Sequentially Electrodeposited MnO_X/Co-Fe as Bifunctional Electrocatalysts for Rechargeable Zinc-Air Batteries

Abstract

Manganese oxide (MnOx) and cobalt-iron (Co-Fe) were sequentially electrodeposited onto a gas diffusion layer (GDL) as bifunctional electrocatalysts for rechargeable zinc-air batteries. The fabricated material was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The sequentially deposited MnOx/Co-Fe catalysts, tested using cyclic voltammetry (CV), showed activity for both the oxygen reduction and oxygen evolution reactions (ORR and OER), with better performance than either MnOx or Co-Fe alone. The fabricated material was assembled into a zinc-air battery as the air electrode component for battery cycling tests. The zinc-air battery using MnOx/Co-Fe catalysts exhibited good discharge-recharge performance and a cycling efficiency of 59.6% at 5 mA cm −2 , which is comparable to Pt/C catalysts. In addition, the electrodeposited MnOx/Co-Fe layer showed strong adhesion to the gas diffusion layer (GDL) and was structurally stable throughout 40 h of battery cycling.

Recent Advances in Carbon‐Based Bifunctional Oxygen Electrocatalysts for Zn−Air Batteries

“…also reported a N‐doped carbon nanotube aerogels coupled Ni/NiO/NiCo 2 O 4 as a highly‐active and stable air‐cathode for Zn−air batteries via a facile alginate‐derived biomass conversion strategy, in which Ni, NiO, and NiCo 2 O 4 provide ternary catalytic centers and 3D porous carbon aerogels facilitate electrons conduction/transfer. Apart from the above reported metal (Ni, Co)‐metal oxides/C materials, other mixed oxide/metal (alloy)/carbon materials, such as Co−CoO x /C,,, Ni−NiO x /C, MnO x −CoFe/C, Co 3 O 4 −Co/CoFe/C, Cu@NCNT/Co x O y and Co/CoFe 2 O 4 /graphene, are also widely applied as bifunctional electrocatalysts for rechargeable Zn−air batteries. More recently, our group has demonstrated boosting bifunctional oxygen electrocatalysis of 3D porous graphene aerogels‐supported Ni/MnO particles (Ni−MnO/rGO aerogels) .…”

A Gas Diffusion Layer Impregnated with Mn3O4‐Decorated N‐Doped Carbon Nanotubes for the Oxygen Reduction Reaction in Zinc‐Air Batteries

“…Zn‐air batteries (ZABs) have garnered recent interest for energy storage battery technology as they have high theoretical energy densities, minimal safety concerns, and low environmental impact relative to other battery types . However, the slow kinetics of the oxygen reduction and oxygen evolution reactions (ORR and OER) result in energy losses and comparably low efficiencies . Commonly, precious metals such as Pt, Ru, Ir, and their oxides have been used as catalysts to enhance the kinetics of the ORR and OER but suffer from high cost and poor stability during cycling .…”

Effects of Crosslinker Concentration in Poly(Acrylic Acid)‐KOH Gel Electrolyte on Performance of Zinc‐Air Batteries

“…Sequentially electrodeposited MnO x /Co−Fe on GDL was utilized as the bifunctional air electrode; MnO x provides ORR activity, while Co−Fe provides OER activity. Details regarding fabrication and characterization of the catalysts can be found in the literature . Briefly, electrodeposition of catalysts was performed at 40 °C in a two‐electrode cell where GDL and Pt mesh were used as working and counter electrodes, respectively.…”

“…The optimal concentration of crosslinker (N,N′‐methylenebis(acrylamide) or MBAA) was affected by the characteristics of the Ni current collector, specifically, a less porous Ni foam structure inhibits PAA‐KOH penetration, while a more porous structure facilitates penetration and increases water evaporation from the PAA‐KOH . For a bi‐electrode design, the most frequently used material to support bifunctional catalysts is a Teflon‐coated carbon paper, known as a gas diffusion layer (GDL) . Unlike Ni foam, GDL combines characteristics such as porosity (to allow access to oxygen gas) and hydrophobicity (to prevent flooding of aqueous electrolytes).…”