Search

Zinc/air batteries have received extensive attention due to their low cost, high safety, and high energy density. However, as the zinc/air battery is operated in the practical environment, water exchange between the battery and the environment occurs and affects the specific capacity and service life of the battery. In this paper, high relative‐humidity water‐vapor‐resistant membrane is prepared based on water‐absorbent polyacrylic acid. Using this membrane, water exchange is effectively reduced due to the decreased humidity gradient through gas diffusion electrode. When the thickness of the PAA wet film is 150 μm, the water vapor transmission rate (WVTR) reduced to 51 % of the blank. The excellent discharge performance of zinc/air battery is also achieved with the discharge voltage plateau of 1.10 V and the specific capacity of 612.5 mAh g−1 under the current density of 20 mA cm−2, which is 33.8 % higher than that without PAA membrane. [ABSTRACT FROM AUTHOR]

Al is one of the principal alloying elements for Mg anodes. In this study, a series of Mg–Al alloys has been evaluated as anode materials for optimizing the Al addition amount in Mg anodes with the intention of improving the discharge performance in aqueous batteries. The effect of Al content on the discharge potential and corrosion resistance of the Mg anode has been investigated through microstructure characterization, electrochemical measurements in a half‐cell, discharge morphology analysis, and Mg–water battery tests. The results show that the Mg–1Al alloy possesses a larger corrosion resistance during discharge, with significant increase of the anode utilization efficiency at 1 and 5 mA/cm2 compared with pure Mg. However, a further increase of Al content does not continuously improve the discharge performance of the Mg anode with the decline of utilization efficiency due to the influence of the precipitated phase. This study contributes to a better understanding about the effect of Al on anodic dissolution and corrosion kinetics of the Mg anode. [ABSTRACT FROM AUTHOR]

Zn−Ni secondary battery is a promising candidate as next generation of energy storage battery. However, suffering from the poor cycle performance, its commercialization remains rather challenging. The severe dendrite growth of Zn anode and the rapid capacity decay caused by its uncontrollable dissolution and poor electronic conductivity of ZnO are the main factors. Herein, we report a novel Indium (In) doped ZnO/rGO anode material to inhibit ZnO dissolution through the generated C−O−Zn bond between ZnO and graphene. Meanwhile, the capacity decay decline due to the enhanced electronic conductivity of ZnO by the In doping and combination of graphene. As a result, In doped ZnO/rGO anode material delivers a high specific capacity of 643.4 mAh g−1 (coulombic efficiency 97.63 %) and remains 531.3 mAh g−1 after 125 cycles at 0.5 C, which are significantly higher than bare ZnO. [ABSTRACT FROM AUTHOR]

The gas diffusion electrode (GDE) represents the most significant component in metal–air batteries (MABs). It is essential to understand the underlying behaviors of GDE and optimize its performance. Herein, a polarization separation method from total polarization curve to single activation, ohmic, and mass transport polarizations of GDE in MABs is proposed for the first time, which is then applied in the investigation of detailed polarization behaviors of the GDE by changing the fabrication parameters. As the polytetrafluoroethylene contents in the catalyst and gas diffusion layers and pressing pressure are adjusted, hydrophobicity, porosity, coverage, and thickness are changed to influence the performance of GDE. Through this analysis, a detailed understanding of the structure–performance relationship of GDE is achieved to improve the electrode design, architecture, and fabrication. [ABSTRACT FROM AUTHOR]

An efficient and durable air cathode is of great importance for the commercial application of zinc‐air fuel cell. In this work, a new air cathode with the hydrophobic pores distributed continuously and in gradient was prepared and characterized by the scanning electron microscope (SEM) combined with energy dispersive X‐ray spectroscopy (EDS). Compared with traditional air cathode, our new cathode exhibits attractive performance and lifetime, by which the maximum power density of 252 mW cm−2 and a stable discharge of 3600 h at 50 mA cm−2 are presented in zinc‐air fuel cells. Further investigation shows that the unique pores with the adequate size and hydrophobic property in current collector layer for the new cathode are helpful to prevent the water accumulation, and inhibit the formation of carbonate. Improving stability! A new air cathode with the hydrophobic pores distributed continuously and in gradient was proposed and successfully prepared for zinc‐air fuel cells. The new cathode shows high performance and long lifetime for the maximum power density 252 mW cm−2 and stably 3600 h discharge in a zinc‐air fuel cells. And this cathode efficiently prevents the accumulation of electrolyte and the formation of carbonate inside the electrodes, and is a potential candidate for zinc‐air fuel cells. [ABSTRACT FROM AUTHOR]

Abstract: Insights into the relationship between the crystal planes of metal oxides and the catalytic activity of the oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER) are essential for developing efficient renewable energy technologies. Herein, spinel Co3O4 nanomaterials were synthesized controllably with the specified morphologies of nanocubes, nanosheets, and nanoplates with different exposed planes of {100}, {110}, and {111}, respectively. The effects of the crystal planes of Co3O4 on the activity for the OER, ORR, and HER were subsequently investigated in alkaline media. Different electrocatalytic performances are possibly attributed to the abundance ratios of Co3+/Co2+ over the different exposed planes. The surface Co3+ ions exhibit higher activity for the OER and HER, whereas the surface Co2+ ions exhibit better performance for the ORR; moreover, higher electroconductivity enhances the polarization current for ORR and HER except OER. [ABSTRACT FROM AUTHOR]

Abstract: With the increasing demand of energy storage towards increasing the use of renewable energy technologies, electrochemical systems with low cost, high safety levels, and low environmental impact are critically needed. Zinc–air/oxygen batteries, which were always considered to be cheap, are losing their competitive advantages due to poor cyclic performance and energy efficiency. Herein, an effective strategy for oxygen recycling, which reduces the cost of oxygen to as low as ¢ 0.2 kWh−1 per cycle, is reported. With the use of oxygen, the performance of zinc–oxygen batteries is largely increased, with a maximum power density of 290 mW cm−2, stable cycling for more than 1500 cycles, an average energy density of 60 %, and elimination of carbonates. A 1 kW/1 kWh zinc–oxygen battery system is also integrated and exhibits a satisfactory energy efficiency of 58 % and a high working power density of 75 mW cm−2. [ABSTRACT FROM AUTHOR]

Zinc-oxygen batteries are promising candidates for electrical vehicles and electric grid energy storage due to their low cost, high safety levels, and low environmental impact. The oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) represent the most significant processes in zinc-oxygen batteries. The development of nonprecious metal catalysts for OER with satisfactory performances and low cost (especially prepared by a straightforward synthesis route), still poses a significant challenge. Herein, we report an exceptionally facile and easily scalable method to produce NiFe layered double hydroxide (LDH) coated nickel foam by immersing nickel foams into aqueous solutions containing NiCl2 and FeCl2 and keeping them standing for a certain period of time. Without any other complicated technique or organic reagent, microflower-shaped NiFe LDHs can be obtained. The resulting electrode shows excellent OER performance with a low overpotential of 210 mV at a 10 mA cm−2 constant current polarization and stable operation for more than 100 charge-discharge cycles in zinc-oxygen batteries. [ABSTRACT FROM AUTHOR]