Porous structure engineering of N-doped carbons for enhanced mass transfer towards High-Performance supercapacitors and Li-Ion batteries

Tailoring the porous structure of carbon materials is one essential approach to improve the energy storage performance of carbon-based electrode materials. Herein, hierarchical porous carbons (HPCs) with different meso-structure are synthesized via a one-pot pyrolysis process with SiO2 and ZnCl2 as template and activator, respectively. The energy storage capacities of the obtained HPC samples are investigated as bi-functional electrode both for supercapacitor and LIBs. The results show that different meso-structure of HPCs can effectively affect the energy storage performance. In the range of 15 ∼ 50 nm, smaller size of mesopore can result better electrochemical performance of HPCs. And the optimized HPC sample (HPC-15) manifests high specific capacitance of 432F g-1 and good cyclic stability in the supercapacitor application. When used as anode of LIBs, the HPC-15 presents a high capacity of 820 mAh g-1. In addition, COMSOL simulation is employed to study the effect of pore structure on mass transfer during electrochemical process. The HPC-15 is calculated to have the highest total porosity (εp) and effective diffusivity of K+ (De = 6.776 × 10-10 m2 s-1), thus leading to its best electrochemical performance.