title: "Rocking-Chair"-Type Metal Hybrid Supercapacitors.
abstract: Hybrid supercapacitors that follow a "rocking-chair"-type mechanism were developed by coupling divalent metal and activated carbon electrodes in nonaqueous electrolytes. Conventional supercapacitors require a large amount of electrolyte to provide a sufficient quantity of ions to the electrodes, due to their Daniell-type mechanism that depletes the ions from the electrolyte while charging. The alternative "rocking-chair"-type mechanism effectively enhances the energy density of supercapacitors by minimizing the necessary amount of electrolyte, because the ion is replenished from the metal anode while it is adsorbed to the cathode. Newly developed nonaqueous electrolytes for Mg and Zn electrochemistry, based on bis(trifluoromethylsulfonyl)imide (TFSI) salts, made the metal hybrid supercapacitors possible by enabling reversible deposition on the metal anodes and reversible adsorption on an activated carbon cathode. Factoring in gains through the cell design, the energy density of the metal hybrid supercapacitors is projected to be a factor of 7 higher than conventional devices thanks to both the "rocking-chair"-type mechanism that minimizes total electrolyte volume and the use of metal anodes, which have substantial merits in capacity and voltage. Self-discharge was also substantially alleviated compared to conventional supercapacitors. This concept offers a route to build supercapacitors that meet dual criteria of power and energy densities with a simple cell design.
authors: Department of Chemistry, University of Illinois at Chicago , Chicago, Illinois 60607, United States.|Joint Center for Energy Storage Research, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors: Hyun Deog
authors: HD
authors: Yoo
authors: Joint Center for Energy Storage Research, Argonne National Laboratory , Argonne, Illinois 60439, United States.|Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors: Sang-Don
authors: SD
authors: Han
authors: Department of Chemistry, University of Illinois at Chicago , Chicago, Illinois 60607, United States.|Joint Center for Energy Storage Research, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors: Ryan D
authors: RD
authors: Bayliss
authors: Joint Center for Energy Storage Research, Argonne National Laboratory , Argonne, Illinois 60439, United States.|Department of Chemistry, University of Illinois at Urbana-Champaign , 600 S. Mathews Avenue, Urbana, Illinois 61801, United States.
authors: Andrew A
authors: AA
authors: Gewirth
authors: Joint Center for Energy Storage Research, Argonne National Laboratory , Argonne, Illinois 60439, United States.|Materials Science Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.|University of Ljubljana , Faculty of Chemistry and Chemical Technology, Vecna pot 113, 1000 Ljubljana, Slovenia.
authors: Bostjan
authors: B
authors: Genorio
authors: Joint Center for Energy Storage Research, Argonne National Laboratory , Argonne, Illinois 60439, United States.|Environmental Energy Technology Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors: Nav Nidhi
authors: NN
authors: Rajput
authors: Joint Center for Energy Storage Research, Argonne National Laboratory , Argonne, Illinois 60439, United States.|Environmental Energy Technology Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|Department of Materials Science and Engineering, University of California , Berkeley, California 94720-1760, United States.
authors: Kristin A
authors: KA
authors: Persson
authors: Joint Center for Energy Storage Research, Argonne National Laboratory , Argonne, Illinois 60439, United States.|Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors: Anthony K
authors: AK
authors: Burrell
authors: Department of Chemistry, University of Illinois at Chicago , Chicago, Illinois 60607, United States.|Joint Center for Energy Storage Research, Argonne National Laboratory , Argonne, Illinois 60439, United States.
authors: Jordi
authors: J
authors: Cabana
keywords: energy density; metal anodes; self-discharge; supercapacitors; volume of electrolyte; “rocking chair”-type mechanism