Construction of a Single Graphitic Nitrogen-Doped Mesoporous Carbon Microsphere with High Electronic and Ionic Transportation Capabilities in Multiscenario Capacitive Energy Storage

Nitrogen-doping has attracted tremendous attention for improving surface wettability, carrier concentration, and electrochemical reactivity of carbon materials as promising candidates for short-time and high-frequency energy storage. However, single-type N-doping still faces huge challenges, owing to an ambiguous pyrolysis mechanism and uncontrollable N-species transformation. Herein, lignin aminomethylation was proposed to introduce a secondary amine on the ortho positions of phenolic hydroxyl, which transforms into pyridinic- and graphitic-N consecutively with elevating carbonization temperature. At 900 °C, a single graphitic-N-doped mesoporous carbon microsphere with a surface area of 1349 m2 g–1, a pore size of 8.1 nm, and excellent electronic/ionic transportation capability was synthesized. Electrochemical evaluations reveal that it delivers a specific capacitance of 258 F g–1 at 0.1 A g–1, an excellent rate capability with 51.6% capacitance retention at 100 A g–1, and an energy density of 9.0 W h kg–1. When printed into a microsupercapacitor, the device exhibits a superior areal capacitance of 105 mF cm–2 at 0.04 A g–1 with a prominent rate capability of 63.9% at 1 A g–1, an energy density of 3.6 μW h cm–2 at 4.3 μW cm–2, and remarkable mechanical flexibility and stability. This work broadens the single N-doping configuration methodology of porous carbons, facilitating the development of novel capacitive energy storage materials.