Bi- and Cu-Modified $\delta $-MnO$_{\mathrm{2}}$ Electrodes in Rechargeable Zn/MnO$_{\mathrm{2}}$ Batteries: An \textit{Ab Initio} study.*

Despite experimental evidence of the influence of Bi and Cu additives on the performance of rechargeable Zn/MnO$_{\mathrm{2}}$ batteries, the mechanism by which these additives affect the rechargeability and cyclability of the $\delta $-MnO$_{\mathrm{2}}$ electrode has not been explained in detail. We apply first-principles computational methods based on density functional theory to study the electrochemical properties of Bi- and Cu-modified delta-MnO$_{\mathrm{2}}$ electrodes in rechargeable Zn/MnO$_{\mathrm{2}}$ batteries. Our calculations show the possibility of formation of Bi-Mn and Cu-Mn oxides in Bi/Cu-modified $\delta $-MnO$_{\mathrm{2}}$ 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 MnO$_{\mathrm{2}}$ electrode.