Corrosion attenuation of zinc electrode in Zn-MnO2 battery by shielding effect in an aqueous ammonium chloride electrolyte

In this paper, we report on the electrochemical behavior of zinc (Zn) anode in Zn-MnO2 battery tested in aqueous NH4Cl electrolyte with a concentration ranging from 0.01 to 1 M without any additives. The Zn electrode shows the lowest corrosion behavior for the 0.1 M concentration. Such corrosion decrease was attributed to a shielding effect due to the formation of a corrosion layer expressed by a higher charge transfer resistance (R-ct) of 270 ohm. The X-ray diffraction (XRD) analysis shows that it constitutes by ZnO, Zn(OH)(2) and Zn(NH3)(2)Cl-2. The Zn was successfully assembled with MnO2 to form a Zn/MnO2 cell using 0.1 M NH4Cl electrolyte. Two types of MnO2 powders were experimented as cathode namely nanostructured MnO2 (NMD) and commercial MnO2 (EMD). It was found that NMD gives the best performance in terms of output voltage and specific energy. Indeed, the Zn/NMD cell has a voltage of 1.743 V which is higher than that of Zn/EMD (1.674 V) at a current of 1 mA. It was found that the cells voltage decreased after 4 h of continuous discharge to 1.712 V and 1.660 V, respectively. Moreover, the Zn/NMD cell can reach a highest specific energy of 228.30 mWh/g. Therefore, our Zn/NMD cell can be used for a high-performance primary battery and take over Zn/MnO2 battery market.