Common Capacity Fade Mechanisms of Metal Foil Alloy Anodes with Different Compositions for Lithium Batteries

Metal foils are attractive anode candidates for replacing graphite in lithium-ion batteries, since metal alloys feature high lithium storage capacity and their direct use as foils could avoid slurry coating during manufacturing. Aluminum foil is highly abundant and low-cost, but aluminum foil anodes have generally shown poor cyclability. Here, we fabricate aluminum alloy foils (aluminum–tin, aluminum–zinc, and aluminum–gallium) and examine their electrochemical behavior to understand how composition and microstructure influence cycling performance of metal foil anodes. We show that the addition of alloy components can increase the cycle life of aluminum foil anodes by up to a factor of 2, and both the composition and microstructure of foils influence the cycling capability. We find an approximate power-law dependence of cycle life on the extent of lithiation per cycle for most aluminum-based foils as well as other metal foil compositions, suggesting a common “electrochemical fatigue” degradation mechanism arising from internal porosity formation during alloying/dealloying that governs the behavior of a wide variety of metal foil-based anodes. This understanding, as well as the improved cyclability of the alloy foils, suggests possible pathways to enhance performance of foil anodes for lithium batteries.