In a lithium-iodine (LiI) battery, a solid lithium anode is surrounded by a polymer impregnated with iodine. The net reaction, Li + ½ I₂→LiI, has a standard reaction free energy of ΔG⁰ = −266.9 kJ/mol and a standard reaction enthalpy of ΔH⁰ = −270.08 kJ/mol. Estimate the cell voltage ℰ⁰, the upper limits on the thermodynamic efficiency η, and the upper limit on the specific energyε_effective of a LiI battery.