Alternative anode materials for lithium-ion batteries: a study of Ag3Sb

Silver antimonide, Ag3Sb, in which silver and antimony are both electrochemically active toward lithium, has been studied as an anode for lithium-ion batteries. The rate of capacity fade on cycling was monitored as a function of the voltage window, which has provided further information about the causes of capacity fade in intermetallic electrode systems. From the voltage profiles, and by comparison with the behavior of SnSb, InSb and Cu2Sb electrodes, the electrochemical reaction of Li/Ag3Sb cells was determined to take place in several discrete stages: first, by a displacement reaction in which lithium replaces Ag in the Ag3Sb structure in a two-step process between 0.9 and 0.7 V to form Li3Sb via Li2AgSb; and second, by reaction of lithium with the extruded silver between 0.2 and 0.0 V to form LixAg compounds (1≤x≤4). The rate of capacity fade that occurs when cells are cycled between 1.2 and 0.0 V was significantly reduced by limiting the reaction to either: (1) the low voltage region (0.7–0.0 V), which provided a stable capacity of not, vert, similar300 mAh/g; or (2) to a wider operating window (1.2–0.1 V, 250 mAh/g), in which the formation of LixAg phases was suppressed.