A lithium battery includes: a positive electrode having a positive active material; a negative electrode including lithium metal; and a solid electrolyte disposed therebetween. The solid electrolyte contains at least one oxide represented by Li4±xM1-x′M′x′O4 (Formula 1), Li4-yM″O4-yA′y (Formula 2), or Li4+4zM′″1-zO4 (Formula 3), wherein and 0≤x23 1 and 0≤x′≤1, M is a Group 4 element, and M′ is an element of Group 2, 3, 5, 12, or 13, a vacancy, or a combination thereof, with the proviso that when M is Zr, then x≠0, x′≠0 and M′ is Be, Ca, Sr, Ba, Ra, Cd, Hg, Cn, Ga, In, TI, an element of Group 3 or 5, or a combination thereof; 0≤y≤1, M″ is a Group 4 element, and A′ includes at least one halogen, with the proviso that when M″ is Zr, then y≠0; and 0