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 °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.

► Layered double hydroxide materials were prepared in non-aqueous precipitation.
► The exposure degree of electroactive species largely determines the capacitance.
► The specific surface area also affects the capacitance.
► The charge/discharge involves the cation-redox via single electron transfer.