A solid electrolyte includes a polymer and a lithium salt, a sodium salt or mixtures of these salts. The polymer has at least 50 mol % of recurring units of formula (I). A method is for the preparation of the electrolyte. Energy storage devices can include the electrolyte.

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An object is to provide an electrode active material that can provide an alkali metal battery having a longer charge/discharge life and a higher capacity. The problem is solved by means of an electrode active material for an alkali metal battery, represented by formula: A.sub.a1MS.sub.a2X.sub.a3 wherein A is selected from Li and Na; M is selected from V, Nb, Ta, Ti, Zr, Hf, Cr, Mo, and W which are group 4 to 6 elements; X is selected from F, Cl, Br, I, CO.sub.3, SO.sub.4, NO.sub.3, BH.sub.4, BF.sub.4, PF.sub.6, ClO.sub.4, CF.sub.3SO.sub.3, (CF.sub.3SO.sub.2).sub.2N, (C.sub.2F.sub.5SO.sub.2).sub.2N, (FSO.sub.2).sub.2N, and [B(C.sub.2O.sub.4).sub.2]; a1 is 1 to 9; a2 is 2 to 6; when a3 is 3 and a3 is 0, a2 is not 4; and when M does not include V, a3>0.

Electrolytes and electrochemical cells include a novel ionic liquid having a quaternary cation and a boron cluster anion. In some versions, the boron cluster anion will be a functionalized or unfunctionalized icosahedral boranyl or carboranyl anion. Electrochemical cells have an electrolyte including the ionic liquid. In some versions, the ionic liquid is used as a solvent to dissolve an ionic shuttle salt for transport of active material, with an optional co-solvent. Methods to synthesize the ionic liquid include contacting a boron cluster salt with a quaternary salt to form the ionic liquid by a metathesis reaction.

Electrolytes and electrochemical cells include a novel ionic liquid having a quaternary cation and a boron cluster anion. In some versions, the boron cluster anion will be a functionalized or unfunctionalized icosahedral boranyl or carboranyl anion. Electrochemical cells have an electrolyte including the ionic liquid. In some versions, the ionic liquid is used as a solvent to dissolve an ionic shuttle salt for transport of active material, with an optional co-solvent. Methods to synthesize the ionic liquid include contacting a boron cluster salt with a quaternary salt to form the ionic liquid by a metathesis reaction.

A sulfur cathode generated at least in part by in situ electrochemical pulverization of a metallic sulfide compound is provided. The in situ generated sulfur cathode suppresses the unfavorable process of polysulfide shuttling to provide enhanced sulfur cathode performance and is envisioned for use in Li—S, Na—S, K—S, Ca—S, Mg—S or Al—S batteries used to support rechargeable electronic devices and electric vehicles.

According to one embodiment, a separator is provided. The separator includes a composite membrane. The composite membrane includes a substrate layer, a first composite layer, and a second composite layer. The first composite layer is located on one surface of the substrate layer. The second composite layer is located on the other surface of the substrate layer. The composite membrane has a coefficient of air permeability of 1×10.sup.−14 m.sup.2 or less. The first composite layer has a first surface and a second surface. The first surface is in contact with the substrate layer. The second surface is located on an opposite side to the first surface. Denseness of a portion including the first surface is lower than denseness of a portion including the second surface in the first composite layer.

According to one embodiment, a separator is provided. The separator includes a composite membrane. The composite membrane includes a substrate layer, a first composite layer, and a second composite layer. The first composite layer is located on one surface of the substrate layer. The second composite layer is located on the other surface of the substrate layer. The composite membrane has a coefficient of air permeability of 1×10.sup.−14 m.sup.2 or less. The first composite layer has a first surface and a second surface. The first surface is in contact with the substrate layer. The second surface is located on an opposite side to the first surface. Denseness of a portion including the first surface is lower than denseness of a portion including the second surface in the first composite layer.

The invention relates to Chevrel-phase materials and methods of preparing these materials utilizing a precursor approach. The Chevrel-phase materials are useful in assembling electrodes, e.g., cathodes, for use in electrochemical cells, such as rechargeable batteries. The Chevrel-phase materials have a general formula of Mo.sub.6Z.sub.8 (Z=sulfur) or Mo.sub.6Z.sup.1.sub.8-yZ.sup.2.sub.y (Z.sup.1=sulfur; Z.sup.2=selenium), and partially cuprated Cu.sub.1Mo.sub.6S.sub.8 as well as partially de-cuprated Cu.sub.1-xMg.sub.xMo.sub.6S.sub.8 and the precursors have a general formula of M.sub.xMo.sub.6Z.sub.8 or M.sub.xMo.sub.6Z.sup.1.sub.8-yZ.sup.2.sub.y, M=Cu. The cathode containing the Chevrel-phase material in accordance with the invention can be combined with a magnesium-containing anode and an electrolyte.

The invention relates to Chevrel-phase materials and methods of preparing these materials utilizing a precursor approach. The Chevrel-phase materials are useful in assembling electrodes, e.g., cathodes, for use in electrochemical cells, such as rechargeable batteries. The Chevrel-phase materials have a general formula of Mo.sub.6Z.sub.8 (Z=sulfur) or Mo.sub.6Z.sup.1.sub.8-yZ.sup.2.sub.y (Z.sup.1=sulfur; Z.sup.2=selenium), and partially cuprated Cu.sub.1Mo.sub.6S.sub.8 as well as partially de-cuprated Cu.sub.1-xMg.sub.xMo.sub.6S.sub.8 and the precursors have a general formula of M.sub.xMo.sub.6Z.sub.8 or M.sub.xMo.sub.6Z.sup.1.sub.8-yZ.sup.2.sub.y, M=Cu. The cathode containing the Chevrel-phase material in accordance with the invention can be combined with a magnesium-containing anode and an electrolyte.

A solid electrolyte includes an oxynitride that contains an alkaline-earth metal, phosphorus, oxygen, and nitrogen. A P2p spectrum obtained by an X-ray photoelectron spectroscopy measurement of the oxynitride contains a peak component originating from a P—N bond.