2. Batteries (lithium-aluminium)-iron sulfide

The lithium-sulfur couple remains attractive thanks to its high specific energy. Its inherent difficulties have been largely overcome by using a lithium alloy at the anode and a transition metal sulfide at the cathode, the main aim being to have two solid electrodes framing a molten salt. This naturally results in a reduction in specific energy compared with the Li/S pair. Alloys of lithium and aluminum, or silicon, elaborated in the form of a porous solid structure, have proved to be electrochemically reversible negative materials, while among the transition metal sulfides, those of iron, FeS and FeS ₂ lead to interesting performances, both technically and in terms of price. The simplest cell is described by the formula : $\text{Li}-\text{Al}\left(\text{s}\right)|\text{LiCl}-\text{KCl}($