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[Display omitted] • Dopamine-functionalized carbon interface enhances interfacial activity. • Boron and oxygen are codoped to optimize the capacitive behavior of carbon materials. • The inside-out pore creating method of body phase improves the activation efficiency. As a typical double-layer capacitive electrode material, carbon nanomaterials show desirable application potential in the field of capacitive deionization (CDI) and supercapacitors (SCs). In this work, interfacial functional groups and B\O co-doping defects are simultaneously introduced into multi-chamber carbon with confinement effect, and their practical applications in CDI and flexible capacitors are also studied. Specifically, the oxygen-rich carbon source and boron source, dissolved and mixed completely via co-crystallization method, released amount of gas during the pyrolysis process to produce multi-chamber honeycomb-like carbon with ultrathin walls, which were further introduced into abundant interfacial functional groups by dopamine to optimize the carbon surface. At the same time, part of boron atoms entered the carbon lattice to form boron doping at high temperature, followed by the integration with the oxygen heteroatoms in carbon source to generate abundant boron and oxygen codoping defects. The as-prepared diatomic defects by the synergistic effect promote the wettability and pseudocapacitance of the material. In addition, the derived carbon materials are endowed with good hydrophilic ability and surface activity under the modification of dopamine functional groups. The ideal hydrophilic ability ensures that the porous structure of material can be infiltrated by electrolyte to provide large effective specific surface area, which enhances the electrical double-layered capacity. The interfacial functional groups also offer additional pseudocapacitance, so as to improve the ion adsorption capacity of PDA-BOC. [ABSTRACT FROM AUTHOR]

[Display omitted] • E-waste can be strategically converted into energy-storing electrodes. • Interesting core–shell morphology is formed by a facile two-step synthesis process. • The optimized NiSe-120/Cu 4 O x -3 electrode shows an areal capacity of 138.27 µAh cm−2. • Excellent stability is achieved even after 50,000 charge–discharge cycles. • The C-type HSC device exhibits a good areal capacitance of 233.1 mF cm−2. Recently, for energy storage materials, various surfactant-less synthesis methods have been attaining extensive attention from researchers. Herein, we utilized the wasted desoldering copper wicks (E-waste) as the base substrate to synthesize hierarchical core–shell maze-corn-like nickel selenide/copper oxide (NiSe/Cu 4 O x) architectures by a facile two-step synthesis process. Initially, the Cu 4 O x nanorods (NRs) were grown directly over the surface of the flat braided E-waste copper wicks by thermal oxidation, followed by a facile electrodeposition method to coat the pre-existing Cu 4 O x NRs with NiSe nanoparticles. The optimized NiSe-120/Cu 4 O x -3 electrode exhibited superior electrochemical characteristics (138.27 µAh cm−2 at 4 mA cm−2) compared to the other electrodes, owing to the contribution of core and shell materials, and sustained an ultra-long cycling test of 50,000 charge/discharge cycles with an excellent capacity retention of 98.7%. Inspired by commercially available AA battery, the as-synthesized working electrode was coupled with activated carbon-coated nickel foam to fabricate a cylindrical-type (C-type) hybrid supercapacitor (HSC) device, with an areal capacitance of 233.1 mF cm−2 accompanied by an extraordinary cycling efficiency of 99.1%. Furthermore, the C-type HSC device exhibited maximum energy and power densities of 70.9 µWh cm−2 and 14,000 µW cm−2, respectively and it was tested by powering portable electronics for real-time application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dual pseudocapacitive electrode/redox electrolyte systems. • Enlarged potential window and cell voltage. • High energy- and power-densities of supercabattery devices. Supercabatteries refer to those supercapacitors with supercapacitor-like high power density and battery-like high energy density. In this work, dual pseudocapacitive electrode/redox electrolyte systems, namely MnO 2 @carbon cloth/Na 2 SO 4 + KI and Fe 2 O 3 @carbon cloth/Na 2 SO 4 + ethyl viologen dibromide, have been designed and developed. As the cathodic and anodic systems, they are employed for the construction of asymmetric supercabatteries. The different working potential windows of two systems lead to a cell voltage of as high as 2.0 V. The synergistic effect of two redox species on the electrode and in the electrolyte results in an enlarged capacitance of 509.1 mF cm−2 at a current density of 10 mA cm−2. The supercabattery device delivers a maximal energy of 6.6 Wh L−1 and a maximal power density of 357.6 W L−1. They are higher than those of most of reported manganese oxide//iron oxide based asymmetric supercapacitor devices, and meanwhile comparable to those of some rechargeable batteries. The integration of pseudocapacitive electrodes with redox electrolytes is thus an efficient approach to construct energy storage devices such as supercapacitors with both high power- and energy-densities. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitrogen plasma can fabricate disorder layers (3 ∼ 5 nm) on the surface of α-MnO 2. • Abundant oxygen vacancies appeared in the disorder layers of α-MnO 2. • Oxygen vacancies improved the capacitive performance of α-MnO 2 even at high mass loading (12 mg cm−2). The electrochemical performance of high theoretical capacitance MnO 2 is usually restricted to low mass loading electrode due to the slower electron/ion diffusion kinetics in dense electrodes. Defect engineering has been supposed to an effective way to improve the capacitive performance of transition metal oxides. Herein, cactus-like structure MnO 2 was grown on carbon cloth (CC) and treated with N 2 -plasma to obtain the N-MnO 2 electrode with high mass loading of 12 mg cm−2. Benefiting from the hierarchical structure and rich oxygen vacancies, the as-prepared N-MnO 2 electrode delivered a high mass specific capacitance of 443F g−1 and a high areal capacitance of 5320 mF cm−2. Furthermore, the N-MnO 2 electrode released an excellent rate capability with 71.8% capacitance retention at 20 mA cm−2 as well as gratifying cycling life with 96 % capacitance retention after 8 000 cycles at 20 mA cm−2. Moreover, an asymmetrical supercapacitor device assembled by N-MnO 2 and activated CC can achieve a high energy density of 0.56 mWh cm−2 (46 Wh kg−1) at the power density of 5.14 mW cm−2 (420 W kg−1) with good cycle stability. Such facile N 2 -plasma treatment for defect engineering shows great potential in the rational design for advanced supercapacitor electrodes with high mass loading. [ABSTRACT FROM AUTHOR]