Page 249 - Lindens Handbook of Batteries

CHAPTER 10

MAGNESIUM AND ALUMINUM
BATTERIES

Patrick J. Spellman

10.1 GENERAL CHARACTERISTICS

Magnesium and aluminum are attractive candidates for use as anode materials in primary batteries. *
As shown in Table 1.1, Chap. 1, they have a high standard potential. Their low atomic weight and
multivalence change result in a high electrochemical equivalence on both a gravimetric and a volu-
metric basis. Further, they are both abundant and relatively inexpensive.
Magnesium has been used successfully in a magnesium/manganese dioxide (Mg/MnO ) battery.
2
This battery has two main advantages over the zinc-carbon battery, namely, twice the service life or
capacity of the zinc battery of equivalent size and the ability to retain this capacity during storage,
even at elevated temperatures (Table 10.1). This excellent storability is due to a protective film that
forms on the surface of the magnesium anode.
Several disadvantages of the magnesium battery are its “voltage delay” and the parasitic cor-
rosion of magnesium that occurs during the discharge once the protective film has been removed,
generating hydrogen and heat. The magnesium battery also loses its excellent storability after
being partially discharged and, hence, is unsatisfactory for long-term intermittent use. For these
reasons, the active (nonreserve) magnesium battery, while used successfully in military applica-
tions, such as radio transceivers and emergency or standby equipment, has not found wide com-
mercial acceptance.
Furthermore, the use of the magnesium battery by the U.S. military has ceased due to upgrades in
military equipment that require higher rate capability than the magnesium system can provide. The
lithium primary and lithium-ion rechargeable batteries are now used.
Aluminum has not been used successfully in an active primary battery despite its potential
advantages. Like magnesium, a protective film forms on the aluminum, which is detrimental to
battery performance, resulting in a battery voltage that is considerably below theoretical and
causing a voltage delay that can be significant for partially discharged batteries or those that have
been stored. While the protective oxide film can be removed by using suitable electrolytes or by
amalgamation, gains by such means are accompanied by accelerated corrosion and poor shelf
life. Aluminum, however, has been more successfully used as an anode in aluminum/air batteries.
(See Chap. 33.)

* The use of magnesium and aluminum in reserve and mechanically rechargeable batteries is covered in Chapters 34 and 33,
respectively.

10.1