NiMH Batteries

- Aug 22, 2019-


Nickel-metal hydride batteries are a good battery. Nickel-metal hydride batteries are classified into high-voltage nickel-hydrogen batteries and low-voltage nickel-hydrogen batteries. The positive electrode active material of the nickel-hydrogen battery is Ni(OH)2 (called NiO electrode), the negative electrode active material is metal hydride, also called hydrogen storage alloy (electrode called hydrogen storage electrode), and the electrolyte is 6 mol/L potassium hydroxide solution. Nickel-hydrogen batteries have become more and more important as an important direction for hydrogen energy applications.


Structure and principle

The positive electrode active material of the nickel-hydrogen battery is Ni(OH)2 (called NiO electrode), the negative electrode active material is metal hydride, also called hydrogen storage alloy (electrode called hydrogen storage electrode), and the electrolyte is 6 mol/L potassium hydroxide solution. The process of forming the electrode sheet of the active material mainly includes sintering type, slurry type, foam nickel type, fiber nickel type and inlay type. The electrodes prepared by different processes have large differences in capacity and large current discharge performance. The battery is produced according to a process using different conditions. Most of the consumer batteries such as communication use a slurry-type negative electrode and a foamed nickel-type positive electrode to form a battery. Charge


The electrochemical reaction is as follows

Positive electrode: Ni(OH)2 OH-=NiOOH H2O e-

Negative electrode: M H2O e-=MHab OH-

Total reaction: Ni(OH)2 M=NiOOH MH

Note: M: hydrogen alloy; Hab: adsorption of hydrogen; the process of the reaction from left to right is the charging process; the process of the reaction from right to left is the discharge process.


Ni(OH)2 and OH- of the positive electrode react to form NiOOH and H2O during charging, and release e- together to form MH and OH-. The total reaction is Ni(OH)2 and M to form NiOOH, hydrogen storage alloy hydrogen storage; discharge In contrast, MHab releases H , H  and OH- to form H2O and e-, NiOOH, H2O and e- regenerate Ni(OH)2 and OH-. The standard electromotive force of the battery is 1.319V.