A comparative study, of 1 M and 8 M KOH electrolyte concentrations, used in Ni–MH batteries

One may wonder if we really should use a very high concentration of KOH electrolyte in Ni–MH batteries, to keep the thermodynamic and kinetic properties of the alloy, while this solution is very aggressive to the used alloys. In this work we present a comparative study, using different techniques of two concentrations, 1 M and 8 M KOH electrolytes. The maximum capacity values are 295 mAh g−1 and 237 mAh g−1, the loss in capacity, after 23 cycles, are of 10% and 58%, the polarization after the activation are 110 mV and 360 mV and the thickness of the corrosion layer, on the electrode surface, are 7 nm and 42 nm, for the 1 M and 8 M KOH electrolytes, respectively. These results showed that replacing the solution 8 M with 1 M improves the performance of Ni–MH batteries and leads to better results.