A number of non-rechargeable batteries were first developed with lithium metal as the anode. Commercial coin cells used for today's watch batteries are mostly a lithium chemistry. These systems use a variety of cathode systems that are safe enough for consumer use. The cathodes are made of various materials, such as carbon monoflouride, copper oxide, or vanadium pentoxide. All solid cathode systems are limited in the discharge rate they will support.
To obtain a higher discharge rate, liquid cathode systems were developed. The electrolyte is reactive in these designs and reacts at the porous cathode, which provides catalytic sites and electrical current collection. Several examples of these systems include lithium-thionyl chloride and lithium-sulfur dioxide. These batteries are used in space and for military applications, as well as for emergency beacons on the ground. They are generally not available to the public because they are less safe than the solid cathode systems.
The next step in lithium ion battery technology is believed to be the lithium polymer battery. This battery replaces the liquid electrolyte with either a gelled electrolyte or a true solid electrolyte. These batteries are supposed to be even lighter than lithium ion batteries, but there are currently no plans to fly this technology in space. It is also not commonly available in the commercial market, although it may be just around the corner.
In retrospect, we have come a long way since the leaky flashlight batteries of the sixties, when space flight was born. There is a wide range of solutions available to meet the many demands of space flight, 80 below zero to the high temperatures of a solar fly by. It is possible to handle massive radiation, decades of service, and loads reaching tens of kilowatts. There will be a continued evolution of this technology and a constant striving toward improved batteries.
