Fast Ionic Diffusion-Enabled Nanoflake Electrode by Spontaneous Electrochemical Pre-Intercalation for High-Performance Supercapacitor

ABSTRACT: Layered intercalation compounds NaxMnO2 (x = 0.7 and 0.91) nanoflakes have been prepared directly through wet electrochemical process with Na+ ions intercalated into MnO2 interlayers spontaneously. The as-prepared NaxMnO2 nanoflake based supercapacitors exhibit faster ionic diffusion with enhanced redox peaks, tenfold-higher energy densities up to 110?Wh·kg?1 and higher capacitances over 1000?F·g?1 in aqueous sodium system compared with traditional MnO2 supercapacitors. Due to the free-standing electrode structure and suitable crystal structure, NaxMnO2 nanoflake electrodes also maintain outstanding electrochemical stability with capacitance retention up to 99.9% after 1000 cycles. Besides, pre-intercalation effect is further studied to explain this enhanced electrochemical performance. This study indicates that the suitable pre-intercalation is effective to improve the diffusion of electrolyte cations and other electrochemical performance for layered oxides, and suggests that the as-obtained nanoflakes are promising materials to achieve the hybridization of both high energy and power density for advanced supercapacitors.

SUBMITTER: Mai L 

PROVIDER: S-EPMC3634106 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature