Flexible supercapacitors (FSCs) are limited in flexible electronics applications due to their low energy density. Therefore, developing electrode materials with high energy density, high electrochemical activity, and remarkable flexibility is challenging. Herein, we designed nitrogen-doped porous MXene (N-MXene), using melamine-formaldehyde (MF) microspheres as a template and nitrogen source. We combined it with an electrospinning process to produce a highly flexible nitrogen-doped porous MXene nanofiber (N-MXene-F) as a self-supporting electrode material and assembled it into a symmetrical supercapacitor (SSC). On the one hand, the interconnected mesh structure allows the electrolyte to penetrate the porous network to fully infiltrate the material surface, shortening the ion transport channels; on the other hand, the uniform nitrogen doping enhances the pseudocapacitive performance. As a result, the as-assembled SSC exhibited excellent electrochemical performance and excellent long-term durability, achieving an energy density of 12.78 Wh kg−1 at a power density of 1080 W kg−1, with long-term cycling stability up to 5000 cycles. This work demonstrates the impact of structural design and atomic doping on the electrochemical performance of MXene and opens up an exciting possibility for the fabrication of highly FSCs.
Vanadium oxides attract increasing research interests for constructing the cathode of aqueous zinc-ion batteries (ZIBs) because of high theoretical capacity, but the low intrinsic conductivity and unstable phase changes during the charge/ discharge process pose great challenges for their adoption. In this work, V 2 O 3 @C microspheres were developed to achieve enhanced conductivity and improved stability of phase changes. Compounding vanadium oxides and conductive carbon through the in-situ carbonization led to significant improvement of the cathode materials. ZIBs prepared with V 2 O 3 @C cathodes produce a specific capacity of 420 mA h g −1 at 0.2 A g −1 . A reversible capacity of 132 mA h g −1 was achieved at 21.0 A g −1 . After 2000 cycles, the electrode could still deliver a capacity of 202 mA h g −1 at the current of 5.0 A g −1 . Besides, the energy density of batteries constructed with the thus-prepared electrodes was about 294 W h kg −1 at 148 W kg −1 power. The in-situ compounding of V 2 O 3 and carbon resulted in a microstructure that facilitated the stable phase transformation of Zn x V 2 O 5−a •nH 2 O (ZnVOH), which provided more Zn 2+ storage activity than the original phase before electrochemical activation. Moreover, the in-situ compositing strategy presents a simple route to the development of ZIB cathodes with promising performance.
Manganese dioxide is regarded as a promising energy functional material due to its open tunnel structure with enormous applications in energy storage and catalysis. In this paper, α-MnO2 with a 2 × 2 tunnel structure and β-MnO2 with a 1 × 1 tunnel structure were hydrothermally synthesized, which possess characteristic tunnel structures formed by the interconnected unit structure of [MnO6] octahedrons. With regards to their different tunnel dimensions, the specific mechanism of ion intercalation in these two phases and the effect on their performance as aqueous Zn-MnO2 battery cathodes are explored and compared. Comprehensive analyses illustrate that both α-MnO2 and β-MnO2 provide decent capacity in the aqueous battery system, but their intrinsic stability is poor due to the structural instability upon cycling. At the same time, experiments show that α-MnO2 has a better rate performance than β-MnO2 under larger currents, thus implying that the former has a broader application in this aqueous battery system.
Metal compounds encapsulated in carbon materials exhibit promising properties as potential oxygen electrocatalysts. Herein, we first report Fe 2 N@C derived from the biomass bioaccumulation doping method, which offers a new perspective for exploring oxygen reduction reaction (ORR) electrocatalysts with low cost and high performance. The Fe 2 N@NCNTs prepared with our biodoping method display excellent ORR activity with a low half-wave potential (E 1/2 ) and long-term stability in a broad pH range. More importantly, a zinc−air battery (ZAB) constructed with Fe 2 N@NCNTs' catalysts exhibits a high open-circuit voltage (1.53 V), high peak power density (135 mW cm −2 ), and excellent stability (over 200 h). The significantly improved ORR performance can be attributed to the high N-doping level and its hierarchically porous structure. This work offers a path for the development of ORR catalysts for environmental governance and efficient energy conversion.
Electrochemical carbon dioxide reduction reaction (CO2RR) refers to the conversion of carbon dioxide into compounds with added value through electrolysis. It is still a great challenge to design and manufacture efficient CO2RR catalysts for desired products. Producing syngas via CO2RR is an environmentally friendly way to reduce CO2 in the atmosphere and the dependence on fossil fuels. Herein, a new class of Cu/In2O3 nanoparticles (NPs) with controlled phases and structures were successfully prepared as superior electrocatalysts for CO2RR, where the CO/H2 ratios in syngas on Cu/In2O3 NPs/C−H2 remained about 1 : 2 at a broad potential range and the total faradaic efficiency of H2 and CO always remained about 90 %. Electronic structural analysis revealed that the excellent performance was attributed to the electronic interaction between amorphous In2O3 and Cu. This work broadens the horizons for designing and preparing fascinating electrocatalysts for CO2RR.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.