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Ternary NiCo2O4 is attracting substantial attention as electrode material for high-performance supercapacitors. Unfortunately, it still suffers from low specific capacitance in terms of its relative low conductivity. Herein, an effective and general surface modulation strategy involving in-situ phosphatization of NiCo2O4 nanowire arrays is developed, and the pseudopotential performance of the resulting NiCo2O4 nanowire arrays is dramatically increased. The surface modulation can increase active sites, enhance conductivity and accelerate charge transfer kinetics. Importantly, at a large current density of 20 A g−1, the optimal NiCo2O4 electrode possesses a significant specific capacitance of 1642 F g−1. When the current density increases from 2 to 20 A g−1, an excellence rate capability with 81.3% specific capacitance is maintained. Also, the resulting electrode owns excellent long-term cycle stability that the specific capacitance only decreases 4.3% after 10,000 cycles. Moreover, an advanced asymmetric supercapacitor device is build up based on the optimal NiCo2O4 cathode and a graphene anode, reaching an outstanding energy density of 92.2 Wh kg−1 with outstanding long-term durability.

A series of remarkable crystalline compounds were obtained from the simple one-step solvothermal reaction of zinc nitrate or copper nitrate, benzentricarboxylate (BTC) and certain macrocyclic metal complexes. In these compounds, the macrocyclic metal complexes were alternately arrayed as noncoordinating guests in the cages of a Zn-BTC or Cu-BTC-based metal organic framework host matrix. Powder X-ray diffraction analysis, ICPAES, EDS, H2 adsorption studies demonstrated the validity of encapsulation of macrocyclic metal complexes and the enhancement of hydrogen capacities. It is the first time that the construction of metal-organic frameworks (MOFs) is based on macrocyclic metal complexes as templates. Actually, it is worth to be noted that the introduction of macrocylic metal complexes contributes to increasing the active sites or the adsorption sites interacting to hydrogen gas.

With the rapid development of portable and wearable electronics, energy storage devices featuring high energy and power densities, long-cycle lifetime, environment friendliness, safe operation, lightweight, ultrathin thickness and flexibilityl have become increasingly important. Herein, a high-performance flexible quasi-solid-state Ni–Fe battery was rationally developed by engineering the surfaces of α-Fe2O3 nanorods (NRs) and NiCo2O4 nanowire arrays (NWAs) as the anode and cathode, respectively. Benefiting from the flexible current collector, fast charge transport, rapid ion diffusion, and sufficient electroactive sites, this flexible quasi-solid-state Ni–Fe battery presents outstanding capacity as high as 134.5 mA h g−1. Furthermore, this battery also has long cycling life, and could be cycled up to 2600 times with 82.7% capacity retention. Most importantly, the as-fabricated flexible quasi-solid-state Ni–Fe battery achieves an admirable energy density of 227 W h kg−1, together with a peak power density of 23.4 kW kg−1, thus outperforming the most recently reported Ni–Fe batteries and other flexible energy storage devices. Coupled with the advantages of admirable energy density and durability, this highly flexible and rechargeable Ni–Fe battery will greatly enrich the energy storage technologies for future flexible electronic device applications.

Aqueous Zn–MnO2 batteries have great potential as flexible energy storage devices owing to their low cost, high energy density, safety, and environmental friendliness. However, their development is plagued by the poor cycling stability, and the use of heavy zinc foil as the anode is antithetical to the flexible devices. Herein, we construct a high-performance and stable flexible rechargeable quasi-solid-state Zn–MnO2 battery using MnO2 nanorod arrays and tiny Zn nanoparticles uniformly deposited on N-doped porous carbon cloth as the free-standing cathode and anode, respectively. The 3D porous nitrogen-doped carbon cloth substrate with high electric conductivity and good flexibility serves as an ideal support for guest active materials of MnO2 nanorod arrays and tiny Zn nanoparticles, which can effectively buffer the volume change giving rise to good cycling ability. Significantly, the device is able to deliver a remarkable capacity of 353 mA h g−1 and good cycling stability (93.6% after 1000 cycles) in an aqueous electrolyte. Moreover, when using PVA/ZnCl2/MnSO4 gel as the electrolyte, the as-fabricated quasi-solid-state Zn–MnO2 battery still achieves a high energy density of 440 W h kg−1, high power density of 7.9 kW kg−1 and excellent cycling ability. This work heralds new opportunities in the development of high-performance, low-cost, safe and flexible electronic devices.

Commercial carbon fiber paper (CFP) has been rarely used as an active electrode material for supercapacitors (SCs) due to its poor electrochemical activity and limited surface area. Herein, we report a facile, scalable and effective thermal oxidation method to directly activate CFP as a robust electrode material in SCs. Significantly, the activated CFP electrode exhibits a high areal capacitance of 0.75 F cm−2 at 5 mA cm−2 and excellent rate capability as well as cycling performance. Moreover, an advanced asymmetric supercapacitor (ASC) device with a remarkable energy density of 2.3 mW h cm−3 and outstanding long-term durability is achieved based on the as-obtained activated CFP electrode as the anode.