Optimizing the microstructure of carbon nano-honeycombs for high-energy sodium-ion capacitor

Carbon materials have received a great assiduity as anode for sodium ion storage, however, the sluggish kinetics of Na+ ions limit their development, suffering from low specific capacity and poor cycling stability. Herein, an eco-friendly biomass carbonization strategy is utilized to synthesize porous carbon nano-honeycombs (CNs) with hierarchical microstructures. Inspiringly, graphitic domains in the CNs can endow conductivity way for electron/charge transport, simultaneously, disordered domains with dilated lattice spacing (0.4 nm) are beneficial for Na+ storage. Both of the merits synergically make the CNs boost superior sodium storage performance with high reversible capacity (322 mAh g(-1) at 50 mA g(-1)), superb rate capability (91 mAh g(-1) at 5.0 A g(-1)), and cycling stability (99.8% retention over 10,0 0 0 cycles at 2.5 A g(-1)). Moreover, the CNs-based sodium-ion capacitor (SIC) device achieves high energy/power densities (122 Wh kg(-1) at 112.5 W kg(-1) and 17,619 W kg(-1) at 34.6 Wh kg(-1)) with an outstanding cycle stability (95.7% retention over 10,0 0 0 cycles at 1.0 A g(-1)). Our findings provide insights into optimizing the microstructure of carbon for boosting sodium storage. (c) 2021 Elsevier Ltd. All rights reserved.