Breaking the delithiation bottleneck in aluminum-foil anodes for rechargeable lithium batteries by Mn alloying

Aluminum foil anodes are attractive for rechargeable lithium batteries because they combine the functions of active material and current collector. However, once Li is removed from lithiated Al, a Li-depleted Al layer rapidly forms at the surface and impedes further Li extraction from deeper regions; this often forces delithiation to proceed through cracking and pore formation, which accelerates passivation and irreversible capacity loss. Here, we show that Mn alloying resolves this bottleneck. Mn remains dissolved in the fcc-Al matrix and locally hinders Li migration, suppressing the growth of lithiated Al domains to form a refined Al/LiAl microstructure. Simultaneously, Mn mitigates the intrinsic diffusion asymmetry between Li and Al within the LiAl phase. Consequently, the synergy of shortened diffusion distances, numerous grain boundaries acting as fast-transport pathways, and balanced atomic transport enables dense deep delithiation without destructive porous evolution. Ultimately, Al–Mn foil anodes achieve improved cycle life without sacrificing initial Coulombic efficiency, thereby providing an Al-foil-anode design strategy.