Ethanol-induced preparation of nitrogen and oxygen co-doped porous carbon nanosheets for zinc ion hybrid capacitors

Abstract

Two-dimensional (2D) porous carbon nanosheet materials possess a large specific surface area, readily accessible interface and abundant active sites, and exhibit great potential in the field of energy storage. Herein, we introduce an antisolvent precipitation strategy for creating precursors to produce 2D carbon nanosheet materials with high specific surface area. The samples without antisolvent (PC) formed a block-like porous structure, while the samples with antisolvent (NPC) formed a carbon nanosheet structure that effectively prevented structural collapse. The nitrogen and oxygen functional groups can provide some pseudocapacitance and improve wettability. Influenced by the collaborative effects, the optimized porous carbon nanosheet electrode (NPC-600) displays a specific capacitance of 420 F g⁻¹ and superior electrochemical stabilization. More importantly, the resulting Zn//ZnSO₄//NPC-600 zinc-ion hybrid capacitor achieves a high reversible specific capacity of 211.66 mAh g⁻¹ and an areal capacity of 0.43 mAh cm⁻² at 0.1 A g⁻¹, a high energy density of 169.33 Wh kg⁻¹, and outstanding long-term cycling stability (10,000 cycles, 84.21% retention). These excellent results indicate that this paper provides a new strategy for constructing high-performance porous carbon nanosheets for zinc-ion hybrid capacitors.