A thermal battery is a pyrotechnically initiated molten salt primary reserve battery. The electrolyte in a thermal battery is a solid non-conducting inorganic salt at natural ambient temperatures. The electrolyte is rendered molten by a pyrotechnic heat source which is integral to the battery. The battery is activated by either electrical or mechanical methods. The term "thermal battery" does not refer to a single electrochemical system but to a family of batteries using different electrochemical systems or couples. The battery normally uses cell stack type construction.
The electrochemical system of a thermal battery consists of an alkali or alkaline earth metal anode, a fusible inorganic salt electrolyte, and a relatively inert cathode. A pyrotechnic heat source is integrated into the construction of the cell stack.
Thermal batteries are constructed using a variety of different electrochemical systems. Selection of a cell couple system depends upon the requirements of the specific application such as power, volume, weight, operating time, load profile, and voltage regulation. Table 8-1 is a list of some electrochemical couples.
(anode / electrolyte / cathode)
|CELL CHARACTERISTICS AND
| Li(M) / LiCl-KCl /
|Highest capacity thermal cell, low electrical
can operate in severe dynamic environments, long
(up to 1
| Ca / LiCl-KCl /
|Used in applications requiring short activation
| Ca / LiCl-KCl / WO3
2.4 - 2.6
|Used principally for fuze applications where a
level of electrical noise is essential and where
are not severe
| Ca / LiCl-KCl / CaCrO4
2.2 - 2.6
|Used in applications requiring short term
/ LiCl-KCl / V2O5
2.2 - 2.7
|Used in applications requiring short-term
|(1) M refers to