Titanium and nitrogen co-doped porous carbon for high-performance supercapacitors

Abstract

A novel titanium, nitrogen co-doped carbon material was designed via a one-step solvothermal reaction at a moderate temperature. Characterization by scanning electron microscopy and transmission electron microscopy illustrates that carbon materials without titanium doping possess a morphology of porous flakes, whereas the inclusion of titanium results in the deposition/intercalation of island-shaped TiO₂ nanoparticles on these carbon flakes. Both the volumetric energy density and the cycling stability are significantly improved by titanium doping. Electrochemical measurements show that the introduction of titanium leads to a high volumetric capacitance of 285.5 F cm⁻³ at 0.5 A g⁻¹ current density. Electrodes prepared with the new materials also exhibit excellent cycling stability, where there is no capacitance loss after 40 000 cycles in the 6 M KOH electrolyte at a high charge/discharge current of 30 A g⁻¹. The volumetric energy density of the as-obtained symmetrical supercapacitor reaches 11.99 W h L⁻¹, which is competitive to that of lithium thin-film batteries (1–10 W h L⁻¹).