Lithium-selenium battery containing an electrode-protecting layer and method of improving cycle-life

A lithium-selenium secondary battery comprising a cathode, an anode, and a porous separator or electrolyte disposed between said cathode and said anode, wherein said cathode and wherein said anode comprises:

• (a) an anode active material layer, comprising a layer of lithium or lithium alloy, in a form of a foil, coating, or multiple particles aggregated together, as an anode active material, and an optional anode current collector supporting said anode active material layer;
• (b) a cathode active material layer, comprising a selenium-containing material as a cathode active material, selected from the group consisting of selenium, selenium-carbon hybrid, a selenium-graphite hybrid, selenium-graphene hybrid, conducting polymer-selenium hybrid, metal selenide, Se alloys or mixtures with Sn, Sb, Bi, S, or Te, selenium compounds, and combinations thereof, and an optional cathode current collector supporting said cathode active material layer;
• (c) an electrolyte and a porous separator layer;
• and
• (d) a discrete anode-protecting layer disposed between said anode active material layer and said porous separator and/or a discrete cathode-protecting layer disposed between the porous separator and the cathode active material layer;
• wherein said anode-protecting layer or cathode-protecting layer comprises a conductive sulfonated elastomer composite having from 0.01% to 40% by weight of a conductive reinforcement material and from 0.01% to 40% by weight of an electrochemically stable inorganic filler dispersed in a sulfonated elastomeric matrix material and said layer of conductive sulfonated elastomer composite has a thickness from 1 nm to 100 μm, a fully recoverable tensile strain from 2% to 500%, a lithium ion conductivity from 10−7 S/cm to 5×10−2 S/cm, and an electrical conductivity from 10−7 S/cm to 100 S/cm when measured at room temperature and wherein said inorganic filler has a lithium intercalation potential from 1.1 V to 4.5 V versus Li/Li+ and is selected from an oxide, carbide, boride, nitride, sulfide, phosphide, or selenide of a transition metal, a lithiated version thereof, or a combination thereof.