Boosting gravimetric and volumetric energy density of supercapacitors by 3D pomegranate-like porous carbon structure design

Recently, the heteroatom-enriched porous carbons have received considerable attention on the research of electrodes with high gravimetric capacitances for supercapacitors (SCs). However, their relatively low volumetric capacitances have limited their practical applications due to very low packing density and poor ion diffusion at high mass loadings. In this study, by means of a facile modified chemical activation route, a functionalized N and O co-doped three-dimensional (3D) hierarchical pomegranate-like porous carbon (PPC) was rationally synthesized. First, A core-shell structured precursor composite for PPC was constructed. The poly-pyrrole (PPy) with the desired functional group was adopted as the precursor of the pomegranate-like core, and the polyacrylamide (PAM) hydrogel as the precursor of the pomegranate-like shell (designated as PPy/PAM). Then, after calcination of the PPy/PAM hydrogel precursor composites, a novel 3D hierarchical PPC was achieved. The as-obtained PPC offers short diffusion paths of ions, increases packing density and provides abundant active sites for pseudocapacitance by increasing self-oxygen-nitrogen-doped content. The performance tests of SC with PPC manifest that at 156 W kg(-1) (109.7 W L-1), boosted energy density of 11.5 Wh kg(-1) (8.05 Wh L-1) can be achieved. The as-obtained PPC is the promising electrode material of high-performance SCs for practical applications.