Lithium arsenate

Lithium Arsenide, Li3As, is formed when a mixture of the elements in suitable proportions is heated to redness, or when lithium arsenate is reduced by heating with charcoal in an electric furnace.8 It is a dark brown crystalline substance of great reactivity. It is attacked by the halogen elements at the ordinary temperature with incandescence. It burns vividly when heated in oxygen it reacts violently with nitric acid, and at a comparatively low temperature it reduces many metallic oxides. 

Lithium Arsenates.—Lithium Orthoarsenate is obtained as the hemihydrate, 2Li3As04.H30, by the action of lithium carbonate on arsenic acid and allowing the solution to crystallise.4 The anhydrous salt is prepared by recrystallising this hydrate from fused lithium chloride 5 rhombic crystals of density 3-07 at 15° C. are obtained. These are soluble in dilute acetic acid they are extremely stable and may be heated to a white heat without fusion. With excess of arsenic acid the normal salt yields deliquescent rhombic prisms of lithium dihydrogen arsenate, 2LiH2As04.3H20, which with water revert to the normal salt.6... 

Lithium arsenide, LigAs.—At the temperature of the electric furnace lithium arsenate is reduced by charcoal to the arsenide, a dark brown crystalline substance of great reactivity.12... 

Reaction 12 is undesired because it involves loss of the additive as a gas. The potential at which this reaction may occur can be calculated from free energy data. For arsenic, the potential of Reaction 12 is 2.90 V vs. lithium. This was confirmed in two tests, one a lithium-sulfur-arsenic cell, the other a lithium-arsenic cell. In the cell containing the sulfur-10 at. % arsenic mixture, a plateau was observed upon charging at 2.95-3.15 V (IR-free with a current density of 20-60 mA/cm2). With the lithium-arsenic cell, the plateau on oxidation was at 2.87 V (IR-free at about 70 mA/cm2). 

Li3As04 LITHIUM ARSENATE 948 MgBrlg] MAGNESIUM MONOBROMIDE (GAS) 996... 

Lithium arsenic fluorine (LiAsFg) has been selected as the substrate material for this battery. 

The cathode is a mixture of CF, with acetylene black and binder such as PTFE. The electrolyte is a 1 1 mixture of dimethoxyethane and propylene carbonate containing IM lithium borotetrafluoride. Alternatively, lithium arsenic hexafluoride in /-butyrolactone has been used. 

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