Decoupling Mechanical Confinement from Ion-Transport Penalty in Sn Foil Anodes via Al-Phase Topology Regulation

Alloy-type metal foils are attractive anodes for high-energy lithium-ion batteries because they eliminate inactive electrode components while providing high volumetric capacity. However, their practical implementation is hindered by a fundamental transport–mechanics conflict. Uniform alloying reactions require open ion pathways, whereas suppressing large lithiation-induced volume strain demands strong mechanical confinement. Here, we demonstrate that this conflict can be mitigated by regulating the spatial continuity of the Al phase in multilayer Sn foil anodes. In contrast to pure Sn multilayers that undergo severe pulverization and continuous Al/Sn laminates that impose a Li+ transport barrier, a mesh-derived discontinuous Al skeleton embedded in a continuous Sn network simultaneously preserves Li+ accessibility and redistributes alloying-induced stress. The optimized AlmSn-ML anode sustains 430 cycles at 2 mAh cm−2 and 1 mA cm−2, while full cells paired with high-loading LiFePO4 (LFP) cathodes retain 91.51% capacity after 160 cycles. Moreover, AlmSn-ML/Li0.8Co0.1Mn0.1O2 (NCM811) full cells deliver a high volumetric energy density. These findings highlight topology-regulated mechanical reinforcement as an effective strategy for developing low-strain, high-capacity foil anodes.