The synergistic effect of bismuth oxide (Bi2O3) + titanium disulphide (TiS2) additives in different proportions into the MnO2 cathode material is physically modified and tested in a Zn-MnO2 battery with aqueous LiOH electrolyte. It is found that these foreign cations stabilized the MnO2 structure upon multiple cycling and the synergistic effect between two additives enhanced the rechargeability. This class of additive modified MnO2 may be of interest for high-energy density and safer batteries for applications such as electric vehicles. The cyclability of the material suitable for electric vehicle (EV) applications is established in this report. The incorporation of Bi2O3 (3 wt.%) and TiS2 (2 wt.%) additives into the MnO2 cathode was found to improve the cell performance, this is partly due to the suppression of proton insertion. The results on cyclic voltammetric and charge-discharge studies describing the redox mechanisms in LiOH electrolyte and the role of additives on those redox reactions are discussed and compared with that of traditional KOH electrolyte.