Lithium containing layered high entropy oxide structures

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.

Alternate Layers of Cobalt Doped Tungsten Oxide and Reduced Graphene Oxide Composite as Electrode Material for Supercapacitor

Composites consist of layers of cobalt doped tungsten oxide and reduced graphitic oxide was prepared using jet nebulized spray pyrolysis technique. A mixture of ammonium tungstate and cobalt acetate solution was coated on glass substrate at 380 °C using jet nebulized spray pyrolysis technique. Spray technique is used to form the reduced graphene oxide (rGO) layer over the first layer and again ammonium tungstate and cobalt acetate solution coated over the surface of rGO and then calcined in nitrogen atmosphere at 450 °C for 2 h. The composite were characterized using XRD, SEM, PL, CV and EIS studies. The SEM and XRD reveal the layered structure. Cyclic voltammetry reveals the high specific capacitance 500 Fg-1 at 5 mV s-1 scan rate for 2 M Na2SO4 as electrolyte. Layered structure of CoWO4/rGO/CoWO4 composite enhances the specific capacitance. EIS gives the electrical series resistance of 7.9 Ω. The layered CoWO4/rGO/CoWO4 composite can be suitable electrode materials for supercapacitor.

Layered High-Entropy Oxide Structures for Reversible Energy Storage

<p>Layered Li<i>_x</i>MO₂ materials, a new class of high-entropy oxides, have been synthesized by nebulized spray pyrolysis. Specifically, the lattice structure of Li(Ni_1/3Mn_1/3Co_1/3)O₂ (NCM111) cathode material has been replicated successfully while increasing the number of cations in equimolar proportions, thereby allowing transition to high-entropy oxide materials.</p>