Layered double hydroxides with larger interlayer distance for enhanced pseudocapacitance

Abstract

The interlayer space of the layered materials is not always the electrochemical active area for contributing to the pseudocapacitive process. To our knowledge, few efforts have been devoted to investigating the effect of interlayer distance of layered double hydroxides (LDHs) on pseudocapacitors. Here, we obtained the CoAl–LDH with different interlayer distance via the reaction in aqueous media hydrothermally. Electrochemical characterization reveals that the CoAl(DS–(dodecyl sulfate))–LDHs with an interlayer distance of 2.58 nm can deliver higher specific capacitance of 1481.7 F g–1 than CoAl(SO42–)–LDH (0.87 nm, 1252.7 F g–1) and CoAl (CO32–)–LDH (0.76 nm, 1149.2 F g–1) at a discharge current density of 1 A g–1. An asymmetric supercapacitor with the CoAl(DS–)–LDHs║activated carbon also shows a better electrochemical performance, including a high energy density of 54.2 W h kg–1 at a power density of 0.9 kW kg–1 and a longterm stability, in comparison with CoAl(SO42–)–LDH and CoAl (CO32–)–LDH║activated carbon.