<i>Ab Initio</i> Study of the Discharge Mechanism of Bi- and Cu- Modified MnO₂/Zn Rechargeable Batteries.

Bi and Cu additives have a great influence on the performance of rechargeable Zn/MnO₂ batteries, however, the mechanism by which these additives affect the rechargeability and cyclability of the MnO₂ electrode has not been explained in detail. We applied first-principles computational methods based on density functional theory to study the discharge mechanism of Bi- and Cu-modified δ-MnO₂ electrodes in rechargeable Zn/MnO₂ batteries. Our calculations show the possibility of formation of Bi-Mn and Cu-Mn oxides in Bi/Cu-modified δ-MnO₂ cathodes during battery cycling. The results of our study suggest that the formation of intermediate Bi-Mn and Cu-Mn oxides could reduce the rate of accumulation of irreversible redox reaction products in the MnO₂ electrode.