Affiliation:
1. Faculty of Chemistry and Food Chemistry Technische Universität Dresden 01062 Dresden Germany
2. Max Planck Institute for Chemical Physics of Solids Nöthnitzer Straße 40 01187 Dresden Germany
Abstract
AbstractZinc ion hybrid capacitors suffer from lack of reversibility and dendrite formation. An electrolyte, based on a solution of a zinc salt in acetonitrile and tetramethylene sulfone, allows smooth zinc deposition with high coulombic efficiency in a Zn||stainless steel cell (99.6% for 2880 cycles at 1.0 mA cm−2, 1.0 mAh cm−2). A Zn||Zn cell operates stably for at least 7940 h at 1.0 mA cm−2 with an area capacity of 10 mAh cm−2, or 648 h at 90% depth of discharge and 1 mA cm−2, 9.0 mAh cm−2. Molecular dynamics simulations reveal the reason for the excellent reversibility: The zinc cation is only weakly solvated than in pure tetramethylene sulfone with the closest atoms at 3.3 to 3.8 Å. With this electrolyte, a zinc||activated‐carbon hybrid capacitor exhibits an operating voltage of 2.0 to 2.5 V, an energy‐density of 135 Wh kg−1 and a power‐density of 613 W kg−1 at 0.5 A g−1. At the very high current‐density of 15 A g−1, 29.3 Wh kg−1 and 14 250 W kg−1 are achieved with 81.2% capacity retention over 9000 cycles.
Funder
China Scholarship Council
Subject
General Physics and Astronomy,General Engineering,Biochemistry, Genetics and Molecular Biology (miscellaneous),General Materials Science,General Chemical Engineering,Medicine (miscellaneous)