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

Abstract

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.