Carbon-based electric double layer capacitors (EDLCs) hold tremendous potentials due to their high-power performance and excellent cycle stability. However, the practical use of EDLCs is limited by the low energy density in aqueous electrolyte and sluggish diffusion kinetics in organic or/and ionic liquids electrolyte. Herein, 3D carbon frameworks (3DCFs) constructed by interconnected nanocages (10–20 nm) with an ultrathin wall of ca. 2 nm have been fabricated, which possess high specific surface area, hierarchical porosity and good conductive network. After deoxidization, the deoxidized 3DCF (3DCF-DO) exhibits a record low IR drop of 0.064 V at 100 A g−1 and ultrafast charge/discharge rate up to 10 V s−1. The related device can be charged up to 77.4% of its maximum capacitance in 0.65 s at 100 A g−1 in 6 M KOH. It has been found that the 3DCF-DO has a great affinity to EMIMBF4, resulting in a high specific capacitance of 174 F g−1 at 1 A g−1, and a high energy density of 34 Wh kg−1 at an ultrahigh power density of 150 kW kg−1 at 4 V after a fast charge in 1.11 s. This work provides a facile fabrication of novel 3D carbon frameworks for supercapacitors with ultrafast charge/discharge rate and high energy-power density.

Despite much efforts to stabilize sodium metal anodes for promoting their commercial applications, achieving a safe cycling process without intrinsic dendrite growth remains difficult owing to the unstable reaction interface and irregular sodium metal propagation. Herein, fluorine-superdoped carbon nanotubes with a fluorine content of 14.38 at% are achieved using a new oxidation-assisted plasma strategy, and then alternately assembled with cellulose nanofibrils to form periodical conductive/dielectric composite paper with outstanding mechanical properties. The superdoping of fluorine facilitates the construction of a NaF-dominated solid electrolyte interphase layer, while the periodical conductive/dielectric network re-homogenizes electric field distribution around irregular sodium protrusions, realizing a "bottom-up" sodium orientation deposition and the "selfcorrection" functionality during sodium plating/stripping process. Density functional theory calculations reveal that the specific oxygen species (CO/CO) and fluorine species (semi-ionic CF/covalent CF 2 ) on the surface of carbon matrix, could remarkably trap active fluorine fragments and generate NaF with sodium metal, respectively, which promotes the superdoping of fluorine and forms dendrite-free sodium anodes. This delicate structure renders the sodium anodes a low nucleation overpotential of ≈7 mV, high Coulombic efficiency of 99.5% over 300 cycles at 3 mA cm −2 , stable operation for up to 2100 h under ≈16 mV, and excellent full battery performance.

Dead pine needle derived O, N codoped activated carbons were prepared by an easy one-step carbonization without adding any chemical reagents. The as-obtained PN-X samples had a high rate performance as electrodes for supercapacitors. It was due to the unique structure of cells in dead pine needles, abundant contents of metal elements (K, Na, Ca, Mg) and a large number of heteroatom contents (O, N). The role of different metal atoms and air for the formation of pores, and the mechanism of one-step carbonization were proposed. Micro/Meso/Macropores are beneficial to ion adsorption and transportation, and the doping O and N can improve physical and chemical properties of the carbon surface and increase electrochemical active sites to generate additional pseudocapacitance. All chemical and physical properties of PN-X samples were provided in detail. Especially, the PN-1000 showed a high specific capacitance of 223 F g–1 (178 F cm–3) at 0.5 A g–1 while it still had 150 F g–1 (120 F cm–3) even at 100 A g–1. The results suggested the unique PN-1000 to be a promising electrode material for supercapacitors in many practical applications.