Influence of water addition on structural and electrochemical behaviour of liquid ammoniates: A study of LiClO4·4NH 3 ammoniate/H2O mixtures

The ammoniates of lithium perchlorate (LiClO 4 • x NH 3 ) can be used as liquid or solid electrolytes in lithium batteries. The compounds possess a very low ammonia pressure and a large electroactivity range at room temperature. The presence of water in the electrolyte is one of the main problems for the lithium anode. From calorimetric measurements on the water-ammoniate system and an X-ray powder diffraction study on crystalline compounds that appear on lithium dipped in the electrolyte, a maximum water content, x = 0.2, can be derived. Above this limit, the thermodynamic properties of the compounds change and the lithium reacts dramatically with the electrolyte. Electrochemical stability ranges behave, over all the water molar fractions studied, in accordance with structural features.