Lithium containing layered high entropy oxide structures

Junbo Wang,Horst Hahn,David Stenzel,Ben Breitung,Kai Wang,Abhishek Sarkar,Thomas Bergfeldt,Qingsong Wang,Torsten Brezesinski,Raheleh Azmi,Simon Schweidler,Robert Kruk,Yanyan Cui,Subramshu S Bhattacharya,Xiaohui Huang

doi:10.1038/s41598-020-75134-1

Abstract

Layered Delafossite-type Lix(M1M2M3M4M5…Mn)O2 materials, a new class of high-entropy oxides, were synthesized by nebulized spray pyrolysis and subsequent high-temperature annealing. Various metal species (M = Ni, Co, Mn, Al, Fe, Zn, Cr, Ti, Zr, Cu) could be incorporated into this structure type, and in most cases, single-phase oxides were obtained. Delafossite structures are well known and the related materials are used in different fields of application, especially in electrochemical energy storage (e.g., LiNixCoyMnzO2 [NCM]). The transfer of the high-entropy concept to this type of materials and the successful structural replication enabled the preparation of novel compounds with unprecedented properties. Here, we report on the characterization of a series of Delafossite-type high-entropy oxides by means of TEM, SEM, XPS, ICP-OES, Mössbauer spectroscopy, XRD including Rietveld refinement analysis, SAED and STEM mapping and discuss about the role of entropy stabilization. Our experimental data indicate the formation of uniform solid-solution structures with some Li/M mixing.

Highlights

Layered Delafossite-type Lix(M1M2M3M4M5...Mn)O2 materials, a new class of high-entropy oxides, were synthesized by nebulized spray pyrolysis and subsequent high-temperature annealing
High-entropy materials can be seen as compounds comprising several different elements in a single-phase structure and according to the Gibbs–Helmholtz equation, the resulting configurational entropy may have structure stabilizing e ffects[9,10,11,12,13,14]
The configurational entropy is solely based on the number of different elements incorporated in a single-phase structure and can be calculated using a Boltzmann-entropy-derived equation (Gibbs entropy, Eq 1)

Summary

Introduction

Layered Delafossite-type Lix(M1M2M3M4M5...Mn)O2 materials, a new class of high-entropy oxides, were synthesized by nebulized spray pyrolysis and subsequent high-temperature annealing. High-entropy materials can be seen as compounds comprising several different elements in a single-phase structure and according to the Gibbs–Helmholtz equation, the resulting (large) configurational entropy may have structure stabilizing e ffects[9,10,11,12,13,14].

Results

Conclusion