Hierarchical porous carbon obtained by Mg–Al double hydroxide templates with high volumetric capacitance and rate performance

Abstract

The hierarchical porous carbons (HPCs) are considered as promising supercapacitor electrode materials. However, most of them suffer from low volumetric capacitance values and rate performance. In the work, a kind of MgAl-layered double hydroxides (LDHs) templates is synthesized by co-precipitation and recrystallization strategy. It is found that the recrystallization can effectively decrease the overall dimensions and adjust the pore size of LDHs. By the use of LDHs as templates and polyethylene glycol-200 (PEG-200) as carbon precursors, a series of HPCs are synthesized. The HPCs basically copy the morphology of LDHs, and their electrochemical properties are influenced significantly by the recrystallization time of LDHs. With the 24h recrystallization of LDHs, the obtained HPC shows the highest compact density of 0.78 g cm −3 . It delivers the volumetric capacitance of 183 F cm −3 and retains outstanding rate stability of 81.54% of initial capacitance when current density is increased to 50 times. Moreover, the volumetric energy density of 15.11 Wh L −1 (19.38 Wh kg −1 ) is achieved at the power density of 373.2 W L −1 . This work provides a simple route to fabricate HPCs with high volumetric capacitance and rate performance. • Recrystallized MgAl-layered double hydroxides (LDHs) are used as templates. • The recrystallization impoves the morphology and structure of LDHs. • The hierarchical porous carbons (HPCs) are achieved using LDH as templates. • The HPCs show high volumetric capacitance and rate performance.