Search

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]

Li–O 2 batteries with higher theoretical specific capacity are a promising energy storage system. Designing an efficient cathode catalyst can alleviate the problem that derives from the sluggish dynamic process. In this study, morphologies of MnCo 2 O 4 are easily tuned from square blocks to nanowire arrays by simple adjusting mole numbers of NH 4 F under hydrothermal conditions. The MnCo 2 O 4 nanowire arrays on carbon cloth with a large specific surface area of 194.9 m2 g−1 are synthesized by 9 mmol NH 4 F, which as a cathode catalyst for Li–O 2 batteries can maintain for 167 cycles with a cutoff capacity to 500 mA h g−1 at 340 mA g−1 (0.2 mA cm−2). And the MnCo 2 O 4 nanowire array electrodes show the discharge capacities of 8364, 7544 and 5887 mA h g−1 at 200, 400 and 800 mA g−1, respectively, which show good rate performance. [ABSTRACT FROM AUTHOR]

Ni-based hydroxides nanomaterials are widely used in alkaline storage devices. Under the guidance of density functional theory calculations and experimental investigations, here, (Ni 0.8 Co 0.1 Mn 0.1)(OH) 2 is designed and prepared on CuO nanowire arrays, demonstrating Co and Mn co-substitution resulted in enhanced capacity and stability of Ni(OH) 2. The enhanced performance is mainly thanks to the low deprotonation energy and the facile electron transport, which results from the synergistic interactions among Ni, Co and Mn. Ni-Zn battery and alkaline hybrid supercapacitor with (Ni 0.8 Co 0.1 Mn 0.1)(OH) 2 (8.4 mg cm−2) as positive electrode can achieve infusive energy density of 605.2 and 270.1 Wh kg−1, respectively. The finding lay a foundation for further the design and fabrication of high-performance Ni-based nanomaterials for alkaline energy storage. By combining the experiment and density functional theory calculations, substituting part of Ni in Ni(OH) 2 with Co and Mn can improve its specific capacity and cycling stability, which are resulted from the low deprotonation energy and the facile electron transport. The (Ni 0.8 Co 0.1 Mn 0.1)(OH) 2 @CuO@CF composite electrode with a high mass loading of 8.4 mg cm−2 shows very high energy density in Ni-Zn battery (605.2 Wh kg−1) and alkaline hybrid supercapacitor (270.1 Wh kg−1). [Display omitted] • Co and Mn co-substituted Ni(OH)2 was grown on CuO nanowire arrays. • Substituting a part of Ni in Ni(OH)2 with Co and Mn can improve capacity. • The enhanced capacity was attributed mainly to the facile electron transport. • The core-shell heterostructures resulted in high energy density. [ABSTRACT FROM AUTHOR]

Rechargeable Li–O 2 batteries (LOBs) have attracted great attentions for its high theoretical energy density, and were considered to be the next potential energy storage devices. However, the high overpotential and poor cycling performance hinder the further development of LOBs. In this study, a binder-free air electrode of MnCo 2 O 4 nanosheets supporting on the carbon cloth, was directly prepared by electrodeposition and calcination. MnCo 2 O 4 @carbon cloth possesses a flaky-porous and interconnected network nanostructure. The MnCo 2 O 4 @carbon cloth electrode could operate more than 108 cycles at 340 mA/g with a limiting specific capacity of 500 mA h/g. And it could deliver a first discharge specific capacity of 7238 mA h/g at 200 mA/g with the charge/discharge overpotential of 1.46 V. And it could achieve 3000 mA h/g when the current density was increased up to 800 mA/g. Such good electrocatalytic activity towards oxygen reduction reaction should derive from the high valence state of Mn3+ and Mn4+, and the three-dimensional interconnected mesoporous structure which can benefit oxygen diffusion and electrolyte infiltrate to form triple-phase regions in favour of oxygen reduction. Image 1 • A 3D mesoporous MnCo 2 O 4 @carbon cloth was prepared by potentiostatic deposition. • It exhibited a high initial specific capacity of 7238 mA h/g at 200 mA/g. • It operated more than 107 cycles at 340 mA/g in the potential window of 2–4.5 V. • Their good ORR performance was ascribed to the high valence state of Mn3+ and Mn4+. [ABSTRACT FROM AUTHOR]