Graphene-Based Oxygen Reduction Reaction Catalysts for Metal Air Batteries

In the past few years, the metal air batteries developed fast due to their remarkably high theoretical energy output. So far, the oxygen reduction reaction catalysts still have been the bottleneck for high power application of metal air batteries because of their sluggish kinetics. Recently, the graphene-based oxygen reduction reaction catalysts (GORRC) with high catalytic activity have been intensively reported. In this review, we focus on the recent progress and current situation of GORRC, and divide them into three categories, graphene as catalyst support, nitrogen doped graphene as the catalyst, and hybrids of nitrogen doped graphene and other catalysts as the catalyst. As an outstanding catalyst support, graphene can not only decrease the application amount of active components but also improve their catalytic activity and long-term stability. After doped by nitrogen, the graphene catalysts exhibit enhanced catalytic activity for the oxygen reduction reaction. In addition, the excellent catalysts can be obtained as the nitrogen doped graphene and other type of catalysts are hybridized. The catalytic activity and long-term stability of the hybrids are even better than that of the commercial Pt/C catalyst. Furthermore, the remarks on the challenges and perspectives of research directions are proposed for further development of GORRC which can be used in the metal air batteries

Study on the fracture behavior of the planar-type solid oxide fuel cells

Study on the fracture behavior of the planar-type solid oxide fuel cell

Effect of phase transformation of zirconia on the fracture behavior of electrolyte-supported solid oxide fuel cells

Effect of phase transformation of zirconia on the fracture behavior of electrolyte-supported solid oxide fuel cell

Improving catalytic activity of layered lithium transition metal oxides for oxygen electrode in metal-air batteries

Lithium transition metal oxide has superior performance for oxygen evolution reaction (OER), while its activity for catalyzing oxygen reduction reaction (ORR) is too low to meet the demand of practical applications. Herein, the NCM-based (NCM, LiN1/3Co1/3Mn1/3O2) composite materials are prepared through the two steps method. The NCM-2 (Mn2O3/(LiN1/Co1/3Mn1/3O2)-Co-3) hybrid material demonstrates excellent ORR catalytic property and high OER catalytic performance, as well as the superior stability. Besides, with NCM-2 hybrid materials as catalysts of air cathode, the Al-air battery and Zn-air battery both exhibit higher power density. Therefore, based on results of Brunauer-Emmett-Teller and O-2 temperature programmed desorption analysis, the improved catalytic performance ascribed to large specific surface area, pore structure and enhanced oxygen adsorption ability. In this work, the catalytic activity of lithium transition metal oxide has been improved, and a new method was provided to synthesize bifunctional catalysts for metal-air batteries. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved

Performance prediction and regulation of a tubular solid oxide fuel cell and hydrophilic modified tubular still hybrid system for electricity and freshwater cogeneration

Tubular solid oxide fuel cells (TSOFCs) are a promising technology for electricity generation; however, they also generate high-temperature waste heat, leading to reduced efficiency and energy wastage. To address this challenge and unlock the full potential, a novel geometry-matching hybrid system incorporating methane reforming TSOFC and hydrophilic modified tubular still (HMTS) is proposed and modelled. Considering various irreversible losses, vital performance indicators including power output, energy efficiency and exergy efficiency are firstly derived, through which comprehensive thermodynamic performance features of the TSOFC/HMTS hybrid system are predicted. The proposed system design demonstrates a significant advantage by achieving a maximum output power density that is 99.7 % higher and a corresponding energy efficiency that is 57.3 % higher compared to the standalone TSOFC. Extensive parametric analyses reveal that raising the operating temperature or stream/carbon ratio positively enhances the system's performance. Conversely, increasing electrode tortuosity, electrolyte thickness, wind velocity, or tubular shell diameter negatively degrades the system's performance. In addition, the anode thickness is an optimizable parameter. Local sensitivity analyses identify that the operation temperature and electrode tortuosity are, respectively, the most and least sensitive parameters for performance regulation. The findings make a significant step forward in the field of sustainable and innovative energy solutions

Template-directed fabrication of porous gas diffusion layer for magnesium air batteries

The uniform micropore distribution in the gas diffusion layers (GDLs) of the air-breathing cathode is very important for the metal air batteries. In this work, the super-hydrophobic GDL with the interconnected regular pores is prepared by a facile silica template method, and then the electrochemical properties of the Mg air batteries containing these GDLs are investigated. The results indicate that the interconnected and uniform pore structure, the available water-breakout pressure and the high gas permeability coefficient of the GDL can be obtained by the application of 30% silica template. The maximum power density of the Mg air battery containing the GDL with 30% regular pores reaches 88.9 mW cm(-2) which is about 1.2 times that containing the pristine GDL Furthermore, the GDL with 30% regular pores exhibits the improved the long term hydrophobic stability. (C) 2015 Elsevier B.V. All rights reserved

La1-xAgxMnO3 electrocatalyst with high catalytic activity for oxygen reduction reaction in aluminium air batteries

The LaMnO3 (LMO) perovskite catalyst has been proposed as one of the best oxygen reduction reaction catalysts (ORRCs) to substitute noble metals. However, its ORR catalytic activity needs to be further improved. Here, La1-xAgxMnO3 (LAM) perovskites doped with Ag are synthesized by a facile improved sol-gel method. The structures, morphologies and valence states of Mn and oxygen adsorption behaviors of these LAM samples are characterized, and their catalytic activities toward ORR are studied by the rotating ring-disk electrode (RRDE) and aluminum air battery technologies. The results demonstrate that the doping of 30% Ag in the A-site of LMO (LAM-30) can effectively improve its ORR catalytic activity due to the regulation of the manganese valence and improvement of the oxygen adsorption capacity. Besides the remarkable ORR catalytic activity, the LAM-30 catalyst exhibits good durability. The current retention is as high as 98% after the aging test for 10 000 seconds. In addition, the maximum power density of the aluminum air battery using LAM-30 as the ORRC can reach 230.2 mW cm(-2), which indicates that LAM-30 can be used as a promising ORRC in aluminum air batteries

Performances of an Al-0.15 Bi-0.15 Pb-0.035 Ga alloy as an anode for Al-air batteries in neutral and alkaline electrolytes

Aluminum is a very good candidate anode for metal-air batteries due to its negative electrode potential, high theoretical electrochemical equivalent value, abundant reserves and environmental friendliness. The corrosion behavior and electrochemical properties of the Al-1.5Bi-1.5Pb-0.035Ga alloy were investigated by self-corrosion tests and electrochemical techniques, and compared with that of pure Al and Al-Bi-Pb alloys. The performances of Al-air batteries based on these alloy anodes were studied by constant current discharge and I-V discharge tests. The corrosion morphology and discharge surface were also investigated by scanning electron microscopy (SEM)and energy dispersive X-ray (EDX) analysis. The results show that the Al-Bi-Pb-Ga alloy provides a more negative potential and exhibits an enhanced activity in NaCl solution compared with pure Al and Al-Bi-Pb alloys, and gives high power density (253.4 +/- 2.5 mW cm(-2)) and desirable anode efficiency (85.4 +/- 0.5%) when used as an anode for Al-air batteries in KOH solution. Moreover, the dissolution mechanism of the Al-Bi-Pb-Ga alloy is also characterized based on the electrochemical measurements and microstructure observations

La0.8Sr0.2Co1-xMnxO3 perovskites as efficient bi-functional cathode catalysts for rechargeable zinc-air batteries

In this work, the La0.8Sr0.2Co1-xMnxO3 (x = 0, 0.2, 0.4, 0.6, 0.8,1) perovskites (LSCM) were synthesized by a facile improved sol-gel method. The crystalline structures, morphologies, Co/Mn valence states and oxygen adsorption/desorption behavior of the LSCM materials are systematically studied, and their catalytic activities toward ORR and OER are investigated by the rotating-disk electrode (RDE) and zinc-air battery techniques. It is found that the proper substitution of Co with Mn can efficiently improve the ORR and OER activities of La0.8Sr0.2CoO3 perovskite at the same time. The LSCM-60 catalyst exhibits the optimum bi-functional activity. It is mainly attributed to the regulation of the Bi-site Co/Mn valence states and the improvement of the oxygen adsorption/desorption capability. Besides of the good bifunctional property, LSCM-60 shows superior durability compared with Pt/C and IrO2 catalysts. When using LSCM-60 as the cathode catalyst of zinc-air batteries, the low charge-discharge overpotential (1.05 Vat 50 mAcm (2)) and the excellent long-term cycle stability were obtained. This study exhibits the possibility to improve the bi-functional activity of La0.8Sr0.2CoO3 through a simple doping process. (C) 2017 Elsevier Ltd. All rights reserved