Morphology control and supercapacitor performance of resorcinol–formaldehyde-based carbon particles upon Ni loading in an inverse emulsion system

Abstract

Ni-doped carbon particles with controlled morphology were synthesized by the carbonization of [Ni(H₂O)₆](NO₃)₂-doped resorcinol–formaldehyde aerogel particles extracted from an inverse emulsion polymerization system. Ni was introduced into the reaction system by directly adding nickel salt into the resorcinol–formaldehyde solution. The morphology and structure of the Ni-doped carbon particles were investigated by TEM, SEM, XRD, FI-IR and BET measurements. The size distribution of the Ni-doped carbon particles can be controlled by the stirring speed of the inverse emulsion polymerization system, and the morphology of the prepared carbon particles can be adjusted to be spheres, semispheres, irregular semispheres and capsules by changing the nickel salt concentration. The Ni particles were distributed uniformly in the carbon network. This study illustrates that [Ni(H₂O)₆](NO₃)₂ changed the resorcinol–formaldehyde inverse emulsion polymerization mechanism. Upon ambient drying, the Ni-doped carbon particles exhibit mainly microporosity and the BET surface area of the samples can reach 487 m² g⁻¹ with a corresponding pore volume of 0.229 cm³ g⁻¹. The electrochemical performance was tested using these carbon particles as the electrode material for supercapacitors. The prepared carbon capsules displayed a stabilized capacity of 154 F g⁻¹ after 1200 cycles with an increasing trend, which indicates that the materials have good electrochemical performance.