As for Ni-Cd cell, which Ni (OH) 2 is used for positive, CdO for negative, KON for basis electrolyte, when Ni-Cd is charged, its positive reacts as below:
Ni(OH)2 –e + OH- → NiOOH + H2O
Negative reaction is:
Cd(OH)2 + 2e → Cd + 2OH-
The whole reaction is described as: 2Ni(OH)2 + Cd(OH)2→ 2NiOOH+ Cd+ 2H2O
When discharged, the reaction is reversible: NiOOH + H2O + e→ Ni(OH)2 + OH-
Cd + 2OH- + 2e→ Cd(OH)2
Ni (OH)2 consistence reduced with NiOOH consistence increasing during charging, and the positive electrical potential gradually raised, while with Cd increasing, Cd (OH)2 is decreased, and the negative electrical potential gradually reduced. When fully charged, the battery’s positive and negative electrical potential reached a balance value; and the electrical potential between the two electrodes is battery charge voltage. |
