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Aqueous rechargeable batteries (ARBs) are generally safer than non-aqueous analogues, they are also less-expensive, and more friendly to the environment. However, the inherent disadvantage of the narrow electrochemical window of H2O seriously restricts the energy density and output voltage of ARBs, especially aqueous rechargeable Fe-based batteries. Herein, we introduce a new battery system: the anode contains C@Fe/Fe2O3 composite, which is interfaced with an alkaline electrolyte; the cathode contains LiMn2O4 in contact with a neutral electrolyte. A Li+-conducting membrane is carefully selected to decouple the electrode-electrolyte, which effectively widens the electrochemical window to above 2.65 V, thereby enables an aqueous rechargeable iron battery. Its average output voltage is 1.83 V and its energy density is 235.3 Wh/kg at 549 W/kg. In this work, we propose the energy storage mechanism with the aid of density functional theory (DFT). The calculated reduction potential of the anode agrees with the experimental value. Furthermore, this battery system demonstrates long cycle lifespan of approximately 2500 cycles at 2 A/g, corresponding to a capacity retention of 82.1%. These results are very far superior than those of mainstream aqueous rechargeable Fe-based batteries, which guarantee future investigation for storing electricity energy. [ABSTRACT FROM AUTHOR]

A binary Mo/Fe-nitrogen-carbon material (MoFe-NC) catalyst was synthesized following the concept of biological nitrogen fixation. The MoFe-NC catalyst demonstrated a maximum N2 reduction faradaic efficiency of 39.9% and a NH3 yield rate of 28.5 μg mgcat−1 h−1 under ambient conditions. [ABSTRACT FROM AUTHOR]

Composites of MnO2 nanosheet arrays vertically grown on the surface of vapor-grown carbon fibers (VGCFs) are fabricated by a low-temperature redox reaction between KMnO4 and the VGCFs. An assembled AC/0.5 M K2SO4/MnO2@VGCF electrochemical capacitor exhibits a higher specific capacitance, as well as a better rate capability, at a fast-current density compared to the capacitor built on hydrothermally prepared, standalone MnO2. Electrochemical tests revealed that VGCFs act as a conducting matrix, which effectively improves the conductivity of MnO2 nanosheets during cycling. [ABSTRACT FROM AUTHOR]

Compared with common lithium-ion batteries, Li–O2 batteries are recognized as attractive power systems owing to their superior high theoretical specific energy. However, sluggish dynamic processes, including the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), need to be overcome to allow their practical application. Here, Fe-doped NiO nanosheets were prepared using a hydrothermal method on carbon cloth (CC) and acted as the electrode material in Li–O2 batteries. The Fe-doped NiO/CC electrodes can exhibit stable performance for 102 cycles under a restricted capacity of 500 mA h g−1 at a current density of 340 mA g−1 and show discharge capacities of about 6010 and 5000 mA h g−1 at current densities of 100 and 200 mA g−1, respectively. Li–O2 batteries based on the Fe-doped NiO/CC electrodes deliver better electrochemical and electrocatalytic performances compared to the NiO/CC electrodes owing to the substitution of Ni2+ in NiO by Fe3+ to provide further active sites, which can significantly enhance the stability during ORR and OER catalysis. Moreover, Fe-doped NiO/CC has more oxygen vacancies than NiO/CC, which is also very beneficial for supporting the cycling stability and reversibility of Li–O2 batteries. [ABSTRACT FROM AUTHOR]

The design of three-dimensional (3D) core-shell heterostructures is an efficient method to achieve high mass specific capacity of electroactive materials under high mass loading. In this work, porous Ni4Co1-OH nanosheets with a mass loading of 7.7 mg·cm−2 are obtained by using Ni4Co1-(NO3)2(OH)4 supported on the CuO nanowires as precursors via an unavoidable electrochemically induced phase reconstruction. During the electrochemical reconstruction process, the NO3− anions in Ni4Co1-(NO3)2(OH)4 are easily replaced by OH− anions in the electrolyte. The phase reconstruction is accompanied by the decrease of ionic diffusion resistance and the increase of pore volume, and the shift of binding energy. The obtained Ni4Co1-OH nanosheets show a high mass specific capacity of 363.6 mAh·g−1 at 5 mA·cm−2. The as-fabricated alkaline hybrid supercapacitor and Ni-Zn battery deliver high energy density of 293.1 and 604.9 Wh·kg−1, respectively, indicating excellent alkaline energy storage performance. [ABSTRACT FROM AUTHOR]

Developing rechargeable Li–O2 batteries is an effective way to relieve current energy stress and electricity shortage. Designing an oxygen electrode catalyst with superior bifunctional catalytic activity can significantly improve the performance of Li–O2 batteries. In this study, unique CuCo2O4 nanowires@NiO nanosheets core/shell arrays are directly synthesized on carbon cloth (CC) through a facile hydrothermal and electrochemical deposition. The one-dimensional CuCo2O4 nanowires have good electrical conductivity and a short transmission path to overcome sluggish kinetic processes. The two-dimensional NiO nanosheets can promote the easier formation and decomposition of Li2O2. The CuCo2O4@NiO/CC electrode can run 181 cycles with the capacity limit of 500 mA h g−1 at 0.2 mA cm−2, much higher than the CuCo2O4 electrode (107 cycles) and can exhibit the discharge capacity of 10 843 mA h g−1 at 0.1 mA cm−2, as well as better rate performance than CuCo2O4 electrode. Thus, the three-dimensional self-supported CuCo2O4 nanowires@NiO nanosheets core/shell arrays can take full advantage of each chemical component, provide more effective space for Li+ and O2 diffusion and Li2O2 storage, and possess better electrical conductivity. [ABSTRACT FROM AUTHOR]

Three-dimensionally mesoporous La1-xSrxFeO3 (x = 0, 0.4, 0.6) precursors have been synthesized through a facile solvothermal process. After high-temperature sintering, La1-xSrxFeO3 still exhibits uniform morphology and good dispersibility, which provides a porous structure and favorable surface area. Particularly, La0.4Sr0.6FeO3 shows the biggest surface area of 58 m2 g−1. Doping also induces the generation of oxygen vacancies and Fe4+, which is beneficial for the conductivity and catalytic activity of the materials. Complete with favorable structure and electrochemical activity, La0.4Sr0.6FeO3 exhibits bifunctional catalytic activity in alkaline solution. Applied as a cathode catalyst in Li-O2 batteries, it shows a larger discharge capacity of 23 905 mA h g−1 and a better cycling stability of 100 cycles. [ABSTRACT FROM AUTHOR]

A binary Mo/Fe-nitrogen-carbon material (MoFe-NC) catalyst was synthesized following the concept of biological nitrogen fixation. The MoFe-NC catalyst demonstrated a maximum N2 reduction faradaic efficiency of 39.9% and a NH3 yield rate of 28.5 μg mgcat−1 h−1 under ambient conditions. [ABSTRACT FROM AUTHOR]