Various embodiments of the invention disclose that the uptake of LiO.sup.iPr in Mg.sub.2(dobdc) (dobdc.sup.4-=1,4-dioxido-2,5-benzenedicarboxylate) followed by soaking in a typical electrolyte solution leads to a new solid lithium electrolyte Mg.sub.2(dobdc).0.35LiO.sup.iPr.0.25LiBF.sub.4.EC.DEC. Two-point ac impedance data show a pressed pellet of this material to have a conductivity of 3.1.times.10.sup.-4 S/cm at 300 K. In addition, the results from variable-temperature measurements reveal an activation energy of approximately 0.15 eV, while single-particle data suggest that intraparticle transport dominates conduction.