Abstract: A battery adapted to operate at low (typically ambient) temperatures for a short initial period and thereafter at higher temperatures. A Li—Mg alloy anode is provided, including up to 25% magnesium, in a liquid thionyl chloride bath which acts as the cathode. A thin, substantially pure lithium layer is applied to a surface of the Li—Mg anode, preferably of a thickness in the range of 0.0019 to 0.0025 inch to allow obtaining of sufficiently high power and voltage output at lower temperatures for a short period where at such lower temperatures the required voltage and power would not otherwise be available from a Li—Mg anode. Thereafter, the battery may be used in, and exposed to, higher temperatures where at such temperatures the necessary voltage and power from the remaining Li—Mg alloy anode is then available.