Ternary Spinel MCo₂O₄ (M = Mn, Fe, Ni, and Zn) Porous Nanorods as Bifunctional Cathode Materials for Lithium–O₂ Batteries

Abstract

The development of Li-O2 battery electrocatalysts has been extensively explored recently. The Co3O4 oxide has attracted much attention because of its bifunctional activity and high abundance. In the present study, toxic Co(2+) has been replaced through the substitution on the tetrahedral spinel A site ions with environmental friendly metals (Mn(2+), Fe(2+), Ni(2+), and Zn(2+)), and porous nanorod structure are formed. Among these spinel MCo2O4 cathodes, the FeCo2O4 surface has the highest Co(3+) ratio. Thus, oxygen can be easily adsorbed onto the active sites. In addition, Fe(2+) in the tetrahedral site can easily release electrons to reduce oxygen and oxidize to half electron filled Fe(3+). The FeCo2O4 cathode exhibits the highest discharging plateau and lowest charging plateau as shown by the charge-discharge profile. Moreover, the porous FeCo2O4 nanorods can also facilitate achieving high capacity and good cycling performance, which are beneficial for O2 diffusion channels and Li2O2 formation/decomposition pathways.

Metal‐Organic‐Framework‐Derived MCo2O4 (M=Mn and Zn) Nanosheet Arrays on Carbon Cloth as Integrated Anodes for Energy Storage Applications

“…No second phases, such as Mn 3 O 4 were observed, suggesting that the materials prepared are pure Co‐based spinel metal oxides. This is in consistent with the results of previous reports . Figures d–e depicted the TEM image of a single MnCo 2 O 4 nanosheet, composed of many interconnected nanoparticles with diameters of ≈10 nm.…”

Recycling of Li−Ni−Mn−Co Hydroxide from Spent Batteries to Produce High‐Performance Supercapacitors with Exceptional Stability

“…Furthermore, intense satellite peaks (marked as Sat.) were observed, indicating that Ni (II) is the predominant oxidation state . The Co 2p spectrum (Figure d) can be deconvoluted into two spin‐orbit doublets and two shake‐up satellite peaks.…”

Synthesis of graphene–transition metal oxide hybrid nanoparticles and their application in various fields

“…MnCo 2 O 4 –graphene has been used as a LiO 2 battery cathode [295], an oxygen reduction electrocatalyst [29], and in reducing fire hazards of poly(butylene terephthalate) [296]. Mohamed et al have studied the influence of Co 2+ replacement in the Co 3 O 4 matrix by M 2+ (where M = Mn, Fe, Ni, Zn) for increasing the catalytic performance [297]. For the synthesis of the hybrid, they mainly use hydrothermal methods.…”