Self-healing in pure tin foil anodes via phase-selective electrochemical prelithiation

Pure tin (Sn) anodes, long hindered by extreme volume expansion and rapid degradation, are revitalized through a voltage-gated, phase-selective electrochemical prelithiation strategy that achieves cycling stability and high areal capacity. By stabilizing the mechanically favorable LiSn intermediate phase while avoiding destructive over-lithiation, this approach suppresses stress buildup and promotes uniform lithiation kinetics. Compared with previously reported prelithiated and non-prelithiated Sn-based foils, the resulting electrodes deliver markedly improved long-term cycling, maintaining excellent capacity retention and near-unity Coulombic efficiency. Microstructural analyses reveal a self-healing, interconnected porous β-LiSn network that forms through the fragmentation and redistribution of the initial β-phase domains generated during prelithiation. This dynamic architecture, absent in Sn alloys, effectively accommodates strain while maintaining continuous ionic and electronic pathways throughout cycling. X-ray photoelectron spectroscopy further reveals the formation of a flexible, organic-rich solid–electrolyte interphase (SEI) on prelithiated Sn, in contrast to the brittle, inorganic-dominated SEI on pristine Sn. The synergy of phase-controlled prelithiation, self-healing microstructure, and tailored interfacial chemistry establishes pure Sn foils as durable, high-energy lithium-ion battery anodes, while providing a broadly applicable design principle for next-generation alloy-based electrodes.