Electrocatalysts For Zinc-air Batteries Research Articles

Cold-plasma activation converting conductive agent in spent Li-ion batteries to bifunctional oxygen reduction/evolution electrocatalyst for zinc-air batteries

Considerable amount of high-value transition metals components can be recycled in spent ternary lithium-ion batteries. In this study, we utilized the conductive agent carbon black, obtained from the leaching waste resulting from the chemical recovery of spent lithium-nickel-manganese-cobalt (NCM) oxide cathode materials. This process allows us to create valuable bifunctional catalysts for the oxygen reduction reaction and oxygen evolution reaction (ORR/OER), facilitated by a facile cold plasma activation method, as a part of lithium batteries circular economy. The activated conductive agent (RCA-30) exhibited an ORR half-wave potential of 0.74 V (vs. RHE) in 0.1 mol/L KOH solution, and an OER overpotential of 360 mV at 10 mA cm-2 in 1 mol/L KOH electrolyte, owing to nitrogen doping of carbon black and activation of surface metal oxides. The complete zinc-air batteries incorporating the activated catalysts at the cathode exhibited an open circuit potential of up to 1.48 V and sustained cycling for 100 h at a current density of 5 mA cm-2. Additionally, the activated catalysts contributed to a power density of 92 mW cm-2 and a full discharge capacity of 640 mAh/g.

Metal oxide Perovskite-Carbon composites as electrocatalysts for zinc-air batteries. Optimization of ball-milling mixing parameters

Zn-air batteries (ZABs) are promising electrochemical devices to store energy. Metal oxide perovskites mixed with carbon materials are highlighted as interesting materials for this application because of their appropriate bifunctional performance in oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The interaction between both components of the electrocatalyst is important in the bifunctional electrocatalytic activity, and the mixing method plays an important role in this interaction. Then, different mixing methods have been studied in this work (ball-milling, mortar and manual shaking). The use of different physicochemical techniques such as temperature programmed desorption (TPD), temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS) in the materials characterization, allows us to conclude that the mixing method strongly influences the particle size and the interaction between both components, which determine the final electrocatalytic activity. The materials prepared by ball-milling displayed the best performance. Herein, the experimental conditions were optimized to obtain electrocatalysts with enhanced electrocatalytic activity for ORR and OER. Low rotating speed, air atmosphere and low ball-milling time generate electrocatalysts with a small nanoparticle size, more homogeneous and with a higher interaction between both components, which enhances electron transfer, and consequently, the overall oxygen-involved reactions. The best electrocatalyst obtained was studied as air-electrode in a Zn-air battery and it was compared to a commercial Pt/C electrocatalyst, obtaining higher cyclability (55.2 vs 51.7 %) for 30 h, and higher energy density at 5 mA/cm2 (764 mAh/g vs 741 mAh/g).

Feco Nanoalloys Encapsulated in Pod-Like N-Doped Carbon Nanotubes as Efficient Oxygen Reduction Reaction Electrocatalysts for Zinc-Air Batteries

Feco Nanoalloys Encapsulated in Pod-Like N-Doped Carbon Nanotubes as Efficient Oxygen Reduction Reaction Electrocatalysts for Zinc-Air Batteries

Fabrication of CoMN2O4 loaded nitrogen-doped graphene as bifunctional electrocatalyst for rechargeable zinc-air batteries

Designing durable and low-cost electrocatalysts for zinc-air batteries is critical, which plays an essential role in oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this paper, the CoMn2O4/N-RGO bifunctional electrocatalyst was synthesized by a facile hydrothermal method. The electrocatalytic performance was tested toward ORR and OER under alkaline condition (0.1[Formula: see text]M KOH). The XRD, SEM and other characterization analyses were used to investigate the physicochemical properties of materials. The results showed that the electrochemical activity of CoMn2O4/N-RGO showed high power density (354[Formula: see text]mW[Formula: see text]cm[Formula: see text], small charge/discharge voltage drop (0.70[Formula: see text]V) and excellent stability cycle (200[Formula: see text]h), which are superior to the noble metal Pt/C+IrO2 electrocatalyst (the voltage drop: 0.60[Formula: see text]V at initial and 0.85[Formula: see text]V after 13[Formula: see text]h). This work provided a new method for developing the bifunctional material in zinc-air batteries.

Fe-N-C combined with Fe100-x-y-zPxOyNz porous hollow spheres on a phosphoric acid group-rich N-doped carbon as an electrocatalyst for zinc-air battery

Replacing the commercial Pt/C with non-precious metal-based electrocatalysts in the proton exchange membrane fuel cells and metal-air batteries is still challenging. Herein, an electrocatalyst (described as Fe-N-C/Fe100-x-y-zPxOyNz/NPC, NPC is N, P co-doped carbon) composed of multiple active components, such as NPC, iron-based porous hollow spheres and Fe-N-C, is reported, which exhibits an excellent activity that is comparable to state-of-the-art Pt/C for half-cell and full zinc-air battery in alkaline media. This catalyst exhibits an excellent activity with a half-wave potential of 0.86 V for the ORR in alkaline media, which is 10 mV more positive than to that of Pt/C (0.85 V), and a gravimetric energy density for zinc-air battery is up to 675 Wh Kgzn−1. The excellent activity is attributed to the synergetic effect of active NPC, iron-based porous hollow spheres (Fe100-x-y-zPxOyNz) and Fe-N-C in its structure. In addition, phosphoric acid groups are partially remained in the structure for our catalyst that make the catalyst excellent hydrophilicity. This work adds a new member into family of non-precious metal-based ORR electrocatalysts.

Hydrophobic 3D Fe/N/S doped graphene network as oxygen electrocatalyst to achieve unique performance of zinc-air battery

Electrocatalysts’ activity in oxygen reduction reaction can be regarded as crucial indicator for their expected performance in metal-air battery, where catalyst selection is limited by low conductivity and insufficient electrochemical activity of available materials. This drawback could be addressed by the development of three-dimensional (3D) hierarchically structured carbon. In this study, hydrophobic 3D Fe/N/S doped graphene network is synthesized as electrocatalysts for zinc-air batteries in molten mixed salts (NaCl/FeCl2). It was observed that NaCl could seal maximum possible quantity of N in 3D-N/S. This is accompanied by more pyridinic-N and graphitic-N groups being tailor made in 3D-Fe/N/S. When assembled as air breathing cathodes in zinc-air batteries, 3D-Fe/N/S material demonstrated open-circuit potential (OCP) of 1.507 V, which was more than 1.492 V in case of 3D-N/S and 1.489 V of 20% Pt/C. Similar pattern occurred at discharge current density 50 mA cm−2 where a discharge voltage of 1.079 V observed in 3D-Fe/N/S was higher than 1.043 V of Pt/C and 1.040 V of 3D-N/S. Corresponding discharge power density maintained the same order, 3D-Fe/N/S (53.929 mW cm−2) > Pt/C (52.158 mW cm−2) > 3D-N/S (52.002 mW cm−2), rendering hydrophobic FeNx and N/S doped 3D-Fe/N/S better zinc-air battery electrode material than 20% Pt/C.

Embedding FeSb alloy nanoparticles in N-doped carbon layers as an efficient bifunctional electrocatalyst for zinc-air battery

Due to the intrinsic sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), developing highly efficient and inexpensive bifunctional electrocatalysts are crucial for high-performance zinc-air battery. In this paper, a series of hybrid electrocatalysts by embedding FeSb alloy nanoparticles in nitrogen-doped carbon layers (FeSb-N-CLs) have been prepared by a facile pyrolysis of solid-phase precursor. The optimized FeSb-N-CLs-50 cathode catalyst exhibits excellent activity and stability to the ORR and OER in alkaline medium, which can be competitive with commercial Pt/C catalyst (20%). More importantly, the good performance and high stability of the primary and rechargeable zinc-air batteries employing FeSb-N-CLs-50 as cathodes further demonstrate this hybrid catalyst is a favorable and promising candidate to replace noble metal-based catalysts for the application in zinc-air batteries.

Highly durable and active non-precious air cathode catalyst for zinc air battery

The electrochemical stability of non-precious FeCo-EDA and commercial Pt/C cathode catalysts for zinc air battery have been compared using accelerated degradation test (ADT) in alkaline condition. Outstanding oxygen reduction reaction (ORR) stability of the FeCo-EDA catalyst was observed compared with the commercial Pt/C catalyst. The FeCo-EDA catalyst retained 80% of the initial mass activity for ORR whereas the commercial Pt/C catalyst retained only 32% of the initial mass activity after ADT. Additionally, the FeCo-EDA catalyst exhibited a nearly three times higher mass activity compared to that of the commercial Pt/C catalyst after ADT. Furthermore, single cell test of the FeCo-EDA and Pt/C catalysts was performed where both catalysts exhibited pseudolinear behaviour in the 12–500 mA cm −2 range. In addition, 67% higher peak power density was observed from the FeCo-EDA catalyst compared with commercial Pt/C. Based on the half cell and single cell tests the non-precious FeCo-EDA catalyst is a very promising ORR electrocatalyst for zinc air battery.