Effect of BaBiO3 and Ba0.6K0.4BiO3 additives on the rechargeability of manganese oxide cathodes in alkaline cells

The effect of the incorporation of small amounts (1-5 wt%) of semiconducting BaBiO3 and metallic Ba0.6K0.4BiO3 additives on the rechargeability of electrolytic manganese dioxide (EMD) cathodes in alkaline cells in the one-electron regime has been investigated. Both the BaBiO3 and Ba0.6K0.4BiO3 additives lead to better cyclability compared to the previously known binary oxide additive Bi2O3. X-ray diffraction patterns recorded before and after 30 cycles as well as cyclic voltammograms recorded after first and 30 cycles reveal that the better cyclability in the presence of BaBiO3 and Ba0.6K0.4BiO3 additives is due to the suppression of the formation of unwanted, electrochemically inactive birnessite and hausmannite phases and a shifting of the second-electron capacity of Mn to higher potentials.