Self-supporting electrodes of lithium aluminium oxide–carbon nanocomposites synthesized from dicarboxylate-intercalated layered double hydroxide for supercapacitors

Abstract

Lithium aluminium oxide–carbon composites on Al metal substrates (Al/LiAl₅O₈/C) were successfully synthesized, and their electrical properties were characterized. Sheet-type lithium aluminium layered double hydroxide (LiAl-LDH) was grown on Al metal (Al/S-LDH) and subjected to anion exchange to introduce aliphatic dicarboxylate into the interlayers through solvothermal treatment. The interlayer spacings of dicarboxylate intercalated LiAl-LDH on Al metal (Al/DC-LDH) were expanded from 9.1 Å to 21.4 Å of the (002) reflection in XRD measurement. Remarkable thickness changes of the LiAl-LDH were also observed in SEM data, indicating a strong correlation with the intercalation reaction of long-chain dicarboxylates. The pyrolysis of Al/DC-LDH above 500 °C provides nanostructured electrodes of Al/LiAl₅O₈/C nanocomposites, which contain graphitic carbon and an ordered nanostructure depending on the calcination temperatures. Al/LiAl₅O₈/C electrodes demonstrate improved electrochemical performance with enhanced durability better than Al/S-LDH electrodes, exhibiting an areal capacitance of 0.51 mF cm⁻² at a current density of 0.01 mA cm⁻².