Iron, Cobalt, and Nickel Phthalocyanine Tri-Doped Electrospun Carbon Nanofibre-Based Catalyst for Rechargeable Zinc-Air Battery Air Electrode.

The goal of achieving the large-scale production of zero-emission vehicles by 2035 will create high expectations for electric vehicle (EV) development and availability. Currently, a major problem is the lack of suitable batteries and battery materials in large quantities. The rechargeable zinc-air battery (RZAB) is a promising energy-storage technology for EVs due to the environmental friendliness and low production cost. Herein, iron, cobalt, and nickel phthalocyanine tri-doped electrospun carbon nanofibre-based (FeCoNi-CNF) catalyst material is presented as an affordable and promising alternative to Pt-group metal (PGM)-based catalyst. The FeCoNi-CNF-coated glassy carbon electrode showed an oxygen reduction reaction/oxygen evolution reaction reversibility of 0.89 V in 0.1 M KOH solution. In RZAB, the maximum discharge power density (Pmax) of 120 mW cm-2 was obtained with FeCoNi-CNF, which is 86% of the Pmax measured with the PGM-based catalyst. Furthermore, during the RZAB charge-discharge cycling, the FeCoNi-CNF air electrode was found to be superior to the commercial PGM electrocatalyst in terms of operational durability and at least two times higher total life-time.

One-dimensional polymer-derived ceramic nanowires with electrocatalytically active metallic silicide tips as cathode catalysts for Zn-air batteries.

New metallic nickel/cobalt/iron silicide droplets at the tips of polymer-derived ceramic (PDC) nanowires have been identified as stable and efficient cathode catalysts for Zn-air batteries. The as-prepared catalyst having a unique one-dimensional (1D) PDC nanowire structure with the presence of metallic silicide tips of 1D-PDC plays a crucial role in facilitating oxygen reduction/evolution reaction kinetics. The Zn-air battery was designed using Ni/PDC, Co/PDC and Fe/PDC as air electrode catalysts. In electrochemical half-cell tests, it was observed that the catalysts have a good bifunctional electrocatalytic activity. The efficiency of the catalysts to function as a cathode catalyst in real-time primary and mechanically rechargeable Zn-air battery configurations was determined. The primary battery testing results revealed that Ni/PDC and Co/PDC exhibited a stable discharge voltage plateau up to 29 h. The Fe/PDC sample, on the other hand, performed up to 23 h with an operating potential of 1.20 V at the discharge current density of 5 mA cm-2 after which the battery ceased to perform. The Ni/PDC, Co/PDC, and Fe/PDC cathode catalysts performed galvanostatic 1200 charge-discharge cycles in a mechanically rechargeable secondary Zn-air battery configuration. The results demonstrate that the Ni/PDC, Co/PDC, and Fe/PDC materials serve as excellent and durable bifunctional cathode electrocatalysts for Zn-air batteries.

A new silicon oxycarbide based gas diffusion layer for zinc-air batteries.

Rational material designs play a vital role in the gas diffusion layer (GDL) by increasing the oxygen diffusion rate and, consequently, facilitating a longer cycle life for metal-air batteries. In this work, a new porous conductive ceramic membrane has been developed as a cathodic GDL for zinc-air battery (ZAB). The bilayered structure with a thickness of 390 µm and an open porosity of 55% is derived from a preceramic precursor with the help of the freeze tape casting technique. The hydrophobic behaviour of the GDL is proved by the water contact angle of 137.5° after the coating of polytetrafluoroethylene (PTFE). The electrical conductivity of 5.59 * 10-3 S/cm is reached using graphite and MWCNT as filler materials. Tested in a ZAB system, the as-prepared GDL coated with commercial Pt-Ru/C catalyst shows an excellent cycle life over 200 cycles and complete discharge over 48 h by consuming oxygen from the atmosphere, which is comparable to commercial electrodes. The as-prepared electrode exhibits excellent ZAB performance due to the symmetric sponge-like structure, which facilitates the oxygen exchange rate and offers a short path for the oxygen ion/-electron kinetics. Thus, this work highlights the importance of a simple manufacturing process that significantly influences advanced ZAB enhancement.

Polysiloxane microspheres encapsulated in carbon allotropes: A promising material for supercapacitor and carbon dioxide capture.

Recently, hierarchical porous materials have received tremendous attention in electrochemical supercapacitors and CO2 adsorption. Both areas of application have a positive impact on global warming by reducing CO2 emissions to the atmosphere. Herein, we synthesized new silica-based ceramic monoliths composed of polysiloxane microspheres sheathed by carbon allotropes (Graphene or MWCNT) and metal nanoparticles. The as-synthesized hybrid ceramics show a high specific surface area of 540 m2 g-1 with hierarchical micro-/meso-/macroporous structures. With the structural benefits, the obtained ceramics exhibits excellent performance in supercapacitors and for CO2 adsorption as probed in this study. As an electrode material for supercapacitor, the hybrid ceramics delivered the specific capacitance of 93 F/g at 2 mV s-1 in 0.5 M KOH electrolyte solution with a capacity retention of 88% after 50 cycles. Further, as a solid adsorbent, the hybrid ceramics shows the maximum CO2 adsorption capacity of 2 mmol g-1 at 100 kPa equilibrium pressure and 303 K, while maintaining 98% capacity retention after 10 cycles. Thus, the hybrid ceramics with its unusual properties make them a promising candidate for both, supercapacitors and CO2 capture in the sheer physical adsorption process.

Ultrasonochemically-induced MnCo2O4 nanospheres synergized with graphene sheet as a non-precious bi-functional cathode catalyst for rechargeable zinc-air battery.

Rechargeable zinc-air batteries are considered to be more sustainable and efficient candidates for safe, low-cost energy storage because of their higher energy density and the abundance of zinc resources. Recently Zn-air batteries have aroused significant research attention, however, because an unresolved impediment due to the notorious instability of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) kinetics of the cathode catalyst limit their practical application. Herein, we report the synthesis of non-precious MnCo2O4 nanospheres synergized with a graphene sheet as a bi-functional cathode catalyst for rechargeable Zn-air battery application using a one-pot probe sonochemical method. Structural characterization confirms that the MnCo2O4 nanospheres successfully anchored on graphene sheet. X-ray photoelectron spectroscopy revealed that the Mn and Co in the MnCo2O4 are in mixed valence states on the graphene sheet surface and the MnCo2O4-graphene sheet (MCO-GS) hybrid catalyst exhibits excellent OER and ORR activity compared with their individual counterparts. A rechargeable Zn-air battery using an MCO-GS catalyst reveals unique small charge-discharge overpotential, cycling stability and higher rate capability than a bare MnCo2O4 (MCO) catalyst. This superiority in electrocatalytic activity combined with simplicity of material synthesis, turn the MCO-GS hybrid into a promising catalyst for a rechargeable Zn-air battery.

Chrysanthemum flower-like NiCo2O4-nitrogen doped graphene oxide composite: an efficient electrocatalyst for lithium-oxygen and zinc-air batteries.

Chrysanthemum flower-like NiCo2O4-nitrogen doped graphene oxide composite material has been explored as a bifunctional cathode electrocatalyst for aqueous zinc-air and non-aqueous lithium-oxygen batteries. This cathode exhibits maximum discharge capacities of 712 and 15 046 mA h g-1 for zinc-air and lithium-oxygen batteries, respectively, with stable cycling over 50 cycles.