Principle of Ni MH battery

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Principle of Ni MH battery

Principle of Ni MH battery

Principle of Ni MH battery:

1. Electrolyte

Koh is mainly used as electrolyte (electrolyte 7moL/LKOH+15g/LLiOH)

2. When charging

Anodic reaction:Ni(OH) 2 + OH - → NiOOH + H 2O + e -

Cathodic reaction:M + H 2O + e - → MH + OH -

Total reaction:M + Ni(OH) 2 → MH + NiOOH

3. When discharging

Positive:NiOOH + H 2O + e - → Ni(OH) 2 + OH -

negative pole:MH + OH - → M + H 2O + e -

Total reaction:MH + NiOOH → M + Ni(OH) 2

In the above formula, M is a hydrogen storage alloy and MH is a hydrogen storage alloy adsorbed with hydrogen atoms. The most commonly used hydrogen storage alloy is LaNi5.

Ni MH battery is composed of hydrogen ions and metal nickel. Its power reserve is 30% more than that of Ni Cd battery, lighter than Ni Cd battery, longer service life and no pollution to the environment. The disadvantage of Ni MH battery is that the price is much more expensive than Ni Cd battery, and the performance is worse than lithium battery.

Chemical composition:

The "metal" part of Ni MH battery is actually metal hydride.

Used in the manufacture of Ni MH batteries, they are mainly divided into two categories. The most common is AB5, A is a mixture of rare earth elements (or) plus titanium (TI); B is nickel (Ni), cobalt (CO), manganese (MN), (or) and aluminum (AL). The "multi-component" electrodes of some high-capacity batteries are mainly composed of AB2, where a is titanium (Ti) or vanadium (V), B is zirconium (Zr) or nickel (Ni), plus some chromium (CR) and cobalt (CO), iron (FE) and / or manganese (MN). All these compounds play the same role: reversibly form metal hydride. When the battery is charged, the hydrogen ion (H +) in the potassium hydroxide (KOH) electrolyte will be released and absorbed by these compounds to avoid the formation of hydrogen (H2) to maintain the pressure and volume inside the battery. When the battery is discharged, these hydrogen ions will return to their original place through the opposite process.

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Principle of Ni MH battery_Nickel metal hydride battery