Ac ompetitive complexation strategy has been developed to construct an ovel electrocatalyst with Zn-Co atomic pairs coordinated on Nd oped carbon support (Zn/ CoN-C). Sucha rchitecture offers enhanced binding ability of O 2 ,s ignificantly elongates the O À Ol ength (from 1.23 to 1.42 ), and thus facilitates the cleavage of O À Ob ond, showing at heoretical overpotential of 0.335 Vd uring ORR process.A saresult, the Zn/CoN-C catalyst exhibits outstanding ORR performance in both alkaline and acid conditions with ah alf-wave potential of 0.861 and 0.796 Vr espectively. The in situ XANES analysis suggests Co as the active center during the ORR. The assembled zinc-air battery with Zn/CoN-Ca sc athode catalyst presents am aximum power density of 230 mW cm À2 along with excellent operation durability.T he excellent catalytic activity in acid is also verified by H 2 /O 2 fuel cell tests (peak power density of 705 mW cm À2 ).

Hard carbons (HCs) possess high lithium/sodium storage capacities, which however suffer from low electric conductivity and poor ion diffusion kinetics. An efficient structure design with appropriate heteroatoms doping and optimized graphitic/defective degree is highly desired to tackle these problems. This work reports a new design of N-doped HC nanoshells (N-GCNs) with homogeneous defective nanographite domains, fabricated through the prechelation between Ni 2+ and chitosan and subsequent catalyst confined graphitization. The as-prepared N-GCNs deliver a high reversible lithium storage capacity of 1253 mA h g −1 , with outstanding rate performance (175 mA h g −1 at a high rate of 20 A g −1 ) and good cycling stability, which outperforms most state-of-the-art HCs. Meanwhile, a high reversible sodium storage capacity of 325 mA h g −1 is also obtained, which stabilizes at 174 mA h g −1 after 200 cycles. Density functional theory calculations are performed to uncover the coupling effect between heteroatom-doping and the defective nanographitic domains down to the atomic scale. The in situ Raman analysis reveals the "adsorption mechanism" for sodium storage and the "adsorptionintercalation mechanism" for lithium storage of N-GCNs.

Highly porous nanostructures with large surface areas are typically employed for electrical double-layer capacitors to improve gravimetric energy storage capacity; however, high surface area carbon-based electrodes result in poor volumetric capacitance because of the low packing density of porous materials. Here, we demonstrate ultrahigh volumetric capacitance of 521 F cm−3 in aqueous electrolytes for non-porous carbon microsphere electrodes co-doped with fluorine and nitrogen synthesized by low-temperature solvothermal route, rivaling expensive RuO2 or MnO2 pseudo-capacitors. The new electrodes also exhibit excellent cyclic stability without capacitance loss after 10,000 cycles in both acidic and basic electrolytes at a high charge current of 5 A g−1. This work provides a new approach for designing high-performance electrodes with exceptional volumetric capacitance with high mass loadings and charge rates for long-lived electrochemical energy storage systems.

Atomically dispersed metal catalysts for the oxygen reduction reaction, including their synthesis, characterization, reaction mechanisms and electrochemical energy application, are reviewed.

In this work, MnO(2)/GO (graphene oxide) composites with novel multilayer nanoflake structure, and a carbon material derived from Artemia cyst shell with genetic 3D hierarchical porous structure (HPC), are prepared. An asymmetric supercapacitor has been fabricated using MnO(2)/GO as positive electrode and HPC as negative electrode material. Because of their unique structures, both MnO(2)/GO composites and HPC exhibit excellent electrochemical performances. The optimized asymmetric supercapacitor could be cycled reversibly in the high voltage range of 0-2 V in aqueous electrolyte, which exhibits maximum energy density of 46.7 Wh kg(-1) at a power density of 100 W kg(-1) and remains 18.9 Wh kg(-1) at 2000 W kg(-1). Additionally, such device also shows superior long cycle life along with ∼100% capacitance retention after 1000 cycles and ∼93% after 4000 cycles.

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Nanolayered structures present significantly enhanced electrochemical performance by facilitating the surface-dependent electrochemical reaction processes for supercapacitors, which, however, causes capacitance fade upon cycling due to their poor chemical stability. In this work, we report a simple and effective approach to develop a stable, high performance electrode material by integrating 2D transition metal hydroxide and reduced graphene oxide sheets at nanometer scale. Specifically, a hybrid nanolayer of Ni-Co hydroxide @reduced graphene oxide (Ni,Co-OH/rGO) with an average thickness of 1.37 nm is synthesized through an easy one-pot hydrothermal method. Benefiting from the face to face contact model between Ni-Co hydroxide and rGO sheets, such unique structure presents superior specific capacitance and cycling performance as compared to the pure Ni-Co hydroxide nanolayers. An asymmetric supercapacitor based on Ni,Co-OH/rGO and three-dimensional (3D) hierarchical porous carbon is developed, exhibiting a high energy density of 56.1 Wh kg(-1) along with remarkable cycling stability (80% retention after 17 000 cycles), which holds great promise for practical applications in energy storage devices.

In this study, three-dimensional (3D) hierarchical porous carbon with abundant functional groups is produced through a very simple low-cost carbonization of Artemia cyst shells. The unique hierarchical porous structure of this material, combining large numbers of micropores and macropores, as well as reasonable amount of mesopores, is proven favorable to capacitive behavior. The abundant oxygen functional groups from the natural carbon precursor contribute stable pseudocapacitance. As-prepared sample exhibits high specific capacitance (369 F g(-1) in 1 M H2SO4 and 349 F g(-1) in 6 M KOH), excellent cycling stability with capacitance retention of 100% over 10 000 cycles, and promising rate performance. This work not only describes a simple way to produce high-performance carbon electrode materials for practical application, but also inspires an idea for future structure design of porous carbon.