NiMH battery pack.Nickel metal hydride battery technology training: nickel metal hydride battery principle

Nickel-hydrogen battery technical training provided by electronic enthusiasts: Nickel-hydrogen battery principle, Nickel-hydrogen battery technical training: Nickel-hydrogen battery principle The positive active material of the nickel-hydrogen battery is nickel hydroxide (called nickel oxide electrode), and the negative active material is metal oxide material, also called hydrogen storage alloy (the electrode is called hydrogen storage electrode)

Nickel metal hydride battery technology training: nickel metal hydride battery principle

The positive active material of the nickel-hydrogen battery is nickel hydroxide (called nickel oxide electrode), the negative active material is metal oxide, also called hydrogen storage alloy (the electrode is called hydrogen storage electrode), and the electrolyte is 6N potassium hydroxide. During battery charging and discharging The battery reaction during the process is:

Among them, M represents hydrogen storage alloy material. The open circuit voltage of the battery is: 1.2V~1.3V, which varies due to different hydrogen storage materials and preparation processes. When overcharging, the reaction on the two poles is: on the nickel oxide electrode: 4OH`-4e-2H2O ten O2

On the hydrogen storage electrode; 2H2O+O2+4e—4OH`

Overall reaction when the battery is overcharged: O

In the design of batteries, the method of using an excessive amount of negative electrode is generally used. When the nickel oxide electrode is fully charged, oxygen is generated, which is recombined into water at the negative electrode through diffusion. In this way, the internal pressure of the battery is kept constant and the concentration of the electrolyte is kept constant. Giant changes occur. When the battery is over-discharged, the electrode reaction is:

On nickel oxide electrode: 2H2O+2e—H2+2OH`

On the hydrogen storage electrode; H2+2OH`-2e—2H2O

Overall reaction when the battery is over-discharged: O

Although the net result of the total battery reaction is zero when over-discharged, polarity reversal will occur. Since the hydrogen produced on the positive electrode will be recombined on the negative electrode, the stability of the system is also maintained. In addition, the negative active material hydrogen can be adsorbed into the dry hydrogen storage alloy in the hydrogen atomic state at a relatively high density. On such an electrode, the hydrogen absorption and release reaction can proceed smoothly, and the discharge performance is improved compared to cadmium-nickel batteries.