Three-Dimensional-Order Macroporous AB₂O₄ Spinels (A, B =Co and Mn) as Electrodes in Zn–Air Batteries

Abstract

In this work, atomically substituted three-dimensionally ordered macroporous (3DOM) spinels based on Co and Mn (MnCo2O4 and CoMn2O4) were synthetized and used as cathodic electrocatalysts in a primary Zn–air battery. Scanning/transmission electron microscopy images show a 3DOM structure for both materials. Skeleton sizes of 114.4 and 140.8 nm and surface areas of 65.3 and 74.6 m2 g–1 were found for MnCo2O4 and CoMn2O4, respectively. The increase in surface area and higher presence of Mn3+ and Mn4+ species in the CoMn2O4 3DOM material improved battery performance with a maximum power density of 101.6 mW cm–2 and a specific capacity of 1440 mA h g–1, which shows the highest battery performance reported to date using similar spinel materials. The stability performance of the electrocatalyst was evaluated in half-cell and battery cell systems, showing the higher durability of CoMn2O4, which was related to its better capability to perform the electrocatalytic process as adsorption, electron transfer, and desorption. It was found through density functional theory calculations that the CoMn2O4 spinel has a higher density of states in the Fermi level vicinity and better conductivity. Finally, the unique shape of 3DOM spinels promoted a high interaction between electroactive species and catalytic sites, making them suitable for oxygen reduction reaction applications.

Air Electrodes for Flexible and Rechargeable Zn−Air Batteries

“…[ 62 ] Cobalt oxide modified by manganese oxide was proposed to improve the intrinsic conductivity and catalytic activity due to their higher density of states (DOS) in the Fermi‐level vicinity based on the DFT calculation. [ 63,64 ]…”

In Situ Grown CoMn2O4 3D‐Tetragons on Carbon Cloth: Flexible Electrodes for Efficient Rechargeable Zinc–Air Battery Powered Water Splitting Systems

“…Figure 4f shows that the OER activity of the CMO-U@CC electrode was superior to those of many outstanding oxide-based electrocatalysts. [19,[40][41][42]45,48,49,[66][67][68][85][86][87] After testing the OER activity, CMO-U@CC was characterized via XPS, XRD, and FESEM analysis (Figure S8a-c, Supporting Information). The XPS characteristic peaks of Co 2p and Mn 2p shifted to higher oxidation states compared with those of CMO-U@CC before OER because of the surface oxidation.…”

“…[1][2][3] Further, electrochemical reactions involving the performance of the cobalt-manganese electrocatalyst. [19] However, their poor conductivities, sluggish kinetics, limited catalytic active sites, as well as their inadequate ability to adsorb reactants, have restricted their ECS applications. [20][21][22] Nevertheless, their electrocatalytic activities can be enhanced by tuning their morphologies, thereby exposing sufficient active sites for mass and charge transfers at the electrode-electrolyte interfaces.…”

“…[29][30][31][32][33][34][35][36][37][38][39] Moreover, this decoration can prevent the aggregation and leaching of the powder electrocatalyst from its substrate in liquid electrolytes during reactions, thus enhancing the electronic coupling between the electrocatalyst and substrate. Although there are many methods for synthesizing CoMn 2 O 4 for ECS applications, [19,20,[40][41][42][43][44][45][46][47][48][49][50] a few studies have attempted to specifically obtain surfactant, binder-free flexible electrodes.…”

Mn-Ni-Co-O Spinel Oxides towards Oxygen Reduction Reaction in Alkaline Medium: Mn0.5Ni0.5Co2O4/C Synergism and Cooperation

“…In alkaline conditions, the cobaltite-based spinel oxides, MCo 2 O 4 (where M = Mn, Ni, Cu, Fe), are very promising ORR electrocatalysts [22][23][24]. Merabet et al [25] used the hydrothermal method to synthesize the crystalline MnCo 2 O 4 spinel with a catalytic activity superior to Co 3 O 4 .…”