High capacitance electrode materials based on layered double hydroxides prepared by non-aqueous precipitation

Supercapacitors that have been actively sought for electricity storage and many metal oxides/hydroxides, including transition metal-containing layered double hydroxides (LDHs), have been widely investigated. In this research, Co- or Mn-containing LDHs were prepared through precipitation in methanol, followed by the hydrothermal treatment and dispersion in water. As-prepared LDHs showed a relatively high capacitance (13-140 F g(-1)) at the scanning rate of 1 mV s(-1) and a current load of 20 mA g(-1) using 6 M KOH as an electrolyte. Calcination of LDHs at 400 degrees C (e.g. LDOs) normally enhances the exposure of electrochemical active species, but can lead to an increase or a decrease of the specific surface area, with a specific capacitance of 50-210 F g(-1). We have also noted that the capacitance of both LDOs and LDHs remains stable after 100-500 cycles. The possible mechanism of electron transfer was considered based on the cyclic voltammograms and physicochemical features of LDHs and LDOs. (C) 2012 Elsevier B.V. All rights reserved.