A series of salt‐templated carbons with gradually changed pore structure and their corresponding nitrogen‐doped analogues are synthesized and applied as model systems to thoroughly study the ion migration dynamics and energy storage mechanism in hierarchical pore structures with different surface functionalization in electric double‐layer capacitors with a model ionic liquid electrolyte (1‐ethyl‐3‐methylimidazolium tetrafluoroborate). Ion conformation and phase variation during the charging/discharging process and their contribution to the energy storage mechanism are investigated. A significant contribution of structural changes in the bulk of the ionic liquid electrolyte strengthening charge storage in the electric double‐layer beyond the usual expectations is uncovered. Furthermore, a quantitative model of the structure–dynamics relationship is proposed, in which the optimal ratio of mesopores to micropores is determined to be 3:1 in pore volume. Below this ratio, the ion dynamics can be promoted by increasing mesopore content and/or doping with nitrogen, while those parameters show only minor influence when the ratio is surpassing 3:1. Nitrogen doping in this system improves the rate capability (due to the enhanced ion transport dynamics) rather than the amount of energy stored.

Microporous nitrogen-rich carbon fibers (HAT-CNFs) are produced by electrospinning a mixture of hexaazatriphenylene-hexacarbonitrile (HAT-CN) and polyvinylpyrrolidone and subsequent thermal condensation. Bonding motives, electronic structure, content of nitrogen heteroatoms, porosity, and degree of carbon stacking can be controlled by the condensation temperature due to the use of the HAT-CN with predefined nitrogen binding motives. The HAT-CNFs show remarkable reversible capacities (395 mAh g −1 at 0.1 A g −1 ) and rate capabilities (106 mAh g −1 at 10 A g −1 ) as an anode material for sodium storage, resulting from the abundant heteroatoms, enhanced electrical conductivity, and rapid charge carrier transport in the nanoporous structure of the 1D fibers. HAT-CNFs also serve as a series of model compounds for the investigation of the contribution of sodium storage by intercalation and reversible binding on nitrogen sites at different rates. There is an increasing contribution of intercalation to the charge storage with increasing condensation temperature which becomes less active at high rates. A hybrid sodium-ion capacitor full cell combining HAT-CNF as the anode and salt-templated porous carbon as the cathode provides remarkable performance in the voltage range of 0.5-4.0 V (95 Wh kg −1 at 0.19 kW kg −1 and 18 Wh kg −1 at 13 kW kg −1 ).

Efficient and low‐cost anode materials for the sodium‐ion battery are highly desired to enable more economic energy storage. Effects on an ultrathin carbon nitride film deposited on a copper metal electrode are presented. The combination of effects show an unusually high capacity to store sodium metal. The g‐C3N4 film is as thin as 10 nm and can be fabricated by an efficient, facile, and general chemical‐vapor deposition method. A high reversible capacity of formally up to 51 Ah g−1 indicates that the Na is not only stored in the carbon nitride as such, but that carbon nitride activates also the metal for reversible Na‐deposition, while forming at the same time an solid electrolyte interface layer avoiding direct contact of the metallic phase with the liquid electrolyte.

Na‐ion hybrid capacitors are an emerging class of inexpensive and sustainable devices that combine the high energy of batteries with the high power of capacitors. However, their development is strongly impeded by a limited choice of electrode materials that display good electrochemical kinetics and long‐term cyclability. Here, a reduced graphene oxide–Zn0.25V2O5·nH2O nanobelt composite is introduced as a high power anode for Na‐ion batteries and Na‐ion hybrid capacitors. The composite material possesses fast Na‐ion intercalation kinetics, high electronic conductivity, and small volume change during Na‐ion storage, which lead to outstanding rate capability and cycling stability in half‐cell tests. Pairing it with a hard salt–templated, highly ordered mesoporous carbon as a high‐performance capacitive cathode results in a Na‐ion hybrid capacitor, which delivers a high energy density (88.7 Wh kg−1 at 223 W kg−1), a high power density (12552 W kg−1 with 13.2 Wh kg−1 retained), and an impressive cycling performance (31.7 Wh kg−1 (i.e., 87%) retained after 2000 cycles at 1 A g−1). This work explores zinc vanadate, a typical example of a layered metal vanadate, as an intercalation anode material with high pseudocapacitance for Na‐ion hybrid capacitors, which may open a promising direction for high‐rate Na‐ion storage.

A simple yet effective solvent mediated synthesis of nano-MOF with controlled polymorphism, size and morphology under ambient conditions is presented.