to 34.6 µW·h·cm−2. The demonstrated deep insight on the surface terminals reconstruction mechanism for synchronously modulating the P0V between symmetrical electrodes and hydrogen evolution potential on cathode provides critical guidance for widening the cell voltage of MSA-MSCs with safer and more inexpensive neutral electrolytes.
- Subjects
SURFACE reconstruction; ENERGY density; VOLTAGE; STANDARD hydrogen electrode; ELECTROCHEMICAL experiments; SODIUM channels; AQUEOUS electrolytes; POLYACRYLAMIDE; PHOTOCATHODES
- Publication
Nano Research, 2023, Vol 16, Issue 5, p6780
- ISSN
1998-0124
- Publication type
Article
- DOI
10.1007/s12274-022-5262-x