Lithium aluminum alloy anodes in Li-ion rechargeable batteries: past developments, recent progress, and future prospects

Aluminum (Al) metal has long been known to function as an anode in lithium-ion batteries (LIBs) owing to its high capacity, low potential, and effective suppression of dendrite growth. However, seemingly intrinsic degradation during cycling has made it less attractive throughout the years compared to graphitic carbon, silicon-blends, and more recently lithium metal itself. Nevertheless, with the recent unprecedented growth of the LIB industry, this review aims to revisit Al as an anode material, particularly in light of important advancements in understanding the electrochemical Li-Al system, as well as the growth of activity in solid-state batteries where cell designs may conveniently mitigate problems found in traditional liquid cells. Furthermore, this review culminates by highlighting several non-trivial points including: (1) prelithiatied Al anodes, with β-LiAl serving as an intercalation host, can be effectively immortal, depending on formation and cycling conditions; (2) the common knowledge of Al having a capacity of 993 mAh g−1 is inaccurate and attributed to kinetic limitations, thus silicon and lithium should not stand alone as the only ‘high-capacity’ candidates in the roadmap for future lithium-ion cells; (3) replacement of Cu current collectors with Al-based foil anodes may simplify LIB manufacturing and has important safety implications due to the galvanic stability of Al at high potentials vs. Li/Li+. Irrespective of the type of Li-ion device of interest, this review may be useful for those in the broader community to enhance their understanding of general alloy anode behavior, as the methodologies reported here can be extended to non-Al anodes and consequently, even to Na-ion and K-ion devices.