A Preassembly and Activation Strategy to Fabricate Hierarchically Porous Carbon Nanosheets for High-Performance Supercapacitors

The rational design and synthesis of porous carbon nanomaterials with fast ion transport kinetics are the key factor in improving the rate capability of energy storage devices. This investigation introduces a methodology involving precursor preorganization and chemical activation to fabricate hierarchically porous carbon nanosheets (HPCNs), which is achieved by controlling the proportion of MgAl-layered double hydroxides (MgAl-LDH) during pretreatment of a polycyclic aromatic hydrocarbon precursor. The obtained highly interconnected nanosheet frameworks within HPCNs not only facilitate efficient charge carrier mobility and high-speed electron transfer to ensure excellent rate performance but also fully expose the nanosheets with an appropriate microporous–mesoporous distribution to maximize interfacial charge accumulation. Consequently, the optimized HPCNs-3 electrode demonstrates excellent electrochemical characteristics with a high specific capacitance of 339 F g–1 at 0.5 A g–1, remarkable rate performance with 72% capacitance retention at 100 A g–1, and superior cycling stability with 88% initial capacitance retained after 30,000 cycles at 10 A g–1, exhibiting the potential practical application of supercapacitors. This study may provide an instructive guide for developing advanced carbonaceous electrodes in electrochemical capacitor applications.