High entropy spinel-structure oxide for electrochemical application

High entropy materials are attracting ever-increasing concern on account of their unique structure and un-precedented potential application in various fields. In this letter, a high entropy (Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)(3)O-4 (S-HEO) with Fd3m spinel structure, is prepared by solid-state reaction. Importantly, without the presence of entropy stabilization behavior, single spinel-structure of S-HEO can be retained through the re-heat treatment process. Benefiting from abundant electroactive species and various chemical valance, excellent Li+ storage capability and favorable performance toward oxygen evolution reaction (OER) are achieved with S-HEO. As anode material for Li ion batteries, S-HEO presents a high specific capacity of 560 mAh g(-1) at 100 mA g(-1) and superior capacity retention of 100% after 5000 cycles. In-situ EIS, ex-situ TEM and XRD analysis were conducted to probe insight into the diffusion kinetic and structural evolution of S-HEO upon cycling. Efficient water oxidation with an overpotential of 332 mV to reach 10 mA cm(-2) are achieved with S-HEO. With comparison to spinel-type moderate entropy oxides (S-MEOs), the synergic effect between five species highlight the merits of high-entropy feature, manifesting a better OER kinetic and higher stability in KOH solution. This research demonstrates the significant importance of high-entropy concept to boost the performance of high entropy materials for electrochemical application.

Automated summary

High entropy materials have unique structures and unprecedented potential applications, which has led to increasing interest in this field. In this study, a high entropy material with a spinel structure was prepared and showed excellent performance in lithium-ion batteries and oxygen evolution reaction. Through experiments and analysis, the diffusion kinetics and structural evolution of the material during cycling were investigated.