Batteries.*

Large-scale electrical energy storage is essential for seamless integration of intermittent renewable energy sources into the power grid. Rechargeable alkaline Zn/MnO₂ batteries hold great promise for electrical energy storage and power grid applications due to their high energy density, non-toxicity, and low cost. Bi and Cu additives are known to significantly extend the cycle life and increase the capacity of MnO₂ electrodes in rechargeable Zn/MnO₂ batteries. However, the mechanism of interaction of Bi and Cu with the MnO₂ cathode material is not completely understood. To investigate the influence of chemical additives on the rechargeability and cyclability of MnO₂ electrodes, we calculated the geometries and formation enthalpies for a wide variety of crystal structures of MnO₂ modified with Bi, Cu, and Mg using ab initio computational methods based on density functional theory. The results of our calculations suggest that reversible transitions between the layered and spinel phases could play an important role in the cycling mechanism of chemically modified MnO₂ cathodes.