Alkaline-Earth Oxide Modified MnO₂ Cathode: Enhanced Performance in an Aqueous Rechargeable Battery

The current work is reported on employing alkaline-earth oxide additives—i.e., barium oxide (BaO), calcium oxide (CaO), or magnesium oxide (MgO)—to the manganese dioxide (MnO 2 ) cathode in an environmentally safe aqueous rechargeable battery. The influence of these additives on the electrochemical behavior of the MnO 2 cathode in a Zn-MnO 2 battery using lithium hydroxide (LiOH) as an electrolyte is investigated. These additives enhanced the discharge performance of the Zn-MnO 2 battery and its rechargeability. Herein, the MnO 2 was physically mixed with at least one of the alkaline-earth oxides (such as BaO, CaO, or MgO) in different proportions of 1, 2, and 5 wt % during the electrode preparation. The incorporation of BaO or MgO additives into MnO 2 was found to result in significantly higher discharge capacity and longer cycle life, compared with the battery using CaO additive or additive-free MnO 2 . The role of these additives in the MnO 2 cathode is found not to suppress the formation of nonrechargeable products, but rather to reduce the access of Zn ions to the MnO 2; without these additives, a ZnO·Mn 2 O 3 product may form at the cathode.