An Exceptionally Facile Synthesis of Highly Efficient Oxygen Evolution Electrodes for Zinc‐Oxygen Batteries

Abstract

Zinc‐oxygen batteries are promising candidates for electrical vehicles and electric grid energy storage due to their low cost, high safety levels, and low environmental impact. The oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) represent the most significant processes in zinc‐oxygen batteries. The development of nonprecious metal catalysts for OER with satisfactory performances and low cost (especially prepared by a straightforward synthesis route), still poses a significant challenge. Herein, we report an exceptionally facile and easily scalable method to produce NiFe layered double hydroxide (LDH) coated nickel foam by immersing nickel foams into aqueous solutions containing NiCl2 and FeCl2 and keeping them standing for a certain period of time. Without any other complicated technique or organic reagent, microflower‐shaped NiFe LDHs can be obtained. The resulting electrode shows excellent OER performance with a low overpotential of 210 mV at a 10 mA cm−2 constant current polarization and stable operation for more than 100 charge‐discharge cycles in zinc‐oxygen batteries.

Reducing the Cost of Zinc–Oxygen Batteries by Oxygen Recycling

“…Fabrication of the zinc-oxygen battery Thez inc-oxygen battery was fabricated with copper foam as the current collector of the negative electrode,N iFel ayered double hydroxide coated nickel foam (NiFe-LDH/NF;adetailed method was reported in Ref. [22]) as the OER electrode in the charge process,a nd ac ommercially available air electrode (MetAir ,Q uantumSphere) as the ORR electrode in the discharge process.A na queous solution of 8.5 mol L À1 KOHc ontaining 1.0 mol L À1 ZnO was used as the electrolyte.T he relative position of these three electrodes was ORR-Zn-OER to reduce the polarization in the discharge process.T he effective area of the copper foam was 5cm 5cm, whereas the areas of the ORR and OER electrodes were designed to be slightly larger (6 cm 6cm) and smaller (4 cm 4cm) than that of the copper foam to eliminate zinc accumulation during the cyclic test.…”

“…[b] This price is estimated from Ref. . [c] Price of Cu foam (780 g m −2 ) is estimated based on the price of Ni foam ($ 12 m −2 @320 g m −2 ) and raw materials ($ 6.9 kg −1 for Cu and $ 11.1 kg −1 for Ni).…”

“…The zinc–oxygen battery was fabricated with copper foam as the current collector of the negative electrode, NiFe layered double hydroxide coated nickel foam (NiFe‐LDH/NF; a detailed method was reported in Ref. ) as the OER electrode in the charge process, and a commercially available air electrode (MetAir®, QuantumSphere) as the ORR electrode in the discharge process. An aqueous solution of 8.5 mol L −1 KOH containing 1.0 mol L −1 ZnO was used as the electrolyte.…”

“…[21] However, zinc-air/oxygen batteries with high cyclic performance and energy efficiencya re still full of challenges.In our recent studies,w ep roposed an effective three-electrode zinc-air/oxygen battery with separate ORR and oxygene volutionr eaction (OER) electrodes to avoid corrosion of the ORR electrode. [22] With intentional arrangement of the positions and areas of these three electrodes,the cyclic performance can be greatly extended.To further improve the cyclic performancea nd energy efficiencyofzinc-air/oxygen batteries, oxygen should be used instead of air to achieve ah igher discharge voltage and eliminate the formationo fc arbonates.U nfortunately,o xygeni s too expensive for energy-storage systems in whichc ost is a vital factor. Theo xygen dosagef or a1 0MWh zinc-oxygen energy-storages ystem is around 2100 Nm 3 day À1 (1 cycle per day), at which the pressures wing adsorption (PSA) oxygen generator becomes the most efficient oxygens upply method of suitable scale and lowest cost.…”

A Review of Precious‐Metal‐Free Bifunctional Oxygen Electrocatalysts: Rational Design and Applications in Zn−Air Batteries

“…Through surface modification process like plasma etching, H 2 etching, or NH 3 treatment, active graphene nanosheets can be in situ generated on the surface of carbon fibers, strongly coupled with the freestanding skeleton via chemical bond connection. For transition‐metal‐based catalysts, the active materials can be deposited on metal foams, especially Ni foams, to fabricate freestanding oxygen electrodes . The rapid electron transfer at interfaces can be achieved through effective connection between active sites and conductive substrates.…”