Electrical performance and chemical composition studies on original and falsified Ni-MH batteries

We show in this paper that falsifications on technological products have hit even rechargeable nickel metal hydride batteries (Ni-MH). The electrical performance and the electrode chemical composition were investigated for authentic and falsified AAA Ni-MH batteries, purchased in the Londrina market, Paraná State. Battery charge capacities were measured at 0,2 C discharge rate and average electrical power was measured at 0.2 and 0.8 C discharge rate. To perform chemical composition analysis, the batteries were vacuum dismantled and their electrodes were characterized by Energy Dispersive X-Ray Fluorescence (EDXRF) and X-Ray Diffraction (XRD) techniques. It was observed that the charge capacities for the authentic and falsified batteries were 920 and 154 mAh, respectively. The average electrical powers were 210 mW for authentic and 41 mW for falsified batteries. The cathode chemical composition was nickel hydroxide, (Ni(OH)2), for both kinds of batteries. However, the anodes of these batteries were not composed by the same materials. The alloy LaNi5 was identified as the electroactive compound in the anode of the authentic battery, while cadmium hydroxide compound, (Cd (OH)2), was identified in the falsified battery anode. The authentic battery therefore presented six times more charge capacity, five times more power at 0.2 C discharge rate and 6 times at 0.8 C than the falsified battery, and are yet less dangerous to environment due cadmium absence.