A battery (100) comprises an electrolyte in which a lanthanide and zinc form a redox pair. Preferred electrolytes are acid electrolytes, and most preferably comprise methane sulfonic acid, and it is further contemplated that suitable electrolytes may include at least two lanthanides. Contemplated lanthanides include cerium, praseodymium, neodymium, terbium, and dysprosium, and further contemplate lanthanides are samarium, europium, thulium and ytterbium.