Shanshan Sun

Silver nanoparticles supported on a nitrogen-doped graphene aerogel composite catalyst for an oxygen reduction reaction in aluminum air batteries

Herein, we developed silver nanoparticles supported on a nitrogen doped graphene (Ag/N-RGO) aerogel by a facile one-step hydrothermal method as an efficient ORR electrocatalyst. The Ag/N-RGO showed remarkable catalytic activity and stability in the alkaline electrolyte. The as-proposed facile strategy to synthesize Ag/N-RGO is promising for the development of inexpensive ORR electrocatalysts.

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.

Promoting effects of Ce0.75Zr0.25O2 on the La0.7Sr0.3MnO3 electrocatalyst for the oxygen reduction reaction in metal–air batteries

Perovskites have been proposed as one of the best oxygen reduction reaction catalysts (ORRCs) to substitute noble metals though their catalytic activity still need to be improved. It is well accepted that improving the oxygen adsorption capacity is beneficial to the catalytic activity of La1−xSrxMnO3 (LSM) perovskites. Herein, we synthesized the LSM-based composite by compositing La0.7Sr0.3MnO3 with Ce0.75Zr0.25O2 (CZ) which is used as an excellent oxygen storage material by a two-step solution method. The LSM–CZ composite is revealed as a novel electrocatalyst for the oxygen reduction reaction with the direct four-electron transfer mechanism and a positive onset potential in comparison with the commercial Pt/C catalyst. And its onset potential is almost the most positive one among those of the perovskites stemmed from LaMnO3. In addition, the stability of LSM–CZ is even superior to that of Pt/C, and LSM–CZ almost accumulates no intermediate product of HO2− (∼0.8%) after aging for 100 000 seconds. By using LSM–CZ as the ORRC, the maximum power density of the aluminum–air battery can reach 233.4 mW cm−2. Our work paves the way for the development of perovskite catalysts for energy conversion and storage.

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.

Transition metal oxide-based oxygen reduction reaction electrocatalysts for energy conversion systems with aqueous electrolytes

In the past decades, there has been a strong incentive to develop electric vehicles by the introduction of batteries to reduce the dependence on petroleum oil and mitigate the tailpipe emissions. Lithium-ion batteries have dominated the electric vehicle market due to their high capacity and energy efficiency. However, the insufficient energy density of lithium-ion batteries is still a big problem for the development of electric vehicles. Metal–air batteries have been considered among the most promising power sources for electric vehicles due to some attractive advantages such as high energy density, low cost and environmental friendliness. One of the most important issues for metal–air batteries is developing oxygen reduction reaction catalysts with high catalytic activity and stability. Transition metal oxides are a series of important catalysts for the oxygen reduction reaction in alkaline solution. The purpose of this paper is to provide a comprehensive review of the recent progress in transition metal oxide-type catalysts for the ORR in aqueous media, including simple transition metal oxide-type catalysts, perovskite-type catalysts, spinel-type catalysts and other ternary transition metal oxides catalysts (such as double perovskite oxides, pyrochlore oxides, Ruddlesden–Popper oxides, LiCoO2-related oxides, and Mn-based mullite oxides). Moreover, we also discuss the factors influencing the transition metal oxide-type catalysts for the ORR in metal–air batteries with aqueous electrolytes.

One-Pot Synthesis of Co3O4/Ag Nanoparticles Supported on N-Doped Graphene as Efficient Bifunctional Oxygen Catalysts for Flexible Rechargeable Zinc-Air Batteries

Flexible rechargeable zinc-air batteries are considered as one of the most promising power supplies for the emerging flexible and wearable electronic devices. However, the development of flexible zinc-air batteries is stagnant due to the lack of efficient bifunctional catalysts with high oxygen catalytic activity and flexible solid-state electrolytes with high mechanical stability and ionic conductivity. In this work, Co3 O4 /Ag@NrGO composite was synthesized by a facile one-pot method, and the catalyst shows remarkable oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) bifunctional catalytic activity and good long-term stability. In particular, the OER overpotential of Co3 O4 /Ag@NrGO reaches 437 mV, outperforming that of the commercial IrO2 catalyst. This can be attributed to the combined effects of Co3 O4 , Ag, and N-rGO. Furthermore, PAA (polyacrylic acid) and PVA (polyvinyl alcohol) based gel-electrolytes have been developed as flexible solid-state electrolytes for zinc-air batteries. The results show that PAA-based electrolyte is more favorable to the flexible zinc-air battery with a high power density due to its relatively high ionic conductivity. The maximum power density of flexible zinc-air batteries with Co3 O4 /Ag@NrGO catalyst and PAA-based electrolyte can reach 108 mW cm-2 , which is almost the highest value reached in recent reports. This work will provide valuable guidance for the development of flexible rechargeable zinc-air batteries with high power density and stability.