Lithium containing layered high entropy oxide structures
Junbo Wang, Yanyan Cui, Qingsong Wang, Kai Wang, Xiaohui Huang, David Stenzel, Abhishek Sarkar, Raheleh Azmi, Thomas Bergfeldt, Subramshu S. Bhattacharya, Robert Kruk, Horst Hahn, Simon Schweidler, Torsten Brezesinski, Ben Breitung
Abstract
Abstract Layered Delafossite-type Li x (M 1 M 2 M 3 M 4 M 5 …M n )O 2 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., LiNi x Co y Mn z O 2 [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.