Nickel-metal hydride batteries

These batteries work by moving hydrogen ions (H⁺ or protons) within the battery to store and release electrical energy.

Inside the battery there are two main parts: the positive side made of nickel oxyhydroxide (NiOOH) and the negative side made of metal alloys like nickel-titanium alloys (TiNi₂ and Ti₂Ni) and nickel zirconium (ZrNi). These two parts are separated by a membrane and surrounded by a liquid electrolyte containing potassium hydroxide (KOH).

When the battery is in use (discharging), the hydrogen ions move from the metal alloy toward the positive side and react with hydroxide (OH^–). When the battery is being recharged, the hydrogen ions move back from the positive side to the negative. This back-and-forth movement of hydrogen ions is what allows the battery to store and release energy (Berg, 2015; Skyllas-Kazacos, 2010).

_{Based on information from Berg, 2015 and Skyllas-Kazacos, 2010}

Research and share

Hopefully you have completed the task in Step 1.8, to research nickel-cadmium (NiCad) batteries. Compare what you’ve learned about NiCad batteries to NiMH, in terms of their charge/discharge mechanism and advantages and disadvantages. Share some findings in the comments below.

References

Berg, H. (2015). Batteries for electric vehicles: materials and electrochemistry. Cambridge University Press.

Skyllas-Kazacos, M. (2010). Electro-chemical energy storage technologies for wind energy systems. Stand-alone and hybrid wind energy systems, 323-365.