An electrode comprises a manganese oxide compound, one or more additives, and a conductive carbon. The manganese oxide compound has manganese in a valence state that is ≤3. The one or more additives can be selected from the group consisting of bismuth, bismuth salt, copper, copper salt, tin, tin salt, lead, lead salt, silver, silver salt, cobalt, cobalt salt, nickel, nickel salt, magnesium, magnesium salt, aluminum, aluminum salt, potassium, potassium salt, lithium, lithium salt, calcium, calcium salt, gold, gold salt, antimony, antimony salt, iron, iron salt, barium, barium salt, zinc and zinc salt.