Alpha Technologies Industrial Ni-Cd Batteries Standard Range - Manual (Page 11)

EN-ALPHA-TMSR-001 (10/09) 11
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3. 0 Electrochemistry of Ni-Cd batteries
Cd Cd 2+ + 2 e¯
During charging the both reactions are reversed.
The complete reaction is:
Negative electrode
Ni3 + + e¯ Ni2+
Reduction of trivalent nickel ions to bivalent at the
positive electrode
Cd + 2 OH¯ Cd(OH)2 + 2 e¯
Cell reaction
Positive electrode
2 NiOOH + 2 H2O + 2 e¯ 2 Ni(OH)2 + 2 OH¯
2 NiOOH + Cd + 2 H2O 2 Ni(OH)2 + Cd(OH)2
Oxidation of cadmium at the negative electrode