An Aqueous Rechargeable Lithium Battery Using Coated Li Metal as Anode

New energy industry including electric vehicles and large-scale energy storage in smart grids requires energy storage systems of good safety, high reliability, high energy density and low cost. Here a coated Li metal is used as anode for an aqueous rechargeable lithium battery (ARLB) combining LiMn ₂ O₄ as cathode and 0.5mol l^-1 Li₂ SO₄ aqueous solution as electrolyte. Due to the cross-over effect of Li⁺ ions in the coating, this ARLB delivers an output voltage of about 4.0V, a big breakthrough of the theoretic stable window of water, 1.229V. Its cycling is very excellent with Coulomb efficiency of 100% except in the first cycle. Its energy density can be 446Wh kg-1, about 80% higher than that for traditional lithium ion battery. Its power efficiency can be above 95%. Furthermore, its cost is low and safety is much reliable. It provides another chemistry for post lithium ion batteries.