Fluorine and Nitrogen Dual-Doped Porous Carbon Nanosheet-Enabled Compact Electrode Structure for High Volumetric Energy Storage

The development of electrode materials with high volumetric performance in compact energy storage is extremely appealing, yet challenging. However, the state-of-the-art compact carbon electrodes succumb to an electrode matrix with sluggish ion-transfer kinetics and unsatisfying volumetric performance. Herein, a molten-salt pyrolysis strategy is presented for preparing a fluorine and nitrogen dual-doped porous carbon nanosheet (F/N-CNS). During the molten-salt pyrolysis, nitrogen- and fluorine-rich precursors were converted into a unique two-dimensional carbon nanostructure with in-plane micropores and tailor-made fluorine/nitrogen dual doping. The as-fabricated thick and compact electrode of the F/N-CNS demonstrates a high packing density of ∼1 g cm–3, fast ion-transfer kinetics, and largely boosted pseudocapacitive characteristics. As a result, the F/N-CNS electrode in a two-electrode configuration exhibits a high volumetric capacitance of 255 F cm–3 (1 A g–1), a high volumetric energy density of 18.8 W h L–1 in an aqueous electrolyte, and an exceptional cycling stability for 20 000 cycles with almost no capacitance loss. These features demonstrate that the developed F/N-CNS is a promising candidate for high-volumetric-performance electrode materials in next-generation compact energy storage devices.