Batteries are disclosed. In some embodiments, a battery has a cathode that includes Cu.sub.xM.sub.yO.sub.zX.sub.t, where M is a metal, X includes one or more halides and/or nitrate, x+y is from about 6.8 to about 7.2, and z and t are selected so that the copper in Cu.sub.xM.sub.yO.sub.zX.sub.t has a formal oxidation state of +2 or greater.