The present disclosure relates to an electrolyte comprising: a) a sodium salt; b) an additive comprising at least one additional metallic/metalloid cation having a standard reduction potential which is at least 2.5V more positive than that of sodium cation; wherein said sodium salt and said additive are dispersed in a solvent comprising at least one alkyl carbonate, and wherein the concentration of said metallic/metalloid cation in the electrolyte is 15 mM to 250 mM. The present disclosure also relates to a sodium-sulfur cell comprising a sodium anode, a microporous sulfur cathode, and the electrolyte as described herein. The present disclosure further provides a method of improving cycling life of a sodium-sulfur cell, wherein the sodium-sulfur cell comprising a sodium anode, a sulfur cathode, and an electrolyte containing a sodium salt dispersed in an alkyl carbonate solvent.

The invention relates to a method for manufacturing of a sinterable green body from sodium-β-aluminate- and/or precursor-particles bonded via binders by means of slip casting, wherein a castable slip containing the particles as well as dispersants and binders is introduced into a casting mold and, after solidification, is demolded as a green body.

Provided is a sulfide-based solid electrolyte, including: a Na element; a Ge element; a P element; and a S element, wherein an atomic percentage (at. %) of each of the Na element, the Ge element, the P element, and the S element is as follows when a total of the respective elements is 100 at. %, Na: from 38.8 at. % to 48.4 at. % Ge: from 0.5 at. % to 8.9 at. % P: from 3.9 at. % to 7.9 at. % S: from 43.6 at. % to 48.6 at. %.

Provided is a sodium ion conductor whose sodium ion conductivity is improved more than the conventional. The sodium ion conductor is a molecular crystal constituted of NaCB.sub.9H.sub.10, NaCB.sub.11H.sub.12, and a sodium halide, the sodium halide having a mol fraction of more than 0 and at most 70 on the basis of the total mol ratio of NaCB.sub.9H.sub.10, NaCB.sub.11H.sub.12, and the sodium halide.

The present invention relates to a novel cathode employing a monoclinic sulfur phase that enables a single plateau lithium-sulfur reaction in, for example, a carbonate electrolyte system. The cathode is applicable to a variety of other types of anodes. Also disclosed are an electrode of a cell or battery and a battery including the cathode.

A dense β″-alumina/zirconia composite solid electrolyte and process for fabrication are disclosed. The process allows fabrication at temperatures at or below 1600° C. The solid electrolytes include a dense composite matrix of β″-alumina and zirconia, and one or more transition metal oxides that aid the conversion and densification of precursor salts during sintering. The composite solid electrolytes find application in sodium energy storage devices and power-grid systems and devices for energy applications.

The present invention relates to a method for making a novel cathode employing a monoclinic sulfur phase that enables a single plateau lithium-sulfur reaction in, for example, a carbonate electrolyte system. The cathode is applicable to a variety of other types of anodes. The method produces a cathode suitable for use in an electrode of a cell or battery by depositing monoclinic phase sulfur via vapor deposition onto a substrate in a sealed vapor deposition apparatus.

Provided is a sodium ion conductor whose sodium ion conductivity is improved more than the conventional. The sodium ion conductor is a molecular crystal constituted of NaCB.sub.9H.sub.10, NaCB.sub.11H.sub.12, and a sodium halide, the sodium halide having a mol fraction of more than 0 and at most 70 on the basis of the total mol ratio of NaCB.sub.9H.sub.10, NaCB.sub.11H.sub.12, and the sodium halide.

The invention relates to a method for the precipitation of a solid material, where the method comprises: providing an aqueous metal ion solution, said metal ion solution comprising TiOSO.sub.4 and metal ions of a metal M, where M is one or more of the elements: Mg, Co, Cu, Ni, Mn, Fe; providing an aqueous carbonate solution; and mixing said aqueous metal ion solution and said aqueous carbonate solution thereby providing a solid material comprising titanium and a metal carbonate comprising said metal(s) M, where the titanium is homogeneously distributed within the solid material. The invention also relates to a solid material, a method of preparing a positive electrode material for a secondary battery from the solid material and the use of the solid material as a precursor for the preparation of a positive electrode material for a secondary battery.

A battery cells that include sulfide cathodes are described with examples being suitable for operation at elevated temperatures. Also described are methods of making and using these battery cells.