Entropy Stabilized Oxide Nanocrystals as Reaction Promoters in Lithium‐O₂ Batteries

Abstract

Charge transport limitations at the Li2O2 discharge product‐electrode interfaces hinder the rechargeability of Li−O2 batteries. Herein, we introduce entropy stabilized oxides (ESO) as reaction ′promoters′ in positive electrodes that can facilitate charge transport by reducing the binding energy of the intermediates. In this work, we developed a rock‐salt type entropy stabilized oxide. We show that the rock salt phase transforms into a pure, equimolar, quinary spinel on heat treatment. A Li−O2 battery with the developed ESOs at the positive electrode is cycled with an areal capacity of 1 mAh cm−2 at a current rate of 0.25 mA cm−2 to study its role as a reaction promoter. The surface, bulk, and morphological characterization are carried out for both materials. The presence of multiple cations and defects on the surface of the ESO is found to benefit the discharge product oxidation and improve the cyclic stability.

High Entropy Materials for Reversible Electrochemical Energy Storage Systems

“…Hegde et al introduced a new type of entropy stabilized oxide as "promoters" in the positive electrode of a Li-O 2 battery. [95] These promoters are designed to enhance charge transport by reducing the binding energy of intermediates in the battery reaction shown in Figure 9c i. The researchers conducted cycling tests on a Li-O 2 battery with the developed entropy stabilized oxide at the positive electrode.…”

“…Hegde et al. introduced a new type of entropy stabilized oxide as “promoters” in the positive electrode of a Li‐O 2 battery [95] . These promoters are designed to enhance charge transport by reducing the binding energy of intermediates in the battery reaction shown in Figure 9c i.…”

Elevating Lithium‐Sulfur Battery Durability through Samarium Oxide/Ketjen Black Modified Separator

“…The polar nature of the ions between the rare earth metal ions and oxygen ions in the rare earth metal oxides polarizes the material in the electric field and produces a polarity effect. At the same time, the oxygen ions have a higher electronegativity while the rare earth metal ions have a lower electronegativity [18] . This electronegativity difference results in a negative charge for the oxygen ions and a positive charge for the rare earth metal ions, further enhancing the polarity of the material.…”

“…This electronegativity difference results in a negative charge for the oxygen ions and a positive charge for the rare earth metal ions, further enhancing the polarity of the material. Materials with strong polar qualities usually have strong catalytic properties, like CeO 2 , [19] Sc 2 O 3 , [20] Nd 2 O 3 , [21] Y 2 O 3 , [22] CeF 3 , [23] Eu 2 O 3 [24] and Sm 2 O 3 [25] have been reported to catalyze and accelerate the conversion of lithium polysulfide in lithium‐sulfur batteries, facilitating electron transfer and transfer thereby improving the reaction kinetics of the battery [18] . Furthermore, the robust Lewis acidity of the highly electronegative rare‐earth metal ions can facilitate their chemical interaction with the Lewis basic lithium polysulfide, promoting enhanced catalytic conversion processes [26]…”

Enhanced Redox Electrocatalysis in High-Entropy Perovskite Fluorides by Tailoring d–p Hybridization

“…Theoretically, synergistic effect and interaction of dissimilar species can enhance site-to-site electron transfer, allowing simultaneous stabilization of reaction intermediates with moderate binding energies in multi-steps/electron/phase redox conversions of LOB electrochemistry. A majority of works have been dedicated to the exploration of catalytic performance for HECs, and however, the understanding of activity origins and correlations between intrinsic electronic structure and reaction intermediates in HECs is greatly neglected [ 13 – 15 ]. Furthermore, the influence of multiple active sites on the nucleation/growth kinetics of Li 2 O 2 in redox processes remains ambiguous, hindering the selection and rational design of HECs catalysts for LOBs.…”