Method of improving the cycle stability and energy density of a lithium metal secondary battery

A method of improving a cycle-life of a lithium metal secondary battery containing a non-solid state electrolyte, not including a lithium-sulfur battery or lithium-selenium battery, said method comprising a procedure of implementing an anode- protecting layer between an anode active material layer and a cathode active material layer without using a porous separator, wherein said anode-protecting layer is in a physical contact with said anode active material layer, has a thickness from 1 nm to 100 μm, and comprises an elastomer having a fully recoverable tensile elastic strain from 2% to 1,000% and a lithium ion conductivity from 10−8 S/cm to 5×10−2 S/cm when measured at room temperature and wherein said anode active material layer contains a layer of lithium or lithium alloy, in a form of a foil, coating, or aggregate of multiple particles, as an anode active material, wherein said elastomer contains a material selected from a non-sulfonated or sulfonated versions selected from the group consisting of protein resilin, protein elastin, and combinations thereof.

A method of improving a cycle-life of a lithium metal secondary battery containing a non-solid state electrolyte, not including a lithium-sulfur battery or lithium-selenium battery, said method comprising a procedure of implementing an anode-protecting layer between an anode active material layer and a cathode active material layer without using a porous separator, wherein said anode-protecting layer is in a physical contact with said anode active material layer, has a thickness from 1 nm to 100 μm, and comprises an elastomer having a fully recoverable tensile elastic strain from 2% to 1,000% and a lithium ion conductivity from 10−8 S/cm to 5×10−2 S/cm when measured at room temperature and wherein said anode active material layer contains a layer of lithium or lithium alloy, in a form of a foil, coating, or aggregate of multiple particles, as an anode active material, wherein said elastomer layer comprises from 0.01% to 50% of an electrically non-conducting reinforcement material dispersed therein, wherein said reinforcement material is selected from the group consisting of a ceramic fiber, polymer fiber, polymer particle, and combinations thereof, wherein said elastomer contains a material selected from a non-sulfonated or sulfonated versions selected from the group consisting of protein resilin, protein elastin, and combinations thereof.