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Standard potentials in aqueous solution at 298K


Reaction Eo (V)
Li+ + e → Li
-3.10
Na+ + e → Na
-2.71
Mg2+ + 2e → Mg
-2.36
½H2 + e → H
-2.25
Mn2+ + 2e → Mn
-1.18
MnO2 + 2H2O + 4e → Mn + 4OH
-0.98
2H2O + 2e → H2 + 2OH
-0.83
Cd(OH)2 + 2e → Cd + 2OH
-0.82
Zn2+ + 2e → Zn
-0.76
Ni(OH)2 + 2e → Ni + 2OH
-0.72
Fe2+ + 2e → Fe
-0.44
Cd2+ + 2e → Cd
-0.40
PbSO4 + 2e → Pb + SO42–
-0.35
Ni2+ + 2e→ Ni
-0.26
MnO2 + 2H2O + 4e → Mn(OH)2 + 2OH
-0.05
2H+ + 2e → H2
0.00
Cu2+ + e → Cu+
+0.16
Ag2O + H2O + 2e → 2Ag + 2OH
+0.34
Cu2+ + 2e → Cu
+0.34
O2 + 2H2O + 4e → 4OH
+0.40
2NiOOH + 2H2O + 2e → 2Ni(OH)2 + 2OH
+0.48
NiO2 + 2H2O + 2e → Ni(OH)2 + 2OH
+0.49
MnO42– + 2H2O + 2e → MnO2 + 4OH
+0.62
2AgO + H2O + 2e → Ag2O + 2OH
+0.64
Fe3+ + e → Fe2+
+0.77
Hg2+ + 2e → Hg
+0.80
Ag+ + e → Ag
+0.80
2Hg2+ + 2e → Hg+
+0.91
O2 + 4H+ + 4e → 2H2O
+1.23
ZnO + H2O + 2e → Zn + 2OH
+1.26
Cl2 + 2e → 2Cl
+1.36
PbO2 + 4H+ + 2e → Pb2+ + 2H2O
+1.47
PbO2 + SO42– + 4H+ + 2e → PbSO4 + 2H2O
+1.70
F2 + 2e → 2F
+2.87

Cells using aqueous electrolytes are limited to under 2 V as water is decomposed at higher voltages. Thus Li batteries available in the 2.7 to 4 V use non-aqueous electrolyte. Typical non-aqueous electrolytes have higher impedance unless used as very thin films, eg lithium polymer battery or at higher temperatures.

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