Nitrogen-Enriched Nonporous Carbon Electrodes with Extraordinary Supercapacitance

Graphical Abstract

Nitrogen-enriched nonporous carbon materials with excellent capacitive performance are prepared from melamine–mica (MM) composites. In samples that are oxidized prior to ammonia treatment (MMOA), the carbon surface incorporates more N functional groups, resulting in high levels of pseudocapacitance. The low surface area and high capacitance of these materials make them suitable electrode materials for compact energy storage devices with stable cycling performance for up to 10 000 cycles.

Abstract

Nitrogen-enriched nonporous carbon materials derived from melamine–mica composites are subjected to ammonia treatment to further increase the nitrogen content. For samples preoxidized prior to the ammonia treatment, the nitrogen content is doubled and is mainly incorporated in pyrrol-like groups. The materials are tested as electrodes for supercapacitors, and in acidic or basic electrolytes, the gravimetric capacitance of treated samples is three times higher than that of untreated samples. This represents a tenfold increase of the capacitance per surface area (3300 µF cm⁻²) in basic electrolyte. Due to the small volume of the carbon materials, high volumetric capacitances are achieved in various electrolytic systems: 280 F cm⁻³ in KOH, 152 F cm⁻³ in H₂SO₄, and 92 F cm⁻³ in tetraethylammonium tetrafluoroborate/propylene carbonate.