Rechargeable Zinc–Air Batteries with Seawater Electrolyte and Cranberry Bean Shell-Derived Carbon Electrocatalyst

Abstract

Zinc–air batteries with seawater electrolyte utilize abundant and cheap resources. However, it requires an electrocatalyst with high bifunctional activity in seawater. In this work, a carbon electrocatalyst is obtained via one-step pyrolysis of the shell waste of cranberry beans. During the oxygen reduction reaction (ORR) in seawater electrolyte, the cranberry bean shell-derived carbon catalyst exhibits an ORR onset potential of 0.69 V vs RHE and an ORR saturating current density of 2.93 mA cm–2, which are promising compared to the ORR performance of Pt/C in seawater electrolyte (0.78 V vs RHE and 3.15 mA cm–2). During OER (oxygen evolution reaction) in seawater electrolyte, the carbon catalyst shows an overpotential of 582 mV at 5 mA cm–2, 35 mV smaller than the commercial Ir/C catalyst (617 mV). Furthermore, when the catalyst is applied to the zinc–air battery with seawater electrolyte, the cell is able to exhibit discharge and charge voltages of 0.93 and 2.2 V, respectively, which are stable for more than 120 cycles of the cycling test. This work highlights the fabrication of metal–air batteries with cost-effective and sustainable resources.

Nanostructured Ball-Milled Ni–Co–Mn Oxides from Spent Li-Ion Batteries as Electrocatalysts for Oxygen Evolution Reaction

“…The lower catalytic performance of Ni–Co–Mn oxides might be due to the Mn 3+ sites that suffer from disproportionation in neutral conditions . The potential of the catalysts to work in neutral medium would enable them to realize devices with nonhazardous systems …”

“…61 The potential of the catalysts to work in neutral medium would enable them to realize devices with nonhazardous systems. 62 Multiple phases of the trimetallic oxide in the sample provide multiple metal cations, leading to various oxidation state possibilities. 52 For instance, Co 2+ molecules in spinel MnCo 2 O 4 serve as the main active sites that are responsible of −OOH formation during OER.…”

Cobalt Nanoparticles Encapsulated with N-Doped Bamboo-Like Carbon Nanofibers as Bifunctional Catalysts for Oxygen Reduction/Evolution Reactions in a Wide pH Range

“…A Zn–air device with 6 M KOH + 0.15 M ZnO and 4 M NH 4 Cl + 2 M KCl electrolytes, corresponding to alkaline-ZAB and neutral-ZAB, was used to measure the battery’s performance. The preparation of catalyst ink and air-cathode was similar to the previous study . A mixed catalyst of Pt/C and Ir/C (1:1 w/w) with the same loading mass was used as the benchmark.…”

“…The preparation of catalyst ink and air-cathode was similar to the previous study. 32 A mixed catalyst of Pt/C and Ir/C (1:1 w/w) with the same loading mass was used as the benchmark. A PGSTAT302N potentiostat was used to measure the galvanodynamic discharge−charge test in which power density was determined from the discharging curve.…”

Advances and Perspective of Noble-Metal-Free Nitrogen-Doped Carbon for pH-Universal Oxygen Reduction Reaction Catalysts

“…Followed by a successful improvement of ORR activity and stability of macrocyclic compounds using heat treatment, many studies have focused on developing Pt-free electrocatalysts within the past decade. − Among the Pt-free electrocatalysts, noble-metal-free nitrogen-doped carbon (M-N/C with M = Ni, Co, Mn, Fe) has drawn massive attention by virtue of its earth abundance, tunable electronic structure, high surface area, and tailored chemical composition, which improve the corresponding ORR activity. − In alkaline conditions, most of these M-N/C electrocatalysts have exhibited comparable ORR performance to Pt-based electrocatalysts . Nevertheless, their activities in neutral and acidic conditions are still insufficient, thus limiting their application in electrochemical-based devices that require acidic and neutral environments. − …”