In this work the role of Ti(IV) and Ba(II) additives in improving the rechargeability of the alkaline manganese dioxide cathode was examined. Modeling of the impedance response of electrodes containing a proportion of additive species, either 10% TiO2 and 3% Ba(OH)(2), in place of the active MnO2 revealed important changes which occur at or near the particle surface. The presence of Ti(TV) or Bag) species at the particle surface was shown to cause a significant decrease in the charge-transfer resistance, most notably in the case of Ti(IV), with these changes explaining the improved performance previously noted for these electrodes. Studies of proton diffusivity within each electrode revealed a decrease in the presence of additive materials and these changes were shown to arise either through the inclusion of Ti(IV) into the bulk structure, or by the progressive buildup of Ba(II) within micropores in the active material. (C) 2014 The Electrochemical Society. All rights reserved.