From Passive Cocoon to Active Metamorphosis: High-Current-Driven Evolution of Silicon for Ultrastable Anodes.

The commercial viability of silicon anodes in lithium-ion batteries remains heavily impeded by severe volume expansion, unstable solid-electrolyte interphases (SEI), and the necessity for restrictive low-current pre-lithiation. While improving initial Coulombic efficiency (ICE), low-current activation accelerates progressive capacity decay over extended cycling and prevents fast-charging. Furthermore, conventional nanostructuring operates on a paradigm of mere passive containment, leaving root electrochemical instabilities fundamentally unresolved. Inspired by butterfly metamorphosis, we introduce a biomimetic electrochemical paradigm. Analogous to endogenous enzymes driving transformation within a protective cocoon, we employ an initial high current as an "electrochemical enzyme" to trigger the controlled size reduction of Si confined within a covalent organic framework (COF) "cocoon." Regulated by this architecture, the high-current pulse drives controlled Si pulverization, synchronously realizing in situ pre-lithiation and generating a stable amorphous Li-Si phase via a comprehensively elucidated synergistic mechanism. Benefiting from this structural evolution, the engineered anode exhibits superior robustness. It retains 74.5% and 71.9% capacity over 2000 cycles at 10 000 and 20 000 mA g-1, respectively, and successfully accommodates extreme fast charging (118 s). By conceptualizing a transition from passive containment to active in situ regulation, this study unveils a transformative design paradigm for high-energy, high-power battery materials.