Application Of Rechargeable Metal-air Batteries Research Articles

A facile and green strategy for mass production of dispersive FeCo-rich phosphides@N,P-doped carbon electrocatalysts toward efficient and stable rechargeable Zn-air battery and water splitting

One key step for advancing the widespread practical application of rechargeable metal-air batteries and water electrolysis fundamentally relies on the development of cost-effective multifunctional electrocatalysts toward oxygen and hydrogen-involving reactions. The present work initiates a tofu-derived one-pot strategy for green, facile, and mass production of highly active and stable catalyst toward oxygen reduction/evolution and hydrogen evolution reactions, through the preparation of Fe/Co cross-linked tofu gel and the subsequent pyrolysis. Despite the free use of additional N/P precursors or pore-forming agents, the as-prepared materials comprise highly dispersive FeCo-rich phosphides nanoparticles and porous N,P co-doped carbon network inherited from the tofu skeleton. The resultant catalysts exhibit remarkably enhanced trifunctional activities as compared to the Fe2P and Co2P counterparts, along with better long-term stabilities than the benchmark RuO2 and Pt/C catalysts. Accordingly, the as-assembled Zn-air battery delivers a large power density (174 mW cm−2) with excellent cycle stability (the gap of charge/discharge voltage@10 mA cm−2 increases by 0.01 V after 720 h of operation, vs. 0.16 V of Pt/C-RuO2 based battery after 378 h). Furthermore, the as-constructed alkaline electrolyzer just requires a small voltage of 1.55 V@10 mA cm−2, which outperforms nearly all of those of biomass-derived electrocatalysts ever reported, and that of noble metal catalysts-based electrolyzers (1.72 V@10 mA cm−2 for Pt/C-RuO2), underscoring their bright future toward commercial applications in green energy conversion devices.

Co3O4 Nanocube -3DrGO Hybrid Structure: Efficient Non-Noble-Metal Electrocatalyst with High-Performance for Oxygen Evolution Reaction

Oxygen Evolution reaction (OER) by water splitting is one of the emerging technologies for the ongoing research in the field of sustainable, clean yet highly efficient energy generation. Electrocatalysis for OER is a key step forward towards achieving this goal and enormous efforts has been devoted recently on the development of high-performance electrocatalysts that are cost-effective, abundant as well as environmentally benign. Transition metal based non-noble electrocatalysts anchored on high-surface area, conductive carbonaceous support serves the dual purpose of being highly catalytically active as well as having excellent stability. Herein, we report the synthesis of Co3O4 nanocube -3DrGO hybrid structure as a high-performance electrocatalyst for OER applications via a facile hydrothermal synthesis technique followed by heat treatment. The unique nanocube like structure offers more active edge sites which plays an important role in its catalytic performance. The hybrid structure exhibits an overpotential of 428 mV (vs RHE) and a small tafel slope of 96.92 mV dec-1 with 100% faradaic efficiency in 1 M NaOH alkaline electrolyte. The electrode needs an overpotential of 648 mV to afford a current density of 10 mA cm-2. This offers a low-cost electrocatalytic electrode for water splitting and rechargeable metal–air battery applications. Figure 1

Facile synthesis of ternary spinel Co–Mn–Ni nanorods as efficient bi-functional oxygen catalysts for rechargeable zinc-air batteries

Facile synthesis of high efficient bi-functional oxygen catalysts is important for large-scale application of rechargeable metal-air batteries. Herein, an ethanol-water mediated co-precipitation approach is applied to fabricate Co–Mn–Ni (CMN) ternary spinel oxides with uniform 1D structure. Their catalytic activities toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are investigated by the rotating ring-disk electrode (RRDE) techniques. The ternary spinel oxide with the Co/Mn/Ni atomic ratio of 2:3:1 (CMN-231) exhibits the best bi-functional activities among the as-prepared ternary, binary and unitary spinel oxides (△E is as low as 0.88 V), which can be attributed to its reasonable element composition, mesoporous nanorod structure, strong oxygen-adsorption ability and good charger-transfer capability. In addition, the CMN-231 catalyst demonstrates a strong stability during long-term operation. This well-designed catalyst is applied in a homemade zinc-air battery, and exhibits good charge–discharge performances (voltage gap is 0.9 V at 50 mA cm−2) and remarkable cycling stability.

"Ship in a Bottle" Design of Highly Efficient Bifunctional Electrocatalysts for Long-Lasting Rechargeable Zn-Air Batteries.

The poor durability of bifunctional oxygen electrocatalysts is one main bottleneck that suppresses the widespread application of rechargeable metal-air batteries. Herein, a "ship in a bottle" design is achieved by impregnating fine transition metal dichalcogenide nanoparticles into defective carbon pores that act as interconnected nanoreactors. The erected 3D porous conductive architecture provides a "highway" for expediting charge and mass transfer. This design not only delivers a high surface-to-volume ratio to increase numbers of exposed catalytic sites but also precludes nanoparticles from aggregation during cycling owing to the pore spatial confinement effect. Therefore, the long-term plague inherent to nanocatalyst stability can be solved. Moreover, the synergistic coupling effects between defect-rich interfaces and chemical bonding derived from heteroatom-doping boost the catalytic activity and prohibit the detachment of nanoparticles for better stability. Consequently, the developed catalyst presents superior bifunctional oxygen electrocatalytic activities and durability, out-performing the best-known noble-metal benchmarks. In a practical application to rechargeable Zn-air batteries, long-term cyclability for over 340 h is realized at a high current density of 25 mA cm-2 in ambient air while retaining an intact structure. Such a universal "ship in a bottle" design offers an appealing and instructive model of nanomaterial engineering for implementation in various fields.

Carbon-coated MnCo2O4 nanowire as bifunctional oxygen catalysts for rechargeable Zn-air batteries

The catalytic activity of spinel-type MnCo2O4 is often limited by the poor electronic conductivity, limited specific surface area and inferior stability in oxygen reduction reaction and oxygen evolution reaction. In this study, carbon-coated MnCo2O4 nanowire (MnCo2O4@C) is prepared by a self-template method from MnCo2-NTA nanowire precursor. MnCo2O4@C shows excellent electrocatalytic performance and improved circulation stability, with an onset potential of 0.92 V and current retention rate of 99% within 10000 s at 0.80 V vs. RHE, better than the commercial Pt/C (Eonset = 0.94 V, current retention rate 94%). Further study shows that the oxygen reduction mechanism of MnCo2O4@C follows quasi-four-electron transfer process. The carbon provides conductive network and promotes the fast transfer of electrons in between the carbon network and MnCo2O4 nanoparticles. Meanwhile, under the limitation of rigid carbon shell, the growth of MnCo2O4 nanoparticle is impeded. These make MnCo2O4@C excellent electrochemical properties, and endow rechargeable Zn-air battery with high open-circuit voltage of 1.43 V and long-term cycling performance over 70 h with high efficiency and stability. MnCo2O4@C holds great promise as highly active bifunctional electrocatalyst in the practical application of rechargeable metal-air batteries and other fuel cells.

Cobalt metalloid and polybenzoxazine derived composites for bifunctional oxygen electrocatalysis

The development of bifunctional oxygen electrodes is a key factor for the envisaged application of rechargeable metal-air batteries. In this work, we present a simple procedure based on pyrolysis of polybenzoxazine/metal metalloid nanoparticles composites into efficient bifunctional oxygen reduction and oxygen evolution electrocatalysts. This procedure generates nitrogen-doped carbon with embedded metal metalloid nanoparticles exhibiting high activity towards both, oxygen reduction and oxygen evolution, in 0.1 M KOH with a roundtrip voltage of as low as 0.81 V. Koutecký-Levich analysis coupled with scanning electrochemical microscopy reveals that oxygen is preferentially reduced in a 4e− transfer pathway to hydroxide rather than to hydrogen peroxide. Furthermore, the polybenzoxazine derived carbon matrix allows for stable catalyst fixation on the electrode surface, resulting in unattenuated activity during continuous alternate polarisation between oxygen evolution at 10 mA cm−2 and oxygen reduction at −1.0 mA cm−2.

Hierarchical Core-Shell Nickel Cobaltite Chestnut-like Structures as Bifunctional Electrocatalyst for Rechargeable Metal-Air Batteries.

Nano-engineered hierarchical core-shell nickel cobaltite chestnut-like structures were successfully synthesized as a bifunctionally active electrocatalyst for rechargeable metal-air battery applications. Both the morphology and composition of the catalyst were optimized by a facile hydrothermal reaction, resulting in a 10 h reacted sample demonstrating significantly enhanced activity toward both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in 0.1 m KOH. Specifically, the catalyst demonstrated -0.28 and 0.60 V versus SCE (saturated calomel electrode) at the ORR half-wave potential and an OER current density of 10 mA cm-2 , respectively. The resulting ORR/OER potential difference of 0.90 V was the smallest compared to the catalysts synthesized using 2, 6, and 12 h of hydrothermal reaction time. The excellent bifunctional activity of the catalyst is attributed to the nanoscale porous morphology and the spinel nickel cobaltite composition, which improved the active site exposure and transport of reactants and charges during the oxygen reactions.

Boosting Bifunctional Oxygen Electrocatalysis with 3D Graphene Aerogel-Supported Ni/MnO Particles.

Electrocatalysts for oxygen-reduction and oxygen-evolution reactions (ORR and OER) are crucial for metal-air batteries, where more costly Pt- and Ir/Ru-based materials are the benchmark catalysts for ORR and OER, respectively. Herein, for the first time Ni is combined with MnO species, and a 3D porous graphene aerogel-supported Ni/MnO (Ni-MnO/rGO aerogel) bifunctional catalyst is prepared via a facile and scalable hydrogel route. The synthetic strategy depends on the formation of a graphene oxide (GO) crosslinked poly(vinyl alcohol) hydrogel that allows for the efficient capture of highly active Ni/MnO particles after pyrolysis. Remarkably, the resulting Ni-MnO/rGO aerogels exhibit superior bifunctional catalytic performance for both ORR and OER in an alkaline electrolyte, which can compete with the previously reported bifunctional electrocatalysts. The MnO mainly contributes to the high activity for the ORR, while metallic Ni is responsible for the excellent OER activity. Moreover, such bifunctional catalyst can endow the homemade Zn-air battery with better power density, specific capacity, and cycling stability than mixed Pt/C + RuO2 catalysts, demonstrating its potential feasibility in practical application of rechargeable metal-air batteries.

Enhanced Electrocatalytic Performance of Self-supported AuCuCo for Oxygen Reduction and Evolution Reactions

The sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) have been one of the bottlenecks hindering the commercial application of rechargeable metal-air batteries. This report describes the viability of synthesis of self-supported Au-based alloy (AuCuCo) by a facile one-pot hydrothermal method and their use as highly efficient catalysts for ORR and OER. The obtained AuCuCo exhibits comparable electrocatalytic activity and better stability toward both the ORR and OER in alkaline media as compared with commercial Pt/C and IrO2/C catalyst. The improved electrocatalytic activity of AuCuCo is attributed to its unique three-dimensional nanostructure, the abundance of twin crystals, and change in the electronic structure of Au by alloying.

Ni-Fe Nitride Nanoplates on Nitrogen-Doped Graphene as a Synergistic Catalyst for Reversible Oxygen Evolution Reaction and Rechargeable Zn-Air Battery.

Obtaining bifunctional electrocatalysts with high activity for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is a main hurdle in the application of rechargeable metal-air batteries. Earth-abundant 3d transition metal-based catalysts have been developed for the OER and ORR; however, most of these are based on oxides, whose insulating nature strongly restricts their catalytic performance. This study describes a metallic Ni-Fe nitride/nitrogen-doped graphene hybrid in which 2D Ni-Fe nitride nanoplates are strongly coupled with the graphene support. Electronic structure of the Ni-Fe nitride is changed by hybridizing with the nitrogen-doped graphene. The unique heterostructure of this hybrid catalyst results in very high OER activity with the lowest onset overpotential (150 mV) reported, and good ORR activity comparable to that for commercial Pt/C. The high activity and durability of this bifunctional catalyst are also confirmed in rechargeable zinc-air batteries that are stable for 180 cycles with an overall overpotential of only 0.77 V at 10 mA-2 .

Self-assembled nitrogen-doped fullerenes and their catalysis for fuel cell and rechargeable metal-air battery applications.

In this study, we report self-assembled nitrogen-doped fullerenes (N-fullerene) as non-precious catalysts, which are active for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), and thus applicable for energy conversion and storage devices such as fuel cells and metal-air battery systems. We screen the best N-fullerene catalyst at the nitrogen doping level of 10 at%, not at the previously known doping level of 5 or 20 at% for graphene. We identify that the compressive surface strain induced by doped nitrogen plays a key role in the fine-tuning of catalytic activity.

Synergistic bifunctional catalyst design based on perovskite oxide nanoparticles and intertwined carbon nanotubes for rechargeable zinc-air battery applications.

Advanced morphology of intertwined core-corona structured bifunctional catalyst (IT-CCBC) is introduced where perovskite lanthanum nickel oxide nanoparticles (LaNiO3 NP) are encapsulated by high surface area network of nitrogen-doped carbon nanotubes (NCNT) to produce highly active and durable bifunctional catalyst for rechargeable metal-air battery applications. The unique composite morphology of IT-CCBC not only enhances the charge transport property by providing rapid electron-conduction pathway but also facilitates in diffusion of hydroxyl and oxygen reactants through the highly porous framework. Confirmed by electrochemical half-cell testing, IT-CCBC in fact exhibits very strong synergy between LaNiO3 NP and NCNT demonstrating bifunctionality with significantly improved catalytic activities of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Furthermore, when compared to the state-of-art catalysts, IT-CCBC outperforms Pt/C and Ir/C in terms of ORR and OER, respectively, and shows improved electrochemical stability compared to them after cycle degradation testing. The practicality of the catalyst is corroborated by testing in a realistic rechargeable zinc-air battery utilizing atmospheric air in ambient conditions, where IT-CCBC demonstrates superior charge and discharge voltages and long-term cycle stability with virtually no battery voltage fading. These improved electrochemical properties of the catalyst are attributed to the nanosized dimensions of LaNiO3 NP controlled by simple hydrothermal technique, which enables prolific growth of and encapsulation by highly porous NCNT network. The excellent electrochemical results presented in this study highlight IT-CCBC as highly efficient and commercially viable bifunctional catalyst for rechargeable metal-air battery applications.

Bi-Functional N-Doped CNT/Graphene Composite as Highly Active and Durable Electrocatalyst for Metal Air Battery Applications

Ethylene diamine-based nitrogen doped carbon nanotube (NCNT) was successfully synthesized on thermally reduced graphene oxide (TRGO) by an injection chemical vapor deposition method and its electrocatalytic activities for oxygen reduction and evolution reactions (ORR and OER, respectively) were investigated for metal air battery applications. The TRGO/NCNT composite with a novel bridged planes morphology does not only exhibits ORR performance similar to that of commercial Pt/C catalyst, but also demonstrates a superior OER activity. Furthermore, the composite exhibits an excellent electrochemical durability confirmed by full range cyclic voltammetry (CV) cycling. This study highlights an approach to prepare highly active and durable metal free catalysts as a highly efficient electrode material for rechargeable metal air battery applications.

Sm0.5Sr0.5CoO3−δ – A new bi-functional catalyst for rechargeable metal-air battery applications

Sm0.5Sr0.5CoO3−δ (SSC) was evaluated as a bi-functional catalyst for rechargeable metal-air battery cathodes. The catalyst was homogenously dispersed on corrosion-resistant graphitized Vulcan XC-72R carbon powder for the cathode fabrication. For comparison, the air cathode catalyzed with the widely studied perovskite La0.6Ca0.4CoO3 (LCC) was included in the evaluation. Based on the polarization curves, SSC exhibited similar catalytic activities as LCC for both oxygen evolution reaction and oxygen reduction reaction. Furthermore, the air cathode prepared with SSC exhibited an improved cyclic life. These results suggest that SSC is a promising alternative to LCC as a bi-functional catalyst for metal-air battery cathode applications.